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HomeMy WebLinkAbout127_Whites_Path_Stormwater_ReportSouth Yarmouth LNG Project South Yarmouth, Massachusetts STORMWATER MANAGEMENT REPORT December 2025 A 100% Recyclable Co CONTENTS Tighe&Bond Section 1 Registered Professional Engineer's Certification Section 2 Project Description 2.1 Project Introduction........................................................................2-1 2.2 Existing Conditions.........................................................................2-1 2.3 Floodplain Management..................................................................2-3 2.4 Proposed Improvements.................................................................2-3 2.5 Method of Hydrologic and Hydraulic Analysis.....................................2-4 Section 3 Regulatory Compliance 3.1 LID Measures.................................................................................3-1 3.2 Standard 1: No New Untreated Discharges........................................3-1 3.3 Standard 2: Peak Discharge Rate Attenuation....................................3-1 3.4 Standard 3: Groundwater Recharge..................................................3-2 3.5 Standard 4: Water Quality...............................................................3-3 3.6 Standard 5: Land Uses with Higher Potential Pollutant Loads (LUHPPLs)3-4 3.7 Standard 6: Critical Areas...............................................................3-4 3.8 Standard 7: Redevelopment Projects................................................3-5 3.9 Standard 8: Construction Period Pollution Prevention, Erosion and Sedimentation Control....................................................................3-5 3.10 Standard 9: Long -Term Operation and Maintenance Plan ....................3-5 3.11 Standard 10: Prohibition of Illicit Discharges.....................................3-5 3.12 Local Stormwater Management Regulations......................................3-5 South Yarmouth LNG Project Stormwater Management Report Tighe&Bond Appendices A Massachusetts Stormwater Checklist B Figures C NRCS Soils Information, Geotechnical Report, High Groundwater Computation Sheet, and USGS Surficial Geologic Map D Stormwater Calculations E Construction Period Soil Erosion and Sediment Control Plan F Long -Term Pollution Prevention and Stormwater Operation and Maintenance Plan G Illicit Discharge Compliance Statement Figures 1 Site Location Map 2 Priority Resource Map 3 Aerial Photograph 4 Existing Conditions Drainage Area Map 5 Proposed Conditions Drainage Area Map 6 National Flood Hazard Layer FIRMette Tables 2.1 Soil Descriptions 2.2 Design Rainfall Depths 3.1 Stormwater Discharge Velocity Summary 3.2 Peak Discharge Rate Comparison 3.3 Total Runoff Volume Comparison 3.4 Recharge and Water Quality Volume Summary Table J:\C\C5200 CH-IV\South Yarmouth LNG - 001\Permitting\Stormwater\Narrative\Stormwater Report Narrative.docx South Yarmouth LNG Project Stormwater Management Report SECTION 1 Section 1 Registered Professional Engineer's Certification I have reviewed the Stormwater Report, including the computations, published and site - specific soil information, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan, the Long-term Post -Construction Operation and Maintenance Plan and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Massachusetts Department of Environmental Protection (MassDEP) Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist, provided in Appendix A, is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Alq��= TIMOTHY J Z GRAC£, CIVIL .mow No. 56050 Registered Professional Engineer Block and Signature to t! oil S nature, Date South Yarmouth LNG Project Stormwater Management Report 1-1 SECTION 2 Tighe&Bond Section 2 Project Description 2.1 Project Introduction On behalf of National Grid, Tighe & Bond has prepared the following Stormwater Management Report to support local permitting efforts for the South Yarmouth Liquified Natural Gas (LNG) Project located at 127 Whites Path in South Yarmouth, Massachusetts. The Town of Yarmouth maintains Stormwater Management Regulations that specify the required stormwater management procedures, and which require that proposed construction activities resulting in land disturbance of one acre or more to obtain a Stormwater Management Permit (SMP) from the Conservation Commission. This report has been prepared to document how the project complies with the Town's Regulations and the Massachusetts Stormwater Handbook. The project site is on the east side of the facility, and has an existing LNG tank and associated infrastructure, gravel vehicle paths, and an impoundment around the tank to contain LNG in the event of a leak. There is also an existing stormwater management system that collects runoff from the developed portion of the site and outlets it to a natural depression in the woods to the South. The proposed project includes the construction of a new LNG tank and associated infrastructure, and a Stormwater management system to mitigate runoff from the new impervious areas that will be generated by the project. The existing tank will remain online until the new tank is constructed and commissioned, at which point the existing tank will be demolished and removed. The drainage improvements associated with the new stormwater management system include trench drains, drainage swales, catch basins, drain manholes, and stormwater treatment structures to collect, pre- treat, and convey runoff away from the infrastructure and into the proposed stormwater infiltration basin. A United States Geological Survey (USGS) Site Location figure, Aerial Photograph, and Priority Resource figure of the Project site are provided in Appendix B as Figures 1-3, respectively. Project plans are provided separately. 2.2 Existing Conditions The Facility is located south of Rt. 6 in South Yarmouth within the Business 3 (B3) zoning district. The Project Site is on the east side of the facility, in a minimally developed area that currently consists of an LNG tank and associated infrastructure, gravel vehicle paths, and an impoundment. Under existing conditions, stormwater runoff from the project area flows to the West, where it is collected in a series of catch basins located in the paved access roads. The existing system does not include any pretreatment, and once collected, the runoff is discharged in a basin on the southern edge of the facility. The Natural Resources Conservation Service (NRCS) soil data was obtained through the Web Soil Survey portal on the United States Department of Agriculture (USDA) NRCS website. Soils within the project area, as published in the USDA Soil Survey for Barnstable County, Version 24, dated September 5, 2025, include Urban Land and Carver Coarse South Yarmouth LNG Project Stormwater Management Report 2-1 Tighe&Bond Sand. The NRCS Soils Mapping is provided in Appendix C. The hydrologic soil group (HSG) and further description for each soil association are presented in Table 2.1 below. Table 2.1 Soil Descriptions Soil Map Soil Name Hydrologic Soil Designation Group (HSG) 252A Carver coarse sand, 0 to 3 percent A slopes 252E Carver coarse sand, 3 to 8 percent A slopes 602 Urban Land N/A The hydrologic soil group designation (HSG) for this soil type is listed as A. The HSG rating for soil types is based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long duration storms. Soils designated as HSG A are generally well draining and have a high capacity for water infiltration. Based on this, soils within the project area are consistent in their ability to infiltrate water and in the development of runoff. The NRCS Soils Mapping and USGS superficial geologic mapping is provided in Appendix C. Several borings were completed on March 20,2023 to confirm the soil characteristics and determine ground water levels. The results of the exploration program confirm USDA soils data and USGS surficial geologic information provided in Appendix C. The depth to groundwater on the day of borings ranged from 19.5 feet to 26.0 feet. For this analysis, the 19.5-foot reading will be used as the basis for calculations since it is most conservative. Several borings were completed on March 20,2023 that confirm soil characteristics and determined ground water levels. The depth to groundwater on the day of borings ranged from 19.5 feet to 26.0 feet below finish grade. For this analysis, the 19.5-foot reading will be used as the basis for calculations since it is most conservative. As per Section 2.4(1)(K) of the Town's Stormwater Management Regulations, the seasonal high groundwater elevation was determined using the Cape Cod Commission adjustment method specified in Technical Bulletin 92-001. The nearest Cape Cod Index Well is A1W- 247R, and the Cape Cod Commission's Index Well Readings as of March 22, 2023 shows a groundwater level of 19.67 feet below finish grade. The Table of Potential Water Level Rise for Index Well A1W-247R begins at 21.9 feet, which is closest to the 19.5-foot depth to groundwater on the day of explorations - indicating that an adjustment of 0 feet is appropriate. Therefore, a groundwater depth of 19.5 feet will be used in the design of the infiltration basin. The borings were completed at existing elevation 36, which puts the seasonal high groundwater at elevation 16.5. The hydraulic calculations included in this report have been completed using the groundwater information previously specified, and with the soil data from the USGS; and surficial geologic mapping from USGS, which will be confirmed with additional soil explorations that will be completed during construction. The Stormwater Infiltration Data Report from the borings is also provided in Appendix C. South Yarmouth LNG Project Stormwater Management Report 2-2 Tighe&Bond The runoff curve numbers (CN) used in the calculation of the composite CN for each drainage area is based on the values provided in TR-55, Urban Hydrology for Small Watersheds. CN values vary depending on the type of ground cover and soil HSG. Existing Conditions Drainage Areas were delineated based on topography and stormwater discharge location. A summary of each existing conditions drainage area, including sizing, CN and time of concentration calculations, are provided in the HydroCAD reports in Appendix D. An Existing Conditions Drainage Area Map is provided as Figure 4 in Appendix B. 2.3 Floodplain Management The Federal Emergency Management Agency's Flood Insurance Rate Map (FIRM) Community Panel Number 25001C0579J, effective July 16, 2014 shows the project site outside of any floodways or floodplains, as attached in Appendix B. Therefore, no floodplain is identified on this site. 2.4 Proposed Improvements The proposed project includes site clearing, regrading, and tree removal. It also includes the construction of a new LNG tank adjacent to the existing tank and associated infrastructure; as well as the construction of a new paved access road around the perimeter, new fencing in various locations, and a stormwater management system. The stormwater management system includes catch basins, trench drains, drain manholes, stormwater treatment units, sediment forebays and an infiltration basin. The design has been prepared in accordance with the Town's Stormwater Management Regulations, and the recommendations in the Massachusetts Department of Environmental Protection (MassDEP) Stormwater Handbook. Under proposed conditions, all of the stormwater runoff from the project area is collected and treated within the new stormwater management system. The new system is hydrologically disconnected from the existing system and no runoff from the redevelopment area will enter the existing stormwater system. Stormwater runoff from the new development generally flows to the south, where it is collected in catch basins, trench drains, or directly into a series of sediment forebays. Runoff entering the catch basins will flow through a series of drain manholes and a Water Quality Treatment Unit, otherwise it will flow into the sediment forebays for pretreatment. The site is located within the Aquifer Protection Overlay district, which will require that the proposed stormwater system achieve pretreatment of 44% Total Suspended Solids (TSS) removal prior to infiltration. All runoff from impervious vehicular areas will achieve the required 44% pretreatment before entering the basin for infiltration, and the basin has been sized to retain the volume of 1 inch per acre of impervious coverage. A summary of each proposed condition drainage area, including sizing, RCN and time of concentration calculations, are provided in the HydroCAD reports in Appendix D. A Proposed Conditions Drainage Area Map is provided as Figure 5 in Appendix B. The proposed stormwater management system treats both the quality and the quantity of stormwater discharge from the site. The system includes best management practices (BMP's) such as deep -sump, hooded catch basins, trench drains, drain manholes, a proprietary stormwater treatment unit, two sediment forebays, and an infiltration basin. South Yarmouth LNG Project Stormwater Management Report 2-3 Tighe&Bond A brief description of the proposed Best Management Practices incorporated into the stormwater management system are as follows: Deep -Sump, Hooded Catch Basins: Catch basins provided throughout the site collect stormwater runoff from the proposed vehicular areas and are connected to the project's stormwater collection system. The deep -sump and hooded outlet provide runoff an opportunity to separate from solids and floatable pollutants prior to discharge and are used as a pretreatment device throughout the project. Proprietary Treatment Devices: Structural stormwater treatment device, proposed as Stormceptor STC450i, is designed to mechanically separate pollutants from stormwater flows through centrifugal force and vortex separation. A unit is proposed at the end of the treatment train in the stormwater management system, prior to discharging into the infiltration basin. Each unit has been sized in accordance with guidance provided by MassDEP to ensure proper sediment removal efficiencies. Infiltration Basin: The proposed surface infiltration basin is the collection point for all runoff from the project and is located in the south area of the site. The infiltration basin has been designed in accordance with the Massachusetts Stormwater Handbook to provide the required groundwater recharge and water quality volume for the project. The basin is equipped with an emergency overflow spillway to minimize the potential for flooding during extreme storm events. Trench Drain: The proposed trench drains have been designed to accept untreated stormwater runoff from the site and convey it to either a series of sediment forebays or directly to the infiltration basin. 2.5 Method of Hydrologic and Hydraulic Analysis The following storm drainage design criteria were used in the hydrologic and hydraulic analyses: 1. Piped storm drainage system and the outlets are designed for a 25-year storm event. 2. Minimum time of concentration = 6 minutes. 3. For SCS peak flow calculations, Curve Number were as follows: a. >75% Grass Cover, Good (HSG A) = 39 b. Gravel Surface (HSG A) = 96 c. Paved Parking (HSG A) = 98 d. Woods, Good (HSG A) = 30 4. Minimum diameter pipes, excluding roof leaders, underdrains and foundation drains = 12 inches 5. Minimum pipe slope = 0.5 percent 6. Watershed areas delineated using polylines in AutoCAD Civil 3D 2025. South Yarmouth LNG Project Stormwater Management Report 2-4 Tighe&Bond 7. The storm water management plan for the site is designed to treat the water quality volume, remove total suspended solids and infiltrate the required recharge volume while reducing peak flow. 8. Comparative hydrology analyzed using HydroCAD Stormwater Modeling software Version 10.20-4c. A comparative hydrologic analysis of the pre -development and post -development site was performed to determine the impacts of the proposed project to peak discharge rates and stormwater runoff volumes. HydroCAD Release 10.20-4c is a hydrology and hydraulics software using Technical Release (TR) 20 and TR-55 methodologies for the determination of stormwater runoff quantities. The HydroCAD Report for both pre- and post - development conditions for each storm event is provided in Appendix D. Table 2.2 below presents the design rainfall depths for the storm events evaluated, as provided by the National Oceanic and Atmospheric Administration's (NOAA) National Weather Service Atlas 14 PLUS. Table 2.2 Design Rainfall Depths Storm Event Rainfall Depth (inches) 1-Year 2.84 2-Year 3.35 5-Year 4.18 10-Year 4.87 25-Year 5.82 50-Year 6.54 100-Year 7.28 The proposed storm drain collection system was analyzed to ensure that the pipe capacities proposed can accommodate the 25-year storm event, as well as meeting minimum and maximum flow velocity. Results of that analysis are provided in Appendix D. South Yarmouth LNG Project Stormwater Management Report 2-5 SECTION 3 Tighe&Bond Section 3 Regulatory Compliance The project is required to comply with the ten MassDEP Massachusetts Stormwater Management Standards (Standards) under the Massachusetts Wetlands Protection Act and the Town of Yarmouth Stormwater Regulations. The Massachusetts Stormwater Checklist is provided in Appendix A. 3.1 LID Measures MassDEP allows for reductions in structural stormwater Best Management Practice (BMP) requirements for water quantity and quality when certain criteria are met. The proposed project includes environmentally sensitive site design and low impact development techniques; however, the applicant is not requesting credit for LID measures. 3.2 Standard 1: No New Untreated Discharges The project will not result in any new stormwater conveyance discharging untreated stormwater directly to the Waters of the Commonwealth. Further documentation pertaining to stormwater treatment is provided in Section 3.5. It is not anticipated that erosive stormwater velocities will be encountered post - construction subsequently causing erosion and siltation to Waters of the Commonwealth. All discharges have been designed to meet the thresholds identified in Volume 3 of the Massachusetts Stormwater Handbook. A summary of stormwater discharge velocities for the 2-year, 24-hour storm event are provided in Table 3.1, below, accompanied by permissible velocities as provided by MassDEP. Table 3.1 Stormwater Discharqe Velocities 2-year Storm 2-Year Storm Maximum Discharge Location Event cfs Event Velocity Permissible ( ) (fps) Velocity (fps)' Infiltration Basin - 0.00 0.00 3.0 Emeraencv SDillwav 1 Maximum Permissible Velocity is based on Table 2.3.1 of Volume 3 of the MassDEP Stormwater Handbook for slopes greater than 10%. All outfalls will be equipped with stone outlet protection as shown on the Site Plans. These devices are designed based on the anticipated flow from each outfall to dissipate energy and reduce the opportunity for erosion to develop. 3.3 Standard 2: Peak Discharge Rate Attenuation Since the proposed project alters existing drainage patterns, stormwater management features are required to attenuate peak discharge rates through the use of infiltration and detention. Runoff is collected in catch basins, trench drains, or directly flows into a series of sediment forebays and conveyed into the infiltration basin where runoff is infiltrated. South Yarmouth LNG Project Stormwater Management Report 3-1 Tighe&Bond Table 3.2 presents the results of the pre -development stormwater runoff analysis versus the post -development stormwater runoff analysis, previously described in Section 2.5, for the project. Table 3.2 Peak Discharge Rate Comparison 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year Storm Storm Storm Storm Storm Storm Event Event Event Event Event Event (cfs) (cfs) (cfs) (cfs) (cfs) (cfs) Design Existing 0.46 1.68 3.20 5.90 8.28 10.96 Point 1 Proposed 0.00 0.00 0.00 0.00 0.00 0.00 Table 3.2 indicates that existing peak discharge rates for the project and at each individual Design Point, are reduced for all storm events. In addition to a summary of peak discharge rates, total runoff volumes are also presented in Table 3.3. Table 3.3 Total Runoff Volume Comparison 2-Year 5-Year 10-Year 25-Year 50-Year 100-Year Storm Storm Storm Storm Storm Storm Event Event Event Event Event Event (acre-ft) (acre-ft) (acre-ft) (acre-ft) (acre-ft) (acre-ft) Design Existing 0.124 0.291 0.470 0.776 1.023 1.311 Point 1 Proposed 0.00 0.00 0.00 0.00 0.00 0.00 3.4 Standard 3: Groundwater Recharge The proposed project will allow treated stormwater runoff from the proposed project to infiltrate to groundwater. The infiltration systems have been designed in accordance with the MassDEP Stormwater Handbook and provide the required recharge volume. Infiltration Basin: For Class A Soils: F = Target Depth Factor = 1 inch Total Impervious Area = 0.34 acres Contributing Impervious Area = 0.34 acres Rv0 = F * Impervious Area = z 0.34 acres * tin * 1 f t * 43560 f t = 1,234 f t3 = Required Recharge Volume 12' acre Total Required Recharge Volume = 1,234 ft3 Groundwater Recharge Time and Drawdown: South Yarmouth LNG Project Stormwater Management Report 3-2 Tighe&Bond Infiltration Basin: — VS TIME Drawdown — (K)(Bottom Area) Vs = Storage Volume = 45,794 ft3 K = 0.69 ft/hr (8.27 in/hr Rawls Rate) Bottom Area = 5,616 ft2 at elev. 27.00' 45,794 f t3 TIMEDrawdown = (0.69 f t/hr)(5,616 f t2) — 11.8 hr 3.5 Standard 4: Water Quality Standard 4 of the Massachusetts Stormwater Standards addresses stormwater quality requirements. This standard requires that new stormwater management systems be designed to achieve an 80% Total Suspended Solids (TSS) removal rate prior to discharge. MassDEP has published presumed removal rates for each of the BMP's featured in their design guidelines. Additionally, this standard addresses the required volume of stormwater runoff that is to be treated by the BMPs, as well as components of a long-term source control and pollution prevention plan. The following treatment trains have been incorporated into the design of the stormwater management system: Treatment Train 1: This treatment train consists of deep -sump, hooded catch basins, proprietary water quality treatment device and an infiltration basin. The pretreatment requirement of 44% TSS removal prior to infiltration is met through the pretreatment features of this train. The overall TSS removal for this train is 80%. Treatment Train 2: This treatment train consists of a series of sediment forebays and an infiltration basin. The pretreatment requirement of 44% TSS removal prior to infiltration is met through the pretreatment features of this train. The overall TSS removal for this train is 80%. The project has been designed such that all proposed impervious and gravel surfaces pass through one of the previously described treatment trains, which results in the required TSS removal for the project. Required Water Quality Volume (Standard 4): The project requires a Water Quality Depth = 1" Infiltration Basin: Total Impervious Required to be treated = 0.34 acres z VwQ = DwQ * Impervious Area = 1" *� 1 Prr * 0.34 acres * 43s6o fr = 1,234 f t3 12" acre Total Required Water Quality Volume = 1,234 ft3 Target Volume: South Yarmouth LNG Project Stormwater Management Report 3-3 Tighe&Bond Target Volume is defined as the larger of Required Recharge Volume and Required Water Quality Volume. Therefore, Target Volume = 1,234 ft3 (Required Water Quality Volume). Sediment forebays, and an infiltration basin provide water quality volumes and are summarized in the following table. Table 3.4 Recharge and Water Quality Volume Summary Table Area, Structure Reference Provided Recharge Volume (cf) Provided Water Quality Volume (cf) Sediment Forebay 1 N/A 1,644 Sediment Forebay 2 N/A 1,337 Infiltration Basin 78,273 78,273 Total Volume Provided 78,273 81,254 Volume Required 1,234 1,234 All volumes calculated are below the elevation of the outlet. See Hydro CAD Report for stage -storage tables. 3.6 Standard 5: Land Uses with Higher Potential Pollutant Loads (LUHPPLs) The proposed use is not considered a LUHPPL. Therefore, compliance with the additional requirements of Standard 5 is not required. 3.7 Standard 6: Critical Areas The project has been designed to improve water quality and quantity under proposed conditions. The stormwater BMPs selected for the project remove 90% of annual average TSS loading when constructed and maintained properly. Refer to Appendix D for pollutant removal calculations. The project is located within a Zone II MassDEP Wellhead Protection Areas and therefore requires a 44% pretreatment for any impervious surfaces. The project has been designed to improve water quality and quantity under proposed conditions. The stormwater BMPs selected for the project remove 90% of annual average TSS loading, as well as 60% of total phosphorus and 100% of total nitrogen when constructed and maintained properly. The infiltration basin is sized to fully infiltrate the 100-year storm, and TSS and nutrient removal requirements are met. Other Critical Areas, as defined in the Massachusetts Stormwater Handbook, are shown on Figure 2 in Appendix B. South Yarmouth LNG Project Stormwater Management Report 3-4 Tighe&Bond 3.8 Standard 7: Redevelopment Projects The project is considered a mix of new development and redevelopment; however, the project has been designed to fully comply with all the Standards. 3.9 Standard 8: Construction Period Pollution Prevention, Erosion and Sedimentation Control A construction period Soil Erosion and Sediment Control Plan (SESCP) is provided in Appendix E. The SESCP presents the minimum soil erosion and sediment control practices to be used during construction. General soil erosion and sedimentation control BMPs are indicated on the Site Plans. Additionally, there will be more than one acre of land disturbed as a result of this project, therefore the construction will be required to comply with the Environmental Policy Act (EPA) National Pollutant Discharge Elimination System (NPDES) Construction General Permit (CGP). Coverage under the CGP will be obtained before construction commenced by the Contractor. The Contractor will be required file a Notice of Intent with the EPA and to implement a Stormwater Pollution Prevention Plan (SWPPP) prior to construction. A SWPPP was not prepared as part of this report. 3.10 Standard 9: Long -Term Operation and Maintenance Plan A Long -Term Stormwater Operations and Maintenance Plan is included in Appendix F of this report. The O&M plan indicates the responsible parties for the project, routine and non -routine maintenance tasks and inspection criteria. The O&M Plan also provides guidance on long-term pollution prevention practices for the project. 3.11 Standard 10: Prohibition of Illicit Discharges Illicit discharges to the stormwater management system are discharges that are not entirely comprised of stormwater. Illicit discharge does not include discharges from the following activities or facilities: firefighting, water line flushing, landscape irrigation, uncontaminated groundwater, potable water sources, foundation drains, air conditioning condensation, footing drains, individual resident car washing, flows from riparian habitats and wetlands, dechlorinated water from swimming pools, water used for street washing, and water used to clean residential buildings without detergents. A signed Illicit Discharge Statement is provided in Appendix G. 3.12 Local Stormwater Management Regulations South Yarmouth Stormwater Management Performance Standards, Projects shall meet the following Performance Standards: (1) Low Impact Development (LID) site planning and design strategies must be implemented unless infeasible in order to reduce the discharge of stormwater from development sites. Reduce the amount of runoff over paved surfaces through the implementation of LID techniques, such as infiltrating roof runoff at the source, South Yarmouth LNG Project Stormwater Management Report 3-5 Tighe&Bond planting large canopy trees over impervious areas to intercept rainfall, use of porous paving materials, etc. where feasible. The applicant must document in writing why LID strategies are not appropriate when not used to manage stormwater. Low Impact Development (LID) strategies have been implemented to the maximum extent practicable for this industrial site. The stormwater management system includes LID measures like sediment forebays and an infiltration basin and has been designed to mitigate and infiltrate the 100-year storm event. (2) Good housekeeping procedures shall be used to reduce sources of sediment, phosphorus, nitrogen and other contaminants in stormwater runoff. These shall be documented in the Operation and Maintenance Plan and must include: (a) Wash vehicles at commercial car washes or on lawns or pervious areas using biodegradable and phosphate free detergent; (b) Removal of sediment, leaf litter and other organic debris from impervious surfaces a minimum of twice a year in the spring (after snowmelt) and fall (after leaf fall); (c) Removal of sediment/debris from catch basin structures a minimum of once a yea r; (d) Restrictions on the application of fertilizers, including: i. Fertilizer shall not be applied during or immediately prior to heavy rainfall, such as but not limited to thunderstorms, hurricanes, or northeastern storms, or when the soil is saturated due to intense or extended rainfall; ii. Fertilizer shall not be applied between November 12 and the following March 31; iii. Fertilizer shall not be applied, spilled or deposited on impervious surfaces or in a manner that allows it to enter into storm drains; iv. Fertilizer shall not be applied within 100 feet of any surface water or within the Zone I of a public drinking water well; v. Fertilizer containing phosphorus shall not be applied unless a soil test taken not more than three years before the proposed fertilizer application indicates that additional phosphorus is needed for growth of that turf, or unless establishing new turf or reestablishing or repairing turf after substantial damage or land disturbance; vi. A single application of fertilizer that contains nitrogen shall not exceed 1.0 pound of nitrogen per 1,000 square feet, shall consist of at least 20% slow -release nitrogen (SRN) fertilizer (NOTE: This represents the minimum percentage: use of higher SRN content is generally preferable, especially on sandy root zones, during stress and pre -stress periods, and when there are fewer annual applications of nitrogen made to a lawn) and the annual rate shall not exceed 3.2 pounds of actual nitrogen per thousand square South Yarmouth LNG Project Stormwater Management Report 3-6 Tighe&Bond feet. Single applications shall be done at intervals of no less than four weeks until the annual maximum is reached; vii. Grass clippings, leaves, or any other vegetative debris shall not be deposited into or within 50 feet of water bodies, retention and detention areas, drainage ditches or stormwater drains, or onto impervious surfaces, such as, but not limited to, roadways and sidewalks, except during scheduled clean -upprograms; and (e) Provide for routine inspection (at least annually) and maintenance of structural BMPs to remove sediment and debris. See the O & M plan in Appendix F. (3) Stormwater management systems design shall be consistent with, or more stringent than, the requirements of the 2008 Massachusetts Stormwater Handbook (as amended) with the following additional requirements: (a) Post -development peak discharge rates do not exceed pre -development peak discharge rates for the 2, 10, 25, 50 and 100-year 24-hour storms. The 50-year post -development stormwater volume shall be retained onsite through design of the stormwater management system to the maximum extent practicable. The 100- year post -development stormwater volume shall be controlled onsite with no offsite discharge to the maximum extent practicable. This Standard may be waived for discharges to land subject to coastal storm flowage as defined in the Massachusetts Wetlands Protection Regulations at 310 CMR 10.04. (b) Structural pretreatment is required for all proposed infiltration devices to remove 44% TSS from runoff before it enters the infiltration device. Runoff from non-metal roofs may be infiltrated without pretreatment. Runoff from metal roofs may be infiltrated without pretreatment only if the roof is located outside the Zone II or Interim Wellhead Protection Area of a public water supply and outside an industrial site, otherwise, pretreatment is required as specified in the Stormwater Management Handbook. (c) The calculations of runoff volumes and peak rates required under Massachusetts Stormwater Management Standard 2 shall be based on precipitation data provided in National Oceanic and Atmospheric Administration (NOAA) - National Weather Service "NOAA Atlas 14" unless otherwise authorized by the Commission. See Section 3 for information that documents compliance with this requirement. (4) Stormwater management systems for new developments shall be designed to meet an average annual pollutant removal equivalent to 90% of the average annual load of TSS AND 60% of the average annual load of Total Phosphorus (TP) AND 30% of average annual load of Total Nitrogen (TN) related to the total post -construction impervious area on the site as achieved through one of the following methods: (a) Installing BMPs that meet the pollutant removal percentages. Pollutant removal shall be determined as required in Paragraph (6) below; or South Yarmouth LNG Project Stormwater Management Report 3-7 Tighe&Bond (b) Retaining the volume of runoff equivalent to, or greater than one (1.0) inch multiplied by the total post -construction impervious surface area on the new development site, with pretreatment provided in accordance with Section 2.05(3)(b); or (c) Meeting a combination of retention and treatment that achieves the above standards; or (d) Utilizing offsite mitigation that meets the above standards within the same USGS HUC12 as the new development site. Offsite mitigation can only be proposed for projects that cannot meet 100% of the infiltration and/or treatment goals due to specific site constraints. Examples when offsite mitigation may be proposed include: impermeable or low permeable soils; high groundwater; site with higher pollutant loads. Despite being a re -development project, the stormwater design meets the requirement above for new development by capturing and retaining all of the proposed runoff from the site. (5) Stormwater management systems for redevelopments shall be designed to meet an average annual pollutant removal equivalent to 80% of the average annual post construction load of TSS AND 50% of the average annual load of TP AND 30% of the average annual load of TN related to the total post -construction impervious area on the site as achieved through one of the following methods: (a) Installing BMPs that meet the pollutant removal percentages. Pollutant removal shall be determined as required in Paragraph (6) below; or (b) Retaining the volume of runoff equivalent to, or greater than, 0.8 inch multiplied by the total post -construction impervious surface area on the redeveloped site, with pretreatment provided in accordance with Section 2.05(3)(b); or (c) Meeting a combination of retention and treatment that achieves the above standards; or (d) Utilizing offsite mitigation that meets the above standards within the same USGS HUC10 as the redevelopment site. Offsite mitigation can only be proposed for projects that cannot meet 100% of the infiltration and/or treatment goals due to specific site constraints. Examples when offsite mitigation may be proposed include: impermeable or low permeable soils; high groundwater; site with higher pollutant loads. (e) Redevelopment activities that are exclusively limited to maintenance and improvement of existing roadways, (including widening less than a single lane, adding shoulders, correcting substandard intersections, improving existing drainage systems, and repaving projects) shall improve existing conditions unless infeasible and are exempt from Paragraphs (5)(a) through (5)(c) above. Roadway widening or improvements that increase the amount of impervious area on the redevelopment site by greater than or equal to a single lane width shall meet the requirements of Paragraphs (5)(a) through (5)(c) fully. South Yarmouth LNG Project Stormwater Management Report 3-8 Tighe&Bond The stormwater design meets the requirement above for new development by capturing and retaining all of the proposed runoff from the site. (6) In complying with (4) and (5) above, the required removal percentage is not required for each storm; it is the average removal over a year that is required. Pollutant removal shall be calculated consistent with EPA Region 1's BMP Accounting and Tracking Tool (2016) (https://www.epa.gov/npdes-permits/stormwater-tools-new-england)or other BMP performance evaluation tool provided by EPA Region 1 where available. If EPA Region 1 tools do not address the planned or installed BMP performance any federally or State approved BMP design guidance or performance standards (e.g. State stormwater handbooks and design guidance manuals) may be used to calculate BMP performance. See Appendix D for Stormwater TSS removal calculations that comply with this standard. The basin is designed to retain and infiltrate the 100-year storm. Complete infiltration of the 100-year storm greatly exceeds the required infiltration rates required. (7) Discharges to water bodies or their tributaries subject to one or more approved Total Maximum Daily Load (TMDL) or impaired waterbodies and their tributaries, listed as Category 4b or 5 in the current Massachusetts Integrated List of Waters listed pursuant to the Federal Clean Water Act Sections 303(d) and 305(b) without an EPA approved TMDL shall adhere to the following: (a) To the extent that a new development or redevelopment project will discharge to a water body or its tributaries subject to one or more pollutant -specific TMDLs, the project shall implement structural and non-structural stormwater best management practices (BMPs) that are consistent with each such TMDL. (b) For any new development or redevelopment project that discharges stormwater to a water body subject to a Nitrogen TMDL, the stormwater management system shall be designed using BMPs optimized for nitrogen removal. (c) For a new development or redevelopment project that discharges stormwater to a waterbody identified as impaired due to phosphorus, the stormwater management system shall be designed using BMPs optimized for phosphorus removal. (d) For a new development or redevelopment project that discharges stormwater to a waterbody identified as impaired due to chloride, the applicant shall include measures in the required Operation and Maintenance (O&M) Plan to minimize salt usage or use alternative deicing materials and practices. The applicant shall consult with the Yarmouth Department of Public Works to develop these O&M provisions. (e) For a new development or redevelopment project that is a commercial or industrial land use and discharges stormwater to a waterbody identified as impaired due to solids, metals, or oil and grease (hydrocarbons). The following shall apply: i. The stormwater management system shall be designed to allow shutdown and containment in the event of an emergency spill or other unexpected event; South Yarmouth LNG Project Stormwater Management Report 3-9 Tighe&Bond ii. Any stormwater management system designed to infiltrate stormwater shall provide the level of pollutant removal equal to or greater than the level of pollutant removal provided through the use of biofiltration of the same volume of runoff to be infiltrated, prior to infiltration. The Project site does not discharge to any water bodies or tributaries. South Yarmouth LNG Project Stormwater Management Report 3-10 APPENDIX A Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report A. Introduction Important: When A Stormwater Report must be submitted with the Notice of Intent permit application to document filling out forms compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for on the computer, Report (which hih should t e Stormwater e wcsouprovide more substantive and detailed information but is offered use only the tab the p p ) key to move your here as a tool to help the applicant organize their Stormwater Management documentation for their cursor - do not Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, use the return the Stormwater Report must contain the engineering computations and supporting information set forth in key. Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and , r_� certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. ��V The Stormwater Report must include: • The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals.' This Checklist is to be used as the cover for the completed Stormwater Report. • Applicant/Project Name • Project Address • Name of Firm and Registered Professional Engineer that prepared the Report • Long -Term Pollution Prevention Plan required by Standards 4-6 • Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82 • Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post -construction best management practices. 2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer's Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Long- term Post -Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature OF kAss4 G TIMOTHY J 0RACE ClYL 140. 56050 Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? ❑ New development ❑ Redevelopment ® Mix of New Development and Redevelopment MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 2 of 8 L1Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 1 Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: ❑ No disturbance to any Wetland Resource Areas ❑ Site Design Practices (e.g. clustered development, reduced frontage setbacks) ❑ Reduced Impervious Area (Redevelopment Only) ❑ Minimizing disturbance to existing trees and shrubs ❑ LID Site Design Credit Requested: ❑ Credit 1 ❑ Credit 2 ❑ Credit 3 ❑ Use of "country drainage" versus curb and gutter conveyance and pipe ❑ Bioretention Cells (includes Rain Gardens) ❑ Constructed Stormwater Wetlands (includes Gravel Wetlands designs) ❑ Treebox Filter ❑ Water Quality Swale ❑ Grass Channel ❑ Green Roof ❑ Other (describe): Standard 1: No New Untreated Discharges ❑ No new untreated discharges ❑ Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth ❑ Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8 L1Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 1 Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation ❑ Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. ❑ Evaluation provided to determine whether off -site flooding increases during the 100-year 24-hour storm. ® Calculations provided to show that post -development peak discharge rates do not exceed pre - development rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off -site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post -development peak discharge rates do not exceed pre -development rates for the 100-year 24- hour storm. Standard 3: Recharge ® Soil Analysis provided. ® Required Recharge Volume calculation provided. ❑ Required Recharge volume reduced through use of the LID site Design Credits. ❑ Sizing the infiltration, BMPs is based on the following method: Check the method used. ❑ Static ® Simple Dynamic ❑ Dynamic Field' ❑ Runoff from all impervious areas at the site discharging to the infiltration BMP. ❑ Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. ® Recharge BMPs have been sized to infiltrate the Required Recharge Volume. ❑ Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: ❑ Site is comprised solely of C and D soils and/or bedrock at the land surface ❑ M.G.L. c. 21 E sites pursuant to 310 CMR 40.0000 ❑ Solid Waste Landfill pursuant to 310 CMR 19.000 ❑ Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. ❑ Calculations showing that the infiltration BMPs will drain in 72 hours are provided. ❑ Property includes a M.G.L. c. 21 E site or a solid waste landfill and a mounding analysis is included. 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 4 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) ❑ The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10- year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. ❑ Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long -Term Pollution Prevention Plan typically includes the following: • Good housekeeping practices; • Provisions for storing materials and waste products inside or under cover; • Vehicle washing controls; • Requirements for routine inspections and maintenance of stormwater BMPs; • Spill prevention and response plans; • Provisions for maintenance of lawns, gardens, and other landscaped areas; • Requirements for storage and use of fertilizers, herbicides, and pesticides; • Pet waste management provisions; • Provisions for operation and management of septic systems; • Provisions for solid waste management; • Snow disposal and plowing plans relative to Wetland Resource Areas; • Winter Road Salt and/or Sand Use and Storage restrictions; • Street sweeping schedules; • Provisions for prevention of illicit discharges to the stormwater management system; • Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; • Training for staff or personnel involved with implementing Long -Term Pollution Prevention Plan; • List of Emergency contacts for implementing Long -Term Pollution Prevention Plan. ® A Long -Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. ® Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: ® is within the Zone II or Interim Wellhead Protection Area ❑ is near or to other critical areas ® is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) ❑ involves runoff from land uses with higher potential pollutant loads. ❑ The Required Water Quality Volume is reduced through use of the LID site Design Credits. ® Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 5 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) ❑ The BMP is sized (and calculations provided) based on: ❑ The'/2" or 1" Water Quality Volume or ❑ The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. ❑ The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs. ❑ A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) ❑ The NPDES Multi -Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. ❑ The NPDES Multi -Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post -construction stormwater BMPs. ❑ The NPDES Multi -Sector General Permit does not cover the land use. ❑ LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. ❑ All exposure has been eliminated. ❑ All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. ❑ The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas ❑ The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. ❑ Critical areas and BMPs are identified in the Stormwater Report. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 6 of 8 L1Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 1 Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable ® The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: ❑ Limited Project ❑ Small Residential Projects: 5-9 single family houses or 5-9 units in a multi -family development provided there is no discharge that may potentially affect a critical area. ❑ Small Residential Projects: 2-4 single family houses or 2-4 units in a multi -family development with a discharge to a critical area ❑ Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff ❑ Bike Path and/or Foot Path ❑ Redevelopment Project ❑ Redevelopment portion of mix of new and redevelopment. ❑ Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. ❑ The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: • Narrative; • Construction Period Operation and Maintenance Plan; • Names of Persons or Entity Responsible for Plan Compliance; • Construction Period Pollution Prevention Measures; • Erosion and Sedimentation Control Plan Drawings; • Detail drawings and specifications for erosion control BMPs, including sizing calculations; • Vegetation Planning; • Site Development Plan; • Construction Sequencing Plan; • Sequencing of Erosion and Sedimentation Controls; • Operation and Maintenance of Erosion and Sedimentation Controls; • Inspection Schedule; • Maintenance Schedule; • Inspection and Maintenance Log Form. ® A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 7 of 8 L1Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 1 Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) ❑ The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. ❑ The project is not covered by a NPDES Construction General Permit ❑ The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. ® The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan ® The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: ® Name of the stormwater management system owners; ® Party responsible for operation and maintenance; ® Schedule for implementation of routine and non -routine maintenance tasks; ® Plan showing the location of all stormwater BMPs maintenance access areas; ® Description and delineation of public safety features; ® Estimated operation and maintenance budget; and ® Operation and Maintenance Log Form. ❑ The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: ❑ A copy of the legal instrument (deed, homeowner's association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; ❑ A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges ❑ The Long -Term Pollution Prevention Plan includes measures to prevent illicit discharges; ❑ An Illicit Discharge Compliance Statement is attached; ❑ NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post -construction BMPs. MassDEP Stormwater Checklist.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 APPENDIX B FIGURE 1 SITE LOCATION October 2025 CH -IV South Yarmouth LNG Whites Path South Yarmouth, Massachusetts c — —tT"tN St CHAR( 9cT QZ` �ppNO RD ORAILL Matthews Pond 90 O tiF sa 0 NPCiEPO 0`'�e a R B EN�E�N LONG S RD z o� Q Yarmouth �ST �WQ Pomf o/Rocks gals River Follins Pond Mil( Pond CLINTON DR 0 c 2 Q A 0R O a z \Jf R R0 z MAVFYO o � > �GR y MISS 7-hatchers - SITE LOCATION � - Z DinaL,� Pond Pond ha: Pond (LCR o O KNOB HILL RC F� Gcrn.nn hui 5 - P a i4 h!-L a - - _ b HI'ES Pl.TH NPc OAN D 94 Cape Cod Ran ST J Cat Swamp Pond� 'a yOARD S Stations Avenuee S Yarmouth Trailhead RID RD p LLOCK 0 F 9^ L Z Z O 3 D_ (✓ C V Z N Lily Por:d O _ D 7 � V n Z n 'OATy o c w(ND/AMMER LN - o mo _ v` 2f CAPTAIN RYDER aQ CAPTAIN SMALL D {r•.�„y a,:::� BESSE RD :; �Q 2� L,:b•::;,. NTH- CAPTAIN IOYCE S' o mQ Ponu 2 S P'4" STILES U NTH .oG n WAY z n LAMES 5T -, 0 o "Po - SIERRA WAY LN O Long Pond Plashes ,MONROE 0� Cedci S—rnp 0R South _ O? Yarmouth o o a z v n AQ O Ap O y< lames Tighe&Bond Based , t1JIG5G5 The National Map Topo Basemap. Contour.I l Equals 10 Feet. Circles indicate 500-root and half -mile radii. G:\GIS\MA\SfteI-xus\Yarmouth\C5200_CH-IVSouthYarrnouthLNG\C5200_CH-IVSouthYarmouthLNG.aprx\Figi_Topo [Exported By: toe Souza Bartow, 101142025, 10:25AMI - 1:24,000 N 0 1,0I 00 2,000 I Feet C-5200 FIGURE 2 PRIORITY RESOURCE October 2025 CH -IV South Yarmouth LNG Whites Path South Yarmouth, Massachusetts i�%;'ll� E���� ► ��li- ���;►� el11�l�� .� (.�il�, ��II, �i►' III -. �I 1 .Qb, 'k � 1 ., ;•�II� Ili I /� ,�_;7� . �� ! � 1 14 li1 li111j ;iiiil���•r �: ��%', ./. �' ►.. 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II/I�IIf,�l1��/\��. 11►\\\111..,1.�11e���� L I ■���,-IIIII/1�i,I/iu,..�_�,i:.� NHESP Certified Vernal Pool ■ Non -Community Non -Transient Public Water Supply Streamllntermittenl Stream ® Solid Waste Landfill Public Surface Water Supply(PSWS) Iii NHESP Potential Vernal Pool ■ Non -Community Transient Public Water Supply ♦ Powerlin, ® Area of Chiral Environmental Concern (ACEC) Water Body Q Pipeline CM NHESP Priority Habitat for Rare Species Non-Potenfal Drinking Water Source Area - High Yield - Non-Lantlfill Solitl Waste SRe tl Highway Track or Trail fo NHESP Estimated Habitat for Rare Wildlife Non -Potential Drinking Water Source Area - Medium Yeld .41 Proposed Well Muft Muif'I-Wne Highway, NOT Limited Access ne Hi + Railroad ® EPA Designated Sole Source Aquifer O Potentially Productive Medium Yield Aquifer — Other Numbered Route ^ Public Surface Water Supply Protection Area (Zone A) Q Major Drainage Basin 1,0 Potentially Productive High Yield Aquifer ©ICJ Emergency Surface Water — Major Road- Arterials and Collectors DEPA d Wellhead Protection Area (Zone I� Approved ( ) Sub Drainage Basin O g county Bounds Q ty Boundary © Community Public Water Supply -Surface Water Minor Street or Road >@ DEP Approved Wellhead Protection Area (Zone II) ® MassDEP Inland Wetland Q Municipal Boundary Aqueduct ® DEP Interim Wellhead Protection Area (IWPA) ® M... DEP Coastal Welland O USGS Quadrangle Sheet Boundary © Community Public Water Supply -Groundwater Hydrologic Connection ® Protected and Recreational Open Space MassDEP Not Interpreted Wetland - 1:24,000 w 1 0 1,000 2,000 Data source: Bureau of Geographic lmomiafien(M—GIS), Commonwealth of Massachusetts, EeradiieOficeoTechnology N I I I Tighe&Bond cata a indicate eoafoor202 halt-mfie radii Feet Data valid as or ocrober zozs. G'\GIS\MA\SmLocus%Yarmouth\C5200_CH-IVSouthyamloulhLNG\C5200_CH-IVSouthYarmouthLNG.apndFig2_Resource (Exported By: IDe Souu BaMmus 1011412025,10:23 AM) C-5200 •Mid -Ca -ape High�w;a�y • WhitAll es • "�, tier - w �: ti ••• 7J IN AIIII C �� • :y yy�' yL • sir �: 3 ♦ y' � t �. - �'• b��a`y't4- .b I Bacon Sfireet� AW CNFik� r�M� ��, ��4+a .y1 t - d. ' '-_ ,�.. r.D + `•��..� �1Tr' � Jf 901.'t �)�f. se Y il W � `� ��.`• '�,.���.:�1q:` :. �lrr ,�•, `'ram' ��~ 3' * a� �. l y .+ U' 'II -Y-�' r _ ti NO t t gne&Bonc 4A\SlteLocus\Yammth\C5200 CH-IVSouthYai 4S - - \\ /1 1 / i /i l� R=34.1 / 1 I301 x / 141 �Jl rl ► / / I I ` _� _ \ \\ \ \\ \ p\\ III \ \ I �) \`1�I111111 4f\ \\ \ l \40— Ji ----- `-- I `—' / ' ems, \ / / \ --w - Wie�f / ro®GENd SUBCATCHMENT BOUNDARY —�i---�--� STORMWATER FLOW PATH NOTES TO USERS =Z- T COASTAL BARRIER RESOURCES SYSTEM (CBRS) LEGEND FIRM FLOOD INSUMNCE MM MAP BARNSTABLE COUNTY, MASSACHUSETTS (AL-URISDI-S) ..U..E. 2501CO57SJ EFFECTNE DAM JULY 16, N14 APPENDIX C USDA United States Department of Agriculture MRCS Natural Resources Conservation Service A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Barnstable County, Massachusetts October 8, 2025 Preface Soil surveys contain information that affects land use planning in survey areas. They highlight soil limitations that affect various land uses and provide information about the properties of the soils in the survey areas. Soil surveys are designed for many different users, including farmers, ranchers, foresters, agronomists, urban planners, community officials, engineers, developers, builders, and home buyers. Also, conservationists, teachers, students, and specialists in recreation, waste disposal, and pollution control can use the surveys to help them understand, protect, or enhance the environment. Various land use regulations of Federal, State, and local governments may impose special restrictions on land use or land treatment. Soil surveys identify soil properties that are used in making various land use or land treatment decisions. The information is intended to help the land users identify and reduce the effects of soil limitations on various land uses. The landowner or user is responsible for identifying and complying with existing laws and regulations. Although soil survey information can be used for general farm, local, and wider area planning, onsite investigation is needed to supplement this information in some cases. Examples include soil quality assessments (http://www.nres.usda.gov/wps/ portal/nres/main/soils/health/) and certain conservation and engineering applications. For more detailed information, contact your local USDA Service Center (https-.//offices.sc.egov.usda.gov/locator/app?agency=nres) or your NRCS State Soil Scientist (http://www.nres.usda.gov/wps/portal/nres/detail/soils/contactus/? cid=nres142p2_053951). Great differences in soil properties can occur within short distances. Some soils are seasonally wet or subject to flooding. Some are too unstable to be used as a foundation for buildings or roads. Clayey or wet soils are poorly suited to use as septic tank absorption fields. A high water table makes a soil poorly suited to basements or underground installations. The National Cooperative Soil Survey is a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local agencies. The Natural Resources Conservation Service (NRCS) has leadership for the Federal part of the National Cooperative Soil Survey. Information about soils is updated periodically. Updated information is available through the NRCS Web Soil Survey, the site for official soil survey information. The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. Contents Preface............................................................................. How Soil Surveys Are Made .......................................... SoilMap........................................................................... SoilMap........................................................................ Legend.......................................................................... MapUnit Legend.......................................................... Map Unit Descriptions................................................... Barnstable County, Massachusetts ........................... 252A—Carver coarse sand, 0 to 3 percent slopes 252B—Carver coarse sand, 3 to 8 percent slopes 602—Urban land ................................................... References .......................................... .2 ..5 .8 ..9 10 11 11 13 13 14 16 18 4 How Soil Surveys Are Made Soil surveys are made to provide information about the soils and miscellaneous areas in a specific area. They include a description of the soils and miscellaneous areas and their location on the landscape and tables that show soil properties and limitations affecting various uses. Soil scientists observed the steepness, length, and shape of the slopes; the general pattern of drainage; the kinds of crops and native plants; and the kinds of bedrock. They observed and described many soil profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The profile extends from the surface down into the unconsolidated material in which the soil formed or from the surface down to bedrock. The unconsolidated material is devoid of roots and other living organisms and has not been changed by other biological activity. Currently, soils are mapped according to the boundaries of major land resource areas (MLRAs). MLRAs are geographically associated land resource units that share common characteristics related to physiography, geology, climate, water resources, soils, biological resources, and land uses (USDA, 2006). Soil survey areas typically consist of parts of one or more MLRA. The soils and miscellaneous areas in a survey area occur in an orderly pattern that is related to the geology, landforms, relief, climate, and natural vegetation of the area. Each kind of soil and miscellaneous area is associated with a particular kind of landform or with a segment of the landform. By observing the soils and miscellaneous areas in the survey area and relating their position to specific segments of the landform, a soil scientist develops a concept, or model, of how they were formed. Thus, during mapping, this model enables the soil scientist to predict with a considerable degree of accuracy the kind of soil or miscellaneous area at a specific location on the landscape. Commonly, individual soils on the landscape merge into one another as their characteristics gradually change. To construct an accurate soil map, however, soil scientists must determine the boundaries between the soils. They can observe only a limited number of soil profiles. Nevertheless, these observations, supplemented by an understanding of the soil -vegetation -landscape relationship, are sufficient to verify predictions of the kinds of soil in an area and to determine the boundaries. Soil scientists recorded the characteristics of the soil profiles that they studied. They noted soil color, texture, size and shape of soil aggregates, kind and amount of rock fragments, distribution of plant roots, reaction, and other features that enable them to identify soils. After describing the soils in the survey area and determining their properties, the soil scientists assigned the soils to taxonomic classes (units). Taxonomic classes are concepts. Each taxonomic class has a set of soil characteristics with precisely defined limits. The classes are used as a basis for comparison to classify soils systematically. Soil taxonomy, the system of taxonomic classification used in the United States, is based mainly on the kind and character of soil properties and the arrangement of horizons within the profile. After the soil 5 Custom Soil Resource Report scientists classified and named the soils in the survey area, they compared the individual soils with similar soils in the same taxonomic class in other areas so that they could confirm data and assemble additional data based on experience and research. The objective of soil mapping is not to delineate pure map unit components; the objective is to separate the landscape into landforms or landform segments that have similar use and management requirements. Each map unit is defined by a unique combination of soil components and/or miscellaneous areas in predictable proportions. Some components may be highly contrasting to the other components of the map unit. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The delineation of such landforms and landform segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, onsite investigation is needed to define and locate the soils and miscellaneous areas. Soil scientists make many field observations in the process of producing a soil map. The frequency of observation is dependent upon several factors, including scale of mapping, intensity of mapping, design of map units, complexity of the landscape, and experience of the soil scientist. Observations are made to test and refine the soil -landscape model and predictions and to verify the classification of the soils at specific locations. Once the soil -landscape model is refined, a significantly smaller number of measurements of individual soil properties are made and recorded. These measurements may include field measurements, such as those for color, depth to bedrock, and texture, and laboratory measurements, such as those for content of sand, silt, clay, salt, and other components. Properties of each soil typically vary from one point to another across the landscape. Observations for map unit components are aggregated to develop ranges of characteristics for the components. The aggregated values are presented. Direct measurements do not exist for every property presented for every map unit component. Values for some properties are estimated from combinations of other properties. While a soil survey is in progress, samples of some of the soils in the area generally are collected for laboratory analyses and for engineering tests. Soil scientists interpret the data from these analyses and tests as well as the field -observed characteristics and the soil properties to determine the expected behavior of the soils under different uses. Interpretations for all of the soils are field tested through observation of the soils in different uses and under different levels of management. Some interpretations are modified to fit local conditions, and some new interpretations are developed to meet local needs. Data are assembled from other sources, such as research information, production records, and field experience of specialists. For example, data on crop yields under defined levels of management are assembled from farm records and from field or plot experiments on the same kinds of soil. Predictions about soil behavior are based not only on soil properties but also on such variables as climate and biological activity. Soil conditions are predictable over long periods of time, but they are not predictable from year to year. For example, soil scientists can predict with a fairly high degree of accuracy that a given soil will have a high water table within certain depths in most years, but they cannot predict that a high water table will always be at a specific level in the soil on a specific date. After soil scientists located and identified the significant natural bodies of soil in the survey area, they drew the boundaries of these bodies on aerial photographs and A Custom Soil Resource Report identified each as a specific map unit. Aerial photographs show trees, buildings, fields, roads, and rivers, all of which help in locating boundaries accurately. 7 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 41°41'23'N 41° 41'14'N Custom Soil Resource Report A Soil Map � � k 3MM 39M 400020 40M 400100 400140 400180 400220 4002-60 400300 400340 3 3 b, Map Scale: 1:2,020 if printed on A landscape (11" x 8.5") sheet - N Meters 0 25 50 100 150 Few 0 50 100 200 30D Map projection: Web Mercator GDmer000rdinabes: WGS84 Edge tics: URN Zone 19N WGS84 9 41°41'23'N 41° 41'14'N Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest (AOI) a Spoil Area The soil surveys that comprise your AOI were mapped at Area of Interest (AOI) 10 Stony Spot 1:25,000. Soils 0 Soil Map Unit Polygons 45 Very Stony Spot Warning: Soil Map may not be valid at this scale. Wet Spot Soil Map Unit Lines Enlargement of maps beyond the scale of mapping can cause � Soil Map Unit Points p Other misunderstanding of the detail of mapping and accuracy of soil g pp g y Special Line Features line placement. The maps do not show the small areas of Special Point Features contrasting soils that could have been shown at a more detailed Blowout Water Features scale. Streams and Canals ® Borrow Pit Transportation Please rely on the bar scale on each map sheet for map Clay Spot i-1-f Rails measurements. O Closed Depression N Interstate Highways Source of Map: Natural Resources Conservation Service X Gravel Pit US Routes Web Soil Survey URL: Gravelly Spot Coordinate System: Web Mercator (EPSG:3857) _ Major Roads ® Landfill � Local Roads Maps from the Web Soil Survey are based on the Web Mercator A Lava Flow projection, which preserves direction and shape but distorts Background distance and area. A projection that preserves area, such as the Marsh or swamp . Aerial Photography Albers equal-area conic projection, should be used if more Mine or Quarry accurate calculations of distance or area are required. Miscellaneous Water This product is generated from the USDA-NRCS certified data as O Perennial Water of the version date(s) listed below. V Rock Outcrop Soil Survey Area: Barnstable County, Massachusetts + Saline Spot Survey Area Data: Version 24, Sep 5, 2025 Sandy Spot Soil map units are labeled (as space allows) for map scales .� Severely Eroded Spot 1:50,000 or larger. 4 Sinkhole Date(s) aerial images were photographed: Jun 10, 2022—Jun Slide or Slip 30, 2022 Sodic Spot The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. 10 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 252A Carver coarse sand, 0 to 3 17.4 89.0% percent slopes 252E Carver coarse sand, 3 to 8 1.3 6.6% percent slopes Urban land 0.8 19.5 602 4.3% Totals for Area of Interest 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The 11 Custom Soil Resource Report delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha -Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha -Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. 12 Custom Soil Resource Report Barnstable County, Massachusetts 252A—Carver coarse sand, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 2y07w Elevation: 0 to 990 feet Mean annual precipitation: 36 to 71 inches Mean annual air temperature: 39 to 55 degrees F Frost -free period: 140 to 240 days Farmland classification: Not prime farmland Map Unit Composition Carver, coarse sand, and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Carver, Coarse Sand Setting Landform: Moraines, outwash plains Landform position (two-dimensional): Summit, shoulder Landform position (three-dimensional): Side slope, crest, tread Down -slope shape: Convex, linear Across -slope shape: Linear Parent material: Sandy glaciofluvial deposits Typical profile Oi - 0 to 2 inches: slightly decomposed plant material Oe - 2 to 3 inches: moderately decomposed plant material A - 3 to 7 inches: coarse sand E - 7 to 10 inches: coarse sand Bw1 - 10 to 15 inches: coarse sand Bw2 - 15 to 28 inches: coarse sand BC - 28 to 32 inches: coarse sand C - 32 to 67 inches: coarse sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Drainage class: Excessively drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to very high (1.42 to 14.17 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Maximum salinity: Nonsaline (0.0 to 1.9 mmhos/cm) Available water supply, 0 to 60 inches: Low (about 4.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Ecological site: F149BY005MA - Dry Outwash 13 Custom Soil Resource Report Hydric soil rating: No Minor Components Deerfield Percent of map unit: 10 percent Landform: Outwash terraces, outwash plains, kame terraces, outwash deltas Landform position (three-dimensional): Tread Down -slope shape: Linear Across -slope shape: Concave Hydric soil rating: No Hinckley Percent of map unit: 5 percent Landform: Moraines, eskers, kames, outwash deltas, outwash terraces, outwash plains, kame terraces Landform position (two-dimensional): Summit, shoulder, backslope, footslope, toeslope Landform position (three-dimensional): Head slope, nose slope, side slope, crest, riser, tread Down -slope shape: Convex Across -slope shape: Convex Hydric soil rating: No Merrimac Percent of map unit: 3 percent Landform: Kame terraces, outwash deltas, outwash terraces Landform position (three-dimensional): Riser, tread Down -slope shape: Linear Across -slope shape: Linear Hydric soil rating: No Mashpee Percent of map unit: 2 percent Landform: Depressions, drainageways, terraces Landform position (three-dimensional): Tread Down -slope shape: Concave Across -slope shape: Concave Hydric soil rating: Yes 25213—Carver coarse sand, 3 to 8 percent slopes Map Unit Setting National map unit symbol: 2y07x Elevation: 0 to 240 feet Mean annual precipitation: 36 to 71 inches Mean annual air temperature: 39 to 55 degrees F Frost -free period: 140 to 240 days Farmland classification: Not prime farmland 14 Custom Soil Resource Report Map Unit Composition Carver, coarse sand, and similar soils: 80 percent Minor components: 20 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Carver, Coarse Sand Setting Landform: Moraines, outwash plains Landform position (two-dimensional): Summit, shoulder, backslope, footslope, toeslope Landform position (three-dimensional): Head slope, nose slope, side slope, crest, tread Down -slope shape: Convex, linear Across -slope shape: Linear Parent material: Sandy glaciofluvial deposits Typical profile Oi - 0 to 2 inches: slightly decomposed plant material Oe - 2 to 3 inches: moderately decomposed plant material A - 3 to 7 inches: coarse sand E - 7 to 10 inches: coarse sand Bw1 - 10 to 15 inches: coarse sand Bw2 - 15 to 28 inches: coarse sand BC - 28 to 32 inches: coarse sand C - 32 to 67 inches: coarse sand Properties and qualities Slope: 3 to 8 percent Depth to restrictive feature: More than 80 inches Drainage class: Excessively drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to very high (1.42 to 14.17 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Maximum salinity: Nonsaline (0.0 to 1.9 mmhos/cm) Available water supply, 0 to 60 inches: Low (about 4.3 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3s Hydrologic Soil Group: A Ecological site: F149BY005MA - Dry Outwash Hydric soil rating: No Minor Components Deerfield Percent of map unit: 10 percent Landform: Outwash terraces, outwash plains, kame terraces, outwash deltas Landform position (three-dimensional): Tread Down -slope shape: Linear Across -slope shape: Concave Hydric soil rating: No 15 Custom Soil Resource Report Hinckley Percent of map unit: 5 percent Landform: Moraines, eskers, kames, outwash deltas, outwash terraces, outwash plains, kame terraces Landform position (two-dimensional): Summit, shoulder, backslope, footslope, toeslope Landform position (three-dimensional): Head slope, nose slope, side slope, crest, riser, tread Down -slope shape: Convex Across -slope shape: Convex Hydric soil rating: No Merrimac Percent of map unit: 3 percent Landform: Kame terraces, outwash deltas, outwash terraces Landform position (three-dimensional): Riser, tread Down -slope shape: Linear Across -slope shape: Linear Hydric soil rating: No Mashpee Percent of map unit: 2 percent Landform: Depressions, drainageways, terraces Landform position (three-dimensional): Tread Down -slope shape: Concave Across -slope shape: Concave Hydric soil rating: Yes 602—Urban land Map Unit Setting National map unit symbol: 98s7 Frost -free period: 120 to 220 days Farmland classification: Not prime farmland Map Unit Composition Urban land: 85 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Urban Land Setting Parent material: Excavated and filled land Minor Components Udipsamments Percent of map unit: 15 percent Hydric soil rating: Unranked Custom Soil Resource Report 17 References American Association of State Highway and Transportation Officials (AASHTO). 2004. Standard specifications for transportation materials and methods of sampling and testing. 24th edition. American Society for Testing and Materials (ASTM). 2005. Standard classification of soils for engineering purposes. ASTM Standard D2487-00. Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of wetlands and deep -water habitats of the United States. U.S. Fish and Wildlife Service FWS/OBS-79/31. Federal Register. July 13, 1994. Changes in hydric soils of the United States. Federal Register. September 18, 2002. Hydric soils of the United States. Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric soils in the United States. National Research Council. 1995. Wetlands: Characteristics and boundaries. Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service. U.S. Department of Agriculture Handbook 18. http://www.nres.usda.gov/wps/portal/ nres/detail/national/soils/?cid=nres142p2_054262 Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for making and interpreting soil surveys. 2nd edition. Natural Resources Conservation Service, U.S. Department of Agriculture Handbook 436. http:// www.nres. usda.gov/wps/portal/nres/detail/national/soils/?cid=nres142p2_053577 Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of Agriculture, Natural Resources Conservation Service. http-.// www. nres. usda.gov/wps/portal/nres/detail/national/soils/?cid=nresl42p2_053580 Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and Delaware Department of Natural Resources and Environmental Control, Wetlands Section. United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of Engineers wetlands delineation manual. Waterways Experiment Station Technical Report Y-87-1. United States Department of Agriculture, Natural Resources Conservation Service. National forestry manual. http://www.nres.usda.gov/wps/portal/nres/detail/soils/ home/?cid=nres142p2_053374 United States Department of Agriculture, Natural Resources Conservation Service. National range and pasture handbook. http://www.nres.usda.gov/wps/portal/nres/ detail/national/landuse/rangepasture/?cid=stelprdb1043084 18 Custom Soil Resource Report United States Department of Agriculture, Natural Resources Conservation Service. National soil survey handbook, title 430-VI. http://www.nres.usda.gov/wps/portal/ nres/deta il/soils/scientists/?cid=nres142p2_054242 United States Department of Agriculture, Natural Resources Conservation Service. 2006. Land resource regions and major land resource areas of the United States, the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook 296. http://www.nres.usda.gov/wps/portal/nres/detail/national/soils/? cid=nres 142 p2_053624 United States Department of Agriculture, Soil Conservation Service. 1961. Land capability classification. U.S. Department of Agriculture Handbook 210. http:// www.nrcs.usda.gov/lnternet/FSE—DOCUMENTS/nrcsl42p2_052290.pdf 19 GEOTECHNICAL ENVIRONMENTAL U NATIONAL GRID LIQUID NATURAL GAS FACILITY GEOTECHNICAL REPORT PROPOSED LIQUID NATURAL GAS TANK REPLACEMENT Whites Path, South Yarmouth, Massachusetts File No. 03.0035206.00 May 2023 PREPARED FOR: National Grid Waltham, Massachusetts GZA GeoEnvironmental, Inc. 188 Valley Street, Suite 300 1 Providence, RI 02909 401-427-2731 31 Offices Nationwide www.gza.com Copyright© 2023 GZA GeoEnvironmental, Inc. GEOTECHNICAL ENVIRONMENTAL May 12, 2023 GZA File No. 03.0035206.00 Mr. Matthew Adam Lead Engineer National Grid 170 Data Drive Waltham, MA 02451 Re: Geotechnical Engineering Report Proposed LNG Tank Replacement National Grid LNG Facility Whites Path South Yarmouth, Massachusetts Dear Mr. Adam: We are pleased to provide you with this Geotechnical Engineering Report, which presents the findings of GZA's subsurface explorations, laboratory testing results, a summary of the subsurface conditions, and recommendations for design and construction of the proposed new liquid natural gas (LNG) tank replacement at the LNG Facility in South Yarmouth, Massachusetts. We appreciate the opportunity to provide these services to National Grid. If you have any questions or need additional information, please contact the undersigned at lason.ressler@gza.com. Sincerely, GZA GEOENVIRONMENTAL INC 4 Jas�, E. Ressler, P.E. Senior Project Manager Gary R. McAllister, P.E. Principle -in -Charge Ja es F. Davis, P.E,cr Consultant / Reviewer J TABLE OF CONTENTS May 12, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 1 1.0 INTRODUCTION.................................................................................................................................................. 