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RESULTS OF INVESTIGATION <br /> The County suspects that the shallow aquifer is being recharged by highly mineralized surface water <br /> from Corral Hollow Creek. The County investigated the source in July and August 2003 by drilling <br /> at two locations, excavating by hand digging within the nearby Corral Hollow Creek bed, then <br /> sampling and testing the groundwater from these locations and from well MW-4. Only samples <br /> from one of the borings, TB-1 (which was converted to piezometer PZ-1), and from <br /> MW-4 were collected. MW-8 was dry and samples could not be collected from the creek bed <br /> explorations(TB-2 and TB-3)with hand tools. <br /> Testing of the collected samples included detection of fecal coliforms and analysis of TDS,pH, <br /> Electrical Conductivity, Turbidity, Chloride,Nitrate as N, and Sulfate (results in this Appendix). <br /> The source affecting the pH and Nitrate trends in MW-4 is inconclusive. Fecal coliforms were not <br /> detected in either TB-1 or MW-4 and the inorganic parameters were very similar in both,which is to <br /> be expected since the wells are separated by less than 100 feet. Since no data from three of five <br /> proposed sampling sites could be obtained,the investigation provided little useful information. <br /> The decreasing trend in pH and increasing trend in Nitrate at down-gradient well MW-4 was again <br /> indicated this quarter. Interestingly, MW-4 does not show an increasing trend in chloride,which is a <br /> common constituent in leachate and moves more quickly through the soil than nitrate. Increasing <br /> trends of other leachate constituents are also not indicated. <br /> Corral Hollow Landfill (_1 Department of Public Works/Solid Waste <br /> ' 4TM Qtr/Annual 2003 Groundwater Monitoring County of San Joaquin-January 28,2004 <br />