• Upgrading an 11-Mile Underground Circuit: Buzzard Point to Ritchie

  • PHI is committed to climate change adaptation and sustainability. Following a series of powerful storms that hit our service territories in 2012, we renewed our focus on improving the reliability of our electric infrastructure. As a part of the Maryland Grid Resiliency Task Force, as well as the District of Columbia Power Line Undergrounding Task Force, we are evaluating the general causes of storm-related outages, actions to reduce future outages and issues related to undergrounding power lines to improve reliability. The District Power Line Undergrounding Task Force is actively reviewing various options with great consideration given to cost versus benefits, funding mechanisms to execute the proposed undergrounding plan and feeder selection criteria.

    As difficult as replacement of overheadtransmission resources is, replacement of underground conductors with fluid-filled conduit, in use throughout the District and certain other areas, presents particular challenges. PHI determined it was necessary to upgrade an 11-mile underground transmission circuit (Pepco's longest underground circuit)connecting Buzzard Point, at the confluence of the Anacostia and Potomac rivers, and the Ritchie substation in Prince George's County, Md. Crossing under the Anacostia, through the U.S. military's Joint Base Anacostia-Bolling and along the National Park Service's Suitland Parkway, required intensive planning andcareful implementation during all phases of construction in order to protect the environment and maintain public safety.

    For this particular project, each manhole was dewatered and cleaned following strict environmental protocols, with any potential contaminants gathered for disposal. At strategic locations,the pipe was uncovered and liquid nitrogen was used to freeze the dielectric (insulating) fluid within. Once capped, the fluid was drained from the conduit and processed for recycling. The 11-mile conduit required removal of more than 100,000 gallons, or 10 tractor-trailer loads, of fluid. Handling the fluidsafely required strong environmental precautions, including development of spill control plans, use of containment devices and readily available qualified emergency response personnel.

    In order to ensure environmental protection, we developed environmental compliance manuals for the construction of each section of the project. For work near sensitive resources, including areas draining into the Anacostia River, redundant controls were put in place to prevent possible release of materials into the watershed. Our third-party environmental monitors inspect the sites regularly to document compliance, address potential issues and recommend proactive measures to protect natural resources. Our project team continues to demonstrate that aging underground infrastructure can be successfully upgraded to meet future needs, while protecting the public and the environment.