SUPERSEDED - Reference Documents - MCU25 0079

                    Best Practice Erosion And Sediment Control                                       Erosion Hazard Assessment Form



                                           Table 3 – Typical properties of various soil groups [1]
                       Soil Groups                                           Typical properties [2]
                          GW, GP               •    Low erodibility potential.
                          GM, GC               •    Low to medium erodibility potential.
                                               •    May create turbid runoff if disturbed as a result of the release of silt
                                                    and clay particles.
                          SW, SP               •    Low to medium erodibility potential.
                          SM, SC               •    Medium erodibility potential.
                                               •    May create turbid runoff if disturbed as a result of the release of silt
                                                    and clay particles.
                          MH, CH               •    Highly variable (low to high) erodibility potential.
                                               •    Will generally create turbid runoff if disturbed.
                           ML, CL              •    High erodibility potential.
                                               •    Tendency to be dispersive.
                                               •    May create some turbidity in runoff if disturbed.
                    Note: [1]       After Soil Services & NSW DLWC (1998).
                          [2]       Any soil can represent a high erosion risk if the binding clays or silts are unstable.

                    Table 4 provides general guidelines on the suitability of various soil groups to various
                    engineering applications.

                           Table 4 – Engineering suitability based on Unified Soil Classification [1]
                                                                Embankments
                                                    USC                                       Fill         Slope        Untreated
                    Unified Soil Class                        Water           Non
                                                   Group                                                  stability      roads
                                                            retaining        water
                                                                           retaining
                    Well graded gravels             GW      Unsuitable      Excellent      Excellent      Excellent          Average
                    Poorly graded gravel            GP      Unsuitable      Average        Excellent       Average       Unsuitable
                    Silty gravels                   GM      Unsuitable      Average          Good          Average           Average
                    Clayey gravels                  GC       Suitable       Average          Good          Average       Excellent
                    Well graded sands               SW      Unsuitable      Excellent      Excellent      Excellent          Average
                    Poorly graded sands             SP      Unsuitable      Average          Good          Average       Unsuitable
                    Silty sands                     SM      Suitable [2]    Average        Average         Average            Poor
                    Clayey sands                    SC       Suitable       Average        Average         Average            Good
                    Inorganic silts                 ML      Unsuitable        Poor         Average          Poor         Unsuitable
                    Inorganic clays                 CL      Suitable [2]      Good         Average          Good              Poor
                    Organic silts                   OL      Unsuitable     Unsuitable        Poor         Unsuitable     Unsuitable
                    Inorganic silts                 MH      Unsuitable        Poor           Poor           Poor         Unsuitable
                    Inorganic clays                 CH      Suitable [2]    Average       Unsuitable       Average       Unsuitable
                    Organic clays                   OH      Unsuitable     Unsuitable     Unsuitable      Unsuitable     Unsuitable
                    Highly organic soils            Pt      Unsuitable     Unsuitable     Unsuitable      Unsuitable     Unsuitable
                    Notes:    [1]      Modified from Hazelton & Murphy (1992)
                              [2]      Suitable only after modifications to soil such as compaction and/or erosion protection




                    IECA (Australasia)                                     November 2008                                         Page 4

Document Set ID: 23959990
Version: 1, Version Date: 23/07/2025