SITE INFORMATION AND CORRESPONDENCE_1998-2000

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SUR • Newly installed A- and B-zone monitoring wells (MW-115A through MW-118A and MW-211B through MW-213B, respectively) were developed between February 16 and 17, 1999. Dedicated purge pump equipment was installed in all newly installed A- and B-zone monitoring wells (MW-115A through MW-I18A and MW-211B through MW-213B, respectively) during the week of February 21, 1999. • Indoor air samples were collected from four locations at Lincoln Center (Spaces 211, 505, 606 and 852) on February 22, 1999. Sample results will be used to evaluate potential health risks, if any, associated with possible exposure to certain Hazardous Substances detected in indoor air samples. Analytical results were forwarded to the RWQCB and LPL. Access negotiations continued with Bank of America to obtain permission to conduct remedial investigation activities on their property located at 503 W. Benjamin Holt Drive. • Monitoring of the operation of the Phase I Interim Remedial Action groundwater extraction and treatment system (GWETS), which includes routine sampling, automated measurement, and logging of the system flow rates and other operational parameters, continued throughout the bimonthly period. The treatment system operated continuously during the reporting quarter, except as noted below. The GWETS shut down on February 6, 1999 because of a failure of process pump P-2. The impeller of the pump was filled with scale and cemented to the pump housing. The pump was disassembled and cleaned on February 8, 1999 and the system was restarted that afternoon. • On February 10, 1999, the check-valve in well GEW-16 failed. As a result, the well discharged groundwater through a 1/4-inch hole in the broken valve, and some of the groundwater exited the extraction well vault. The well was turned off and the valve was replaced on the same day. The well was returned to service later that afternoon. • The following day, February 11, 1999, the GWETS was taken off line to replace the check valves in the other extraction wells. The valves were replaced on February 12, 1999 and the system was returned to service on the same day. • On February 27, 1999, the system was shut down because of a low-level alarm in tank T-1. The alarm was reset and the system was restarted on March 1, 1999. • On March 15, 1999, LFR turned off the GWETS as directed by the San Joaquin County Department of Public Works because the environmental insurance had been terminated. To date, the insurance has not been renewed and the system has remained off line. On March 16, 199, LFR verbally notified the RWQCB of the shut down. bimonthly-Apr99-0411 I.doc:blh 2