▽ HDPESheet membranes
Geomembrane & HDPE liners
Polymer sheets thermally welded on site to line lakes, large reservoirs and flood channels.
What it is and how it works
Geomembranes are low-permeability polymer sheets, most commonly high-density polyethylene (HDPE). They are laid on a prepared subgrade and thermally welded on site into a continuous liner for lakes, large reservoirs and channels.
Geotextiles protect it below and above, its edges are held in anchor trenches, and the seams are tested by air pressure or vacuum before covering or filling.
HDPE
- Family
- Sheet membranes
- Build-up
- 5 layers
Where it fits — and where it does not
A good fit for
- Artificial lakes, ponds and water features
- Large reservoirs and basins
- Flood and storm-water channels
- Containment works, where the design specifies a liner
Not a fit, or needs a check
- Building roofs and podiums: roofing membranes are used there
- Small tanks with many penetrations and corners
- Exposed areas with traffic, without cover or ballast
Application pages
Advantages and limitations
Every system has strengths and limits; the right choice starts from the site conditions.
Advantages
- Low permeability and broad chemical resistance
- Large panels and seams that can be tested non-destructively
- Suited to large areas and earth structures
Limitations
- HDPE is fairly stiff and expands with heat, so wrinkles must be managed
- Needs a smooth, stone-free subgrade and protective geotextiles
- Needs specialised welding crews and equipment
System build-up
Top to bottom. Final thicknesses and materials follow the approved specification and the product TDS.
System build-up5 layers
Geomembrane & HDPE liners
Select a layer to see what it does.
Cover or ballast
Soil, concrete or armouring where the specification calls for it to protect the liner.
Where designed
Protective geotextile (upper)
Shields the liner from puncture under the cover layer.
Where designed
Geomembrane liner (HDPE)Core layer
Sheets rolled out, thermally welded on site, seam-tested and anchored in trenches.
Cushion geotextile (lower)
A cushion that protects the liner from sharp particles in the ground.
Prepared subgrade
Compacted, graded ground free of sharp stones and roots.
Preparation and application
Surface preparation
- Subgrade graded, compacted and cleared of stones, roots and sharp objects
- Anchor trenches excavated at the crest
- A cushion geotextile laid under the liner
- Panel layout planned to keep seams off the slopes where possible
Application sequence
Subgrade acceptance
Grades, compaction and surface checked before deployment.
Deployment
Panels unrolled downslope, overlapped and held down against wind.
Welding
Double-track hot-wedge welds for long seams; extrusion welds for patches and details.
Seam testing
Air-channel pressure tests on double seams, a vacuum box on extrusion welds, and destructive samples as specified.
Anchoring and cover
Edges anchored in the trenches; upper geotextile and cover or ballast placed.
General educational content; final values and requirements follow the manufacturer’s TDS and the approved project specification.
Checks and common mistakes
Quality checks
- Trial welds and recorded welding parameters
- Air-pressure test of double-track seams (ASTM D5820)
- Vacuum-box test of extrusion welds (ASTM D5641)
- A panel and seam log with the repairs marked
Common mistakes
- Deploying on stony or soft subgrade
- Welding in wind, dust or moisture without protection
- Leaving the liner unballasted overnight
- A tight installation with no allowance for thermal contraction
Common questions
How are geomembrane seams tested?
Double seams by air pressure in the channel between the welds, extrusion welds by vacuum box, plus destructive samples as specified.
Can the liner be left exposed?
Some grades are made for exposure, but many designs cover the liner to protect it from damage and temperature swings.
Do you line lakes and flood channels?
Yes, with HDPE and geomembrane sheets welded on site, the seams tested and the liner anchored in trenches.
Next step
Considering this system for your project?
Send drawings or site photos; our engineers review the case and propose the right specification.