Glebe-Potomac River

New Proposed Transmission Project Changes
to Improvements at Existing Substations

In 2014, our team began work to address a forecasted reliability concern in the Alexandria-Arlington-Fairfax area, and proposed the new Glebe-Potomac River line project. Updated data on the need for the original project has changed and no longer requires a new line, but requires work on two existing substations in Alexandria and Fairfax to resolve our current energy challenge.

In July 2018, Dominion Energy received an updated base case study from PJM, a regional transmission organization, on load projections through 2023. This updated study revealed several changes to the electrical planning horizon – removing the need for certain work.

In addition to changing the need and scope of the solution, cost was also significantly impacted. Specifically, the estimated cost of the Rebuild Solution decreased from approximately $290 million to approximately $170 million. Alternately, the total estimated cost for the New Line Solution is approximately $340 million.

Following these changes, the New Line is no longer a justifiable solution for the current capacity need.

The current solution calls for Dominion Energy to rebuild its existing Glebe Substation in Arlington County and to expand its Occoquan Substation in Fairfax County.


Updated Documents:


This substation project will:

  • Comply with mandatory North American Electric Reliability Corporation (“NERC”) Standards
  • Support continued economic development and growth in the Alexandria/Arlington area
  • Maintain continued reliable service to local customers
  • Help strengthen the electrical grid


Current reliability studies have determined that by summer 2020, the existing transmission facilities in the City of Alexandria and Arlington County will no longer adequately meet demand and mandatory North American Electric Reliability Corporation (NERC) reliability criteria. In response, a new transmission line is proposed between Dominion Energy's Glebe Substation located at the intersection of S. Glebe Road and S. Eads Street, and Pepco’s Station C Substation at the intersection of Slaters Lane and E. Abingdon Drive.

Dominion Energy has presented and received approval for the need of the proposed project from PJM - the first step required as a member of the PJM regional transmission organization. Concerns include potential violations of mandatory North American Electric Reliability Corporation (NERC) reliability standards and potential overloads in the region given certain electric use and load contingencies.

The New Line Solution, formerly known as Glebe‐Potomac River Substation, requires a new 230kV underground transmission line from Dominion Energy’s existing Glebe Substation in Arlington County to Pepco’s existing Potomac River Substation in the City of Alexandria. Additional infrastructure improvements will be required at Glebe Substation and Potomac River Substation. The Rebuild Solution requires the re‐conductor, rebuild, and ampacity uprate of sections of existing overhead and underground lines in Fairfax County and the City of Alexandria. Additional infrastructure improvements will also be required at multiple Dominion Energy Substations.

Routes and project scope studies take into account input from neighbors, cost, routing constraints and regulatory requirements.


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