Adeteriorated 700-foot-length of 8-inch steel water main feeding the private water treatment plant for the south side of Yosemite (Calif.) National Park was leaking.
The National Park Service had replaced all but this section of the 95-year-old line with C900 pipe. It was encased in a 4-foot-square block of concrete embedded with river stones the size of bowling balls. The massive aboveground structure paralleling the Tuolumne River prevented the pipe from washing away in spring floods.
Excavating the main would disturb the environment, cost millions of dollars, and wasn't an option. The prime contractor for federal
