HomeMy WebLinkAbout25IWC7-Silver Falls Rd - Narrative & Wetlands Report
April 7, 2025
Town of Montville
Inland Wetlands Commission Attn: Douglas K. Brush, Chair Montville Town Hall 310 Norwich-New London Tpke
Uncasville, CT 06382
Re: Town of Montville Lot 00A Silver Falls Rd
Montville, CT
CLA #7885 Dear Mr. Brush:
On behalf of the applicant, CLA Engineers has performed a delineation and functional evaluation of
the inland wetlands at the referenced site and assessed the site to provide a basis for determining the potential for impacts. The inland wetland boundary was delineated by Robert Russo CSS between June and November 2024. The wetland boundary and proposed development are shown on the plans prepared by CLA Engineers dated December 5, 2024. These data were augmented with additional
online information from CTDEEP, USFWS, USGS, and the Town of Montville.
Site Setting The site is a 19.5-acre parcel located on the eastern side of Silver Falls Rd south of 27 Silver Falls Rd. The parcel abuts the Town of Waterford and is currently undeveloped. The majority of the
parcel is forested and there are six (6) unique wetland areas on the property, five of which appear
to have some degree of groundwater or surface connectivity. Only one on-site wetland area (defined on plans as Wetland 101) will be disturbed by the proposed development. Therefore, this wetland impact letter and associated function and value analysis focuses only on Wetland 101. The entire project area is within the Latimer Brook subregional drainage basin (2202).
The surrounding neighborhood is zoned residential (R-60) per most recent update of the Town of Montville Zoning Map and consists of low- to medium-density single family residential lots, many of which are developed.
Soils
The upland and wetland soils mapped on the property by NRCS (USGS) are listed in the table below. Additional descriptive details are provided in Appendix A.
CLA Engineers, Inc.
Civil Structural Survey
317 MAIN STREET NORWICH, CT 06360 (860) 886-1966 (860) 886-9165 FAX
Table 1 - Soil Types and Properties at the Silver Falls Rd Site
Soil Series Parent Material Drainage Class Texture/Characteristics
Ridgebury, Leicester, and Whitman (3)*
Coarse-loamy lodgment till Poorly drained to very poorly drained Sandy loam
Paxton and Montauk (85) Coarse-loamy lodgment till Well drained Fine sandy loam
Raypol (12)* Coarse-loamy
eolian deposits
Poorly drained Silt loam
Woodbridge (46-47) Coarse-loamy lodgment till Moderately well drained Fine sandy loam
Haven (703) Coarse-loamy eolian deposits Well drained Silt loam
*Hydric (wetland) soil type
One wetland soil unit mapped on this site consists of Ridgebury, Leicester, and Whitman soils. The Ridgebury series consists of very deep, somewhat poorly and poorly drained soils formed in lodgment till derived mainly from granite, gneiss and/or schist. They are commonly shallow to a densic contact. They are nearly level to gently sloping soils in depressions in uplands. They also
occur in drainageways in uplands, in toeslope positions of hills, drumlins, and ground moraines, and in till plains. The Leicester series consists of very deep, poorly drained soils formed in coarse-loamy till. They are nearly level or gently sloping soils in drainageways and low-lying positions on hills. The Whitman series consists of very deep, very poorly drained soils formed in lodgment till derived mainly from granite, gneiss, and schist. They are shallow to a densic contact.
Another wetland soil unit mapped on this site is comprised of Raypol silt loam. The Raypol series consists of very deep, poorly drained soils formed in loamy over sandy and gravelly outwash. They are nearly level to gently sloping soils in shallow drainageways and low-lying positions on terraces and plains.
The upland soil units on this site are Paxton and Montauk fine sandy loams, Woodbridge fine sandy loam, and Haven silt loam. The Paxton series consists of well drained loamy soils formed in lodgment till. The soils are very deep to bedrock and moderately deep to a densic contact. They are nearly level to steep soils on hills, drumlins, till plains, and ground moraines. The Montauk
series consists of well drained soils formed in lodgment or flow till derived primarily from granitic materials with lesser amounts of gneiss and schist. The soils are very deep to bedrock and moderately deep to a densic contact. These soils are on upland hills and moraines. The Woodbridge series consists of moderately well drained loamy soils formed in lodgment till. They are very deep to bedrock and moderately deep to a densic contact. They are nearly level to moderately steep soils
on hills, drumlins, till plains, and ground moraines. The Haven series consists of very deep, well drained soils formed in loamy over sandy and gravelly outwash. They are nearly level through
moderately sloping soils on outwash plains, valley trains, terraces, and water-sorted moraine deposits.
