ENVIRONMENTAL site assessment

Detailed Site Investigation - Remedial Action Plan - Site validation and Monitoring

Enivronmental Site Assessments

An Environmental Site Assessment (ESA) is undertaken determine the likelihood or extent of contamination on a site. The requirement for an Environmental Site Assessment is often triggered by a change in land use during the Development Application. In NSW the environmental site assessment is undertaken in accordance with the National Environmental Protection Measure (Assessment of Site Contamination) guideline and best industry practices.

Environmental site assessments consist of one to four stages as follows:

  1. Preliminary site investigation
  2. Detailed site investigation
  3. Remediation action plan
  4. Site validation and ongoing monitoring

Stages two to four are only required if the previous stage shows a necessity or is inconclusive. If there is known contamination on a site, the preliminary and detailed site investigations will be completed simultaneously to save time and money for the client.

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Preliminary Site Investigation

A preliminary site investigation (PSI) is the first stage of an environmental site assessment. The report:

  • Identifies past and present potentially contaminating land use activities
  • Identifies potential contamination types
  • Discusses the site condition
  • Provides a preliminary assessment of site contamination
  • Assesses the need for further investigations

An appraisal of the site history is fundamental to the preliminary site investigation and may be used to identify site contamination. During a site investigation it is important to review and assess all relevant information about the site, including information obtained during a site inspection. A site investigation will determine whether further testing is required based upon:

  • If a complete site history clearly demonstrates that site activities have been non-contaminating, there may be no need for further investigation or contamination sampling.
  • If contaminating activities are suspected or known to have occurred, or if the site history is incomplete, it may be necessary to undertake a preliminary sampling and analysis program to assess the need for a detailed site investigation.

Detailed Site Investigation

A detailed site investigation (DSI) is the second stage of an environmental site assessment. The report should provide information on the:

  • Issues raised in the preliminary site investigation
  • Type, extent and level of contamination
  • Potential contaminant dispersal
  • Potential effects of contaminants on public health, the environment and building structures
  • Adequacy and completeness of all information used in the decision-making process, and
  • Recommendations for moving forward

Soil contamination sampling and testing at a NATA accredited laboratory is completed during the detailed site investigation. The results from the soil laboratory testing is used to create a detailed site concept model, showing the location, depth and extent of the contamination.

If the detailed site investigation indicates that the site poses unacceptable risks to human health or the environment, under either the present or the proposed land use, then a Remedial Action Plan needs to be prepared and implemented.

Site Remedial Action Plan

A Site Remedial Action plan is the third stage of an environmental site assessment and should:

  • Set site remediation action goals that ensure the site remediation will be suitable for the proposed use and will pose no unacceptable risk to human health or the environment
  • Document in detail all procedures and plans to be implemented during the site remediation to reduce risks to acceptable levels
  • Establish environmental safeguards to complete the site remediation in an environmentally acceptable manner
  • Identify and include proof of approvals and licenses required by regulatory authorities

Once site remedial work is complete, a report is prepared detailing the work conducted, and regulatory decisions made.

Site Validation and Ongoing Monitoring

A site validation report is the fourth stage of an environmental site assessment. When a remedial action plan has been carried out a site validation is performed to ensure that the objectives stated in the remedial action plan have been achieved. The extent of site validation will depend on:

  • The degree of contamination originally present
  • The type of remediation processes that have been carried out
  • The proposed land-use
  • Validation must confirm statistically that the remediated site complies with the clean-up criteria set for the site

If site validation targets have not been achieved, reasons must be stated and additional site work proposed to achieve the original remediation action plan objectives. The site validation report includes an assessment confirming that all regulatory authorities’ license conditions and approvals have been met.

When a full site clean-up is not feasible or on-site contamination containment is proposed, an ongoing monitoring program should be assessed. If a monitoring program is required, details of the proposed monitoring strategy, parameters, locations, frequency, and reporting requirements are provided.


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