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Ind <br /> 4. Summary Rd <br /> Quarterly groundwater level and quality monitoring of two identified aquifer zones(a shallow and a deep <br /> zone) commenced in 1994 and mining of the Lone Tree Il phase area commenced in 1998. Water level r <br /> data, collected semi-annually since 1960 by the California Department of Water Resources, are also <br /> available for one shallow zone well. <br /> MIN <br /> The extensive available shallow groundwater level record shows that water levels observed since 1994 are <br /> within the range of historically observed levels and relatively stable. Groundwater level elevations in the <br /> area of Teichert's Vernalis plant suggest predominantly southeasterly to northeasterly groundwater flow 01111 <br /> directions. Groundwater levels observed in the deep wells are typically lower than in the shallow zone, <br /> and exhibit greater seasonal and annual fluctuation than groundwater levels in the shallow wells. In the <br /> early 2000's,groundwater levels in the deep zone noticeably declined, likely in response to reported <br /> increased pumping of local deep irrigation and industrial production wells. In the mid 2000's,substantial d <br /> recovery of groundwater levels occurred. <br /> The groundwater quality record documents stable conditions in both the shallow and deep aquifer zones. <br /> Shallow groundwater is generally of Ca-Na/HCO3-Cl type and deep groundwater is of Ca-Na/HCO3-SO' <br /> type. The overall content of soluble minerals is slightly higher in shallow zone groundwater than in deep <br /> zone groundwater. Elevated nitrate concentrations in groundwater,documented since pre-mining times to <br /> the present, are most likely attributable to historical and ongoing agricultural land use in the area. In <br /> summary,the existing data record shows no indication that mining operations have changed groundwater <br /> quality to date. <br /> WIN <br /> IRII <br /> (MLU-00PIT S SCALMANINI <br /> 8 CCINSlLTING ENGINEERS IMI <br />