The Taylor Wimpy and Barratt Homes development on Henthorn Road, Clitheroe presented the project consulting engineers with an interesting challenge.
Running across the development was an existing water course which required realigning and profiling. Part of the watercourse was channelled through a culvert, with the remainder left as an open channel to form a green area within the development.
In order to maximise the available land for housing, the slopes of the culvert bank were to be as steep as permissible whilst taking into account the safety of the new residents.
The slopes of the channel were to be grassed and Betts Associates, acting as the consulting engineer, deemed the inclusion of an erosion control mat necessary to prevent erosion of the topsoil before establishment of the vegetation.
During periods of heavy rainfall, the water flow velocity down the face of the slope was considered a risk and so the use of a short–term biodegradable mat was discounted. The long lengths of the slope mean that the erosion control mat also needed an inherent tensile strength to withstand the load applied by topsoil before the vegetation root structure was established.
The base of the channel would also need a system capable of withstanding high peak flows within the watercourse.
Having considered various options it was decided that Erosamat Type 3 erosion control matting offered the necessary performance requirements for the steep side slopes.
Erosamat Type 3 comprises a three dimensional structure of entangled filaments to create a long lasting, environmentally friendly, flexible erosion control mat. In combination with vegetation it forms both an effective erosion control surface and root reinforcement layer.
The bottom of the channel required an alternative solution and here ABG proposed Erosaweb geocell, a geocellular system infilled with graded crushed stone. Erosaweb geocell is a three dimensional honeycomb structure designed to strengthen infill materials by containing them within its open structure. Used in water flow channels it dissipates energy by containing the granular fill and producing a rip-rap type performance.
The ABG Service
ABG provided a holistic design by combining both Erosaweb and Erosamat, allowing engineers to achieve the desired visual effect for the channel whilst ensuring the groundwork contractors could quickly and simply install the required protection. ABG are a market leading developer of high performance geosynthetic solutions for use in a wide range of civil, environmental and building applications.