Channel & Culvert Lining | A40, South Wales, UK

6,500m² of CCT2^® Installed for Erosion Control on the A40

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Project Overview

In August 2023, Concrete Canvas^® GCCM (CC) was used to line newly installed and improved drainage channels and culverts as part of improvement work on the A40 between Llanddewi Velfrey and Red Stone Cross.

The A40 improvement scheme is part of the Welsh Governments plans to improve accessibility and enhance the network along the east to west transport corridor to key employment, community and tourist destinations. The improvements works include installing new drainage channels and culverts whilst also improving existing infrastructure. To ensure that the drainage channels and culverts were able to be effectively maintained while also being protected from erosion caused by water run-off, a number of hard armour solutions were considered.

6500m²

CCT2^® installed to line new drainage channels and culverts

100mm

Overlap used in the direction of water flow for secure joints

2023

Installation completed on the A40 scheme in Wales

Solution

Poured and precast concrete was initially considered for the project. However, when reviewed, both solutions would have pushed the project over budget and schedule, whilst also being costly to be maintain. CCT2^® was specified for the project due to the speed and ease in which it can be installed – needing very little specialist labour or equipment – and being easier to maintain, making it a more cost effective solution.

Design & Installation

Before the CCT2^® was installed, new drainage channels were excavated. An excavator with a v-shaped bucket was used to cut the channel into a uniform surface. Once the excavation work was completed, Bulk Rolls of CCT2^® were delivered to site and lifted into place using an excavator with a spreader beam attachment. The CCT2^® material was laid transversely across the channel, cut to length and overlapped by 100mm in the direction of water flow. To join the overlapped material, an auto-fed screw driver with stainless steel screws was used, with the screws spaced 100mm along the overlap 30-50mm from the material edge. Galvanised J-pegs were used to secure the perimeter edges of the CCT2^® material within pre-excavated anchor trenches, with the material secured through each overlapped joint. Once all the CCT2^® material was secured, it was hydrated using a water bowser and hose, with the anchor trenches later backfilled with excavated substrate.

CCT2^® used to line the culvert

CCT2^® overlapped in the direction of water flow

To line the culverts with CCT2^®, preparation work had to be carried out. Corrugations within the culvert was filled using a suitable grout, providing support to the CCT2^® material once laid. Bulk Rolls of CCT2^® were cut down into custom length Batched Rolls and were deployed by hand in a transverse layup – with the material laid in the direction of water flow. To secure the overlapped CCT2^® material, stainless steel screw anchors with 15mm washers were used, with the screw anchors spaced 100mm apart and 30-50mm from the material edge. Once secured, the CCT2^® material was hydrated and the edges backfilled with a non-erodible fill.

Summary

Although improvement works are not set to be completed until Spring 2025, the current installation work carried out has been successful, with CCT2^® being used on a number of drainage work phases and being specified for further projects.

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