Wetland Characteristics Classification While the National Wetlands Inventory (NWI https ://fwsprimary.wim.usgs.gov/ wetlands/apps/wetlands-mapper/) does not identify the wetland, CLA determined the onsite
wetland to be a 43,300 square foot palustrine forested wetland (PFO1E) and palustrine emergent
wetland (PEM1E) based on field investigation and GIS site review. The description of that classification is provided below. Classification code: PFO1E
System Palustrine (P): The Palustrine System includes all nontidal wetlands dominated by trees,
shrubs, persistent emergents, emergent mosses or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5 ppt. It also includes wetlands lacking such vegetation, but with all of the following four characteristics: (1) area less than 8 ha (20 acres); (2) active wave-formed or bedrock shoreline features lacking; (3) water depth in the deepest part
of basin less than 2.5 m (8.2 ft) at low water; and (4) salinity due to ocean-derived salts less than
0.5 ppt. Class Forested (FO): Characterized by woody vegetation that is 6 m tall or taller. Subclass Persistent (1): Dominated by species that normally remain standing at least until the beginning of the next growing season. This subclass is found only in the Estuarine and Palustrine
systems.
Water Regime Seasonally Flooded/Saturated (E): Surface water is present for extended periods (generally for more than a month) during the growing season, but is absent by the end of the season in most years. When surface water is absent, the substrate typically remains saturated at or near the surface.
Classification code: PEM1E System Palustrine (P): The Palustrine System includes all nontidal wetlands dominated by trees, shrubs, persistent emergents, emergent mosses or lichens, and all such wetlands that occur in tidal areas where salinity due to ocean-derived salts is below 0.5 ppt. It also includes wetlands lacking
such vegetation, but with all of the following four characteristics: (1) area less than 8 ha (20 acres);
(2) active wave-formed or bedrock shoreline features lacking; (3) water depth in the deepest part of basin less than 2.5 m (8.2 ft) at low water; and (4) salinity due to ocean-derived salts less than 0.5 ppt. Class Emergent (EM): Characterized by erect, rooted, herbaceous hydrophytes, excluding mosses
and lichens. This vegetation is present for most of the growing season in most years. These
wetlands are usually dominated by perennial plants. Subclass Persistent (1): Dominated by species that normally remain standing at least until the beginning of the next growing season. This subclass is found only in the Estuarine and Palustrine systems.
Water Regime Seasonally Flooded/Saturated (E): Surface water is present for extended periods
(generally for more than a month) during the growing season, but is absent by the end of the season in most years. When surface water is absent, the substrate typically remains saturated at or near the surface.
Wetland hydrology
The onsite wetland consists largely of a palustrine forested wetland area with likely groundwater
connectivity to other wetlands and water bodies, most notably Silver Falls Pond across the street. Since the proposed development is not within 100 feet of any wetland besides Wetland 101, the below functional assessment focuses only on Wetland 101. The wetland is densely vegetated and appears healthy with high organic matter content in the soil. Various strata of vegetation exist
within and around the wetland (trees, shrubs, emergent, mosses, etc.), evidencing relatively high
plant biodiversity in the wetland. The wetland sits high in the drainage basin and appears to have groundwater connectivity to the other wetlands on site as well as Latimer Brook, a tributary to the Niantic River. The wetland is saturated but does not contain sufficient ponded water to support finfish or shellfish habitat. Additionally, a FEMA-designated floodplain contains much of Wetland
101 and the surrounding upland. The FEMA flood map for this site is included in Appendix B.
Factors important to functional assessment The following observations are important to the functional assessment and are listed here to provide context to the later discussion of functions and values.
1. Connecticut protected species are known to be present on the site per the June 2024 update of the CTDEEP NDDB. 2. The wetland has two dominant classes (PFO1E and PEM1E). 3. The local zoning is residential (R-60) per the Town GIS, and the surrounding parcels
appear to be used for single-family residences.
4. The wetland has melt-out till soils along its edge and lodgement till soils within per available online mapping. Detailed soil mapping from the U.S. Web Soil Survey are included within Appendix A. 5. The wetland is a part of a larger watercourse system (Niantic River system).
