ARCHIVED REPORTS_2009 - Laserfiche WebLink

Home Browse Search

4:k LGeoLogic Associates Geologists, Hydrogeologists and Engineers July 29, 2009 JN: 2009-0018 Mr. Ross Atkinson Central Valley Regional Water Quality Control Board 11020 Sun Center Drive, #200 Rancho Cordova, CA 95670-6114 SUBJECT: JANUARY—JUNE 2009 FIRST SEMIANNUAL WATER QUALITY MONITORING REPORT FRENCH CAMP LANDFILL SAN JOAQUIN COUNTY, CALIFORNIA On behalf of Forward, Inc. (Forward), Geologic Associates is pleased to submit the January through June 2009 semiannual monitoring report for the French Camp Landfill, in compliance with the California Regional Water Quality Control Board- Central Valley Region (RWQCB) Waste Discharge Requirement (WDR) Order Number R5-2007-0046. This report summarizes standard observations and presents the results of surface-water, groundwater, and soil-pore gas monitoring from January 1 through June 30, 2009 (monitoring period). A summary of analytical results and time-series concentration plots for field and monitoring parameters are also included in this report. A description of field procedures and sampling protocols followed by personnel conducting field monitoring activities is included in Appendix B of the report. Groundwater quality conditions beneath the French Camp Landfill during the monitoring period are generally similar to those observed in previous monitoring periods. Concentration limits (CLs) were exceeded for one or more constituents in the samples collected from background well MW-6A, and compliance wells MW-9A, MW-913 and MW-10A. With the exception of the chloride concentration measured in the sample collected from well MW-10A, none of the constituents that exceeded a CL exhibited a statistically significant increasing trend during the monitoring period. Previous statistical exceedances for chloride and total dissolved solids (TDS) have been identified in samples from well MW-l0A and a no release demonstration for groundwater monitoring well MW-l0A (Herst, 2005) concluded that the French Camp Landfill has been impacted by saltwater intrusion and the elevated chloride and TDS concentrations measured in well MW-1 OA are believed to be the result of this condition and not the result of landfill-related impacts. Organic constituent results indicate chloroform was measured above the practical quantitation limit(PQL) in the sample collected from wells MW-6A. In response to the detection of chloroform, retest samples were collected from this well on June 30, 2009. The results of the retest samples indicate that chloroform was confirmed in both of the retest samples at similar concentrations above the PQL. Review of the historical database indicates that since 1995 chloroform has only been detected three times at three different sample points in on-site wells, while low levels of chloroform have been intermittently detected in background well 16885 W. Bernardo Dr., Suite 305, San Diego, CA 92127 Phone: (858) 451-1136 Fax: (858) 451-1087