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generated. Decontamination solutions will be poured onto shoulder areas, avoiding storm drains <br /> or conduits to surface water bodies, and be allowed to soak into the soil. Drilling and sampling <br /> procedures are presented in Appendix A. <br /> 4.2.1 Geophysical Survey <br /> A surface geophysical survey will be conducted to assess the presence or absence of underground <br /> storage tanks (USTs) and any other unreported underground utilities at the site. The surveys will <br /> be conducted using a magnetometer and ground-penetrating radar (GPR). The approach for the <br /> geophysical surveys will be to initially conduct a magnetometer survey to locate magnetic <br /> anomalies followed by the GPR survey to locally investigate suspect magnetic anomalies. <br /> The magnetometer survey will be conducted using nodes spaced approximately 10 feet apart. The <br /> magnetic field data will be reduced in the field and a contour map produced that is referenced to <br /> aboveground structures that may affect the results. The magnetometer should be able to detect <br /> metallic objects the size of a UST at depths of up to approximately 6 meters (20 feet) below the <br /> ground surface (BGS). <br /> Magnetic anomalies potentially created by a UST will be investigated using GPR. The GPR <br /> traverses will be spaced approximately five feet apart and oriented both parallel and <br /> perpendicular to the anomaly. A map showing GPR traverses and subsurface features located by <br /> the GPR will be produced by IT in the field. Based on the GPR survey results, electromagnetic <br /> radio frequency pipe locating equipment may be used to investigate possible underground <br /> utilities. <br /> 4.2.2 Soil Sample Collection <br /> The soil borings will be located using the boring location template provided by Caltrans (2000) <br /> and shown in Appendix A. Work will be conducted in the unpaved portion of the shoulders <br /> approximately every 30 meters (98 feet) where the shoulder is wide enough to allow for safe <br /> stopping of sampling and safety equipment. The borings will be located approximately 2 meters <br /> (6 feet) in from the edge of the pavement in each traffic direction as well as in any depressed area <br /> where runoff may accumulate or ponding may occur. Additional soil borings will be advanced at <br /> close proximity to railroad crossings, culverts, intersections, overpasses and bridge inlets <br /> encountered in the project area as indicated in the bore hole template. <br /> IT Corporation 3 120Auslin_wkp <br />