INSTALLATION PROCEDURE OF HDPE GEOMEMBRANE
Detailed installation of the geomembrane step by step
In general, the Geomembrane Installer is not responsible for earthworks on a construction site. The general contractor is responsible for all preparation and maintenance of the surface to be covered by a layer of geosynthetic as well as that it is dry before be covered by said layer of geosynthetic. If you need to know more about applications of geomembranes in various industries we suggest you read the corresponding article in our blog too.
When a project does not have specific guidelines such as the preparation of a compacted ground must follow a “Quality Control and Assurance of Quality for Facilities Containing Wastes” according to the US-EPA. The surface should be as smooth as possible and should not contain puddles. water, debris, or other objects that may damage the geosynthetic layer. At the request of the owner and/or contractor’s representative, the installer will provide written approval of the compacted land. Bliss approval will be limited to the amount of compacted soil that has been covered during a specific job. The repairs that are made subsequently to the compacted ground and surface will continue to be contractor’s responsibility. An example of a Compacted Soil Acceptance Certificate form.
The anchor trench will be excavated by the earthmoving contractor. (unless otherwise specified) in depth and width according with the established design and prior to the installation of the geomembrane Sites where the geomembrane enters the trench must be free of irregularities, bumps, etc. To avoid potential damage to the material. Backfilling of the anchor trench will be the responsibility of the contractor for the earthworks following the pertinent specifications. the stuffing must be carried out at the moment when the geomembrane is in its normal state. higher shrinkage to prevent possible instability damage dimensional. Special care must be taken at the time of filling and compaction of anchor trenches to prevent damage to the geomembrane.
Placement of the HDPE Geomembrane
Before starting a project, a panel layout must be made showing the location of each panel of the geomembrane. This layout must presented for informational purposes only and is normally based on plans and project specifications. During the installation of the geomembrane, the panel placement may differ from the proposed layout. On the scale plan of the project will show the actual placement of the panel in the field. During the installation, the Installer QC Inspector collects all the information shown on the scale drawing. This scale drawing must show the panel location, panel identification, pipe penetration, repairs and locations of destructive tests.
A distinctive number must be given to each installed panel. the system panel numbering should reflect the actual manufacturer roll number followed by a letter showing the chronological order of deployment (example: 1-8522-A, 2-8522-B). Each panel is identified by its number both on the drawing to scale as well as physically on the panel using indelible marker (or spray when allowed).
During installation of the panel, care must be taken not to damage the geomembrane and/or compacted soil. So much walking on any geosynthetic material as well as traffic should be kept to a minimum. Someone should not be allowed to wear shoes that can puncture, scratch or cause any damage to the geomembrane by walking on it.
During panel placement, an anchor and ballast should be used to prevent a wind uplift of the geomembrane (sandbags or others). I know You must install the lining material (when applicable) as soon as it is complete installation, testing, and repairs on the geomembrane. This will greatly reduce the risks of wind uplift over a large area of installed geomembrane.
Geomembrane panels must not be unfolded or left unattended. sewing at night The geomembrane should not be deployed when the weather conditions are uncertain or not suitable for a seam in countryside. Extreme temperatures, high humidity, rain, etc. they are all unfavorable conditions for sewing in the field. The person in charge of the work and the QC Inspector must determine if the seam can be made properly so that quality seams are obtained.
In general, all seams should be oriented parallel to the slope, not traversed Related seams (perpendicular to slope) are not they must be located within 5 feet (1.5 meters) of the tip of the slope. The Quality Control Inspector will document all quality control procedures sewing using the Sewing Procedures form (A3) that can be found shows in the appendix. Field documentation of procedures sewing include sewing number, date and time of sewing, technical welder, length of the seam and a reference regarding the seam of corresponding test (calibration).
The welding device technician must ensure that the seam area is free of dust, humidity or any other object that could affect the quality of the sewing. All intersections in the Panel (“T” seams) shall be Extrusion welded to ensure a proper seal. with the frequency Whenever possible, the QC Inspector should cut a 1-inch sample wide (25 mm) at the end of the seams and then carry out a test of takeoff. If the sample fails, welding with the equipment must be stopped. appointed immediately. The QC Inspector will define the defective area and repair it properly. A new test seam will be required to Let the welding technician resume welding.
The main method used should be the hot wedge welder. East automatic equipment allows a higher welding speed as well as a more consistent welding method. Geomembrane panels are laps of five (125 mm) to six inches (150 mm) which allows a double fusion welding and leaves enough material to carry out tests of cut and peel on samples with seams taken on the spot. These welds include an air channel that allows a test of seam air pressure.
This type of sealing is applied longitudinally to join two rolls of geomembrane. This seal leaves an internal channel for quality control.
