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Drainage Analysis 10-23-19.pdf 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com STORMWATER DRAINAGE REPORT AND MANAGEMENT PLAN for Thomas Gu and Ping Geng 25 Maple Avenue Northampton, MA Prepared for Thomas Gu 782 Northeast Street Amherst, Massachusetts Prepared by T Reynolds Engineering 152 Maplewood Terrace Florence, MA 01062 (413) 387-8078 Fax (413) 727-3477 e-mail: terry@treynoldsengineering.com August, 2019 Revised 10/23/19 T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 2 TABLE OF CONTENTS Project Summary and Site Description ........................................................................................3  Soil and Flood Plain Review With Soil Analysis .........................................................................3  Method of Drainage Analysis ......................................................................................................5  Model Results .............................................................................................................................6  Stormwater Management Performance Standards ........................................................................7  Construction Period Pollution Prevention and Erosion and Sediment Control Measures ..............9  Short-Term Erosion Control Maintenance ................................................................................. 11  Post Construction Operation and Maintenance Plan................................................................... 12  Long Term Pollution Prevention Plan........................................................................................ 13  FIGURES Figure 1: Locus of Project Area ................................................................................................... 4 TABLES Table 1: Rainfall Runoff Results ................................................................................................. 6 APPENDICES Appendix A: Pre- & Post-Construction Drainage Area Plans Appendix B: Soils Report Appendix C: Hydrologic Analyses Appendix D: TSS Removal and Storage Volume Calculation Worksheet Appendix E: BMPs Checklist Appendix F: MA Stormwater Report Checklist T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 3 Project Summary and Site Description Thomas Gu is proposing to build a five unit apartment building and associated parking located at 25 Maple Avenue in Northampton, MA (see Figure 1). T Reynolds Engineering has been retained by Tom Gu to design the site and analyze the pre-development and post-development stormwater flow calculations for the proposed project. The purpose of this analysis is to determine the 2, 10, and 100-year peak flow rates and quantities for pre and post conditions. The stormwater management system has been designed to be in general accordance with applicable City of Northampton regulations and MA Stormwater Standards. The site is currently developed with a single residential building with associated parking. The site is generally flat over the majority of the site with the back of the property sloping down steeply to a perennial stream located to the north and east. A strip of wooded area extends along the slope to the bank of the stream. The site is a mix of impervious and pervious areas due to the paved areas and building and fill that has been capped with clay. Elevations range from low areas along the north and east side of 108 to the developed areas of 119 along the westerly perimeter. Under existing conditions, runoff from the site runs overland from the west side of the site to the northern, and eastern perimeters of the property. Runoff from the site all flows overland to the stream to the north and east. The proposed improvements to the site include; the construction of a 112'x30' building and a 10 space parking lot area. Additional construction includes associated utilities and construction of a stormwater management system. Under the improved conditions, stormwater runoff generated from the new the parking area and building will be collected in a stormwater-management system that will treat and infiltrate/detain up to and including the 100 year storm event. Stormwater entering the stormwater management system will be treated using a proprietary water quality unit. The stormwater management system has been designed so that no increases in off-site discharge rates are expected between the pre- and post-development conditions for the 2, 10, and 100-year storm events. Soil and Flood Plain Review With Soil Analysis See Soils Report Appendix C. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 4 FIGURE 1: LOCUS OF PROJECT AREA (Partial reproduction of USGS Easthampton, MA Quadrangle) SITE LOCATION T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 5 Method of Drainage Analysis The program HydroCAD was utilized to perform stormwater modeling for this project. HydroCAD uses the NRCS method of analysis TR-20. The TR-20 method is a widely accepted, standard engineering practice within the civil engineering profession. The NRCS method of hydrology analysis utilizes the drainage area, hydraulic length, terrain slope, and soil conditions of a watershed or catchment as input to calculate peak flows and total volume of runoff for specific synthetic rain events. The model analyzes an area approximately 37,673± SF contributing stormwater runoff flows on the project site. TRE modeled the 2-year, 10-year, and 100-year statistical rain events for the existing and proposed condition. The total rainfall per a 24-hour period for the 2, 10, and 100- year statistical rain events are 3.08-inches, 4.93-inches, and 7.88-inches respectively (see Pre and Post Construction Drainage Area Plans, Appendix A). Limitations The stormwater analysis was performed in accordance with standard civil engineering practice and relies on information provided by other parties as well as published information. Potential runoff analysis was limited to areas within the bounds of property owned and areas immediately adjacent and interpreted to drain toward the site of concern. Although the NRCS method has become one of the standard methods of hydrologic analysis within civil engineering community, it may be conservative for use on very small areas of modern development and provide runoff results that are greater than actual conditions. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 10/23/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 6 Model Results The following table summarizes the results of the drainage analysis using HydroCad (see Appendix C for complete analysis). Three design point were used to evaluate the pre and post construction stormwater flows that leave the site expected for the 2, 10, and 100-year storm events. Table 1: Rainfall Runoff Results Existing and Proposed Peak Discharge DESIGN POINT 2-year (cfs) 10-year (cfs) 100-year (cfs) Pre-Construction Northern Perimeter 0.70 1.57 3.05 Eastern Perimeter 0.33 0.90 1.93 Post- Construction Northern Perimeter 0.70 1.57 2.98 Eastern Perimeter 0.24 0.55 1.10 As can be seen from the above results, stormwater runoff from the 2, 10, and 100-year storm events are not expected to increase the run-off to the adjacent areas from the pre-construction conditions to the post construction condition. As stated above, the project as designed will not increase peak discharges to down gradient areas during the 100-year storm event and as a result is expected not to increase off-site flooding impacts from the 100-year, 24 hour storm (See Hydrologic Analysis, Appendix C). T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 7 Stormwater Management Performance Standards 1. No new Stormwater conveyances (e.g. Outfalls) shall discharge untreated Stormwater directly to or cause erosion in wetlands or Water of the Commonwealth. There is no increase in runoff rates from the site, and therefore no potential for increased downstream erosion. Discharges have been evaluated to determine that discharge velocities will not result in scouring and erosion (See Hydrologic Analysis, Appendix C). A stormwater management system has been designed including energy dissipaters. 2. Stormwater Management Facilities must be designed so that post-development Peak Discharge rates do not exceed predevelopment Peak Discharge rates. Post development peak discharges have been designed to not exceed pre-development peak flows up to and including the 100-year storm event. The project as designed will not increase off-site flooding impacts from the 100-year 24-hour storm (See Hydrologic Analysis, Appendix C). 3. Loss of annual Recharge to Groundwater should be minimized through the use of Infiltration measures to the maximum extent practicable. The annual Recharge from the post-development site should approximate the annual Recharge rate from the predevelopment or existing site conditions, based on soil types. Stormwater runoff from the impervious areas are directed to a water quality unit and subsequent subsurface retention system to control runoff volume and provide minimal infiltration. Stormwater from the site is calculated to infiltrate at a rate of approximately 0.10 cubic feet per second and exfiltrate 495 cubic feet during a 1-inch storm event (1.22” over 24 hrs). The instantaneous infiltration volume within the basin is approximately 490 cubic feet (volume below the lowest outlet invert). Massachusetts Stormwater Management Standards prescribes that for “B” soil, 0.35-inches of stormwater runoff and 0.1 for “D” soil multiplied by the total impervious area equals the volume of stormwater runoff that should be recharged. The total prescribed recharge volume for type “B” and "D" soil is calculated to be 101.2 cubic feet. See volume sizing calculations, Appendix D. 4. For new development, Stormwater Management Facilities must be designed to remove 80 percent of the average annual load (post development conditions) of total suspended solids (TSS). It is presumed that this standard is met when: a. Suitable nonstructural practices for source control and pollution prevention are implemented; b. Stormwater management Best Management Practices (BMPs) are sized to capture the prescribed Runoff volume; and c. Stormwater management BMPs are maintained as designed. All newly developed areas have been designed with stormwater BMPs that remove a minimum of 80% TSS. See TSS removal worksheet, Appendix D. 5. Stormwater discharges from areas with higher potential Pollutant loads require the use of specific Stormwater management BMPs (see Stormwater Management Handbook, February 2008, MassDEP, as updated or amended). The use of Infiltration practices without pretreatment is prohibited. