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Forward Landfill WMU FU-23 <br />02778 14 HDPE GEOMEMBRANE <br />11. Weld only when ambient temperature, measured 6 inches above the geomembrane, is between 40 degrees Fahrenheit and 104 degrees Fahrenheit. 12. If the GEOSYNTHETICS CONTRACTOR seams at ambient temperatures below 40 degrees Fahrenheit and above 104 degrees Fahrenheit, then the GEOSYNTHETICS CONTRACTOR must demonstrate and certify that such methods produce seams which are entirely equivalent to seams produced at ambient temperatures above 40 degrees Fahrenheit and below 104 degrees Fahrenheit, and that the overall quality of the geomembrane is not adversely affected. In addition, a change order to the contract between the OWNER and the Installer is required which specifically states that the seaming procedure does not cause any physical or chemical modification to the geomembrane that will generate any short- or long-term damage to the geomembrane. Then, the temperatures in the above quality assurance procedure will be modified accordingly. 13. Seaming below temperatures of 32 degrees Fahrenheit must include preheating methods approved by the QA/QC CONSULTANT. <br />F. Defects and Repairs. 1. Examine all welds and non-weld areas of the geomembrane for defects, holes, blister, undispersed raw materials, and any sign of contamination by foreign matter. The surface of the geomembrane must be clean at the time of the examination. 2. Repair and non-destructively test each suspect location both in weld and non-weld areas. Do not cover geomembrane at locations which have been repaired until test results with passing values are available. <br />G. Extrusion Type of Welding. 1. Use procedures to tack bond adjacent panels together that do not damage geomembrane and allow CQA tests to be performed. 2. Purge welding apparatus of heat-degraded extrudate before welding. 3. Bevel top edges of geomembrane a minimum of 45 degrees and full thickness of geomembrane before extrusion welding. 4. Clean seam welding surfaces of oxidation by disc grinder or equivalent not more than 30 minutes before extruding weld. Change grinding discs frequently. Do not use clogged discs. 5. Do not remove more than 4 mils of material when grinding. 6. Grind across, not parallel to, welds. 7. Cover entire width of grind area with extrudate. 8. When restarting welding, grind ends of all welds that are more than 5-minutes old. <br />H. Hot Wedge Welding. 1. Place smooth insulating plate or fabric beneath hot welding apparatus after usage. 2. Protect against moisture build-up between panels. 3. If welding cross seams, conduct field test welds at least every 2 hours, otherwise, once prior to start of work and once at mid-day. 4. Bevel edges of top and bottom panels on cross seams. 5. Do not weld on geomembrane until equipment has passed trial weld test. 6. Extrusion-weld a repair patch over all seam intersections.