Conservation Commission - 158 (01/28/2021)

WATERFORD WOODS MULTI-FAMILY DEVELOPMENT 
 
WATERFORD, CONNECTICUT 
 
ENGINEERING RESPONSE 1 
COMMENT RESPONSE SUMMARY 
FROM: 
Maureen FitzGerald, Environmental Planner 
DATE: 
December 9, 2020 
RE: 
Waterford Woods, Conservation Commission Site Plan Review 
1. A portion of the cleared area within the upland review area is to be revegetated with 
conservation seed mixture to provide vegetated buffer area between the maintained surface 
areas and the wetland boundaries. The restored buffer width ranges between 40-50 feet. The 
boundary of the restored vegetated buffer should be marked with a fence, boulder wall or a 
line of woody shrubs to identify the limit of lawn area maintenance and provide a minimum 
50 ft wetland buffer. 
Response. Additional native trees and shrubs have been added to the landscape plan on Sheets 
9 and 10 to delineate the edge of maintained landscape and the restored 50’ wetland 
buffer. 
2. The limits of vegetation disturbance and soil grading associated with the removal of past debris 
stockpiles should be minimized where possible to reduce soil disturbance to where debris is 
identified for removal. Per the E&S plan, perimeter silt fence is shown at the limit of clearing 
and grading 15-30 feet from the wetland boundary. It is not clear that debris stockpiles occur 
along the entire wetland perimeter. Measure to preserve undisturbed buffer area are 
recommended. 
Response. Based on field observations, we believe the limit of clearing and the downstream 
row of silt fence will allow removal of debris and stockpiles within contained areas.  
Disturbed buffer areas will be restored as shown on the plan or will remain 
undisturbed if debris is not present. 
3. Based on soil test data provided, the floor of the stormwater basins will be excavated close to 
seasonally high-water table, limiting the ability to infiltrate stormwater. Details for the 
stormwater wet pond construction should be provided in the site plans, indicating 
substrate/growing media depth, vegetation cover and wetland planting species and number. 
Response. Details have been added to the plan set for the stormwater basins. 
The bottom of Pond-01A is at elevation 29.5, which is approximately 4.5’ to 2.5’ 
below existing grades.  Soil testing in this area indicates that seasonally high 
groundwater occurs between 2.5’ and 3’ below grade at the bottom of a silty loam 
layer.  The bottom of the basin is generally set at the seasonally high groundwater 
level to remove the silty loam layer, install a suitable filter and growing medium 
and encourage infiltration into the sand and gravel till layer. 
The bottom of Pond-02A at elevation 27.5, which is approximately 2.5’ to 1.0’ 
below existing grades.  Soil testing in this area indicates that seasonally high 
groundwater occurs between 2.5’ and 3’ below grade at the bottom of a silty loam 
layer.  The bottom of the basin is generally set at the seasonally high groundwater 
level to remove the silty loam layer, install a suitable filter and growing medium 
and encourage infiltration into the sand and gravel till layer. 

 
WATERFORD WOODS MULTI-FAMILY DEVELOPMENT 
 
WATERFORD, CONNECTICUT 
 
ENGINEERING RESPONSE 2 
 
4. In accordance with the DEEP Stormwater Manual, the wet ponds should be provided with a 
forebay sized to hold 10% of the water quality volume to allow for removal of suspended 
sediments and preserve the function and capacity of the main basin component. The applicant 
should address what modifications are incorporated to provide this recommended 
pretreatment. 
Response. Sediment forebays are shown for both Pond-01A and 02-A. The combined forebay 
volume for 01A has 100% of the WQV capacity and 02A has greater than 50% 
WQV capacity.   
5. The stormwater basins are proposed to serve as temporary sediment traps during construction. 
The construction sequence or narrative should include details for the conversion of the 
temporary sediment traps to permanent stormwater basins and any temporary soil stabilization 
measures to protect from soil erosion. 
Response. Details have been added to the plan and note 7A added to the Erosion and 
Sedimentation Control Notes. 
6. The wetland assessment indicates there is a likely vernal pool in the on-site southwestern 
wetland. The applicant should evaluate whether exclusion measures should be incorporated 
into the stormwater pond design to deter amphibians from using the basins as potential decoy 
pools. 
Response. In general, the primary function of Pond 01A and 02A is peak flow attenuation.  
Sediment forebays are proposed to provide pretreatment.  The floor of each 
detention pond is depressed 8” to 12” below the lowest stage orifice to promote 
groundwater recharge through a filter bed growth media consisting of a topsoil, 
mulch and sand mixture.  While the depressed bottom of the basins may hold 
stormwater for 48 to 72 hours after a storm event, we do not anticipate the 
temporary ponding to last long enough to warrant exclusion measures.  An 
underdrain will be installed at the bottom of the filter bed to ensure the filter bed 
does not hold water for excessive periods of time. 
7. Construction and stabilization details are required for the vegetated filter swales and rain 
garden area. 
Response. Details have been added to the plan set. 
8. The stormwater operations and maintenance narrative must include timing and frequency of 
inspection and maintenance of the vegetated swales, wet pond and stormtech infiltration units. 
Response. Inspection and maintenance information added to Sheet 5. 
9. Test pits in the vicinity of the infiltration chambers indicate potential for bedrock 4-6 ft below 
surface grade. A minimum of 3 feet of separation between the bottom of the infiltration stone 
and bedrock is recommended to maintain adequate drainage. Additional test pit data should be 
developed to determine whether the infiltration galleys can be installed and function where 
proposed. 

 
WATERFORD WOODS MULTI-FAMILY DEVELOPMENT 
 
WATERFORD, CONNECTICUT 
 
ENGINEERING RESPONSE 3 
Response. The bottom of the Stormtech System B stone is set at elevation 28.50, which is 2.5’ 
to 1.0’ into existing grade.  Test pits performed in the area (D101 & D102) indicate 
that ledge is present at depths ranging from 5’ to greater than 7’.  A minimum 
separation of 2.5’ to bedrock is anticipated, with most of the system providing a 
separation of 3’ or greater.  As a conservative measure, the infiltration system has 
been designed with a minimal 1” per hour infiltration rate.