1 2.0 BACKGROUND INFORMATION............................................................................................................................ 1 2.1 SITE LOCATION AND OBSERVED CONDITIONS......................................................................................... 1 2.2 PROPOSED CONSTRUCTION.................................................................................................................... 1 2.3 SITE HISTORY.......................................................................................................................................... 2 2.4 REGIONAL GEOLOGIC SETTING................................................................................................................ 2 2.5 FLOOD INSURANCE MAP......................................................................................................................... 2 3.0 GEOTECHNICAL INVESTIGATION......................................................................................................................... 2 3.1 PRIOR TEST BORINGS.............................................................................................................................. 2 3.2 GEOTECHNICAL TEST BORINGS PERFORMED FOR THIS STUDY................................................................. 3 4.0 LABORATORY TESTING PROGRAM...................................................................................................................... 4 5.0 SUBSURFACE CONDITIONS................................................................................................................................. 4 6.0 IMPLICATIONS OF SUBSURFACE CONDITIONS.................................................................................................... 6 7.0 CONCLUSIONS AND GEOTECHNICAL RECOMMENDATIONS................................................................................ 6 7.1 ADDITIONAL SUBSURFACE EXPLORATIONS.............................................................................................. 6 7.2 PRELIMINARY DESIGN PARAMETERS....................................................................................................... 7 7.3 SHALLOW FOUNDATIONS....................................................................................................................... 7 7.4 FOUNDATION ALTERNATIVES.................................................................................................................. 7 7.4.1 Oversized Mat......................................................................................................................................... 7 7.4.2 Ground Improvement............................................................................................................................. 7 7.4.3 Pile Foundations..................................................................................................................................... 8 7.5 SEISMIC DESIGN CONSIDERATIONS......................................................................................................... 8 7.6 PERMANENT GROUNDWATER CONTROL................................................................................................ 9 7.7 FILL MATERIALS, PLACEMENT, AND COMPACTION.................................................................................. 9 7.8 EXCAVATED MATERIAL REUSE AND DISPOSAL........................................................................................12 TABLE OF CONTENTS May 12, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 2 8.0 CONSTRUCTION.................................................................................................................................................13 8.1 SUBGRADE PREPARATION......................................................................................................................13 8.2 SUBGRADE STABILIZATION.....................................................................................................................13 8.3 SUBGRADE PROTECTION........................................................................................................................13 8.4 EXCAVATION SUPPORT..........................................................................................................................14 8.5 CONSTRUCTION DEWATERING...............................................................................................................14 8.6 PROTECTION OF EXISTING STRUCTURES.................................................................................................14 TABLES TABLE 1 SUMMARY OF SUBSURFACE CONDITIONS TABLE 2 RECOMMENDED GENERALIZED SUBSURFACE PROFILE OF EXISTING CONDITIONS TABLE 3 RECOMMENDED FOUNDATION DESIGN PARAMETERS —GRANULAR SOIL TABLE 4 RECOMMENDED FOUNDATION DESIGN PARAMETERS — COHESIVE SOIL FIGURES FIGURE 1 LOCUS FIGURE 2 EXPLORATION LOCATION PLAN APPENDICES APPENDIX A— LIMITATIONS APPENDIX B— SUBSURFACE EXPLORATIONS APPENDIX C — LABORATORY TEST DATA May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 1 1.0 INTRODUCTION In accordance with our Proposal for Geotechnical Engineering Services, dated February 27, 2023, GZA GeoEnvironmental, Inc. (GZA) has prepared this report documenting the results of our recent subsurface investigations within the Liquified Natural Gas (LNG) Facility in South Yarmouth, Massachusetts (herein referred to as the "Site"). The scope of this study included geotechnical investigations and preliminary recommendations for the proposed new LNG tank. Unless indicated otherwise, elevations presented herein are referenced to North American Vertical Datum of 1988 (NAVD 88). This study was completed pursuant to National Grid Purchase Order No. 3200619528. This report is subject to the limitations included in Appendix A. It is our understanding that this project will be executed as an engineer -procure -construct (EPC) contract. The intent of this Geotechnical Engineering Report is to provide the EPC contractors with factual information (i.e., test boring logs, laboratory testing) and preliminary design recommendations. We understand that the EPC firm awarded the contract will perform their own separate analysis of foundations, settlement, and other geotechnical design and construction considerations. 2.0 BACKGROUND INFORMATION Our understanding of the project is based on the following: 1. Our observations made during the field activities completed as noted herein; 2. Conference calls and meetings with National Grid; 3. A file titled "Comparison of Dimensions, Volumes, etc. with or without 980CMR10.pdf", by Cashman -Preload Cryogenics, received by GZA on February 15, 2023, which shows the preliminary tank sizing; and 4. Sketch plans provided by National Grid, showing the location of the proposed new tank. 2.1 SITE LOCATION AND OBSERVED CONDITIONS The LNG Facility is located in the town of South Yarmouth, MA as shown on Figure 1. The specific portion of the Site addressed in this geotechnical study includes the footprint of the proposed tank, located about 100 feet to the northeast of the existing tank, as shown on Figure 2. The location of the proposed new tank is partially within the fenced area of existing LNG facility, and partially outside the fenced area. The new tank location is bounded by undeveloped woodlands to the north, east, and south. A topographic survey of the Site was not available at the time of this report. Based on LiDAR topography obtained from the MAGIS, existing grades in the vicinity of the proposed new tank are generally flat, at about elevation 37 to 38 feet. The ground surface within the new tank footprint is either gravel (within the existing LNG facility) or a combination of asphalt paved access drive and wooded land (outside the existing LNG facility). 2.2 PROPOSED CONSTRUCTION The proposed construction includes the replacement of the LNG tank. The preliminary proposed replacement tank will be constructed at existing grades, with a diameter of about 90 to 100 feet. The tank size will be about 2.91 MG, and the tank will consist of an inner and an outer tank, with a dome roof. Based on preliminary estimates, we anticipate that the maximum gravity loads imposed by the tank in a loaded condition will average on the order of 2,500 pounds per square foot (psf.) May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 2 2.3 SITE HISTORY Historic aerial photographs and topography dating back to 1889 were reviewed byGZA in order to obtain an understanding of the Site history. The existing LNG facility and tank first appear on historical topographic maps in 1974. Based on the historical mapping, it does not appear the area ofthe proposed new LNG tank was previously developed, otherthan minor grading, fencing, and the asphalt access drive associated with the existing facility. 2.4 REGIONAL GEOLOGIC SETTING United States Geologic Survey (USGS) publications were reviewed to obtain an understanding of the area geology. The publications included the "Surficial Materials Map of the Dennis Quadrangle, Massachusetts", dated 2018, the "Geologic Map of Cape Cod and the Islands, Massachusetts", dated 1986, and the "Bedrock Geologic Map of Massachusetts", dated 1983. Surficial Geology Based on the Surficial Materials Map of the Dennis Quadrangle, Massachusetts, the mapped profile consists of glacial stratified deposits, which is comprised of gravel, sand and gravel, and sand deposits, deposited by glacial meltwaters from the last glaciation period. Based on the "Geologic Map of Cape Cod and the Islands", the Site is located at the intersection of the Sandwich Moraine and Harwich Outwash Plan Deposits. The Sandwich Moraine Deposits consist of sand and gravel, with stratified layers of fine sand, silt, and clay. The Harwich Outwash Plain Deposits consist of gravelly sand, with localized layers of silt and clay. The Sandwich Moraine and Harwich Outwash Plan Deposits both have the potential to contain boulders. Bedrock Geology The bedrock underlying the Site consists of granite, gneiss, or schist, which is described as plutonic and metamorphic rocks. 2.5 FLOOD INSURANCE MAP The Site is located within the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM) Number 25001C0579J, effective July 16, 2014. Based on the FIRM, the Site is located outside of the 100-year and 500-year flood zones. 3.0 GEOTECHNICAL INVESTIGATION The following sections describe the relevant previous subsurface site investigations and the geotechnical test borings performed for this study at the Site. Logs of the test borings drilled for this study are included in Appendix B, and the locations are shown on Figure 2. 3.1 PRIOR TEST BORINGS The prior subsurface explorations referenced in this study include the B-series test borings by Tighe & Bond in 2014. Tighe & Bond performed two (2) test borings located about 330 feet to 820 feet west of the proposed LNG tank. The soil profile encountered in these test borings consisted of medium dense stratified sands with silt and clay, which are consistent with the mapped Surficial geology. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 3 3.2 GEOTECHNICAL TEST BORINGS PERFORMED FORTH IS STUDY The test borings were located in the field by National Grid. The completed test boring locations were measured using fiberglass tape and line -of -sight methods referencing existing site features, and are shown on Figure 2. The ground surface elevations at each test boring were estimated based on published Light Detection and Ranging (LiDAR) data from the Massachusetts Geographic Information System (MassGIS), rounded to the nearest foot. The locations and elevations should be considered accurate to the degree implied by the method used. Prior to drilling, to assess for the presence of potential buried utilities at the test boring locations, each test boring was pre -cleared for utilities by using a soil vacuum rig. The vacuum excavations extended to a depth of approximately 5.5 feet below ground and were observed and logged by a GZA representative. Soil samples were obtained. Three test borings, designated GZ-1 through GZ-3, were drilled by Geologic Earth Exploration Inc. of Norfolk, Massachusetts between March 20th and March 23rd, 2023, to depths ranging from about 51 feet to 101 feet below ground surface within the footprint of the proposed new LNG tank. The explorations were drilled with an ATV -mounted drill rig utilizing drive and wash rotary drilling and telescoping casing techniques. Below the vacuum excavation depths, split spoon samples were obtained at 2- to 5-foot intervals. Split spoon sampling was performed in conformance with ASTM D-1586, the Standard Penetration Test, to obtain an indication of the relative density and consistency of the underlying soils. The Standard Penetration Test consists of driving a 1-3/8 inch inside diameter standard split spoon sampler at least 18 inches with a 140-pound hammer dropping from a height of 30 inches. The standard penetration value (N-value) is the number of blows required to drive the split spoon sampler from a depth of 6 to 18 inches of penetration (a total of 12-inches). Recovered soil samples were visually classified in the field in accordance with the Modified Burmister Soil Classification System with Unified Soil Classification symbols. The test borings were observed and logged by GZA personnel. The test borings were extended to the depths described below. Groundwater observations are noted on the test boring logs. Refer to the test boring logs in Appendix B for specific conditions encountered in each test boring. Refer to Table 1 for a summary of test boring information. Test Boring Location Test Boring Termination Termination Depth (Feet, approx.) GZ-1 Proposed New LNG Tank Proposed depth achieved 101 GZ-2 Proposed depth achieved 51 GZ-3 Proposed depth achieved 51 May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 4 4.0 LABORATORY TESTING PROGRAM Selected soil samples obtained during the subsurface exploration program were submitted to Thielsch Engineering of Cranston, Rhode Island for consolidation and index testing. The results of the laboratory program are summarized below. The laboratory reports are included in Appendix C. DEP(Feet) USCS BORING SAMPLE Tests Performed CLASSIFICATION Consolidation, Unit Weight, Moisture Content, GZ-2 U-1 31-33 CL Atterberg Limits Consolidation, Unit Weight, Moisture Content, GZ-3 U-1 33-35 CL/CH Atterberg Limits Recommended design values for each soil strata are provided in Tables 3 and 4. 5.0 SUBSURFACE CONDITIONS Based on the test borings, the general subsurface conditions consisted of: 1. Surficial material, consisting of asphalt or yard gravel, over 2. Glacial Stratified Deposits —Sand, over 3. Glacial Stratified Deposits —Silty Clay, over 4. Glacial Stratified Deposits —Sand. In general, the subsurface conditions encountered in the three new test borings were consistent with the results of previous investigations conducted within the area, and with the published geologic mapping. Table 1 summarizes the subsurface conditions encountered in the test borings. The subsequent sections describe the subsurface conditions in more detail. Surficial Materials At test boring locations GZ-1 and GZ-2, within the existing LNG fencing, approximately 6 inches of yard gravel was encountered. At test boring location GZ-3, outside the existing LNG fence line and within the perimeter access road, the asphalt section was measured to be approximately 6 inches thick. Glacial Stratified — Upper Sand Deposits The surficial material was underlain by a Glacial Stratified, poorly -graded, fine to medium Sand deposit, with less than about 10 percent silt, and occasional trace amounts of gravel (USCS: SP). A 5+-foot-thick silty fine sand layer (USCS: SMf) was encountered at depths of 15 to 20 feet bgs. The SPT N-values obtained ranged from 10 to 43 blows per foot, indicating a relative density of medium dense to dense, with a majority of the uncorrected SPT N-values indicating a medium relative density. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 5 Glacial Stratified — Silty Clay Deposits Glacial stratified silty clay deposits (USCS: CL, CL/CH) were encountered below the upper sand deposits beginning at approximately 28 feet to 30 feet below ground surface. The silty clay deposits were about 5 to 16 feet in thickness. Measured SPT N-values ranged from 9 to 18 blows per foot, indicating a stiff to very stiff consistency. Due to disturbance of the samples, Torvane measurements taken at the laboratory are anticipated to be artificially low, and not representative of in -situ shear strength. Lab testing indicated the following parameters: Moisture Content: 25% to 48% Dry Unit Weight: 85 to 90 pcf Total Unit Weight: 115 to 120 pcf Overconsolidation Ratio, OCR: 3 to 3.5 Modified Coefficient of Compression, C'c: 0.15 to 0.20 Modified Coefficient of Recompression, C'r: 0.02 to 0.03 Coefficient of Consolidation, Cv: 0.002 to 0.02 cmZ/sec Glacial Stratified — Lower Sand Deposits The glacial stratified deposits continued to the termination depth of the test borings. The silty clay stratum was underlain by more glacial stratified sand. This lower sand deposit was similar to the upper sand deposit consisting mainly of poorly - graded fine to medium sand, trace silt (USCS: SP.) The sand included occasional trace amounts of gravel, and in GZ-3 graded to a well -graded fine to coarse sand, trace silt (USCS: SW.). The uncorrected SPT N-values obtained ranged from 18 to 55 blows per foot, indicating a relative density of medium dense to dense. Bedrock Bedrock was not encountered within the maximum test boring depth of 101 feet. Based on our experience in the area, bedrock may be deeper than 200 feet. Groundwater Groundwater was measured during drilling at depths ranging from about 19.5 feet to 26 feet below ground surface, corresponding to approximately El. 11 to 18. Due to the use of drilling fluids, these groundwater levels are not necessarily representative of the equilibrated groundwater conditions. A temporary groundwater monitoring well was installed in the completed test boring GZ-1, and allowed to equilibrate for two days, at which time groundwater was measured to be about 26 feet bgs (El. 11 feet). Fluctuations of the groundwater levels are anticipated to occur due variation in rainfall and other factors different than those prevailing at the time the explorations were performed, and groundwater levels observed. Potential Subsurface Conditions Although not encountered in the test borings, geologic mapping indicates that the glacial deposits may include cobbles and boulders, which could be several feet in diameter. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 6 6.0 IMPLICATIONS OF SUBSURFACE CONDITIONS The primary geotechnical issues anticipated to impact the design and construction of the proposed LNG tank include: 1. The proposed LNG tank will apply ground loads over a significant area. Although the stratified deposits are of generally medium relative density and stiff consistency, they are anticipated to undergo significant compression under these applied loads. Based on the preliminary estimates of the tank loads, the combined immediate and long-term settlements are anticipated to be on the order of 4 to 8 inches, with differential settlements on the order of 20 to 40 percent of the total settlement. The selected foundation design will need to consider means to control the long-term settlements to acceptable amounts. Further evaluation may include performing additional, deeper test borings. Existing Fill and Boulders —Although not encountered in the test borings in the vicinity of the proposed new LNG tank, boulders and existing fill may be present, and include unsuitable bearing materials including unstripped former topsoil / subsoil layers, buried organics, rubble or other foreign debris, or cobbles and boulders. These materials, if encountered, pose foundation design and material re -use challenges. 7.0 CONCLUSIONS AND GEOTECHNICAL RECOMMENDATIONS The geotechnical design and construction recommendations presented below are based on our evaluation of the available data and design concepts provided to GZA and are subject to the limitations contained in Appendix A. The sections below describe GZA's preliminary recommendations for foundations. The EPC contractor will need to confirm the recommendations provided herein, if they will be used for design. If it is found that the structure locations, orientations, or loading change significantly, or that National Grid wishes to consider alternative foundation types, it is recommended that GZA review the changes and revise these recommendations, as necessary. The following recommendations assume that construction will follow National Grid's standard specifications, the requirements of the Federal Energy Regulatory Commission (FERC), and the Massachusetts State Building Code 10th Edition (Unofficial, to be adopted) amending the 2021 International Building Code. 7.1 ADDITIONAL SUBSURFACE EXPLORATIONS The selection and design of the appropriate foundation is dependent on controlling estimated settlements of the tank to within tolerable amounts. The settlement estimates are a function of the applied stresses and soil compressibility with depth. It is anticipated that 90% of load -induced stresses from the tank will be dissipated within a depth of two times the tank diameter below the foundation. Test borings drilled for this study extended to a maximum depth of 101 feet bgs, and the estimates of settlements assume that the medium dense sands extend to minimum depth of 200 feet. Future test borings should extend to a minimum depth of bedrock or at least 200 feet, whichever is encountered first, to evaluate the depth and compressibility and soil to that depth. If a dense bearing stratum (i.e., glacial till) is encountered within that depth it should be sufficiently characterized to evaluate the feasibility, and the design, of pile foundations bearing within that stratum as a potential foundation alternative. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 7 7.2 PRELIMINARY DESIGN PARAMETERS The generalized soil strata in Table 2 and the soil properties provided in Tables 3 and 4 are recommended for analyses and design of the new tank foundation. The recommended parameters are provided to be representative of the subsurface conditions encountered in the test borings. It is recommended that the designer also review the boring logs and independently verify that the parameters are consistent with the designer's interpretation of the subsurface conditions. 7.3 SHALLOW FOUNDATIONS Shallow foundations, such as a ring footing with a slab -on -grade or a uniform mat foundation, are preliminarily anticipated to apply maximum, unfactored, combined dead and live static loads on the order of 2,500 psf onto the soil subgrades. This does not consider factored or dynamic loading. Preliminary combined immediate and long-term total settlement estimates for shallow foundations at the center of the tank range from about 4 to 8 inches. The estimated differential settlement at the edges of the tank could be on the order of 20 to 40 percent of the total settlement at the center. A significant portion of the settlement will take place during tank erection, and both during and after filling the tank. For frost protection, all exterior footings / mats / slabs should be placed at least 4 feet below final grade. The EPC contractor should independently evaluate the anticipated settlements based on the final tank design and loading, with consideration given to the tolerable tank settlements. If the anticipated settlements are not tolerable, foundation alternatives will be required to support the tank. 7.4 FOUNDATION ALTERNATIVES The subsequent paragraphs provide conceptual foundation alternatives that the EPC contractor may consider in reducing the post -construction settlements to within tolerable amounts. The applicability of these alternatives is dependent on the actual loading conditions and tolerable settlements of the tank. Additional, deeper test borings may also be considered to evaluate the soil behavior and potential deep foundation alternatives below a depth of 100 feet. 7.4.1 Oversized Mat A rigid mat foundation may be considered to reduce differential settlements. Oversizing the mat to extend beyond the tank footprint will distribute the loads and potentially reduce settlements to within tolerable amounts. 7.4.2 Ground Improvement Conceptual ground improvement techniques could consist of either rigid inclusions or aggregate piers. Rigid inclusions are columns of unreinforced concrete installed beneath the footings and slabs. The elements would be constructed by advancing a 10- to 16-inch diameter mandrel or reverse -flight augerthrough the sand and silty clay, to a deeper and more dense deposit. As the tooling is extracted, concrete is placed through the tooling under pressure. Little to no spoils are generated with these displacement installation methods. The elements increase bearing capacity of the soil and reduce settlement potential by transferring the vertical loads through the sand and silty clay, and into underlying denser deposits. The elements would be installed in a closely spaced grid below footings, with spacings typically increased in slab areas. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 8 Aggregate piers (i.e., Geopiers° or Rammed Aggregate Piers°) are typically constructed by vibrating or pre -drilling a steel mandrel (pipe) through the unsuitable soils (sand and silty clay), and into the underlying denser granular soil deposit. Crushed stone is then introduced into the hole through the steel mandrel. The crushed stone is compacted in lifts as the mandrel is withdrawn by repetitive ramming with a specially designed vibratory hammer. This process compacts the crushed stone into the sides of the cavity created by the initial installation of the mandrel, and a compacted column of stone is created. A load transfer platform (LTP) consisting of layers of aggregate and geogrid would then be constructed above the rigid inclusions or RAPS. A conventional shallow foundation system and slab -on -grade could then be constructed to bear on the LTP. The rigid inclusions or aggregate piers should extend at least 40 feet laterally beyond the tank foundation, to improve soils within the zone of influence of the applied load. The design and construction of ground improvement is typically performed on a design -build basis by the contractor. Rigid inclusions and aggregate piers should be designed to increase the allowable bearing capacity and improve the subgrade modulus, therefore reducing the anticipated settlement. The EPC contractor should provide a design which includes the required dimensions and spacing of the ground improvement, and relevant details regarding the LTP. The design submittal should include modulus verification testing. Modulus load testing should be performed to two times the design load on the piers. Ground improvement design should be provided by a Professional Engineer licensed in the Commonwealth of Massachusetts. The aggregate piers induce ground vibrations. We recommend pre -construction and post -construction surveys of the existing tank, and implementation of an instrumentation program to monitor vibrations and settlements of the existing tank during construction. The pre -construction condition survey should be documented prior to the start of any work at the project site. This includes photographing and measuring all existing conditions and defects to provide a quantifiable baseline record prior to construction. Crack gages, vibration monitors and/or survey points should be installed at applicable locations, and baseline values should be recorded. Crack readings, vibration measurements, and deflections should be measured throughout construction. If damage, exceeding vibration levels, or excessive deflections are measured, the contractor should stop work and provide an alternate work plan to reduce vibrations and or deflections. 7.4.3 Pile Foundations Based on the available subsurface information, there is insufficient information to assess the feasibility or provide design parameters of drilled or driven pile foundations for support of the tank. Certain types of pile foundations can be feasibly advanced to depths of 200 feet or more. If a suitable bearing stratum is identified and adequately characterized within this depth, pile foundations in conjunction with a pile cap mat foundation may potentially be a feasible foundation alternative. 7.5 SEISMIC DESIGN CONSIDERATIONS The following seismic design parameters are based on subsurface information described herein. Should conditions vary from those stated in this report, the following should be confirmed to maintain compliance with the applicable guidelines and codes. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 9 Seismic Design Parameter Value Site Class D Mapped short -period spectral response acceleration SS 0.153 Mapped one -second spectral response acceleration Sl 0.048 The subsurface conditions were assessed for liquefaction potential. The term "liquefaction" describes a phenomenon in which saturated, cohesionless soil experiences a substantial reduction in effective stress during a design earthquake and acquires a degree of temporary mobility sufficient to permit substantial settlement and/or loss of bearing capacity. Based on the measured relative density and gradation of the site soils below the groundwater level, it is our opinion that liquefaction under a design seismic event is not anticipated to result in a significant loss in bearing capacity or result in significant seismic -induced settlement. In Massachusetts, the state code design for lateral earth pressures should also include seismic forces added to the static forces. For horizontal backfill, foundation and retaining walls should be designed to resist an earthquake force, FW, as defined below. The seismic resultant force should be distributed over the height of the wall as an inverted triangle. FW = 0.1(Ss)(Fa)(yt)(H)Z Where Ss and Fa are seismic parameters provided above; yt is the total unit weight of the soil, provided in Table 3, and H is the height of the wall, measured from the grade in front of the wall to the top of the wall. 7.6 PERMANENT GROUNDWATER CONTROL Groundwater was encountered within about 20 to 26 feet bgs at the time of the explorations. The site soils are generally free draining. Permanent subdrainage is not considered necessary. 7.7 FILL MATERIALS, PLACEMENT, AND COMPACTION For the purposes of this report, the term Structural Fill is fill or backfill material placed and compacted within structural areas and within bearing zones of influence, which can include the materials described below. Ordinary Fill is not considered Structural Fill. We recommend the following materials and their respective recommended applications for use on this project, consistent with National Grid's Standard Specifications. Reference is made to acceptable materials described in the Massachusetts Highway Department (MHD) Standard Specifications for Highways and Bridges, as appropriate. %" Crushed Stone This Structural Fill material is recommended for use as a subgrade stabilization layer and as a base course beneath mats and slabs. %" Crushed Stone should be separated from all subgrade and fill soils with the use of a non -woven geotextile in all drainage or wet applications and below the seasonal high groundwater table. Filter fabric is also recommended in dry applications where fill is placed directly over Crushed Stone. When used as a stabilization layer or base course, the May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 10 geotextile should consist of Mirafi 1120N (or equivalent), and when used only as part of a drainage system, the geotextile should consist of Mirafi 140N (or equivalent). Crushed Stone should consist of durable crushed rock or durable crushed gravel stone, free of organics, deleterious materials, clay, ice, snow, and waste of any kind and meet the gradation tabulated herein. Material meeting MHD Section M2.01.4 (3/4 in.) is recommended for use as Crushed Stone. 1-%" Crushed Stone This Structural Fill material is recommended for use as a subgrade stabilization layer. 1-%" Crushed Stone should be separated from all subgrade and fill soils with the use of a non -woven geotextile in all drainage or wet applications and below the seasonal high groundwater table. Filter fabric is also recommended in dry applications where fill is placed directly over Crushed Stone. When used as a stabilization layer, the geotextile should consist of Mirafi 1120N (or equivalent), and when used only as part of a drainage system, the geotextile should consist of Mirafi 140N (or equivalent). Crushed Stone should consist of durable crushed rock or durable crushed gravel stone, free of organics, deleterious materials, clay, ice, snow, and waste of any kind and meet the gradation tabulated herein. Material meeting ASTM C-33, Type 4 is recommended for use as 1-%" Crushed Stone. Suh-Rasa Fill This Structural Fill material is recommended for use in the following applications: • Within 0.5 and 2.5 feet below final yard grade, • As backfill for foundation and retaining walls, • As base course beneath floor slabs and mats, and • In other free -draining, potentially frost susceptible applications where Crushed Stone is not required. Sub -base Fill should consist of clean sand, gravel and/or aggregate, free of concrete, brick, asphalt, cinder, organics, deleterious materials, ice, snow, and waste of any kind. The fine fraction should NOT consist of Clayey Silt, Silty Clay, Clay, Organic Silt, Organic Clay, or Peat. Water content by weight during compaction should not exceed ±2 percent of optimum moisture as determined by ASTM D 1557. Material meeting MHD Gravel Borrow, Section M1.03.0-1 with a maximum particle size of 1 inch is recommended for use as Sub -Base Fill. Suh-Gr;;dP Fill This Structural Fill material is recommended for use in the following applications: • Within the yard below a depth of 2.5 feet below final yard grade; • Within the bearing zone of footings; • Below slab -on -grade and mat base courses; and • In all other Structural Fill applications where Crushed Stone or Sub -base Fill are not required. Sub -grade Fill should consist of clean sand, gravel and/or aggregate, free of concrete, brick, asphalt, cinder, organics, deleterious materials, ice, snow, and waste of any kind. The fine fraction should NOT consist of Clayey Silt, Silty Clay, Clay, Organic Silt, Organic Clay or Peat. Water content by weight during compaction should not exceed ±2 percent of optimum moisture as determined by ASTM D 1557. Material meeting MHD Gravel Borrow, Section M1.03.0-1, Type b is recommended for use as Sub -grade Fill. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 11 The on -site soil may be used as an alternative to imported Subgrade Fill provided it meets the following criteria: • Granular (i.e., < 35% fines content) • Used only below the frost depth noted herein. • Screened to remove particle sizes over 4 inches. • Moisture conditioned to within 2% of optimum moisture content. • Can be placed and compacted to create a consistent, stable and uniform lift thickness, compacted to 95% of modified Proctor. • On -site mineral material, free of concrete, brick, asphalt, cinder, organics, deleterious materials, ice, snow, and waste of any kind. Ordinary Fill On -site soil that does not meet any of the above Structural Fill requirements is defined herein as Ordinary Fill can potentially be used on -site as fill to minimize the export of excess on -site soils. Ordinary Fill may be considered for use in the following applications: • Below a depth of 5 feet within yard and pavement areas. • Outside of the bearing zone of foundations, pads, and floors. • Within slopes shallower than 2H:1V. • Screened to remove particle sizes over 10 inches. • Moisture conditioned to within 3% of optimum moisture content. • Can be placed and compacted to create a consistent, stable and uniform lift thickness, compacted to 92% of modified Proctor. • On -site mineral material, free of concrete, brick, asphalt, cinder, organics, deleterious materials, ice, snow, and waste of any kind. Placement and Compaction Prior to placing new fills, all existing subgrades steeper than 5HAV should be benched to roughly horizontal to facilitate equipment travel and to avoid sloped material interfaces. Fill operations should start at the lowest bench. In addition, all loose materials and slough created at the edges of compacted lifts should be cut during placement of adjacent lifts to ensure uniform compaction. Fill slopes are recommended to be over -built horizontally, and then cut back to finish slope grade to remove the uncompacted edges of each lift. Representative samples of existing fills planned for reuse as Structural Fill should be obtained by the Geotechnical Engineer and tested for gradation prior to use. Representative samples of all fills and backfills for use on the project should be tested using the Modified Proctor method (ASTM D1557 and D4718) to determine maximum dry density and optimum moisture content. Field compaction should be measured prior to placing subsequent lifts. The following minimum compaction criteria are recommended: May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 12 Location and Depth of Fill(',',') Percent of Maximum Dry Density (ASTM D1557) Beneath Foundations and Slabs 95 Adjacent to exterior foundation walls 92 Includes area within bearing zone (1H:1V slope) of bottom of footings. The following paragraph regarding gravel fills does not apply to crushed stone or rip rap. The maximum loose lift thickness should be 12 inches for vibratory rollers and 6 inches for hand -operated equipment. Gravel fills containing greater than 30% coarse gravel (>3/4-inch size) may not be reliably tested in the field for compaction using conventional methods. A procedural compaction assessment method may be appropriate in the cases under the direction of the Geotechnical Engineer. 