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HomeMy WebLinkAbout5193 897 Route 28 Stormwater Management Report 07.24.25(508)746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 897 Main Street (Route 28), S. Yarmouth MA July 24, 2025 Stormwater Management Report Submitted To: Town of Yarmouth (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Table of Contents Stormwater Management Report •Project Summary •Methodology o Existing Conditions o Proposed Conditions •Compliance with Stormwater Management Standards Figures •USGS Locus Map •FEMA Flood Rate Insurance Map •Wetland and NHESP Inventory Map •2023 Google Earth Aerial Photograph Appendices •Appendix A: Existing Conditions with Watershed Delineation Plan •Appendix B: Proposed Conditions with Watershed Delineation Plan •Appendix C: Stormwater Compliance Computations: o Groundwater Recharge Volume o Infiltration System Drawdown o Water Quality Volume o TSS Removal •Appendix D: Stormwater Management Plans and Documentation o Stormwater Report Checklist o Construction Operation and Maintenance Plan & Pollution Prevention Plan o Long Term Source Control / Pollution Prevention Plan & Operation and Maintenance Plan o StormTech SC-740 Operation and Maintenance Notes o First Defense High Capacity and First Defense Optimum Operation and Maintenance Manual •Appendix E: Site Soil Analysis o NRCS Soils Map & Soil Description (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Stormwater Management Report • Project Summary • Methodology o Existing Conditions o Proposed Conditions • Compliance with Stormwater Management Standards (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Stormwater Management Report Residential Development 897 Main Street (Route 28), South Yarmouth, MA July 24, 2025 Project Summary The project proponent, ACRE+ WCI Real Estate Ventures 1, LLC, wishes to redevelop the subject property containing approximately 1.09± acres of land with frontage on Main Street (Route 28) and Pine Grove Road in South Yarmouth, Massachusetts. The proposed redevelopment consists of a residential development under a M.G.L. Chapter 40B Comprehensive Permit, containing 3 residential buildings with condominium units, totaling 27 total units between the 3 buildings. The general scope of work for this project will include razing the existing commercial development building, along with existing parking, construction of the three residential buildings, parking lots and driveway improvements to the existing curb cut on Pine Grove Road, and the installation of electrical, sewer, water, and stormwater utilities and structures. Methodology Drainage computations were performed using the National Conservation Services (NRCS) TR-20 method and HydroCAD® Drainage Calculation Software. The existing and proposed watershed plans, HydroCAD® Report, and copies of the calculation sheets are included in the appendices of this report. Existing Conditions The subject property, 897 Main Street (Route 28) in South Yarmouth is a 1.09± acre lot located within the “Business 1” and “Business 2” (“B1” and “B2”) Zoning District, with Overlay Districts in the “Hotel/Motel Overlay District 1” and “Village Center 3 Overlay District” as depicted on the Town of Yarmouth Zoning Map. The property is currently developed and has a commercial building for laundromat services, along with associated parking and driveway curb cuts on Main Street and Pine Grove Road. The project site abuts a single-family residential property to the south, and a motel development to the west. There are also residential developments to the east, across Pine Grove Road. There are no known wetland resource areas located on or abutting the project site. The site is not located within or near any known Areas of Critical Concern (ACEC), Estimated Habitat of Rare Wildlife, or Priority Habitat of Rare Species. The site is not located within any surface or well protection zones (Zone A, B, C – Zone I, II, etc.). The site topography is relatively flat, with slopes ranging from 0-3%. Existing soil conditions were investigated by researching the National Resources Conservation Service (NRCS) Web Soil Survey database. Data from Web Soil Survey showed that the site is completely comprised of Carver coarse sand with an associated map unit of 252A. The soil profile for this material essentially includes coarse sand throughout the A, B and C soil layers, with a small section of organic materials at the surface. The soil properties show that the soil is excessively drained and has a Hydrologic Soil Group (HSG) A. The parent material is identified as dry outwash. To view the NRCS Web Soil Survey data see Appendix E. To supplement the (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Yarmouth regarding a previous Site and Sewage Plan completed by Down Cape Engineering, Inc. in December of 1993. The previous Site and Sewage Plan had test pit information indicating that soil parent material was medium sand throughout the profile. Proposed Conditions Under proposed conditions, stormwater runoff within the site will be collected within catch basins, pre-treated with Hydro International First Defense Units, and discharged to proposed subsurface infiltration chamber systems. The stormwater management systems were designed to be in compliance with DEP Stormwater regulations (SMR) to the extent practicable. There will be an increase in runoff rates due to the additional impervious area proposed on the site. The increase is attenuated by the proposed infiltration chamber systems by providing infiltration, storage volume and discharge controls. These measures will both detain and infiltrate runoff, help mitigate increased rates and volumes of runoff for the 2, 10, 25 and 100-year storm events off site. Compliance with Stormwater Management Standards Standard 1 – No Untreated Discharges or Erosion to Wetlands The proposed project will not discharge any untreated impervious runoff or cause erosion to the surrounding wetland resources. Standard 2 – Peak Attenuation Rates Peak rates of runoff calculations were completed using the NRCS (SCS) TR-20 methodology, for a Type-III 24-hr storm, within HydroCAD® software. These calculations help to compare the effects of stormwater runoff between the existing conditions and proposed conditions on-site. Precipitation data was obtained from the National Oceanic and Atmospheric Administration (NOAA) to analyze the 2, 10, 25, and 100-year storm frequencies. Storm Frequency (years) Rainfall Depth (inches) 2 3.35 10 4.88 25 5.83 100 7.30 The increase in runoff is attenuated by the proposed subsurface infiltration chamber systems onsite providing treatment, infiltration and storage volume controls. These measures will mitigate increased rates of runoff for the 2, 10, 25 and 100-year storm events. The stormwater infiltration facilities were designed to accommodate and store peak flows generated by the 100-year storm event. (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 See the following tables, which provide the peak rates and volumes of runoff for the project Design Point: Peak Rates of Runoff Design Point 1 (Abutting properties to south and west) Design Point 2 (Pine Grove Road) Storm Event 2-yr 10-yr 25-yr 100-yr 2-yr 10-yr 25-yr 100-yr Existing (cfs) 0.00 0.03 0.09 0.24 0.00 0.01 0.40 1.14 Proposed (cfs) 0.00 0.00 0.01 0.03 0.00 0.01 0.03 0.10 Peak Volumes of Runoff Design Point 1 (Abutting properties to south and west) Design Point 2 (Pine Grove Road) Storm Event 2-yr 10-yr 25-yr 100-yr 2-yr 10-yr 25-yr 100-yr Existing (ac-ft) 0.001 0.008 0.014 0.028 0.001 0.008 0.014 0.031 Proposed (ac-ft) 0.000 0.001 0.002 0.004 0.000 0.003 0.007 0.015 Note: The proposed conditions for stormwater runoff rates and volumes is improved in comparison to the existing conditions for all storm events noted above. (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Standard 3 – Recharge Requirements To mitigate loss of annual recharge from the proposed project scope of work, the proposed subsurface infiltration chamber systems will meet the following requirements from the Massachusetts Stormwater Handbook: o The recharge volume provided must meet or exceed the recharge volume required. o The drawdown time provided must be less than 72 hours for infiltration systems. The subsurface infiltration chamber systems will be a minimum of two feet above seasonal high groundwater. The hydraulic conductivity was based on sandy soil conditions found on the site via research on the National Resources Conservation Service (NRCS) Web Soil Survey database, existing soil test pit data done by Down Cape Engineering, Inc., and DEP SMR Table 2.3.3 1982 Rawls Rates - values developed from Rawls, Brakensiek and Saxton, 1982 for sandy soils (HSG A) with an exfiltration rate of 8.27 in/hr. The total required groundwater recharge volume for the entire site was calculated to be 1,337 cubic feet. The proposed infiltration facilities will provide 6,797 cubic feet of recharge below the overflow outlet elevation. Refer to Appendix C for recharge volume, drawdown calculations and Appendix E for soil testing results. Standard 4 – Water Quality Requirements A Long-Term Source Control/Pollution Prevention Plan has been incorporated into the Operation and Maintenance Plan (see Appendix D). The water quality volume was calculated using the one-inch rule for the total proposed impervious area of 0.61 acres. The total required water quality treatment volume required was calculated to be 2,228 cubic feet. The proposed water quality treatment volume provided is 6,797 cubic feet through the infiltration systems and pretreatment units. Refer to Appendix C for water quality calculations for the treatment system. In accordance with the guidelines of the Stormwater Management Policy, the Total Suspended Solids (TSS) Removal was calculated to be 80% or greater for every treatment train which will handle the stormwater runoff from the proposed project area. The treatment train consists of a First Defense Unit proprietary structure to a subsurface infiltration chamber system to achieve the minimum required removal rate of 80% total suspended soils. TSS removal calculations are included in Appendix C. Standard 5 – Land Use with Higher Potential Pollutant Loads (LUHPPL) The proposed project is not considered a LUHPPL, not applicable. Standard 6 – Discharges Near or to Critical Areas This site is not located within any critical areas. Water Quality computations were completed by using the 1.0-inch treatment method and 44% TSS removal was provided prior to discharge to the infiltration BMPs. See Appendix C for Water Quality computations and the Long-Term Pollution Prevention Plan. (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Standard 7 – Redevelopment This project is not considered a redevelopment project, not applicable. Standard 8 – Construction Period Controls Sediment and erosion control measures such as silt sock barriers will be placed at the limit of work for this project prior to the commencement of any activity. See the Construction Operation and Maintenance Plan/ Pollution Prevention plan in Appendix D and the construction detail plans for more information. Standard 9 – Operations and Maintenance See the Long-Term Operations and Maintenance Plan in Appendix D for more information. Standard 10 – Prohibition of Illicit Discharges No illicit discharges are anticipated on this project. Measures to prevent illicit discharges are included in the Long-Term Source Control / Pollution Prevention Plan in Appendix D. (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Figures •USGS Topographic Map Locus Map •FEMA Flood Rate Insurance Map •Wetland and NHESP Inventory Map •2023 Google Earth Aerial Map (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Figure 1 - USGS Topographic Locus Map PROJECT LOCUS (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Figure 2 - FEMA Flood Insurance Rate Map PROJECT LOCUS (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Figure 3 - Wetland & NHESP Inventory Map PROJECT LOCUS (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Figure 4 – 2024 Google Earth Aerial Photograph PROJECT LOCUS (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Appendices • Appendix A: Existing Conditions • Appendix B: Proposed Conditions • Appendix C: Stormwater Compliance Calculations o Groundwater Recharge Volume o Infiltration System Drawdown o Water Quality Volume o TSS Removal • Appendix D: Stormwater Management Plans and Documentation o Stormwater Checklist o Construction Operation and Maintenance Plan & Pollution Prevention Plan o Long Term Source Control/Pollution Prevention Plan & Operation and Maintenance Plan o StormTech SC-740 Operation and Maintenance Notes o First Defense High Capacity and First Defense Optimum Operation and Maintenance Manual • Appendix E: Site Soil Analysis o NRCS Soils Map & Soil Description (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Appendix A Existing Conditions (2-, 10-, 25-, and 100-Year Design Storms) • Existing Watershed Plan • Existing HydroCAD® Report TVTVTVTVTV EG G G G GGG GGGGGGG G G G G G GG GGGGGGGGG GGGGGGGGGGGGGGGOHWOHWOHW OHW OHW OHW OHW OHW OHW OHW OHW OHW OHW O H W O H W OHWOHWOHWOHWOHWOHWOHWOHWOH W OH W OHWSW W W W W W W WWWLOT AREA SSSSSSSSSMAIN STREET ( R O UTE 28) PUBLI C ~ 40' WI DE (ST AT E L. O. No. 3111)PINE GROVE ROADPUBLIC ~ 40' WIDEPARCEL ID: 41/ 43/ / / #19 PINE GROVE RD N/F MOORE CLIVE A BOOK: 29943 PAGE: 0218 PARCEL ID: 41/ 47/ / / #891 ROUTE 28 N/F SWAMINARAYAN LLC BOOK: 16963 PAGE: 0234 G W W W WWWG GHEMLOCK PLACE © merrillinc.com DRAFTLOCUS EXISTING WATERSHED SUBCATCHMENT AREAS 1S 1S 1Sa 1Sa 2S 2S 2Sa 2Sa DP1 DP1 DP2 DP2 3Pe EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) 4Pe EXISTING DEPRESSED AREA Routing Diagram for EWP Prepared by Merrill Associates Inc, Printed 6/25/2025 HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Subcat Reach Pond Link Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 2HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=11,153 sf 13.09% Impervious Runoff Depth=0.05"Subcatchment 1S: 1S Flow Length=75' Tc=11.6 min CN=44 Runoff=0.00 cfs 0.001 af Runoff Area=9,235 sf 6.96% Impervious Runoff Depth=0.03"Subcatchment 1Sa: 1Sa Flow Length=120' Tc=9.4 min CN=43 Runoff=0.00 cfs 0.001 af Runoff Area=7,287 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 2S: 2S Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 Runoff=0.00 cfs 0.000 af Runoff Area=19,706 sf 59.79% Impervious Runoff Depth=1.14"Subcatchment 2Sa: 2Sa Flow Length=137' Tc=9.9 min CN=74 Runoff=0.50 cfs 0.043 af Inflow=0.00 cfs 0.001 afReach DP1: DP1 Outflow=0.00 cfs 0.001 af Inflow=0.00 cfs 0.000 afReach DP2: DP2 Outflow=0.00 cfs 0.000 af Peak Elev=10.37' Storage=653 cf Inflow=0.50 cfs 0.043 afPond 3Pe: EX LEACHING PITS (ASSUMED TO Discarded=0.06 cfs 0.043 af Primary=0.00 cfs 0.000 af Outflow=0.06 cfs 0.043 af Peak Elev=12.84' Storage=0 cf Inflow=0.00 cfs 0.001 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.00 cfs 0.001 af Primary=0.00 cfs 0.000 af Outflow=0.00 cfs 0.001 af Total Runoff Area = 1.088 ac Runoff Volume = 0.045 af Average Runoff Depth = 0.49" 70.69% Pervious = 0.769 ac 29.31% Impervious = 0.319 ac Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 3HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.00 cfs @ 15.40 hrs, Volume= 0.001 af, Depth= 0.05" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 1,460 98 Roofs, HSG A 2,956 30 Woods, Good, HSG A 6,737 39 >75% Grass cover, Good, HSG A 11,153 44 Weighted Average 9,693 86.91% Pervious Area 1,460 13.09% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 50 0.0250 0.08 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.6 25 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 11.6 75 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.002 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=11,153 sf Runoff Volume=0.001 af Runoff Depth=0.05" Flow Length=75' Tc=11.6 min CN=44 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 4HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.00 cfs @ 15.70 hrs, Volume= 0.001 af, Depth= 0.03" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 643 98 Roofs, HSG A 8,592 39 >75% Grass cover, Good, HSG A 9,235 43 Weighted Average 8,592 93.04% Pervious Area 643 6.96% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.4 70 0.0150 0.86 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 9.4 120 Total Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=9,235 sf Runoff Volume=0.001 af Runoff Depth=0.03" Flow Length=120' Tc=9.4 min CN=43 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 5HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 5,510 30 Woods, Good, HSG A 1,777 39 >75% Grass cover, Good, HSG A 7,287 32 Weighted Average 7,287 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.1 50 0.0200 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.7 30 0.0200 0.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.8 80 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=7,287 sf Runoff Volume=0.000 af Runoff Depth=0.00" Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 6HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 0.50 cfs @ 12.15 hrs, Volume= 0.043 af, Depth= 1.14" Routed to Pond 3Pe : EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 9,733 98 Paved parking, HSG A 2,050 98 Roofs, HSG A 7,923 39 >75% Grass cover, Good, HSG A 19,706 74 Weighted Average 7,923 40.21% Pervious Area 11,783 59.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.8 75 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 12 0.0300 3.52 Shallow Concentrated Flow, Paved Kv= 20.3 fps 9.9 137 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=19,706 sf Runoff Volume=0.043 af Runoff Depth=1.14" Flow Length=137' Tc=9.9 min CN=74 0.50 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 7HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.468 ac, 10.31% Impervious, Inflow Depth = 0.03" for 2-yr event Inflow = 0.00 cfs @ 15.40 hrs, Volume= 0.001 af Outflow = 0.00 cfs @ 15.40 hrs, Volume= 0.001 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.002 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0 0 Inflow Area=0.468 ac0.00 cfs0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 8HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.620 ac, 43.65% Impervious, Inflow Depth = 0.00" for 2-yr event Inflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.620 ac 0.00 cfs0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 9HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Inflow Area = 0.452 ac, 59.79% Impervious, Inflow Depth = 1.14" for 2-yr event Inflow = 0.50 cfs @ 12.15 hrs, Volume= 0.043 af Outflow = 0.06 cfs @ 11.90 hrs, Volume= 0.043 af, Atten= 88%, Lag= 0.0 min Discarded = 0.06 cfs @ 11.90 hrs, Volume= 0.043 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP2 : DP2 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 10.37' @ 13.31 hrs Surf.Area= 316 sf Storage= 653 cf Plug-Flow detention time= 97.2 min calculated for 0.043 af (100% of inflow) Center-of-Mass det. time= 97.1 min ( 959.9 - 862.8 ) Volume Invert Avail.Storage Storage Description #1 7.00'661 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 2,212 cf Overall - 560 cf Embedded = 1,652 cf x 40.0% Voids #2 7.00'560 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 Inside #1 #3 12.00'837 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,058 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 7.00 79 0 0 14.00 79 553 553 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 7.00 28 0 0 12.00 28 140 140 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 12.00 3 0 0 13.60 3 5 5 13.80 1,160 116 121 14.00 6,000 716 837 Device Routing Invert Outlet Devices #1 Discarded 7.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 13.80'20.0' long x 12.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.57 2.62 2.70 2.67 2.66 2.67 2.66 2.64 Discarded OutFlow Max=0.06 cfs @ 11.90 hrs HW=7.08' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.06 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=7.00' TW=0.00' (Dynamic Tailwater) 2=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 10HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.452 ac Peak Elev=10.37' Storage=653 cf 0.50 cfs 0.06 cfs0.06 cfs 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 11HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.212 ac, 6.96% Impervious, Inflow Depth = 0.03" for 2-yr event Inflow = 0.00 cfs @ 15.70 hrs, Volume= 0.001 af Outflow = 0.00 cfs @ 16.92 hrs, Volume= 0.001 af, Atten= 3%, Lag= 73.3 min Discarded = 0.00 cfs @ 16.92 hrs, Volume= 0.001 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 12.84' @ 16.92 hrs Surf.Area= 16 sf Storage= 0 cf Plug-Flow detention time= 6.1 min calculated for 0.001 af (100% of inflow) Center-of-Mass det. time= 6.1 min ( 1,141.3 - 1,135.2 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.00 cfs @ 16.92 hrs HW=12.84' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.00 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 12HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 Inflow Area=0.212 ac Peak Elev=12.84' Storage=0 cf 0.00 cfs 0.00 cfs0.00 cfs 0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 13HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=11,153 sf 13.09% Impervious Runoff Depth=0.36"Subcatchment 1S: 1S Flow Length=75' Tc=11.6 min CN=44 Runoff=0.03 cfs 0.008 af Runoff Area=9,235 sf 6.96% Impervious Runoff Depth=0.32"Subcatchment 1Sa: 1Sa Flow Length=120' Tc=9.4 min CN=43 Runoff=0.02 cfs 0.006 af Runoff Area=7,287 sf 0.00% Impervious Runoff Depth=0.02"Subcatchment 2S: 2S Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 Runoff=0.00 cfs 0.000 af Runoff Area=19,706 sf 59.79% Impervious Runoff Depth=2.27"Subcatchment 2Sa: 2Sa Flow Length=137' Tc=9.9 min CN=74 Runoff=1.05 cfs 0.086 af Inflow=0.03 cfs 0.008 afReach DP1: DP1 Outflow=0.03 cfs 0.008 af Inflow=0.01 cfs 0.000 afReach DP2: DP2 Outflow=0.01 cfs 0.000 af Peak Elev=13.80' Storage=1,321 cf Inflow=1.05 cfs 0.086 afPond 3Pe: EX LEACHING PITS (ASSUMED Discarded=0.30 cfs 0.086 af Primary=0.01 cfs 0.000 af Outflow=0.30 cfs 0.086 af Peak Elev=13.10' Storage=19 cf Inflow=0.02 cfs 0.006 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.01 cfs 0.006 af Primary=0.00 cfs 0.000 af Outflow=0.01 cfs 0.006 af Total Runoff Area = 1.088 ac Runoff Volume = 0.099 af Average Runoff Depth = 1.09" 70.69% Pervious = 0.769 ac 29.31% Impervious = 0.319 ac Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 14HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.03 cfs @ 12.43 hrs, Volume= 0.008 af, Depth= 0.36" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 1,460 98 Roofs, HSG A 2,956 30 Woods, Good, HSG A 6,737 39 >75% Grass cover, Good, HSG A 11,153 44 Weighted Average 9,693 86.91% Pervious Area 1,460 13.09% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 50 0.0250 0.08 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.6 25 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 11.6 75 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.038 0.036 0.034 0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=11,153 sf Runoff Volume=0.008 af Runoff Depth=0.36" Flow Length=75' Tc=11.6 min CN=44 0.03 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 15HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.02 cfs @ 12.42 hrs, Volume= 0.006 af, Depth= 0.32" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 643 98 Roofs, HSG A 8,592 39 >75% Grass cover, Good, HSG A 9,235 43 Weighted Average 8,592 93.04% Pervious Area 643 6.96% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.4 70 0.0150 0.86 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 9.4 120 Total Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.026 0.025 0.024 0.023 0.022 0.021 0.02 0.019 0.018 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.0040.003 0.002 0.001 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=9,235 sf Runoff Volume=0.006 af Runoff Depth=0.32" Flow Length=120' Tc=9.4 min CN=43 0.02 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 16HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.00 cfs @ 21.86 hrs, Volume= 0.000 af, Depth= 0.02" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 5,510 30 Woods, Good, HSG A 1,777 39 >75% Grass cover, Good, HSG A 7,287 32 Weighted Average 7,287 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.1 50 0.0200 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.7 30 0.0200 0.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.8 80 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=7,287 sf Runoff Volume=0.000 af Runoff Depth=0.02" Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 17HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 1.05 cfs @ 12.14 hrs, Volume= 0.086 af, Depth= 2.27" Routed to Pond 3Pe : EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 9,733 98 Paved parking, HSG A 2,050 98 Roofs, HSG A 7,923 39 >75% Grass cover, Good, HSG A 19,706 74 Weighted Average 7,923 40.21% Pervious Area 11,783 59.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.8 75 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 12 0.0300 3.52 Shallow Concentrated Flow, Paved Kv= 20.3 fps 9.9 137 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=19,706 sf Runoff Volume=0.086 af Runoff Depth=2.27" Flow Length=137' Tc=9.9 min CN=74 1.05 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 18HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.468 ac, 10.31% Impervious, Inflow Depth = 0.20" for 10-yr event Inflow = 0.03 cfs @ 12.43 hrs, Volume= 0.008 af Outflow = 0.03 cfs @ 12.43 hrs, Volume= 0.008 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.038 0.036 0.034 0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Inflow Area=0.468 ac0.03 cfs0.03 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 19HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.620 ac, 43.65% Impervious, Inflow Depth = 0.01" for 10-yr event Inflow = 0.01 cfs @ 12.56 hrs, Volume= 0.000 af Outflow = 0.01 cfs @ 12.56 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.009 0.009 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Inflow Area=0.620 ac0.01 cfs0.01 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 20HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Inflow Area = 0.452 ac, 59.79% Impervious, Inflow Depth = 2.27" for 10-yr event Inflow = 1.05 cfs @ 12.14 hrs, Volume= 0.086 af Outflow = 0.30 cfs @ 12.56 hrs, Volume= 0.086 af, Atten= 71%, Lag= 25.0 min Discarded = 0.30 cfs @ 12.56 hrs, Volume= 0.086 af Primary = 0.01 cfs @ 12.56 hrs, Volume= 0.000 af Routed to Reach DP2 : DP2 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.80' @ 12.56 hrs Surf.Area= 1,549 sf Storage= 1,321 cf Plug-Flow detention time= 166.5 min calculated for 0.085 af (100% of inflow) Center-of-Mass det. time= 166.4 min ( 1,008.7 - 842.2 ) Volume Invert Avail.Storage Storage Description #1 7.00'661 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 2,212 cf Overall - 560 cf Embedded = 1,652 cf x 40.0% Voids #2 7.00'560 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 Inside #1 #3 12.00'837 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,058 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 7.00 79 0 0 14.00 79 553 553 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 7.00 28 0 0 12.00 28 140 140 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 12.00 3 0 0 13.60 3 5 5 13.80 1,160 116 121 14.00 6,000 716 837 Device Routing Invert Outlet Devices #1 Discarded 7.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 13.80'20.0' long x 12.