Environment Court panel (from left) commissioner Alex Sutherland, Judge Jeff Smith and commissioner Ann Leijenn question a panel of specialist witnesses at the second day of a hearing in Dunedin into an appeal of conditions relating to Port Otago depositing sediment off-shore of Taiaroa Head. Photo by Peter McIntosh.
Port Otago has proposed three monitoring sites be established
to track sedimentation movement as a result of it dumping
dredged spoil off Dunedin's shores, in an effort to protect
the coastal environment.
Fisheries interests have appealed to the Environment Court
conditions around Port Otago's consent to dump dredged
sediment from Otago Harbour, 6.5km off Taiaroa Head.
An Environment Court panel led by Judge Jeff Smith yesterday
heard evidence from a panel of experts representing Port
Otago, Otago Regional Council and the fishery interests as
well as from Port Otago infrastructure general manager
Lincoln Coe, fisheries consultant Richard Boyd and Otago Rock
Lobster Industry Association executive officer Simon Gilmour.
Judge Smith said the aim of yesterday's session was to work
out how conditions might be worded or framed so the process
could be caught before it went wrong and adversely affected
the inshore environment.
He warned that if the parties could not find solutions to the
issues, the court would.
"I know you have made an honest attempt to get it solved in
the past six months."
Len Andersen, counsel for Port Otago, said discussions
between the parties had resulted in a proposal to install
three monitoring points, at 500m south of the dumping site
boundary, 500m northwest of the boundary and 1km north east
of Cornish Head.
Regular sampling was proposed while the large dredge was
operating and for four months during the smaller New Era
dredge's operation in a variety of conditions.
From there, he saw an exceedance level being agreed to and
below that a suite of management actions.
Niwa programme leader hazard and risks Dr Robert Bell, for
Port Otago, said in answer to a question from Judge Smith,
modelling showed moving the dump site 2km east would not make
a lot of difference to the amount of silt deposited inshore.
University of Waikato senior lecturer in coastal oceanography
Dr Willem de Lange, for the Otago Regional Council, said if
it was moved further offshore it would put the sediment in
stronger currents which meant it would travel further in a
northerly direction than at the dump site (AO).
"In terms of the options presented, AO was the most desirable
Capping the silt at the dump zone would increase the mound;
it would be more effective to mix silt and sand during
dredging, he said.
Trialling the monitoring method at the existing maintenance
dump site would give parties a chance to fine-tune the
process and get a "handle" on what would happen if the plume
from the dumping bypassed the sensor.
Judge Smith said there appeared to be some agreement on using
turbidity measure NTU to judge if sedimentation was going
where it should not.
University of Otago lecturer in aquaculture Dr Chris Hepburn,
for the fishing interests, said photosynthetically active
radiation sensors should also be used to judge light levels
around the reefs and kelp beds near shore.
A suggestion by Judge Smith that Port Otago use a back hoe to
remove silt from the harbour as it would not disturb
sediments as much as the proposed suction dredge was "not a
realistic possibility", Mr Andersen said.
Mr Coe said a back hoe would have to be sourced off-shore,
was less mobile, would take longer to do the job and was
Mr Boyd told the court any risk to rock lobster from the
dumping was very small but agreed it could not be ruled out.
However, Mr Gilmour said they were concerned the dump site
would affect larvae that populated the coast's rock lobster
The hearing was adjourned until Friday to allow the parties
to develop conditions and an environmental management plan
with assistant from commissions Alex Sutherland and Anne