Conservation Commission Agenda (linked)

JAN 09 2028 |
Planning & Developmen
Town of Waterford, CT
FIFTERN ROPE FERRY ROAD WATERFORD, CT 06385-2886
PLANNING & DEVELOPMENT
Date: October 4, 2023
To: Wayne S. Garrick, AIA
From: Maureen FitzGerald, Environmental Planner 7
Re: Inland Wetland Application #23-08: 33 Kenyon Road
Proposed Construction of New Building, parking, stormwater swale and utilities
Application Review Comments:
The following review comments address the application materials received by the Conservation
Commission on September 28, 2023.
1) Staff has requested the wetland boundary be reviewed by the wetland scientist and re-marked in the
field as the boundary flags are no longer apparent. col PULTE, a AS pec |MB
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2) The proposed construction impacts 450 sq. ft of inland wetland area. The application should provide
a discussion of alternatives considered to avoid or reduce wetland impact and any measures
considered to mitigate for unavoidable wetland impacts. The Conservation Commission will need to
evaluate the impacts to determine if th¢ proppsal involves a significant wetJand impactactiyity
Section 2.32 of the regulation i Plt Hl ial f iS
3) To minimize direct discharge of stormwater to the seasonally 6& LL fand area east of the swale, ‘
the opportunity to direct the swale discharge to the upland vegetated areas north and south of the on-
"e wetland to ~ B “dper F Dik ni be evaluated.
4) The stormwater treatment system 1s proposed as an infiltration swale. Infiltration testing of in-situ
soils has not been conducted to verify infiltration rates will meet CT DEEP Stormwater Manual
(2004) criteria. The soil is classified as hydrologic group C, which has a minimum infiltration rate
below the DEEP recommended 0.3 inch/hr. Saturated soil conditions were evident in the area of the
proposed swale location in October 2023. The DEEP design criteria recommend infiltration areas be
a minimum of 3 ft. above seasonal high groundwater, as documented by on-site soil testing.
It is recommended this field testing be conducted during this design phase to verify stormwater
infiltration can be utilized at this location, An alternate wet-bottom swale or basin design may be.
better suited to conditions. REV |669. [oe < APPL ABLE 4
5) Inclusion of biofiltration media into the swale construction is suggested to increase sediment and
nutrient removal efficiency. Soil media recommendations from UNH Stormwater Center}publicatio
ey ae TELE thicker soil media depth and reduced compost component. pA loess
6) The swale cumulative volume as presented in drainage calculations is less than the calculated water
quality volume. The water quality volume from the post-construction condition should be, re,
and treated prior to discharge to wetlands. EY. 4 é,
RE SEP. i
7) The application should address the anticipated percent pollutant removal for the proposed stormwater
treatment swale. Gt pec Ww Aa G .

8) The ESC plan for project construction needs to include proposed stockpile locations and indicate the
propos Ces eer for ne water swale during construction, eE~ jade,
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9) A Site Stormwater Management manual is required per Section 25.6 of the zoning regulations. The
O&M portion of this manual should include timing, frequency of inspection and maintenance tasks
for the stormwater treatment system and LID components, Drainage calculations should demonstrate
the design attenuateg the 10-yr, 25-yr and 100-yr storm frequency to predevelopmentdisgharge, rates,
10) The final plan requires the signature of the wetland /soil scientist responsible for the wetland
boundary delineation. LEE & ; Se
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Ce: Michael J. Ott, P.E. 
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James Sipperly, Wetland Scientist | Al . q-
- 3) The stormwater wetland is designed to temporarily store and then infiltrate t i
> ol portion of rainfall events. That volume is presumed to be treated, Only stormweter runot ean the portion
of rainfall events greater than the water quality volume will be directed to the inland wetland to the east.
The southern third of the stormwater wetland berm length directs stormwater runoff to the immediately _
adjacent intand wetland and the remaining northern portion directs stormwater runoff over relativel rat
heavily vegetated ground surface cover areas before entering the inland wetland, mm