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HomeMy WebLinkAbout2025-12-22 Stormwater Report Prepared by: 349 Main Street – Route 28 West Yarmouth, MA 02673 STORMWATER REPORT 703 ROUTE 28 SOUTH YARMOUTH, MA DECEMBER 2025 Owner/Applicant: STEVEN M. KATZ 99 Sullivan Road West Yarmouth, MA BSC Job Number: 0101264.00 Stormwater Report 703 Route 28 South Yarmouth, MA TABLE OF CONTENTS 1.0 PROJECT INFORMATION 1.01 PROJECT DESCRIPTION 1.02 PRE-DEVELOPMENT CONDITIONS 1.03 POST-DEVELOPMENT CONDITIONS 2.0 DRAINAGE SUMMARY 2.01 STORMWATER STANDARD 1 – NEW STORMWATER CONVEYANCES 2.02 STORMWATER STANDARD 2 – STORMWATER RUNOFF RATES 2.03 STORMWATER STANDARD 3 – GROUNDWATER RECHARGE 2.04 STORMWATER STANDARD 4 – TSS REMOVAL 2.05 STORMWATER STANDARD 5 – LUHPPL 2.06 STORMWATER STANDARD 6 – CRITICAL AREAS 2.07 STORMWATER STANDARD 7 – REDEVELOPMENT PROJECTS 2.08 STORMWATER STANDARD 8 – SEDIMENTATION & EROSION CONTROL PLAN 2.09 STORMWATER STANDARD 9 – LONG TERM O&M PLAN 2.10 STORMWATER STANDARD 10 – ILLICIT DISCHARGES 2.11 CONCLUSIONS 3.0 CONSTRUCTION PERIOD POLLUTION PREVENTION AND EROSION AND SEDIMENTATION CONTROL 4.0 LONG-TERM POLLUTION PREVENTION & OPERATION AND MAINTENANCE PLAN 5.0 HYDROLOGY CALCULATIONS 5.01 EXISTING WATERSHED PLAN 5.02 EXISTING HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) 5.03 PROPOSED WATERSHED PLAN 5.04 PROPOSED HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) 6.0 ADDITIONAL DRAINAGE CALCULATIONS 6.01 TSS REMOVAL CALCULATIONS 6.02 GROUNDWATER RECHARGE VOLUME CALCULATIONS 6.03 WATER QUALITY VOLUME CALCULATIONS 6.04 PIPE SIZING CALCULATIONS 6.05 GROUNDWATER MOUNDING ANALYSIS 6.06 ILLICIT DISCHARGE COMPLIANCE STATEMENT APPENDICES APPENDIX A – USGS LOCUS MAP APPENDIX B – FEMA MAP APPENDIX C – WEB SOIL SURVEY APPENDIX D – TEST PIT LOGS APPENDIX E – NOAA 14 PRECIPITATION TABLES APPENDIX F – STORMWATER CHECKLIST Stormwater Report 703 Route 28 South Yarmouth, MA SECTION 1.0 PROJECT INFORMATION Stormwater Report 703 Route 28 South Yarmouth, MA 1.01 PROJECT DESCRIPTION Steven M. Katz (The Applicant) is seeking to construct a mixed-use commercial and residential development in South Yarmouth, Massachusetts, hereinafter referred to as “the Project”. The total property area is approximately 36,662 square feet (0.84 acres) and is located off Route 28 adjacent to Parkers River. The project is bounded on the north by the Parker River viewing platform, on the east by privately owned condominiums, and bounded on the south and west by Parker River. The Project consists of the demolition of the existing building, removal of all existing bituminous pavement, and the clearing and grubbing of the southern and western portions of the property. Three multi-family duplex housing units are proposed with a total of six units with garage parking, as well as walkways, utility services, native landscaping, and a stormwater management system. The buildings have a combined footprint of approximately 6,600 square feet. 1.02 PRE-DEVELOPMENT CONDITIONS The existing site topography generally slopes west across the property towards Parker River with slopes ranging from 0-66%. The current site is comprised of a retail building with a paved parking area and small areas of vegetation. The primary soil classification identified by the NRCS Web Soil Survey is Carver coarse sand (252A) and Udipsamments (665), which account for all of the property and the project area. Based on the soil classification identified, runoff calculations have been performed using curve numbers corresponding to Hydrologic Soil Group (HSG) A. The Project is entirely within 200-foot Riverfront Area and FEMA flood zone, elevation 11.0. A large portion of the project is within 100-foot Riverfront Area. The existing site has no existing drainage facilities, and the majority of the stormwater runoff is directed to Parker River via country drainage. A small portion of the site flows toward a small depression on site, where it will ultimately be directed towards the river as well. 1.03 POST-DEVELOPMENT CONDITIONS The proposed stormwater management system has been designed in a manner that will meet or exceed the provisions of the Department of Environmental Protection (DEP) Stormwater Management Standards and the Town of Yarmouth Stormwater Management Regulations for a redevelopment project. Stormwater runoff from all of the 3-story buildings (approximately 6,600 square feet) will be collected via roof drains and conveyed into the proposed subsurface stormwater infiltration system located under the proposed driveway. In addition, three water quality units are proposed at low spots along the curb line which collect stormwater runoff from the driveway and discharge into the subsurface infiltration system. The system is designed to completely hold and infiltrate the 100-year, 24-hour storm event. Based upon the test pit data performed in March 2025, the estimated seasonal high groundwater elevation is equal to 1.5. As such the infiltration system has been set with a bottom elevation of 3.50 to provide the minimum 2-feet of clearance above groundwater and account for any groundwater fluctuations that may occur. A groundwater mounding analysis is included in Section 6.0 of this report. Specifics of the project’s compliance with the Stormwater Standards are discussed in detail in the following sections. Stormwater Report 703 Route 28 South Yarmouth, MA SECTION 2.0 DRAINAGE SUMMARY Stormwater Report 703 Route 28 South Yarmouth, MA 2.01 Stormwater Standard 1 – New Stormwater Conveyances Per Massachusetts Stormwater Management Standard #1, no new outfalls may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth. No new untreated stormwater discharges are proposed. Rip-rap outlet protection sizing calculations are included in Section 6.0 of this Report. 2.02 Stormwater Standard 2 – Stormwater Runoff Rates Watershed modeling was performed using HydroCAD Stormwater Modeling Software version 10.20, a computer aided design program that combines SCS runoff methodology with standard hydraulic calculations. A model of the site’s hydrology was developed for both pre- and post-development conditions to assess the effects of the proposed development on the project site and surrounding areas. Stormwater runoff was modeled using NOAA 14 rainfall values as required by the Town of Yarmouth Stormwater Management Regulations. The following rainfall values have been used in our analysis: Storm Frequency NOAA 14 Rainfall (Inches) 2-year 3.37 10-year 4.90 25-year 5.86 50-year 6.58 100-year 7.33 The stormwater management system for the project has been designed such that the post-development conditions result in no increase to peak runoff rates off the property for the 2, 10, 25, 50, and 100-year, 24-hour storm events, as detailed in the table below. Peak Flow Discharge Rates Node DP1 – Flow to Parker River Storm Event Pre-Development Peak Discharge Rate (cfs) Post-Development Peak Discharge Rate (cfs) Change in Peak Discharge Rate (cfs) 2-Year 1.63 0.00 -1.63 10-Year 3.21 0.04 -3.17 25-Year 4.26 0.14 -4.12 50-Year 5.07 0.32 -4.75 100-Year 5.92 0.55 -5.37 2.03 Stormwater Standard 3 – Groundwater Recharge Groundwater recharge is provided on site via an underground structural infiltration system beneath the driveway east of the proposed buildings. Overall, the project will result in no loss of annual recharge to groundwater as require by Standard 3. Refer to Section 6.0 of this Report for groundwater recharge information. As the infiltration system has more than 2-feet but less than 4-feet separation to estimated seasonal high groundwater, a mounding analysis has been performed in accordance with the Hantoush Method to ensure that a groundwater mound Stormwater Report 703 Route 28 South Yarmouth, MA does not extend into the bottom of the infiltration system preventing infiltration of the required recharge volume. This analysis is included in Section 6.0 of this Report. 2.04 Stormwater Standard 4 – TSS Removal As a redevelopment, the Project stormwater management system will achieve a TSS removal greater than 80% and will provide a minimum removal of 44% of TSS prior to entering the infiltration system as require by the Town of Yarmouth Stormwater Management Standards. The proposed stormwater management system has been designed to provide treatment of runoff in order to reduce suspended solids prior to discharge off-site through the implementation of the following best management practices: · Proprietary Hydrodynamic Separators · Underground Stormwater Infiltration Systems The water quality volume is defined as the runoff volume requiring TSS Removal for the site and is equal to 1.0-inches of runoff over the total impervious area of the post-development site for sites with rapid infiltration rates. The required water quality volume for the project is provided in Section 6.0 of this Report. The underground infiltration system has been sized to treat the required water quality volume and calculations are included in Section 6.0 of this Report. A long-term pollution prevention plan complying with the requirements of Standard 4 is included in Section 4.0 of this Report. 2.05 Stormwater Standard 5 – Land Uses with Higher Potential Pollutant Loads This standard is not applicable as the project site is not a land use with higher potential pollutant loads (LUHPPL). 2.06 Stormwater Standard 6 – Stormwater Discharges to a Critical Area This standard is not applicable as runoff from the project site does not discharge to a critical area. 2.07 Stormwater Standard 7 – Redevelopment Projects The Project qualifies as a redevelopment project under Stormwater Standard 7. However, the project has been designed to fully comply with all MassDEP Stormwater Standards and the Town of Yarmouth Stormwater Management Regulations. 2.08 Stormwater Standard 8 – Sedimentation and Erosion Control Plan Erosion and sedimentation controls are shown on the Project Plans. Additionally, a Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan is included in Section 3.0 of this Report. 2.09 Stormwater Standard 9 – Long Term Operation and Maintenance Plan A Long-Term Operation and Maintenance Plan is included in Section 4.0 of this Report. 2.10 Stormwater Standard 10 – Illicit Discharges There are no known illicit discharges on the project site, and none are proposed. An illicit discharge compliance statement is included in Section 6.0 and will be signed by the Applicant prior to issuance of any permits. 2.11 Conclusion The project has been designed in accordance with DEP Stormwater Management Standards. Through the construction of the aforementioned stormwater system, the project will provide peak rate attenuation, TSS removal and groundwater recharge. SECTION 3.0 CONSTRUCTION PERIOD POLLUTION PREVENTION AND EROSION AND SEDIMENTATION CONTROL PLAN Stormwater Report 703 Route 28 South Yarmouth, MA 3.0 CONSTRUCTION PERIOD POLLUTION PREVENTION AND EROSION AND SEDIMENTATION CONTROL PLAN This Section specifies requirements and suggestions for implementation of a Stormwater Pollution Prevention Plan (SWPPP) for 703 Route 28, in South Yarmouth, Massachusetts. The SWPPP shall be provided and maintained on-site by the Contractor(s) during all construction activities. The SWPPP shall be updated as required to reflect changes to construction activity. The stormwater pollution prevention measures contained in the SWPPP shall be at least the minimum required by Local Regulations. The Contractor shall provide additional measures to prevent pollution from stormwater discharges in compliance with all local, state and federal requirements. The SWPPP shall include provisions for, but not be limited to, the following: 1. Construction Trailers 2. Lay-down Areas 3. Equipment Storage Areas 4. Stockpile Areas 5. Disturbed Areas Erosion and Sedimentation Control The Contractor shall be solely responsible for erosion and sedimentation control at the site. The Contractor shall utilize a system of operations and all necessary erosion and sedimentation control measures, even if not specified herein or elsewhere, to minimize erosion damage at the site to prevent the migration of sediment into environmentally sensitive areas. Environmentally sensitive areas include all wetland resource areas within, and downstream of, the site, and those areas of the site that are not being altered. Erosion and sedimentation control shall be in accordance with this Section, the design drawings, and the following:  “National Pollutant Discharge Elimination System General Permit for Discharges from Construction Activities (EPA Construction General Permit February 16, 2017).  Massachusetts Stormwater Management Policy Handbook issued by the Massachusetts Department of Environmental Protection, January 2008.  Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas, A Guide for Planners, Designers and Municipal Officials, March 1997. The BMP's presented herein should be used as a guide for erosion and sedimentation control and are not intended to be considered specifications for construction. The most important BMP is maintaining a rapid construction process, resulting in prompt stabilization of surfaces, thereby reducing erosion potential. Given the primacy of rapid construction, these guidelines have been designed to allow construction to progress with essentially no hindrance by the erosion control methods prescribed. These guidelines have also been designed with sufficient flexibility to allow the Contractor to modify the suggested methods as required to suit seasonal, atmospheric, and site-specific physical constraints. Another important BMP is the prevention of concentrated water flow. Sheet flow does not have the erosive potential of a concentrated rivulet. These guidelines recommend construction methods that allow localized erosion control and a system of construction, which inhibits the development of shallow concentrated flow. These BMP's shall be maintained throughout the construction process. Stormwater Report 703 Route 28 South Yarmouth, MA CONTACT INFORMATION AND RESPONSIBLE PARTIES The following is a list of all project-associated parties: Owner Steven M. Katz 99 Sullivan Road West Yarmouth, MA 02673 Contractor To be determined Environmental Consultant BSC Group, Inc. 803 Summer Street Boston, MA 02127 Contact: Brian G. Yergatian Phone: (617) 896–4590 Email: byergatian@bscgroup.com 3.1 Existing Site and Soil Conditions The total project area is approximately 36,662 square feet (0.84 acres) and is located adjacent to Parkers River off Route 28. The project is bounded on the north by the Parker River viewing platform, on the east by privately owned condominiums, and bounded on the south and west by Parker River. The current site is comprised of a retail building with a paved parking area and small areas of vegetation. The primary soil classification identified by the NRCS Web Soil Survey is Carver coarse sand (252A) and Udipsamments (665), which accounts for all of the property and project area. Based on the soil classification identified, runoff calculations have been performed using curve numbers corresponding to Hydrologic Soil Group (HSG) A. 3.2 Project Description and Intended Construction Sequence The site is currently comprised of a commercial retail building. The proposed activities will include the following major components: · The construction of three (3) duplexes with six (6) units, each with garage parking, of a drive aisle, and walkways, · The construction of a stormwater management system, · Site grading and native plantings, and · Utility connections and installation. The proposed project will disturb a total of approximately 35,775± S.F. (0.82± acres). Soil disturbing activities will include site demolition, installing stabilized construction exits, installation of erosion and sedimentation controls, grading, storm drain inlets, stormwater management systems, utilities, building foundation, construction of site driveways and preparation for final landscaping. Please refer to Table 1 for the projects anticipated construction timetable. A description of BMP’s associated with project timetable and construction-phasing elements is provided in this Erosion and Sediment Control Plan. Stormwater Report 703 Route 28 South Yarmouth, MA Table 1 – Anticipated Construction Timetable Construction Phasing Activity Anticipated Timetable Grubbing and Stripping of Limits of Construction Phase To be determined Rough Site Grading and Site Utilities To be determined Utility Plan Construction To be determined Landscaping To be determined 3.3 Potential Sources of Pollution Any project site activities that have the potential to add pollutants to runoff are subject to the requirements of the SWPPP. Listed below are a description of potential sources of pollution from both sedimentation to Stormwater runoff, and pollutants from sources other than sedimentation. Table 2 – Potential Sources of Sediment to Stormwater Runoff Potential Source Activities/Comments Construction Site Entrance and Site Vehicles Vehicles leaving the site can track soils onto public roadways. Site Vehicles can readily transport exposed soils throughout the site and off-site areas. Grading Operations Exposed soils have the potential for erosion and discharge of sediment to off-site areas. Material Excavation, Relocation, and Stockpiling Stockpiling of materials during excavation and relocation of soils can contribute to erosion and sedimentation. In addition, fugitive dust from stockpiled material, vehicle transport and site grading can be deposited in wetlands and waterway. Landscaping Operations Landscaping operations specifically associated with exposed soils can contribute to erosion and sedimentation. Hydroseeding, if not properly applied, can runoff to adjacent wetlands and waterways. Table 3 – Potential Pollutants and Sources, other than Sediment to Stormwater Runoff Potential Source Activities/Comments Staging Areas and Construction Vehicles Vehicle refueling, minor equipment maintenance, sanitary facilities and hazardous waste storage Materials Storage Area General building materials, solvents, adhesives, paving materials, paints, aggregates, trash, etc. Construction Activities Construction, paving, curb/gutter installation, concrete pouring/mortar/stucco 3.4 Erosion and Sedimentation Control Best Management Practices All construction activities will implement Best Management Practices (BMP’s) in order to minimize overall site disturbance and impacts to the sites natural features. Please refer to the following sections for a detailed description of site specific BMP’s. In addition, an Erosion and Sedimentation Control Plan is provided in the Site Plans. 