The reactivation of a landslide during the construction of the Ok Ma tailings dam, Papua New Guinea

The Ok Ma dam (Ok is a local word meaning river) was to form part of the permanent tailings disposal system designed for the Ok Tedi gold and copper opencast mine located at Mount Fubilan in the Star Mountains of Papua New Guinea. During the construction works a landslide involving approximately 35 million cubic metres of soil and rock moved downslope to partially fill the foundation excavations of the dam. The failure of this landslide was the start of an insurance litigation that finally reached the Supreme Court of Papua New Guinea in November 1989. The geotechnical, geomorphological and engineering geological data that were available at the time of the failure are presented together with an evaluation of the key deductions from the case study.

[1]  A. Davis.  The mineralogy and phase equilibrium of Keuper Marl , 1967, Quarterly Journal of Engineering Geology.

[2]  Alec Westley Skempton,et al.  Residual strength of clays in landslides, folded strata and the laboratory , 1985 .

[3]  P. G. Fookes,et al.  Geology for Engineers: the Geological Model, Prediction and Performance , 1997, Quarterly Journal of Engineering Geology.

[4]  J. M. Land,et al.  Some observations on a comparative aerial photography interpretation of a landslipped area , 1991, Quarterly Journal of Engineering Geology.

[5]  Ralph B. Peck,et al.  Advantages and Limitations of the Observational Method in Applied Soil Mechanics , 1969 .

[6]  An influence line approach to the stabilization of slopes by cuts and fills , 1984 .

[7]  P. G. Fookes,et al.  Comparison of interpretations of a major landslide at an earthfill dam site in Papua New Guinea , 1992, Quarterly Journal of Engineering Geology.

[8]  J. N. Hutchinson.  General report: morphological and geotechnical parameters of landslides in relation to geology and hydrogeology : Proc 5th International Symposium on Landslides, Lausanne, 10–15 July 1988V1, P3–35. Publ Rotterdam: A A Balkema, 1988 , 1988 .

[9]  J. N. Hutchinson.  The Fourth Glossop Lecture , 2001, Quarterly Journal of Engineering Geology and Hydrogeology.

[10]  Leslie R. Davison,et al.  Total Geological History: a web-based modelling approach to the anticipation, observation and understanding of site conditions , 2003 .

[11]  A. Davis.  The structure of Keuper Marl , 1968, Quarterly Journal of Engineering Geology.

[12]  D. Varnes,et al.  Landslide types and processes , 2004 .

[13]  James S. Griffiths,et al.  Proving the occurrence and cause of a landslide in a legal context , 1999 .

[14]  David M. Cruden,et al.  LANDSLIDE TYPES AND PROCESSES , 1958 .

[15]  E Lu F ffler.  Geomorphology of Papua New Guinea , 1977 .

[16]  L. Bjerrum.  PROGRESSIVE FAILURE IN SLOPES OF OVERCONSOLIDATED PLASTIC CLAY AND CLAY SHALES , 1967 .

[17]  John E. Costa,et al.  The formation and failure of natural dams , 1988 .