The end of March brought to a close the Year 1 dredging and restoration works being carried out within Brightlingsea Creek, Essex as part of the “Using Sediment As a Resource (USAR)” programme, on behalf of the Brightlingsea Harbour Commissioners, the managing authority of the local waterways.
As Principle Designer for the works, Exo Environmental have developed a four year project that aims to dredge approximately 50,000cu.m of accumulated sediment, which is currently causing concern for the continued safe and efficient use of this busy harbour. This sediment is to be beneficially used on site (BUDM), to restore nationally and internationally recognised intertidal mudflat and saltmarsh habitats to their historic extent (1940’s) following decades of erosion.
The beneficial use of dredged material in this occasion is made possible by containing it in compartments of brushwood fascines, due to the close proximity of the navigation channels to the restoration sites. The brushwood retaining structures allow dredged sediment to be contained to form a natural gradient from the mature saltmarsh down to the intertidal mudflats. Currently the mature marsh is eroding with a 1 to 1.5 metre cliff face susceptible to wave impacts.
The design by Exo Environmental involves careful consideration of environmental conditions and impacts on archaeological assets. It incorporates a combination of natural material, including hemp matting to retain sediment whilst it consolidates.
Year 1 saw the dredging of the harbour approach, Main Channel and access routes to the commercial wharf located within the North Channel. Local dredging company Port Flair, were selected as Principal Contractors for the works, bringing with them a wealth of local knowledge, experience and tools to achieve the first year targets. A combination of water injection dredging, plough dredging and barge-mounted excavators were all utilised in order to obtain target depths and create a level bed profile in the main channels for ease of navigation and maintenance.