Channel Lining | Coalcleugh, Hexham, Northumberland, UK

700m² of CC8^® installed as erosion control to a newly formalised channel

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Project Overview

In September 2019, Concrete Canvas^® GCCM (CC) was specified for use on a project at the former Coalcleugh mine near Hexham in Northumberland, UK.

The project involved the formalisation of a channel to divert the river away from heaps of metal-contaminated wastes left by mining activities in the 19th and early 20th century at the very top of the River West Allen. Situated within the North Pennines Area of Outstanding Natural Beauty, more than 40km of river is heavily polluted by historical metal mining. This intervention will help prevent about half a tonne of lead, cadmium and zinc polluting the river each year

Channel Preparation: installation site, channel prior to formalisation, small excavator used to cut channel, installation began downstream

700m²

of CC8^® used to line the drainage channel

7 weeks

to complete during extreme weather conditions

100mm

overlaps secured with screws for durability

Solution

A lining solution was required for the formalised channel to provide erosion control in order to ensure the channel is able to accommodate high water levels and rapid flow rates. Having previous experience of Concrete Canvas^® the client – the Coal Authority – included CC in the project designs from the offset with no alternatives considered.

This was due to the rapid installation rates of the material and the ease of install in such a remote location. The works were carried out by a contractor who was also familiar with CC having installed the material on numerous Coal Authority projects.

Rock Rolls used to backfill anchor trenches in difficult to access locations

Anchor trenches used to capture CC edges where possible

Design & Installation

Small excavator used to cut new channel
Batched and Bulk Rolls of CC8^® were specified
Transverse layup
Screwed overlap joint
Downstream, the material was terminated into a drystone wall
Upstream, the material was terminated into a sandbag headwall
Edges of CC8^® were secured within anchor trenches using ground pegs, backfilled with soil where possible, or rock rolls, or larger stones.
Hydrated using diverted stream

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Where anchor trenches were not possible, rock rolls and stones were used

Summary

The installation was carried out by a team of four over several weeks. One of the advantages of using CC in a transverse layup is that the installation can be halted quickly if needed, which was necessary on this scheme as several extreme weather events and floods required the channel to be quickly reopened. A total of 700m² of CC8^® was successfully installed in difficult weather conditions

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Upstream headwall

The use of Concrete Canvas on the scheme at Coalcleugh was certainly the right material for the job in what was a remote site with difficult topography under some extremely challenging weather conditions. Where ground conditions varied and required quick modifications to the design, the team at Concrete Canvas supported and provided advice for solutions very quickly so as to mitigate any potential delays to the project.

Rob Culledge Contracts Manager, JN Bentley