Oil Spill Science and Technology, 2nd Edition

10.10. Final Recovery of Residue

The oil residue left after a burn is usually a heavy, tar-like material which is very viscous and adhesive, similar to a highly weathered oil. The greater the burn efficiency, the higher the density and viscosity of the residue. The burn residue from some types of oil may sink in the water column [173]. This behavior should be determined in advance for common crude and bunker oils being transported in American or Canadian waters.

The decision to recover the residue mechanically or leave it to break down biologically depends on the total volume of the residue, whether the residue is dense enough to sink, and where it is expected to go if left alone. Other considerations include the immediate availability of equipment ...