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Issue link: http://sea-technology.epubxp.com/i/477967
18 st / March 2015 www.sea-technology.com tee, the Thames Estuary Partnership, dredging liaison groups, the RSPB, Essex Wildlife Trust, Natural England, the Port of London Authority and English Heritage. Managing the Dredge On completion of the EIA, a network of monitoring sta- tions should be established (in suitable locations according to the site conditions) that surround the site to be dredged, which will report real-time data back to the dredging op- erator. The operator will then use this data to manage the dredge and vessel activity to ensure that operations can continue as effciently as possible, without exceeding the predetermined parameter threshold limits or having to tem- porarily cease dredging operations, as downtime can be ex- tremely costly. This may be achieved in a variety of ways, including moving dredging operations to another area within the site. Disposal of sediment may also impact operations, and it is crucial to ensure that this occurs in an area where it is not likely to be washed back into the dredged site, if it is not be- ing used in associated land reclamation projects. Operators for the London Gateway Project established well over 20 real-time monitoring stations throughout the duration of the project. OSIL was closely involved with the mencement of any works in order to establish baseline in- formation over a variety of conditions and seasonal fuc- tuations, and to understand how the currents and tides will affect the movement of resuspended sediments. For exam- ple, during the London Gateway Port Development Project, U.K., which was completed in 2014, water quality, benthic and epibenthic surveys frst commenced in the Thames Estu- ary more than 10 years before the four-year-long dredging work began. An extended period of background monitoring is in the best interests of all parties to ensure that the base- line information is correct and accounts for as many regular hydrodynamic events as possible. Background monitoring is nearly always undertaken with a permanently moored monitoring station (or stations, depending on the size of the project site), such as the Ha- vant, England-based Ocean Scientifc International Ltd.'s (OSIL) 1.2-meter Tern buoy platform equipped with Nortek (Providence, Rhode Island) AquaDopp current proflers, Campbell Scientifc (North Logan, Utah) OBS turbidity sen- sors and Hydrolab multiparameter sondes, which need to be strategically located within the proposed dredge site to avoid erroneously high or low data readings. Defning Threshold Limits Prior to undertaking dredging and/or disposal projects, a careful assessment by a competent authority to identify potential effects and to determine their signifcance is nec- essary. The environmental impact assessment (EIA) should take into account the background data previously gathered, identify all stakeholders, and defne acceptable threshold limits for contractors and stakeholders alike. For example, when planning and undertaking operations for the London Gateway Project, various stakeholders and interest groups were identifed and involved with setting the threshold limits for water quality parameters, including the Environment Agency, Marine Management Organisation, river leisure industries, Kent & Essex Sea Fisheries Commit- (Top) OSIL 1.2-meter Shearwater Buoys ready to ship to the client. (Bottom) OSIL calibration facilities. (Photo Credit: OSIL) (Photo Credit: OSIL)