Petition No. 761

Northeast Utilities/CL&P

Frost Bridge Substation - Watertown, Connecticut

Staff Report

April 19, 2006

CL&P is seeking to make modifications at the Frost Bridge Substation location on Frost Bridge Road in Watertown, Connecticut. These modifications would consist of replacing an underground diesel fuel storage tank with an aboveground liquid propane tank and replacing an existing 300 kW three-phase diesel-fueled emergency generator with a 100 kW three-phase emergency generator fired by liquid propane.

Council member Ed Wilensky and staff member David Martin conducted a field review of this project on April 18, 2006. They were joined by Girish Behal of Northeast Utilities.

The proposed work is prompted by the need to replace the underground diesel tank, which is reaching the end of its useful life of approximately 30 years. CL&P chose to replace their diesel fuel with cleaner, more efficient propane, and because the existing emergency generator runs on diesel fuel, it also must be replaced.

The new propane tank will be located just inside the substation’s fence line near the entrance to the substation. This will eliminate any need for the tank’s service personnel to encroach very far into the substation.

The existing generator is oversized for the amount of power needed to perform the required backup function. The new generator will be sized more appropriately and will be located behind the relay and control enclosure.

The new generator will be approximately six feet high by ten feet long by three feet wide. It will not be seen from Frost Bridge Road. There will be an underground pipe to connect the propane tank near the front gate to the generator behind the relay and control enclosure. The generator would operate for approximately one half hour per month for maintenance purposes.

The proposed modifications will have minimal visual impact on the surrounding area. The fence line of the station will be unchanged. The generator will not be visible to passing traffic. The only visible addition will be the propane tank which will be a relatively minor addition to the existing substation structures and equipment.

This substation is located in a secluded area between Route 8, which is elevated in this vicinity, and the Naugatuck River. There are no homes visible from the substation, and the only nearby development is an industrial building to the north of the substation.