3.5 Timetable and Construction Phasing This section provides the Owner and Contractor with a suggested order of construction that shall minimize erosion and the transport of sediments. The individual objectives of the construction techniques described Stormwater Report 703 Route 28 South Yarmouth, MA herein shall be considered an integral component of the project design intent of each project phase. The construction sequence is not intended to prescribe definitive construction methods and should not be interpreted as a construction specification document. However, the Contractor shall follow the general construction phase principles provided below: · Protect and maintain existing vegetation wherever possible. · Minimize the area of disturbance. · To the extent possible, route unpolluted flows around disturbed areas. · Install mitigation devices as early as possible. · Minimize the time disturbed areas are left unstabilized. · Maintain siltation control devices in proper condition. · The contractor should use the suggested sequence and techniques as a general guide and modify the suggested methods and procedures as required to best suit seasonal, atmospheric, and site specific physical constraints for the purpose of minimizing the environmental impact of construction. Demolition, Grubbing and Stripping of Limits of Construction Phase · Install Temporary Erosion Control (TEC) devices as required to prevent sediment transport into resource areas. · Place a ring of silt socks and/or haybales around stockpiles. · Stabilize all exposed surfaces that will not be under immediate construction. · Store and/or dispose all pavement and building demolition debris as indicated in accordance with all applicable local, state, and federal regulations. Driveway Area Sub-Base Construction · Install temporary culverts and diversion ditches and additional TEC devices as required by individual construction area constraints to direct potential runoff toward detention areas designated for the current construction phase. · Compact gravel as work progresses to control erosion potential. · Apply water to control air suspension of dust. · Avoid creating an erosive condition due to over-watering. · Install piped utility systems as required as work progresses, keeping all inlets sealed until all downstream drainage system components are functional. Binder Construction · Fine grade gravel base and install processed gravel to the design grades. · Compact pavement base as work progresses. · Install pavement binder coat starting from the downhill end of the site and work toward the top. Finish Paving · Repair and stabilize damaged side slopes. · Clean inverts of drainage structures. · Install final top coat of pavement. Final Clean-up · Clean inverts of culverts and catch basins. · Remove sediment and debris from rip-rap outlet areas. · Remove TEC devices only after permanent vegetation and erosion control has been fully established. Stormwater Report 703 Route 28 South Yarmouth, MA 3.6 Site Stabilization Grubbing Stripping and Grading · Erosion control devices shall be in place as shown on the design plans before grading commences. · Stripping shall be done in a manner, which will not concentrate runoff. If precipitation is expected, earthen berms shall be constructed around the area being stripped, with a silt sock, silt fence or haybale dike situated in an arc at the low point of the berm. · If intense precipitation is anticipated, silt socks, haybales, dikes and /or silt fences shall be used as required to prevent erosion and sediment transport. The materials required shall be stored on site at all time. · If water is required for soil compaction, it shall be added in a uniform manner that does not allow excess water to flow off the area being compacted. · Dust shall be held at a minimum by sprinkling exposed soil with an appropriate amount of water. Maintenance of Disturbed Surfaces · Runoff shall be diverted from disturbed side slopes in both cut and fill. · Mulching may be used for temporary stabilization. · Silt sock, haybale or silt fences shall be set where required to trap products of erosion and shall be maintained on a continuing basis during the construction process. Loaming and Seeding · Loam shall not be placed unless it is to be seeded directly thereafter. · All disturbed areas shall have a minimum of 4” of loam placed before seeded and mulched. · Consideration shall be given to hydro-mulching, especially on slopes in excess of 3 to 1. · Loamed and seeded slopes shall be protected from washout by mulching or other acceptable slope protection until vegetation begins to grow. Stormwater Collection System Installation · The Stormwater drainage system shall be installed from the downstream end up and in a manner which will not allow runoff from disturbed areas to enter pipes. · Excavation for the drainage system shall not be left open when rainfall is expected overnight. If left open under other circumstances, pipe ends shall be closed by a staked board or by an equivalent method. · All catch basin openings shall be covered by a silt bag between the grate and the frame or protected from sediment by silt fence surrounding the catch basin grate. · During the installation of the infiltration systems, ensure that loose material from the construction of the town home roof shingles is swept and removed from the area prior to connecting the roof drains to the infiltration systems. No roof drains shall be connected to the infiltration systems until all tributary roof areas have been thoroughly cleared of debris that could impact the infiltration system functions. Completion of Paved Areas · During the placement of sub-base and pavement, the entrance to the Stormwater drainage systems shall be sealed when rain is expected. When these entrances are closed, consideration must be given to the direction of run-off and measures shall be undertaken to minimize erosion and to provide for the collection of sediment. · In some situations, it may be necessary to keep catch basins open. · Appropriate arrangements shall be made downstream to remove all sediment deposition. Stormwater Report 703 Route 28 South Yarmouth, MA Stabilization of Surfaces · Stabilization of surfaces includes the placement of pavement, rip-rap, wood bark mulch and the establishment of vegetated surfaces. · Upon completion of construction, all surfaces shall be stabilized even though it is apparent that future construction efforts will cause their disturbance. · Vegetated cover shall be established during the proper growing season and shall be enhanced by soil adjustment for proper pH, nutrients and moisture content. · Surfaces that are disturbed by erosion processes or vandalism shall be stabilized as soon as possible. · Areas where construction activities have permanently or temporarily ceased shall be stabilized within 14 days from the last construction activity, except when construction activity will resume within 21 days (e.g., the total time period that construction activity is temporarily ceased is less than 21 days). · Hydro-mulching of grass surfaces is recommended, especially if seeding of the surfaces is required outside the normal growing season. · Hay mulch is an effective method of temporarily stabilizing surfaces, but only if it is properly secured by branches, weighted snow fences or weighted chicken wire. 3.7 Temporary Structural Erosion Control Measures Temporary erosion control measures serve to minimize construction-associated impacts to wetland resource and undisturbed areas. Please refer to the following sections for a description of temporary erosion control measures implemented as part of the project and this sample SWPPP. 3.7.1 Silt Socks, Haybales, and Silt Fencing The siltation barriers will demarcate the limit of work, form a work envelope and provide additional assurance that construction equipment will not enter the adjacent wetlands or undisturbed portions of the site. All barriers will remain in place until disturbed areas are stabilized. 3.7.2 Temporary Stormwater Diversion Swale A temporary diversion swale is an effective practice for temporarily diverting stormwater flows and to reduce stormwater runoff velocities during storm events. The swale channel can be installed before infrastructure construction begins at the site, or as needed throughout the construction process. The diversion swale should be routinely compacted or seeded to minimize the amount of exposed soil. 3.7.3 Dewatering Basins Dewatering may be required during stormwater system, foundation construction and utility installation. Should the need for dewatering arise, groundwater will be pumped directly into a temporary settling basin, which will act as a sediment trap during construction. All temporary settling basins will be located within close proximity of daily work activities. Prior to discharge, all groundwater will be treated by means of the settling basin or acceptable substitute. Discharges from sediment basins will be free of visible floating, suspended and settleable solids that would impair the functions of a wetland or degrade the chemical composition of the wetland resource area receiving ground or surface water flows and will be to the combined system. 3.7.4 Material Stockpiling Locations Piping and trench excavate associated with the subsurface utility work will be contained with a single row of silt socks and/or haybales. Stormwater Report 703 Route 28 South Yarmouth, MA 3.8 Permanent Structural Erosion Control Measures Permanent erosion control measures serve to minimize post-construction impacts to wetland resource areas and undisturbed areas. Please refer to the Site Plans and Long-Term Operations and Maintenance Plan for a description of permanent erosion control measures implemented as part of the project and this SWPPP. 3.9 Good Housekeeping Best Management Practices 3.9.1 Street Sweeping Route 28 in front of the project property shall be swept clean on a daily basis at the conclusion of the work day of any soils tracked onto it from the project site. All sweepings shall be disposed of off-site in accordance with all applicable laws and regulations. 3.9.2 Material Handling and Waste Management Solid waste generation during the construction period will be primarily construction debris. The debris will include scrap lumber (used forming and shoring pallets and other shipping containers), waste packaging materials (plastic sheeting and cardboard), scrap cable and wire, roll-off containers (or dumpsters) and will be removed by a contract hauler to a properly licensed landfill. The roll-off containers will be covered with a properly secured tarp before the hauler exits the site. In addition to construction debris, the construction work force will generate some amount of household-type wastes (food packing, soft drink containers, and other paper). Trash containers for these wastes will be located around the site and will be emptied regularly so as to prevent wind-blown litter. This waste will also be removed by a contract hauler. All hazardous waste material such as oil filters, petroleum products, paint and equipment maintenance fluids will be stored in structurally sound and sealed shipping containers in the hazardous-materials storage area and segregated from other non-waste materials. Secondary containment will be provided for all materials in the hazardous materials storage area and will consist of commercially available spill pallets. Additionally, all hazardous materials will be disposed of in accordance with federal, state and municipal regulations. Two temporary sanitary facilities (portable toilets) will be provided at the site in the combined staging area. The toilets will be away from a concentrated flow path and traffic flow and will have collection pans underneath as secondary treatment. All sanitary waste will be collected from an approved party at a minimum of three times per week. 3.9.3 Building Material Staging Areas Construction equipment and maintenance materials will be stored at the combined staging area and materials storage areas. Silt fence will be installed around the perimeter to designate the staging and materials storage area. A watertight shipping container will be used to store hand tools, small parts and other construction materials. Non-hazardous building materials such as packaging material (wood, plastic and glass) and construction scrap material (brick, wood, steel, metal scraps, and pine cuttings) will be stored in a separate covered storage facility adjacent to other stored materials. All hazardous-waste materials such as oil filters, petroleum products, paint and equipment maintenance fluids will be stored in structurally sound and sealed containers under cover within the hazardous materials storage area. Large items such as framing materials and stockpiled lumber will be stored in the open storage area. Such materials will be elevated on wood blocks to minimize contact with runoff. The combined storage areas are expected to remain clean, well-organized and equipped with ample cleaning supplies as appropriate for the materials being stored. Perimeter controls such as containment structures, covers and liners will be repaired or replaced as necessary to maintain proper function. Stormwater Report 703 Route 28 South Yarmouth, MA 3.9.4 Designated Washout Areas Designated temporary, below-ground concrete washout areas will be constructed, as required, to minimize the pollution potential associated with concrete, paint, stucco, mixers etc. Signs will, if required, be posted marking the location of the washout area to ensure that concrete equipment operators use the proper facility. Concrete pours will not be conducted during or before an anticipated precipitation event. All excess concrete and concrete washout slurries from the concrete mixer trucks and chutes will be discharged to the washout area or hauled off-site for disposal. 3.9.5 Equipment/Vehicle Maintenance and Fueling Areas 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. All major equipment/vehicle fueling and maintenance will be performed off-site. A small, 20-gallon pickup bed fuel tank will be kept on-site in the combined staging area. When vehicle fueling must occur on-site, the fueling activity will occur in the staging area. Only minor equipment maintenance will occur on-site. . All equipment fluids generated from maintenance activities will be disposed of into designated drums stored on spill pallets. Absorbent, spill-cleanup materials and spill kits will be available at the combined staging and materials storage area. Drip pans will be placed under all equipment receiving maintenance and vehicles and equipment parked overnight. 