Selecting the right HDPE geomembrane for mining containment: Why resin design matters
Rethinking containment: why index standards aren't enough for tailings storage
When performance matters, the design basis matters
In many containment applications, design choices reduce to a simple question: Does the material meet the standard? If a geomembrane satisfies GRI GM13/17 or GRI GM42, the specification is often considered complete, the box is checked, and the project proceeds.
Tailings storage is different
A Tailings Storage Facility (TSF) is not a routine containment structure. It is a long-lived, high-consequence facility requiring a barrier system evaluated against strict site-specific variables including tailings chemistry, foundation conditions, local climate, seismicity, staged construction, operational demands, and final closure. If a barrier system fails to perform as intended, the potential impacts can include significant safety, environmental, regulatory, operational, financial, and reputational consequences.
Rather than asking only whether a geomembrane meets a broad reference standard, facility owners and design professionals must consider whether the barrier system has been fully evaluated and documented for the specific facility and its operational environment.
Compliance is a baseline, not a design basis
GRI GM13 and GRI GM42 standards establish vital minimum index properties that enable designers and specifiers to compare geomembranes on a common benchmark. However, index standards are no substitute for project-specific engineering evaluations.
Laboratory index results must be weighed alongside site-specific factors that include:
Process or tailings liquor chemistry
Long-term thermal exposure and stress-cracking behaviour
Interface shear mechanics under representative site loads
Subgrade quality, mechanical installation stress, and staged construction sequences
Project risk assessments, regulatory requirements, and owner mandates
A common pitfall in TSF design is carrying forward legacy specifications without re-assessing project-specific design assumptions. When past specs are reused automatically, parameters like geomembrane thickness and reference standards may be carried forward even though the current project may involve different site, operational, construction, risk-assessment, or closure considerations.
A generic, checklist-based approach does not address the fundamental question: Is this barrier system fit for service over the full lifecycle of this specific facility?
How GISTM reframes the industry's core questions
Global Industry Standard on Tailings Management (GISTM) has reframed the core questions the mining industry must answer. High-profile tailings failures, including Mount Polley1, Samarco2, and Brumadinho3, have fundamentally shifted governance expectations. They underscore the vital need to align design assumptions, construction practices, operational controls, governance, risk management, and long-term monitoring over the facility lifecycle.
The Global Industry Standard on Tailings Management has elevated expectations around governance, accountability, risk management, and overall TSF lifecycle oversight.
Specifically, GISTM introduces design-related expectations that must be evaluated within the context of the individual facility. This includes assessing site conditions, credible failure modes, consequence classifications, lifecycle considerations, closure criteria, and documented risk management processes. Materials and barrier systems must be evaluated within this broader context, accounting for seepage control, internal erosion, geochemical interaction, and constructability.
This moves far beyond confirming a generic index property. It demands a documented, site-specific technical basis confirming that selected materials are fit for their intended service conditions. Furthermore, GISTM defines clear governance accountabilities, including the role of the Accountable Executive, subject to the applicable implementation framework and organizational context.
Core elements of a project-specific design basis
A comprehensive, project-specific barrier system design basis should be established by qualified engineering professionals and address:
Long-Term Service Life: Predictive aging models, chemical compatibility data, and testing designed around actual exposure conditions.
Interface Shear Performance: Shear testing under site-specific normal stresses, moisture levels, and liner interface configurations.
Thermal & Stress-Crack Resistance: Performance evaluation under site-specific placement and operating temperature ranges, acknowledging that standard index tests do not fully predict field aging.
Survivability & Installation: Evaluation of subgrade profiles, cover soils, construction equipment loads, operational stress, and rigorous QA/QC protocols.
Chemical Compatibility: Site-specific exposure testing with project process liquor, supported by relevant literature and historical data.
Integrated Risk Management: Direct alignment between barrier selection, credible failure modes, consequence classifications, and facility controls.
Note: These project-specific evaluations are intended to supplement, not replace, GRI GM13, GRI GM42, or applicable regulatory and owner criteria. They bridge the gap between published minimum standards and rigorous, documented engineering evaluations.
Integrating technical design with governance
Under GISTM-aligned governance, barrier system performance directly informs technical design, risk management frameworks, accountability structures, and independent review processes. Accountable Executives and review boards require clear, objective data to evaluate design assumptions, material limitations, risk assessments, and residual risks.
Consequently, barrier system selection must happen early enough to align engineering, procurement, construction, operations, and governance oversight. Documentation must clearly detail the assumptions, testing data, site limitations, risk inputs, and engineering logic driving the selected design. While this documentation supports statements regarding GISTM alignment, it should be presented transparently without being framed as a absolute guarantee of performance outcomes.
How Solmax supports project-specific engineering
Solmax collaborates with Engineers of Record, Owner’s Engineers, and mining operators by providing project-specific technical information, testing support, product data, and documentation for consideration in the design process. Depending on project demands, this support includes:
Chemical compatibility testing with actual tailings liquor
Long-term service life modelling under site-specific exposures
Tailored interface shear testing and documentation
Final decisions regarding facility design, risk assessment, regulatory compliance, GISTM alignment, and overall system performance remain the sole responsibility of the owner and their appointed qualified professionals.
A geomembrane that meets a referenced standard and a barrier system evaluated for the facility’s specific chemistry, climate, construction, operation, risk assessment, and lifecycle conditions are not necessarily the same inquiry. GISTM and recent industry experience have increased attention to this distinction.
A project-specific design basis can help ensure that barrier-system selection is tied to the facility’s actual conditions, documented risk assessment, and technical assumptions.
For facilities with significant safety, environmental, and operational risks, barrier-system design considerations should be addressed early and documented throughout the project lifecycle.
Summary takeaways
Index compliance does not equal fit-for-purpose design. GRI GM13/17 and GRI GM42 are starting points, not complete design bases.
Site conditions dictate performance. Chemistry, thermal cycles, shear stresses, and placement conditions must drive material selection.
GISTM demands documentation. Material selection must be backed by a documented technical basis linked directly to risk management and governance.
Disclaimer: This article is provided for general informational, marketing, and industry-commentary purposes only. It reflects Solmax’s opinions and observations regarding tailings management practices, barrier-system design considerations, and industry standards. It does not constitute legal, engineering, geotechnical, environmental, regulatory, or other professional advice and should not be relied upon as such. Project-specific decisions regarding tailings management, geomembranes or barrier systems, GISTM alignment or conformance, safety, environmental performance, regulatory compliance, and risk management should be made by qualified professionals based on site-specific data, applicable laws, standards, permits, approvals, contracts, and owner requirements. References to GRI GM13, GRI GM42, GISTM, or any other standard or guideline are general in nature and may not reflect all applicable requirements or project-specific obligations. This article is not intended as a definitive interpretation of GISTM, any regulatory requirement, or any particular project’s design obligations, risk profile, compliance status, or performance expectations. Solmax does not represent or warrant that any product, system, testing, modeling, technical support, documentation, or service will ensure regulatory compliance, GISTM conformance, facility performance, risk elimination, or any particular outcome. All information is subject to project-specific evaluation and applicable terms and conditions.