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.57 2.62 2.70 2.67 2.66 2.67 2.66 2.64 Discarded OutFlow Max=0.30 cfs @ 12.56 hrs HW=13.80' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.30 cfs) Primary OutFlow Max=0.01 cfs @ 12.56 hrs HW=13.80' TW=0.00' (Dynamic Tailwater) 2=Broad-Crested Rectangular Weir (Weir Controls 0.01 cfs @ 0.14 fps) Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 21HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.452 ac Peak Elev=13.80' Storage=1,321 cf 1.05 cfs 0.30 cfs0.30 cfs 0.01 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 22HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.212 ac, 6.96% Impervious, Inflow Depth = 0.32" for 10-yr event Inflow = 0.02 cfs @ 12.42 hrs, Volume= 0.006 af Outflow = 0.01 cfs @ 12.74 hrs, Volume= 0.006 af, Atten= 43%, Lag= 19.1 min Discarded = 0.01 cfs @ 12.74 hrs, Volume= 0.006 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.10' @ 12.74 hrs Surf.Area= 242 sf Storage= 19 cf Plug-Flow detention time= 23.4 min calculated for 0.006 af (100% of inflow) Center-of-Mass det. time= 23.4 min ( 995.6 - 972.2 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.01 cfs @ 12.74 hrs HW=13.10' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 23HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Inflow Area=0.212 ac Peak Elev=13.10' Storage=19 cf 0.02 cfs 0.01 cfs0.01 cfs 0.00 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 24HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=11,153 sf 13.09% Impervious Runoff Depth=0.67"Subcatchment 1S: 1S Flow Length=75' Tc=11.6 min CN=44 Runoff=0.09 cfs 0.014 af Runoff Area=9,235 sf 6.96% Impervious Runoff Depth=0.61"Subcatchment 1Sa: 1Sa Flow Length=120' Tc=9.4 min CN=43 Runoff=0.06 cfs 0.011 af Runoff Area=7,287 sf 0.00% Impervious Runoff Depth=0.11"Subcatchment 2S: 2S Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 Runoff=0.00 cfs 0.002 af Runoff Area=19,706 sf 59.79% Impervious Runoff Depth=3.04"Subcatchment 2Sa: 2Sa Flow Length=137' Tc=9.9 min CN=74 Runoff=1.41 cfs 0.115 af Inflow=0.09 cfs 0.014 afReach DP1: DP1 Outflow=0.09 cfs 0.014 af Inflow=0.40 cfs 0.009 afReach DP2: DP2 Outflow=0.40 cfs 0.009 af Peak Elev=13.84' Storage=1,386 cf Inflow=1.41 cfs 0.115 afPond 3Pe: EX LEACHING PITS (ASSUMED Discarded=0.46 cfs 0.107 af Primary=0.40 cfs 0.007 af Outflow=0.86 cfs 0.115 af Peak Elev=13.23' Storage=68 cf Inflow=0.06 cfs 0.011 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.03 cfs 0.011 af Primary=0.00 cfs 0.000 af Outflow=0.03 cfs 0.011 af Total Runoff Area = 1.088 ac Runoff Volume = 0.141 af Average Runoff Depth = 1.56" 70.69% Pervious = 0.769 ac 29.31% Impervious = 0.319 ac Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 25HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.09 cfs @ 12.28 hrs, Volume= 0.014 af, Depth= 0.67" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 1,460 98 Roofs, HSG A 2,956 30 Woods, Good, HSG A 6,737 39 >75% Grass cover, Good, HSG A 11,153 44 Weighted Average 9,693 86.91% Pervious Area 1,460 13.09% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 50 0.0250 0.08 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.6 25 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 11.6 75 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=11,153 sf Runoff Volume=0.014 af Runoff Depth=0.67" Flow Length=75' Tc=11.6 min CN=44 0.09 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 26HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.06 cfs @ 12.30 hrs, Volume= 0.011 af, Depth= 0.61" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 643 98 Roofs, HSG A 8,592 39 >75% Grass cover, Good, HSG A 9,235 43 Weighted Average 8,592 93.04% Pervious Area 643 6.96% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.4 70 0.0150 0.86 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 9.4 120 Total Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=9,235 sf Runoff Volume=0.011 af Runoff Depth=0.61" Flow Length=120' Tc=9.4 min CN=43 0.06 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 27HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.00 cfs @ 15.12 hrs, Volume= 0.002 af, Depth= 0.11" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 5,510 30 Woods, Good, HSG A 1,777 39 >75% Grass cover, Good, HSG A 7,287 32 Weighted Average 7,287 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.1 50 0.0200 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.7 30 0.0200 0.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.8 80 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.003 0.002 0.002 0.002 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=7,287 sf Runoff Volume=0.002 af Runoff Depth=0.11" Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 0.00 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 28HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 1.41 cfs @ 12.14 hrs, Volume= 0.115 af, Depth= 3.04" Routed to Pond 3Pe : EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 9,733 98 Paved parking, HSG A 2,050 98 Roofs, HSG A 7,923 39 >75% Grass cover, Good, HSG A 19,706 74 Weighted Average 7,923 40.21% Pervious Area 11,783 59.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.8 75 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 12 0.0300 3.52 Shallow Concentrated Flow, Paved Kv= 20.3 fps 9.9 137 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=19,706 sf Runoff Volume=0.115 af Runoff Depth=3.04" Flow Length=137' Tc=9.9 min CN=74 1.41 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 29HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.468 ac, 10.31% Impervious, Inflow Depth = 0.37" for 25-yr event Inflow = 0.09 cfs @ 12.28 hrs, Volume= 0.014 af Outflow = 0.09 cfs @ 12.28 hrs, Volume= 0.014 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.468 ac0.09 cfs0.09 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 30HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.620 ac, 43.65% Impervious, Inflow Depth = 0.17" for 25-yr event Inflow = 0.40 cfs @ 12.30 hrs, Volume= 0.009 af Outflow = 0.40 cfs @ 12.30 hrs, Volume= 0.009 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.620 ac0.40 cfs0.40 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 31HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Inflow Area = 0.452 ac, 59.79% Impervious, Inflow Depth = 3.04" for 25-yr event Inflow = 1.41 cfs @ 12.14 hrs, Volume= 0.115 af Outflow = 0.86 cfs @ 12.30 hrs, Volume= 0.115 af, Atten= 39%, Lag= 9.8 min Discarded = 0.46 cfs @ 12.30 hrs, Volume= 0.107 af Primary = 0.40 cfs @ 12.30 hrs, Volume= 0.007 af Routed to Reach DP2 : DP2 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.84' @ 12.30 hrs Surf.Area= 2,427 sf Storage= 1,386 cf Plug-Flow detention time= 142.3 min calculated for 0.115 af (100% of inflow) Center-of-Mass det. time= 142.3 min ( 976.0 - 833.7 ) Volume Invert Avail.Storage Storage Description #1 7.00'661 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 2,212 cf Overall - 560 cf Embedded = 1,652 cf x 40.0% Voids #2 7.00'560 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 Inside #1 #3 12.00'837 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,058 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 7.00 79 0 0 14.00 79 553 553 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 7.00 28 0 0 12.00 28 140 140 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 12.00 3 0 0 13.60 3 5 5 13.80 1,160 116 121 14.00 6,000 716 837 Device Routing Invert Outlet Devices #1 Discarded 7.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 13.80'20.0' long x 12.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.57 2.62 2.70 2.67 2.66 2.67 2.66 2.64 Discarded OutFlow Max=0.46 cfs @ 12.30 hrs HW=13.84' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.46 cfs) Primary OutFlow Max=0.40 cfs @ 12.30 hrs HW=13.84' TW=0.00' (Dynamic Tailwater) 2=Broad-Crested Rectangular Weir (Weir Controls 0.40 cfs @ 0.51 fps) Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 32HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.452 ac Peak Elev=13.84' Storage=1,386 cf 1.41 cfs 0.86 cfs 0.46 cfs 0.40 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 33HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.212 ac, 6.96% Impervious, Inflow Depth = 0.61" for 25-yr event Inflow = 0.06 cfs @ 12.30 hrs, Volume= 0.011 af Outflow = 0.03 cfs @ 12.71 hrs, Volume= 0.011 af, Atten= 56%, Lag= 24.7 min Discarded = 0.03 cfs @ 12.71 hrs, Volume= 0.011 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.23' @ 12.71 hrs Surf.Area= 508 sf Storage= 68 cf Plug-Flow detention time= 28.0 min calculated for 0.011 af (100% of inflow) Center-of-Mass det. time= 28.1 min ( 964.8 - 936.7 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.03 cfs @ 12.71 hrs HW=13.23' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 34HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.212 ac Peak Elev=13.23' Storage=68 cf 0.06 cfs 0.03 cfs0.03 cfs 0.00 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 35HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=11,153 sf 13.09% Impervious Runoff Depth=1.29"Subcatchment 1S: 1S Flow Length=75' Tc=11.6 min CN=44 Runoff=0.24 cfs 0.028 af Runoff Area=9,235 sf 6.96% Impervious Runoff Depth=1.21"Subcatchment 1Sa: 1Sa Flow Length=120' Tc=9.4 min CN=43 Runoff=0.19 cfs 0.021 af Runoff Area=7,287 sf 0.00% Impervious Runoff Depth=0.38"Subcatchment 2S: 2S Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 Runoff=0.02 cfs 0.005 af Runoff Area=19,706 sf 59.79% Impervious Runoff Depth=4.30"Subcatchment 2Sa: 2Sa Flow Length=137' Tc=9.9 min CN=74 Runoff=2.00 cfs 0.162 af Inflow=0.24 cfs 0.028 afReach DP1: DP1 Outflow=0.24 cfs 0.028 af Inflow=1.14 cfs 0.031 afReach DP2: DP2 Outflow=1.14 cfs 0.031 af Peak Elev=13.88' Storage=1,493 cf Inflow=2.00 cfs 0.162 afPond 3Pe: EX LEACHING PITS (ASSUMED Discarded=0.65 cfs 0.137 af Primary=1.14 cfs 0.026 af Outflow=1.78 cfs 0.162 af Peak Elev=13.43' Storage=213 cf Inflow=0.19 cfs 0.021 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.05 cfs 0.021 af Primary=0.00 cfs 0.000 af Outflow=0.05 cfs 0.021 af Total Runoff Area = 1.088 ac Runoff Volume = 0.217 af Average Runoff Depth = 2.39" 70.69% Pervious = 0.769 ac 29.31% Impervious = 0.319 ac Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 36HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.24 cfs @ 12.20 hrs, Volume= 0.028 af, Depth= 1.29" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 1,460 98 Roofs, HSG A 2,956 30 Woods, Good, HSG A 6,737 39 >75% Grass cover, Good, HSG A 11,153 44 Weighted Average 9,693 86.91% Pervious Area 1,460 13.09% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.0 50 0.0250 0.08 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.6 25 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 11.6 75 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=11,153 sf Runoff Volume=0.028 af Runoff Depth=1.29" Flow Length=75' Tc=11.6 min CN=44 0.24 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 37HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.19 cfs @ 12.17 hrs, Volume= 0.021 af, Depth= 1.21" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 643 98 Roofs, HSG A 8,592 39 >75% Grass cover, Good, HSG A 9,235 43 Weighted Average 8,592 93.04% Pervious Area 643 6.96% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.4 70 0.0150 0.86 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 9.4 120 Total Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=9,235 sf Runoff Volume=0.021 af Runoff Depth=1.21" Flow Length=120' Tc=9.4 min CN=43 0.19 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 38HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.02 cfs @ 12.52 hrs, Volume= 0.005 af, Depth= 0.38" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 5,510 30 Woods, Good, HSG A 1,777 39 >75% Grass cover, Good, HSG A 7,287 32 Weighted Average 7,287 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 12.1 50 0.0200 0.07 Sheet Flow, Woods: Light underbrush n= 0.400 P2= 3.35" 0.7 30 0.0200 0.71 Shallow Concentrated Flow, Woodland Kv= 5.0 fps 12.8 80 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.018 0.017 0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=7,287 sf Runoff Volume=0.005 af Runoff Depth=0.38" Flow Length=80' Slope=0.0200 '/' Tc=12.8 min CN=32 0.02 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 39HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 2.00 cfs @ 12.14 hrs, Volume= 0.162 af, Depth= 4.30" Routed to Pond 3Pe : EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 9,733 98 Paved parking, HSG A 2,050 98 Roofs, HSG A 7,923 39 >75% Grass cover, Good, HSG A 19,706 74 Weighted Average 7,923 40.21% Pervious Area 11,783 59.79% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 1.8 75 0.0100 0.70 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 0.1 12 0.0300 3.52 Shallow Concentrated Flow, Paved Kv= 20.3 fps 9.9 137 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=19,706 sf Runoff Volume=0.162 af Runoff Depth=4.30" Flow Length=137' Tc=9.9 min CN=74 2.00 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 40HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.468 ac, 10.31% Impervious, Inflow Depth = 0.71" for 100-yr event Inflow = 0.24 cfs @ 12.20 hrs, Volume= 0.028 af Outflow = 0.24 cfs @ 12.20 hrs, Volume= 0.028 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Inflow Area=0.468 ac0.24 cfs0.24 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 41HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.620 ac, 43.65% Impervious, Inflow Depth = 0.60" for 100-yr event Inflow = 1.14 cfs @ 12.19 hrs, Volume= 0.031 af Outflow = 1.14 cfs @ 12.19 hrs, Volume= 0.031 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.620 ac1.14 cfs1.14 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 42HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) Inflow Area = 0.452 ac, 59.79% Impervious, Inflow Depth = 4.30" for 100-yr event Inflow = 2.00 cfs @ 12.14 hrs, Volume= 0.162 af Outflow = 1.78 cfs @ 12.19 hrs, Volume= 0.162 af, Atten= 11%, Lag= 3.3 min Discarded = 0.65 cfs @ 12.19 hrs, Volume= 0.137 af Primary = 1.14 cfs @ 12.19 hrs, Volume= 0.026 af Routed to Reach DP2 : DP2 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.88' @ 12.19 hrs Surf.Area= 3,382 sf Storage= 1,493 cf Plug-Flow detention time= 118.2 min calculated for 0.162 af (100% of inflow) Center-of-Mass det. time= 118.2 min ( 942.0 - 823.8 ) Volume Invert Avail.Storage Storage Description #1 7.00'661 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 2,212 cf Overall - 560 cf Embedded = 1,652 cf x 40.0% Voids #2 7.00'560 cf Custom Stage Data (Prismatic) Listed below (Recalc) x 4 Inside #1 #3 12.00'837 cf Custom Stage Data (Prismatic) Listed below (Recalc) 2,058 cf Total Available Storage Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 7.00 79 0 0 14.00 79 553 553 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 7.00 28 0 0 12.00 28 140 140 Elevation Surf.Area Inc.Store Cum.Store (feet)(sq-ft) (cubic-feet) (cubic-feet) 12.00 3 0 0 13.60 3 5 5 13.80 1,160 116 121 14.00 6,000 716 837 Device Routing Invert Outlet Devices #1 Discarded 7.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' #2 Primary 13.80'20.0' long x 12.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.57 2.62 2.70 2.67 2.66 2.67 2.66 2.64 Discarded OutFlow Max=0.65 cfs @ 12.19 hrs HW=13.88' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.65 cfs) Primary OutFlow Max=1.13 cfs @ 12.19 hrs HW=13.88' TW=0.00' (Dynamic Tailwater) 2=Broad-Crested Rectangular Weir (Weir Controls 1.13 cfs @ 0.72 fps) Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 43HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 3Pe: EX LEACHING PITS (ASSUMED TO BE CONSTRUCTED) InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.452 ac Peak Elev=13.88' Storage=1,493 cf 2.00 cfs 1.78 cfs 0.65 cfs 1.14 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 44HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.212 ac, 6.96% Impervious, Inflow Depth = 1.21" for 100-yr event Inflow = 0.19 cfs @ 12.17 hrs, Volume= 0.021 af Outflow = 0.05 cfs @ 12.77 hrs, Volume= 0.021 af, Atten= 73%, Lag= 36.0 min Discarded = 0.05 cfs @ 12.77 hrs, Volume= 0.021 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.43' @ 12.77 hrs Surf.Area= 923 sf Storage= 213 cf Plug-Flow detention time= 45.4 min calculated for 0.021 af (100% of inflow) Center-of-Mass det. time= 45.3 min ( 951.8 - 906.5 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.05 cfs @ 12.77 hrs HW=13.43' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.05 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"EWP Printed 6/25/2025Prepared by Merrill Associates Inc Page 45HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.21 0.2 0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Inflow Area=0.212 ac Peak Elev=13.43' Storage=213 cf 0.19 cfs 0.05 cfs0.05 cfs 0.00 cfs (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Appendix B Proposed Conditions (2-, 10-, 25-, and 100-Year Design Storms) •Proposed Watershed Plan •Proposed HydroCAD® Report TVTVTVTVTV EG G G G GGG GGGGGGG G G G G G GG GGGGGGGGG GGGGGGGGGGGGGGGOHWOHWOHW OHW OHW OHW OHW OHW OHW OHW OHW OHW OHW O H W O H W OHWOHWOHWOHWOHWOHWOHWOHWOH W OH W OHWSW W W W W W W WWWSSSSSSSSSMAIN STREET ( R O UTE 28) PUBLI C ~ 40' WI DE (ST AT E L. O. No. 3111)PINE GROVE ROADPUBLIC ~ 40' WIDEPARCEL ID: 41/ 43/ / / #19 PINE GROVE RD N/F MOORE CLIVE A BOOK: 29943 PAGE: 0218 PARCEL ID: 41/ 47/ / / #891 ROUTE 28 N/F SWAMINARAYAN LLC BOOK: 16963 PAGE: 0234 G W W W WWWG GHEMLOCK PLACE © merrillinc.com DRAFTLOCUS PROPOSED WATERSHED SUBCATCHMENT AREAS 1S 1S 1Sa 1Sa 2S 2S 2Sa 2Sa 3S 3S 3Sa 3Sa 4S 4S DP1 DP1 DP2 DP2 1P SUBSURFACE SYSTEM #1 2P SUBSURFACE SYSTEM #2 4Pe EXISTING DEPRESSED AREA Routing Diagram for PWP Prepared by Merrill Associates Inc, Printed 6/26/2025 HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Subcat Reach Pond Link PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 2HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Rainfall Events Listing Event# Event Name Storm Type Curve Mode Duration (hours) B/B Depth (inches) AMC P2 (inches) 1 2-yr Type III 24-hr Default 24.00 1 3.35 2 3.35 2 10-yr Type III 24-hr Default 24.00 1 4.88 2 3.35 3 25-yr Type III 24-hr Default 24.00 1 5.83 2 3.35 4 100-yr Type III 24-hr Default 24.00 1 7.30 2 3.35 PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 3HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (acres) CN Description (subcatchment-numbers) 0.492 39 >75% Grass cover, Good, HSG A (1S, 1Sa, 2S, 2Sa, 3S, 3Sa, 4S) 0.406 98 Paved parking, HSG A (1S, 3S, 3Sa, 4S) 0.189 98 Roofs, HSG A (3Sa, 4S) 1.088 71 TOTAL AREA PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 4HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Soil Listing (all nodes) Area (acres) Soil Group Subcatchment Numbers 1.088 HSG A 1S, 1Sa, 2S, 2Sa, 3S, 3Sa, 4S 0.000 HSG B 0.000 HSG C 0.000 HSG D 0.000 Other 1.088 TOTAL AREA PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 5HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Ground Covers (all nodes) HSG-A (acres) HSG-B (acres) HSG-C (acres) HSG-D (acres) Other (acres) Total (acres) Ground Cover Subcatchment Numbers 0.492 0.000 0.000 0.000 0.000 0.492 >75% Grass cover, Good 1S, 1Sa, 2S, 2Sa, 3S, 3Sa, 4S 0.406 0.000 0.000 0.000 0.000 0.406 Paved parking 1S, 3S, 3Sa, 4S 0.189 0.000 0.000 0.000 0.000 0.189 Roofs 3Sa, 4S 1.088 0.000 0.000 0.000 0.000 1.088 TOTAL AREA Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 6HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=6,220 sf 1.61% Impervious Runoff Depth=0.01"Subcatchment 1S: 1S Flow Length=90' Tc=7.5 min CN=40 Runoff=0.00 cfs 0.000 af Runoff Area=2,335 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 1Sa: 1Sa Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 Runoff=0.00 cfs 0.000 af Runoff Area=4,310 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 2S: 2S Flow Length=75' Tc=8.3 min CN=39 Runoff=0.00 cfs 0.000 af Runoff Area=4,472 sf 0.00% Impervious Runoff Depth=0.00"Subcatchment 2Sa: 2Sa Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 Runoff=0.00 cfs 0.000 af Runoff Area=3,990 sf 72.43% Impervious Runoff Depth=1.66"Subcatchment 3S: 3S Tc=6.0 min CN=82 Runoff=0.18 cfs 0.013 af Runoff Area=15,822 sf 87.25% Impervious Runoff Depth=2.31"Subcatchment 3Sa: 3Sa Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 Runoff=0.95 cfs 0.070 af Runoff Area=10,230 sf 89.35% Impervious Runoff Depth=2.49"Subcatchment 4S: 4S Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 Runoff=0.67 cfs 0.049 af Inflow=0.00 cfs 0.000 afReach DP1: DP1 Outflow=0.00 cfs 0.000 af Inflow=0.00 cfs 0.000 afReach DP2: DP2 Outflow=0.00 cfs 0.000 af Peak Elev=9.57' Storage=523 cf Inflow=1.13 cfs 0.083 afPond 1P: SUBSURFACE SYSTEM #1 Outflow=0.39 cfs 0.083 af Peak Elev=9.58' Storage=309 cf Inflow=0.67 cfs 0.049 afPond 2P: SUBSURFACE SYSTEM #2 Outflow=0.22 cfs 0.049 af Peak Elev=12.80' Storage=0 cf Inflow=0.00 cfs 0.000 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.00 cfs 0.000 af Primary=0.00 cfs 0.000 af Outflow=0.00 cfs 0.000 af Total Runoff Area = 1.088 ac Runoff Volume = 0.131 af Average Runoff Depth = 1.45" 45.26% Pervious = 0.492 ac 54.74% Impervious = 0.595 ac Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 7HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.00 cfs @ 22.60 hrs, Volume= 0.000 af, Depth= 0.01" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 6,120 39 >75% Grass cover, Good, HSG A 100 98 Paved parking, HSG A 6,220 40 Weighted Average 6,120 98.39% Pervious Area 100 1.61% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.8 50 0.0300 0.12 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.7 40 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 7.5 90 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 0 0 0 0 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=6,220 sf Runoff Volume=0.000 af Runoff Depth=0.01" Flow Length=90' Tc=7.5 min CN=40 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 8HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.00 cfs @ 23.96 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 2,335 39 >75% Grass cover, Good, HSG A 2,335 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.8 20 0.0200 0.09 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 3.8 20 Total, Increased to minimum Tc = 6.0 min Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=2,335 sf Runoff Volume=0.000 af Runoff Depth=0.00" Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 9HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.00 cfs @ 23.98 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 4,310 39 >75% Grass cover, Good, HSG A 4,310 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 25 0.0500 1.57 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.3 75 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=4,310 sf Runoff Volume=0.000 af Runoff Depth=0.00" Flow Length=75' Tc=8.3 min CN=39 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 10HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 0.00 cfs @ 23.98 hrs, Volume= 0.000 af, Depth= 0.00" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 4,472 39 >75% Grass cover, Good, HSG A 4,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.5 30 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.5 80 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=4,472 sf Runoff Volume=0.000 af Runoff Depth=0.00" Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 11HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: 3S Runoff = 0.18 cfs @ 12.09 hrs, Volume= 0.013 af, Depth= 1.66" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 2,890 98 Paved parking, HSG A 1,100 39 >75% Grass cover, Good, HSG A 3,990 82 Weighted Average 1,100 27.57% Pervious Area 2,890 72.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: 3S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.19 0.18 0.17 0.16 0.15 0.14 0.13 0.12 0.11 0.1 0.09 0.08 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=3,990 sf Runoff Volume=0.013 af Runoff Depth=1.66" Tc=6.0 min CN=82 0.18 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 12HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3Sa: 3Sa Runoff = 0.95 cfs @ 12.09 hrs, Volume= 0.070 af, Depth= 2.31" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 8,310 98 Paved parking, HSG A 5,494 98 Roofs, HSG A 2,018 39 >75% Grass cover, Good, HSG A 15,822 90 Weighted Average 2,018 12.75% Pervious Area 13,804 87.25% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 35 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 15 0.0200 0.96 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.2 30 0.0200 2.87 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.5 80 Total Subcatchment 3Sa: 3Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=15,822 sf Runoff Volume=0.070 af Runoff Depth=2.31" Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 0.95 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 13HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: 4S Runoff = 0.67 cfs @ 12.09 hrs, Volume= 0.049 af, Depth= 2.49" Routed to Pond 2P : SUBSURFACE SYSTEM #2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35" Area (sf) CN Description 6,395 98 Paved parking, HSG A 2,745 98 Roofs, HSG A 1,090 39 >75% Grass cover, Good, HSG A 10,230 92 Weighted Average 1,090 10.65% Pervious Area 9,140 89.