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Ms Elizabeth Thayer February 22, 1993 Page 5 5 The treatment system operation and maintenance (O & M) procedures will consist of the following Upon successful system startup, a Brown and Caldwell Consultants (BCC) technician trained in O & M of remediation systems will visit the site weekly 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 techrucian If any such items can not 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 Water Quality Control Board (RWQCB) 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 and BETX using EPA method 8015m/5030/8020. Process controls include a high level swatch 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. Pumping rates are described under item 2. 6 The extraction system is expected to capture the plume of hydrocarbon-affected groundwater. Exhabat C shows the anticipated capture zone achieved by pumping from TEX-1 at 10 gpm and ATR-2, 4, and 5 at 1 gpm. These results were obtained using the analytical groundwater flow model "Quickflow" (by Geraghty & Miller,Inc ). The model input parameters used to the analysis are as follows: hydraulic conductivity = 60 ft/day hydraulic gradient = 0 002 aquifer thickness = 23 feet average flow direction = N45E These parameters have been previously reported in quarterly reports and in the "Supplemental Site Investigation Report" dated March 5, 1991 (Brown and Caldwell) for this site The extraction system as not expected to have a significant impact on the regional hydraulic gradient 7. Extraction is expected to be needed for approximately 3 to 5 years The source of groundwater contamination as hydrocarbons in the vadose zone, specifically in the "smear" zone, or the zone within which the water table fluctuates. The source (hydrocarbons in Brown and Caldwell Consultants 722XTR