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 8  The site does not contain land with higher pollutant loads. 6. Stormwater discharges to critical areas must utilize certain Stormwater management BMPs approved for critical areas (see Stormwater Management Handbook, February 2008, MassDEP, as updated or amended). Critical areas are outstanding resource waters (ORWs), cold-water fisheries, vernal pools and Recharge areas for public water supplies.  The site is not within a Zone II of a public water supply. 7. Redevelopment of previously developed sites must meet the Stormwater management standards to the maximum extent practicable, as determined by the Board of Public Works. However, if it is not practicable to meet all the standards, Section 4 Performance Standards and Design Requirements Stormwater Management Rules and Regulations 4-2 new (retrofitted or expanded) Stormwater Management Facilities must be designed to improve existing conditions.  The project is a redevelopment project, but all standards are being met. 8. Erosion and sediment controls must be implemented to prevent impacts during disturbance and construction activities.  Erosion and sediment controls are incorporated into the project to prevent erosion, control sediments, and stabilize exposed soils during construction (see project Plans and Erosion Control Measures, below). 9. All Stormwater Management Facilities must have an operation and maintenance plan to ensure that systems function as designed. The operation and maintenance plan must be implemented for the life of the system.  The following section describes the long-term stormwater maintenance program to be implemented. 10. All Illicit Discharges to the Stormwater Management Facilities are prohibited.  There are no known illicit discharges to the stormwater management system. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 9 Construction Period Pollution Prevention and Erosion and Sediment Control Measures The following erosion and sedimentation control measures will be employed during the earthwork and construction phases of the project. Sediment Barrier and Work Limit: Before installation of the sediment barriers, the location shall be staked in the field for review and approval by the engineer or their representative. To facilitate sediment barrier installation, woody vegetation may then be removed and any required trench may be cut by machine, provided all other ground cover is left intact. Silt Fence: The bottom of the fence shall be trenched into the ground a minimum of 4" and back-filled with compacted soil. Where trenching is not feasible, the silt fence skirt shall be covered with compacted soil or crushed stone. The top of the fabric shall be stretched as tightly as is practical, with intermediate stakes added to correct excessive sags. Stakes shall be driven at least 12" into the ground. Splices between sections shall be made by rolling end stakes together one complete turn and driving into the ground together. Filter Sock (Filtrexx or equivalent): In areas of expected sheet flow, filter sock may be placed directly on the ground without trenching or stakes. In areas of expected concentrated flow, mulch or crushed stone shall be placed along the up-slope face to control and filter underflow. Additional layers of Filter Sock may be required for adequate freeboard. Stocking Additional Materials: A stock of additional erosion control materials shall be available on the site for emergency repairs and temporary measures. Stock shall be replenished when decreased to 50% of the numbers below. Stock shall include: Straw -bales - 10 (Covered to be kept dry) with 20 Oak stakes Or Silt fence - 30 linear feet. Or Filter Sock - 4, 8 ft. sections (covered to be kept dry) Washed stone - 1 cubic yards, 3/4" to 1 2" diameter Trench Protection: Open trenches shall be protected from accumulation of surface water or groundwater that could result in erosion of the trench and discharge of sediment. Where feasible, spoil shall be stockpiled on the up-slope side of the trench to prevent surface runoff from entering the trench. Backfill shall be crowned to allow for settlement and to avoid concentration of runoff on top of the trench. Storm Drain Protection: The storm drain and swale system shall be put into operation as soon as possible in order to control runoff within a non-erodable system. The storm drain system shall be protected against inflow of sediment. Open storm drain structures shall be protected by sediment barriers, “Filtrexx” filter socks, stone filter berms, or filter fabric inserts (tea-bags, silt- sacks or equivalents). These measures shall be maintained until the tributary area is stabilized by paving and vegetative cover. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 10 Site Stabilization - Temporary: Where a portion of the site will not be subject to construction activity for over 14 days, measures shall be taken to provide temporary stabilization of that inactive portion of the site, within 14 days of the cessation of construction activity. Stabilization measures may include seeding for temporary cover, mulching, or other measures to protect exposed soil from erosion and prevent sediment movement. Site Stabilization - Permanent: Within 14 days of completion of loaming and finish grading on any portion of the site, that area shall be seeded or planted for permanent cover (season permitting) in accordance with USDA NRCS guidelines or equivalent. Roadway Sweeping: The entrance to the site and affected portions of the public roadway or paved project roadway shall be swept as needed to control sediment runoff into storm drains or waterways and to control dust migration. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 11 Short-Term Erosion Control Maintenance  The contractor or subcontractor will be responsible for implementing all erosion and sediment controls.  The on-site contractor will inspect all sediment and erosion controls on a ongoing weekly basis and after each significant rainfall event. Records of the inspections will be prepared and maintained on-site by the contractor.  Sediment shall be removed from behind barriers if greater than 6-inches deep or as needed.  Damaged or deteriorated items will be repaired immediately after identification.  The underside of filter socks should be kept in close contact with the earth and reset or provided with mulch or stone filter as necessary.  The underside of hay bales should be kept in close contact with the earth and reset as necessary.  Sediment that is collected in drainage structures or within sediment controls shall be disposed of properly and, if on site, shall not be placed in an area subject to erosion.  Erosion control structures shall remain in place until all disturbed earth has been securely stabilized. After removal of structures, disturbed areas shall be re-graded and stabilized as necessary. The sedimentation and erosion control plan is included in project plan set. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 12 Post Construction Operation and Maintenance Plan The following maintenance program is proposed to ensure the continued effectiveness of the structural water quality controls previously described.  The Stormwater management system will be owned and operated by Thomas Gu and Ping Geng.  Operation and maintenance of stormwater management system will be the responsibility of the Owners.  VortSentry HS36, Water Quality Unit maintenance; In accordance with the manufacturers recommended maintenance, at a minimum, inspections should be performed twice per year (i.e. spring and fall). The VortSentry HS36 should be cleaned when the sediment has accumulated to a depth of two feet in the treatment chamber. This determination can be made by taking two measurements with a stadia rod or similar measuring device; one measurement from the manhole opening to the top of the sediment pile and the other from the manhole opening to the water surface. If the difference between these measurements is less than 3.6 feet, the VortSentry HS36 should be maintained to ensure effective treatment.  CULTEC Sub-surface Basin The CULTEC system may be equipped with inspection ports located on the inlet row. The inspection ports are circular cast boxes placed in a rectangular concrete collar. When the lid is removed, a 6-inch (150 mm) pipe with a screw-in plug will be exposed. Remove the plug. This will provide access to the CULTEC Chamber row below. From the surface, through this access, the sediment may be measured at this location. A stadia rod may be used to measure the depth of sediment if any in this row. CCTV inspection of this row can be deployed through this access port to determine if any sediment has accumulated in the inlet row. If significant sediment is observed to be accumulating in the chamber, the pretreatment devised is not performing as designed and should be inspected. If ponding is observed in the chambers occurring 72 hours after a storm, the basin is not performing as designed and maintenance, repair or reconstruction of the chamber system is required. Sub-surface systems should be inspected in accordance with manufacturers recommended maintenance guidelines and after significant storm events of two years or greater.    