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Monitoring Wall Abandonment Cloaure Report - <br /> 707 East Yosemite Ave-,Manteca,Calilornia <br /> In June 1993, Aegis conducted a subsurface investigation that included drilling three soil <br /> borings (SB-1 through SB-3) to 15 feet below tirade (bg) in the vicinity of the pump <br /> islands and UST basin (Figure 2). This investigation was prompted by the request of <br /> SJCEHD requesting soil borings around the of incl pipeline repair area to asses the <br /> presence of petroleum hydrocarbons. Soil sample analytical results indicated no <br /> petroleum hydrocarbons were present, except 0.008 ppm of xylenes at 15 feet bg <br /> adjacent to the western dispenser island (SB-1). <br /> Because of the xylenes detected in the soil boring investigation SJCEHD requested <br /> monitoring wells to asses groundwater conditions On August 13, 1993, Aegis conducted <br /> a subsurface investigation that included drilling three soil borings to 30 to 35 (bg) that <br /> were completed as 2-inch-diameter groundwater monitoring wells MW-1, MW-2 and MW-3 <br /> (Figure 2). On August 17, 1993 Aegis personnel monitored and sampled groundwater <br /> from the three wells. The results for the subsurlace investigation and monitoring were <br /> compiled in Aegis report, Groundwater Monitoring Well Installation Results Report, dated <br /> September 14, 1993. No petroleum hydrocarbons were detected in the groundwater <br /> samples. <br /> SJCEHD requested one more groundwater sampling event at least 30 days after the <br /> August 17, 1993 event to confirm the absence of petroleum hydrocarbons. <br /> On October 11, 1993, Aegis personnel monitor d and sampled groundwater from the <br /> three wells. The results of the monitoring event were compiled in Aegis' report, <br /> "Groundwater Monitoring Report", dated October 19, 1993. No petroleum hydrocarbons <br /> were detected in the groundwater samples. In a letter from SJCEHD dated <br /> October 27, 1993, SJCEHD stated that closure is warranted and pending well destruction <br /> a closure letter will be issued. <br /> SCOPE <br /> On December 29, 1993, Aegis personnel super ised the abandonment of wells MW-1, <br /> MW-2, and MW-3. Woodward Drilling Company removed the monitoring well boxes, <br /> pressure grouted the wells with a neat cement bentonite slurry, and finished them to <br /> grade with quick setting-concrete. Mary Meays of SJCEHD witnessed the well <br /> abandonment. <br /> Aegis requests a letter from the SJCEHD docurr enting site closure. <br /> 83-0420-RER 2 <br />