3.9.6 Equipment/Vehicle Wash down Area All equipment and vehicle washing will be performed off-site. 3.9.7 Spill Prevention Plan A spill containment kit will be kept on-site in the Contractor’s trailer and/or the designated staging area throughout the duration of construction. Should there be an accidental release of petroleum product into a resource area, the appropriate agencies will be immediately notified. 3.9.8 Inspections Maintenance of existing and proposed BMP’s to address stormwater management facilities during construction is an on-going process. The purpose of the inspections is to observe all sources of stormwater or non-stormwater discharge as well as the status of the receiving waters. The following sections describe the appropriate inspection measures to adequately implement the project’s SWPPP. A blank sample inspection form is provided at the end of this section. Completed inspection forms are to be maintained on site. Inspection Personnel The owner’s appointed representative will be responsible for performing regular inspections of erosion controls and ordering repairs as necessary. Inspection Frequency Inspections will be performed by qualified personnel once every 7 days, in accordance with the CGP. The inspections must be documented on the inspection form provided at the end of this section, and completed forms will be provided to the on-site supervisor and maintained at the Owner’s office throughout the entire duration of construction. Inspection Reporting Each inspection report will summarize the scope of the inspection, name(s) and qualifications of personnel making the inspection, and major observations relating to the implementation of the SWPPP, including compliance and non-compliance items. Completed inspection reports will remain with the completed SWPPP on site. Stormwater Report 703 Route 28 South Yarmouth, MA 3.9.9 Amendment Requirements The final SWPPP is intended to be a working document that is utilized regularly on the construction site, and provides guidance to the Contractor. It must reflect changes made to the originally proposed plan and will be updated to include project specific activities and ensure that they are in compliance with the state and local laws and regulations. It should be amended whenever there is a change in design, construction, operation or maintenance that affects discharge of pollutants. The following items should be addressed should an amendment to the SWPPP occur: · Dates of certain construction activities such as major grading activities, clearing and initiation of and completion of stabilization measures should be recorded. · Future amendments to the SWPPP will be recorded as required. As this SWPPP is amended, all amendments will be kept on site and made part of the SWPPP. · Upon completion of site stabilization (completed as designed and/or 70% background vegetative cover), it can be documented and marked on the plans. Inspections are no longer required at this time. · Inspections often identify areas not included in the original SWPPP, which will require the SWPPP to be amended. These updates should be made within seven days of being recognized by the inspector. 3.11 SWPPP Inspection and Maintenance Report The following form is an example to be used for SWPPP Inspection Reporting. Stormwater Report 703 Route 28 South Yarmouth, MA Stormwater Construction Site Inspection and Maintenance Report TO BE COMPLETED AT LEAST EVERY 7 DAYS. AFTER SITE STABILIZATION, TO BE COMPLETED AT LEAST ONCE PER MONTH FOR THREE YEARS OR UNTIL A NOTICE OF TERMINATION IS FILED (IF APPLICABLE). General Information Project Name 703 Route 28 Redevelopment NPDES Tracking No. (if applicable) Location 703 Route 28 South Yarmouth, MA Date of Inspection Start/End Time Inspector’s Name(s) Inspector’s Title(s) Inspector’s Contact Information Inspector’s Qualifications Describe present phase of construction Type of Inspection:  Regular  Pre-storm event  During storm event  Post-storm event Weather Information Has there been a storm event since the last inspection? Yes No If yes, provide: Storm Start Date & Time: Storm Duration (hrs): Approximate Amount of Precipitation (in): Weather at time of this inspection?  Clear Cloudy  Rain  Sleet  Fog  Snowing  High Winds  Other: Temperature: Have any discharges occurred since the last inspection? Yes No If yes, describe: Are there any discharges at the time of inspection? Yes No If yes, describe: Site-specific BMPs · Number the structural and non-structural BMPs identified in your SWPPP on your site map and list them below (add as many BMPs as necessary). Carry a copy of the numbered site map with you during your inspections. This list will ensure that you are inspecting all required BMPs at your site. · Describe corrective actions initiated, date completed, and note the person that completed the work in the Corrective Action Log. BMP BMP Installed? BMP Maintenance Required? Corrective Action Needed and Notes Action required by whom and when 1 Catch Basin Protection Yes No Yes No 2 Haybale & Silt Fencing Yes No Yes No Stormwater Report 703 Route 28 South Yarmouth, MA BMP BMP Installed? BMP Maintenance Required? Corrective Action Needed and Notes Action required by whom and when 3 Straw Wattles Yes No Yes No 4 Construction Entrance Yes No Yes No 5 Sediment Basins Yes No Yes No 6 Dewatering Pit Yes No Yes No 7 Yes No Yes No Overall Site Issues Below are some general site issues that should be assessed during inspections. Customize this list as needed for conditions at your site. BMP/activity Implemented? Maintenance Required? Corrective Action Needed and Notes Action required by whom and when 1 Are all slopes and disturbed areas not actively being worked properly stabilized? Yes No Yes No 2 Are natural resource areas (e.g., streams, wetlands, mature trees, etc.) protected with barriers or similar BMPs? Yes No Yes No 3 Are perimeter controls and sediment barriers adequately installed (keyed into substrate) and maintained? Yes No Yes No Stormwater Report 703 Route 28 South Yarmouth, MA BMP/activity Implemented? Maintenance Required? Corrective Action Needed and Notes Action required by whom and when 4 Are discharge points and receiving waters free of any sediment deposits? Yes No Yes No 5 Are storm drain inlets properly protected? Yes No Yes No 6 Is the construction exit preventing sediment from being tracked into the street? Yes No Yes No 7 Is trash/litter from work areas collected and placed in covered dumpsters? Yes No Yes No 8 Are washout facilities (e.g., paint, stucco, concrete) available, clearly marked, and maintained? Yes No Yes No 9 Are vehicle and equipment fueling, cleaning, and maintenance areas free of spills, leaks, or any other deleterious material? Yes No Yes No Vehicle Maintenance not allowed on site 10 Are materials that are potential stormwater contaminants stored inside or under cover? Yes No Yes No 11 Are non-stormwater discharges (e.g., wash water, dewatering) properly controlled? Yes No Yes No 12 (Other) Yes No Yes No Non-Compliance Describe any incidents of non-compliance not described above: Stormwater Report 703 Route 28 South Yarmouth, MA CERTIFICATION STATEMENT “I certify under penalty of law that this document and all attachments were prepared under my direction or supervision in accordance with a system designed to assure that qualified personnel properly gathered and evaluated the information submitted. Based on my inquiry of the person or persons who manage the system, or those persons directly responsible for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and complete. I am aware that there are significant penalties for submitting false information, including the possibility of fine and imprisonment for knowing violations.” Print name and title: . (Qualified Person Performing the Inspection) Signature:_____________________________________________________ Date: . Print name and title: __________________________________________________________________________ (Contractor/Operator) Signature:______________________________________________________ Date: Stormwater Report 703 Route 28 South Yarmouth, MA SECTION 4.0 LONG-TERM POLLUTION PREVENTION & OPERATION AND MAINTENANCE PLAN Stormwater Report 703 Route 28 South Yarmouth, MA 4.0 LONG-TERM POLLUTION PREVENTION & OPERATION AND MAINTENANCE PLAN As required by Standard #4 of the Stormwater Management Policy, this Long-Term Pollution Prevention Plan has been developed for source control and pollution prevention at the site after construction. MAINTENANCE RESPONSIBILITY Ensuring that the provisions of the Long-Term Pollution Prevention Plan are followed will be the responsibility of Steven M. Katz, the owner. GOOD HOUSEKEEPING PRACTICES The site to be kept clean of trash and debris at all times. Trash, junk, etc. is not to be left outside. VEHICLE WASHING CONTROLS The following BMP’s, or equivalent measures, methods or practices are required if you are engaged in vehicle washing and/or steam cleaning: It is allowable to rinse down the body or a vehicle, including the bed of a truck, with just water without doing any wash water control BMP’s. If you wash (with mild detergents) on an area that infiltrates water, such as gravel, grass, or loose soil, it is acceptable to let the wash water infiltrate as long as you only wash the body of vehicles. However, if you wash on a paved area and use detergents or other cleansers, or if you wash/rinse the engine compartment or the underside of vehicles, you must take the vehicles to a commercial vehicle wash. REQUIREMENTS FOR ROUTINE INSPECTIONS AND MAINTENANCE OF STORMWATER BMPS All stormwater BMPs are to be inspected and maintain as follows; Haybales, Silt Fence, and other temporary measures The temporary erosion control measures will be installed up gradient of any wetland resource area where any disturbance or alteration might otherwise allow for erosion or sedimentation. They will be regularly inspected to ensure that they are functioning adequately. Additional supplies of these temporary measures will be stockpiled on site for any immediate needs or routine replacement. Water Quality Treatment Units The water quality treatment structures require periodic inspection and cleaning to maintain operation and function. Owners should have these units inspected on a semi-annual basis and after periods of intense precipitation. Inspections can be done by using a clear Plexiglas tube (“sludge judge”) to extract a water column sample. When sediment accumulation reaches 15% of storage capacity, cleaning of the unit is required. These water quality structures must and will be checked and cleaned immediately after petroleum spills; contact appropriate regulatory agencies. Maintenance of these units should be done by a vacuum truck that will remove the water, sediment, debris, floating hydrocarbons and other materials in unit. Proper cleaning and disposal of the removed materials and liquid must be followed. Underground Infiltration Systems Maintenance is required for the proper operation of the underground infiltration system. Infiltration systems are prone to failure due to clogging if the upstream water quality units are not maintained. The use of pretreatment BMPs will minimize failure and maintenance requirements. After construction, the infiltration system shall be inspected after every major storm for the first few months to ensure proper stabilization and function. Water levels in the access ports shall be recorded over several days to check the Stormwater Report 703 Route 28 South Yarmouth, MA drainage of the systems. It is recommended that a log book be maintained showing the depth of water in the detention/infiltration systems at each observation in order to determine the rate at which the system dewaters after runoff producing storm events. Once the performance characteristics of the detention/infiltration have been verified, the monitoring schedule can be reduced to an annual basis, unless the performance data suggests that a more frequent schedule is required. Preventive maintenance on the infiltration system shall be performed at least twice a year, and sediment shall be removed from any and all pretreatment and collection structures. Sediment shall be removed when deposits approach within six inches of the invert heights of connecting pipes between unit rows, or in sumped inlet structures. Ponded water inside the systems (as visible from the access ports) that remains after several days most likely indicates that the bottom of the system is clogged and will require cleaning or replacement. The system is designed with a defined top portal area at the “down-flow” end of the chamber that can be cut out to accept up to a 10-inch diameter riser pipe. The 10-inch riser can be used as an observation well and as access for a vacuum truck tube for use in removing sediment. The “down flow” ends of the units have end walls that are closed on the bottom. The closed bottom functions like a coffer dam, with most of the sediment depositing prior to flowing into the next chamber, facilitating its removal through the riser pipe, which is positioned directly above this area. In addition to the routine maintenance described above, an operation and maintenance log. This log must be maintained for a minimum of three years after construction of the system, and include inspection reports and notes on any repairs, replacement, and disposal (including material and location). This log must be made available to MassDEP and the Conservation Commission upon request. In addition, members and agents of MassDEP shall be allowed to enter and inspect the property and drainage system to ensure compliance with this O&M plan. PROVISIONS FOR MAINTENANCE OF LAWNS, GARDENS AND OTHER LANDSCAPE AREAS Suggested Maintenance Operations A. Trees and Shrubs Disease and Pest Management - Prevention of disease or infestation is the first step of Pest Management. A plant that is in overall good health is far less susceptible to disease. Good general landscape maintenance can reduce problems from disease. Inspections of plant materials for signs of disease or infestation are to be performed monthly by the Landscape Maintenance Contractor’s Certified Arborist. This is a critical step for early diagnosis. Trees and Shrubs that have been diagnosed to have a plant disease or an infestation of insect pests are to be treated promptly with an appropriate material by a licensed applicator. Fertilization - Trees and shrubs live outside their natural environment and should be given proper care to maintain health and vigor. Fertilizing trees and shrubs provides the plants with nutrients needed to resist insect attack, to resist drought and to grow thicker foliage. Fertilizing of new and old trees may be done in one of three ways, in either the early spring or the late fall. · Systemic Injection of new and existing trees on trees 2 inches or greater in diameter. You must be licensed to apply this method. · Soil Injection – a liquid fertilizer with a product such as Arbor Green or Rapid Grow injected into the soil under the drip zone of a tree or shrub. Material must be used according to manufacturers’ specifications to be effective. Outside contracting is recommended. · Punch Bar Method – a dry fertilizer such as 10-10-10, may be used by punched holes in the drip zone of the tree 12-18” deep, two feet apart around the circumference, to the edge of the drip line. Three pounds of fertilizer should be used per diameter inch for trees with trunks six inches or more in diameter. · Fertilizer of shrubs – use a fertilizer such as 10-10-10, broadcast over the planting area according to the manufacturers’ rate and water in. · All fertilization must be noted on daily maintenance log. Stormwater Report 703 Route 28 South Yarmouth, MA Watering - Trees and Shrubs will need supplemental watering to remain in vigorous health. All new plants need to be watered once a week in cool weather, twice a week during warm weather, and up to three times in a week during periods of extreme heat and drought. Trees and shrubs should be watered in such a manner as to totally saturate the soil in the root zone area. Over-watering or constant saturation of the soil must be avoided as this could lead to root rot and other disease problems. The use of a soil moisture meter can help you monitor the soil’s water intake. Plant Replacement - Unhealthy plants that may cause widespread infestation of other nearby plants shall be immediately removed from the site. Any vegetation removed from the site must be recorded and submitted with the daily maintenance log. The area shall