Meyer, T.G.H., Peter, P., Richards, B.G., and Townley, L. (1993), New Celebration tailings dams, Final report to Newcrest Mining Ltd, CSIRO Minesite Rehabilitation Research Program, 41pp., November 1993. [Confidential]

At the request of Newcrest Mining Ltd, a preliminary visit was made by Drs Brian Richards and Lloyd Townley to the New Celebration mine site on April 7 1993. Their preliminary report (Appendix 1) indicated that the north wall was potentially unstable and an investigation was subsequently proposed.

Later in April 1993, the proposed field program was begun and piezometers were installed in the tailings and dam wall at four wall sections, including the north wall. The piezometer readings were used to determine the piezometric water levels against the wall at these sections. These data indicated that the section on the north wall was leaking badly and that the section representative of the eastern wall was dry. An attempt was made at that time to sample a section through the north wall at the site where leakage was occurring, but this was unsuccessful due to the use of an inappropriate drilling rig. Following the field visit in May, 'intact' samples were successfully taken from the tailings, compacted tailings lifts, and the earthen walls at this site at several depths. Nine of these samples were subsequently selected as representative of the different materials present in the dam and forming the dam wall. These samples were tested in triaxial apparatus to determine the material stiffness and shear strength parameters. Subsequently, the mine surveyors have provided a surveyed section of the north wall where the field work was undertaken.

Using the geometry of the north wall and the measured material properties at the leaking section, finite element analyses of the seepage of water through the wall were carries out. When good agreement was obtained with the results from the piezometers, slope stability analyses were carried out to predict the factor of safety for the slope.