Pacific Harbour maintenance dredging, Bribie Island

The Spinnaker Sound Marina boat ramp and part of the carpark, on Kal Ma Kuta Drive, Sandstone Point, will be temporarily closed from 12:00 PM Thursday 22 to 12:00 PM Friday 23 May for the unloading, assembly and launch of the cutter dredge.

Why is the project required?

Sediments wash into canal estates through natural tidal and drainage processes. It requires periodic removal to maintain navigational safety. The process of removal is by dredging.

Council’s Canal Estates Portfolio Asset Management Plan (CEPAMP) defines how we will maintain canals. Maintenance is required to ensure safe navigation and mooring of vessels. Canal depths in the lower reaches of the Pacific Harbour canals have reached the depths nominated in the estate's Long Term Maintenance Plan. Particularly, the lower Skippers Canal and the Marina have reached limits, and maintenance dredging is now required.

The maintenance dredging will ensure safe navigation and mooring within Pacific Harbour.

This is the first large-scale maintenance dredging project we've undertaken at Pacific Harbour. Smaller-scale maintenance dredging, of less than 2,500 cubic metres, was undertaken in 2005/06, 2013 and 2016. 

How long will the dredging take?

The planned maintenance dredging is expected to start in mid-2025. It will take approximately eight months to complete.

The set-up of the temporary pipeline from Pacific Harbour to the Ningi DMMF should start in May 2025 and be completed by July 2025. The pipeline and boosters will be in place for the full duration of the dredge works.

Once completed, the next major maintenance dredging project will be in approximately 10 to 20 years.

What is the dredged material?

In 2020, we completed detailed sampling and analysis of sediments from the bottom of Pacific Harbour canals.

Tests found that the material is, for the most part, very soft, dark grey marine clays and sand with occasional clays. It was tested and assessed against relevant guidelines and is suitable for land-based disposal.

How much material will be dredged?

Based on bathymetric surveys of the canals, approximately 80,000 cubic metres of sediment material needs to be removed from the dredging area.

How is the project funded?

The Pacific Harbour Canal Maintenance Special Charge funds the cost of maintenance dredging and spoil disposal. This charge is levied on the canal fronting rateable land within Pacific Harbour.

The sediment will be extracted by cutter suction dredging. It will be pumped through a temporary submerged pipeline across Pumicestone Passage and a short way up Ningi Creek to the Ningi DMMF.

The temporary pipeline will have a diameter of approximately 300 to 400 millimetres. It will be approximately seven kilometres in length. To help move the dredged sediment, three booster pumps will be used along the length of the pipeline. The booster pumps and pipeline will be secured in place for the duration of the project using anchors.

During the dredging campaign, residents may notice temporary impacts as detailed:

Boat ramp temporary closures

The Turners Camp and Kal Ma Kuta Drive Park boat ramps at Sandstone Point will be closed for public use during the project. This also includes their adjacent car parking areas.

Turners Camp will be used to stockpile and assemble the pipeline. Operational boating will be launched from Kal Ma Kuta Drive. Each site will have temporary changes to traffic and pedestrian movements throughout the project.

No local boat ramps or boating facilities will be permanently closed for the duration of the dredging.

• Turners Camp: the rest area will close for the duration of works between May 2025 and March 2026.
• Kal Ma Kuta Drive Park Boat Ramp: Some parking bays will be fenced off for the duration of works between May 2025 and March 2026. The boat ramp will be used intermittently by the contractor but will not be closed during the works.
• Spinnaker Sound Boat Ramp: Some parking bays will be fenced off between May 2025 and July 2025. The boat ramp will be closed for 3-4 days around mid-to-late May 2025 and another 3-4 days in March 2026 when the project concludes.

Noise

There may be noise from the temporary pipeline booster pump stations. To minimise noise impacts, the pumps will:

• only operate during daylight hours, 7:00 AM to 5:00 PM, Monday to Saturday
• be positioned as far as reasonably possible from residents’ properties
• include effective noise suppression and or noise screening devices, including mufflers
• be monitored by the dredging contractor.

Marine areas

There may be minor impacts to the Marine Park environment of Pumicestone Passage and Ningi Creek. Impacts on natural marine environments will be minimised as much as possible.

These impacts, anticipated by the Marine Park Permit and Development Approval, will be temporary. They are expected to naturally recover and include:

• disturbance of seagrasses and mangroves where the temporary pipeline and anchors rest on the seabed
• vessel strikes on marine fauna. The use of exclusion zones and marine megafauna spotters during marine works will help reduce the risk.

The installation of the pipeline by the end of June aims to avoid disturbance to flowering seagrasses.

Navigation and public use of waterways

The submerged pipeline will run across Pumicestone Passage and along most of its alignment within Ningi Creek. This aims to minimise impacts on navigation and marine-based activities. The exception will be where the pipeline connects to the floating booster pumps. To avoid the pipeline and booster pumps moving, they will be anchored in place.

For safety, closures of parts of Pumicestone Passage to recreational boating activities may be required during the installation and removal of the temporary pipeline and booster pumps. Once operational, an anchoring exclusion zone will apply around the temporary pipeline. Additional exclusions are also likely around the booster pump stations. Any required partial closures and exclusion zones will be advised by Maritime Safety Queensland.