ARCHIVED REPORTS XR0006449 - Laserfiche WebLink

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SUMMARY There has been no evidence of floating product or product sheen on the groundwater in MW1 since April 14 , 1992 and MW3 and MW10 since November 11, 1992 . The last evidence of product, as a sheen in the condensate recovery system, was on March 1, 1993 Vapor recovery has reduced the hydrocarbons in groundwater significantly since the May 25, 1990 sampling, see Table 1 On January 31, 1996 a sample of the water being treated by air strapping inside the "ConVault" was obtained for certified laboratory analysis This was accomplished to prove the suitability for dumping this cleaned water to the City of Stockton' s sanitary sewer . This water (800 gallons) was discharged to sewer on February 20, 1996 Since that time there has been no additional discharge to sewer. Bio-venting of MW8 was initiated on October 26, 1994 Sample results obtained of the groundwater at and near MW8 suggests that this weekly venting is beneficial an controlling the migration of the gasoline hyrocarbon plume . As of March 18 , 1997 an estimated 12093 1 gallons of gasoline range hydrocarbons have been removed from the soil and groundwater beneath this site The 12093 1 gallons consists of previously removed floating product (40 25 gallons) , condensation . from vapor extraction (48 75 gallons) , projected petroleum hydrocarbon vapor extraction-destruction using Thermal Oxidation (74849 pounds/6 25 = 11975 8 gallons) , projected petroleum hydrocarbon vapor extraction--adsorbtion using Activated Carbon (171 93 pounds/6 25 = 27 51 gallons) and venting of MW8 (4 . 91 pounds/6 25 = 0 79 gallons) No chlorinated solvents were detected in chromatogram comparisons of the vapor samples, "i .e . " 1, 2 , Dichloroethene (DCE) - retention time 2 079 minutes, Trichloroethylene (TCE) - retention time 3 023 minutes and Tetrachloroethylene (PCE) - retention time 3 75 minutes . In the past, water samples from MW1 and MW6 were tested using EPA method 8240 and were below detection limits for these compounds, see Update Status Report 21, September, 1993 Water samples obtained on March 4 , 1994 from MWl, MW6, MW9 and MW11 were tested using EPA Method 8010 and were below detection limits for these compounds Water and vapor samples obtained from MW1, MW6 and MW9 on April 19, 1995, were tested using EPA Metod 8260 All Priority compounds were below detection limits . WEGE changed the BACT from Thermal Oxidation (REMOX unit) to vapor phase Carbon Adsorption on March 6, 1996 This modification to the BACT was approved by San Joaquin Valley Unified Aar Pollution Control District on Mav 3 , 1995 Currentiv WEGE as conducting the weekly emission screening of the carbon units and LTT is continuing the weekly venting of MW8 PAGE 3 R603 UPDATE-47 04/03/97