Five-and-a-Half-Foot Trench in July
A crew of six is installing a 2-inch irrigation main along a property line in North Las Vegas in July. The trench is 5.5 feet deep, 60 feet long, and 24 inches wide. The spoil pile is 18 inches from the edge. There is no ladder. A worker enters the trench to glue a fitting. The temperature is 110°F, a new hire is on his second day, and there is no water on site. A passing compliance inspector stops at the site. The crew has a trench box on the trailer but has not installed it because the excavation is 'only' 5.5 feet deep and the soil looks firm. The foreman says he checked the trench that morning but did not document the inspection.
1. List the safety violations an OSHA inspector would likely cite and the specific correction for each.
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At 5.5 feet deep, the trench is beyond the 5-foot point where OSHA requires a protective system unless the excavation is entirely in stable rock. A trench box, shoring, or properly sloped or benched sides must be in place before entry. The spoil pile is only 18 inches from the edge; spoil and equipment must be kept at least 2 feet from the edge, and the pile should be moved or retained. The 60-foot trench has no ladder; a means of egress must be within 25 feet of lateral travel for every worker. The crew also needs a competent person who inspects the excavation daily and after any change, and there is no documentation that inspection occurred. The lack of water in 110°F heat is a separate serious hazard. Corrections: install the protective system, move the spoil, place a secured ladder extending 3 feet above the trench, assign and document the competent-person inspection, and provide water, shade, and rest. Do not let anyone re-enter until those controls are in place.
2. What should the competent person verify before anyone re-enters the trench?
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Before re-entry, the competent person should verify the soil classification and confirm that the protective system matches the soil and depth. He should inspect the trench walls for tension cracks, sloughing, bulging, or water intrusion, and check the trench box or shoring for damage and proper placement. He should confirm that the spoil pile and equipment are at least 2 feet back, that the ladder is secured and extends 3 feet above the edge, and that there are no exposed utilities or hazardous atmospheres. If water is present, it must be controlled and the trench re-inspected. The inspector should also check traffic and vibration sources nearby. The inspection must be documented, and entry should be prohibited until any deficiency is corrected. The reasoning is that a trench can look stable and still fail; the competent person's inspection is the last control before a worker enters a 5.5-foot excavation.
3. What heat-illness controls should be in place for the crew that day?
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At 110°F, heat controls are as important as trench controls. Provide cool water within reach, shade or a cooled rest area, and a schedule that allows rest before workers become symptomatic. Acclimatize the new hire gradually; a second-day worker is at elevated risk. Shift heavy work to early morning, use a buddy system, and train the crew to recognize confusion, cramps, nausea, and cessation of sweating. Have an emergency plan with a way to call 911 and cool a worker immediately. The supervisor should conduct checks throughout the shift and record them. The reasoning is that heat illness is preventable but progresses quickly; water, rest, shade, and acclimatization are the core controls, and a new worker in extreme heat needs closer supervision than the experienced crew.