Last summer The Northern Pass Transmission project (NPT) filed an application with the U.S. Forest Service (USFS), outlining its proposed use of an existing transmission corridor within the White Mountain National Forest (WMNF). The application detailed a preliminary design for the inclusion of the NPT line, while also noting that the project’s design could change based on evolving engineering data and ongoing dialogue with the USFS, the Department of Energy, and other stakeholders.
Since filing our initial application with the USFS, NPT engineers have continued to gather and assess data in an effort to refine and improve the proposed design. As a result of these efforts over the past year, the NPT team has been able to significantly lower proposed structure heights.
The submittal of this proposed redesign serves as a formal update to our application before the USFS. The proposed structure design has been lowered to a typical height of 85 feet for areas in the WMNF. As before, this new design can safely be sited within the existing 150 foot right-of-way without the need for widening.
The lower structure heights are a result of installing horizontally configured structures, with V-String insulators, instead of using the vertical structures. A V-String design reduces the spacing requirements associated with horizontal designs (see structure depiction on the right side of the attached graphic). In other words, a V-String design minimizes how much an insulator can move in windy conditions, which keeps the transmission line a safe distance from the edge of the right-of-way.
NPT is pleased to announce this proposed redesign as a positive step forward in ensuring the transmission corridor in the WMNF can continue to co-exist with the Forest, as it has for the past 60 years. Going forward, NPT will continue our dialogue with officials from the WMNF and other stakeholders, and provide updates about this proposal when available.