Project Name: Moresby Hall A595 Roadway Embankment Repair Project
Project Location: Cumbria, England
For several years, the United Kingdom’s National Highways and local authorities have been monitoring areas of ground movement within the embankments supporting the A595 roadway near Moresby Hall in Cumbria.
To address the deteriorating ground concerns, the National Highways developed a £16 million (approximately $20 million USD) improvement project. The goal was to rebuild the roadway embankments and integrate a new drainage system, thereby facilitating long-term improvements and reducing maintenance needs for the A595.
Project Planning and Initial Phases
In 2022, Amey Highways (the project designer) and AE Yates Civil Engineering (the project contractor) collaborated with National Highways to begin planning an improvement project aimed at rebuilding the A595 embankments and drainage systems near Moresby Hall. The team worked closely with technical experts and material supplier, Greenfix.
Two site enhancement locations were established, one on each side of the A595 roadway.
Phase One: A micro-tunnelling technique was used to minimize disruption while two tunnels were installed under the embankment as part of the work to upgrade the drainage system along the A595.
Phase Two: Improvements to the A595 included restructuring embankments on both sides of the roadway. These embankments had an average length of approximately 140 meters (460 ft) long and up to 10 meters (33 ft) high.
Material Selection and Design Criteria
Given the height of the embankments, the project required a solution that could minimize settlement and mitigate the risk of overloading the newly installed drainage infrastructure below. A lightweight yet strong system that could also support a vegetated finish was essential. With these requirements in mind, the GEOWEB® Earth Retention System emerged as a viable choice due to its capability to withstand differential settlement without compromising structural integrity.
Following discussions with stakeholders and the technical team, it was decided that Presto Geosystems’ GEOWEB® Retaining Wall System, infilled with Leca® Lightweight Aggregate (LWA), would be employed to address the issues with the failing embankments. As part of this decision-making process, Presto Geosystems’ design engineering team conducted a complimentary project evaluation to provide further design assistance.
Product Features and Installation: A Perfect Re-Pairing: GEOWEB Green Walls with Leca Lightweight Aggregate
The design engineers recommended that the GEOWEB System sections form the wall fascia with a minimum depth of three cells, thus creating a deep integrated section resistant to movement. Calculations were run to determine the factor of safety against sliding, overturning, and bearing capacity failure, and the wall design was deemed acceptable.
The GEOWEB Reinforced Wall was designed to include the Greenfix 3PE geogrid for earth reinforcement, and the GEOWEB Wall green fascia was chosen to maintain a natural aesthetic when vegetated. Additionally, the patented ATRA® Wall Key was used to connect the GEOWEB sections at interleaf sections, and it was color-matched to the green fascia.
The selected infill was the LECA® Lightweight Expanded Clay Aggregate (LWA) due to the much lower horizontal earth pressures it allows. Approximately 11,000 cubic meters (387,462 f3) of LWA was used to fill the GEOWEB Wall sections. Installation was designed for speed and ease, using materials that are both lightweight and easy to assemble.
Once infilled, the GEOWEB front panels were topped with topsoil and seed to create the required vegetated finish. Seed may also be mixed in with topsoil prior to infill, hydroseeding methods can be employed, or voluntary native vegetation can be used. The choice of plant species is not critical to the geocell’s functionality, so low-maintenance, native varieties are generally recommended.
The GEOWEB Walls are both aesthetically pleasing and environmentally friendly, requiring no maintenance for vegetation and capturing stormwater runoff. Horizontal terraces collect rainwater, minimizing runoff and erosion from the impervious roadway surface. Local grasses and flowering vegetation will help ensure easy growth with a natural look, especially when using the green ATRA Wall Key.
Performance and Sustainability
Presto Geosystems’ GEOWEB Geocells offer industry-leading durability, design flexibility, and performance. The high-density polyethylene (HDPE) material is environmentally safe and has undergone third-party testing for long-term stability against weathering and oxidation. The GEOWEB system’s design flexibility accommodates various wall types, infill options, and site conditions while its unique structure minimizes hydrostatic buildup and enhances stability.
The GEOWEB Retaining Walls are made from premium HDPE resin, designed to confine infill materials and resist environmental degradation. This HDPE material is chemically inert and has been proven not to leach harmful substances or microplastics.
Not only are the GEOWEB Walls quick and easy to install, but they also offer a more cost-effective and sustainable alternative to traditional MSE walls, such as masonry or gabion block walls. They excel in performance under differential settlement, seismic activity, and hydrostatic pressure—benefits not commonly found in traditional systems.
Since its completion in early 2023, the A595 Moresby Hall project has achieved several noteworthy milestones. It is now the largest GEOWEB Retaining Wall installation in Europe. The success of this installation was enhanced by the combined use of GEOWEB Geocells and LECA® Lightweight Expanded Clay Aggregate (LWA) as infill material. Both materials contributed to a sustainable and cost-effective solution that optimized stability and minimized the risk of future landslides.
The project has also earned recognition from English Heritage for its cultural importance, especially in relation to 12th-century settlers in the region. With this state-of-the-art earth retention system in place, featuring both GEOWEB System and LECA technologies, these historically significant embankments will remain stable and secure for generations to come.