ARCHIVED REPORTS_2017 - Laserfiche WebLink

Home Browse Search

2017 Corrective Action Evaluation Report-Austin Road Unit Forward Landfill a function of the types and age of waste in the landfill and the extent of the reactions that • produce various compounds from the anaerobic decomposition of waste. As demonstrated by the results of the TO-15 testing, the NMOC concentrations in LFG vary across the landfill from well to well. The concentrations varying from point to point with no distinct pattern is consistent with the expectations for the heterogeneous environment of an MSW landfill. The second semiannual 2016 TO-15 sampling event demonstrated that NMOCs were present in the LFG extraction wells, consistent with expectations for an MSW landfill. In the event of an uncontrolled release, there is the potential for LFG to impact the unsaturated zone; however, perimeter LFG probes have been installed in accordance with Title 27 of the California Code of Regulations and demonstrate continued compliance with the requirements. In addition, the combined LFG collection system, the Ameresco landfill gas-to-energy plant and the Forward LFG flaring system are operating at 75%of full capacity and in compliance with regulations. The LFG collection and combustion system is upgraded on a routine basis to optimize LFG collection. The potential for LFG impacts on the unsaturated zone are therefore being mitigated through source control measures. In accordance with the Point of Compliance LFG Monitoring Program, Forward will begin installing_additional perimeter monitoring probes around the Austin Unit to evaluate the effectiveness of the existing LFG extraction system in August 2017. If it is determined that additional mitigation is needed, or if impacts are observed, the LFG collection system can be increased to extract additional LFG. In conclusion, the existing system is optimized to maintain continued compliance with both State and Federal Air standards, but if site conditions change, or impacts are observed, the current system has back up capacity to • maintain compliance and continue or increase source control measures, as needed. The gas collection and control system at the Forward Landfill complex currently includes 194 extraction wells, a flare for thermal destruction (Flare A-2), a backup flare (Flare A-1), and a methane gas recovery facility that generates electricity. Over the next year, Forward is scheduled to install additional LFG extraction wells. The Forward Landfill includes 27 perimeter landfill gas monitoring probes spaced 1,000 feet apart, pursuant to Title 27 of the CCR. These probes include multi-level monitoring of shallow and deep intervals. Several of the probes also include monitoring of a medial interval. Combined, the perimeter monitoring system includes 77 individual monitoring points. Thirteen of the 27 permanent probes are located around the perimeter of the ARU: GP-13 through GP- 25. These 13 probes comprise 39 of the complex's 77 individual monitoring points. ARU perimeter gas monitoring probes were monitored quarterly for methane, carbon dioxide, oxygen, balance gas, and static pressure. Quarterly landfill gas sample results for ARU, provided by SCS Field Services (SCS), are in Appendix C. Quarterly results are generally consistent from quarter to quarter at the ARU, and methane was not detected in any ARU perimeter monitoring probe above a concentration of 0.1%during the monitoring period. Given the lack of detectable methane above 0.1% in the Title 27 perimeter gas probes over the past year, it can be concluded that the gas collection system continues to operate effectively. Forward will continue to enhance the landfill gas extraction system through regular maintenance and adjustments of the LFG well field by SCS. In addition, as presented above, • Project No 5017.1030 12017 Corrective Action Evaluation Report-Austin Road Unit 4 Forward Landfill