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CLOSURE REQUEST 5-31-94 UPDATE STATUS REPORT #28, MARCH 23, - MAY 25, 1994 . INTRODUCTION This report includes the results of events occurring at this site from March 23 , 1994 Through May 25, 1994 . LOCATION Regal Station 604 (parcel # 139-020--08) is located at 1448 N. El Dorado and Harding Way, Stockton, San Joaquin County, California. The site is in pro3ected section 2; TiN, R6E; MDB&M at approximately 14 feet above mean sea level Initial drilling (November, 1989) encountered ground water at approximately 32 feet below sea level (47, below the surface) and flowing in an east to southeasterly direction, see Figures 1, 2 , and 3 . SITE ACTIVITIES WEGE personnel visited and/or monitored the site on March 29, April 26 , May 19 , and May 25, 1994 The VES was operating at each visit with occasional shut down due to blowers reaching maximum operating temperatures Vapor stream samples were obtained from the influent and effluent at each visit , along with samples from selected vapor extraction wells, see Table 3 and Figures 5A through 5F Figure 5A represents total petroleum hydrocarbons as gasoline in the influent vapor stream, 3n mg/L. Likewise Figures 5C, 5D, 5E and 5F represent the influent measurements for Benzene, Toluene, Ethylbenzene and Xylenes respectively in mg/L These graphs show the decline and/or absence of the compound being tested for Figure 5B represents the percent of CO2 measured in the influent and likewise shows a steady decline On the April 26 , 1994 site visit influent and effluent samples were obtained and Chain of Custody delivered to American Environmental Network (AEN) DOHS certified laboratory #1172 for analysis using EPA method 8020/5030 , TPHg/BTEX Laboratory results indicated the absence Benzene and Toluene in the influent vapor stream with Dust above detection limits of Ethylbenzene (0 7 ug/L) , minor Xylenes (21 ug/L) and minor gasoline range hydrocarbons (0 48 mg/L) Again on May 25, 1994 , influent and effluent samples were obtained and Chain of Custody delivered to AEN The laboratory showed similar results in the influent vapor stream with the absence of Benzene, Toluene and now Ethylbenzene, with Xylenes at 15 ug/L and TPHg at 0 58 mg/L, see Laboratory Report - Appendix C Depth to ground water measurements were also obtained during the March 23, 1994 site visit and indicate that the predominate flow direction is to the northeast and a continuation of a recharge event is still occurring from the rainy season of winter of 1993/1994 , see Table 2 and Figure 4 . page30