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 65 0.0200 1.29 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.8 65 Total, Increased to minimum Tc = 6.0 min Subcatchment 4S: 4S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 2-yr Rainfall=3.35" P2=3.35" Runoff Area=10,230 sf Runoff Volume=0.049 af Runoff Depth=2.49" Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 0.67 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 14HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.196 ac, 1.17% Impervious, Inflow Depth = 0.00" for 2-yr event Inflow = 0.00 cfs @ 23.96 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 23.96 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Inflow Area=0.196 ac 0.00 cfs0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 15HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.202 ac, 0.00% Impervious, Inflow Depth = 0.00" for 2-yr event Inflow = 0.00 cfs @ 23.98 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 23.98 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 0 0 0 0 0 Inflow Area=0.202 ac 0.00 cfs0.00 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 16HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 1P: SUBSURFACE SYSTEM #1 Inflow Area = 0.455 ac, 84.26% Impervious, Inflow Depth = 2.18" for 2-yr event Inflow = 1.13 cfs @ 12.09 hrs, Volume= 0.083 af Outflow = 0.39 cfs @ 11.98 hrs, Volume= 0.083 af, Atten= 66%, Lag= 0.0 min Discarded = 0.39 cfs @ 11.98 hrs, Volume= 0.083 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 9.57' @ 12.39 hrs Surf.Area= 2,031 sf Storage= 523 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 6.1 min ( 816.1 - 810.0 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,851 cf 30.00'W x 67.70'L x 3.50'H Field A 7,108 cf Overall - 2,481 cf Embedded = 4,627 cf x 40.0% Voids #2A 9.50' 2,481 cf ADS_StormTech SC-740 +Cap x 54 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 54 Chambers in 6 Rows 4,332 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.39 cfs @ 11.98 hrs HW=9.04' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.39 cfs) Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 17HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 9 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 65.70' Row Length +12.0" End Stone x 2 = 67.70' Base Length 6 Rows x 51.0" Wide + 6.0" Spacing x 5 + 12.0" Side Stone x 2 = 30.00' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 54 Chambers x 45.9 cf = 2,480.8 cf Chamber Storage 7,108.2 cf Field - 2,480.8 cf Chambers = 4,627.4 cf Stone x 40.0% Voids = 1,851.0 cf Stone Storage Chamber Storage + Stone Storage = 4,331.7 cf = 0.099 af Overall Storage Efficiency = 60.9% Overall System Size = 67.70' x 30.00' x 3.50' 54 Chambers 263.3 cy Field 171.4 cy Stone Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 18HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.455 ac Peak Elev=9.57' Storage=523 cf 1.13 cfs 0.39 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 19HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 2P: SUBSURFACE SYSTEM #2 Inflow Area = 0.235 ac, 89.35% Impervious, Inflow Depth = 2.49" for 2-yr event Inflow = 0.67 cfs @ 12.09 hrs, Volume= 0.049 af Outflow = 0.22 cfs @ 11.96 hrs, Volume= 0.049 af, Atten= 66%, Lag= 0.0 min Discarded = 0.22 cfs @ 11.96 hrs, Volume= 0.049 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 9.58' @ 12.38 hrs Surf.Area= 1,170 sf Storage= 309 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 6.1 min ( 802.3 - 796.1 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,087 cf 25.25'W x 46.34'L x 3.50'H Field A 4,095 cf Overall - 1,378 cf Embedded = 2,717 cf x 40.0% Voids #2A 9.50' 1,378 cf ADS_StormTech SC-740 +Cap x 30 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 30 Chambers in 5 Rows 2,465 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.22 cfs @ 11.96 hrs HW=9.04' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.22 cfs) Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 20HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 6 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 44.34' Row Length +12.0" End Stone x 2 = 46.34' Base Length 5 Rows x 51.0" Wide + 6.0" Spacing x 4 + 12.0" Side Stone x 2 = 25.25' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 30 Chambers x 45.9 cf = 1,378.2 cf Chamber Storage 4,095.0 cf Field - 1,378.2 cf Chambers = 2,716.8 cf Stone x 40.0% Voids = 1,086.7 cf Stone Storage Chamber Storage + Stone Storage = 2,464.9 cf = 0.057 af Overall Storage Efficiency = 60.2% Overall System Size = 46.34' x 25.25' x 3.50' 30 Chambers 151.7 cy Field 100.6 cy Stone Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 21HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.7 0.65 0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Inflow Area=0.235 ac Peak Elev=9.58' Storage=309 cf 0.67 cfs 0.22 cfs Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 22HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.143 ac, 1.61% Impervious, Inflow Depth = 0.01" for 2-yr event Inflow = 0.00 cfs @ 22.60 hrs, Volume= 0.000 af Outflow = 0.00 cfs @ 22.60 hrs, Volume= 0.000 af, Atten= 0%, Lag= 0.0 min Discarded = 0.00 cfs @ 22.60 hrs, Volume= 0.000 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 12.80' @ 0.00 hrs Surf.Area= 10 sf Storage= 0 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 0.0 min ( 1,256.7 - 1,256.7 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.00 cfs @ 22.60 hrs HW=12.80' (Free Discharge) 2=Exfiltration (Passes 0.00 cfs of 0.00 cfs potential flow) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 2-yr Rainfall=3.35", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 23HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0 0 0 0 0 0 0 0 0 0 Inflow Area=0.143 ac Peak Elev=12.80' Storage=0 cf 0.00 cfs0.00 cfs0.00 cfs 0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 24HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=6,220 sf 1.61% Impervious Runoff Depth=0.21"Subcatchment 1S: 1S Flow Length=90' Tc=7.5 min CN=40 Runoff=0.01 cfs 0.002 af Runoff Area=2,335 sf 0.00% Impervious Runoff Depth=0.18"Subcatchment 1Sa: 1Sa Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 Runoff=0.00 cfs 0.001 af Runoff Area=4,310 sf 0.00% Impervious Runoff Depth=0.18"Subcatchment 2S: 2S Flow Length=75' Tc=8.3 min CN=39 Runoff=0.00 cfs 0.001 af Runoff Area=4,472 sf 0.00% Impervious Runoff Depth=0.18"Subcatchment 2Sa: 2Sa Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 Runoff=0.00 cfs 0.002 af Runoff Area=3,990 sf 72.43% Impervious Runoff Depth=2.97"Subcatchment 3S: 3S Tc=6.0 min CN=82 Runoff=0.32 cfs 0.023 af Runoff Area=15,822 sf 87.25% Impervious Runoff Depth=3.76"Subcatchment 3Sa: 3Sa Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 Runoff=1.52 cfs 0.114 af Runoff Area=10,230 sf 89.35% Impervious Runoff Depth=3.97"Subcatchment 4S: 4S Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 Runoff=1.04 cfs 0.078 af Inflow=0.00 cfs 0.001 afReach DP1: DP1 Outflow=0.00 cfs 0.001 af Inflow=0.01 cfs 0.003 afReach DP2: DP2 Outflow=0.01 cfs 0.003 af Peak Elev=10.11' Storage=1,410 cf Inflow=1.83 cfs 0.137 afPond 1P: SUBSURFACE SYSTEM #1 Outflow=0.39 cfs 0.137 af Peak Elev=10.07' Storage=769 cf Inflow=1.04 cfs 0.078 afPond 2P: SUBSURFACE SYSTEM #2 Outflow=0.22 cfs 0.078 af Peak Elev=13.02' Storage=6 cf Inflow=0.01 cfs 0.002 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.00 cfs 0.002 af Primary=0.00 cfs 0.000 af Outflow=0.00 cfs 0.002 af Total Runoff Area = 1.088 ac Runoff Volume = 0.220 af Average Runoff Depth = 2.43" 45.26% Pervious = 0.492 ac 54.74% Impervious = 0.595 ac Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 25HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.01 cfs @ 12.48 hrs, Volume= 0.002 af, Depth= 0.21" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 6,120 39 >75% Grass cover, Good, HSG A 100 98 Paved parking, HSG A 6,220 40 Weighted Average 6,120 98.39% Pervious Area 100 1.61% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.8 50 0.0300 0.12 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.7 40 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 7.5 90 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.007 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=6,220 sf Runoff Volume=0.002 af Runoff Depth=0.21" Flow Length=90' Tc=7.5 min CN=40 0.01 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 26HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.00 cfs @ 12.50 hrs, Volume= 0.001 af, Depth= 0.18" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 2,335 39 >75% Grass cover, Good, HSG A 2,335 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.8 20 0.0200 0.09 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 3.8 20 Total, Increased to minimum Tc = 6.0 min Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=2,335 sf Runoff Volume=0.001 af Runoff Depth=0.18" Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 27HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.00 cfs @ 13.65 hrs, Volume= 0.001 af, Depth= 0.18" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 4,310 39 >75% Grass cover, Good, HSG A 4,310 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 25 0.0500 1.57 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.3 75 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.003 0.002 0.002 0.002 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=4,310 sf Runoff Volume=0.001 af Runoff Depth=0.18" Flow Length=75' Tc=8.3 min CN=39 0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 28HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 0.00 cfs @ 13.65 hrs, Volume= 0.002 af, Depth= 0.18" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 4,472 39 >75% Grass cover, Good, HSG A 4,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.5 30 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.5 80 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.003 0.003 0.002 0.002 0.002 0.002 0.002 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=4,472 sf Runoff Volume=0.002 af Runoff Depth=0.18" Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 29HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: 3S Runoff = 0.32 cfs @ 12.09 hrs, Volume= 0.023 af, Depth= 2.97" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 2,890 98 Paved parking, HSG A 1,100 39 >75% Grass cover, Good, HSG A 3,990 82 Weighted Average 1,100 27.57% Pervious Area 2,890 72.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: 3S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=3,990 sf Runoff Volume=0.023 af Runoff Depth=2.97" Tc=6.0 min CN=82 0.32 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 30HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3Sa: 3Sa Runoff = 1.52 cfs @ 12.09 hrs, Volume= 0.114 af, Depth= 3.76" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 8,310 98 Paved parking, HSG A 5,494 98 Roofs, HSG A 2,018 39 >75% Grass cover, Good, HSG A 15,822 90 Weighted Average 2,018 12.75% Pervious Area 13,804 87.25% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 35 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 15 0.0200 0.96 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.2 30 0.0200 2.87 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.5 80 Total Subcatchment 3Sa: 3Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=15,822 sf Runoff Volume=0.114 af Runoff Depth=3.76" Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 1.52 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 31HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: 4S Runoff = 1.04 cfs @ 12.08 hrs, Volume= 0.078 af, Depth= 3.97" Routed to Pond 2P : SUBSURFACE SYSTEM #2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35" Area (sf) CN Description 6,395 98 Paved parking, HSG A 2,745 98 Roofs, HSG A 1,090 39 >75% Grass cover, Good, HSG A 10,230 92 Weighted Average 1,090 10.65% Pervious Area 9,140 89.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 65 0.0200 1.29 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.8 65 Total, Increased to minimum Tc = 6.0 min Subcatchment 4S: 4S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 10-yr Rainfall=4.88" P2=3.35" Runoff Area=10,230 sf Runoff Volume=0.078 af Runoff Depth=3.97" Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 1.04 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 32HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.196 ac, 1.17% Impervious, Inflow Depth = 0.05" for 10-yr event Inflow = 0.00 cfs @ 12.50 hrs, Volume= 0.001 af Outflow = 0.00 cfs @ 12.50 hrs, Volume= 0.001 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.002 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.001 0.000 0.000 0.000 0.000 0 0 Inflow Area=0.196 ac0.00 cfs0.00 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 33HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.202 ac, 0.00% Impervious, Inflow Depth = 0.18" for 10-yr event Inflow = 0.01 cfs @ 13.65 hrs, Volume= 0.003 af Outflow = 0.01 cfs @ 13.65 hrs, Volume= 0.003 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Inflow Area=0.202 ac0.01 cfs0.01 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 34HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 1P: SUBSURFACE SYSTEM #1 Inflow Area = 0.455 ac, 84.26% Impervious, Inflow Depth = 3.60" for 10-yr event Inflow = 1.83 cfs @ 12.09 hrs, Volume= 0.137 af Outflow = 0.39 cfs @ 11.82 hrs, Volume= 0.137 af, Atten= 79%, Lag= 0.0 min Discarded = 0.39 cfs @ 11.82 hrs, Volume= 0.137 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 10.11' @ 12.52 hrs Surf.Area= 2,031 sf Storage= 1,410 cf Plug-Flow detention time= 19.3 min calculated for 0.136 af (100% of inflow) Center-of-Mass det. time= 19.3 min ( 815.5 - 796.2 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,851 cf 30.00'W x 67.70'L x 3.50'H Field A 7,108 cf Overall - 2,481 cf Embedded = 4,627 cf x 40.0% Voids #2A 9.50' 2,481 cf ADS_StormTech SC-740 +Cap x 54 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 54 Chambers in 6 Rows 4,332 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.39 cfs @ 11.82 hrs HW=9.04' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.39 cfs) Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 35HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 9 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 65.70' Row Length +12.0" End Stone x 2 = 67.70' Base Length 6 Rows x 51.0" Wide + 6.0" Spacing x 5 + 12.0" Side Stone x 2 = 30.00' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 54 Chambers x 45.9 cf = 2,480.8 cf Chamber Storage 7,108.2 cf Field - 2,480.8 cf Chambers = 4,627.4 cf Stone x 40.0% Voids = 1,851.0 cf Stone Storage Chamber Storage + Stone Storage = 4,331.7 cf = 0.099 af Overall Storage Efficiency = 60.9% Overall System Size = 67.70' x 30.00' x 3.50' 54 Chambers 263.3 cy Field 171.4 cy Stone Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 36HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.455 ac Peak Elev=10.11' Storage=1,410 cf 1.83 cfs 0.39 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 37HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 2P: SUBSURFACE SYSTEM #2 Inflow Area = 0.235 ac, 89.35% Impervious, Inflow Depth = 3.97" for 10-yr event Inflow = 1.04 cfs @ 12.08 hrs, Volume= 0.078 af Outflow = 0.22 cfs @ 11.80 hrs, Volume= 0.078 af, Atten= 78%, Lag= 0.0 min Discarded = 0.22 cfs @ 11.80 hrs, Volume= 0.078 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 10.07' @ 12.50 hrs Surf.Area= 1,170 sf Storage= 769 cf Plug-Flow detention time= (not calculated: outflow precedes inflow) Center-of-Mass det. time= 17.5 min ( 801.0 - 783.5 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,087 cf 25.25'W x 46.34'L x 3.50'H Field A 4,095 cf Overall - 1,378 cf Embedded = 2,717 cf x 40.0% Voids #2A 9.50' 1,378 cf ADS_StormTech SC-740 +Cap x 30 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 30 Chambers in 5 Rows 2,465 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.22 cfs @ 11.80 hrs HW=9.04' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.22 cfs) Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 38HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 6 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 44.34' Row Length +12.0" End Stone x 2 = 46.34' Base Length 5 Rows x 51.0" Wide + 6.0" Spacing x 4 + 12.0" Side Stone x 2 = 25.25' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 30 Chambers x 45.9 cf = 1,378.2 cf Chamber Storage 4,095.0 cf Field - 1,378.2 cf Chambers = 2,716.8 cf Stone x 40.0% Voids = 1,086.7 cf Stone Storage Chamber Storage + Stone Storage = 2,464.9 cf = 0.057 af Overall Storage Efficiency = 60.2% Overall System Size = 46.34' x 25.25' x 3.50' 30 Chambers 151.7 cy Field 100.6 cy Stone Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 39HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.235 ac Peak Elev=10.07' Storage=769 cf 1.04 cfs 0.22 cfs Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 40HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.143 ac, 1.61% Impervious, Inflow Depth = 0.21" for 10-yr event Inflow = 0.01 cfs @ 12.48 hrs, Volume= 0.002 af Outflow = 0.00 cfs @ 13.07 hrs, Volume= 0.002 af, Atten= 30%, Lag= 35.3 min Discarded = 0.00 cfs @ 13.07 hrs, Volume= 0.002 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.02' @ 13.07 hrs Surf.Area= 78 sf Storage= 6 cf Plug-Flow detention time= 27.7 min calculated for 0.002 af (100% of inflow) Center-of-Mass det. time= 27.7 min ( 1,033.4 - 1,005.7 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.00 cfs @ 13.07 hrs HW=13.02' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.00 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 10-yr Rainfall=4.88", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 41HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.007 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Inflow Area=0.143 ac Peak Elev=13.02' Storage=6 cf 0.01 cfs 0.00 cfs0.00 cfs 0.00 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 42HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=6,220 sf 1.61% Impervious Runoff Depth=0.45"Subcatchment 1S: 1S Flow Length=90' Tc=7.5 min CN=40 Runoff=0.03 cfs 0.005 af Runoff Area=2,335 sf 0.00% Impervious Runoff Depth=0.40"Subcatchment 1Sa: 1Sa Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 Runoff=0.01 cfs 0.002 af Runoff Area=4,310 sf 0.00% Impervious Runoff Depth=0.40"Subcatchment 2S: 2S Flow Length=75' Tc=8.3 min CN=39 Runoff=0.01 cfs 0.003 af Runoff Area=4,472 sf 0.00% Impervious Runoff Depth=0.40"Subcatchment 2Sa: 2Sa Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 Runoff=0.01 cfs 0.003 af Runoff Area=3,990 sf 72.43% Impervious Runoff Depth=3.83"Subcatchment 3S: 3S Tc=6.0 min CN=82 Runoff=0.41 cfs 0.029 af Runoff Area=15,822 sf 87.25% Impervious Runoff Depth=4.68"Subcatchment 3Sa: 3Sa Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 Runoff=1.87 cfs 0.142 af Runoff Area=10,230 sf 89.35% Impervious Runoff Depth=4.90"Subcatchment 4S: 4S Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 Runoff=1.27 cfs 0.096 af Inflow=0.01 cfs 0.002 afReach DP1: DP1 Outflow=0.01 cfs 0.002 af Inflow=0.03 cfs 0.007 afReach DP2: DP2 Outflow=0.03 cfs 0.007 af Peak Elev=10.50' Storage=2,029 cf Inflow=2.27 cfs 0.171 afPond 1P: SUBSURFACE SYSTEM #1 Outflow=0.39 cfs 0.171 af Peak Elev=10.43' Storage=1,085 cf Inflow=1.27 cfs 0.096 afPond 2P: SUBSURFACE SYSTEM #2 Outflow=0.22 cfs 0.096 af Peak Elev=13.11' Storage=21 cf Inflow=0.03 cfs 0.005 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.01 cfs 0.005 af Primary=0.00 cfs 0.000 af Outflow=0.01 cfs 0.005 af Total Runoff Area = 1.088 ac Runoff Volume = 0.281 af Average Runoff Depth = 3.10" 45.26% Pervious = 0.492 ac 54.74% Impervious = 0.595 ac Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 43HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.03 cfs @ 12.36 hrs, Volume= 0.005 af, Depth= 0.45" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 6,120 39 >75% Grass cover, Good, HSG A 100 98 Paved parking, HSG A 6,220 40 Weighted Average 6,120 98.39% Pervious Area 100 1.61% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.8 50 0.0300 0.12 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.7 40 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 7.5 90 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=6,220 sf Runoff Volume=0.005 af Runoff Depth=0.45" Flow Length=90' Tc=7.5 min CN=40 0.03 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 44HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.01 cfs @ 12.36 hrs, Volume= 0.002 af, Depth= 0.40" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 2,335 39 >75% Grass cover, Good, HSG A 2,335 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.8 20 0.0200 0.09 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 3.8 20 Total, Increased to minimum Tc = 6.0 min Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.009 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=2,335 sf Runoff Volume=0.002 af Runoff Depth=0.40" Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 0.01 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 45HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.01 cfs @ 12.40 hrs, Volume= 0.003 af, Depth= 0.40" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 4,310 39 >75% Grass cover, Good, HSG A 4,310 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 25 0.0500 1.57 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.3 75 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=4,310 sf Runoff Volume=0.003 af Runoff Depth=0.40" Flow Length=75' Tc=8.3 min CN=39 0.01 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 46HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 0.01 cfs @ 12.40 hrs, Volume= 0.003 af, Depth= 0.40" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 4,472 39 >75% Grass cover, Good, HSG A 4,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.5 30 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.5 80 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.016 0.015 0.014 0.013 0.012 0.011 0.01 0.009 0.008 0.007 0.006 0.005 0.004 0.003 0.002 0.001 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=4,472 sf Runoff Volume=0.003 af Runoff Depth=0.40" Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 0.01 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 47HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: 3S Runoff = 0.41 cfs @ 12.09 hrs, Volume= 0.029 af, Depth= 3.83" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 2,890 98 Paved parking, HSG A 1,100 39 >75% Grass cover, Good, HSG A 3,990 82 Weighted Average 1,100 27.57% Pervious Area 2,890 72.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: 3S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.44 0.42 0.4 0.38 0.36 0.34 0.32 0.3 0.28 0.26 0.24 0.22 0.2 0.18 0.16 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=3,990 sf Runoff Volume=0.029 af Runoff Depth=3.83" Tc=6.0 min CN=82 0.41 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 48HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3Sa: 3Sa Runoff = 1.87 cfs @ 12.09 hrs, Volume= 0.142 af, Depth= 4.68" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 8,310 98 Paved parking, HSG A 5,494 98 Roofs, HSG A 2,018 39 >75% Grass cover, Good, HSG A 15,822 90 Weighted Average 2,018 12.75% Pervious Area 13,804 87.25% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 35 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 15 0.0200 0.96 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.2 30 0.0200 2.87 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.5 80 Total Subcatchment 3Sa: 3Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=15,822 sf Runoff Volume=0.142 af Runoff Depth=4.68" Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 1.87 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 49HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: 4S Runoff = 1.27 cfs @ 12.08 hrs, Volume= 0.096 af, Depth= 4.90" Routed to Pond 2P : SUBSURFACE SYSTEM #2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35" Area (sf) CN Description 6,395 98 Paved parking, HSG A 2,745 98 Roofs, HSG A 1,090 39 >75% Grass cover, Good, HSG A 10,230 92 Weighted Average 1,090 10.65% Pervious Area 9,140 89.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 65 0.0200 1.29 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.8 65 Total, Increased to minimum Tc = 6.0 min Subcatchment 4S: 4S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 25-yr Rainfall=5.83" P2=3.35" Runoff Area=10,230 sf Runoff Volume=0.096 af Runoff Depth=4.90" Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 1.27 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 50HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.196 ac, 1.17% Impervious, Inflow Depth = 0.11" for 25-yr event Inflow = 0.01 cfs @ 12.36 hrs, Volume= 0.002 af Outflow = 0.01 cfs @ 12.36 hrs, Volume= 0.002 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.009 0.008 0.007 0.007 0.006 0.006 0.005 0.005 0.004 0.004 0.003 0.003 0.002 0.002 0.001 0.001 0.000 0 Inflow Area=0.196 ac0.01 cfs0.01 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 51HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.202 ac, 0.00% Impervious, Inflow Depth = 0.40" for 25-yr event Inflow = 0.03 cfs @ 12.40 hrs, Volume= 0.007 af Outflow = 0.03 cfs @ 12.40 hrs, Volume= 0.007 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Inflow Area=0.202 ac0.03 cfs0.03 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 52HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 1P: SUBSURFACE SYSTEM #1 Inflow Area = 0.455 ac, 84.26% Impervious, Inflow Depth = 4.51" for 25-yr event Inflow = 2.27 cfs @ 12.09 hrs, Volume= 0.171 af Outflow = 0.39 cfs @ 11.76 hrs, Volume= 0.171 af, Atten= 83%, Lag= 0.0 min Discarded = 0.39 cfs @ 11.76 hrs, Volume= 0.171 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 10.50' @ 12.56 hrs Surf.Area= 2,031 sf Storage= 2,029 cf Plug-Flow detention time= 30.2 min calculated for 0.171 af (100% of inflow) Center-of-Mass det. time= 30.2 min ( 820.4 - 790.2 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,851 cf 30.00'W x 67.70'L x 3.50'H Field A 7,108 cf Overall - 2,481 cf Embedded = 4,627 cf x 40.0% Voids #2A 9.50' 2,481 cf ADS_StormTech SC-740 +Cap x 54 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 54 Chambers in 6 Rows 4,332 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.39 cfs @ 11.76 hrs HW=9.04' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.39 cfs) Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 53HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 9 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 65.70' Row Length +12.0" End Stone x 2 = 67.70' Base Length 6 Rows x 51.0" Wide + 6.0" Spacing x 5 + 12.0" Side Stone x 2 = 30.00' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 54 Chambers x 45.9 cf = 2,480.8 cf Chamber Storage 7,108.2 cf Field - 2,480.8 cf Chambers = 4,627.4 cf Stone x 40.0% Voids = 1,851.0 cf Stone Storage Chamber Storage + Stone Storage = 4,331.7 cf = 0.099 af Overall Storage Efficiency = 60.9% Overall System Size = 67.70' x 30.00' x 3.50' 54 Chambers 263.3 cy Field 171.4 cy Stone Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 54HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)2 1 0 Inflow Area=0.455 ac Peak Elev=10.50' Storage=2,029 cf 2.27 cfs 0.39 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 55HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 2P: SUBSURFACE SYSTEM #2 Inflow Area = 0.235 ac, 89.35% Impervious, Inflow Depth = 4.90" for 25-yr event Inflow = 1.27 cfs @ 12.08 hrs, Volume= 0.096 af Outflow = 0.22 cfs @ 11.76 hrs, Volume= 0.096 af, Atten= 82%, Lag= 0.0 min Discarded = 0.22 cfs @ 11.76 hrs, Volume= 0.096 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 10.43' @ 12.54 hrs Surf.Area= 1,170 sf Storage= 1,085 cf Plug-Flow detention time= 26.6 min calculated for 0.096 af (100% of inflow) Center-of-Mass det. time= 26.6 min ( 804.6 - 778.0 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,087 cf 25.25'W x 46.34'L x 3.50'H Field A 4,095 cf Overall - 1,378 cf Embedded = 2,717 cf x 40.0% Voids #2A 9.50' 1,378 cf ADS_StormTech SC-740 +Cap x 30 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 30 Chambers in 5 Rows 2,465 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.22 cfs @ 11.76 hrs HW=9.05' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.22 cfs) Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 56HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 6 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 44.34' Row Length +12.0" End Stone x 2 = 46.34' Base Length 5 Rows x 51.0" Wide + 6.0" Spacing x 4 + 12.0" Side Stone x 2 = 25.25' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 30 Chambers x 45.9 cf = 1,378.2 cf Chamber Storage 4,095.0 cf Field - 1,378.2 cf Chambers = 2,716.8 cf Stone x 40.0% Voids = 1,086.7 cf Stone Storage Chamber Storage + Stone Storage = 2,464.9 cf = 0.057 af Overall Storage Efficiency = 60.2% Overall System Size = 46.34' x 25.25' x 3.50' 30 Chambers 151.7 cy Field 100.6 cy Stone Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 57HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.235 ac Peak Elev=10.43' Storage=1,085 cf 1.27 cfs 0.22 cfs Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 58HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.143 ac, 1.61% Impervious, Inflow Depth = 0.45" for 25-yr event Inflow = 0.03 cfs @ 12.36 hrs, Volume= 0.005 af Outflow = 0.01 cfs @ 12.62 hrs, Volume= 0.005 af, Atten= 44%, Lag= 15.7 min Discarded = 0.01 cfs @ 12.62 hrs, Volume= 0.005 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.11' @ 12.62 hrs Surf.Area= 260 sf Storage= 21 cf Plug-Flow detention time= 24.2 min calculated for 0.005 af (100% of inflow) Center-of-Mass det. time= 24.3 min ( 982.4 - 958.1 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.01 cfs @ 12.62 hrs HW=13.11' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.01 