Slope Protection | Old Whittington STW, Chesterfield, UK

230m² of CC5^® protected a slope, delivering long-term erosion control with 40% carbon savings

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Project Overview

In August 2020, Concrete Canvas Ltd was approached regarding a scheme where a section of slope at the Old Whittington Sewage Treatment Works in Chesterfield required a hard armoured protective layer to prevent cake – a byproduct from the recycling process at a sewage treatment works – from coming into contact with the soil on the slope.

230m²

of CC5^® Batched Rolls used to line slope

40%

carbon saving vs poured concrete

4 days

to complete by a team of 2

Slope prior to installation, Type 2 hardcore used to regrade slope, hardcore compacted to provide uniform surface, CC edges terminated against concrete upstand at the crest

Solution

The storage area at Old Whittington STW is connected to the treatment plant via a number of screw conveyors which terminate in a storage shed at the top of the site. Under the screw conveyors the slope was unlined and there was a risk of cake spillage onto the slope surface during maintenance activities. Yorkshire Water wanted to ensure the area underneath the conveyors was a controlled area in line with permit conditions.

One of the original designs for the slope involved mass pouring of concrete over the area; however, the time required for creating formwork, installing the poured concrete, curing time, potential mess and embodied carbon impact involved meant that ultimately Concrete Canvas^® GCCM (CC) was chosen as an alternative.

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Stainless steel fixings and a termination bar were used at the crest

Design & Installation

CC5^® Batched Rolls specified
Slope regraded using type 2 hardcore.
Vertical layup
Overlaps jointed using stainless steel screws and sealant
Secured using stainless steel fixings and clamping bar at the crest and against concrete steps
Secured in anchor trenches on side and at toe
Hydrated using a water bowser and hose and covered in plastic sheeting during curing in accordance with cold weather hydration guidance

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Termination at the crest

Hydrated, plastic sheeting used to cover CC overnight in cold weather conditions, poured concrete used to backfill anchor trench at toe, completed installation

Summary

The installation of 230m² of CC5^® was completed by a team of two over a total of four days in cold weather conditions, using only hand tools due to access restrictions on the site.

When the project was completed, Concrete Canvas Ltd conducted a Carbon Saving Report (which can be viewed here) . The report showed that CC5^® is hugely preferable to the poured concrete alternative, providing a GWP saving of over 40%. CC5^® has just over 15.81kg of embodied carbon per square meter of slope, compared to 28.02kg of embodied carbon per square meter of slope for the ST4 concrete.

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