System Model Development of Two Fast Current Oil Removal Systems

Abstract

ABSTRACT Presently, the effective removal of oil spills is limited to current speeds of about one knot. There are several high risk areas of the country where currents are in excess of one knot. To be able to effectively recover spilled oil in these areas, the Coast Guard has initiated a program to develop suitable systems. This program and the results to date are discussed herein along with its projected future direction. INTRODUCTION The most common technique available today to control oil spills is the floating boom that supports a vertical skirt extending down into the water to form a barrier to the passage of the oil. At currents in excess of about one knot, the oil slick will not be contained by the boom and will flow beneath the barrier as the oil droplets are entrained by the escaping water. This phenomena applies to any oil recovery device that establishes a relative velocity in excess of about one knot between the oil and the water. The effectiveness of these devices is even further limited by the action of winds and waves. A large number of oil spills occur in rivers, estuaries, and bays with velocities in excess of one knot. Today, the only way of cleaning up spills in these situations is to wait until it is caught by back water areas and then apply conventional clean up techniques. Another aspect of this problem is the slick that has spread out over a vast area. To recover this type of spill effectively requires the capability of rapidly picking it up with a speed of at least three to four knots in order to effectively maneuver. The opinions or assertions contained herein are the private ones of the writer and are not to be construed as official or reflecting the views of the Commandant or the Coast Guard at large. The National Oil and Hazardous Substances Pollution Contingency Plan gave the Coast Guard the responsibility of removing oil discharges on the waters of the United States. Since the fast current problem existed in many of these waters, the Coast Guard initiated a program to develop a suitable oil spill recovery system. INITIAL RESEARCH The initial part of this program consisted of two parallel efforts. One of these efforts was to investigate the feasibility of various processes to recover oil in a fast current situation. The other was to determine suitable support systems and the environmental factors that would be encountered in trying to pick up oil in a high current situation. Process Feasibility Study A study by Texas A &M investigated the behavior of a floating oil slick subject to various external mechanical influences and to the action of current and waves. Oil diversion schemes, rapid removal techniques, and energy absorption barriers were evaluated. Energy dissipation and rapid removal by lifting appeared to have the most promise for fast current oil recovery.