ARCHIVED REPORTS_2012_1 - Laserfiche WebLink

Home Browse Search

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 first semester sampling event was conducted on January 19, 2012. Quarterly groundwater elevations were measured at all groundwater monitoring wells on January 19, 2012 and June 5, 2012. Two VOCs (Benzene, and Toluene) were detected in well MW-3, although Toluene was also detected in quality assurance samples. These compounds are not generally associated with landfill gas and two VOCs (Dichlorodifluoromethane and Tetrachloroethene) 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 three chlorinated VOCs (PCE, CFC-12 and 1, 2-Dichloropropane) that indicated LFG impact. This is a significant improvement since 2007, when all three compounds were consistently reported at well MW-2. With the exception of Turbidity in MW-3 and M -4 and Chloride in MW-5 (downgradient from the wastewater treatment ponds), no concentration limits, where concentration limits could be determined, were exceeded in any wells during the first semester 2012 sampling event. r Harney Lane Sanitary Landfill 5 Department of Public Works/Solid Waste 1t Semester 2012 Groundwater Monitoring Report County of San Joaquin—July 31,2012