A heap leach geomembrane must be selected for the process solution, temperature, loading, support conditions and construction method—not simply by polymer name or thickness. HDPE and LLDPE can be candidates, but approval requires evidence for the proposed formulation and the complete lining system. A material specification does not by itself approve a mine design or guarantee a service life.
This guide supports engineers and procurement teams comparing liner proposals. The mining application page covers supply enquiries; this article explains how to evaluate the technical evidence. Separate guides address installed liner testing and operating maintenance.
Chemical Resistance & Durability
Specify the actual exposure
Describe the complete process liquid, including concentrations, pH range, temperature, oxidizing constituents, dissolved salts and relevant contaminants. Include normal service, start-up, cleaning and credible upset conditions. Two liquids at the same pH can affect a polymer differently; an acid/alkali resistance chart is only a screening tool.
Ask which evidence applies to the exact offered formulation, surface construction and seams. Identify the solution, exposure temperature and duration, then compare relevant before-and-after properties against agreed criteria. A favorable result for a different chemical concentration or a much lower temperature should not be presented as proof for the project.
ASTM D5322-23 provides laboratory immersion procedures for investigating geosynthetic chemical resistance. It does not, by itself, establish acceptable behavior: the liquid, evaluation tests and acceptance criteria must be defined. Laboratory compatibility evidence is one input to the engineer’s selection, not a prediction that the liner will last a specified number of years.
Compare HDPE and LLDPE without assuming interchangeability
| Selection issue | What to compare | Approval evidence |
|---|---|---|
| Material behavior | HDPE is generally stiffer; LLDPE is generally more flexible. Grade and formulation still matter. | Relevant product test data, including the response required by the design. |
| Settlement and strain | Expected differential movement, restraint, transitions and load duration. | A deformation assessment; break elongation is not an allowable long-term design strain. |
| Chemical and thermal exposure | Actual liquid, temperature and exposure duration for both materials. | Compatible formulation and seam evidence under relevant conditions. |
| Manufacturing quality | Applicable specification, edition, thickness and surface type. | Batch-linked reports and a clear schedule of required properties. |
| Construction | Handling, weather, trial welding, seam tests and protection placement. | An approved installation and CQA plan for the proposed product. |
GRI-GM13, Revision 19 (11 June 2025) addresses HDPE manufacturing quality. GRI-GM17, Revision 17 (11 June 2025) addresses LLDPE. These are the editions available from the official source during this review; the procurement specification should state the edition it adopts. Do not call LLDPE “GM13 compliant” or treat either specification as a GSI-issued product certificate.
Separate durability indicators from service-life claims
Review antioxidant-related test results, aging behavior, stress-crack resistance where applicable, temperature and mechanical stress together. Standard OIT and high-pressure OIT are different tests and their values should not be treated as interchangeable. An OIT result is not a stand-alone demonstration of 30, 50 or 100 years of field service.
Ask whether the durability assessment includes exposed and buried zones, actual chemical exposure, relevant stresses, seams and penetrations. State the assumptions behind any service-life estimate and distinguish it from a commercial warranty. If the supplier cannot substantiate a numerical lifetime, record that limitation instead of repeating the number as a design value.
Puncture Resistance & Mechanical Strength
Evaluate the full layer arrangement
Identify the foundation, liner, any cushioning geotextile, drainage material and ore or other overlying load. Puncture can originate above the membrane or from a hard projection beneath it. Remove unsuitable projections and soft spots; a protection fabric is not a substitute for an accepted subgrade.
Assess particle angularity, grading, cover placement and equipment effects as well as nominal sheet thickness. A high index puncture result is useful for product comparison under that test method, but it is not an allowable field pressure. In particular, do not convert a result in newtons directly into a permitted heap pressure in kilopascals.
ASTM D5514/D5514M-24 includes site-specific hydrostatic compression procedures. GRI-GS11 addresses field test pads for protection assessment. Choose an evaluation representing the actual materials and installation conditions, with the test pressure, duration and failure criteria agreed in advance.
