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® CLs for nonstatistical COCs, including VOCs, other organic COCs, and dissolved metals not detected in background, shall be equal to the method detection limit (MDL). Concentration limits are updated semiannually, where possible, and were most recently updated in this semester (Table 1). Interim CLs Fourteen out of 25 dissolved metals were identified as statistical COCs, based on available historical monitoring data from upgradient well MW-1. Interim statistical CLs for these constituents have been estimated. Concentrations of the remaining 11 dissolved metals were assumed nonstatistical COCs for setting interim CLs. Revised CLs Revised CLs shall be developed for general minerals and dissolved metals once additional background monitoring wells have been established per WDR and a sufficient amount of monitoring data have been collected for statistical determination of CLs A Mann-Kendall trend analysis of all monitoring parameters for MW-2 is conducted semiannually in accordance with WDR Order No. R5-2009-0049. The results of a statistical analysis of trends in VOC concentrations in well MW-2 are shown on Tables 1 and 2. Surface Water Concentration limits for surface water constituents are determined by the inter-well tolerance limit method using Sanitas software. Analytical results from the upstream monitoring point S-1 provide the background data for this analysis. Compliance is verified if current test result from monitoring point S-2 (downstream) is within the tolerance limit. Tolerance limits are updated when surface water analyses are available. MONITORING RESULTS Groundwater Summary The groundwater at all monitoring wells meet drinking water standards. The second semester sampling event was conducted on July 30, 2012. Quarterly groundwater elevations were measured at all groundwater monitoring wells on July 30, 2012 and October 9, 2012. One VOC (PCE) was detected in well MW-2 at a trace concentration during the second semester 2012 sampling event. One VOC (Acetone) was detected in well MW-4 during the second semester 2012 Sampling event. Two VOCs (CFC-12 and PCE)were detected in well MW-5. Note that MW-5 is upgradient from the landfill, but downgradient from the wastewater treatment ponds. ® Significant improvement in VOC concentration has been observed in well MW-2 with the non- detection of two chlorinated VOCs (CFC-12 and 1, 2-Dichloropropane) that indicated LFG impact. Harney Lane Sanitary Landfill 5 Department of Public Works/Solid Waste 2"d Semester and Annual 2012 Groundwater Monitoring Report County of San Joaquin—January 25,2013