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Behavior of Oil

The #6 fuel oil from the Bouchard 155 barge is the only material known to have been
released during this incident.  The oil initially formed a contiguous slick that moved
west out of Tampa Bay.  Once out of the bay, the oil moved west and north into the Gulf of
Mexico where it began to break up into more widely scattered fields and tarballs with some
heavy concentrated bands.  The winds were predominately easterly initially, but began to
shift to westerly by August 12.   This wind shift began to drive the oil closer to shore.
By August 14 shoreline oiling, reported as light tarballs, was occurring from southern St.
Petersburg Beach north to Madeira Beach.  By August 15 most of the floating oil had come
ashore and heavily coated sand beaches, several mangrove islands, and seawalls within Boca
Ciega Bay.  By August 16 very little floating oil was seen offshore.

In the shallow, low-energy areas along the mangrove islands inside Johns Pass and at a few
locations in the surf zone, a small fraction of the total spill mixed with beach sand and
shallow sediments to form underwater tarmats.  These mats have been described as having
the consistency of frosting or peanut butter with an outer skin that holds the mat
together.  The mats within the bay area tended to fall apart once this skin was ruptured,
but the mats offshore maintain their cohesiveness.

Several tarmats were located offshore in 6 to 20 feet of water.  They average 20 by 150
feet and are about 2 inches thick.  This oil should weather very slowly and the mats will
probably remain in place.  Two of the mats are located perpendicular to the shoreline in
dredged borrow areas dating to 1985.  The area is to be mapped to locate any additional
tarmats.  The FOSC has issued an administrative order to the RP directing them to remove
the submerged oil.  Procedures for this operation are currently under review and
development.  The GST will help evaluate options for removing the submerged tarmats.