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� f <br /> ' Excavation,Trenching and Shoring Safety and the OSHA Excavation Standard- ... Page 2 of 2 <br /> In many construction projects, the soil that is being excavated has been previously disturbed.This <br /> means the soils has been dug up or moved in the past. This is another factor a competent person must <br /> consider when typing soils. Previously disturbed soils are rarely as strong as undisturbed soils, and are <br /> usually typed as"C"soil. Previouslydisturbed soil is commonly found above existing utilities, such as <br /> water,sewer, electrical and gas lines.This makes work around these utilities more dangerous due to the <br /> unstable nature of the soil. Much of the work AFSCME members perform in excavations are along right- <br /> of-ways,where the soil is almost always likely to be Type C. Because of where we dig, it's important to <br /> understand that once soil has been excavated, it will never be returned to the way it was naturally formed. <br /> Per 1926 Subpart P,Appendix A(c)(2), a competent person must type soils by using at least one visual <br /> and one manual test.A visual test can include inspecting the soil as it is being removed, and examining <br /> the spoil pile and the color and make-up of the excavation walls.A manual test means working with the <br /> soil with either your hands or with an instrument designed to measure soil strength. For example, if you <br /> can roll the soil in your hands into a long"worm"or ribbon, the soil is cohesive and may be classified as A <br /> or B, depending on other conditions. One useful instrument for measuring soil strength is a <br /> penetrometer.When you press this instrument into a soil sample, it measures its unconfined <br /> compressive strength in tons per square foot(tsf). <br /> Regardless of the methods used,the typing of soils must be done by the competent person prior anyone <br /> entering the excavation. The weaker the soil,the greater the need for protective systems. <br /> Note:If you are uncertain of the soil type,ALWAYS assume Type C soil! <br /> http://www.afscme.org/health/excav04.htm 8/25/2005 <br />