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As-Built CQA Report for the Construction of Area 2A at the Foothill Sanitary Landfill San Joaquin County,California • 7.0 LEACHATE COLLECTION AND REMOVAL SYSTEM 7.1 GENERAL A leachate collection and removal system (LCRS) was constructed atop the Area 2A composite liner system. The LCRS consisted of geotextile,gravel,and piping that required monitoring and testing in accordance with the CQA Manual. The LCRS on the floor section of the Area 2A composite liner consisted of the following components (from bottom to top): ■ 6-inch-diameter perforated HDPE SDR 11 LCRS floor collection pipe; ■ 24-inch diameter perforated HDPE SDR 11 secondary leachate sump collection pipe connected to solid risers; ■ 24-inch diameter perforated HDPE SDR 11 primary leachate sump collection pipes connected to solid risers; ■ 6-inch diameter perforated HDPE SDR 11 secondary leachate sump instrumentation pipe connected to solid risers ■ 9-inch thick, minus 5/16-inch GDM layer above geomembrane and surrounding the LCRS floor collection pipe network; ■ Minus 1-inch coarse gravel placed within the secondary and primary sumps surrounding the • LCRS sump collection pipes; and ■ 8-oz filter geotextile above the gravel drainage layer to act as a filter/separation between the GDM and the operations layer soil and between the sump gravels and overlying minus 1-inch coarse gravel within the sump area. 7.2 PIPING AND LCRS GRANULAR DRAINAGE MATERIAL AND SUMP GRAVEL PLACEMENT The AES CQA Monitors observed the placement of LCRS materials including geotextile, LCRS pipes, LCRS granular drainage material and coarse gravel, and perforated and solid riser LCRS pipes. The perforated LCRS pipes on the floor were installed on a bed of 2 inches of GDM. The LCRS collection and riser pipes were joined by fusion welding. R.J.Gordon placed the GDM by taking precautions to avoid damage or inducing wrinkles to underlying geosynthetics. The gravel materials were transported to the site using highway bottom dump trucks. The GDM was unloaded immediately adjacent to the active placement area, and pushed by low-ground-pressure (LGP) track equipment (CAT D6 LGP bulldozers) onto the lined floor area. The piled gravel was pushed over geomembrane with the CAT D6 LGP bulldozers operating on no less than 9 inches of gravel. The thickness of the gravel layer was checked by AES using manual probing. Construction of the LCRS collection sump included placement of the secondary and primary sump • collection piping, coarse gravel and a separation geotextile between the upper coarse gravel and PA14 Projects114-101(SJCDPW North County and Foothillffoothill CQAIReport\Final ReportToothill CQA Rport-Final.docx 30