HDPE geomembrane installation requires an accepted support surface, traceable rolls, a practical panel layout, qualified welding procedures and documented testing before the liner is covered or commissioned. There is no universal welding temperature, speed, air-test pressure or seam-strength value suitable for every thickness, machine and site condition.
Use this guide to organize installation hold points and handover records. The approved design, construction specification, manufacturer’s instructions and site quality plan determine acceptance. For more detail on joining methods, see the geomembrane welding and seaming guide.
Approve the installation package before mobilization
| Hold point | Required evidence | Release condition |
|---|---|---|
| Material delivery | Approved grade, thickness, roll identification and relevant reports | Delivered material matches the accepted submittal |
| Subgrade readiness | Survey, compaction where specified, surface and drainage inspection | Support is accepted and defects are resolved |
| Start of welding | Qualified operators, equipment checks and passing trial seams | Procedure is suitable for current material and conditions |
| Covering | Production testing, repair records and detail inspection | Required results and repairs are accepted |
| Handover | As-built panel map, seam and test logs, outstanding-item closure | Responsible project authority releases the system |
The U.S. Bureau of Reclamation’s geomembrane design chapter provides a public reference for liner systems, construction details and quality considerations. It is not a substitute for the specification governing a different project.
Inspect delivered rolls and plan safe handling
Match roll labels and certificates to the approved HDPE geomembrane grade. Check dimensions, surface type, visible damage, storage and sampling requirements. A manufacturing report does not prove that shipping and unloading caused no damage. Quarantine nonconforming material rather than mixing it into accepted stock.
Estimate handling mass using width × length × thickness × density. A hypothetical 7 m × 150 m roll, 1.5 mm thick, at an assumed density of 940 kg/m³ contains approximately 1,480.5 kg of polymer; an 8 m roll with the same length and thickness contains 1,692 kg. Add core and packaging mass when planning lifts. Use the actual labelled weight and an approved lifting arrangement.
Accept the support surface and water controls
The surface must provide the support, grades and finish specified by the design. Remove debris and unacceptable sharp objects; repair soft zones, erosion and voids. Verify the required compaction using the specified test and acceptance basis. A footprint or a fixed number of roller passes is not a density test.
Address groundwater, trapped gas and rainfall before deployment. Do not place lining over standing water or unstable ground and assume a thicker sheet will solve the problem. Where a protection geotextile is specified, inspect it separately; it must not conceal unaccepted subgrade conditions.
For scale, 10 m of freshwater head gives approximately 1,000 × 9.81 × 10 = 98.1 kPa hydrostatic pressure. This does not represent the concentrated contact pressure beneath a sharp stone, nor does it establish a safe liner thickness.
Lay out panels, details and quantities
Plan deployment routes, working space, panel orientation, seam access and termination details before unrolling. Minimize difficult intersections where practical while following the approved layout. Pipe boots, sumps, penetrations and anchors need coordinated details; do not invent one anchor-trench size for every slope and foundation.
Keep the sheet supported without bridging voids or introducing sharp folds. Manage wind and thermal movement with the approved installation method. Temporary ballast must not damage the liner. Keep unapproved vehicles off exposed material and establish controlled access for covering.
Check movement and material quantities
With an illustrative linear thermal-expansion coefficient of 0.00012/K, a free 50 m length subjected to a 20 K temperature rise changes length by 0.12 m, or 120 mm. Actual restraint and material behavior alter the response. This example does not prescribe a universal slack allowance or overlap.
A 6 m × 50 m panel has 300 m² gross area. Dividing a 7,140 m² geometric requirement by 300 gives 23.8, or at least 24 such panels before layout, overlaps, anchors, penetrations and waste. The procurement quantity must come from a panel plan, not that division alone.
Qualify the welding procedure on site
Hot-wedge equipment is commonly used for accessible straight seams, including dual-track configurations. Extrusion welding serves suitable details and repairs. The appropriate process depends on material and access; it is not established by the appearance of a finished bead.
- Use clean, dry and properly prepared interfaces, with compatible extrusion material where applicable.
- Set and record equipment parameters through qualified trials for the grade, thickness, machine and current conditions.
- Check calibration and equipment condition; identify the operator and trial-seam specimens.
- Repeat trials at the intervals and changes specified by the quality plan.
- Follow the approved preparation procedure; do not prescribe arbitrary grinding depth, solvent use or removal of the finished weld bead.
A machine display is a process setting, not proof of an adequate interface temperature or bond. Stop and reassess when conditions depart from the qualified procedure. Numerical settings from another project are not ready-to-use installation instructions.
Use complementary seam tests
ASTM D5820 evaluates continuity of compatible dual-track seams through their air channel. It does not measure seam strength. The test pressure, stabilization, duration and allowable changes must follow the applicable procedure and quality plan, including temperature considerations and verification that the test covers the intended channel length.
ASTM D6392 addresses destructive peel and shear assessment for nonreinforced thermofusion seams. Interpret strength, separation, elongation and failure behavior against the specified criteria. A parent-sheet tear alone is not the entire acceptance decision. Do not apply a value for one thickness or material to every liner.
Use appropriate nondestructive methods for details that cannot be tested through an air channel. Record each test location, method, result and repair. Sampling frequency, laboratory confirmation and failure-resolution boundaries must be established in the approved plan rather than inferred from a universal metres-per-sample rule.
Repair, retest and protect accepted work
Identify punctures, defective seams and unaccepted details on the panel map. Determine the extent of a failed seam using the specified investigation procedure. Repair with compatible material and an approved detail, then repeat the required tests. Closing a visible hole without documenting the repair does not close the quality record.
Inspect the liner before covering. If electrical leak-location testing is specified, confirm that the method suits the liner and surrounding conductive or insulating layers. Cover placement must avoid unacceptable dragging, dropping, rutting and trapped folds. Approved seam results do not protect against later construction damage.
Handover with a traceable record
Provide roll records, accepted subgrade releases, panel identification, trial and production seam logs, destructive-test reports, repair maps, inspection photographs and as-built details. List deviations and their written dispositions. Commissioning and operating inspection requirements belong in the handover package, not just the material warranty.
Request a material and document package with the drawings, thickness, surface finish, quantities and project acceptance specification. Confirm installation responsibilities and testing scope separately from the roll-supply quotation.
