Dunsbury Park Riverbank Flex MSE Retaining Wall – 2016
Case Study: Riverbank/Retaining Wall, Dunsbury Park, Havant, Hampshire, PO9 4EE, UK
Client: Portsmouth City Council
Designers: Peter Brett Associates
As part of a commercial highway scheme to redevelop land on Dunsbury Hill Farm, Havant, consulting engineers Peter Brett Associates designed a permanent, green solution to create a riverbank alongside a new link road between the B2150 and the new Dunsbury Park site. Flex MSE® Vegetated Wall System was specified to preserve native habitats and ecological features, as well as diverting an existing stream to provide wetland for wildlife and increased flood alleviation capacity.
VolkerFitzpatrick, the winner of the tender, installed Flex MSE® GTX Bags & Interlocking plates, reinforced with geogrid, alongside rock-rolls & gabion baskets.
Flex MSE® Units, prefilled with a free draining granular material (first two courses) and a proprietary mixture of sand & compost (remaining courses) were installed up to 2m high, with geogrid laid every three rows tying up to 1m into the bank. Some of the Units were filled with a pre-seeded mix. Posts and a safety rail were installed alongside a public footpath that was created at the crest of the bank.
The Units were then hydroseeded using a native seed mix, and within 12 weeks were fully covered in vegetation.
The project was completed in a matter of weeks, required very little machinery to install as the Flex MSE® Units were delivered prefilled to site, and installed by hand, without any heavy machinery required. Twelve months post-installation, the system was completely covered in vegetation, and had blended into the natural environment.
The Flex MSE® GTX bags are both water & root permeable and UV-stabilised, acting as a scour protection at the face, withstanding high flow-rates during flood events.