HomeMy WebLinkAboutConsultant Review - 1160 GREAT POND ROAD 7/21/2009 Eggleston Erivironmerital RECEIVED
JUL 212009
NORTH ANDOVER
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North Andover Planning Board
1600 Osgood Street
North Andover, MA 01845
Attn: Judy Tymon, Town Planner
RE: Stormwater Management Review
Brooks School— Soccer Field Renovation
Dear Ms. Tymon and Board Members:
I am writing this letter in follow-up to my June 24, 2009 review of the above-referenced
project. Since that time I have received and reviewed the July 14, 2009 response from
Huntress Associates, including plans revised through July 14, 2009 and a revised
drainage report dated July 10, 2009.
While the revised submission addresses some of the issues expressed in my June 24t"
letter, I do have several concerns regarding the revised plan. My comments are as
follows:
1. The soil tests indicate a high groundwater elevation of about 204.0 in the field
area. While the proposed fields have been raised since the previous submission,
several of the underdrains are below this elevation, and are likely to intercept
groundwater during certain periods of the year.
2. An outlet control structure has been added to the system design in order to detain
flows out of the underdrain system and promote infiltration. However, based on
the elevations shown on the plan (and modeled in the HydroCAD analysis), the
inlet pipe to the outlet control structure (inv. 205.0) is nearly two feet above the
outlet pipe from DM#8 (inv. 203.15), and the overflow weir (inv. 206.9) is
another nearly two feet above that. This would render the entire underdrain
system as "dead storage"with no viable means of draining between storms.
3. It is not clear what the 6-inches of dead storage referenced in the response letter
(Comment # 8) refers to. As indicated above, the current design provides nearly
four feet of dead storage, and the design details do not show 6-inches of stone
below the outlet pipe. I suggest that providing a stone base below the field
interceptor J-drains (provided there is adequate depth to groundwater) would be a
more suitable location for enhancing infiltration.
4. In my June 24'h letter I noted that the PVC drains along either end of the proposed
Boys Field #2 would not meet the minimum 0.5% slope specified based on the
5 5 0[d Coach Road Sudbury MA 01776 text 508.2 59,1137 fax 866.820,7840
Brooks School Field Reilovatioi7. Technical Revie',v 2
.l a IV 21. 2009
inverts shown. In the revised plans, none of the collector pipes meet this
minimum slope;they all now slope at 0.25%.
5. There is inadequate depth of cover over the outlet pipe from DM#1; a minimum
of two feet is recommended.
6. The rim elevations of DM#9 and the outlet control structure are a foot or more
above grade.
7. The drainage system for the existing fields, including the outfall, has not been
shown on the revised plans.
8. The test pit locations should be shown on the plans. A north arrow would also be
useful
Once again, I appreciate the opportunity to assist the North Andover Planning Board with
the review of this project, and hope that this information is suitable for your needs. Please
feel free to contact me if you or the applicants have any questions regarding the issues
addressed herein.
Sincerely,
EGGLESTON ENVIRONMENTAL
1
Lisa D. Eggleston, P.E.
C: Jennifer Hughes,North Andover Conservation Commission
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CONSERVATION DEPARTMENT North Andover Planning Board
Community Development Division Meeting Date:
Agenda
MEMORANDUM
DATE: August 19, 2009
TO: Judy Tymon, Town Planner
FROM: Jennifer Hughes, Conservation Administrator
SUBJECT: Brooks School - Conservation Commission Jurisdiction related to Athletic Field
I
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At the request of the Town of North Andover Planning Board,I have reviewed the plan titled
Watershed Special Permit Drawings for Soccer Field Renovations (Brooks School), dated June 5,2009
and revised July 24,2009 and conducted site investigations at the Brook School athletic fields. The
project as proposed is not jurisdictional to the North Andover Conservation Commission(NACC).
Wetland resource areas are greater than 100 feet from any proposed work on the site.
