QUANTIFYING ENVIRONMENTAL RISK OF GROUNDWATER CONTAMINATED WITH VOLATILE CHLORINATED HYDROCARBONS by

Water quality guidelines (WQGs) present concentrations of contaminants that are designed to be protective of aquatic ecosystems. In Australia, guidance for assessment of water quality is provided by the ANZECC and ARMCANZ (2000) Guidelines for Fresh and Marine Water Quality. WQGs are generally provided for individual contaminants, not complex mixtures of chemicals, where interaction between contaminants may occur. Complex mixtures of contaminants are however, more commonly found in the environment than singular chemicals. The likelihood and consequences of adverse effects occurring in aquatic ecosystems resulting from contaminants are generally assessed using an ecological risk assessment (ERA) framework. Ecological risk assessment is often a tiered approach, whereby risks identified in early stages, using conservative assumptions, prompt further detailed and more realistic assessment in higher tiers. The objectives of this study were: to assess and investigate the toxicity of the mixture of volatile chlorinated hydrocarbons (VCHs) in groundwater to indigenous marine organisms; to present a ‘best practice ’ ecological risk assessment of the discharge of contaminated groundwater to a