2023-12-06 15150-Smith College Stormwater Report updated narrative
November 1, 2023 Revised December 6, 2023
Stormwater Report
Smith College Lazarus-Wurtele Center
College Lane
Northampton MA 01063
Prepared for:
TenBerke Architects D.P.C.
41 Madison Avenue, 17th Floor
New York NY 01001
Prepared by:
Nitsch Engineering
2 Center Plaza, Suite 430
Boston, MA 02108
Nitsch Project #15150
Northampton MA – Stormwater Report
11/01/2023 Revised 12/06/2023 | Nitsch #15150 i
TABLE OF CONTENTS
SECTION 1 Introduction ........................................................................................................................................................ 1
SECTION 2 Existing Conditions .............................................................................................................................................. 2
Existing Drainage Infrastructure ...................................................................................................................................................... 2
Natural Resources Conservation Services (NRCS) Soil Designations ................................................................................................ 2
Onsite Soil Investigations ................................................................................................................................................................. 2
Wetland Resource Areas .................................................................................................................................................................. 2
Total Maximum Daily Load (TMDL) ................................................................................................................................................. 2
SECTION 3 Proposed Conditions ........................................................................................................................................... 3
Project Description ........................................................................................................................................................................... 3
Stormwater Management System ................................................................................................................................................... 3
Stormwater Management During Construction .............................................................................................................................. 4
SECTION 4 Stormwater Management Analysis ..................................................................................................................... 5
Methodology .................................................................................................................................................................................... 5
HydroCAD Version 10.10 .................................................................................................................................................................. 5
Existing Hydrologic Conditions ......................................................................................................................................................... 6
Proposed Hydrologic Conditions ...................................................................................................................................................... 6
Peak Flow Rates ............................................................................................................................................................................... 6
SECTION 5 City of Northampton Stormwater Regulations .................................................................................................... 7
LID Design Strategies ....................................................................................................................................................................... 7
Annual Load Reduction of Phosphorus (50%) and TSS (80%) ........................................................................................................... 7
Annual Load Reduction of Nitrogen ................................................................................................................................................. 7
SECTION 6 MassDEP Stormwater Management Standards ................................................................................................... 8
Standard 1: No New Untreated Discharges ..................................................................................................................................... 8
Standard 2: Peak Rate Attenuation ................................................................................................................................................. 8
Standard 3: Groundwater Recharge ................................................................................................................................................ 8
Standard 4: Water Quality Treatment ............................................................................................................................................. 8
Standard 5: Land Uses with Higher Potential Pollutant Loads ......................................................................................................... 9
Standard 6: Critical Areas ................................................................................................................................................................ 9
Standard 7: Redevelopments ........................................................................................................................................................... 9
Standard 8: Construction Period Pollution Prevention and Sedimentation Control ......................................................................... 9
Standard 9: Operation and Maintenance Plan ................................................................................................................................ 9
Standard 10: Prohibition of Illicit Discharges ................................................................................................................................. 10
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SECTION 7 Closed Drainage System Design ........................................................................................................................ 10
SECTION 8 Conclusion ........................................................................................................................................................ 10
FIGURES ..................................................................................................................................................................................... 11
DR-1 Existing Watershed Areas ..................................................................................................................................................... 11
DR-2 Proposed Watershed Areas ................................................................................................................................................... 11
Figure 1 - USGS Aerial Map ............................................................................................................................................................ 11
Figure 2 - USGS Locus Map ............................................................................................................................................................ 11
Figure 3 - NHESP Map .................................................................................................................................................................... 11
Figure 4 - Wetlands Map ............................................................................................................................................................... 11
Figure 5 - FEMA Flood Map ............................................................................................................................................................ 11
APPENDIX A ............................................................................................................................................................................... 12
Stormwater Management Standards Documentation .................................................................................................................. 12
APPENDIX B ............................................................................................................................................................................... 13
Existing Conditions – HydroCAD Calculations ................................................................................................................................ 13
APPENDIX C ............................................................................................................................................................................... 14
Proposed Conditions – HydroCAD Calculations .............................................................................................................................. 14
APPENDIX D ............................................................................................................................................................................... 15
Closed Drainage System Design ..................................................................................................................................................... 15
APPENDIX E ............................................................................................................................................................................... 16
Long-Term Pollution Prevention and Stormwater Operation and Maintenance Plan ................................................................... 16
APPENDIX F ............................................................................................................................................................................... 17
Draft Stormwater Pollution Prevention Plan (SWPPP) ................................................................................................................... 17
APPENDIX G ............................................................................................................................................................................... 18
Soil Investigations .......................................................................................................................................................................... 18
APPENDIX H ............................................................................................................................................................................... 19
Phosphorus, Nitrogen, and TSS Removal Calculations ................................................................................................................... 19
Northampton MA – Stormwater Report
11/01/2023 Revised 12/06/2023 | Nitsch #15150 1
SECTION 1 Introduction
Nitsch Engineering has prepared this Stormwater Report to support the Site Plan Review and Notice of Intent
application to the City of Northampton for the new Smith College Lazarus-Wurtele Center located in
Northampton, MA. The Project site is located at 8 College Lane in the Smith College Campus (subsequently
referred to as the “Site”).
