Background

In August 2020, a large number of truck and car tyres caught fire at a rural site at Boxers Creek, NSW. The fire was extinguished by the NSW Fire Brigade, but there was concern that the burnt tyre debris may have contaminated the soil and water in the nearby dam..

Investigation

A detailed contamination site investigation was undertaken by Earthwise Environmental (EE). The investigation included a site inspection, soil and water sampling, and laboratory analysis.

The soil test results found elevated concentrations of total recoverable hydrocarbons (TRH) and zinc over the area of the burnt tyres. TRH exceeded the ecological screening level (ESL) and zinc exceeded the health investigation level (HIL).

Water test results from the nearby dam had slightly elevated aluminium concentrations (compared to dam water sampled further up gradient) but it did not exceed the assessment criteria.

Remediation

Given the exceedances of the assessment criteria EE outlined a remediation plan which involved the removal of the burnt tyre debris, mixing of the soil layers, topdressing the area with clean topsoil and revegetation of site with native grasses to return ground cover.

Validation

After the remediation was completed, EE undertook a follow-up validation study to confirm whether the site had been successfully remediated. Soil tests results confirmed TRH and zinc concentrations below the ESL and HIL assessment criteria and issued a clearance certificate for the client.

Conclusion

The case study demonstrates the importance of conducting a thorough contamination investigation and implementing appropriate remediation measures. EE was able to save the client time and money by outlying the detailed site investigation findings and including a remedial action plan within the one report. The follow-up validation study confirmed that the remediation was successful and that the site is now safe for future use.