S25-107-Stormwater Report

Best Practice Erosion And Sediment Control                                  Erosion Hazard Assessment Form


                               Erosion Hazard Assessment Form
                               Condition                                       Points   Score     Trigger
                                                                                                   value
AVERAGE SLOPE OF DISTURBANCE AREA [1]
•   not more than 3%                                [3%  33H:1V]                 0
•   more than 3% but not more than 5%               [5% = 20H:1V]                 1
                                                                                           2         4
•   more than 5% but not more than 10%              [10% = 10H:1V]                2
•   more than 10% but not more than 15%             [15%  6.7H:1V]               4
•   more than 15%                                                                 6
SOIL CLASSIFICATION GROUP (AS1726) [2]
•   GW, GP, GM, GC                                                                0
•   SW, SP, OL, OH                                                                1        3
•   SM, SC, MH, CH                                                                2
•   ML, CL, or if imported fill is used, or if soils are untested                 3
EMERSON (DISPERSION) CLASS NUMBER [3]
•   Class 4, 6, 7, or 8                                                           0
•   Class 5                                                                       2        3         6
•   Class 3, (default value if soils are untested)                                4
•   Class 1 or 2                                                                  6
DURATION OF SOIL DISTURBANCE [4]
•   not more than 1 month                                                         0
•   more than 1 month but not more than 4 months                                  2        2         6
•   more than 4 months but not more than 6 months                                 4
•   more than 6 months                                                            6
AREA OF DISTURBANCE [5]
•   not more than 1000 m2                                                         0
•   more than 1000 m2 but not more than 5000 m2                                   1        0         4
•   more than 5000 m2 but not more than 1 ha                                      2
•   more than 1 ha but not more than 4 ha                                         4
•   more than 4 ha                                                                6
WATERWAY DISTURBANCE [6]
•   No disturbance to a watercourse, open drain or channel                        0
                                                                                           0         2
•   Involves disturbance to a constructed open drain or channel                   1
•   Involves disturbance to a natural watercourse                                 2
REHABILITATION METHOD [7]
Percentage of area (relative to total disturbance) revegetated by seeding
without light mulching (i.e. worst-case revegetation method).
•   not more than 1%                                                              0        1
•   more than 1% but not more than 5%                                             1
•   more than 5% but not more than 10%                                            2
•   more than 10%                                                                 4
RECEIVING WATERS [8]
•   Saline waters only                                                            0        0
•   Freshwater body (e.g. creek or freshwater lake or river)                      2
SUBSOIL EXPOSURE [9]
•   No subsoil exposure except of service trenches                                0        2
•   Subsoils are likely to be exposed                                             2
EXTERNAL CATCHMENTS [10]
•   No external catchment                                                         0
                                                                                  1
                                                                                           2
•   External catchment diverted around the soil disturbance
•   External catchment not diverted around the soil disturbance                   2
ROAD CONSTRUCTION [11]
•   No road construction                                                          0        0
•   Involves road construction works                                              2
pH OF SOILS TO BE REVEGETATED [12]
•   more than pH 5.5 but less than pH 8                                           0        1
•   other pH values, or if soils are untested                                     1

                                                                    Total Score [13]      16


IECA (Australasia)                               November 2008                                     Page 1