Method Statement

Geopoly Sdn Bhd are fully committed and focused on the Geomembranes and Geosynthetics Industry. It is Geopoly’s mission to ensure that our HDPE Geomembrane Plastic Lining Systems are the right choice for your requirements.

2.0 Panel Placement
Geomembrane panel placement shall take into account site topography, drainage, wind direction, sub grade surface, access to site and schedule of the project. Sufficient material slack shall be provided to allow for thermal expansion and contraction of the material. Panel deployment shall not proceed under adverse weather conditions, and panels seam are marked after deployment. The Site Supervisor, QA Technician or Independent Inspector shall visually inspect each panel, soonest after deployment and any possible damage areas to be marked for repair.

3.0 Unrolling Methods
Unroll geomembrane panels using methods that will not damage geomembrane and will protect underlying surface from damage by using a spreader beam and axle bar or a stationary unrolling stand or any other methods serving this purpose. The spreader beam is attached to the front end of the handling machinery. The spreader beam is constructed from steel I-beam or steel pipe and the axle bar is constructed of thick walled steel pipe. Spreader beam and axle bar shall be minimum one meter longer than the roll width.

The roll panels may be opened by placing roll on the ground and with the handling machinery pulling it. Or the panels are manually pulled while the handling machinery is stationary. In the absence of the handling machinery and spreader beam and axle bar, a set of unrolling stand may be fabricated, with the rolls placed on the stationary stand and the panels pulled manually. Vise grip or metal clamps are used to pull panel from the rolls, or pull cut panels into place and to align the overlap.

4.0 Ballast

Sandbags that act as ballasts are sufficiently spaced and placed on geomembrane to prevent wind drift. Proper footwear that will not damage the geomembrane liners shall be worn by all parties allowed on the liner. Smoking is prohibited on the geomembrane. Heavy vehicles are not allowed directly on geomembrane. Protect and cover geomembrane in areas of heavy traffic, from moisture, from theft or over long storage periods.

5.0 Field Seaming
Generally, seams are oriented parallel to the direction of maximum slope. Seams are minimized in corners, odd-shaped geometric locations and outside corners. A seam is considered a separate entity if it is the principal attachment that joins two or more panels.

6.0 Fusion Weld System
Geomembrane liners are welded by Fusion Weld method using a self-propelled hot air or hot wedge welding machine. The welder creates a fusion weld by heating the overlapped liner surfaces, with a pair of pressure rollers pressing them together while in molten state to result in a permanent bond. Seam overlap shall be consistent with the requirements of the welding equipment being used. For fusion weld a 4 inch (100 mm) overlap is a common standard.

7.0 Extrusion Weld System
Special detail fabricating areas such as sumps, pipe penetrations, concrete structures, fittings and accessories shall require Extrusion Weld process. Non-linear seams, roll ends, pipe penetrations, sumps, patches, corners or anywhere it is impractical to use a Fusion Welder are welded by Extrusion Weld method using an Extruder Resin or Extruder Rod Gun. This technique encompasses extruding molten resin between two geomembranes or at the edge of two overlapped geomembranes to effect a continuous bond. The extrudate rod or resin bead shall be made from similar type as the geomembrane.

8.0 Welding Equipment Operations
For all types of welding, the Installer Site Manager shall verify that the welding personnel are attentive and act professionally and all equipments are well maintained and functioning properly. Welding Technician must purge the Extruder machine of heat degraded extrudate for at least one minute prior to use. The surfaces to be welded are well abraded and clean.

Welding equipment has temperature monitoring devices to ensure proper measurement. Ambient temperature like cloud, moisture and hot sun will cause the temperature settings to vary. Occasional adjustment of the equipment may be necessary to maintain a consistent weld.

No seaming shall be performed in abnormal ambient temperature under adverse weather conditions that may affect the integrity of the liner installation. The high temperature limit for welding is the temperature at which the well being of the team is to be of concern.

9.0 Seam Preparation
The seam area shall be clean and dry, free of mud, moisture, dust, dirt, sand or debris and seam panels are overlapped properly for fusion welding. Seam surface area shall be abraded or grinded to rid of surface oxidation and tack weld for extrusion welding. Grinding is performed parallel to the seam and grinding marks shall not extend more than quarter inch outside the weld bead area. The Welding Technician shall ensure that wrinkles or fishmouths are minimized. During seaming, visual inspection and constant hand peel testing is practiced.

10.0 Trial Weld
The Installation QA Plan include routine trial weld at the beginning of each work day where small samples of liner for fusion weld are trial welded. Seaming equipments shall be warmed up for 15 minutes before performing trial welds. Trial welds assist to check and adjust welding equipment heating temperatures, roller pressure and variable speed controls, and to verify that the welding equipments are functioning properly. Seaming shall not proceed when ambient air temperature or adverse weather conditions jeopardize the integrity of the liner installation.
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Seams may be non-destructively or destructively tested. Non-destructive test field seams are performed using a vacuum box test or an air pressure test. These test operations are co-ordinated by the Site Supervisor in line with the project schedule for prompt identification of weld quality. The QA Technician shall ensure that any possible leak area detected is marked for repairs.

11.0 Defects and Repairs
The portion on the geomembrane liner marked for remedy may be repaired by patching; grind and reweld; spot welding; capping and topping, under dry conditions.