DREDGED MATERIAL FROM PORT DEVELOPMENTS: A CASE STUDY OF OPTIONS FOR EFFECTIVE ENVIRONMENTAL MANAGEMENT

摘要

The disposal of dredged material arising from port expansion can pose significant environmental challenges, because of the large amounts that may be generated over a relatively short space of time. While sea disposal continues to account for the bulk of dredged material in the UK, an increasing quantity has been directed elsewhere. In this paper, we reflect this trend by reference to activities associated with recent dredging of the approach channel and port facility at Harwich, on the SE English coast. Most of the dredged material (29 million t wet wt) arising from the Harwich development was disposed of at 'Roughs Tower', a deposit ground in the outer Thames estuary, UK. In view of increasing concerns over the dispersive capacity of the local environment in response to such large quantities of material, and the development of a nearby crustacean fishery, this deposit was accompanied by effective closure of the site. We report on the outcome of surveys of the sediments and the benthic fauna at the disposal ground before and after the event of cessation. These were conducted as part of a wider programme of monitoring at sites around the England and Wales coastline, in order to provide an independent check that licence conditions are being met, and to provide information relevant to the future decision-making process. Finally, we explore the view that, when properly managed, the conventional sea disposal route may itself be considered as an enlightened use of dredged material.