7.8 EXCAVATED MATERIAL REUSE AND DISPOSAL The on -site soils do not meet the specifications for Structural Fill. Recommendations for on -site material re -use is addressed in the Ordinary Fill and Subgrade Fill sections above. Re -use of the onsite soils will require careful planning and extra care to adjust and maintain moisture content to near the optimum moisture when stockpiled, and protect from wet weather with proper sloping and sealing during and following placement and compaction. The excavated materials should be regularly assessed bythe Geotechnical Engineerto ensure conformance with the intent of gradation specifications prior to reuse of any on -site materials as fill. Excavated material may be utilized on -site in the applications as described above at the discretion of the Geotechnical Engineer, provided that the material can be properly moisture conditioned and compacted to the recommended percent of the maximum dry density. Oversized materials (i.e., cobbles and boulders) may be encountered and excavated from the onsite materials, requiring screening, which should be planned and budgeted for. Protecting exposed soil from moisture and freezing will also be necessary. Covering stockpiles, diverting stormwater, and potentially aerated or watering overly moist or dry soil should also be planned and budgeted to meet the recommended range of optimum moisture content prior to placement and compaction. Excess material from the site that cannot be reused on site should be transported off -site in accordance with local, State, and federal regulations. GZA's Scope of Services did not include chemical screening or testing. Evidence of stained or environmentally -impacted soil and water was not observed during the explorations. It is recommended that characterization and disposal or discharge of soil and water originating from the work area be performed in accordance with National Grid's Environmental Procedure, EP-1- Waste Management; Environmental Guidance Document, EG-119 — Excavated Fill Materials and C&D Debris Management, and EG-1701 — Projects at Existing Substations, and in a manner acceptable to National Grid, as well as per applicable local, State, and Federal regulations. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 13 8.0 CONSTRUCTION It is recommended that construction follow National Grid's Standard Construction Specification. If final analysis by the EPC contractor shows that settlements can be controlled using shallow foundations, the following additional recommendations and considerations are provided below. 8.1 SUBGRADE PREPARATION Subgrade preparation serves to: • Densify existing materials, for use as bearing materials; • Improve otherwise suitable subgrade soils that become loosened or disturbed during excavations; • Assist the geotechnical engineer in assessing the suitability of the subgrades for their intended use; and • Identify additional weak, unstable, deleterious, or otherwise unsuitable subsurface conditions. Surface compaction is recommended to improve the relative density of the existing subgrade soils. Surface compaction is a high -intensity compaction procedure anticipated to improve the relative density of granular subgrade soils to a depth of 2 to 4 feet. All mat, foundation, and slab subgrades should be tracked and back -bladed, and then surface compacted with a minimum of 8 passes of a 10,000-pound or heavier smooth drum roller operating with full vibration. Surface compaction should be performed with the roller operating a maximum 2 miles per hour (3 feet per second). The Geotechnical Engineer should provide full-time observation and evaluation of surface compaction to confirm that the content, gradation, and relative density of the subgrade is consistent with the conditions described in the test boring logs and the foundation design parameters, and is sufficiently firm and stable to support subsequent fills and foundations. Based on the Geotechnical Engineer's assessment, either the subgrades will be approved, or further removal and evaluation of the subgrades will be required prior to approval of the subgrade for direct and indirect support of structural fills and foundations. 8.2 SUBGRADE STABILIZATION Once exposed, subgrade materials may become weakened by weather and construction traffic disturbance. Subgrade stabilization, if required, may consist of over -excavation to a deeper stable subgrade and replacement with structural fill and/or placement of coarse graded aggregate or crushed stone wrapped in non -woven geotextile or placement of a lean concrete working slab. The extent of subgrade stabilization can likely be reduced if the Contractor waits to excavate to the final subgrade surface until immediately before new fills or foundations are constructed. 8.3 SUBGRADE PROTECTION Following subgrade preparation and/or stabilization, the Contractor should employ means to protect the otherwise suitable bearing and stable subgrades. The exposed subgrade should be graded to promote positive runoff to a suitable drainage feature at all times during construction. The degree of subgrade disturbance will be dependent on the Contractor's means and methods, such as coordinating site activities around anticipated precipitation, and protecting exposed subgrades due to disturbance from excess moisture and construction equipment traffic. Prior to fill placement or foundation construction, subgrades should be covered and protected from freezing, either by blankets or excess fill material. Foundations and fill or backfill should not be placed over frozen subgrades. Where subgrades are frozen, as an alternative to removal and replacement with Structural Fill, frozen subgrades which were May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 14 otherwise suitable bearing and stable may be thawed by means approved by the Geotechnical Engineer, scarified, and re - compacted. 8.4 EXCAVATION SUPPORT Excavation slopes should be flattened or braced to maintain stability. All excavations should be performed in accordance with current OSHA requirements under the observation and responsibility of the project contractors. Construction site safety generally is the sole responsibility of the Contractor, who shall also be solely responsible for the means, methods, and sequencing of construction operations. Based on the granular nature of the soils within planned excavation depths, it is anticipated that the soil exposed in excavations would generally be classified as Type C soil in accordance with OSHA regulations, with a maximum slope inclination of 1.5HAV. Excavation slopes should be checked regularly for signs of instability and should be shored or flattened as required. Temporary slopes should be protected from surface run-off erosion by means of berms and swales located along the top of the slope and by means of plastic sheeting placed over the slope. It is recommended that if additional excavation support is required, the support of excavation (SOE) system should be designed by a Professional Engineer registered in the Commonwealth of Massachusetts for any excavation deeper than 8 feet. 8.5 CONSTRUCTION DEWATERING The site is underlain by generally free -draining soils; however, some temporary construction dewatering due to increased precipitation, should be anticipated during excavations for foundation subgrades. The contractor should be prepared to dewater as necessary to allow excavation, observation of the subgrade, and foundation/mat/slab construction in -the -dry. In general, we anticipate that pumping from localized sumps should be sufficient for construction dewatering of accumulated precipitations. Dewatering efforts must satisfy the requirements of local, State, and federal environmental and conservation authorities. It is also recommended that temporary control measures be implemented to reduce the amount of surface water (from rainfall runoff) from potentially entering and ponding in the excavations. Temporary measures should include, but not be limited to, construction of drainage ditches to divert and/or reduce the amount of surface water flowing over exposed subgrades during construction. Precipitation that results in standing water in the excavation should be removed immediately. The degree of moisture and construction disturbance will be dependent on the Contractor's means and methods, such as coordinating site activities around anticipated precipitation, and protecting exposed subgrades due to disturbance from excess moisture and construction equipment traffic. Additional time and expense should be planned and budgeted to protect moisture condition and stabilize the exposed sensitive subgrades. 8.6 PROTECTION OF EXISTING STRUCTURES The proposed excavations for foundations may be close to existing above- and below -ground structures. Particular care should be made to avoid undermining these features to remain. May 11, 2023 File No. 03.0035206.00 South Yarmouth LNG Facility — Proposed New LNG Tank Page / 15 All excavations should be restricted from encroaching into the 2H:1V line extending downward and outward from the bottom of existing footings/foundation and walls/slabs. Temporary cut slopes adjacent to existing footings/foundation and walls/slabs should be protected from erosion and storm water runoff. Vibration monitoring may be warranted to monitor potential disturbance to active facilities. Vibration monitoring should establish a low-level warning and a higher -level stop work vibration threshold, real-time reporting, and a contingency plan in the event that construction activities create unacceptable vibrations. TABLES TABLE 1- SUMMARY OF SUBSURFACE CONDITIONS LNG Tank Replacement South Yarmouth, Massachusetts Project No. 03.0035206.00 Approximate Soil and Groundwater Conditions Existing Ground Thickness Ground Top of Glacial Top of Glacial Top of Glacial Test Boring Surface Groundwater Cover (ft) Stratified Deposits - Stratified Deposits - Stratified Deposits - Bottom of Exploration (ft) Elevation Upper Sand Silty Clay Lower Sand (NAVD88in Feet) Depth BGS ELEV Depth BGS ELEV Depth BGS ELEV Depth BGS ELEV Depth BGS ELEV Depth BGS ELEV GZ-1 37 26.0 11 0.5 37 0.5 37 27.5 10 42.5 -6 101.0 -64 GZ-2 37 19.5 18 0.5 37 0.5 37 27.5 1 10 34.7 2 51.0 -14 GZ-3 38 23.2 14 0.5 37 0.5 37 29.7 8 34.6 3 51.0 -14 NOTES: 1 All depths are measured in feet below ground surface (bgs). Depths were estimated to the nearest 0.1 feet during drilling as presented on the boring logs. The accuracy of these values depends on drilling conditions and sample recovery and is on the order of ±1 foot. Ground surface elevation estimated using VlassGIS. 2 "NE" indicates stratum not encountered in exploration. "NM" indicates groundwater not measured. See test boring logs in Appendix B for additional information. TABLE 2 - RECOMMENDED GENERALIZED SUBSURFACE PROFILE OF EXISTING CONDITIONS GZ-1 eCd xydrostatic Depth)ft) El-(h) Design Condition ata 0 39 1 36 2 35 3 4 33 5 32 6 31 30 B 29 9 28 10 22 11 26 12 5 UNSAT 13 24 G1 10 23 15 22 16 21 1) 20 18 19 19 18 20 12 21 16 12 11 23 14 N 13 25 12 26 11 2) 0 28 9 29 8 30 31 6 3z 5 33 34 3 % 2 C1 % 1 3] 0 Is -1 39 -2 40 -3 41 -0 42 -5 13 -6 41 -J O6 9 O -10 48 -11 12 50 -23 51 14 52 -11 53-16 50 -12 55 -28 % -19 51 -20 58 -21 59 -22 60 -23 61 24 62 25 63 -26 AT 64 -z2 65 -28 66 -21 6) -30 69 32 -33 11 - a )2 G1 )3 36 0 37 TS 16 n a 42 n -0z 80 -03 81 dd az 4s 83 -06 8a -47 85 <8 % -09 81 50 88 51 89 52 % -53 91 92 -ss 93 56 94 -52 15 % 59 9) 60 % 61 62 1% LNG Tank Replacement South Yarmouth, Massachusetts Project No.03.0035206.00 GZ-2 GZ-3 Depth(ft) El-(ft) O—di e gntati< Depth(k) El-(k) 0 sl8n Hydrostatic Strata Condition Strata Condition 0 3) 0 8 1 36 1 3J 2 35 2 36 4 33 4 34 s 32 5 33 6 31 6 32 2 0 2 31 8 29 8 0 9 28 UNSAT 9 29 10 10 11 z6 11 22 UNSAT 11 25 11 26 13 24 G1 13 25 14 23 14 24 G1 15 22 15 23 16 21 16 22 17 20 17 21 18 19 18 20 19 18 19 19 20 1) 20 8 21 16 21 17 22 22 16 23 14 23 15 24 3 24 14 25 12 25 13 26 1112 27 ]0 27 11 28 9 28 30 29 8 29 9 30 > 30 31 6 C1 31 2 32 5 32 6 C1 33 5 34 3 34 35 2 AT 35 3 36 1 36 2 37 0 31 1 SAT 38 -1 38 0 39 -2 39 40 3 QD 2 41 -0 41 -3 42 5 42 -4 43 -6 G1 a3 -5 G1 44 -9 44 -6 45 a 4S 46 -9 46 -8 4) 30 4) 9 48 -11 48 -10 50 13 50 12 51 14 51 -13 TABLE 3 - RECOMMENDED FOUNDATION DESIGN PARAMETERS - GRANULAR SOIL LNG Tank Replacement South Yarmouth, Massachusetts Project No. 03.0035206.00 G1 Parameter Units Glacial Stratified Sand and New Structural Fill Interpreted Index Parameters USCS Symbol SP, SM, SW Presumed corrected SPT (N'60) bpf 20 Presumed Relative Density unitless Medium Dense Unit Weight, dry, gd pcf 105 Unit Weight, Total (Moist, Unsaturated), gm pcf 115 Unit Weight, Total (Saturated), g, pcf 130 Unit Weight, Effective / Buoyant (Saturated), ge pcf 68 Internal friction angle, f deg 34 NOTES: Bpf = blows per foot Pcf = pounds per cubic foot Deg = degrees TABLE 4 - RECOMMENDED FOUNDATION DESIGN PARAMETERS - COHESIVE SOIL LNG Tank Replacement South Yarmouth, Massachusetts Project No. 03.0035206.00 C1 Parameter Units Silty Clay Interpreted Index Parameters USCS symbol CL, CH Presumed corrected SPT (N'60) bpf 12 Cohesion, c / Undrained Shear Strength, su ksf 1.0 Cohesion, c / Undrained Shear Strength, su psf 1000 Consistency unitless stiff Liquid Limit, ILL % 45 Plastic Index, PI % 24 Plastic Limit, PL % 21 Unit Weight, dry, gd pcf 90 Unit Weight, Total (Moist, Unsaturated), g,„ pcf 105 Unit Weight, Total (Saturated), g, pcf 115 Unit Weight, Effective / Buoyant (Saturated), ge pcf 53 Internal friction angle, f' deg 25 NOTES: 1. Phi and cohesion are provided for performing separate total and effective stress analyses, respectively. It is not recommended to rely on both cohesion and friction in the same analysis. Bpf = blows per foot Ksf = kips per square foot Psf = pounds per square foot Pcf = pounds per cubic foot Deg = degrees FIGURES MAINs1 �� 6 - - Pointof (I 7�otiin. Yamoutli Q" ;po - J Rocks o �-44� F�� D _ ' � � DRIFT LN -✓ ALLA R O s O IY �I Oj� 11IPQ L V �SO�� C 2 ' y�TF QOclr - o Gy�� j rC c RD O m Lin Q cc ]] 1t?iuis Pond cc c 50 So 50����- N, \so D GERMA yh� 100 1�'✓ K 0 WHILES PATH A German hill 0 f Cuo; / N S 5T 11 4 ( BEpCO /1 1 Q ��/SHOP R D� O�tiSITE A 2 �POINSETTI �CE-AVE �. vimA 5� ��� 'CFo� PU11cl _ \ T C A A < -(;APTAIN NICKERgO 0 . Ap t— a N M l R ROW A �� Nr a 2T o T � M 2 O i u /h m CAPTAIN SMALL RD J h- c�;� P ,nci c A Q n �• `\ - ti r v z REGIONAL - PATH ���/` - BETTY'S (., LOTHROP RD a o \ 3� CAPTAIN Z N O � F MULFORD ST 50 h SIERRA WAY NO,IES SOUTH \ J Pine YARMOUTH Grove Cem ;:00 RO ❑ 0 1000, 2000' 4000' SCALE IN FEET 1" = 2000' MASSACHUSETTS SOURCE: N BASE MAP FROM THE FOLLOWING USGS QUADRANGLE MAP: DENNIS, MA (2021) DIGITAL TOPOGRAPHIC MAPS PROVIDED BY USGSSTORE.GOV. W E CONTOUR ELEVATIONS REFERENCE NAVD 88, CONTOURS ARE SHOWN IN FEET AT 10' INTERVALS S THE INFORMATION SHOWN ON THE DRAWING iS SOLELY FOR USE BY ,N-O,NAL GR.D OR THE NATIONAL GRIDS DESIGNATED REPRESENTATIVE FOR THE SPECIFIC PROJECT AND LOCATION QUADRANGLE LOCATION IDENTIFIED ON THE DRAWING. THE DRAWING SHALE NOT BE TRANSFERRED. REUSED. COPIED, OR ALTERED IN ANY MANNER FOR USE AT ANY OTHER LOCATION OR FOR ANY OTHER PURPOSE WITHOUT THE PRIOR WRITTEN CONSENT OF GZA AND NATIONAL GRID. ANY TRANSFER, REUSE, OR MODIFICATION TO THE DRAWING BY OTHERS, WITHOUT THE PRIOR WRITTEN EXPRESS CONSENT OF GZA AND NATIONAL GRID, WILL BE AT THE USER'S SOLE RISK AND WITHOUT ANY RISK OR LIABILITY TO GZA AND NATIONAL GRID. PREPARED BY: PREPARED FOR: LNG TANK REPLACEMENT GZA GeoEnvironmental , Inc. SOUTH YARMOUTH, MASSACH USETTS G� Engineers and Scientists n at i o n a l g r i d www.gza.com PRIORI MGR: JER REVIEWED BY: GRIM CHECKED BY: JFD FIGURE DESIGNED BY: IS DRAWN BY: ADD SCALE: AS NOTED LOCUS DATE: PROJECT NO. REVISION NO. MAY, 2023 03.0035206.00 0 SHEET NO. 1 OF 2 dr ar im F APPROX. LIMIT OF PROPOSED LNG TANK NOTES: 1. BASE MAP AERIAL IMAGERY OBTAINED FROM BING MAP SERVICES, ACCESSED IN MAY 2023. 2. THE LOCATIONS OF THE TEST BORINGS WERE DETERMINED BY TAPE MEASUREMENTS FROM EMSTING SITE FEATURES. THE LOCATIONS SHOULD BE CONSIDERED ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD USED. LEGEND INDICATESTESTBORINGSDRILLED BY GEOLOGIC EARTH GZ-1 EXPLORATIONS BETWEEN MARCH 20, 2023 AND MARCH 23, 2023, AND OBSERVED AND LOGGED BY GZA PERSONNEL 1 �- N y/ p y W E 0 30' 60' 120' 8 SCALE IN FEET 1" =60' LNG TANK REPLACEMENT WHITE PATH SOUTH YARMOUTH. MA 02664 EXPLORATION LOCATION PLAN eoEnNronmenUl, Inc. nation 2 APPENDIX A LIMITATIONS GEOTECHNICAL LIMITATIONS Page / 1 October 2018 USE OF REPORT 1. GZA GeoEnvironmentaI, Inc. (GZA) prepared this report on behalf of, and for the exclusive use of our Client for the stated purpose(s) and location(s) identified in the Proposal for Services and/or Report. Use of this report, in whole or in part, at other locations, or for other purposes, may lead to inappropriate conclusions; and we do not accept any responsibility for the consequences of such use(s). Further, reliance by any party not expressly identified in the contract documents, for any use, without our prior written permission, shall be at that party's sole risk, and without any liability to GZA. STANDARD OF CARE 2. GZA's findings and conclusions are based on the work conducted as part of the Scope of Services set forth in Proposal for Services and/or Report, and reflect our professional judgment. These findings and conclusions must be considered not as scientific or engineering certainties, but rather as our professional opinions concerning the limited data gathered during the course of our work. If conditions other than those described in this report are found at the subject location(s), or the design has been altered in any way, GZA shall be so notified and afforded the opportunity to revise the report,as appropriate, to reflect the unanticipated changed conditions . GZA's services were performed using the degree of skill and care ordinarily exercised by qualified professionals performing the same type of services, at the same time, under similar conditions, at the same or a similar property. No warranty, expressed or implied, is made. 4. In conducting our work, GZA relied upon certain information made available by public agencies, Client and/or others. GZA did not attempt to independently verify the accuracy or completeness of that information. Inconsistencies in this information which we have noted, if any, are discussed in the Report. SUBSURFACE CONDITIONS The generalized soil profile(s) provided in our Report are based on widely -spaced subsurface explorations and are intended only to convey trends in subsurface conditions. The boundaries between strata are approximate and idealized, and were based on our assessment of subsurface conditions. The composition of strata, and the transitions between strata, may be more variable and more complex than indicated. For more specific information on soil conditions at a specific location refer to the exploration logs. The nature and extent of variations between these explorations may not become evident until further exploration or construction. If variations or other latent conditions then become evident, it will be necessary to reevaluate the conclusions and recommendations of this report. In preparing this report, GZA relied on certain information provided by the Client, state and local officials, and other parties referenced therein which were made available to GZA at the time of our evaluation. GZA did not attempt to independently verify the accuracy or completeness of all information reviewed or received during the course of this evaluation. Water level readings have been made in test holes (as described in this Report) at the specified times and under the stated conditions. These data have been reviewed and interpretations have been made in this Report. Fluctuations in the level of the groundwater however occur due to temporal or spatial variations in areal recharge rates, soil heterogeneities, the presence of subsurface utilities, and/or natural or artificially induced perturbations. The water table encountered in the course of the work may differ from that indicated in the Report. Recommendations for foundation drainage, waterproofing, and moisture control address the conventional geotechnical engineering aspects of seepage control. These recommendations may not preclude an environment that allows the infestation of mold or other biological pollutants. GEOTECHNICAL LIMITATIONS Page / 2 October 2018 COMPLIANCE WITH CODES AND REGULATIONS 9. We used reasonable care in identifying and interpreting applicable codes and regulations. These codes and regulations are subject to various, and possibly contradictory, interpretations. Compliance with codes and regulations by other parties is beyond our control. COST ESTIMATES 10. Unless otherwise stated, our cost estimates are only for comparative and general planning purposes. These estimates may involve approximate quantity evaluations. Note that these quantity estimates are not intended to be sufficiently accurate to develop construction bids, or to predict the actual cost of work addressed in this Report. Further, since we have no control over either when the work will take place or the labor and material costs required to plan and execute the anticipated work, our cost estimates were made by relying on our experience, the experience of others, and other sources of readily available information. Actual costs may vary over time and could be significantly more, or less, than stated in the Report. SCREENING AND ANALYTICAL TESTING 11. We collected environmental samples at the locations identified in the Report. These samples were analyzed for the specific parameters identified in the report. Additional constituents, for which analyses were not conducted, may be present in soil, groundwater, surface water, sediment and/or air. Future Site activities and uses may result in a requirement for additional testing. 12. Our interpretation of field screening and laboratory data is presented in the Report. Unless otherwise noted, we relied upon the laboratory's QA/QC program to validate these data. 13. Variations in the types and concentrations of contaminants observed at a given location or time may occur due to release mechanisms, disposal practices, changes in flow paths, and/or the influence of various physical, chemical, biological or radiological processes. Subsequently observed concentrations may be other than indicated in the Report. ADDITIONAL SERVICES 14. GZA recommends that we be retained to provide services during any future: site observations, design, implementation activities, construction and/or property development/redevelopment. This will allow us the opportunity to: i) observe conditions and compliance with our design concepts and opinions; ii) allow for changes in the event that conditions are other than anticipated; iii) provide modifications to our design; and iv) assess the consequences of changes in technologies and/or regulations. APPENDIX B SUBSURFACE EXPLORATIONS a z FK O 07 U) W H W LU Q J a 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZA LNG Tank Replacement SHEET: 1 of 3 Z\p/) GeoEnvironmental, Inc. South Yarmouth, MA PROJECT NO: 35206 Engineers and Scientists REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan H. Datum: NA Drilling Co.: GeoLogic Rig Model: CME 750 Ground Surface Elev. ft): 37 Foreman: Matt Ferreira Drilling Method: Final Boring Depth ft): 101 V. Datum: NAVD88 Drive & Wash Date Start - Finish: 3/20/2023 - 3/23/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (lb.): 140 Sampler O.D. (in.): 2.0 3/23/23 13:30 2 Days 26 Well Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description w Depth Pen. Rec. Blows SPT (ft) (Core No. 6 in.) Value (Modified Burmister Classification) o R ft. (in) (in) (per 0-1 G-1 0.0-0.5 G-1: CRUSHED STONE 5 ------ G-2 0.5-5.5 G-2: Tan brown, fine to medium SAND, trace Silt, trace Root, moist 1 (SP) 2 5 S-1 5.5-7.5 24 12 3 6 14 S-1: Medium dense, tan brown, fine to medium SAND, trace Silt, moist 8 10 (SP) 10 S-2 9.0-11.0 24 9 6 9 18 S-2: Medium dense, tan brown, fine to medium SAND, trace Silt, moist 9 12 (SP) GLACIAL STRATIFIED 15 S-3 14.0-16.0 24 12 11 15 31 S-3: Dense, tan brown, fine SAND, little Silt, moist, stratified (SMf) DEPOSITS - SAND 16 20 20 S-4 19.0-21.0 24 14 10 14 34 S-4: Dense, tan brown, fine to medium SAND, trace Silt, miost (SP) 20 22 25 S-5 24.0-26.0 24 0 8 10 20 S-5: NO RECOVERY 10 10 27_5-------9_5 30 S-6 29.0-31.0 24 24 6 6 12 S-6: Top 4": Stiff, brown, SILT and CLAY, wet (ML) 6 8 Bottom 20": Gray, SILTY CLAY, wet (CL) GLACIAL STRATIFIED DEPOSITS - SILTY CLAY 35 S-7 34.0-36.0 24 20 6 6 16 S-7: Top 4": Very stiff, gray, SILTY CLAY, wet (CL) 1 - Borehole vacuum excavated to approximately 5.5 ft below ground surface on 3/20/2023. Borehole drilled on 3/20/2023. Temporary ground water monitoring well installed on 3/21/2023. Temporary well removed and borehole backfilled with soil cuttings on 3/23/2023. Y E 2 - Ground surface elevation estimated based on MassGIS LiDAR. See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZA than those present at the times the measurements were made. z O m LU w w J M LU 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZA LNG Tank Replacement SHEET: 2 of 3 GG—�` Z\�GeoEnvironmental, Inc. South Yarmouth, MA PROJECT NO: 35206 Engineers and Scientists REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan NA Drilling Co.: Geologic Rig Model: CME 750 Ground Surface Elev. ft): 37Foreman: FHDaattuum: Matt Ferreira Drilling Method: Final Boring Depth ft): 101 m: NAVD88 Drive & Wash Date Start - Finish:3/20/2023 - 3/23/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (lb.): 140 Sampler O.D. (in.): 2.0 3/23/23 13:30 2 Days 26 Well Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description Depth Pen. Rec. Blows SPT (ft) (Core No. (Modified Burmister Classification) o w R ft. (in) (in) (per6in.)Value 10 8 Bottom 16": Very stiff, gray, Silty CLAY, some fine Sand, little fine Gravel, wet (CL) GLACIAL STRATIFIED S-8 39.0-41.0 24 8 2 4 12 S-8: Stiff, gray, Silty CLAY, some fine Sand, little fine Gravel, wet (CL) DEPOSITS - SILTY CLAY 40 8 11 42.5 -5.5 45 S-9 44.0-46.0 24 8 7 13 31 S-9: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 18 26 3 50 S-10 49.0-51.0 24 9 16 18 34 S-10: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 16 16 55 S-11 54.0-56.0 24 12 9 10 21 S-11: Medium dense, tan brown, fine to medium SAND, trace Silt, wet 11 10 (SP) GLACIAL STRATIFIED DEPOSITS - SAND 60 S-12 59.0-61.0 24 12 12 14 30 S-12: Medium dense, tan brown, fine to medium SAND, trace Silt, wet 16 17 (SP) 65 S-13 64.0-66.0 24 12 13 14 32 S-13: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 18 18 70 S-14 69.0-71.0 24 11 16 14 30 S-14: Medium dense, tan brown, fine to medium SAND, trace Silt, wet 3 - Casing used to advance test boring to 46 ft bgs. Drilling mud was introduced into the borehole at approximately 46 ft below ground surface. a s Borehole advanced open -hole from 46 to 101 ft bgs. See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZA than those present at the times the measurements were made. z 0 m LU w w J M LU 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZ-1 LNG Tank Replacement SHEET: 3 of 3 GGG—�` Z\�GeoEnvironmental, Inc. South Yarmouth, MA PROJECT NO: 35206 Engineers and Scientists REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan NA Drilling Co.: Geologic Rig Model: CME 750 Ground Surface Elev. ft): 37Foreman: FHDaattuum: Matt Ferreira Drilling Method: Final Boring Depth ft): 101 m: NAVD88 Drive & Wash Date Start - Finish:3/20/2023 - 3/23/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (Ib.): 140 Sampler O.D. (in.): 2.0 3/23/23 13:30 2 Days 26 Well Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description Depth Pen. Rec. Blows SPT (ft) (Core No. (Modified Burmister Classification) o w R ft. (in) (in) (per6in.)Value 16 18 (SP) 75 S-15 74.0-76.0 24 9 13 15 31 S-15: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 16 20 80 S-16 79.0-81.0 24 9 13 15 29 S-16: Medium dense, tan brown, fine to medium SAND, trace fine 14 15 Gravel, trace Silt, wet (SP) 85 S-17 84.0-86.0 24 0 13 20 41 S-17: NO RECOVERY 21 25 GLACIAL STRATIFIED DEPOSITS - SAND 90 S-18 89.0-91.0 24 8 15 18 38 S-18: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 20 24 95 S-19 94.0-96.0 24 5 11 15 33 S-19: Dense, tan brown, fine to medium SAND, trace fine Gravel, trace 18 20 Silt, wet (SP) 100 S-20 99.0- 24 8 11 13 23 S-20: Tan brown, fine to medium SAND, trace Silt, wet (SP) 4 101.0 10 11 5 101 -64.0 End of exploration at 101 feet 105 4 - No recovery in sample S-20. 3-inch split spoon was redriven at sample depth with blows 10-14-17-23. 5 - A temporary groundwater monitoring well was installed to an approximate depth of 30 ft below ground surface. Ten feet of 2-inch diameter flush -joint PVC screen set from 20 to 30 ft bgs. PVC riser set from 20 ft bgs to ground surface. Annulus between PVC and borehole wall was left open. Temporary well removed and borehole backfilled with soil cuttings on 3/23/2023. See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZA than those present at the times the measurements were made. z O m LU w w J M LU 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZ-2 LNG Tank Replacement SHEET: 1 of 2 G� �Z\�)J� GeoEnvironmental, Inc. South Yarmouth, MA PROJECT NO: 35206 Engineers and Scientists REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan NA Drilling Co.: Geologic Rig Model: CME 750 Ground Surface Elev. ft): 37Foreman: FHDaattuum: Matt Ferreira Drilling Method: Final Boring Depth ft): 51 m: NAVD88 Drive & Wash Date Start - Finish:3/20/2023 - 3/22/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (Ib.): 140 Sampler O.D. (in.): 2.0 3/22/23 13:00 20 Minutes 19.5 30 Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description Depth Pen. Rec. Blows SPT (ft) (Core No. (Modified Burmister Classification) o w R ft. (in) (in) (per6in.)Value G-1 0.0-0.5 G-1: CRUSHED STONE � -11f G-2 0.5-5.5 G-2: Tan brown, fine to medium SAND, trace Silt, trace Root, moist 1 (SP) 2 5 S-1 5.5-7.5 24 11 2 5 10 S-1: Medium dense, tan brown, fine to medium SAND, trace Silt, moist 5 7 (SP) 10 S-2 9.0-11.0 24 9 5 9 18 S-2: Medium dense, tan brown, fine to medium SAND, trace Silt, moist 9 14 (SP) GLACIAL STRATIFIED 15 S-3 14.0-16.0 24 17 9 15 30 S-3: Medium dense, tan brown, fine SAND, some Silt, moist, stratified DEPOSITS - SAND 15 16 (SMf) 20 S-4 19.0-21.0 24 13 12 17 43 S-4: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 26 27 25 S-5 24.0-26.0 24 6 6 6 14 S-5: Medium dense, tan brown, fine to medium SAND, trace Silt, wet 8 11 (SP) 27.5 9.5 30 S-6 29.0-31.0 24 24 2 4 10 S-6: Stiff, dark gray, CLAY and SILT, wet (CL) 6 7 GLACIAL STRATIFIED U-1 31.0-33.0 24 24 PUSH U-1: Dark gray, CLAY and SILT, wet (CL) DEPOSITS - SILTY CLAY S-7 33.0-35.0 24 24 2 3 18 S-7: Top 20": Very stiff, dark gray, CLAY, trace fine Sand, wet (CL) 15 20 Bottom 4": Orange/tan brown, fine to medium SAND, trace Silt, wet (SP) 34.7 2.3 35 — -------- 1 - Borehole was vacuum excavated to an approximate depth of 5.5 ft below ground surface on 3/20/2023. Borehole drilled on 3/22/23. a s 2 - Ground surface elevation estimated based on MassGIS LiDAR. See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZ-2 than those present at the times the measurements were made. z 0 m LU w w J M LU 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZ-2 LNG Tank Replacement SHEET: 2 of 2 GGG—�` Z\�GeoEnvironmental, Inc. South Yarmouth, MA PROJECT NO: 35206 Engineers and Scientists REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan NA Drilling Co.: Geologic Rig Model: CME 750 Ground Surface Elev. ft): 37Foreman: FHDaattuum: Matt Ferreira Drilling Method: Final Boring Depth ft): 51 m: NAVD88 Drive & Wash Date Start - Finish:3/20/2023 - 3/22/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (Ib.): 140 Sampler O.D. (in.): 2.0 3/22/23 13:00 20 Minutes 19.5 30 Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description Depth Pen. Rec. Blows SPT (ft) (Core No. (Modified Burmister Classification) o w R ft. (in) (in) (per6in.)Value 40 S-8 39.0-41.0 24 3 8 14 25 S-8: Medium dense, tan brown, fine to medium SAND, trace Silt, wet 11 15 (SP) GLACIAL STRATIFIED DEPOSITS - SAND 45 S-9 44.0-46.0 24 12 15 13 32 S-9: Dense, tan brown, fine to medium SAND, trace Silt, wet (SP) 19 29 50 S-10 49.0-51.0 24 3 15 19 37 S-10: Tan brown to gray, fine to medium SAND, trace Silt, wet (SP) 3 18 23 4 51 -14.0 End of exploration at 51 feet 5 55 60 65 70 3 - No recovery in sample S-10. 3-inch split spoon redriven at sample depth with blows 5-9-11-14. 4 - Groundwater was measured following introduction of drilling fluid into the borehole and may not be representative of actual groundwater level. 5 - Upon completion, the borehole was backfilled with soil cuttings to ground surface. See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZ-2 than those present at the times the measurements were made. a z FK O 07 U) W H W LU Q J a 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZ-3 LNG Tank Replacement SHEET: 1 of 2 GG—\` Z\t/� GeoEnvironmental, Inc. South Yarmouth, MA PROJECT NO: 35206 Engineers and Scientists REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan H. Datum: NA Drilling Co.: GeoLogic Rig Model: CME 750 Ground Surface Elev. ft): 38 Foreman: Matt Ferreira Drilling Method: Final Boring Depth ft): 51 V. Datum: NAVD88 Drive & Wash Date Start - Finish:3/20/2023 - 3/23/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (lb.): 140 Sampler O.D. (in.): 2.0 3/23/23 14:30 15 Minutes 23.2 35 Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description w Depth Pen. Rec. Blows SPT (ft) (Core No. 6 in.) Value (Modified Burmister Classification) o R ft. (in) (in) (per 0-1 G-1 0.0-0.5 6 G-1: 6 inches Asphalt ------�7� G-2 0.5-5.5 60 G-2: Tan brown, fine to medium SAND, trace Silt, trace Root, moist 1 (SP) 2 3 5 S-1 5.5-7.5 24 15 4 4 10 S-1: Medium dense, tan brown, fine to medium SAND, trace Silt, moist 6 9 (SP) 10 S-2 9.0-11.0 24 13 2 5 13 S-2: Medium dense, tan brown, fine to medium SAND, trace Silt, moist 8 10 (SP) 15 S-3 14.0-16.0 24 13 4 8 18 S-3: Medium dense, tan brown, fine SAND, trace Silt, moist, stratified GLACIAL STRATIFIED 10 16 (SP) DEPOSITS - SAND 20 S-4 19.0-21.0 24 18 14 18 39 S-4: Top 12": Tan brown, fine SAND and SILT, moist (SMf) 21 25 Bottom 6": Tan brown, fine to medium SAND, trace Silt, moist (SP) 25 S-5 24.0-26.0 24 3 8 11 25 S-5: Medium dense, tan brown, fine to coarse SAND, trace Silt, wet 14 12 (SP) 30 S-6 29.0-31.0 24 16 10 10 20 S-6: Top 8": tan/brown, fine to medium SAND, wet (SP) 29.7 _ _ _ _ _ _ _8_3 10 10 Middle 6": Very stiff, tan/brown, SILTY CLAY, trace fine Sand, wet (CH) S-7 31.0-33.0 24 24 3 4 9 Bottom 2": Very stiff, dark gray, SILTY CLAY, wet (CH) 5 7 S-7: Stiff, dark gray, SILTY CLAY, wet (CH) GLACIAL DEPOSITS S SIILTYIFIED CLAY U-1 33.0-35.0 24 20 PUSH U-1: Dark gray, SILTY CLAY, wet (CH) 3.4 34_6_______— 35 S-8 35.0-37.0 24 14 2 6 29 S-8: Medium dense, tan brown, fine to medium SAND, trace Silt, wet 23 27 (SP) GLACIAL STRATIFIED DEPOSITS - SAND 1 - Borehole was vacuum excavated to an approximate depth of 5.5 ft below ground surface on 3/20/2023. Borehole drilled on 3/23/2023. 2 - Ground surface elevation estimated based on MassGIS LiDAR. Y E 3 - Bottom 1/2 inch of U-1 consisted of tan brown, fine to medium Sand, trace Silt, wet (SP) See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZ-3 than those present at the times the measurements were made. z O m LU w w J M LU 0 TEST BORING LOG GZA National Grid EXPLORATION NO.: GZ-3 GeoEnvironmental, Inc. LNG Tank Replacement SHEET: 2 of 2 G� �Z\�)J� Engineers and Scientists South Yarmouth, MA PROJECT NO: 35206 REVIEWED BY: Jay Ressler Logged By: Isabella Bernardi Type of Rig: ATV Boring Location: See Plan NA Drilling Co.: Geologic Rig Model: CME 750 Ground Surface Elev. ft): 38Foreman: FHDaattuum: Matt Ferreira Drilling Method: Final Boring Depth ft): 51 m: NAVD88 Drive & Wash Date Start - Finish:3/20/2023 - 3/23/2023 Hammer Type: Automatic Hammer Sampler Type: SS Groundwater Depth (ft.) Date Time Stab. Time Water Casin Hammer Weight (Ib.): 140 Sampler O.D. (in.): 2.0 3/23/23 14:30 15 Minutes 23.2 35 Hammer Fall (in.): 30 Sampler Length (in.): 24 Auger or Casing O.D./I.D Dia (in.): 4 Rock Core Size: N/A Depth Casing Blows/ Sam le Sample Description E Stratum o � Description Depth Pen. Rec. Blows SPT (ft) (Core No. (Modified Burmister Classification) o w R ft. (in) (in) (per6in.)Value 40 S-9 39.0-41.0 24 0 7 8 18 S-9: NO RECOVERY 10 9 45 S-10 44.0-46.0 24 5 7 12 33 S-10: Dense, tan brown, fine to coarse SAND, trace Silt, wet (SW) GLACIAL STRATIFIED DEPOSITS - SAND 21 27 50 S-11 49.0-51.0 24 6 25 26 55 S-11: Very dense, tan brown, fine to coarse SAND, trace Silt, trace fine 3 29 28 Gravel, wet (SW) 4 51 -13.0 End of exploration at 51 feet 55 60 65 70 75 3 - Groundwater was measured following introduction of drilling fluid and may not be representative of actual groundwater level. a s 4 - Upon completion, the borehole was backfilled with soil cuttings to ground surface. See Log Key for exploration of sample description and identification procedures. Stratification lines represent Exploration No.: approximate boundaries between soil and bedrock types. Actual transitions may be gradual. Water level readings have been made at the times and under the conditions stated. Fluctuations of groundwater may occur due to other factors GZ-3 than those present at the times the measurements were made. APPENDIX C LABORATORY TEST DATA h ielsch 195 Frances Avenue Cranston Rl, 02910 Phone: (401)-467-6454 Client Information: Project Information: GZA GeoEnvironmental Providence, RI LNG Tank Replacement South Yarmouth, MA Fax: (401)-467-2398 Project Manager: Jay Ressler Project Number: 03.0035206.00 DIVISION OF THE RISE GROUP thielsch.com Assigned By: Jay Ressler Summary Page: 1 of 1 Let's Build a Solid Foundation Collected By: Isabella Bernardi Report Date: 04.04.23 LABORATORY TESTING DATA SHEET, Report No.: 7423-C-163 Identification Tests Shear / Consolidation Tests As EST. Laboratory Log Depth Laboratory Received LoL PL Gravel Sand Fines Org. Dry Torvane — a� Failure of -o3 Strain Internal CR / and Boring ID Sample No. (ft) No. Moisture /° /o /o /o /o /o Gs unit or Type psf Criteria or T /o Friction RR Soil Description Content wt. pcf Test psf o/ Angle /- U-1 31-33 23-S-1381 Average Total Unit Weight (31-33') = 113.5 pcf 31.0 - Disturbed 31.5 31.5 - W-1381a I Grey CLAY & SILT 31.6 31.6 - SAVED SAVED 32.1 322.13 L-1381 25.1 38 19 Grey CLAY & SILT 332 5 C-1381 "> '� )1 4 O1' Grey CLAY & SILT 0.15 32.5 - SAVED SAVED 33.0 333.0 W-1381b Tv = 1.0 Grey CLAY & SILT Date Received: 03.27.23 Reviewed By:Uaic Reviewed: 04.C4.23 This report only LeWeS LO fteulS ftispmTm&or tested. No warranty, expressed or implied, is mu . This report shall not be reproduced, except in full, without prior written approval from the Agency, as defined in ASTM E329. 