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30 April 1997 <br /> AGE-NC Project No. 96-0209 <br /> Page 2 of 5 <br /> 2.3. EXCAVATION OF HYDROCARBON-IMPACTED SOIL <br /> Between December 1989 and April 1990, approximately 2,500 cubic yards of hydrocarbon-impacted <br /> soil were removed from the former tJST area. In addition, approximately 3.500 cubic yards of <br /> "clean"overburden soil were also removed. I-lie soil was stockpiled east of the I_JS`I`site on property <br /> o%vned by Mr. Bill Fisk. <br /> Soil samples were collected intermittently Brom the walls of the excavation. TP11-- and BTE&X <br /> N ere detected in soil samples at concentrations tip to 5,350 ppm. Based upon results of the sidewal l <br /> samples, additional assessment and/or- excavation was required by the PIIS-F.,IID. Results of the soil <br /> samples collected during the excavations reinoval are surnmarired on Table 1, <br /> Ground Eater was encountered during excavation of hydrocarbon-impacted soil; soil samples <br /> collected at depths between 17 and 23 feet during excavation procedures. However, no (Trab -round <br /> water samples were collected from the excavation. <br /> 2.4. EXCAVATION BACKFILLING' <br /> t.'pon completion of excavation procedures in 1990, the excavation was backfilled to surface grade <br /> with clean, imported fill material. I'11e area � as then resurfaced with asphalt. <br /> 2.5. SOIL AEP-ATION AND SA'-1111_lNG <br /> Approximately 2.500 cubic yards of excavated soil was transferred into an aeration cell on the <br /> southern portion of the site . An authorization for the uncontrolled soil aeration was granted by the <br /> San Joaquin Valley Unified Air Pollution Control District (S,IVUAPCD). <br /> In order to determine the effectiveness of the soil aeration treatment lour composite soil samples <br /> were collected from the stockpiled Soil excavated from the former LISTS area. The samples %were <br /> analyzed for `111-1-g and B TF&K No detectable concentrations of petroleum hydrocarbons were <br /> presort in the soil samples analyzed. A copy of the laboratory report, location report and chain-of- <br /> custody are enclosed as Appendix A. <br /> 2.6. GROUND WATER DEPTH AND FLOW DIRECTION <br /> Accordin- to the San Joaquin County Flood Control and Water Conservation District map titled <br /> Lines cif equal Depth of Nater I41ells-Fall 1993,the-round water is approximately at 20 feet Mow <br /> surface grade (bs-). Regional ground water flow direction in the area is westerly. <br />