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The author of new stormwater guidelines that dictate how major Queensland development projects get approved says significant findings that showed past versions were flawed were wiped from a version published without his blessing.
Bligh Tanner civil engineer Alan Hoban says the Model for Urban Stormwater Improvement Conceptualisation (MUSIC), which developers use to align with state planning policy, have relied on incorrect data for about two decades, and has called for the state planning policy to be reviewed.
Earlier this year, Healthy Land and Water, the peak environmental body in south-east Queensland – which is funded by the state, councils and other stakeholders – contracted Hoban to update the guidelines, which had last been looked at in 2018.
Hoban, a former Healthy Land and Water employee and the 2020 winner of Queensland Engineer of the Year, played a key role in the establishment of the Queensland MUSIC guidelines in 2010 and 2018, which was only released as a draft.
This time, Hoban said he went back to the foundations of the first guidelines and found they were built on unreliable data.
“A lot has been learnt in the 16 years since the previous guideline was released, so we sought to go back to first principles and validate all the key input assumptions,” Hoban said.
“What we found was the earlier stormwater quality analyses were flawed, and they are based on a limited number of catchments for urban run-off – it’s only based off two catchments studied by Brisbane City Council.
“The catchments were clearly subject to contamination and didn’t have typical stormwater run-off.”
The flaws meant there was actually less stormwater run-off, and it was much cleaner than the MUSIC guidelines assumed, he said.
“The implication is there is far less pollution coming off developed urban catchments than has been previously assumed,” Hoban said.
He said the bungle meant the underlying assumptions for the business case he helped prepare, which informed state planning policy, was wrong.
“There’s not the acute problem with sediment and nutrients that’s been previously assumed, and was used to support the implementation of the planning policy,” he said.
Because of this, developers have been spending millions of dollars on stormwater quality control, such as underground cartridge systems that filter water and have high upkeep costs, Hoban said.
When he learnt Healthy Land and Water intended to release the draft guidelines with the outdated data, Hoban wrote to Queensland environment minister Andrew Powell and the department director general expressing his dismay.
That letter was sent on April 14. The following day, Hoban received an email from Healthy Land and Water chief executive Julie McLellan who was angered by the letter, but offered to meet with the engineer in May.
Despite this, the draft guidelines were released for stakeholder consultation on Tuesday using the data Hoban claimed is outdated.
“What they’re doing is censoring the science to hide from the minister, and the broader industry, the fact that urban stormwater pollutant loads have been systematically overstated, and that the state planning policy is in need of a review,” he said.
The back-and-forth follows reporting by this masthead earlier this week that Healthy Land and Water had paused a long-running toxic algae monitoring program in Moreton Bay as part of a broad review into its water quality reports at the behest of the environment department.
A Healthy Land and Water spokesperson said they had discussed the issues raised by Hoban with the department, and it was decided further investigation was required before they could be included in the guidance material.
“Therefore [it would] be best addressed through a dedicated discussion paper to be provided to DETSI [Department of Environment, Tourism, Science and Innovation] as the appropriate government authority to assess their implications for policy and practice,” they said.
“Healthy Land and Water is working closely with DETSI to ensure the discussion paper is completed and that Mr Hoban’s proposals receive the thorough government consideration they deserve.”
A department spokesperson said they were working with Healthy Land and Water to consider the issues raised by Hoban.
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