Excavation issues are always of importance to SH&E professionals in the construction industry. We will cover the essential elements of hazard identification as well as how hazards can be defined and then eliminated or controlled. By the end of our session every attendee should leave with a clear and practical picture of how to address various issues in the workplace.

Each year in the United States, an estimated 100 deaths occur and over 1,000 workers are injured in excavation accidents. Cave-ins pose the greatest risk and are much more likely than other excavationrelated accidents to result in worker fatalities. This presentation describes the greatest hazards in the workplace as they relate to excavation and trenching operations performed in the construction industry. When we evaluate the need for safety during excavations, the prime responsibility is always the safety of our personnel.

Excavation Hazards

Soil is heavy. A cubic foot can weigh as much as 110 pounds, and a cubic yard can weigh between 3,000 and 4,000lbs.-a little more than a small Pickup Truck. A person buried under only a few feet of soil can experience enough pressure in the chest area to prevent the lungs from expanding. Suffocation can take place in as little as three minutes while heavier soils can crush the body in a matter of seconds. And to know, for that moment you may never see your loved ones again.

The texture of the soil is a key to its stability. Cohesion is the ability of a soil to stick together instead of crumbling. The more cohesive a soil is, the safer. Soil is classified by its cohesive properties. With the exception of stable rock the soil types are A, B, and C. Type A soil is the most cohesive of the three soils. Clay, silty clay and clay loam are examples of type A. Type C is the least cohesive. Sand is type C soil. Sandy or loose grain soil have poor cohesive properties and are very dangerous and unstable. The cohesive property of type B lies between A and C.

Caution should be used when classifying soil. Other conditions may affect soil strength. Soil classification should be left up to the competent person. Moisture, vibration and load affect the stability of the soil. What may be safe at one time may not be safe at another. These changes occur often without sufficient warning to protect the workers.

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