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 25-yr Rainfall=5.83", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 59HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Inflow Area=0.143 ac Peak Elev=13.11' Storage=21 cf 0.03 cfs 0.01 cfs0.01 cfs 0.00 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 60HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Time span=0.00-36.00 hrs, dt=0.02 hrs, 1801 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=6,220 sf 1.61% Impervious Runoff Depth=0.96"Subcatchment 1S: 1S Flow Length=90' Tc=7.5 min CN=40 Runoff=0.09 cfs 0.011 af Runoff Area=2,335 sf 0.00% Impervious Runoff Depth=0.88"Subcatchment 1Sa: 1Sa Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 Runoff=0.03 cfs 0.004 af Runoff Area=4,310 sf 0.00% Impervious Runoff Depth=0.88"Subcatchment 2S: 2S Flow Length=75' Tc=8.3 min CN=39 Runoff=0.05 cfs 0.007 af Runoff Area=4,472 sf 0.00% Impervious Runoff Depth=0.88"Subcatchment 2Sa: 2Sa Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 Runoff=0.05 cfs 0.008 af Runoff Area=3,990 sf 72.43% Impervious Runoff Depth=5.20"Subcatchment 3S: 3S Tc=6.0 min CN=82 Runoff=0.55 cfs 0.040 af Runoff Area=15,822 sf 87.25% Impervious Runoff Depth=6.12"Subcatchment 3Sa: 3Sa Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 Runoff=2.40 cfs 0.185 af Runoff Area=10,230 sf 89.35% Impervious Runoff Depth=6.35"Subcatchment 4S: 4S Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 Runoff=1.62 cfs 0.124 af Inflow=0.03 cfs 0.004 afReach DP1: DP1 Outflow=0.03 cfs 0.004 af Inflow=0.10 cfs 0.015 afReach DP2: DP2 Outflow=0.10 cfs 0.015 af Peak Elev=11.19' Storage=3,033 cf Inflow=2.95 cfs 0.225 afPond 1P: SUBSURFACE SYSTEM #1 Outflow=0.39 cfs 0.225 af Peak Elev=11.03' Storage=1,593 cf Inflow=1.62 cfs 0.124 afPond 2P: SUBSURFACE SYSTEM #2 Outflow=0.22 cfs 0.124 af Peak Elev=13.26' Storage=86 cf Inflow=0.09 cfs 0.011 afPond 4Pe: EXISTING DEPRESSED AREA Discarded=0.03 cfs 0.011 af Primary=0.00 cfs 0.000 af Outflow=0.03 cfs 0.011 af Total Runoff Area = 1.088 ac Runoff Volume = 0.379 af Average Runoff Depth = 4.18" 45.26% Pervious = 0.492 ac 54.74% Impervious = 0.595 ac Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 61HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: 1S Runoff = 0.09 cfs @ 12.15 hrs, Volume= 0.011 af, Depth= 0.96" Routed to Pond 4Pe : EXISTING DEPRESSED AREA Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 6,120 39 >75% Grass cover, Good, HSG A 100 98 Paved parking, HSG A 6,220 40 Weighted Average 6,120 98.39% Pervious Area 100 1.61% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.8 50 0.0300 0.12 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.7 40 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 7.5 90 Total Subcatchment 1S: 1S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=6,220 sf Runoff Volume=0.011 af Runoff Depth=0.96" Flow Length=90' Tc=7.5 min CN=40 0.09 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 62HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 1Sa: 1Sa Runoff = 0.03 cfs @ 12.13 hrs, Volume= 0.004 af, Depth= 0.88" Routed to Reach DP1 : DP1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 2,335 39 >75% Grass cover, Good, HSG A 2,335 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 3.8 20 0.0200 0.09 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 3.8 20 Total, Increased to minimum Tc = 6.0 min Subcatchment 1Sa: 1Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=2,335 sf Runoff Volume=0.004 af Runoff Depth=0.88" Flow Length=20' Slope=0.0200 '/' Tc=6.0 min CN=39 0.03 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 63HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2S: 2S Runoff = 0.05 cfs @ 12.18 hrs, Volume= 0.007 af, Depth= 0.88" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 4,310 39 >75% Grass cover, Good, HSG A 4,310 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 25 0.0500 1.57 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.3 75 Total Subcatchment 2S: 2S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=4,310 sf Runoff Volume=0.007 af Runoff Depth=0.88" Flow Length=75' Tc=8.3 min CN=39 0.05 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 64HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 2Sa: 2Sa Runoff = 0.05 cfs @ 12.18 hrs, Volume= 0.008 af, Depth= 0.88" Routed to Reach DP2 : DP2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 4,472 39 >75% Grass cover, Good, HSG A 4,472 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 8.0 50 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.5 30 0.0200 0.99 Shallow Concentrated Flow, Short Grass Pasture Kv= 7.0 fps 8.5 80 Total Subcatchment 2Sa: 2Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=4,472 sf Runoff Volume=0.008 af Runoff Depth=0.88" Flow Length=80' Slope=0.0200 '/' Tc=8.5 min CN=39 0.05 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 65HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3S: 3S Runoff = 0.55 cfs @ 12.09 hrs, Volume= 0.040 af, Depth= 5.20" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 2,890 98 Paved parking, HSG A 1,100 39 >75% Grass cover, Good, HSG A 3,990 82 Weighted Average 1,100 27.57% Pervious Area 2,890 72.43% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: 3S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.6 0.55 0.5 0.45 0.4 0.35 0.3 0.25 0.2 0.15 0.1 0.05 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=3,990 sf Runoff Volume=0.040 af Runoff Depth=5.20" Tc=6.0 min CN=82 0.55 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 66HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 3Sa: 3Sa Runoff = 2.40 cfs @ 12.09 hrs, Volume= 0.185 af, Depth= 6.12" Routed to Pond 1P : SUBSURFACE SYSTEM #1 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 8,310 98 Paved parking, HSG A 5,494 98 Roofs, HSG A 2,018 39 >75% Grass cover, Good, HSG A 15,822 90 Weighted Average 2,018 12.75% Pervious Area 13,804 87.25% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 35 0.0200 0.10 Sheet Flow, Grass: Dense n= 0.240 P2= 3.35" 0.3 15 0.0200 0.96 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.2 30 0.0200 2.87 Shallow Concentrated Flow, Paved Kv= 20.3 fps 6.5 80 Total Subcatchment 3Sa: 3Sa Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)2 1 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=15,822 sf Runoff Volume=0.185 af Runoff Depth=6.12" Flow Length=80' Slope=0.0200 '/' Tc=6.5 min CN=90 2.40 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 67HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Subcatchment 4S: 4S Runoff = 1.62 cfs @ 12.08 hrs, Volume= 0.124 af, Depth= 6.35" Routed to Pond 2P : SUBSURFACE SYSTEM #2 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35" Area (sf) CN Description 6,395 98 Paved parking, HSG A 2,745 98 Roofs, HSG A 1,090 39 >75% Grass cover, Good, HSG A 10,230 92 Weighted Average 1,090 10.65% Pervious Area 9,140 89.35% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 0.8 65 0.0200 1.29 Sheet Flow, Smooth surfaces n= 0.011 P2= 3.35" 0.8 65 Total, Increased to minimum Tc = 6.0 min Subcatchment 4S: 4S Runoff Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Type III 24-hr 100-yr Rainfall=7.30" P2=3.35" Runoff Area=10,230 sf Runoff Volume=0.124 af Runoff Depth=6.35" Flow Length=65' Slope=0.0200 '/' Tc=6.0 min CN=92 1.62 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 68HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP1: DP1 Inflow Area = 0.196 ac, 1.17% Impervious, Inflow Depth = 0.24" for 100-yr event Inflow = 0.03 cfs @ 12.13 hrs, Volume= 0.004 af Outflow = 0.03 cfs @ 12.13 hrs, Volume= 0.004 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP1: DP1 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.032 0.03 0.028 0.026 0.024 0.022 0.02 0.018 0.016 0.014 0.012 0.01 0.008 0.006 0.004 0.002 0 Inflow Area=0.196 ac0.03 cfs0.03 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 69HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Reach DP2: DP2 Inflow Area = 0.202 ac, 0.00% Impervious, Inflow Depth = 0.88" for 100-yr event Inflow = 0.10 cfs @ 12.18 hrs, Volume= 0.015 af Outflow = 0.10 cfs @ 12.18 hrs, Volume= 0.015 af, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Reach DP2: DP2 InflowOutflow Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.11 0.105 0.1 0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.202 ac0.10 cfs0.10 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 70HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 1P: SUBSURFACE SYSTEM #1 Inflow Area = 0.455 ac, 84.26% Impervious, Inflow Depth = 5.93" for 100-yr event Inflow = 2.95 cfs @ 12.09 hrs, Volume= 0.225 af Outflow = 0.39 cfs @ 11.70 hrs, Volume= 0.225 af, Atten= 87%, Lag= 0.0 min Discarded = 0.39 cfs @ 11.70 hrs, Volume= 0.225 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 11.19' @ 12.64 hrs Surf.Area= 2,031 sf Storage= 3,033 cf Plug-Flow detention time= 50.0 min calculated for 0.225 af (100% of inflow) Center-of-Mass det. time= 49.9 min ( 833.0 - 783.0 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,851 cf 30.00'W x 67.70'L x 3.50'H Field A 7,108 cf Overall - 2,481 cf Embedded = 4,627 cf x 40.0% Voids #2A 9.50' 2,481 cf ADS_StormTech SC-740 +Cap x 54 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 54 Chambers in 6 Rows 4,332 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.39 cfs @ 11.70 hrs HW=9.05' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.39 cfs) Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 71HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 9 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 65.70' Row Length +12.0" End Stone x 2 = 67.70' Base Length 6 Rows x 51.0" Wide + 6.0" Spacing x 5 + 12.0" Side Stone x 2 = 30.00' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 54 Chambers x 45.9 cf = 2,480.8 cf Chamber Storage 7,108.2 cf Field - 2,480.8 cf Chambers = 4,627.4 cf Stone x 40.0% Voids = 1,851.0 cf Stone Storage Chamber Storage + Stone Storage = 4,331.7 cf = 0.099 af Overall Storage Efficiency = 60.9% Overall System Size = 67.70' x 30.00' x 3.50' 54 Chambers 263.3 cy Field 171.4 cy Stone Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 72HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 1P: SUBSURFACE SYSTEM #1 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)3 2 1 0 Inflow Area=0.455 ac Peak Elev=11.19' Storage=3,033 cf 2.95 cfs 0.39 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 73HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 2P: SUBSURFACE SYSTEM #2 Inflow Area = 0.235 ac, 89.35% Impervious, Inflow Depth = 6.35" for 100-yr event Inflow = 1.62 cfs @ 12.08 hrs, Volume= 0.124 af Outflow = 0.22 cfs @ 11.70 hrs, Volume= 0.124 af, Atten= 86%, Lag= 0.0 min Discarded = 0.22 cfs @ 11.70 hrs, Volume= 0.124 af Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 11.03' @ 12.59 hrs Surf.Area= 1,170 sf Storage= 1,593 cf Plug-Flow detention time= 42.9 min calculated for 0.124 af (100% of inflow) Center-of-Mass det. time= 42.8 min ( 814.4 - 771.6 ) Volume Invert Avail.Storage Storage Description #1A 9.00' 1,087 cf 25.25'W x 46.34'L x 3.50'H Field A 4,095 cf Overall - 1,378 cf Embedded = 2,717 cf x 40.0% Voids #2A 9.50' 1,378 cf ADS_StormTech SC-740 +Cap x 30 Inside #1 Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 30 Chambers in 5 Rows 2,465 cf Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 9.00'8.270 in/hr Exfiltration over Surface area Phase-In= 0.01' Discarded OutFlow Max=0.22 cfs @ 11.70 hrs HW=9.05' (Free Discharge) 1=Exfiltration (Exfiltration Controls 0.22 cfs) Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 74HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 - Chamber Wizard Field A Chamber Model = ADS_StormTech SC-740 +Cap (ADS StormTech® SC-740 with cap length) Effective Size= 44.6"W x 30.0"H => 6.45 sf x 7.12'L = 45.9 cf Overall Size= 51.0"W x 30.0"H x 7.56'L with 0.44' Overlap 51.0" Wide + 6.0" Spacing = 57.0" C-C Row Spacing 6 Chambers/Row x 7.12' Long +0.81' Cap Length x 2 = 44.34' Row Length +12.0" End Stone x 2 = 46.34' Base Length 5 Rows x 51.0" Wide + 6.0" Spacing x 4 + 12.0" Side Stone x 2 = 25.25' Base Width 6.0" Stone Base + 30.0" Chamber Height + 6.0" Stone Cover = 3.50' Field Height 30 Chambers x 45.9 cf = 1,378.2 cf Chamber Storage 4,095.0 cf Field - 1,378.2 cf Chambers = 2,716.8 cf Stone x 40.0% Voids = 1,086.7 cf Stone Storage Chamber Storage + Stone Storage = 2,464.9 cf = 0.057 af Overall Storage Efficiency = 60.2% Overall System Size = 46.34' x 25.25' x 3.50' 30 Chambers 151.7 cy Field 100.6 cy Stone Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 75HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 2P: SUBSURFACE SYSTEM #2 InflowDiscarded Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)1 0 Inflow Area=0.235 ac Peak Elev=11.03' Storage=1,593 cf 1.62 cfs 0.22 cfs Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 76HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Summary for Pond 4Pe: EXISTING DEPRESSED AREA Inflow Area = 0.143 ac, 1.61% Impervious, Inflow Depth = 0.96" for 100-yr event Inflow = 0.09 cfs @ 12.15 hrs, Volume= 0.011 af Outflow = 0.03 cfs @ 12.63 hrs, Volume= 0.011 af, Atten= 64%, Lag= 28.5 min Discarded = 0.03 cfs @ 12.63 hrs, Volume= 0.011 af Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 af Routed to Reach DP1 : DP1 Routing by Dyn-Stor-Ind method, Time Span= 0.00-36.00 hrs, dt= 0.02 hrs Peak Elev= 13.26' @ 12.63 hrs Surf.Area= 577 sf Storage= 86 cf Plug-Flow detention time= 30.2 min calculated for 0.011 af (100% of inflow) Center-of-Mass det. time= 30.3 min ( 950.1 - 919.9 ) Volume Invert Avail.Storage Storage Description #1 12.80' 1,535 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 12.80 10 0 0 13.00 40 5 5 13.50 1,065 276 281 14.00 3,950 1,254 1,535 Device Routing Invert Outlet Devices #1 Primary 13.60'10.0' long x 10.0' breadth Broad-Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64 #2 Discarded 12.80'2.410 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.03 cfs @ 12.63 hrs HW=13.26' (Free Discharge) 2=Exfiltration (Exfiltration Controls 0.03 cfs) Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=12.80' TW=0.00' (Dynamic Tailwater) 1=Broad-Crested Rectangular Weir ( Controls 0.00 cfs) Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/26/2025Prepared by Merrill Associates Inc Page 77HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Pond 4Pe: EXISTING DEPRESSED AREA InflowOutflowDiscardedPrimary Hydrograph Time (hours) 3635343332313029282726252423222120191817161514131211109876543210Flow (cfs)0.095 0.09 0.085 0.08 0.075 0.07 0.065 0.06 0.055 0.05 0.045 0.04 0.035 0.03 0.025 0.02 0.015 0.01 0.005 0 Inflow Area=0.143 ac Peak Elev=13.26' Storage=86 cf 0.09 cfs 0.03 cfs0.03 cfs 0.00 cfs (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Appendix C Stormwater Compliance Calculations • Groundwater Recharge Volume • Infiltration System Drawdown • Water Quality Volume • TSS Removal Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/25/2025Prepared by Merrill Associates Inc HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1P: SUBSURFACE SYSTEM #1 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 9.00 2,031 0 9.05 2,031 41 9.10 2,031 81 9.15 2,031 122 9.20 2,031 162 9.25 2,031 203 9.30 2,031 244 9.35 2,031 284 9.40 2,031 325 9.45 2,031 366 9.50 2,031 406 9.55 2,031 490 9.60 2,031 573 9.65 2,031 656 9.70 2,031 740 9.75 2,031 822 9.80 2,031 905 9.85 2,031 987 9.90 2,031 1,069 9.95 2,031 1,151 10.00 2,031 1,233 10.05 2,031 1,314 10.10 2,031 1,394 10.15 2,031 1,475 10.20 2,031 1,555 10.25 2,031 1,634 10.30 2,031 1,713 10.35 2,031 1,792 10.40 2,031 1,870 10.45 2,031 1,948 10.50 2,031 2,025 10.55 2,031 2,102 10.60 2,031 2,178 10.65 2,031 2,254 10.70 2,031 2,329 10.75 2,031 2,403 10.80 2,031 2,477 10.85 2,031 2,551 10.90 2,031 2,623 10.95 2,031 2,695 11.00 2,031 2,766 11.05 2,031 2,837 11.10 2,031 2,906 11.15 2,031 2,975 11.20 2,031 3,043 11.25 2,031 3,109 11.30 2,031 3,175 11.35 2,031 3,239 11.40 2,031 3,303 11.45 2,031 3,365 11.50 2,031 3,426 11.55 2,031 3,486 11.60 2,031 3,544 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 11.65 2,031 3,600 11.70 2,031 3,654 11.75 2,031 3,704 11.80 2,031 3,752 11.85 2,031 3,798 11.90 2,031 3,842 11.95 2,031 3,884 12.00 2,031 3,926 12.05 2,031 3,966 12.10 2,031 4,007 12.15 2,031 4,047 12.20 2,031 4,088 12.25 2,031 4,129 12.30 2,031 4,169 12.35 2,031 4,210 12.40 2,031 4,250 12.45 2,031 4,291 12.50 2,031 4,332 Type III 24-hr 100-yr Rainfall=7.30", P2=3.35"PWP Printed 6/25/2025Prepared by Merrill Associates Inc HydroCAD® 10.20-3h s/n 02159 © 2024 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 2P: SUBSURFACE SYSTEM #2 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 9.00 1,170 0 9.05 1,170 23 9.10 1,170 47 9.15 1,170 70 9.20 1,170 94 9.25 1,170 117 9.30 1,170 140 9.35 1,170 164 9.40 1,170 187 9.45 1,170 211 9.50 1,170 234 9.55 1,170 281 9.60 1,170 328 9.65 1,170 376 9.70 1,170 423 9.75 1,170 469 9.80 1,170 516 9.85 1,170 563 9.90 1,170 609 9.95 1,170 655 10.00 1,170 701 10.05 1,170 747 10.10 1,170 793 10.15 1,170 838 10.20 1,170 884 10.25 1,170 929 10.30 1,170 973 10.35 1,170 1,018 10.40 1,170 1,062 10.45 1,170 1,106 10.50 1,170 1,150 10.55 1,170 1,194 10.60 1,170 1,237 10.65 1,170 1,280 10.70 1,170 1,322 10.75 1,170 1,364 10.80 1,170 1,406 10.85 1,170 1,448 10.90 1,170 1,489 10.95 1,170 1,530 11.00 1,170 1,570 11.05 1,170 1,610 11.10 1,170 1,650 11.15 1,170 1,689 11.20 1,170 1,727 11.25 1,170 1,765 11.30 1,170 1,802 11.35 1,170 1,839 11.40 1,170 1,875 11.45 1,170 1,910 11.50 1,170 1,945 11.55 1,170 1,979 11.60 1,170 2,012 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 11.65 1,170 2,044 11.70 1,170 2,075 11.75 1,170 2,104 11.80 1,170 2,131 11.85 1,170 2,157 11.90 1,170 2,183 11.95 1,170 2,207 12.00 1,170 2,231 12.05 1,170 2,254 12.10 1,170 2,278 12.15 1,170 2,301 12.20 1,170 2,325 12.25 1,170 2,348 12.30 1,170 2,371 12.35 1,170 2,395 12.40 1,170 2,418 12.45 1,170 2,442 12.50 1,170 2,465 MERRILL ENGINEERS AND LAND SURVEYORS JOB 24-479 427 COLUMBIA ROAD, HANOVER, MA. 02339 SHEET N0.1 of 2 TEL. (781) 826-9200 CALCULATED BY NC CHECKED BY DK Date:6/20/2025 GROUNDWATER RECHARGE VOLUMES (STANDARD #3) Location:897 Main Street (Rt 28), South Yarmouth MA Total Area (Ac.)=0.61 (Total impervious watershed area) Total Impervious Area A Soil (Ac.)=0.61 Total Impervious Area B Soil (Ac.)=0.00 Total Impervious Area C Soil (Ac.)=0.00 Total Impervious Area D Soil (Ac.)=0.00 Roofs, Drives, Road and Sidewalk Vol. To Recharge (inches per Imp. Acre) Volume (Imp. Area x inches per Acre) Recharge Volume (A soil)0.60 0.37 Recharge Volume (B soil)0.35 0.00 Recharge Volume (C soil)0.25 0.00 Recharge Volume (D soil)0.10 0.00 0.37 AC-IN 0.031 AC-FT 1337 C.F. Recharge volume provided within Infiltration Facilities (chamber systems)6,797 C.F. (Rv will be total storage volume below lowest outlet elevation) Groundwater Recharge Volume Calculation Per Infiltration System: Subsurface Infiltration Chamber Sys. #1 Total Impervious Area A Soil (SF.)=16634 Roofs, Drives, Road and Sidewalk Total Impervious Area B Soil (SF.)=0 Total Impervious Area C Soil (SF.)=0 Total Impervious Area D Soil (SF.)=0 Vol. To Recharge (inches per Imp. SF) Volume (Imp. Area x inches per SF) Recharge Volume (A soil)0.60 9980 SF-IN Recharge Volume (B soil)0.35 0 Recharge Volume (C soil)0.25 0 Recharge Volume (D soil)0.10 0 Required Recharge Volume:832 C.F. Proposed Recharge Volume:4,332 C.F. Subsurface Infiltration Chamber Sys. #2 Total Required Recharge Volume: DESIGN SUFFICIENT Total Impervious Area A Soil (SF.)=10100 Roofs, Drives, Road and Sidewalk Total Impervious Area B Soil (SF.)=0 Total Impervious Area C Soil (SF.)=0 Total Impervious Area D Soil (SF.)=0 Vol. To Recharge (inches per Imp. SF) Volume (Imp. Area x inches per SF) Recharge Volume (A soil)0.60 6060 SF-IN Recharge Volume (B soil)0.35 0 Recharge Volume (C soil)0.25 0 Recharge Volume (D soil)0.10 0 Required Recharge Volume:505 C.F. Proposed Recharge Volume:2,465 C.F. Drawdown Calculations for Infiltration Systems: Drawdown Time = Rv/(k)(basin bottom area)where Rv will be total storage volume below lowest outlet elevation Sub .Infiltration Chamber System #1 3.09 < 72 hrs. Rv =4332 cf k=8.27 in/hr (convert to ft) Bot. Area=2,031 sf Sub. Infiltration Chamber System #2 2.32 < 72 hrs. Rv =2465 cf k=8.27 in/hr (convert to ft) Bot. Area=1539 sf DESIGN SUFFICIENT MERRILL ENGINEERS AND LAND SURVEYORS JOB 24-479 427 COLUMBIA ROAD, HANOVER, MA. 02339 SHEET N0.1 of 2 TEL. (781) 826-9200 CALCULATED BY NC CHECKED BY DK Date:6/20/2025 Rev: WATER QUALITY VOLUME (STANDARD #4) Location:897 Main Street (Rt 28), South Yarmouth MA Subsurface Infiltration Chamber System #1 qu for Tc of 6 min.774 (csm/in) Impervious Area: AC*0.0015625mi2/AC 0.000104 mi2 0.07 AC WQV Treated: 1.00 in Q (Peak flow rate for 1.0" WQV):0.08 cfs Proposed FD-HC3 Max. Treated Flow Rate: 0.84 cfs Max flow rate = 15 cfs qu for Tc of 6 min.774 (csm/in) Impervious Area: AC*0.0015625mi2/AC 0.000296 mi2 0.19 AC WQV Treated: 1.00 in Q (Peak flow rate for 1.0" WQV):0.23 cfs Proposed FD-HC3 Max. Treated Flow Rate: 0.84 cfs Max flow rate = 15 cfs Volume using:1.0 inch x Imp. Area (Per Mass. Stormwater Regulations) 1 inch x Imp. Area 1,157 CF (min) WQ Treatment within FD Unit = = included in total system WQ Treatment within basin (below outlet) = 4,332 4,332 CF (Proposed) DESIGN SUFFICIENT Subsurface Infiltration Chamber System #2 qu for Tc of 6 min.774 (csm/in) Impervious Area: AC*0.0015625mi2/AC 0.000167 mi2 0.11 AC WQV Treated: 1.00 in Q (Peak flow rate for 1.0" WQV):0.13 cfs Proposed FD-HC3 Max. Treated Flow Rate: 0.84 cfs Max flow rate = 15 cfs First Defense Unit (FD-HC#2): Proprietary Treatment Unit: Q=(qu)(A)(WQV) First Defense Unit (FD-HC #1): Proprietary Treatment Unit: Q=(qu)(A)(WQV) Total Walter Quality Volume Provided = First Defense Unit (FD-HC#4): Proprietary Treatment Unit: Q=(qu)(A)(WQV) qu for Tc of 6 min.774 (csm/in) Impervious Area: AC*0.0015625mi2/AC 0.000059 mi2 0.04 AC WQV Treated: 1.00 in Q (Peak flow rate for 1.0" WQV):0.05 cfs Proposed FD-HC3 Max. Treated Flow Rate: 0.84 cfs Max flow rate = 15 cfs Volume using:1.0 inch x Imp. Area (Per Local Stormwater Regulations) 1 inch x Imp. Area 982 CF (min) WQ Treatment within FD Unit = = included in total system WQ Treatment within basin (below outlet) = 2,465 2,465 CF (Proposed) DESIGN SUFFICIENT Total Impervious Area: Proposed Roof 0.19 AC Proposed Road/Pvmt/Sidewalk 0.42 AC Total Area:0.61 AC Water Quality Volume using:1.0 inch x Imp. Area (1.0 Treatment for critical areas) 1 inch x Imp. Area 2,228 CF (min) 6,797 CF Total Walter Quality Volume Provided = Water Quality Volume - Total Site Improvements Total Walter Quality Volume Provided = First Defense Unit (FD-HC3 #3): Proprietary Treatment Unit: Q=(qu)(A)(WQV) TSS Removal Calculation Worksheet Pretreatment for Infiltration Systems Proj. No.: 24-479 Date: 06/24/2025 Location: 897 Main Street, Yarmouth Computed by: NC A B C D E BMP TSS Removal Starting TSS Amount Remaining Rate Load*Removed (BxC)Load (C-D) Total TSS Removal= Notes: Pre-treatment Unit (First Defense Unit) 50 1.00 0.5 0.50 *Starting TSS Load for first BMP= 1.00. TSS load for subsequent BMP's is equal to the Remaining Load (E) from the previous BMP. 50% V INSTRUCTIONS:Version 1, Automated: Mar. 4, 2008 1. In BMP Column, click on Blue Cell to Activate Drop Down Menu 2. Select BMP from Drop Down Menu 3. After BMP is selected, TSS Removal and other Columns are automatically completed. Location: B C D E F TSS Removal Starting TSS Amount Remaining BMP1 Rate1 Load*Removed (C*D)Load (D-E) Deep Sump and Hooded Catch Basin 0.25 1.00 0.25 0.75 Subsurface Infiltration Structure 0.80 0.75 0.60 0.15 0.00 0.15 0.00 0.15 0.00 0.15 0.00 0.15 0.00 0.15 0.00 0.15 Total TSS Removal =85% Separate Form Needs to be Completed for Each Outlet or BMP Train Project:24-479 Prepared By:NC *Equals remaining load from previous BMP (E) Date:6/24/2025 which enters the BMP 897 Main Street, Yarmouth MA TSS Removal Calculation WorksheetNon-automated TSS Calculation Sheet must be used if Proprietary BMP Proposed 1. From MassDEP Stormwater Handbook Vol. 1 Mass. Dept. of Environmental Protection NOAA Atlas 14, Volume 10, Version 3 Location name: South Yarmouth, Massachusetts, USA* Latitude: 41.6535°, Longitude: -70.2102° Elevation: 14 ft** * source: ESRI Maps ** source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica, Sandra Pavlovic, Michael St. Laurent, Carl Trypaluk, Dale Unruh, Orlan Wilhite NOAA, National Weather Service, Silver Spring, Maryland PF_tabular | PF_graphical | Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.268 (0.215‑0.330) 0.339 (0.272‑0.418) 0.455 (0.364‑0.563) 0.551 (0.438‑0.686) 0.684 (0.524‑0.897) 0.783 (0.587‑1.05) 0.889 (0.647‑1.24) 1.02 (0.689‑1.44) 1.21 (0.784‑1.78) 1.37 (0.868‑2.06) 10-min 0.379 (0.304‑0.467) 0.480 (0.385‑0.592) 0.645 (0.516‑0.799) 0.781 (0.620‑0.972) 0.969 (0.743‑1.27) 1.11 (0.831‑1.49) 1.26 (0.916‑1.76) 1.44 (0.975‑2.04) 1.71 (1.11‑2.51) 1.94 (1.23‑2.91) 15-min 0.446 (0.358‑0.549) 0.564 (0.453‑0.696) 0.758 (0.606‑0.938) 0.919 (0.730‑1.14) 1.14 (0.874‑1.49) 1.30 (0.978‑1.75) 1.48 (1.08‑2.08) 1.69 (1.15‑2.40) 2.01 (1.31‑2.96) 2.28 (1.45‑3.43) 30-min 0.658 (0.528‑0.810) 0.829 (0.665‑1.02) 1.11 (0.885‑1.37) 1.34 (1.06‑1.67) 1.66 (1.27‑2.17) 1.90 (1.42‑2.54) 2.15 (1.57‑3.01) 2.46 (1.67‑3.49) 2.92 (1.90‑4.29) 3.32 (2.10‑4.97) 60-min 0.870 (0.699‑1.07) 1.09 (0.877‑1.35) 1.46 (1.16‑1.80) 1.76 (1.40‑2.19) 2.18 (1.67‑2.85) 2.49 (1.86‑3.34) 2.82 (2.05‑3.95) 3.22 (2.18‑4.57) 3.83 (2.49‑5.63) 4.35 (2.75‑6.52) 2-hr 1.22 (0.988‑1.50) 1.51 (1.22‑1.86) 1.99 (1.60‑2.45) 2.39 (1.91‑2.95) 2.93 (2.26‑3.81) 3.34 (2.52‑4.43) 3.77 (2.76‑5.22) 4.29 (2.94‑6.02) 5.08 (3.32‑7.37) 5.74 (3.66‑8.49) 3-hr 1.46 (1.19‑1.78) 1.79 (1.46‑2.19) 2.34 (1.89‑2.86) 2.79 (2.24‑3.44) 3.42 (2.65‑4.41) 3.88 (2.94‑5.12) 4.38 (3.22‑6.01) 4.96 (3.41‑6.91) 5.84 (3.84‑8.42) 6.58 (4.22‑9.67) 6-hr 1.91 (1.56‑2.31) 2.31 (1.89‑2.80) 2.97 (2.42‑3.61) 3.52 (2.84‑4.30) 4.27 (3.33‑5.45) 4.83 (3.68‑6.30) 5.42 (4.00‑7.34) 6.11 (4.24‑8.42) 7.13 (4.73‑10.1) 7.97 (5.16‑11.6) 12-hr 2.39 (1.96‑2.87) 2.85 (2.34‑3.43) 3.61 (2.95‑4.35) 4.23 (3.44‑5.14) 5.10 (4.00‑6.44) 5.75 (4.40‑7.40) 6.43 (4.76‑8.57) 7.19 (5.03‑9.78) 8.29 (5.55‑11.6) 9.19 (6.00‑13.1) 24-hr 2.84 (2.36‑3.40) 3.35 (2.77‑4.01) 4.19 (3.45‑5.02) 4.88 (4.00‑5.88) 5.83 (4.60‑7.29) 6.56 (5.05‑8.34) 7.30 (5.44‑9.59) 8.12 (5.72‑10.9) 9.25 (6.25‑12.8) 10.2 (6.69‑14.3) 2-day 3.26 (2.72‑3.86) 3.80 (3.17‑4.51) 4.69 (3.89‑5.58) 5.43 (4.47‑6.49) 6.44 (5.11‑7.97) 7.21 (5.59‑9.07) 8.00 (5.99‑10.4) 8.84 (6.29‑11.7) 9.98 (6.81‑13.7) 10.9 (7.23‑15.2) 3-day 3.54 (2.97‑4.19) 4.10 (3.42‑4.84) 5.00 (4.16‑5.92) 5.74 (4.75‑6.84) 6.77 (5.40‑8.33) 7.56 (5.88‑9.45) 8.36 (6.28‑10.7) 9.20 (6.58‑12.1) 10.4 (7.11‑14.1) 11.3 (7.52‑15.6) 4-day 3.79 (3.18‑4.46) 4.34 (3.64‑5.12) 5.25 (4.38‑6.20) 6.00 (4.98‑7.12) 7.03 (5.63‑8.62) 7.82 (6.11‑9.74) 8.62 (6.51‑11.0) 9.48 (6.81‑12.4) 10.7 (7.34‑14.4) 11.6 (7.78‑16.0) 7-day 4.43 (3.74‑5.19) 4.99 (4.21‑5.85) 5.91 (4.96‑6.94) 6.67 (5.57‑7.87) 7.72 (6.22‑9.39) 8.52 (6.70‑10.5) 9.34 (7.09‑11.8) 10.2 (7.37‑13.2) 11.4 (7.89‑15.2) 12.3 (8.30‑16.7) 10-day 5.03 (4.26‑5.87) 5.61 (4.75‑6.56) 6.57 (5.53‑7.68) 7.36 (6.16‑8.65) 8.44 (6.82‑10.2) 9.28 (7.32‑11.4) 10.1 (7.70‑12.7) 11.0 (7.99‑14.2) 12.2 (8.48‑16.1) 13.1 (8.88‑17.7) 20-day 6.85 (5.84‑7.94) 7.54 (6.42‑8.74) 8.66 (7.34‑10.1) 9.58 (8.08‑11.2) 10.9 (8.83‑13.0) 11.9 (9.41‑14.4) 12.8 (9.80‑15.9) 13.8 (10.1‑17.5) 15.0 (10.5‑19.6) 15.8 (10.8‑21.1) 30-day 8.42 (7.21‑9.71) 9.20 (7.86‑10.6) 10.5 (8.92‑12.1) 11.5 (9.76‑13.4) 13.0 (10.6‑15.4) 14.1 (11.2‑17.0) 15.2 (11.6‑18.6) 16.2 (12.0‑20.5) 17.5 (12.4‑22.6) 18.3 (12.6‑24.1) 