Research investigated the effect of a previously identified key containment boom characteristic on boom performance. Ohmsett testing examined the relationship between boom performance and buoyancy to weight ratio, as measured by first loss and gross loss tow speeds. These carefully controlled tests were compared to previous data on boom performance collected both at Ohmsett and elsewhere in controlled tank tests and during at-sea trials. The spill response community has expressed concern with low buoyancy to weight ratios allowed under existing U. S. Coast Guard response regulations as well as   the minimum ratios specified in the ASTM boom selection standard. The standards were approved with a note the “buoyancy to weight ratios greater than those listed in the table may result in improved boom performance under certain conditions, however, further research is required before minimum values greater than those shown in the table can be established.”

In testing, A fence-type boom was prepared with the ability to vary its floatation and eight elements. However, only a minor variation in buoyancy was achieved with the result that little variation in boom performance was observed.

With the curtain-type boom, buoyancies ranged from 3.8 to 10.4, which covers the range of interest for booms to be used in near-shore and protected waters. There was a significant decline in performance, as measured by first and gross loss tow speeds, with less buoyant booms. All booms had essentially the same performance when operated in calm conditions, first loss speeds of approximately 0.85 knots and gross loss speeds of 1.0 to 1.1 knots were observed. When operated in regular and harbor chop waves, the first loss tow speed was in the order of 0.5 knots and the gross loss speed was in the order of 0.6 knots for the less buoyant boom, while the values for the more buoyant booms declined only slightly.

The results of these tests could affect not only U. S. Coast Guard regulations, but MMS reviews of spill response plans. Results may also be used by the ATSM in developing revised standards for containment booms. Requiring improved, minimum standards in the areas of buoyancy to weight ratio could improve the effectiveness of mechanical spill clean up operations.

Complete

S.L. Ross Environmental Research, Ltd., and Applied Fabrics Technologies, Inc., The Effect of Buoyancy to Weight Ratio on Oil Spill Containment Boom Performance, Final Report, May 2003.

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Last Updated: 07/22/2008, 06:28 PM