Environmental Monitoring and Control of Sediments Around Dredging and Reclamation Works, Thames, UK
Type:
Presented during:
WODCON XX: "The Art of Dredging" - 2013, Brussels, Belgium
Authors:
Leggett DJ, Read K, Black KS
Abstract: The requirements for dredging to be managed with respect to environmental considerations continue to grow and develop. In tandem, there has also been a move down the supply chain of responsibility for this matter directly to contractors. This situation applies in the case of the dredging of the Thames estuary in the UK for the purposes of the new London Gateway Port project. This paper provides insight into the aspects of sediment management that have been placed with the dredging contractor by the developer.
The paper covers how measurement of suspended sediments has been applied to manage and control day-to-day dredging operations and assess compliance with the requirements of the formal Environmental Impact Assessment undertaken for the development. This shall include the equipment applied and the experiences of running the monitoring equipment (located over 32km) in real time and characterising dredging and reclamation activities.
The result includes monitoring data gathered across the estuary from before the start of dredging in March 2010 and during dredge operations. Results of monitoring taken directly within plumes from dredging and reclamation operations and results from discharges from the reclamation are presented. A discussion is presented describing how some of the results vary on different spatial and temporal scales and link through the geomorphology of the Thames to tides, tidal cycles (spring / neap) and seasonal variations. The linkage of such variations to other factors such as freshwater discharge to the estuary system and to other activities and discharges (i.e. non-dredging activities) is also discussed.
The application of the real time control will be explained as well as the implications of this on the dredge operation. Lessons learnt and the application for future dredge activities shall be considered.
Keywords: suspended sediment, real time monitoring, plume characterisation, weir box monitoring