Green Erosion Control Revetment

Derbyshire

This Derbyshire estate had a number of lakes and water bodies ranging in size from a quarter of an acre to five acres. All had been neglected by the previous owners and lay untouched for many years. As well as desilting, all the lakes needed to be realigned and their banks reinstated due to considerable erosion by American Signal cray fish.

The Brief

Assess the volume of silt in all lakes and waterbodies and recommend how much to remove.

Advice on ‘green’ solutions to control lake bank erosion.

Consider aesthetic enhancements e.g. enlarge islands and amalgamate various small pools.

Future-proof the works by designing meandering water inlets to create machine-accessible silt traps as well as new water control structures to manage flows.

Enhance pedestrian access by the design and construction of five bridges.

Before

After

Project Highlights

Surveys

Extensive bathymetric and estate-wide topographical surveys enabled the production of design drawings to support the planning application to drain down, de-silt and re-shape the lakes.

Revetment areas determined

Revetment design

Revetment Construction

The ponds and lakes were drained down using a combination of syphons, over pumping and opening of existing sluices.

The fish were caught and temporarily rehomed in another of the estate’s lakes.

(Image Left) Two parallel lines of posts were driven into the lake bed, with the rear post having a fines retention membrane attached. This helped to retain the silt backfill.

Tie back wires were installed to offer additional support to the revetment during the backfilling process and establishment of the planted coir logs (not shown).