Secure landfills for industrial waste

Secure landfills for industrial waste are permanent disposal facilities designed to isolate hazardous or non-recoverable industrial waste indefinitely, preventing any contact with the surrounding environment. In Spanish they are known as depositos de seguridad.

Unlike conventional landfills, secure landfills are subject to much stricter technical requirements for lining, leachate control, geotechnical stability and long-term environmental monitoring.

These facilities sit at the very bottom of the waste hierarchy: they are used only when prevention, reuse, recycling and recovery are not technically or economically viable.

What a secure landfill is

A secure landfill is a controlled disposal facility that ensures the physical, chemical and biological containment of hazardous or stable, non-reactive industrial waste. Its design must prevent the release of contaminants to soil, water or air for decades, and in some cases far longer, depending on the nature of the materials stored.

Secure landfills can hold solid, semi-solid or stabilised industrial waste, after a pre-treatment that guarantees the waste is immobilised and compatible with the storage conditions.

Main objectives

1. Isolate hazardous waste permanently.
2. Prevent contamination of soil and groundwater.
3. Provide a safe disposal route for waste that cannot be recovered.
4. Meet the environmental safety requirements set out in EU legislation.
5. Ensure long-term traceability and control of the waste deposited.

Types of secure landfill

Surface facilities

Built on the ground, with several lining layers and drainage systems.

• Most common for solid or stabilised waste.
• Require extensive leachate and gas control measures.

Underground facilities

Located in stable geological formations such as disused mines or deep salt deposits.

• Used for highly toxic waste or waste with low radioactivity.
• Offer greater natural geological isolation.

Facilities in exhausted quarries or mines

These make use of existing natural or artificial cavities, reducing the impact on new land.

Types of waste accepted

Secure landfills are intended for industrial waste that cannot be safely recovered or recycled:

• Waste containing heavy metals such as lead, cadmium or mercury.
• Contaminated ash and slag.
• Sewage sludge containing persistent contaminants.
• Residues from chemical or electroplating processes.
• Materials containing persistent organic pollutants (POPs).
• Rejects from hazardous waste treatment plants.

How a secure landfill works

Design and construction

• Double lining with geomembranes and compacted clay.
• A leachate drainage system.
• Gas control through venting pipes.
• Natural or engineered geological barriers.
• Continuous hydrogeological monitoring.

Operation

• Reception and documentary verification of incoming waste.
• Inspection and recording of each load.
• Disposal in cells, with compaction and intermediate cover.
• Progressive sealing to reduce infiltration.

Closure and aftercare

• Final sealing with a multi-layer cap (clay, geotextile, vegetation).
• Environmental control for a minimum of 30 years.
• Monitoring of water, soil and gas emissions.

Applicable legislation

European Union

• The Landfill Directive 1999/31/EC, amended by Directive (EU) 2018/850.
• Council Decision 2003/33/EC, which sets the criteria and procedures for the acceptance of waste at landfills.
• The Industrial Emissions Directive 2010/75/EU.
• Regulation (EU) 2020/852 (EU Taxonomy), relevant where these facilities are assessed against environmental sustainability criteria.

Spain

• Law 7/2022 on waste and contaminated land for a circular economy.
• Royal Decree 646/2020 on the disposal of waste by landfill.
• Royal Decree 815/2013 on industrial emissions.
• Regional plans for the management of industrial and hazardous waste.

Waste acceptance criteria

Before disposal, waste must pass the leaching tests and meet the chemical and physical criteria set out in Council Decision 2003/33/EC.

Parameters typically analysed include:

• pH and conductivity.
• Concentrations of heavy metals and salts.
• Long-term behaviour under environmental conditions.

Waste that exceeds the established limits must be pre-treated through solidification or stabilisation processes to ensure it is rendered inert before disposal.

Safety and environmental control requirements

• Composite lining: synthetic geomembranes plus a clay layer at least one metre thick.
• Leachate drainage system: perforated pipes, extraction wells and regular analysis.
• Natural geological barriers: preferably with low permeability (k below 10⁻⁹ m/s).
• Groundwater monitoring: before, during and after disposal.
• Gas emission control: passive or active venting.
• Aftercare monitoring: a minimum of 30 years, extendable according to risk.

Benefits of secure landfills

Environmental

• They prevent uncontrolled dumping and the contamination of soil and water.
• They isolate hazardous waste from the biosphere for very long periods.
• They allow old industrial sites to be closed safely.

Economic

• They reduce the cost of transporting hazardous waste over long distances.
• They create jobs in construction, operation and environmental monitoring.
• They support regulatory compliance and legal certainty for companies.

Social

• They strengthen public trust through transparency and control.
• They protect local communities and nearby ecosystems.

Risks and controversies

1. Social opposition due to siting or the perception of risk.
2. High construction and maintenance costs.
3. The need for very long-term monitoring.
4. Management of the environmental liability after closure.
5. The risk of leaks in the event of structural or geological failure.

Innovation and sustainability

The engineering of secure landfills is moving towards more sustainable models:

• Advanced geosynthetic materials with greater durability.
• Early leak-detection systems based on IoT sensors.
• Digital twins to simulate structural and chemical behaviour.
• Landscape integration and ecological restoration.
• Gas capture and, where applicable, energy recovery from residual biogas.

How they relate to the circular economy

Although secure landfills belong to the lowest level of the waste hierarchy, they are a necessary tool for closing the industrial cycle safely, particularly when waste cannot be recycled or recovered. They contribute to the circular economy by:

• Providing controlled, traceable disposal of non-recoverable waste.
• Preventing future impacts and environmental liabilities.
• Supporting projects for landscape recovery and ecological compensation.

Their management is also aligned with the principles of extended producer responsibility and corporate environmental transparency.

Conclusion

Secure landfills for industrial waste are essential infrastructure for the safe, permanent disposal of the most hazardous or non-recoverable waste. Their design and management demand the highest technical responsibility, rigorous environmental control and social transparency, because their stability must be maintained for generations. Within a circular-economy framework they are not an alternative to recycling but a final guarantee of environmental protection, reserved only for waste with no other viable treatment. At Manglai we help companies measure their environmental impact and prepare their sustainability reporting. Discover how Manglai can help you.