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New Substation Eases Peak Summer Loads at Lake Winnipesaukee

New Hampshire Electric Cooperative, Inc. (NHEC) is a member-owned electric distributor serving approximately 80,000 members/customers in nine of New Hampshire’s 10 counties. NHEC hired ESC engineering to design and oversee construction of the new Moultonborough Neck Substation which needed to go online in time for a busy summer season in one of the state’s premier Central Lakes playgrounds, specifically Lake Winnipesaukee. The substation currently serving this area was experiencing load capacity, especially during summer months when it supplied electrical service for both seasonal and year-round homes in the area.

Problem

Inherent seasonal restrictions in this part of the country affected project timelines and construction windows and required strategic planning to accommodate stop-and-go scheduling. The design approach for foundation work was impacted by harsh winter conditions and it was necessary to excavate below the frost line to circumvent damaging frost heave. An oil-filled transformer and voltage regulators also required an oil spill separation and containment system to prevent any oil spillage, while an adjacent wetlands area surrounding the site necessitated setbacks to prevent any environmental damage from the construction efforts.

Approach

Long-range planning to accommodate seasonal construction restrictions was a pivotal factor in project success. In-ground construction was planned during the fall season and was completed in November. Construction efforts resumed the following spring and focused on the above-ground aspects of this project. A spread footer foundation was embedded 6.5 feet below ground to minimize concrete heaving that occurs during freeze/thaw cycles. A maintenance-free oil containment system was also designed to connect to an oil-filled transformer via a 6-inch PVC pipe which drained into a below-surface 3,000-gallon concrete holding tank. ESC worked with a surveying company to design a perimeter silt fence to delineate the limits of the construction site and restrict any hazardous runoff from contaminating the wetlands area.

Result

The Moultonborough Neck Substation was completed and energized in time to meet increased electrical service demands during Lake Winnipesaukee’s busy summer season and shifted load capacity to adequately serve the surrounding neighborhood. All aspects of this project went smoothly with no significant issues and the project came in under budget.