SUPERSEDED Compiled Reference Document - MCU24 0153 & OPW24 0202 (As Published)

        Detailed design will also need to account for relevant factors of safety to maintain the temporary and
        long-term stability of the retention system and control deflections so as not to put neighbouring
        structures or underground services at risk or distress.
        Retaining structures greater than 1 m high, or those required to support surcharge loads or sloping
        backfill, will require engineer design and certification of construction. Retaining wall design should be
        carried out in accordance with AS4678-2002 Earth retaining structures.
        Design for temporary and permanent retaining structures could be carried out using a trapezoidal (for
        propped or anchored walls) pressure distribution applicable to the wall type and based on the
        parameters listed in Table 4. These values do not include allowance for hydrostatic pressures nor
        transient (e.g. construction) or adjacent footing loadings.

        Table 4: Retaining Structure Design Parameters

                                         Unit                          Lateral earth pressure coefficients
                                                        Friction
          Retained material              weight                        Ka                   Ko                    Kp
                                                        angle (°)
                                         (kN/m3)                       (Cantilever wall)    (Non-yielding wall)
                                         18             28             0.36                 0.53                  2.77
          Very Loose/ Loose
          Sands


                                         19             34             0.28                 0.44                  3.54
          Medium Dense (or
          Denser) Sands


                                         *              *              *                    *                     *
          Future Controlled Fill*


        Note:     * Depends on fill material type and level of compaction.

        Retaining structures must be founded as per the recommendations in Section 6.3.2 above with the piled
        footings, if required, also designed to resist lateral loads imposed by the retaining wall. Detailed design
        must include an assessment of stability.


        6.5             Drainage
        Surface diversion drainage should be constructed above the crest of any new cut or fill embankment or
        retaining walls (e.g. grassed or landscaped swales or diversion mounds). Adequate site drainage must be
        installed to ensure that stormwater runoff is directed away from building walls, footings, batters and
        retaining walls.
        Although unlikely, if groundwater seepage is encountered during excavations, Tectonic must be notified
        to assess the impact on stability.
        All excess stormwater collected around the residence (including overflow from rainwater tanks etc.) must
        be directed by pipes or lined channels to discharge into the existing stormwater infrastructure along
        Bottlebrush Avenue or Noosa Drive. Subsurface disposal of stormwater must not be undertaken.



        Proposed Unit Development
        30 September 2024 | 24265-001-Rev0                                                                               16
Document Set ID: 23376055
Version: 1, Version Date: 28/11/2024