Black Sluice IDB has started major enhanced maintenance works on the South Forty Foot Drain upstream of Boston in Lincolnshire, the Association of Drainage Authorities (ADA) just announced.
The work is taking place thanks to financial backing from the Environment Agency who are partners in the works through a Public Sector Co-Operation Agreement (PSCA) with the IDB. Works started in February removing mature bushes and trees from both banks, ADA said.
Once this had been completed, a specialist 45 ton long reach excavator worked in tandem with a smaller spider excavator. This machine could ‘walk’ its way along the bottom of the riverbed and pass extensive root growth and blanket weed it had collected to the larger machine in order to remove it from the river bed.
The vegetation removal work has now given way to a specialist silt cutting and pumping dredger from the Netherlands, which has been lowered into the river to start removing 60,000 m³ of silt from the 11 km length of river being worked on.
The silt and water mix is being pumped into a number of 4 ha silt lagoons where the silt settles and the clean water is fed back into the river, ADA said.
The benefit of this technique is that silt can be pumped up to 3 km between the cutting head and lagoon location, requiring far fewer machine movements to complete the work.