The site improvements include the following:
1. Demolition of the existing 8 College Lane building;
2. Construction of a new Lazarus-Wurtele Center building;
3. Construction of pedestrian walkways and outdoor space;
4. Installation of new utilities to support the proposed building; and
5. Construction of a new stormwater management system.
The proposed stormwater management system has been designed to comply with the requirements of the City of
Northampton Rules and Regulations and the Massachusetts Department of Environmental Protection (DEP)
Stormwater Management Standards.
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SECTION 2 Existing Conditions
The Site is located at 8 College Lane in Northampton, MA. The site is bound by Chapin Way to the northeast,
College Lane to the west, and the Lyman Plant House and Conservatory to the south. The existing site contains
the existing 8 College Lane building, a parking lot, and supporting site walkways.
Existing Drainage Infrastructure
Stormwater generated by the existing site is collected using a series of interconnected catch basins and is piped
via a closed drainage system to a 12” drainage main in College Lane. The existing stormwater management
system was constructed prior to the 2008 MassDEP Stormwater Management Standards, and the Site provides
minimal peak flow attenuation, water quality treatment, and groundwater recharge.
Natural Resources Conservation Services (NRCS) Soil Designations
There is no data available for the site on the NRCS website. Please refer to the Onsite Soil Sections below for
more information.
Onsite Soil Investigations
Haley and Aldrich performed 6 borings from May 15, 2023 to June 9, 2023. These borings were located around
the proposed building and in the existing parking lot footprint. Results of these borings indicate soils with poor
infiltrating capacity due to the presence of silt and clay layers. Additionally, borings indicate a perched
groundwater table. Haley and Aldrich recommended the design groundwater level to be located at elevation 183.
These boring logs are provided in Appendix G.
Wetland Resource Areas
The site is in proximity to Paradise Pond, which is part of the Mill River. Paradise Pond is located to the
southwest of the site and has a 200-foot jurisdictional Riverfront Area under the Massachusetts Wetlands
Protection Act. Refer to the Wetlands Delineation Report (Attachment C in the NOI) for more information.
Total Maximum Daily Load (TMDL)
The Site ultimately discharges into Paradise Pond, which is part of the Mill River. This portion of the Mill River is
classified as a Category 5 water by the Massachusetts Integrated List of Waters, with an impairment of E. Coli.
The Site is located within the Connecticut River Basin Watershed and will potentially be subject to a Draft
Pathogen Total Maximum Daily Load (TMDL) if it is finalized by MassDEP. The Project has been designed to
minimize stormwater discharge and associated pathogen pollutants through extensive filtration practices to meet
the intent of the TMDL.
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SECTION 3 Proposed Conditions
Project Description
The proposed Project includes the construction of the new Lazarus-Wurtele Center and the supporting site. The
proposed site improvements include the following:
1. Demolition of the existing building;
2. Construction of a new building;
3. Construction of new accessible and pedestrian walkways;
4. Installation of new utilities to support the proposed building; and
5. Construction of a new stormwater management system.
The Project is considered a redevelopment and is anticipated to decrease the overall impervious area for the Site
by 851 square feet (0.02 acres). There is approximately 860 square feet of permeable pavers and 1000 square
feet of green roof area provided in the proposed design. Refer to Table 1 for a comparison of the existing and
proposed land use for the Site.
Table 1. Proposed land use for the Site (in acres)
Land Use Existing Site
(acres)
Proposed Site
(acres) Change
Buildings 0.02 0.11 + 0.09
Green Roof 0.00 0.02 + 0.02
Site Pavement 0.32 0.22 - 0.10
Permeable Pavers 0.00 0.02 + 0.02
Landscaped Areas 0.61 0.58 - 0.03
Total 0.95 0.95 ---
Stormwater Management System
The Site will include the installation of a stormwater management system that is being designed to meet the
MassDEP Stormwater Management Standards and the City of Northampton Regulations. As a redevelopment,
the Project is required to meet the Stormwater Management Standards to the maximum extent practicable as
described in Section 5.
