ARCHIVED REPORTS XR0009184 - Laserfiche WebLink

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compounds(including benzene,toluene,ethylbenzene and total xylenes[BTEX] and methyl i tertiary-butyl ether [MTBE]) or polychlorinated biphenyls ' Subsequently, a geophysical (magnetometer) survey of a portion of the site was performed to locate potential anomalies(underground storage tanks[USTs] or other buried structures) I July 2002-Four exploratory trenches(T-1 through T-4)were excavated utilizing a backhoe and three soil probe borings were advanced at the site, the trenches were excavated at locations identified during the magnetic survey as possible USTs or buned structures ' Trenches T-1, T-2 and T-4 contained assorted waste material, soil samples from the soil borings did not contain detectible concentrations of petroleum hydrocarbons at the depths sampled Petroleum hydrocarbons and volatile organic compounds were detected in a grab ' ground water sample at concentrations of 270 micrograms per liter (µg/1) TPH-g, 2 6 gg/l toluene, 2 3 µg/1 ethylbenzene, 27 6 lig/1 total xylenes, 3 7 µg/1 napthalene, 1 1 µg/1 n- propylbenzene, 14µg111,2,4-tnmethylbenzene,4 1 µg/11,3,5-tnmethylbenzene and 12µg/1 n-butylbenzene, however, the detected concentrations of VOCs do not exceed the state of California Department of Health Services' (DHS) Maximum Contaminant Levels (MCLs) and Action Levels (Als) Analytical results of soil and grab ground water samples are presented in Tables 1 and 2, respectively • November 2002 - Two USTs (UST-1 and UST-2) were discovered during excavation of debris and hydrocarbon-impacted soil The two USTs were single-walled and appeared to be constructed of redwood with steel banding, the tanks were contained in separate brick vaults with concrete floors Each tank had an approximate capacity of 15,000 to 20,000 rgallons Upon discovery of the tanks, the San Joaquin County Environmental Health Department (EHD) was notified and the tanks were removed under permit Based on analytical results of soil samples collected from beneath the tanks, it appears that the tanks contained diesel TPH-d was detected in each of the soil samples collected from beneath UST-1 and UST-2 and in the stockpile soil sample at concentrations ranging from 1,400 ' mg/kg (UST-2) to 28,000 mg/kg (UST-1) None of the other target analytes were detected in the samples collected • May 2003 - one soil probe boring (PB-20) was advanced to a total depth of 45 feet bsg Analytes of concern were not detected at or above laboratory reporting limits in the two soil samples