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A STRATEGY FOR PROTECTING CIRCULATING SEAWATER SYSTEMS FROM OIL SPILLS
Citation:
Young, D R., D T. Specht, AND R J. Ozretich. A STRATEGY FOR PROTECTING CIRCULATING SEAWATER SYSTEMS FROM OIL SPILLS. Presented at International Oil Spill Conference 2003, Vancouver, Canada, April 6-10, 2003.
Description:
The double grounding of the freighter New Carissa, and resultant oil spills, on the central Oregon coast in spring of 1999 caused great concern regarding possible petroleum hydrocarbon (PHC) contamination of Coos Bay, Alsea Bay, and Yaquina Bay estuaries. Among these concerns was the perception that the circulating seawater systems of several local marine research institutions or aquaria needed to be shut down to avoid major contamination and lengthy, expensive cleaning-up efforts. In response to this concern, a simple, rapid water monitoring program was devised and established to provide sufficient warning of high seawater PHC levels to temporarily interrupt seawater uptake into the associated circulation system. This program included (1) walking adjacent beaches at high tide in search of tar balls, patches, or sheens; (2) continuous pumping of subsurface seawater from the depth of intake to a small, baffled aquarium tank designed to accumulate both negatively-buoyant materials such as tar balls, and floatables such as oil slicks; and (3) instantaneous sampling of subsurface, nearsurface, and surface slick water samples for rapid analyses of PHC levels quantified as marine diesel oil equivalents (MDE). The average and highest subsurface water concentrations of MDE observed were about 4 and 10 ppb (?g/liter), respectively, well below reported thresholds of aquatic toxicity. In comparison, nearsurface water collected from the fishing fleet anchorage across Yaquina Bay averaged about 20 ppb MDE. Similar results were obtained from the monitoring of two subsequent oil spills in the estuary, demonstrating the usefulness of this simple approach in making decisions regarding the costly interdiction of circulating seawater at marine institutions.