Controlling Oil Spills in Fast Currents with the Flow∼Diverter

ABSTRACT Sixty nine percent (645 million tons annually) of the oil transported in United States waters is on waterways where currents routinely exceed one knot. Conventional skimmers and booms lose their effectiveness when current speeds exceed 1 knot. The US Coast Guard recognized that this threat could not be easily controlled, and so they initiated a project that led to the successful development of a novel spill control device, the Oil Spill Flow~Diverter. The Flow~Diverter system is effective at diverting and converging oil at speeds up to 5+ knots. In more moderate currents it can also be used in place of an anchor, towboat or outrigger arm to deploy and position the outboard end of a deflection boom. It may also have application to dispersant and in-situ burn operations. The diverter is a unique stable catamaran design that consists of two hulls each comprised of symmetrical foils with integral buoyancy. The foils are pinned to a rigid connecting structure such that they can pivot but always remain parallel to each other. Two or more diverter catamarans can be connected together with cables to increase the total sweep width of the system. Two control lines are anchored to shore or secured to a boat and are used to deploy the system by adjusting the foils’ angle to the oncoming water. With the control lines securely anchored, the system is launched into the current and “flies out” into a stable operating position. It remains in equilibrium, balanced by the hydrodynamic lift forces of the passing water and the tension in the lines. The foils create a strong transverse surface current downstream to achieve the desired diversion and consolidation affect on floating oil. Unlike most skimmers and deflection boom, the diverters are not adversely affected as currents increase. The oil is diverted by the same lateral distance irrespective of the current or speed of advance. This paper presents the development of the Flow~Diverter prototype, its testing and operational evaluations. Several applications of the diverter technology in various response tactics are discussed. Use of the Diverter during a recent US Coast Guard Spill Exercise on the Ohio River is also presented. Production model enhancements are presented that will enhance performance in 7+ knot currents and shallow water applications.