Parking Lot Sweeping Paved areas will be swept, at a minimum, two times per year in the months of May and October.  See the Grading and Drainage Plan for a scaled drawing of the treatment train. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 13 Long Term Pollution Prevention Plan Good Housekeeping Practices The following is a list of good housekeeping practices provided as guidance by DEP to be considered by the property management company hired to maintain the proposed retail building and grounds. Lawn and Garden Activities, including application and disposal of lawn and garden care products, and proper disposal of leaves and yard trimmings. Effective measures include: applying pesticides and fertilizers properly, including: timing; application reduction; providing buffer areas (preferably natural vegetation) between surface waters and lawn and garden activities; limiting lawn watering and landscaping with climate-suitable vegetation; providing guidelines for what to expect from landscaping and lawn care professionals; and providing composting guidelines, if not covered elsewhere under solid waste efforts. <http://www.mass.gov/dep/water/resources/nonpoint.htm#megaman> See “More than Just a Yard: Ecological Landscaping Tools for Massachusetts Homeowners” http://www.mass.gov/envir/mwrc/pdf/More_Than_Just_Yard.pdf and Guide to Lawn and Landscape Water Conservation, http:www.mass.gov/envir/mwrc/pdf/LawnGuide.pdf. Turf Management on golf courses, parks, and recreation areas. Many of the measures described above are applicable to turf management and need to be implemented by caretakers responsible for golf courses and parks and recreation areas (including municipal employees, in some cases). Pet Waste Management. Pooper-scooper laws for pets should be enacted and implemented. Public outreach is essential to the effectiveness of these laws. Priority resource areas, such as bathing beaches and shellfish growing areas may need to exclude pets at least for the summer months or at other critical use times. Specific controls for horses and the control of manure may be needed. <http://www.mass.gov/dep/water/resources/nonpoint.htm#megaman> Integrated Pest Management (IPM) effectively prevents and controls pests (including weeds) in a way that maximizes environmental benefits at a reduced cost to growers. IPM involves applying an array of techniques and control strategies for pest management – with a focus on using them in the proper amounts and determining when they are most needed. By choosing from all possible pest control methods (e.g., biological controls and beneficial organisms) and rotating methods, resistance to repeated chemical controls can be delayed or prevented. <http://www.mass.gov/dep/water/resources/nonpoint.htm#megaman> Proper Storage, Use, and Disposal of Household Hazardous Chemicals, including automobile fluids, pesticides, paints, and solvents. Information should be provided on chemicals of concern, proper use, and disposal options. Household hazardous waste collection days should be sponsored whenever feasible. Recycling programs for used motor oil, antifreeze, and other products should be developed and promoted. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 14 Storm Drain Stenciling involves labeling storm drain inlets with painted messages warning citizens not to dump pollutants into the drains. The stenciled messages are generally a simple phrase to remind passersby that the storm drains connect to local waterbodies and that dumping pollutes those waters. Some storm drain stencils specify which waterbody the inlet drains to or name the particular river, lake, or bay. Commonly stenciled messages include: “No Dumping. Drains to Water Source,” “Drains to River,” and “You Dump it, You Drink it. No Waste Here.” Pictures can also be used to convey the message, including a shrimp, common game fish, or a graphic depiction of the path from drain to waterbody. Communities with a large Spanish- speaking population might wish to develop stencils in both English and Spanish, or use a graphic alone. <http://www.mass.gov/dep/water/resources/nonpoint.htm#megaman> Proper Operation and Maintenance of Septic Systems. Knowledge of proper operation and maintenance of septic systems should be promoted to avoid serious failures. Car Washing. This management measure involves educating the general public, businesses, municipal fleets (public works, school buses, fire, police, and parks) on the water quality impacts of the outdoor washing of automobiles and how to avoid allowing polluted runoff to enter the storm drain system. Outdoor car washing has the potential to result in high loads of nutrients, metals, and hydrocarbons during dry weather conditions in many watersheds, as the detergent- rich water used to wash the grime off our cars flows down streets and into storm drains. Commercial car wash facilities often recycle their water or are required to treat their wash-water discharge prior to release to the sanitary sewer system. As a result, most stormwater impacts from car washing are from residents, businesses, and charity car wash fundraisers that discharge polluted wash water to the storm drain system. <http://www.mass.gov/dep/water/resources/nonpoint.htm#megaman> Commercial Operations and Activities, including parking lots, gas stations, and other local businesses. Recycling, spill prevention and response plans, and proper material storage and disposal should be promoted. Using dry floor cleaners and absorbent materials and limiting the use of water to clean driveways and walkways should be encouraged. Care should be taken to avoid accidental disposal of hazardous materials down floor drains. Floor drains should be inventoried. Department of Public Works Facilities (DPWs). Because of the nature of the activities they perform, such as storing and managing sand, salt, and chemicals, and fueling and maintaining trucks and other equipment, DPWs are in a unique position to prevent a wide range of compounds from becoming stormwater pollutants. MassDEP has developed a Fact Sheet specifically for DPWs: <http://www.mass.gov/dep/water/resources/nonpoint.htm#megaman> Other efforts, including water conservation and litter control, can be tied to nonpoint source pollution control. Provisions for Storing Materials and Waste Products Inside or Under Cover All maintenance will be conducted by independent contractors hired by the property owner. No maintenance equipment or materials will be kept on-site. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 15 Vehicle Washing Controls All maintenance vehicles will be associated with independent contractors hired by the property manager. These vehicles will not be cleaned on-site. Vehicles owned by employees will not be cleaned on-site. Requirements for Routine inspections and Maintenance of Stormwater BMP’s Routine inspections will be performed to ensure the correct functioning of stormwater BMP’s. Please see the Long Term Stormwater Maintenance Program for detail regarding inspections and maintenance. Spill Prevention and Response Plan It will be the responsibility of the property manager to contain and legally remove any materials that are spilled onsite. The property manager will be responsible for providing an emergency response plan for any spills within the subject property. Provisions for Maintenance of Lawns, Gardens, and Other Landscaped Areas There will be standard landscaping consistent with other residential uses. The use of fertilizers, herbicides and pesticides will be limited to areas outside of resource areas, and outside of the 50- foot buffer of the Bordering Vegetated Wetland (BVW) on-site. Standard practices will be conducted outside of said areas and will be the ultimate responsibility of the property manager. Requirements for Storage and Use of Fertilizers, Herbicides, and Pesticides As mentioned above, fertilizers, herbicides, and pesticides will be limited to those areas outside of the resource area and the 50-foot buffer zone to the bordering vegetated wetland on-site. All of these materials will be stored off-site by the independent contractor hired by the property manager and will be applied consistent with industry standards and applicable laws. Pet Waste Management Provisions Pet waste is not anticipated to be a problem. However, any pet waste is required to be properly maintained by the pet owner. Provisions for Operation and Management of Septic Systems There are no septic systems on-site. City sewer is be utilized for the building. Provisions for Solid Waste Management A dumpster will be located on-site at the rear of the parking area. The traffic circulation within the parking area is two-way throughout, which should provide easy access for trash removal. Snow Disposal and Plowing Plans Relative to Wetland Resource Areas A snow removal area is proposed along the north side of the parking area. Snow will be stored in this area in the event of winter storms. Winter Road Salt and/or Sand Use and Storage Restrictions The use of road salt will be kept to a minimum per the Department of Environmental Protection’s (DEP’s) standards. Please refer to the Long Term Stormwater Maintenance Program for additional information. