A ground breaking dredging trial which could cut costs for dredging on the lower reaches of the Broads was carried out at Great Yarmouth last April.

The £30,000 pilot scheme which removed 6,200 m3 of silt from the River Bure cost one third of the average cost of dredging projects in the Broads. It involved injecting low-pressure water into the river bed sediment and fluidising the silt which was carried out to sea by the tide and gravity.

The technique was patented by Dutch company Van Oord who brought a dredger by sea to carry out the 10-day exercise. Work was carried out round the clock on every ebb tide between Bure Mouth and the top of Bure Loop.

Director of Waterways Trudi Wakelin said: "This is an innovative technique which has produced excellent results elsewhere. We are hopeful it could prove to be a cost effective solution to the expensive and difficult task of disposing of the sediment and could be a major breakthrough for dredging the lower reaches of the Broads. However, it is not likely to be a solution for the upper, shallower reaches where the tidal flow is not as great."

Monitoring has shown that due to its fine nature the sediment stayed in suspension for a lengthy period which allowed the particles to be carried downriver for a significant distance, but also caused a proportion of the material to return on the following flood tide, and some even to be transported upstream of the dredge site.

However the trial demonstrated that the technique can remobilise sediment without long-term detrimental effects to water quality and early surveys have shown an improvement in navigable depths.

Detailed analysis of all monitoring results is currently underway.