604597 NOI - Letter to ConCom regarding MassDEP.pdf TranSystems
101 Arch Street
Suite 301
Boston, MA 02110
Tel 857 453 5483
Fax 857 453 4576
www.transystems.com
[1]
March 28, 2018
Sarah LaValley
Conservation, Preservation, and Land Use Planner
Planning & Sustainability
210 Main St., Room 11
City Hall
Northampton, MA 01060
RE: Notification of Wetlands Protection Act File Number: WE 246-0713
Improvements on I-91 Interchange 19 at Route 9 and Damon Road
MassDOT # 604597
Northampton, MA
TranSystems Project Number: P701070053
Dear Conservation Commission members,
In response to the six “please note the following” from Mr. Mark Stinson, MassDEP:
(1) The increase in runoff to Design Point G is a direct correlation to an increase in
impervious are in post construction. In post construction, I-91on-ramp and I-91 off-
ramps have been increased in length and width, creating more impervious area. To
handle the increased flow in post construction, the existing 24” pipe is up sized to a 30”
pipe.
If requested, designer can add language to clarify on page 7 of the Stormwater Report.
(2) Designer interpreted the regulations for TSS removal as 25% TSS removal credit for
deep sump catch basins, and 25% TSS removal credit for a sediment forebay. Using deep
sump catch basins in combination with a sediment forebay the total pretreatment is 44%
TSS removal.
As an example, if the project proposed standard sump catch basins, which have a 0%
TSS removal credit, and then a sediment forebay, the total pretreatment would be 25%
TSS removal.
In both cases, the infiltration basin requires a sediment forebay, and the TSS removal
credit of 80% is applied to the infiltration basin. For each infiltration basin on this project
the TSS removal credit is a total of 85% TSS removal credit (deep sump catch basin and
infiltration basin) as opposed to 89% TSS removal credit (deep sump catch basin,
sediment forebay, and infiltration basin) For this project, both Infiltration Basin B and
Infiltration Basin J each provide 44% TSS removal as pretreatment.
[2]
Will include as an Attachment the TSS Removal Calculation Worksheet showing pretreatment
and the TSS Removal Calculation Worksheet showing total treatment for each infiltration basin.
(3) Test pit locations are shown on sheets 23 and 25. Test pits are shown within the area of
the proposed basins.
If requested, designer can provide the basin details sheets for added clarity in the NOI plans.
(4) On page 4 of the Stormwater Report, Attachment B, which shows the Hydrologic Soil
Group (HSG) characterizes the entire project site as HSG B soils. On page 8 (under
Standard 3 – Groundwater Recharge), the recharge target depth is calculated based on
HSG B soils. At the location of proposed recharge (Infiltration Basin B and Infiltration
Basin J), test pits were done at the location of the basins. The layer of the soil from the
test pits where re-charge is proposed (bottom of proposed basins) is used for
calculations as opposed to what the NRCS Soil Survey identified. The intent of the
NRCS Soil Survey for this project was to see if infiltration was feasible on this site
before deciding to propose infiltration.
Can add statement in section of report under Standard 3 – Groundwater Recharge clarifying
that the results of the test pits override the NRCS Soil Survey identified from Attachment B.
(5) MassDOT has been working with MassDEP in developing a new MassDOT Stormwater
Management Design Handbook. This new handbook builds upon the Massachusetts
Stormwater Handbook from February 2008. The design of deep sump catch basins
adheres to the 2016 MassDOT construction standards details. The design of the
sediment forebays and infiltration basins follows guidelines from the 2008 Massachusetts
Stormwater Handbook, but also includes design elements that will be included in the
MassDOT Stormwater Management Design Handbook (currently under review). All
proposed BMP’s will be constructed per MassDOT specifications/and or special
provisions and final contract drawings. The BMP’s will be operated and maintained per
the Operation and Maintenance Plan included in the Drainage Report. The BMP’s will
function to receive TSS removal credit.
Because a new MassDOT Stormwater Management Design Handbook is under development,
we are not planning on providing excerpts.
