Appendix B - Global Stability Assessment Report

                                                  -9-
                                                                                     Job No: ME21/032


      Table 4 – Characteristic Strength Parameters for the Expected Subsurface Materials

                                                                 Effective Strength Parameters1)
      Batter Location          Batter Subsurface Profile        Density,
                                                                            Cohesion,      Friction
                                                                   ɣ
                                                                             c’ (kPa)     Angle, ϕ’ (°)
                                                                (kN/m3)
      5.5m high cut,             Natural Stiff Clay of High
  approximately 380 slope           Plasticity (Extremely          19            5             30
          angle                    Weathered Granite) 2)
                                Stiff Clay of High Plasticity
    4.5m high fill batter,
                                Sourced from Cuts in the
  approximately 350 slope                                          19            1             25
                                  Extremely Weathered
          angle
                                           Granite
 Notes:
    1) The natural subsurface materials must be tested to confirm the parameters presented in this
        Table are present onsite.
    2) The natural stiff clay contains layers of sand based soils.
    3) If other subsurface materials are encountered to those described in this report, this office
        should be contacted and further advice sought.


8.0     GLOBAL STABILITY ASSESSMENT RESULTS

The global slope stability analyses were performed using the characteristic strength parameters in Table
4 and the ground slope information in the section provided by the Client. The section and corresponding
plan provided by the Client are presented in Appendix E. Assessments have been carried out for a
groundwater level approximately 3m below the ground surface of the shed pad adjacent to the cut
batter. A ground surface surcharge of 10kPa has been applied over the ground surface of the shed pad
to simulate the loading of the shed. The global slope stability modelling was carried out using
commercial software SLOPE/W incorporating the Morgenstern Price analysis method.

A Factor of Safety (FOS) of 1.5 has been targeted as the minimum requirement when assessing long
term stability of batters in accordance with generally accepted minimum industry standards.

The global stability analysis models of the cut and fill batters are presented in Appendix F, with the
results summarised in Table 5.




Ref: 27222-rev 1                                                           MORRISON GEOTECHNIC
Mr Geoff Hussin