Overview

The Flex MSE® geo-modular block and interlocking plate system was specified for riverbank repairs and revetment replacement at War Memorial Park, Romsey.

Challenge

Test Valley Borough Council proposed to repair >270m of existing timber bank revetment that had failed, running through the site. This particular site has a number of SSSI (Sites of Special Scientific Interest) designations with regard to native vegetation, biodiversity and a chalk bank stream.

Solution

Flex MSE® geo-modular block and interlocking plate system was specified, due to the successes on similar projects, conducted by the Environment Agency, whereby the system had received the unique designation “Recommended for use on SSSIs” – the first man-made product to receive such a designation to date.

After a long tender process, the contract was awarded to Five Rivers Environmental Contracting – a Flex MSE®-certified contractor. Works commenced in mid-Summer 2017; first to remove the existing failed timber revetment, and then to replace the bank edge using geogrid-reinforced Flex MSE units.

Sustainably-sourced river-stone was used as a launch-apron, to not only help tie into the riverbed, but also to provide a form of permanent scour protection at the toe.

In some places Flex MSE® units were tied-back into the bank, with every other unit turned perpendicular to the face, and in others where structural engineers had stipulated, geogrid was laid every 3 courses of units, tying up to 1.5m into the bank.

During installation, native aquatic plants were brush-layered in between the units at the water line. Post-installation, a specific native seed mix was hydroseeded onto the face, and top of the bank to meet the sensitive vegetation specification.

Outcome

The whole project was completed in a matter of weeks, whilst maintaining all SSSI designations, and making use of site-won materials from the chalk riverbank.