ARCHIVED REPORTS_2014_2 - Laserfiche WebLink

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A"significantly increasing"trend is reported by the Sanitas program for EC, and TDS thisq uarter (Table 3). No VOCs were reported at this well this quarter. Other than false positives,no VOCs have been reported since Toluene was reported in 2005 when the well was first installed. These Toluene data indicate that this compound was probably introduced when this well was installed in 2003,but quickly reduced to "trace"in three quarters. Excluding probable contamination during well construction and compounds also found the QC blanks, no VOC has been reported in this well. Therefore,there has been no indication of impact from the landfill at this well. MW-7(Up gradient): Concentrations of all parameters were within established concentration limits where the limits could be determined (Table 2). No VOCs were reported at this well this quarter. VOCs were last detected in this well on April 23, 2004. These detections are believed to have been introduced during well construction, and do not indicate groundwater impact from the landfill. Surface water Surface water samples were not available during staff site visits this quarter due to lack of rain. Such samples were last collected on January 27, 2011. All concentrations of field parameters and constituents of concern were below established concentration limits where the limits could be determined. An upcoming revision of the Stormwater Pollution Prevention Plan will identify the Corral Hollow Landfill as a"non-discharge" site, after which upstream and downstream samples will no longer be taken from the Corral Hollow Creek. Unsaturated Zone Soil Pore Gas The Monitoring and Reporting program for the landfill requires semi-annual VOC testing by TO-15 analysis. Soil gas samples were collected on April 25, 2014, and are included in this report. The concentrations of major gasses recorded during this TO-15 sampling event are also included. Before sampling,the concentration of major gasses (Methane, Carbon Dioxide, and Oxygen) and pressure were measured using a CES-LANDTEC GEMTm2000 portable gas detector. The GEMTm2000 was operated until a steady-state gas composition indicated that the well was purged and ready for sampling. Soil gas samples were collected in 1-liter Summa canisters and sent for VOC analysis by EPA method TO-15. VOCs were detected in all ten soil gas samples as shown on Table 4. Corral Hollow Sanitary Landfill 17 Department of Public Works/Solid Waste 2nd Quarter 2014 Groundwater Monitoring County of San Joaquin—July 15,2014