This type of sealing is applied to restricted areas such as corners and closed connections where the power cannot be used properly. wedge welder a manual extrusion fillet welder is used. Before any extrusion fillet welding, it should be ground the geomembrane to ensure proper adhesion of the material stretched by pressure or extruded.
The extrusion or granulated cord must be made entirely of the same resin, have the same type of polyethylene and be of the same geomembrane supplier. Process additives and antioxidants, other than carbon black, must be be identified by name and percentage. The total combined percentage processing media, antioxidants, carbon black and other additives, should be less than 3.5% by weight. All additives must be dispersed throughout the extrusion bead or granules. should not exist no contamination of foreign matter in the extrusion cord or granulated. Read more about Choosing the proper method for welding geomembranes.
Seals or test seams are made before each displacement and at intervals not exceeding four or five hours. The test seams must reproduce the same conditions as the encountered when geomembrane panels are welded: type of material, ambient temperature, etc. The CC Inspector also can request test stitching when weather conditions vary considerably.
For each test seam, the QC Inspector cuts four samples 1 inch wide (25 mm) with a die cutter. Then you are samples are subjected to peel and shear strength tests using a field tensiometer. All four samples must meet or exceed project requirements relative to peel and shear tests and present a type of failure FTB (Film Tearbond). Please refer to NSF-54 for failure types. The test seams are tested and approved by the Inspector of CC who will document each test seam with the following information: test seam number, parameters for the welding (speed and temperature), name of the welding technician, equipment number, date and time, shear test results and take off etc. as it appears in the Test Essay form by Fusion (A4) and Extrusion Proof Test form (A5) of the Appendix.
In each seam, the welding technician must mark on the lining your initials, team number and time you started the welding. The QC Inspector will record this information in the Sewing Procedures form (A3) included in the Appendix.
Non destructive essays
All seams should be inspected for continuity (100%) with a non-destructive testing method. These methods include air pressure test and the Vacuum Box test (more common for polyethylene geomembranes). any seam failing any of these tests is rebuilt or repaired until to obtain a satisfactory result. It must be registered in the proper form (A3) all test results not destructive.
Air Pressure Test
The air pressure test is used as much as possible since relies less on observation and represents mechanical testing supplementary for sewing. This test consists of inject air into the center channel of the seams by double-way fusion at a given pressure of approximately 30 psi (208 KPa). After a monitoring time of three to five minutes, the Quality Control Inspector will record the pressure drop and will ensure that it is within the limits of the requirements of the project for initial air pressure and Table 2 for maximum allowable pressure drop).
Once the pressure test of a seam has been completed, the edge of a seam that is opposite the pressure gauge should be cut off to ensure that air pressure flows freely throughout along the entire seam. If the air pressure is not removed from the rim Opposite the seam, the air channel blockage should be located.
Yes said blockage cannot be located visually, the seam down the middle and retest both sides of the cut. The same operation must be repeated until the channel lock. If the seam does not hold air pressure, check that both edges are well sealed and retest. If the seal still does not hold pressure and the leak cannot be visually located, The overlap of the seam shall be cut and a test shall be made to the stitching using the Vacuum Box method. can be considered sewing as satisfactory only when one of the methods non-destructive testing yields a satisfactory result.
In order to evaluate the seam in the field, tests must be carried out in destructive samples both as regards the take-off Photo 06 and shear strength. In most cases the Quality Assurance Representative will also send samples to an independent laboratory. destructive samples they are usually marked at a frequency of one every 500 feet (150 meters) of seam length, unless otherwise specified. Is frequency represents an average frequency for the entire project.
These tests are carried out in a portable equipment called a tensiometer.
Whether it is the Quality Assurance representative or the Inspector of Quality Control will indicate the location of the samples. Whenever Wherever possible, destructive samples should be taken in such a way that the repair procedures are minimal or unnecessary (example: in the anchor channel). Care must be taken that all destructive samples cut from the geomembrane are patched or covers the same day to avoid possible damage to the compacted ground due to overnight rains or strong winds. The Inspector of Control of Quality must verify the destructive tests with the person in charge of the work and inform you of the locations of all trials so that they are patched later the same day.
The QC Inspector must test four one-inch samples wide (25 mm) in terms of shear strength and peel strength. In In the case of double-track fusion seams, tests will be carried out on both sides of the seam as far as take off. If all four samples meet the project specifications, considers that the seam has passed the field test and can send the rest of the sample to the laboratory in order to carry out further tests. With regard to laboratory tests, it is considered acceptable that four out of five samples pass. At the end of the project, each seam in field must be linked to two destructive tests that have passed the test, as shown on the Destructive Testing form (A6) of the Appendix. The Quality Control Inspector will document the destructive tests with the following information: date and time, destructive test number, number of seam, location, results of shear strength tests and detachment and type of failure of each sample.
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