New Approach to Outdated Desilting Method at World Heritage Site Studley Royal and Fountains Abbey De-silting works

A new and innovative approach was required for our client who was stuck for a feasible solution to desilting a large river fed reservoir where environmental and customer impact were of the highest importance.

In order to maintain the excellent reputation of the world heritage parkland and carry out the works without reducing the impact on visitors, Ebsford designed a non-invasive and innovative solution that could replace traditional dredging, a system the National Trust had stuck with since the early 1930s.

The Half-moon reservoir at Fountains Abbey is fed by the river Skell, which runs directly through the estate. Over the years, silt levels had been increasing and led to a build-up in the reservoir that required dredging.

De-silting is best carried out when the water levels are at their lowest which coincides with the summer months, the most popular season for visitors to the site. The last project at the site and of this type was carried out in 2010 at Studley Lake. The works created scenes of mud, diggers and destruction to the surrounding landscape which the site managers were keen to avoid this time.

Ebsford were able to specify a low impact solution using the amphibious Truxor machine. The use of on water machinery limited the impact to the surrounding areas and removed the need for heavy machinery which was estimated to require over 2000 vehicle movements over the length of the project.

To further reduce the impact on the environment and to the business, the silt was pumped out of sight over 1km uphill into a bespoke straw bale silt receptor capable of holding in excess of 8,000 cubic metres of the material. This solution was designed to replace standard geosynthetic silt bags which required a huge area to dewater and couldn’t be re-used therefore making it much less sustainable.

On target and within budget, works were completed with the minimum of impact, allowing the lakes to remain open as a visitor attraction. All materials were sourced locally which helped to dramatically reduce the cost to the client. Over 8000 m3 of silt was removed and along with the used straw bales, re-worked into the residing farmer’s land providing a nutrient rich boost to the soil.