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} iF F Table 2 Analytical Results ii Soil Samples Beneath UST9,..'.July 1998 +: (mglkg) r 64 ,B•2 BA B-S BTEX ND ljND NO NO Total Petroleum Hydrocarbons ND IND ; ND ND Diesel Hydrocarbons NO !!ND 2.47 NO i MTBEND liND NO NO VOCs J . NO I iIND ND ND { 4.5 Waste Oil/Motor Oil Tank Filler Samples i URSGWC was directed by SJCPHS-EHD to collect sampjles from the pea gravel at the fillet to these tanks; Samples S-SWC}-01-01 (waste oil tank) andli S-SMO-01-01 were therefore collected. The waste oil tank sample was found to contain diesel hydrocarbons at 5.73 mg/kg, indicating that some spillage had occurred during filling. 4.6 Discussion of Results As previously mentioned, the USTs at the site were sitting on top,'jof.a 1-foot-thick concrete pad that could not be removed or sampled beneath at the time of the UST removal (see Appendix B, Photographs). Consequently,only piping and dispenser sarriples and soil stockpile samples could be collected-at the time of the UST removal, as directed by the SJCPHS-EHD representative. At the time of the removal, the SJCPHS-EHD representative recommended that the USPS submit a plan of action within 30 days, outlining how the soil samples would be collected from beneath the concrete pad. These samples were subsequently collected from beneath the concrete pad as outlined in Section 3.2.1. URSGWC considers the native soil under the USTs to have been adequately characterized by the ' four samples collected (13-1, B-2, B-4, B-5), which included samples from beneath both the unleaded gasoline and diesel tanks. The low-level diesel detection of 2.47 mg/kg (sample B4, under the unleaded gasoline tank) is not consistent with leakages of the diesel tank, since the samples under the diesel tank were non-detect for diesel and the other analytes (samples B-2 and B-5). Furthermore,none of the samples had any detects for TPH, BTEX or MTBE. The absence of leaking from the tanks is further supported by the results of;`the stockpiled soil sampling, which showed only one low-level diesel detection of 1.81 mg/kg, and the condition of the tanks upon removal. twktan VMF Construction 4luervation RWrt July Z7,.1999 Pose 9 i G -d [V0C-CN VN]Cvs 'd slit/ 0.Mv AV01 Nd11"0 0001 .1 . q8j.