Bribie Island Road, Ningi

Council has been searching for a suitable site to manage dredged material from Pacific Harbour canals for many years.

1077 Bribie Island Rd Ningi was identified as being a suitable site as the site:

• is within a suitable distance from Pacific Harbour
• is large enough to manage dredged material, whilst maintaining buffers to adjacent areas
• has existing disused prawn farm ponds which are suitable for containing dredged material.

During 2019, the site became available for sale and Council purchased it as a strategic land acquisition for the future storage and treatment of dredged material (e.g. a dredged material management facility).

Natural areas

The site has remnant bushland along the eastern boundary of the site. This area includes eucalyptus woodlands and mangrove areas. As part of the site’s development this area will be inspected and weed species treated to enhance and protect the native vegetation.

The western part of the site was used as a pine plantation. The previous owner of the site legally harvested pine trees prior to Council purchasing the land.

To enhance the site’s natural assets and to re-create a vegetated buffer between homes and the site, Council will re-establish native vegetation along the western side of the site. As part of the revegetation works, Council will ensure that fire and asset protection breaks are incorporated into the plantings and that overland (water) flows are identified and managed. 

Ponds

The existing large ponds (disused aquaculture prawn ponds) were designed to perform an aquaculture function for the now disused prawn farm. 

The design and engineering specifications of the existing ponds is similar to what that is required to contain dredged material.

Detailed geotechnical analysis works to confirm the integrity and stability of the existing ponds will be completed. Only minor earthworks to a small number of the external batters of the ponds is expected to be required, prior to placement of dredged material.

Security - building and equipment

Council has identified that the site contains a number of buildings built with asbestos containing materials. In addition, at least one open well has been identified on the site. 

To maintain safety, Council has installed fences around some buildings on the site, prior to planned demolition by professionals licensed to remove buildings with asbestos containing materials. 

Residents are reminded that while the site is Council managed land, it is not open for public access at any time.

Sediments wash into canal estates through normal tidal processes and require periodic removal to maintain navigational safety. The process of removal is via dredging.

How much material will be dredged?

Approximately 60,000 - 80,000m³ of sediment material needs to be removed from the Pacific Harbour canal system during the first dredging campaign.

The existing ponds at the site have capacity to receive and treat up to approximately 110,000m³ of material.

How long will the dredging at Pacific Harbour take?

The first major dredging campaign is scheduled to occur in 2021. Depending on the methods of dredging it is expected to take approximately 9 -12 months to complete.

Once the initial dredging campaign is completed another will not be required for approximately 10 years. During this time, the site will continue to be rehabilitated with native habitat.

In many cases, dredged material from canals is transported, via barges, to the offshore State Government Mud Island Dredged Material Placement Area (DMPA) in Moreton Bay. Unfortunately, the dredge material from Pacific Harbour canals is not able to be barged to this location due to potential risks to the Bribie Island Bridge.

Two potential alternative options have been identified to transport material from Pacific Harbour canals to the site. These options require further analysis including consideration of the impacts to local residents and costs. 

It should be noted that the preferred option has not been determined at this time.

Option 1 - By pipeline

A purpose-built slurry pipeline may be temporarily installed across the Pumicestone Passage to carry the dredged material to the site. Some of the pipeline would be laid within road reserve and public lands. Up to six ‘booster stations’ (small pump stations) would also be required along the pipeline to prevent build-up and ‘clogging’ of the pipeline.

Option 2 - By road

Dredged material may be transferred to the site in sealed trucks (similar to a cement mixer). Approximately two trucks, each completing between 10 and 15 trips per day (total daily truck movements of 20 - 30 round-trips per day) would be anticipated using this method. As part of this option, entry to the site would require upgrade to ensure traffic safety is maintained.

Both options would be operational during daylight hours only, up to 6 days per week.

Council continues to work with the State Government regarding these options with the aim of establishing the most cost-effective and environmentally sustainable option that minimises impacts to the Ningi and Bribie Island communities.

Approvals

A range of state and local government approvals are required for the treatment of the dredge material.

Council has commenced discussions with the State Government (Department of Environment and Science and Department of Agriculture and Fisheries) to identify the necessary approvals.

It is anticipated that Council will submit applications for approvals by February 2020.

Treatment process

Once placed into the existing ponds, it is anticipated that the dredged material will be dried out via natural solar-drying. Treatment of residual acid sulfate soils will also occur if required.

Noise

Depending on the transport method, there may be noise from the pipeline ‘booster stations’, however they will:

• only operate during daylight hours
• be positioned as far as possible from residents’ properties
• include effective noise suppression and / or noise screening devices, and
• will be monitored by Council.

The only noise expected at the site during the dredging works will be associated with vehicles on the site. 

Dust

Some dust may be generated within the site from the unsealed roads or from the dried dredged material.

Various techniques will be used to limit dust travelling to neighbouring properties, including the use of dust suppressants, if required.

Smell

The material to be dredged is marine muds and sands which may exhibit some odour when exposed to the air, similar to the smell of the natural mangrove system in Ningi Creek at low tide.

Various techniques will be used to limit odour impacts on neighbouring properties, including the use of odour suppressants if required.

Water quality

The ponds on the site will be used to dewater and dry the dredged material. Any water discharged from the site will meet the strict environmental thresholds imposed by the State Government.

The existing pond layout on the site already includes treatment ponds that were designed to meet State Government requirements. Council will take advantage of these existing ponds to treat water prior to discharge.

Mosquitoes

Council has a comprehensive mosquito management program which it applies across the region and the site has been included in the regular mosquito monitoring and treatment program. Further information on Council’s mosquito treatment program can be found on mosquito management.