ARCHIVED REPORTS_2002_2 - Laserfiche WebLink

Home Browse Search

Consolidated Forward Inc. Landfill Page 19 Future design for the vertical expansion will, if necessary, include additional components in the liner system, depending on future differential settlement on the liner system. The extraction wells proposed as part of the Revised Engineering Feasibility Study (AEE, 2001B) will be maintained and monitored during combined landfill build -out phases, and modified as needed based on the RWQCB's review of monitoring data. The appropriate responsible agencies, the CIWMB and RWQCB, shall conduct a review of the liner and leachate collection system for the vertical expansion over the existing landfill(s) proposed in the JTD. 49 (F.6) Proposed as Part of the Project: Because of the potential for contamination from WMU B and/or A of the shallow groundwater table downgradient and adjacent to the project, existing domestic off- site wells within 500 feet of the eastern property boundary will be sampled at the same frequency as the monitoring wells onsite and for the same constituents (see CCR, Title 27). Final determination of the sampling program and the evaluation of the test results, along with the appropriate mitigation, is the responsibility of the RWQCB and must be carried out under their permit authorization. Identified in This EIR: Water quality at the offsite wells, such as the two private wells along Austin Road and the CYA wells, shall be monitored at least biannually (twice a year) to determine the extent that the plume impacts them. Continued operation of the groundwater extraction system at the site will help limit the contaminant plume from expanding in a downgradient direction but will not address the offsite component far beyond the boundary of Austin Road Landfill unless the contamination is attenuated and diluted over time or more extraction wells are brought on line per the AEE (2001b) Alternative 3 proposal. However, in their revised AEE (2002a) report the proposed alternative 11 is put forth as the only remedy to implement at this time. The RWQCB accepted alternative 11 in their letter to Forward dated March 11, 2002. If the groundwater VOC concentrations do not attenuate at a rate that is acceptable to the RWQCB then the Board will require that Alternative 3 - or some variant on Alternative 3 - be implemented. The recent (AEE, 2002a) addendum to the corrective action proposed procedures to analyze the hydrochemcial trends and trigger concentrations at which additional extraction wells would be considered. (Atkinson, 2002). 50 (F.7) Identified in This EIR: Two infiltration methods are currently used at the landfill. Most of the groundwater currently pumped by the former agricultural well is used onsite; thus, some of it will infiltrate through the unlined parts of the site and migrate back to the groundwater aquifer from where it was extracted. Secondly, the treated groundwater from the