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Z2 Field Investigation <br /> ' The field investigation was conducted in two phases on March 13, 2002 and May 20, 2002. <br /> ' The first phase performed on March 13, 2002 consisted of drilling up to six soil borings using <br /> direct-push sampling equipment. Soil borings were located in accordance with Caltrans' Task <br /> Order 10-OA7401-ME(Figure 2). The soil borings were advanced to attempt to encounter first <br /> groundwater, which was expected to be encountered at approximately 10 meters (32 feet) below <br /> ground surface (BGS). Groundwater was not encountered in this phase of the investigation as <br /> site geology prevented the direct push drilling from reaching first groundwater. A well-cemented <br /> soil strata logged in the field as caliche was encountered between 7.9 to 9.1 meters (26 to 30 feet) <br /> ' BGS resulting in drill rig refusal. As a result of this caliche layer, only 3 of the 6 proposed <br /> borings were drilled in this phase. The borings were logged in general accordance with the <br /> Unified Soil Classification System(USCS) by an IT staff geologist under the supervision of a <br /> California-Registered Geologist. Boring logs are included in Appendix B. <br /> ' Discreet soil samples were collected at 1.3-meter(4-foot) intervals using a 5-centimeter(2-inch) <br /> diameter sampler lined with a 1.3-meter(4-foot) long acetate sleeve. The soil samples were <br /> labeled, packaged, and stored on ice in an insulated chest for transport under chain-of-custody <br /> manifest to a California-certified analytical laboratory. Drilling and sampling procedures are <br /> presented in Appendix C. <br /> ' The second phase performed on May 20, 2002 consisted of drilling two soil borings using <br /> ' hollow-stem auger(HSA) drilling techniques. The soil borings were advanced to first <br /> groundwater using 8-inch diameter augers. Groundwater was encountered at approximately <br /> 38.0 feet BGS. Discreet soil samples were collected at 1.3-meter (4-foot) intervals and were <br /> ' collected using a 5-centimeter (2-inch) diameter sampler lined with a 1.3-meter(4-foot) long <br /> acetate sleeve. The soil samples were labeled,packaged, and stored on ice in an insulated chest <br /> ' for transport under chain-of-custody manifest to a California-certified analytical laboratory. <br /> ' After completion of the soil borings, and to facilitate water sampling, a well casing was inserted <br /> into the selected soil borings. The casing consisted of approximate 2.5-centimeter(1-inch) <br /> diameter, Schedule 40, flush-threaded, 0.05-centimeter (0.020-inch), machine-slotted polyvinyl <br /> ' chloride (PVC)well screen. Dedicated disposable polyethylene bailers were used for sample <br /> collection. The groundwater grab samples were labeled,packaged, and stored in an insulated <br /> ' chest for transport under chain-of-custody manifest to a California-certified analytical laboratory. <br /> Groundwater sampling procedures are presented in Appendix C. <br /> -IIS4CRFPIICOMMOMsacDPVOOMRMJM31834 7881aodoc 2-2 <br />