Jemena manages multiple legacy contaminated sites, which have been impacted by historical gas production and its associated infrastructure (Gasworks). These assets including the former Goulburn Gasworks were acquired through a business transaction and have been managed to ensure long term environmental risks are reduced or mitigated through our priority site management regime which incorporates the systematic approach of the Jemena Asset Management System. This forms a critical part of Jemena’s commitment to managing the full-life cycle of its assets including maintaining, monitoring for compliance and ensuring the correct retirement of an asset, as demonstrated by the successful delivery of the remediation of the former Goulburn Gasworks.
Introduction and Use of Best Practice
The former Goulburn Gasworks operated from 1879 until the 1970s when the production of gas through coal gasification ceased. The historical gasworks-related operations and waste handling contaminated the soil and groundwater on- and immediately off-site along the adjacent foreshore area of the Mulwaree River, which forms part of the Sydney water drinking catchment.
The remediation works, which was completed in December 2019, represents a significant achievement in the close out process of asset management life cycle particularly after an acquisition of a poorly decommissioned asset. The project demonstrated how asset disposal can validate and improve the effectiveness of a company’s asset management practices and future due diligence procedures.
Upholding the best practice asset management principles includes, focusing on the complete asset life-cycle of the physical asset as well as its associated liabilities related to its operation and maintenance, ensuring that no damage occurs to the environment or community. In contrast to this, the Goulburn Gasworks was operational and decommissioned at a time when environmental compliance was non-existent across industries and in-turn lead to significant environmental harm both on- and off-site.
The primary objective of the project was to remove the potential of significant environmental harm caused by the ongoing contamination from the remaining gas production infrastructure while taking the opportunity to harness potential social, environmental and economic benefits for the people of Goulburn.
This remediation required a solution which could meet the company objectives as to retiring and disposing of the asset with a triple bottom line approach, while removing the statutory and regulatory compliance requirements.
The remediation required many innovative solutions to ensure it achieved the objective of reducing potential environmental harm both on-site at the former gasworks and off-site along the foreshore area, adjacent the Mulwaree River.
On-site the project scope included:
i) the construction of a 90 m long subterranean low permeable barrier wall between the site and foreshore area – to stop groundwater flow towards the River;
ii) cleaning and decommissioning of all below ground assets including tanks, pipes, structures and gas holders;
iii) removal of 270 tonnes pure tar for off-site destruction;
iv) ex-situ stabilisation of tar-impacted soils with powdered activated carbon (undertaken within a purpose built environmental enclosure); and
v) reinstatement and planting of ~2,500 native trees, shrubs and grasses across the site.
Off-site, the project scope included:
i) the removal and treatment tar within natural material at depth along the foreshore of the river;
ii) removal of fill and asbestos impacts across the embankment;
iii) the geotechnical repair of the embankment separating the former gasworks site and foreshore area; and
iv) reinstatement of the bike track, road and revegetation of ~4,500 native trees, shrubs and grasses across the Council owned area. With the vegetation selected with input and assistance from Council and local community groups.
Project Program and Management
The project required multiple intrusive investigations over many years, to assess, delineate and ensure any remediation works undertaken achieved complete compliance and reduced/removed long term liabilities.
The focus of the project was minimising impact to the community, ensuring a sustainable approach to the remediation and achieving a the best long term outcome whilst considering the environmental, social and economic aspects (triple bottom line) of asset management activities.
The remediation was managed and overseen by Jemena’s Major Project Remediation Team and was undertaken between Nov 2018 to Dec 2019.
Project Team
The project team involvement was critical in the project’s success, the team included a subject matter expert project manager, dedicated project support team and business support functions. Due to the complexities in the project, the team produced detailed and targeted scope requirements and consistently assessed risks and successfully managed complex issues to ensure the successful project delivery.