45-day 10.4 (8.96‑12.0) 11.3 (9.72‑13.0) 12.8 (10.9‑14.7) 14.0 (11.9‑16.2) 15.6 (12.8‑18.4) 17.0 (13.5‑20.2) 18.2 (14.0‑22.1) 19.3 (14.3‑24.2) 20.6 (14.7‑26.5) 21.4 (14.8‑28.0) 60-day 12.2 (10.5‑13.9) 13.1 (11.3‑15.0) 14.7 (12.6‑16.9) 16.1 (13.7‑18.5) 17.9 (14.7‑21.0) 19.3 (15.5‑23.0) 20.7 (15.9‑25.0) 21.9 (16.3‑27.3) 23.2 (16.6‑29.7) 24.1 (16.7‑31.3) 1 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 atupper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical 10/06/2025, 17:20 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=41.6535&lon=-70.2102&data=depth&units=english&series=pds 1/4 Back to Top Maps & aerials Small scale terrain 10/06/2025, 17:20 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=41.6535&lon=-70.2102&data=depth&units=english&series=pds 2/4 Large scale terrain Large scale map Large scale aerial + – 3km 2mi + – 100km 60mi + – 100km 60mi 10/06/2025, 17:20 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=41.6535&lon=-70.2102&data=depth&units=english&series=pds 3/4 Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring, MD 20910 Questions?: HDSC.Questions@noaa.gov Disclaimer + – 100km 60mi 10/06/2025, 17:20 Precipitation Frequency Data Server https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=41.6535&lon=-70.2102&data=depth&units=english&series=pds 4/4 First Defense is a versatile stormwater separator with some of the highest approved flow rates in the United States. Engineers and contractors can save site space and reduce project costs by using the smallest possible footprint. It works with single or multiple inlet pipes and inlet grates. An internal bypass conveys infrequent peak flows directly to the outlet, efficiently capturing pollutants and preventing washouts.Benefits Highest Flow Through the Smallest Footprint First Defense® Advanced Hydrodynamic Separator »Smaller Footprint, Lower Costs First Defense provides space-saving, easy-to- install surface water treatment in standard size chambers/manholes. »Adapt to Site Limitations Variable configurations will help you effectively slip First Defense into a tight spot. It also works well with large pipes, multiple inlet pipes and inlet grates. »Reduce Installation Time & Costs Every First Defense unit is delivered to site pre- assembled and ready for install. »Online System Configuration First Defense eliminates the need for separate structures with its integrated internal bypass. »Designed with Maintenance in Mind Easy vactor hose access through the center shaft of the system makes for quick sump cleanout, saving time and reducing long-term operational cost. Contaminated stormwater runoff enters the inlet chute from a surface grate and/or inlet pipe. The inlet chute introduces flow into the chamber tangentially to create a low energy vortex flow regime (magenta arrow) that directs sediment into the sump while oils, floating trash and debris rise to the surface. Treated stormwater exits through a submerged outlet chute located opposite to the direction of the rotating flow (blue arrow). Enhanced vortex separation is provided by forcing the rotating flow within the vessel to follow the longest path possible rather than directly from inlet to outlet. Higher flows bypass the treatment chamber to prevent turbulence and washout of captured pollutants. An internal bypass conveys infrequent peak flows directly to the outlet eliminating the need for, and expense of, external bypass control structures. A floatables draw off slot functions to convey floatables into the treatment chamber prior to bypass. »Areas requiring a minimum of 50% TSS removal »Stormwater treatment at the point of entry into the drainage line »Sites constrained by space, topography or drainage profiles with limited slope and depth of cover »Highways, parking lots, industrial areas and urban developments »Pre-treatment to ponds, storage systems, green infrastructure Features Applications Product Summary A Simple Solution for the Trickiest Sites Optional inlet grate Internal bypass weir Outlet pipe Oil/floatables storage Outlet chute Sediment storage sump Precast chamber Optional inlet pipe Floatables drawoff slot (not pictured) Inlet chute Hydro International, 94 Hutchins Drive, Portland, ME 04102 Tel : (207) 756-6200 Email: stormwaterinquiry@hydro-int.com Web: www.hydro-int.com/firstdefense Download Drawings: hydro-int.com/fddrawings Operation & Maintenance Manual: hydro-int.com/fd-om FD_SS_B_2203 Free Online Design Tool This free online sizing tool will recommend the best separator, model size and online or offline configuration based on site-specific data entered by the user. Upon completion, users have the option to submit the design to Hydro International for a free review by our engineering team. Go to hydro-int.com/sizing to access the tool. Sizing & Specifications Hydro International offers First Defense units in two versions that conform to the performance requirements of different states’ water quality regulations.4 Diameter Peak Online Flow Rate Maximum Pipe Diameter1 Typical Sediment Storage Capacity2 Minimum Distance from Outlet Invert to Top of Rim3 Standard Distance from Outlet Invert to Sump Floor (ft / m)(cfs / L/s)(in / mm)(yd3 / m3)(ft / m)(ft / m) 3 / 0.9 15 / 424 18 / 450 0.4 / 0.3 2.0 - 2.5 / 0.61 - 0.76 3.71 / 1.13 4 / 1.2 18 / 510 24 / 600 0.7 / 0.5 2.0 - 3.0 / 0.61 - 0.91 4.97 / 1.5 5 / 1.5 20 / 566 24 / 600 1.1 / .84 2.0 - 3.7 / 0.61 - 1.13 5.83 / 1.5 6 / 1.8 32 / 906 30 / 750 1.6 / 1.2 2.0 - 4.1 / 0.61 - 1.25 5.97 / 1.8 8 / 2.4 50 / 1415 48 / 1200 2.8 / 2.1 2.4 - 5.4 / 0.73 -1.65 7.40 / 2.2 10 / 3.0 50 / 1415 48 / 1200 4.4 / 3.3 2.4 - 6.8 / 0.73 - 2.07 10.25 / 3.12 First Defense units are available in six diameters to fit standard chamber and manhole sizes. The dimensions below are common across all model numbers. Also available in a screened configuration for Full Trash Capture! First Defense High Capacity Model Number Typical TSS Treatment Flow Rates NJDEP Certified4 110µm (cfs / L/s)(cfs / L/s) FDHC-3 0.84 / 23.7 1.06 / 30.0 FDHC-4 1.50 / 42.4 1.88 / 53.2 FDHC-5 2.35 / 66.2 2.94 / 83.2 FDHC-6 3.38 / 95.7 4.23 / 119.8 FDHC-8 6.00 / 169.9 7.52 / 212.9 FDHC-10 9.38 / 265.6 11.75 / 332.7 1Contact Hydro International when larger pipe sizes are required. 2Contact Hydro International when custom sediment storage capacity is required. 3These are guidlines only. Minimum distance is based on pipe diameter and headloss at assumed flow rates, contact Hydro for detailed design. 4NJDEP Certified / NJCAT Verified , based on one inlet pipe and no inlet grate. First Defense Optimum Model Number NJDEP Certified Treatment Flow Rates4 (cfs / L/s) FDO-3 1.02 / 28.9 FDO-4 1.81 / 51.3 FDO-5 2.83 / 80.0 FDO-6 4.07 / 115.2 FDO-8 7.23 / 204.7 FDO-10 11.33 / 320.6 (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Appendix D Stormwater Management Plans and Documentation • Stormwater Report Checklist • Construction Operation and Maintenance Plan/Construction Pollution Prevention Plan • Long Term Source Control/Pollution Prevention Plan and Operation and Maintenance Plan swcheck.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 A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. 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.1 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. 1 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 2 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 Signature and Date 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 July 24, 2025 swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 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. Subsurface infiltration chamber systems swcheck.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 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 Field1 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. 21E 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. 21E site or a solid waste landfill and a mounding analysis is included. 1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. swcheck.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 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 6 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 ½” 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 7 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 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. swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program 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. CONSTRUCTION PHASE OPERATION AND MAINTENANCE PLAN/ CONSTRUCTION POLLUTION PREVENTION PLAN Dated: July 24, 2025 Residential Development 897 Main Street (Route 28) S. Yarmouth, MA The structural and stabilization practices utilized on the site correspond with plans entitled “897 Main Street, Residential Development”, dated July 24, 2025 as revised hereinafter referred to as the Site Plans. Responsible Party for Operation and Maintenance Contact Information: ACRE+ WCI Real Estate Ventures 1, LLC 897 Main Street (Route 28) South Yarmouth, MA P: 610-737-7625 Source of Funding: Operation and Maintenance of this stormwater management system will be the responsibility of the property owner to include its successor and/or assigns, as the same may appear on record with the appropriate register of deeds. The following Operation and Maintenance plan is provided to upkeep proposed non-structural and structural best performance practices as outlined in the Massachusetts Department of Environmental Protection’s Stormwater Management Policy. The proposed redevelopment consists of a residential development under a M.G.L. Chapter 40B Comprehensive Permit, containing 3 residential apartment buildings totaling 27 residential units, razing of the existing commercial building and outbuildings, construction of a parking and driveway areas, stormwater management facilities, utility service connections, landscaping and associated infrastructure. The site will have two (2) subsurface Stormtech infiltration systems, along with pretreatment proprietary First Defense Units. Erosion and Sedimentation Control Best Management Practices: Structural Practices: 1) Silt Sock Erosion Control Barrier – A silt sock barrier will be constructed along downward slopes at the limit of work in locations shown on the plans. This control will be installed prior to major soil disturbance on the site. The sediment silt sock barrier should be installed as shown on the Site Plan and Construction Detail Plan. Silt Sock Installation Requirements a) Locate the silt sock where identified on the plans. b) The silt sock line should be nearly level through most of its length to impound a broad, temporary pool. The last 10 to 20 feet at each end of the silt sack should be swung slightly uphill (approximately 0.5 feet in elevation) to provide storage capacity. c) The silt sock shall be staked every 8 linear feet with 1-inch by 1-inch stakes. d) Sediment silt sock should be removed when they have served their useful purpose, but not before the upslope area has been permanently stabilized through one growing season. Retained sediment must be removed and properly disposed of, or mulched and seeded. Silt Sock Inspection/Maintenance a) Silt sock should be inspected immediately after each rainfall event of 1-inch or greater, and at least daily during prolonged rainfall. Inspect the depth of sediment, fabric tears, and to see that the stakes are firmly in the ground. Repair or replace as necessary. b) Remove sediment deposits promptly after storm events to provide adequate storage volume for the next rain and to reduce pressure on the sock. Sediment will be removed from behind the silt sock when it becomes about ½ foot deep. Take care to avoid undermining the sock during cleanout. c) If the fabric tears, decomposes, or in any way becomes ineffective, replace it immediately. d) Remove all silt sock materials after the contributing drainage area has been properly stabilized. Sediment deposits remaining after the fabric has been removed should be graded to conform with the existing topography and vegetated. 2) Sediment Fence Control Barrier – A sediment fence barrier will be installed along the limit of work in combination with the silt sock where necessary and in areas where silt sock barriers can not be used. This control will be installed prior to major soil disturbance on the site. The sediment fence should be installed as shown on the Erosion Control Detail Plan and be Amoco woven polypropylene 1198 or equivalent. Sediment Fence Design/Installation Requirements a) Locate the fence where necessary. b) The fence line should be nearly level through most of its length to impound a broad, temporary pool. The last 10 to 20 feet at each end of the fence should be swung slightly uphill (approximately 0.5 feet in elevation) to provide storage capacity. c) Excavate a trench approximately 8 inches deep and 4 inches wide, or a V-trench; along the line of the fence, upslope side. d) Fasten support wire fence (14 gauge with 6-inch mesh) securely to the upslope side of the fence posts with wire ties or staples. Wire should extend 6 inches into the trench. e) Attach continuous length of fabric to upslope side of fence posts. Avoid joints, particularly at low points in the fence line. Where joints are necessary, fasten fabric securely to support posts and overlap to the next post. f) Place the bottom one foot of fabric in the trench. Backfill with compacted earth or gravel. g) Filter cloth shall be fastened securely to the woven wire fence with ties spaced every 24 inches at the top, mid-section, and bottom. h) Sediment fences should be removed when they have served their useful purpose, but not before the upslope area has been permanently stabilized through one growing season. Retained sediment must be removed and properly disposed of, or mulched and seeded. Sediment Fence Inspection/Maintenance a) Silt fences should be inspected immediately after each rainfall event of 1-inch or greater, and at least daily during prolonged rainfall. Inspect the depth of sediment, fabric tears, if the fabric is securely attached to the fence posts, and to see that the fence posts are firmly in the ground. Repair or replace as necessary. b) Remove sediment deposits promptly after storm events to provide adequate storage volume for the next rain and to reduce pressure on the fence. Sediment will be removed from behind the sediment fence when it becomes about ½ foot deep at the fence. Take care to avoid undermining fence during cleanout. c) If the fabric tears, decomposes, or in any way becomes ineffective, replace it immediately. d) Remove all fencing materials after the contributing drainage area has been properly stabilized. Sediment deposits remaining after the fabric has been removed should be graded to conform with the existing topography and vegetated. 3) Stabilized Construction Entrance – A stabilized construction entrance will be placed at the proposed roadway entrance off Pine Grove Road. The construction entrance will keep mud and sediment from being tracked off the construction site onto surrounding streets by vehicles leaving the site. The stabilized construction entrance will be installed prior to any major soil disturbance on site. The construction entrance will be graded to contain stormwater runoff from the entrance to prevent sediment from washing onto the adjacent ground surface. The stabilized construction entrance shall be constructed as shown on the Site Plans. Construction Entrance Installation Requirements a) Grade foundation of construction entrance with slightly concave shape to contain runoff within the entrance to prevent sediment from washing onto the adjacent ground surface. b) Stone for a stabilized construction entrance shall consist of 1 to 3-inch stone placed on a stable foundation. c) Pad dimensions: The minimum length of the gravel pad should be 50 feet. The pad should extend the full width of the proposed roadway, or wide enough so that the largest construction vehicle will fit in the entrance with room to spare; whichever is greater. d) A geotextile filter fabric shall be placed between the stone fill and the earth surface below the pad to reduce the migration of soil particles from the underlying soil into the stone and vice versa. The filter fabric should be Amoco woven polypropylene 1198 or equivalent. e) Washing: If the site conditions are such that the majority of mud is not removed from the vehicle tires by the gravel pad, then the tires should be washed before the vehicle enters the road or street. The wash area shall be located at the stabilized construction entrance. f) Water employed in the washing process shall be directed to the temporary sedimentation basin/dewatering area as shown on the plans prior to discharge. Sediment should be prevented from entering any watercourses. Construction Entrance Maintenance a) The entrance should be maintained in a condition that will prevent tracking or flowing of sediment onto Pine Grove Road. This may require periodic topdressing with additional stone b) The construction entrance and sediment disposal area shall be inspected weekly and after heavy rains or heavy use. c) Mud and sediment tracked or washed onto public road shall be immediately removed by sweeping. d) Once mud and soil particles clog the voids in the gravel and the effectiveness of the gravel pad is no longer satisfactory, the pad must be topdressed with new stone. Replacement of the entire pad may be necessary when the pad becomes completely clogged. e) If washing facilities are used, the temporary sedimentation basin/dewatering area should be cleaned out as often as necessary to assure that adequate trapping efficiency and storage volume is available. Any water pumped from the temporary sedimentation basin shall be directed into a sediment dirt bag or equivalent inlet protection prior to discharge. Discharge should not be across the disturbed construction site but rather to undisturbed areas. f) The pad shall be reshaped as needed for drainage and runoff control. g) Broken road pavement on Pine Grove Road shall be repaired immediately. h) All temporary erosion and sediment control measures shall be removed within 30 days after final site stabilization is achieved or after the temporary practices are no longer needed and only following approval by the Engineering Department or their representative. Trapped sediment shall be removed or stabilized on site. Disturbed soil areas resulting from removal shall be permanently stabilized. 4) Temporary Sediment Basin – Temporary sediment basins shall be constructed in locations as determined by the Site Contractor as necessary. The temporary sediment basins will handle storm water, filtering out sediment until the permanent stormwater drainage system is functioning properly. The temporary sediment basins will be lined with sediment erosion barrier controls. Sediment Basin Design/Installation Requirements a) Divert runoff from undisturbed areas away from basins. b) The sediment basins should have a minimum volume based on ½ inch of storage for each acre of drainage area. c) The length-to-width ratio should be 2:1 or greater; divert inflow to upper end of basin to avoid short-circuiting flow. Length is defined as the average distance from the inlet to the outlet of the trap. d) Utilize side slopes of 3:1. e) The sediment basins should be located as close to the sediment source as site conditions permit considering soils, pool area, dam length, and spillway conditions. f) Line bottom with gravel and stabilize as soon as possible. Sediment Basin and Swale Inspection/Maintenance a) The sediment basins should be readily accessible for maintenance and sediment removal. The sediment basins should remain in operation and be properly maintained until the site area is permanently stabilized by vegetation and/or when permanent structures are in place. b) Inspect the sediment basins after each significant rainfall. c) Remove and properly dispose of sediment when it accumulates to one-half design volume (level marked by reference stake). The effectiveness of a sediment pond is based less on its size than on regular sediment removal. d) Check embankment and outlet for erosion damage. e) Check embankment for: settlement, seepage, or slumping along the toe. Repair immediately. Remove trash and other debris from principal spillway and pool area. f) Clean or replace gravel when sediment pool does not drain properly. 5) Inlet Protection – Inlet Protection will be utilized around the existing catch basin grates as determined by the Site Contractor as necessary. The inlet protection will prevent any sediment from entering the street(s) and or site’s closed drainage system. Siltsack or equivalent will be utilized for the inlet protection. Siltsack is manufactured by ACF Environmental. The telephone number is 1-800-437-6746. Regular flow siltsack will be utilized, and if it does not allow enough storm water flow, hi-flow siltsack will be utilized. Silt Sack (or equivalent) Inlet Protection Maintenance Requirements a) The silt sack trapping device and the catch basin should be inspected after every rain storm and repairs made as necessary. b) Sediment should be removed from the silt sack after the sediment has reached a maximum depth of one-half the depth of the trap. c) Sediment should be disposed of in a suitable area and protected from erosion by either structural or vegetative means. Sediment material removed shall be disposed of in accordance with all applicable local, state, and federal regulations. d) The silt sack must be replaced if it is ripped or torn in any way. e) Temporary traps should be removed and the area repaired as soon as the contributing drainage area to the inlet has been completely stabilized. Stabilization Practices: Stabilization measures shall be implemented as soon as practicable in portions of the site where construction activities have temporarily or permanently ceased, but in no case more than 14 days after the construction activity in that portion of the site has temporarily or permanently ceased, with the following exceptions. • Where the initiation of stabilization measures by the 14th day after construction activity temporary or permanently cease is precluded by snow cover, stabilization measures shall be initiated as soon as practicable. • Where construction activity will resume on a portion of the site within 21 days from when activities ceased, then stabilization measures do not have to be initiated on that portion of the site by the 14th day after construction activity temporarily ceased. 1) Temporary Seeding – Temporary seeding will allow a short-term vegetative cover on disturbed site areas that may be in danger of erosion. Temporary seeding will be done at stock piles and disturbed portions of the site where construction activity will temporarily cease for at least 21 days. The temporary seedings will stabilize cleared and unvegetated areas that will not be brought into final grade for several weeks or months. Temporary Seeding Planting Procedures a) Planting should preferably be done between April 1st and June 30th, and September 1st through September 31st. If planting is done in the months of July and August, irrigation may be required. If planting is done between October 1st and March 31st, mulching should be applied immediately after planting. If seeding is done during the summer months, irrigation of some sort will probably be necessary. b) Before seeding, install structural practice controls. Utilize Amoco supergro or equivalent. c) The seedbed should be firm with a fairly fine surface. Perform all cultural operations across or at right angles to the slope. A minimum of 2 to 4-inches of tilled topsoil is required. The topsoil must have a sandy loam to silt loam texture with 15% to 20% organic content. d) Apply uniformly 2 tons of ground limestone per acre (100 lbs. Per 1,000 sq.ft.) or according to soil test. Apply uniformly 10-10-10 analysis fertilizer at the rate of 400 lbs. per acre (14 lbs. per 1,000 sq.ft.) or as indicated by soil test. Forty percent of the nitrogen should be in organic form. Work in lime and fertilizer to a depth of 4-inches using any suitable equipment. e) Select the appropriate seed species for temporary cover from the following table. Species Seeding Rate (lbs/1,000 sq.ft.) Seeding Rate (lbs/acre) Recommended Seeding Dates Seed Cover required Annual Ryegrass 1 40 April 1st to June 1st August 15th to Sept. 15th ¼ inch Foxtail Millet 0.7 30 May 1st to June 30th ½ to ¾ inch Oats 2 80 April 1st to July 1st August 15th to Sept. 15th 1 to 1-½ inch Winter Rye 3 120 August 15th to Oct. 15th 1 to 1-½ inch f) Apply the seed uniformly by hydroseeding, broadcasting, or by hand. g) Use effective mulch, such as clean grain straw; tacked and/or tied with netting to protect seedbed and encourage plant growth. Temporary Seeding Maintenance a) Inspect within 6 weeks of planting to see if stands are adequate. Check for damage within 24 hours of the end to a heavy rainfall, defined as a 2-year storm event (i.e., 3.35 inches of rainfall within a twenty-four hour period). Stands should be uniform and dense. Reseed and mulch damaged and sparse areas immediately. Tack or tie down mulch as necessary. b) Seeds should be supplied with adequate moisture. Furnish water as needed, especially in abnormally hot or dry weather. Water application rates should be controlled to prevent runoff. 2) Geotextiles - Geotextiles such as jute netting will be used in combination with other practices such as mulching to stabilize slopes. The following geotextile materials or equivalent are to be utilized for structural and nonstructural controls as shown in the following table. Practice Manufacturer Product Remarks Sediment Fence Amoco Woven polypropylene 1198 or equivalent 0.425 mm opening Construction Entrance Amoco Woven polypropylene 2002 or equivalent 0.300 mm opening Outlet Protection Amoco Nonwoven polypropylene 4551 or equivalent 0.150 mm opening Erosion Control (slope stability) Amoco Supergro or equivalent Erosion control revegetation mix, open polypropylene fiber on degradable polypropylene net scrim Amoco may be reached at (800) 445-7732 Geotextile Installation a) Netting and matting require firm, continuous contact between the materials and the soil. If there is no contact, the material will not hold the soil and erosion will occur underneath the material. Geotextile Maintenance a) In the field, regular inspections should be made to check for cracks, tears, or breaches in the fabric. The appropriate repairs should be made. 3) Mulching and Netting – Mulching will provide immediate protection to exposed soils during the period of short construction delays, or over winter months through the application of plant residues, or other suitable materials, to exposed soil areas. In areas, which have been seeded either for temporary or permanent cover, mulching should immediately follow seeding. On steep slopes, mulch must be supplemented with netting. The preferred mulching material is straw. Mulch (Straw) Installation a) Straw has been found to be one of the most effective organic mulch materials. The specifications for straw are described below, but other material may be appropriate. The straw should be air-dried; free of undesirable seeds & coarse materials. The application rate per 1,000 sq.ft. is 90-100 lbs. (2-3 bales) and the application rate per acre is 2 tons (100-120 bales). The application should cover about 90% of the surface. The use of straw mulch is appropriate where mulch is maintained for more than three months. Straw mulch is subject to wind blowing unless anchored, is the most commonly used mulching material, and has the best microenvironment for germinating seeds. Mulch Maintenance a) Inspect after rainstorms to check for movement of mulch or erosion. If washout, breakage, or erosion occurs, repair surface, reseed, remulch, and install new netting. b) Straw or grass mulches that blow or wash away should be repaired promptly. c) If plastic netting is used to anchor mulch, care should be taken during initial mowings to keep the mower height high. Otherwise, the netting can wrap up on the mower blade shafts. After a period of time, the netting degrades and becomes less of a problem. d) Continue inspections until vegetation is well established. 