Client: Eversource Energy
The Stamford Reliability Project required a new 115 kV underground transmission line in one of Connecticut’s oldest cities in an effort to ensure the area’s electric grid conforms to national and regional reliability standards and meet growing energy needs. POWER provided specialized underground transmission capabilities to help with routing, design and construction management for this important and high-profile reliability project.
Challenges and Accomplishments
- Energized on time despite numerous construction setbacks including considerable dewatering, a trenchless crossing under the busiest railroad corridor in the United States, removing contaminants and capping.
- Less-intrusive pipe-jacking technique minimized impacts to project site and mitigated schedule constraints.
- Avoided disruption to urban street traffic by implementing night time construction schedule.
- Strategic routing realized cost efficiencies while satisfying multiple stakeholder interests and mitigating project obstacles.
- Met owner’s completion target through skillful coordination of multiple stakeholders (Owner, city, ConnDOT, Metro North, residents, etc.) to keep the project on track.
- Challenging 1.5-mile route between two existing substations, spanning both commercial and residential areas
- Crosses under the busiest metro railroad system in the Northeast
- Extends through an area of environmental contaminant containment
- Single circuit, XLPE cable system, concrete-encased duct bank, trenchless crossing and three splice vaults within city streets
- One overhead to underground transition structure, one substation termination structure, and a 165-foot pipe jack crossing
- Alternatives analysis
- Routing and siting
- Preliminary and detailed transmission line design engineering
- Electrical system studies
- Geotechnical and geothermal investigations
- City, agency, and interconnecting utility coordination
- Construction and material management
- Field engineering and compliance inspection