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J CLOSURE REQUEST 5-31-94 Dual WEGE instruments, GC FID and GC PID, have confirmed that benzene, toluene and ethylbenzene are no longer components of the vapor streams . Confirmation vapor extraction influent samples were collected on January 10, 1994, prior to installation of the new vapor recovery wells and on March 23, 1994, 35 days of operation after the installation of the new vapor recovery wells (VSB13 , VSB14, VSB15) These samples were Chain of Custody delivered to MATRIX and AEN respectively, see Appendix C. The WEGE laboratory along with the confirmation analysis of MATRIX and AEN indicate the more volatile and mobile compounds of gasoline have been removed. Modeling has shown that these less mobile non-carcinogenic compounds have concentrations low enough to warrant being left in place . Monitoring of the ground water indicates that contaminated ground water associated with MW1 and MW5 has been remediated and meets the Title 22 and DHS standards . Ground water gradients, corrected for vacuum influence, have shown potentiometric lows at the wells being used for vapor recovery (MW5) . Once the vapor recovery is shut off, normal flow directions again take place to the east-southeast or northeast, with the exception of the March 5, 1992 gradient, which flowed to the north-northwest and may represent a recharge and/or a decline in water usage of the municipal wells located east of the site. Fecal coliform has been analyzed for monitoring wells MW3 , MW4, MW5 and MW6 on a monthly basis from December, 1991 through February, 1992 . Only trace amounts of fecal coliform have been occasionally detected in any of the wells during those 3 months, see Table 2 RECOMMENDATIONS 1 Schedule a meeting to discuss closure monitoring and the need, if any for further remedial activities with CVRWQCB and San Joaquin County Health. 2 . Continue vapor extraction until the above mentioned meeting has taken place Well Destruction Once we are granted permission to close the site, we will schedule the destruction of all the wells associated with this site . County Health will be notified so that a representative of their department may witness the destruction. A mobile truck mounted drilling rig with 101, hollow stem augers will be used to remove all well material from the wells as specified in California Well Standards Bulletin 74-90, January 1990 A 12 sack mix of neat cement will be gravity poured through the augers (tremae pipe) and the augers will be staged out to insure page36