6. The wetland appears to be healthy and densely vegetated, and most of its edges are
surrounded by at least 100 feet of undeveloped buffer area. Principal functions The functional assessment was conducted using the USCAE Highway Methodology
(https://www.nae.usace.army.mil/Portals/74/docs/regulatory/Forms/HighwaySupplement6Apr20
15.pdf). The assessment is included as Appendix C and it revealed that the wetland has the following principal functions: 1. Groundwater recharge and discharge: this wetland has a variable water level and lacks
a permanent outlet, indicating that it feeds the groundwater system.
2. Nutrient removal: the wetland is rich in organic material, which is highly capable of removing excess nutrients from agricultural operations and roads upland and upstream of the wetland. 3. Wildlife habitat: overland access from the wetland is possible to six (6) unique classes of
wetland as well as upland areas.
4. Endangered species habitat: The Connecticut Natural Diversity Data Base (CTNDDB) has identified the wetland area as an area of concern for endangered species.
Proposed Development
As shown on the project plans, the following activities are planned in the wetland for a total of
approximately 4,590 square feet of disturbance: 1. Construction and grading of a common driveway across the property from Silver Falls Rd to the four unique housing lots in the subdivision. Contractors will utilize typical
excavators, loaders, rollers, and dump trucks for the construction of the driveway.
2. Construction of a 15” culvert beneath the driveway to promote connectivity in the wetland on both sides of the driveway. 3. Construction of a 70’ by 45’ stormwater quality basin within the upland review area (outside of the wetland) to manage runoff from the driveway area.
4. Implementation of erosion and sedimentation control measures in and around the project
area including silt fence, grassed swale, anti-tracking pad, and hay bale barrier. Table: total wetland impacts from the proposed driveway construction Area in square U.S. feet Area in acres
Permanent area impacted 4590 +/- 0.10 +/-
Temporary area impacted 0 0
Potential for Impacts
The proposed activities outlined above may impact the wetland’s principal functions in the following ways: 1. Groundwater recharge and discharge: because the stormwater basin is sized to accommodate for the changes in drainage due to the driveway, CLA does not anticipate
any changes to the wetland’s ability to perform this function. 2. Nutrient removal: the proposed driveway could increase the overall nutrient load into the wetland. However, if proper erosion and sedimentation controls are implemented during and after construction as indicated on plans, CLA does not predict significant impacts to this functionality.
3. Wildlife habitat: because the area of the driveway is small relative to the wetland and quite narrow, we do not expect this project to impact wildlife habitat via fragmentation or other means. For instance, bats can easily travel across roadways with low or moderate traffic flow where the distance from one tree canopy to the other is less than 20 meters1. Because the proposed project is a private driveway only 14 feet in width, we do not expect to
see any habitat fragmentation or collision risk for bat species.
4. Endangered species habitat: see “Wildlife Habitat” above. Narrative Describing the Activities to Take place on the property.
This section is responsive to the Town of Montville Inland Wetlands Checklist, page 2 Item 3, Narrative.
Alternatives considered
This site is a developable parcel of land that has wetland along the entire road frontage as shown on the project plans. As such, the access driveway was located so as to minimize the total area of wetland disturbance by crossing the wetlands at the narrowest point. Description of the activity including location and square footage of disturbance. The overall all project consists of a 4-lot residential subdivision to be accessed from Sliver Spring Rd in Montville. The proposed development includes on site driveways, septic systems, wells, rain gardens and a stormwater treatment basin. The regulated activity includes construction of a residential driveway and a stormwater management basin within the upland review zone. More specifically, there will be a loss of
approximately 4590 square feet of forested wetland in two separate locations within the first 400 feet of the intersection with Silver Falls Rd. The construction will include a15 inch diameter culvert at the first crossing location in order to provide connectivity to the upslope wetland and to protect the driveway.
This work will be done in only after meeting with town staff and installation of the proper erosion and sediment control measures. The work will be performed with excavators, bulldozers and dump trucks.
What type of erosion and sediment control will be used? As shown on the site plan, the following best management practices will be employed: 1. An anti-tracking pad at the construction entrance. 2. A rip rap swale along the edge of the driveway 3. Silt fence along the limits of disturbance 4. De-watering, if needed, as shown on the dewatering detail on the site plans. If machinery will be used or if work will be done by hand.
