Appendix B - Global Stability Assessment Report

                                                                                                                           Brisbane | Gold Coast | Maroochydore
                                                                                       Unit 1, 35 Limestone Street (PO Box 3063), Darra Q 4076 P (07) 3279 0900
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                                                                                                                                      www.morrisongeo.com.au
SOIL DESCRIPTION AND CLASSIFICATION
The description and classification of soils is carried out in accordance with              Particle size distribution
AS1726 -2017 “Geotechnical Site Investigations” and is based on the Unified
                                                                                           Well graded – a good representation of all particle sizes.
Soil Classification System. A Behavioural approach has been adopted in this
standard when identifying, naming and classifying soil.                                    Poorly graded – an excess or deficiency of one or more intermediate particle
                                                                                           sizes.
CLASSIFICATION GROUP                                                                       Gap graded – an absence of one or more intermediate particle sizes.
                            Major Divisions                         Size (mm)              Uniform – essentially of one particle size.

                              Boulders                                 >200                Particle Shape
                              Cobbles                                63 – 200              Equidimensional particles may be described as rounded, sub-rounded, sub-
  (<35% clay/silt)




                                                    coarse           19 – 63               angular, or angular.
     Grained
     Coarse




                               Gravel              medium            6.7 – 19              Two dimensional particles with third dimension small by comparison may be
                                                       fine         2.36 – 6.7             described as flaky or platy.
                                                    coarse          0.6 – 2.36             One dimensional particles with the other two dimensions small by comparison
                                Sand               medium           0.21 – 0.6             may be described as elongated.
                                                       fine        0.075 – 0.21
                                                                                           Cementation
                                Silt                              0.002 – 0.075            Soils or defects within soils may be cemented together by various substances.
  Fine Grained




                                Clay                                  <0.002               The following terms are used to describe cemented soils.
    Clay/silt)
     (>35%




                                                                                            -     Weakly cemented – the soil may be easily disaggregated by hand in air
                                                               N/A – Peat and other               or water
                                Peat
                                                                highly organic soils        -     Moderately cemented – effort is required to disaggregate the soil by
                                                                                                  hand in air and water

MINOR/SECONDARY COMPONENT                                                                  SOIL ORIGIN
Most natural soils are a mixture of basic soil types. The primary soil is
described and modified by secondary constituents as follows:                               Residual Soil        Soil developed on extremely weathered rock
                                                                                           Aeolian              Deposited by wind.
Coarse Grained Soils
                                                   %                                       Alluvium             Deposited by streams and rivers.
    %                                         Accessory                                                         Deposited on slopes (transported downslope by
                            Modifier                            Modifier                   Colluvium
  Fines                                         Coarse                                                          gravity).
                                               Fraction
                                                                                           Lacustrine           Deposited by lakes.
  ≤5                  Add ‘trace clay/silt’      ≤ 15   Add ‘trace sand/gravel’
>5, ≤12               Add ‘with clay/silt’     >15, ≤30 Add ‘with sand/gravel                                   Deposited in ocean basins, beaches and estuarine
                                                                                           Marine
                     Prefix soil name with               Prefix soil name with                                  (tidal river)
  >12                                            >30
                          silty /clayey                    Sandy/gravelly                                       Mantle of surface and/or near surface soil often but
                                                                                           Topsoil              not always defined by high levels of organic material,
Fine Grained Soils                                                                                              both dead and living.
      %                                                                                                         Any material that has been placed by anthropogenic
                                                    Modifier                               Fill
 Sand/gravel                                                                                                    (human derived) processes
    ≤ 15                                            Use ‘trace’
  >15, ≤30                                    Add ‘with sand/gravel
                                               Prefix soil name with
                                                                                           TYPICAL REPRESENTATION AND TERMS
          >30                                                                                                 Clean                   Well graded gravels and
                                                 Sandy/gravelly                                                              GW
                                                                                                             Gravels                  gravel/sand mixtures
                                                                                                            (Little or no             Poorly graded gravels and
COHESIVE SOIL DESCRIPTION                                                                                      Fines)        GP
                                                                                             GRAVEL                                   gravel/sand mixtures
Plasticity                                                                                                                            Silty Gravels, gravel/sand/silt
                                                                                                                             GM
                                    Range of Liquid             Range of Liquid                            Gravel with                mixtures
 Descriptive term
                                     Limit for SILT             Limit for CLAY                               Fines                    Clayey Gravels,
                                                                                                                             GC
  Low Plasticity                           ≤50%                      ≤35%                                                             gravel/sand/clay mixtures
 Medium Plasticity                     Not applicable            >35 and <50%                                 Clean                   Well graded sands, gravelly
                                                                                                                             SW
  High Plasticity                          >50%                      <50%                                     Sands                   sands
                                                                                                            (Little or no             Poorly graded sands,
                                                                                                               Fines)        SP
Consistency                                                                                                                           gravelly/sand mixtures
                                                                                              SANDS
                                        Indicative undrained Shear Strength (cu)                                             SM       Silty sands
                     Term                                                                                  Sands with
                                                          kPa                                                Fines
       Very Soft (VS)                                        ≤12                                                             SC       Clayey Sands
          Soft (S)                                       >12 and ≤25                                                                  High plasticity inorganic silts,
                                                                                                                             MH
          Firm (F)                                       >25 and ≤50                                                                  silt mixtures
          Stiff (St)                                    >50 and ≤100                                       Liquid Limit               High plasticity inorganic clays,
                                                                                                                             CH
       Very Stiff (VSt)                                 >100 and ≤200                                         >50%                    clay mixtures
          Hard (H)                                          >200                                                                      High plasticity organic clays
                                                                                                                             OH
                                                                                                                                      and silts
                                                                                              SILTS
NON-COHESIVE SOIL DESCRIPTION                                                                                                         Intermediate/medium plasticity
                                                                                               and                            CI
                                                                                                           Liquid Limit               inorganic clay
                                                                                              CLAYS
Relative Density                                                                                           >35% <50%                  Intermediate plasticity organic
                                                                                                                             OI
                         Term                           Density Index %                                                               silt/clay
                                                                                                                                      Low plasticity inorganic clays,
            Very loose (VL)                                   ≤15                                                            CL
                                                                                                           Liquid Limit               clay mixtures
               Loose (L)                                 >15 and <35%
                                                                                                              ≤35%
          Medium Dense (MD)                              >35 and <65%                                                        OL       Low plasticity organic clay/silts
              Dense (D)                                  >65 and <85%
           Very Dense (VD)                                    >85                            HIGHLY                                   Peat, Humus, Swamp Soils
                                                                                                                              Pt
                                                                                            ORGANIC                                   with high organics