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

S0300-A6-MAN-060CHAPTER 4CONTROL, CONTAINMENT and PROTECTION4-1 INTRODUCTIONSpilled oil can be treated while it is floating on the water or after it comes ashore. It is simpler andless expensive to treat the oil while it is on the water surface before it spreads over a wide area.Initial, immediate spill response should focus on stopping or slowing oil flow with concurrentcontainment actions to limit the spread of already released oil. Measures to protect environmentallysensitive areas should be taken as soon as the direction of oil movement is determined.Limiting oil spread facilitates recovery, reduces the length of shoreline that will be fouled if theoil slick reaches shore and limits the amount of water and quantity of wildlife exposed to the oil.Short of preventing discharge, containing spilled oil for prompt recovery is the most effectivemeans of minimizing environmental impact of an oil spill.Securing the source of a major spill can be difficult and time consuming. Unless damage controlor oil removal actions can be initiated almost immediately after a ship casualty, initial spill sizecannot be limited in most cases. Oil flows out of severely damaged tanks at an extremely high rateuntil the oil head inside the tank equals the water head outside. If this occurs before all oil flowsout the tanks in a stranded ship, additional oil will be lost as the tide falls over the next tide cycle.In the 1989 EXXON VALDEZ spill in Prince William Sound, more than 95 percent of the oilspilled was discharged in the first nine hours following the tanker stranding—nearly 50 percent inthe first 20 minutes—long before salvage or spill control assets arrived at the scene. Removing oilfrom damaged tanks can prevent additional oil discharge resulting from fluctuating water levelscaused by waves, vessel motions, storms or extreme tides. Oil may be removed from undamagedtanks in a stranded or sunken ship to eliminate the potential for further discharge if the ship suffersadditional damage.Unlike spills from ships, where the spill source is finite, however large, oil well blowouts create avirtually unlimited oil spill source. Securing the source requires the services of specialists andmay take months. Until the source is secured, containment is ineffective unless oil can beremoved from within the containment barrier as fast as it is released.The Navy’s oil spill response philosophy, parallel to commercial operating procedures, is to capturethe spill with containment booms for mechanical removal before oil reaches the shore. Whenit is not possible to contain spilled oil completely or prevent it from coming ashore, boom can bedeployed to protect and divert oil away from sensitive areas or to bring oil ashore at selected locations.The Navy spill response organization provides equipment and personnel through existing contingencyplans. This chapter discusses spill containment equipment in the NOSCDR and SUPSALVinventories and related control and protection methods.4-1