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com 16 Parking Lot Sweeping Schedules Please see the Long-Term Stormwater Maintenance Program. Provisions for Prevention of Illicit Discharges to the Stormwater Management System Any and all illicit discharges to the stormwater basin will be promptly dealt with. It will be the property manager’s responsibility to ensure compliance with the legal disposal of all materials and containment/cleanup of any illicit discharges. Training for Staff or Personnel Involved with Implementing Long-Term Pollution Prevention Plan The property manager on-site will be responsible for the implementations of the measures set forth in the Long-Term Pollution Prevention Plan (LTPPP). Said property manager will be responsible for providing documentation that management staff and sub-contractors involved with the implementation of the LTPPP have been trained to conduct such tasks. List of Emergency Contacts for Implementing Long-Term Pollution Prevention Plan A standard form for listing emergency contact information in the event of an emergency has been provided. See Appendix J. T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com Appendix A: Pre-Construction and Post-Construction Drainage Area Plans T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com Appendix B: Soils Report DE P F o r m 1 1 S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s a l • P a g e 1 o f 5 Co m m o n w e a l t h o f M a s s a c h u s e t t s Ci t y / T o w n o f Fo r m 1 1 - S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s al D a t e : 8 / 2 / 1 9 25 M a p l e A v e n u e , N o r t h a m p t o n , M A De e p O b s e r v a t i o n H o l e N u m b e r : TP - 1 De p t h (I n . ) So i l Ho r i z o n / La y e r So i l M a t r i x : Co l o r - M o i s t (M u n s e l l ) Re d o x i m o r p h i c F e a t u r e s (m o t t l e s ) So i l Te x t u r e (U S D A ) Co a r s e F r a g m e n t s % b y V o l u m e So i l S t r u c t u r e S o i l Co n s i s t e n c e (M o i s t ) Ot h e r De p t h C o l o r Pe r c e n t Gr a v e l C o b b l e s & S t o n e s 0- 6 F i l l L S F R 6- 2 7 F i l l F S F R 27 - 4 2 F i l l A s h F R 42 - 7 0 C 1 1 0 Y R 4 / 3 F S M F R 70 - 8 7 C 2 1 0 Y R 5 / 3 S S G F R Ad d i t i o n a l N o t e s DE P F o r m 1 1 S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s a l • P a g e 2 o f 5 Co m m o n w e a l t h o f M a s s a c h u s e t t s Ci t y / T o w n o f Fo r m 1 1 - S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s al D a t e : 8 / 2 / 1 9 25 M a p l e A v e n u e , N o r t h a m p t o n , M A De e p O b s e r v a t i o n H o l e N u m b e r : TP - 2 De p t h (I n . ) So i l Ho r i z o n / La y e r So i l M a t r i x : Co l o r - M o i s t (M u n s e l l ) Re d o x i m o r p h i c F e a t u r e s (m o t t l e s ) So i l Te x t u r e (U S D A ) Co a r s e F r a g m e n t s % b y V o l u m e So i l S t r u c t u r e S o i l Co n s i s t e n c e (M o i s t ) Ot h e r De p t h C o l o r Pe r c e n t Gr a v e l C o b b l e s & S t o n e s 0- 1 F i l l L S F R 1- 9 F i l l S M F R 9- 3 6 F i l l S 5 0 M F R 36 - 7 0 F i l l S M F R 70 - 9 0 F i l l A s h - F R Ad d i t i o n a l N o t e s DE P F o r m 1 1 S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s a l • P a g e 3 o f 5 Co m m o n w e a l t h o f M a s s a c h u s e t t s Ci t y / T o w n o f Fo r m 1 1 - S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s al D a t e : 8 / 2 / 1 9 25 M a p l e A v e n u e , N o r t h a m p t o n , M A De e p O b s e r v a t i o n H o l e N u m b e r : TP - 3 , 4 , 5 De p t h (I n . ) So i l Ho r i z o n / La y e r So i l M a t r i x : Co l o r - M o i s t (M u n s e l l ) Re d o x i m o r p h i c F e a t u r e s (m o t t l e s ) So i l Te x t u r e (U S D A ) Co a r s e F r a g m e n t s % b y V o l u m e So i l S t r u c t u r e S o i l Co n s i s t e n c e (M o i s t ) Ot h e r De p t h C o l o r Pe r c e n t Gr a v e l C o b b l e s & S t o n e s TP - 3 0- 1 8 Fi l l C l a y M F 18 - 6 5 F i l l S an d M F R 65 - 7 8 F i l l A s h M F R TP - 4 0- 3 8 Fi l l C l a y M F TP - 5 0- 3 0 Fi l l C l a y m F Ad d i t i o n a l N o t e s T P - 3 M i x e d f i l l w i t h c l a y c a p . L S , F S , S a n d a s h TP - 4 C l a y w i t h m i x o f g r a v e l a s p h a l t a n d b r i c k DE P F o r m 1 1 S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s a l • P a g e 4 o f 5 Co m m o n w e a l t h o f M a s s a c h u s e t t s Ci t y / T o w n o f Fo r m 1 1 - S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s al D a t e : 8 / 2 / 1 9 25 M a p l e A v e n u e , N o r t h a m p t o n , M A De e p O b s e r v a t i o n H o l e N u m b e r : TP - 6 , 7 , 8 De p t h (I n . ) So i l Ho r i z o n / La y e r So i l M a t r i x : Co l o r - M o i s t (M u n s e l l ) Re d o x i m o r p h i c F e a t u r e s (m o t t l e s ) So i l Te x t u r e (U S D A ) Co a r s e F r a g m e n t s % b y V o l u m e So i l S t r u c t u r e S o i l Co n s i s t e n c e (M o i s t ) Ot h e r De p t h C o l o r Pe r c e n t Gr a v e l C o b b l e s & S t o n e s TP 6 0- 6 2 Fi l l C l a y m i x M F TP - 7 0- 4 8 Fi l l C l a y m i x M F 48 - 8 2 F i l l F L S 5 M F R TP - 8 0- 1 2 Fi l l C l a y m i x 5 M F 12 - 4 0 F i l l F L S M F R 40 - 6 6 F i l l S w i t h Br i c k S G F R 66 - 6 8 F i l l A s h F R Ad d i t i o n a l N o t e s T P - 6 C l a y m i x w i t h B r i c k , g r a v e l a n d c o n c . TP - 7 C l a y m i x w i t h b r i c k g r a v e a n d c o n c . , F L S m o s t l y s a n d w i t h so m e b r i c k TP - 8 C l a y m i x w i t h b r i c k , g r a v e l a n d c o n c . DE P F o r m 1 1 S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s a l • P a g e 5 o f 5 Co m m o n w e a l t h o f M a s s a c h u s e t t s Ci t y / T o w n o f Fo r m 1 1 - S o i l S u i t a b i l i t y A s s e s s m e n t f o r O n - S i t e S e w a g e D i s p o s al D a t e : 8 / 2 0 / 1 9 25 M a p l e A v e n u e , N o r t h a m p t o n , M A De e p O b s e r v a t i o n H o l e N u m b e r : TP - 9 De p t h (I n . ) So i l Ho r i z o n / La y e r So i l M a t r i x : Co l o r - M o i s t (M u n s e l l ) Re d o x i m o r p h i c F e a t u r e s (m o t t l e s ) So i l Te x t u r e (U S D A ) Co a r s e F r a g m e n t s % b y V o l u m e So i l S t r u c tu r e S o i l Co n s i s t e n c e (M o i s t ) Ot h e r De p t h C o l o r Pe r c e n t Gr a v e l C o b b l e s & S t o n e s 0- 2 3 F i l l - F R 23 - 1 0 0 C 1 0 Y R 4 / 3 9 5 1 0 Y R 5 / 8 C F S M F R Ad d i t i o n a l N o t e s F i l l - g r a v e l b r i c k s , t r a s h , a s h e t c . Re d u c e d s a n d s a n d m o t t l e s @ 9 5 " United States Department of Agriculture A product of the National Cooperative Soil Survey, a joint effort of the United States Department of Agriculture and other Federal agencies, State agencies including the Agricultural Experiment Stations, and local participants Custom Soil Resource Report for Hampshire County, Massachusetts, Central Part Natural Resources Conservation Service July 25, 2019 Contents Preface....................................................................................................................2 How Soil Surveys Are Made..................................................................................5 Soil Map..................................................................................................................8 Soil Map................................................................................................................9 Legend................................................................................................................10 Map Unit Legend................................................................................................12 Map Unit Descriptions........................................................................................12 Hampshire County, Massachusetts, Central Part...........................................14 98A—Winooski silt loam, 0 to 3 percent slopes..........................................14 741A—Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes....................................................................................15 744A—Hadley-Winooski-Urban land complex, 0 to 3 percent slopes.........17 References............................................................................................................19 4 Soil Map The soil map section includes the soil map for the defined area of interest, a list of soil map units on the map and extent of each map unit, and cartographic symbols displayed on the map. Also presented are various metadata about data used to produce the map, and a description of each soil map unit. 8 9 Custom Soil Resource Report Soil Map 46 8 7 5 5 0 46 8 7 5 8 0 46 8 7 6 1 0 46 8 7 6 4 0 46 8 7 6 7 0 46 8 7 7 0 0 46 8 7 7 3 0 46 8 7 5 5 0 46 8 7 5 8 0 46 8 7 6 1 0 46 8 7 6 4 0 46 8 7 6 7 0 46 8 7 7 0 0 46 8 7 7 3 0 695190 695220 695250 695280 695310 695340 695370 695400 695430 695460 695490 695220 695250 695280 695310 695340 695370 695400 695430 695460 695490 42° 19' 2'' N 72 ° 3 7 ' 5 3 ' ' W 42° 19' 2'' N 72 ° 3 7 ' 3 9 ' ' W 42° 18' 56'' N 72 ° 3 7 ' 5 3 ' ' W 42° 18' 56'' N 72 ° 3 7 ' 3 9 ' ' W N Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84 0 50 100 200 300 Feet 0 20 40 80 120 Meters Map Scale: 1:1,400 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 Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:15,800. 