be treated to prevent further infestation. The plant shall then be replaced with a healthy specimen of the same species and size. This work shall have a pre-established budget allowance for the year. A spring inspection of all plant materials shall be performed to identify those plant materials that are not in vigorously healthy condition. Unhealthy plant materials shall be evaluated. If the problem is determined to be minor the plant material shall be given appropriate restorative care in accordance with this maintenance guideline until it is restored to a vigorously healthy condition. Unhealthy plant materials that do not respond to restorative care or are determined to be beyond saving shall be replaced with a healthy specimen of the same species and size. In the case of the necessity of replacing extremely large plant materials the Landscape Architect shall determine the size of the replacement plant. Pruning - Proper pruning is the selective removal of branches without changing the plant’s natural appearance, or habit of growth. All tree pruning is to be performed by a licensed Arborist. All branches that are dead, broken, scared or crossing should be removed. All cuts should be made at the collar and not cut flush with the base. Pruning on the site shall be done for the following purposes; · To maintain or reduce the size of a tree or shrub · To remove dead, diseased or damaged branches · To rejuvenate old shrubs and encourage new growth · To stimulate future flower and fruit development · To maximize the visibility of twig color · To prevent damage and reduce hazards to people and properties All shrubs are recommended to be pruned on an annual basis to prevent the shrub from becoming overgrown and eliminate the need for drastic pruning. There are several types of pruning for deciduous shrubs. Hand snips should be used to maintain a more natural look or hand shears can be used for a more formal appearance. Winter Protection - All trees and shrubs are to be watered, fertilized, and mulched before the first frost. All stakes should be checked and ties adjusted. Damaged branches should be pruned. Broadleaf and Coniferous Evergreen plant materials are to be sprayed with an anti-desiccant product to prevent winter burn. The application shall be repeated during a suitable mid-winter thaw. Shrubs located in areas likely to be piled with snow during snow removal (but not designated as Snow Storage Areas) shall be marked by six-foot high poles with bright green banner flags. Stockpiles of snow are not to be located in these areas due to potential damage to the plant materials from both the weight of the snow and the snow melting chemicals. At the fall landscape maintenance conference parameters will be discussed between the Landscape Maintenance Contractor and the snow removal contractor to assure minimal damage and loss of landscape amenities during the winter season. Seasonal Clean Up - A thorough spring cleanup is to be performed. This includes the removal and replacement of dead or unhealthy plant materials and the cleanup of plant debris and any general debris that has accumulated over the winter season. Mulch is to be lightly raked to clean debris from the surface without removing any mulch. Twigs and debris are to be removed from the planting beds throughout the growing season. Mulching - Planting beds shall be mulched with a treated shredded hardwood mulch free from dirt, debris, and insects. A sample of this mulch shall be given to the Owner for approval prior to installation. Stormwater Report 703 Route 28 South Yarmouth, MA Maintain a 2-3” maximum depth and keep free of weeds either by hand weeding or by the use of a pre-emergent weed control such as Treflan or Serfian. Seasonal re-mulching shall occur as necessary in the spring and the fall to maintain this minimum depth. When new mulch is added to the planting bed it shall be spread to create a total depth of no more than three inches. Edges should be maintained in a cleanly edged fashion. Mulch shall not be placed directly against the trunk of any tree or shrub. B. Groundcover and Perennials Disease and Pest Management – Pesticides and herbicides should be applied only as problems occur, with the proper chemical applied only by a trained professional or in the case of pesticide, a Certified Pesticide Applicator. Plants should be monitored weekly and treated accordingly. Fertilizer – The health of the plants can be maintained or improved, and their growth encouraged by an application of complete fertilizer. Apply a fertilizer such as 4-12-4 as growth becomes apparent and before mulching. Apply to all groundcover and perennial planting areas by hand and avoid letting the fertilizer come in contact with the foliage, or use a liquid fertilizer and apply by soaking the soil. Apply according to the manufacturers’ specifications. Fertilization shall stop at the end of July. Water – Groundcovers and Perennials will need supplemental watering in order to become established, healthy plants. All new plants need to be watered once a week in cool weather, twice a week during warm weather, and up to three times in a week during periods of extreme heat and drought. Until established, groundcovers and perennials should be watered in such a manner as to totally saturate the soil in the root zone area, to a depth of 6 inches. Once established, perennials shall continue to be watered as necessary to maintain them in a vigorous healthy condition. Over-watering or constant saturation of the soil must be avoided as this could lead to root rot and other disease problems. The use of a soil moisture meter can help you monitor the soil’s water intake. On-site water shall be furnished by the Owner. Hose and other watering equipment shall be furnished by the Landscape Maintenance Contractor. Replacement – Any unhealthy plant/s that may cause widespread infestation of other nearby plants shall be immediately removed from the site. Any vegetation removed from the site must be recorded and submitted with the landscape maintenance log. The area shall be treated to prevent further infestation. The plant/s shall then be replaced with healthy specimen/s of the same species and size. Old Forge shall have a pre-established budget allowance for this type of replacement, each year. Plant material that is damaged as a result of other landscape maintenance activities, such as mowing, shall be replaced with healthy specimens of the same species and size, at no additional cost to the owner. Deadheading – Perennials shall be checked on a weekly basis and dead-headed once flowers have faded or as necessary based on plant type and duration of flower. Spent flowers can be pinched off with the thumb and forefinger. Continue to remove all faded flowers until Fall. All associated debris shall be removed from site daily. Staking – Upright-growing perennials need support especially when in flower. Use of bamboo stakes, galvanized wire hoops or mesh may be necessary for their support. Supports should be put in place before they have become too difficult to handle. The supports should not be taller than the mature height of the perennial plant. Division of Perennials – Two or three-year-old perennials are easily divided in the spring if more plants are needed. To divide, cut out the entire section of plant to be divided, including roots. The larger divisions (those with three or more shoots), can be set out immediately in their permanent location, where they can be expected to bloom the same season. Smaller divisions are best planted in an out-of-the-way planting bed until the following autumn or spring, when they can be moved to their permanent location. Weeding – All planting beds should be kept weed-free. Weed either by hand or with a pre-emergent herbicide such as Treflen used according to manufacturers’ specifications. Manual weeding is to be used in combination with the use of spot applications of herbicides. Both live and dead weeds are to be pulled and removed from the site. Stormwater Report 703 Route 28 South Yarmouth, MA All herbicide applications shall be documented in the Landscape Maintenance Log. The actual product label or the manufacturer’s product specification sheet for the specific product shall also be included in the Log. Only personnel with appropriate applicator licenses shall supervise and/or perform the application of pesticide products requiring a license. Winterizing – Perennial gardens should be cleaned-up when growth ceases in the fall. Remove foliage of plants that normally die down to the ground. Divide and replant over-grown clumps. C. Lawn Areas - Turf Systems Mowing – Proper mowing is an integral part of any good turf maintenance program. Without it, the finest in fertilization, watering and other vital maintenance practices would be completely ineffective. Proper mowing will help control dicot weeds; help the turf survive during periods of extreme heat, and gain strength and vigor to resist disease and other infestations. Mowing height – The proper mowing height will vary somewhat according to the type of grass. The most common type of seed & sod lawns contain a mixture of bluegrass, fine fescue and perennial rye, which should be mowed at 2-3 inches. Mowing frequency – The basic rule of thumb for mowing frequency is to never remove more than 1/3 of the grass blade in one mowing. Example: if you want to mow your turf at 2 inches, you should cut it when it reaches 3 inches. Removing more than ½ of the grass plant at a time can put the plant into shock, thus making it more susceptible to stress disease and weed infestation. Mowing frequency will vary with the growing season and should be set by the plant height and not a set date. It will often be necessary to mow twice a week during periods of surge growth to help maintain plant health and color. Mowing should be cut back during periods of stress. Grass clippings should be removed whenever they are thick enough to layer the turf. The return of clippings to the soil actually adds nutrients and helps retain moisture. Heavily clumped grass clippings are a sign of infrequent mowing, calling for an adjustment in the mowing schedule. When mowing any area, try to alternate mowing patterns. This tends to keep grass blades more erect and assures an even cut. A dull mower will cause color loss due to tearing of the turf plant, and since mowing will ultimately determine the appearance of any turf area there is an absolute necessity for a clean sharp cut. Weed & Pest Control and Fertilizing- In order to maintain turf grass health, vigor color, and nutrients, fertilizer must be added to the soil. Recommendations for fertilization of lawn areas are as follows; fertilize at the rate of one (1) pound of nitrogen per thousand square feet, per year is optimum. Fertilizer should be a balanced slow release, sulfur coated type fertilizer. Weed Control - All turf areas will require some weed control, for both weed grasses and dicot weeds. Weeds should be treated at the appropriate time and with a material labeled for the target weed. Please refer to the fertilizer weed and pest schedule for timing. Pest Control - All turf areas will require some pest control. Pests should be treated at the appropriate time with a material labeled for the target pest. Please refer to the fertilizer, weed and pest schedule for timing. Lime - A common cause for an unhealthy lawn is acidic soil. When the pH is below the neutral range (between 6-7) vital plant nutrients become fixed in the soil and cannot be absorbed by the grass plant. Lime corrects an acid soil condition, supplies calcium for plant growth and improves air and water circulation. Limestone applied at the rate of 50 lbs. per thousand square feet will adjust the soil pH one point over a period of 6-9 months. D. Fertilizer, Weed & Pest Control Schedule – Turf Systems Spring - Fertilize one (1) pound of nitrogen per 1,000 square feet (April) Pre-emergent weed grass control Stormwater Report 703 Route 28 South Yarmouth, MA Broadleaf weed control Late Spring - Fertilize one (1) pound of nitrogen per 1,000 square feet (June) Pre-emergent weed grass control Broadleaf weed control Insect Control (if needed) *Summer - Fertilize one (1) pound of nitrogen per 1,000 square feet (August) Broadleaf weed control (if needed) Insect Control (if needed) Fall - Fertilize one (1) pound of nitrogen per 1,000 square feet (September) *Omit if area is not to be irrigated Lawn Maintenance Task Schedule MARCH (Weather permitting) · Clean up winter debris, sand, leaves, trash etc. · Re-edge mulch beds, maintain at 2-3” maximum. · Fertilize plants · Aerate and thatch turf (conditions permitting) APRIL · Reseed or sod all areas needing attention. · Fertilize and weed control · Lime · Start mowing when grass reaches 2-1/2”, mow to 2” MAY · Mow turf to 2-2-1/2” · Weed as necessary. · Check for disease and pest problems in both turf and plants. JUNE · Mow turf to 2-1/2” – 3” · Fertilize and weed control. · Weed · Check for disease and pest problems in both turf and plants, treat as necessary. PROVISIONS FOR SOLID WASTE MANAGEMENT (SITE TRASH) Trash will be placed in on-site dumpsters and the Owner will make provisions for its regular and timely removal. SNOW DISPOSAL AND PLOWING PLANS The purpose of the snow and snowmelt management plan is to provide guidelines regarding snow disposal site selection, site preparation and maintenance that are acceptable to the Department of Environmental Protection. For the areas that require snow removal, snow storage onsite will largely be accomplished by using pervious areas along the shoulder of the roadway and development as windrowed by plows. Stormwater Report 703 Route 28 South Yarmouth, MA · Avoid dumping of snow into any water body, including rivers, ponds, or wetlands. In addition to water quality impacts and flooding, snow disposed of in open water can cause navigational hazards when it freezes into ice blocks. · Avoid disposing of snow on top of storm drain catch basins or in stormwater basins. Snow combined with sand and debris may block a storm drainage system, causing localized flooding. A high volume of sand, sediment, and litter released from melting snow also may be quickly transported through the system into surface water. · In significant storm events, the melting or off-site trucking of snow may be implemented. These activities shall be conducted in accordance with all local, state and federal regulations. · Snow shall be removed from the areas around on-site fire-hydrants to maintain emergency access to hydrants at all times. Removable flags or markers should be placed on hydrants to allow snow removal crews to more easily locate hydrants and not damage them with plows or other snow removal equipment. WINTER ROAD SALT AND/OR SAND USE AND STORAGE RESTRICTIONS The applicant will be responsible for sanding and salting the site. No storage on site. STREET SWEEPING SCHEDULES There are three types of sweepers: Mechanical, Regenerative Air, and Vacuum Filter. 1) Mechanical: Mechanical sweepers use brooms or rotary brushes to scour the pavement. 2) Regenerative Air: These sweepers blow air onto the road or parking lot surface, causing fines to rise where they are vacuumed. 3) Vacuum filter: These sweepers remove fines along roads. Two general types of vacuum filter sweepers are available - wet and dry. The dry type uses a broom in combination with the vacuum. The wet type uses water for dust suppression Regardless of the type chosen, the efficiency of street sweeping is increased when sweepers are operated in tandem. This project has not included street sweeping as part of the TSS removal calculations. However, it is recommended that street sweeping of the parking areas occur two times a year, including once after the spring snow melt. Reuse and Disposal of Street Sweepings Once removed from paved surfaces, the sweepings must be handled and disposed of properly. Mass DEP’s Bureau of Waste Prevention has issued a written policy regarding the reuse and disposal of street sweepings. These sweepings are regulated as a solid waste, and can be used in three ways: · In one of the ways already approved by Mass DEP (e.g., daily cover in a landfill, additive to compost, fill in a public way) · If approved under a Beneficial Use Determination · Disposed in a landfill TRAINING OF STAFF OR PERSONNEL INVOLVED WITH IMPLEMENTING LONG-TERM POLLUTION PREVENTION PLAN The Long-Term Pollution Prevention Plan is to be implemented by property owner of the site. Trained and, if required, licensed Professionals are to be hired by the owner as applicable to implement the Long-Term Pollution Prevention Plan. LIST OF EMERGENCY CONTACTS FOR IMPLEMENTING LONG-TERM POLLUTION PREVENTION PLAN The applicant will be required to implement the Long-Term Pollution Prevention Plan and will create and maintain a list of emergency contacts. Stormwater Report 703 Route 28 South Yarmouth, MA POST CONSTRUCTION PHASE INSPECTION SCHEDULE AND EVALUATION CHECKLIST Inspection Date Inspector BMP Inspected Inspection Frequency Requirement s Comments Recommendation Follow-up Inspection Required (yes/no) Water Quality Units Four times a year Infiltration System Twice a year 1. Refer to the Massachusetts Stormwater Handbook Volume Two: Stormwater Technical Handbook (February 2008) for recommendations regarding frequency for inspections and maintenance of specific BMP’s 2. Inspections to be conducted by a qualified professional such as an environmental scientist or civil engineer. 