HAVING finally won approval to mine the northern tenements in its Koolyanobbing Iron Ore Project near Southern Cross, Portman now faces another environmental issue.
This time the problems are at its joint venture with Henry Walker Eltin at Cockatoo Island Iron Ore project where production has been much slower than expected due to an unexpectedly big aquifer in the ore body and some slumping in the much-vaunted seawall.
Portman announced the Cockatoo Island workforce has been reduced and production cut back during a technical review of the problems.
In an announcement, the company said it was complying with its environmental obligations.
“Occasionally, the water discharged from the pit has caused some discolouration in the sea,” Portman said in a statement to the Australian Stock Exchange last week.
“It is not causing damage to the surrounding marine environment and every effort is being made to contain that discolouration.
“In respect of construction of the seawall and handling of waste from the pit, the joint venture strongly denies allegations of improper practices.”
The timing of problems on Cockatoo Island could not have been worse for Perth-based engineering firm GHD which said it had just been commissioned to design a seawall extension almost as big as the first construction.
With more than half a year of operations on the island under its belt, it started to trumpet its achievement with the construction of an 850-metre long, 15-metre high cofferdam which was completed in September last year.
Miners at Cockatoo Island for the past 60 years have had a continuous battle against the tides with much of the ore body hiding below the tides.
It seems previous leaseholder BHP was unable to go beyond low tide level in its endeavours. It baulked at building a coffer-dam into the sea to isolate the ore from the water because the seabed was too soft to support a dam and BHP ended up walking away from the island.
However, Portman and Henry Walker Eltin decided it could be done and contracted GHD.
In September the first cofferdam was built, using a clay core sandwiched between rock fill, and the sea pumped out to reveal the ore body.
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