THE BEHAVIOUR AND TREATMENT OF ORIMULSION® BITUMEN STRANDED ON PEBBLE, COBBLE OR IMPERMEABLE SUBSTRATE SHORELINES

Bitumen from an Orimulsion® spill can strand on shorelines in the form or dispersed bitumen or coalesced bitumen. Wetness of the shoreline substrate is an important factor in the adhesion of the bitumen and this in turn significantly effects selection of a treatment technique. Stranded bitumen on the surface of a shoreline that remains wet and/or non adhesive can be removed relatively easily by a combination of low-pressure washing, flooding, and recovery, or by manual and mechanical removal techniques. When stranded on dry surfaces or when interfacial surfaces dry, then the bitumen will strongly adhere to shoreline substrates either in the form of thin coatings or thick deposits of bitumen that are difficult to remove. Heated, high-pressure seawater washing is effective but must be accompanied by flooding to minimize penetration into coarse sediments. Sediment relocation, sediment removal, wet tilling and natural recovery techniques are appropriate techniques under specific oiling conditions. Temperature greatly effects bitumen penetration into sediments. Where bitumen coatings or deposits form in subsurface sediments then treatment becomes extremely difficult, requiring sediment removal or techniques to bring oiling surface sediments to the surface for treatment.