This project to reduce flood risk to the local area was part of the wider Lustrum Beck Flood Alleviation Scheme being delivered by the Environment Agency with the Tees Rivers Trust.
Lustrum Beck, west of Stockton-on-Tees was a section of river identified as a potential flood risk, which without interference posed a threat to 150 local properties.
A combination of new features were required for the scheme, designed to divert and slow the flow of water downstream.
The improvement works constructed by Ebsford included creating an open channel inlet connection to Coatham Beck, designed to admit flood water into an excavated area where it could be retained. A variation of water levels here could mean that overtime the storage areas could not contain predicted flows in a flood event.
Ebsford excavated a large area on the flood plain to create three separate storage ponds with a meandering channel extending through the beds of the ponds from the inlet to the outlet structures. Earth embankments constructed above floodplain level with the excavated material increased flood storage capacity. The combination is designed to hold in excess of 17,500 litres of water and withstand a 1 in 75 flood event.
Scour protection measures were installed at the inlet following a survey in which Ebsford identified areas of significant erosion. Whilst typically within river restoration natural processes are preferred, in this instance it was important that no erosion occurred around the storage area inlets. Both the inlet and outlet channels were constructed with stone pitching to give further protection from the velocity of water at these points.
The outlet structures comprising of pipes passing through the embankments to discharge water from the ponds to Coatham Beck, also included stop log arrangements at the outlet to restrict outflows, ensuring water held back would slowly re-enter Lustrum Beck
The levels of flood water admitted into the new storage areas created a new and diverse range of habitats. The diversity of unfamiliar flows, with the addition of aquatic fauna and flora encourages improved biodiversity of the landscape whilst offering some protection for the local residential properties. Ebsford completed works on the scheme with additional landscaping, land drainage and the installation of timber footbridges across the inlet channels to allow public access to this a well-used community resource.