0 LIQUID AND PLASTIC LIMITS TEST REPORT 60 so 40 X W Z � 30 u d 20 10 0 Dashed line indicates the approximate upper limit boundary for natural o� �o< G 1O�- O� MLorOL MHorOH 0 10 20 30 40 50 60 70 80 90 100 110 LIQUID LIMIT 39 38.8 38.6 38.4 538.2 z z 38 z W F �7.8 37.6 37.4 37.2 37 5 6 7 8 9 10 20 25 30 40 NUMBER OF BLOWS MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS • Grey CLAY & SILT 38 19 19 Project No. 03.0035206.00 Client: GZA GeoEnvironmental Project: LNG Tank Replacement South Yarmouth, MA Source of Sample: Shelby Tubes Depth: 31-33' Sample Number: GZ-2 / U-1 Remarks: Figure 23-S-1381 Thielsch Engineering Inc. Cranston, RI Tested By: RB Checked By: Rebecca Roth Q E 0 CONSOLIDATION TEST REPORT 0.0 1.5 3.0 4.5 6.0 CU U) 7.5 U N 0- 9.0 10.5 12.0 13.5 15.0 0.02 0.016 0.012 U c� E 0.008 0.004 0 0.01 0.1 1 10 Applied Pressure - tsf MATERIAL DESCRIPTION USCS AASHTO Grey CLAY & SILT LL PI Sp. Gr. Overburden (tsf) Dry Dens. (pcf) Init. Final Moisture Init. Final Saturation Init. Final Void Ratio Init. Final Pc (tsf) C r 38 19 2.65 0 91.4 96.4 29.9 % 29.5 % 98.2 % 109.5 % 0.807 0.713 7.0 0.15 Preparation Process: Trimmed using cutting ring D2435 R Swell Press. Swell Method r (tsf) % Condition of Test: Saturated at 2 tsf B 0.02 Project No. 03.0035206.00 Client: GZA GeoEnvironmental Remarks: Project: LNG Tank Replacement End of Primary Loading South Yarmouth, MA Source: Shelby Tubes Depth: 31-33' Sample No.: GZ-2 / U-1 Checked By: Rebecca Roth Thielsch Engineering Inc. Title: Laboratory Manager Cranston, RI Figure C-1381 Tested By: SL Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes tan -0.1842 -0.1843 -0.1844 -0.1845 c 0.1846 c -0.1847 Of co-0.1848 0 -0.1849 -0.1850 -0.1851 -0.1852 -0.1847 -0.1846 -0.1845 -0.1844 c 0.1843 rn c c-0.1842 w co-0.1841 0 -0.1840 -0.1839 -0.1838 -0.1837 Dial Reading vs. Time Depth: 31-33' Sample Number: GZ-2 / U-1 0 1 2 t90 Square Root of Elapsed Time (min.) V V • 0 • 0 0 • 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr_ Load No.= 2 Load= 0.13 tsf D 0 =-0.1844 D90 =-0.1847 D 100 =-0.1847 T90 = 0.86 min. CV @ T90 0.0169 cm.2/sec. Load No.= 3 Load= 0.25 tsf DO =-0.1847 D90 =-0.1841 D 100 =-0.1840 T90 = 1.25 min. CV @ T90 0.0116 cm.2/sec. Figure C-1381 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.1829 -0.1826 -0.1823 -0.1820 c 0.1817 0) c @-0.1814 W cB-0.1811 0 -0.1808 -0.1805 -0.1802 -0.1799 -0.1796 -0.1792 -0.1788 -0.1784 c 0.1780 rn c c-0.1776 w co-0.1772 0 -0.1768 -0.1764 -0.1760 -0.1756 Dial Reading vs. Time Depth: 31-33' Sample Number: GZ-2 / U-1 • 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) t90 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr_ Load No.= 4 Load= 0.50 tsf DO =-0.1828 D90 =-0.1810 D 100 =-0.1808 T90 = 2.22 min. CV @ T90 0.0065 cm.2/sec. Load No.= 5 Load= 1.00 tsf D0 =-0.1801 D90 =-0.1772 D 100 =-0.1769 T90 = 1.52 min. CV @ T90 0.0094 cm.2/sec. Figure C-1381 Dial Reading vs. Time Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes Depth: 31-33' Sample Number: GZ-2 / U-1 -0.175t 4t Load No.= 6 Load= 2.00 tsf -0.174 DO =-0.1732 -0.17341 D50 =-0.1716 -0.172 D 100 =-0.1700 -0.171 T50 = 2.14 min. N-0.170 • CV @ T50 ( -0.169 0.0015 cm.2/sec. 0 -0.168 -0.167 -0.166 -0.165 0.1 1 10 100 1000 Elapsed Time (min.) t90 Load No.= 6 -0.175 Load= 2.00 tsf -0.174 - Dp =-0.1730 -0.173 D90 =-0.1714 -0.172 D 100 =-0.1712 T90 = 3.85 min. -0.171 rn c CU -0.170 CV @ T90 • m -0. — 0.0036 cm.2/sec. -0.168 -0.167 -0.166 -0.165 0 4 8 12 16 20 24 28 32 36 40 Square Root of Elapsed Time (min.) Figure C-1381 Thielsch Enaineerina Inc. Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.1765 -0.1764 -0.1763 -0.1762 c 0.1761 0) c -0.1760 Of cU-0.1759 0 -0.1758 -0.1757 -0.1756 -0.1755 tan Dial Reading vs. Time Depth: 31-33' Sample Number: GZ-2 / U-1 • 0 1 2 - - - - - - - -0.17550 -0.17525 -0.17500 -0.17475 c 0.17450 rn c c-0.17425 w co-0.17400 0 -0.17375 -0.17350 -0.17325 -0.17300 t90 Square Root of Elapsed Time (min.) V V 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr__ Load No.= 9 Load= 0.25 tsf DO =-0.1766 D90 =-0.1762 D 100 =-0.1761 T90 = 0.79 min. CV @ T90 0.0180 cm.2/sec. Load No.= 10 Load= 0.50 tsf DO =-0.1755 D90 =-0.1745 D 100 =-0.1744 T90 = 0.88 min. CV @ T90 0.0161 cm.2/sec. Figure C-1381 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.17265 -0.17250 -0.17235 -0.17220 c 0.17205 0) c @-0.17190 W Of cO-0.17175 0 -0.17160 -0.17145 -0.17130 -0.17115 -0.1701 -0.1698 -0.1695 -0.1692 c 0.1689 rn c c-0.1686 w co-0.1683 0 -0.1680 -0.1677 -0.1674 -0.1671 Dial Reading vs. Time Depth: 31-33' Sample Number: GZ-2 / U-1 • 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) t90 • • 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr_ Load No.= 11 Load= 1.00 tsf DO =-0.1725 D90 =-0.1718 D100 =-0.1718 T90 = 2.42 min. CV @ T90 0.0058 cm.2/sec. Load No.= 12 Load= 2.00 tsf DO =-0.1708 D90 =-0.1683 D 100 =-0.1680 T90 = 1.03 min. CV @ T90 0.0136 cm.2/sec. Figure C-1381 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes tan -0.166 -0.165 -0.164 -0.163 c -0.162 0) c m -0.161 W cB -0.160 0 -0.159 -0.158 -0.157 -0.156 Dial Reading vs. Time Depth: 31-33' Sample Number: GZ-2 / U-1 0 1 2 -0.1545 -0.1530 -0.1515 -0.1500 c 0.1485 rn c c-0.1470 w co-0.1455 0 -0.1440 -0.1425 -0.1410 -0.1395 t90 3 4 5 b / b J 1 U Square Root of Elapsed Time (min.) 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr_ Load No.= 13 Load= 4.00 tsf DO =-0.1653 D90 =-0.1615 D100 =-0.1611 T90 = 0.76 min. CV @ T90 0.0180 cm.2/sec. Load No.= 14 Load= 8.00 tsf DO =-0.1547 D90 =-0.1455 D 100 =-0.1445 T90 = 2.27 min. CV @ T90 0.0059 cm.2/sec. Figure C-1381 Dial Reading vs. Time Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes Depth: 31-33' Sample Number: GZ-2 / U-1 -0.140 t 4t Load No.= 15 -0.136 Load= 16.00 tsf DO =-0.1427 -0.132 D50 =-0.1266 -0.128 D 100 =-0.1106 -0.124 T50 = 0.44 min. rn N-0.120 CV @ T50 W -0.116 0.0065 cm.2/sec. 0 -0.112 41 Ca = 0.002 -0.108 Lei -0.104 -0.100 0.1 1 10 100 1000 Elapsed Time (min.) t90 Load No.= 15 -0.140 Load= 16.00 tsf -0.136 DO =-0.1377 0.132 D90 =-0.1156 -0.128 D 100 =-0.1132 T90 = 3.61 min. -0.124 rn CU -0.120 CV @ T90 (D m -0.116 0.0034 cm.2/sec. i5 -0.112 -0.108 -0.104 -0.100 0 4 8 12 16 20 24 28 32 36 40 Square Root of Elapsed Time (min.) Figure C-1381 Thielsch Enaineerina Inc. h ielsch 195 Frances Avenue Cranston Rl, 02910 Phone: (401)-467-6454 Client Information: Project Information: GZA GeoEnvironmental Providence, RI LNG Tank Replacement South Yarmouth, MA Fax: (401)-467-2398 Project Manager: Jay Ressler Project Number: 03.0035206.00 DIVISION OF THE RISE GROUP thielsch.com Assigned By: Jay Ressler Summary Page: 1 of 1 Let's Build a Solid Foundation Collected By: Isabella Bernardi Report Date: 04.04.23 LABORATORY TESTING DATA SHEET, Report No.: 7423-C-163 Identification Tests Shear / Consolidation Tests As EST. Laboratory Log Depth Laboratory Received PL Gravel Sand Fines Org. Dry Torvane — a� Failure of -o3 Strain Internal CR / and Boring ID Sample No. (ft) No. Moisture OL /° /o /o /o /o /o Gs unit or Type psf Criteria or T /o Friction RR Soil Description Content wt. pcf Test psf o/ Angle /- U-1 33-35 23-S-1382 Average Total Unit Weight (33-35') = 120.0 pcf 33.0 - Disturbed 33.6 33.6- W-1382a 33.6 Grey Silty CLAY 33.65 33.65 - C-1382 35.3 y �,,,, 0.17 Grey Silty CLAY 33.85 0.02 33.85 - L-1382 48.4 51 23 Grey Silty CLAY 33.95 34.15 - W 1382b >7 s Grey Silty CLAY 34.2 34.5 - Disturbed 34.8 Date Received: 03.27.23 Reviewed By:Uaic Reviewed: 04.C4.23 This report only LeWeS LO fteulS ftispmTm&or tested. No warranty, expressed or implied, is mu . This report shall not be reproduced, except in full, without prior written approval from the Agency, as defined in ASTM E329. E LIQUID AND PLASTIC LIMITS TEST REPORT 0 60 v Dashed line indicates the approximate vupper limit boundary for natural X v 50 & c o � 40 3 X 0 Z W Z L 30 u • N (v `0 � g a 20 O� ti v 10 E c`'"" ML or OL MH or OH 0 0 +� 0 10 20 30 40 50 60 70 80 90 100 110 v LIQUID LIMIT co N L 52.5 c 0 52.3 • tf 0 v 52.1 H 51.9 v � Y � 0 ~ Z & v 1.5 � 3 W ~ 1.3 a� t E 51.1 0 t 3 50.9 0 +� 50.7 c v u 50.5 5 6 7 8 9 10 20 25 30 40 *' NUMBER OF BLOWS 0 v MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS v • Grey Silty CLAY 51 23 28 V X N N Y Project No. 03.0035206.00 Client: GZA GeoEnvironmental Remarks: ° Project: LNG Tank Replacement a� m South Yarmouth, MA Y Source of Sample: Shelby Tubes Depth: 33-35' InSample Number: GZ-3 / U-1 Thielsch Engineering Inc. v v Cranston, RI Figure 23-L-1382 Tested By: RB Checked By: Rebecca Roth 0- E 0 Cc u a C C M a C U, E Cc C a a c C r- C C a U: t CONSOLIDATION TEST REPORT 1.5 3.0 4.5 6.0 7.5 CU U) 9.0 U N 0- 10.5 12.0 13.5 15.0 16.5 0.15 0.12 0.09 U c� E 0.06 0.03 0 0.01 0.1 10 Applied Pressure - tsf MATERIAL DESCRIPTION USCS AASHTO Grey Silty CLAY LL PI Sp. Gr. Overburdel (tsf) Dry Dens. (pcf) Moisture Saturation Void Ratio PC (tsf) C c Init. Final I Init. I Final I Init. I Final Init. Final 87.4 88.6 35.3 % 34.2 % 101.0 % 100.5 % 0.961 0.935 6.1 51 28 2.75 0.17 Preparation Process: Trimmed using cutting ring D2435 Swell Press. Swell Method Cr (tsf) % Condition of Test: Saturated at 2 tsf B 0.03 Project No. 03.0035206.00 Client: GZA GeoEnvironmental Remarks: Project: LNG Tank Replacement End of Primary Loading South Yarmouth, MA Source: Shelby Tubes Depth: 33-35' Sample No.: GZ-3 / U-1 Checked By: Rebecca Roth Thielsch Engineering Inc. Title: Laboratory Manager Cranston, RI Figure C-1382 Tested By: SL Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.04462 -0.04447 -0.04432 -0.04417 c 0.04402 0) c @-0.04387 W Of cO-0.04372 0 -0.04357 -0.04342 -0.04327 -0.04312 -0.04275 -0.04250 -0.04225 -0.04200 c 0.04175 rn c c-0.04150 w co-0.04125 0 -0.04100 -0.04075 -0.04050 -0.04025 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 • 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) t90 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr__ Load No.= 2 Load= 0.13 tsf DO =-0.0446 D90 =-0.0437 D 100 =-0.0436 T90 = 1.49 min. CV @ T90 0.0093 cm.2/sec. Load No.= 3 Load= 0.25 tsf DO =-0.0429 D90 =-0.0411 D 100 =-0.0410 T90 = 3.38 min. CV @ T90 0.0041 cm.2/sec. Figure C-1382 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes tan -0.0400 -0.0395 -0.0390 -0.0385 c 0.0380 c -0.0375 Of cU-0.0370 0 -0.0365 -0.0360 -0.0355 -0.0350 -0.0338 -0.0333 -0.0328 -0.0323 c 0.0318 rn c C-0.0313 w co-0.0308 0 -0.0303 -0.0298 -0.0293 -0.0288 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 0 1 2 t90 Square Root of Elapsed Time (min.) V V 1� 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr_ Load No.= 4 Load= 0.50 tsf DO =-0.0397 D90 =-0.0363 D100 =-0.0359 T90 = 5.59 min. CV @ T90 0.0024 cm.2/sec. Load No.= 5 Load= 1.00 tsf DO =-0.0345 D90 =-0.0305 D 100 =-0.0300 T90 = 1.60 min. CV @ T90 0.0084 cm.2/sec. Figure C-1382 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.027 -0.02E -0.02E -0.024 -0.022 -0.022 N re -0.021 0 -0.02r -0.01 £ -0.01E -0.017 0.1 t90 -0.027 -0.028 -0.025 -0.024 c -0.023 rn c N -0.022 (6 -0.021 i5 -0.020 -0.019 -0.018 -0.017 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 1 10 100 1000 Elapsed Time (min.) 0 4 8 12 16 20 24 28 32 36 40 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr_ Load No.= 6 Load= 2.00 tsf DO =-0.0293 D50 =-0.0253 D 100 =-0.0213 T50 = 0.13 min. CV @ T50 0.0244 cm.2/sec. �11 Load No.= 6 Load= 2.00 tsf DO =-0.0268 D90 =-0.0224 D 100 =-0.0219 T90 = 1.41 min. CV @ T90 0.0093 cm.2/sec. Figure C-1382 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.01863 -0.01864 -0.01865 -0.01866 c 0.01867 0) c @-0.01868 W Of cO-0.01869 0 -0.01870 -0.01871 -0.01872 -0.01873 0 t90 t90 -0.01869 -0.01870 -0.01871 -0.01872 c 0.01873 rn c c-0.01874 w co-0.01875 0 -0.01876 -0.01877 -0.01878 -0.01879 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 Square Root of Elapsed Time (min.) 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) ThiPlcrh FnninPPrinn Inr-_ Load No.= 9 Load= 0.25 tsf DO =-0.0186 D90 =-0.0187 D 100 =-0.0187 T90 = 0.64 min. CV @ T90 0.0202 cm.2/sec. Load No.= 10 Load= 0.50 tsf DO =-0.0187 D90 =-0.0187 D 100 =-0.0187 T90 = 0.10 min. CV @ T90 0.1294 cm.2/sec. Figure C-1382 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes -0.01874 -0.01875 -0.01876 -0.01877 c 0.01878 0) c @-0.01879 W Of cO-0.01880 0 -0.01881 -0.01882 -0.01883 -0.01884 -0.01888 -0.01892 -0.01896 -0.01900 c 0.01904 rn c c-0.01908 w co-0.01912 0 -0.01916 -0.01920 -0.01924 -0.01928 0 1.5 3 t90 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 4.5 6 7.5 9 10.5 12 13.5 15 Square Root of Elapsed Time (min.) 0 1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 Square Root of Elapsed Time (min.) Thielsch Enaineerina Inc. Load No.= 11 Load= 1.00 tsf DO =-0.0188 D90 =-0.0188 D 100 =-0.0188 T90 = 15.62 min. CV @ T90 0.0008 cm.2/sec. Load No.= 12 Load= 2.00 tsf DO =-0.0189 D90 =-0.0190 D100 =-0.0191 T90 = 1.98 min. CV @ T90 0.0065 cm.2/sec. Figure C-1382 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes t90 -0.017 -0.016 -0.015 -0.014 c -0.013 c co -0.012 a) Of CU -0.011 6 -0.010 -0.009 -0.008 -0.007 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) t90 -0.006 -0.004 -0.002 0.000 c �- 0.002 0) c m 0.004 a) N 0.006 0 • 0.008 • • • 0.010 • • • • • 0.012 0.014 0 1 2 3 4 5 6 7 8 9 10 Square Root of Elapsed Time (min.) Thielsch Enaineerina Inc. Load No.= 13 Load= 4.00 tsf DO =-0.0165 D90 =-0.0106 D100 =-0.0099 T90 = 2.00 min. CV @ T90 0.0064 cm.2/sec. Load No.= 14 Load= 8.00 tsf DO =-0.0055 D90 = 0.0061 D100 = 0.0074 T90 = 1.71 min. CV @ T90 0.0072 cm.2/sec. Figure C-1382 Project No.: 03.0035206.00 Project: LNG Tank Replacement Source of Sample: Shelby Tubes I 0 0.015 0.020 0.025 0.030 c �- 0.035 0) c m 0.040 a) ry N 0.045 0 0.050 0.055 0.060 0.065 Dial Reading vs. Time Depth: 33-35' Sample Number: GZ-3 / U-1 0.1 1 10 100 1000 Elapsed Time (min.) t90 0 4 8 12 16 20 24 28 32 36 40 Square Root of Elapsed Time (min.) Thielsch Enaineerina Inc. Load No.= 15 Load= 16.00 tsf DO = 0.0128 D50 = 0.0305 D100 = 0.0481 T50 = 0.55 min. CV @ T50 0.0047 cm.2/sec. Ca = 0.004 Load No.= 15 Load= 16.00 tsf DO = 0.0160 D90 = 0.0404 D100 = 0.0432 T90 = 2.92 min. CV @ T90 0.0039 cm.2/sec. Figure C-1382 GEOTECHNICAL ENVIRONMENTAL GZA GeoEnvironmental, Inc. HIGH GROUND -WATER LEVEL COMPUTATION Site Location: Owner: Contractor: Notes: STEP 1 Measure depth to water table to nearest 1/10 ft. (depth is in feet below land surface) STEP 2 Using Water -Level Range Zone and Index Well Map locate site and determine: A) Appropriate index well B) Water -level range zone Date: Permit: Phone: Phone: Date: STEP 3 Using monthly "Current Water Resources Conditions" determine current depth to water level for index well. m m/yy STEP 4 Using Table of Potential Water Level Rise for index well (STEP 2A), current depth to water level for index well (STEP 3), and water -level zone (STEP 213) determine water -level adjustment. STEP 5 Estimate depth to high water by subtracting the water -level adjustment (STEP 4) from measured depth to water level at site (STEP 1). mm/dd/yy 0 feet below Is 0 0 NOTE* Tables 1-9 "Potential Water -Level Rise" are attached as worksheets to this file. monthly index well data: www.capecodcommission.org/wells.html U.S. DEPARTMENT OFTHE INTERIOR U.S. GEOLOGICAL SURVEY .'_in mgei .wi.. COMMONWEALTH OF MASS ACHUSETTS OFFICE OFTHE STATE GEOLOGIST AND EXECUTIVE OFFICE OF ENERGY AND ENVIRONMENTAL AFFAIRS OPEN -FILE REPORT 20061260.E (SHEET4of19) DENNIS QUADRANGLE scAle I:zluoo .,�rn�m u.s. wnneia Isal. La n ��.•wc p a�W fminnWak.lYlOa. Nep wa. kmrvtl. v�.v.. W. 6c•+n rrnmid. �i6Nc mlin<m: OaR'I[R MpJlwwwgeo.�inuvss Nuhlalegwloge✓aame_mapxhw CONroUR INTCRVAL IOILCr mu ef. Suriicial Geologic Map of the Dennis Quadrangle, Massachusetts Compiled by Byron D. Stone and Mary L. DiGiaconno-Cohen 2009 APPENDIX D is DP-1 SubCat Reach Pon Link Routing Diagram for Existing Prepared by Tighe & Bond, Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Existing Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 2 Rainfall Events Listing Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1-Year Type III 24-hr Default 24.00 1 2.84 2 2 2-Year Type III 24-hr Default 24.00 1 3.35 2 3 5-Year Type III 24-hr Default 24.00 1 4.18 2 4 10-Year Type III 24-hr Default 24.00 1 4.87 2 5 25-Year Type III 24-hr Default 24.00 1 5.82 2 6 50-Year Type III 24-hr Default 24.00 1 6.54 2 7 100-Year Type III 24-hr Default 24.00 1 7.28 2 Existing Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 3 Area Listing (all nodes) Area CN Description (acres) (subcatchm ent-num hers) 2.665 96 Gravel surface, HSG A (1S) 0.212 98 Paved parking, HSG A (1S) 5.841 30 Woods, Good, HSG A (1S) 8.719 52 TOTAL AREA Existing Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 4 Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 8.719 HSG A 1S 0.000 HSG B 0.000 HSG C 0.000 HSG D 0.000 Other 8.719 TOTAL AREA Existing Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 5 Ground Covers (all nodes) HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 2.665 0.000 0.000 0.000 0.000 2.665 Gravel surface 1S 0.212 0.000 0.000 0.000 0.000 0.212 Paved parking 1S 5.841 0.000 0.000 0.000 0.000 5.841 Woods, Good 1S 8.719 0.000 0.000 0.000 0.000 8.719 TOTAL AREA Existing Type 11124-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 6 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>0.07" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=0.12 cfs 0.053 of Reach DP-1: Inflow=0.12 cfs 0.053 of Outflow=0.12 cfs 0.053 of Total Runoff Area = 8.719 ac Runoff Volume = 0.053 of Average Runoff Depth = 0.07" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type 11124-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 1 S: Runoff = 0.12 cfs @ 13.99 hrs, Volume= 0.053 af, Depth> 0.07" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 0.07" for 1-Year event Inflow = 0.12 cfs @ 13.99 hrs, Volume= 0.053 of Outflow = 0.12 cfs @ 13.99 hrs, Volume= 0.053 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Existing Type 11124-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 8 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>0.17" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=0.46 cfs 0.124 of Reach DP-1: Inflow=0.46 cfs 0.124 of Outflow=0.46 cfs 0.124 of Total Runoff Area = 8.719 ac Runoff Volume = 0.124 of Average Runoff Depth = 0.17" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type 11124-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 1 S: Runoff = 0.46 cfs @ 12.71 hrs, Volume= 0.124 af, Depth> 0.17" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 0.17" for 2-Year event Inflow = 0.46 cfs @ 12.71 hrs, Volume= 0.124 of Outflow = 0.46 cfs @ 12.71 hrs, Volume= 0.124 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Existing Type 11124-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 10 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>0.40" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=1.68 cfs 0.291 of Reach DP-1: Inflow=1.68 cfs 0.291 of Outflow=1.68 cfs 0.291 of Total Runoff Area = 8.719 ac Runoff Volume = 0.291 of Average Runoff Depth = 0.40" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type 11124-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment 1 S: Runoff = 1.68 cfs @ 12.57 hrs, Volume= 0.291 af, Depth> 0.40" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 0.40" for 5-Year event Inflow = 1.68 cfs @ 12.57 hrs, Volume= 0.291 of Outflow = 1.68 cfs @ 12.57 hrs, Volume= 0.291 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Existing Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 12 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>0.65" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=3.20 cfs 0.470 of Reach DP-1: Inflow=3.20 cfs 0.470 of Outflow=3.20 cfs 0.470 of Total Runoff Area = 8.719 ac Runoff Volume = 0.470 of Average Runoff Depth = 0.65" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 13 Summary for Subcatchment 1 S: Runoff = 3.20 cfs @ 12.51 hrs, Volume= 0.470 af, Depth> 0.65" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 0.65" for 10-Year event Inflow = 3.20 cfs @ 12.51 hrs, Volume= 0.470 of Outflow = 3.20 cfs @ 12.51 hrs, Volume= 0.470 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Existing Type 11124-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 14 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>1.05" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=5.90 cfs 0.766 of Reach DP-1: Inflow=5.90 cfs 0.766 of Outflow=5.90 cfs 0.766 of Total Runoff Area = 8.719 ac Runoff Volume = 0.766 of Average Runoff Depth = 1.05" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type 11124-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 15 Summary for Subcatchment 1 S: Runoff = 5.90 cfs @ 12.47 hrs, Volume= 0.766 af, Depth> 1.05" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 1.05" for 25-Year event Inflow = 5.90 cfs @ 12.47 hrs, Volume= 0.766 of Outflow = 5.90 cfs @ 12.47 hrs, Volume= 0.766 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Existing Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 16 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>1.41" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=8.28 cfs 1.023 of Reach DP-1: Inflow=8.28 cfs 1.023 of Outflow=8.28 cfs 1.023 of Total Runoff Area = 8.719 ac Runoff Volume = 1.023 of Average Runoff Depth = 1.41" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 17 Summary for Subcatchment 1 S: Runoff = 8.28 cfs @ 12.45 hrs, Volume= 1.023 af, Depth> 1.41" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 1.41" for 50-Year event Inflow = 8.28 cfs @ 12.45 hrs, Volume= 1.023 of Outflow = 8.28 cfs @ 12.45 hrs, Volume= 1.023 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Existing Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 18 Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=379,799 sf 2.44% Impervious Runoff Depth>1.80" Flow Length=1,115' Tc=27.7 min CN=52 Runoff=10.96 cfs 1.311 of Reach DP-1: Inflow=10.96 cfs 1.311 of Outflow=10.96 cfs 1.311 of Total Runoff Area = 8.719 ac Runoff Volume = 1.311 of Average Runoff Depth = 1.80" 97.56% Pervious = 8.507 ac 2.44% Impervious = 0.212 ac Existing Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment 1 S: Runoff = 10.96 cfs @ 12.43 hrs, Volume= 1.311 af, Depth> 1.80" Routed to Reach DP-1 : Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Area (sf) CN Description 116,096 96 Gravel surface, HSG A 214,996 30 Woods, Good, HSG A 9,249 98 Paved parking, HSG A 39,458 30 Woods, Good, HSG A 379,799 52 Weighted Average 370,550 97.56% Pervious Area 9,249 2.44% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 10.9 50 0.0260 0.08 Sheet Flow, Woods Woods: Light underbrush n= 0.400 P2= 3.35" 3.2 149 0.0235 0.77 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fps 9.3 861 0.0058 1.55 Shallow Concentrated Flow, Impervious Paved Kv= 20.3 fps 4.3 55 0.0018 0.21 Shallow Concentrated Flow, Woods Woodland Kv= 5.0 fos 27.7 1,115 Total Summary for Reach DP-1: Inflow Area = 8.719 ac, 2.44% Impervious, Inflow Depth > 1.80" for 100-Year event Inflow = 10.96 cfs @ 12.43 hrs, Volume= 1.311 of Outflow = 10.96 cfs @ 12.43 hrs, Volume= 1.311 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs CB 4S � 8P Trench Drain CB CB CB-1 Dt 1 CB CB 6S 9P 12P 6s Trench Drain DMH 2 c6 c6 CB-2 DMH 3 A WTU ca Infiltratior Basin #1 Trench Drain 41 DP-1 Subcat Reach Pon Link Proposed Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 2 Rainfall Events Listing Event# Event Storm Type Curve Mode Duration B/B Depth AMC Name (hours) (inches) 1 1-Year Type III 24-hr Default 24.00 1 2.84 2 2 2-Year Type III 24-hr Default 24.00 1 3.35 2 3 5-Year Type III 24-hr Default 24.00 1 4.18 2 4 10-Year Type III 24-hr Default 24.00 1 4.87 2 5 25-Year Type III 24-hr Default 24.00 1 5.82 2 6 50-Year Type III 24-hr Default 24.00 1 6.54 2 7 100-Year Type III 24-hr Default 24.00 1 7.28 2 Proposed Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 3 Area Listing (all nodes) Area CN Description (acres) (subcatchm ent-num bers) 2.430 39 >75% Grass cover, Good, HSG A (1S, 2S, 6S) 4.066 96 Gravel surface, HSG A (1S, 2S, 3S, 4S, 5S) 0.338 98 Paved parking, HSG A (3S, 5S) 1.885 30 Woods, Good, HSG A (1S, 2S) 8.719 66 TOTAL AREA Proposed Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 4 Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 8.719 HSG A 1 S, 2S, 3S, 4S, 5S, 6S 0.000 HSG B 0.000 HSG C 0.000 HSG D 0.000 Other 8.719 TOTAL AREA Proposed Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 5 Ground Covers (all nodes) HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 2.430 0.000 0.000 0.000 0.000 2.430 >75% Grass cover, Good 1S, 2S, 6S 4.066 0.000 0.000 0.000 0.000 4.066 Gravel surface 1 S, 2S, 3S, 4S, 5S 0.338 0.000 0.000 0.000 0.000 0.338 Paved parking 3S, 5S 1.885 0.000 0.000 0.000 0.000 1.885 Woods, Good 1S, 2S 8.719 0.000 0.000 0.000 0.000 8.719 TOTAL AREA Proposed Prepared by Tighe & Bond HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Printed 12/10/2025 Page 6 Pipe Listing (all nodes) Line# Node In -Invert Out -Invert Length Slope n Width Diam/Height Inside -Fill Node Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches) Name 1 6P 33.00 32.75 50.0 0.0050 0.013 0.0 12.0 0.0 2 7P 33.00 30.00 131.0 0.0229 0.013 0.0 18.0 0.0 3 8P 34.66 33.50 58.0 0.0200 0.013 0.0 12.0 0.0 4 9P 34.10 33.18 168.0 0.0055 0.013 0.0 8.0 0.0 5 11 P 30.34 29.90 91.7 0.0048 0.013 0.0 18.0 0.0 6 12P 29.87 29.40 115.2 0.0041 0.013 0.0 18.0 0.0 7 13P 29.31 28.54 155.2 0.0050 0.013 0.0 24.0 0.0 8 14P 28.54 28.46 72.0 0.0011 0.013 0.0 24.0 0.0 9 15P 30.50 30.21 57.7 0.0050 0.013 0.0 24.0 0.0 Proposed Type III 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 7 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>0.05" Tc=6.0 min CN=49 Runoff=0.02 cfs 0.012 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>0.05" Tc=6.0 min CN=49 Runoff=0.01 cfs 0.008 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>2.39" Tc=6.0 min CN=96 Runoff=3.20 cfs 0.248 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>2.39" Tc=6.0 min CN=96 Runoff=1.76 cfs 0.137 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>2.39" Tc=6.0 min CN=96 Runoff=3.56 cfs 0.276 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth=0.00" Tc=6.0 min CN=39 Runoff=0.00 cfs 0.000 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak Elev=28.37' Storage=8,800 cf Inflow=8.53 cfs 0.680 of Discarded=1.39 cfs 0.679 of Primary=0.00 cfs 0.000 of Outflow=1.39 cfs 0.679 of Pond 6P: CB-1 Peak EIev=33.07' Inflow=0.01 cfs 0.008 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=0.01 cfs 0.008 of Pond 7P: Trench Drain Peak EIev=33.97' Inflow=3.20 cfs 0.248 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=3.20 cfs 0.248 of Pond 8P: Trench Drain Peak EIev=35.51' Inflow=1.76 cfs 0.137 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=1.76 cfs 0.137 of Pond 9P: Trench Drain Peak EIev=34.10' Inflow=0.00 cfs 0.000 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.00 cfs 0.000 of Pond 11P: DMH 1 Peak EIev=31.06' Inflow=1.76 cfs 0.144 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=1.76 cfs 0.144 of Pond 12P: DMH 2 Peak EIev=30.61' Inflow=1.76 cfs 0.144 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=1.76 cfs 0.144 of Pond 13P: DMH 3 Peak EIev=30.47' Inflow=5.33 cfs 0.420 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=5.33 cfs 0.420 of Pond 14P: WQTU Peak EIev=29.95' Inflow=5.33 cfs 0.420 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=5.33 cfs 0.420 of Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 8 Pond 15P: C13-2 Peak Elev=31.47' Inflow=3.56 cfs 0.276 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=3.56 cfs 0.276 of Total Runoff Area = 8.719 ac Runoff Volume = 0.680 of Average Runoff Depth = 0.94" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 1 S: Runoff = 0.02 cfs @ 15.05 hrs, Volume= 0.012 af, Depth> 0.05" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 0.01 cfs @ 15.05 hrs, Volume= 0.008 af, Depth> 0.05" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 3.20 cfs @ 12.09 hrs, Volume= 0.248 af, Depth> 2.39" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 10 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 1.76 cfs @ 12.09 hrs, Volume= 0.137 af, Depth> 2.39" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 3.56 cfs @ 12.09 hrs, Volume= 0.276 af, Depth> 2.39" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type 11124-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment 6S: 6s Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 1-Year Rainfall=2.84" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 1-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 0.94" for 1-Year event Inflow = 8.53 cfs @ 12.09 hrs, Volume= 0.680 of Outflow = 1.39 cfs @ 12.56 hrs, Volume= 0.679 af, Atten= 84%, Lag= 28.6 min Discarded = 1.39 cfs @ 12.56 hrs, Volume= 0.679 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 28.37' @ 12.56 hrs Surf.Area= 7,261 sf Storage= 8,800 cf Plug -Flow detention time= 43.7 min calculated for 0.679 of (100% of inflow) Center -of -Mass det. time= 42.8 min ( 828.5 - 785.6 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type Ill 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 12 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=1.39 cfs @ 12.56 hrs HW=28.37' (Free Discharge) L1=Exfiltration (Exfiltration Controls 1.39 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 0.05" for 1-Year event Inflow = 0.01 cfs @ 15.05 hrs, Volume= 0.008 of Outflow = 0.01 cfs @ 15.05 hrs, Volume= 0.008 af, Atten= 0%, Lag= 0.0 min Primary = 0.01 cfs @ 15.05 hrs, Volume= 0.008 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 33.07' @ 15.05 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.01 cfs @ 15.05 hrs HW=33.07' (Free Discharge) L1=Culvert (Barrel Controls 0.01 cfs @ 0.82 fps) Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 13 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91% Impervious, Inflow Depth > 2.39" for 1-Year event Inflow = 3.20 cfs @ 12.09 hrs, Volume= 0.248 of Outflow = 3.20 cfs @ 12.09 hrs, Volume= 0.248 af, Atten= 0%, Lag= 0.0 min Primary = 3.20 cfs @ 12.09 hrs, Volume= 0.248 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 33.97' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=3.12 cfs @ 12.09 hrs HW=33.96' (Free Discharge) L1=Culvert (Inlet Controls 3.12 cfs @ 2.63 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 2.39" for 1-Year event Inflow = 1.76 cfs @ 12.09 hrs, Volume= 0.137 of Outflow = 1.76 cfs @ 12.09 hrs, Volume= 0.137 af, Atten= 0%, Lag= 0.0 min Primary = 1.76 cfs @ 12.09 hrs, Volume= 0.137 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 35.51' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=1.72 cfs @ 12.09 hrs HW=35.49' (Free Discharge) L1=Culvert (Inlet Controls 1.72 cfs @ 2.45 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth = 0.00" for 1-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 14 Peak Elev= 34.10' @ 0.00 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=34.10' (Free Discharge) L1=Culvert ( Controls 0.00 cfs) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 0.51" for 1-Year event Inflow = 1.76 cfs @ 12.09 hrs, Volume= 0.144 of Outflow = 1.76 cfs @ 12.09 hrs, Volume= 0.144 af, Atten= 0%, Lag= 0.0 min Primary = 1.76 cfs @ 12.09 hrs, Volume= 0.144 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.06' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=1.72 cfs @ 12.09 hrs HW=31.05' (Free Discharge) L1=Culvert (Barrel Controls 1.72 cfs @ 3.06 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 0.51" for 1-Year event Inflow = 1.76 cfs @ 12.09 hrs, Volume= 0.144 of Outflow = 1.76 cfs @ 12.09 hrs, Volume= 0.144 af, Atten= 0%, Lag= 0.0 min Primary = 1.76 cfs @ 12.09 hrs, Volume= 0.144 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.61' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=1.72 cfs @ 12.09 hrs HW=30.60' (Free Discharge) L1=Culvert (Barrel Controls 1.72 cfs @ 2.97 fps) Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 15 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 1.06" for 1-Year event Inflow = 5.33 cfs @ 12.09 hrs, Volume= 0.420 of Outflow = 5.33 cfs @ 12.09 hrs, Volume= 0.420 af, Atten= 0%, Lag= 0.0 min Primary = 5.33 cfs @ 12.09 hrs, Volume= 0.420 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.47' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=5.19 cfs @ 12.09 hrs HW=30.45' (Free Discharge) L1=Culvert (Barrel Controls 5.19 cfs @ 4.05 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 1.06" for 1-Year event Inflow = 5.33 cfs @ 12.09 hrs, Volume= 0.420 of Outflow = 5.33 cfs @ 12.09 hrs, Volume= 0.420 af, Atten= 0%, Lag= 0.0 min Primary = 5.33 cfs @ 12.09 hrs, Volume= 0.420 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 29.95' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=5.19 cfs @ 12.09 hrs HW=29.92' (Free Discharge) L1=Culvert (Barrel Controls 5.19 cfs @ 3.15 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 2.39" for 1-Year event Inflow = 3.56 cfs @ 12.09 hrs, Volume= 0.276 of Outflow = 3.56 cfs @ 12.09 hrs, Volume= 0.276 af, Atten= 0%, Lag= 0.0 min Primary = 3.56 cfs @ 12.09 hrs, Volume= 0.276 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 1-Year Rainfall=2.84" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 16 Peak Elev= 31.47' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=3.47 cfs @ 12.09 hrs HW=31.45' (Free Discharge) L1=Culvert (Barrel Controls 3.47 cfs @ 3.43 fps) Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 17 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>0.14" Tc=6.0 min CN=49 Runoff=0.07 cfs 0.031 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>0.14" Tc=6.0 min CN=49 Runoff=0.05 cfs 0.020 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>2.90" Tc=6.0 min CN=96 Runoff=3.83 cfs 0.300 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>2.90" Tc=6.0 min CN=96 Runoff=2.11 cfs 0.165 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>2.90" Tc=6.0 min CN=96 Runoff=4.26 cfs 0.334 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth>0.00" Tc=6.0 min CN=39 Runoff=0.00 cfs 0.000 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak Elev=28.71' Storage=11,359 cf Inflow=10.20 cfs 0.851 of Discarded=1.47 cfs 0.850 of Primary=0.00 cfs 0.000 of Outflow=1.47 cfs 0.850 of Pond 6P: CB-1 Peak Elev=33.13' Inflow=0.05 cfs 0.020 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=0.05 cfs 0.020 of Pond 7P: Trench Drain Peak EIev=34.09' Inflow=3.83 cfs 0.300 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=3.83 cfs 0.300 of Pond 8P: Trench Drain Peak EIev=35.65' Inflow=2.11 cfs 0.165 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=2.11 cfs 0.165 of Pond 9P: Trench Drain Peak EIev=34.12' Inflow=0.00 cfs 0.000 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.00 cfs 0.000 of Pond 11P: DMH 1 Peak EIev=31.14' Inflow=2.11 cfs 0.186 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=2.11 cfs 0.186 of Pond 12P: DMH 2 Peak EIev=30.68' Inflow=2.11 cfs 0.186 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=2.11 cfs 0.186 of Pond 13P: DMH 3 Peak EIev=30.60' Inflow=6.37 cfs 0.520 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=6.37 cfs 0.520 of Pond 14P: WQTU Peak EIev=30.10' Inflow=6.37 cfs 0.520 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=6.37 cfs 0.520 of Proposed Type 11124-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 18 Pond 15P: C13-2 Peak Elev=31.57' Inflow=4.26 cfs 0.334 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=4.26 cfs 0.334 of Total Runoff Area = 8.719 ac Runoff Volume = 0.851 of Average Runoff Depth = 1.17" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 19 Summary for Subcatchment 1 S: Runoff = 0.07 cfs @ 12.47 hrs, Volume= 0.031 af, Depth> 0.14" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 0.05 cfs @ 12.47 hrs, Volume= 0.020 af, Depth> 0.14" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 3.83 cfs @ 12.09 hrs, Volume= 0.300 af, Depth> 2.90" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 20 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 2.11 cfs @ 12.09 hrs, Volume= 0.165 af, Depth> 2.90" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 4.26 cfs @ 12.09 hrs, Volume= 0.334 af, Depth> 2.90" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type 11124-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 21 Summary for Subcatchment 6S: 6s Runoff = 0.00 cfs @ 23.95 hrs, Volume= 0.000 af, Depth> 0.00" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Rainfall=3.35" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 2-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 1.17" for 2-Year event Inflow = 10.20 cfs @ 12.09 hrs, Volume= 0.851 of Outflow = 1.47 cfs @ 12.62 hrs, Volume= 0.850 af, Atten= 86%, Lag= 31.9 min Discarded = 1.47 cfs @ 12.62 hrs, Volume= 0.850 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 28.71' @ 12.62 hrs Surf.Area= 7,700 sf Storage= 11,359 cf Plug -Flow detention time= 56.7 min calculated for 0.848 of (100% of inflow) Center -of -Mass det. time= 55.8 min ( 842.4 - 786.6 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type Ill 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 22 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=1.47 cfs @ 12.62 hrs HW=28.71' (Free Discharge) L1=Exfiltration (Exfiltration Controls 1.47 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 0.14" for 2-Year event Inflow = 0.05 cfs @ 12.47 hrs, Volume= 0.020 of Outflow = 0.05 cfs @ 12.47 hrs, Volume= 0.020 af, Atten= 0%, Lag= 0.0 min Primary = 0.05 cfs @ 12.47 hrs, Volume= 0.020 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 33.13' @ 12.47 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.05 cfs @ 12.47 hrs HW=33.13' (Free Discharge) L1=Culvert (Barrel Controls 0.05 cfs @ 1.23 fps) Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 23 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91 % Impervious, Inflow Depth > 2.90" for 2-Year event Inflow = 3.83 cfs @ 12.09 hrs, Volume= 0.300 of Outflow = 3.83 cfs @ 12.09 hrs, Volume= 0.300 af, Atten= 0%, Lag= 0.0 min Primary = 3.83 cfs @ 12.09 hrs, Volume= 0.300 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 34.09' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=3.73 cfs @ 12.09 hrs HW=34.07' (Free Discharge) L1=Culvert (Inlet Controls 3.73 cfs @ 2.78 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 2.90" for 2-Year event Inflow = 2.11 cfs @ 12.09 hrs, Volume= 0.165 of Outflow = 2.11 cfs @ 12.09 hrs, Volume= 0.165 af, Atten= 0%, Lag= 0.0 min Primary = 2.11 cfs @ 12.09 hrs, Volume= 0.165 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 35.65' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=2.06 cfs @ 12.09 hrs HW=35.63' (Free Discharge) L1=Culvert (Inlet Controls 2.06 cfs @ 2.65 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth > 0.00" for 2-Year event Inflow = 0.00 cfs @ 23.95 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 23.95 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Primary = 0.00 cfs @ 23.95 hrs, Volume= 0.000 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 24 Peak Elev= 34.12' @ 23.95 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.00 cfs @ 23.95 hrs HW=34.12' (Free Discharge) L1=Culvert (Barrel Controls 0.00 cfs @ 0.38 fps) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 0.66" for 2-Year event Inflow = 2.11 cfs @ 12.09 hrs, Volume= 0.186 of Outflow = 2.11 cfs @ 12.09 hrs, Volume= 0.186 af, Atten= 0%, Lag= 0.0 min Primary = 2.11 cfs @ 12.09 hrs, Volume= 0.186 