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<br /> <br />Foothill Sanitary Landfill Page 23 of 52 San Joaquin County DPW - Solid Waste <br />Joint Technical Document Revised 01/05/2026 <br /> <br />side slopes, sloped at 1 percent towards a collection sump. In select instances, the slope of a <br />collection trench may be reduced to accommodate the tie in of the individual LCRS trenches <br />within a cell. This will allow the collected leachate to drain to one sump within the cell. This main <br />collection trench would typically be located at the toe of an excavation slope where the waste fill <br />over it is a near constant height. A constant height of waste over the trench produces consistent <br />normal stresses that reduce the likelihood of subgrade differential settlement. Thus, the <br />minimum slope will be maintained. <br /> <br />Within each collection trench will be a 6-inch diameter perforated High Density <br />Polyethylene (HDPE) pipe used to collect the leachate and transmit it to the collection sump. <br />This pipe provides a large cavity for leachate to flow freely to the sump. It also provides <br />redundancy in the overall LCRS system. If the pipe were to fail over time, the permeability of <br />the gravel drainage layer would suffice to transmit the leachate to the sump. <br /> <br />The sump of the LCRS will be constructed with a sideslope riser system. This sideslope <br />riser system allows for a pump to be placed into the sump area for ultimate extraction of the <br />leachate for disposal <br /> <br />5.5.3. Collection and Removal <br />The main leachate collection drains were sized to carry a minimum of "twice the <br />maximum anticipated daily volume of leachate," as required under 27 CCR 20340(b). This will <br />be achieved with a minimum cross-slope of 1.4 percent. The lateral collection drains will have a <br />minimum slope of 1 percent. A comprehensive construction quality assurance program was <br />developed that establishes criteria for proper grade control and spacing of lateral collection lines <br />during construction. The liner and LCRS for the landfill will be constructed in incremental <br />phases. All operational components of the LCRS within each phase will be in place prior to <br />refuse being placed in that cell. Each phase will be either independent or compatible with <br />preceding phases. <br /> <br />The leachate collection pipes are constructed with risers that extend to the perimeter of <br />the landfill. During the initial operations of each module, the risers will allow for camera or other <br />means of inspection. As the landfill expands, the risers that have been constructed at the