Machinery will be used and it will include typical heavy construction machines such as excavators, bulldozers, and dump trucks.
Identify the sub-drainage basin where the proposed activity will occur.
The sub-drainage basin is number 2202.
Summary CLA has designed the wetland crossing to occur at the narrowest available location thus providing for minimal loss of wetland habitat and function. If proper erosion and sedimentation controls are
installed according to the site plans, we do not anticipate the proposed development will have any
significant impact on the four principal functions of the onsite forested wetland.
Sincerely,
Robert C. Russo
Soil and Wetland Scientist
CLA Engineers, Norwich, CT
Soil Map—State of Connecticut, Eastern Part
(7885 Silver Falls Subdivision)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/2/2024
Page 1 of 3458810045882004588300458840045885004588600458810045882004588300458840045885004588600732400732500732600732700732800732900733000733100733200733300
732400 732500 732600 732700 732800 732900 733000 733100 733200 733300
41° 24' 57'' N 72° 13' 10'' W41° 24' 57'' N72° 12' 27'' W41° 24' 36'' N
72° 13' 10'' W41° 24' 36'' N
72° 12' 27'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 18N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,630 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:12,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: State of Connecticut, Eastern Part
Survey Area Data: Version 2, Aug 30, 2024
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jun 14, 2022—Oct 6,
2022
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Soil Map—State of Connecticut, Eastern Part
(7885 Silver Falls Subdivision)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/2/2024
Page 2 of 3
Map Unit Legend
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
3 Ridgebury, Leicester, and
Whitman soils, 0 to 8
percent slopes, extremely
stony
4.6 12.4%
12 Raypol silt loam, 0 to 3 percent
slopes
2.3 6.1%
29B Agawam fine sandy loam, 3 to
8 percent slopes
0.8 2.2%
38C Hinckley loamy sand, 3 to 15
percent slopes
0.1 0.3%
46B Woodbridge fine sandy loam, 0
to 8 percent slopes, very
stony
6.1 16.5%
47C Woodbridge fine sandy loam, 3
to 15 percent slopes,
extremely stony
3.8 10.4%
75E Hollis-Chatfield-Rock outcrop
complex, 15 to 45 percent
slopes
0.1 0.2%
85B Paxton and Montauk fine
sandy loams, 3 to 8 percent
slopes, very stony
7.1 19.2%
85C Paxton and Montauk fine
sandy loams, 8 to 15 percent
slopes, very stony
7.3 19.8%
703B Haven silt loam, 3 to 8 percent
slopes
3.2 8.8%
W Water 1.5 4.1%
Totals for Area of Interest 36.9 100.0%
Soil Map—State of Connecticut, Eastern Part 7885 Silver Falls Subdivision
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/2/2024
Page 3 of 3
National Flood Hazard Layer FIRMette
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Feet
Ü
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOODHAZARD AREAS
Without Base Flood Elevation (BFE)Zone A, V, A99With BFE or Depth Zone AE, AO, AH, VE, AR
Regulatory Floodway
0.2% Annual Chance Flood Hazard, Areasof 1% annual chance flood with averagedepth less than one foot or with drainageareas of less than one square mile Zone X
Future Conditions 1% Annual
Chance Flood Hazard Zone X
Area with Reduced Flood Risk due to
Levee. See Notes.Zone X
Area with Flood Risk due to LeveeZone D
NO SCREEN Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood Hazard Zone D
Channel, Culvert, or Storm Sewer
Levee, Dike, or Floodwall
Cross Sections with 1% Annual Chance
17.5 Water Surface Elevation
Coastal Transect
Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of Study
Jurisdiction Boundary
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No Digital Data Available
Unmapped
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digital flood maps if it is not void as described below.The basemap shown complies with FEMA's basemapaccuracy standards
The flood hazard information is derived directly from theauthoritative NFHL web services provided by FEMA. This mapwas exported on 11/19/2024 at 4:51 PM and does notreflect changes or amendments subsequent to this date andtime. The NFHL and effective information may change orbecome superseded by new data over time.
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Legend
OTHER AREAS OF
FLOOD HAZARD
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MAP PANELS
8
B 20.2
The pin displayed on the map is an approximatepoint selected by the user and does not representan authoritative property location.
1:6,000
72°13'20"W 41°25'7"N
72°12'42"W 41°24'40"N
Basemap Imagery Source: USGS National Map 2023