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: Hampshire County, Massachusetts, Central Part Survey Area Data: Version 13, Sep 10, 2018 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Sep 29, 2013—Oct 16, 2016 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background Custom Soil Resource Report 10 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 98A Winooski silt loam, 0 to 3 percent slopes 0.2 2.3% 741A Amostown-Windsor silty substratum-Urban land complex, 0 to 3 percent slopes 1.5 17.2% 744A Hadley-Winooski-Urban land complex, 0 to 3 percent slopes 7.3 80.5% Totals for Area of Interest 9.0 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. Custom Soil Resource Report 12 The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. Soils that have profiles that are almost alike make up a soil series. Except for differences in texture of the surface layer, all the soils of a series have major horizons that are similar in composition, thickness, and arrangement. Soils of one series can differ in texture of the surface layer, slope, stoniness, salinity, degree of erosion, and other characteristics that affect their use. On the basis of such differences, a soil series is divided into soil phases. Most of the areas shown on the detailed soil maps are phases of soil series. The name of a soil phase commonly indicates a feature that affects use or management. For example, Alpha silt loam, 0 to 2 percent slopes, is a phase of the Alpha series. Some map units are made up of two or more major soils or miscellaneous areas. These map units are complexes, associations, or undifferentiated groups. A complex consists of two or more soils or miscellaneous areas in such an intricate pattern or in such small areas that they cannot be shown separately on the maps. The pattern and proportion of the soils or miscellaneous areas are somewhat similar in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example. An association is made up of two or more geographically associated soils or miscellaneous areas that are shown as one unit on the maps. Because of present or anticipated uses of the map units in the survey area, it was not considered practical or necessary to map the soils or miscellaneous areas separately. The pattern and relative proportion of the soils or miscellaneous areas are somewhat similar. Alpha-Beta association, 0 to 2 percent slopes, is an example. An undifferentiated group is made up of two or more soils or miscellaneous areas that could be mapped individually but are mapped as one unit because similar interpretations can be made for use and management. The pattern and proportion of the soils or miscellaneous areas in a mapped area are not uniform. An area can be made up of only one of the major soils or miscellaneous areas, or it can be made up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example. Some surveys include miscellaneous areas. Such areas have little or no soil material and support little or no vegetation. Rock outcrop is an example. Custom Soil Resource Report 13 744A—Hadley-Winooski-Urban land complex, 0 to 3 percent slopes Map Unit Setting National map unit symbol: 9b03 Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 45 to 52 degrees F Frost-free period: 120 to 240 days Farmland classification: Not prime farmland Map Unit Composition Hadley and similar soils: 45 percent Winooski and similar soils: 20 percent Urban land: 20 percent Minor components: 15 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Hadley Setting Landform: Flood plains Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Friable coarse-silty alluvium Typical profile H1 - 0 to 11 inches: silt loam H2 - 11 to 68 inches: silt loam H3 - 68 to 72 inches: loamy fine sand Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 2.00 in/hr) Depth to water table: About 48 to 72 inches Frequency of flooding: Occasional Frequency of ponding: None Available water storage in profile: High (about 10.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 1 Hydrologic Soil Group: B Hydric soil rating: No Custom Soil Resource Report 17 Description of Winooski Setting Landform: Flood plains Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Tread Down-slope shape: Linear Across-slope shape: Linear Parent material: Silty alluvium Typical profile H1 - 0 to 17 inches: silt loam H2 - 17 to 60 inches: silt loam Properties and qualities Slope: 0 to 3 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Moderately well drained Runoff class: Very low Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.60 to 6.00 in/hr) Depth to water table: About 18 to 36 inches Frequency of flooding: Occasional Frequency of ponding: None Available water storage in profile: High (about 10.5 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2w Hydrologic Soil Group: B Hydric soil rating: No Description of Urban Land Setting Parent material: Paved/filled Minor Components Limerick Percent of map unit: 10 percent Landform: Alluvial flats Hydric soil rating: Yes Saco Percent of map unit: 5 percent Landform: Alluvial flats Hydric soil rating: Yes Custom Soil Resource Report 18 T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com Appendix C: Hydrologic Analyses 1S 2S 4R Northern Perimeter 5R Eastern Perimeter Routing Diagram for Pre-Dev Prepared by T Reynolds Engineering, Printed 8/22/2019 HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Subcat Reach Pond Link Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 2HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 7,464 61 >75% Grass cover, Good, HSG B (1S) 4,443 96 Gravel surface, HSG B (1S, 2S) 728 98 Paved parking, HSG B (1S, 2S) 528 98 Roofs, HSG B (1S) 3,786 58 Woods/grass comb., Good, HSG B (2S) 20,725 79 Woods/grass comb., Good, HSG D (1S, 2S) 37,674 76 TOTAL AREA Type III 24-hr 2-Year Event Rainfall=3.08"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 3HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=15,976 sf 4.51% Impervious Runoff Depth>0.78"Subcatchment 1S: Tc=6.0 min CN=72 Runoff=0.33 cfs 1,032 cf Runoff Area=21,698 sf 2.47% Impervious Runoff Depth>1.15"Subcatchment 2S: Tc=6.0 min CN=79 Runoff=0.70 cfs 2,076 cf Inflow=0.70 cfs 2,076 cfReach 4R: Northern Perimeter Outflow=0.70 cfs 2,076 cf Inflow=0.33 cfs 1,032 cfReach 5R: Eastern Perimeter Outflow=0.33 cfs 1,032 cf Total Runoff Area = 37,674 sf Runoff Volume = 3,109 cf Average Runoff Depth = 0.99" 96.67% Pervious = 36,418 sf 3.33% Impervious = 1,256 sf Type III 24-hr 2-Year Event Rainfall=3.08"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 4HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Runoff = 0.33 cfs @ 12.10 hrs, Volume= 1,032 cf, Depth> 0.78" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Event Rainfall=3.08" Area (sf) CN Description 528 98 Roofs, HSG B 7,464 61 >75% Grass cover, Good, HSG B 192 98 Paved parking, HSG B 597 96 Gravel surface, HSG B 7,195 79 Woods/grass comb., Good, HSG D 15,976 72 Weighted Average 15,256 95.49% Pervious Area 720 4.51% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 0.70 cfs @ 12.10 hrs, Volume= 2,076 cf, Depth> 1.15" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Event Rainfall=3.08" Area (sf) CN Description 3,846 96 Gravel surface, HSG B 536 98 Paved parking, HSG B 3,786 58 Woods/grass comb., Good, HSG B 13,530 79 Woods/grass comb., Good, HSG D 21,698 79 Weighted Average 21,162 97.53% Pervious Area 536 2.47% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach 4R: Northern Perimeter Inflow Area = 21,698 sf, 2.47% Impervious, Inflow Depth > 1.15" for 2-Year Event event Inflow = 0.70 cfs @ 12.10 hrs, Volume= 2,076 cf Outflow = 0.70 cfs @ 12.10 hrs, Volume= 2,076 cf, Atten= 0%, Lag= 0.0 min Type III 24-hr 2-Year Event Rainfall=3.08"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 5HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach 5R: Eastern Perimeter Inflow Area = 15,976 sf, 4.51% Impervious, Inflow Depth > 0.78" for 2-Year Event event Inflow = 0.33 cfs @ 12.10 hrs, Volume= 1,032 cf Outflow = 0.33 cfs @ 12.10 hrs, Volume= 1,032 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 6HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=15,976 sf 4.51% Impervious Runoff Depth>1.98"Subcatchment 1S: Tc=6.0 min CN=72 Runoff=0.90 cfs 2,636 cf Runoff Area=21,698 sf 2.47% Impervious Runoff Depth>2.56"Subcatchment 2S: Tc=6.0 min CN=79 Runoff=1.57 cfs 4,623 cf Inflow=1.57 cfs 4,623 cfReach 4R: Northern Perimeter Outflow=1.57 cfs 4,623 cf Inflow=0.90 cfs 2,636 cfReach 5R: Eastern Perimeter Outflow=0.90 cfs 2,636 cf Total Runoff Area = 37,674 sf Runoff Volume = 7,259 cf Average Runoff Depth = 2.31" 96.67% Pervious = 36,418 sf 3.33% Impervious = 1,256 sf Type III 24-hr 10-Year Event Rainfall=4.93"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 7HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Runoff = 0.90 cfs @ 12.10 hrs, Volume= 2,636 cf, Depth> 1.98" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93" Area (sf) CN Description 528 98 Roofs, HSG B 7,464 61 >75% Grass cover, Good, HSG B 192 98 Paved parking, HSG B 597 96 Gravel surface, HSG B 7,195 79 Woods/grass comb., Good, HSG D 15,976 72 Weighted Average 15,256 95.49% Pervious Area 720 4.51% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 1.57 cfs @ 12.09 hrs, Volume= 4,623 cf, Depth> 2.56" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93" Area (sf) CN Description 3,846 96 Gravel surface, HSG B 536 98 Paved parking, HSG B 3,786 58 Woods/grass comb., Good, HSG B 13,530 79 Woods/grass comb., Good, HSG D 21,698 79 Weighted Average 21,162 97.53% Pervious Area 536 2.47% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach 4R: Northern Perimeter Inflow Area = 21,698 sf, 2.47% Impervious, Inflow Depth > 2.56" for 10-Year Event event Inflow = 1.57 cfs @ 12.09 hrs, Volume= 4,623 cf Outflow = 1.57 cfs @ 12.09 hrs, Volume= 4,623 cf, Atten= 0%, Lag= 0.0 min Type III 24-hr 10-Year Event Rainfall=4.93"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 8HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach 5R: Eastern Perimeter Inflow Area = 15,976 sf, 4.51% Impervious, Inflow Depth > 1.98" for 10-Year Event event Inflow = 0.90 cfs @ 12.10 hrs, Volume= 2,636 cf Outflow = 0.90 cfs @ 12.10 hrs, Volume= 2,636 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 9HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=15,976 