Opened in 1827, the Gloucester & Sharpness Canal was built to bypass the notorious River Severn between Sharpness and Gloucester. At sixteen miles long it has no intermediate locks, just the sea lock at Sharpness and the lock out into the Severn at Gloucester.
Sadly, no longer do ships trade to Gloucester, instead millions of gallons of water is extracted from Purton each night by Bristol Water. To replenish this loss of water, the same amount has to be pumped into the canal at Gloucester from the Severn where it enters the dock basin adjacent to the dry docks. Unfortunately each gallon of water contains silt which settles to the bottom of the dock and over a period of twelve months, tonnes of silt fill the dock. Mud which has to be dredged and which, until 2000, was removed by hopper barge, to be taken down to Purton for discharging at the Suction Plant.
This problem is nothing new for the Severn, a river notorious for having large quantities of silt held in suspension. First steam dredgers, then a modern diesel engine dredger were built to attack the mud each year. In recent years a revolutionary method has been used at Gloucester, water injection, which made the bucket dredger redundant!