Reliable Energy Supply and Appealing Architecture Marked a Connecticut Transmission and Substation Project

In the face of rising energy demand in the northeast United States, many utilities in the region were faced with the need to make major investments in transmission and distribution. One of those utilities, the United Illuminating Company (UI), needed help with two big projects – the Middletown-Norwalk transmission line and the Trumbull substation. UI provides electric service to more than 320,000 Connecticut customers.

The need for extensive work in populated residential areas added extra challenge to both projects. Also, land is at a premium in the UI service territory. As a result, electric facility designs needed to be compact while also providing room for potential future expansion. One of UI’s objectives was to ensure public input, so community feedback played an important role in the development of both the transmission line and substation.

Black & Veatch took on the projects with a history of successful partnership with UI.

The transmission project consisted of around 70 miles of 345 kV overhead and underground lines. It also included several 345 kV interconnection substations to service the southwest part of the state. Black & Veatch provided full engineering and construction management services for UI on its portion of the project. The scope of the work included a gas-insulated switchgear (GIS) substation and additions at two existing substations. It also included 5.5 miles of double-circuit 345 kV underground transmission utilizing solid dielectric cable.

The GIS substation was chosen for its minimal land use and noise abatement. The highly secure facility is enclosed in a precast concrete building that fits in well with its surroundings.

For the Trumbull project, Black & Veatch handled engineering, procurement and construction of the distribution substation. Also, an existing adjacent transmission line was routed into the station to connect Trumbull into UI’s electric system. The substation is enclosed within a precast concrete wall to screen it from nearby residences.

Black & Veatch supported UI in presentations for permitting of the projects, and in town and neighborhood meetings where issues and public concerns were addressed.