Replacing specified gabion mattresses with Profix mattresses – Norfolk Broads
Broadland Environmental Services Ltd have a 20-year PFI contract to provide and maintain flood protection to the Norfolk Broads and surrounding areas.
Identifying a need for a lightweight erosion protection product to be used on navigable waterways, Hesselberg Hydro developed Geomat DM20, a geomesh reinforced with bitumen-bound aggregate. It allows reeds to grow through it and protects the riverbanks from boatwash and tidal currents.
A trial section at Ludham Bridge in 2002 was very successful and has led to Geomat DM20 being used on several sections of waterways. To date approximately 20,000 m2 has been placed.
Along a section of the broads a navigable channel required erosion protection at and below the ‘Mean Low Water Springs’. The designed solution was for gabion reno mattresses to be placed – this was a difficult task as the mattresses had to be filled in the dry and sailed into place, and they are not designed to be lifted.
Hesselberg Hydro used its knowledge of similar problems on work in The Netherlands and proposed and designed a system using profix geotextile mattresses. The mattresses were filled with local sand and are designed to be lifted resulting in a much simpler installation procedure.