Barr, A.D., Townley, L.R., and Turner, J.V. (1995), Estimated concentrations of calcium, ammonium sulphate and chloride in recovered groundwater near Baldivis tailings pond, Report to WMC Kwinana Nickel Refinery, CSIRO Division of Water Resources Consultancy Report No. 95/44, 39pp., November. [Confidential]

This report was commissioned by the WMC Kwinana Nickel Refinery to estimate the future trends of particular solutes in the groundwater recovered from near the Baldivis tailings pond. Using gross approximations about the flow regime towards the recovery pumps and the solute concentration distributions in the aquifer, a method of superimposing ellipses onto the concentration distributions has been used to calculate average annual concentrations of selected solutes in the recovered waters. Two different pumping rates of 2.0 ML day^-1 and 5.0 ML day^-1 were used, with part of the larger rate being used in a dual pump strategy.

The results show that the calcium concentration in the water has a range of 150-250 mg L^-1, with the higher concentration occurring at the start of recovery when using the larger total pumping rate. For all reasonable scenarios, the average concentration of calcium seems to settle around 150 mg L^-1.

The AMSUL concentration always declines with time. As time increases, the recovery system extracts a part of the plume that was originally further away from the tailings pond. The average concentration of AMSUL declines with distance away from the tailings pond, so when recovering these waters, the average concentration will drop. Furthermore, the thickness of the plume layer diminishes with distance from the tailings pond, thus the efficiency of the recovery of the plume also declines.

The chloride concentration in the pumped water remains constant within a band of 120-200 mg L^-1, with the higher concentration occurring with the use of dual pumping. An area of very high chloride concentration to the southeast of the tailings pond has the potential to increase the chloride concentration after 6 years of pumping at 5.0 ML day^-1.