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Mr.Nuel Henderson,SJCEHD October 17,2005 <br /> Site Investigation Work Plan <br /> Former Quick-n-Save Market&Gas, Stockton,California <br /> Page 2 <br /> BACKGROUND <br /> It is our understanding that an exploratory soil boring (B-1) was advanced immediately <br /> adjacent to one of the USTs in May 1998. Total petroleum hydrocarbons as gasoline <br /> (TPHG), benzene, and methyl tertiary butyl ether (MTBE) were reported at maximum <br /> concentrations of 11 milligrams per kilogram (mg/Kg), 1.94 mg/Kg, and 0.102 mg/Kg, <br /> respectively, for soil samples collected from the boring. A groundwater sample collected <br /> near the base of boring B-1 was also impacted with TPHG (8,790 micrograms per liter <br /> [µg/L]), benzene (1,950 µg/L), and MTBE (182 µg/L). The USTs and fuel storage and <br /> delivery system were removed from the property in January 2000. <br /> SCOPE OF WORK <br /> The objectives of the proposed work are to: <br /> • Further characterize the extent of petroleum hydrocarbon impact to soil and <br /> groundwater, <br /> • Characterize the geology beneath the site, and <br /> • Identify groundwater flow direction and gradient. <br /> To accomplish these objectives, Stratus is proposing the following activities: <br /> • Drill and install three 2-inch diameter groundwater monitoring wells (MW-1 <br /> through MW-3) to approximately 45 feet below ground surface (bgs) using 8-inch <br /> diameter hollow stem augers. <br /> • Collect soil samples in 5-foot intervals during the advancement of each boring. <br /> • Develop, sample, and survey the newly installed monitoring wells. <br /> Rationale <br /> Depth to groundwater beneath the K&S site has fluctuated between approximately 30 and <br /> 38 feet bgs since monitoring was initiated in 1998. Depth to groundwater was measured <br /> at depths ranging between approximately 33 and 36 feet bgs in June 2005. Proposed <br /> groundwater monitoring wells MW-1 through MW-3 will be installed approximately 10 <br /> feet below the anticipated current static water table surface. <br /> South-southeast groundwater flow directions have historically been reported at the K&S <br /> site. Given this anticipated groundwater flow direction, well MW-2 will be installed <br /> downgradient of the former fuel dispenser islands, and well MW-3 will be installed <br /> downgradient of the former UST complex. Well MW-1 will be installed near the former <br /> K1Quick-n-Save\Work Plans\quicknsave-wp-101705.doc STKATU5 <br />