As a major component of the Central Maine Power Maguire Road Transmission Project, the Buxton 345kV Switchyard expansion was required to mitigate voltage, thermal and stability performance contingencies limiting power flow through the Maine – New Hampshire transmission interface. TRC’s role was to provide a turnkey solution including environmental permitting, design, procurement and construction for a yard expansion that would allow for the addition of two new termination bays, four additional 345kV breakers, replacement of five existing 345kV breakers and a control house expansion. Complicating the project was wetland impacts that required specific permitting and mitigation. As an existing in service 345KV switchyard the project required extensive design planning, and sequencing to limit outages and outage duration.
TRC, as a Joint Venture with ES Boulos, provided engineering, licensing, procurement, construction and project management services. The work at Buxton was completed in two phases: Phase One – Included engineering, construction and permitting for the two bay/four breaker expansion, and the control house addition. Additional minor protection upgrades were required at two 345kV remote ends. Phase Two – Included the engineering and construction of five additional 345kV breaker replacements including protection and control upgrades for each breaker. Phase two also included a complete wetland mitigation project, which required expansion or improvements to wetlands at three separate southern Maine locations.
TRC provided the detailed project sequence plan and outage planning that allowed the project to proceed on schedule with minimal impact to the critical 345kV transmission system. Phase one of the Buxton project commenced in January of 2007 and completed in January of 2008, a significant achievement for the complex scope of work. Phase two breaker replacements were completed in June of 2008 allowing only two weeks of construction/outage for each breaker replacement and protection upgrade.