SITE INFORMATION AND CORRESPONDENCE FILE 1

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r � CLEARWATER G R O U P, I N C. Environmental se—ices Waste Disposal Approximately 10 55-gallon drums of purge water are currently stored at the site. Clearwater proposes to have all of the drums vacuumed out by a licensed hauler for disposal/recycling at an appropriate facility during the next quarterly groundwater monitoring event scheduled for mid-October 1996. Transport manifests and disposal/recycling receipts will be submitted with future correspondence. The PHS/EHD also noted that approximately 7,000 gallons of water were disposed of following December 1995 pilot testing; however only 4,300 gallons of water were generated during the constant discharge test on RW-1 (pumping rate of 5 gallons per minute (gpm) for 14.25 hours). This discrepancy is compensated by additional volume of water pumped from RW-1 during pilot testing. Following coi-npletion of the constant discharge test, the pumping rate from RW-1 was reduced to 4 gpm and allowed to continue at this rate for 8 hours, in order to keep the former uppermost saturated zone dry for the impending dual-phase groundwater and vapor extraction test. This accounts for an additional 1,920 gallons of water. The dual-phase test continued for an additional 2.25 hours at a pumping rate of approximately 6.5 gpm. This accounts for an additional 878 gallons of water. Thus, the total volume of water produced during the pilot testing was approximately 7,098 gallons of water. This value compares well with the 7,000 gallons shown on the manifest submitted to your offices earlier. Soil Contamination As requested by the PHS/EHD, analytical results for soil samples collected from borings drilled on December 14, 1987, for soil samples collected during underground storage tank removal on February 28, 1989, and for soil samples collected from MW- 2 and MW-3 on August 28, 1991 will be included in Table 1 summarizing soil sample analyses. The PHS/EHD indicated they will transmit a facsimile of these data to Clearwater, as these data are not in our files. Upon receipt of this information, Clearwater will submit a revised Table 1. The estimated contaminant .mass in soil was also questioned by the PHS/EHD. Clearwater originally estimated a contaminant mass in the soil of approximately 5,050 lbs. (--842 gallons). The PHS/EHD estimated a contaminant mass in the soil of approximately 137,200 lbs. (22,867 gallons) in correspondence dated May 23, 1996. As discussed previously in Clearwater correspondence dated June 5 1996, we felt the PHS/EHD estimate was excessive. It was also noted that such estimates are difficult, at best, to make with a great deal of accuracy. Ruiz.4491.W.DurhamFerry.Tracy.CA 2 September 17, 1996