HomeMy WebLinkAbout2013-11-05 Planning Board Supplemental Materials (4) DEVELLIS ZREIN INC.
Land Planning. Civil Engineering
Landscape Architectrure
November 4, 2013
Judy Tymon, Town Planner
North Andover Planning Board
1600 Osgood Street
North Andover,MA 01.845
Re: Stormwater Review
School Department Building, 566 Main Street
Dear Ms. Tymon and Members of Board:
On behalf of our Client, Kang Associates, Inc., we are pleased to provide response comments to
the review letter prepared by Eggleston Environmental, dated October 30, 2013, regarding the
above referenced site.
The items listed in the review letter are re-typed below in plain text. Our responses to the
comments are typed in italics.
1. In accordance with the Site Plan Review requirements,the proposed plan will not
increase either the rate or volume of runoff from the site, and the piped connection to
the drain in Osgood Street will eliminate flow from the site onto the street surface
Agreed
2. Conveyance of the pavement runoff through the grassed swale will also provide some
degree of water quality treatment of the flow discharged from the project site. I do
recommend the addition of a deep sump catchbasin or other means of pretreating the
flow upgradient of the plunge pool, however, in order to minimize the deposition of
sediment within the swale and the ongoing maintenance required.
The plans are revised to include a deep sump catch basin at the lowest point of the parking. Flow
fi°om the catch basin is piped to the beginning of the grassed Swale with a flared end section,
having a riprap outlet. The originally proposed stone swale is therefore eliminated.
3. A means of access to the grassed swale for periodic removal of accumulated
sediments should be provided. It appears that this would best be accomplished from
Osgood Street.
The grassed Swale is proposed with relatively gentle side slopes (5:1) and can easily be accessed
from Osgood Street for maintenance.
4. As proposed,the bottom of the proposed swale/basin will be approximately two feet
below existing grade. Soil testing should be conducted to confirm that the cut will not
intercept groundwater.
Soil testing has been performed on the site and ground water was generally found to be
approximately 10'below existing grade. A copy of the test results are attached.
DeVellis Zrein Inc.
P.O.Box 307,Foxborough,MA 02035 508-473-4114
School Department Building
Responses to Review Letter
November 4,2013
Page 2
5. The depth of the existing sewer service line is not identified,but it should be
confirmed that it is below the proposed grading or will not otherwise interfere with
the construction of the swale.
The existing sewer line is proposed to be demolished and cut and capped.
6. Designated snow storage locations should be shown on the plan.
The plans are revised to show proposed snow storage areas
7. Consideration should be given to using a cistern to capture roof runoff for irrigation
on the site.
A cistern system will be discussed with the client, but given the budget constraints, it may be
difficult to include it.
8. The Planning Board may want to request cut and fill calculations to assess traffic
impacts during construction.
Given the site topography, the proposed site grading attempts to utilize site cuts and fills to the
extend possible. Additional fill materials may be required to be brought to the site.
9. Other than the proposed haybale line,the plans do not address erosion and sediment
control measures to be employed on the site. I do note that the total area of
disturbance associated with the project will exceed one acre, however,therefore
coverage under EPA's Construction General Permit will be required and the selected
contractor will need to prepare a Stormwater Pollution Prevention Plan outlining
more detailed sediment control measures in accordance with the EPA Permit. The
Planning Board should be provided the opportunity to review the Construction
SWPPP before it is finalized.
Agreed
If you have any questions or need additional information please contact us at 508-473-4114.
Sincerely,
DEVELt REIN INC.
Imad A Zrein, P.E.
cc: Kaffee Kang
Lisa Eggleston