Aberdeen Proving Ground (APG) is the Army's oldest active proving ground. It opened on October 20, 1917, six months after the U.S. entered World War I, to provide the military with a facility for the design and testing of ordnance material in close proximity to the nation's industrial and shipping centers. As a center for Army material testing, laboratory research and military training, the post is a key element in the nation's defense. APG occupies more than 72,500 acres in Harford County, Maryland and is home to more than 60 tenants and a host of satellite activities.

In an effort to reduce its energy usage and costs, APG wanted to shift a portion of its electric load from the existing transmission system to one it owned. This required the design and construction of a new substation.

Constellation experts evaluated APG's electric usage, systems and equipment, and designed and built a customer-owned, 115kV-34kV electric substation and associated equipment and services. Constellation also provided comprehensive operations and maintenance training for assigned APG personnel.

All project costs were financed through savings resulting from elimination of electric distribution system demand charges.