The mechanical recovery of oil in ice-infested water presents unique and difficult clean-up challenges. Ice can impede the movement of spilled oil making it less available for removal by the active components of oil recovery skimmers. Ice and slush that is recovered with oil can jam the skimmer, pump inlets and hoses and can provide an environment for enhanced emulsion formation. Low temperatures increase oil viscosity, further complicating processing and pumping of recovered product.
In response to these challenges, the U.S. Department of the Interior’s Bureau of Safety and Environmental Enforcement (BSEE) recognized the need for comprehensive programs of testing and research in the area of oil spill response in icy waters. BSEE has supported and sponsored a number of testing and research programs at the Ohmsett facility involving oil in cold water and ice. During the winter of 2013, BSEE sponsored an oil-in-ice spill test at Ohmsett titled Skimmer Tests in Drift Ice: Ice Month 2013 at Ohmsett. The tests involved ten commercially available skimmers that represented a range of skimmer types. Testing was done in the Ohmsett test basin using a controlled test area with fabricated ice. To the best extent possible, test variables such as water temperature, oil characteristics, oil slick thickness, ice coverage and size distribution, and skimmer operations were controlled. Performance determinations were made for oil recovery rate and oil recovery efficiency as per the general principles and guidelines of ASTM F2709. Tabulated results for the same are presented.
At lower ice coverage (30% ice), there was no significant mechanical impediment for most skimmers. However, ice can interfere with the flow of oil to the skimmer periodically even in this coverage. At higher ice coverage (70% ice), there was significant impediment to skimming, with most skimmers having dramatically lower rates and efficiencies. It was also observed that with longer exposure to skimming under these conditions, operators became more proficient with regard to recovery performance. This indicates the importance of training and practice for effective skimming operations.
Testing of Oil Recovery Skimmers in Ice at Ohmsett - The National Oil Spill Response Research & Renewable Energy Test Facility