General hazard controls for any excavation. Surface encumbrances that create a hazard must be removed or supported. Before an excavation is opened, the estimated location of sewer, telephone, fuel, electric, water or other underground installations likely to be met must be determined, and utility companies or owners must be contacted within customary local response times, told of the work and asked to locate their installations. If they cannot respond within 24 hours (or any longer period that state or local law sets), or cannot pin down the exact location, the employer may go ahead cautiously using detection equipment or other acceptable means. As digging nears the estimated location, the exact position must be found by safe means, and exposed installations must be protected, supported or removed while the excavation is open. Structural ramps used only by employees for access or egress must be designed by a competent person; ramps for equipment need a design by a competent person with structural design qualifications, and must be built as designed. Multi-member ramps and runways must be joined against displacement, use members of uniform thickness, have cleats fixed underneath or placed so they do not trip, and ramps used instead of steps need cleats or a non-slip top surface. Trenches 4 feet or deeper must have a ladder, stairway, ramp or other safe exit placed so that no worker has to travel over 25 feet sideways to reach it. Employees exposed to public vehicle traffic must be given and wear reflective or high-visibility vests or garments. Nobody may stand beneath loads that digging or lifting equipment is handling, and workers must stand clear of vehicles being loaded or unloaded; operators may stay in cabs fitted with protection meeting 1926.601(b)(6). Where mobile equipment works beside or approaches an excavation edge and the operator cannot see the edge clearly, a warning system such as barricades, stop logs, or hand or mechanical signals must be used. Where oxygen below 19.5 percent or another hazardous atmosphere is present or reasonably foreseeable (for example in landfill areas or near stored hazardous substances), the atmosphere must be tested before entry into excavations deeper than 4 feet; precautions such as respiratory protection or ventilation under Subparts D and E must prevent exposure, flammable gas must be kept at or below 20 percent of its lower flammable limit, and where controls are used, testing is repeated as often as needed. Emergency rescue equipment (breathing apparatus, harness and line, or basket stretcher) must be readily available where hazardous atmospheres exist or may develop and attended when in use. Anyone entering a bell-bottom pier hole or similar deep confined footing must wear a harness with a separate, individually attended lifeline. Work in excavations holding or accumulating water requires adequate precautions; water removal equipment must be monitored by a competent person; where natural drainage is interrupted, ditches or dikes must divert surface water, and excavations exposed to heavy-rain runoff require a competent person inspection. Where adjacent buildings, walls or structures are endangered, shoring, bracing or underpinning must keep them stable. Digging below a footing or retaining wall base that could endanger workers is allowed only with a support system such as underpinning, in stable rock, or with a registered professional engineer's approval that the structure is far enough away or that no hazard results. Sidewalks, pavements and appurtenant structures may not be undermined unless employees are protected from their possible collapse by a support system or another method. Loose rock or soil on faces must be controlled by scaling, barricades or equivalent, and spoil, materials and equipment must be kept at least 2 feet back from the edge or held by retaining devices, or both. A competent person must inspect excavations, adjacent areas and protective systems daily before work starts, as needed during the shift, and after each rainstorm or other event that increases hazards, whenever employee exposure can reasonably be anticipated; when signs of cave-in, protective system failure or hazardous atmosphere are found, exposed employees must be removed until made safe. Walkways must be provided where people or equipment cross excavations, with guardrails complying with 1926.502(b) where the walkway sits 6 feet or higher above a lower level.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.