COMPLIANCE INFO_JTD 9/3/2025 - Laserfiche WebLink

Home Browse Search

Foothill Sanitary Landfill 5 Department of Public Works/Solid Waste First Semiannual 2025 Groundwater Monitoring ©2025 County of San Joaquin. All rights reserved. In the spring of 2009, healthy vegetation was observed on the ET cap area. On June 10, 2009, CVRWQCB staff issued a notice of violation for discharge of wastes outside of containment due to the presence of VOCs in the soil within County property. Refuse was not discharged at those locations. On March 4, 2009, San Joaquin County staff noticed that the LFG condensate pump discharge was connected to the secondary leachate sump of Module 1 rather than to the leachate collection and removal system (LCRS). In April 2009, the LFG condensate was removed from the secondary sump, and the soil gas trench (installed beneath the liner of Module 1) was activated to enhance the protection of groundwater. An investigation in October 2009 indicated that the condensate had been forced between the primary and secondary liner up the side of the landfill, and had been discharged a few feet below ground surface into the anchor trench along the side of the landfill where the primary and secondary liners terminate. In March 2011, the continuing removal of liquid from the secondary sump, including increased removal during a high-water level event in the primary sump, indicated hydraulic communication between the primary and secondary sump. In October 2011, as agreed by District staff, the County installed an automatic pump in the secondary sump to maintain the liquid head above the liner below 12”, in accordance with CCR Title 27. This pump continues to operate. In December 2011, the County replaced LFG extraction well GX-2 with well GX-2A, and upgraded the LFG collection piping, which included an increase in the LFG pipe size, to increase the collection rate from wells GX-7 and GX-9. VOCs were again detected in MW-3 in the first quarter 2011, approximately five years after placing the impermeable barrier. This was the first VOC detection in MW-3 since the fourth quarter of 2001. No other wells were impacted. The County submitted an EFS on August 25, 2014, followed by a Revised EFS on December 19, 2014. An Addendum to the Revised EFS was submitted on July 17, 2015 proposing the installation of five tri-level soil gas probes and eight LFG extraction wells. The CVRWQCB approved the Addendum entailing that scope of work in a letter dated July 27, 2015. In November 2016, a Well Installation Report was submitted to the CVRWQCB that described the installation of five (5) tri-level soil gas probes (SG-2A, SG-3A, SG-6A, SG-10A, and SG-11A) and eight LFG extraction wells in the summer of 2016. The tri-level soil gas monitoring probes were installed to determine the extent of LFG migration from the base of unlined LF-1. Four (4) LFG extraction wells (GX-10, GX-11, GX-12, and GX-13) were installed in Module “I” to control groundwater impacts caused by LFG migration from LF-1. Wells GX-10 and GX-11 were installed near well MW-3 to provide enhanced vacuum within the refuse mass in close proximity to MW-3 where VOCs had previously been detected. Four (4) additional LFG extraction wells