20191211_Response to SW Comments.pdf
53 Southampton Road • Westfield, MA 01085-5308 • Tel 413.562.1600
www.tighebond.com
N-0936-016
December 11, 2019
Doug McDonald
Stormwater Manager
Department of Public Works
125 Locust Street
Northampton MA, 01060
Re: Fire Rescue Headquarters Parking Lot Improvement Project
Site Plan Review Application – Response to Stormwater Comments
Dear Doug:
On behalf of the City of Northampton Central Services Department (“the Applicant”), Tighe &
Bond has reviewed your comments on the November 12, 2019 submittal of the Fire Rescue
Headquarters Parking Lot Site Plans received via email on December 10, 2019. We have
prepared the following responses and clarifications to address the questions raised. The
comment is presented in italicized font followed by the response.
1. A Stormwater Management Permit is not required for projects that disturb less than 1
acre. As proposed, the project will disturb less than one acre and therefore does not
require a Stormwater Management Permit.
Acknowledged.
2. The project proposes to reconstruct the existing parking lot and results in a slight
increase in peak flows to the City's King Street stormwater system for the 1, 2- and
10-year storms. There are no stormwater measures proposed to mitigate peak flows
or water quality improvements for the stormwater flows to King Street. The DPW
requires some water quality improvement for redevelopment projects particularly for
increased flows from parking lots. The stormwater design must include a structural
BMP such as a proprietary treatment unit or oil grit separator to improve the water
quality for the flows discharged to the City's King Street stormwater system.
3. The on-site vehicle fueling station is considered a land use with higher potential
pollutant load (LUHPPL) and therefore additional measures must be implemented to
eliminate or reduce the discharge of stormwater runoff from such land uses. Depending
on the grading of the parking lot in the area of the fueling station, potential spills from
this area may flow to the proposed infiltration basin, to the existing stormwater system
to King Street or both. The project must include an additional structural BMP to address
the risk of spills from the fueling station. The BMP could be the same structure to
address the water quality issue described in #2 above if the fueling area is graded to
all flow toward the existing stormwater system to King Street.
The fueling area generally grades to the existing swale, but we have made minor
grading adjustments (inclusion of high points) to the west of the fueling area to ensure
that the runoff is directed to the existing swale. To provide a water quality upgrade
for the site, and address both spill and LUHPPL concerns, a treatment unit will be added
to the discharge line prior to its confluence with the drain line in North King Street.
- 2 -
4. The Stormwater Report specifies that all fill below the proposed infiltration basin will
be removed and replaced with clean fill with a higher infiltrative capacity. This
specification for removal of all fill under the infiltration basin and specification of the
replaced material must be added to the plans.
The plan was revised to include a note regarding the replacement of fill beneath the
proposed stormwater basin.
5. The proposed Long-Term Pollution Prevention and Stormwater Management System
Operation and Maintenance Plan names Northampton Public Works as the Maintenance
Contact. The Maintenance Contact should be changed to either the Northampton Fire
Department of Central Services Department as determined by the Applicant.
The Department of Central Services is willing to assume the responsibilities of
maintenance contact for the stormwater system on the Fire Station site. We
recommend the Board make it a condition of approval.
If you have additional questions or would like to discuss any of our responses, please contact
me at (413) 572-3279 or ZPChornyak@tighebond.com.
Very truly yours,
TIGHE & BOND, INC.
Alex Fagnand, PE, ENV SP
Project Engineer
Copy: David Pomerantz, City of Northampton
J:\N\N0936 Northampton DPW\16 - Fire Station Parking Lot and Solar\Permitting\SPR\Comment Response\20191211_Response to SW Comments.docx