Melbourne and London
Following technical difficulties at its Coke Making Plant, BHP Steel commenced discharging waste processed water into the main drain at Port Kembla Steelworks at 7.00pm on Monday 22 October.
The company has advised the New South Wales Environmental Protection Authority (EPA) of the incident. EPA representatives have inspected the area and taken samples of the water.
The water was released following the blockage of cooling sprays with tar in the Steelworks' 7A coke battery.
Under normal circumstances, the coke ovens gas cooling system operates as a closed circuit, recycling a 'flushing liquor' that is used to reduce the temperature of gas produced during the coke-making process.
To ensure the continued safety of the plant and personnel, production operations were suspended on 7A coke battery and fresh water introduced to cool the gas until the blockages could be cleared.
This has had the effect of introducing additional water into the cooling system, exceeding the capacity of the Steelworks' process water containment facilities. As a result, water overflowed to an emergency retention basin for a period of 11 hours before the need arose to discharge to the drain.
Following the discharge a number of dead fish have been observed in the Steelworks' internal drain system and Allans Creek.
A further consequence was the tar contamination of recycled waste water to the 6 coke battery quencher basin, which resulted in a yellow discolouration of the quencher plume at 4.40pm on 22 October. Remedial action was taken as quickly as possible to remove the contaminated water from the quencher feed.
BHP Steel Vice President Primary Operations Ross Murray said an investigation into the cause of the blockage is underway and the company is working to rectify the problem as quickly as possible.
It is expected that there will be further overflow into the main drain during this time, however the source of the 'flushing liquor' contamination was stopped earlier this morning.
BHP Steel has also established a monitoring process to test all water that is subsequently discharged.