UK: New Dredging Technique at Gloucester Docks

New Dredging Technique

Important dredging works will begin in Gloucester Docks this November, with a new technique being used for the first time to ensure the water is deep enough for large boats.

The dredging operation will remove sediment build-up on the bottom of the docks and is expected to take two weeks to complete.

Dredging is vital to ensure that Gloucester Docks can continue to be used safely by all vessels, particularly those with deeper draughts, such as those that visit during the popular Tall Ships Festival.

The new method of Suction Dredging will ‘hoover-up’ sediment from the bed and discharge it back to the River Severn through a floating pipeline. In previous years the technique of Water Injection Dredging has been used to flush sediment away, and while effective, it gives less control over where silt is dispersed and relies on large transfers of water.

Improved efficiency

Paul Fox, project manager at the Canal & River Trust said: “Dredging is essential to how the docks can be used for the next 12 months. We expect the new method to improve the efficiency of our work, while ensuring we increase the depth of the water to a suitable level.

We know how important a successful dredging operation is to local businesses and people who use the docks on a regular basis. It is particularly important for events like the Tall Ships Festival, which features vessels with deeper draughts that rely on a certain water depths.

By doing the work in November, when the traffic in the dock is relatively low, we’ll keep any temporary disruptions to a minimum.”

Tall ships festival

The aim is to achieve a minimum depth of four metres in the areas critical for the deeper draughted vessels expected at Gloucester Docks for the Tall Ships Festival which is being held in May 2013. The overall success of the scheme will also take into account the environmental impacts and costs as well as the depths achieved.

While essential, dredging alone cannot guarantee water depths. Other factors such as drought restrictions, shipping movements and pumping regimes are also significant.

We have consulted with the Environment Agency (EA) about the project, and both parties will monitor its effectiveness and the impact on water quality within the docks and the River Severn.

While the work is being carried out boat movements will be restricted during the week because of the presence of the floating pipeline, though boaters wishing to enter or leave will be able to do so by prior arrangement. Movements will be accommodated as far as reasonably practicable before 9am and after 3.15pm. At weekends the berths on the West Quay will be unavailable as the dredging pipeline will be assembled there, otherwise boaters’ use of the docks will be unaffected.

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Source: canalrivertrust, November 7, 2012