ARCHIVED REPORTS_2014 - Laserfiche WebLink

Home Browse Search

8. Provide adequate illumination if welding operations are carried out at night, and night operations are approved by the OWNER. 9. Cut fishmouths or wrinkles along the ridge of the wrinkle in order to achieve a flap overlap. Extrusion weld the cut fishmouths or wrinkles where the overlap is more than 3 inches. When there is less than 3 inches overlap, patch with an oval or round patch extending a minimum of 6 inches beyond the cut in all directions. 10. Log every 2 hours: a. Temperature directly on the geomembrane surface being welded. b. Extrudate temperatures in barrel and at nozzle (extrusion welder). C. Operating temperature of hot wedge (hot wedge welder) and any pressure adjustments made. d. Preheat temperature. e. Speed of hot wedge welder in feet per minute. 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. F. Defects and Repairs. I. Examine all welds and non-weld areas ofthe 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. 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. Forward Compost Facility Stormwater Improvements 02778 13 HDPE GEOMEMBRANE