sf 4.51% Impervious Runoff Depth>4.29"Subcatchment 1S: Tc=6.0 min CN=72 Runoff=1.93 cfs 5,709 cf Runoff Area=21,698 sf 2.47% Impervious Runoff Depth>5.08"Subcatchment 2S: Tc=6.0 min CN=79 Runoff=3.05 cfs 9,178 cf Inflow=3.05 cfs 9,178 cfReach 4R: Northern Perimeter Outflow=3.05 cfs 9,178 cf Inflow=1.93 cfs 5,709 cfReach 5R: Eastern Perimeter Outflow=1.93 cfs 5,709 cf Total Runoff Area = 37,674 sf Runoff Volume = 14,887 cf Average Runoff Depth = 4.74" 96.67% Pervious = 36,418 sf 3.33% Impervious = 1,256 sf Type III 24-hr 100-Year Event Rainfall=7.88"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 10HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Runoff = 1.93 cfs @ 12.09 hrs, Volume= 5,709 cf, Depth> 4.29" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88" Area (sf) CN Description 528 98 Roofs, HSG B 7,464 61 >75% Grass cover, Good, HSG B 192 98 Paved parking, HSG B 597 96 Gravel surface, HSG B 7,195 79 Woods/grass comb., Good, HSG D 15,976 72 Weighted Average 15,256 95.49% Pervious Area 720 4.51% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 3.05 cfs @ 12.09 hrs, Volume= 9,178 cf, Depth> 5.08" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88" Area (sf) CN Description 3,846 96 Gravel surface, HSG B 536 98 Paved parking, HSG B 3,786 58 Woods/grass comb., Good, HSG B 13,530 79 Woods/grass comb., Good, HSG D 21,698 79 Weighted Average 21,162 97.53% Pervious Area 536 2.47% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach 4R: Northern Perimeter Inflow Area = 21,698 sf, 2.47% Impervious, Inflow Depth > 5.08" for 100-Year Event event Inflow = 3.05 cfs @ 12.09 hrs, Volume= 9,178 cf Outflow = 3.05 cfs @ 12.09 hrs, Volume= 9,178 cf, Atten= 0%, Lag= 0.0 min Type III 24-hr 100-Year Event Rainfall=7.88"Pre-Dev Printed 8/22/2019Prepared by T Reynolds Engineering Page 11HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach 5R: Eastern Perimeter Inflow Area = 15,976 sf, 4.51% Impervious, Inflow Depth > 4.29" for 100-Year Event event Inflow = 1.93 cfs @ 12.09 hrs, Volume= 5,709 cf Outflow = 1.93 cfs @ 12.09 hrs, Volume= 5,709 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs 1S 2aS 2bS Roof 2S 4R Northern Perimeter 5R Eastern Perimeter 3P Subsurface Infiltration Routing Diagram for Post-Dev Prepared by T Reynolds Engineering, Printed 10/23/2019 HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Subcat Reach Pond Link Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 2HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Area Listing (all nodes) Area (sq-ft) CN Description (subcatchment-numbers) 4,069 61 >75% Grass cover, Good, HSG B (1S, 2aS) 6,245 98 Paved parking, HSG B (2aS) 200 98 Paved patios, HSG B (1S) 3,890 98 Roofs, HSG B (2aS, 2bS) 3,656 58 Woods/grass comb., Good, HSG B (2S) 19,612 79 Woods/grass comb., Good, HSG D (1S, 2S) 37,672 80 TOTAL AREA Type III 24-hr 2-Year Event Rainfall=3.08"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 3HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=8,160 sf 2.45% Impervious Runoff Depth>1.03"Subcatchment 1S: Tc=6.0 min CN=77 Runoff=0.24 cfs 702 cf Runoff Area=9,506 sf 71.27% Impervious Runoff Depth>1.69"Subcatchment 2aS: Tc=6.0 min CN=87 Runoff=0.45 cfs 1,340 cf Runoff Area=3,360 sf 100.00% Impervious Runoff Depth>2.66"Subcatchment 2bS: Roof Tc=6.0 min CN=98 Runoff=0.22 cfs 746 cf Runoff Area=16,646 sf 0.00% Impervious Runoff Depth>0.87"Subcatchment 2S: Tc=6.0 min CN=74 Runoff=0.40 cfs 1,212 cf Inflow=0.70 cfs 1,679 cfReach 4R: Northern Perimeter Outflow=0.70 cfs 1,679 cf Inflow=0.24 cfs 702 cfReach 5R: Eastern Perimeter Outflow=0.24 cfs 702 cf Peak Elev=114.48' Storage=0.006 af Inflow=0.68 cfs 2,085 cfPond 3P: Subsurface Infiltration Discarded=0.13 cfs 1,620 cf Primary=0.34 cfs 467 cf Outflow=0.47 cfs 2,088 cf Total Runoff Area = 37,672 sf Runoff Volume = 3,999 cf Average Runoff Depth = 1.27" 72.57% Pervious = 27,337 sf 27.43% Impervious = 10,335 sf Type III 24-hr 2-Year Event Rainfall=3.08"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 4HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Runoff = 0.24 cfs @ 12.10 hrs, Volume= 702 cf, Depth> 1.03" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Event Rainfall=3.08" Area (sf) CN Description 1,338 61 >75% Grass cover, Good, HSG B * 200 98 Paved patios, HSG B 6,622 79 Woods/grass comb., Good, HSG D 8,160 77 Weighted Average 7,960 97.55% Pervious Area 200 2.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2aS: Runoff = 0.45 cfs @ 12.09 hrs, Volume= 1,340 cf, Depth> 1.69" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Event Rainfall=3.08" Area (sf) CN Description 2,731 61 >75% Grass cover, Good, HSG B 6,245 98 Paved parking, HSG B 530 98 Roofs, HSG B 9,506 87 Weighted Average 2,731 28.73% Pervious Area 6,775 71.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2bS: Roof Runoff = 0.22 cfs @ 12.09 hrs, Volume= 746 cf, Depth> 2.66" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Event Rainfall=3.08" Area (sf) CN Description 3,360 98 Roofs, HSG B 3,360 100.00% Impervious Area Type III 24-hr 2-Year Event Rainfall=3.08"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 5HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 0.40 cfs @ 12.10 hrs, Volume= 1,212 cf, Depth> 0.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 2-Year Event Rainfall=3.08" Area (sf) CN Description 3,656 58 Woods/grass comb., Good, HSG B 12,990 79 Woods/grass comb., Good, HSG D 16,646 74 Weighted Average 16,646 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach 4R: Northern Perimeter Inflow Area = 29,512 sf, 34.34% Impervious, Inflow Depth > 0.68" for 2-Year Event event Inflow = 0.70 cfs @ 12.12 hrs, Volume= 1,679 cf Outflow = 0.70 cfs @ 12.12 hrs, Volume= 1,679 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach 5R: Eastern Perimeter Inflow Area = 8,160 sf, 2.45% Impervious, Inflow Depth > 1.03" for 2-Year Event event Inflow = 0.24 cfs @ 12.10 hrs, Volume= 702 cf Outflow = 0.24 cfs @ 12.10 hrs, Volume= 702 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Pond 3P: Subsurface Infiltration Inflow Area = 12,866 sf, 78.77% Impervious, Inflow Depth > 1.94" for 2-Year Event event Inflow = 0.68 cfs @ 12.09 hrs, Volume= 2,085 cf Outflow = 0.47 cfs @ 12.18 hrs, Volume= 2,088 cf, Atten= 30%, Lag= 5.3 min Discarded = 0.13 cfs @ 12.18 hrs, Volume= 1,620 cf Primary = 0.34 cfs @ 12.18 hrs, Volume= 467 cf Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 114.48' @ 12.18 hrs Surf.Area= 0.011 ac Storage= 0.006 af Flood Elev= 118.00' Surf.Area= 0.011 ac Storage= 0.028 af Plug-Flow detention time= (not calculated: outflow precedes inflow) Type III 24-hr 2-Year Event Rainfall=3.08"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 6HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Center-of-Mass det. time= 6.6 min ( 775.7 - 769.1 ) Volume Invert Avail.Storage Storage Description #1A 113.50' 0.012 af 18.50'W x 26.50'L x 4.00'H Field A 0.045 af Overall - 0.016 af Embedded = 0.029 af x 40.0% Voids #2A 114.00' 0.016 af Cultec R-360HD x 18 Inside #1 Effective Size= 54.9"W x 36.0"H => 9.99 sf x 3.67'L = 36.6 cf Overall Size= 60.0"W x 36.0"H x 4.17'L with 0.50' Overlap 18 Chambers in 3 Rows Cap Storage= +6.5 cf x 2 x 3 rows = 38.8 cf 0.028 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 113.50'8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 111.00' #2 Primary 113.50'8.0" Round Culvert L= 60.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 113.50' / 112.90' S= 0.0100 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 0.35 sf #3 Device 2 114.00'5.0" Vert. Orifice/Grate C= 0.600 #4 Device 2 116.00'4.0" Vert. Orifice/Grate C= 0.600 #5 Device 2 116.50'8.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.13 cfs @ 12.18 hrs HW=114.47' (Free Discharge) 1=Exfiltration ( Controls 0.13 cfs) Primary OutFlow Max=0.34 cfs @ 12.18 hrs HW=114.47' TW=0.00' (Dynamic Tailwater) 2=Culvert (Passes 0.34 cfs of 1.06 cfs potential flow) 3=Orifice/Grate (Orifice Controls 0.34 cfs @ 2.47 fps) 4=Orifice/Grate ( Controls 0.00 cfs) 5=Orifice/Grate ( Controls 0.00 cfs) Type III 24-hr 10-Year Event Rainfall=4.93"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 7HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=8,160 sf 2.45% Impervious Runoff Depth>2.39"Subcatchment 1S: Tc=6.0 min CN=77 Runoff=0.55 cfs 1,622 cf Runoff Area=9,506 sf 71.27% Impervious Runoff Depth>3.30"Subcatchment 2aS: Tc=6.0 min CN=87 Runoff=0.86 cfs 2,613 cf Runoff Area=3,360 sf 100.00% Impervious Runoff Depth>4.35"Subcatchment 2bS: Roof Tc=6.0 min CN=98 Runoff=0.36 cfs 1,219 cf Runoff Area=16,646 sf 0.00% Impervious Runoff Depth>2.14"Subcatchment 2S: Tc=6.0 min CN=74 Runoff=1.01 cfs 2,966 cf Inflow=1.57 cfs 4,266 cfReach 4R: Northern Perimeter Outflow=1.57 cfs 4,266 cf Inflow=0.55 cfs 1,622 cfReach 5R: Eastern Perimeter Outflow=0.55 cfs 1,622 cf Peak Elev=115.13' Storage=0.012 af Inflow=1.22 cfs 3,832 cfPond 3P: Subsurface Infiltration Discarded=0.15 cfs 2,531 cf Primary=0.63 cfs 1,300 cf Outflow=0.78 cfs 3,831 cf Total Runoff Area = 37,672 sf Runoff Volume = 8,420 cf Average Runoff Depth = 2.68" 72.57% Pervious = 27,337 sf 27.43% Impervious = 10,335 sf Type III 24-hr 10-Year Event Rainfall=4.93"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 8HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Runoff = 0.55 cfs @ 12.09 hrs, Volume= 1,622 cf, Depth> 2.39" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93" Area (sf) CN Description 1,338 61 >75% Grass cover, Good, HSG B * 200 98 Paved patios, HSG B 6,622 79 Woods/grass comb., Good, HSG D 8,160 77 Weighted Average 7,960 97.55% Pervious Area 200 2.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2aS: Runoff = 0.86 cfs @ 12.09 hrs, Volume= 2,613 cf, Depth> 3.30" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93" Area (sf) CN Description 2,731 61 >75% Grass cover, Good, HSG B 6,245 98 Paved parking, HSG B 530 98 Roofs, HSG B 9,506 87 Weighted Average 2,731 28.73% Pervious Area 6,775 71.