U.S. Navy Ship Salvage Manual Volume 6 - Oil Spill Response

S0300-A6-MAN-060CHAPTER 6DISPERSANTS AND OTHER CHEMICALS6-1 INTRODUCTIONNavy policy advocates the mechanical recovery of spilled oil over the use of dispersants or otherchemicals. Because oil spill response chemicals may be environmentally damaging and do notremove oil from the environment, their use is strictly controlled or forbidden by regulatory agencies,particularly in the United States.Although mechanical recovery is usually preferable, chemical application is sometimes the bestresponse option and is deployed by the spiller or host government. Pollution control plans, therefore,may require immediate availability of dispersants during salvage and emergency POL offloadingoperations.Several types of chemicals can lessen or alter the environmental impact of spilled oil:• Dispersants that disperse slicks into small droplets of oil in the water column.• Surface collecting agents that enhance mechanical recovery.• Biological additives that encourage biodegradation.• Burning agents that facilitate in situ burning.• Sinking agents that cause oil to settle to the seafloor.The Navy does not stockpile nor recommend initial response with dispersants or other chemicals,however, salvage officers should recognize situations that favor chemical application over otherresponse options. Although not responsible for deploying chemicals, Navy salvors should haveenough technical knowledge to coordinate salvage activities and mechanical spill response measureswith the application of dispersants or other chemicals.6-2 DISPERSANTSThe first large application of dispersants was in response to the spill from the oil tanker TORREYCANYON, following her grounding and the release of 14,000 tons of crude oil off the coast ofCornwall, England in 1967. Approximately 10,000 tons of dispersant were applied during thisresponse. These early dispersants were essentially degreasers made for tank and bilge cleaningand consisted of extremely toxic surfactants and solvents. While effective in removing visual evidenceof spilled oil, these first-generation dispersants were harmful to organisms in shallow waterand along the shoreline. In many cases, the dispersants were more harmful than the spilled oil.6-1