Cheapside dredging & piling project complete
Land and Water Services have completed dredging and piling the canal channel between Wallbridge Upper Lock and Capels Mill. The towpath is now open too.
Not a simple job
This project was not simply clearing out a clogged up canal channel. A history of landslip on this stretch meant that measures to diminish the risk of further slippages had to be taken.
Two piling systems have been used to stabilise the toe of the embankment. Such stability has been achieved by piling the foot of the slope for a length of 100 metres using 4.5 metre long Eucalyptus Cloeziana logs.
The superior grade timber, with high natural durability, was supplied by Cambridgeshire based company EcoChoice. The company supply Forest Stewardship Council certified timbers for exterior projects in the building, landscaping, civil and marine industries in the UK. This system (pictured above) was applied to the most vulnerable section of the embankment.
The piles were driven into position using the hydraulic power of Land and Water’s 7 tonne, Water King, amphibious excavator. Once in place and trimmed to equal height; the piles were faced with Ekki ‘waling planks’ bolted along the whole length. Ekki is another high grade timber. Waling planks serve to tie the piles together and to deal with contact from vessels… in the fullness of time!
200 metres of the less vulnerable parts of the embankment have been piled using the Nicospan system. Nicospan is a prefabricated, double woven polyethylene revetment fabric made from strong Ultra Violet stabilised mono-filament yarn. The fabric is heat sealed to form a series of open pockets each 220mm wide to allow timber posts to be placed into the sleeve. The 3 metre long timber posts inserted into the Nicospan are smooth, machine rounded & pointed. They have also been pressure treated with an environmentally safe wood preservative. The Nicospan poles are also installed using the hydraulic power of the 7 tonne, Water King, amphibious excavator.
Dredging & drying the black stuff
Once piling was completed the dredging began in earnest. 1,300 cubic metres of black and glutinous material was removed from the channel and held on site in an enormous lagoon to drain before removal. The material consisted of a combination of waterborne silt washed into the canal from the hillside streams together with generations of rotted vegetation. Land and Water Services have some very big equipment. The skills and deftness of touch exercised by the operators can be seen in the video made by CCT film maker Robert Paget. (See the link below)
Stroud District Councils Canal Project Manager Dave Marshall comments…
“The biggest single problem on this project has been the site’s history of previous landslips. Whilst the most recent incidents were back in the 1990’s and also in 2000, the embankment, historically, has clearly been susceptible to slippage. Neither steel nor concrete piling was financially viable and re-creating the original full width navigation designed to take Severn Trow sized vessels full of coal was therefore not a priority. This being the case the timber piles and Nicospan solutions were applied.
“We are pleased with the result and eagerly await regrowth of the waterside plantlife and the wildlife that will inhabit it. We are also happy that the Stroud District Council Volunteers Team, led by Paul Weller, were able to use the opportunity of low water levels in the pound to point the exposed wharf wall and towpath wall with lime mortar. This provided the finishing touches to the job.”
Cheapside Wharf is now ready for the next steps to be taken by Newland Homes who are preparing to develop the site.
Dredging & Piling — The Movie
Find out more
Local historian, author and Cotswold Canals Trust member Hugh Conway-Jones discovered evidence of an 1894 landslip that occurred just short of the Capels Mill railway viaduct.
- Click here to read Hugh’s findings on the 1894 landslip
- Click here to view CCT Photographer Mike Gallagher’s record of the Dredging & Piling Project
- Click here, or on the icon below, to find out more about Land and Water Services
- Click here, on the icon below, to learn more about Ecochoice
- Click here or on the icon below to find out more about Newland Homes proposed development of the Cheapside site