In the world of geomembranes, GRI GM13 has been a cornerstone specification for decades, providing a minimum standard for HDPE geomembranes to ensure baseline material quality. While this standard has served its purpose well for low-risk applications, the industry has been slow to adopt enhanced specifications that align with advancements in material science and the increasing demands of high-risk containment systems.

Some engineers and industry professionals continue to resist calls for stricter specifications, often citing the satisfactory performance of older, exposed liners. While this argument may hold true for some projects, the mining industry offers a stark counterpoint. As the saying goes, “All our sins are buried.” We don’t fully know the extent of degradation and failures in liners that have been covered or subjected to extreme conditions.

What we do know is that acid mine drainage (AMD) represents one of the most severe environmental challenges globally, with catastrophic impacts on ecosystems and communities. In such scenarios, the argument for maintaining the status quo falls apart. We must take a cautious and forward-thinking approach, focusing on the development of perpetual containment systems that can withstand the test of time. The additional cost of higher-performing geomembranes is relatively insignificant compared to the long-term environmental and financial costs of failure.

Atarfil recognises this reality and has responded with its EVO AC (Acid-Resistant) and EVO AR (Alkaline-Resistant) geomembranes. These go far beyond the limitations of GM13 and set a new benchmark for long-term containment in aggressive environments.

The Limitations of GRI GM13

GRI GM13 focuses on manufacturing quality control (MQC), setting minimum thresholds for properties such as:

• Oxidative Induction Time (OIT) and High-Pressure OIT (HPOIT).
• Stress Crack Resistance (SCR).
• UV and thermal resistance.

While GM13 ensures baseline quality, it does not address:

• Chemical resistance: Critical for high-risk applications involving acidic or alkaline solutions.

• Site-specific performance: Factors like pH, heavy metals, or brines that accelerate degradation are not considered.

These limitations highlight the need for specifications that align with modern containment challenges, particularly in the mining industry, where the risks of failure are profound.

Atarfil EVO AC and AR: Advancing the Standard

Atarfil’s EVO AC and EVO AR geomembranes are designed to address these gaps, offering properties that far exceed GM13 and introducing chemical immersion testing to validate long-term performance under extreme conditions.

Comparing EVO AC and AR to GRI GM13

1. Oxidative Induction Time (OIT) and High-Pressure OIT (HPOIT):

   • GM13 Requirements:

     • OIT ≥ 100 minutes.
     • HPOIT ≥ 400 minutes.

   • EVO AC and AR Performance:

     • EVO AC: OIT ≥ 120 min, HPOIT ≥ 500 min (20–25% higher).

     • EVO AR: OIT ≥ 150 min, HPOIT ≥ 1,000 min (50–150% higher).

2. Stress Crack Resistance (SCR):

   • GM13 Requirement: ≥ 500 hours.

   • EVO AC and AR Performance: ≥ 3,000 hours (500% higher).

3. UV and Thermal Ageing:

   • GM13 Requirements: Retention of ≥ 50% HPOIT after UV (1,600 hours) and oven ageing (90 days at 85°C).

   • EVO AC and AR Performance: Retention of ≥ 75% HPOIT under the same conditions.

Introducing Chemical Immersion Testing

Chemical resistance is a critical factor that GM13 does not address. Atarfil’s immersion tests validate performance under aggressive conditions:

EVO AC (Acid Resistant):

• Immersion in 10% sulfuric acid (pH ≈ 1) at 50°C for 90 days.
• Retains ≥ 50% Std OIT.

EVO AR (Alkaline Resistant):

• Immersion in concentrated brines (pH ≈ 10) at 60°C for 200 days.
• Retains ≥ 55% Std OIT.

These tests provide measurable, site-specific performance data, enabling confident specification for projects involving heap leach pads, tailings dams, and brine storage.

Why This Matters for Designers

1. Mitigating Long-Term Risks:

   • Higher OIT, HPOIT, and SCR values ensure durability under chemical, thermal, and UV stresses.
   • Chemical immersion tests validate material reliability in the most challenging environments.

2. Future-Proofing Containment:

   • EVO AC and AR align with GISTM requirements, offering enhanced protection for high-risk applications.

3. Standardising Excellence:

   • By providing superior standardised materials, Atarfil helps designers specify high-performance options without the need for time-intensive customisation.

4. Customisation When Needed:

   • For unique site conditions, Atarfil can develop bespoke antioxidant packages, though the EVO range offers a practical, high-performing solution for most applications.

Setting a New Baseline for Perpetual Containment

Atarfil’s EVO AC and AR geomembranes represent a significant step forward, not as a limit to innovation, but as a foundation for raising industry standards. These materials set a higher baseline for chemical resistance and long-term performance, ensuring secure containment for aggressive waste.

The need for perpetual containment systems has never been clearer, given global environmental challenges like acid mine drainage. Even if the extra cost of enhanced specifications is relatively insignificant, there is no excuse for complacency. The protection of the environment demands nothing less.