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UIRS <br /> Mr. Ross Atkinson <br /> Regional Water Quality Control Board—Central Valley Region <br /> May 20, 2011 Page 5 of 10 <br /> • Lead was detected within 30 of the 54 samples. For MW-1, lead was detected 8 of 18 events <br /> with the highest concentration of 0.0203 mg/L(4Q07). For MW-2, it was'detected 12 of 18 <br /> events with the highest concentration of 0.0823 mg/L (4Q08). For MW-3, it was detected 10 of <br /> 18 events with the highest concentration of 0.0239 mg/L (4Q06). <br /> • Manganese was detected within 45 of the 54 samples. For MW-1, manganese was detected 18 of <br /> 18 events with the highest concentration of 7.00 mg/L(4Q06). For MW-2 it was detected 18 of <br /> 18 events with the highest concentration of 5.08 mg/L(4Q09). For MW-3, it was detected 9 of <br /> 18 events with the highest concentration of 0.216 mg/L (4Q08). <br /> • Nickel was detected within 38 of the 54 samples. For MW-1, nickel was detected 18 of 18 <br /> events with the highest concentration of 0.0176 mg/L (4Q07). For MW-2 it was detected 18 of <br /> 18 events with the highest concentration of 0.0236 mg/L(2Q10). For MW-3, it was detected 2 of <br /> 18 events with the highest concentration of 0.00291)mg/L(4Q08). <br /> Table 4 summarizes the inorganic results. <br /> Arsenic Occurrence and Conjunctive Management in California(Saracino-Kirby, Inc., 2000)presents an <br /> evaluation of arsenic occurrence in California water sources and provides the following statement: <br /> "Based on the composite database (186 sampling locations within the Eastern San <br /> Joaquin groundwater basin),the average arsenic concentration was 11.6 ppb. As <br /> expected, arsenic concentration varied from well to well, with some concentrations <br /> exceeding 50 parts per billion (ppb)." <br /> The World Enterprises site is located within the Eastern San Joaquin area. <br /> Additionally, another site located within the Eastern San Joaquin area is the Defense Distribution Region <br /> West(DDRW) Sharpe site(also known by EPA as Sharpe Army Depot). Groundwater samples have <br /> been collected at this site and analyzed for metals. At the DDRW Sharpe site, all of the metals <br /> concentrations in groundwater were considered to be within the background concentration. The highest <br /> concentration of arsenic found in groundwater at the DDRW Sharpe site was 0.764 mg/L. The highest <br /> concentration of lead found at this site was 0.0427 mg/L. The DDRW Sharpe site is located <br /> approximately 4 miles south of the World Enterprises site. <br /> GROUNDWATER GOALS <br /> Potential groundwater goals had not been established for the World Enterprises site. Groundwater goals <br /> are established based on the potential receptors and the potential pathways. For the World Enterprises <br /> site, the potential receptors are humans and the potential pathway is primarily through ingestion. <br /> Regional Water Quality Control Board <br /> Unless designated by RWQCB, all groundwater in the region are considered suitable or potential suitable <br /> for municipal or domestic water supply, agricultural supply, industrial service supply or industrial <br /> process supply. Because RWQCB has not designated the potential beneficial use at the World <br /> H:A W processV25532\Worl dGnteipri se\ClosureA05201 l.doc <br />