Thursday, 31 October 2013

Fleet Pond Silt and Sandy Bay Works

In 2006 the Ministry of Defence authorised a programme of installing silt traps and filters on the Army Training lands at Long Valley, which has significantly reduced the input of silt to Fleet Pond via the Gelvert Stream. This was the incentive to produce the Restoration Programme which includes dredging much of the silt accumulated over more than 30 years.

At times of heavy rain it is inevitable that some of the eroded soils will not be retained by the traps and filters, but will be washed into the Gelvert Stream and be transported to Fleet Pond. The works at and adjacent to Sandy Bay are aimed at reducing to an absolute minimum any silt that might reach the main body of Fleet Pond.

The line of islands constructed from dredged silt along the reedbed edge to the right of Sandy Bay is designed to direct the flow of the main stream around the edge of the pond. This channel will slow the water movement and help to deposit silt before it can be carried into the centre of the pond.

The clearance works to the left of the open beach and in the adjacent reedbed are aimed at allowing high levels of flow in the stream to overflow into channels (known as braiding) cut across the reedbed. This will also slow water movement and the reeds will filter out any suspended silt before it reaches the Pond.

The islands and the reedbed channels will allow silt brought in by the Gelvert Stream to be deposited in areas which, in future years, can be accessed by land-based or shallow water based equipment. This will remove the need to mobilise high cost, heavy machinery on pontoons for dredging operations.

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