Conservation Commission Meeting Agenda/Materials 109R and 131 Clark Lane Exhibit List (linked)

Carya Ecological Services, LLC
183 Guinevere Ridge
Cheshire, CT 06410
(203) 537-1869
sigrun.n.gadwa@gmail.com
February 9, 2023
Comservation Commission, Town of Waterford
Ms. Maureen FitzGerald, Environmental Planner
15 Rope Ferry Road
Waterford, CT 06385
RE: Application Review, App # C22-15 47-Unit Residential Subdivision w. affordable units
Response to Applicant’s rebuttals;housekeeping for the public hearing record
Carya Job No.: 23- WFD 3
This letter has been pasted from an e-mail to the town Conservation Commission, Mas Fitzgerald, and
also to my client and the applicant’s attorney & engineer. It was sent today at 3:06 PM . It has not been
altered except for minor proof-reading, including separating paragraphs. A high resolution photo of the
flow[path display board was attached.
C-22-14
Sincerely, 109R & 131 CLARK LANE
PUBLIC HEARING
S ; Ng -_ EXHIBIT # 44
Sigrun N. Gadwa, MS
Ecologist, Wetland Scientist, Registered Soil Scientist
Carya Ecological Services LLC
VIA E- MAIL
Sigrun Nicodemus <sigrun.n.gadwa@gmail.com> 3:06 PM (30 minutes ago)
to Maureen, Mark, David, arlene
Dear Ms. Fitzgerald and Conservation Commisioners:
This display board describes some flow path characteristics, between Detention Basin outfall & Fenger
Brook. There is clearly a reasonable likelihood of damage to Fenger Brook and to wetlands

Town of Waterford, Conservation Commission
RE: Clark Lane Proposed Subdivision
Feb. 9, 2023
Page 2
downgradient of the level spreader. However, more information is needed on soils and on topography
in the steep section, and on the downgradient plant community. In particular, the extent and duration of
saturation to the surface is needed to more accurately assess risk of channelization/erosion, which
would discharge suspended sediment into the brook. It is also needed to assess the risk/extent of harm
to trees and the overall plant community.
A jurisdictional wetland can provide considerable infiltration capacity - and stormwater attenuation -if
saturation is well below the surface for extended periods. Such “transitional” wetlands can support
a diverse array of facultative species of plants, quite different from the limited suite of plant species in a
very wet forested wetland, usually saturated to within an inch or two of the surface. But plant diversity
may not be very high in a post-ag wetland forest or thicket with transitional hydrology - largely because
many wetland species that could thrive there have not yet colonized, or because invasive species arrived
first and are preventing establishment of native species. Wetland soils with a low seasonal high-water
table (e.g. below ten or fifteen inches) do help prevent flooding and stream degradation by
disconnecting runoff sources from surface waters at least during smaller storm events like summer
thunderstorms. Mr. Theroux indicated that this is the predominant hydrologic regime, and that flood
storage is negligible because multiple rivulets connect to the brook.
In that case, likelihood of severe impacts to Fenger Brook, including channel degradation due to bank-
full or near bank-full conditions for longer periods. Banks - and level bare ground- are gradually
eroded if water flows past or over them for extended periods, even if velocities are low, especially if the
soil has a significant fine particle fraction (e.g. silt loam, fine sandy loam, loam, or very fine sandy
loam). The duration of contact with flow is the key factor here. The stormwater management system
does not meet the channel protection criteria in the CT 2004 Stormwater Manual. The detention basin
capacity and discharge is quite high, even for small interval storms. Stream bank erosion and widening:
Even infiltrated, redistributed runoff can result in a significant increase in groundwater discharge if the
discharge volume is great enough.
The applicant has also not provided groundwater recharge calculations. They should be done for the
northern half of the project because Clark Lane is the high point, the watershed Divide between the
Fenger Brook Basin(CT2000-30)and the Jordan Brook Drainage Basin (Basin 2201-03), which means
watershed size to the west of the Fenger Brook wetland system is not in fact very large, as Mr Theroux
believes, based on his rebuttal regarding our concerns that drought stress will increase in the upland
review area, and also in the wetland where the upland buffer is narrow (e.g. + - 50 feet).
We are pleased that pollutant loading calculations have been done but have not yet had an opportunity
to review them.
The concerns expressed will be part of my presentation, and each commissioner and the applicant will
receive an 11 X 8.5 copy of the display board. I send this letter in email form, primarily to be fair to the
applicant, who may wish to request an extension.
On behalf of my clients, we shall be recommending denial without prejudice. They are providing a list
of categories of additional information needed, either before a permit is granted, or to be provided as
permit conditions.

Town of Waterford, Conservation Commission
RE: Clark Lane Proposed Subdivision
Feb. 9, 2023
Page 3
Substantial additional field data is needed on buffer characteristics, both on the subject property and on
town-owned land. Field evidence and CTECO & USDA Soils data, to date, point to effective
infiltration of the existing Clark Lane discharge into the upland buffer along a ~ 250-foot flow path.
Dispersed flow begins downgradient of the deep ~ 60'-long, steep-sided ditch that has formed below the
outfall over the past few decades. The flow from the Clark Lane pipe spreads out in a tree cluster, to be
clear-cut, and evidence of channelized flow is absent in the downgradient riparian corridor of Fenger
Brook. But more soil depth data is needed to assess the likelihood of drought stress from significant
water diversion. (Impact is less for deep soils, with deep groundwater, than for shallow soils with hard
pan or ridge near the surface.) Nutrient data is needed from Fenger Brook, down-gradient of the flow
path from the lower Clark Lane discharge pipe, and from the upper end of the brook, below the Clark
Lane outfall from the pipe along the northern property line. Nutrient analysis is needed, not just the
"catch-all" specific conductivity parameter.
I shall also use two other display boards tonight. One is a blow up of 4 figures in the existing
conditions report. The second is a large watershed map clarifying the question as to whether the site is
in the Fenger Brook or Jordan Brook watershed (a collage of 9 printouts covering its 3.1 square mile,
3.47 miles long watershed (CT-2000-30) from the on-line CTECO map.) The board shows topography,
watershed boundaries, and all surface waters (including Alewife Cove). It shows the easterly flow
direction of the "connecting" unnamed stream that appears at first glance to link Fenger Brook to
Jordan Mill Pond. I shall leave the board with you tonight, for the record. I shall also give numbered
copies of the CT-ECO map print-outs to the applicant tonight.
Could I enter the full 16 page Fenger Brook Watershed Study into the Record without making copies
for the commissioners and the applicant? It is downloadable from the CTDEEP website. My clients
have already provided the commission with copies of an excerpt of this 2015 CTDEEP report on Fenger
Brook as Attachment A to the Carya Report dated 2-7-23.
Best Regards,
Sigrun. N. Gadwa, MS
Soil Scientist, Consulting Ecologist, Botanist
Carya Ecological Services, tc
183 Guinevere Ridge,
Cheshire, CT 06410
www.caryaecological.com
sigrun.n.gadwa@gmail.com
203 271 1949 (m) 203 537 1869
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