Article#3 Newcastle Steelworks- ENGINEERS MAG VOL 79

In Mayfield Newcastle a 1.5km, 49m deep bentonite barrier wall has begun to be constructed. This wall is part of a $110 million remediation strategy for the former Newcastle Steelworks.
BHP Billiton has owned the site since 1915. In 2002 the NSW government negotiated a land transfer with BHP Billiton. BHP Billiton demolished the buildings on site and RMLC staff set to work on how the site could be remediation that would be compatible with the future land use and acceptable to the environmental regulator.
A number of remediation and treatment options were discussed. Taking into account the depth of the containment it was concluded that capping and containment of containments was the best option, although more needed to be done about the control of the ground water.
This strategy had been designed to help contain the contaminated soils as well as manage contaminated ground water which it brings it into line with standard regulations which will allow the site to be used for industrial usage. This protects the adjacent Hunter River from any environmental damage.

The underground wall is being built in a water-charged area, which means it is a difficult task to build.
The construction method involved a continuous trench, which is up to several hundred metres long and only one metre wide. The trench is filled with bentonite slurry to support the trench in the water charged soil. The backfill is made up of soil and slurry replaces the bentonite at the rear of the trench to replace the slurry. The natural clay and rocks already in the soil support the lower part of the trench.
The concrete slabs that were left over from the steel works have been dug up and are ready to recycled on site. 80% of the concrete’s been crushed for use in the sub base for capping the site, while the remainder 20% will be used for the construction drains.