A SCAT survey in 2002 documented conditions at 39 selected survey sites where EVOS oil persisted in 1992, at the time the Federal and State On-Scene Coordinators determined that further cleanup activities would provide no net environmental benefit. The 2002 field survey found isolated occurrences of residual EVOS surface oil (SO) in the form of weathered asphalt pavement at 15 of the 39 sites. SO, expressed as a continuous oil cover, was less 0.2% of the surface area surveyed. Seven of the 39 sites and 815 (68%) of the total 1182 pits contained no residual SSO. SSO was found primarily in middle to upper intertidal locations, where it occurred in discontinuous ∼3cm thick bands 5–10 cm below the boulder/cobble or pebble/gravel veneer. Despite evidence of continued oil weathering, both at the surface and in the subsurface, it is clear that the natural cleaning processes at these particular locations are slow. The continued but slow weathering rates are a consequence of the oil being sequestered from the environment because it occurs in mixed (coarse and fine) sediments on beaches where boulders and outcrops, shallow bedrock asperities, or boulder-armoring limit effective physical weathering action.

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