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23 Groundwater Depth and Gradient <br /> Information obtained from nearby monitoring wells in Tracy indicate that groundwater <br /> depth at the site is between 8 to 10 feet. Groundwater flow direction in the Tracy area is <br /> generally to the north. <br /> 3.0 SCOPE OF WORK <br /> The San Joaquin County Public Health Services - Environmental Health Division <br /> (PHS/EHD) is requiring further investigation of the site to determine the vertical and lateral <br /> extent of hydrocarbon impacted soil and groundwater. <br /> Initially,we propose to re-excavate the former UST area to remove any remaining impacted <br /> soil in the vadose zone. The re-excavation will be performed using a backhoe; samples will <br /> be collected from each sidewall. Since it is anticipated that groundwater will be encountered <br /> during excavation, no soil samples will be collected from the floor of the excavation. <br /> Upon completion of excavation procedures, three groundwater monitoring wells will be <br /> drilled and installed at the site. Samples will be collected at five-foot intervals and field <br /> screened using a photo-ionization detector (PID). <br /> 4.0 PROCEDURES <br /> 4.1 Re-excavation of UST Area <br /> For the excavation of impacted soil in the area of the former USTs, the following <br /> procedures will be performed: <br /> 1) Prepare a site health and safety plan in accordance with Occupational Safety and <br /> Health Guidance Manual for Hazardous Waste Site Activities (Prepared by National <br /> Institute for Occupational Safety and Health Administration, U.S. Coast Guard and <br /> U.S. Environmental Protection Agency, 1985). <br /> 2) Notify the San Joaquin County Environmental Public Health Services - <br /> Environmental Health Division (PHS/EHD) 48 hours prior to commencement of any <br /> work. <br /> 3) Excavate the contaminated soil using a backhoe. The approximate area to be <br /> excavated will be 10 feet by 15 feet. Assuming the removal of impacted soil to a <br /> depth of approximately 10 to 12 feet, the volume of soil that will be removed will be <br /> approximately 65 to 75 cubic yards. The proposed excavation limits are illustrated in <br /> Sr_".p1-1ft5 aL TU)0N CHURCH..pV1Ys <br /> 2 <br />