Abstract: At approximately 1:22 p.m. on November 9, 2004, an explosion and fire occurred when a Mountain Cascade, Incorporated excavator struck a 10-inch Kinder Morgan Energy Partners petroleum line. The San Ramon Valley Transmission Improvement Project (East Bay Municipal Utility District's domestic water main) required excavation of a 15-foot deep trench, setting of the ground support systems, and placement of 72-inch by 40-foot-long water line segments with fit-up and welding of the water line. The 10-inch petroleum line was carrying gasoline at the time of penetration, and was estimated to be at a pressure of 974 psi. When the line was punctured, the pressurized fuel was ignited by the welding operations. As a result of the excavator's puncture of the petroleum line, Employees #1 through #3 were killed and Employees #4 and #5 sustained serious burns and were hospitalized.