Siltbuster called in to protect watercourse in Exmoor National Park

10 Jul 2013

Siltbuster have been awarded a £750,000 contract by Bachy Soletanche, for the supply of two water treatment plants, to help prevent any environmental impact from a major dam maintenance project in Exmoor National Park, Somerset.

Bachy Soletanche is undertaking the major remedial grouting works at Wimbleball Dam on behalf of South West Water, who are jointly funding the project with Wessex Water. The 49m high concrete dam, which spans the River Haddeo, is located in the middle of the stunning Exmoor National Park and is a popular area for tourism and water sports. The 21 million cubic metres capacity reservoir created by the dam also supplies the drinking water for local towns such as Taunton, Tiverton and Exeter.

The maintenance work will inject grout into the bedrock to block fissures and prevent water seepage by enhancing the grout curtain under the dam. Specially designed drilling rigs are used to drill into the underlying rock, injecting hundreds of cubic metres of liquid grout. As it sets, this forms an impervious ‘grout curtain’, thereby reducing seepage.

Eddie Edwards, Bachy Soletanche’s Project Manager at the site said: “As a company, we take our environmental responsibilities very seriously. Of particular concern was the potential impact that the drilling and grouting works could have on the beautiful Haddeo Valley and the surrounding countryside and river systems. Any seepage of the injected high-pH cementicious grout into the water systems would be particularly concerning in its impact on the valley and the fish farm a mile downstream.” As a result, and working with South West Water and Wessex Water, Bachy Soletanche established an automatic water quality monitoring system and appointed Siltbuster, the experts in construction site water treatment, to help prevent any environmental impact from the works.

Siltbuster designed the treatment system, based on strict discharge limits imposed by Bachy Soletanche and South West Water engineers. Siltbuster’s Adam Huckstep explained that ‘’based on experience with similar projects, our engineers designed a 150m3/hr water treatment system. This treats the seepage water collected from under the dam, removes any grout or aggregate such as sand particles and neutralises the pH, allowing the water to be harmlessly discharged into the river downstream.”
He added: “The system operates autonomously, constantly monitoring the incoming and outflowing water quality and treating the water accordingly. A second larger 500m3/hr Siltbuster treatment plant is located further downstream and automatically starts and treats groundwater from a series of natural springs in the valley below.’’

Siltbuster installed both plants at the remote dam site and had them operational in just under 12 weeks, helping to keep the project timetable on-track to be completed this year. Eddie Edwards, Project Manager at the site for Bachy Soletanche added: “Siltbuster has provided a cutting-edge water treatment system which is simple to use and reliable. It has been really easy for us to train our drilling engineers on how to operate, monitor and maintain the plant in this remote and difficult-to-access drilling site. Siltbuster engineers are on call 24/7 to provide support, which gives everyone involved added peace of mind.”