The Project has been designed using environmentally-sensitive site design and LID techniques. This design
prevents the generation of stormwater and non-point source pollution by reducing impervious surfaces with
porous pavers, disconnecting flow paths, treating stormwater at its source, and protecting natural processes.
Stormwater systems have been designed to model natural hydrologic features.
The proposed stormwater management system for the Project will include permeable pavers, proprietary
treatment structures, landscape filters, grassed swales, a green roof, and lined bioretention basins. All
stormwater generated by the Site makes its way southwest across the site either piped or overland. Overflow
from the proposed BMPs will be discharged to the existing drainage main in College Lane.
Permeable Pavers and Grass Pave
Three (3) permeable pavers systems totaling approximately 860 square feet, are proposed as part of this project.
Additionally, there are two (2) areas with Grass Pave surface, totaling approximately 480 square feet. These
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areas are pedestrian only, and therefore will not be subject to significant pollutant loadings. Due to the perched
groundwater table and the clay/silt layers, these systems are lined and will not provide infiltration and are
intended for water quality and rate reduction only.
The permeable pavers will replace traditional impervious walkway area and allow runoff to be treated within the
pavement section. Because of poor soils on the site and groundwater, these areas will be lined and will not be
infiltrating. The filter course and reservoir course were sized according to the University of New Hampshire
Design Specifications for Porous Asphalt Pavement and Infiltration Beds.
Bioretention Basins
Eleven (11) bioretention basins are proposed to treat stormwater runoff generated by the landscaped site and
site walkways. The bioretention basin includes a minimum 24-inch media filter to provide TSS and nutrient
pollutant removal. Due to the perched groundwater table and the clay/silt layers, these systems are lined and will
not provide infiltration and are intended for water quality and rate reduction only. These areas are pedestrian
only, and therefore will not be subject to significant pollutant loadings.
Water Quality Structures
Five (5) silt prison inlet structures are proposed on Chapin Way and College Lane in place of the existing catch
basin structures. The first inlet is located to the north of the 8 College Lane building. This catch basin was
adjacent to the limit of work, but in the existing condition it discharges to the sewer, so this area was ultimately
included in the limit of work in order remediate this condition and connect it to site drainage. Of the other four,
three are located adjacent to the raised table in College Lane at the southwest corner of the site, and the last is
in Chapin Way across from the Wesley House. These existing catch basin structures will be retrofitted with the
silt prison insert and will provide additional Total Phosphorus and TSS removal for the site.
Green Roof
1000 square feet of green roof is proposed on the building. Green roof provides peak rate attenuation by plant
uptake and evapotranspiration. The Green roof will consist of a minimum of a 4-inch-thick drainage layer that will
store collected rainfall for smaller storm events. The Green roof system will overflow to the building’s plumbing
system and then to the underground landscape filter section prior to discharging to the drain main that passes
through the project site.
Bioretention Landscape Filters (Biofiltration)
Bioretention landscape filters are proposed to treat stormwater runoff generated by the proposed surrounding
pedestrian and landscaped areas. The bioretention landscape filters include a minimum 24-inch media filter to
provide TSS and nutrient pollutant removal. Due to the perched groundwater table and the clay/silt layers, these
systems are lined and will not provide infiltration and are intended for water quality and rate reduction only.
Stormwater Management During Construction
The Site Contractor will be responsible for stormwater management of the active construction site and is required
to adhere to the conditions of the 2017 Construction General Permit under the Environmental Protection Agency
through the preparation and implementation of a Stormwater Pollution Prevention Plan (SWPPP). A draft
SWPPP has been prepared in accordance with the MassDEP Stormwater Management Standards and the 2017
Construction General Permit (Appendix F).
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SECTION 4 Stormwater Management Analysis
Methodology
Nitsch Engineering completed a hydrologic analysis of the existing project site utilizing Soil Conservation Service
(SCS) Runoff Curve Number (CN) methodology. The SCS method calculates the rate at which the runoff reaches
the design point considering several factors: the slope and flow lengths of the subcatchment area, the soil type of
the subcatchment area, and the type of surface cover in the subcatchment area. HydroCAD Version 10.00
computer modeling software was used in conjunction with the SCS method to determine the peak runoff rates
and runoff volumes for the 2-, 10-, 25-, and 100-year, 24-hour storm events. The proposed project site is being
analyzed with the same methodology.
