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10 Af 1996 <br /> AGE- C Project No. 95-0108 <br /> Page 2 of 5 <br /> (bsg), Analytical results of soil samples collecteL' from the probings indicated the presence of <br /> petroleum hydrocarbons. However, laboratory detection limits for the soil samples were unacceptable <br /> by the PHS-EHD, <br /> Two additional soil borings were advanced at the site on 08 September 1992. Borings LCSB-1D and <br /> LCSB4-1 D were placed immediately adjacent to borings SB 1 and SB4 to obtain duplicate samples <br /> for analysis using acceptable method detection reporting limits for BTE&X. A PHS-EHD inspection <br /> report indicates that no hydrocarbon odors were noted in samples collected from the duplicate <br /> borings. However, analytical results of TPH-d for soil samples \vere not located in PHS-EHD t=iles. <br /> 2.5. EXCAVATION OF HYDROCARBON-I'yIPACTED SOIL <br /> �el <br /> Between FA1993 and April 1995, approximately _';2-16 cubic yards of hydrocarbon impacted- <br /> soil was excavated from the former UST area and was stockpiled nearby. TPH-d was detected in the <br /> sample collected from the westwall of the excavations at a concentration of 14,000 ppm. TPH-d was <br /> detected in sample from the southern end of the excavations at 7,600 ppm. The excavation has been <br /> backfilled with stockpiles from the site, under the authorization of the PHS-L--IID. Excavation of <br /> hydrocarbon impacted soil was summarized in a Site 4s.se.s.vnent Sununmy Repoi•l dated 2.0 March <br /> 1996 prepared by AGE. <br /> 2.6. STOCKPILED SOIL <br /> All excavated soil is presently stockpiled on-site. Results from the most recent sampling of the <br /> stockpiled soil, performed by AGE on 14 April 1995, indicates that petroleum hydrocarbons continue <br /> to be present in the soil. <br /> The soil is presently uncovered and aerating. However, because the primary contaminant in the <br /> stockpile soil is diesel (longer-chain hydrocarbons), it is unlikely that aeration alone will attain clean- <br /> up goals. <br /> 2.7, GROUND WATER DEPTH AND FLOW DIRECTION <br /> Based on the San Joaquin County Flood Control and Fater Conservation District map entitled Lines <br /> ofEclual Elevation in Water- Wells, Fall 1993, ground water depth at the site is approximately 55 feet <br /> below surface grade (bsg). Regional flow direction in the area of the site is west to southwest. <br /> However, flow direction can vary locally and with seasonal changes of ground water depth <br />