- Last updated:
- 12 Jan 2020
Council has successfully managed the ponded water at the Airport Expansion project site, largely through treatment and reuse on-site. As a result, council will not be releasing the ponded water to the ocean.
At its peak, it was estimated that 325 megalitres of rainwater had accumulated at the site, equivalent to 130 Olympic swimming pools.
Council worked closely with the Queensland Department of Environment and Science (DES) and qualified environmental specialists, to ensure the water would be removed in an environmentally responsible manner.
How was the water removed from site?
Council pursued a number of options for the release of the ponded water, with the prevailing dry conditions enabling council to remove the large volume of water through a combination of actions, over several months.
In October 2019, council proceeded with the option to install a Water Treatment Plant on-site. The plant processed around six megalitres of water per week, and the treated water was used to suppress dust, and for compaction around the site.
Due to the dry conditions, evaporation has also significantly contributed to reducing the volume of water on site.
Is the proposed pipeline still required?
As council needed to ensure all viable options remained available if needed, council proceeded to seek approval to construct a temporary pipeline, to allow the water to be released into the ocean in a controlled manner. This will now not proceed.
This decision to progress approval for the pipeline was based on information available at the time, about the potential for significant rainfall.
If heavy rainfall had occurred, the pipeline would have been necessary to prevent uncontrolled releases of fresh water into the Maroochy River estuarine environment.
As council has always advised the community, it was responsible and prudent to start mobilising a range of solutions, to manage the ponded water on-site.
As the water has been substantially reduced via other means, the proposed pipeline is now no longer needed.
How did the rainwater accumulate on-site?
The Rainwater Release program at Sunshine Coast Airport, was required to remove excess ponded water from the Airport Expansion project site.
The water accumulated on the construction site earlier this this year when above average rainfall was received and was unable to drain away, due to bunding installed to comply with the Airport Expansion’s environmental conditions of approval.
The bunding was in place to prevent ocean water entering the adjacent estuarine environment, when sand was pumped in for the new runway. As sand dredging and filling is now complete, the bunding is no longer required.
Will the problem reoccur?
Works have now occurred to enable the site to return to a self-draining area as it has always been, thus preventing further rainwater accumulation.
What was the cost to remove the water from site?
Council initially estimated the pipeline would cost approximately $2.5 million to construct. As it has not been necessary to progress beyond Development Approval, the actual cost was less than $50,000.
What environmental investigations were undertaken?
As this water contained low level concentrations of per- and poly-fluoroalkyl substances (PFAS), council worked closely with DES about solutions for removing the water from site.
To inform decision making around water removal options, council engaged qualified environmental specialists to undertake investigations at the site, in accordance with the PFAS NEMP, and other regulatory requirements. Detailed environmental investigations involved:
- targeted sampling and testing of local groundwater and the ponded water
- groundwater modelling
- monitoring, sampling and testing surface water and sediment
- sampling and testing of biota in the aquatic environment adjacent to and downstream of the project site
- ongoing liaison with relevant Federal and State authorities.
What was found?
Sampling results reported low level concentrations PFAS in the ponded water. Low levels of suspended solids and metals were also reported.
The reported concentrations of PFAS in samples from the ponded water were close to the laboratory limit of reporting (LOR). The LOR is the lowest concentration level that the laboratory is able to measure in a sample, with a reasonable degree of certainty. All samples are below health-based guidelines for recreational and drinking water.
How will soil be managed?
Now that the ponded water has been removed, any PFAS-impacted soil will managed in accordance with the PFAS National Environmental Management Plan (NEMP).
What are PFAS?
PFAS is an abbreviation for per and poly-fluoroalkyl substances. These are manufactured chemicals that have been used for more than 50 years.
PFAS are man-made compounds and have been widely used worldwide because they are resistant to heat, water and oil. They are in hundreds of everyday products, such as non-stick cookware, food packaging and clothing treated with Durable Water Repellent coatings.
They have also been used in industrial applications, including mist suppressants in the metal plating industry, hydraulic fluid in the aviation industry, and surfactants in the photography industry.
Since 1970, firefighting foams containing PFAS were once used extensively in Australia and elsewhere, due to their effectiveness in fighting liquid fuel fires.
PFAS do not occur in nature, and some take a long time to break down in the environment and can accumulate over time. As a result, there are constraints on the amount of certain PFAS chemicals that can be released safely into the environment.
The Management of Ponded Site Water report outlines considerations that led to council’s support for the Water Release Program.