When Energex wanted to prepare the old Toowoomba Gasworks site for sale and redevelopment in 2012, it faced a major remediation challenge.
The valuable site was heavily contaminated as a result of industrial waste disposal practices dating back to the 19th century. First established in the 1870s by the Toowoomba Gas and Coke Company, the Gasworks were an important public utility for the region for more than 100 years.
Recognising our expertise and experience in remediation, Energex commissioned Thiess Services (now Ventia Utility Services) to undertake this complex work.
There were two primary objectives for the project:
- remediate the site to a standard that did not compromise or put at risk the health of the community or cause an unacceptable impact on the local environment
- mitigate environmental and human health risks through strict environmental control measures.
Managing multiple challenges
We needed to demolish structures that were still on the site so we could access the contaminated soils. This demolition work involved removing and safely disposing of asbestos roof sheeting, and salvaging recyclable materials such as steel, timber and rubble.
After demolition was complete, 100,000 tonnes of contaminated soil were removed and sent to a licensed facility to be safely encapsulated. We backfilled the site with clean soil from a nearby quarry.
During the remediation process we also had to protect the live gas mains running across the site.
Large volumes of contaminated water were pumped into holding ponds before entering a water treatment plant. The temporary plant was designed and constructed by Ventia where it the contaminated water was properly treated before discharge to the sewer.
We constructed a large odour control enclosure over the most heavily contaminated part of the site. This helped contain offensive odours and also minimised dust. Numerous deodorising misting sprays were also used around the site to intercept and neutralise odours.
To ensure the safety of workers exposed to contaminant vapours, we monitored benzene, polycyclic aromatic hydrocarbons (PAH) and volatile organic compounds (VOC) levels in real time.
Community engagement was also important to the project. Open days, a project website, letterbox drops, a 1800 phone number, newsletters and a contact register all provided the local community with key information throughout the project and a feedback loop for questions or concerns.
Snapshot of scope of works
- Remediation planning
- General site preparation and operation
- OHS and environmental controls – monitoring for dust, odour, noise and vibration, excavation fencing, safety barricades, site demarcation
- Water management and treatment
- Odour control
- Excavation, transport and disposal of contaminated material
- Stabilisation to site boundaries
- Traffic management
- Backfill and reinstatement
- Site demobilisation.