Lancaster, Pa., sits on the Conestoga River in the southeast corner of the state, some 60 miles west of Philadelphia. The Conestoga is a tributary of the Susquehanna, the largest river emptying into Chesapeake Bay. Lancaster contributes about 1 billion gallons annually to this watershed, too much of that fouled by combined sewer system overflows. The cost to store and treat this water conventionally would be prohibitive. Green infrastructure provided the better solution.

Founded and platted in the 1730s, and incorporated in 1818, Lancaster is rich in history (see sidebar). Unfortunately, that history includes an old combined sewer system with antiquated pipes and pump stations. Lancaster is one of about 770 combined systems still operating around the country.

“That old pipe and other infrastructure was causing problems,” says Charlotte Katzenmoyer, director of Public Works. “We didn’t have a consent decree from the EPA, but we did have an administrative order, so in 2011 we got started with our greening plan.”