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. Section No 6 <br /> Revision No. 1 <br /> Date: January 13, 1992 <br /> Page 31 of 55 <br /> interval at which the drill rods are advanced while the sample is collected, <br /> and note this information in the borehole log The viscosity of the drilling <br /> fluid, penetration rates, drilling characteristics, and sample "lag-time" <br /> will also be noted in the log Composite samples representing 5-foot sample <br /> intervals will be bagged for future study <br /> Undisturbed samples may be collected using the Diedrich sampler and <br /> related techniques described in Section 6 5.1 The Diedrich sampler is <br /> fastened to the lead drill rod, lowered to the bottom of the borehole and <br /> hydraulically pushed or hammered into the undisturbed soils in a manner <br /> similar to the hollow-stem auger (HSA) method <br /> Following completion of the borehole, the lithology may be <br /> electronically logged using the geophysical methods described in Section <br /> 6 10 3 <br /> 6 5 3 Test Pit Exploration <br /> For many engineering investigations, backhoe equipment is used for <br /> excavation The locations of test pits are specific to each given task and <br /> will be described in the Work Plan for each given task Trenching locations <br /> will be determined on the basis of field reconnaissance completed by field <br /> personnel with the approval of the group leader Trenching locations will be <br /> free of any overhead or subsurface obstructions The process of selecting <br /> the trench locations will be documented <br /> Selection of the excavation equipment to be used and dimensions of the <br /> test pit are dependent on the project objectives and will be defined in the <br /> • Work Plan for each given task If over 5 feet deep, the test pit will be <br /> 6-31 <br />