Use calculations to check a proposal’s assumptions
For a simplified uniform heap, nominal vertical stress is γH. An illustrative 20 kN/m³ unit weight and 30 m height produce 600 kPa before detailed geometry, equipment and local-contact effects are considered. This is a loading estimate, not a membrane capacity. A pressure stated for a shallow test should not be assumed adequate for the full heap.
Check thickness units independently of the nominal sales label. One mil is 0.0254 mm: 60 mil equals 1.524 mm, while 1.5 mm is approximately 59.1 mil. Whether an offered grade meets a nominal-thickness requirement depends on the specified measurement method, tolerances and acceptance rules—not on rounding the label.
Where a geotextile cushion is proposed, specify the relevant puncture-protection assessment and material properties. GSM describes mass per area. Two fabrics with the same GSM can have different thickness under load, construction and protection performance. Confirm the suitability of the proposed nonwoven geotextile as part of the system.
Check interface stability and deformation
A textured surface changes the interface; it does not provide a universal friction angle or guarantee stability. Test the actual contacting materials under representative normal stresses, moisture conditions and displacement requirements. The designer must decide which strength and deformation parameters are relevant to the expected failure mechanism.
Consider transitions, anchor zones, drainage features and possible differential settlement. Do not use a high tensile elongation at break as permission for comparable strain in a loaded long-term barrier. If deformation, slope angle or the layer arrangement changes, revisit the design rather than merely ordering a thicker sheet.
Seam Integrity & Installation Reliability
Match the welding procedure to polyethylene liners
Use a qualified procedure for the specified material, equipment and detail. Dual-track hot-wedge welding is commonly used on long accessible runs; compatible extrusion welding can be used at suitable details and repairs. Trial welds should demonstrate the accepted procedure under the relevant field conditions before production continues.
Single-ply roofing tape widths, roof-membrane solvent cleaning instructions and roofing inspection schedules are not interchangeable with heap leach polyethylene lining requirements. Detail pipe penetrations, terminations, changes of grade and repairs using the approved containment drawings and manufacturer-compatible procedures.
Require distinct continuity and strength evidence
Air-channel and suitable vacuum testing assess seam continuity. Destructive testing evaluates sampled seam peel and shear behavior. ASTM D6392-25 describes destructive testing of nonreinforced thermo-fusion seams; GRI-GM19a provides property requirements for relevant homogeneous polyolefin seams when specified. Select the applicable material, thickness and seam-method criteria.
Agree how failures are investigated, repaired and retested. Covering should wait for the required release. Where an electrical leak location survey is specified, plan the construction sequence and electrical conditions so the survey can evaluate the intended area. Keep these installation checks separate from the manufacturer’s sheet test report.
Build a submittal that can be accepted
| Document | What it should identify | Decision it supports |
|---|---|---|
| Product data sheet | Grade, polymer, surface, thickness, methods and whether values are minimums or typical. | Initial specification comparison. |
| Manufacturing reports | Lot or roll identity, samples, dates, results and applicable requirements. | Traceable material conformity; not installation acceptance. |
| Compatibility and durability assessment | Liquid, temperature, exposure, formulation and evaluation criteria. | Suitability for the proposed service conditions. |
| Protection and interface evidence | Actual materials, loading and test conditions. | System design review. |
| Installation and CQA plan | Trial welds, production tests, sampling, repairs and hold points. | Controlled field acceptance. |
| As-built and handover records | Panels, seams, tests, defects, repairs, exclusions and signed release. | Operation, monitoring and future investigation. |
Compare quotes on an equal technical basis
Give each supplier the same thickness, surface, quantity, roll constraints, material standard edition and required documentation. Separate supply, transport, protection layers, installation, testing and repair allowances. A lower price per square metre is not equivalent if the proposed product or testing scope differs.
Start with the HDPE liner and LLDPE liner options, then send Jinseed the project specification. Include process chemistry, operating temperature, heap height, foundation conditions and the required approval documents so the proposed grade can be reviewed against the actual project.
