The Vermont Public Service Board (PSB), in an order entered on Sept. 12, granted Green Mountain Power’s (GMP) petition for a certificate of public good (CPG), subject to certain conditions, related to the company’s proposal to reconstruct the South Brattleboro substation located on Cotton Mill Hill Road in Brattleboro, Vt.
As noted in the order, GMP in July submitted the petition for the project, which consists of rebuilding the substation at its current location to replace an aging transformer and other aging infrastructure, to address clearance issues, to improve substation operability, and to provide greater operating flexibility for feeder backup during planned and emergency outages. That would improve system stability and reliability, as well as accommodate future load growth, the PSB said.
According to the company’s petition, the proposed design of the project will include:
- Reconstruction of the substation yard with gravel parking; a new yard fence; new steel structures and foundations; an oil containment system; a retaining wall; a ground grid; a new conduit system; a cable trench system; yard stone; emergency fence lights; and a security system
- One 69-kV air break switch and one 69-kV circuit breaker
- Three 69-kV phase to neutral bus potential transformers with fuses
- One 15/28 MVA, 69 to 12.47-kV autotransformer to replace the two existing units
Construction is anticipated to occur from April 2017 through December 2017, the PSB said in its order, adding that the project’s estimated cost is about $3.7m.
The project will meet the need for present and future demand for service, which could not otherwise be provided in a more cost-effective manner through energy conservation programs and measures, as well as energy efficiency and load management measures.
The PSB also said that the Brattleboro region has four substations with circuit ties that provide feeder backup opportunities. Loss of any one transformer due to a planned or emergency situation decreases the total area transformer capacity to a level that is close to the regional loads, the PSB said, noting that additional backup limits could quickly consume the difference, resulting in limited future load capacity for the entire area feeder backup.
The PSB said that the project will not have an undue adverse effect on aesthetics, historic sites, air and water purity, the natural environment, the use of natural resources, or public health and safety.
Construction activities will be managed in accordance with the Vermont Department of Environmental Conservation standards and specifications for erosion prevention and sediment control, which will help suppress dust, the PSB said.
Discussing aesthetics, the PSB noted that the project will not have an undue adverse effect on aesthetics, adding that the project involves reconstruction of an existing substation at its current location. The rebuilt substation will look similar to the existing substation, although there will be changes to the appearance of the adjacent slope, the oil containment system, and the perimeter fence, the PSB said.
The PSB said that the project will not have an undue adverse effect on rare and irreplaceable natural areas because it will be located in a previously disturbed site in a densely populated area that does not contain any such resources. Also, the project will not destroy or significantly imperil necessary wildlife habitat or threatened or endangered species.
Among other things, the PSB said that GMP is to restrict construction activities to the hours of 7 a.m., to 5 p.m., Monday through Friday, 8 a.m., and 5 p.m., on Saturdays, and is to cease construction activities on Sundays and state or federal holidays.