Risk Assessment

Risk Assessment is an internationally excepted scientific method used to evaluate adverse impacts site contamination may present to public health and the environment. In Europe and the USA Risk Assessment is routinely applied to contaminated sites of all sizes and complexity. It is a powerful tool for contaminated site management and remediation which offers significant savings. In its simplest form it is a process of estimating the daily contaminant intake rate site occupants may be involuntary exposed to from chemical contamination. The daily intake rate is derived by multiplying the chemical concentration at the point of exposure by the duration of exposure. These two principals are vital for understanding the power of risk assessment.

The chemical concentration at the point of exposure is derived using mathematical models which estimate the contaminants ability to migrate through soil, water, groundwater and air (environmental media). The concentration at the point of exposure is related to physico-chemical properties and physical properties of the environmental media. For example a release of volatile chemical in sandy soils will present a greater concern than a release in clay soils because vapors will migrate easily through permeable sand than clay. Therefore higher levels of contamination can be left in place in a clay soil than a sandy soil. The higher the level of contamination that can be left in place the less money you will have to spend investigating and remediating.

Similarly, how the chemical enters into the body (exposure route) and the duration of that exposure is used to estimate the daily intake rate. The behaviour of site occupants and the land-use will dictate the exposure route and duration. For example chemical exposure would be greater on a residential property because the time spent at home is considered to be greater than the time spent in the workplace. Therefore the level of contamination that can be left in place at a commercial property will be greater than what can be left in place at a residential property.

National and State investigation levels presented in Environmental Reports are used to compare contamination levels. Those investigation levels were derived by Risk Assessment using conservative assumptions for environmental media and exposure rates. They are not acceptance levels. Acceptance levels can be derived for your specific site conditions and in almost all cases will result in significant savings. If you have a remediation system in place, ask yourself what target cleanup levels have been adopted? When will the system be turned off? Geo-Logix can appraise, review and derive cleanup goals for remediation. If we can establish less stringent cleanup goals we can reduce the running time of the remediation system and offer significant savings.

Risk assessment is not frequently applied to contaminated sites in Australia, in part due to a lack of understanding, complexity, and misguided perception that it is only useful on large contaminated sites. Geo-Logix Director David Gregory has conducted Risk Assessments in the USA and Australia and is well experienced to provide you with a quick appraisal of the benefits of Risk Assessment for your circumstance. Through Risk Assessment Geo-Logix can offer the following benefits for your contaminated site:

• Review your contaminated site environmental reports and provide an appraisal of the benefits risk assessment may offer;

• Identify risks contamination may present to your site and design a directed site investigation to enable a quantitative assessment of risk;

• Derive site specific investigation/acceptance levels;

• Derive site specific cleanup goals for sites with existing remediation systems, or sites about to undergo remediation; and

• Identify appropriate remediation technologies and design to optimize remediation effectiveness.

Feel free to contact Geo-Logix on the benefits of Risk Assessment.