Case Studies

Walking Excavator Passes Screen Test

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Walking Excavator Passes Screen Test

REMU Screener L50
Client: Alaska Limited

I’m not sure how we would have tackled this project without the Dig A Screener R600

The combination of the excavator and the Dig A Screener R600 has proved perfect for our remediation work

Walking Excavator Passes Screen Test

A Dorset-based specialist contractor is helping to remediate a brook in Derbyshire using, perhaps, the most unusual equipment combination currently working anywhere in the UK

Alaska Limited is using a 10 tonne walking excavator equipped with a Dig A Screener R600 to help remove silt from a water course contaminated after a land slip at the end of last year. Based in Wareham, Dorset, Alaska Limited is using a combination of a Batemag walking excavator and an R600 Dig A Screener rotating screening bucket to tackle a tricky remediation contract on a Derbyshire brook that ultimately feeds into the River Derwent.
Land Slippage

At the end of 2007, a land slippage caused the failure of a dam sealing the clean water lagoon at a local mine. The resultant wall of water crashed through the adjoining village of Cavendish Mill and raised the water level in Stoney Brook by over a metre. To make matters worse, the lagoon contained a high level of tailings from the mine workings that contaminated the stream bed with silt. Ordinarily this would have been washed away naturally, but this material swamped the gravel fish breeding beds to such an extent that the flow of water has been insufficient to move it. As a result the silt has now compacted and ‘armoured’ the gravel, rendering it useless for breeding.

In a contract overseen by the Environment Agency, Alaska Limited was called upon to remove the silt and clean and replace the gravel at various locations along a 3.0 kilometre stretch of Stoney Brook. It was originally estimated that the project would require the removal of approximately 100 tonnes of silt but Alaska has already extracted more than 1,000 tonnes and isn’t finished yet.
Wading and Walking

The relatively remote location of the brook, coupled with the need to safeguard the integrity of the banks of the brook forced Alaska to take a somewhat unusual approach to its equipment selection process. “Environmentally, this is an extremely sensitive project. We are restoring the breeding grounds for fish whilst also protecting the banks of the brook which is home to a large population of water voles,” says Alaska’s Mike Worth. “The walking excavator is able to climb over the banks without damaging them and can also wade into the brook itself and work freely in water that is up to two metres deep in places.” According to Worth, the combination of the excavator and the Dig A Screener R600 has proved perfect for the remediation work. “The screen is used as a normal bucket on selected areas. The loaded bucket is then rotated over the waste skip to remove the heavier silt before being immersed in the water filled-skip to remove the finer silt. The cleaned gravel is then replaced in the river bed.”

The reclaimed material is returned to the mine where over 90 percent of the material to date has been processed and reclaimed.

“We’ve been extremely pleased with the R600 screening bucket; it has enabled Alaska to revitalise the river bed and bring this part of the river back to life. The Environment Agency has also been impressed with its performance and the comparison before and after is nothing short of remarkable.” Mike Worth concludes. “It is quite a brilliant piece of kit and absolutely ideal for this type of remedial work. The 4 mm screen is just right for removing the silt and retaining the gravel. And it must be working because the whole area is now awash with kingfishers.”

23rd August 2012


Worsley Plant Ltd,Road Beta,Brooks Lane Industrial Estate,Middlewich,Cheshire,CW10 0QF


Sensitive environmental application
Silt removal and gravel cleaning
Easy change 4mm screen
Material washing & separation
Loading capability bucket