UK. Brightlingsea Harbour Commissioners announce dredging and saltmarsh creation programme
Wednesday, 06 January 2016
Brightlingsea, Essex, UK - Brightlingsea Harbour Commissioners (BHC) have announced formal plans for a long term dredging and saltmarsh creation programme designed to improve and maintain harbour depths and regenerate the vital intertidal saltmarshes in Brightlingsea Creek.
The build up of mud is a natural occurrence and dredging is therefore one of BHC's key responsibilities. Such dredging requires careful planning, complex survey work, liaison with commercial and leisure stakeholders, local residents and other interest groups, plus detailed consultation with organisations such as the Environment Agency, the Marine Management Organisation and the Centre for Environment, Fisheries and Aquaculture Science.
The erosion of the inter tidal salt marshes that surround the harbour is also of major concern.
Saltmarshes are highly productive biologically, providing nutrients which support other features within the marine ecosystem, such as mudflats, sandflats, subtidal areas, and wildfowl. They also have an important flood defence function, absorbing wave energy and forming a natural buffer between land and sea. There has been considerable loss of saltmarsh within the harbour area in recent years and BHC recognise the importance of redressing this.
Key to the success of any dredging operation is the correct disposal of dredged material together with the provision of an on going maintenance plan to ensure required depths are retained long term. Following extensive consultation with experts in the field in both the UK and Europe, plans are being drawn up for the spoil from harbour dredges to be used in a major regeneration programme for the saltmarshes.
Coincidental to BHC's own dredging plans, during 2015 the owners of Brightlingsea's Waterside Marina, which lies within the harbour, put forward proposals for dredging the marina and creating a barrier wall around it. The plans were not acceptable to BHC or many harbour users, so following discussion between BHC and the marina owners, it was agreed that BHC would assist in identifying a more acceptable dredging solution for the marina.
The opportunity to position the marina dredge within the wider context of the planned harbour dredging and saltmarsh regeneration programme brings considerable benefits. Following additional consultation/survey work a plan has been agreed with the marina owners that will ensure the marina dredge becomes a cohesive element of the programme and that the work will be overseen by BHC.
The areas covered by BHC's own dredging plan will mainly produce heavy mud waste, whilst the material to be removed from the marina is a lighter silt. Further surveys including complex hydrodynamic modelling, a Habitats Regulations Assessment and an Environment Impact Assessment have been undertaken which identify that a sediment dispersal programme is the optimum system for extracting the material from the marina. This option will allow maintenance of navigational depths whilst not removing sediment from the 'system'. The Colne Estuary and Brightlingsea Creek are a natural eco-system. Removing sediment from a balanced system can cause erosion or accretion of sediment because of a disruption in the balance. The conclusions of the modelling and assessments on the effects of the proposed marina dredge are:
That there will be no siltation of the main navigation channel.
That sedimentation upon the oyster beds within the Colne is negligible whether dispersing on the ebb or flood.
That there is minimal, if any, disturbance to wildlife (including fish), flora and fauna during dredging operations.
That a flood dispersal is more beneficial to the saltmarshes, and therefore the habitat and designated areas, than an ebb dispersal.
That a flood dispersal will see some siltation on the Town Hard, Smack Dock and between Olivers' Wharf and Morgan Marine. There may be some siltation on the oyster beds being used in the North and South Channel and BHC will work with the operator to mitigate any effect.
A key part of the programme will be monitoring; in particular, the amount of siltation and the concentration of sediment within the water. It is intended to employ an independent consultant to conduct the monitoring. The marina dredge will allow data to be gathered that will be invaluable in determining the final plans for the more extensive and complex harbour dredge.
Regarding timing, the main harbour dredge is expected to commence in late 2016 and will be preceded by the marina dredge in early 2016. The timetable will be carefully planned to minimise disruption to harbour users, whilst at the same time maximising the potential for rejuvenation of the saltmarshes. Amongst the many issues being taken into consideration are the seasonal activities of the leisure boaters, the requirements of commercial oystermen and fishermen and the needs of the wildlife which rely on the saltmarsh.
The total cost of the dredge will be in the region of £720k. The marina dredge will be funded entirely by the marina owners. Funding of the main harbour dredge will be through a mix of BHC funds and an EU grant.
Jim Addison, the Chairman of the Harbour Commissioners, commented "Dredging the harbour is a priority established by the Harbour Commissioners, and it essential to the sustainability of Brightlingsea as a commercial and recreational harbour. The opportunity to work with European partners and identify solutions that will enhance and support our unique environment and habitat is welcomed."
Further information about the dredging can be found at www.brightlingseaharbour.org or by contacting Brightlingsea Harbour Master Stephen Chick on 01206 302200.
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