2023-08-25 Response to DEP Comments - 196 Cooke Ave.pdf
4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com
Berkshire
Design
Group
August 25, 2023
Northampton Conservation Commission
Northampton, MA
RE: Response to MassDEP Comments on Notice of Intent
196 Cooke Ave – MassDEP File Number WE 246-0774
Dear Commissioners:
Berkshire Design Group is the engineer of record for the proposed improvements at 196 Cooke Avenue and
prepared design plans for the project that were part of a Notice of Intent submitted by the City of Northampton.
We are in receipt of comments from MassDEP on the Notice of Intent, and are providing the following responses
as the Commission considers this application:
1. MassDEP: Per 310 CMR 10.05(6)(l), there is no regulatory requirement for a stormwater management
system.
We acknowledge that a stormwater management system is not required; however, in the context of
this project, which is partly parking and access for public conservation land, one of the design goals of
the project was to provide an improvement to the existing condition, which includes reducing runoff
and improving water quality.
2. However, since a stormwater management system is being created, it must comply with the standards.
Per 310 CMR 10.53(1), the commission may require a redesign of the parking lot area to move those
areas and the stormwater management system further away from the wetlands such that possibly no
BMP’s are required and that sheet flow alone with a well vegetated buffer zone may be adequate based
on the site having HSG B soils. The commission may require that pre and post development calculations
be run for sheet flow runoff only. As a reminder, roof runoff does not typically require treatment. Both
forebays and infiltration basins require ongoing maintenance which often does not get done as required.
We note that sheet flow over vegetated areas is likely to provide insufficient treatment from flows off
of larger paved areas. While we acknowledge that stormwater management is not required, we
believe that some improvement on existing conditions (even if not fully compliant with standards) is
better than no stormwater management at all.
We have reviewed the site plan and coordinated with Northampton DPW. We have modified the
outlets for the proposed stormwater basin designed to capture pavement runoff from the residential
site and can now qualify it as a water quality swale instead of a sediment forebay, providing a greater
level of water quality treatment. The proposed conservation parking lot has been re-graded to direct
runoff to the existing catch basin at the driveway entrance, which will be converted to a stormwater
treatment chamber (Contech CDS or equal).
The proposed treatment chamber will be owned and maintained by the City. The infiltration basin and
water quality swale are designed to require simple maintenance that is achievable by the
homeowners in the future residential development.
August 25, 2023
Response to MassDEP Comments on Notice of Intent
196 Cooke Ave – MassDEP File Number WE 246-0774
Page 2 of 2
4 Allen Place, Northampton, MA 01060 (413) 582-7000 bdg@berkshiredesign.com
While the project may comply with wetland protection regulations if the proposed stormwater
management system were eliminated, it is our opinion that the proposed design is a significant
improvement over that alternative design.
Sincerely,
Berkshire Design Group
Chris Chamberland
Principal Civil Engineer