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Ms. Dot Lofstrom <br /> Page 2 of 5 <br /> UST. The laboratory analytical results indicated total petroleum hydrocarbon (TPH) <br /> concentrations of 370 parts per million (ppm) and total xylenes at a concentration of 44 ppm. A <br /> second soil sample was collected at 14 ft below ground surface from the fill port end of the larger <br /> UST. TPH was detected at a concentration of 360 ppm and total xylenes were detected at a <br /> concentration of 58 ppm. <br /> On September 1, 1987, additional soil samples were collected from the former UST pit. The <br /> samples were collected using a backhoe at approximately the same locations as the initial samples <br /> collected during the UST removal, but at depths of approximately 16.5-ft bgs. Analytical results <br /> for the sample collected beneath the smaller UST were not available. Results for the sample <br /> beneath the larger UST indicated TPH concentrations of 2,000 ppm and total xylenes at a <br /> concentration of 1,000 ppm. <br /> On September 25, 1987, twelve soil samples were collected from a stockpile of soil removed <br /> during the tank removal. Four of the samples contained detectable concentrations of TPH. <br /> Laboratory analytical results indicated that one sample contained concentrations of TPH as diesel <br /> at 13 ppm. The other three samples contained concentrations of total petroleum hydrocarbons as <br /> gasoline (TPHg) ranging from 170 ppm to 1900 ppm. The stockpiled soil had been segregated <br /> based on the sampling locations and laboratory results. In October 1987 Mr. Jay Friedman of <br /> Valley Volkswagen and Mr. Ray Walker of Walker Hydraulics backfilled the UST pit with the <br /> stockpiled soil. <br /> In May 1995, Ground Zero advanced three soil borings (SBI, SB2, and S133) to approximately 46 <br /> feet bgs and installed monitoring well MW 1 to a depth of 62.5 feet bgs (see Figure 2). <br /> The soil samples collected from soil borings SBI, SB2, and SB3 did not contain detectable <br /> concentrations of TPHg, benzene, toluene, ethylbenzene, total xylenes (BTEX), or Oil and Grease, <br /> except for the 25.5-ft sample from SBI (0.010-ppm total xylenes). The soil samples collected <br /> from MW 1 (located in the center of the former UST pit) contained TPHg concentrations of 8,000 <br /> ppm and 8,800 ppm in the 20.5 ft and 30.5 ft samples, respectively. Soil samples collected from <br /> MW1 at the depths of 35.5 ft and 45.5 ft did not contain detectable concentrations of TPHg. <br /> Benzene was not detected in any of the soil samples. Oil and Grease was detected at <br /> concentrations of 230 ppm, 140 ppm, and 50 ppm in the 10.5 ft, 20.5 ft, and 30.5 ft samples, <br /> respectively. Soil analytical results from the initial investigation are summarized in Table 1. <br /> Low to moderate levels of TPHg and BTEX were reported in the initial groundwater sample <br /> collected from well MW 1. Subsequent samples did not contain detectable TPHg or BTEX but did <br /> contain low levels of methyl tert-butyl ether(MTBE). The MTBE may originate from the fuel leak <br /> at the adjacent property (601 E. Miner). Groundwater analytical results for MW 1 are summarized <br /> in Table 2. <br /> In July and November 1999 Ground Zero advanced four additional borings downgradient of the <br /> USTs and collected soil and groundwater samples for analysis. Results were submitted to <br /> PHS/EHD and RWQCB in the report entitled Subsurface Investigation Summary Report and <br /> Request for Case Closure (December 20, 1999). Analytical results of soil and groundwater <br /> va11eyvwlrepodslwkp1mn 2.doc <br />