Planning Response letter to Council Information Request · MCU18/0015

   Item 7 – Provide the following:
   i. Slope stability analyses should be provided to show that the proposed filling and retention system
   has an adequate factor of safety against both local and global instability.
   ii. Site specific recommendations are required on site preparation prior to filling given the presence
   of very loose to loose sand.
   iii. Site specific recommendations are required on footing designs for the proposed retaining walls
   given the presence of loose to very loose sand.
   iv. The geotechnical design parameters to be adopted in the design should be confirmed. There is
   an inconsistency between the parameters quoted in Table 1 and Table 5 of the Golder Associates
   Report. The parameters quoted in Table 5 need to be modified for the actual site conditions to
   avoid errors in design. For example, there will be a significant reduction in passive resistance at the
   toe of the wall due to the steep slopes and the Kp values presented in Table 5 are not appropriate.
   Clear advice also needs to be given in relation to accommodating other relevant site factors into
   the design.


   Response – The Geotechnical Assessment included at Attachment 5 provides the requested slope
   stability assessment at Section 7, site preparation recommendations at sections 6.1.1 and 6.1.3
   and footing and other design recommendations at section 6.3.


   Item 8 – Provide full details as to how the sewer is to be constructed on such steep slopes.
   The details should include:
   a. Cross sections showing the extent of cut and fill required to provide access for machinery.
   b. An assessment of the impact of the construction on the stability of the dune including constraints
   that may apply such as limitations on the stockpiling of spoil, temporary betters slopes,
   management of backfilling and compaction to prevent vibrations etc.
   c. A plan showing the extent of clearing of vegetation that is required and the likely zone of
   disturbance.


   Response – Included at Appendix I to the Engineering Report at Attachment 4 is some preliminary
   technical advice from Bamser Engineering who are experts in underground engineering. They have
   provided advice that the sewer is likely to be able to be constructed by using horizontal directional
   drilling which will minimise the extent of vegetation clearing required. The sketch diagram
   provided at Appendix I shows the areas required to accommodate construction machinery which
   aligns with the proposed development footprint. The applicant would be accepting of a condition

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