Infiltration basin protects Pumicestone Passage
  • Wednesday 09 December 2015
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Only a few months after Council constructed an infiltration basin at Earnshaw Street in Golden Beach the vital piece of infrastructure has done its job – albeit in a different way than expected.

The basin, which helps reduce pollution from stormwater runoff at the northern end of the Pumicestone Passage to protect critical habitats, stopped a large volume of sewage entering the waterway when a Unitywater sewerage pipe broke.

Division 2 Councillor Tim Dwyer said council took community safety seriously and was cleaning the site with Unitywater.

“Council takes community safety and environmental protection very seriously and is ensuring all contamination is removed from the site,” Cr Dwyer.

“Once it was determined that the issue was coming from Unitywater’s sewerage system, Unitywater arrived on site promptly and has acted in partnership with council to pump out the sewage and ensure the site was cleaned up as quickly as possible.

“Staff were on site again this morning to clean the contaminated sand in the basin.

“Council will keep the local community up to date as we restore the standard of the basin.

“The clean-up will include removing contaminated plants, rocks, geofabric and sand.

“Further testing will be done to ensure we know the full extent of pollution and the extent of remediation required.” 

Cr Dwyer said the spill could not have been predicted and reassured residents it was not caused by construction of the basin.

“This incident occurred due to a rare and unlikely set of circumstances and while the basin was not intended for this purpose, 100% of the sewage would have entered the passage if that basin wasn’t there,” he said.

“The affected sewer pipe is located approximately 30-40m away from the basin and neither its construction, nor its location, contributed to damaging the main or caused this spill.

“Initial investigations indicate a rising sewer main, upstream from the basin, appears to intersect one of council’s stormwater pipes.

“Council was unaware of this intersection, which would have been installed many years ago.

“Unitywater has now advised council it will relocate the sewer line away from the stormwater pit and will continue to monitor Pumicestone Passage to ensure there is no evidence of pollution, before the warning signs are removed.”

Any concerns regarding swimming in this location should be referred to Unitywater on 1300 086 489.

Fast facts – basin construction

  • It stops around 80% of pollution from entering our waterways.

The Pumicestone Passage received poor ratings of between D+ and C+ in South East Queensland’s Healthy Waterways Report Card in recent years, meaning critical habitats are impacted. Council installed the infiltration basin in this location to reduce pollution and improve water quality in this internationally recognised waterway. Experienced environmental engineers and landscape architects designed the basin and surrounding landscape to ensure it fits well into the environment, park and coastal pathway.

  • It does not pose an increase safety risk to the community.

Council conducted a thorough risk assessment before constructing the basin, which determined the basin does not pose any increased safety risks to the community. The basin only holds water for short durations in stormwater events, until it dissipates through the sand dune as intended. Barrier fencing is in place on the park side of the basin and low growing vegetation on the ocean side also discourages entry. As the basin is dry most of the time, it is unlikely to attract mosquitoes.

  • An infiltration basin is the most suitable piece of stormwater infrastructure for this location.

As well as preventing pollution from entering Pumicestone Passage, the basin helps dune stability. Stormwater from the local catchment is diverted into the basin and the water infiltrates into the sandy soils of the basin. Plants absorb nutrients in the stormwater and the sand will also act as a filter. This promotes plant growth in the area around the basin and enhances dune stability.