4) Land Grading – Grading on fill slopes, cut slopes, and stockpile areas will be done with full siltation controls in place. Land Grading Requirements a) Areas to be graded should be cleared and grubbed of all timber, logs, brush, rubbish, and vegetated matter that will interfere with the grading operation. Topsoil should be stripped and stockpiled for use on critical disturbed areas for establishment of vegetation. Cut slopes to be topsoiled should be thoroughly scarified to a minimum depth of 3-inches prior to placement of topsoil. b) Fill materials should be generally free of brush, rubbish, rocks, and stumps. Frozen materials or soft and easily compressible materials should not be used in fills intended to support buildings, parking lots, roads, conduits, or other structures. c) Earth fill intended to support structural measures should be compacted to a minimum of 90 percent of Standard Proctor Test density with proper moisture control, or as otherwise specified by the engineer responsible for the design. Compaction of other fills should be to the density required to control sloughing, erosion or excessive moisture content. Maximum thickness of fill layers prior to compaction should not exceed 9 inches. d) The uppermost one foot of fill slopes should be compacted to at least 85 percent of the maximum unit weight (based on the modified AASHTO compaction test). This is usually accomplished by running heavy equipment over the fill. e) Fill should consist of material from borrow areas and excess cut will be stockpiled in areas shown on the Site Plans. All disturbed areas should be free draining, left with a neat and finished appearance, and should be protected from erosion. Land Grading Stabilization Maintenance a) All slopes should be checked periodically to see that vegetation is in good condition. Any rills or damage from erosion and animal burrowing should be repaired immediately to avoid further damage. b) If seeps develop on the slopes, the area should be evaluated to determine if the seep will cause an unstable condition. Subsurface drains or a gravel mulch may be required to solve seep problems. However, no seeps are anticipated. c) Areas requiring revegetation should be repaired immediately. Control undesirable vegetation such as weeds and woody growth to avoid bank stability problems in the future. 5) Topsoiling – Topsoiling will help establish vegetation on all disturbed areas throughout the site during the seeding process. The soil texture of the topsoil to be used will be a sandy loam to a silt loam texture with 15% to 20% organic content. Topsoiling Placement a) Topsoil should not be placed while in a frozen or muddy condition, when the subgrade is excessively wet, or when conditions exist that may otherwise be detrimental to proper grading or proposed seeding. b) Do not place topsoil on slopes steeper than 2.5:1, as it will tend to erode. c) If topsoil and subsoil are not properly bonded, water will not infiltrate the soil profile evenly and it will be difficult to establish vegetation. The best method is to actually work the topsoil into the layer below for a depth of at least 6 inches. 6) Permanent Seeding – Permanent Seeding should be done immediately after the final design grades are achieved. Native species of plants should be used to establish perennial vegetative cover on disturbed areas. The revegetation should be done early enough in the fall so that a good cover is established before cold weather comes and growth stops until the spring. A good cover is defined as vegetation covering 75 percent or more of the ground surface. Permanent Seeding Seedbed Preparation a) In infertile or coarse-textured subsoil, it is best to stockpile topsoil and re-spread it over the finished slope at a minimum 2 to 6-inch depth and roll it to provide a firm seedbed. The topsoil must have a sandy loam to silt loam texture with 15% to 20% organic content. If construction fill operations have left soil exposed with a loose, rough, or irregular surface, smooth with blade and roll. b) Loosen the soil to a depth of 3-5 inches with suitable agricultural or construction equipment. c) Areas not to receive topsoil shall be treated to firm the seedbed after incorporation of the lime and fertilizer so that it is depressed no more than ½ - 1 inch when stepped on with a shoe. Areas to receive topsoil shall not be firmed until after topsoiling and lime and fertilizer is applied and incorporated, at which time it shall be treated to firm the seedbed as described above. Permanent Seeding Grass Selection/Application a) Select an appropriate cool or warm season grass based on site conditions and seeding date. Apply the seed uniformly by hydro-seeding, broadcasting, or by hand. Uniform seed distribution is essential. On steep slopes, hydroseeding may be the most effective seeding method. Surface roughening is particularly important when preparing slopes for hydroseeding. b) Lime and fertilize. Organic fertilizer shall be utilized in areas within the 100 foot buffer zone to a wetland resource area. c) Mulch the seedings with straw applied at the rate of ½ tons per acre. Anchor the mulch with erosion control netting or fabric on sloping areas. Amoco supergro or equivalent should be utilized. Permanent Seeding Inspection/Maintenance a) Frequently inspect seeded areas for failure and make necessary repairs and reseed immediately. Conduct or follow-up survey after one year and replace failed plants where necessary. b) If vegetative cover is inadequate to prevent rill erosion, overseed and fertilize in accordance with soil test results. c) If a stand has less than 40% cover, reevaluate choice of plant materials and quantities of lime and fertilizer. Re-establish the stand following seedbed preparation and seeding recommendations, omitting lime and fertilizer in the absence of soil test results. If the season prevents resowing, mulch or jute netting is an effective temporary cover. d) Seeded areas should be fertilized during the second growing season. Lime and fertilize thereafter at periodic intervals, as needed. Organic fertilizer shall be utilized in areas within the 100-foot buffer zone to a wetland resource area. Dust Control: Dust control will be utilized throughout the entire construction process of the site. For example, keeping disturbed surfaces moist during windy periods will be an effective control measure, especially along vehicle circulation paths. The use of dust control will prevent the movement of soil to offsite areas. However, care must be taken to not create runoff from excessive use of water to control dust. The following are methods of dust control that may be used on-site: • Vegetative Cover – The most practical method for disturbed areas not subject to traffic. • Calcium Chloride – Calcium chloride may be applied by mechanical spreader as loose, dry granules or flakes at a rate that keeps the surface moist but not so high as to cause water pollution or plant damage. • Sprinkling – The site may be sprinkled until the surface is wet. Sprinkling will be effective for dust control on haul roads and other traffic routes. • Stone – Stone will be used to stabilize construction roads; will also be effective for dust control. The general contractor shall employ an on-site water vehicle for the control of dust as necessary. Non-Stormwater Discharges: The construction de-watering and all non-stormwater discharges will be directed into a sediment dirt bag (or equivalent inlet protection) or a sediment basin. Sediment material removed shall be disposed of in accordance with all applicable local, state, and federal regulations. The developer and site general contractor will comply with the E.P.A.’s Final General Permit for Construction De-watering Discharges, (N.P.D.E.S., Section 402 and 40 C.F.R. 122.26(b)(14)(x). Soil Stockpiling: Topsoil and subsoil from the roadway grading will be stockpiled in locations shown on the plans. Stockpile Material Construction Procedure 1) Topsoil and subsoil that are stripped will be stockpiled for later distribution on disturbed areas. 2) The stockpiles will be located as shown on the plans. These locations will allow them to not interfere with work on the site. 3) Seed the stockpiles with a temporary erosion control mix if the stockpile is to remain undisturbed for more than 30 days. The stockpiles must be stable and the side slopes should not exceed 2:1. 4) Sediment erosion control measures should be placed surrounding each stockpile. 5) As needed, the stockpiled topsoil and subsoil are redistributed throughout the site. Pollution Prevention: Spill Prevention and Response: The site supervisor or their representative shall be present on the job site at all times during the course of work and shall be present during the delivery, removal of any liquid/chemical materials to or from the job site. They will also be present during any refueling practices. All subcontractors will be notified of their responsibilities in writing. In the event a spill occurs, the site supervisor shall be notified immediately. The site supervisor shall have in place a spill prevention plan and resources to contain and clean up any potential spills in a timely manner. Refer to the attached Spill Containment & Management Plan, including Spill Report, Emergency Response Equipment Inventory, and Emergency Notification and phone numbers. Fueling and Maintenance of Equipment or Vehicles: The site supervisor shall produce a written document received by all subcontractors and employees that delineates their responsibilities on site. This document shall include language that shall permit the maintenance of vehicles only in designated locations on the job site. The site supervisor shall document receipt of these instructions by obtaining the signatures of subcontractors and individuals that may enter the site and the date in which they were notified of their responsibilities. Several types of vehicles and equipment will be used on-site throughout the project, including graders, scrapers, excavators, loaders, paving equipment, rollers, trucks and trailers, backhoes, and forklifts. Vehicles requiring refueling or lubrication shall be brought to a designated portion of the site away from environmentally sensitive areas (such as storm drains, steep slopes, etc.) or shall utilize temporary drip protection measures at the location of fueling. The operator shall take precautions to ensure that drips, spills or seeps do not enter the ground. The use of absorbent towels beneath the fuel tank is recommended. Absorbent, spill cleanup materials and spill kits should be kept on site. Refueling or maintenance of equipment in locations other than those designated for such activity shall be performed under the supervision of the site supervisor or his/her designee. The site supervisor shall have a fuel spill plan and measures on site to initiate containment and clean-up in the event a fuel spill occurs. 1. Fueling operations shall take place in designated area(s) as shown on site maps. Provide temporary drip protection during fueling operations which take place outside of designated area(s). Materials necessary to address a spill shall be made readily available in a location known to the site supervisor or his/her designee. 2. Fueling operation procedures shall be in effect throughout the project duration. Maintenance Requirements - 1. Vehicles and equipment will be inspected on each day of use. Leaks will be repaired immediately, or the problem vehicle or equipment will be removed from the project site. 2. All emergency response equipment listed in the Emergency Response Equipment Inventory shall be made readily available and kept in a designated location known to the site supervisor or his/her designee. All such materials shall be replenished as necessary to the listed amounts. Washing of Equipment and Vehicles: The site supervisor shall produce a written document received by all subcontractors and employees that delineates their responsibilities on site. The site supervisor shall document receipt of these instructions by obtaining the signatures of subcontractors and individuals that may enter the site and the date in which they were notified of their responsibilities. This document shall include language that shall not permit vehicle washing on the job site. Concrete trucks shall be exempt from this rule. Concrete truck cleaning shall be confined within the work area and conducted in a manner to prevent water drainage beyond the specified area of work. Concrete truck washout shall be conducted in designated areas only and shall not be discharged in areas which would allow wash water to leave the site or enter protected areas. Maintenance Requirements - 1. The site supervisor shall maintain a log of individuals receiving these instructions. Storage, Handling, and Disposal of Construction Products, Materials, and Wastes: Building products stored on site shall be kept in designated materials storage areas as shown on the site map(s). Storage areas shall properly contain materials and prevent materials or their containers/wrappers from being strewn about the site. Any leaking containers shall be removed and properly disposed of immediately. Weather sensitive materials shall be safely stored in closed temporary containers as necessary. 1. Place all materials being stored for future use in designated storage areas. 2. Place all weather sensitive materials in closed temporary containers as necessary. Care should be taken to store materials in accordance with manufacturer’s recommendations and to avoid storing combinations of materials which may cause a noxious, volatile or otherwise dangerous condition. 3. All non-hazardous solid waste shall be disposed of in a trash receptacle (dumpster) which shall be removed and disposed of at an approved land fill. Maintenance Requirements - 1. The site supervisor shall inspect the designated storage areas weekly and after storm events as well as any portions of the site under construction to ensure that all materials are properly stored. The storage areas will be kept clean, well-organized, and equipped with ample cleanup supplies as appropriate for the materials being stored. Pesticides, Herbicides, Insecticides, Fertilizers, and Landscape Materials The use of pesticides and herbicides is not currently anticipated for this site. Fertilizers and landscape materials will be used to stabilize slopes and other disturbed areas. 1. Store all fertilizers and landscape materials in designated secure locations. Store all weather sensitive materials in closed containers in accordance with manufacturer’s recommendations. Maintenance Requirements 1. The site supervisor shall inspect the designated storage areas weekly as well as any portions of the site under construction to ensure that all materials are properly stored. Storage issues shall be immediately addressed. Diesel Fuel, Oil, Hydraulic Fluids, Other Petroleum Products, and Other Chemicals Storage of diesel fuel, oil hydraulic fluids and other petroleum products/chemicals shall be in a secure area protected from the outside elements. Refueling and maintenance for vehicles or equipment shall occur either within the designated area or shall utilize temporary drip protection measures at the location of fueling. The site supervisor shall have a fuel spill plan and measures on site to initiate containment and clean-up in the event a fuel spill occurs. Refueling or maintenance of equipment in locations other than those designated for such activity shall be performed under the supervision of the site supervisor or his/her designee and shall employ drip pans or other suitable means of preventing fuel, hydraulic fluid, etc. from spilling or being otherwise carried offsite or into protected areas. Hazardous or Toxic Waste (Note: Examples include paints, solvents, petroleum-based products, wood preservatives, additives, curing compounds, acids.) Hazardous or toxic waste associated with paints, solvents, petroleum-based products, wood preservatives, additives, curing compounds, acids shall be stored in sealed containers to prevent leakage and corrosion, and which are labeled in accordance with applicable Resource Conservation and Recovery Act (RCRA) and all other applicable federal, state and local requirements. Hazardous or toxic waste shall be collected in approved containers and disposed of in accordance with municipal, state and federal regulations. Hazardous and toxic waste shall not be disposed of in solid waste containers intended for non- hazardous construction debris. Maintenance Requirements 1. The site supervisor shall inspect all portions of the project under construction weekly and after storm events to ensure that all hazardous or toxic materials are stored and disposed of in accordance with the practices detailed above and shall immediately correct any improper storage or disposal practices. Construction and Domestic Waste: (Note: Examples include packaging materials, scrap construction materials, masonry products, timber, pipe and electrical cuttings, plastics, styrofoam, concrete, and other trash or building materials.) All construction and domestic waste shall be collected and disposed of into dumpsters. Dumpsters will be placed away from stormwater conveyances and drains, and meet all federal, state, and municipal regulations. Only trash and construction debris from the site will be deposited in the dumpster. No construction materials will be buried on-site. Any overflow from containers/dumpsters shall be cleaned up immediately. All personnel will be instructed regarding the correct disposal of trash and construction debris. Notices that state these practices will be posted in the job site trailer and the individual who manages day-to-day operations will be responsible for seeing that these practices are followed. Recyclable waste material shall be stored in an appropriate container or in a designated location on site until it can be removed. 1. Dumpsters and recyclable waste material containers shall be located as needed throughout the site. Maintenance Requirements 1. The site supervisor shall inspect all dumpsters and containers to confirm that construction and domestic waste is properly contained and shall also ascertain that waste is being picked up in a timely manner to ensure that no receptacles are overflowing. Pick-up schedules shall be modified, or the number of receptacles shall be increased as needed. Sanitary Waste Sanitary facilities (portable toilets) will be provided at the site throughout the construction phase. The portable toilets will be located away from a concentrated flow paths or traffic flow. Sanitary facilities will be brought to the site at the start of construction. Maintenance Requirements 1. If necessary, the site supervisor shall execute a contract with a vendor to supply and maintain portable toilets throughout the site for the project duration. The portable toilets shall be inspected weekly for evidence of leaking holding tanks. Toilets with leaking holding tanks will be removed from the site and replaced with new portable toilets. The site supervisor shall determine if a sufficient number of toilets are present to meet staffing levels and shall ensure that the toilets are regularly and properly maintained. Washing of Applicators and Containers used for Paint, Concrete or Other Materials Concrete washout shall be restricted to designated areas only. Paints, form release oils, curing compounds, etc. shall be recycled and/or disposed of utilizing appropriate containers in accordance with manufacturer’s recommendations and EPA guidelines. 1. Direct all wash water into a leak-proof container or leak-proof pit at the appropriate designated location. The washout location shall be designated before concrete pours commence. The container or pit must be designed so that no overflow can occur due to inadequate sizing or precipitation. Concrete trucks shall wash out only at washout pit or container such as a portable roll-off washout pit. 2. Signs will be posted marking the location of the washout area to ensure that the concrete and other equipment operators use the proper facility. Concrete pours or other material application will not be conducted during or before an anticipated storm event. 3. Provide suitable containers for recycling or disposal for cleanup of paints, form release oils, curing compounds, etc. Maintenance Requirements 1. The site supervisor shall inspect concrete washout pits (or other acceptable facility) daily to ensure that they are properly maintained. Washout pits shall be cleaned out when the area is filled to 75% of holding capacity. If necessary, wash water in a washout pit shall be vacuumed off and the hardened concrete broken up and recycled. Wash water and broken up concrete shall be properly disposed of at a suitable facility. If necessary, the washout pit shall be repaired and relined with plastic prior to continued use. 2. Containers for waste paint, form release oil, curing compounds, etc. shall be sealed and removed from the site and properly disposed of at a suitable facility. Empty containers shall replace those being removed for disposal. Fertilizers Fertilizers shall be used only as necessary to establish vegetative stabilized slopes and disturbed areas. Apply at recommended rates. Use only slow-release fertilizers to minimize discharge of nitrogen or phosphorous. 1. Store all fertilizers in designated locations. Store all weather sensitive materials in closed containers in accordance with manufacturer’s recommendations. 2. To prevent accidental release of fertilizers, the site supervisor shall attempt to coordinate delivery of fertilizers to coincide with application and reduce the need to warehouse large quantities on-site. 3. Avoid applying before heavy rains that could cause excess nutrients to be discharged. 4. Never apply to frozen ground or apply to stormwater conveyance channels with flowing water. 5. Follow all other federal, state, and local requirements regarding fertilizer applications. Maintenance Requirements 1. Site supervisor shall make regular inspections to ensure that fertilizer is being applied at proper rates and that all perimeter controls are in place and properly maintained to control runoff which may contain fertilizer. Inspection and Corrective Action: Operator personnel must inspect the construction site at least once every 7 calendar days and within 24 hours of a storm event of ½-inch or greater. The owner shall be responsible to secure the services of a design professional or similar “qualified person” (inspector) on an on-going basis throughout all phases of the project. The inspector should review the erosion and sediment controls with respect to the following: • Whether or not the measure was installed/performed correctly. • Whether or not there has been damage to the measure or ineffective controls since it was installed or performed. • What corrective actions should be done to correct any problems with the measure. The inspector should complete the Stormwater Management Best Management Practices Inspection Schedule and Evaluation Checklist – Construction Phase, as attached or provided in the Site’s Stormwater Pollution Prevention Plan, for documenting the findings and should request the required maintenance or repair for the pollution prevention measures when the inspector finds that it is necessary for the measure to be effective. The inspector should notify the appropriate person to make the changes. It is essential that the inspector documents the inspection of the pollution prevention measures. These records will be used to request maintenance and repair and to prove that the inspection and maintenance were performed. STORMWATER MANAGEMENT BEST MANAGEMENT PRACTICES INSPECTION SCHEDULE AND EVALUATION CHECKLIST – CONSTRUCTION PHASE Project Location: 897 Main Street, Yarmouth MA Latest revision: ________ Best Management Practice Inspection Frequency (1) Date Inspected Inspector Minimum Maintenance and Key Items to Check Cleaning/ Repair Needed yes/no List Items Date of Cleaning/ Repair Performed By Water Level in System Silt Sock Erosion Control Barrier Weekly or after every major storm event – minimum weekly Check sediment levels and remove when reaches ¼ to ½ the height of sock Silt Fence Erosion Control Barrier Weekly or after every major storm event – minimum weekly Check sediment levels and remove when reaches ½ foot in height along fence Stabilized Construction Entrance Weekly or after every major storm event – minimum weekly Check sediment levels in stone Temporary Sedimentation Basin Weekly or after every major storm event – minimum weekly Check sediment levels and remove when reaches ½ the design volume Inlet Protection Weekly or after every major storm event – minimum weekly Check silt sack for sediment levels, tears or any damage Stockpiles Weekly or after every major storm event – minimum weekly Ensure surrounding erosion control measures are intact Temp/ Prop Seeding for Stabilization Weekly or after every major storm event – minimum weekly Geotextiles/ mulching & Netting Weekly or after every major storm event – minimum weekly Dust Control Weekly (1) Refer to the Massachusetts Stormwater Management, Volume Two: Stormwater Technical Handbook (current) for recommendations regarding frequency for inspection and maintenance of specific BMPs. (2) Limited or no use of sodium chloride salts, fertilizers or pesticides recommended. Slow release fertilizer recommended. Stormwater Control Manager: Stamp LONG TERM SOURCE CONTROL/POLLUTION PREVENTION PLAN AND OPERATION AND MAINTENANCE PLAN Dated: July 24, 2025 Residential Development 897 Main Street (Route 28) S. Yarmouth, MA Responsible Party for Operation and Maintenance Contact Information: ACRE+ WCI Real Estate Ventures 1, LLC 897 Main Street (Route 28) South Yarmouth, MA P: 610-737-7625 Best Management Practices (BMPs) of the Commonwealth of Massachusetts Department of Environmental Protection’s (DEP’s) Stormwater Management Policy (SMP) have been implemented and utilized for the project. The following information provided is to be used as a guideline for monitoring and maintaining the performance of the drainage facilities and to ensure that the quality of water runoff meets the standards set forth by the SMP. The structural Best Management Practices (BMPs) shall be inspected during rainfall conditions during the first year of operation to verify functionality. General Conditions 1. The BMP’s will be owned and maintained by the Developer until such time that a Homeowner's Association is created, then the Homeowner's Association will own and maintain the BMP’s located on the site. 2. All Stormwater BMP’s shall be operated and maintained in accordance with the design plans and the following Long-Term Operations