COMPLIANCE INFO 2000-2009 - Laserfiche WebLink

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' + 0 September 11, 2000 50441 Mr. Vidal Pedraza San Joaquin County Public Health Service ' Environmental Health Division (PHS/EHD) Page 2 1 I 1 1 1 1 BACKGROUND Harding Lawson Associates During preparation activities for paving at the above referenced location, three 500 -gallon gasoline USTs were discovered. These three single -walled steel USTs (two whole and one partial) were originally located beneath a single dispenser island at a small, former, auto -repair facility that reportedly operated prior to the 1940's. Based on interviews with present and former Newark Sierra employees, the dispensers were no longer present in the early 1940s. When the USTs were partially uncovered during paving preparation, they were observed to be filled with sand and no product piping or vent lines were present. No residual product was present in the USTs. The USTs were severely rusted with numerous holes visible on the sides, ends, and tops of the USTs. Slight hydrocarbons odors were apparent in the native soil at the depth of the UST inverts and in the sand within the east and middle USTs. On April 27, 2000, HLA visited the Site to evaluate site conditions. To assess potential petroleum hydrocarbon concentrations within the sand inside the USTs, a sample of sand from each of the two intact USTs was collected from just above the tank inverts where the highest concentrations were likely to occur. These samples were submitted to a state -certified analytical laboratory for the following analyses: • Total petroleum hydrocarbons as gasoline (TPHg) with Environmental Protection Agency (EPA) Method 8260B, • Total petroleum hydrocarbons as diesel (TPHd) and total petroleum hydrocarbons as motor oil (TPHmo) with EPA Method 8015M, • Benzene, toluene, ethylbenzene, and total xylenes (BTEX); and methyl tertiary butyl ether (MTBE), with EPA Method 8260B. The results of these analyses are presented in the following table: Sample ID TPHg TPHd TPHmo Benzene Toluene Ethyl- Total MTBE benzene xylenes East Tank <1.0 1.0 11 <0.005 <0.005 <0.005 <0.005 <0.005 Contents Middle Tank 38 23 16 <0.005 <0.005 <0.005 <0.005 <0.005 Contents Units for all analytes are in milligrams per kilogram (mg/kg) These results indicate that BTEX and MTBE were not detected above normal reporting limits of 0.005 milligrams per kilogram (mg/kg). The maximum TPHg, TPHd, and TPHmo concentrations detected were 38 mg/kg, 23 mg/kg, and 16 mg/kg, respectively from the middle UST. Copies of the analytical reports and chain of custody forms are included in Appendix A.