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M/V Alvenus

Date 4 September, 1984 . To Capt. Shaw  MSO Galveston . From Todd Baxter  SSC . Subject
Weathering of ALVENUS Oil on the Galveston Sea Wall. Your question of last week on
weathering of the oil on the sea wall was passed to our chemical consultant, Dr. Ed
Overto. He contacted Mr. Jim Payne and Mr. Dan McNabb of S.A.I., for the results of
chemical analysis and a weathering model run conducted at our request. The following is
his comment on the subject: "Weathering is a term used to describe the collective chemical
and physical changes which alter both the composition and characteristics of crude oil and
petrolreum products spilled into the marine environment. The chemical changes include
those oxidative reactions caused by microbial and photo induced processes. These changes
tend to transform crude oil and petroleum products into substances that are water soluble
and can be available as food stuff for microorganisms that live in the water column.
Physical weathering processes include evaporation, dissolution, and the formation of
emulsions. The composition of crude oils and petroleum products determines which of these
processes are importamt in altering the composition of spilled material.  The crude oil
spilled by the Alvenus contained approximately 60% material that is not readily
succeptable to degradation by the weathering processes. Consequently, much of the spilled
material will remain, unchanged, as an oily residue in the environment. Normal weather
conditions will not be very effective in promoting removal of this oily residue. Harsh
meterological conditions, such as hurricanes or winter storms, may cause enough errosive
action to remove the oily residue from the sea wall."  Dr. Ed Overton, LSU A very good
reference on the subject of oil spill cleanup is 'Oil Spill Cleanup: Options for
Minimizing Adverse Ecological Impacts' by Thomas L. Johnson and Robert A. Pastorok, 1982.
Published by Tetra Tech. Inc., 1900 116th Ave. N.E., Bellevue, Washington 98004. Section
3.5 of this report deals with cleanup of the 'Rocky Intertidal', which fits the Galveston
Sea Wall case. Several case studies are reviewed in this section, and I will condense the
findings as follows. In the case of the TAMANO (No.6 fuel oil) in 1975, the ARROW (bunker
C) in 1970, and the AMOCO CADIZ (Saudi Crude) in 1979, several methods were tested for the
cleaning of rocks and concrete of spilled oils. These included high and low pressure water
flushing, steam cleaning, sand blasting, hand wipe-down, and chemical dispersant. Each of
these methods has limitations, the most common being recovery of the displaced oil. In the
case of the AMOCO CADIZ, very high pressure water (5,800 to 13,000 psi) was found most
effective between weeks 6 and 9 of the spill. The oil is described as being much the same
as the ALVENUS oil during this period. Steam cleaning was used on piers and jetties, in
conjunction with sand blasting as well. Containment booms and hand held sorbents were used
to collect the displaced oil, though a signifigant ammount escaped to remain behind after
cleanup was completed. The use of the hydroblaster seems as effective as any other method
mentioned in the literature. The recovery of displaced oil is a problem with no easy
solution. Further hardening of the oil is not probable based on the chemical analysis and
professional opinion presented. Thus, the question of waiting 6 to 10 weeks for oil
hardening does not show promise of results. On the other hand no negative result can be
seen if the decision is made to suspend cleaning for a brief period. A rest for the
cleanup crews alone may be worth the delay in final cleanup.