Detailed Quantitative Risk Assessment

A detailed quantitative risk assessment (DQRA) is an advanced, site-specific evaluation of the risks to human health and the environment from contaminated land or groundwater. It builds upon the findings of preliminary risk assessments and site investigations to provide a more detailed and quantitative characterisation of exposure, toxicity, and risk.  

DQRA uses mathematical models, statistical methods, and site-specific data to estimate contaminant fate and transport, receptor exposure, and potential health or ecological impacts. It provides a more refined and defensible assessment of risk than generic or screening-level approaches, and supports informed decision-making and risk management. 

A DQRA is typically required when: 

• A preliminary risk assessment or site investigation identifies potentially significant contamination risks that cannot be adequately assessed using generic or screening-level approaches 

• Site-specific conditions, such as complex hydrogeology, heterogeneous contamination, or sensitive receptors, require a more detailed and tailored assessment of risk 

• Regulatory requirements or planning conditions specify the need for a DQRA, based on the nature and extent of contamination, the proposed land use, or the sensitivity of the environment 

• Risk-based remediation or development decisions require a more robust and defensible assessment of contaminant fate, transport, and exposure, to optimise risk management strategies and minimise costs and liabilities 

The key components of a DQRA typically include: 

Problem Formulation 

Defining the scope, objectives, and boundaries of the risk assessment, based on the findings of preliminary assessments and stakeholder input 

Exposure Assessment 

Characterising the pathways and routes by which receptors may be exposed to contaminants, using site-specific data on land use, receptor activities, and exposure factors 

Toxicity Assessment 

Evaluating the potential health or ecological effects of contaminants, using dose-response data, toxicity criteria, and uncertainty factors 

Risk Characterisation 

Combining exposure and toxicity estimates to quantify the magnitude and likelihood of potential impacts, using deterministic or probabilistic methods 

Uncertainty Analysis 

Identifying and quantifying sources of uncertainty and variability in the risk assessment, using sensitivity analysis, Monte Carlo simulation, or other techniques 

Risk Management 

Developing and evaluating options for managing or mitigating identified risks, using risk-based criteria, cost-benefit analysis, and stakeholder input 

• The advantages of using a DQRA approach include: 

• Providing a more realistic and site-specific assessment of risk, based on detailed characterisation of contaminant fate, transport, and exposure, rather than generic or conservative assumptions 

• Supporting more targeted and cost-effective risk management strategies, by focusing on the most significant contaminants, pathways, and receptors contributing to overall risk 

• Enabling the development of risk-based remediation objectives and options, based on site-specific conditions and stakeholder needs, rather than generic or prescriptive standards 

• Facilitating regulatory compliance and stakeholder communication, by providing a transparent, defensible, and scientifically robust assessment of risk, supported by detailed documentation and expert review 

• Reducing uncertainty and conservatism in risk estimates, by using probabilistic methods to characterise variability and uncertainty in key input parameters, such as exposure factors and toxicity values 

The limitations and challenges of DQRA include: 

• Requiring more extensive and site-specific data on contaminant concentrations, soil and groundwater properties, receptor characteristics, and exposure factors, which may be costly or time-consuming to obtain 

• Relying on complex mathematical models and assumptions about contaminant fate, transport, and exposure, which may be subject to uncertainty, variability, and model error 

• Requiring specialised expertise and tools in risk assessment, modelling, and data analysis, which may not be available or affordable for all projects or organisations 

• Potentially leading to more complex and lengthy regulatory reviews and stakeholder consultations, due to the technical and site-specific nature of the risk assessment approach 

• Requiring careful communication and interpretation of risk assessment results and uncertainties, to avoid misunderstandings or misuse of the findings by non-technical audiences or decision-makers 

Lucion’s DQRA services can benefit your project in several ways: 

• Providing a comprehensive, scientifically robust, and legally defensible assessment of the risks to human health and the environment from contaminated land or groundwater, based on state-of-the-art modelling tools and best practices 

• Supporting informed and risk-based decision-making on remediation, development, and risk management options, by quantifying the magnitude and likelihood of potential impacts and evaluating the effectiveness of different risk management strategies 

• Facilitating regulatory compliance and planning approvals, by demonstrating that the risks associated with contamination have been adequately assessed and managed, in accordance with relevant guidance and standards 

• Communicating and justifying the risk assessment approach and conclusions to stakeholders, regulators, and the public, using clear, transparent, and accessible reporting and visualisation methods, supported by our expertise in risk communication and stakeholder engagement 

• Providing expert advice and support throughout the entire DQRA process, from problem formulation to risk management and verification, drawing on our extensive experience and knowledge of contaminated land risk assessment and management 

• Delivering reliable, efficient, and value-added services that help you manage contamination risks effectively, minimise project delays and costs, and protect human health and the environment, while achieving your commercial and reputational objectives