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

S0300-A6-MAN-060time. Most skimmers have only a limited storage capacity. To avoid frequent trips by skimmers tothe storage vessel, oil storage bladders (dracones) can be towed by the skimming vessel. Workboatscan shuttle empty bladders to skimmers and full bladders to central storage or dischargepoints. Alternatively, small coastal tankers can accompany skimming vessels to receive skimmedoil.It is often difficult to find adequate barge or lightering vessels at remote locations. TransportableESSM oil storage bladders are a method of augmenting barges and tank storage ashore. In longterm,large-scale operations, it may be necessary to dispose of some of the recovered oil whilerecovery operations are still ongoing, to free storage space, rather than dealing with disposal afterrecovery and cleanup operations are finished.5-3.3 Oil-Water Separation. Because skimmers recover a sometimes-emulsified oil-water mixture,it is desirable to remove water from the recovered mixture to conserve storage space.5-3.4 Skimming and Sweeping. Spilled oil can be recovered by skimmers operating inside containmentbarriers. For effective recovery of oil spread over a wide area, recovery systems consistingof boom and skimmer combinations or specialized large recovery vessels concentrate andrecover oil from broad areas.5-3.4.1 Single-Vessel Sweep System. A single-vessel sweep system consists of a vesselequipped with special booms or sweep arms extended from one or both sides of the vessel by rigidarms or bridles. Oil encountered by the vessel is concentrated by the extended sweep arms andrecovered by skimmers built into the vessel hull or sweep arms or operated from the vessel deck.5-3.4.2 Two-Vessel Sweep System. Two-vessel sweep systems consist of a length of boom,a boom-towing vessel and a skimming vessel. The vessels operate in one of the two configurationsshown in Figure 5-11. Recovered oil is stored aboard the skimming vessel, a towed bladderor an accompanying vessel.Figure 5-11. Two-Vessel Sweep System.5-15