Conservation Commission - 128 (11/18/2021)

WATERFORD WOODS SITE MODIFICATION 
 
384 & 394 WILLETTS AVE. EXT. 
 
WATERFORD, CONNECTICUT 
1 
FEMA ZONE A BFE DETERMINATION SUMMARY 
OVERVIEW   
 
To better meets the needs of future residents of Waterford Woods, a site modification is being sought 
to provide a Clubhouse and recreational pool amenity.  The work is proposed on 394 Willetts Avenue 
Extension.  A portion of the subject site lies within a mapped FEMA Zone A of Fenger Brook.   
Zone A identifies an approximately studied special flood hazard area (SFHA) for which no base flood 
elevations (BFE) have been provided.  Determination of the 100-year BFE was required to ensure no 
adverse impact from the proposed site modification.  The following summary outlines the proposed 
project, regulated area, and methods used to determine the BFE in accordance with “Managing 
Floodplain Development in Approximate Zone A Areas, A Guide for Obtaining and Developing Base 
(100-Year Flood Elevations), July 1995” (FEMA 265).  
PROJECT OVERVIEW 
 
Approvals were granted in 2021 to Waterford Woods, LLC to construct a residential multi-family 
development on two (2) parcels of land located at 384 & 394 Willetts Avenue Ext. The development 
consists of the construction of three (3) apartment buildings with amenities including a dog park, grill 
and gathering area, and areas for passive and active recreation. 
To better meet the needs of future residents of Waterford Woods, a modification to the development 
is being sought to provide a Clubhouse and recreational pool amenity on 394 Willets Avenue Ext. 
Main access will be provided via extension of the approved driveway. The site modifications will 
include: 
• Clearing and grubbing. 
• Clubhouse to serve the future residents with indoor fitness, lounge, game, and office areas. 
• Exterior pool and lounge patio adjacent to the Clubhouse 
• Extension of the 24’ wide main access drive including a looped connection to improve 
vehicular circulation and emergency access at the rear of the development. 
• Outdoor recreation areas including a dog park and community spaces. 
• 8 new paved parking spaces in front of the Clubhouse, including 1 handicapped accessible. 
• Concrete pedestrian sidewalks connecting the Clubhouse building to the adjacent parking area. 
• Drainage improvements including a stormwater collection network, grass-lined treatment 
swales, and detention ponds; 
• Extension of private water, sewer, electric, gas and telecom mains; 
• Landscaping including a mixture of street trees, shrubs, foundation plantings and planting beds 
• Building and street lighting; 
• Erosion and sedimentation control measures. 
 
 

 
WATERFORD WOODS SITE MODIFICATION 
 
384 & 394 WILLETTS AVE. EXT. 
 
WATERFORD, CONNECTICUT 
2 
FEMA ZONE A MAPPING   
 
FEMA Zone A of Fenger Brook is mapped on a portion of 394 Willetts Avenue.  In general, the limits 
of the SFHA align with the wetlands and parallel existing contours.  However, a portion is 
perpendicular to existing contours and passes over an elevated peninsula at the southwest corner.  A 
snapshot of the FIRM is provided below.   
 
Review of the FIRM and other available data suggest the flood mapping on site may not accurately 
reflect currently flooding conditions.  Therefore, determination of BFE was needed to determine limits 
of the floodplain. 
BFE DETERMINATION 
 
METHODOLOGY 
In accordance with FEMA 265, the FEMA Library and the Town of Waterford were contacted to 
determine if technical or administrative data used in the original delineation was available.  The FEMA 
request determined that no data is available.  No response from the Town was received. 
Using Simplified Methods, a Contour Interpolation was considered.  Based on a review of watershed 
studies completed in the region, current topography, and field investigation, it was apparent that 
Fenger Brook and its watershed was bounded by the railroad, and Fenger Brook traveled west under 
a culvert in Miner Lane, and not south under the railroad.  Therefore, Detailed Methods would be 
needed to determine BFE of Fenger Brook at the subject site. 

 
WATERFORD WOODS SITE MODIFICATION 
 
384 & 394 WILLETTS AVE. EXT. 
 
WATERFORD, CONNECTICUT 
3 
HYDROLOGY 
The watershed contributing to the outlet at Miner Lane was determined to be 1.2 mi
2 as measured 
using current topography and available mapping.   
 
Peak flows for Fenger Brook were determined using StreamStats, which models regression equations 
developed by USGS, in cooperation with CTDOT.  The equations were updated recently, as presented 
in SIR 2020-5054, based on flood frequency estimates for stream gages in Connecticut and adjacent 
States using annual peak flow data through water year 2015.  The equations are applicable for basins 
in Connecticut with drainage areas between 0.69 to 325 mi that are not affected by flood control 

 
WATERFORD WOODS SITE MODIFICATION 
 
384 & 394 WILLETTS AVE. EXT. 
 
WATERFORD, CONNECTICUT 
4 
regulation or flow diversion.  The subject watershed falls within the method’s limitations. The 100-
year peak flow discharge was determined to be 228 CFS. 
HYDRAULICS 
The hydraulic analysis of Fenger Brook and flows to Miner Lane was performed using the Hydrologic 
Engineering Center’s River Analysis System (HEC-RAS) version 5.0.7 in accordance with the 
CTDEEP Hydraulic Guidance Document and FEMA 265.  Geometric data used in the analysis is a 
combination of current field survey and LiDAR topography.  The hydraulic model included sections 
downstream of Miner Lane and extended through the subject site to the north.  An overview of the 
hydraulic section alignment on the local digital elevation model is provided below. 
 
The 100-year water surface profile for the reach is as follows: 
 
0
1000
2000
3000
4000
10
12
14
16
18
20
22
24
26
28
30
HEC-RAS Model       Plan: Existing Conditions    7/27/2021 
Main Channel Distance (ft)
Elevation (ft)
Legend
WS  100 YR
Ground
1444
1883
2266
2500
2579
2655
2688
2767
3001
3407
3877
4280
4854
4999
Fenger Brook Modified

 
WATERFORD WOODS SITE MODIFICATION 
 
384 & 394 WILLETTS AVE. EXT. 
 
WATERFORD, CONNECTICUT 
5 
The analysis determined Fenger Brook in the vicinity of the site has a BFE of 20 at the northern limit 
of the site and 18 at the southern limit (NAVD88).  The original FEMA Zone A (teal fill) as compared 
to the limit of BFE inundation (yellow outline) is provided below.  
 
CONCLUSION 
 
As depicted above, Detailed Methods in accordance with FEMA 265 were used to determine a BFE.  
No work is proposed within the determined BFE and the project will not adversely impact the regulated 
floodplain.  The enclosed Site Plans depict work related to the determined BFE.