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in the Victor formation is unconfined. The groundwater monitoring wells sample water from the Victor formation. Most wells penetrate through the Victor formation into the underlying formations to obtain higher water quality and better flow characteristics. The Laguna formation of Pliocene age consists of stream laid sand and clay (3) . It contains discontinuous lenses of unconsolidated to semi-consolidated sand and silt with lesser amounts of clay and gravel . The boundary between the Victor and Laguna formation at the site is at approximately 150 ft. In the well drillers report log for the QAP plant wells included in the appendix, a clay layer approximately 100 ft thick is evident between 50 and 150 ft. Alternating layers of sand and clay below 150 ft are part of the Laguna formation. The Victor and Laguna formations constitute an upper aquifer system. The confining layer separating the upper aquifer from the lower Mehrten formation prevents hydraulic continuity between these systems. Groundwater Ouality Monitoring Program QAP installed three groundwater monitoring wells in August 1985 to comply with the Regional Board reporting program under Order 85-149. The monitoring wells terminate at approximately 90 ft. Free groundwater was encountered in each well at approximately 70 ft below existing ground surface. Monitoring well samples are analyzed quarterly. Resulting data is included in the appendix. Figure 2 shows the location of the three monitoring wells installed under Order 85-149. Water quality in the shallow groundwater samples obtained from the monitoring wells is characterized by a high nitrate content, indicating contamination from agricultural fertilizers. Table 1 shows average nitrate concentration and average conductivity data for the three monitoring wells. Table 1 WATER QUALITY PARAMETERS IN MONITORING WELLS Nitrate Conductivity Year m 1 (umhos/cm) 1985 69 1,070 1986 89 1,010 1987 74 1,100 1988 71 1,060 In addition to the monitoring wells installed in 1985 a domestic well monitoring program was established at the request of Edward Steffani of the Stockton East Water District. Five domestic wells in the immediate vicinity of the plant are sampled and a Title 22 chemical analysis is performed every quarter. Well locations for the domestic well monitoring program are shown in Figure 4. 1-6 RP033-L