3. Limited or no use of sodium chloride salts, fertilizers or pesticides recommended. 4. Other Notes: (Include deviations from Conservation Commission Approvals, Planning Board Approvals and Approved Plans) Stormwater Report 703 Route 28 South Yarmouth, MA SECTION 5.0 HYDROLOGY CALCULATIONS Stormwater Report 703 Route 28 South Yarmouth, MA 5.01 EXISTING WATERSHED PLAN G G G G G G G G G G G OHWOHWOHWWOHW OHW OHW OHW OHW OHW OHWOHW(PUBL I C V A R I A B L E W I D T H ) MAIN S T R E E T - S T A T E R O U T E 2 8 PARKERS R IVERPARKERS RIVERS(PRIV A T E 4 0' WI D E ) MERM A I D L A N ENAD 83 MA MAINLANDWWWWGGGGGGGGGEXISTING CONDITIONS WATERSHED MAP EWAM 349 Main Street - Route 28 West Yarmouth, Massachusetts 02673 508 778 8919 IN ISSUED FOR PERMITTING NOT FOR CONSTRUCTION 703 ROUTE 28 REDEVELOPMENT SOUTH YARMOUTH MASSACHUSETTS (BARNSATBLE COUNTY) DECEMBER 22, 2025 Stormwater Report 703 Route 28 South Yarmouth, MA 5.02 EXISTING HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) EX1Off-Site (Parkers River)DP1Parkers RiverRouting Diagram for 010126400-EWAMPrepared by BSC Group, Printed 12/22/2025HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSubcatReachPondLinkEWAM010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 2HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCRainfall Events ListingEvent# EventNameStorm Type Curve Mode Duration(hours)B/B Depth(inches)AMC1 2-year NOAA 24-hr A Default 24.00 1 3.37 22 10-year NOAA 24-hr A Default 24.00 1 4.90 23 25-year NOAA 24-hr A Default 24.00 1 5.86 24 50-year NOAA 24-hr A Default 24.00 1 6.58 25 100-year NOAA 24-hr A Default 24.00 1 7.33 2 EWAM010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 3HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCArea Listing (all nodes)Area(sq-ft)CN Description(subcatchment-numbers)13,759 39 >75% Grass cover, Good, HSG A (EX1)15,201 98 Paved parking, HSG A (EX1)5,742 98 Roofs, HSG A (EX1)34,702 75 TOTAL AREAEWAM010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 4HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSoil Listing (all nodes)Area(sq-ft)SoilGroupSubcatchmentNumbers34,702 HSG A EX10 HSG B0 HSG C0 HSG D0 Other34,702 TOTAL AREA EWAM010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 5HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCGround Covers (all nodes)HSG-A(sq-ft)HSG-B(sq-ft)HSG-C(sq-ft)HSG-D(sq-ft)Other(sq-ft)Total(sq-ft)GroundCover13,759 0 0 0 0 13,759 >75% Grass cover, Good15,201 0 0 0 0 15,201 Paved parking5,742 0 0 0 0 5,742 Roofs34,702 0 0 0 0 34,702 TOTAL AREAEWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 6HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=5.00-20.00 hrs, dt=0.05 hrs, 301 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=34,702 sf 60.35% Impervious Runoff Depth>1.13"Subcatchment EX1: Off-Site (Parkers Tc=6.0 min CN=75 Runoff=1.63 cfs 3,280 cf Inflow=1.63 cfs 3,280 cfPond DP1: Parkers River Primary=1.63 cfs 3,280 cfTotal Runoff Area = 34,702 sf Runoff Volume = 3,280 cf Average Runoff Depth = 1.13"39.65% Pervious = 13,759 sf 60.35% Impervious = 20,943 sf EWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 7HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment EX1: Off-Site (Parkers River)Runoff = 1.63 cfs @ 12.14 hrs, Volume= 3,280 cf, Depth> 1.13" Routed to Pond DP1 : Parkers RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsNOAA 24-hr A 2-year Rainfall=3.37"Area (sf) CN Description15,201 98 Paved parking, HSG A5,742 98 Roofs, HSG A13,759 39 >75% Grass cover, Good, HSG A34,702 75 Weighted Average13,759 39.65% Pervious Area20,943 60.35% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment EX1: Off-Site (Parkers River)RunoffHydrographTime (hours)201918171615141312111098765Flow (cfs)10NOAA 24-hr A2-year Rainfall=3.37"Runoff Area=34,702 sfRunoff Volume=3,280 cfRunoff Depth>1.13"Tc=6.0 minCN=75 1.63 cfs EWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 8HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond DP1: Parkers RiverInflow Area = 34,702 sf, 60.35% Impervious, Inflow Depth > 1.13" for 2-year eventInflow = 1.63 cfs @ 12.14 hrs, Volume= 3,280 cfPrimary = 1.63 cfs @ 12.14 hrs, Volume= 3,280 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsPond DP1: Parkers RiverInflowPrimaryHydrographTime (hours)201918171615141312111098765Flow (cfs)10Inflow Area=34,702 sf 1.63 cfs 1.63 cfs EWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 9HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=5.00-20.00 hrs, dt=0.05 hrs, 301 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=34,702 sf 60.35% Impervious Runoff Depth>2.24"Subcatchment EX1: Off-Site (Parkers Tc=6.0 min CN=75 Runoff=3.21 cfs 6,475 cf Inflow=3.21 cfs 6,475 cfPond DP1: Parkers River Primary=3.21 cfs 6,475 cfTotal Runoff Area = 34,702 sf Runoff Volume = 6,475 cf Average Runoff Depth = 2.24"39.65% Pervious = 13,759 sf 60.35% Impervious = 20,943 sfEWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 10HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment EX1: Off-Site (Parkers River)Runoff = 3.21 cfs @ 12.13 hrs, Volume= 6,475 cf, Depth> 2.24" Routed to Pond DP1 : Parkers RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsNOAA 24-hr A 10-year Rainfall=4.90"Area (sf) CN Description15,201 98 Paved parking, HSG A5,742 98 Roofs, HSG A13,759 39 >75% Grass cover, Good, HSG A34,702 75 Weighted Average13,759 39.65% Pervious Area20,943 60.35% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment EX1: Off-Site (Parkers River)RunoffHydrographTime (hours)201918171615141312111098765Flow (cfs)3210NOAA 24-hr A10-year Rainfall=4.90"Runoff Area=34,702 sfRunoff Volume=6,475 cfRunoff Depth>2.24"Tc=6.0 minCN=75 3.21 cfs EWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 11HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond DP1: Parkers RiverInflow Area = 34,702 sf, 60.35% Impervious, Inflow Depth > 2.24" for 10-year eventInflow = 3.21 cfs @ 12.13 hrs, Volume= 6,475 cfPrimary = 3.21 cfs @ 12.13 hrs, Volume= 6,475 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsPond DP1: Parkers RiverInflowPrimaryHydrographTime (hours)201918171615141312111098765Flow (cfs)3210Inflow Area=34,702 sf 3.21 cfs 3.21 cfs EWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 12HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=5.00-20.00 hrs, dt=0.05 hrs, 301 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=34,702 sf 60.35% Impervious Runoff Depth>3.00"Subcatchment EX1: Off-Site (Parkers Tc=6.0 min CN=75 Runoff=4.26 cfs 8,677 cf Inflow=4.26 cfs 8,677 cfPond DP1: Parkers River Primary=4.26 cfs 8,677 cfTotal Runoff Area = 34,702 sf Runoff Volume = 8,677 cf Average Runoff Depth = 3.00"39.65% Pervious = 13,759 sf 60.35% Impervious = 20,943 sf EWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 13HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment EX1: Off-Site (Parkers River)Runoff = 4.26 cfs @ 12.13 hrs, Volume= 8,677 cf, Depth> 3.00" Routed to Pond DP1 : Parkers RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsNOAA 24-hr A 25-year Rainfall=5.86"Area (sf) CN Description15,201 98 Paved parking, HSG A5,742 98 Roofs, HSG A13,759 39 >75% Grass cover, Good, HSG A34,702 75 Weighted Average13,759 39.65% Pervious Area20,943 60.35% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment EX1: Off-Site (Parkers River)RunoffHydrographTime (hours)201918171615141312111098765Flow (cfs)43210NOAA 24-hr A25-year Rainfall=5.86"Runoff Area=34,702 sfRunoff Volume=8,677 cfRunoff Depth>3.00"Tc=6.0 minCN=75 4.26 cfs EWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 14HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond DP1: Parkers RiverInflow Area = 34,702 sf, 60.35% Impervious, Inflow Depth > 3.00" for 25-year eventInflow = 4.26 cfs @ 12.13 hrs, Volume= 8,677 cfPrimary = 4.26 cfs @ 12.13 hrs, Volume= 8,677 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsPond DP1: Parkers RiverInflowPrimaryHydrographTime (hours)201918171615141312111098765Flow (cfs)43210Inflow Area=34,702 sf 4.26 cfs 4.26 cfs EWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 15HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=5.00-20.00 hrs, dt=0.05 hrs, 301 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=34,702 sf 60.35% Impervious Runoff Depth>3.59"Subcatchment EX1: Off-Site (Parkers Tc=6.0 min CN=75 Runoff=5.07 cfs 10,393 cf Inflow=5.07 cfs 10,393 cfPond DP1: Parkers River Primary=5.07 cfs 10,393 cfTotal Runoff Area = 34,702 sf Runoff Volume = 10,393 cf Average Runoff Depth = 3.59"39.65% Pervious = 13,759 sf 60.35% Impervious = 20,943 sfEWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 16HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment EX1: Off-Site (Parkers River)Runoff = 5.07 cfs @ 12.13 hrs, Volume= 10,393 cf, Depth> 3.59" Routed to Pond DP1 : Parkers RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsNOAA 24-hr A 50-year Rainfall=6.58"Area (sf) CN Description15,201 98 Paved parking, HSG A5,742 98 Roofs, HSG A13,759 39 >75% Grass cover, Good, HSG A34,702 75 Weighted Average13,759 39.65% Pervious Area20,943 60.35% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment EX1: Off-Site (Parkers River)RunoffHydrographTime (hours)201918171615141312111098765Flow (cfs)543210NOAA 24-hr A50-year Rainfall=6.58"Runoff Area=34,702 sfRunoff Volume=10,393 cfRunoff Depth>3.59"Tc=6.0 minCN=75 5.07 cfs EWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 17HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond DP1: Parkers RiverInflow Area = 34,702 sf, 60.35% Impervious, Inflow Depth > 3.59" for 50-year eventInflow = 5.07 cfs @ 12.13 hrs, Volume= 10,393 cfPrimary = 5.07 cfs @ 12.13 hrs, Volume= 10,393 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsPond DP1: Parkers RiverInflowPrimaryHydrographTime (hours)201918171615141312111098765Flow (cfs)543210Inflow Area=34,702 sf 5.07 cfs 5.07 cfs EWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 18HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=5.00-20.00 hrs, dt=0.05 hrs, 301 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=34,702 sf 60.35% Impervious Runoff Depth>4.23"Subcatchment EX1: Off-Site (Parkers Tc=6.0 min CN=75 Runoff=5.92 cfs 12,226 cf Inflow=5.92 cfs 12,226 cfPond DP1: Parkers River Primary=5.92 cfs 12,226 cfTotal Runoff Area = 34,702 sf Runoff Volume = 12,226 cf Average Runoff Depth = 4.23"39.65% Pervious = 13,759 sf 60.35% Impervious = 20,943 sf EWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 19HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment EX1: Off-Site (Parkers River)Runoff = 5.92 cfs @ 12.13 hrs, Volume= 12,226 cf, Depth> 4.23" Routed to Pond DP1 : Parkers RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsNOAA 24-hr A 100-year Rainfall=7.33"Area (sf) CN Description15,201 98 Paved parking, HSG A5,742 98 Roofs, HSG A13,759 39 >75% Grass cover, Good, HSG A34,702 75 Weighted Average13,759 39.65% Pervious Area20,943 60.35% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment EX1: Off-Site (Parkers River)RunoffHydrographTime (hours)201918171615141312111098765Flow (cfs)6543210NOAA 24-hr A100-year Rainfall=7.33"Runoff Area=34,702 sfRunoff Volume=12,226 cfRunoff Depth>4.23"Tc=6.0 minCN=75 5.92 cfs EWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-EWAM Printed 12/22/2025Prepared by BSC GroupPage 20HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond DP1: Parkers RiverInflow Area = 34,702 sf, 60.35% Impervious, Inflow Depth > 4.23" for 100-year eventInflow = 5.92 cfs @ 12.13 hrs, Volume= 12,226 cfPrimary = 5.92 cfs @ 12.13 hrs, Volume= 12,226 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrsPond DP1: Parkers RiverInflowPrimaryHydrographTime (hours)201918171615141312111098765Flow (cfs)6543210Inflow Area=34,702 sf 5.92 cfs 5.92 cfs Stormwater Report 703 Route 28 South Yarmouth, MA 5.03 PROPOSED WATERSHED PLAN G G G G G G G G G G G OHWOHWOHWWOHW OHW OHW OHW OHW OHW OHWOHW(PUBL I C V A R I A B L E W I D T H ) MAIN S T R E E T - S T A T E R O U T E 2 8 PARKERS R IVERPARKERS RIVERS(PRIV A T E 4 0' WI D E ) MERM A I D L A N ENAD 83 MA MAINLANDWWWWGGGGGGGGGEXISTING CONDITIONS WATERSHED MAP EWAM 803 Summer Street Boston, Massachusetts 02127 617 896 4300508 792 4500 1 Mercantile Street, Suite 610 Worcester, Massachusetts 01608 349 Main Street - Route 28 West Yarmouth, Massachusetts 02673 508 778 8919 665 Winding Brook Drive Glastonbury, Connecticut 06033 860 652 8227 IN ISSUED FOR PERMITTING NOT FOR CONSTRUCTION 703 ROUTE 28 REDEVELOPMENT SOUTH YARMOUTH MASSACHUSETTS (BARNSATBLE COUNTY) DECEMBER 22, 2025 300 Brickstone Square, Suite 203 Andover, Massachusetts 01810 617 896 4300 150 Dow Street Manchester, New Hampshire 03101 617 896 4300 Stormwater Report 703 Route 28 South Yarmouth, MA 5.04 PROPOSED HYDROLOGY CALCULATIONS (HYDROCAD™ PRINTOUTS) PR1To CB-1PR2To CB-2PR3Off-Site FlowPR4RoofPR5To CB-3DP1Parker's River1PInfiltration System-02Routing Diagram for 010126400-PWAMPrepared by BSC Group, Printed 12/22/2025HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSubcatReachPondLinkPWAM010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 2HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCRainfall Events ListingEvent# EventNameStorm Type Curve Mode Duration(hours)B/B Depth(inches)AMC1 2-year NOAA 24-hr A Default 24.00 1 3.37 22 10-year NOAA 24-hr A Default 24.00 1 4.90 23 25-year NOAA 24-hr A Default 24.00 1 5.86 24 50-year NOAA 24-hr A Default 24.00 1 6.58 25 100-year NOAA 24-hr A Default 24.00 1 7.33 2 PWAM010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 3HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCArea Listing (all nodes)Area(sq-ft)CN Description(subcatchment-numbers)21,404 39 >75% Grass cover, Good, HSG A (PR1, PR2, PR3, PR5)396 98 Deck, HSG A (PR4)5,906 98 Paved parking, HSG A (PR1, PR2, PR5)6,748 98 Roofs, HSG A (PR4)248 98 Walkway, HSG A (PR3)34,702 62 TOTAL AREAPWAM010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 4HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSoil Listing (all nodes)Area(sq-ft)SoilGroupSubcatchmentNumbers34,702 HSG A PR1, PR2, PR3, PR4, PR50 HSG B0 HSG C0 HSG D0 Other34,702 TOTAL AREA PWAM010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 5HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCGround Covers (all nodes)HSG-A(sq-ft)HSG-B(sq-ft)HSG-C(sq-ft)HSG-D(sq-ft)Other(sq-ft)Total(sq-ft)GroundCover21,404 0 0 0 0 21,404 >75% Grass cover, Good396 0 0 0 0 396 Deck5,906 0 0 0 0 5,906 Paved parking6,748 0 0 0 0 6,748 Roofs248 0 0 0 0 248 Walkway34,702 0 0 0 0 34,702 TOTAL AREAPWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 6HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=0.00-24.00 hrs, dt=0.01 hrs, 2401 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=2,873 sf 68.50% Impervious Runoff Depth>1.46"Subcatchment PR1: To CB-1 Tc=6.0 min CN=79 Runoff=0.17 cfs 350 cfRunoff Area=2,424 sf 64.44% Impervious Runoff Depth>1.33"Subcatchment PR2: To CB-2 Tc=6.0 min CN=77 Runoff=0.13 cfs 269 cfRunoff Area=18,914 sf 1.31% Impervious Runoff Depth>0.01"Subcatchment PR3: Off-Site Flow Tc=6.0 min CN=40 Runoff=0.00 cfs 14 cfRunoff Area=7,144 sf 100.00% Impervious Runoff Depth>3.13"Subcatchment PR4: Roof Tc=6.0 min CN=98 Runoff=0.77 cfs 1,866 cfRunoff Area=3,347 sf 70.99% Impervious Runoff Depth>1.60"Subcatchment PR5: To CB-3 Tc=6.0 min CN=81 Runoff=0.22 cfs 447 cf Inflow=0.00 cfs 14 cfReach DP1: Parker's River Outflow=0.00 cfs 14 cfPeak Elev=3.88' Storage=405 cf Inflow=1.29 cfs 2,933 cfPond 1P: Infiltration System-02 Outflow=0.50 cfs 2,932 cfTotal Runoff Area = 34,702 sf Runoff Volume = 2,947 cf Average Runoff Depth = 1.02"61.68% Pervious = 21,404 sf 38.32% Impervious = 13,298 sf PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 7HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR1: To CB-1Runoff = 0.17 cfs @ 12.14 hrs, Volume= 350 cf, Depth> 1.46" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 2-year Rainfall=3.37"Area (sf) CN Description1,968 98 Paved parking, HSG A905 39 >75% Grass cover, Good, HSG A2,873 79 Weighted Average905 31.50% Pervious Area1,968 68.50% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR1: To CB-1RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.190.180.170.160.150.140.130.120.110.10.090.080.070.060.050.040.030.020.010NOAA 24-hr A2-year Rainfall=3.37"Runoff Area=2,873 sfRunoff Volume=350 cfRunoff Depth>1.46"Tc=6.0 minCN=79 0.17 cfs PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 8HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR2: To CB-2Runoff = 0.13 cfs @ 12.14 hrs, Volume= 269 cf, Depth> 1.33" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 2-year Rainfall=3.37"Area (sf) CN Description1,562 98 Paved parking, HSG A862 39 >75% Grass cover, Good, HSG A2,424 77 Weighted Average862 35.56% Pervious Area1,562 64.44% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR2: To CB-2RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.140.130.120.110.10.090.080.070.060.050.040.030.020.010NOAA 24-hr A2-year Rainfall=3.37"Runoff Area=2,424 sfRunoff Volume=269 cfRunoff Depth>1.33"Tc=6.0 minCN=77 0.13 cfs PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 9HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR3: Off-Site FlowRunoff = 0.00 cfs @ 24.00 hrs, Volume= 14 cf, Depth> 0.01" Routed to Reach DP1 : Parker's RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 2-year Rainfall=3.37"Area (sf) CN Description18,666 39 >75% Grass cover, Good, HSG A* 248 98 Walkway, HSG A18,914 40 Weighted Average18,666 98.69% Pervious Area248 1.31% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR3: Off-Site FlowRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.0010.0010.0000.0000.0000.0000.0000.0000.000000NOAA 24-hr A2-year Rainfall=3.37"Runoff Area=18,914 sfRunoff Volume=14 cfRunoff Depth>0.01"Tc=6.0 minCN=40 0.00 cfs PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 10HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR4: RoofRunoff = 0.77 cfs @ 12.13 hrs, Volume= 1,866 cf, Depth> 3.13" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 2-year Rainfall=3.37"Area (sf) CN Description6,748 98 Roofs, HSG A* 396 98 Deck, HSG A7,144 98 Weighted Average7,144 100.00% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR4: RoofRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.850.80.750.70.650.60.550.