A last-ditch effort on July 16 by two Washington Suburban Sanitary Commission technicians to close a stubborn, corrosion-covered valve for water-pipeline diversion enabled the Washington, D.C., area water-wastewater utility to bypass the rapidly failing main. Closing the valve averted an extended service outage in a densely populated section during excessively hot weather.

The 54-in.-dia reinforced-concrete high-pressure transmission line, installed in 1966, supplies 10 million to 15 million gallons a day to more than 100,000 users in a large portion of Prince George's County, Md., including residences, Andrews Air Force Base and the National Harbor mixed-use complex adjacent to the Potomac River. Acoustical tests taken in mid-July showed that 37 strands of reinforcing wire had broken, indicating a failure—potentially in the form of an explosion—was imminent. WSSC, which dates to 1918, now serves 1.8 million people in the county and neighboring Montgomery County with a network of nearly 5,600 miles of freshwater pipeline.