Brigitta Montanari
The
Italian chemical tanker Brigitta Montanari, transporting more than
1,300 tonnes of vinyl chloride monomer (VCM), sank in the Adriatic
Sea on 16 November 1984, to a depth of 82 m, near the city of Sibenik
(Yugoslavia).
The
solution chosen to deal with the wreck was to refloat it, then to
pump out the chemicals. This decision was made based on ecological
considerations, but also technical feasability, safety and economic
viability.
Rescue operations began in August 1987, on the assumption that the
vinyl chloride monomer tanks had not been damaged. However a leak
of VCM estimated at 1 kg/day was detected at the beginning of the
operation. The leak was thought to be situated between the left
side of the wreck and the deck (the wreck was lying on the right
side).
Operations began by positioning the wreck on its keel. This
operation is often the first step in raising procedures, however
it could have been dangerous because of the risk of a sudden spill
of a large quantity of vinyl chloride. To release this chemical,
a 5 mm hole was drilled in the deck. An significant leak of VCM
began (estimated at 3 tonnes/day). A concentration of vinyl chloride
greater than 5 µg/L was observed in the water column, 300
m from the wreck.
After the chemicals had been leaking for several days, divers connected
PVC piping to the holes which had been drilled. The vinyl chloride
was piped to the suface where it dispersed into the atmosphere or
was burned.
The operations were stopped in winter 1987, then resumed in spring
1988. The wreck was raised to a depth of 55 m to be towed underwater
to a small sheltered bay near the island of Kaprije, where it grounded.
It was then raised to a depth of 30 m, while insuring that the hydrostatic
pressure was higher outside the tanks. This precautionary measure
was taken to avoid vinyl chloride being released from the corroded
tanks. 700 tonnes of vinyl chloride were then pump tranferred into
another boat.
Biological monitoring began in 1987 on bottom-dwelling populations,
including histopathological exams and biochemical testing. Organism
samples were taken from the wreck and the surrounding area, as well
as from a non-polluted control site. The results showed that the
vinyl chloride leak had not resulted in any acute toxic effect on
the organisms studied. The wreck was covered in marine organisms,
despite the fact that the vinyl chloride concentration in the immediate
surroundings was often relatively high (over 10 mg/L).
In light of the biochemical and histopathological results, it appears
that sublethal effects could take place on sedentary bottom-dwelling
fish, however these results were not confirmed.
Name: Brigitta Montanari
Date: 16 November 1984
Location: Croatia
Accident area : off Sibenik, Adriatic coast
Cause of spill : damage to ship
Quantity transported : 1,300 tonnes
Type of pollutant : vinyl chloride monomer
Quantity spilled : 1,300 tonnes
Ship type : chemical tanker
Date built : 1975
Length : 68.41 m
Width : 11.84 m
Flag : Maltese
The Brigittta Montanari sinking off Adriatic coast
(source : http://bezkomentara.bloger.hr/)
Source:
- The sinking and fate of the chemical tanker Brigitta Montanari, M.AHEL. Centre of Marine Research Zagreb, Rudjer Boskovic Institute, Zagreb Yougoslavia
Last update: April 2006