Townley, L.R. (1995), Review of regional groundwater modelling for the Cannington Project, Report to BHP Minerals Pty Ltd, CSIRO Division of Water Resources Consultancy Report No. 95/7, 16pp., February. [Confidential]

This report provides a review of three reports by RUST PPK (1994a,b,c) on groundwater modelling of the Longsight sandstone aquifer and the impacts of the proposed Cannington and Osborne borefields of BHP Minerals Pty Ltd and Placer Pacific Ltd, respectively. The objective of the review was to confirm that the AQUIFEM-N data sets provided by RUST PPK (1994c) are sufficient to allow the model to be used at a later date. Such an assessment could not be made, however, without a complete understanding of the modelling carried out to date. Thus this report also contains comments about the conceptual model and results to date, which extend beyond the original objective of the review.

The models of the Longsight sandstone aquifer appear to provide a good presentation of the observed piezometric surface, and is well designed to allow predictions of the cones of depression caused by the borefields. There are several reasons why model predictions may be conservation, in the sense that actual drawdowns may be smaller than those predicted. It is suggested, however, that monitoring be carries out at an additional site to the west or northwest of the Cannington borefields, to supplement the three sites already recommended by RUST PPK (1994a, p.19. Figure 17). The data sets provided by RUST PPK (994c) have a few minor inconsistencies, however any experienced user of AQUIFEM-N would be able to use the data provided to reproduce and extend the model in a very short time. In general, the work of RUST PPK appears to be of a high standard, consistent with the state of knowledge at this time.