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.14' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=2.05 cfs @ 12.09 hrs HW=31.12' (Free Discharge) L1=Culvert (Barrel Controls 2.05 cfs @ 3.20 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 0.66" for 2-Year event Inflow = 2.11 cfs @ 12.09 hrs, Volume= 0.186 of Outflow = 2.11 cfs @ 12.09 hrs, Volume= 0.186 af, Atten= 0%, Lag= 0.0 min Primary = 2.11 cfs @ 12.09 hrs, Volume= 0.186 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.68' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=2.05 cfs @ 12.09 hrs HW=30.67' (Free Discharge) L1=Culvert (Barrel Controls 2.05 cfs @ 3.10 fps) Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 25 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 1.31" for 2-Year event Inflow = 6.37 cfs @ 12.09 hrs, Volume= 0.520 of Outflow = 6.37 cfs @ 12.09 hrs, Volume= 0.520 af, Atten= 0%, Lag= 0.0 min Primary = 6.37 cfs @ 12.09 hrs, Volume= 0.520 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.60' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=6.20 cfs @ 12.09 hrs HW=30.58' (Free Discharge) L1=Culvert (Barrel Controls 6.20 cfs @ 4.22 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 1.31" for 2-Year event Inflow = 6.37 cfs @ 12.09 hrs, Volume= 0.520 of Outflow = 6.37 cfs @ 12.09 hrs, Volume= 0.520 af, Atten= 0%, Lag= 0.0 min Primary = 6.37 cfs @ 12.09 hrs, Volume= 0.520 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.10' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=6.20 cfs @ 12.09 hrs HW=30.07' (Free Discharge) L1=Culvert (Barrel Controls 6.20 cfs @ 3.32 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 2.90" for 2-Year event Inflow = 4.26 cfs @ 12.09 hrs, Volume= 0.334 of Outflow = 4.26 cfs @ 12.09 hrs, Volume= 0.334 af, Atten= 0%, Lag= 0.0 min Primary = 4.26 cfs @ 12.09 hrs, Volume= 0.334 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 2-Year Rainfall=3.35" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 26 Peak Elev= 31.57' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=4.15 cfs @ 12.09 hrs HW=31.56' (Free Discharge) L1=Culvert (Barrel Controls 4.15 cfs @ 3.58 fps) Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 27 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>0.35" Tc=6.0 min CN=49 Runoff=0.41 cfs 0.080 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>0.35" Tc=6.0 min CN=49 Runoff=0.27 cfs 0.052 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>3.72" Tc=6.0 min CN=96 Runoff=4.85 cfs 0.385 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>3.72" Tc=6.0 min CN=96 Runoff=2.67 cfs 0.212 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>3.72" Tc=6.0 min CN=96 Runoff=5.39 cfs 0.429 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth>0.07" Tc=6.0 min CN=39 Runoff=0.01 cfs 0.005 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak Elev=29.35' Storage=16,576 cf Inflow=13.16 cfs 1.163 of Discarded=1.64 cfs 1.161 of Primary=0.00 cfs 0.000 of Outflow=1.64 cfs 1.161 of Pond 6P: CB-1 Peak Elev=33.31' Inflow=0.27 cfs 0.052 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=0.27 cfs 0.052 of Pond 7P: Trench Drain Peak Elev=34.27' Inflow=4.85 cfs 0.385 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=4.85 cfs 0.385 of Pond 8P: Trench Drain Peak Elev=35.96' Inflow=2.67 cfs 0.212 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=2.67 cfs 0.212 of Pond 9P: Trench Drain Peak Elev=34.16' Inflow=0.01 cfs 0.005 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.01 cfs 0.005 of Pond 11P: DMH 1 Peak Elev=31.27' Inflow=2.77 cfs 0.269 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=2.77 cfs 0.269 of Pond 12P: DMH 2 Peak EIev=30.82' Inflow=2.77 cfs 0.269 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=2.77 cfs 0.269 of Pond 13P: DMH 3 Peak EIev=30.81' Inflow=8.16 cfs 0.698 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=8.16 cfs 0.698 of Pond 14P: WQTU Peak EIev=30.34' Inflow=8.16 cfs 0.698 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=8.16 cfs 0.698 of Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 28 Pond 15P: C13-2 Peak Elev=31.73' Inflow=5.39 cfs 0.429 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=5.39 cfs 0.429 of Total Runoff Area = 8.719 ac Runoff Volume = 1.163 of Average Runoff Depth = 1.60" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 29 Summary for Subcatchment 1 S: Runoff = 0.41 cfs @ 12.32 hrs, Volume= 0.080 af, Depth> 0.35" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 0.27 cfs @ 12.32 hrs, Volume= 0.052 af, Depth> 0.35" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 4.85 cfs @ 12.09 hrs, Volume= 0.385 af, Depth> 3.72" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 30 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 2.67 cfs @ 12.09 hrs, Volume= 0.212 af, Depth> 3.72" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 5.39 cfs @ 12.09 hrs, Volume= 0.429 af, Depth> 3.72" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type 11124-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 31 Summary for Subcatchment 6S: 6s Runoff = 0.01 cfs @ 15.20 hrs, Volume= 0.005 af, Depth> 0.07" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 5-Year Rainfall=4.18" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 5-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 1.60" for 5-Year event Inflow = 13.16 cfs @ 12.09 hrs, Volume= 1.163 of Outflow = 1.64 cfs @ 12.83 hrs, Volume= 1.161 af, Atten= 88%, Lag= 44.3 min Discarded = 1.64 cfs @ 12.83 hrs, Volume= 1.161 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 29.35' @ 12.83 hrs Surf.Area= 8,547 sf Storage= 16,576 cf Plug -Flow detention time= 82.2 min calculated for 1.161 of (100% of inflow) Center -of -Mass det. time= 81.4 min ( 869.8 - 788.5 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type Ill 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 32 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=1.64 cfs @ 12.83 hrs HW=29.35' (Free Discharge) L1=Exfiltration (Exfiltration Controls 1.64 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 0.35" for 5-Year event Inflow = 0.27 cfs @ 12.32 hrs, Volume= 0.052 of Outflow = 0.27 cfs @ 12.32 hrs, Volume= 0.052 af, Atten= 0%, Lag= 0.0 min Primary = 0.27 cfs @ 12.32 hrs, Volume= 0.052 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 33.31' @ 12.32 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.27 cfs @ 12.32 hrs HW=33.31' (Free Discharge) L1=Culvert (Barrel Controls 0.27 cfs @ 1.97 fps) Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 33 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91 % Impervious, Inflow Depth > 3.72" for 5-Year event Inflow = 4.85 cfs @ 12.09 hrs, Volume= 0.385 of Outflow = 4.85 cfs @ 12.09 hrs, Volume= 0.385 af, Atten= 0%, Lag= 0.0 min Primary = 4.85 cfs @ 12.09 hrs, Volume= 0.385 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 34.27' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=4.72 cfs @ 12.09 hrs HW=34.25' (Free Discharge) L1=Culvert (Inlet Controls 4.72 cfs @ 3.00 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 3.72" for 5-Year event Inflow = 2.67 cfs @ 12.09 hrs, Volume= 0.212 of Outflow = 2.67 cfs @ 12.09 hrs, Volume= 0.212 af, Atten= 0%, Lag= 0.0 min Primary = 2.67 cfs @ 12.09 hrs, Volume= 0.212 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 35.96' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=2.60 cfs @ 12.09 hrs HW=35.92' (Free Discharge) L1=Culvert (Inlet Controls 2.60 cfs @ 3.31 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth > 0.07" for 5-Year event Inflow = 0.01 cfs @ 15.20 hrs, Volume= 0.005 of Outflow = 0.01 cfs @ 15.20 hrs, Volume= 0.005 af, Atten= 0%, Lag= 0.0 min Primary = 0.01 cfs @ 15.20 hrs, Volume= 0.005 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 34 Peak Elev= 34.16' @ 15.20 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.01 cfs @ 15.20 hrs HW=34.16' (Free Discharge) L1=Culvert (Barrel Controls 0.01 cfs @ 0.79 fps) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 0.96" for 5-Year event Inflow = 2.77 cfs @ 12.09 hrs, Volume= 0.269 of Outflow = 2.77 cfs @ 12.09 hrs, Volume= 0.269 af, Atten= 0%, Lag= 0.0 min Primary = 2.77 cfs @ 12.09 hrs, Volume= 0.269 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.27' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=2.73 cfs @ 12.09 hrs HW=31.26' (Free Discharge) L1=Culvert (Barrel Controls 2.73 cfs @ 3.42 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 0.96" for 5-Year event Inflow = 2.77 cfs @ 12.09 hrs, Volume= 0.269 of Outflow = 2.77 cfs @ 12.09 hrs, Volume= 0.269 af, Atten= 0%, Lag= 0.0 min Primary = 2.77 cfs @ 12.09 hrs, Volume= 0.269 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.82' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=2.73 cfs @ 12.09 hrs HW=30.81' (Free Discharge) L1=Culvert (Barrel Controls 2.73 cfs @ 3.32 fps) Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 35 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 1.76" for 5-Year event Inflow = 8.16 cfs @ 12.09 hrs, Volume= 0.698 of Outflow = 8.16 cfs @ 12.09 hrs, Volume= 0.698 af, Atten= 0%, Lag= 0.0 min Primary = 8.16 cfs @ 12.09 hrs, Volume= 0.698 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.81' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=7.97 cfs @ 12.09 hrs HW=30.79' (Free Discharge) L1=Culvert (Barrel Controls 7.97 cfs @ 4.46 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 1.76" for 5-Year event Inflow = 8.16 cfs @ 12.09 hrs, Volume= 0.698 of Outflow = 8.16 cfs @ 12.09 hrs, Volume= 0.698 af, Atten= 0%, Lag= 0.0 min Primary = 8.16 cfs @ 12.09 hrs, Volume= 0.698 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.34' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=7.97 cfs @ 12.09 hrs HW=30.32' (Free Discharge) L1=Culvert (Barrel Controls 7.97 cfs @ 3.58 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 3.72" for 5-Year event Inflow = 5.39 cfs @ 12.09 hrs, Volume= 0.429 of Outflow = 5.39 cfs @ 12.09 hrs, Volume= 0.429 af, Atten= 0%, Lag= 0.0 min Primary = 5.39 cfs @ 12.09 hrs, Volume= 0.429 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 5-Year Rainfall=4.18" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 36 Peak Elev= 31.73' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=5.25 cfs @ 12.09 hrs HW=31.71' (Free Discharge) L1=Culvert (Barrel Controls 5.25 cfs @ 3.77 fps) Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 37 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>0.59" Tc=6.0 min CN=49 Runoff=0.99 cfs 0.133 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>0.59" Tc=6.0 min CN=49 Runoff=0.65 cfs 0.087 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>4.40" Tc=6.0 min CN=96 Runoff=5.69 cfs 0.456 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>4.40" Tc=6.0 min CN=96 Runoff=3.13 cfs 0.251 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>4.40" Tc=6.0 min CN=96 Runoff=6.33 cfs 0.508 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth>0.17" Tc=6.0 min CN=39 Runoff=0.02 cfs 0.013 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak Elev=29.95' Storage=21,915 cf Inflow=16.56 cfs 1.449 of Discarded=1.79 cfs 1.447 of Primary=0.00 cfs 0.000 of Outflow=1.79 cfs 1.447 of Pond 6P: CB-1 Peak Elev=33.49' Inflow=0.65 cfs 0.087 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=0.65 cfs 0.087 of Pond 7P: Trench Drain Peak Elev=34.45' Inflow=5.69 cfs 0.456 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=5.69 cfs 0.456 of Pond 8P: Trench Drain Peak Elev=36.26' Inflow=3.13 cfs 0.251 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=3.13 cfs 0.251 of Pond 9P: Trench Drain Peak EIev=34.20' Inflow=0.02 cfs 0.013 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.02 cfs 0.013 of Pond 11P: DMH 1 Peak EIev=31.45' Inflow=3.70 cfs 0.352 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=3.70 cfs 0.352 of Pond 12P: DMH 2 Peak EIev=31.01' Inflow=3.70 cfs 0.352 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=3.70 cfs 0.352 of Pond 13P: DMH 3 Peak EIev=31.03' Inflow=10.01 cfs 0.859 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=10.01 cfs 0.859 of Pond 14P: WQTU Peak EIev=30.60' Inflow=10.01 cfs 0.859 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=10.01 cfs 0.859 of Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 38 Pond 15P: C13-2 Peak Elev=31.86' Inflow=6.33 cfs 0.508 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=6.33 cfs 0.508 of Total Runoff Area = 8.719 ac Runoff Volume = 1.449 of Average Runoff Depth = 1.99" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 39 Summary for Subcatchment 1 S: Runoff = 0.99 cfs @ 12.15 hrs, Volume= 0.133 af, Depth> 0.59" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 0.65 cfs @ 12.15 hrs, Volume= 0.087 af, Depth> 0.59" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 5.69 cfs @ 12.09 hrs, Volume= 0.456 af, Depth> 4.40" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 40 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 3.13 cfs @ 12.09 hrs, Volume= 0.251 af, Depth> 4.40" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 6.33 cfs @ 12.09 hrs, Volume= 0.508 af, Depth> 4.40" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 41 Summary for Subcatchment 6S: 6s Runoff = 0.02 cfs @ 12.51 hrs, Volume= 0.013 af, Depth> 0.17" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Rainfall=4.87" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 10-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 1.99" for 10-Year event Inflow = 16.56 cfs @ 12.09 hrs, Volume= 1.449 of Outflow = 1.79 cfs @ 12.99 hrs, Volume= 1.447 af, Atten= 89%, Lag= 53.6 min Discarded = 1.79 cfs @ 12.99 hrs, Volume= 1.447 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 29.95' @ 12.99 hrs Surf.Area= 9,363 sf Storage= 21,915 cf Plug -Flow detention time= 106.6 min calculated for 1.447 of (100% of inflow) Center -of -Mass det. time= 105.7 min ( 895.1 - 789.3 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 42 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=1.79 cfs @ 12.99 hrs HW=29.95' (Free Discharge) L1=Exfiltration (Exfiltration Controls 1.79 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 0.59" for 10-Year event Inflow = 0.65 cfs @ 12.15 hrs, Volume= 0.087 of Outflow = 0.65 cfs @ 12.15 hrs, Volume= 0.087 af, Atten= 0%, Lag= 0.0 min Primary = 0.65 cfs @ 12.15 hrs, Volume= 0.087 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 33.49' @ 12.15 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=0.65 cfs @ 12.15 hrs HW=33.49' (Free Discharge) L1=Culvert (Barrel Controls 0.65 cfs @ 2.46 fps) Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 43 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91 % Impervious, Inflow Depth > 4.40" for 10-Year event Inflow = 5.69 cfs @ 12.09 hrs, Volume= 0.456 of Outflow = 5.69 cfs @ 12.09 hrs, Volume= 0.456 af, Atten= 0%, Lag= 0.0 min Primary = 5.69 cfs @ 12.09 hrs, Volume= 0.456 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 34.45' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=5.55 cfs @ 12.09 hrs HW=34.42' (Free Discharge) L1=Culvert (Inlet Controls 5.55 cfs @ 3.20 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 4.40" for 10-Year event Inflow = 3.13 cfs @ 12.09 hrs, Volume= 0.251 of Outflow = 3.13 cfs @ 12.09 hrs, Volume= 0.251 af, Atten= 0%, Lag= 0.0 min Primary = 3.13 cfs @ 12.09 hrs, Volume= 0.251 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 36.26' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=3.05 cfs @ 12.09 hrs HW=36.20' (Free Discharge) L1=Culvert (Inlet Controls 3.05 cfs @ 3.88 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth > 0.17" for 10-Year event Inflow = 0.02 cfs @ 12.51 hrs, Volume= 0.013 of Outflow = 0.02 cfs @ 12.51 hrs, Volume= 0.013 af, Atten= 0%, Lag= 0.0 min Primary = 0.02 cfs @ 12.51 hrs, Volume= 0.013 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 44 Peak Elev= 34.20' @ 12.51 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.02 cfs @ 12.51 hrs HW=34.20' (Free Discharge) L1=Culvert (Barrel Controls 0.02 cfs @ 1.08 fps) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 1.25" for 10-Year event Inflow = 3.70 cfs @ 12.10 hrs, Volume= 0.352 of Outflow = 3.70 cfs @ 12.10 hrs, Volume= 0.352 af, Atten= 0%, Lag= 0.0 min Primary = 3.70 cfs @ 12.10 hrs, Volume= 0.352 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.45' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=3.67 cfs @ 12.10 hrs HW=31.45' (Free Discharge) L1=Culvert (Barrel Controls 3.67 cfs @ 3.66 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 1.25" for 10-Year event Inflow = 3.70 cfs @ 12.10 hrs, Volume= 0.352 of Outflow = 3.70 cfs @ 12.10 hrs, Volume= 0.352 af, Atten= 0%, Lag= 0.0 min Primary = 3.70 cfs @ 12.10 hrs, Volume= 0.352 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.01' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=3.67 cfs @ 12.10 hrs HW=31.00' (Free Discharge) L1=Culvert (Barrel Controls 3.67 cfs @ 3.57 fps) Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 45 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 2.17" for 10-Year event Inflow = 10.01 cfs @ 12.09 hrs, Volume= 0.859 of Outflow = 10.01 cfs @ 12.09 hrs, Volume= 0.859 af, Atten= 0%, Lag= 0.0 min Primary = 10.01 cfs @ 12.09 hrs, Volume= 0.859 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.03' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=9.80 cfs @ 12.09 hrs HW=31.00' (Free Discharge) L1=Culvert (Barrel Controls 9.80 cfs @ 4.67 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 2.17" for 10-Year event Inflow = 10.01 cfs @ 12.09 hrs, Volume= 0.859 of Outflow = 10.01 cfs @ 12.09 hrs, Volume= 0.859 af, Atten= 0%, Lag= 0.0 min Primary = 10.01 cfs @ 12.09 hrs, Volume= 0.859 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.60' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=9.81 cfs @ 12.09 hrs HW=30.57' (Free Discharge) L1=Culvert (Barrel Controls 9.81 cfs @ 3.82 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 4.40" for 10-Year event Inflow = 6.33 cfs @ 12.09 hrs, Volume= 0.508 of Outflow = 6.33 cfs @ 12.09 hrs, Volume= 0.508 af, Atten= 0%, Lag= 0.0 min Primary = 6.33 cfs @ 12.09 hrs, Volume= 0.508 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type III 24-hr 10-Year Rainfall=4.87" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 46 Peak Elev= 31.86' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=6.16 cfs @ 12.09 hrs HW=31.83' (Free Discharge) L1=Culvert (Barrel Controls 6.16 cfs @ 3.92 fps) Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 47 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>0.99" Tc=6.0 min CN=49 Runoff=2.29 cfs 0.223 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>0.99" Tc=6.0 min CN=49 Runoff=1.50 cfs 0.147 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>5.34" Tc=6.0 min CN=96 Runoff=6.84 cfs 0.554 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>5.34" Tc=6.0 min CN=96 Runoff=3.77 cfs 0.305 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>5.34" Tc=6.0 min CN=96 Runoff=7.61 cfs 0.617 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth>0.39" Tc=6.0 min CN=39 Runoff=0.13 cfs 0.030 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak EIev=30.83' Storage=30,647 cf Inflow=21.85 cfs 1.875 of Discarded=2.03 cfs 1.873 of Primary=0.00 cfs 0.000 of Outflow=2.03 cfs 1.873 of Pond 6P: CB-1 Peak EIev=33.81' Inflow=1.50 cfs 0.147 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=1.50 cfs 0.147 of Pond 7P: Trench Drain Peak EIev=34.79' Inflow=6.84 cfs 0.554 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=6.84 cfs 0.554 of Pond 8P: Trench Drain Peak EIev=36.75' Inflow=3.77 cfs 0.305 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=3.77 cfs 0.305 of Pond 9P: Trench Drain Peak EIev=34.33' Inflow=0.13 cfs 0.030 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.13 cfs 0.030 of Pond 11P: DMH 1 Peak EIev=31.74' Inflow=5.22 cfs 0.481 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=5.22 cfs 0.481 of Pond 12P: DMH 2 Peak EIev=31.30' Inflow=5.22 cfs 0.481 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=5.22 cfs 0.481 of Pond 13P: DMH 3 Peak EIev=31.46' Inflow=12.81 cfs 1.098 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=12.81 cfs 1.098 of Pond 14P: WQTU Peak EIev=31.06' Inflow=12.81 cfs 1.098 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=12.81 cfs 1.098 of Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 48 Pond 15P: C13-2 Peak Elev=32.02' Inflow=7.61 cfs 0.617 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=7.61 cfs 0.617 of Total Runoff Area = 8.719 ac Runoff Volume = 1.875 of Average Runoff Depth = 2.58" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 49 Summary for Subcatchment 1 S: Runoff = 2.29 cfs @ 12.12 hrs, Volume= 0.223 af, Depth> 0.99" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 1.50 cfs @ 12.12 hrs, Volume= 0.147 af, Depth> 0.99" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 6.84 cfs @ 12.09 hrs, Volume= 0.554 af, Depth> 5.34" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 50 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 3.77 cfs @ 12.09 hrs, Volume= 0.305 af, Depth> 5.34" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 7.61 cfs @ 12.09 hrs, Volume= 0.617 af, Depth> 5.34" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type 11124-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 51 Summary for Subcatchment 6S: 6s Runoff = 0.13 cfs @ 12.36 hrs, Volume= 0.030 af, Depth> 0.39" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 25-Year Rainfall=5.82" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 25-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 2.58" for 25-Year event Inflow = 21.85 cfs @ 12.09 hrs, Volume= 1.875 of Outflow = 2.03 cfs @ 13.21 hrs, Volume= 1.873 af, Atten= 91 %, Lag= 66.9 min Discarded = 2.03 cfs @ 13.21 hrs, Volume= 1.873 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 30.83' @ 13.21 hrs Surf.Area= 10,600 sf Storage= 30,647 cf Plug -Flow detention time= 143.2 min calculated for 1.869 of (100% of inflow) Center -of -Mass det. time= 142.0 min ( 931.8 - 789.8 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type/1/ 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 52 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=2.03 cfs @ 13.21 hrs HW=30.83' (Free Discharge) L1=Exfiltration (Exfiltration Controls 2.03 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 0.99" for 25-Year event Inflow = 1.50 cfs @ 12.12 hrs, Volume= 0.147 of Outflow = 1.50 cfs @ 12.12 hrs, Volume= 0.147 af, Atten= 0%, Lag= 0.0 min Primary = 1.50 cfs @ 12.12 hrs, Volume= 0.147 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 33.81' @ 12.12 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=1.45 cfs @ 12.12 hrs HW=33.79' (Free Discharge) L1=Culvert (Barrel Controls 1.45 cfs @ 2.97 fps) Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 53 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91 % Impervious, Inflow Depth > 5.34" for 25-Year event Inflow = 6.84 cfs @ 12.09 hrs, Volume= 0.554 of Outflow = 6.84 cfs @ 12.09 hrs, Volume= 0.554 af, Atten= 0%, Lag= 0.0 min Primary = 6.84 cfs @ 12.09 hrs, Volume= 0.554 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 34.79' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=6.66 cfs @ 12.09 hrs HW=34.73' (Free Discharge) L1=Culvert (Inlet Controls 6.66 cfs @ 3.77 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 5.34" for 25-Year event Inflow = 3.77 cfs @ 12.09 hrs, Volume= 0.305 of Outflow = 3.77 cfs @ 12.09 hrs, Volume= 0.305 af, Atten= 0%, Lag= 0.0 min Primary = 3.77 cfs @ 12.09 hrs, Volume= 0.305 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 36.75' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=3.67 cfs @ 12.09 hrs HW=36.67' (Free Discharge) L1=Culvert (Inlet Controls 3.67 cfs @ 4.67 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth > 0.39" for 25-Year event Inflow = 0.13 cfs @ 12.36 hrs, Volume= 0.030 of Outflow = 0.13 cfs @ 12.36 hrs, Volume= 0.030 af, Atten= 0%, Lag= 0.0 min Primary = 0.13 cfs @ 12.36 hrs, Volume= 0.030 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 54 Peak Elev= 34.33' @ 12.36 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.13 cfs @ 12.36 hrs HW=34.33' (Free Discharge) L1=Culvert (Barrel Controls 0.13 cfs @ 1.80 fps) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 1.71" for 25-Year event Inflow = 5.22 cfs @ 12.10 hrs, Volume= 0.481 of Outflow = 5.22 cfs @ 12.10 hrs, Volume= 0.481 af, Atten= 0%, Lag= 0.0 min Primary = 5.22 cfs @ 12.10 hrs, Volume= 0.481 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.74' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=5.18 cfs @ 12.10 hrs HW=31.73' (Free Discharge) L1=Culvert (Barrel Controls 5.18 cfs @ 3.95 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 1.71" for 25-Year event Inflow = 5.22 cfs @ 12.10 hrs, Volume= 0.481 of Outflow = 5.22 cfs @ 12.10 hrs, Volume= 0.481 af, Atten= 0%, Lag= 0.0 min Primary = 5.22 cfs @ 12.10 hrs, Volume= 0.481 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.30' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=5.18 cfs @ 12.10 hrs HW=31.29' (Free Discharge) L1=Culvert (Barrel Controls 5.18 cfs @ 3.86 fps) Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 55 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 2.77" for 25-Year event Inflow = 12.81 cfs @ 12.09 hrs, Volume= 1.098 of Outflow = 12.81 cfs @ 12.09 hrs, Volume= 1.098 af, Atten= 0%, Lag= 0.0 min Primary = 12.81 cfs @ 12.09 hrs, Volume= 1.098 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.46' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=12.55 cfs @ 12.09 hrs HW=31.41' (Free Discharge) L1=Culvert (Inlet Controls 12.55 cfs @ 3.99 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 2.77" for 25-Year event Inflow = 12.81 cfs @ 12.09 hrs, Volume= 1.098 of Outflow = 12.81 cfs @ 12.09 hrs, Volume= 1.098 af, Atten= 0%, Lag= 0.0 min Primary = 12.81 cfs @ 12.09 hrs, Volume= 1.098 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.06' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=12.59 cfs @ 12.09 hrs HW=31.02' (Free Discharge) L1=Culvert (Barrel Controls 12.59 cfs @ 4.14 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 5.34" for 25-Year event Inflow = 7.61 cfs @ 12.09 hrs, Volume= 0.617 of Outflow = 7.61 cfs @ 12.09 hrs, Volume= 0.617 af, Atten= 0%, Lag= 0.0 min Primary = 7.61 cfs @ 12.09 hrs, Volume= 0.617 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type /// 24-hr 25-Year Rainfall=5.82" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 56 Peak Elev= 32.02' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=7.41 cfs @ 12.09 hrs HW=31.99' (Free Discharge) L1=Culvert (Barrel Controls 7.41 cfs @ 4.09 fps) Proposed Type /// 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 57 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>1.34" Tc=6.0 min CN=49 Runoff=3.43 cfs 0.302 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>1.34" Tc=6.0 min CN=49 Runoff=2.26 cfs 0.198 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>6.06" Tc=6.0 min CN=96 Runoff=7.72 cfs 0.629 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>6.06" Tc=6.0 min CN=96 Runoff=4.25 cfs 0.346 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>6.06" Tc=6.0 min CN=96 Runoff=8.58 cfs 0.699 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth>0.61" Tc=6.0 min CN=39 Runoff=0.26 cfs 0.046 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak Elev=31.51' Storage=38,280 cf Inflow=26.23 cfs 2.220 of Discarded=2.22 cfs 2.180 of Primary=0.00 cfs 0.000 of Outflow=2.22 cfs 2.180 of Pond 6P: CB-1 Peak EIev=34.09' Inflow=2.26 cfs 0.198 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=2.26 cfs 0.198 of Pond 7P: Trench Drain Peak EIev=35.06' Inflow=7.72 cfs 0.629 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=7.72 cfs 0.629 of Pond 8P: Trench Drain Peak EIev=37.18' Inflow=4.25 cfs 0.346 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=4.25 cfs 0.346 of Pond 9P: Trench Drain Peak EIev=34.43' Inflow=0.26 cfs 0.046 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.26 cfs 0.046 of Pond 11P: DMH 1 Peak EIev=32.06' Inflow=6.61 cfs 0.590 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=6.61 cfs 0.590 of Pond 12P: DMH 2 Peak EIev=31.61' Inflow=6.61 cfs 0.590 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=6.61 cfs 0.590 of Pond 13P: DMH 3 Peak EIev=31.92' Inflow=15.16 cfs 1.290 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=15.16 cfs 1.290 of Pond 14P: WQTU Peak EIev=31.48' Inflow=15.16 cfs 1.290 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=15.16 cfs 1.290 of Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 58 Pond 15P: C13-2 Peak Elev=32.14' Inflow=8.58 cfs 0.699 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=8.58 cfs 0.699 of Total Runoff Area = 8.719 ac Runoff Volume = 2.220 of Average Runoff Depth = 3.06" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 59 Summary for Subcatchment 1 S: Runoff = 3.43 cfs @ 12.11 hrs, Volume= 0.302 af, Depth> 1.34" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 2.26 cfs @ 12.11 hrs, Volume= 0.198 af, Depth> 1.34" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 7.72 cfs @ 12.09 hrs, Volume= 0.629 af, Depth> 6.06" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 60 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 4.25 cfs @ 12.09 hrs, Volume= 0.346 af, Depth> 6.06" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 8.58 cfs @ 12.09 hrs, Volume= 0.699 af, Depth> 6.06" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 61 Summary for Subcatchment 6S: 6s Runoff = 0.26 cfs @ 12.29 hrs, Volume= 0.046 af, Depth> 0.61" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 50-Year Rainfall=6.54" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 50-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 3.06" for 50-Year event Inflow = 26.23 cfs @ 12.09 hrs, Volume= 2.220 of Outflow = 2.22 cfs @ 13.47 hrs, Volume= 2.180 af, Atten= 92%, Lag= 82.6 min Discarded = 2.22 cfs @ 13.47 hrs, Volume= 2.180 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.51' @ 13.47 hrs Surf.Area= 11,608 sf Storage= 38,280 cf Plug -Flow detention time= 173.3 min calculated for 2.175 of (98% of inflow) Center -of -Mass det. time= 161.7 min ( 951.5 - 789.8 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 62 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=2.22 cfs @ 13.47 hrs HW=31.51' (Free Discharge) L1=Exfiltration (Exfiltration Controls 2.22 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 1.34" for 50-Year event Inflow = 2.26 cfs @ 12.11 hrs, Volume= 0.198 of Outflow = 2.26 cfs @ 12.11 hrs, Volume= 0.198 af, Atten= 0%, Lag= 0.0 min Primary = 2.26 cfs @ 12.11 hrs, Volume= 0.198 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 34.09' @ 12.11 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=2.20 cfs @ 12.11 hrs HW=34.06' (Free Discharge) L1=Culvert (Barrel Controls 2.20 cfs @ 3.27 fps) Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 63 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91 % Impervious, Inflow Depth > 6.06" for 50-Year event Inflow = 7.72 cfs @ 12.09 hrs, Volume= 0.629 of Outflow = 7.72 cfs @ 12.09 hrs, Volume= 0.629 af, Atten= 0%, Lag= 0.0 min Primary = 7.72 cfs @ 12.09 hrs, Volume= 0.629 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 35.06' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=7.51 cfs @ 12.09 hrs HW=35.00' (Free Discharge) L1=Culvert (Inlet Controls 7.51 cfs @ 4.25 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 6.06" for 50-Year event Inflow = 4.25 cfs @ 12.09 hrs, Volume= 0.346 of Outflow = 4.25 cfs @ 12.09 hrs, Volume= 0.346 af, Atten= 0%, Lag= 0.0 min Primary = 4.25 cfs @ 12.09 hrs, Volume= 0.346 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 37.18' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=4.13 cfs @ 12.09 hrs HW=37.08' (Free Discharge) L1=Culvert (Inlet Controls 4.13 cfs @ 5.26 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth > 0.61" for 50-Year event Inflow = 0.26 cfs @ 12.29 hrs, Volume= 0.046 of Outflow = 0.26 cfs @ 12.29 hrs, Volume= 0.046 af, Atten= 0%, Lag= 0.0 min Primary = 0.26 cfs @ 12.29 hrs, Volume= 0.046 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 64 Peak Elev= 34.43' @ 12.29 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.26 cfs @ 12.29 hrs HW=34.43' (Free Discharge) L1=Culvert (Barrel Controls 0.26 cfs @ 2.16 fps) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 2.10" for 50-Year event Inflow = 6.61 cfs @ 12.10 hrs, Volume= 0.590 of Outflow = 6.61 cfs @ 12.10 hrs, Volume= 0.590 af, Atten= 0%, Lag= 0.0 min Primary = 6.61 cfs @ 12.10 hrs, Volume= 0.590 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 32.06' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=6.58 cfs @ 12.10 hrs HW=32.05' (Free Discharge) L1=Culvert (Inlet Controls 6.58 cfs @ 3.73 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 2.10" for 50-Year event Inflow = 6.61 cfs @ 12.10 hrs, Volume= 0.590 of Outflow = 6.61 cfs @ 12.10 hrs, Volume= 0.590 af, Atten= 0%, Lag= 0.0 min Primary = 6.61 cfs @ 12.10 hrs, Volume= 0.590 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.61' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=6.58 cfs @ 12.10 hrs HW=31.60' (Free Discharge) L1=Culvert (Barrel Controls 6.58 cfs @ 4.05 fps) Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 65 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 3.25" for 50-Year event Inflow = 15.16 cfs @ 12.09 hrs, Volume= 1.290 of Outflow = 15.16 cfs @ 12.09 hrs, Volume= 1.290 af, Atten= 0%, Lag= 0.0 min Primary = 15.16 cfs @ 12.09 hrs, Volume= 1.290 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.92' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=14.88 cfs @ 12.09 hrs HW=31.86' (Free Discharge) L1=Culvert (Inlet Controls 14.88 cfs @ 4.74 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 3.25" for 50-Year event Inflow = 15.16 cfs @ 12.09 hrs, Volume= 1.290 of Outflow = 15.16 cfs @ 12.09 hrs, Volume= 1.290 af, Atten= 0%, Lag= 0.0 min Primary = 15.16 cfs @ 12.09 hrs, Volume= 1.290 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.48' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=14.88 cfs @ 12.09 hrs HW=31.43' (Free Discharge) L1=Culvert (Barrel Controls 14.88 cfs @ 4.74 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 6.06" for 50-Year event Inflow = 8.58 cfs @ 12.09 hrs, Volume= 0.699 of Outflow = 8.58 cfs @ 12.09 hrs, Volume= 0.699 af, Atten= 0%, Lag= 0.0 min Primary = 8.58 cfs @ 12.09 hrs, Volume= 0.699 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type III 24-hr 50-Year Rainfall=6.54" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 66 Peak Elev= 32.14' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=8.35 cfs @ 12.09 hrs HW=32.11' (Free Discharge) L1=Culvert (Barrel Controls 8.35 cfs @ 4.21 fps) Proposed Type 111 24-hr 100-Year Rainfall= 7.28 " Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 67 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Runoff Area=118,302 sf 0.00% Impervious Runoff Depth>1.73" Tc=6.0 min CN=49 Runoff=4.73 cfs 0.391 of Subcatchment 2S: Runoff Area=77,705 sf 0.00% Impervious Runoff Depth>1.73" Tc=6.0 min CN=49 Runoff=3.11 cfs 0.257 of Subcatchment 3S: Runoff Area=54,208 sf 9.91 % Impervious Runoff Depth>6.80" Tc=6.0 min CN=96 Runoff=8.61 cfs 0.705 of Subcatchment 4S: Runoff Area=29,833 sf 0.00% Impervious Runoff Depth>6.80" Tc=6.0 min CN=96 Runoff=4.74 cfs 0.388 of Subcatchment 5S: Runoff Area=60,293 sf 15.49% Impervious Runoff Depth>6.80" Tc=6.0 min CN=96 Runoff=9.58 cfs 0.784 of Subcatchment 6S: 6s Runoff Area=39,458 sf 0.00% Impervious Runoff Depth>0.87" Tc=6.0 min CN=39 Runoff=0.48 cfs 0.066 of Reach DP-1: Inflow=0.00 cfs 0.000 of Outflow=0.00 cfs 0.000 of Pond 1 P: Infiltration Basin #1 Peak Elev=32.22' Storage=46,901 cf Inflow=31.04 cfs 2.591 of Discarded=2.43 cfs 2.427 of Primary=0.00 cfs 0.000 of Outflow=2.43 cfs 2.427 of Pond 6P: CB-1 Peak EIev=34.60' Inflow=3.11 cfs 0.257 of 12.0" Round Culvert n=0.013 L=50.0' S=0.0050 T Outflow=3.11 cfs 0.257 of Pond 7P: Trench Drain Peak EIev=35.39' Inflow=8.61 cfs 0.705 of 18.0" Round Culvert n=0.013 L=131.0' S=0.0229 '/' Outflow=8.61 cfs 0.705 of Pond 8P: Trench Drain Peak EIev=37.67' Inflow=4.74 cfs 0.388 of 12.0" Round Culvert n=0.013 L=58.0' S=0.0200 T Outflow=4.74 cfs 0.388 of Pond 9P: Trench Drain Peak EIev=34.58' Inflow=0.48 cfs 0.066 of 8.0" Round Culvert n=0.013 L=168.0' S=0.0055 '/' Outflow=0.48 cfs 0.066 of Pond 11P: DMH 1 Peak EIev=32.61' Inflow=8.23 cfs 0.711 of 18.0" Round Culvert n=0.013 L=91.7' S=0.0048 T Outflow=8.23 cfs 0.711 of Pond 12P: DMH 2 Peak EIev=32.25' Inflow=8.23 cfs 0.711 of 18.0" Round Culvert n=0.013 L=115.2' S=0.0041 T Outflow=8.23 cfs 0.711 of Pond 13P: DMH 3 Peak EIev=32.52' Inflow=17.78 cfs 1.495 of 24.0" Round Culvert n=0.013 L=155.2' S=0.0050 '/' Outflow=17.78 cfs 1.495 of Pond 14P: WQTU Peak EIev=31.85' Inflow=17.78 cfs 1.495 of 24.0" Round Culvert n=0.013 L=72.0' S=0.0011 T Outflow=17.78 cfs 1.495 of Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 68 Pond 15P: C13-2 Peak Elev=32.26' Inflow=9.58 cfs 0.784 of 24.0" Round Culvert n=0.013 L=57.7' S=0.0050 T Outflow=9.58 cfs 0.784 of Total Runoff Area = 8.719 ac Runoff Volume = 2.591 of Average Runoff Depth = 3.57" 96.13% Pervious = 8.381 ac 3.87% Impervious = 0.338 ac Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 69 Summary for Subcatchment 1 S: Runoff = 4.73 cfs @ 12.11 hrs, Volume= 0.391 af, Depth> 1.73" Routed to Pond 1 P : Infiltration Basin #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Area (sf) CN Description 53,287 39 >75% Grass cover, Good, HSG A 27,292 96 Gravel surface, HSG A 37,723 30 Woods, Good, HSG A 118,302 49 Weighted Average 118,302 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 3.11 cfs @ 12.11 hrs, Volume= 0.257 af, Depth> 1.73" Routed to Pond 6P : C13-1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Area (sf) CN Description 20,196 96 Gravel surface, HSG A 44,389 30 Woods, Good, HSG A 13,120 39 >75% Grass cover, Good, HSG A 77,705 49 Weighted Average 77,705 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 3S: Runoff = 8.61 cfs @ 12.09 hrs, Volume= 0.705 af, Depth> 6.80" Routed to Pond 7P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCADO 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 70 Area (sf) CN Description 48,836 96 Gravel surface, HSG A 5,372 98 Paved parking, HSG A 54,208 96 Weighted Average 48,836 90.09% Pervious Area 5,372 9.91 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 4S: Runoff = 4.74 cfs @ 12.09 hrs, Volume= 0.388 af, Depth> 6.80" Routed to Pond 8P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Area (sf) CN Description 29,833 96 Gravel surface, HSG A 29,833 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 5S: Runoff = 9.58 cfs @ 12.09 hrs, Volume= 0.784 af, Depth> 6.80" Routed to Pond 15P : CB-2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Area (sf) CN Description 50,956 96 Gravel surface, HSG A 9,337 98 Paved parking, HSG A 60,293 96 Weighted Average 50,956 84.51 % Pervious Area 9,337 15.49% Impervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 (9 2024 HydroCAD Software Solutions LLC Page 71 Summary for Subcatchment 6S: 6s Runoff = 0.48 cfs @ 12.15 hrs, Volume= 0.066 af, Depth> 0.87" Routed to Pond 9P : Trench Drain Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Rainfall=7.28" Area (sf) CN Description 39,458 39 >75% Grass cover, Good, HSG A 39,458 100.00% Pervious Area Tc Length Slope Velocity Capacity Description min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Min Summary for Reach DP-1: Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth = 0.00" for 100-Year event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Pond 1 P: Infiltration Basin #1 Inflow Area = 8.719 ac, 3.87% Impervious, Inflow Depth > 3.57" for 100-Year event Inflow = 31.04 cfs @ 12.09 hrs, Volume= 2.591 of Outflow = 2.43 cfs @ 13.66 hrs, Volume= 2.427 af, Atten= 92%, Lag= 94.1 min Discarded = 2.43 cfs @ 13.66 hrs, Volume= 2.427 of Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Routed to Reach DP-1 : Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 32.22' @ 13.66 hrs Surf.Area= 12,685 sf Storage= 46,901 cf Plug -Flow detention time= 200.1 min calculated for 2.427 of (94% of inflow) Center -of -Mass det. time= 165.0 min ( 954.6 - 789.7 ) Volume Invert Avail.Storage Storage Description #1 27.00' 79,901 cf Custom Stage Data (Irregular) Listed below (Recalc) Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 72 Elevation (feet) Surf.Area (sq-ft) Perim. (feet) Inc.Store (cubic -feet) Cum.Store (cubic -feet) Wet.Area (sq-ft) 27.00 5,616 380.0 0 0 5,616 28.00 6,800 410.0 6,199 6,199 7,543 29.00 8,079 440.0 7,430 13,629 9,616 30.00 9,432 462.0 8,747 22,376 11,258 31.00 10,854 485.0 10,135 32,510 13,055 32.00 12,344 508.0 11,591 44,101 14,939 33.00 13,903 531.0 13,116 57,217 16,911 34.00 15,531 554.0 14,709 71,927 18,969 34.50 16,371 566.0 7,975 79,901 20,075 Device Routing Invert Outlet Devices #1 Discarded 27.00' 8.270 in/hr Exfiltration over Surface area #2 Primary 34.50' 20.