I
In addition,drainage work previously conducted on the fields also discharges more than 100 feet
from existing wetland resource areas. This work would not have required a filing with the NACC
under the Massachusetts Wetland Protection Act or Town of North Andover Wetland Bylaw.
1600 Osgood Street,North Andover,Massachusetts 01845
Phone 978.688.9530 Fax 978.688.9542 Web www.townofnorthandover.com
Eggleston Environmental
June 24, 2009
North Andover Planning Board
1600 Osgood Street
North Andover, MA 01845
Attn: Judy Tyman, Town Planner
RE: Stormwater Management Review
Brooks School—Soccer Field Renovation
Dear Ms. Tyman and Board Members:
Per your request, I have conducted an initial technical review of the June 5, 2009
Watershed Special Permit Application packet submitted by Huntress Associates for the
above- referenced project. The focus of my review was on stormwater management.
The proposed project includes the replacement of two existing natural grass soccer fields
with new synthetic turf fields, grandstands and viewing areas. The project is located
within the General Zone of the Watershed Protection District.
My comments on the application are outlined below:
1. In accordance with the Special Permit Requirements the plans should be stamped
by a registered Professional Engineer or Land Surveyor, and the application
should include a written certification by a registered Professional Engineer or
other qualified scientist stating that there will not be any degradation of the
quality or quantity of water in or entering Lake Cochichewick.
2. The drainage system for the existing fields, including the outfall, should be shown
on the plans.
3. Site-specific soil testing is needed to determine that there is adequate depth to
groundwater for the proposed underdrain system to function as designed.
4. Based on the inverts shown, the 12-inch PVC drains along either end of the
proposed Boys Field#2 will not meet the minimum 0.5% slope specified.
5. The flared end section should be designed in accordance with the current DEP
Stormwater Handbook,based on the projected maximum discharge velocity.
6. The pipe inverts used in the HydroCAD model are not consistent with the inverts
shown on the plan.
55 Otd Coach Road Sudbury MA 01776 tel 508.259.1137 fax 866.820.7840
Brooks School Field Renovation, Technical Re1,ieN.\! 2
.lone 24. 2009
7. It is not clear whether by using a curve number of 62 in the HydroCAD model the
applicant is intending to model surface runoff from the fields, or infiltration
through them. If it is presumed that all of the rainfall that falls on the proposed
artificial turf fields will be infiltrated, a curve number of 98 should be used to
generate the "runoff' flow that is routed through the perimeter drain system.
8. Infiltration through artificial turf fields is generally rapid and, as currently
designed, there is no dead storage provided in the underdrain system to attenuate
flows or enhance infiltration. I would therefore expect that the proposed design
will both shorten the time of concentration and increase the peak rate of discharge
from the system. The fact that this is not reflected in the HydroCAD analysis is a
function of the analysis, not the design.
9. The plan should identify the erosion and sediment control measures that will be
employed during construction to prevent sedimentation into Lake Cochichewick.
10. Finally, the Board should be aware that while artificial turf fields are increasingly
popular and do have the benefit of eliminating the need for irrigation, fertilizer
and herbicides, a number of other environmental concerns have been raised with
respect to their use. The most pertinent of these concerns to this application are
the potential for the leaching of zinc from the crumb rubber infill, the "heat
island" effect that can result in increased temperatures in the discharge, and the
potential need for periodic disinfection of the turf, the runoff from which would
be discharged through the underdrain system. You may want to have some
discussion with the applicant regarding the products proposed for use at this site
and potential mitigation measures.
I appreciate the opportunity to assist the North Andover Planning Board with the review
of this project, and hope that this information is suitable for your needs. Please feel free
to contact me if you or the applicants have any questions regarding the issues addressed
herein.
Sincerely,
EGGLESTON ENVIRONMENTAL
Lisa D. Eggleston, P.E.
C: Jennifer Hughes,North Andover Conservation Commission