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As-Built CQA Report for the Construction of Area 2A at the Foothill Sanitary Landfill San Joaquin County,California • 10.5 DRAINAGE STRUCTURES Construction of Area 2A included earthen drainage channels, two storm water basins and two drainage culverts. AES CQA Monitors observed the grading of the earthen channels and basins to check conformance with the plans and details. AES also monitored placement of pipe bedding, 80 cu. yds. of CLSM trench backfill, and earthfill cover for the 30-inch diameter corrugated metal pipe installed under the access ramp adjacent to the lined area.AES observed bedding and CLSM backfill placement to ensure trench backfill materials were placed to properly surround the pipe and without causing any damage. Two sets of cylinders of the CLSM samples were collected for compression testing. The 28 day compressive strengths were 160 psi and met the Specifications (150 psi minimum). The CQA Monitor also provided observation and testing of earthfill cover over the completed CLSM backfill section. The earthfill was placed with CAT D4 and D6 dozers and compacted by a CAT CP54 self-propelled sheepsfoot compactor. The backfill was moisture conditioned and compacted to 95 percent relative compaction based on ASTM D1557. Density test results for the earthfill are provided in Table 1. Observation during placement of rip rap, cushion geotextile, and turf reinforcement mats in the drainage channels was performed by County inspectors. 10.6 LEACHATE COLLECTION PIPING,PUMP AND CONTROLS • Area 2A construction included mechanical, electrical and piping to facilitate pumping of leachate to the existing leachate storage tank near the flare station southeast of Area 2A. The components of this work included: ■ A 5 hp submersible pump in the primary leachate riser; ■ An electronic water level sensor and bubbler in the primary leachate riser; ■ Bubbler water level sensors in the secondary leachate and lysimeter risers; ■ Below grade force main and a spare force main for a future tank connection consisting of 4-inch diameter HDPE SDR 17 pipes; ■ Flow routing rack with a sample port, flow meter, pressure gauge, check valve,ball valve and strainer; ■ Below grade electrical power and signal wiring and conduit within trenches; and, ■ Electrical control panel. The County personnel performed the mechanical and electrical inspection. AES CQA Monitors provided monitoring of pressure testing of the force main segments as they were constructed. The force main was pressurized with water to 120 psi and monitored for pressure drop over 1 hour. • P:114 Projects114-101(SJCDPW North County and Foothiliffoothill CQA1ReportlFinal ReportToothill CQA Rport-Final.docx 36