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• Soil type <br /> • • Surface and groundwater <br /> • Water table location <br /> • Overhead and underground utilities <br /> • Weather conditions <br /> • Presence of hazardous waste/materials <br /> These and other conditions can be determined by job site studies, observations, test <br /> borings for soil type and conditions, and consultations with local officials and utility <br /> companies. <br /> Before any excavation begins, the contractor shall determine the estimated location of <br /> utilities (sewer, telephone, fuel, gas, electrical, water lines). In addition, the contractor <br /> must contact the utility companies, Digsafe, USA Alert, or similar, before excavating. <br /> 512.4 ON THE JOB EVALUATIONS <br /> The excavation/trenching standard requires that a competent person inspect, on a daily <br /> basis, excavations and the adjacent areas for possible cave-ins, failures of protective <br /> systems and equipment, hazardous atmospheres, or other hazardous conditions. If any <br /> of these conditions are encountered, the exposed employees must be removed from the <br /> hazardous area until the necessary safety precautions have been taken. Inspections are <br /> • also required after natural (i.e. rain) or man-made events (i.e. blasting), that may <br /> increase the potential for hazards . <br /> If employees or equipment are required or permitted to cross over an excavation, <br /> walkways or bridges with standard guard rails shall be provided. <br /> 512.5 CAVE-IN AND PROTECTIVE SUPPORT SYSTEMS <br /> Excavation workers are exposed to a wide variety of hazards, cave-ins being the chief <br /> danger. OSHA requires that in all excavations employees exposed to potential cave-ins <br /> must be protected by sloping or benching the sides of the excavation, supporting the <br /> sides of the excavation, or placing a shield between the side of the excavation and the <br /> work area. <br /> Design of the protective system can be complex because of the number of factors <br /> involved. These might include soil classification, depth of cut, water content of the soil, <br /> changes due to weather and climate, or other operations in the vicinity. The new Federal <br /> standard provides several different methods and approaches (4 for sloping and 4 for <br /> shoring, including the use of shields) for designing protective systems that can be used <br /> to provide the required level of protection against cave-ins. These alternatives or options <br /> include the following: <br /> 2 <br />