Compiled Reference Documents - MCU25/0091 (As Published)

            Wingara Hills Pty Ltd

            Permanent batters should not be steeper than 1V:2H in the natural stiff (or stiffer) clays. Batters in extremely
            weathered mudstone may be constructed at 1V:1H (subject to inspection by Core).
            Further positive support by engineer-designed retaining structures may also be required where space
            restrictions prevent trimming of batters to safe slopes and where slopes are surcharged or near movement
            sensitive structures (ref Section 7.2).
            Permanent batters that are not retained should be protected from erosion (e.g. revegetation or stone
            pitching).

            7.1.4 Erosion Protection
            Any excavations or disturbance of materials should be carefully monitored and managed during the
            construction phase to minimise potential for scour/erosion and sediment run off.
            Exposed soil (i.e. on batters or drains) should be protected from erosion by appropriate measures such as
            re-vegetation and hydro-seeding, protective matting, geotextiles or hard facings. Temporary sediment control
            should be adopted during construction where surface water will flow offsite. Concentrating surface runoff
            should be avoided unless adequate erosion protection and flow dissipation is constructed.

            7.2 Retaining Structures
            Design for retaining structures could be carried out using a triangular pressure distribution applicable to the
            wall type and based on the parameters listed in Table 4. The values in Table 4 assume that the walls are
            fully drained and no allowance is included below for construction loading, up-slope footing loadings, and
            backfill compaction stresses. Retaining walls should be founded as described in Section 7.3.
            Positive permanent drainage (surface and subsoil) must be installed behind retaining walls to prevent the
            development of hydrostatic pressures. Drainage outlets must extend beyond the ends of the walls.

            Retaining wall backfill should be a loose, free draining granular material and should only be lightly
            compacted as heavy compaction may raise the earth pressure to above the ‘at rest’ earth pressure.

            Table 3: Retaining structure design parameters.

                                                                                                         Lateral earth pressure coefficient
                                                          Unit          Friction                                                    Non-
                                                                                      Cohesion,                 Yielding
                       Retained material                 weight          angle                                                    yielding
                                                                                       cu (kPa)
                                                         (t/m3)        (degrees)
                                                                                                            Ka
                                                                                                                           Kp        Ko
                                                                                                        (cantilever)
              Stiff clay - Residual Soil                   1.8                25         50-100               0.41         2.5      0.58

              Very Stiff to Hard Clay - Residual
                                                           1.9                30        100-200               0.33         3.00     0.50
              Soil
              Extremely Weathered
                                                           1.9                34         >1000                0.38         3.54     0.44
              Material/Mudstone
              Notes:

              Ka - active; Ko - at rest; Kp - passive

              For yielding walls active state develops when: Deflection > 0.001H to 0.004H (granular soil),
              or deflection > 0.01H to 0.04H (cohesive soil)




            7.3 Footings
            The proposed structures could be supported on a combination of high-level strip/pad and/or piered footings
            founded at least 300 mm into stiff (or stiffer) residual soils or extremely weathered material/mudstone below
            depths of 1.2 m BGL. Design bearing pressures are provided in Section 7.3.2.




            J002915-001-R-Rev0                                            9


Document Set ID: 24031832
Version: 1, Version Date: 14/08/2025