Att 3 - Landslide Risk Assessment

    Qualtest Geotechnics Slope Stability Assessment Tool – Hargreaves & Kidd (2012)

                        Slope Hazard Rating at 399 Sunrise Road, Tinbeerwah QLD

Grade      (1) Natural Surface                 Level      Factor   Grade   (8) Cut Depth               Level   Factor
           Conditions                                                      No cut existing nor         L       0.9
           <5                                  L          0.1              proposed
           50 to 150                           M          0.5              <1m                         M       1.1
✓          150 to 300                          M          0.8      ✓       1 to 3m                     M       1.5
           300 to 450                          H          0.8              3 to 6m                     H       1.7
           > 450                               M          0.8              >6m                         VH      2.5


           (2) Slope Shape/Appearance          Level      Factor   Grade   (9) Cut batter angle        Level   Factor
           Crest or ridge                      L          0.7      ✓       <30o                        L       0.5
✓          Planar/convex                       M          0.9              30o to 45o                  M       1.0
           Rough/irregular                     H          1.2              45o to 60o                  M       1.5
           Concave                             H          1.5              >60o                        VH      3.0


Grade    (3) Site Geology                      Level      Factor   Grade   (10) Cut Batter Support     Level   Factor
         Problematical geological              VH         1.5
                                                                           Engineered concrete /       L       0.5
         boundary
                                                                           masonry wall
         Volcanic extrusive (basalts etc)      H          1.2
                                                                           Engineered crib wall        M       0.9
         Volcanic intrusive (granites etc)     M          1.0
✓        Sedimentary rocks                     M          1.0              V gabion wall               M       1.0
         Low-grade metamorphic rocks           M          1.0              Engineered dry rock stack   H       1.2
         High-grade metamorphic rocks          L          0.9              wall
         Hill wash (recent colluvial)          VH         2.0      ✓       Engineered post and wale    H       1.5
                                                                           wall
                                                                           Other (including non-       VH      2.0
Grade    (4) Soil Profile                      Level      Factor           engineered)
         Bedrock as surface                    VL         0.1
         Residual Soil – bedrock < 1m          L          0.5
         Residual Soil – bedrock 1 to 3m       M          0.9      Grade   (11) Fill                   Level   Factor
✓        Residual Soil – bedrock > 3m          H          1.5              No fill – existing nor      L       0.9
         Transported Soil - < 1m deep          H          1.5              proposed
         Transported Soil - 1 to 3m deep       VH         2.0              <1m                         M       1.1
         Transported Soil – 3 to 6m deep       VH         4.0      ✓       1 to 3m                     M       1.5
         Transported Soil - > 6m deep          VH         2.0
                                                                           3 to 6m                     H       1.7
                                                                           >6m                         VH      2.5
Grade    (5) Regional Position on              Level      Factor
         Hillside (refer AS4055-2066)
         Ridgeline                             VL         0.7      Grade   (12) Fill Batter Angle      Level   Factor
         Crest                                 L          0.8
         Upper 1/3 of slope                    M          0.9      ✓       <30                         L       0.5
✓        Mid 1/3 of slope                      H          1.2              30o to 45o                  H       1.2
         Lower 1/3 of slope                    H          1.5              45o to 60o                  VH      2.0
                                                                           >60o                        VH      4.0

Grade    (6) Evidence of Groundwater           Level      Factor
✓        No evidence                           L          0.7
                                                                   Grade   (13) Fill Batter Support    Level   Factor
         Minor moistness                       M          0.9
                                                                           Engineered concrete /       L       0.8
         Generally wet                         H          1.5
                                                                           masonry wall
         Evidence of spring                    VH         3.0
                                                                           Engineered crib wall        M       1.0
         Do not know                           VH         4.0
                                                                           V gabion wall               H       1.2
                                                                           Engineered dry rock stack   VH      1.5
Grade    (7) Evidence of Slope                 Level      Factor           wall
         Instability                                               ✓       Engineered post and wale    V       1.8
         No sign of instability                L          0.8              wall
✓        Indicators of soil creep              H          1.2              Other (including non-       VH      4.0
                                                                           engineered)
         Minor irregularity                    VH         2.0
         Major irregularity                    VH         5.0
         Active instability                    VH         10.0
         Don’t know                            VH         15.0
Pre Construction Output = 0.8x0.9x1.0x1.5x1.2x0.7x1.2 =   1.09