Landfill Leachate Risks

Summary

Landfill leachate risks refer to the environmental and human health hazards associated with contaminated liquid generated within landfills or historical fill sites. Effective assessment and management are essential to protect groundwater, waterways, ecosystems, and development outcomes.

Definition

Landfill leachate risks relate to the potential for contaminated water—formed when rainwater or waste moisture percolates through landfill material—to migrate into soil, groundwater, or surface water environments, causing pollution or harm. Leachate often contains a complex mix of organic compounds, heavy metals, nutrients, pathogens, and dissolved solids.

Why It Matters

Leachate is one of the most significant environmental concerns associated with modern and historical landfills.

Poorly managed leachate can:
‍

• contaminate groundwater aquifers used for drinking water or irrigation
• pollute nearby waterways, wetlands, and stormwater systems
• mobilise contaminants, increasing the extent and complexity of remediation
• generate odours and contribute to vapour intrusion risks
• corrode infrastructure or affect soil stability
• threaten human health, ecosystems, and sensitive receptors
• create long-term liabilities that affect redevelopment feasibility
  ‍

Australian environmental regulators—including EPA NSW, EPA Victoria, and QLD DEPW—require thorough assessment and management of leachate, particularly where redevelopment or construction intersects with former landfill sites.

Leachate risks are closely linked to landfill gas, hydrology, waste composition, groundwater elevation, and engineered containment integrity (liners, capping, drainage systems).

When It’s Required

Leachate risk assessment, monitoring, or management is required whenever works occur on or near former landfills, waste disposal areas, or filled land. Common triggers include:

Development Applications (DAs) on Former Landfill Sites

Planning authorities typically request leachate investigations as part of contaminated land or groundwater assessments.

Construction and Excavation Activities

Earthworks can alter drainage pathways or expose leachate-affected material, increasing risk to workers and the environment.

Groundwater and Hydrogeological Assessments

Leachate can migrate into aquifers, requiring monitoring wells and long-term groundwater quality assessment.

Landfill Capping, Closure, and Encapsulation Projects

Engineered containment systems must manage leachate generation and prevent off-site migration.

Post-Closure Environmental Monitoring

Operational and closed landfills are typically subject to EPA-mandated leachate monitoring frameworks.

Contaminated Land and Remediation Works

Leachate may drive contaminant migration, influencing the design of remediation strategies and environmental controls.

High-Risk Sensitive Receptors

Sites located near waterways, wetlands, drinking water catchments, or residential areas typically require enhanced leachate risk assessment.

How We Can Help

Nova Group Pacific provides comprehensive assessment, monitoring, and management solutions to understand and mitigate landfill leachate risks.

Our multidisciplinary services include:
‍

• Contaminated Land & Remediation‍
• Water Quality Sampling & Monitoring‍
• Leachate & Gas Monitoring‍
• Groundwater & Surface Water Assessments‍
• Soil & Waste Classifications

Related Terms and Concepts

Explore associated landfill and environmental risk-management concepts:
‍

• Landfill Gas‍
• Remediation Action Plan (RAP)‍
• ‍Environmental Drilling‍
• Leachability‍
• Volatile Organic Compounds‍
• Groundwater Sampling