The cleanup of oiled shorelines has generally been by mechanical, labor-intensive means. The use of surfactants to deterge and lift the oil from the surface results in more complete and more rapid cleaning. Not only is the cleaning process more efficient, but it can also be less environmentally damaging since there is potentially much less human intrusion and stress on the biological community because chemicals can make washing effective at lower temperature. This paper will describe research on chemical beach cleaners for treatment of oiled shorelines that was initiated in support of the cleaning activities in Prince Willliam Sound (PWS) following the Valdez oil spill in March 1989.
The concept for using beach cleaners for shoreline cleanup is to apply a pre-soak to the weathered crude oil on shore and then flush with sea water to wash the oil into a boomed area for subsequent recovery. Criteria imposed on the use of chemical beach cleaners for the cleanup of the Valdez spill were: (1) effective rock cleaning agents should have very little or no toxicity to marine and terrestrial life, (2) there should be no dispersion of the oil washed from the shoreline into the water column; oil was to be recovered by techniques such as skimming or sorbents, and (3) the agents should be on the EPA National Contingency Plan (NCP) list.
A laboratory-scale rock washing test was developed to measure cleaner effectiveness and dispersion. A large number of commercially available formulated products were evaluated, as well as developmental formulations. The commercial products included all of the available NCP-listed products which could function as cleaners. None of the commercial products completely satisfied all the requirements established by the agencies for beach cleaning. However, a new formula, called COREXIT 9580, consisting of two surfactants and a solvent was developed. It exhibited low fish toxicity, low dispersancy and effective rock cleaning capability.
Although it was not approved for use in Alaska other than testing, subsequent work at ENVIRONMENT CANADA confirmed the outstanding cleaning effectiveness and very low toxicity of the new product, and it is currently on the approved product list in Canada.
The paper reviews the laboratory and field testing conducted to prove out this new product and highlights more recent work on mangroves to explore the potential use of COREXIT 9580 to save and restore oiled vegetation.