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

S0300-A6-MAN-060• Fences are wooden barriers built across the water flow to hold sorbent materials. Thefences are not solid and allow water to pass. Oil is absorbed as it makes contact withthe sorbent materials. Sorbent material is removed after it has extracted the oil from theflowing water. Fences do not stop all of the oil from passing; a series of fencesimproves oil removal efficiency. A typical fence type sorbent barrier is shown in Figure4-6.• Pneumatic barriers employ a screen of bubbles released below the water surface. Therising air bubbles create an upward water flow. At the surface, the upward water flowcreates a slight mound on the water and diverts horizontally to form currents that flowaway from the bubble stream as shown in Figure 4-7. The water mound and surfacecurrent can retain oil in low current areas. The principle advantage of pneumatic barriersis that they are fireproof and do not obstruct ship passage. Their primary disadvantagesare the time and effort required to transport and set up air compressors, hose,diffusion piping and other equipment at the spill site and the fact that any malfunctionthat interrupts air flow will destroy the barrier and allow oil to spread. Pneumatic barriersmay be permanently installed at oil terminals or other high traffic areas.4-2.5 COMNAVFACENGCOM Boom. This boom is maintained and operated by NOSCDRsunder the direction of the NOSCs at various locations worldwide. NAVFAC boom is procured byactivities under Military Specification MIL-B-28617C. The three classes of boom depend uponthe environment for which it is suited:• Class I - for quiescent water with low currents and waves.• Class II - for open water harbor environments with moderate waves and currents.• Class III - for water with high waves.The MILSPEC requires durability and ruggedness that is available only with closed-cell foam orother puncture-proof materials for flotation. All fabric must be able to pass strength, tear, abrasionand weathering tests. Other features required of boom complying with NAVFAC specificationsare:• Stability and strength during a straight line or U-shaped tow.• Boom hardware that allows easy connecting and disconnecting in the water.• Floating single-point tow assembly.• Sliding bulkhead attachment points.Table 4-2 shows the three NAVFAC boom measurements and operational ranges.4-12