Remediation works, involving the clean up of contaminated sediments in Kendall Bay is progressing well, with the Insitu-stabilisation (ISS) work commencing this week (w/c Feb 24). The ISS works involve the pumping of marine cement into the contaminated sediments below the surface, to form a raft like structure and contain the contaminated sediments permanently.
Work completed to date has included the establishment of the Staging Site at 140 Tennyson road and installing the majority of the environmental controls, including the installation of the Northern sheet pile walls, the outer and inner silt curtains, the bubble curtains and work continues on southern sheet piles – due to be completed in March 2020.
The Sheet pile wall in the North was completed within ~4.5 weeks, well in advance of the initial estimated ~8-10 weeks that were scheduled. This allowed a good respite period over the Christmas/New Year period.
The use of Bubble curtains (whereby a compressor supplies air which blows up bubbles to surface) has been adopted in areas to act as access gates. These bubble curtains control turbidity in the water while allowing for boats/barges to move through the gating areas efficiently, without having to open and close any physical structure.
Sediment removal in the southern area (to enable the larger equipment/barges to access this shallow area) requires an excavator to remove the sediments and place into purpose built (blue) bins. The bins are then closed to limit the time the sediments are exposed to reduce the potential for odour. The barges transport the bins back to the Staging site whereby they are transported offsite for treatment and disposal.
Impacts associated with the works include the potential to create odour, intermittent noise and a visual sheen on the surface of the water in the vicinity of the works. Stringent controls and mitigation measures are in place to manage these impacts, as well as Environmental Monitoring for Water Quality, Noise and Air Quality (Odour). No readings have been outside the Project compliance criteria to date.
Jemena’s Community Liaison Manager, Barbara said that the local community had been patient and supportive of the works. “ Residents have been very understanding and appreciative of these important environmental works that will ultimately leave a lasting legacy”.
The project is on schedule to be completed in December 2020, weather and site conditions dependant.
Jemena is an infrastructure company that builds, owns and maintains a combination of major electricity, gas and water assets. It supplies millions of households and businesses with essential services every day.
Jemena operates in New South Wales, Victoria, and Queensland. In NSW, Jemena owns and manages gas transmission and distribution pipelines. These gas pipelines enable the transfer of natural gas directly to over one million NSW households and businesses.
A specialist and experienced remediation contractor, Ventia will manage the remediation activities.
The remediation of Kendall Bay is required by the NSW Environmental Protection Authority (NSW EPA) to address the health and environmental risks posed by the contamination.
A key objective of the Project is to ensure the long-term protection of the health of users of the Kendall Bay foreshore and recreational users of the waterway from potential impacts from historic gas-works related contamination. This includes the southern beach and adjacent mangrove area where gasworks contaminated sediment are currently exposed at low tide. Sediments within Kendall Bay were impacted with the by-products of the former gasworks facility operated by AGL at the Mortlake site. The former Mortlake gasworks site has previously been remediated and redeveloped and is now known as Breakfast Point.
Regular Occupational Health & Hygiene assessments will be undertaken during the works to address site-specific requirements to manage potential risks to the health and safety of workers and the public. This will include monitoring on the work barges and on the shoreline of Kendall Bay. Monitoring was undertaken during the trial works within Kendall Bay and these assessments showed no correlation between detectable odour and health risks. Monitoring of volatile organic compounds (VOCs) was undertaken on the foreshore of Kendall Bay and no VOC concentrations were detected.
Jemena submitted the formal remediation application, including an Environmental Impact Statement (EIS), to the Department of Planning, Industry and Environment (DPI&E) in 2018. The EIS includes technical studies to assess potential impacts, including (but not limited to) community impacts, marine ecology, visual impacts, traffic, dust and odour, and acoustics analysis.
The application was exhibited publically for a period of 30 days, allowing the public the opportunity to review and comment on the project application, EIS and technical studies during the Public Exhibition period. All submissions were considered by the Department during the assessment of the application.
The DPI&E determined Project consent on 31st May 2019.
Jemena continues to liaise with the relevant government agencies, including the Department of Planning (DPI&E), RMS, NSW Health, NSW Fisheries and the Environment Protection Agency (EPA) to implement and manage the project.
The Environmental Impact Statement (EIS) was required as part of the planning process under Part 4 of the NSW Environmental Planning and Assessment Act 1979. Part 4 of the Act applies to all State Significant Developments (SSD).
As part of the EIS process, a number of specialist environmental reports were prepared. These reports address issues such as:
The application and all supporting documentation was publicly exhibited for 30 days.
