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First Quarter 1993 Monitoring Report <br /> .' <br /> Western Stone Products,Tracy,CA <br /> Project No.W0195.00 <br /> Page 2 <br /> collected from the water stored in the Baker tank. The water in the Baker tank was again <br /> sampled on February 23. A disposable bailer was used to collect the sample from MW3. Purge <br /> logs are included in Attachment 1. <br /> The groundwater and Baker Tank samples were delivered to state certified RESNA <br /> Environmental Laboratories and analyzed for total petroleum hydrocarbons as diesel (TPHD) and <br /> benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA methods 3510/8015 and <br /> 503018020, respectively. No petroleum analytes were detected in the groundwater sample <br /> collected from well MW3. Low levels of ethylbenzene (2.0 µg/f) and xylenes (3.4 Icg1P) were <br /> detected in the January 26, 1993 Baker Tank sample. No petroleum analytes were detected in <br /> the February 23, 1993 Baker Tank sample. Table 2 summarizes analytical results. Attachment <br /> 2 contains laboratory data sheets and chain-of-custody documentation. <br /> RESPONSE TO DECEMBER 1993 CORRESPONDENCE <br /> In response to the above referenced correspondence your questions are outlined below: <br /> r ,rr 1. Characterize the extent of soil contamination left in place beneath the site maintenance <br /> -'=f shed; <br /> 2. Describe the treatment system and additives being used to bioremediate the <br /> groundwater being stored in the Baker Tank; <br /> 3. Submit a workplan to define the boundaries and extent of residual soil contamination <br /> and a soil disposal plan for the stockpiled soils on site. <br /> Following is a response: <br /> 1. Based upon data collected during excavation of the former tank area adjacent to the <br /> maintenance shed RESNA estimates the total volume of contaminated soil left in place <br /> to be approximately 100 cubic yards. This assumes an affected area of 450 square feet <br /> and an affected interval of 6 feet (5-11 feet below grade). The total estimated volume <br /> of soil left in place is based upon the theory that contamination in undisturbed soil <br /> peripheral to the former tank pit is symmetrical about an axis through the center of the <br /> tank pit, parallel to groundwater flow (Table 3 contains analytical soil data). Figure 3 <br /> depicts the contaminated soil left in place. The total estimated volume of benzene and <br /> TPHD calculated from the sum of the volumes estimated in each contamination zone are <br /> 0.0027 pounds (lbs.) or 0.05 fluid ounces and 3.6 lbs. (0.51 gallons), respectively (Table <br /> 4). <br /> 1 QMR1993.FNL <br />