Abstract: At approximately 9:00 a.m. on July 6, 1988, Employees #1 and #2 were leveling gravel approximately 11 feet deep at the bottom of an excavation, preparing to install a sanitary sewer line. A 10 inch diameter PVC water main had been installed approximately 3 feet deep along one side of the excavation 10 days before. A concrete thrust block had been poured around the water pipe next to a fire hydrant. The ground caved in beneath the block, causing the pipe to pull loose at a joint. The weight of the block caused the pipe to whip sideways, striking the employees. Employee #1 was killed and Employee #2 was hospitalized.