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June 1996 -4- 953-7001002 The TPH-containing soil was aerated on site, confirmation soil samples were collected and the excavation backfilled with the "non-detect" soil The four composrted soil samples were non-detect for TPHg and BTEX (WHF, 1991) March 1991 -A 12-hour aquifer pumping test was performed in MW-8 in March 1991 (WHF, 1991) March 1992-WHF drilled eight soil borings BX-1 through BX-8 to depths of 12 5 to 15 feet (Appendix A contains the analytical results) Maximum concentrations of BTEX were detected in soil samples from borings BX-1 and BX-3 at depths of 12 5 and 7 5,respectively The concentrations were 0 9 mg/kg benzene (B-1 at 7 5 feet),0 26 mg/kg toluene, 2 3 mg/kg ethylbenzene, 13 mg/kg xylenes,and (BX-3 at 12 5 feet) The maximum concentration of TPHg was 170 mg/kg also in the soil sample from BX-3 at 12 5 feet IFebruary-Marsh 19.93-WHF installed three groundwater monitoring wells MW-10,MW-11, and MW-12 downgradient of the suspected brine release area Groundwater samples collected from these wells were analyzed for total chromium content March 993-Based on the results of the analysis of soil samples from the eight soil borings drilled to the east of the 1991 excavation, an additional approximately 2,000 cubic yards of soil was excavated in March and April of 1993 (WHF,July 1994) In addition,approximately 22,000 gallons of groundwater was pumped from the excavation and disposed of offsite A total of thirty soil samples were collected and analyzed for TPHg and BTEX Two of the twenty-five soil samples (X-10 on the west side of the excavation and X-18 on the north side of the excavation were reported to contain detected concentrations of TPHg (15 and 24 mg/kg, respectively) The soil sample,X-10,also contained 0 07 mg/kg benzene, 0 28 mg/kg ethylbenzene, and 14 mg/kg xylenes Soil sample X-18 contained 0 29 mg/kg ethylbenzene and 0 17 mg/kg xylenes The excavation was expanded along the northwest side to excavate soil in the vicinity of X-10 Five additional confirmation sidewall samples were taken from the expanded excavation and they were non-detect for TPHg and BTEX December 1993-Levine-Fricke resampled groundwater from monitoring wells MW-5S, MW-7S,MW-10,MW-11, and MW-12 for dissolved total and hexavalent chromium No dissolved chromium was detected in the groundwater samples at the laboratory detection limit of 0 01 mg/L February through October 19 -At the direction of the SJCHD, three additional rounds of groundwater sampling and analysis were performed during 1995 Groundwater samples were collected from selected monitoring wells in February, May, and September 1995 The wells associated with the brine release(MW-10,MW-11 and MW-12) were also sampled and analyzed for TPHg and BTEX The results of all sampling events are summarized in Table 3 ' 9M7001 R01(713198) Golder Associates