Finding leaks in water transmission mains before they become safety hazards is an ongoing challenge for the Washington Suburban Sanitary Commission in Laurel, Md. In 2009, the district repaired 1,847 water main breaks and leaks in Prince George’s and Montgomery counties, the second-highest calendar year total in the past quarter-century.But the real problem children in the agency’s 5,500 miles of water lines are 350 miles of 50- to 70-year-old prestressed concrete cylinder pipe (PCCP). The concrete core, steel cylinder, high-strength steel prestressing wires and mortar coating are highly sensitive to corrosion.Consequently, the commission has inspected all 59 miles of 54-