The Site was divided into multiple drainage areas, or subcatchments, which drain to the design points along the
property boundary and within the site. For each subcatchment area, SCS Runoff Curve Numbers (CNs) were
selected by using the cover type and hydrologic soil group of each area. The peak runoff rates and runoff
volumes for the 2-, 10-, 25- and 100-year 24-hour storm events were then determined by inputting the drainage
areas, CNs, and time of concentration (Tc) paths into the HydroCAD model.
The National Oceanic and Atmospheric Administration Atlas 14 precipitation frequency estimates were used to
calculate the 2-, 10-, 25-, and 100- year 24-hour storm events in HydroCAD. Refer to the HydroCAD calculations
in Appendix B and C for rainfall information.
HydroCAD Version 10.10
The HydroCAD computer program uses SCS and TR-20 methods to model drainage systems. TR-20 (Technical
Release 20) was developed by the Soil Conservation Service to estimate runoff and peak discharges in small
watersheds. TR-20 is generally accepted by engineers and reviewing authorities as the standard method for
estimating runoff and peak discharges.
HydroCAD Version 10.10 uses up to four types of components to analyze the hydrology of a given site:
subcatchments, reaches, basins, and links. Subcatchments are areas of land that produce surface runoff. The
area, weighted CN, and Tc characterize each individual subcatchment area. Reaches are generally uniform
streams, channels, or pipes that convey water from one point to another. A basin is any impoundment that fills
with water from one or more sources and empties via an outlet structure. Links are used to introduce
hydrographs into a project from another source or to provide a junction for more than one hydrograph within a
project. The time span for the model was set for 0-72 hours in order to prevent truncation of the hydrograph.
Modeling of Permeable Pavers Section
The permeable paver systems were modeled according to methodology developed by the University of New
Hampshire Stormwater Center (UNHSC). Under ideal conditions, porous pavers with a suitable base will rapidly
infiltrate several inches of water, resulting in no runoff in the traditional sense. However, the HydroCAD model
needs to evaluate the “runoff” that is penetrating through the porous pavers. This requires the use of a high CN
(98) to capture most of the rainfall.
Once intercepted by the porous asphalt surface, the water will take some time to travel through the base layers
of the roadway, before ponding in the voids of the stone base. The UNHSC has studied this behavior and
developed an extended Tc value to simulate the travel time through the base. Their research determined that a Tc
of 790 minutes has produced good predictions of the final discharge from porous asphalt with a 41-inch base
(measured above the underdrains). It is believed that a proportional Tc can be used for a smaller base thickness,
as long as the layers remain proportional and are in accordance with the UNH specifications.
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Existing Hydrologic Conditions
As summarized in Section 2.1, Nitsch Engineering delineated the project site into on-site subcatchments
(watershed) areas discharging to one (1) design point utilizing an existing conditions survey and on-site
observations (See Figure DR-1). The design point (DP-1) is the existing closed drainage in College Lane. The
HydroCAD model for existing conditions is provided in Appendix B and results from the HydroCAD calculations
are summarized below in Table 3.
Proposed Hydrologic Conditions
The proposed project has been designed to mitigate the change in stormwater runoff at the design point as
required by the DEP Stormwater Management Standards and the City of Northampton Rules and Regulations.
The existing watershed areas were modified to reflect the proposed topography, storm drainage structures and
BMPs, and roof areas. (See Figure DR-2). The HydroCAD model for proposed conditions is provided in
Appendix C and results from the calculations are summarized in Table 2.
Peak Flow Rates
The proposed stormwater management system is expected to reduce the proposed peak runoff rates to at or
below the existing rates. Table 2 below summarizes the existing and proposed hydrologic analyses for the site.
Table 2. Peak Rates of Runoff in Cubic Feet per Second (cfs)
Storm Event 2-year 10-year 25-year 100-year
DP-1
Existing 2.01 3.79 4.91 6.62
Proposed 1.55 2.98 4.09 5.55
Northampton MA – Stormwater Report
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SECTION 5 City of Northampton Stormwater Regulations
The City of Northampton has additional design considerations required for stormwater as summarized below.
LID Design Strategies
The City’s Stormwater Management Rules and Regulations indicate that low impact design (LID) strategies must
be implemented unless infeasible in order to reduce the discharge of stormwater from development sites.
