It has been argued that the presence of surfactants on the water surface of wavetanks from prior dispersant applications prevents the spreading of oil within the tank. It is further argued that the dispersant effectiveness (DE) measured in wavetanks could be severely reduced in comparison to the DE of the same dispersants at sea. Previous research has agreed with this argument and has advocated the flushing of the wavetank to ensure that no surfactants are present at the water surface. As this is not feasible for the Ohmsett tank due to its large size, this project evaluated the effect of residual surfactants and other ambient chemicals in the tank water, and their impact on dispersant testing in the Ohmsett tank.
This project has been completed.
Dispersant effectiveness testing conducted by a Baffled Flask Test using both synthetic seawater and water from Ohmsett showed that Ohmsett water produced a more effective dispersion. This is attributed to Ohmsett water having a lower hardness that synthetic seawater and ocean water (4,700mg/L of CaCO3 vs. 6,500mg/L of CaCO3). Also, it is believed that trace amounts of surfactant from previous test contributed a negligible change in effectiveness when testing at Ohmsett.