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�.. 1.01 <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> June 7, 1999 <br /> Page 2 <br /> 1,and three discrete soil samples were collected from Stockpile No. 2, for a total of eleven stockpile <br /> soil samples. Of these eleven stockpile soil samples, eight samples contained TPH-D levels ranging <br /> from 19 ppm to 40 ppm,with no detectable BTEX constituents. The three remaining stockpile soil <br /> samples (all from Stockpile No. 1) contained TPH-D levels of 150 ppm, 180 ppm, and 210 ppm, <br /> with no detectable BTEX constituents. <br /> The UST excavation cavity was backfilled by Bowen Construction-Engineering in late March. using <br /> clean fill from elsewhere on the Tiger Lines site. In order to allow compaction equipment access to <br /> the excavation cavity,a ramp was excavated on the west side of the former excavation cavity, in the <br /> area of the former dispenser island. This excavated soil,which amounted to about two cubic yards, <br /> was added to Stockpile No. 1. <br /> PROJECT APPROACH <br /> Based on both field evidence and soil analytical results, it appears that no significant releases <br /> occurred from the former USTs themselves, but that some releases occurred adjacent to the south <br /> side of the former fuel dispenser island. In addition, it appears that approximately 75% of the <br /> stockpiled soil generated during UST removal activities contains levels of TPH-D below 40 ppm, <br /> with no detectable BTEX. <br /> Some overexcavation of fuel-impacted soils in the former dispenser area was conducted to provide <br /> access to the UST excavation cavity during backfilling. In order to assess the effectiveness of this <br /> overexcavation,we propose to conduct soil sampling in the former south dispenser area using hand <br /> auger equipment. If results of this sampling show no significant levels of TPH-D and BTEX,then <br /> we would recommend that San Joaquin County Public Health Services grant regulatory closure for <br /> this UST site. <br /> Based on the overall low levels of TPH-D present in the excavated soil stockpiles,we propose to re- <br /> use of the stockpiled soil onsite. Using Table 2-1 Leaching Potential Analysis for Gasoline and <br /> Diesel Using Total Petroleum Hydrocarbons and Benzene, Toluene, Xylenes, and Ethylbenzene, we <br /> score the project site as having 44 points, based on: (1) Five points for depth to groundwater of 25 <br /> to 50 feet beneath soil sampling points; (2)Ten points for no fractures in subsurface; (3)Nine points <br /> for average annual precipitation between 10 and 25 inches;(4)Ten points for no man-made conduits <br /> which could increase vertical hydrocarbon migration; and(5) Ten points for no unique site features, <br /> such as recharge area,coarse soils,or nearby wells. With this scoring,the maximum allowable TPH- <br /> Diesel level which can be left in place at the site is 1,000 ppm. Based on this analysis,Tiger Lines <br /> proposes to use the soil for surface grading material for new construction anticipated on the recently- <br /> acquired nine-acre north adjoining property at 1000 East Turner Road. Once in place,this soil will <br /> be covered with either asphalt or concrete and will not pose a significant risk to potential human <br /> health or environmental receptors. <br /> GRIBI Associates <br />