Ingenuity The project required multiple alternative approaches to the overall methodology to ensure the works met the triple bottom line and overarching objectives. This required the implementation of multiple remediation methodologies including many first of a kind, including construction of a secant pile/soil low permeable wall to reduce groundwater flow and thermal treatment of pure tar. The on-site treatment methodology reduced the impacts to surrounding local infrastructure by removing over 2,500 truck and dog movements
The project team utilised drone surveys to both manage material excavation and overall remediation progress. The drone footage provided another benefit whereby stakeholders were kept up to date with frequent drone images, demonstrating the scale and measurable project performance.
The project team utilised drone surveys to both manage material excavation and overall remediation progress. The drone footage provided another benefit whereby stakeholders were kept up to date with frequent drone images, demonstrating the scale and measurable project performance.
from the transport and treatment of contaminated material off-site. Another benefit of the project, was improving the aesthetics and function of the foreshore area which really demonstrated Jemena’s commitment and thanks to the community. The foreshore works included:
- the decommissioning and realignment underground of overhead powerlines to ensure unfettered access to contamination and improve amenity;
- reinstatement of imported clean material and placement of native vegetation with input from Council and local community groups;
- re-installation of a renewed bike path with the addition of a two donated park benches; and
- removal of fly-tipped asbestos and geotechnical repair of the embankment separating the former gasworks site and foreshore area.
Social Benefits at a Glance
- Majority of the contractors and suppliers were local Goulburn businesses. Over 50,000 local project hours or 85% of the time on project.
- Council foreshore area re-instated with native vegetation, upgraded bike path and donated park bench.
- Protection of an on-site building with heritage significance.
Finally, one of the project’s critical obstacles was transformed into an opportunity to provide support to the nearby drought-affected golf course. Jemena received a NSW EPA Resource Recovery Exemption and Order which allowed the application of treated and validated water from the water treatment plant to golf course fairways. This offered significant benefit to the project and community through the upgrading of golf course assets and reduced water consumption.
Proactive Stakeholder Engagement
To facilitate the remediation of the former Goulburn Gasworks, the project team undertook substantial engagement and advocacy with a range of government and public stakeholders. The focussed engagement was undertaken to ensure all stakeholders supported and understood both the objectives and methodology required to undertake and complete the remediation successfully. The effectiveness of the stakeholder engagement process was evident prior to the remediation when no objections were made to the development application were made. We continued our open engagement with a community open day, allowing unfettered site access and tours from the Jemena project team personnel through the site’s water treatment plant, odour control enclosure, ex-situ stabilisation process as well as access to the health and safety equipment required for the works.
The proactive engagement with the NSW EPA, Goulburn Mulwaree Council, Water NSW, Local Aboriginal Group, multiple Heritage Associations, DPI Water, Crown Lands, local community and groups proved pivotal in the project’s ability to succeed.
Engagement at a Glance
Four community engagement and information sessions as well as two project open-days with unfettered access to the site.
Continuous project notifications and updates to the local community and regulators.
Additional Supporting Information
Jemena has provided additional supporting documentation and images to further support the submission, these demonstrate the projects ingenuity, use of best practice and the benefit the project provided to the community and include the following:
- Project Photographs
- Community and Industry Open Day Photographs
- Letter from Goulburn Mayor
Attachment A – Project Photographs
Four weeks into the remediation project.
Mid-way through the remediation works. Large historical infrastructure from the former gasworks can be seen in the excavation area with the large odour control enclosure in the background. The works along the Mulwaree River foreshore area are well underway in the right of the image.
Remediation works completed successfully.
Through the use of on-site remediation there was a reduction of 8,800+ tonnes of CO2 emissions.
Site personnel inspecting the on-site treatment process.
The team successful completed the remediation of the foreshore area, with no environmental incidents and no impacts to the Mulwaree River, a tributary of the Sydney Water drinking catchment.
The project team collaborated with the local community on the native vegetation selection for the foreshore area and the works included an upgrade of the bike path as well as the inclusion of two donated recycled park benches.
Attachment B – Community and Industry Open Day Photographs
Attachment C – Letter from Goulburn Mayor
