COMPLIANCE INFO_JTD 9/3/2025 - Laserfiche WebLink

Home Browse Search

Foothill Sanitary Landfill Page 24 of 53 San Joaquin County DPW - Solid Waste Joint Technical Document Revised 6/09/2020 Leachate will be pumped from sumps and returned to Subtitle D modules in accordance with the WDRs. 5.5.4. Vadose Zone Monitoring Sump Each of the LCRS sumps in the future modules will be designed with a vadose zone monitoring system below the primary LCRS sump acting as a leak detection system. The vadose zone monitoring sump will be excavated into the subgrade below the LCRS sump at the lowest point of the module floor. The vadose zone monitoring system will be localized in this area because the LCRS sump will be the only area where a potential constant head of leachate will be present on the liner system. Access to the leak detection sump will be via a sideslope riser pipe. The vadose zone sideslope riser pipe will be 6 in. diameter, HDPE SDR 11 pipe. The liquid (if any) in the vadose zone monitoring sump will be manually monitored on a periodic basis. Any liquids in the vadose zone monitoring sump will be removed with a pump via the sideslope riser pipe with the appropriate type and size pump. Containment in the vadose zone monitoring sump will be accomplished with the following components (Figure 5-5), from bottom to top: • Prepared subgrade • A geosynthetic clay liner (GCL) providing an hydraulic conductivity of no greater than 5 x 10-9 cm/s • 60-mil thick HDPE, double-sided textured geomembrane • 12-inch thick vadose zone gravel providing a minimum hydraulic conductivity of 0.1 cm/s • Geotextile filter. 5.6. Drainage County will design and construct temporary surface water drainage features to control runoff and erosion as needed to control drainage as the landfill develops. Erosion will also be controlled by establishing vegetation. Final surface configuration will include drainage berms or benches to direct storm water away from refuse fill areas to the existing storm water facilities (Appendix B).