Drainage Analysis-Newgate/Phelps & Hatchett Hill Road Areas Rev. 1 Introduction

3.0 INTRODUCTION

Based on the comments received from residents and town officials through various forums,

CL&P initiated a review of existing drainage conditions in two areas along the GSRP route.

These areas are located in the vicinity of Newgate Road and Phelps Road in East Granby and

Suffield; and Hatchett Hill Road in East Granby. As stated above, the residents are concerned

that construction, including the additional tree clearing proposed by the Project, will

alter/increase the amount and frequency of runoff they currently experience on their property.

The objective of the review was to evaluate existing drainage conditions/patterns and to develop

a plan to manage surface water flow during construction to minimize the chance that the Project

would have a detrimental impact on the existing drainage conditions/patterns. Developing

permanent solutions to the pre-existing surface water runoff or ground water issues (which can

be attributed to development upslope of the right-of-way, conditions created during site work

associated with construction on the parcels where issues now occur, or the construction of homes

on poorly drained soils) are very complex by nature, and are further complicated by the fact that

CL&P’s only interest in the land is by way of easement (limited ownership in fee). As a result,

this plan predominantly focuses on the use of temporary surface water control measures during

construction.

The Project does not propose an increase of impervious surfaces within these areas, therefore it is

not expected that there will be a long-term increase in surface water runoff resulting from the

construction of the Project. Accordingly, the control measures recommended in this report have

been designed to provide adequate control of the existing surface water flow (sheet and

concentrated), and a small, temporary increase in surface water flow that can be expected during

construction. Properly managing the surface water flow will minimize the probability that the

pre-existing localized flooding issues will be exacerbated, and that erosion and sedimentation

issues associated with the ground disturbing construction activities will occur. All the proposed

controls will remain in place until the areas have been stabilized and surface water volumes have

returned to pre-construction levels.

Typically, utility projects such as this are required by the regulating agencies to develop surface

water control measures to protect water resources during construction. However, after being

Northeast Utilities 3-1 Burns & McDonnell

Drainage Analysis-Newgate/Phelps & Hatchett Hill Road Areas Rev. 1 Introduction

made aware of the pre-existing drainage/surface water runoff problems in these areas, CL&P has

developed control measures that normally would not be prescribed if protection of water

resources was the only objective. In the two areas of concern, the traditional control measures

associated with the protection of wetlands and watercourses, minimizing sedimentation and

erosion, and maintaining the stability of all improved surfaces (access roads and crane pads),

have been further augmented by additional control measures to address local concerns. The final

D&M Plan, as submitted to the CSC and each town, has been amended to include all additional

controls identified in this report.

All control measures will be inspected regularly and will be repaired, reinforced, and upgraded

as needed throughout the Project’s duration. Northeast Utilities Transmission Business Unit’s

Best Management Practices: Construction and Maintenance Environmental Requirements –

Connecticut (provided under separate cover or as an appendix to the D&M Plan for Construction

of the Greater Springfield Reliability Project) will be adhered to when inspecting and

maintaining all erosion control measures.

3.1 NEWGATE/PHELPS ROAD AREA, EAST GRANBY AND SUFFIELD The Newgate/Phelps Road area is generally bounded by Phelps Road on the north, Newgate

Road on the west, the western slope of West Suffield Mountain on the east, and the intersection

of Copper Hill Road and Newgate Road on the south. Except for residential development to the

west of the ROW, and scattered residential development to the east, the area consists of wooded

land with varying slopes that are in excess of 30 percent in some areas. This area is shown on

Figure 1.

3.1.1 Public Comments Comments from several home owners along Phelps Road and Newgate Road were received.

Most comments reflected that some residents in this area have installed engineered drainage

systems to control the water that flows down the hill, through the ROW, before reaching their

properties at the base of the slope. These systems are currently effective, but the residents are

concerned the construction may result in runoff changes that their engineered systems are not

designed to handle.

Northeast Utilities 3-2 Burns & McDonnell

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Source: AECOM, Coler & Colantonio, ESRI and Burns & McDonnell Engineering. Image Source: Optimal Geomatics and CT DOT

1,500 0 1,500750 Feet

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Drainage Analysis-Newgate/Phelps & Hatchett Hill Road Areas Rev. 1 Introduction

Another resident expressed concern about an existing drainage issue between his home and his

neighbor’s home. According to this resident, during rain events water flows from the ROW

behind their homes to Newgate Road where it frequently freezes during the winter.

3.2 HATCHETT HILL ROAD AREA, EAST GRANBY This area is approximately bounded by Holcomb Road on the north, the western slope of

Hatchett Hill on the east, Hatchett Hill Road on the south, and the approximate toe of the slope

for Hatchett Hill on the west. Adams Road, a cul-de-sac, ends at the west edge of the ROW.

Marsh Pond and its associated wetland system are located to the south of Adams Road. This

system receives surface and ground water from the south, from residential development to the

west and north, and from Hatchett Hill to the east. The west slope of Hatchett Hill is heavily

wooded with steep slopes of 10 percent or greater. This area is shown on Figure 2.

3.2.1 Public Comments A resident that lives at the end of Adams Road expressed concern that Marsh Pond and its

associated forested wetland system south of his property frequently overflows. He further

contends that if the Project causes more water to drain into the pond during construction, it may

exacerbate the problem. The resident states his yard, as well as his street, can be a sheet of ice

during the winter. He suggested that the Project consider tying into the Town’s existing storm

drainage system in the street to capture the runoff leaving the ROW, thereby decreasing the

amount of additional water that ultimately reaches his property.

Northeast Utilities 3-3 Burns & McDonnell

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Expanded ROW 500 250 0 500 Feet Source: AECOM, Coler & Colantonio, ESRI and Burns & McDonnell Engineering. Image Source: Optimal Geomatics and CT DOT