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TECHNICAL SPECIFICATIONS <br />a. For cross seam tees associated with fusion welding, CONTRACTOR shall patch panel <br />intersections consisting of three or more panels and extrusion weld to a minimum distance of <br />4 inches on each side of patch. The edge of the sheet shall be ground to a 45° angle prior to <br />welding. <br />b. Place a protective layer, e.g., insulting plate or fabric, beneath hot welding apparatus after <br />usage. <br />C. When subgrade conditions dictate, use a moveable protective layer directly below each <br />overlap of geomembrane that is to be seamed to prevent buildup of moisture between sheets <br />and prevent debris from collecting around pressure rollers. <br />d. Remove seaming sheets and excess geomembrane trimmed to provide required overlap. <br />3. Use conventional extrusion welding as a secondary method for seaming between adjacent panels <br />and as a primary method of welding for detail and repair work. <br />a. Purge heat - degraded extrudate from barrel of extruder under the following conditions: <br />i. Prior to beginning a seam. <br />ii. Whenever extruder has been inactive. <br />b. Place a smooth insulating plate or fabric beneath hot welding apparatus after usage. <br />C. Use clean and dry welding rods or extrudate pellets. <br />d. Complete grinding process without damaging geomembrane according to <br />MANUFACTURER'S instructions no more than one (1) hour prior to seaming operations. <br />e. Prevent exposed grinding marks adjacent to an extrusion weld. Do not extend exposed <br />grinding marks more than one - quarter (1/4) inch from seam area. CERTIFYING <br />ENGINEER may request that any and all abraded areas be covered with extrudate. <br />f. Extrusion weld all cross seam tees to a minimum distance of four (4) inches on each side of <br />the tee. <br />g. For extrusion welds, the edge of the top sheet shall be beveled by grinding the edge of the <br />sheet to approximately a 45- degree angle. Extrusion welds cannot be placed on previous <br />extrusion welds. <br />C. Seaming Procedures <br />General Seaming Procedures <br />a. Areas to be seamed shall be cleaned and free of moisture, debris, or any marking on the <br />geomembrane. <br />b. Use a flat board, a conveyor belt, or similar hard surface directly under the seam overlap to <br />achieve proper support if required. <br />C. Cut fish mouths or wrinkles at the seam overlap along the ridge of the wrinkle in order to <br />achieve a flat overlap. The cut fish mouths or wrinkles shall be seamed and any portion <br />where the overlap is inadequate shall then be patched with an oval or round patch of the <br />same geomembrane extending a minimum of six (6) inches beyond the cut in all directions. <br />d. Extend seaming to the outside edge of panels placed in the anchor trench. <br />e. Do not field seam without the seaming supervisor present. <br />D. Field Trial Seams <br />Trial seams shall be conducted at the beginning of each seaming period and within 30 minutes of <br />commencement of seaming, at the CERTIFYING ENGINEER'S discretion, and immediately <br />Geomembrane August 28, 2013 <br />02776.1 -11 Revision 0 <br />S \Projects \1550 - CC &V Field Spt CQA PSES Bldg \8 0 Project Engineering and Design \8 2 Specifications\PSES Pipe Rack Liner Extension Specifications \02776 1 Geomembrane docx <br />