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nonstatistical CDCs, including VOCs, other organic CDCs, 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 CDCs, 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 CDCs 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. Note that surface water samples are no longer being collected because the landfill is separated from Waters of the State by drainage system and a retention pond. Samples will be taken from pond discharge if it were to occur. Pond discharge requires manual operation of discharge pumps. MONITORING RESULTS Groundwater Summary The groundwater at all monitoring wells meet drinking water standards. The first semester sampling event was conducted on February 1, 2013. The first semester resampling event was conducted on March 1, 2013. Quarterly groundwater elevations were measured at all groundwater monitoring wells on February 1, 2013 and April 4, 2012. In the first semester 2013, several compounds, many of which are BTEX (benzene, toluene, Ethylbenzene or Xylene) were detected. Volatile compounds associated with landfill gas were detected at , well MW-3 and well MW-5 . Note that MW-5 is upgradient from the landfill, but ® downgradient from the wastewater treatment ponds. Harney Lane Sanitary Landfill 5 Department of Public Works/Solid Waste 1"Semester 2013 Groundwater Monitoring Report County of San Joaquin—July 15,2013