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A2-year Rainfall=3.37"Runoff Area=7,144 sfRunoff Volume=1,866 cfRunoff Depth>3.13"Tc=6.0 minCN=98 0.77 cfs PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 11HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR5: To CB-3Runoff = 0.22 cfs @ 12.13 hrs, Volume= 447 cf, Depth> 1.60" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 2-year Rainfall=3.37"Area (sf) CN Description2,376 98 Paved parking, HSG A971 39 >75% Grass cover, Good, HSG A3,347 81 Weighted Average971 29.01% Pervious Area2,376 70.99% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR5: To CB-3RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.240.230.220.210.20.190.180.170.160.150.140.130.120.110.10.090.080.070.060.050.040.030.020.010NOAA 24-hr A2-year Rainfall=3.37"Runoff Area=3,347 sfRunoff Volume=447 cfRunoff Depth>1.60"Tc=6.0 minCN=81 0.22 cfs PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 12HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Reach DP1: Parker's RiverInflow Area = 18,914 sf, 1.31% Impervious, Inflow Depth > 0.01" for 2-year eventInflow = 0.00 cfs @ 24.00 hrs, Volume= 14 cfOutflow = 0.00 cfs @ 24.00 hrs, Volume= 14 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsReach DP1: Parker's RiverInflowOutflowHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.0010.0010.0000.0000.0000.0000.0000.0000.000000Inflow Area=18,914 sf 0.00 cfs 0.00 cfs PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 13HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond 1P: Infiltration System-02Inflow Area = 15,788 sf, 82.66% Impervious, Inflow Depth > 2.23" for 2-year eventInflow = 1.29 cfs @ 12.13 hrs, Volume= 2,933 cfOutflow = 0.50 cfs @ 11.99 hrs, Volume= 2,932 cf, Atten= 61%, Lag= 0.0 minDiscarded = 0.50 cfs @ 11.99 hrs, Volume= 2,932 cfRouting by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 3.88' @ 12.26 hrs Surf.Area= 2,637 sf Storage= 405 cfPlug-Flow detention time= 3.9 min calculated for 2,931 cf (100% of inflow)Center-of-Mass det. time= 3.8 min ( 779.2 - 775.4 )Volume Invert Avail.Storage Storage Description#1A 3.50' 1,281 cf15.00'W x 137.50'L x 2.04'H Field A4,211 cf Overall - 1,009 cf Embedded = 3,202 cf x 40.0% Voids#2A 4.00' 1,009 cfCultec C-100HD x 72 Inside #1Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 4 rows#3B 3.50' 385 cf5.00'W x 115.00'L x 2.04'H Field B1,174 cf Overall - 210 cf Embedded = 964 cf x 40.0% Voids#4B 4.00' 210 cfCultec C-100HD x 15 Inside #3Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 1 rows2,886 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber WizardDevice Routing Invert Outlet Devices#1 Discarded 3.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.50 cfs @ 11.99 hrs HW=3.52' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.50 cfs)PWAMNOAA 24-hr A 2-year Rainfall=3.37"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 14HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCPond 1P: Infiltration System-02InflowDiscardedHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)10Inflow Area=15,788 sfPeak Elev=3.88'Storage=405 cf 1.29 cfs 0.50 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 15HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=0.00-24.00 hrs, dt=0.01 hrs, 2401 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=2,873 sf 68.50% Impervious Runoff Depth>2.71"Subcatchment PR1: To CB-1 Tc=6.0 min CN=79 Runoff=0.31 cfs 650 cfRunoff Area=2,424 sf 64.44% Impervious Runoff Depth>2.54"Subcatchment PR2: To CB-2 Tc=6.0 min CN=77 Runoff=0.25 cfs 512 cfRunoff Area=18,914 sf 1.31% Impervious Runoff Depth>0.21"Subcatchment PR3: Off-Site Flow Tc=6.0 min CN=40 Runoff=0.04 cfs 336 cfRunoff Area=7,144 sf 100.00% Impervious Runoff Depth>4.66"Subcatchment PR4: Roof Tc=6.0 min CN=98 Runoff=1.13 cfs 2,774 cfRunoff Area=3,347 sf 70.99% Impervious Runoff Depth>2.89"Subcatchment PR5: To CB-3 Tc=6.0 min CN=81 Runoff=0.39 cfs 807 cf Inflow=0.04 cfs 336 cfReach DP1: Parker's River Outflow=0.04 cfs 336 cfPeak Elev=4.26' Storage=1,060 cf Inflow=2.08 cfs 4,744 cfPond 1P: Infiltration System-02 Outflow=0.50 cfs 4,743 cfTotal Runoff Area = 34,702 sf Runoff Volume = 5,079 cf Average Runoff Depth = 1.76"61.68% Pervious = 21,404 sf 38.32% Impervious = 13,298 sfPWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 16HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR1: To CB-1Runoff = 0.31 cfs @ 12.13 hrs, Volume= 650 cf, Depth> 2.71" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 10-year Rainfall=4.90"Area (sf) CN Description1,968 98 Paved parking, HSG A905 39 >75% Grass cover, Good, HSG A2,873 79 Weighted Average905 31.50% Pervious Area1,968 68.50% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR1: To CB-1RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A10-year Rainfall=4.90"Runoff Area=2,873 sfRunoff Volume=650 cfRunoff Depth>2.71"Tc=6.0 minCN=79 0.31 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 17HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR2: To CB-2Runoff = 0.25 cfs @ 12.13 hrs, Volume= 512 cf, Depth> 2.54" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 10-year Rainfall=4.90"Area (sf) CN Description1,562 98 Paved parking, HSG A862 39 >75% Grass cover, Good, HSG A2,424 77 Weighted Average862 35.56% Pervious Area1,562 64.44% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR2: To CB-2RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A10-year Rainfall=4.90"Runoff Area=2,424 sfRunoff Volume=512 cfRunoff Depth>2.54"Tc=6.0 minCN=77 0.25 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 18HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR3: Off-Site FlowRunoff = 0.04 cfs @ 12.53 hrs, Volume= 336 cf, Depth> 0.21" Routed to Reach DP1 : Parker's RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 10-year Rainfall=4.90"Area (sf) CN Description18,666 39 >75% Grass cover, Good, HSG A* 248 98 Walkway, HSG A18,914 40 Weighted Average18,666 98.69% Pervious Area248 1.31% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR3: Off-Site FlowRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.040.0380.0360.0340.0320.030.0280.0260.0240.0220.020.0180.0160.0140.0120.010.0080.0060.0040.0020NOAA 24-hr A10-year Rainfall=4.90"Runoff Area=18,914 sfRunoff Volume=336 cfRunoff Depth>0.21"Tc=6.0 minCN=40 0.04 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 19HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR4: RoofRunoff = 1.13 cfs @ 12.13 hrs, Volume= 2,774 cf, Depth> 4.66" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 10-year Rainfall=4.90"Area (sf) CN Description6,748 98 Roofs, HSG A* 396 98 Deck, HSG A7,144 98 Weighted Average7,144 100.00% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR4: RoofRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)10NOAA 24-hr A10-year Rainfall=4.90"Runoff Area=7,144 sfRunoff Volume=2,774 cfRunoff Depth>4.66"Tc=6.0 minCN=98 1.13 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 20HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR5: To CB-3Runoff = 0.39 cfs @ 12.13 hrs, Volume= 807 cf, Depth> 2.89" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 10-year Rainfall=4.90"Area (sf) CN Description2,376 98 Paved parking, HSG A971 39 >75% Grass cover, Good, HSG A3,347 81 Weighted Average971 29.01% Pervious Area2,376 70.99% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR5: To CB-3RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.420.40.380.360.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A10-year Rainfall=4.90"Runoff Area=3,347 sfRunoff Volume=807 cfRunoff Depth>2.89"Tc=6.0 minCN=81 0.39 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 21HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Reach DP1: Parker's RiverInflow Area = 18,914 sf, 1.31% Impervious, Inflow Depth > 0.21" for 10-year eventInflow = 0.04 cfs @ 12.53 hrs, Volume= 336 cfOutflow = 0.04 cfs @ 12.53 hrs, Volume= 336 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsReach DP1: Parker's RiverInflowOutflowHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.040.0380.0360.0340.0320.030.0280.0260.0240.0220.020.0180.0160.0140.0120.010.0080.0060.0040.0020Inflow Area=18,914 sf 0.04 cfs 0.04 cfs PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 22HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond 1P: Infiltration System-02Inflow Area = 15,788 sf, 82.66% Impervious, Inflow Depth > 3.61" for 10-year eventInflow = 2.08 cfs @ 12.13 hrs, Volume= 4,744 cfOutflow = 0.50 cfs @ 11.89 hrs, Volume= 4,743 cf, Atten= 76%, Lag= 0.0 minDiscarded = 0.50 cfs @ 11.89 hrs, Volume= 4,743 cfRouting by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 4.26' @ 12.37 hrs Surf.Area= 2,637 sf Storage= 1,060 cfPlug-Flow detention time= 11.7 min calculated for 4,741 cf (100% of inflow)Center-of-Mass det. time= 11.6 min ( 781.7 - 770.0 )Volume Invert Avail.Storage Storage Description#1A 3.50' 1,281 cf15.00'W x 137.50'L x 2.04'H Field A4,211 cf Overall - 1,009 cf Embedded = 3,202 cf x 40.0% Voids#2A 4.00' 1,009 cfCultec C-100HD x 72 Inside #1Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 4 rows#3B 3.50' 385 cf5.00'W x 115.00'L x 2.04'H Field B1,174 cf Overall - 210 cf Embedded = 964 cf x 40.0% Voids#4B 4.00' 210 cfCultec C-100HD x 15 Inside #3Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 1 rows2,886 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber WizardDevice Routing Invert Outlet Devices#1 Discarded 3.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.50 cfs @ 11.89 hrs HW=3.52' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.50 cfs) PWAMNOAA 24-hr A 10-year Rainfall=4.90"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 23HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCPond 1P: Infiltration System-02InflowDiscardedHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)210Inflow Area=15,788 sfPeak Elev=4.26'Storage=1,060 cf 2.08 cfs 0.50 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 24HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=0.00-24.00 hrs, dt=0.01 hrs, 2401 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=2,873 sf 68.50% Impervious Runoff Depth>3.55"Subcatchment PR1: To CB-1 Tc=6.0 min CN=79 Runoff=0.41 cfs 850 cfRunoff Area=2,424 sf 64.44% Impervious Runoff Depth>3.35"Subcatchment PR2: To CB-2 Tc=6.0 min CN=77 Runoff=0.33 cfs 677 cfRunoff Area=18,914 sf 1.31% Impervious Runoff Depth>0.46"Subcatchment PR3: Off-Site Flow Tc=6.0 min CN=40 Runoff=0.14 cfs 720 cfRunoff Area=7,144 sf 100.00% Impervious Runoff Depth>5.62"Subcatchment PR4: Roof Tc=6.0 min CN=98 Runoff=1.36 cfs 3,345 cfRunoff Area=3,347 sf 70.99% Impervious Runoff Depth>3.75"Subcatchment PR5: To CB-3 Tc=6.0 min CN=81 Runoff=0.50 cfs 1,047 cf Inflow=0.14 cfs 720 cfReach DP1: Parker's River Outflow=0.14 cfs 720 cfPeak Elev=4.51' Storage=1,556 cf Inflow=2.59 cfs 5,919 cfPond 1P: Infiltration System-02 Outflow=0.50 cfs 5,919 cfTotal Runoff Area = 34,702 sf Runoff Volume = 6,639 cf Average Runoff Depth = 2.30"61.68% Pervious = 21,404 sf 38.32% Impervious = 13,298 sf PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 25HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR1: To CB-1Runoff = 0.41 cfs @ 12.13 hrs, Volume= 850 cf, Depth> 3.55" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 25-year Rainfall=5.86"Area (sf) CN Description1,968 98 Paved parking, HSG A905 39 >75% Grass cover, Good, HSG A2,873 79 Weighted Average905 31.50% Pervious Area1,968 68.50% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR1: To CB-1RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.440.420.40.380.360.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A25-year Rainfall=5.86"Runoff Area=2,873 sfRunoff Volume=850 cfRunoff Depth>3.55"Tc=6.0 minCN=79 0.41 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 26HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR2: To CB-2Runoff = 0.33 cfs @ 12.13 hrs, Volume= 677 cf, Depth> 3.35" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 25-year Rainfall=5.86"Area (sf) CN Description1,562 98 Paved parking, HSG A862 39 >75% Grass cover, Good, HSG A2,424 77 Weighted Average862 35.56% Pervious Area1,562 64.44% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR2: To CB-2RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.360.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A25-year Rainfall=5.86"Runoff Area=2,424 sfRunoff Volume=677 cfRunoff Depth>3.35"Tc=6.0 minCN=77 0.33 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 27HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR3: Off-Site FlowRunoff = 0.14 cfs @ 12.17 hrs, Volume= 720 cf, Depth> 0.46" Routed to Reach DP1 : Parker's RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 25-year Rainfall=5.86"Area (sf) CN Description18,666 39 >75% Grass cover, Good, HSG A* 248 98 Walkway, HSG A18,914 40 Weighted Average18,666 98.69% Pervious Area248 1.31% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR3: Off-Site FlowRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.150.140.130.120.110.10.090.080.070.060.050.040.030.020.010NOAA 24-hr A25-year Rainfall=5.86"Runoff Area=18,914 sfRunoff Volume=720 cfRunoff Depth>0.46"Tc=6.0 minCN=40 0.14 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 28HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR4: RoofRunoff = 1.36 cfs @ 12.13 hrs, Volume= 3,345 cf, Depth> 5.62" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 25-year Rainfall=5.86"Area (sf) CN Description6,748 98 Roofs, HSG A* 396 98 Deck, HSG A7,144 98 Weighted Average7,144 100.00% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR4: RoofRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)10NOAA 24-hr A25-year Rainfall=5.86"Runoff Area=7,144 sfRunoff Volume=3,345 cfRunoff Depth>5.62"Tc=6.0 minCN=98 1.36 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 29HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR5: To CB-3Runoff = 0.50 cfs @ 12.13 hrs, Volume= 1,047 cf, Depth> 3.75" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 25-year Rainfall=5.86"Area (sf) CN Description2,376 98 Paved parking, HSG A971 39 >75% Grass cover, Good, HSG A3,347 81 Weighted Average971 29.01% Pervious Area2,376 70.99% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR5: To CB-3RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.550.