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ki ate engineering practices and published regulatory standards, suggests the following conclusions for each tank closure. -- 4.1 Tank T2 Based on the excavation tank bottom soil sample analytical results as discussed in section 2.1, there appears to be no need for further investigation or remedial action in the vicinity of the tank. The on-site stockpiled soils are discussed in Section 4.4. 4.2 Tank T3 While minor traces of both toluene and _PH were detected within the tank/pipeline excavation area, as discussed in Section 2.2, no regulatory standards appear to be exceeded. For toluene, the - California. Regional Water Quality control Board's (CRWQCB) designated level in a solid for the protection of groundwater is 100 mg/Xg. The toluene concentrations detected ranged from 0.035 mg/Kg to 0.32 mg/Kg. This range is two orders of magnitude less than the allowable level. Regarding the TPH levels, both the Leaking Underground Fuel Tank Manual and the California Regional Water Quality Control Board's b Staff Tri-Regional Recommendations recommend a "no further action required" level of 100 mg/Kg for diesel. The applicability of these recommendations is supported by the fact that the average minimum depth to groundwater is 581 . Therefore, with the trace concentrations of. TPH encountered, there appears to be no outstanding issues associated with the closure of the T3 tank and pipeline excavation. µ 4.3 Tank Tl As discussed in Secti4��n 2.3, only total lead was discovered in the excavation bottom soil samples taken from beneath tank T1. The concentrations detected were 61.3 mg/Kg and 54.2 mg/Kg. These levels are well below both the California Department of g_ Health Services (DOHS) total threshold limit concentration and the CRWQCB designated level in, a solid for the protection: of groundwater. These levels .are 1 g/Kg. 'and 500 mg/Kg respectively _ for lead. Also, the additional analysis for organolead indicated that for sample T1 west, no organic fractions of lead were present. Therefore, there appears to be no need for additional investigation or remediation in the vicinity of this tank. 4.4 Stockpiled Soils (Tank T2) Within the stockpiled soils at the sita, TPH concentrations exist un--to 1700 -m Kg -- - — discussed--in in---section-- -Based -on- preliminary sampling, the TPH concentrations appear to be limited to the southern half of the stockpil R TON Analytical Results, sample' ID n's_RS--ATE, RS-NW S-SE, RS-SW Appendix B) . CoQ /000 9 - ��