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b Discharge will be regulated under a NPDES permit. The NPDES permit application was ,,. submitted to the California Regional Water Quality Control Board (Regional Board) in February 1992. Permits for discharge will be obtained from the City of Tracy prior to any discharge. If groundwater extraction is not needed, these permits will not be obtained. Remediation Monitoring The efficiency of vapor extraction and treatment will be determined by periodic sampling of vapor from the wells, and at the inlet and outlets to the catalytic oxidizer. Sampling times and intervals will be specified in the San Joaquin County Valley Unified Air Pollution Control District permit issued for this site. The efficiency of the sparging and groundwater extraction and treatment system, if needed, will be determined from groundwater samples collected quarterly from all of the monitoring wells and depth to groundwater data collected quarterly from all monitoring wells. The treatment system operation and maintenance (O&M) procedures will consist of the following. Upon successful system start-up, a BC technician trained in O&M of remediation systems will visit the site biweekly. The technician will record flow rates, and pressure readings, test the backup system (sump and high level float switch), check the system for leaks, and adjust pumping rates (if needed). Any items noted that affect the system operation will be immediately repaired by the technician. If any such items cannot be immediately repaired, the system will be temporarily shut down until satisfactorily repaired. The technician will sample the treatment system inlet, between the GAC units, and the system effluent at a schedule agreed to by the City and the Regional Board. Typically, samples are collected approximately weekly for a month, then monthly following that period, unless the first month's sampling indicated a need for additional weekly sampling. The samples will be analyzed for TPH-G and BETX using U.S. Environmental Protection Agency (EPA) Methods 5030/8020 and 8015 Modified. Process controls include a high level switch in the sump containment area that automatically shuts down the entire system in case of a system leak. The system must be re-started manually. Each pumping well is equipped with level controllers that automatically start and stop the pumps based on water levels. Implementation Construction of the remediation system is anticipated to begin within 90 days of approval of this final remediation plan and upon issuance of the necessary permits. The plumbing, electrical, and general infrastructure required for groundwater extraction will be installed at the same time as the vapor extraction and sparge system. However, the granulated carbon vessels and groundwater pumps will not be installed until needed. 04/03+95+'\7403\RFPORTS17403A i.R•1 QMS.PS2000