Reference Document - MCU25 0060 (As Published)

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)


 Loose or Loose to
                               17             27             0.38                 0.55                  2.66
 Medium Dense Sands



 Medium Dense Sands            18             33             0.29                 0.46                  3.39


 Dense (or denser)
                               18             36             0.26                 0.41                  3.85
 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 internal and global 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 from hard surfaces (including overflow from
rainwater tanks etc.) must be directed by pipes or lined channels to discharge into the existing
stormwater infrastructure along Marcus Dunes Court. A stormwater management report was prepared
by Westera Partners for the development (Ref. S25-137, dated 18 August 2025) which allows for
management and discharge of run-off from roof and hardstand areas around the house to be discharged
as per this recommendation. The report states that run-off from garden areas around the residence will
continue to discharge per the existing conditions, with a non-worsening condition to the south/
south-east. This would be considered the minimum recommendation from a slope stability perspective.
Subsurface disposal of stormwater must not be undertaken.




Proposed Residential Development
25 August 2025 | 25038-001-Rev0                                                                                18