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' INTERIM SOIL AND GROUNDWATER <br /> CORRECTIVE ACTION SUMMARY REPORT <br /> 8940 W Walnut Grove Road, Thornton, CA <br />' Soil from the old, clean, and potentially contaminated stockpiles that contained no BTEX <br /> constituents and less than 50 ppm TPHd or TPHg were used as fill material when the excavation <br />' was backfilled Impacted soil was transported to the contaminated soil pile along the site's <br /> western boundary and remains on site Analytical results of soil stockpile samples are presented <br />' in Table 5 Laboratory data sheets and chain of custody documentation are included in Appendix B <br /> Soil stockpile locations are shown on Figure 6 <br /> 1 <br /> 4.4 Interim Groundwater Remediation <br />' Between March 6, 2000 and March 8, 2000, approximately 40,000 gallons of contaminated <br /> groundwater was pumped from the excavation pit Into two 20,000-gallon portable storage tanks <br />' Water samples were collected from each of the tanks for profiling Analyses determined that the <br /> concentration of constituents of concern in one tank fell within levels acceptable to the <br />' Sacramento County Regional Wastewater Treatment Plant (SCRWTP) in Elk Grove, California <br /> The tank was emptied into tanker trucks and transported to the facility by Denbeste <br /> Transportation for disposal under a temporary discharge permit <br /> rContaminant concentrations in water remaining in the other portable tank were reduced by <br /> aerating the water with supplied air introduced through perforated piping An additional 20,000 <br /> gallons of water was removed from the excavation pit on March 20, 2000 and was also aerated <br /> with the ex-situ air sparging system After confirmation sampling determined that contaminant <br /> concentrations fell to levels acceptable to the SCRWTP, the remaining 40,000 gallons of <br />' groundwater pumped from the excavation was transported by Denbeste Transportation to the <br /> facility for disposal A copy of the temporary discharge permit issued by the Sacramento County <br /> Water Quality Division is included in Appendix C <br /> 4.4.1 Analytical Results of Groundwater Samples <br /> Analytical results of water samples collected during interim remediation activities indicated that <br /> contaminant concentrations in groundwater were substantially reduced by excavating impacted <br /> soil and removing 60,000 gallons of contaminated groundwater from the excavation For <br /> example, TPHg levels were reduced from 320,000 ppb (sample EXW 3/8/00) to 1,100 ppb <br /> G 1Data1GROUNDZE\MANSER\Reports\sodexsum doc 6 <br /> I <br />