Thinking outside the (drag) box - Using technology from the steam era to solve the problems of today

Land & Water the specialist contractor and plant hirer has been putting their latest innovative plant to good use in Chichester Harbour to complete trials in salt marsh restoration working with the newly formed business Earth Change.

Earth Change along with Land & Water have partnered with Chichester Harbour Commissioners for trials to restore the Saltmarsh in Chichester Harbour. ?The Saltmarsh is an incredible environment which provides flood defences, absorbs harmful nitrates and phosphates as well as being a wildlife haven and superb example of biodiversity. Environmental changes have meant 60% of the Salt Marsh has been lost in the last 70 years.

A long term goal of Land & Water’s founders Richard Melhuish and James Maclean has always been to learn from the past and bring new technology to improve efficiency in our industry. This has been borne out in the recent trials in Chichester Harbour where Land & Water have adopted the traditional dredging method that was used by steam engines and have adapted it to modern plant.

A traditional method of dredging utilised steam engines to winch a steel box across silt to move it hundreds of meters through lakes and ponds to a point for disposal. Land & Water have removed the need for steam engines and replaced them with a hydraulic winch from the timber market that fits onto a 28 tonne excavator as an attachment. The drag-box that’s pulled by the winch is based around the traditional steam drag-box’s of the past. Depending on the density of the silt, the drag-box can move between 5 and 10m3 of silt at a time and has been moving 300m3 of silt in a 3 hour low tide window over around 150 meters up the shore

The process works like this…

Barges arrive at high tide and deposit 300m3 of silt (dredged from a marina elsewhere in the harbour). The pontoon acts as an anchor point beyond the deposited silt and the winch return pulley is anchored to a sliding rail on the side of the pontoon. The excavator is positioned on the land at the chosen deposit area. The excavator operator pushes the winch anchor blade into the ground to secure the winch and uses the winch to pull the drag-box backwards down the foreshore towards the deposited silt and pontoon. When travelling in reverse, the drag-box tailgate is pulled open. Once the drag-box has travelled over the deposited silt, the excavator operator reverses the winch to pull the drag-box back to the shore, as it does this, the tail gate pulls shut and the drag box is loaded as its pulled through the silt. ?A full cycle taking around 2 to 3 minutes. An amphibious excavator is on hand for general duties and to ensure the material is placed at the design height in the correct location utilising GPS positioning.htt

View the drag-box in use here: https://www.dhirubhai.net/feed/update/urn:li:activity:7042075435223916545

Tom Godfrey co founder of Earth Change commented “This has proven an incredibly efficient and low carbon method of reusing a material that’s usually deposited at sea to regenerate a failing SSSI Saltmarsh. We are impressed by both the equipment and the team at Land & Water and I am looking forward to working with them on other projects later in the year.”