Comparison of Real Time Plume Tracking Methods in Coastal Waters

Today´s stringent environmental regulations require comprehensive, highly defensible evaluations of environmental risk and impacts. Monitoring the fate and transport of potential contaminant releases to the aquatic environment is a critical compliance element for clean-up, remediation, maintenance, and other activities. It has become increasingly evident that high resolution plume tracking and dilution studies can substantially contribute to these monitoring programs and defensible environmental evaluations. This paper will discuss three plume tracking systems that are able to define plumes and collect water for calibration and contaminant measurements. These methods are conducting vertical casts with CTD and rosette of water collectors, towed body with CTD and water pump using a custom cable and winch (BOSScopy), and a multi-depth water sampling system (MDWS). The pros and cons of using each system such as spatial and temporal density of information will be discussed. The paper will finish with a series of case-studies presented to describe several different applications and methodologies for plume tracking. Based on the application a variety of systems may be used. These include towed arrays which cover large spatial scales in deeper waters, and rigid systems which capture fine scale changes in shallow water areas at multiple depths simultaneously. Highlighted projects include dredge resuspension tracking, certification of offshore outfall systems, and characterization of ship discharge streams. These programs have shown success at measuring dilutions down to 1:3200 and tracking plume behavior on time scales from minutes to several days. The use of these systems is transforming the way science and public agencies address compliance programs