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Discarded OutFlow Max=2.43 cfs @ 13.66 hrs HW=32.22' (Free Discharge) L1=Exfiltration (Exfiltration Controls 2.43 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=27.00' (Free Discharge) L2= Broad -crested Rectangular Weir ( Controls 0.00 cfs) Summary for Pond 6P: CB-1 Inflow Area = 1.784 ac, 0.00% Impervious, Inflow Depth > 1.73" for 100-Year event Inflow = 3.11 cfs @ 12.11 hrs, Volume= 0.257 of Outflow = 3.11 cfs @ 12.11 hrs, Volume= 0.257 af, Atten= 0%, Lag= 0.0 min Primary = 3.11 cfs @ 12.11 hrs, Volume= 0.257 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 34.60' @ 12.11 hrs Device Routinq Invert Outlet Devices #1 Primary 33.00' 12.0" Round Culvert L= 50.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 32.75' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=3.06 cfs @ 12.11 hrs HW=34.57' (Free Discharge) L1=Culvert (Barrel Controls 3.06 cfs @ 3.89 fps) Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 73 Summary for Pond 7P: Trench Drain Inflow Area = 1.244 ac, 9.91 % Impervious, Inflow Depth > 6.80" for 100-Year event Inflow = 8.61 cfs @ 12.09 hrs, Volume= 0.705 of Outflow = 8.61 cfs @ 12.09 hrs, Volume= 0.705 af, Atten= 0%, Lag= 0.0 min Primary = 8.61 cfs @ 12.09 hrs, Volume= 0.705 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 35.39' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 33.00' 18.0" Round Culvert L= 131.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 33.00' / 30.00' S= 0.0229 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=8.38 cfs @ 12.09 hrs HW=35.31' (Free Discharge) L1=Culvert (Inlet Controls 8.38 cfs @ 4.74 fps) Summary for Pond 8P: Trench Drain Inflow Area = 0.685 ac, 0.00% Impervious, Inflow Depth > 6.80" for 100-Year event Inflow = 4.74 cfs @ 12.09 hrs, Volume= 0.388 of Outflow = 4.74 cfs @ 12.09 hrs, Volume= 0.388 af, Atten= 0%, Lag= 0.0 min Primary = 4.74 cfs @ 12.09 hrs, Volume= 0.388 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 37.67' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 34.66' 12.0" Round Culvert L= 58.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.66' / 33.50' S= 0.0200 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.79 sf Primary OutFlow Max=4.61 cfs @ 12.09 hrs HW=37.55' (Free Discharge) L1=Culvert (Inlet Controls 4.61 cfs @ 5.87 fps) Summary for Pond 9P: Trench Drain Inflow Area = 0.906 ac, 0.00% Impervious, Inflow Depth > 0.87" for 100-Year event Inflow = 0.48 cfs @ 12.15 hrs, Volume= 0.066 of Outflow = 0.48 cfs @ 12.15 hrs, Volume= 0.066 af, Atten= 0%, Lag= 0.0 min Primary = 0.48 cfs @ 12.15 hrs, Volume= 0.066 of Routed to Pond 11 P : DMH 1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 74 Peak Elev= 34.58' @ 12.15 hrs Device Routing Invert Outlet Devices #1 Primary 34.10' 8.0" Round Culvert L= 168.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 34.10' / 33.18' S= 0.0055 '/' Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 0.35 sf Primary OutFlow Max=0.48 cfs @ 12.15 hrs HW=34.58' (Free Discharge) L1=Culvert (Barrel Controls 0.48 cfs @ 2.53 fps) Summary for Pond 11 P: DMH 1 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 2.53" for 100-Year event Inflow = 8.23 cfs @ 12.10 hrs, Volume= 0.711 of Outflow = 8.23 cfs @ 12.10 hrs, Volume= 0.711 af, Atten= 0%, Lag= 0.0 min Primary = 8.23 cfs @ 12.10 hrs, Volume= 0.711 of Routed to Pond 12P : DMH 2 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 32.61' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 30.34' 18.0" Round Culvert L= 91.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.34' / 29.90' S= 0.0048 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=8.18 cfs @ 12.10 hrs HW=32.59' (Free Discharge) L1=Culvert (Barrel Controls 8.18 cfs @ 4.63 fps) Summary for Pond 12P: DMH 2 Inflow Area = 3.375 ac, 0.00% Impervious, Inflow Depth > 2.53" for 100-Year event Inflow = 8.23 cfs @ 12.10 hrs, Volume= 0.711 of Outflow = 8.23 cfs @ 12.10 hrs, Volume= 0.711 af, Atten= 0%, Lag= 0.0 min Primary = 8.23 cfs @ 12.10 hrs, Volume= 0.711 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 32.25' @ 12.10 hrs Device Routing Invert Outlet Devices #1 Primary 29.87' 18.0" Round Culvert L= 115.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.87' / 29.40' S= 0.0041 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 1.77 sf Primary OutFlow Max=8.17 cfs @ 12.10 hrs HW=32.23' (Free Discharge) L1=Culvert (Barrel Controls 8.17 cfs @ 4.63 fps) Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 75 Summary for Pond 13P: DMH 3 Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 3.77" for 100-Year event Inflow = 17.78 cfs @ 12.09 hrs, Volume= 1.495 of Outflow = 17.78 cfs @ 12.09 hrs, Volume= 1.495 af, Atten= 0%, Lag= 0.0 min Primary = 17.78 cfs @ 12.09 hrs, Volume= 1.495 of Routed to Pond 14P : WQTU Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 32.52' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 29.31' 24.0" Round Culvert L= 155.2' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 29.31' / 28.54' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=17.45 cfs @ 12.09 hrs HW=32.44' (Free Discharge) L1=Culvert (Inlet Controls 17.45 cfs @ 5.55 fps) Summary for Pond 14P: WQTU Inflow Area = 4.759 ac, 4.50% Impervious, Inflow Depth > 3.77" for 100-Year event Inflow = 17.78 cfs @ 12.09 hrs, Volume= 1.495 of Outflow = 17.78 cfs @ 12.09 hrs, Volume= 1.495 af, Atten= 0%, Lag= 0.0 min Primary = 17.78 cfs @ 12.09 hrs, Volume= 1.495 of Routed to Pond 1 P : Infiltration Basin #1 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 31.85' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 28.54' 24.0" Round Culvert L= 72.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 28.54' / 28.46' S= 0.0011 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=17.45 cfs @ 12.09 hrs HW=31.80' (Free Discharge) L1=Culvert (Barrel Controls 17.45 cfs @ 5.55 fps) Summary for Pond 15P: CB-2 Inflow Area = 1.384 ac, 15.49% Impervious, Inflow Depth > 6.80" for 100-Year event Inflow = 9.58 cfs @ 12.09 hrs, Volume= 0.784 of Outflow = 9.58 cfs @ 12.09 hrs, Volume= 0.784 af, Atten= 0%, Lag= 0.0 min Primary = 9.58 cfs @ 12.09 hrs, Volume= 0.784 of Routed to Pond 13P : DMH 3 Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Proposed Type III 24-hr 100-Year Rainfall=7.28" Prepared by Tighe & Bond Printed 12/10/2025 HydroCAD® 10.20-4c s/n 01453 © 2024 HydroCAD Software Solutions LLC Page 76 Peak Elev= 32.26' @ 12.09 hrs Device Routing Invert Outlet Devices #1 Primary 30.50' 24.0" Round Culvert L= 57.7' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 30.50' / 30.21' S= 0.0050 T Cc= 0.900 n= 0.013 Corrugated PE, smooth interior, Flow Area= 3.14 sf Primary OutFlow Max=9.32 cfs @ 12.09 hrs HW=32.23' (Free Discharge) L1=Culvert (Barrel Controls 9.32 cfs @ 4.32 fps) C NTECK ING1NEEND SOLLMNS w I � Brief Stormceptor Sizing Report - South Yarmouth LNG Project Project Info JA Project Name South Yarmouth LNG Project Project Number 50698 City Yarmouth State/ Province Massachusetts Country United States of America Date 10/20/2025 Name Name lff Company Tighe & Bond Company Phone # 970-819-2343 Phone # Email apaoli@tighebond.com Email Stormwater Treatment Recommendation The recommended Stormceptor Model(s) which achieve or exceed the user defined water quality objective for each site within the project are listed in the below Sizing Summary table. ie ame Project MONNOWFT TSS Removal (%) TSS Removal (%) Provided Recommended Stormceptor Mo The recommended Stormceptor Model achieves the water quality objectives based on the selected inputs, historical rainfall records and selected particle size distribution. Stormceptor Model % TSS Removal Provided STC 450i 85 STC 900 91 STC 1200 91 STC 1800 91 STC 2400 94 STC 3600 94 STC 4800 95 STC 6000 96 STC 7200 97 STC 11000 98 STC 13000 98 STC 16000 98 Stormceptor Brief Sizing Report — Page 1 of 2 CONTECK INNNIIRID SOL1A10NS w .�c Alff Total Area (acres) 7.81 Sizing Details AM 9w� TSS Removal (%) 44.0 Imperviousness % 4.3 Runoff Volume Capture (%) Oil Spill Capture Volume (Gal) Station Name HYANNIS Peak Conveyed Flow Rate (CFS) State/Province Massachusetts Water Quality Flow Rate (CFS) Station ID # 3821 • • - • ' Years of Records 14 Storage (ac-ft) Discharge (cfs) Latitude 41 °24'0"N 0.000 0.000 Longitude 70°10'47"W . • � Particle Diameter (microns) 20.0 60.0 150.0 400.0 2000.0 Max. ine Distribution Distribution % 20.0 20.0 20.0 20.0 20.0 Flow to Stormceptor (cfs) Specific Gravity 1.30 1.80 2.20 2.65 2.65 • Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor, which uses the EPA Rainfall and Runoff modules. • Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal defined by the selected PSD, and based on stable site conditions only, after construction is completed. • For submerged applications or sites specific to spill control, please contact your local Stormceptor representative for further design assistance. For Stormceptor Specifications and Drawings Please Visit: https://www.conteches.com/technical-guides/search?filter=1 WBC005EYX Stormceptor Brief Sizing Report — Page 2 of 2 10/22/25, 8:39 AM Precipitation Frequency Data Server NOAA Atlas 14, Volume 10, Version 3 Location name: South Yarmouth, Massachusetts, •b,, USA* Latitude: 41.6884°, Longitude:-70.2009* Elevation: 34 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Pence, Sandra Pavlovic, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Orlan Wilhite NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Average recurrence interval (years) Duration ��� 10 25 50 100 200 500 1000 0.268 0.339 0.455 0.552 0.685 0.784 0.890 1.02 1.21 1.37 5-min (0.215-0.331) (0.271-0.419) (0.362-0.564) (0.437-0.688) (0.524-0.899) (0.587-1.05) (0.647-1.25) (0.689-1.44) (0.786-1.78) (0.869-2.06) 0.380 0.480 0.644 0.781 0.970 1.11 1.26 1.44 1.71 1.94 10-min (0.304-0.468) (0.384-0.593) (0.514-0.799) (0.619-0.974) (0.742-1.27) (0.831-1.49) (0.916-1.77) (0.976-2.04) (1.11-2.52) 1 (1.23-2.91) 0.447 0.565 0.759 0.920 1.14 1.31 1.48 1.70 2.02 2.29 15-min (0.358-0.551) (0.452-0.698) (0.605-0.941) (0.728-1.15) (0.873-1.50) (0.978-1.76) (1.08-2.08) (1.15-2.40) (1.31-2.96) (1.45-3.43) 0.658 0.829 1.11 1.34 1.66 1.90 2.15 2.46 2.93 3.32 30-min (0.527-0.811) (0.663-1.02) (0.883-1.38)1 1 (1.27-2.18) (1.42-2.55) (1.57-3.02) (1.67-3.49) (1.90-4.30) 0.869 1.09 1.46 1.76 2.18 2.49 2.83 3.23 3.84 4.36 60-min (0.696-1.07) (0.874-1.35) 1 (1.16-1.81) 1 l(l.86-3.35) (2.06-3.96) (2.19-4.58) (2.49-5.64) (2.76-6.53) 1.22 1.51 1.99 2.39 2.93 3.34 3.77 4.29 5.07 5.74 2-hr (0.982-1.49) 1 (1.22-1.85) 1 (1.60-2.45) 11 (1.90-2.95) 1 (2.26-3.81) (2.514.44) (2.76-5.22) (2.93-6.02) (3.32-7.36) (3.66-8.49) 1.46 1.79 2.34 2.79 3.41 3.87 1 F 4.37 4.96 5.83 6.57 3-hr (1.18-1.78) 1 (1.44-2.19) 1 (1.88-2.86) 1 1(2.93-5.12) (3.21-6.00) (3.40-6.90) (3.84-8.40) (4.21-9.65) 1.90 2.30 2.96 3.50 4.25 4.82 5.41 6.10 7.11 7.95 6-hr (1.55-2.31) 1 (1.87-2.80) 1 (2.40-3.60) 11 (2.82-4.29) (3.31-5.44) (3.66-6.28) (3.99-7.33) (4.22-8.39) (4.72-10.1) (5.14-11.5) 2.38 2.84 3.60 4.22 5.08 5.73 6.41 7.17 8.26 9.16 12-hr (1.95-2.87) 1 (2.33-3.43) 1 (2.93-4.35) (3.42-5.13) (3.97-6.42) (4.38-7.38) (4.74-8.54) (5.01-9.75) (5.53-11.6) (5.97-13.1) 2.84 3.35 4.18 4.87 5.82 6.54 7.28 8.09 9.22 10.1 24-hr (2.34-3.40) 1 (2.76-4.01) (3.43-5.02) (3.97-5.87) 1 (4.58-7.28) (5.03-8.33) (5.41-9.56) (5.70-10.9) (6.23-12.8) (6.66-14.3) 3.26 3.80 4.68 F 6.42 7.19 IF 7.98 8.82 9.96 10.9 2-day (2.71-3.87) (3.15-4.52) (3.87-5.58) (4.45-6.49) (5.09-7.96) (5.57-9.06) (5.96-10.3) (6.26-11.7) (6.79-13.6) (7.21-15.1) 3.55 4.09 4.99 5.74 6.76 7.54 8.34 9.18 10.3 11.2 3-day (2.96-4.19) (3.41-4.85) (4.14-5.92) 1 (5.38-8.32) (5.86-9.44) (6.26-10.7) (6.56-12.1) (7.08-14.0) (7.50-15.5) 3.79 4.34 5.24 5.99 7.02 F 7.80 8.60 9.46 10.6 11.6 4-day (3.17-4.47) (3.63-5.13) (4.36-6.21) (4.96-7.12) (5.60-8.62) (6.09-9.73) (6.48-11.0) (6.78-12.4) (7.32-14.4) (7.76-15.9) 4.44 4.99 5.91 6.67 7.71 8.51 9.33 10.2 11.4 12.3 7-day (3.73-5.20) (4.20-5.86) (4.95-6.95) (5.55-7.88) (6.20-9.39) (6.68-10.5) (7.06-11.8) (7.35-13.2) (7.86-15.2) (8.27-16.7) 5.04 5.62 6.57 7.36 8.44 9.27 10.1 11.0 12.2 13.1 10-day (4.25-5.89) (4.74-6.57) (5.52-7.70) (6.14-8.66) (6.80-10.2) (7.30-11.4) (7.68-12.7) (7.97-14.2) (8.46-16.1) 6.86 7.55 8.66 9.59 10.9 11.9 12.8 13.8 15.0 15.8 20-day (5.84-7.97) (6.41-8.76) (7.33-10.1) 11 (8.06-11.2) 1 (8.81-1 3.0) (9.38-14.4) (9.78-15.9) (10.1-17.5) (10.5-19.6) (10.8-21.0) 8 9.21 10.5 11.5 13.0 14.1 15.2 16.2 17.4 18.3 30-day .43 (7.20-9.74) (7.85-10.6) 1 (8.90-12.1) 1 1 (10.6-15.4) (11.2-17.0) (11.6-18.6) (11.9-20.5) (12.3-22.6) (12.6-24.1) 10.4 11.3 12.8 14.0 15.6 17.0 18.2 19.3 20.6 21.4 45-day (8.95-12.0) (9.70-13.0) 1 (10.9-14.7) 11 (11.9-16.2) 1 (12.8-18.5) (13.5-20.3) (13.9-22.1) (14.3-24.2) (14.6-26.5) (14.8-28.0) 12.2 13.1 14.7 16.1 17.9 19.3 20.7 21.9 23.2 24.1 60-day (10.5-14.0) (11.3-15.1) (12.6-17.0) (13.7-18.5) (14.7-21.0) (15.5-23.0) (15.9-25.0) (16.2-27.3) (16.6-29.7) (16.7-31.3) Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PIMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=41.6884&Ion=-70.2009&data=depth&units=english&series=pds 1/4 Project: C5200-001 Tighe&Bond Date: AEP 2025 Pipe Material Calculated by: EP Roughness Coefficlera 0.012 RCP Checked by: TJG 0.at3 HDPE Upstream structure Downstream Structure Anticipated Flow (cfs)• Pipe Dia. (in) Pipe Material Pipe Area (sf) Pipe Length (ft) Upstream Invert Downstream Invert Pipe Slope (ft/ft) Hydr. Radius (ft) Full -Pipe Velocity (fps) Full -Pipe Flow (cfs) CB 1 DMH 1 150 12 HDPE 0.785 47.75 33.00 32.75 0.005 0.25 3.29 2.58 Trench 1 DMH 1 3J7 12 HDPE 0.785 58.95 34.70 33.50 0.020 0.25 6.49 5.10 DMH 1 DMH 2 5.21 18 HDPE 1.767 91.75 30.34 29.90 0.005 0.38 4.13 7.29 DMH 2 DMH 3 5.21 18 HDPE 1.767 115.25 29.87 29.40 0.004 0.38 3.81 6.73 DMH 3 SWTU 1 12.81 24 HDPE 3.142 155.25 29.31 28.64 0.005 0.50 5.08 15.97 CB 2 DMH 3 7.61 24 HDPE 3.142 57.7 30.50 30.21 0.005 0.50 5.12 16.08 SWTU 1 Basin 12.81 24 HDPE 3.142 72 28.54 28.16 0.005 0.50 5.25 16.48 Trench 2 Basin 8.61 18 HDPE 1.767 133.8 33.00 30.00 0.022 0.38 8.92 15.77 Trench 3 DMH 4 0.48 8 HDPE 0.349 165 34.10 33.18 0.006 0.17 2.59 0.90 DMH 4 CB 1 0.48 8 HDPE 0.349 37 33.18 33.00 0.005 0.17 2.42 0.85 APPENDIX E CONSTRUCTION PERIOD EROSION AND SEDIMENTATION CONTROL PLAN SOUTH YARMOUTH PROJECT SOUTH YARMOUTH, MASSACHUSETTS DECEMBER 2025 Prepared for: National Grid Table of Contents Tighe&Bond Section 1 Introduction Section 2 Project Information 2.1 Plan Contents................................................................................2-1 2.2 Project/ Site Information.................................................................2-1 2.3 Nature of the Construction Activity...................................................2-1 2.4 Sequence and Estimated Dates of Construction Activities ....................2-2 2.4.1 Construction Schedule..........................................................2-2 2.5 Allowable Non-Stormwater Discharges..............................................2-3 2.6 Site Maps......................................................................................2-3 Section 3 Erosion and Sediment Controls 3.1 Perimeter Controls.........................................................................3-1 3.2 Sediment Track-Out.......................................................................3-2 3.3 Stockpiled Sediment or Soil.............................................................3-2 3.4 Minimize Dust................................................................................3-3 3.5 Minimize the Disturbance of Steep Slopes.........................................3-3 3.6 Topsoil/Loam Areas........................................................................3-4 3.7 Soil Compaction.............................................................................3-4 3.8 Storm Drain Inlets..........................................................................3-4 3.9 Sediment Traps.............................................................................3-5 3.10 Dewatering Practices......................................................................3-5 3.11 Site Stabilization............................................................................3-6 3.11.1 Seeding..............................................................................3-7 3.11.2 Mulching.............................................................................3-7 Section 4 Pollution Prevention Standards 4.1 Potential Sources of Pollution...........................................................4-1 4.2 Spill Prevention and Response.........................................................4-1 4.2.1 Federal and State Spill Notification.........................................4-2 4.2.2 Local Notification..................................................................4-2 4.3 Fueling and Maintenance of Equipment or Vehicles.............................4-3 4.4 Washing of Equipment and Vehicles..................................................4-3 4.5 Storage, Handling, and Disposal of Construction Products, Materials, and Wastes.........................................................................................4-4 4.5.1 Building Products.................................................................4-4 4.5.2 Pesticides, Herbicides, Insecticides, Fertilizers, and Landscaping Materials.............................................................................4-4 4.5.3 Diesel Fuel, Oil, Hydraulic Fluids, Other Petroleum Products, and Other Chemicals...................................................................4-4 4.5.4 Hazardous or Toxic Waste.....................................................4-4 4.5.5 Construction and Domestic Waste..........................................4-5 Table of Contents Tighe&Bond 4.5.6 Sanitary Waste....................................................................4-5 4.6 Washing of Applicators and Containers used for Paint, Concrete or Other Materials.......................................................................................4-5 4.7 Fertilizers......................................................................................4-6 J:\C\C5200 CH-IV\South Yarmouth LNG - 001\Permitting\Stormwater\Appendix E - Construction Period LTPPP and Erosion Controls\Construction Period PPP and Erosion and Sediment Controls.doc Tighe&Bond Section 1 Introduction Stormwater runoff from construction activities can have a significant impact on water quality. As stormwater flows over a construction site, it can pick up pollutants like sediment, debris, and chemicals and transport these to a nearby storm sewer system or directly to a river, lake, or coastal water. Polluted stormwater runoff can harm or kill fish and other wildlife. Sedimentation can destroy aquatic habitat, and high volumes of runoff can cause stream bank erosion. Debris can clog waterways and potentially reach the ocean where it can kill marine wildlife and impact habitat. Standard 8 of the Massachusetts Stormwater Standards requires: "a plan to control construction -related impacts including erosion, sedimentation and other pollutant sources during construction and land disturbance activities (construction period erosion, sedimentation, and pollution prevention plan) shall be developed and implemented". The following Erosion and Sediment Control Plan (ESCP) identifies the requirements to comply with Standard 8. Erosion and Sediment Control Plan Tighe&Bond Section 2 Project Information 2.1 Plan Contents This ESCP was developed for the South Yarmouth LNG Project in South Yarmouth, Massachusetts. This ESCP provides permit -related information to satisfy the requirements of Standard 8 of the Massachusetts Stormwater Handbook. 2.2 Project/ Site Information Project Name and Address Project/Site Name: South Yarmouth LNG Project Project Street/Location: 127 Whites Path City: South Yarmouth State: Massachusetts ZIP Code: 02664 County or Similar Subdivision: Barnstable County 2.3 Nature of the Construction Activity General Description of Project The proposed project includes the construction of a new LNG tank, all associated infrastructure and a stormwater management system for the areas affected by construction. The existing tank will remain online until completion of the new tank and then will be taken offline and removed. Other drainage improvements include trench drains, swales, and catch basin structures to collect and convey stormwater away from the LNG tanks and the existing site area. Size of Construction Project Total size of the property: 31.83 Acres Total area expected to be disturbed by the construction activities: 7.8 Acres The maximum area expected to be disturbed at any one time (in acres): 7.8 Acres TABLE 2-4 Pollutant -Generating Activities Pollutant -Generating Activity Pollutants or Pollutant Constituents (that could be discharged if exposed to stormwater) Site work Soil particles and fines Paving and construction areas Petroleum, concrete, vehicle fluids, paints, solvents Disinfection of water mains Chlorine, dechlorination chemicals Erosion and Sediment Control Plan 2-1 Section 2 Site Evaluation, Assessment, and Planning Tighe&Bond Pollutant -Generating Activity Pollutants or Pollutant Constituents (that could be discharged if exposed to stormwater) Concrete construction Concrete Pavement marking Paint Solid waste storage Construction debris, trash Fertilizing Fertilizers Equipment use Hydraulic Oils/fluids Equipment use Antifreeze/coolant Portable toilets Sewage Staging areas Sediment, gasoline, fuel oil, concrete, vehicle fluids, paints, solvents, fertilizers, adhesives, antifreeze/coolant, hydraulic oil/fluid, etc. Construction Support Activities If applicable, describe any construction support activities for the project (e.g., concrete or asphalt batch plants, equipment staging yards, material storage areas, excavated material disposal areas, borrow areas) Activity: TBD Location: Description: Contact information for construction support activity: Name: Telephone No: Email: 2.4 Sequence and Estimated Dates of Construction Activities The following is an anticipated construction sequence identifying the major components of construction for the project. 2.4.1 Construction Schedule Estimated Start Date of Construction Activities for this Phase SPRING 2026 Estimated End Date of Construction Activities for this Phase FALL 2026 Estimated Date(s) of Application of Stabilization Measures for SPRING 2026 Areas of the Site Required to be Stabilized Estimated Date(s) when Stormwater Controls will be Removed FALL 2029 Erosion and Sediment Control Plan 2-2 Section 2 Site Evaluation, Assessment, and Planning Tighe&Bond 2.5 Allowable Non-Stormwater Discharges Water from non-stormwater sources are allowed when properly managed. The following identifies discharge sources anticipated with the project. TABLE 2-5 List of Allowable Non-Stormwater Discharges Present at the Site Likely to be Type of Allowable Non-Stormwater Discharge Present at Your Location on Site Site? Discharges from emergency fire -fighting activities ❑ YES ® NO Fire hydrant flushings ® YES ❑ NO Landscape irrigation ❑ YES ® NO Waters used to wash vehicles and equipment' ❑ YES ® NO Water used to control dust ® YES ❑ NO Throughout site Potable water including uncontaminated water line ❑ YES ® NO flushings External building wash down, provided soaps, ❑ YES ® NO solvents, and detergents are not used, and external surfaces do not contain hazardous substances (e.g. see Appendix A) (e.g. paint or caulk containing PCBs) Pavement wash waters2 ❑ YES ® NO Uncontaminated air conditioning or compressor ❑ YES ® NO condensate Uncontaminated, non -turbid discharges of ground ❑ YES ® NO water or spring water Foundation or footing drains ❑ YES ® NO Construction dewatering water4 ❑ YES ® NO 'provided that there is no discharge of soaps, solvents, or detergents used for such purposes 2provided spills or leaks of toxic or hazardous substances have not occurred (unless all spill material has been removed) and where soaps, solvents, and detergents are not used. You are prohibited from directing pavement wash waters directly into any water of the U.S., storm drain inlet, or stormwater conveyance, unless the conveyance is connected to a sediment basin, sediment trap, or similarly effective control; 3where flows are not contaminated with process materials sucks as solvents or contaminated ground water 4discharged in accordance with applicable regulations * No untreated or contaminated groundwater will be discharged to wetlands or waterways. Excess water will be discharged overland in upland areas and allowed to naturally infiltrate in well -drained soils, or discharged to wetlands or streams only after passing through filtration sacks or similar devices. 2.6 Site Maps An Erosion and Sediment Control Plan (ESCP) has been prepared to provide the Contractor will the minimum requirements for the prevention of erosion and sedimentation due to consruction impacts. The ESCP is provided in the Site Plans. The Erosion and Sediment Control Plan 2-3 Section 2 Site Evaluation, Assessment, and Planning Tighe&Bond ESCP provides locations of perimeter erosion controls, inlet controls, and construction - period stormwter management features such as sediment traps. Erosion and Sediment Control Plan 2-4 Tighe&Bond Section 3 Erosion and Sediment Controls The Contractor must implement erosion and sediment controls in accordance with the following requirements to minimize the discharge of pollutants in stormwater from construction activities. This project also includes site specific controls and permit conditions which may take precedent and are not included in the following descriptions. The Contractor shall also comply with the requirements in the project's permits. 3.1 Perimeter Controls Provide perimeter controls to prevent sediment from entering and compromising the adjacent storm drain system. General Roadways and storm drainage components adjacent to the proposed project area will be protected by a row of erosion control barriers. The erosion control barriers will consist of straw wattles or mulch -filled tubes (e.g. compost filter tubes/socks) and siltation fencing placed in a fashion that restricts the contractor(s) to the areas necessary to conduct the work and will generally define the limits of work. The locations of these barriers are shown on the project drawings. Specific Perimeter Controls Perimeter Control Description • Perimeter controls include the installation of a straw wattle or mulch log barrier and siltation fence system around the perimeter of the site. Perform work in accordance with the ESCP. Installation • Temporary erosion control measures shall be installed prior to the start of any earth disturbing activities. • Erosion control barriers shall not be removed until their removal is approved by the Engineer. Maintenance Requirements • The contractor(s) will be required to maintain a reserve supply of erosion control barriers on -site to make repairs, as necessary. • Perimeter control shall be inspected immediately after each rainfall and at least daily during prolonged rainfall. They shall be repaired if there are any signs of erosion or sedimentation below them, any repairs shall be made immediately. If there are signs of undercutting at the center or the edges, or impounding of large volumes of water behind them, sediment barriers shall be replaced with a temporary check dam. • Should the fabric on a barrier decompose or become ineffective prior to the end of the expected usable life and the barrier still is necessary, the fabric shall be replaced promptly. • Sediment deposits should be removed after each storm event. They must be removed when deposits reach approximated 1/3 the height of the barrier. Erosion and Sediment Control Plan 3-1 Section 3 Erosion and Sediment Controls Tighe&Bond At the conclusion of the project, the erosion control barriers will be removed and properly disposed off -site following the stabilization of disturbed areas. 3.2 Sediment Track -Out General It is the Contractor's responsibility to take measures to prevent tracking of sediment from the project site. It is also the Contractor's responsibility to take measures to prevent tracking of sediment from any staging and material storage area. A stone tracking pad and street sweeping apparatus shall be used as necessary to minimize the track -out of sediment onto adjacent streets, other paved areas, and sidewalks from vehicles exiting the construction site. Specific Track -Out Controls Track -Out Controls Description • Stone aggregate tracking pad • Street sweeping Installation • Sediment track out controls to be installed by the Contractor include a stone aggregate tracking pad with an underlying geotextile fabric. The pad shall be constructed in accordance with the ESCP. Maintenance Requirements • The site exit shall be maintained in a condition which will prevent tracking of sediment onto public right-of-way. When washing is required, it shall be done in an area stabilized with aggregate which drains into a sediment trapping controls. • If sediment is tracked out from the site to the surface of off -site streets, other paved areas, and sidewalks, the Contractor shall remove the deposited sediment by the end of the same work day in which the track -out occurs. 3.3 Stockpiled Sediment or Soil General Temporary soil stockpiles shall be surrounded by hay bales or silt fence and shall be stabilized by covering or temporary erosion control seeding. Stockpiles are to be located as far as possible from any surface water. Specific Stockpile Controls Description • Temporary stockpiles of excavated soil may be present at the site as construction progresses. Installation • Install a sediment barrier consisting of silt fencing or straw bales along downgradient perimeter areas of stockpiles. Erosion and Sediment Control Plan 3-2 Section 3 Erosion and Sediment Controls Tighe&Bond • For piles that will be unused for 14 or more days, temporary stabilization with erosion control seeding shall be used if perimeter controls and/or temporary covering are not sufficient to prevent sediment migration. Maintenance Requirements • Do not hose down or sweep soil or sediment accumulated on pavement or other impervious surfaces into any stormwater conveyance (unless connected to a sediment basin, sediment trap, or similarly effective control), storm drain inlet, or surface water. 3.4 Minimize Dust General The Contactor shall be responsible for the control of dust throughout the construction period. Dust control methods shall include, but be not limited to, sprinkling water or calcium chloride on exposed areas, covering loaded dump trucks leaving the site, and temporary mulching exposed soil areas. Dust control measures shall be utilized to prevent the migration of dust from the site to abutting areas. Specific Dust Controls Description • Prevent dust from becoming a nuisance or hazard. During construction, excavated material and open or stripped areas are to be policed and controlled to prevent spreading of the material. • Dust control measures shall be utilized to prevent the migration of dust from the site to abutting areas. • Ensure that the existing equipment, facilities, and occupied space adjacent to or nearby areas of the work do not come in contact with dust or debris as a result of concrete demolition, excavation or surface preparation. Installation • Dust control methods shall include, but be not limited to, sprinkling water on exposed areas, using calcium chloride, covering loaded dump trucks leaving the site, and temporary mulching. • Use a mechanical street sweeper daily. Maintenance Requirements • During the work on -site, daily all paved road and driveway surfaces shall be scraped and broomed free of excavated materials on a daily basis. Prior to sweeping, or as needed during the work day, the surfaces shall be hosed down or otherwise treated to eliminate active or potential dust conditions and the natural road or wearing surface shall be exposed. 3.5 Minimize the Disturbance of Steep Slopes General All slopes greater than 15% during the regular construction season are to have slope stabilization measures. This applies to all slopes greater than 8% after October 15t Erosion and Sediment Control Plan 3-3 Section 3 Erosion and Sediment Controls Tighe&Bond Specific Steep Slope Controls • Where slopes greater than 3:1 will be created, synthetic erosion control fabric is to be utilized in these areas to prevent erosion until permanent vegetation is established. 3.6 Topsoil/Loam Areas General All areas not to be paved or otherwise treated shall receive 4-inch loam and seed. The salvaging of existing loam and topsoil is not anticipated due to the urban nature of the site. Specific Topsoil/Loam Area Controls Description • Erosion of topsoil/ loam areas will be controlled by providing temporary and perminant grass cover. • Where slopes greater than 3:1 will be created, synthetic erosion control fabric will be utilized to prevent erosion until permanent vegetation is established. Installation • Temporary vegetative cover shall be provided to stabilize the site in areas where additional construction activity will not occur for more than 14 calendar days. Maintenance Requirements • Seeding shall be inspected periodically and at a minimum 95% of the soil surface should be covered by vegetation. If any evidence of erosion is apparent, repairs shall be made and additional measures shall be used to prevent further erosion. • Straw mulch, wood fiber mulch, or erosion control blankets shall be applied immediately after seeding. 3.7 Soil Compaction General In areas where final vegetative stabilization is proposed, the Contractor shall prevent excessive compaction by: • Restricting vehicle and equipment use in these locations to avoid excessive soil compaction; or • Prior to seeding or planting areas of exposed soil that have been compacted, use techniques that aerates the soils resulting in conditions that will support vegetative growith. 3.8 Storm Drain Inlets General Provide catch basin inlet protection as per construction drawings and specifications in all catch basins within the vicinity of the earth disturbing activities to protect the Erosion and Sediment Control Plan 3-4 Section 3 Erosion and Sediment Controls Tighe&Bond stormwater management system from high sediment loads and high velocities, while disturbance due to construction is occurring in the drainage area. Specific Storm Drain Inlet Controls Description • Storm Drain Inlet Controls include the installation of Silt Sacks • Refer to the ESCP for inlet control locations. Installation • Refer to manufacturer recommended specifications and instillation instructions. Maintenance Requirements • Silt sacks shall be inspected immediately after each rainfall and at least daily during prolonged rainfall. They shall be repaired or replaced as needed immediately. • Sediment deposits should be removed after each storm event. They must be cleaned when deposits reach approximated 1/3 the height of the barrier. • The Contractor shall remove the deposited sediment and make any repairs by the end of the same work day in which the sediment is observed or by the end of the next work day if observation occurs on a non -work day. 3.9 Sediment Traps General Permanent sediment basins are not proposed as part of the final stormwater management system, however, temporary sediment basins or sediment traps may be used during construction to retain runoff and settle out particles prior to discharge from the site. Specific Sediment Basin/Sediment Trap Controls Description • Temporary sediment basins or sediment traps may be excavations or bermed detention areas on site with stabilized discharges. Installation • As required due to site conditions and activities. Maintenance Requirements • Contractor shall periodically remove sediments and dispose of them in an appropriate location. Discharge locations shall be inspected regularly and stabilized as necessary. 3.10Dewatering Practices General Erosion and Sediment Control Plan 3-5 Section 3 Erosion and Sediment Controls Tighe&Bond Dewatering is not anticipated for this project. Standard dewatering measures will be employed. No untreated groundwater will be discharged to wetlands or waterways. Excess water will be discharged overland in upgradient areas and allowed to naturally infiltrate, or discharged to the drainage system only after passing through filtration sacks or similar devices. Specific Dewatering Practices Dewatering Practice Description • Provide, operate and maintain adequate pumping, diversion and drainage facilities in accordance with the approved dewatering plan to maintain the excavated area sufficiently dry from groundwater and/or surface runoff so as not to adversely affect construction procedures nor cause excessive disturbance of underlying natural ground. Locate dewatering system components so that they do not interfere with construction under this or other contracts. • Install erosion/sedimentation controls for velocity dissipation at point discharges onto non -paved surfaces. Installation • Install sand and gravel, or crushed stone, filters in conjunction with sumps, well points, and/or deep wells to prevent the migration of fines from the existing soil during the dewatering operation. • Transport pumped or drained water without interference to other work, damage to pavement, other surfaces, or property. Pump water through a silt filter bag prior to discharge to grade or drainage system. • Do not discharge water into any separated sanitary sewer system. Maintenance Requirements • Repair any damage resulting from the failure of the dewatering operations and any damage resulting from the failure to maintain all the areas of work in a suitable dry condition. • Take actions necessary to ensure that dewatering discharges comply with permits applicable to the Project. Dispose of water from the trenches and excavations in such a manner as to avoid public nuisance, injury to public health or the environment, damage to public or private property, or damage to the work completed or in progress. 