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As-Built CQA Report for the Construction of Area 2A at the Foothill Sanitary Landfill San Joaquin County,California ■ Collection of cylinders for compression testing of CLSM backfill for the riser section of the pipe. Field density tests using a nuclear gauge (ASTM D6938) of foundation layer portion of the trench backfill over the solid riser section were taken at a frequency of one test per lift. Density and moisture content tests indicated the backfill met the required minimum relative compaction of 90 percent based on ASTM D1557. Test results are included in Table 3. Geotextile conformance tests are reported in Section 6.4.3 of this report. Compressive strength results of CLSM samples are provided in Appendix E.7. 3.3 PAN LYSIMETER A pan lysimeter was constructed under the Area 2A leachate sump in the southeastern corner of the cell (see Sheet C-9 and C-10 of the Construction Drawings, Appendix D.1). The lysimeter was constructed in a 6-foot wide trench extending down the eastern slope and 10 feet across the bottom of the sump. The lysimeter trench excavation was performed using Hitachi 300 and CAT 320 excavators. To form a pan, the trench was lined with 60-mil HDPE geomembrane on the bottom and sides of the trench and extending 5 feet laterally beyond the edge of the trench. The liner was welded to conform to the trench and surrounding area geometry. The welded seams were tested by the spark method (ASTM D6365). To complete the lysimeter installation, the bottom of the trench across the sump was backfilled with foundation layer soil in 8-inch lifts using a Hitachi 300 excavator. The foundation layer soil lifts were compacted using a plate compactor. The 2-foot wide slot for the gravel and pipe was hand excavated through the placed foundation layer soil. The slot was lined with 8-oz geotextile and 6-inch diameter, SDR 11 HDPE perforated pipe was placed across the floor and 5 feet up the slope. Solid pipe extending to the top of the eastern slope was welded to the perforated section. The perforated section of pipe was backfilled with coarse gravel and wrapped with the geotextile. Granular backfill was used to backfill above the solid section of riser pipe. The granular backfill material was moisture conditioned and compacted using a plate compactor. The CQA activities during installation of the lysimeter included: ■ Review of MQC data and conformance tests of the 60-mil geomembrane to form the pan and 8-oz geotextile encasing the lysimeter gravel and piping. ■ Sampling and testing of delivered coarse gravel and granular backfill soil. ■ Observation of the installation,seaming and spark testing of the lysimeter pan geomembrane and backfilling the pan with foundation layer soil making sure that the geomembrane was not disturbed or damaged during placement operations. ■ Observation of the placement of geotextile, perforated and solid HDPE pipe. PA14 Projects114-101(SJCDPW North County and Foothiliffoothill CQAIReportTinal ReportToothill CQA Rport-Final.docx 12