and Maintenance Plan. 3. The Responsible Party shall: a. Maintain an Operation and Maintenance Log (see Attachment A). The Log shall include all BMP inspections, repairs, replacement activities and disposal activities (disposal material and disposal location shall be included in the Log); b. Retain inspection and maintenance logs for a period of three years, on an ongoing basis; c. Make the logs available to the Town upon request; d. Allow members and agents of the Yarmouth DPW to enter the premises and ensure that the Responsible Party has complied with the Operation and Maintenance Plan requirements for each BMP. 4. An inspection and maintenance schedule should be adhered to at a minimum for the first year of service of all BMP’s referenced in this document. After the first year of service, a more accurate inspection/maintenance schedule should be determined based on the level of service for this site. Operation and Maintenance 1. Requirements for Routine Inspections and Maintenance of Stormwater Best Management Practices Note: The Town shall be notified immediately if a change in ownership or maintenance responsibility occurs at the site. Drain lines After construction, the drainlines shall be inspected after every major storm for the first few months to ensure proper functions. The presence of accumulated sand and silt would indicate more frequent maintenance of the pre-treatment devices is required. Thereafter, the drainlines shall be inspected at least once per year. Deep sump and hooded Catch Basins Catch basin grates shall be checked quarterly and following heavy rainfalls to verify that the inlet openings are not clogged by debris. Debris shall be removed from the grates and disposed of properly. Deep sump catch basins shall be inspected and cleaned bi-annually of all accumulated sediments. Catch basins with hoods shall be inspected annually to check oil build-up and outlet obstructions. Material shall be removed from catch basins and disposed of in accordance with all applicable regulations. Pre-treatment Structures – First Defense Units The proprietary pretreatment unit shall be inspected and maintained from the surface, without entry into the unit quarterly and following heavy rain events defined as a storm event exceeding one inch of rainfall within a twenty-four hour period to verify that the inlet opening is not clogged by debris. During the first year of installation, perform inspections regularly, so an accurate maintenance schedule can be established. Perform oil and floatables removal once per year and immediately in the event of a spill. Oil shall be removed by using a small portable pump and disposed of properly. Perform sediment removal once per year or as needed and following a spill event. Sediment shall be removed from the unit using a vacuum truck. The requirements for the disposal from the unit should be in compliance with all local, state and federal regulations. Please refer to the attached manufacturer's maintenance manual for additional detail on proper inspection and maintenance of the First Defense unit. Subsurface Infiltration Chamber Systems Proper maintenance of the subsurface infiltration systems is essential to the long-term effectiveness of the infiltration function. After construction, the subsurface infiltration chamber systems shall be inspected for proper function after every major storm event until the site is completely developed and stabilized. After the site has been stabilized, the subsurface infiltration chamber systems shall be inspected at least twice per year or if lack of performance is observed and perform necessary corrective measures to maintain infiltration capacity; as required by the Stormwater Management Policy. The systems shall have inspection ports for proper inspections. Inspections shall include checking the water level in the system after a major storm event, and performing necessary corrective action if water is observed 72 hours following the storm. The owner shall retain a qualified stormwater professional to assess the cause of this condition and develop a corrective action plan for restoring the infiltration function. The owner shall immediately implement the corrective action to restore the infiltration function. Documentation of these actions shall be maintained in the inspection and maintenance records. Inspection & Maintenance Steps Accumulated sediment must be removed from the bottom of the chambers. Material removed from the systems shall be disposed of in accordance with all applicable local, state, and federal regulations. Step 1. Inspect chamber rows for sediment and water levels • Inspection Ports a. Remove/open lid on nyloplast inspection port b. Remove and clean flexstorm filter if installed c. Using a flashlight and stadia rod, measure depth of sediment or water level and record on maintenance log d. Lower camera into chamber row for visual inspection of sediment or water levels (optional) e. If water is observed 72 hours following a storm event, proceed to Step 3. If not, proceed to Step 4 • Clean out locations a. Remove clean out cover b. Using a flashlight, inspect down the chamber row through the manifold pipe c. If sediment is at, or above 3” at inlet chambers, proceed to Step 2. If not, proceed to Step 4. Step 2. Clean out inlet chambers (first 12.5 ft. only) using the jetvac process if sediment build up is observed a. A fixed culvert cleaning nozzle with rear facing spread of 45” or more is preferred b. Apply multiple passes of jetvac until backflush water is clean c. Vacuum structure sump as required Step 3. Repair chamber system when water levels do not infiltrate after 72 hours. A corrective action plan shall be prepared by a qualified stormwater professional and immediately implemented. Step 4. Replace all covers, grates, filters, and lids; record observations and actions. Step 5. Inspect and clean basins and manholes upstream of the chamber system. Please refer to the attached manufacturer's maintenance manual for additional detail on proper inspection and maintenance of the StormTech chamber systems. Driveway Pavement Maintenance Vacuum sweepers shall sweep the driveway and parking area periodically during dry weather to remove excess sediments to reduce the amount of sediments that the drainage system shall have to remove from the runoff. The sweeping should be conducted four times per year and will be the responsibility of the property owner. Salt used for de-icing on the roadway during winter months should be limited as much as possible as this will reduce the need for removal and treatment. Sand containing the minimum amount of calcium chloride (or approved equivalent) needed for handling may be applied as part of the routine winter maintenance activities. 2. Inspections The responsible party shall secure the services of a Licensed Engineer or similar professional (inspector) on an on-going basis. The inspector shall review the project with respect to the following: • Proper installation and performance of the Stormwater Management System. • Review of the controls to determine any damaged or ineffective controls. • Corrective actions. The inspector shall prepare a report documenting the findings and should request the required maintenance or repair for the pollution prevention controls when the inspector finds that it is necessary for the control to be effective. If hydrocarbons or any petroleum products are detected in any stormwater structure during an inspection, immediate measures shall be taken to remove and dispose of the material in accordance with all applicable regulations. The inspector shall notify the Owner to make the changes. The owner shall be responsible for retaining the inspection and maintenance records for a period of three years, on an ongoing basis. For additional information, refer to Performance, Standards and Guidelines for Stormwater Management in Massachusetts, published by the Department of Environmental Protection. Pollution Prevention Plan Good Housekeeping To develop and implement an operation and maintenance program with the goal of preventing or reducing pollutant runoff by keeping potential pollutants from coming into contact with stormwater or being transported off site without treatment, the following efforts will be made: • Property Management awareness and training on how to incorporate pollution prevention techniques into maintenance operations. • Follow appropriate best management practices (BMPs) by proper maintenance and inspection procedures. • Homeowner education outreach, including promoting recycling through the Town of Yarmouth. 1.0 Storage and Disposal of Household Waste and Toxics This management measure involves educating the general public on the management considerations for hazardous materials. Failure to properly store hazardous materials dramatically increases the probability that they will end up in local waterways. Many people have hazardous chemicals stored throughout their homes, especially in garages and storage sheds. Practices such as covering hazardous materials or even storing them properly, can have dramatic impacts. Property owners are encouraged to support the household hazardous product collection events sponsored by the Town of Yarmouth. MADEP has prepared several materials for homeowners on how to properly use and dispose of household hazardous materials: http://www.mass.gov/dep/recycle/reduce/househol.htm For consumer questions on household hazardous waste call the following number: DEP Household Hazardous Waste Hotline 800-343-3420 The following is a list of management considerations for hazardous materials as outlined by the EPA: • Ensuring sufficient aisle space to provide access for inspections and to improve the ease of material transport; • Storing materials well away from high-traffic areas to reduce the likelihood of accidents that might cause spills or damage to drums, bags, or containers. • Stacking containers in accordance with the manufacturers' directions to avoid damaging the container or the product itself; • Storing containers on pallets or equivalent structures. This facilitates inspection for leaks and prevents the containers from coming into contact with wet floors, which can cause corrosion. This consideration also reduces the incidence of damage by pests. The following is a list of commonly used hazardous materials used in the household: Batteries – automotive and rechargeable ............nickel cadmium batteries ............(no alkaline batteries) Gasoline Oil-based paints Fluorescent light bulbs and lamps Pool chemicals Propane tanks Lawn chemicals, fertilizers and weed killers Turpentine Bug sprays Antifreeze Paint thinners, strippers, varnishes and Disinfectant Drain clog dissolvers Driveway sealer Flea dips, sprays and collars Houseplant insecticides Metal polishes Mothballs Motor oil and filters Muriatic acid (concrete cleaner) Nail polishes and nail polish removers Oven cleaner Household pest and rat poisons Rug and upholstery cleaners .......stains Arts and crafts chemicals Charcoal lighter fluid Shoe polish Windshield wiper fluid 2.0 Vehicle Washing This management measure involves educating the general public on the water quality impacts of the outdoor washing of automobiles and how to avoid allowing polluted runoff to enter the storm drain system. Outdoor car washing has the potential to result in high loads of nutrients, metals, and hydrocarbons during dry weather conditions in many watersheds, as the detergent-rich water used to wash the grime off our cars flows down the street and into the storm drain. The following management practices will be encouraged: • Washing cars on gravel, grass, or other permeable surfaces. • Blocking off the storm drain during car washing and redirecting wash water onto grass or landscaping to provide filtration. • Using hoses with nozzles that automatically turn off when left unattended. • Using only biodegradable soaps. • Minimize the amounts of soap and water used. Wash cars less frequently. • Promote use of commercial car wash services. 3.0 Landscape Maintenance This management measure seeks to control the storm water impacts of landscaping and lawn care practices through education and outreach on methods that reduce nutrient loadings and the amount of storm water runoff generated from lawns. Nutrient loads generated by fertilizer use on suburban lawns can be significant, and recent research has shown that lawns produce more surface runoff than previously thought. Using proper landscaping techniques can effectively increase the value of a property while benefiting the environment. These practices can benefit the environment by reducing water use; decreasing energy use (because less water pumping and treatment is required); minimizing runoff of storm and irrigation water that transports soils, fertilizers, and pesticides; and creating additional habitat for plants and wildlife. The following lawn and landscaping management practices will be encouraged: • Mow lawns at the highest recommended height. • Minimize lawn size and maintain existing native vegetation. • Collect rainwater for landscaping/gardening needs (rain barrels and cisterns to capture roof runoff). • Raise public awareness for promoting water efficient maintenance practices by informing users of water efficient irrigation techniques and other innovative approaches to water conservation. • Abide by water restrictions and other conservation measures implemented by the Town of Yarmouth. • Water only when necessary. • Use automatic irrigation systems to reduce water use if necessary. 4.0 Integrated Pest Management (IPM) This management measure seeks to limit the adverse impacts of insecticides and herbicides by providing information on alternative pest control techniques other than chemicals or explaining how to determine the correct dosages needed to manage pests. The presence of pesticides in stormwater runoff has a direct impact on the health of aquatic organisms and can present a threat to humans through contamination of drinking water supplies. The pesticides of greatest concern are insecticides, such as diazinon and chlorpyrifos, which even at very low levels can be harmful to aquatic life. The major source of pesticides to urban steams is application of products designed to kill insects and weeds in landscape areas. The following IPM practices will be encouraged: • Pesticides and herbicides shall be used sparingly. Fertilizers should be restricted to the use of organic fertilizers only. • Lawn care and landscaping management programs including appropriate pesticide use management as part of program. 5.0 Pet Waste Management Pet waste management involves using a combination of pet waste collection programs, pet awareness and education, to alert residents to the proper disposal techniques for pet droppings. The following management practices will be encouraged: • Raise awareness of homeowners that are also pet owners that they are encouraged to pick up after their pets and dispose of the waste either in the trash, including on their own lawns. 6.0 Proper Management of Deicing Chemicals and Snow The following deicing chemicals and snow storage practices will be encouraged: • Select effective snow disposal sites adjacent to or on pervious surfaces in upland areas away from water resources and wells. At these locations, the snow meltwater can filter into the soil, leaving behind sand and debris, which can be removed in the springtime. • No roadway deicing materials shall be stockpiled on site unless all storage areas are protected from exposure to rain, snow, snowmelt and runoff. • Avoid dumping snow into any waterbody, including wetlands, cranberry bogs, detention/infiltration basins, and grassed swales/channels. • Avoid disposing of snow on top of storm drain catch basins. 7.0 Illicit Discharge Compliance Statement: Illicit Discharge Statement At no time will the owner or any other individual utilize the stormwater management system for any purpose other than its intended use. The stormwater management system as shown on the attached site plan at no time shall receive discharges other than stormwater, this includes “wastewater discharges and discharges of stormwater contaminated by contact with process wastes, raw materials, toxic pollutants, hazardous substances, oil or grease.” Applicant/Owner (Signature) STORMWATER MANAGEMENT BEST MANAGEMENT PRACTICES INSPECTION SCHEDULE AND EVALUATION CHECKLIST – POST CONSTRUCTION PHASE Project Location: 897 Main Street, S. Yarmouth MA Latest revision: ________ Best Management Practice Inspection Frequency (1) Date Inspected Inspector Minimum Maintenance and Key Items to Check Cleaning/ Repair Needed yes/no List Items Date of Cleaning/ Repair Performed By Water Level in System Drain Lines Quarterly -Sediment build up -Trash and debris Deep Sump Hooded Catch Basins Quarterly -Sediment level exceeds 8” -Trach and debris - Floatable oils or hydrocarbon - Grate or outlet blockage Pretreatment Unit – First Defense Untis Quarterly - Sediment not to exceed 18” -Floating contaminates shall be removed by vacuum pump prior to sediment removal -Outlet blockages Subsurface Infiltration Chamber Systems Twice per year -Sediment build up -Standing water greater than 72 hours Roadway Pavement Maintenance Quarterly (1) Refer to the Massachusetts Stormwater Management, Volume Two: Stormwater Technical Handbook (current) for recommendations regarding frequency for inspection and maintenance of specific BMPs. (2) Limited or no use of sodium chloride salts, fertilizers or pesticides recommended. Slow release fertilizer recommended. Stormwater Control Manager: Stamp 10 SC-740 Chamber StormTech SC-740 Chamber (not to scale) Nominal Specifications Size (Lx W x H)85.4” x 51.0” x 30.0” (2,170 x 1,295 x 762 mm) Chamber Storage 45.9 ft 3 (1.30 m 3) Min. Installed Storage*74.9 ft 3 (2.12 m 3) Weight 74.0 lbs (33.6 kg) *Assumes 6” (150 mm) stone above, below and between chambers and 40% stone porosity. The installed chamber system shall provide the load factors specified in the aashto lr fd bridge design specifications section 12.12 for ear th and live loads, with consideration for impact and multiple vehicle presences. 18" (450 mm) MIN* 8' (2.4 m) MAX 51" (1295 mm) 6" (150 mm) MIN 6" (150 mm) MIN 12" (300 mm) TYP 30" (760 mm) DEPTH OF STONE TO BE DETERMINED BY SITE DESIGN ENGINEER 6" (150 mm) MIN 12" (300 mm) MIN SITE DESIGN ENGINEER IS RESPONSIBLE FOR THE ENSURING THE REQUIRED BEARING CAPACITY OF SUBGRADE SOILS PAVEMENT LAYER (DESIGNED BY SITE DESIGN ENGINEER) CHAMBERS SHALL BE BE DESIGNED IN ACCORDANCE WITH ASTM F2787 "STANDARD PRACTICE FOR STRUCTURAL DESIGN OF THERMOPLASTIC CORRUGATED WALL STORMWATER COLLECTION CHAMBERS". GRANULAR WELL-GRADED SOIL/AGGREGATE MIXTURES, <35% FINES, COMPACT IN 6" (150 mm) MAX LIFTS TO 95% PROCTOR DENSITY. SEE THE TABLE OF ACCEPTABLE FILL MATERIALS. ADS GEOSYTHETICS 601T NON-WOVEN GEOTEXTILE ALL AROUND CLEAN, CRUSHED, ANGULAR EMBEDMENT STONE CHAMBERS SHALL MEET THE REQUIREMENTS FOR ASTM F2418 POLYPROPLENE (PP) CHAMBERS OR ASTM F2922 POLYETHYLENE (PE) CHAMBERS EMBEDMENT STONE SHALL BE A CLEAN, CRUSHED AND ANGULAR STONE WITH AN AASHTO M43 DESIGNATION BETWEEN #3 AND #57 PERIMETER STONE EXCAVATION WALL (CAN BE SLOPED OR VERTICAL) SC-740 END CAP *MINIMUM COVER TO BOTTOM OF FLEXIBLE PAVEMENT. FOR UNPAVED INSTALLATIONS WHERE RUTTING FROM VEHICLES MAY OCCUR, INCREASE COVER TO 24" (600 mm). Designed to meet the most stringent industry performance standards for superior structural integrity while providing designers with a cost-effective method to save valuable land and protect water resources. The StormTech system is designed primarily to be used under parking lots, thus maximizing land usage for private (commercial) and public applications. StormTech chambers can also be used in conjunction with Green Infrastructure, thus enhancing the performance and extending the service life of these practices. Shipping 30 chambers/pallet 60 end caps/pallet 12 pallets/truck 11 Note: Add 1.13 ft 3 (0.032 m3) of storage for each additional inch (25 mm) of stone foundation. Depth of Water in System in. (mm) Cumulative Chamber Storage ft3 (m 3) Total System Cumulative Storage ft3 (m 3) 42 (1067)45.90 (1.300)74.90 (2.121) 41 (1041)45.90 (1.300)73.77 (2.089) 40 (1016)45.90 (1.300)72.64 (2.057) 39 (991)45.90 (1.300)71.52 (2.025) 38 (965)45.90 (1.300) 70.39 (1.993) 37 (940)45.90 (1.300)69.26 (1.961) 36 (914)45.90 (1.300)68.14 (1.929) 35 (889)45.85 (1.298) 66.98 (1.897) 34 (864)45.69 (1.294) 65.75 (1.862) 33 (838)45.41 (1.286)64.46 (1.825) 32 (813)44.81 (1.269)62.97 (1.783) 31 (787)44.01 (1.246)w61.36 (1.737) 30 (762)43.06 (1.219)59.66 (1.689) 29 (737)41.98 (1.189)57.89 (1.639) 28 (711)40.80 (1.155) 56.05 (1.587) 27 (686)39.54 (1.120) 54.17 (1.534) 26 (660)38.18 (1.081)52.23 (1.479) 25 (635)36.74 (1.040) 50.23 (1.422) 24 (610)35.22 (0.977)48.19 (1.365) 23 (584)33.64 (0.953)46.11 (1.306) 22 (559)31.99 (0.906)44.00 (1.246) 21 (533)30.29 (0.858)1.85 (1.185) 20 (508)28.54 (0.808)39.67 (1.123) 19 (483)26.74 (0.757)37.47 (1.061) 18 (457)24.89 (0.705)35.23 (0.997) 17 (432)23.00 (0.651)32.96 (0.939) 16 (406)21.06 (0.596)30.68 (0.869) 15 (381)19.09 (0.541)28.36 (0.803) 14 (356)17.08 (0.484)26.03 (0.737) 13 (330)15.04 (0.426)23.68 (0.670) 12 (305)12.97 (0.367)21.31 (0.608) 11 (279)10.87 (0.309)18.92 (0.535) 10 (254)8.74 (0.247)16.51 (0.468) 9 (229)6.58 (0.186)14.09 (0.399) 8 (203)4.41 (0.125)11.66 (0.330) 7 (178)2.21 (0.063)9.21 (0.264) 6 (152)0 (0)6.76 (0.191) 5 (127)0 (0) 5.63 (0.160) 4 (102)0 (0)4.51 (0.128) 3 (76)0 (0)3.38 (0.096) 2 (51)0 (0)2.25 (0.064) 1 (25)0 (0)1.13 (0.032) Stone Foundation Stone Cover TONS (yds3)Stone Foundation Depth 6 12 16 SC-740 3.8 (2.8)4.6 (3.3)5.5 (3.9) KILOGRAMS (m3)150 mm 300 mm 450 mm SC-740 3,450 (2.1)4,170 (2.5)4,490 (3.0) Note: Assumes 6” (150 mm) of stone above and between chambers. Amount of Stone Per Chamber yd3 (m 3)Stone Foundation Depth 6 (150)12 (300)18 (450) SC-740 5.5 (4.2)6.2 (4.7)6.8 (5.2) Note: Assumes 6” (150 mm) of row separation and 18” (450 mm) of cover. The volume of excavation will vary as depth of cover increases. Volume Excavation Per Chamber ft3 (m 3) Bare Chamber Storage ft3 (m 3) Chamber and Stone Foundation Depth in. (mm) 6 (150)12 (300)18 (450) SC-740 45.9 (1.3)74.9 (2.1)81.7 (2.3)88.4 (2.5) Storage Volume Per Chamber Note: Assumes 6” (150 mm) stone above chambers, 6” (150 mm) row spacing and 40% stone porosity. SC-740 Cumulative Storage Volumes per chamber Assumes 40% Stone Porosity. Calculations are Based Upon a 6” (150 mm) Stone Base Under Chambers. 31 12.0 Inspection and Maintenance Looking down the Isolator Row PLUS A typical JetVac truck (This is not a StormTech product.) Examples of culvert cleaning nozzles appropriate for Isolator Row PLUS maintenance. (These are not StormTech products). 12.1 Isolator Row Plus Inspection Regular inspection and maintenance are essential to assure a properly functioning stormwater system. Inspection is easily accomplished through the manhole or optional inspection ports of an Isolator Row PLUS. Please follow local and OSHA rules for a confined space entry. Inspection ports can allow inspection to be accomplished completely from the surface without the need for a confined space entry. Inspection ports provide visual access to the system with the use of a flashlight. A stadia rod may be inserted to determine the depth of sediment. If upon visual inspection it is found that sediment has accumulated to an average depth exceeding 3 (76 mm), cleanout is required. A StormTech Isolator Row PLUS should initially be inspected immediately after completion of the site’s construction. While every effort should be made to prevent sediment from entering the system during construction, it is during this time that excess amounts of sediments are most likely to enter any stormwater system. Inspection and maintenance, if necessary, should be performed prior to passing responsibility over to the site’s owner. Once in normal service, a StormTech Isolator Row PLUS should be inspected bi-annually until an understanding of the sites characteristics is developed. The site’s maintenance manager can then revise the inspection schedule based on experience or local requirements. 12.2 Isolator Row Plus Maintenance JetVac maintenance is recommended if sediment has been collected to an average depth of 3 (76 mm) inside the Isolator Row PLUS. More frequent maintenance may be required to maintain minimum flow rates through the Isolator Row PLUS. The JetVac process utilizes a high pressure water nozzle to propel itself down the Isolator Row PLUS while scouring and suspending sediments. As the nozzle is retrieved, a wave of suspended sediments is flushed back into the manhole for vacuuming. Most sewer and pipe maintenance companies have vacuum/ JetVac combination vehicles. Fixed nozzles designed for culverts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45 (1143 mm) are best. StormTech recommends a maximum nozzle pressure of 2000 psi be utilized during cleaning. The JetVac process shall only be performed on StormTech Rows that have ADS PLUS fabric over the foundation stone. 32 12.0 Inspection & Maintenance 12.3 Eccentric Pipe Header Inspection Theses guidelines do not supercede a pipe manufacturer’s recommended I&M procedures. Consult with the manufacturer of the pipe header system for specific I&M procedures. Inspection of the header system should be carried out quarterly. On sites which generate higher levels of sediment more frequent inspections may be necessary. Headers may be accessed through risers, access ports or manholes. Measurement of sediment may be taken with a stadia rod or similar device. Cleanout of sediment should occur when the sediment volume has reduced the storage area by 25% or the depth of sediment has reached approximately 25% of the diameter of the structure. 12.4 Eccentric Pipe Manifold Maintenance Cleanout of accumulated material should be accomplished by vacuum pumping the material from the header. Cleanout should be accomplished during dry weather. Care should be taken to avoid flushing sediments out through the outlet pipes and into the chamber rows. Eccentric Header Step-by-Step Maintenance Procedures 1. Locate manholes connected to the manifold system 2. Remove grates or covers 3. Using a stadia rod, measure the depth of sediment 4. If sediment is at a depth of about 25% pipe volume or 25% pipe diameter proceed to step 5. If not proceed to step 6. 5. Vacuum pump the sediment. Do not flush sediment out inlet pipes. 6. Replace grates and covers 7. Record depth and date and schedule next inspection StormTech Isolator Row Plus - Step-by-Step Maintenance Procedures Step 1: Inspect Isolator Row PLUS for sediment A) Inspection ports (if present) i. Remove lid from floor box frame ii. Remove cap from inspection riser iii. Using a flashlight and stadia rod, measure depth of sediment iv. If sediment is at, or above, 3” (76 mm) depth proceed to Step 2. If not proceed to Step 3. B) All Isolator Plus Rows i. Remove cover from manhole at upstream end of Isolator Row PLUS ii. Using a flashlight, inspect down Isolator Row PLUS through outlet pipe 1. Follow OSHA regulations for confined space entry if entering manhole 2. Mirrors on poles or cameras may be used to avoid a confined space entry iii. If sediment is at or above the lower row of sidewall holes [approximately 3” (76 mm)]proceed to Step 2. If not proceed to Step 3. Step 2: Clean out Isolator Row PLUS using the JetVac process A) A fixed floor cleaning nozzle with rear facing nozzle spread of 45 (1143 mm) or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required during jetting Step 3: Replace all caps, lids and covers Step 4: Inspect and clean catch basins and manholes upstream of the StormTech system following local guidelines. Figure 20 – StormTech Isolator Row Plus (not to scale) Figure 21 – Eccentric Manifold Maintenance 4 21) B)1) A) 1, 2, 6 3, 4, 5 Please contact StormTech’s Technical Services Department at 888-892-2894 for a spreadsheet to estimate cleaning intervals. 