ARCHIVED REPORTS_2011_27 - Laserfiche WebLink

Home Browse Search

2-1 2.0 EXISTING ENVIRONMENTAL CONTROL AND MONITORING SYSTEMS 2.1 Landfill Gas Control/Monitoring System The FL has two active landfill gas extraction systems. One system consists of 18 wells and provides control for parts of the northern portion of the site. Landfill gas from this 18-well system is conveyed to the gas-to-energy plant located at the northwest corner of the site. A third party landfill gas developer, Covanta, currently operates the landfill gas-to-energy plant at FL along with the field of extraction wells. The developer collects gas sufficient to produce up to 760 kilowatts per hour of electrical power at the gas-to-energy plant. This power is sold to Pacific Gas and Electric Company (PG&E) under a long-term agreement. Additional gas extracted from the landfill is destroyed at the flare station in the northeast portion of the landfill. The second landfill gas extraction system encompasses the majority of the site, and consists primarily of 216 vertical gas wells. Approximately 24 of these vertical landfill gas collection wells are in the Stage 18 Partial Final Closure area. Landfill gas is collected through a perimeter gas collection header and is destroyed at the flare station located at the northeast corner of the site. The flare station consists of two enclosed ground flares located at the northeast comer of the landfill, with a combined capacity of 5,400 cubic feet per minute Wall). The FL has a landfill gas migration monitoring system consisting of 27 perimeter gas monitoring probes. Probes GP-13, GP-14, and GP-15 are located at the western perimeter of the Stage 1B closure area as shown on Figure 1 of the Perimeter Probe Monitoring Network Work Plan (SCS Engineers, May 2009),which is included as Appendix A. In 2008, the County of San Joaquin, Environmental Health Department determined that the spacing between probes GP-16 and GP-17; and GP-24 and GP-25 were both in excess of 1,000 feet, therefore, not in compliance with 27 CCR, Section 20925(b). In order for the FL perimeter probe monitoring network to be in compliance, an additional probe was installed between each of the probes (GP-16 and GP-17; GP-24 and GP-25). Therefore, two probes were installed - GP-26 and GP-27. The Perimeter Probe Monitoring Network Work Plan was prepared by SCS Engineering in 2009 to reflect the two additional probes. 2.2 Groundwater 2.2.1 Groundwater Monitoring Well The groundwater monitoring system at the FL is designed to detect the presence of contaminants in groundwater by analyzing groundwater chemistry at point-of-compliance wells. The monitoring system consists of 36 groundwater monitoring wells (not including 4 background wells), which meet the requirements of the landfill's Detection Monitoring Program (DMP) for groundwater monitoring and the Corrective Action Program (CAP) for groundwater contamination. The northern portion of the FL is currently under a CAP for groundwater contamination by ® volatile organic compounds (VOCs). To comply with the CAP, a groundwater extraction and Forward Landfill Stage 1B Partial Final Closure/Post-gosure Maintenance Plan-June 2011 SWT Engineering z:\projects\allled waste\forward\11-1014 partial fnl clsr pin\partial final closure plan document\text\sec 2.doc