Abstract: At approximately 10:20 a.m. on April 8, 1991, Employee #1, of Mountain Crest Enterprises, was working at a site in Spokane, WA, when a 3 in. and an 8 in. PVC water line both ruptured. The pipes crossed an approximately 24 ft wide trench about 5 ft below the top of the trench. Employee #1 and a coworker shut off both lines, but the water from the ruptured pipes had undermined the sidewalk on the east side of the trench. Employee #1 saw some equipment close to the edge of the undermined sidewalk and as he went to retrieve it, the bank of the trench near the sidewalk collapsed. He slid into the trench and under the sidewalk, which fell on top of him. He was taken to the hospital, where he was treated for a bruised knee and released at approximately 2:00 p.m. the same day.