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As-Built CQA Report for the Construction of Area 2A at the Foothill Sanitary Landfill San Joaquin County,California • testing on extrusion welded seams, and spark testing for penetrations or other difficult areas not accessible for vacuum testing. The procedures for air-pressure testing consisted of the following: ■ Sealing the air-channel between the inner and outer tracks of the fusion weld; ■ Inserting a needle with an attached pressure gauge into the air channel; and ■ Inflating the air channel to at least 30 psi using an air pump and observing the pressure gauge over a period of five minutes. A pressure drop of more than 2 psi during this period indicates a possible leak or discontinuity in the seam. A vacuum box is a rigid-wall box with a clear Plexiglas top and a neoprene gasket around the bottom of the box forming a seal between the box and the HDPE geomembrane. Vacuum box testing was performed on the extrusion fillet seams and the procedure consisted of the following: ■ Cleaning the area to be tested of dust, debris, dirt,and other foreign matter; ■ Applying a soapy water solution to the seam; ■ Applying a vacuum of at least 5 psi to the inside of the box for 10 seconds; and • ■ Observing the seam for bubbles,which would indicate a leak or discontinuity in the seam. Spark testing utilizes a 24-gauge copper wire placed within 1/4-inch of the edge of extrusion seam or clamp seal and a low-amperage electric detector, 20,000 to 30,000 volt, with rod-type electrode capable of causing visible arc up to 3/4-inch from copper the wire. A spark observed when passing the electrode over the seam or clamp seal area would indicate a leak or discontinuity. When leaks or discontinuities were detected in the HDPE geomembrane seams, GBE repaired and re-tested the defective seams or discontinuities in accordance with the Project Specifications and as described above. Destructive Seam Testing During the seaming of 60-mil HDPE geomembrane panels, AES marked locations for obtaining test samples from the seams for destructive testing. The frequency of destructive test sample was one sample per approximately 500 linear feet of seam. GBE sampled 67 locations for destructive testing. Specifications called for each destructive test sample to consist of four, 1-inch wide by 12-inch long samples (2 strips from each end) for testing by the Contractor in the field and one 12- inch wide by approximately 44-inch sample for laboratory testing. Each laboratory sample was cut into three portions: one 12" x 18" sample for an independent laboratory, one 12" x 12" sample for • P:114 Projects114-101(SJCDPW North County and Foothillffoothill CQMReporffinal ReportToothill CQA Rport-Final.docx 27