SITE INFORMATION AND CORRESPONDENCE

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1�dw�ell&Rolb Ms. Kitty Walker 31 August 2000 Page 3 2. The report documenting the installation of the system, including soil boring logs, soil sampling and analytical data, and well construction details and pilot test check. 3. The system piping layout and process and instrumentation as-built diagrams. 4. Copies of required permits,including the San Joaquin Unified Air Quality Management District Permit to Operate(PTO), fire department, and municipal construction and electrical permits. 5. The SVE Operations and Maintenance manual. 6. Any other reports regarding the design or operation of the system. The treatment system began operation on 3 November 1999. However, after approximately 10 months of operation,we are not aware of any reports describing the operation, efficiency, or adequacy of the system. The following issues should be addressed: 1. Only three vapor samples are reported to have been collected for laboratory analyses during the first 5 months of operation. This is not sufficient to evaluate the efficiency of the treatment system. Additional samples should be collected at individual extraction wells and at the intake manifold to facilitate the performance of the system. 2. Table 7 of the 20 April AGE report summarizes organic vapor measurements using a photo-ionization detector(PID), flow rates, and vacuum measurements at individual wells. On all monitoring dates data is either missing or the well is labeled as closed without explanation. The missing data or its reason for omission should be given. 3. It also does not appear that site closure criteria,or the methods required to meet those criteria,have been established. These should be established, and a projected timeline to complete the remediation prepared. Common approaches include determining the asymptotic performance limit of the system, comparing the estimated mass of contaminants prior to remediation with the mass of contaminants removed by the SVE system, and running the system in Pulse-Mode Operation. Possible remedial confirmation sampling includes soil,water and soil gas sampling. At the current time, we cannot determine the risk associated with acquiring Areas 15 and 16. Resolving the issues described above will provide us with information on the likely future remediation activities required at the sites, and the cleanup goals that will be required to close them.