Pepco Holdings Inc. of Washington, D.C., will build a $470-million electric generating plant in Peach Bottom, Pa., the company said today.

The Lancaster County plant, to be called the Delta Power Project and completed by June 2011, will be operated by Conectiv Energy, Pepco's electric power subsidiary. Work on the project will begin in 2008 with the expenditure of the first $62 million, Pepco said in a Securities and Exchange Commission filing.

Delta Power will be fueled by natural gas and oil. Electricity generated there from 2011 to 2017 is to be sold to Constellation Energy Group Inc., but Conectiv will operate the 545-megawatt plant, Pepco said.

Conectiv provides electric and natural gas service in parts of New Jersey, Delaware, Maryland and Virginia through its Atlantic City Electric, Delmarva Power and Pepco operating units.