Abstract: At approximately 10:30 a.m. on May 18, 2006, Employee #1 was working for an employer that was excavating an old canal, replacing it with reinforced concrete pipes. Employee #1's coworker was operating a Caterpillar crawler excavator, Model Number 321CLCR, Serial Number MCF00300, with an operating weight of 52,911 lbs. The bucket used was a three yard Entek 320-5. Employee #1's coworker was told the approximate location of the canal, since the adjacent segments were removed earlier. The coworker dug up the ground to locate the canal that he estimated to be 3 ft deep. Meanwhile, Employee #1, a water truck driver was controlling dust using a water hose. Employee #1 was standing between the excavator's arm and a block wall, when suddenly, the ground under the excavator's left track gave away and the excavator's arm swung to the left striking Employee #1 against a block wall. The excavator had been operated at the end of a narrow alley between a hillside to the right, and a block wall of the back yards of houses on its left. The morning of the accident was the first time the excavator had been used at the site since the work had progressed to the end of the narrow alley and was approaching the open field. The backhoe had previously been used in the narrow alley. The coworker did not know that the left excavator's track was 2 ft above the canal. Employee #1 was hospitalized and treated for his injuries.