Restoring a Protected Coastal Area from Hydrocarbon Contamination

In 2018 Cardno was contracted by a major oil company as Principal Contractor for removal of subsurface hydrocarbon contamination from a protected foreshore area in regional Victoria, Australia. Cardno is a global provider of integrated professional services. 

Remediation of the site was achieved by establishing an on-site sand washing plant and processing over 70,000 m³ of contaminated sand over a 12-month period. Cardno has managed all technical, commercial, compliance and safety aspects for the project.

During the investigation phase, RemScan was identified as a key technical enabler for the project. An initial study was conducted by Cardno and Ziltek to verify the calibration of the RemScan against NATA laboratory results. On the basis of this study, the independent Environmental Auditor accepted the use of the RemScan as the primary analytical tool for analysis of hydrocarbons in soil during the remediation, with QA/QC samples analysed at a NATA accredited laboratory to ensure ongoing reliability of the results.

RemScan was used to:

• Classify the excavated sand, to determine if it needed treatment or not, and to segregate pre-treated stockpiles based on the level of impact.
• Validate the walls and floor of the excavation, and/​or determine if there were areas of impact that needed​“chasing out”.
• Monitor the sand washing process, providing real-time feedback for control and optimisation of the process. 
• Validate the treated sand, to classify it as suitable for backfill or requiring further treatment.

Ziltek worked with Cardno to establish an initial calibration for the site and to monitor and maintain the accuracy of the calibration over the lifetime of the project. The calibration was easily updated several times during the project using the validation data, to account for minor changes in the geology across the site.