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A25-year Rainfall=5.86"Runoff Area=3,347 sfRunoff Volume=1,047 cfRunoff Depth>3.75"Tc=6.0 minCN=81 0.50 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 30HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Reach DP1: Parker's RiverInflow Area = 18,914 sf, 1.31% Impervious, Inflow Depth > 0.46" for 25-year eventInflow = 0.14 cfs @ 12.17 hrs, Volume= 720 cfOutflow = 0.14 cfs @ 12.17 hrs, Volume= 720 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsReach DP1: Parker's RiverInflowOutflowHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.150.140.130.120.110.10.090.080.070.060.050.040.030.020.010Inflow Area=18,914 sf 0.14 cfs 0.14 cfs PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 31HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond 1P: Infiltration System-02Inflow Area = 15,788 sf, 82.66% Impervious, Inflow Depth > 4.50" for 25-year eventInflow = 2.59 cfs @ 12.13 hrs, Volume= 5,919 cfOutflow = 0.50 cfs @ 11.83 hrs, Volume= 5,919 cf, Atten= 80%, Lag= 0.0 minDiscarded = 0.50 cfs @ 11.83 hrs, Volume= 5,919 cfRouting by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 4.51' @ 12.42 hrs Surf.Area= 2,637 sf Storage= 1,556 cfPlug-Flow detention time= 18.3 min calculated for 5,919 cf (100% of inflow)Center-of-Mass det. time= 18.3 min ( 785.7 - 767.4 )Volume Invert Avail.Storage Storage Description#1A 3.50' 1,281 cf15.00'W x 137.50'L x 2.04'H Field A4,211 cf Overall - 1,009 cf Embedded = 3,202 cf x 40.0% Voids#2A 4.00' 1,009 cfCultec C-100HD x 72 Inside #1Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 4 rows#3B 3.50' 385 cf5.00'W x 115.00'L x 2.04'H Field B1,174 cf Overall - 210 cf Embedded = 964 cf x 40.0% Voids#4B 4.00' 210 cfCultec C-100HD x 15 Inside #3Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 1 rows2,886 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber WizardDevice Routing Invert Outlet Devices#1 Discarded 3.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.50 cfs @ 11.83 hrs HW=3.52' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.50 cfs)PWAMNOAA 24-hr A 25-year Rainfall=5.86"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 32HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCPond 1P: Infiltration System-02InflowDiscardedHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)210Inflow Area=15,788 sfPeak Elev=4.51'Storage=1,556 cf 2.59 cfs 0.50 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 33HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=0.00-24.00 hrs, dt=0.01 hrs, 2401 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=2,873 sf 68.50% Impervious Runoff Depth>4.20"Subcatchment PR1: To CB-1 Tc=6.0 min CN=79 Runoff=0.48 cfs 1,005 cfRunoff Area=2,424 sf 64.44% Impervious Runoff Depth>3.99"Subcatchment PR2: To CB-2 Tc=6.0 min CN=77 Runoff=0.39 cfs 805 cfRunoff Area=18,914 sf 1.31% Impervious Runoff Depth>0.69"Subcatchment PR3: Off-Site Flow Tc=6.0 min CN=40 Runoff=0.32 cfs 1,085 cfRunoff Area=7,144 sf 100.00% Impervious Runoff Depth>6.34"Subcatchment PR4: Roof Tc=6.0 min CN=98 Runoff=1.53 cfs 3,773 cfRunoff Area=3,347 sf 70.99% Impervious Runoff Depth>4.41"Subcatchment PR5: To CB-3 Tc=6.0 min CN=81 Runoff=0.58 cfs 1,231 cf Inflow=0.32 cfs 1,085 cfReach DP1: Parker's River Outflow=0.32 cfs 1,085 cfPeak Elev=4.75' Storage=1,968 cf Inflow=2.97 cfs 6,813 cfPond 1P: Infiltration System-02 Outflow=0.50 cfs 6,813 cfTotal Runoff Area = 34,702 sf Runoff Volume = 7,898 cf Average Runoff Depth = 2.73"61.68% Pervious = 21,404 sf 38.32% Impervious = 13,298 sfPWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 34HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR1: To CB-1Runoff = 0.48 cfs @ 12.13 hrs, Volume= 1,005 cf, Depth> 4.20" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 50-year Rainfall=6.58"Area (sf) CN Description1,968 98 Paved parking, HSG A905 39 >75% Grass cover, Good, HSG A2,873 79 Weighted Average905 31.50% Pervious Area1,968 68.50% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR1: To CB-1RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A50-year Rainfall=6.58"Runoff Area=2,873 sfRunoff Volume=1,005 cfRunoff Depth>4.20"Tc=6.0 minCN=79 0.48 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 35HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR2: To CB-2Runoff = 0.39 cfs @ 12.13 hrs, Volume= 805 cf, Depth> 3.99" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 50-year Rainfall=6.58"Area (sf) CN Description1,562 98 Paved parking, HSG A862 39 >75% Grass cover, Good, HSG A2,424 77 Weighted Average862 35.56% Pervious Area1,562 64.44% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR2: To CB-2RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.420.40.380.360.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A50-year Rainfall=6.58"Runoff Area=2,424 sfRunoff Volume=805 cfRunoff Depth>3.99"Tc=6.0 minCN=77 0.39 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 36HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR3: Off-Site FlowRunoff = 0.32 cfs @ 12.16 hrs, Volume= 1,085 cf, Depth> 0.69" Routed to Reach DP1 : Parker's RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 50-year Rainfall=6.58"Area (sf) CN Description18,666 39 >75% Grass cover, Good, HSG A* 248 98 Walkway, HSG A18,914 40 Weighted Average18,666 98.69% Pervious Area248 1.31% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR3: Off-Site FlowRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A50-year Rainfall=6.58"Runoff Area=18,914 sfRunoff Volume=1,085 cfRunoff Depth>0.69"Tc=6.0 minCN=40 0.32 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 37HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR4: RoofRunoff = 1.53 cfs @ 12.13 hrs, Volume= 3,773 cf, Depth> 6.34" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 50-year Rainfall=6.58"Area (sf) CN Description6,748 98 Roofs, HSG A* 396 98 Deck, HSG A7,144 98 Weighted Average7,144 100.00% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR4: RoofRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)10NOAA 24-hr A50-year Rainfall=6.58"Runoff Area=7,144 sfRunoff Volume=3,773 cfRunoff Depth>6.34"Tc=6.0 minCN=98 1.53 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 38HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR5: To CB-3Runoff = 0.58 cfs @ 12.13 hrs, Volume= 1,231 cf, Depth> 4.41" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 50-year Rainfall=6.58"Area (sf) CN Description2,376 98 Paved parking, HSG A971 39 >75% Grass cover, Good, HSG A3,347 81 Weighted Average971 29.01% Pervious Area2,376 70.99% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR5: To CB-3RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.60.550.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A50-year Rainfall=6.58"Runoff Area=3,347 sfRunoff Volume=1,231 cfRunoff Depth>4.41"Tc=6.0 minCN=81 0.58 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 39HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Reach DP1: Parker's RiverInflow Area = 18,914 sf, 1.31% Impervious, Inflow Depth > 0.69" for 50-year eventInflow = 0.32 cfs @ 12.16 hrs, Volume= 1,085 cfOutflow = 0.32 cfs @ 12.16 hrs, Volume= 1,085 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsReach DP1: Parker's RiverInflowOutflowHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020Inflow Area=18,914 sf 0.32 cfs 0.32 cfs PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 40HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond 1P: Infiltration System-02Inflow Area = 15,788 sf, 82.66% Impervious, Inflow Depth > 5.18" for 50-year eventInflow = 2.97 cfs @ 12.13 hrs, Volume= 6,813 cfOutflow = 0.50 cfs @ 11.79 hrs, Volume= 6,813 cf, Atten= 83%, Lag= 0.0 minDiscarded = 0.50 cfs @ 11.79 hrs, Volume= 6,813 cfRouting by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 4.75' @ 12.53 hrs Surf.Area= 2,637 sf Storage= 1,968 cfPlug-Flow detention time= 24.0 min calculated for 6,810 cf (100% of inflow)Center-of-Mass det. time= 23.9 min ( 789.6 - 765.7 )Volume Invert Avail.Storage Storage Description#1A 3.50' 1,281 cf15.00'W x 137.50'L x 2.04'H Field A4,211 cf Overall - 1,009 cf Embedded = 3,202 cf x 40.0% Voids#2A 4.00' 1,009 cfCultec C-100HD x 72 Inside #1Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 4 rows#3B 3.50' 385 cf5.00'W x 115.00'L x 2.04'H Field B1,174 cf Overall - 210 cf Embedded = 964 cf x 40.0% Voids#4B 4.00' 210 cfCultec C-100HD x 15 Inside #3Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 1 rows2,886 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber WizardDevice Routing Invert Outlet Devices#1 Discarded 3.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.50 cfs @ 11.79 hrs HW=3.52' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.50 cfs) PWAMNOAA 24-hr A 50-year Rainfall=6.58"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 41HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCPond 1P: Infiltration System-02InflowDiscardedHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)3210Inflow Area=15,788 sfPeak Elev=4.75'Storage=1,968 cf 2.97 cfs 0.50 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 42HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCTime span=0.00-24.00 hrs, dt=0.01 hrs, 2401 pointsRunoff by SCS TR-20 method, UH=SCS, Weighted-CNReach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind methodRunoff Area=2,873 sf 68.50% Impervious Runoff Depth>4.88"Subcatchment PR1: To CB-1 Tc=6.0 min CN=79 Runoff=0.55 cfs 1,169 cfRunoff Area=2,424 sf 64.44% Impervious Runoff Depth>4.66"Subcatchment PR2: To CB-2 Tc=6.0 min CN=77 Runoff=0.45 cfs 941 cfRunoff Area=18,914 sf 1.31% Impervious Runoff Depth>0.97"Subcatchment PR3: Off-Site Flow Tc=6.0 min CN=40 Runoff=0.55 cfs 1,526 cfRunoff Area=7,144 sf 100.00% Impervious Runoff Depth>7.09"Subcatchment PR4: Roof Tc=6.0 min CN=98 Runoff=1.70 cfs 4,218 cfRunoff Area=3,347 sf 70.99% Impervious Runoff Depth>5.11"Subcatchment PR5: To CB-3 Tc=6.0 min CN=81 Runoff=0.67 cfs 1,425 cf Inflow=0.55 cfs 1,526 cfReach DP1: Parker's River Outflow=0.55 cfs 1,526 cfPeak Elev=5.11' Storage=2,428 cf Inflow=3.36 cfs 7,753 cfPond 1P: Infiltration System-02 Outflow=0.50 cfs 7,753 cfTotal Runoff Area = 34,702 sf Runoff Volume = 9,279 cf Average Runoff Depth = 3.21"61.68% Pervious = 21,404 sf 38.32% Impervious = 13,298 sf PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 43HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR1: To CB-1Runoff = 0.55 cfs @ 12.13 hrs, Volume= 1,169 cf, Depth> 4.88" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 100-year Rainfall=7.33"Area (sf) CN Description1,968 98 Paved parking, HSG A905 39 >75% Grass cover, Good, HSG A2,873 79 Weighted Average905 31.50% Pervious Area1,968 68.50% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR1: To CB-1RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.60.550.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A100-year Rainfall=7.33"Runoff Area=2,873 sfRunoff Volume=1,169 cfRunoff Depth>4.88"Tc=6.0 minCN=79 0.55 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 44HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR2: To CB-2Runoff = 0.45 cfs @ 12.13 hrs, Volume= 941 cf, Depth> 4.66" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 100-year Rainfall=7.33"Area (sf) CN Description1,562 98 Paved parking, HSG A862 39 >75% Grass cover, Good, HSG A2,424 77 Weighted Average862 35.56% Pervious Area1,562 64.44% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR2: To CB-2RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.50.480.460.440.420.40.380.360.340.320.30.280.260.240.220.20.180.160.140.120.10.080.060.040.020NOAA 24-hr A100-year Rainfall=7.33"Runoff Area=2,424 sfRunoff Volume=941 cfRunoff Depth>4.66"Tc=6.0 minCN=77 0.45 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 45HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR3: Off-Site FlowRunoff = 0.55 cfs @ 12.15 hrs, Volume= 1,526 cf, Depth> 0.97" Routed to Reach DP1 : Parker's RiverRunoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 100-year Rainfall=7.33"Area (sf) CN Description18,666 39 >75% Grass cover, Good, HSG A* 248 98 Walkway, HSG A18,914 40 Weighted Average18,666 98.69% Pervious Area248 1.31% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR3: Off-Site FlowRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.60.550.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A100-year Rainfall=7.33"Runoff Area=18,914 sfRunoff Volume=1,526 cfRunoff Depth>0.97"Tc=6.0 minCN=40 0.55 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 46HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR4: RoofRunoff = 1.70 cfs @ 12.13 hrs, Volume= 4,218 cf, Depth> 7.09" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 100-year Rainfall=7.33"Area (sf) CN Description6,748 98 Roofs, HSG A* 396 98 Deck, HSG A7,144 98 Weighted Average7,144 100.00% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR4: RoofRunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)10NOAA 24-hr A100-year Rainfall=7.33"Runoff Area=7,144 sfRunoff Volume=4,218 cfRunoff Depth>7.09"Tc=6.0 minCN=98 1.70 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 47HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Subcatchment PR5: To CB-3Runoff = 0.67 cfs @ 12.13 hrs, Volume= 1,425 cf, Depth> 5.11" Routed to Pond 1P : Infiltration System-02Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsNOAA 24-hr A 100-year Rainfall=7.33"Area (sf) CN Description2,376 98 Paved parking, HSG A971 39 >75% Grass cover, Good, HSG A3,347 81 Weighted Average971 29.01% Pervious Area2,376 70.99% Impervious AreaTc Length Slope Velocity Capacity Description(min) (feet) (ft/ft) (ft/sec) (cfs)6.0Direct Entry, Subcatchment PR5: To CB-3RunoffHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.70.650.60.550.50.450.40.350.30.250.20.150.10.050NOAA 24-hr A100-year Rainfall=7.33"Runoff Area=3,347 sfRunoff Volume=1,425 cfRunoff Depth>5.11"Tc=6.0 minCN=81 0.67 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 48HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Reach DP1: Parker's RiverInflow Area = 18,914 sf, 1.31% Impervious, Inflow Depth > 0.97" for 100-year eventInflow = 0.55 cfs @ 12.15 hrs, Volume= 1,526 cfOutflow = 0.55 cfs @ 12.15 hrs, Volume= 1,526 cf, Atten= 0%, Lag= 0.0 minRouting by Stor-Ind+Trans method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsReach DP1: Parker's RiverInflowOutflowHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)0.60.550.50.450.40.350.30.250.20.150.10.050Inflow Area=18,914 sf 0.55 cfs 0.55 cfs PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 49HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCSummary for Pond 1P: Infiltration System-02Inflow Area = 15,788 sf, 82.66% Impervious, Inflow Depth > 5.89" for 100-year eventInflow = 3.36 cfs @ 12.13 hrs, Volume= 7,753 cfOutflow = 0.50 cfs @ 11.75 hrs, Volume= 7,753 cf, Atten= 85%, Lag= 0.0 minDiscarded = 0.50 cfs @ 11.75 hrs, Volume= 7,753 cfRouting by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.01 hrsPeak Elev= 5.11' @ 12.57 hrs Surf.Area= 2,637 sf Storage= 2,428 cfPlug-Flow detention time= 30.4 min calculated for 7,753 cf (100% of inflow)Center-of-Mass det. time= 30.3 min ( 794.4 - 764.1 )Volume Invert Avail.Storage Storage Description#1A 3.50' 1,281 cf15.00'W x 137.50'L x 2.04'H Field A4,211 cf Overall - 1,009 cf Embedded = 3,202 cf x 40.0% Voids#2A 4.00' 1,009 cfCultec C-100HD x 72 Inside #1Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 4 rows#3B 3.50' 385 cf5.00'W x 115.00'L x 2.04'H Field B1,174 cf Overall - 210 cf Embedded = 964 cf x 40.0% Voids#4B 4.00' 210 cfCultec C-100HD x 15 Inside #3Effective Size= 32.1"W x 12.0"H => 1.86 sf x 7.50'L = 14.0 cfOverall Size= 36.0"W x 12.5"H x 8.00'L with 0.50' OverlapRow Length Adjustment= +0.50' x 1.86 sf x 1 rows2,886 cf Total Available Storage Storage Group A created with Chamber Wizard Storage Group B created with Chamber WizardDevice Routing Invert Outlet Devices#1 Discarded 3.50'8.270 in/hr Exfiltration over Surface area Discarded OutFlow Max=0.50 cfs @ 11.75 hrs HW=3.52' (Free Discharge)1=Exfiltration (Exfiltration Controls 0.50 cfs)PWAMNOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC GroupPage 50HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLCPond 1P: Infiltration System-02InflowDiscardedHydrographTime (hours)2423222120191817161514131211109876543210Flow (cfs)3210Inflow Area=15,788 sfPeak Elev=5.11'Storage=2,428 cf 3.36 cfs 0.50 cfs Stormwater Report 703 Route 28 South Yarmouth, MA SECTION 6.0 ADDITIONAL DRAINAGE CALCULATIONS Stormwater Report 703 Route 28 South Yarmouth, MA 6.01 TSS REMOVAL CALCULATIONS TSS Removal Calculation Worksheet Location: 703 Route 28 Yarmouth, MA Project: 0101264.00 Prepared By: M. Morrison Date: 12/22/2025 AREA 1 - To WQU-1 Total Impervious Area, Acres= 0.045 A B C D E BMP TSS Removal Rate Starting TSS Load* Amount Removed (BxC) Remaining Load (C-D) StormCeptor 0.77 1.00 0.77 0.23 Subsurface Infiltration System 0.8 0.23 0.18 0.05 TSS Removal = 0.95 AREA 2 - To WQU-2 Total Impervious Area, Acres= 0.036 A B C D E BMP TSS Removal Rate Starting TSS Load* Amount Removed (BxC) Remaining Load (C-D) StormCeptor 0.77 1.00 0.77 0.23 Subsurface Infiltration System 0.8 0.23 0.18 0.05 TSS Removal = 0.95 AREA 3 - To WQU-3 Total Impervious Area, Acres= 0.008 A B C D E BMP TSS Removal Rate Starting TSS Load* Amount Removed (BxC) Remaining Load (C-D) StormCeptor 0.77 1.00 0.77 0.23 Subsurface Infiltration System 0.8 0.23 0.18 0.05 TSS Removal = 0.95 Weighted Annual Average TSS Removal Rate Prj\2290800\Design\Drainage\2025-12-22 Weighted Average TSS Calculation.xls 12/22/2025 2:40 PM [TSS Removal-1 (Area-1) + TSS Revoval-2 (Area-2)+ ….] / [Area-1 + Area-2 + ...] = 0.95 Project Site TSS Removal =0.95 Prj\2290800\Design\Drainage\2025-12-22 Weighted Average TSS Calculation.xls 12/22/2025 2:40 PM Stormwater Report 703 Route 28 South Yarmouth, MA 6.02 GROUNDWATER RECHARGE VOLUME CALCULATIONS Stormwater Report 703 Route 28 South Yarmouth, MA Required Recharge Volume Rv = F x Impervious Area Where: Rv = Recharge Volume F=Target Depth Factor associated with each Hydrologic Soil Group (F=0.60-inch for Soil Type C) Impervious Area = Proposed Pavement and Rooftop area on-site = 0.60 12 13,298 = Rv = 664.9 cf (required recharge volume) As not all impervious surfaces are directed to an infiltration BMP, an adjusted Required Volume must be provided. The adjusted Required Volume (Rva) is calculated as: = . !" . !" #$% (Rv) = = 13,298 13,050 664.9 (= = 677.5 ( Storage Provided o Underground Infiltration System = 2,886 cubic feet provided. Refer to the HydroCAD storage table provided for more information. Stormwater Report 703 Route 28 South Yarmouth, MA Drawdown Within 72-Hours Pond 1P Rv = Recharge Volume, cu.ft. (see above) K = Saturated Hydraulic Conductivity, in/hr (from Rawls Table) Bottom Area = Area of Infiltration System Bottom, sq.ft. *+, = -. /# !" *+, = 2,886 (0.. 