CBEC was commissioned by Fisher German LLP develop detailed designs for bank protection works for the River Dove at Coldwall Farm, near Thorpe in Derbyshire.
Previous bank protection works had been undertaken at the site. However, these works subsequently failed resulting in significant slumping of the bank and further remediation was required. To inform the development of detailed designs, CBEC undertook a topographic survey and a design walkover. These informed the production of detailed design drawings and a design method statement.
Detailed designs were prepared with the main design feature comprising the creation of a Krainer cribwall comprised of nine levels arranged in the following configuration:
– Criss-cross of 0.5 m diameter timber logs to form open crib cells;
– 1.5 m corrugated steel bars fixed through log intersections for added stability;
– Pre-established coir rolls placed between perpendicular logs to retain finer
material;
– Cells backfilled with free-draining gabion aggregate, won on site from previous
stabilisation attempt, and compacted; and
– 250 mm Rock mattress gridding on the upper bank fixed with 2.0 m ground
anchors.
The design is based on CBEC’s previous experience in riverbank stabilisation projects, ensuring that further erosion is mitigated without increasing flood frequency downstream of the site and that there is minimal risk to local infrastructure, services and assets.
