standardization of environmental data and information - International ...

SUMMARY OF DISCUSSION
Size of environmental assessment area
A contractor wondered whether it would have to conduct a vast
environmental study on its entire claim area when it was likely to mine only
about 10,000-20,000 km² over the next 25 years. As the economical
viability was unknown, the likely scenario would be to start small, see how
things went and, if they did not go well, close down.
Dr. Sharma replied that, if a contractor had not yet identified its
mine sites, it could collect baseline data for the entire claim area, but if it
knew its sites and thought they would be enough, there would be no need
to gather baseline data all over the area.
Scale of impact
Participants, referring to Sharma’s figure of 300 km 2 /yr as the size
of the area to be mined by a single contractor, discussed how the size of the
impact area should be extrapolated from BIEs to actual mining, and how
large the impact area would be relative to the area mined.
Dr. Craig Smith recalled that the JET experiment had made 26 tows
with a disturber that had resuspended sediment from a track 1 m wide.
Thus, by analogy, a swath of sediment 26 m wide had been mined.
Resedimentation effects had been detectable up to 200 m on either side,
so that the mined area could be multiplied by a factor of 20. Actual mining
would cover a swath 1-10 km wide, extending for 15-20 km, and the plume
would cover an area several times larger.
However, a participant observed that, as the tracks were parallel,
the 200-m impact area in the experiment was smaller than Smith had
calculated, running only from the border of the overall mined area. A miner
would want to clear the entire area, which might be in the range of 1-3 km
wide by 10 km long. The likely extent of the plume was unknown, given the
fact that contractor might be able to limit it in a way that reduced the width
of the disturbed area. Moreover, the miner would run back and forth over
the area disturbed during a previous pass, until at the end the disturbed
area would be confined to the margin of the mined area. Thus, the
disturbed area would amount to much less than each track multiplied by
400 m.
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INTERNATIONAL SEABED AUTHORITY