(6) We received a letter from NHESP dated March 1, 2018 stating its Determination. This
letter was forwarded to the conservation commission.
Sincerely,
Michael J. Rieger, PE
Civil Engineer
Encl: Notification of Wetlands Protection Act File Number dated March 19, 2018
[3]
Cc: Mark Stinson, MassDEP; Susan McArthur, MassDOT – Highway Division; Robert
Natario, MassDOT – Highway Division
DATE:March 19, 2018 Municipality NORTHAMPTON
(city/town)
RE: NOTIFICATION OF WETLANDS PROTECTION ACT FILE NUMBER
The Department of Environmental Protection has received a Notice of Intent filed in accordance with the
Wetlands Protection Act (M.G.L. c. 131, §40):
Applicant:
Address:
LOCUS:
MASSDOT
10 PARK PLAZA
INTERSTATE 91 INTERCHANGE AT RT. 9 AND DAMON ROAD
Owner:
Address:
This project has been assigned the following file # :WE 246-0713
Although a file # is being issued, please note the following:
Commissioner
MARTIN SUUBERG
Secretary
MATTHEW A. BEATON
Lieutenant Governor
KARYN E. POLITO
Governor
CHARLES D. BAKER
A FILE NUMBER ONLY INDICATES THAT THE APPLICATION CONTAINS THE MINIMAL
SUBMITTAL REQUIREMENTS AND IS ADMINISTRATIVELY COMPLETE - NOT THAT
THE INFORMATION IN THE APPLICATION IS ADEQUATE FOR ISSUANCE OF AN ORDER
OF CONDITIONS.
436 DWIGHT STREET, SPRINGFIELD, MA 01103 413-784-1100
WESTERN REGIONAL OFFICE
DEPARTMENT OF ENVIRONMENTAL PROTECTION
EXECUTIVE OFFICE OF ENERGY & ENVIRONMENTAL AFFAIRS
COMMONWEALTH OF MASSACHUSETTS
BOSTON, MA 02116
[1] Please explain the significant post construction runoff vs. pre, for Design Point G and why this is or is not an
issue.
[2] A CB provides 25%TSS and a sediment forebay provides 25%. An infiltration basin requires that total of 44%
TSS removal prior to the water entering the basin for HSG A or B soils. One only gets a total of 80% for an
infiltration basin. One does not add the pretreatment TSS removal to the 80%.
[3] Are the soils test pit locations shown on the plan and if so, were they taken in the area of the basins as
required?
[4] There should be a statement somewhere in the stormwater report, that the soils found onsite are, or are not, as
those reported in the NRCS soil survey especially regarding HSG information. Please review figure 2.3.1, page 8,
Determining HSG, from Volume 3, Chapter 1 of the Stormwater Handbook.
[5] All Stormwater BMP's must be designed, constructed, operated and maintained per the Stormwater Handbook
Volume 2 Chapter 2 in order to receive any presumptive TSS removal credit. It is recommended that the relevant
This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at 617-556-1057. TDD# 1-866-539-7622 or 1-617-574-6868.
http://www.mass.gov/dep
Printed on Recycled Paper
MASSDOT
10 PARK PLAZA
BOSTON, MA 02116
sections of the handbook pertaining to each individual BMP be cut and pasted into the Stormwater report, to assist
in Commission review of the stormwater management system.
[6] The Commission should wait to close the public hearing until NHESP has issued its Determination.
If you have any questions regarding this letter, please contact: MARK STINSON @ (413)-755-2257
Cc: Northampton Conservation Commission, CITY HALL, 210 MAIN STREEET RM 11, Northampton, MA, 01060
Natural Heritage & Endangered Species Program, Div of Fisheries & Wildlife Route 135, North Drive,
Westborough, MA, 01581
Representative: TranSystems, 101 Arch Street, BOSTON, MA, 02110
This information is available in alternate format. Call Donald M. Gomes, ADA Coordinator at 617-556-1057. TDD# 1-866-539-7622 or 1-617-574-6868.
http://www.mass.gov/dep
Printed on Recycled Paper