Changes Application - MCU15/0023.02

Project No. 112-14608
January, 2013   REF: 1-14608,2013-01-15, BR VER O.                                            Page 19

      The existing slopes on the site are well vegetated with grasses and trees and are
      considered to be at equilibrium, although observed to be somewhat uneven and irregular,
      likely to be a result from some long term soil creep. Based on the observed and measure
      slope angle and expected medium dense to dense sand profile downslope, a factor of
      safety in the order of 1.0 - 1.3 is likely, which is low (at limiting equilibrium) to marginally
      acceptable.


      The cunstruction of any structures at tho crest of the slope will apply an additional load
      that could be potentially destabilising and Is also likely to be subject to the effects of long
      term soil creep. However, the aim of the proposed deep foundations discussed above, is
      to carry the load down a depth below a 25 degree line from the toe of the slope into
      medium dense sands, and not apply it to the loose surface sand.           Survey of the slope
      extending below the site boundaries may be required to confirm the position of this
      influence line, and Figure 2 (Section 4.4) illustrates how such a 25 degree influence line
      should be drawn.


      Any development of this site will have to be carried out with care to ensure this stability
      status is maintained.   This will apply to both the temporary works during construction, as
      well as the permanent building works, and the long term site maintenance.


      It is recommended       that heavy constnuction materials such as concrete blocks or
      construction machinery should not be required to traverse or be placed on the slope, as
      these may apply an unacceptably large surcharge load onto the slope.


      Only non-vibrating construction techniques and activities should be selected, to ensure
      that slumping of the sloping loose sand is prevented from occurring.


      In addition to the recommendations on the design of foundations, we recommend that the
      proposed construction works should follow good hillside constnuction practice, to ensure
      the long-term stability of the developed site. Attached to this report are some guideline
      notes of such practice for your reference (Australian Geomechanics Society - Landslide
      Risk Management Subcommittee, Appendix J, AG Vol.35 NO.1 March 2000).




                                                           *   SOIL SURVEYS ENGINEERING