The project will include eleven (11) bioretention basins, green roof, landscape filters, and porous paver areas to
treat and mitigate peak runoff rates. Bioretention basins were located where site programing allowed for them
and were designed to be lined systems because there was not adequate separation from the bottom of the basin
and groundwater.
Annual Load Reduction of Phosphorus (50%) and TSS (80%)
The Northampton Stormwater Management Rules and Regulations require redevelopments to meet the minimum
requirements of the MS4 permit by including removal of 80% of the average annual load of Total Suspended
Solids and 50% of the average annual load of Total Phosphorus.
The proposed project is expected to reduce phosphorus loads in the post-construction condition by 66% and
TSS loads by 80% by using a combination of bioretention basins, permeable pavers, landscape filters, deep-
sump and hooded catch basins, and silt prison inlets. In addition, an Operations and Maintenance plan that calls
for catch basin cleaning, sweeping of the vehicular impervious surfaces on-site, and litter removal will allow for
additional phosphorus reductions.
Refer to Appendix H for the Phosphorus and TSS Removal Calculations.
Annual Load Reduction of Nitrogen
In addition to the Phosphorus and TSS removal requirements as outlined above, the City of Northampton
requires stormwater BMPs to be optimized for Nitrogen removal. The Massachusetts MS4 General Permit
Appendix F Attachment 3 provides Nitrogen Load reduction values for various BMPs. Each of the BMPs used for
phosphorus removal also provide Nitrogen Load reduction.
Refer to Appendix H for the Nitrogen Removal Calculations.
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SECTION 6 MassDEP Stormwater Management Standards
The Project is considered a redevelopment under the DEP Stormwater Management System. As such, the
project is required to meet Standards 2, 3, and the pretreatment and structural best management practice
requirements of Standards 4,5, and 6 only to the maximum extent practicable. Existing stormwater discharges
need to comply with Standard 1 only to the maximum extent practicable. The project will comply with all other
Standards. The site will be designed to meet or meet to the maximum extent practicable the MassDEP
Stormwater Management Standards as summarized below:
Standard 1: No New Untreated Discharges
The Project will not discharge any untreated stormwater directly to or cause erosion in wetlands or waters of the
Commonwealth. Stormwater from the Site will be collected and treated in accordance with the MassDEP
Stormwater Management Standards and stormwater outfalls will be stabilized to prevent erosion.
Standard 2: Peak Rate Attenuation
The proposed stormwater management system will be designed so that the post-development peak discharge
rates do not exceed pre-development peak discharge rates. To prevent storm damage and downstream
flooding, the proposed stormwater management practices will mitigate peak runoff rates for the 2-, 10-, 25- and
100-year, 24-hour storm events. Refer to Table 3 for a pre- and post- development peak runoff rate comparison.
Standard 3: Groundwater Recharge
The Site was designed using environmentally-sensitive site design, low impact development techniques, and
stormwater BMP treatment trains. Because of poor soils, there is no proposed infiltration on the site, however,
the design results in a net decrease in impervious area to the site, which promotes additional annual
groundwater recharge on the site in comparison to the existing condition.
The HydroCAD reports provided in Appendix C indicate that all proposed BMPs will drain within 72 hours for the
2-, 10-, 25-, and 100-year storm events, meeting the 72-hour MassDEP drawdown requirement. No infiltration is
proposed on site.
Standard 4: Water Quality Treatment
The proposed stormwater management system will be designed to remove greater than 80% of the average
annual post-construction load of Total Suspended Solids (TSS). Structural stormwater BMPs including a Silt
Prison, bioretention basins, and porous pavers, are sized to capture the required water quality volume (1 inch
over the project site) and remove a minimum of 80% of total suspended solids.
Table 3. Proposed Treatment Train Summary
Watershed Treatment Train
PR1-PR11 Bioretention Basin → Discharge
PR16 Silt Prison → Discharge
PR13, PR12 Permeable Pavers → Discharge
PR14 Permeable Pavers → Bioretention Basin → Discharge
PR15 Green Roof → Biofiltration (Landscape filter) → Discharge
Northampton MA – Stormwater Report
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The Permeable paver sections were designed in accordance with the University of New Hampshire Design
Specifications for Porous Asphalt Pavement and Infiltration Beds and include an 18-inch filter course of bank run
gravel to provide water quality treatment prior to flowing into the reservoir course.
TSS removal calculation spreadsheets are provided in Appendix H.
Source control and pollution prevention measures, such as vacuum cleaning, street sweeping, proper snow
management, and stabilization of eroded surfaces, are included in the Long-Term Pollution Prevention Plan and
Operation and Maintenance Plan (Appendix E).
