- On 19th April 2016
- In Dredging, Sediment Management
- By William Coulet
During the period of the 18th January to the 18th March, Exo Environmental in collaboration with the Brightlingsea Harbour Commissioners (BHC) successfully executed the maintenance dredging of 11,000m3 of accumulated sediments from within the two basins of Waterside Marina, Brightlingsea, Essex.
To facilitate the project design, extensive baseline data was obtained in order to assess the natural state and variability of the estuary. This data was utilised to draft a Habitat Regulations Assessment, Environmental Impact Assessment and other supporting data for the permits. One particular piece of supporting evidence was the detailed hydrodynamic and morphological modelling study, carried out in partnership with long-standing associates Svasek Hydraulics, Netherlands. These predictive models provided an understanding of the potential effects of dispersal of dredged sediment within Brightlingsea Creek and supported the development of a new scheduled maintenance dredging programme for the long term use of the Harbour and Waterside Marina.
Based on the results of the modelling studies and the input provided from stakeholder consultations within the local community, a final project methodology was developed. The site was mechanically dredged by Port Flair (Bradwell) using a 15 ton excavator mounted on a barge and the arising sediments liquefied and hydraulically pumped via pipeline to a discharge point. Discharge was carried out on an ebb tide to allow sediment dispersal throughout the estuary.
During this critical stage of the project, the surveillance monitoring of environmental parameters such as turbidity and dissolved oxygen concentrations was undertaken to ensure compliance with environmental responsibilities. This also provided an early warning system for any potential negative environmental impacts, allowing project flexibility and facilitating any remedial action required. However, throughout the duration of the dredging works, there was no evidence of any significant adverse impact on the estuary.
This project is an example of how adaptive management in conjunction with monitoring was utilised by Exo Environmental alongside the ‘Working with Nature’ philosophy to successfully deliver our clients’ needs.