Ecological Risk Assessment (ERA)
Evaluating the Impact of Contamination and Industrial Activity on Ecosystems and Biodiversity
An Ecological Risk Assessment is the structured, science-based process of evaluating whether contamination or industrial activity poses an unacceptable risk to ecological receptors — plants, animals, soil organisms, aquatic biota, and the ecosystems they comprise. The ERA sits alongside the HHRA as one of the two pillars of risk assessment for contaminated sites. Regulators require that both human health and ecological risks are assessed before a site can be declared suitable for its intended use.
The ERA Framework
Problem Formulation
Defines assessment endpoints (ecological values to protect), identifies contaminants of concern, develops the ecological conceptual site model, and defines measurement endpoints. Receptors include soil organisms, aquatic biota, terrestrial wildlife, and vegetation.
Exposure Assessment
Estimates contaminant exposure for each receptor group. Considers bioavailability (total vs. available fraction), fate and transport modelling, and food chain bioaccumulation for substances like mercury, PCBs, and PFAS.
Effects Assessment
Determines concentrations causing adverse effects using species sensitivity distributions (SSDs), NEPM EILs, ANZG water quality guidelines, and site-specific ecotoxicity testing (earthworm survival, plant germination, algal growth, fish survival).
Risk Characterisation
Integrates exposure and effects into hazard quotients. Addresses uncertainty through sensitivity analysis. Determines whether ecological risk is acceptable, requires management, or requires remediation.
ERA and Site Management
The ERA directly informs remediation targets, which may be expressed as biological endpoints — restoration of soil ecological function, recovery of macroinvertebrate community health, re-establishment of native vegetation. These targets are more complex to define, measure, and verify than concentration-based targets, and require ongoing ecological monitoring. Management responses range from remediation to engineering controls (capping, barriers, constructed wetlands) to land management controls and ecological restoration programmes.
The Occupational Hygiene Connection
Field ecologists, soil scientists, and remediation workers on sites with ecological contamination are occupationally exposed to the same contaminants. The ERA and occupational hygiene monitoring plan should be developed in parallel, drawing on the same contamination data and conceptual site model. This integrated approach delivers better outcomes for the client, more defensible reports for the regulator, and better protection for both ecological receptors and human workers.
Commission an Ecological Risk Assessment
For projects involving both ecological and occupational health risks, OHConnect provides access to practitioners who deliver integrated assessments — ensuring ecological receptors, site workers, and future users are all protected.