ARCHIVED REPORTS_2009 - Laserfiche WebLink

Home Browse Search

1.0 Surface Water Monitoring Surface water samples were collected by ATC Associates Inc. during the first quarter 2009 monitoring event from surface water monitoring points SW-1, SW-2, and SW-3. Upstream surface water monitoring points SW-1 in Walker Slough and SW-2 in French Camp Slough are sampled to provide background monitoring data. Surface water monitoring point SW-3 is downstream at the confluence of the sloughs. The Waste Discharge Requirements (WDRs) stipulate quarterly analysis for field parameters(pH, specific conductance, temperature, and turbidity) and monitoring parameters (bicarbonate, calcium, carbonate, chloride, magnesium, nitrate, potassium, sodium, sulfate, total dissolved solids [TDS], and volatile organic compounds [VOCs]). First quarter 2009 field and laboratory sampling results from surface water monitoring points are summarized on Table 2.1, along with the concentration limits determined from upstream data. The historical surface water data are presented in Appendix A. The data are graphed on time series concentration plots in Appendix B. The concentration limits were calculated from data collected through the first quarter 2009. Information on the development of the concentration limits can be found in the Fourth Quarter/Annual 1999 Monitoring Report, French Camp Landfill prepared by CH2M HILL in January 2000. The statistical analysis calculations are presented in Appendix B. A copy of the statistical analysis methodology is reproduced in Appendix C. There were no constituents that exceeded concentration limits at SW-3 during the first quarter 2009 monitoring event. Historical data from the surface water sampling points were evaluated for temporal trend using Sen's Slope trend analysis. Graphs of the Sen's Slope analyses are included in Appendix B. Only turbidity at SW-1, SW-2, and SW-3 exhibited an increasing trend according to the Sen's Slope analysis. As noted above, SW-1 and SW-2 are background surface water monitoring points, and trends in the surface water quality at these points are not indicative of an impact from the facility. Given that turbidity exhibits a statistically significant increasing trend at background surface water monitoring points SW-1 and SW-2,the increasing trend in turbidity at SW-3 should be considered reflective of regional impacts and/or non-facility impacts. Total dissolved solids at SW-1 exhibited a decreasing trend according to the Sen's Slope analysis. There was only one VOC detected at surface water monitoring points during the first quarter 2009 monitoring event. Carbon disulfide was detected at SW-1 at a concentration of 1.3 ug/L. Carbon disulfide has previously been detected at surface water monitoring points, but has never been confirmed during a subsequent monitoring event. Soil cover has been placed over the waste material to prevent ponding of stormwater and to protect surface water. In addition, a perimeter ditch directs stormwater to a basin in the southeast corner of the site. A smaller ditch collects stormwater from the grinding area in the northeast corner of the site. Inspection and maintenance procedures for these stormwater control structures are provided in the site's Stormwater Pollution Prevention Plan. The facility reported that these control structures effectively directed storinwater from the waste material during the first quarter 2009. 2.0 Groundwater Monitoring Program Groundwater samples were collected by ATC Associates Inc. from two background monitoring wells (MW-6A and MW-7A) and four detection monitoring wells (MW-8A, MW-9A, MW-9B,