Standard 5: Land Uses with Higher Potential Pollutant Loads
The Project is not considered a LUHPPL and therefore, this standard is not applicable.
Standard 6: Critical Areas
The Mill River/Paradise Pond is identified as a Cold-Water Fisheries Habitat by the Massachusetts Division of
Fisheries and Wildlife. BMPs complying with Standard 6 have been chosen to provide water quality, including
bioretention basins, permeable pavers with a filter course, biofiltration (landscape filter), and green roof.
Standard 7: Redevelopments
The Project is considered a redevelopment under the MassDEP Stormwater Management Standards. Therefore,
the project is required to meet Standard 2, Standard 3, and the pretreatment and structural stormwater BMP
requirements of Standards 4, 5, and 6 to the maximum extent practicable. The projects should comply with all
other requirements of the Stormwater Management Standards and improve existing conditions. The Project
meets this standard.
Standard 8: Construction Period Pollution Prevention and Sedimentation Control
A plan to control construction-related impacts, including erosion, sedimentation, and other pollutant sources
during construction and land disturbance activities (construction period erosion, sedimentation, and pollution
prevention plan) will be developed and implemented during the Notice of Intent permitting process.
Due to how close the project area is to one (1) acre, to be conservative, the Project will be submitting a Notice of
Intent to the Environmental Protection Agency (EPA) for coverage under the National Pollution Discharge
Elimination System (NPDES) Construction General Permit. As part of this application the Applicant is required to
prepare a Stormwater Pollution Prevention Plan (SWPPP) and implement the measures in the SWPPP. The
SWPPP, which is to be kept on site, includes erosion and sediment controls (stabilization practices and structural
practices), temporary and permanent stormwater management measures, Contractor inspection schedules and
reporting of all SWPPP features, materials management, waste disposal, off-site vehicle tracking, spill prevention
and response, sanitation, and non-stormwater discharges. A draft SWPPP is provided in Appendix F.
Standard 9: Operation and Maintenance Plan
A post-construction operation and maintenance plan has been prepared and will be implemented to ensure that
stormwater management systems function as designed. Source control and stormwater BMP operation
requirements for the site are summarized in the Long-Term Pollution Prevention Plan and Operation and
Maintenance Plan provided in Appendix E.
10
Standard 10: Prohibition of Illicit Discharges
There will be no illicit discharges to the stormwater management system associated with the Project. An Illicit
Discharge Compliance Statement is provided in Appendix A.
SECTION 7 Closed Drainage System Design
The proposed closed drainage system consists of area drains, deep sump and hooded catch basins, drainage
manholes connected with corrugated polyethylene pipe. The closed drainage system was designed to convey
the 25-year storm event using the Rational method, as required by the City of Northampton. Refer to Appendix D
for more information.
SECTION 8 Conclusion
In conclusion, the Project’s stormwater management system will reduce or maintain peak runoff rates through the
widespread use of filtration BMPs and improve the water quality of stormwater being discharged from the Site.
Environmentally sensitive site design and low impact development techniques will be implemented throughout
the Site. The Project is being designed to meet and exceed the MassDEP Stormwater Management Standards
and the City of Northampton Rules and Regulations.
Northampton MA – Stormwater Report
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FIGURES
DR-1 Existing Watershed Areas
DR-2 Proposed Watershed Areas
Figure 1 - USGS Aerial Map
Figure 2 - USGS Locus Map
Figure 3 - NHESP Map
Figure 4 - Wetlands Map
Figure 5 - FEMA Flood Map
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APPENDIX A
Stormwater Management Standards Documentation
MassDEP Checklist for Stormwater Report
Standard 10: Illicit Discharge Compliance Statement
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APPENDIX B
Existing Conditions – HydroCAD Calculations
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APPENDIX C
Proposed Conditions – HydroCAD Calculations
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APPENDIX D
Closed Drainage System Design
16
APPENDIX E
Long-Term Pollution Prevention and Stormwater Operation and Maintenance Plan
Northampton MA – Stormwater Report
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APPENDIX F
Draft Stormwater Pollution Prevention Plan (SWPPP)
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APPENDIX G
Soil Investigations
NRCS Soil Maps and Descriptions
Geotechnical Report
Soil Test Pit Logs
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APPENDIX H
Phosphorus, Nitrogen, and TSS Removal Calculations
Phosphorus, Nitrogen, and TSS Removal Calculation (MS4 Methodology)