Report of the Inquest Into the Deaths Arising from the Thredbo Landslide

Report of the inquest into the deaths arising from the Thredbo landslide Derrick Hand Coroner 29 June 2000 Table of contents Table of contents .......................................................................................................................... 1 Table of abbreviations.................................................................................................................. 4 Summary ................................................................................................... 5 Introduction.............................................................................................. 8 The Landslide ................................................................................................................................ 8 Scope of the Report...................................................................................................................... 9 Submissions on Cause................................................................................................................10 Consideration of Cause Submissions.......................................................................................11 Hindsight......................................................................................................................................13 The Course of the Inquest.........................................................................................................14 Presentation of Technical Evidence ........................................................................................14 The Convocation of Engineers.................................................................................................15 Section 33.....................................................................................................................................17 Indictable Offence......................................................................................................................18 Legislative Framework ...............................................................................................................18 A Cautionary Note......................................................................................................................18 The Alpine Way .......................................................................................21 Responsibility for the Alpine Way............................................................................................22 Historical Understanding of Landslide Risk...........................................................................23 History of Landslides along the Alpine Way ..........................................................................25 The Winterhaus Landslide.........................................................................................................26 Status of the Alpine Way before 1968.....................................................................................32 Tyrola Lodge................................................................................................................................33 Relationship between NPWS and the DMR ..........................................................................39 The Bright Period .......................................................................................................................48 RTA as Technical Advisor, 1991-1996 .....................................................57 Arrival of Mr. Tony Sullivan .....................................................................................................57 Mr. Warren-Gash........................................................................................................................59 The Site Inspection.....................................................................................................................60 Subsequent Inspections and Reports.......................................................................................62 Unpredicted Slides......................................................................................................................63 Mr. Reedy’s Supervision.............................................................................................................64 Presence of the Watermain .......................................................................................................65 Approach to Instability Assessment.........................................................................................65 The RTA Slope Risk Assessment.............................................................................................67 Submissions for Mr. Warren-Gash and RTA .........................................................................68 The Development of Thredbo.................................................................71 Identification of Instability in the Eastern Subdivision ........................................................72 The Lend Lease takeover...........................................................................................................75 Construction of Carinya Lodge ................................................................................................80 Regulation of Building in the Park...........................................................................................82 The Dagger Period .....................................................................................................................84 Western Subdivision...................................................................................................................88 Conclusion ...................................................................................................................................89 The Watermain — Construction.............................................................93 1 Construction of the Watermain................................................................................................ 96 Configuration of the Schuss Bend ........................................................................................... 98 Thrust Blocks .............................................................................................................................. 99 Suitability of Watermain Site................................................................................................... 100 The Winterhaus Retaining Wall — Construction .................................111 Purpose of the Retaining Wall................................................................................................ 111 Preliminary Design and Investigations.................................................................................. 111 The Final Design ...................................................................................................................... 112 Construction of the Retaining Wall ....................................................................................... 114 Absence of a Geotechnical Study .......................................................................................... 115 Method of Construction.......................................................................................................... 116 Floor of the Trench.................................................................................................................. 116 Engineering Cause ................................................................................ 119 Slope Failure.............................................................................................................................. 121 Description of the Manner of Failure of the Slope............................................................. 121 Nature of the Landslide Site ................................................................................................... 122 Primary Landslide..................................................................................................................... 123 Two Major Fills on the Site..................................................................................................... 124 Geohydrological Description of the Carinya Site Pre-slide................................................ 124 Change Necessary to Cause the Slide.................................................................................... 125 Nature of the Landslide........................................................................................................... 125 The Watermain Theory ......................................................................... 127 Observations after the Landslide ........................................................................................... 128 Observations prior to the Landslide...................................................................................... 133 Mr. O’Reilly’s Observations.................................................................................................... 133 Water Observations in and around Carinya prior to the Landslide.................................. 136 Observations of water around Carinya.................................................................................. 137 Noises heard prior to the Landslide....................................................................................... 138 Creep .......................................................................................................................................... 138 Rate of Leak .............................................................................................................................

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