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2bS: Roof Runoff = 0.36 cfs @ 12.09 hrs, Volume= 1,219 cf, Depth> 4.35" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93" Area (sf) CN Description 3,360 98 Roofs, HSG B 3,360 100.00% Impervious Area Type III 24-hr 10-Year Event Rainfall=4.93"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 9HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 1.01 cfs @ 12.09 hrs, Volume= 2,966 cf, Depth> 2.14" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 10-Year Event Rainfall=4.93" Area (sf) CN Description 3,656 58 Woods/grass comb., Good, HSG B 12,990 79 Woods/grass comb., Good, HSG D 16,646 74 Weighted Average 16,646 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach 4R: Northern Perimeter Inflow Area = 29,512 sf, 34.34% Impervious, Inflow Depth > 1.73" for 10-Year Event event Inflow = 1.57 cfs @ 12.11 hrs, Volume= 4,266 cf Outflow = 1.57 cfs @ 12.11 hrs, Volume= 4,266 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach 5R: Eastern Perimeter Inflow Area = 8,160 sf, 2.45% Impervious, Inflow Depth > 2.39" for 10-Year Event event Inflow = 0.55 cfs @ 12.09 hrs, Volume= 1,622 cf Outflow = 0.55 cfs @ 12.09 hrs, Volume= 1,622 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Pond 3P: Subsurface Infiltration Inflow Area = 12,866 sf, 78.77% Impervious, Inflow Depth > 3.57" for 10-Year Event event Inflow = 1.22 cfs @ 12.09 hrs, Volume= 3,832 cf Outflow = 0.78 cfs @ 12.19 hrs, Volume= 3,831 cf, Atten= 36%, Lag= 6.2 min Discarded = 0.15 cfs @ 12.19 hrs, Volume= 2,531 cf Primary = 0.63 cfs @ 12.19 hrs, Volume= 1,300 cf Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 115.13' @ 12.19 hrs Surf.Area= 0.011 ac Storage= 0.012 af Flood Elev= 118.00' Surf.Area= 0.011 ac Storage= 0.028 af Plug-Flow detention time= (not calculated: outflow precedes inflow) Type III 24-hr 10-Year Event Rainfall=4.93"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 10HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Center-of-Mass det. time= 7.0 min ( 766.0 - 759.0 ) Volume Invert Avail.Storage Storage Description #1A 113.50' 0.012 af 18.50'W x 26.50'L x 4.00'H Field A 0.045 af Overall - 0.016 af Embedded = 0.029 af x 40.0% Voids #2A 114.00' 0.016 af Cultec R-360HD x 18 Inside #1 Effective Size= 54.9"W x 36.0"H => 9.99 sf x 3.67'L = 36.6 cf Overall Size= 60.0"W x 36.0"H x 4.17'L with 0.50' Overlap 18 Chambers in 3 Rows Cap Storage= +6.5 cf x 2 x 3 rows = 38.8 cf 0.028 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 113.50'8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 111.00' #2 Primary 113.50'8.0" Round Culvert L= 60.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 113.50' / 112.90' S= 0.0100 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 0.35 sf #3 Device 2 114.00'5.0" Vert. Orifice/Grate C= 0.600 #4 Device 2 116.00'4.0" Vert. Orifice/Grate C= 0.600 #5 Device 2 116.50'8.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.15 cfs @ 12.19 hrs HW=115.12' (Free Discharge) 1=Exfiltration ( Controls 0.15 cfs) Primary OutFlow Max=0.63 cfs @ 12.19 hrs HW=115.12' TW=0.00' (Dynamic Tailwater) 2=Culvert (Passes 0.63 cfs of 1.51 cfs potential flow) 3=Orifice/Grate (Orifice Controls 0.63 cfs @ 4.60 fps) 4=Orifice/Grate ( Controls 0.00 cfs) 5=Orifice/Grate ( Controls 0.00 cfs) Type III 24-hr 100-Year Event Rainfall=7.88"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 11HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Dyn-Stor-Ind method - Pond routing by Dyn-Stor-Ind method Runoff Area=8,160 sf 2.45% Impervious Runoff Depth>4.85"Subcatchment 1S: Tc=6.0 min CN=77 Runoff=1.10 cfs 3,297 cf Runoff Area=9,506 sf 71.27% Impervious Runoff Depth>5.99"Subcatchment 2aS: Tc=6.0 min CN=87 Runoff=1.51 cfs 4,742 cf Runoff Area=3,360 sf 100.00% Impervious Runoff Depth>7.04"Subcatchment 2bS: Roof Tc=6.0 min CN=98 Runoff=0.58 cfs 1,970 cf Runoff Area=16,646 sf 0.00% Impervious Runoff Depth>4.51"Subcatchment 2S: Tc=6.0 min CN=74 Runoff=2.11 cfs 6,258 cf Inflow=2.98 cfs 9,187 cfReach 4R: Northern Perimeter Outflow=2.98 cfs 9,187 cf Inflow=1.10 cfs 3,297 cfReach 5R: Eastern Perimeter Outflow=1.10 cfs 3,297 cf Peak Elev=116.39' Storage=0.022 af Inflow=2.09 cfs 6,712 cfPond 3P: Subsurface Infiltration Discarded=0.20 cfs 3,781 cf Primary=1.17 cfs 2,929 cf Outflow=1.37 cfs 6,710 cf Total Runoff Area = 37,672 sf Runoff Volume = 16,267 cf Average Runoff Depth = 5.18" 72.57% Pervious = 27,337 sf 27.43% Impervious = 10,335 sf Type III 24-hr 100-Year Event Rainfall=7.88"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 12HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Summary for Subcatchment 1S: Runoff = 1.10 cfs @ 12.09 hrs, Volume= 3,297 cf, Depth> 4.85" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88" Area (sf) CN Description 1,338 61 >75% Grass cover, Good, HSG B * 200 98 Paved patios, HSG B 6,622 79 Woods/grass comb., Good, HSG D 8,160 77 Weighted Average 7,960 97.55% Pervious Area 200 2.45% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2aS: Runoff = 1.51 cfs @ 12.09 hrs, Volume= 4,742 cf, Depth> 5.99" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88" Area (sf) CN Description 2,731 61 >75% Grass cover, Good, HSG B 6,245 98 Paved parking, HSG B 530 98 Roofs, HSG B 9,506 87 Weighted Average 2,731 28.73% Pervious Area 6,775 71.27% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2bS: Roof Runoff = 0.58 cfs @ 12.09 hrs, Volume= 1,970 cf, Depth> 7.04" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88" Area (sf) CN Description 3,360 98 Roofs, HSG B 3,360 100.00% Impervious Area Type III 24-hr 100-Year Event Rainfall=7.88"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 13HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Subcatchment 2S: Runoff = 2.11 cfs @ 12.09 hrs, Volume= 6,258 cf, Depth> 4.51" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type III 24-hr 100-Year Event Rainfall=7.88" Area (sf) CN Description 3,656 58 Woods/grass comb., Good, HSG B 12,990 79 Woods/grass comb., Good, HSG D 16,646 74 Weighted Average 16,646 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Summary for Reach 4R: Northern Perimeter Inflow Area = 29,512 sf, 34.34% Impervious, Inflow Depth > 3.74" for 100-Year Event event Inflow = 2.98 cfs @ 12.11 hrs, Volume= 9,187 cf Outflow = 2.98 cfs @ 12.11 hrs, Volume= 9,187 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Reach 5R: Eastern Perimeter Inflow Area = 8,160 sf, 2.45% Impervious, Inflow Depth > 4.85" for 100-Year Event event Inflow = 1.10 cfs @ 12.09 hrs, Volume= 3,297 cf Outflow = 1.10 cfs @ 12.09 hrs, Volume= 3,297 cf, Atten= 0%, Lag= 0.0 min Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Summary for Pond 3P: Subsurface Infiltration Inflow Area = 12,866 sf, 78.77% Impervious, Inflow Depth > 6.26" for 100-Year Event event Inflow = 2.09 cfs @ 12.09 hrs, Volume= 6,712 cf Outflow = 1.37 cfs @ 12.19 hrs, Volume= 6,710 cf, Atten= 35%, Lag= 6.0 min Discarded = 0.20 cfs @ 12.19 hrs, Volume= 3,781 cf Primary = 1.17 cfs @ 12.19 hrs, Volume= 2,929 cf Routing by Dyn-Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 116.39' @ 12.19 hrs Surf.Area= 0.011 ac Storage= 0.022 af Flood Elev= 118.00' Surf.Area= 0.011 ac Storage= 0.028 af Plug-Flow detention time= (not calculated: outflow precedes inflow) Type III 24-hr 100-Year Event Rainfall=7.88"Post-Dev Printed 10/23/2019Prepared by T Reynolds Engineering Page 14HydroCAD® 10.00-25 s/n 04155 © 2019 HydroCAD Software Solutions LLC Center-of-Mass det. time= 9.1 min ( 758.9 - 749.8 ) Volume Invert Avail.Storage Storage Description #1A 113.50' 0.012 af 18.50'W x 26.50'L x 4.00'H Field A 0.045 af Overall - 0.016 af Embedded = 0.029 af x 40.0% Voids #2A 114.00' 0.016 af Cultec R-360HD x 18 Inside #1 Effective Size= 54.9"W x 36.0"H => 9.99 sf x 3.67'L = 36.6 cf Overall Size= 60.0"W x 36.0"H x 4.17'L with 0.50' Overlap 18 Chambers in 3 Rows Cap Storage= +6.5 cf x 2 x 3 rows = 38.8 cf 0.028 af Total Available Storage Storage Group A created with Chamber Wizard Device Routing Invert Outlet Devices #1 Discarded 113.50'8.270 in/hr Exfiltration over Surface area Conductivity to Groundwater Elevation = 111.00' #2 Primary 113.50'8.0" Round Culvert L= 60.0' CPP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 113.50' / 112.90' S= 0.0100 '/' Cc= 0.900 n= 0.010 PVC, smooth interior, Flow Area= 0.35 sf #3 Device 2 114.00'5.0" Vert. Orifice/Grate C= 0.600 #4 Device 2 116.00'4.0" Vert. Orifice/Grate C= 0.600 #5 Device 2 116.50'8.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Discarded OutFlow Max=0.20 cfs @ 12.19 hrs HW=116.37' (Free Discharge) 1=Exfiltration ( Controls 0.20 cfs) Primary OutFlow Max=1.16 cfs @ 12.19 hrs HW=116.37' TW=0.00' (Dynamic Tailwater) 2=Culvert (Passes 1.16 cfs of 2.11 cfs potential flow) 3=Orifice/Grate (Orifice Controls 0.97 cfs @ 7.08 fps) 4=Orifice/Grate (Orifice Controls 0.19 cfs @ 2.18 fps) 5=Orifice/Grate ( Controls 0.00 cfs) T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com Appendix D: TSS Removal Calculation Worksheet Te r r e n c e R . R e y n o l d s , P . E . TS S R e m o v a l C a l c u la t i o n W o r k s h e e t Fl o r e n c e , M A 0 1 0 6 2 Na m e : 2 5 M a p l e A v e P r o j . N o . : 1 8 - 0 9 0 1 Da t e : 8 / 2 0 / 1 9 Lo c a t i o n : N o r t h a m p t o n , M A C o m p u t e d b y : T R Tr e a t m e n t T r a i n T S S R e mo v a l B a s i n s A a n d B C h e c k e d b y : T R AB C D E BM P T S S R e m o v a l S t a r t i n g T S S A m o u n t R e m a i n i n g Ra t e L o a d * R e m o v e d ( B x C ) L o a d ( C - D ) 0. 2 0 Vo r t s e n t r y W a t e r Qu a l i t y U n i t 80 1 . 0 0 0 . 8 T o t a l T S S Re m o v a l = No t e s : *S t a r t i n g T S S L o a d f o r f i r s t B M P = 1 . 