D&M Staff Report: Norwalk Substation - Revised Landscape Plan/Revised D&M Plan

Docket No. 217
Connecticut Light & Power Company
Development and Management Plan
Norwalk Substation 345-kV Expansion

Connecticut Light Power Company (CL&P) submitted a Revised Landscape Plan on December 20, 2004, and a Revision to the Norwalk Substation Development and Management (D&M) Plan for the Norwalk Substation 345-kV Expansion on February 14, 2005.

The D&M Plan outlines revisions to the landscape plan consistent with the Council’s direction in approving the Norwalk Substation D&M Plan in October 2003. In addition, CL&P seeks to retain a 115-kV switchyard bay previously slated for removal, and construct foundation footings for a future terminal structure associated with Docket No. 292.

In developing a revised landscape plan CL&P considered construction of a berm between the Route 7 exit ramp and the substation compound. The location of the berm would be on property owned by the Department of Transportation (DOT). In consultation with DOT, DOT preferred not to have a berm for reasons of maintenance, snow removal, and emergency access and egress for the highway. Because the DOT controls the land and prefers a berm not be constructed, Council staff sees no reason to enforce such action.

Presently, the majority of the plantings have been installed and in areas where construction is complete loam, seed and mulch have been applied. Some plantings were not available during the Fall of 2004 and CL&P will continue landscaping in the Spring of 2005. Initially some non-native species were proposed for planting but have since been replaced with native species (i.e. columnar maple, red cedar, and arborvitae). In constructing a diversion channel for the Norwalk River, CL&P installed a biolog for support of plant species tolerant of a wet environment. A biolog is a 12-inch diameter coconut fiber log. Since installation, and a passage of a summer season, CL&P observed a reduction in the function of the biolog which needs to be in contact of moisture. Council staff with Diana Walden, Environmental Inspector of BSC Group, observed site conditions and suggested the biolog be placed lower in the channel and potentially closer to the water table of the Norwalk River. CL&P has reduced the length from 410 feet to 215 feet to coincide with the moister area of the channel, closest to the Norwalk River. Also, because of site conditions CL&P substituted plantings of Blue Flag iris and Arrow Arum tolerate of wet conditions (constitute 25% of plantings) and Joe Pyeweed and Fowl Bluegrass (constitute 75% of plantings) which are more tolerant of drier conditions.

In addition to landscaping revisions, CL&P seeks to retain a 115-kV switchyard bay previously slated for removal and construct foundation footings for a future terminal structure associated with Docket No. 292. Recent plans call for retaining the existing 115-kV switchyard bay for use in the near term. Also, a future terminal structure (for Docket No. 292) would straddle this existing 115-kV bay and CL&P requests the Council approve construction of foundations for this terminal structure. CL&P has space today and contractors on-site to do the foundation work compared to deploying a new contractor and contending with construction in a constrained switchyard compound. CL&P has updated its D&M Plan drawings to identify the existing switchyard bay to be retained, the foundations to be constructed, as well as a 345-kV structure previously discussed in text but not previously on the drawings, is now shown, and a concrete slab previously shown to be installed on the east side of the substation has now been eliminated.

CL&P has complied with the Council’s directive for landscaping, and has submitted changes of the D&M Plan to the Council for review and approval prior to construction; therefore, Council staff recommends approval of the D&M Plans revisions.