Southeastern Connecticut is in one of the most power-constrained regions in the United States. During peak periods, Connecticut uses more power than it generates, creating a need to import energy from out-of-state sources. The Killingly Substation project is one Northeast Utilities' (NU; Berlin, Connecticut) many infrastructure upgrades targeting Connecticut's — and southern New England's — bulk-power transmission system.

For a long time, one of Connecticut's highest-risk regions was the eastern tier, extending westward from the Rhode Island border for approximately 25 miles (40 km) to New London and northward from Long Island Sound to Massachusetts. Eastern Connecticut is a key economic component of the state. This region is home to Electric Boat of General Dynamics, the Department of Defense's Groton Submarine Base and Pfizer Corp.'s largest research and development site. In addition, the northeast corner's casinos are some of the state's largest private employers.

What's more, the I-395 corridor, which runs through the region from Montville to Thompson, Connecticut, is experiencing ongoing economic development, with an influx of new industry and homes adding to the area's energy demand. Yet the region's electric power system fell short of the recently upgraded national, regional and local reliability performance standards. Something had to be done to comply with the increasing demands and new industry standards.

The Solution

The solution became known as the Northeast Connecticut Reliability (NECTR) project, the main focus of which was the installation of a 345-kV/115-kV substation on existing property of Connecticut Light & Power (CL&P; Hartford, Connecticut), a wholly owned subsidiary of NU. This greenfield facility, which straddles the town line between Killingly and Putnam, Connecticut, and is now known as the Killingly substation, lies within 600 ft (180 m) of CL&P's existing Tracy substation. While consideration was given to performing a large-scale expansion of the Tracy substation, rather than installing a new facility, nearby topography and wetlands complicated this option. Beyond that, starting from scratch allowed more flexibility to get the project done right, specifically allowing for the future expansion of this bulk power substation.

Although three other CL&P-owned locations were considered for the project, the Killingly/Putnam site was clearly the ideal option. Proximity to the Tracy substation put the new facility not just close to customer load, but also directly beneath the 345-kV interstate bulk-power transfer line from Rhode Island, as well as Tracy's 115-kV lines. In addition, installation at the Killingly/Putnam site would have minimal environmental effects, involve only a moderate amount of earthwork and be consistent with local zoning regulations.

The site also would allow minimal visibility from outside the perimeter of the substation, an added benefit for the community that welcomed NU's investment in the region's future. The bolstered infrastructure would not only improve power reliability and quality, it also would provide the energy capacity to support further economic development in Connecticut's eastern tier.

Project Approach

Along with the installation of a 345-kV/115-kV transformer (600 MVA) and associated circuit breakers at the Killingly substation, the NECTR project called for ancillary transmission-line modifications, as well as system protection and control upgrades at five existing substations in the region. This comprehensive solution would not only bring the eastern Connecticut transmission system into compliance with industry standards, it would create an infrastructure capable of supporting long-term load growth: a solid transmission backbone enabling access to lower-cost power generation elsewhere in New England.

The largest component of the NECTR project, the Killingly substation development required a large-scale engineering and construction effort, supported by an array of highly qualified personnel including environmental, siting, procurement, contracts and engineering/design specialists. It was subject to the technical, financial and scheduling risks inherent to projects of this nature. With two major transmission projects already under way (Bethel/Norwalk and Middletown/Norwalk), NU determined that the engineer-procure-construct (EPC) approach would be the most effective project-delivery method.

After reviewing competitive bids from four parties, NU awarded the NECTR EPC contract to M.J. Electric (MJE; Iron Mountain, Michigan, U.S.), an InfraSource company. With only a single contract for NU to administer, MJE assumed overall project responsibility, alleviating NU's internal resource constraints and assuming a good portion of the risk. As prime contractor on the EPC project team, MJE handled equipment procurement, managed the hiring and efforts of all subcontractors involved, and established a single point of contact to maintain a simple, direct line of communication with NU's project management and engineering team.