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Staff Report: ACL Order for -3- <br /> Mr. Frank Guinta, Ms. Shari Guinta <br /> Mr. James Ramsey and Mrs. Marilyn Ramsey <br /> Frank's One Stop <br /> San Joaquin County <br /> 10,000-gallon gasoline USTs from the Site. During excavation, hydrocarbon odors were <br /> noted, and soil staining was observed in the excavation and photographed by SJCEHD. Soil <br /> and groundwater sample results confirmed the presence of TPHg, TPHd, benzene, and MtBE <br /> in the tank excavation. <br /> Between May 1999 and September 2000, Frank Guinta's consultant installed twenty <br /> monitoring wells (MW-1 through MW-20) and five piezometers (P-1 through P-5). Monthly <br /> hand bailing removed free product from two monitoring wells (MW-5 and MW-6) and one <br /> piezometer (P-4). Currently the off-site monitoring wells are located to the north within <br /> 200 feet of the Site, while the MtBE plume impacts to domestic wells extends over 600 feet to <br /> the north of the Site. Recently, water analyses from two domestic wells approximately 400 feet <br /> to the south of the Site have reported sporadic low level groundwater impacts from MtBE. The <br /> existing extent of the monitoring network does not adequately characterize vertical and lateral <br /> extent of the plume. CAO No. R5-2003-0713 requires that an adequate MtBE investigation be <br /> performed and additional monitoring wells be installed to characterize the vertical and lateral <br /> extent of the MtBE plume. <br /> From 1999 to 2002, the maximum concentrations of pollutants in groundwater were reported <br /> as: <br /> Constituent Maximum Concentration (Ng/L) Numerical Water Quality <br /> Limits /L <br /> Total Petroleum Hydrocarbons as 280,000 5 <br /> gasoline <br /> Total Petroleum Hydrocarbons as 70,000 100 <br /> diesel <br /> Benzene 1,500 0.15 <br /> Eth (benzene 4,500 29 <br /> Toluene 18,000 42 <br /> Xylenes 25,000 17 <br /> Methyl Tertiary Butyl Ether MtBE 8,100 5 <br /> Tertiary Butyl Alcohol 1,100 12 <br /> 1,2 Dichloroethane 1,2-DCA 1.1 0.4 <br /> Tetrachloroethylene PCE 26 0.06 <br /> 1 -Taste & Odor Threshold <br /> 2—California Public Health Goal <br /> s -California State Action Levels <br /> In August 2000, one groundwater extraction well and one air sparge well were installed to <br /> conduct a pilot study for the feasibility of using these technologies at the Site. <br /> In September 2000, one additional extraction well was installed, three piezometers were <br /> converted to extraction wells, and the groundwater pump and treat system began operating at <br /> the Site as an interim remedial action. <br />