The Observer, May, 2009

Study shows new skimmers work better

A new study by the citizens’ council shows that Alyeska’s Current Buster skimming system, adopted three years ago, can collect spilled oil up to five times better than the traditional U-boom configuration.

The council study examined encounter rates, meaning how much oil a skimming operation will encounter in a given period of time. The key to effective oil-spill response is getting lots of oil to the skimmer. That can be difficult in real-world conditions because oil spreads after it is spilled and because the slick is affected by wind and sea currents.

“Spilled oil is messy stuff, and it can get away from you real fast,” said Dan Gilson, the council’s oil spill response project manager. “Obviously, the faster you can encounter oil, the better off you are.”

The Current Buster’s advantage is greater the farther the oil is spread out, Gilson said. The Current Buster can operate at about 4.5 mph, while the U-boom system’s top speed is just under 1 mph.

The report also shows that Alyeska’s Ship Escort/Response Vessel System, or SERVS, can recover oil better from a spill that leaks over time than from a fast, catastrophic discharge.

“SERVS could just park their skimming systems near a stricken tanker and collect the oil as it came out and was at its thickest. That’s what those systems are really designed to do,” Gilson said. “The report shows that recovery of oil would be much less effective if the response system had to chase thin oil slicks. The report shows these shortfalls when applying actual environmental conditions to the planning standards, so the message is clear that prevention is the best solution to the problem of oil spills.”

The report also emphasizes the importance of maintaining fast response times and for advocating for recovery systems with high encounter speeds.

With state approval, Alyeska adopted the Current Buster system in 2006. The changed raised concerns for the council about whether the new equipment was really better than, or at least equal to, what it was replacing. The council hired a contractor to analyze the encounter-rate question, leading to the new report. Titled Prince William Sound Recovery Rate Analysis, the report by Censum Northwest, LLC, is available on the council website at www.pwsrcac.org/docs/d0048600.pdf.

State regulations and the oil-spill contingency plans for Prince William Sound require Alyeska to have enough equipment and personnel to contain and clean up 300,000 barrels of oil in 72 hours.

• Dan Gilson is a project manager for the council.

return to this edition