0 0 . T S S l o a d f o r s u b s e q u e n t B M P ' s i s e q u a l t o t h e R e m a i n i n g Lo a d ( E ) f r o m t h e p r e v i o u s B M P . 80 % Te r r e n c e R . R e y n o l d s , P . E . Na m e : 2 5 M a p l e A v e P r o j . N o . : 1 18 - 0 9 0 1 Fl o r e n c e , M A 0 1 0 6 2 Da t e : 8 / 2 0 / 1 9 Lo c a t i o n : N o r t h a m p t o n , M A C o m p u t e d b y : T R C h e c k e d b y : T R Im p e r v i o u s A r e a 2 3 0 3 s f D s o i l s F 0 . 1 i n c h e s Im p e r v i o u s A r e a 2 8 1 1 s f B s o i l s Rv = F x im p e r v i o u s a r e a F 0 . 3 5 i n c h e s A = R v ÷ ( D + K T ) D= b a s i n d e p t h 0 . 5 f t V= A x D K= I n f i l t r a t i o n R a t e 8 . 2 7 i n c h e s / h r Rv i s t h e Re q u i r e d R e c h a r g e V o l u m e t= t i m e ( 2 h o u r s f o r R a w l s r a t e s ) 2 h r s ( 1 1 - 1 3 ) F= T a r g e t D e p t h F a c t o r . S e e T a b l e 2 . 3 . 2 . A i s t h e m i n i m u m r e q u i r e d s u r f a c e a r e a o f t h e b o t t o m o f t h e i n f il t r a t i o n s t r u c t u r e Rv = F x I m p e r v i o u s a r e a V i s t h e St o r a g e V o l u m e d e t e r m i n e d i n a c c o r d a n c e w i t h t h e “S i m p l e D y n a m i c ” Me t h o d Rv = 1 0 1 . 2 c f D i s a d e p t h o f t h e i n f i l t r a t i o n f a c i l i t y [ 1 ] A= R v / ( d + K t ) K i s t h e s a t u r a t e d h y d r a u l i c c o n d u c t i v i t y . F o r “ Si m p l e D y n a m i c ” Me t h o d , us e R a w l s R a t e ( S e e T a b l e 2 . 3 . 3 ) , a n d A= 5 3 . 9 s f T i s t h e a l l o w a b l e d r a w d o w n d u r i n g t h e p e a k o f t h e s t o r m ( u s e 2 h o u r s ) V= A X D Ap i s t h e p r o v i d e d s u r f a c e a r e a o f t h e b o t t o m o f t h e i n f i l t r a t i on s t r u c t u r e V= 2 7 c f Vp i s t h e p r o v i d e d s t o r a g e f o r b a s i n Ap = 4 9 0 s f Vp = 2 4 5 c f O K Ba s i n , S t o r a g e V o l u m e S i z i n g C a l c u l a t i o n W o r k s h e e t ( S i m p l e D y n a mi c M e t h o d ) [1 ] I f t h e i n f i l t r a t i o n f a c i l i t y i s a p r a c t i c e t h a t u s e s s t o n e or a n o t h e r m e d i a s u c h a s a d r y w e l l , o n l y t h e v o i d s p a c e s m u s t be c o n s i d e r e d . I n t h o s e c i r c u m s t a n c e s , u s e nd i n s t e a d o f d , w h e r e n i s t h e p e r c e n t p o r o s i t y o f t h e s t o n e o r o t h e r m e d i a . T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com Appendix E: BMPs Checklist Bm p s C h e c k l i s t . d o c 25 M a p l e A v e , N o r t h a m p t o n , M a s s a c h u s e t t s Be s t M a n a g e m e n t P r a c t i c e s – M a i n te n a n c e / E v a l u a t i o n C h e c k l i s t Co n s t r u c t i o n P r a c t i c e s Be s t Ma n a g e m e n t Pr a c t i c e In s p e c t i o n Fr e q u e n c y Da t e In s p e c t e d In s p e c t o r M i n i m u m M a i n t e n a n c e a n d K e y It e m s t o C h e c k Cl e a n i n g / R e p a i r N e e d e d ye s no ( L i s t I t e m s ) Da t e o f Cl e a n i n g / R e p a i r Pe r f o r m e d b y Er o s i o n C o n t r o l Ba r r i e r s On c e a m o n t h a n d im m e d i a t e l y fo l l o w i n g a n y m a j o r st o r m e v e n t . Gr a v e l Co n s t r u c t i o n En t r a n c e On c e a m o n t h a n d im m e d i a t e l y fo l l o w i n g a n y m a j o r st o r m e v e n t . Ve g e t a t e d S l o p e St a b i l i z a t i o n On c e a m o n t h a n d im m e d i a t e l y fo l l o w i n g a n y m a j o r st o r m e v e n t . St o r m w a t e r C o n t r o l M a n a g e r Bm p s C h e c k l i s t . d o c 25 M a p l e A v e , N o r t h a m p t o n , M a s s a c h u s e t t s Be s t M a n a g e m e n t P r a c t i c e s – M a i n te n a n c e / E v a l u a t i o n C h e c k l i s t Lo n g T e r m P r a c t i c e s Be s t Ma n a g e m e n t Pr a c t i c e In s p e c t i o n Fr e q u e n c y Da t e In s p e c t e d In s p e c t o r M i n i m u m M a i n t e n a n c e a n d K e y I t e m s t o Ch e c k Cl e a n i n g / R e p a i r Ne e d e d ye s no ( L i s t I t e m s ) Da t e o f Cl e a n i n g / R e p a i r Pe r f o r m e d by Su b - S u r f a c e In f i l t r a t i o n  I n s p e c t t h e s u b s u r f a c e st o r m w a t e r s y s t e m s af t e r e v e r y m a j o r s t o r m fo r t h e f i r s t f e w m o n t h s to e n s u r e p r o p e r st a b i l i z a t i o n a n d fu n c t i o n . T h e r e a f t e r , in s p e c t t h e m a t l e a s t on c e p e r y e a r .  W a t e r l e v e l s i n t h e o b s e r v a t i o n w e l l s h o u l d b e re c o r d e d o v e r s e v e r a l d a y s t o c h e c k t h e s u b s u r f a c e st o r m w a t e r s y s t e m d r a i n a g e . N e c e s s a r y s e d i m e n t re m o v a l a n d o r r e m o v a l o f d e b r i i n o u t l e t c o n t r o l w i l l be p e r f o r m e d i m m e d i a t e l y u p o n i d e n t i f i c a t i o n . Vo r t s e n t r y H S  Q u a r t e r l y i n s p e c t i o n o f th e s e d i m e n t a n d o i l ch a m b e r s , t o d e v e l o p a sc h e d u l e o f ma i n t e n a n c e .  T h e i n s p e c t i o n a n d cl e a n i n g s c h e d u l e sh o u l d b e r e v i s e d b a s e d on t h e c o n t a m i n a t e lo a d s f o u n d d u r i n g in s p e c t i o n , a n d c l e a n i n g sh o u l d i n c r e a s e i f re q u i r e d .  A t a m i n i m u m , t h e u n i t sh o u l d b e c l e a n e d an n u a l l y t o p r o v i d e p e a k pe r f o r m a n c e .  C l e a n u n i t w h e n t h e s e d i m e n t h a s a c c u m u l a t e d t o a de p t h o f t w o f e e t i n t h e t r e a t m e n t c h a m b e r . T h i s de t e r m i n a t i o n c a n b e m a d e b y t a k i n g t w o me a s u r e m e n t s w i t h a s t a d i a r o d o r s i m i l a r me a s u r i n g d e v i c e ; o n e m e a s u r e m e n t f r o m t h e ma n h o l e o p e n i n g t o t h e t o p o f t h e s e d i m e n t p i l e a n d th e o t h e r f r o m t h e m a n h o l e o p e n i n g t o t h e w a t e r su r f a c e . I f t h e d i f f e r e n c e b e t w e e n t h e s e me a s u r e m e n t s i s l e s s t h a n 3 . 6 f e e t , t h e V o r t S e n t r y HS 3 6 s h o u l d b e m a i n t a i n e d t o e n s u r e e f f e c t i v e tr e a t m e n t . St r e e t Sw e e p i n g Tw i c e a y e a r St o r m w a t e r C o n t r o l M a n a g e r T Reynolds Engineering 25 Maple Avenue Civil Engineers- Planning, Design and Permitting Services Stormwater Drainage Report 8/22/2019 152 Maplewood Terrace, Florence, MA 01062 Phone: 413-387-80787, Fax: 413-727-3477 Email: terry@treynoldsengineering.com Appendix F: Massachusetts Stormwater Report Checklist Massachusetts Stormwater Report Checklist Stormwater Report 1 Stormwater Report A Stormwater Report must be submitted with the permit application to document compliance with the Stormwater Management Standards. The Stormwater Report must be organized into sections that correspond to the categories listed in the Checklist (e.g., Project Type, LID Practices, Standard 1 etc.). 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 by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include:  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 81  Operation and Maintenance Plan required by Standard 9  The Stormwater Checklist completed and stamped by a Registered Professional Engineer (attached) that certifies that the Stormwater Report contains all required submittals.2 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 1 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. 2 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. Massachusetts Stormwater Report Checklist Stormwater Report 2 not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. 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 to comprise 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 8/20/19 Signature, Date Massachusetts Stormwater Report Checklist Stormwater Report 3 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 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 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. 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. Massachusetts Stormwater Report Checklist Stormwater Report 4 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: Circle the method used. Static Simple Dynamic Dynamic Field3 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. 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; 3 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. Massachusetts Stormwater Report Checklist Stormwater Report 5  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. 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 Massachusetts Stormwater Report Checklist Stormwater Report 6 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. 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. 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. Massachusetts Stormwater Report Checklist Stormwater Report 7 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: o Narrative; o Construction Period Operation and Maintenance Plan; o Names of Persons or Entity Responsible for Plan Compliance; o Construction Period Pollution Prevention Measures; o Erosion and Sedimentation Control Plan Drawings; o Detail drawings and specifications for erosion control BMPs, including sizing calculations; o Vegetation Planning; o Site Development Plan; o Construction Sequencing Plan; o Sequencing of Erosion and Sedimentation Controls; o Operation and Maintenance of Erosion and Sedimentation Controls; o Inspection Schedule; o Maintenance Schedule; o 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. 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. Massachusetts Stormwater Report Checklist Stormwater Report 8 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.