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samples collected from beneath the gasoline and 'diesel tanks contained elevated levels of petroleum <br /> hydrocarbons The former gasoline tank pit was backfilled with crushed rock in September 1993 <br />' Analytical results are summarized in Table 4 and sample locations are shown on Figure 4 <br /> 4.1.1 Excavation of Diesel Tank Location <br />' On January 4, 1994, approximately 160 cubic yards of residual petroleum hydrocarbon contaminated <br /> soil was excavated from the vicinity of the former underground diesel storage tank Petroleum <br /> hydrocarbon odor and gray discoloration indicated that impacted soils remained in the area of the <br /> former diesel tank between approximately 3 and 8 feet below grade along the north wall where <br /> excavation was hnuted by California Street Excavation continued along the east, west and south sides <br />' of the pit, to a maximum depth of 14 feet until field evidence indicated that contamination was no <br /> longer present <br /> Following excavation, confirmation samples were collected under the direction of Ms Turkatte <br /> Laboratory analysis determined that no BTEX constituents were present in any of the confirmation <br />' samples collected from the former diesel tank pit (Table 4) TPHd (20,000 ppm) was reported in the <br /> sample from the north wall of the pit where excavation was limited by public easements Low levels of <br /> TPHd were also reported in the samples from the floor (2 8 ppm), the east wall (5 2 ppm), and the <br /> 1 south wall (1 9 ppm) TPHd was not detected in the sample from the west wall of the pit <br /> Due to the high levels of TPHd in the soli sample collected from the north wall of the pit, RESNA <br /> collected a second sample from the north wall on March 17, 1994 The second sample was analyzed <br /> by Sequoia Analytical for TPHd using EPA method 3550/8015 modified and for leachable TPHd using <br /> the Toxicity Characteristic Leaching Procedure (TCLP, EPA 35101352018015 modified) The sample <br /> 1 was labeled EP-HBEW-8 Analytical results confirmed the presence of elevated levels of TPHd <br /> (11,000 ppm) in the soil beneath Cahforrua Street However, only 0 24% was considered leachable <br /> Soil sample results are summarized in Table 4 <br />' 4.1.2 Excavation of Waste Oil Tank Location <br />' Approximately 15 cubic yards of soil were removed prior to sampling in the former waste oil tank <br /> location No olfactory or visual evidence of residual contamination was noted during over-excavation <br /> and, at Ms Turkatte's request, the pit was backfilled with the excavated soil Prior to backfilling, a <br />' floor sample was collected from approximately 9 5 feet below grade from the excavator bucket as <br /> described above The sample was submitted for analysis of BTEX utilizing EPA method 8020, TPHd <br /> 1 and TPHg utilizing EPA method 8015, total oil and grease utilizing SM5520 EIF, halogenated volatile <br /> organics (HVOs)utilizing EPA method 8010, polychlorinated biphenyls (PCBs) utilizing EPA method <br /> 8080, and cadmium, chromium, lead, zinc, and nickel <br /> 1 No BTEX constituents, TPHg, oil and grease, HVOs or PCBs were reported in the sample collected <br /> from the former waste oil tank pit TPHd (2 6 ppm) was detected The reported concentrations of <br /> chromium, nickel and zinc (14, 11 and 29 ppm, respectively) are well below TTLC levels established in <br /> w\95141knuwilyl4gr-1993 doc 3 <br /> r <br /> 1 <br /> SUTH <br />