0.6891 /ℎ32,6374..= *+, = 1.59 ℎ503 o 1.59 hours < 72 hours NOAA 24-hr A 100-year Rainfall=7.33"010126400-PWAM Printed 12/22/2025Prepared by BSC Group HydroCAD® 10.20-7a s/n 00904 © 2025 HydroCAD Software Solutions LLC Stage-Area-Storage for Pond 1P: Infiltration System-02 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 3.50 2,638 0 3.52 2,638 21 3.54 2,638 42 3.56 2,638 63 3.58 2,638 84 3.60 2,638 106 3.62 2,638 127 3.64 2,638 148 3.66 2,638 169 3.68 2,638 190 3.70 2,638 211 3.72 2,638 232 3.74 2,638 253 3.76 2,638 274 3.78 2,638 295 3.80 2,638 316 3.82 2,638 338 3.84 2,638 359 3.86 2,638 380 3.88 2,638 401 3.90 2,638 422 3.92 2,638 443 3.94 2,638 464 3.96 2,638 485 3.98 2,638 506 4.00 2,638 528 4.02 2,638 570 4.04 2,638 611 4.06 2,638 653 4.08 2,638 694 4.10 2,638 735 4.12 2,638 776 4.14 2,638 817 4.16 2,638 857 4.18 2,638 898 4.20 2,638 938 4.22 2,638 978 4.24 2,638 1,018 4.26 2,638 1,059 4.28 2,638 1,099 4.30 2,638 1,139 4.32 2,638 1,179 4.34 2,638 1,218 4.36 2,638 1,258 4.38 2,638 1,297 4.40 2,638 1,336 4.42 2,638 1,375 4.44 2,638 1,414 4.46 2,638 1,452 4.48 2,638 1,491 4.50 2,638 1,529 4.52 2,638 1,567 4.54 2,638 1,604 4.56 2,638 1,641 4.58 2,638 1,678 4.60 2,638 1,715 4.62 2,638 1,751 4.64 2,638 1,787 Elevation (feet) Surface (sq-ft) Storage (cubic-feet) 4.66 2,638 1,823 4.68 2,638 1,858 4.70 2,638 1,892 4.72 2,638 1,926 4.74 2,638 1,960 4.76 2,638 1,992 4.78 2,638 2,024 4.80 2,638 2,056 4.82 2,638 2,086 4.84 2,638 2,116 4.86 2,638 2,144 4.88 2,638 2,172 4.90 2,638 2,198 4.92 2,638 2,223 4.94 2,638 2,247 4.96 2,638 2,270 4.98 2,638 2,293 5.00 2,638 2,314 5.02 2,638 2,335 5.04 2,638 2,356 5.06 2,638 2,377 5.08 2,638 2,398 5.10 2,638 2,420 5.12 2,638 2,441 5.14 2,638 2,462 5.16 2,638 2,483 5.18 2,638 2,504 5.20 2,638 2,525 5.22 2,638 2,546 5.24 2,638 2,567 5.26 2,638 2,588 5.28 2,638 2,609 5.30 2,638 2,631 5.32 2,638 2,652 5.34 2,638 2,673 5.36 2,638 2,694 5.38 2,638 2,715 5.40 2,638 2,736 5.42 2,638 2,757 5.44 2,638 2,778 5.46 2,638 2,799 5.48 2,638 2,820 5.50 2,638 2,842 5.52 2,638 2,863 5.54 2,638 2,884 This document was created by an application that isn’t licensed to use novaPDF. Purchase a license to generate PDF files without this notice. Stormwater Report 703 Route 28 South Yarmouth, MA 6.03 WATER QUALITY VOLUME CALCULATIONS Stormwater Report 703 Route 28 South Yarmouth, MA Water Quality Volume Calculation VWQ = (DWQ/12 inches/foot) * (AIMP square feet) VWQ = Required Water Quality Volume (in cubic feet) DWQ = Water Quality Depth: 1.0-inch AIMP = Total Impervious Area (in acres) used for driveways, parking, etc. Underground Infiltration Systems and Bio-Retention Areas AIMP = 13,298 sq.ft. VWQ = (1.0 inches/12 inches/foot) * (13,298 sq.ft.) VWQ = 1,108 cubic feet (required volume), provided volume = 2,886 cubic feet in Underground Infiltration System (refer to the HydroCAD storage tables provided in groundwater recharge section). Stormwater Report 703 Route 28 South Yarmouth, MA 6.04 PIPE SIZING CALCULATIONS PROJECT NAME:703 Route 28DATE:12/22/2025CALCS BY:MMMCHECKED BY:BGYRational Method Flow Rate (WQU-1 to INF) Pipe Capacity AnalysisTotal Area, A (ac) =0.07Design Flow Rate, Q (cfs) =0.41Manning's EquationQ = VA = (1.49/n )AR2/3S1/2 [cfs]Area Impervious (ac) =0.05Pipe Material (HDPE, RCP, PVC) =PVC (1.49/n )AR2/3S1/2 =1.84 cfsArea Grass (ac) =0.02Pipe Size (in) =10Area Woods (ac) = 0.00Pipe Slope, S (%) =0.70%Pipe Sufficiently Sized:YesTime of Concentration, Tc (min) =6.0Manning's Roughness Coefficient, n =0.013Return Frequency Period (years) =100Wetted Area, A (sf) =0.55Cover Characteristics, C =0.71 Wetted Perimeter, P (ft) = 2.62Rainfall Intensity, i (in/hr) =7.33 Hydraulic Radius, R [A/P] (ft) = 0.21R2/3 =0.351Q = CiA [cfs]Pipe Slope, S (ft/ft) = 0.007Flow Rate, Q (cfs) =0.41S1/2 =0.08Velocity, V (ft/s) = 3.37 PROJECT NAME:703 Route 28 DATE:12/22/2025 CALCS BY:MMM CHECKED BY:BGY Rational Method Flow Rate (WQU-2 to INF) Pipe Capacity Analysis Total Area, A (ac) =0.06 Design Flow Rate, Q (cfs) =0.33 Manning's Equation Q = VA = (1.49/n )AR2/3S1/2 [cfs] Area Impervious (ac) =0.04 Pipe Material (HDPE, RCP, PVC) =PVC (1.49/n )AR2/3S1/2 =0.56 cfs Area Grass (ac) =0.02 Pipe Size (in) =6 Area Woods (ac) = 0.00 Pipe Slope, S (%) =1.00%Pipe Sufficiently Sized:Yes Time of Concentration, Tc (min) =6.0 Manning's Roughness Coefficient, n =0.013 Return Frequency Period (years) =25 Wetted Area, A (sf) =0.20 Cover Characteristics, C =0.69 Wetted Perimeter, P (ft) = 1.57 Rainfall Intensity, i (in/hr) =7.33 Hydraulic Radius, R [A/P] (ft) = 0.13 R2/3 =0.250 Q = CiA [cfs] Pipe Slope, S (ft/ft) = 0.010 Flow Rate, Q (cfs) =0.33 S1/2 =0.10 Velocity, V (ft/s) = 2.87 PROJECT NAME:703 Route 28 DATE:12/22/2025 CALCS BY:MMM CHECKED BY:BGY Rational Method Flow Rate (WQU-3 to INF) Pipe Capacity Analysis Total Area, A (ac) =0.08 Design Flow Rate, Q (cfs) =0.50 Manning's Equation Q = VA = (1.49/n )AR2/3S1/2 [cfs] Area Impervious (ac) =0.05 Pipe Material (HDPE, RCP, PVC) =PVC (1.49/n )AR2/3S1/2 =0.56 cfs Area Grass (ac) =0.02 Pipe Size (in) =6 Area Woods (ac) = 0.00 Pipe Slope, S (%) =1.00%Pipe Sufficiently Sized:Yes Time of Concentration, Tc (min) =6.0 Manning's Roughness Coefficient, n =0.013 Return Frequency Period (years) =25 Wetted Area, A (sf) =0.20 Cover Characteristics, C =0.73 Wetted Perimeter, P (ft) = 1.57 Rainfall Intensity, i (in/hr) =7.33 Hydraulic Radius, R [A/P] (ft) = 0.13 R2/3 =0.250 Q = CiA [cfs] Pipe Slope, S (ft/ft) = 0.010 Flow Rate, Q (cfs) =0.50 S1/2 =0.10 Velocity, V (ft/s) = 2.87 Stormwater Report 703 Route 28 South Yarmouth, MA 6.05 GROUNDWATER MOUNDING ANALYSIS use consistent units (e.g. feet & days or inches & hours)Conversion Table Input Values inch/hour feet/day 1.0940 R Recharge (infiltration) rate (feet/day)0.67 1.33 0.270 Sy Specific yield, Sy (dimensionless, between 0 and 1) 165.40 K Horizontal hydraulic conductivity, Kh (feet/day)*2.00 4.00 68.750 x 1/2 length of basin (x direction, in feet) 10.000 y 1/2 width of basin (y direction, in feet)hours days 0.900 t duration of infiltration period (days)36 1.50 200.000 hi(0)initial thickness of saturated zone (feet) 200.042 h(max)maximum thickness of saturated zone (beneath center of basin at end of infiltration period) 0.042 Δh(max)maximum groundwater mounding (beneath center of basin at end of infiltration period) Ground- water Mounding, in feet Distance from center of basin in x direction, in feet 0.042 0 0.041 20 0.039 40 0.035 60 0.030 80 0.026 100 0.023 120 0.021 140 0.019 160 0.017 180 Disclaimer This spreadsheet solving the Hantush (1967) equation for ground-water mounding beneath an infiltration basin is made available to the general public as a convenience for those wishing to replicate values documented in the USGS Scientific Investigations Report 2010-5102 "Groundwater mounding beneath hypothetical stormwater infiltration basins" or to calculate values based on user-specified site conditions. Any changes made to the spreadsheet (other than values identified as user-specified) after transmission from the USGS could have unintended, undesirable consequences. These consequences could include, but may not be limited to: erroneous output, numerical instabilities, and violations of underlying assumptions that are inherent in results presented in the accompanying USGS published report. The USGS assumes no responsibility for the consequences of any changes made to the spreadsheet. If changes are made to the spreadsheet, the user is responsible for documenting the changes and justifying the results and conclusions. This spreadsheet will calculate the height of a groundwater mound beneath a stormwater infiltration basin. More information can be found in the U.S. Geological Survey Scientific Investigations Report 2010-5102 "Simulation of groundwater mounding beneath hypothetical stormwater infiltration basins". The user must specify infiltration rate (R), specific yield (Sy), horizontal hydraulic conductivity (Kh), basin dimensions (x, y), duration of infiltration period (t), and the initial thickness of the saturated zone (hi(0), height of the water table if the bottom of the aquifer is the datum). For a square basin the half width equals the half length (x = y). For a rectangular basin, if the user wants the water-table changes perpendicular to the long side, specify x as the short dimension and y as the long dimension. Conversely, if the user wants the values perpendicular to the short side, specify y as the short dimension, x as the long dimension. All distances are from the center of the basin. Users can change the distances from the center of the basin at which water-table aquifer thickness are calculated. Cells highlighted in yellow are values that can be changed by the user. Cells highlighted in red are output values based on user-specified inputs. The user MUST click the blue "Re-Calculate Now" button each time ANY of the user-specified inputs are changed otherwise necessary iterations to converge on the correct solution will not be done and values shown will be incorrect. Use consistent units for all input values (for example, feet and days) In the report accompanying this spreadsheet (USGS SIR 2010-5102), vertical soil permeability (ft/d) is assumed to be one-tenth horizontal hydraulic conductivity (ft/d). Re-Calculate Now 0.000 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0 50 100 150 200 Groundwater Mounding, in feet Stormwater Report 703 Route 28 South Yarmouth, MA 6.06 ILLICIT DISCHARGE COMPLIANCE STATEMENT Stormwater Report 703 Route 28 South Yarmouth, MA Illicit Discharge Compliance Statement This statement is to document that, to the best of my knowledge and belief, there are no and will be no illicit discharges to the stormwater management systems or protected wetland resource areas for the 703 Route 28 redevelopment in South Yarmouth, Massachusetts. Authorized Signature/Title Date Stormwater Report 703 Route 28 South Yarmouth, MA APPENDIX A USGS LOCUS MAP LOCUS STEVEN M. KATZ 99 SULLIVAN ROAD WEST YARMOUTH, MA USGS LOCUS MAP 703 ROUTE 28 SOUTH YARMOUTH, MA 349 Main Street Route 28 West Yarmouth, Massachusetts 02649 508 778 8919 Stormwater Report 703 Route 28 South Yarmouth, MA APPENDIX B FEMA MAP National Flood Hazard Layer FIRMette 0 500 1,000 1,500 2,000250 Feet Ü SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT SPECIAL FLOOD HAZARD AREAS Without Base Flood Elevation (BFE) Zone A, V, A99 With BFE or Depth Zone AE, AO, AH, VE, AR Regulatory Floodway 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage areas of less than one square mile Zone X Future Conditions 1% Annual Chance Flood Hazard Zone X Area with Reduced Flood Risk due to Levee. See Notes.Zone X Area with Flood Risk due to Levee Zone D NO SCREEN Area of Minimal Flood Hazard Zone X Area of Undetermined Flood Hazard Zone D Channel, Culvert, or Storm Sewer Levee, Dike, or Floodwall Cross Sections with 1% Annual Chance 17.5 Water Surface Elevation Coastal Transect Coastal Transect Baseline Profile Baseline Hydrographic Feature Base Flood Elevation Line (BFE) Effective LOMRs Limit of Study Jurisdiction Boundary Digital Data Available No Digital Data Available Unmapped This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 12/22/2025 at 4:50 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, FIRM panel number, and FIRM effective date. Map images for unmapped and unmodernized areas cannot be used for regulatory purposes. Legend OTHER AREAS OF FLOOD HAZARD OTHER AREAS GENERAL STRUCTURES OTHER FEATURES MAP PANELS 8 B 20.2 The pin displayed on the map is an approximate point selected by the user and does not represent an authoritative property location. 1:6,000 70°7'40"W 41°40'21"N 70°7'2"W 41°39'54"N Basemap Imagery Source: USGS National Map 2023 Stormwater Report 703 Route 28 South Yarmouth, MA APPENDIX C WEB SOIL SURVEY Hydrologic Soil Group—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2024 Page 1 of 446114504611470461149046115104611530461155046115704611590461143046114504611470461149046115104611530461155046115704611590398060398080398100398120398140398160398180398200398220398240398260398280398300 398060 398080 398100 398120 398140 398160 398180 398200 398220 398240 398260 398280 398300 41° 38' 58'' N 70° 13' 27'' W41° 38' 58'' N70° 13' 16'' W41° 38' 53'' N 70° 13' 27'' W41° 38' 53'' N 70° 13' 16'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 19N WGS84 0 50 100 200 300 Feet 0 15 30 60 90 Meters Map Scale: 1:1,150 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Rating Polygons A A/D B B/D C C/D D Not rated or not available Soil Rating Lines A A/D B B/D C C/D D Not rated or not available Soil Rating Points A A/D B B/D C C/D D Not rated or not available 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. Hydrologic Soil Group—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2024 Page 2 of 4 Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 252A Carver coarse sand, 0 to 3 percent slopes A 1.4 31.0% 607 Water, saline 1.5 32.4% 665 Udipsamments, smoothed 1.7 36.6% Totals for Area of Interest 4.7 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long-duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Hydrologic Soil Group—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2024 Page 3 of 4 Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher Hydrologic Soil Group—Barnstable County, Massachusetts Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 10/3/2024 Page 4 of 4 Stormwater Report 703 Route 28 South Yarmouth, MA APPENDIX D TEST PIT LOGS STEVEN M. KATZ 99 SULLIVAN ROAD WEST YARMOUTH, MA SOIL / DRAINAGE TEST PIT DATA 703 ROUTE 28 YARMOUTH, MA 349 Main Street - Route 28 West Yarmouth, Massachusetts 02673 508 778 8919 Stormwater Report 703 Route 28 South Yarmouth, MA APPENDIX E NOAA 14 PRECIPITATION TABLES Stormwater Report 703 Route 28 South Yarmouth, MA APPENDIX F STORMWATER CHECKLIST Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Important: When filling out forms on the computer, use only the tab key to move your cursor - do not use the return key. A. Introduction 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 2 of 8 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 12/22/2025 Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 4 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 5 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 6 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 7 of 8 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. Massachusetts Department of Environmental Protection Bureau of Resource Protection - Wetlands Program Checklist for Stormwater Report swcheck.doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 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.