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UNDERGROUND STORAGE TANK REMOVAL <br /> AT&T <br /> MICROWAVE RELAY FACILITY <br /> LODI,CALIFORNIA <br /> 6.0 CONCLUSIONS AND RECOMA ENDATIONS <br /> The UST and/or the piping system associated with the UST appeared to have released petroleum <br /> hydrocarbon product Into the soil on site Stained and odorous soil was observed in soil samples <br /> collected from the base of the UST excavation A visual inspection of the UST upon removal <br /> from the excavations found little indication of surface pitting, corrosion, cracking, or holes <br /> Moderate staining and petroleum hydrocarbon odors were observed in the soil removed from the <br /> excavations <br /> Based on the laboratory analytical results, organic compounds were detected in the soil samples <br /> collected at the base of the removed UST and in all the soil stockpiles Confirmatory soil samples <br /> indicated the following <br /> • The UST excavation area soil had a maximum detected concentration of TPH-D at the <br /> south end of the UST at 4,900 ppm at a depth of 16 feet bgs (the maximum depth of the <br /> excavation) Elevated TPH-D concentrations were also found in the west and southwest <br /> ends of the excavation BTEX and MTBE were not detected in the UST excavation area <br /> . sail <br /> • Soil stockpile samples found TPH-D at a maximum concentration of 82 ppm to 2,800 <br /> ppm Ethylbenzene was detected at 0 13 ppm in stockpile soil sample ATT-SP-4 <br /> • Imported backfill soil had no detected concentrations of TPH-D or VOCs The metals <br /> concentrations were below regulatory guidelines and do not qualify the soil as a hazardous <br /> waste <br /> Based on laboratory analytical results and field observations, it appears that diesel fuel has been <br /> released into the soil in the vicinity of the former UST Diesel fuel impacted soil was present <br /> primarily at the southern and western ends of the UST excavation <br /> State of California action levels for TPH in the soil do not currently exist However, the California <br /> Regional Water Quality Control Board uses TPH concentrations to prioritize cases for review The <br /> priontization level for Total TPH in soil is 100 ppm This level for TPH have been exceeded by the <br /> results indicated above and the case will likely be prioritized for review Based on ATC's experience <br /> with similar sites, it is likely that the SJCEHD will require that a soil and groundwater <br /> investigation be performed in order to characterize the lateral and vertical extent of petroleum <br /> hydrocarbons in the vicinity of the former UST <br /> ATC Associates Inc 61059 0029 <br /> 7 <br />