33 13.0 General Notes 1.StormTech requires installing contractors to use and understand StormTech’s latest Installation Instructions prior to beginning system installation. 2.Our Technical Services Department offers installation consultations to installing contractors. Contact our Technical Service Representatives at least 30 days prior to system installation to arrange a preinstallation consultation. Our representatives can then answer questions or address comments on the StormTech chamber system and inform the Installing contractor of the minimum installation requirements before beginning the system’s construction. Call 860-529-8188 to speak to a Technical Service Representative or visit www.stormtech.com to receive a copy of our Installation Instructions. 3.StormTech’s requirements for systems with pavement design (asphalt, concrete pavers, etc.): Minimum cover for the SC-740, DC-780 and SC-310 chambers is 18” (457 mm) not including pavement; Minimum cover for the SC-160LP chamber is 14 (350 mm); Maximum cover for the SC-740 and SC- 310 chambers is 96” (2.4 m) including pavement design; Maximum cover for the SC-160LP chamber is 10’ (3.0 m); Maximum cover for the DC-780 chamber is 12’ (3.6 m) including pavement design. For installations that do not include pavement, where rutting from vehicles may occur, minimum required cover is 24” (610 mm), maximum cover is as stated above. 4.The contractor must report any discrepancies with the bearing capacity of the chamber foundation materials to the design engineer. 5.AASHTO M288 Class 2 non-woven geotextile (filter fabric) must be used as indicated in the project plans. 6.Stone placement between chamber rows and around perimeter must follow instructions as indicated in the most current version of StormTech’s Installation Instructions. 7.Backfilling over the chambers must follow requirements as indicated in the most current version of StormTech’s Installation Instructions. 8.The contractor must refer to StormTech’s Installation Instructions for a Table of Acceptable Vehicle Loads at various depths of cover. This information is also available at StormTech’s website: www.stormtech.com. The contractor is responsible for preventing vehicles that exceed StormTech’s requirements from traveling across or parking over the stormwater system. Temporary fencing, warning tape and appropriately located signs are commonly used to prevent unauthorized vehicles from entering sensitive construction areas. 9.The contractor must apply erosion and sediment control measures to protect the stormwater system during all phases of site construction per local codes and design engineer’s specifications. 10. STORMTECH PRODUCT WARRANTY IS LIMITED. Contact StormTech for warranty information. Isolator® Row Plus O&M Manual 2 Looking down the Isolator Row Plus from the manhole opening, ADS Plus Fabric is shown between the chamber and stone base. StormTech Isolator Row Plus with Overflow Structure (not to scale) The Isolator® Row Plus Introduction An important component of any Stormwater Pollution Prevention Plan is inspection and maintenance. The StormTech Isolator Row Plus is a technique to inexpensively enhance Total Suspended Solids (TSS), Total Phosphorus (TP), Total Petroluem Hydrocarbons (TPH) and Total Nitrogen (TN) removal with easy access for inspection and maintenance. The Isolator Row Plus The Isolator Row Plus is a row of StormTech chambers, either SC-160, SC- 310, DC-780, SC-800, MC-3500, MC-4500 or MC-7200 models, are lined with filter fabric and connected to a closely located manhole for easy access. The fabric lined chambers provide for sediment settling and filtration as stormwater rises in the Isolator Row Plus and passes through the filter fabric. The open bottom chambers allow stormwater to flow vertically out of the chambers. Sediments are captured in the Isolator Row Plus protecting the adjacent stone and chambers storage areas from sediment accumulation. ADS Isolator Row and Plus fabric are placed between the stone and the Isolator Row Plus chambers. The woven geotextile provides a media for stormwater filtration, a durable surface for maintenance, prevents scour of the underlying stone and remains intact during high pressure jetting. The Isolator Row Plus is designed to capture the “first flush” runoff and offers the versatility to be sized on a volume basis or a flow-rate basis. An upstream manhole provides access to the Isolator Row Plus and includes a high/low concept such that stormwater flow rates or volumes that exceed the capacity of the Isolator Row Plus bypass through a manifold to the other chambers. This is achieved with an elevated bypass manifold or a high-flow weir. This creates a differential between the Isolator Row Plus row of chambers and the manifold to the rest of the system, thus allowing for settlement time in the Isolator Row Plus. After Stormwater flows through the Isolator Row Plus and into the rest of the chamber system it is either exfiltrated into the soils below or passed at a controlled rate through an outlet manifold and outlet control structure. The Isolator Row Plus FlampTM is a flared end ramp apparatus attached to the inlet pipe on the inside of the chamber end cap. The FLAMP provides a smooth transition from pipe invert to fabric bottom. It is configured to improve chamber function performance by enhancing outflow of solid debris that would otherwise collect at the chamber's end, or more difficult to remove and require confined space entry into the chamber area. It also serves to improve the fluid and solid flow into the access pipe during maintenance and cleaning and to guide cleaning and inspection equipment back into the inlet pipe when complete. The Isolator Row Plus may be part of a treatment train system. The treatment train design and pretreatment device selection by the design engineer is often driven by regulatory requirements. Whether pretreatment is used or not, StormTech recommend using the Isolator Row Plus to minimize maintenance requirements and maintenance costs. Note: See the StormTech Design Manual for detailed information on designing inlets for a StormTech system, including the Isolator Row Plus. 3 Inspection The frequency of inspection and maintenance varies by location. A routine inspection schedule needs to be established for each individual location based upon site specific variables. The type of land use (i.e. industrial, commercial, residential), anticipated pollutant load, percent imperviousness, climate, etc. all play a critical role in determining the actual frequency of inspection and maintenance practices. At a minimum, StormTech recommends annual inspections. Initially, the Isolator Row Plus should be inspected every 6 months for the first year of operation. For subsequent years, the inspection should be adjusted based upon previous observation of sediment deposition. The Isolator Row Plus incorporates a combination of standard manhole(s) and strategically located inspection ports (as needed). The inspection ports allow for easy access to the system from the surface, eliminating the need to perform a confined space entry for inspection purposes. If upon visual inspection it is found that sediment has accumulated, a stadia rod should be inserted to determine the depth of sediment. When the average depth of sediment exceeds 3" (75 mm) throughout the length of the Isolator Row Plus, clean-out should be performed. Maintenance The Isolator Row Plus was designed to reduce the cost of periodic maintenance. By “isolating” sediments to just one row, costs are dramatically reduced by eliminating the need to clean out each row of the entire storage bed. If inspection indicates the potential need for maintenance, access is provided via a manhole(s) located on the end(s) of the row for cleanout. If entry into the manhole is required, please follow local and OSHA rules for a confined space entry. Maintenance is accomplished with the JetVac process. The JetVac process utilizes a high pressure water nozzle to propel itself down the Isolator Row Plus while scouring and suspending sediments. As the nozzle is retrieved, the captured pollutants are flushed back into the manhole for vacuuming. Most sewer and pipe maintenance companies have vacuum/JetVac combination vehicles. Selection of an appropriate JetVac nozzle will improve maintenance efficiency. Fixed nozzles designed for culverts or large diameter pipe cleaning are preferable. Rear facing jets with an effective spread of at least 45” are best. StormTech recommends a maximum nozzle pressure of 2000 psi be utilized during cleaning. JetVac reels can vary in length. For ease of maintenance, ADS recommends Isolator Row Plus lengths up to 200' (61 m). The JetVac process shall only be performed on StormTech Isolator Row Plus that have ADS Plus Fabric (as specified by StormTech) over their angular base stone. Isolator Row Plus Inspection/Maintenance StormTech Isolator Row Plus (not to scale) Isolator Row Plus Step By Step Maintenance Procedures Step 1 Inspect Isolator Row Plus for sediment. A) Inspection ports (if present) i. Remove lid from floor box frame ii. Remove cap from inspection riser iii. Using a flashlight and stadia rod,measure depth of sediment and record results on maintenance log. iv. If sediment is at or above 3 inch depth, proceed to Step 2. If not, proceed to Step 3. B) All Isolator Row Plus i. Remove cover from manhole at upstream end of Isolator Row Plus ii. Using a flashlight, inspect down Isolator Row Plus through outlet pipe 1. Mirrors on poles or cameras may be used to avoid a confined space entry 2. Follow OSHA regulations for confined space entry if entering manhole iii. If sediment is at or above the lower row of sidewall holes (approximately 3 inches), proceed to Step 2. If not, proceed to Step 3. Step 2 Clean out Isolator Row Plus using the JetVac process. A) A fixed floor cleaning nozzle with rear facing nozzle spread of 45 inches or more is preferable B) Apply multiple passes of JetVac until backflush water is clean C) Vacuum manhole sump as required Step 3 Replace all caps, lids and covers, record observations and actions. Step 4 Inspect & clean catch basins and manholes upstream of the StormTech system. ADS “Terms and Conditions of Sale” are available on the ADS website, www.adspipe.com The ADS logo, StormTech®, the Isolator® Row Plus and the Green Stripe are registered trademarks of Advanced Drainage Systems, Inc. © 2025 Advanced Drainage Systems, Inc. #11081 5/25 CS 4 21) B)1) A) Sample Maintenance Log Date Stadia Rod Readings Sedi- ment Depth (1)–(2) Observations/Actions InspectorFixed point to chamber bottom (1) Fixed point to top of sediment (2) 3/15/11 6.3 ft none New installation. Fixed point is CI frame at grade DJM 9/24/11 6.2 0.1 ft Some grit felt SM 6/20/13 5.8 0.5 ft Mucky feel, debris visible in manhole and in Isolator Row Plus, maintenance due NV 7/7/13 6.3 ft 0 System jetted and vacuumed DJM adspipe.com 800-821-6710 Operation and Maintenance Manual First Defense® High Capacity and First Defense®Optimum Vortex Separator for Stormwater Treatment First Defense® Operation and Maintenance Manual Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com Table of Contents 3 First Defense® by Hydro International - Introduction - Operation - Pollutant Capture and Retention 4 Model Sizes & Configurations - First Defense® Components 5 Maintenance - Overview - Maintenance Equipment Considerations - Determining Your Maintenance Schedule 6 Maintenance Procedures - Inspection - Floatables and Sediment Clean Out 8 First Defense® Installation Log 9 First Defense® Inspection and Maintenance Log COPYRIGHT STATEMENT: The contents of this manual, including the graphics contained herein, are intended for the use of the recipient to whom the document and all associated information are directed. Hydro International plc owns the copyright of this document, which is supplied in confidence. It must not be used for any purpose other than that for which it is supplied and must not be reproduced, in whole or in part stored in a retrieval system or transmitted in any form or by any means without prior permission in writing from Hydro International plc. First Defense® is a trademarked hydrodynamic vortex separation device of Hydro International plc. A patent covering the First Defense® has been granted. DISCLAIMER: Information and data contained in this manual is exclusively for the purpose of assisting in the operation and maintenance of Hydro International plc’s First Defense®. No warranty is given nor can liability be accepted for use of this information for any other purpose. Hydro International plc has a policy of continuous product development and reserves the right to amend specifications without notice. Page | 2 First Defense® Operation and Maintenance Manual I. First Defense® by Hydro International Page | 3 Introduction The First Defense® is an enhanced vortex separator that combines an effective and economical stormwater treatment chamber with an integral peak flow bypass. It efficiently removes total suspended solids (TSS), trash and hydrocarbons from stormwater runoff without washing out previously captured pollutants. The First Defense® is available in several model configurations to accommodate a wide range of pipe sizes, peak flows and depth constraints. The two product models described in this guide are the First Defense® High Capacity and the First Defense® Optimum; they are inspected and maintained identically. Operation The First Defense® operates on simple fluid hydraulics. It is self- activating, has no moving parts, no external power requirement and is fabricated with durable non-corrosive components. No manual procedures are required to operate the unit and maintenance is limited to monitoring accumulations of stored pollutants and periodic clean-outs. The First Defense® has been designed to allow for easy and safe access for inspection, monitoring and clean-out procedures. Neither entry into the unit nor removal of the internal components is necessary for maintenance, thus safety concerns related to confined-space- entry are avoided. Pollutant Capture and Retention The internal components of the First Defense® have been designed to optimize pollutant capture. Sediment is captured and retained in the base of the unit, while oil and floatables are stored on the water surface in the inner volume (Fig.1). The pollutant storage volumes are isolated from the built-in bypass chamber to prevent washout during high-flow storm events. The sump of the First Defense® retains a standing water level between storm events. This ensures a quiescent flow regime at the onset of a storm, preventing resuspension and washout of pollutants captured during previous events. Accessories such as oil absorbent pads are available for enhanced oil removal and storage. Due to the separation of the oil and floatable storage volume from the outlet, the potential for washout of stored pollutants between clean-outs is minimized. • Inlet options include surface grate or multiple inlet pipes • Integral high capacity bypass conveys large peak flows without the need for “offline” arrangements using separate junction manholes • Long flow path through the device ensures a long residence time within the treatment chamber, enhancing pollutant settling • Delivered to site pre-assembled and ready for installation Advantages • Stormwater treatment at the point of entry into the drainage line • Sites constrained by space, topography or drainage profiles with limited slope and depth of cover • Retrofit installations where stormwater treatment is placed on or tied into an existing storm drain line • Pretreatment for filters, infiltration and storage Applications Oil Max Oil Storage Depth Sediment StorageSediment Fig.1 Pollutant storage volumes in the First Defense®. First Defense® Operation and Maintenance Manual Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com 7 II. Model Sizes & Configurations The First Defense® inlet and internal bypass arrangements are available in several model sizes and configurations. The components have modified geometries allowing greater design flexibility to accommodate various site constraints. Page | 4 First Defense® Components 1. Built-In Bypass 2. Inlet Pipe 3. Inlet Chute 4. Floatables Draw-off Port 5. Outlet Pipe 6. Floatables Storage 12 3 4 5 6 7 8 (not pictured) All First Defense® models include the internal components that are designed to remove and retain total suspended solids (TSS), gross solids, floatable trash and hydrocarbons (Fig.2). First Defense® model sizes (diameter) are shown in Table 1. III. Maintenance 7. Sediment Storage 8. Inlet Grate or Cover First Defense® Model Sizes (ft / m) diameter 3 / 0.9 4 / 1.2 5 / 1.5 6 / 1.8 7 / 2.1 8 / 2.4 10 / 3.0 Fig. 2 Table 1 First Defense® Operation and Maintenance ManualPage | 5 Overview The First Defense® protects the environment by removing a wide range of pollutants from stormwater runoff. Periodic removal of these captured pollutants is essential to the continuous, long-term functioning of the First Defense®. The First Defense® will capture and retain sediment and oil until the sediment and oil storage volumes are full to capacity. When sediment and oil storage capacities are reached, the First Defense® will no longer be able to store removed sediment and oil. The First Defense® allows for easy and safe inspection, monitoring and clean-out procedures. A commercially or municipally owned sump-vac is used to remove captured sediment and floatables. Access ports are located in the top of the manhole. Maintenance events may include Inspection, Oil & Floatables Removal, and Sediment Removal. Maintenance events do not require entry into the First Defense®, nor do they require the internal components of the First Defense® to be removed. In the case of inspection and floatables removal, a vactor truck is not required. However, a vactor truck is required if the maintenance event is to include oil removal and/or sediment removal. Maintenance Equipment Considerations The internal components of the First Defense® have a centrally located circular shaft through which the sediment storage sump can be accessed with a sump vac hose. The open diameter of this access shaft is 15 inches in diameter (Fig.3). Therefore, the nozzle fitting of any vactor hose used for maintenance should be less than 15 inches in diameter. Determining Your Maintenance Schedule The frequency of clean out is determined in the field after installation. During the first year of operation, the unit should be inspected every six months to determine the rate of sediment and floatables accumulation. A simple probe such as a Sludge-Judge® can be used to determine the level of accumulated solids stored in the sump. This information can be recorded in the maintenance log (see page 9) to establish a routine maintenance schedule. The vactor procedure, including both sediment and oil / flotables removal, for First Defense® typically takes less than 30 minutes and removes a combined water/oil volume of about 765 gallons. Fig.3 The central opening to the sump of the First Defense®is 15 inches in diameter. 15-in Maintenance Access First Defense® Operation and Maintenance Manual Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com Inspection Procedures 1. Set up any necessary safety equipment around the access port or grate of the First Defense® as stipulated by local ordinances. Safety equipment should notify passing pedestrian and road traffic that work is being done. 2. Remove the grate or lid to the manhole. 3. Without entering the vessel, look down into the chamber to inspect the inside. Make note of any irregularities. Fig.4 shows the standing water level that should be observed. 4. Without entering the vessel, use the pole with the skimmer net to remove floatables and loose debris from the components and water surface. 5. Using a sediment probe such as a Sludge Judge®, measure the depth of sediment that has collected in the sump of the vessel. 6. On the Maintenance Log (see page 9), record the date, unit location, estimated volume of floatables and gross debris removed, and the depth of sediment measured. Also note any apparent irregularities such as damaged components or blockages. 7. Securely replace the grate or lid. 8. Take down safety equipment. 9. Notify Hydro International of any irregularities noted during inspection. Floatables and Sediment Clean Out Floatables clean out is typically done in conjunction with sediment removal. A commercially or municipally owned sump- vac is used to remove captured sediment and floatables (Fig.4). Floatables and loose debris can also be netted with a skimmer and pole. The access port located at the top of the manhole provides unobstructed access for a vactor hose to be lowered to the base of the sump. Scheduling • Floatables and sump clean out are typically conducted once a year during any season. • Floatables and sump clean out should occur as soon as possible following a spill in the contributing drainage area. Recommended Equipment • Safety Equipment (traffic cones, etc) • Crow bar or other tool to remove grate or lid • Pole with skimmer or net (if only floatables are being removed) • Sediment probe (such as a Sludge Judge®) • Vactor truck (flexible hose recommended) • First Defense® Maintenance Log Fig.4 Floatables are removed with a vactor hose Page | 6 First Defense® Operation and Maintenance Manual Floatables and Sediment Clean Out Procedures 1. Set up any necessary safety equipment around the access port or grate of the First Defense® as stipulated by local ordinances. Safety equipment should notify passing pedestrian and road traffic that work is being done. 2. Remove the grate or lid to the manhole. 3. Without entering the vessel, look down into the chamber to inspect the inside. Make note of any irregularities. 4. Remove oil and floatables stored on the surface of the water with the vactor hose or with the skimmer or net 5. Using a sediment probe such as a Sludge Judge®, measure the depth of sediment that has collected in the sump of the vessel and record it in the Maintenance Log (page 9). 6. Once all floatables have been removed, drop the vactor hose to the base of the sump. Vactor out the sediment and gross debris off the sump floor 7. Retract the vactor hose from the vessel. 8. On the Maintenance Log provided by Hydro International, record the date, unit location, estimated volume of floatables and gross debris removed, and the depth of sediment measured. Also note any apparent irregularities such as damaged components, blockages, or irregularly high or low water levels. 9. Securely replace the grate or lid. - Regularly during first year of installation - Every 6 months after the first year of installation - Once per year, with sediment removal - Following a spill in the drainage area - Once per year or as needed - Following a spill in the drainage area Activity FrequencyInspection Oil and Floatables Removal Sediment Removal Maintenance at a Glance NOTE: For most clean outs the entire volume of liquid does not need to be removed from the manhole. Only remove the first few inches of oils and floatables from the water surface to reduce the total volume of liquid removed during a clean out. Page | 7 First Defense® Installation Log HYDRO INTERNATIONAL REFERENCE NUMBER: SITE NAME: SITE LOCATION: OWNER: CONTRACTOR: CONTACT NAME: CONTACT NAME: COMPANY NAME: COMPANY NAME: ADDRESS: ADDRESS: TELEPHONE: TELEPHONE: FAX: FAX: INSTALLATION DATE: / / MODEL SIZE (CIRCLE ONE): [3-FT] [4-FT] [5-FT] [6-FT] [7-FT] [8-FT] [10-FT] INLET (CIRCLE ALL THAT APPLY): GRATED INLET (CATCH BASIN) INLET PIPE (FLOW THROUGH) Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com First Defense® Inspection and Maintenance Log Initials Depth of Floatables and Oils Sediment Depth Measured Volume of Sediment Removed Site Activity and Comments Date Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com First Defense® Operation and Maintenance Manual Hydro International (Stormwater), 94 Hutchins Drive, Portland ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 Web: www.hydro-int.com NOTES First Defense® Operation and Maintenance ManualNotes Stormwater Solutions 94 Hutchins Drive Portland, ME 04102 Tel: (207) 756-6200 Fax: (207) 756-6212 stormwaterinquiry@hydro-int.com www.hydro-int.com Turning Water Around...® FD_O+M_K_2105 (508) 746-6060 / 26 Union Street, Plymouth, MA 02360 merrillinc.com / (781) 826-9200 / 427 Columbia Road, Hanover, MA 02339 Appendix E Site Soil Analysis • NRCS Web Soil Survey Map and Units Soil Map—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/16/2025 Page 1 of 34611970461198046119904612000461201046120204612030461204046120504612060461207046120804612090461197046119804611990461200046120104612020461203046120404612050461206046120704612080399160399170399180399190399200399210399220399230399240399250 399160 399170 399180 399190 399200 399210 399220 399230 399240 399250 41° 39' 15'' N 70° 12' 39'' W41° 39' 15'' N70° 12' 35'' W41° 39' 10'' N 70° 12' 39'' W41° 39' 10'' N 70° 12' 35'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 19N WGS84 0 25 50 100 150Feet 0 5 10 20 30Meters Map Scale: 1:615 if printed on A portrait (8.5" x 11") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:25,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Barnstable County, Massachusetts Survey Area Data: Version 23, Sep 17, 2024 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jun 10, 2022—Jun 30, 2022 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. Soil Map—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/16/2025 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 252A Carver coarse sand, 0 to 3 percent slopes 1.2 100.0% Totals for Area of Interest 1.2 100.0% Soil Map—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/16/2025 Page 3 of 3 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:Outwash plains, moraines Landform position (two-dimensional):Summit, shoulder Landform position (three-dimensional):Side slope, crest, tread Down-slope shape:Linear, convex 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) Map Unit Description: Carver coarse sand, 0 to 3 percent slopes---Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/16/2025 Page 1 of 2 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 deltas, kame terraces, outwash plains, outwash terraces 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:Kame terraces, outwash plains, outwash terraces, outwash deltas, kames, eskers, moraines 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:Outwash terraces, outwash deltas, kame 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:Terraces, drainageways, depressions Landform position (three-dimensional):Tread Down-slope shape:Concave Across-slope shape:Concave Hydric soil rating: Yes Data Source Information Soil Survey Area: Barnstable County, Massachusetts Survey Area Data: Version 23, Sep 17, 2024 Map Unit Description: Carver coarse sand, 0 to 3 percent slopes---Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/16/2025 Page 2 of 2