The Observer, January 2007
Better procedures needed in dispersant trials
A new citizens’ council report recommends several improvements to dispersant testing procedures at the federal government’s Oil and Hazardous Materials Simulated Environment Test Tank in New Jersey.
The report is the last of two prepared by council consultants Merv Fingas and Elise Decola after they observed tests at the facility – known as OHMSETT – in February and March of 2006.
Test procedures at the OHMSETT facility fail to account properly for the resurfacing phenomenon, shown here, according to the council’s report. Photo courtesy of Merv Fingas.
OHSMETT, operated by a contractor for the U.S. Minerals Management Service, resembles a huge outdoor swimming pool. It is 667 feet long by 65 feet wide and holds 2.6 million gallons of sea water. In the tests, a traveling bridge sprays oil onto the water followed a few seconds later by the chemical oil-spill dispersant.
Researchers attempt to measure effectiveness by visual observation, instrumentation, and recovery of undispersed oil remaining on the water.
Fingas and Decola recommended a series of measures to improve the accuracy of OHMSETT results:
• Use a quantitative method of measuring dispersant effectiveness. At present, the OHMSETT tests do not include what is called a mass balance – an attempt to account for all oil put onto the water. Typically, some of it disperses into the water of the tank, some evaporates into the air, some fails to disperse and remains on the surface, some attaches itself to the walls of the tank or to equipment used in the tests, and some that does disperse resurfaces later. Some of the test procedures – such as herding remaining oil with fire hoses for recovery and measurement – probably cause additional dispersion, according to the report. It recommends finding a way to recover dispersed oil.
• Use correct analytical procedures. The report faults the OHMSETT researchers for inadequate calibration of test instruments and use of the resulting date. The report also notes there is no measurement of wave energy, a critical factor in the dispersion process.
• Continue to take measurements for at least six hours after the dispersant is applied. In the typical OHMSETT test, measurement ends less than an hour afterward. As a result one of the major problems with dispersant use – resurfacing of the oil in a new slick – is not evaluated in the OHMSETT test.
Fingas and DeCola did note that the 2006 tests appeared to resolve some of the problems identified in previous tests at OHMSETT. Those problems had included applying dispersants to heated oil rather than oil that had been allowed to cool to ambient air temperature; the use of booms to contain the oil during the tests; and testing dispersants on artificially weathered oil rather than oil that had been allowed to weather naturally, as would occur after an actual spill.
Because of the many questions about the effectiveness of dispersants in cold seawater, as well as their toxicity, the citizens’ council board in May 2006 adopted a position opposing their use in the Exxon Valdez oil spill region until research is conducted that produces conclusive answers to the questions.
The new report, titled “Oil Spill Dispersant Effectiveness Testing in OHMSETT,” is available for download from the council web site at www.pwsrcac.org/projects/EnvMonitor/dispers.html. An earlier report by Fingas and Decola on the 2006 OHMSETT tests is also available on the same page, along with much additional information on dispersants.