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4.3 Field Investigation <br /> The scope of work for this project includes an underground utility location survey and the <br /> advancement of up to four soil borings using direct-puE h sampling equipment. The utility <br /> surveys will be conducted using ground-penetrating radar(GPR) and electromagnetic radio <br /> frequency survey equipment. <br /> 4.3.9 Underground Utility Location Survey <br /> An underground utility location survey will be conducted to assess the absence or presence of <br /> unreported underground utilities at the site. The geophysical surveys will clear utilities for the <br /> direct push boring locations. <br /> F ' The surveys will be conducted using GPR and radio frequency survey equipment. The approach <br /> r. for the geophysical surveys will be to initially conduct a GPR survey to locally investigate <br /> suspect magnetic anomalies. Based on the GPR surve results, electromagnetic radio frequency <br /> pipe locating equipment will be used to investigate possible underground utilities. <br /> 4.3.2 Drilling and Soil Sampling <br /> 'Up to four soil borings will be advanced using direct-p sh sampling equipment. Soil borings <br /> i <br /> will be located in accordance with Caltrans' Task Order 10-OE7900-MT. Figure 2 shows <br /> r proposed boring locations. Three borings (B-2 through B-4) will be advanced to approximately <br /> 7.6 meters (25 feet)BGS. One boring (B-1) will be ad anced to approximately 12.2 meters ? <br /> (40 feet)BGS. Discreet soil samples will be collected at 1.5-meter(5-foot) intervals. Soil <br /> samples will be collected using a 5-centimeter(2-inch) diameter sampler lined with a 1.3-meter <br /> (4-foot) long acetate sleeve. Soil samples will be field screened using a photo-ionization <br /> detector(PID). A groundwater sample will be collected from each boring using one or more of <br /> ' the methods described in Section 4.3.3. Drilling and sampling procedures are presented in <br /> Appendix A. <br /> y ; i <br /> Following sample collection, the borings will be backfilled with bentonite cement grout from the <br /> bottom of the borehole to ground surface. Drill cuttings will be placed into a 208-liter <br /> y (55-gallon)United Nations-approved drum. <br /> I <br /> All drilling and sampling equipment will be washed prior to use. In addition, to minimize <br /> cross-contamination between borings, all appropriatedownhole drilling and sampling equipment <br /> will be washed between borings. Decontamination water will be placed into a 208-liter <br /> (55-gallon)United Nations-approved drum. <br /> -4M4CRPPACOMMOAAsasDR20021PR.APJBV M35M4.2e6.doc <br /> 4-2 <br />