In 2009 BHP engaged Thiess Services (now Ventia Utility Services) as the Principal Contractor on the $405m Hunter River Remediation Project. This involved removing, immobilising, transporting and encapsulating 1,200,000m3 of sediment, of which 800,000m3 was contaminated. This is the largest remediation project ever undertaken in Australia and involved managing and controlling a number of potentially significant environmental issues. It was also one of the most regulated projects in Australia requiring more than 260 statutory approvals.
The former BHP-owned Newcastle Steelworks operated for 84 years from 1915 and was, at its peak, the largest steelworks in the Commonwealth. During this time, by-products from the steelmaking made their way into the neighbouring Hunter River, settling in the sediment alongside the steelworks site. When the steelworks closed in 1999, BHP committed to clean up those areas of the Hunter River affected by its activities.
The primary contaminants included polycyclic aromatic hydrocarbons (PAHs) derived from the coking of coal used in the steelmaking process. Coal tar, a by-product of the coke ovens, was also released into the environment through leaks, spills and disposal to waste pits.
We were responsible for three components of the remediation:
- marine remediation – dredging
- stabilisation treatment – cement stabilisation of the river sediments on land at the Mayfield site
- off-site landfill – transporting treated sediments by truck along major arterial roads to a new landfill facility on former industrial land at Kooragang Island.
Successfully managing specific challenges for excellent results
There were no environmental incidents during the project, no pollution, and no adverse impacts on the river water quality or health of the ecosystem. This was despite inherent environmental risks associated with the location of this project – it’s close to residential areas, sensitive marine environments and native habitats.
Our success was due to the resourceful and innovative initiatives our team implemented to meet project-specific challenges and manage the associated environmental risks, including:
- accurately pre-determining contaminated material and protecting the river during dredging by implementing engineering and real-time monitoring controls
- mapping contamination spots using 3-D modelling based on extensive data analysis
- reducing the potential for odour impacts on the community through modelling, engineering and 24/7 monitoring
- protecting groundwater at the new landfill facility by installing leading edge liner systems and developing new criteria to provide additional insurance
- conserving as much native habitat as possible
- protecting the Green and Gold Bell Frog by undertaking a compensatory habitat program
- strengthening our regulatory compliance by developing benchmark compliance tracking systems
- developing excavated materials and odour management plans, including constructing fully enclosed stabilisation buildings for odour control
- implementing a leachate management system at the Kooragang Island Waste Emplacement Facility
- preventing pressure building up and potential damage to the geo-membrane capping barrier by installing a gas relief system in the cap of the landfill.