Changing the Shape of the River Derwent, Derby

The Project

A lack of material in this area was causing the surrounding bank to become increasingly vulnerable, making it susceptible to undercutting erosion and imminent collapse. More worryingly, the infrastructure that was under threat included a sewage treatment plant and an ambulance depot – collapse of these areas would cause critical harm to water safety and local life. Which is why the Enviormental Agency made this project an urgent priority and enlisted Jackson Civil Engineering to revise the shape of the river to divert water flow away from the high priority infrastructure. 

The location of the scour hole was sandwiched between buildings and a wall of greenery, meaning the only way this project could be completed is by machinery on water. With this in mind, JCE reached out to The Rothen group for boats, experience and expertise.

The plan outlined by JCE included the removal and disposal of approximately 4,370t of silt and the redistribution of 2,000t – but in order to complete this, over 3500m² of vegetation had to be removed first. This wasn’t a straight-forward job, however, since there were large pockets of Japanese Knotweed and Himalayan Balsam within the overgrowth, requiring our team to undergo a check, clean and dry policy to prevent any further spread. 

Once the vegetation was removed off-site, our team began the dredging process. With a long reach 40t on the bank along with 8t diggers on our wide beam digger pontoons and two pusher tugs to transport five 35t hoppers back and forth to the offload point, we made light work of such large quantities. A safety boat was also used as the works were upstream of a weir. 

The only speedbump our team encountered was the presence of Signal Crayfish, which required us to carefully monitor each hopper that was being filled and ensure that the invasive species didn’t re-enter the waterway.

With our team’s works complete, a straighter waterway has been created, preventing the 

growth of the scour hole.