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Petition No. 760
Sasco Creek Substation
Clayton Street, Westport
Staff Report
March 17, 2006

On March 3, 2006, the Connecticut Light and Power Company submitted a petition (Petition) to the Connecticut Siting Council (Council) for a declaratory ruling that no Certificate of Environmental Compatibility and Public Need is required for the proposed modifications to the existing Sasco Creek substation located at Clayton Street, Westport. This Petition was field reviewed by Council member Dr. Barbara Currier Bell and Michael Perrone of the Council staff on March 15, 2006. Three representatives from CL&P also attended the field review: Robert Carberry, Manager of Transmission Siting and Permitting; Christopher Swan, Director of Municipal Relations and Siting; and Robert Trotta, Project Siting and Permitting Specialist.

The Sasco Creek substation (owned by the Connecticut Department of Transportation) currently is supplied by two CL&P 115-kV overhead transmission lines. Two existing 28 MVA, single-phase transformers step the voltage down from 115-kV to 27.6-kV. Two overhead 27.6-kV feeders exit the substation and feed an adjacent railroad substation which is located to the west of the Sasco Creek substation.

In order to maintain electric reliability in the Westport area, CL&P proposes to install within Sasco Creek Substation: an 18 MVA transformer; a 115-kV circuit breaker to protect the transformer; three wood pole structures to accommodate the connection of the circuit breaker to the 115-kV bus; two outgoing 13.8-kV feeders; and one wood pole to support the feeders.

This modification to the substation is proposed to be temporary. It would supply local CL&P customers until a future substation is sited and permitted. (A future substation in Westport has not been identified in CL&P’s annual forecast report.) All equipment would remain within the substation except for the overhead 13.8-kV feeders, which would leave the substation to feed into the local distribution system. The three new 115-kV wood poles (one for each phase) to be installed inside the substation would be approximately 34’ tall. Another wood pole would be installed inside the substation to carry the two 13.8-kV feeders out of the substation. This pole would be approximately 32’ feet tall. The existing steel 115-kV structures are approximately 51’ tall at the lightning mast. The existing steel 27.6-kV structures are approximately 40’ tall. Thus, the new poles would not exceed existing structure heights at the substation.

To the north of the substation are railroad tracks and Interstate 95. Three homes are approximately 300’ to the south of the substation. However, views from these homes are reduced by existing trees; also, since their elevation is higher than the substation, these residents don’t look at it but over it. The proposed wood poles are expected to have less visual impact than steel structures, given their color and the existing trees.

The insulating oil in the transformer would be a non-PCB oil. In addition, a containment berm would be installed around the transformer to contain the oil in the event of a leak. It would have a capacity of at least 3,000 gallons, which is sufficient to hold the entire amount of the transformer’s oil. Imbiber beads would allow the drainage of water, but would stop any oil from leaving the containment berm. (When oil is present, the imbiber beads expand to block the flow; they allow water, however, to pass through.)

There is not sufficient space between the proposed transformer and the existing south perimeter fence to meet safety-code requirements, so CL&P also proposes to temporarily add a second fence section opposite the new equipment, via a rectangle with dimensions of 8’ x 40’. This area is largely cleared already.

The existing substation was constructed within a wetland. This project would not involve any significantly greater impact to the wetland than what occurred at the time of initial construction.

Sound levels would meet state regulations at the property lines. The dominant sources of noise in the area are I-95 and the railroad. This proposed project is not within the 100-year flood zone or any stream channel encroachment lines.

If approved, construction would begin as soon as possible. The estimated date for completion would be the end of May 2006. This installation would be expected to be in place for several years, given the significant lead time associated with locating a new substation site.

Also, if approved, staff suggests including a condition that the site is restored to its previous condition when the equipment is removed.