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MONITORING WELL INSTALLATION WORK PLAN WKA No. 5279.02 January 30, 2004 Page 3 Based on the six most-recent quarterly groundwater monitoring events, first groundwater is encountered less than 10 feet below ground surface at the West Facility and approximately 18 to 20 feet below ground surface at the East Facility. Groundwater elevation data from the three monitoring wells at the site consistently show(calculated)groundwater flow towards the southeast. As noted by the RWQCB and others,however,the southeast flow direction is suspect and may be biased by the proximity of MW-1 and MW-2 to the wastewater ponds. We have reviewed San Joaquin County groundwater elevation maps(Lines of Equal Elevation of Groundwater,prepared by the San Joaquin County Flood Control and Water Conservation District) for spring 1999, fall 1998, and spring 1998 (the most recent maps available). The maps show regional flow towards the west-southwest. Monitoring Well Locations Based on possible westward to southwestward groundwater flow, we propose the installation of two new monitoring wells (MW4 and MW5) at the West Facility. The proposed locations are illustrated on Plate 2 and discussed briefly below. MW4 Northeast corner of the west facility for the purpose of monitoring upgradient for background groundwater quality, MW5 Southeast of the AIPS ponds for the purpose of monitoring up/cross gradient of the wastewater application area if groundwater flow is towards the west or southwest; downgradient monitoring if groundwater flow is toward the southeast. It is our opinion that, given the absence of wastewater application at the East Facility, sampling of monitoring well MW3 should be discontinued. The depth to groundwater would continue to be measured at MW3 during quarterly monitoring events. Scope of Work The scope of work will include the following: • Obtain Monitoring Well permits from San Joaquin County Public Health Services. `M WALLACE-KUHL 6 ASSOCIATES INC.