REMEDIATION
69,000 tonnes of soil removed
2.3M litres of contaminated ground water removed
What is remediation?
Land remediation is the process of restoring land to a standard that protects the environment, human health, or buildings.
Land remediation often entails the removal of pollutants or contaminants in soil, surface water, and ground water. It can also include more complex types of land remediation where the contamination remains in the ground but is stabilised through some means.
Since its inception, the Macquarie Point Development Corporation has been tasked with remediating the 9.3-hectare site known of as Mac Point.
For almost 200 years, Mac Point has been used as a farm, an abattoir, lumber yard, a gas works, cold store, goods storage, for heavy industry, rubbish disposal, the military, freight, and rail. As a result, the site’s soil and ground water has been heavily polluted over time with a combination of fuels, heavy metals, and other contaminants.
Why is there contamination?
Since colonisation, Mac Point has been a place of industrial needs for a growing population, and each time the site has built on what was there before, and then built on again and again, creating layer upon layer of coal and tar, grease and oil and concrete.
Contaminants found in the ground at Mac Point include:
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Asbestos pipe
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Spent fuel
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Coal tar
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Phosphorus and sulphur
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Heavy metals (arsenic, copper, lead, zinc, etc.)
Contaminants found in the groundwater at Mac Point include:
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Heavy metals
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Ammonia
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Cyanide
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E. Coli
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Spent fuel
In addition to removing contaminants, almost 1 kilometre of ageing oil and diesel pipelines, once used by industry and the navy over 50 years ago, have been removed.
To date:
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Nearly 2000 soil samples have been undertaken to map and confirm the removal of contamination
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69,000 tonnes of contaminated soil have been removed from Mac Point
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2.3M litres of contaminated ground water has been removed from Mac Point
What work has been done?
Remediation work started in 2015 after the appointment of a Project Remediation Consultant and subsequent Environmental Auditor.
This was followed by site investigations to understand the contamination on site, and to date has included:
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Soil investigations, soil bores and test pits at 250 locations across the site
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588 soil samples were analysed as part of the initial soil profiling and analysis
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65 groundwater wells on and off site were installed, making a total of 175 ground water monitoring wells on or near the site, with over 273 groundwater samples collected over 9 groundwater monitoring events
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the collection and assessment of 60 soil vapour samples and 27 ambient air samples, to assess if any potential current or future risk to Site users is presented from soil or groundwater impacts
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Removal of approximately 445L of light non-aqueous phase liquids (LNAPLs) from groundwater on site. LNAPLS are organic liquid contaminates such as gasoline, diesel, and other petroleum hydrocarbon products
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A further 1,190 soil samples as part of the remediation work so far, to confirm removal of the contaminated soil.
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A pilot trial is currently being finalised to inform the remediation of the former gasworks
What remediation work remains?
We have recently finished physical works at Audit Area 3, in the south-east corner of the site. This included the demolition of the old SeaRoads shed, removal of a historic pipeline and treatment and removal of excavated soil. The Corporation's Remediation Consultant is finalising documentation to issue to the independent Environmental Auditor to review the report to finalise and certify those works as being Development Ready.
The final key area to remediate is Audit Area 6 – in the south-west corner of the site (the old cold store site).
This parcel was added to the precinct in 2015 and requires the remediation of subsurface coal tar. A Development Application has been approved and the tender for the excavation works has recently closed and submissions are currently being assessed. Physical works are planned to commence in early 2024. This will see around 12,000m3 in contaminated material removed from the site, with a further 1,110m3 of tar-impacted material to be treated in-situ.
There is also a small section of land (Audit Area 4 East) where a historic diesel pipeline will need to be removed. This work is anticipated to be completed as part of the installation of the Northern Access Road.
Why has it taken so long to remediate the site?
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The Corporation was established in 2012, with an initial focus of establishing the statutory authority. Early consultation started in 2013.
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The site was initially leased by the Corporation, but the site continued to be used for rail operations until the last train left in mid-2014.
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An amendment was made in 2015 to the Act to provide a legislative framework with which to provide for a statutory audit pathway, as there was no existing framework to measure remediation against.
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The scoping of remediation work is determined based on site specific investigations to determine what contamination needs to be managed and what the intended future use of the area is.
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A remediation consultant was appointed to oversee this work in 2015.
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Because of the different nature and extent of contamination across the site 9.3 hectare site, it was not possible to achieve a single “sign-off” for the entire site before development commences.
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The remediation strategy divided the site into seven “audit areas”, to facilitate sign-off as remediation works and development proceeds across the site.
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This allowed the audit areas to be progressively scheduled, to ensure the sites are signed-off ahead of planned developments and to manage financial resources.
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This approach is consistent with other sites remediated in Australia. Remediation advice indicates other sites that have needed to manage similar contamination, including old pipelines and fuel contamination, and old gasworks, have taken between 10-25 years to safely complete. The Corporation is on track to complete physical remediation works by the end of 2024.