Valley Forge, Pa., December 1, 2010 — The PJM Board approved $1.25 billion in transmission improvements, including a capacity improvement project to rebuild one of the most heavily used transmission lines in PJM.

The $320-370 million rebuild of the 500-kV line between the Mt. Storm substation in West Virginia and the Doubs substation in Maryland will increase the capacity of the line by more than 60 percent by improving electrical clearance and adding conductors.

Originally approved in 2007, the 277-mile, 765-kV Potomac-Appalachian Transmission Highline between West Virginia and Frederick, Md. has a required in-service date of June 1, 2015, and an estimated cost of $2.1 billion.

During 2010, the PJM Board has authorized $3.92 billion in transmission additions and upgrades as part of PJM’s 15-year Regional Transmission Expansion Plan. More than $19.02 billion in transmission improvements have been authorized since PJM’s formal planning process began in 2000.

PJM Interconnection, founded in 1927, ensures the reliability of the high-voltage electric power system serving 51 million people in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia.

PJM coordinates and directs the operation of the region’s transmission grid, which includes 6,038 substations and 56,500 miles of transmission lines; administers a competitive wholesale electricity market; and plans regional transmission expansion improvements to maintain grid reliability and relieve congestion.