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09 July 1998 <br /> AGE-NC-97-0326 <br /> Page 2 of 6 <br /> The installation of ground water monitoring wells was subsequently required by the San Joaquin <br /> County Public Health Services - Environmental Health Division (PHS-EHD). <br /> According to a map titled Lines of Equal Elevation of Groundwater-Spring 1996,published by the <br /> San Joaquin County Flood Control and Water Conservation District, ground water occurs at a depth <br /> of approximately 55 feet bsg with a flow direction toward the northeast. The most recent data <br /> collected from ground water monitoring wells located at the USA gasoline station located east of the <br /> subject property confirms the gradient data with a slight increase in ground water elevation. <br /> 3.0. SCOPE OF WORK <br /> 3.1. DRILLING AND SAMPLING <br /> The scope of work will include the advancement of one soil boring near the former USTs location <br /> to a total depth of approximately 60 feet bsg, collection of soil samples, and installation of one 2- <br /> inch diameter ground water monitoring well. One additional boring will be advanced near the <br /> southern dispenser island to a depth of approximately 25 feet bsg. The soil borings will be advanced <br /> utilizing a truck-mounted drill rig equipped with 8-inch diameter hollow-stem augers. The <br /> monitoring well will be installed through the existing conductor casing. <br /> Soil samples will be collected at five-foot intervals beginning at a depth of 15 feet bsg in the boring <br /> adjacent to the UST and beginning at a depth of 5 feet bsg in the boring near the dispenser island. <br /> Soil samples will be preserved and placed in a chilled container for transportation to a state-certified <br /> laboratory under chain-of-custody. Soils will be described using the Unified Soil Classification <br /> System(USCS). Soil sample descriptions and PID screening results will be summarized on boring <br /> logs prepared for the final report. <br /> 3.2. EQUIPMENT DECONTAMINATION <br /> All sampling tools and brass sleeves used for sample collection will be thoroughly rinsed with clean <br /> water after washing with a solution of Alconox. All hollow stem augers will be steam-cleaned prior <br /> to advancement in each borehole. <br /> 3.3. MONITORING WELL COMPLETION <br /> The boring near the UST will be completed as a 2-inch diameter ground water monitoring well with <br /> the screened interval extending from approximately 60 to 40 feet bsg. If impacted soil near the <br /> Advanced GeoEnvironmental,Inc. <br />