Consolidating the state of knowledge of surface washing agents for oil spill response decision making

Surface washing agents (SWAs; also known as beach cleaners or shoreline cleaning agents) are oil spill cleanup agents that enhance the separation and removal of oil from substrates. Compared to conventional measures such as substrate removal or high-pressure/hot-water flushing, the fundamental advantage of using a SWA on oiled substrates is a higher degree of oil removal with reduced secondary impacts resulting from these more intensive conventional response strategies. SWAs are categorized in two groups; "lift and float" and "lift and disperse." The lift and float SWAs facilitate recovery of the treated oil on the surface of the water. The lift and disperse products include surfactants that result in dispersion of the treated oil into the water column. Because lift and float SWAs allow recovery of the spilled oil, they are preferred over lift and disperse agents. However, there may be conditions where use of a lift and disperse SWA would be best, such as where the released oil cannot be effectively recovered because of high wave energy or strong currents or no access for recovery operations at the treatment site. Lessons learned from 32 SWA use case studies are summarized. Potential ecological impacts resulting from SWA use are evaluated, and recommendations made to reduce those impacts through implementation of best management practices. Current methods for testing SWA effectiveness and effects are described, and recommendations are made for conducting SWA effectiveness and effect testing during operational responses, including for "tail-gate testing" on the actual oiled substrates and for first operational use in the field.