During September 2009 soil mixing provided a successful solution to British Waterways at the Shropshire Union Canal in Shebdon on the Staffordshire - Shropshire border. The canal had been leaking for many years and even with the introduction of sheet piles on both sides the water was not able to be stopped from dissipating through the canal bed and out the sides of the embankment.
Eco Foundations were able to respond immediately to the emergency situation utilising it's mass soil mixing rig to solidify the base of the canal into a clay-like substance utilising a cement / bentonite binder. Normal pre-construction soil mixing and and testing assessments provided an indication of what was achievable using this ground improvement technique but permeability testing could not be carried out within the short time scale available. With the batching equipment mobilised to a suitable location close to the proposed working area and the soil mixing unit floated down the last kms of canal to the breach location, the canal was closed off and dewatered ready for operations to commence.
During the installation of the timber working platform, time was spent carrying out trial soil mixing to determine the best suited binder to meet British Waterways' requirements for a flexible and impermeable base to the canal. The computer controlled batching plant mixed the selected proportions of binders and then pumped this slurry mix a distance of 500 m to the mass soil mixing system which is installed on a 40 tons excavator.
The mixed material solidified after 24 hours to produce a substance stong enough to carry the weight of the machinery and flexible enough not to crack if the subsoil subsequently moved. Progressing on average 15 m per day, each soil mixed section was reprofiled within three days of being soil mixed. Almost 200 metres of canal base have been treated, reprofiled, flooded and then opened for public use within the 4 week programme.
Following successful reopening of the canal and close examination of the embankment British Waterways commented on the overall performance as follows:-
"British Waterways were delighted with the response time from Eco Foundations and all indications are that the technique has delivered exactly what is promised. In fact, it proved so flexible that we were able to treat soft spots found on site down to a depth of 4 metres" George Ballinger, Head of Engineering, British Waterways.
Over forty samples were taken from the canal bed for extensive testing and these results can be reviewed in the case study which may be downloaded by clicking on the link below:
Soil Mixing British Waterways Shebdon Canal Case Study
Click on the link to view a video of the in situ soil mixing in operation