3.11Site Stabilization General Initiate site stabilization measures immediately whenever earth -disturbing activities have permanently ceased or will be temporarily suspended on any portion of the site for more than 14 days. Complete the stabilization activities within 14 days after the permanent or temporary cessation of earth -disturbing activities. Temporary paving of disturbed areas of existing roads should be completed at a minimum at the end of each week. Use the following stabilization practices to protect exposed soil from erosion and prevent sediment movement. Erosion and Sediment Control Plan 3-6 Section 3 Erosion and Sediment Controls Tighe&Bond 3.11.1 Seeding Installation • When construction has temporarily or permanently ceased, seeding shall occur immediately in accordance with the project specifications. Maintenance Requirements • Periodic inspections shall occur once a week and after every rainstorm of 0.25 inches or greater until a minimum of 70% of the soil surface is covered by vegetation. 3.11.2 Mulching Installation • When construction has temprorarily or permanently ceased, mulching shall occur immediately, as required, for erosion control while vegetation is being established. Maintenance Requirements • Periodic inspections shall occur once a week and after every rainstorm 0.25 inches or greater. Erosion and Sediment Control Plan 3-7 Tighe&Bond Section 4 Pollution Prevention Standards A clean and orderly construction site will reduce the opportunity for pollutants to enter the stormwater runoff stream. The following identifies sources of pollution anticipated on a typical construction site and preventative measures to avoid pollution. 4.1 Potential Sources of Pollution TABLE 4-1 Construction Site Pollutants Pollutant -Generating Pollutants or Pollutant Location on Site Activity Constituents Site work Soil particals and fines Where disturbance is proposed Paving and construction areas Petroleum, concrete, vehicle Where paving and construction is fluids, paints, solvents proposed Disinfection of water mains Chlorine, dechlorination chemicals Where water mains are proposed Concrete construction Concrete Where concrete is proposed Pavement marking Paint Where pavement markings are proposed Solid waste storage Construction debris, trash In dumpster locations Fertilizing Fertilizers In areas of proposed seeding Equipment use Hydraulic Oils/fluids Leaks/broken hoses from equipment Equipment use Antifreeze/coolant Leaks/broken hoses from equipment Portable toilets Sewage Where portable toilets are located Sediment, gasoline, fuel oil, concrete, vehicle fluids, paints, Staging areas solvents, fertilizers, adhesives, antifreeze/coolant, hydraulic oil/fluid, etc. 4.2 Spill Prevention and Response • Manufacturer's recommended methods for cleanup will be clearly posted and site personnel will be made aware of the procedures and the location of the information and clean up supplies. • Materials and equipment necessary for spill cleanup will be kept in the material storage areas on site. Equipment and materials will include but not be limited to 4-1 Section 4 Pollution Prevention Standards Tighe&Bond brooms, dustpans, mops, rags, gloves, goggles, kitty litter, sand, sawdust and plastic or metal trash containers specifically for this purpose. • All spills will be cleaned up immediately after discovery. • The spill area will be kept well ventilated and personnel will wear appropriate protective clothing to prevent injury from contact with hazardous substances. • Spills of toxic or hazardous material will be reported to the appropriate state or local government agency regardless of size. • The Spill Prevention Plan will be adjusted to include measures to prevent this type of spill from recurring and how to cleanup the spill if it recurs. A description of the spill, its cause and the cleanup measures will be included. • The site superintendent responsible for day to day operations will be the Spill Response Coordinator (SRC). The SRC is responsible for decisive actions in the event of a spill at the facility. The SRC will supervise efforts to provide immediate containment of the spill to prevent a more difficult cleanup situation. Cleanup crews will utilize proper spill cleanup materials and employ safe work practices. 4.2.1 Federal and State Spill Notification In accordance with 310 CMR 40.0333, the SRC shall notify the Massachusetts Department of Environmental Protection (Southeast Region) - (508)-946-2700, the Local Emergency Planning Committee (LEPC) and any other authorities or agencies within two hours if an accident or other type of incident results in a release to: • Land 0 10 Gallons for more Oils (PCB<500 ppm) 0 1 Gallon or more Oils (PCB >_500 ppm) • Waterways 0 Any quantity of Oils • Or, triggers the exposure to toxic chemical levels as listed in 301 CMR 40.1600, Revised Massachusetts Contingency Plan The SRC shall notify the National Response Center (NRC) at (800) 424-8802 where a leak, spill, or other release containing a hazardous substance or oil in an amount equal to or in excess of a reportable quantity consistent with Part 2.3.3.4c and established under either 40 CFR Part 110, 40 CFR Part 117, or 40 CFR Part 302, occurs during a 24- hour period. In either event, the SRC will work with state and federal agencies to ensure that all appropriate forms and reports are submitted in a timely manner. • Note: Trigger volumes for other chemical spills vary. Contact the DEP or a Licensed Site Professional (LSP) for specific guidance on reporting thresholds and requirements for other chemicals. 4.2.2 Local Notification The following local agencies will be called to provide emergency assistance at the facility on the judgment of the SRC: Erosion and Sediment Control Plan Section 4 Pollution Prevention Standards Tighe&Bond TABLE 4-2 Emergency Assistance Notification Fire Department Police Department 911 or (508)-398-2212 911 or (508)-775-0445 Hospital: Department of Public Works: Cape Cod Hospital (508)-398-2231 ext. 1250 (508)-771-1800 4.3 Fueling and Maintenance of Equipment or Vehicles General Efforts shall be made to perform equipment/vehicle fueling and maintenance off -site. If fueling and/or maintenance of equipment of vehicles is performed on site, the following pollution prevention practices must be provided. Specific Pollution Prevention Practices • Site contractor/project manager shall provide an onsite vehicle fueling and maintenance area that is clean and dry. • If possible keep area covered. • Keep a spill kit at the fueling and maintenance area. • Vehicles shall be inspected regularly for leaks and damage. • Use drip pans, drip cloths or absorbent pads when replacing spent fluid. 4.4 Washing of Equipment and Vehicles General Efforts shall be made to perform equipment/vehicle washing and maintenance off -site. If washing of equipment and vehicles is performed on site, the following pollution prevention practices must be provided to minimize the discharge of pollutants. Specific Pollution Prevention Practices • Site contractor/project manager shall provide a proper washing area. • Discharges from washing areas shall be infiltrated or diverted into sanitary sewer system unless no soaps or detergents are used. • If soaps, detergents or solvents are stored onsite over must be provided to prevent these detergents from coming into contact with rainwater. Erosion and Sediment Control Plan Section 4 Pollution Prevention Standards Tighe&Bond 4.5 Storage, Handling, and Disposal of Construction Products, Materials, and Wastes 4.5.1 Building Products • Site contractor/project manager shall designate a waste collection area on the site that does not receive a substantial amount of runoff from upland areas and does not drain directly to a water body. • Ensure that containers have lids so they can be covered before periods of rain, and keep containers in a covered area whenever possible. • Schedule waste collection to prevent the containers from overfilling. • Clean up spills immediately. For hazardous materials, follow cleanup instructions on the package. Use an absorbent material such as sawdust or kitty litter to contain the spill. • During the demolition phase of construction, provide extra containers and schedule more frequent pickups. • Collect, remove, and dispose of all construction site wastes at authorized disposal areas. 4.5.2 Pesticides, Herbicides, Insecticides, Fertilizers, and Landscaping Materials • Store new and used materials in a neat, orderly manner in their appropriate containers in a covered area. If storage in a covered area is not possible, the materials shall be covered with polyethylene or polypropylene sheeting to protect them from the elements. • Storage area should include precautions to contain any potential spills. • Immediately contain and clean up any spills with absorbent materials. 4.5.3 Diesel Fuel, Oil, Hydraulic Fluids, Other Petroleum Products, and Other Chemicals • Store new and used petroleum products for vehicles in a neat, orderly manner in their appropriate containers in a covered area. If storage in a covered area is not possible, the materials shall be covered with polyethylene or polypropylene sheeting to protect them from the elements. • Storage area should include precautions to contain any potential spills. • Immediately contain and clean up any spills with absorbent material. • Have equipment available in fuel storage areas and in vehicles to contain and clean up any spills that occur. 4.5.4 Hazardous or Toxic Waste • Store new and used materials in a neat, orderly manner in their appropriate containers in a covered area. If storage in a covered area is not possible, the materials shall be covered with polyethylene or polypropylene sheeting to protect them from the elements. • Storage areas should include precautions to contain any potential spills. Erosion and Sediment Control Plan Section 4 Pollution Prevention Standards Tighe&Bond • Immediately contain and clean up any spills with absorbent materials. • Have equipment available in fuel storage areas and in vehicles to contain and clean up any spills that occur. • To prevent leaks, empty and clean hazerdous waste containers before disposing of them. • Never remove the original product label from the container because it contains important safety information. Follow the manufacturer's recommended method of disposal, which should be printed on the label. • Never mix excess products when disposing of them, unless specifically recommended by the manufacturer. 4.5.5 Construction and Domestic Waste • All materials shall be collected and stored in securely lidded receptacles, no construction waste materials will be buried. Clean up immediately if containers overflow. 4.5.6 Sanitary Waste • Portable sanitary units will be provided throughout the course of the project for use by the site contractor/project manager's employees. A licensed sanitary waste management contractor will regularly collect all sanitary waste from the portable units. Position portable toilets so that they are secure and will not be tipped or knocked over. 4.6 Washing of Applicators and Containers used for Paint, Concrete or Other Materials • The contractors should be encouraged where possible, to use washout facilities at their own plant or dispatch facility from stucco, paint, concrete, form release oils, curing compounds, and other construction materials. If washout of these materials in done on site: o Direct all washwater into a leak -proof container or leak -proof pit. The container or pit must be designed so that no overflows can occur due to inadequate sizing or precipitation. o Handle washout or cleanout wastes as follows: ■ Do not dump liquid wastes in the storm sewers ■ Dispose of liquid wastes in accordance with applicable regulations ■ Remove and dispose of hardened concrete waste consistent with your handling of other construction wastes in Section 5.5. o Attempts should be made to locate washout area as far away as possible from surface waters and storwmater inlets or conveyances, and to the extend practicable, designate areas to buse for these activities and conduct such activities only in these areas. • Inspect washout facilities daily to detect leaks or tears and to identify when materials need to be removed. Erosion and Sediment Control Plan Section 4 Pollution Prevention Standards Tighe&Bond 4.7 Fertilizers If fertilizers are to be used on site, the following requirements shall be followed: • Store new and used materials in a neat, orderly manner in their appropriate containers in a covered area. If storage in a covered area is not possible, the materials shall be covered with polyethylene or polypropylene sheeting to protect them from the elements. • Storage area should include precautions to contain any potential spills. • Immediately contain and clean up any spills with absorbent materials. • Apply at a rate and in amounts consistent with manufacturer's specifications, or document departures from the manufacturer's specifications. • Apply at the appropriate time of year for the site, and preferably timed to coincide as closely as possible to the period of maximum vegetation uptake and growth • Avoid applying before heavy rains that could cause excessive nutrients to be discharged • Never apply to frozen ground • Never apply to stormwater conveyance channels with flowing water • Follow all federal, state, tribal, and local requirements regarding fertilizer application. Erosion and Sediment Control Plan APPENDIX F LONG-TERM POLLUTION PREVENTION AND STORMWATER MANAGEMENT SYSTEM OPERATION AND MAINTENANCE PLAN SOUTH YARMOUTH LNG PROJECT SOUTH YARMOUTH, MASSACHUSETTS DECEMBER 2025 Prepared for: National Grid Table of Contents Tighe&Bond Section 1 Introduction and Purpose Section 2 Responsible Parties Section 3 Long Term Pollution Prevention Plan 3.1 Good Housekeeping........................................................................3-1 3.1.1 Local Standards...................................................................3-1 3.2 Potential Sources of Pollution...........................................................3-2 3.3 General Spill Prevention and Response..............................................3-2 3.3.1 Federal and State Spill Notification.........................................3-3 3.3.2 Local Notification..................................................................3-3 3.4 Storage, Handling, and Disposal of Materials and Wastes ....................3-4 3.4.1 Pesticides, Herbicides, Insecticides, Fertilizers, and Landscaping Materials.............................................................................3-4 3.4.3 Hazardous or Toxic Waste.....................................................3-4 3.4.4 Domestic Waste...................................................................3-5 Section 4 Stormwater Management System 4.1 Inspections....................................................................................4-1 4.1.1 Vegetated Surfaces..............................................................4-1 4.1.2 Driveway and Walkway Sweeping...........................................4-1 4.1.3 Deep -Sump, Hooded Catch Basins..........................................4-1 4.1.4 Proprietary Water Treatment Devices.....................................4-2 4.1.6 Surface Infiltration Basin.......................................................4-2 4.1.7 Infiltration Trenches.............................................................4-2 4.1.13 Stone End Protection (Outfalls)..............................................4-3 Section 5 Operation and Maintenance Log Form Section 6 Snow Management & De -Icing Section 7 Estimated O&M Budget Table of Contents Tighe&Bond Appendices Stormwater BMP Location Map ]:\C\C5200 CH-IV\South Yarmouth LNG - 001\Permitting\Stormwater\Appendix F - Stormwater 0&M\Long Term Pollution Prevention and Stormwater Management OM Plan.doc Tighe&Bond Section 1 Introduction and Purpose The following Long -Term Pollution Prevention and Stormwater Operations and Maintenance (O&M) Plan has been prepared for the stormwater management system at the proposed South Yarmouth LNG project in South Yarmouth, Massachusetts. The purpose of the plan is to provide guidance and procedures for proper pollution prevention and stormwater management system maintenance following construction completion. The proposed project has been designed in compliance with the Massachusetts Department of Environmental Protection (MassDEP) Stormwater Handbook and the Town of Yarmouth Stormwater Regulations to maintain or improve stormwater runoff quality and quantity. The stormwater management system components shall be maintained as recommended in the Massachusetts Stormwater Handbook. Long Term O&M Plan 2-1 Tighe&Bond Section 2 Responsible Parties National Grid is responsible for maintaining and servicing the proposed driveway, paved and unpaved parking and storage areas, landscaping, utility infrastructure and the stormwater management facilities post construction. The property is owned by Boston Gas Company. During construction, the contractor will be responsible for stormwater management system maintenance. Applicant/Property Owner: Matthew T. Wozniak Boston Gas Company DBA National Grid 170 Data Drive Waltham, MA 02451 Applicant Signature, date: j (,{J� 12/12/25 Maintenance Contact: Jaylon Todman Boston Gas Company DBA National Grid 127 Whites Path South Yarmouth, MA 02664 Maintenance Contact j�cr Signature, date: 12/12/25 Long Term O&M Plan 2-1 Tighe&Bond Section 3 Long Term Pollution Prevention Plan 3.1 Good Housekeeping The goal of the good housekeeping policy is to keep the site in a clean and orderly condition. A disorderly site can lead to improper materials management and can reduce the efficiency of any response to potential pollution problems. The following good housekeeping measures will be followed at the site to aid in pollution prevention: • Promptly clean and remove any spills or contamination from vehicles or other services. • Perform preventative maintenance on the structural components of the stormwater system. • Properly dispose of refuse. 3.1.1 Local Standards South Yarmouth Good Housekeeping Standards, Projects shall meet the following Performance Standards: (2) Good housekeeping procedures shall be used to reduce sources of sediment, phosphorus, nitrogen and other contaminants in stormwater runoff. These shall be documented in the Operation and Maintenance Plan and must include: (a) Wash vehicles at commercial car washes or on lawns or pervious areas using biodegradable and phosphate free detergent; (b) Removal of sediment, leaf litter and other organic debris from impervious surfaces a minimum of twice a year in the spring (after snowmelt) and fall (after leaf fall); (c) Removal of sediment/debris from catch basin structures a minimum of once a year; (d) Restrictions on the application of fertilizers, including: i. Fertilizer shall not be applied during or immediately prior to heavy rainfall, such as but not limited to thunderstorms, hurricanes, or northeastern storms, or when the soil is saturated due to intense or extended rainfall; ii. Fertilizer shall not be applied between November 12 and the following March 31; iii. Fertilizer shall not be applied, spilled or deposited on impervious surfaces or in a manner that allows it to enter into storm drains; iv. Fertilizer shall not be applied within 100 feet of any surface water or within the Zone I of a public drinking water well; Long Term O&M Plan 3-1 Section 3 Long Term Pollution Prevention Plan Tighe&Bond v. Fertilizer containing phosphorus shall not be applied unless a soil test taken not more than three years before the proposed fertilizer application indicates that additional phosphorus is needed for growth of that turf, or unless establishing new turf or reestablishing or repairing turf after substantial damage or land disturbance; vi. A single application of fertilizer that contains nitrogen shall not exceed 1.0 pound of nitrogen per 1,000 square feet, shall consist of at least 20% slow - release nitrogen (SRN) fertilizer (NOTE: This represents the minimum percentage: use of higher SRN content is generally preferable, especially on sandy root zones, during stress and pre -stress periods, and when there are fewer annual applications of nitrogen made to a lawn) and the annual rate shall not exceed 3.2 pounds of actual nitrogen per thousand square feet. Single applications shall be done at intervals of no less than four weeks until the annual maximum is reached; vii. Grass clippings, leaves, or any other vegetative debris shall not be deposited into or within 50 feet of water bodies, retention and detention areas, drainage ditches or stormwater drains, or onto impervious surfaces, such as, but not limited to, roadways and sidewalks, except during scheduled clean-upprograms; and (e) Provide for routine inspection (at least annually) and maintenance of structural BMPs to remove sediment and debris. 3.2 Potential Sources of Pollution The following sources of pollution are anticipated as part of the long-term use of the project. Pollutant -Generating Activity Pollutants or Pollutant Constituents (that could be discharged if exposed to stormwater) Vehicular Access Petroleum, concrete, vehicle fluids, paints, solvents Solid waste storage Construction debris, trash Landscaping Activites Fertilizers, pesticides, herbcides Equipment use Hydraulic oils, fluids, antifreeze, coolant 3.3 General Spill Prevention and Response In the event of a spill, the following procedures shall be followed by the Maintenance Contact or their authorized representative: • Manufacturer's recommended methods for cleanup will be clearly posted and facility personnel will be made aware of the procedures and the location of the information and clean up supplies. • Materials and equipment necessary for spill cleanup will be kept in the material storage areas at the facility. Equipment and materials will include but not be limited to brooms, dustpans, mops, rags, gloves, goggles, kitty litter, sand, sawdust and plastic or metal trash containers specifically for this purpose. Long Term O&M Plan 3-2 Section 3 Long Term Pollution Prevention Plan Tighe&Bond • All spills will be cleaned up immediately after discovery. • The spill area will be kept well ventilated and personnel will wear appropriate protective clothing to prevent injury from contact with hazardous substances. • Spills of toxic or hazardous material will be reported to the appropriate state or local government agency regardless of size. • The Spill Prevention Plan will be adjusted to include measures to prevent this type of spill from recurring and how to cleanup the spill if it recurs. A description of the spill, its cause and the cleanup measures will be included. • The Maintenance Contact is responsible for day to day operations will be the spill prevention and cleanup coordinator. 3.3.1 Federal and State Spill Notification In accordance with 310 CMR 40.0333, the Maintenance Contact shall notify the Massachusetts Department of Environmental Protection (Southeast Region) - (508) 946- 2700 the Local Emergency Planning Committee (LEPC) (if applicable) and any other authorities or agencies within two hours if an accident or other type of incident results in a release to: • land 0 10 Gallons for more Oils (PCB<500 ppm) 0 1 Gallon or more Oils (PCB >_500 ppm) • waterways o Any quantity of Oils • Or, triggers the exposure to toxic chemical levels as listed in 301 CMR 40.1600, Revised Massachusetts Contingency Plan (MPC) The Maintenance Contact shall notify the National Response Center (NRC) at (800) 424-8802 where a leak, spill, or other release containing a hazardous substance or oil in an amount equal to or in excess of a reportable quantity consistent with Part 2.3.3.4c and established under either 40 CFR Part 110, 40 CFR Part 117, or 40 CFR Part 302, occurs during a 24-hour period. In either event, the Maintenance Contact will work with state and federal agencies to ensure that all appropriate forms and reports are submitted in a timely manner. • Note: Trigger volumes for other chemical spills vary. Contact the MassDEP or a Licensed Site Professional (LSP) for specific guidance on reporting thresholds and requirements for other chemicals. 3.3.2 Local Notification The following local agencies will be called to provide emergency assistance at the facility on the judgment of the Maintenance Contact: Fire Department 911 or (508)-398-2212 Police Department 911 or (508) 775-0445 Hospital: Cape Cod Hospital Department of Public Works: Long Term O&M Plan 3-3 Section 3 Long Term Pollution Prevention Plan Tighe&Bond (508) 771-1800 1 (508) 398-2231 ext.1250 3.4 Storage, Handling, and Disposal of Materials and Wastes The following procedures shall be followed throughout the facility when storing, handling and disposing of various materials. 3.4.1 Pesticides, Herbicides, Insecticides, Fertilizers, and Landscaping Materials • Store new and used materials in a neat, orderly manner in their appropriate containers in a covered area. If storage in a covered area is not possible, the materials shall be covered with polyethylene or polypropylene sheeting to protect them from the elements. • Storage area should include precautions to contain any potential spills. • Immediately contain and clean up any spills with absorbent materials. • Apply at a rate and in amounts consistent with manufacturer's specifications, or document departures from the manufacturer's specifications. • Apply at the appropriate time of year for the site, and preferably timed to coincide as closely as possible to the period of maximum vegetation uptake and growth • Avoid applying before heavy rains that could cause excessive nutrients to be discharged • Never apply to frozen ground • Never apply to stormwater conveyance channels with flowing water • Follow all federal, state, tribal, and local requirements regarding fertilizer application. 3.4.3 Hazardous or Toxic Waste • Store new and used materials in a neat, orderly manner in their appropriate containers in a covered area. If storage in a covered area is not possible, the materials shall be covered with polyethylene or polypropylene sheeting to protect them from the elements. • Storage areas should include precautions to contain any potential spills. • Immediately contain and clean up any spills with absorbent materials. • Have equipment available in fuel storage areas and in vehicles to contain and clean up any spills that occur. • To prevent leaks, empty and clean hazerdous waste containers before disposing of them. • Never remove the original product label from the container because it contains important safety information. Follow the manufacturer's recommended method of disposal, which should be printed on the label. Long Term O&M Plan 3-4 Section 3 Long Term Pollution Prevention Plan Tighe&Bond • Never mix excess products when disposing of them, unless specifically recommended by the manufacturer. 3.4.4 Domestic Waste • Site property manager shall designate a waste collection area on the site that does not receive a substantial amount of runoff from upland areas and does not drain directly to a water body. • Ensure that containers have lids so they can be covered before periods of rain and keep containers in a covered area whenever possible. • Schedule waste collection to prevent the containers from overfilling. • Clean up spills immediately. For hazardous materials, follow cleanup instructions on the package. Use an absorbent material such as sawdust or kitty litter to contain the spill. Long Term O&M Plan 3-5 Tighe&Bond Section 4 Stormwater Management System Under proposed conditions, stormwater runoff from the project area is all collected and treated within the new stormwater system. No runoff from the redevelopment area will enter the existing stormwater system on site. The stormwater runoff generally flows south and is collected in catch basins, trench drains, or directly flows into a series of sediment forebays. The runoff entering catch basins will flow through a series of drain manholes and a Water Quality Treatment Unit. All run off from impervious vehicular areas will reach the required 44% pretreatment before entering the basin for infiltration. The infiltration basin has been sized to retain the volume of 1 inch per impervious. See the attached Figures 1-3 in Appendix A for the location of the various described components of the Stormwater Management System. 4.1 Inspections Inspections will be performed in accordance with the Massachusetts Department of Environmental Protection (MassDEP) Stormwater Handbook. Figure 3, provided in Appendix A, identifies the location of each BMP to be inspected and maintained as described in this Section. All inspections should be logged using the Inspection Forms provided in Section 5. The following stormwater management system features will be evaluated during each inspection: 4.1.1 Vegetated Surfaces Inspection Frequency: Bi-annually in Summer and Winter Special Inspection Event(s): Spring Snow Melt All vegetative surfaces will be observed to identify locations of settlement, erosion and other impacts from the proposed access roads. Areas of settlement and erosion that may result in a discharge of sediment into Waters of the Commonwealth shall be repaired and restored to a vegetated condition. 4.1.2 Driveway and Walkway Sweeping Inspection Frequency: Quarterly Special Inspection Event(s): Spring Snow Melt All pavement surfaces should be inspected annually for deterioration or spalling. Additionally, the pavement surface should be regularly monitored to make sure it drains properly after storms. Cleanings should be conducted on a quarterly basis to prevent clogging. For best management practices, high -efficiency vacuum sweeping machines should be used to clean and maintain the surface. 4.1.3 Deep -Sump, Hooded Catch Basins Inspection Frequency: Quarterly Long Term O&M Plan 4-1 Section 4 Stormwater Management System Tighe&Bond Special Inspection Event(s): Rainfall greater than 0.5 inches Deep sump catch basins should be inspected at least four times per year. The Visual inspection should ascertain that the catch basin is functioning properly (i.e. no blockages or obstructions to the outlet and/or hood) and to measure the amount of solid materials that have accumulated in the sump. This can be done with a calibrated dipstick, tape measure or other measuring instrument so that the depth of deposition in the sump can be tracked. Inspections should be completed visually from the ground level. Deep sump catch basins should be cleaned four times per year or whenever the depth of the sediment is greater than or equal to one half the depth from the bottom of the invert of the lowest pipe in the basin. Cleanings should also be conducted at the end of the foliage and snow -removal seasons. Clamshell buckets can be used to remove sediment. However, vacuum trucks will remove more trapped sediment, are more expedient, and are less likely to damage hoods on outlet pipes. Disposal of sediment removed from catch basins must be disposed of in accordance with local, state and federal requirements. 4.1.4 Proprietary Water Treatment Devices Inspection Frequency: Per manufacturer recommendations Special Inspection Event(s): Rainfall greater than 0.5 inches Structural Water Quality Units (WQU) will be observed in accordance with manufacturer recommendations. Units are to be cleaned as directed by the manufacturer. Manufacturer recommended O&M requirements are provided in Appendix F. 4.1.6 Surface Infiltration Basin Inspection Frequency: Bi-annually Special Inspection Event(s): Rainfall greater than 0.5 inches Surface infiltration basins should be inspected bi-annually for standing water. If standing water is observed for longer than 72 hours, a pump should be placed in the basin and discharged through the outlet pipe. After the system is dewatered, it should be observed by a Professional Engineer. A Professional Engineer should provide an opinion as to why the infiltrations basin is not draining and provide recommendations to restore infiltration capacity to the system. Additionally, infiltration basins shall be observed to identify depths of sediment and occurrence of debris which would impact functionality. The outlet control structure, if applicable, shall be observed for signs of clogging during storm events and erosion. Any trash or debris encountered shall be removed. If the basin is equipped with a Sediment Forebay, inspect the forebay monthly to observe sediment depth, and to identify signs of rilling and gullying an repair as needed. Forebays should be mowed as needed, with grass height no greater than 6 inches. Remove accumulated sediment quarterly, and when sediment depth is between 3 to 6 feet. After sediment removal, reseed by incorporating practices such as hydroseeding with a tackifier or erosion control blanket. 4.1.7 Infiltration Trenches Inspection Frequency: Bi-annually Special Inspection Event(s): Rainfall greater than 0.5 inches Long Term O&M Plan 4-2 Section 4 Stormwater Management System Tighe&Bond Perform preventive maintenance at least twice a year. Inspect and clean pretreatment BMPs every six months and after every major storm event (2 year return frequency). Check inlet and outlet pipes to determine if they are clogged. Remove accumulated sediment, trash, debris, leaves and grass clippings from mowing. Remove tree seedlings, before they become firmly established. Because infiltration trenches are prone to failure due to clogging, it is imperative that they be aggressively maintained on a regular schedule. 4.1.13 Stone End Protection (Outfalls) Inspection Frequency: Bi-annually Special Inspection Event(s): Rainfall greater than 0.5 inches Emergency spillways should be inspected twice a year as well as after every major storm, for slope integrity, soil moisture, vegetated health, soil stability, soil compaction, soil erosion, ponding and sediment accumulation. If the rip rap has been displaced, undermined or damaged, it should be replaced immediately. The channel immediately below the outlet should be checked to see that erosion is not occurring. The downstream channel will be kept clear of obstructions, such as fallen trees, debris, leaves and sediment that could change flow patterns and/or tail water depths in pipes. Repairs must be carried out immediately to avoid additional damage to the outlet protection apron. Long Term O&M Plan 4-3 Tighe&Bond Section 5 Operation and Maintenance Log Form Person conducting Inspection: Reason for Inspection (Routine / Significant Rainfall): Stormwater Management System Components: Vegetated Surface Component inspected during this inspection Any Repair Necessary Other Comments Driveway and Walkway Sweeping Component inspected during this inspection Any Repair Necessary Other Comments Deep -Sump Hooded Catch Basins Component inspected during this inspection Any Repair Necessary Other Comments Proprietary Water Quality Units Component inspected during this inspection Any Repair Necessary Other Comments Infiltration Basins Component inspected during this inspection Any Repair Necessary Other Comments Culvert and Stone End Protection Component inspected during this inspection Any Repair Necessary Other Comments Long Term O&M Plan 5-1 Tighe&Bond Section 6 Snow Management & De -Icing Snow removal will occur along areas where the proposed site improvements occur. Snow storage should not be in or adjacent to wetland areas nor block drainage to surface inlets (e.g. catch basins). Applications of chemical de-icing may be applied along with sand for the roads, main entrances, stop sign areas, and sidewalks. Apply only as needed using minimum quantities. Small quantities of deicers may be mixed with sand or sprayed on hard to maintain areas. Sweep or clean up accumulated sand, sidewalks, steps, and roads as soon as possible after the road surface clears. Long Term O&M Plan 6-1 Tighe&Bond Section 7 Estimated O&M Budget The following estimated O&M Budget includes the inspections and maintenance activities previously described on an annual basis. Maintenance Quantity Frequency Unit Cost Annual Cost Component er ear Vegetated Surfaces 1 4 $100 $100 Street Sweeping 1 4 $250 $250 Catch Basin 4 4 $250 $1,000 Inspection Catch Basin 4 2 $1,000 $4,000 Sediment Removal Surface Infiltration 1 2 $500 $500 Basins System Outfalls 2 2 $250 $500 Proprietary 1 3 $500 $500 Treatment Devices Total Annual Estimated Budget $6,950 \\Tighebond. com\data\Data\Projects\C\C5200 CH-IV\South Yarmouth LNG - 001\Permitting\Stormwater\Appendix F - Stormwater O&M\Long Term Pollution Prevention and Stormwater Management OM Plan.doc Long Term O&M Plan 7-1 APPENDIX G Tighe&Bond Illicit Discharge Compliance Statement Project Location: 127 Whites Path, South Yarmouth, MA 02664 Illicit discharges to the stormwater management system are discharges that are not entirely comprised of stormwater. Illicit discharge does not include discharges from the following activities or facilities: firefighting, water line flushing, landscape irrigation, uncontaminated groundwater, potable water sources, foundation drains, air conditioning condensation, footing drains, individual resident car washing, flows from riparian habitats and wetlands, dechlorinated water from swimming pools, water used for street washing, and water used to clean residential buildings without detergents. To the best of my knowledge, I am not aware of any existing illicit discharges located at the Project Location and will abandon or remove such illicit discharges/connections in the future, if found. Signature: //JI Printed Name & Title: Matthew T. Wozniak, PE, Lead Environmental Engineer J:\C\C5200 CH-IV\South Yarmouth LNG - 001\Permitting\stormwater\Appendix G - Illicit Discharge\Illicit Discharge Statement.doc South Yarmouth LNG Project Stormwater Management Report 100%Recyclable IW