DPI&E consent for the project was received in May 2019, and remediation works - starting with mobilisation to the Tennyson Road Staging site will commence in September 2019.
The Remediation work is scheduled to be completed within a 15 month period (weather and site conditions dependant) - commencing in September 2019.
The areas requiring remediation (Remediation Area A and B) were identified following comprehensive technical investigations. They are directly related to past activities associated with the former AGL Mortlake Gasworks, including a loading and unloading wharf and a storm drainage pipe (Remediation Area A) from a gasworks containment structure. Contamination levels in the rest of the Bay are largely considered to be representative of the whole of Sydney Harbour.
After remediation activities are complete, Jemena may sell the land on the open market however a decision has not been made yet.
Truck movements will vary in numbers as we move through each stage of the project. Greater vehicle movements will be expected during the loading out of excavated material, and when significant materials are being delivered to the site (for example; sheet piles, mooring piles, fuel and marine cement, imported clean sand, and other materials). The number of truck movements has been greatly reduced from previous proposals with the treatment of materials now occurring in-situ within Kendall Bay.
As part of the EIS, the air quality impact assessment will determine potential air quality (odour and dust) impacts associated with the operation of remediation works. There is not expected to be significant dust associated with the works, however the sediments are odorous and, although controls will be in place, residents may experience occasional odours.
Jemena's Staging site at Tennyson Road will be used as the Project Management Office as well as for mobilising operations to the water and for unloading excavated materials barged from the bay (in covered bins) to trucks for off-site treatment and disposal.
Only one mangrove at the north of the western shoreline will be removed.
Jemena was required to complete an Environmental Impact Statement (EIS). The EIS fully assesses potential impacts associated with the identified site access option, including (but not limited to) noise, odour, marine ecology and traffic. Where impacts are identified over the adopted criteria or where a disturbance to the community is considered, mitigation measures are developed to provide guidance on how to lessen or prevent impacts to the community.
Jemena will continue to communicate with the community during the progression of the works. Members of the community have had the opportunity to comment and provide input into the EIS process, and the approval of the project by the DPI&E takes this feedback into consideration. For more information on the planning process please see below ‘What is the Planning Process’.
The sediments present in Kendall Bay currently can have a strong unpleasant tar and hydrocarbon smell at low tide even with no remedial activities being undertaken in the Bay. There is potential for a similar odour to emanate from a number of sources during the remediation works, including through excavation of material from the Bay.
Odour modelling based on conservative assumptions showed that none of the chemicals relevant to the gasworks waste is predicted to be present in shoreline locations at concentrations that are above conservative ambient air quality guidelines. The Project is therefore not expected to result in adverse health impacts for surrounding residents and pedestrians along the promenade. It is possible that unpleasant odours will be noticeable at times but only for short periods.
Overall the remediation works will have beneficial impacts to the community by removing or containing the contaminated sediments which are the current source of the odour.
As part of the EIS, a traffic impact study has been undertaken, along with several other specialist studies. Measures to assist mitigating the impact of trucks include a Traffic Management Plan that identifies an approved truck route and the restriction of truck movements within operational hours.
A detailed assessment of alternative routes and a traffic impact assessment concluded that heavy vehicle movements generated by the Project will be less than 1% of the total vehicle traffic within the local road network at present.
Jemena has consulted with the local community since 2004 during the initial Project planning and investigation stages. This consultation has included stakeholder briefings, community information stalls, feedback sessions, surveys and the formation of a Community Liaison Group (CLG).
Materials and information displayed and notes taken during consultation activities are available on the Jemena Project website for broader interest and reference.
Moving forward, we always welcome your feedback and encourage you to register and communicate with us via this Portal.
(Pictured left to right: Ciaran, Joabie, Allan, Stephen, Steve, Nader, Brendan, Jay, Nigel, Pat.)
Ventia is one of the largest infrastructure service providers in Australia and New Zealand.
Ventia’s Environmental Services team is made up of people who have been transforming contaminated land and waterways using innovative, technology-driven remediation solutions for more than 30 years.
With over 140 environmental remediation projects successfully completed in Australia and internationally, the Environmental Services team has dealt with a diverse range of contaminants from industry and other sources.
Remediating soil, sediment, surface water and groundwater, our team has restored many sites to safe and productive spaces for the community.
Ventia’s internal capabilities include:
Our team develops site-specific solutions, informed by rigorous data analysis, to effectively manage each remediation project’s unique risks.
Putting safety and health above else, protecting communities and local environments is always Ventia’s priority.
Major projects by Ventia Environmental Services include: