230320 Response to DEP Comments.pdf
An Equal Opportunity Employer M/F/V/H
M E M O R A N D U M
To: Sarah LaValley, AICP, Northampton Conservation Commission
From: Nathaniel L. Russell, P.E., Stephen L Lecco (GZA)
Date: March 20, 2023
File No.: 15.0166793.00
Re: Response to DEP Comments
Wetland Notice of Intent Application
0 Dryads Green, Northampton MA
On behalf of the City of Northampton, GZA offers the following responses to the comments
provided by DEP in their letter dated February 7, 2023.
DEP Comment No. 1: The Commission needs to keep the hearing open until NHESP has
issued its determination.
Response: NHESP determination letter was received March 7, 2023.
DEP Comment No. 2: Please note the requirement for the location of the stormwater outfall
noted in 310 CMR 10.05(6)(k).
Response: 310 CMR 10.05(6)(k) provides performance standards related to stormwater
management, including Standards 1 through 10 as specified in the Massachusetts
Stormwater Standards. The proposed project was designed in accordance with the
applicable performance standards, as described below. Note, a general description of each
of the Standards is provided in italic text, followed by discussion of the project’s compliance.
For some of the Standards, only a portion of the text describing the standard is presented
for clarity. Refer to the full text in 310 CMR 10.05(6)(k) for additional information, as
appropriate.
Standard 1: No new stormwater conveyances may discharge untreated water directly to or
cause erosion in wetlands of waters of the Commonwealth.
The project involves repair to an existing stormwater outfall and will not result in a new
stormwater discharge. Further, the project will provide additional treatment of the existing
stormwater discharge (existing catch basins being replaced with new, deep sump catch basins
with hoods). Additionally, we note that the project involves repair of an existing stormwater
outfall and the permanent work associated with the project will be no closer to the resource
area than existing.
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Standard 2: Post-development peak discharge rates do not exceed pre-development peak discharge rates:
Peak discharge rates will remain unchanged by the project. The project involves repair of an existing
stormwater drainage outfall. There is no increase in impervious surface or other work proposed that
would be anticipated to change the peak discharge rates.
Standard 3: Loss of annual recharge to ground water shall be eliminated or minimized.
As a redevelopment project (refer to Standard 7, below), the Project is required to meet Standard 3
only to the maximum extent practicable. The project involves repair of an existing stormwater outfall
and is not anticipated to result in any change to the infiltration of ground water. Retrofitting the
existing municipal drainage system to provide infiltration of the water quality volume is not practical.
Further, infiltration of stormwater near the top of the steep slope supporting the drainage outfall is
not recommended as it could result in seepage gradients and would have the potential to negatively
impact slope stability.
Standard 4: Stormwater management systems shall be designed to remove 80% of the average annual post-
construction load of Total Suspended Solids (TSS).
As a redevelopment project (refer to Standard 7, below), the Project is required to meet Standard 4
only to the maximum extent practicable. The project will provide for enhanced stormwater treatment
though the replacement of multiple existing catch basins with new deep sump catch basins with
hoods. Providing additional stormwater treatment to achieve 80% TSS removal is not practical and
beyond the scope of the project.
Standard 5: Land Uses with Higher Pollutant Loads (LUHPPL).
Not applicable, the project is not a LUHPPL.
Standard 6: Stormwater discharges within a Zone II or Interim Wellhead Protection Area of a public water
supply or other critical areas.
Not applicable. The project is not within a Zone II or Interim Wellhead Protection area or other critical
areas as identified under 310 CMR 10.05(6)(k), 6. As noted above, the project involves repair to an
existing stormwater outfall. The location of the existing discharge is being maintained and is no closer
to the resource area than existing conditions. Further, as a redevelopment project (refer to Standard
7 below), the project would only be required to comply with Standard 6 to the maximum extent
practicable, including providing pre-treatment and structural best management practice
requirements of Standard 6.
Standard 7: A redevelopment project is required to meet the following Stormwater Management
Standards only to the maximum extent practicable: Standard 2, Standard 3, and the pretreatment and
structural stormwater best management practice requirements of Standards 4, 5 and 6. Existing stormwater
discharges shall comply with Standard 1 only to the maximum extent practicable. A redevelopment project
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shall also comply with all other requirements of the Stormwater Management Standards and improve existing
conditions.
The project is a redevelopment project as defined under the Massachusetts Stormwater Standards.
As designed, the project will improve existing conditions through provision of additional pre-
treatment of the existing stormwater discharge and repair of the existing outfall, which will reduce
erosion and discharge of sediment to the Mill River.
Standard 8: A plan to control construction related impacts including erosion, sedimentation and
other pollutant sources during construction and land disturbance activities (construction period erosion,
sedimentation and pollution prevention plan) shall be developed and implemented.
A plan showing proposed construction-phase erosion and sediment control measures was provided
as part of the Application. The contractor will be required to follow all applicable erosion and pollution
control regulations during performance of their work, including preparing a project-specific Spill
Prevention Control and Countermeasures Plan / Emergency Action Plan.
Standard 9: A long-term operation and maintenance plan shall be developed and implemented to ensure that
the stormwater management system functions as designed.
The project involves repair to an existing municipal utility (stormwater drain) and the infrastructure will
be maintained in accordance with the City of Northampton Stormwater Infrastructure Operation and
Maintenance Plan (O&M Plan), which includes requirements for the following:
• Inspection, cleaning, maintenance of municipal catch basins.
• Sweeping of municipal streets and parking lots.
• Winter road maintenance procedures to reduce the discharge of pollutants from the MS4.
• Inspection of maintenance of municipal stormwater BMPs.
• The City’s O&M Plan includes detailed SOPs for the maintenance of the stormwater system
components.
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