Environmental legislation in Western Australia requires controls over the discharge of drilling wastes to preserve the natural environment. Nowadays, drilling operators use standard practices and treatments to reduce the drilling waste, which includes drilling fluids and wastewater.

Dewatering of the drilling fluids waste is one waste management practice that can help operators remain in compliance with environmental legislation. However, there are still some issues concerning the chemical cost and successfulness of the dewatering process. There is a clear incentive to reduce costs through optimum chemical selection, which, in turn, can lead to reduce equipment costs.

The primary objective of the research work reported here is to optimise the chemical consumption in the dewatering process. This has been achieved through a series of pilot tests carried out in the laboratory, and this paper describes the laboratory procedures employed to reach an optimum outcome. The procedures include the selection of the proper coagulants and flocculants by the common jar test method, and, in addition, the determination of the optimum chemical concentration by comparing the effectiveness of the dewatering process after centrifuge testing.