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

S0300-A6-MAN-060Diversion boom does not maintain nor should it be rigged to keep a straight-line shape. A straightlineboom is not desirable, as it tends to roll over and lose oil through entrainment. The force ofthe current naturally causes the boom to take a J-shape. The J-shape occurs toward the downstreamend of the boom. Oil will eventually entrain under the center in the J-shape or around theend of the boom. This oil can be collected by a second boom and skimmer arrangement locateddownstream but away from the shore.Large forces created by the boom trying to hold flowing water are reduced as the boom is movedto parallel the water flow. Mooring diversion boom in planned positions based on current andtidal flow directions makes the boom more effective.Where the geography permits, multiple diversion booms may be rigged. Multiple booms—knownas cascading booms—divert oil sequentially in the desired direction, as shown in Figure 4-11.Figure 4-11. Cascading Oil with Boom (Plan View).Oil spilled in waterways subject to fast-moving currents will spread over wide areas unless it isdeflected ashore for manual and vacuum pickup. Oil may be deflected into slower moving currents.The primary purpose of deflecting oil into slower moving currents is so it can be dealt withmore easily. Diversion boom can also divert oil past marina entrances, environmentally sensitiveareas, water intakes and other areas of concern. In tidal waters, booms must be adjusted or sec-4-19