Compiled Reference Documents - OPW25/0053 (As Published)

                                                                                                   Terminology
Soil Descriptions                                                                                     Symbols
                                                                                                  Abbreviations

Classification
The soil classification comprises a two character group symbol. The first character identifies the primary
component. The second character identifies either the grading or presence of fines in a coarse grained soil,
or the plasticity in a fine grained soil. Refer AS1726-2017 6.1.6 for further clarification.

Soil Name
For most soils, the name is derived with the primary Component                Prominence in Soil Name
component included as the noun (in upper case),               1

preceded by any secondary components stated in Primary                  Noun (eg “CLAY”)
an adjective form. In this way, the soil name also Secondary            Adjective modifier (eg “Sandy”)
describes the general composition and indicates Minor                   No influence
the dominant behaviour of the material.             1
                                                      – for determination of component proportions, refer
                                                         component proportions on previous page

For materials which cannot be disaggregated, or which are not comprised of rock or mineral fragments,
the names “ORGANIC MATTER” or “ARTIFICIAL MATERIAL” may be used, in accordance with AS1726-2017
Table 14.
Commercial or colloquial names are not used for the soil name where a component derived name is
possible (for example “Gravelly SAND” rather than “CRACKER DUST”).
Materials of “fill” or “topsoil” origin are generally assigned a name derived from the primary/secondary
component (where appropriate). In log descriptions this is preceded by uppercase “FILL” or “TOPSOIL”.
Origin uncertainty is indicated in the description by the characters `(?)`, with the degree of uncertainty
described (using the terms “probably” or “possibly” in the origin column, or at the end of the description).

Identification of minor components
Minor components are identified in the soil description immediately following the soil name. The minor
component fraction is usually preceded with a term indicating the relative proportion of the component.

   Minor Component                                         Relative Proportion
   Proportion Term                In Fine Grained Soil                    In Coarse Grained Soil
 With                       All fractions: 15-30%                  Clay/silt: 5-12%
                                                                   sand/gravel: 15-30%
 Trace                      All fractions: 0-15%                   Clay/silt: 0-5%
                                                                   sand/gravel: 0-15%
The terms “with” and “trace” generally apply only to gravel or fine particle fractions.                   Where
cobbles/boulders are encountered in minor proportions (generally less than about 12%) the term
“occasional” may be used. This term describes the sporadic distribution of the material within the confines
of the investigation excavation only, and there may be considerable variation in proportion over a wider
area which is difficult to factually characterise due to the relative size of the particles and the investigation
methods.

Soil Composition
Plasticity                                               Grain Size
 Descriptive      Laboratory liquid limit range                   Type                 Particle size (mm)
     Term              Silt            Clay               Gravel Coarse           19 - 63
 Non-plastic     Not applicable  Not applicable                     Medium        6.7 - 19
 materials                                                          Fine          2.36 – 6.7
 Low             ≤50                ≤35                   Sand      Coarse        0.6 - 2.36
 plasticity                                                         Medium        0.21 - 0.6
 Medium          Not applicable     >35 and ≤50                     Fine          0.075 - 0.21
 plasticity
 High            >50                >50             Grading
 plasticity                                          Grading Term                   Particle size (mm)
Note, Plasticity descriptions generally describe the Well                    A good representation of all
plasticity behaviour of the whole of the fine grained                        particle sizes
soil, not individual fine grained fractions.              Poorly             An excess or deficiency of
                                                                             particular sizes within the
                                                                             specified range
                                                          Uniformly          Essentially of one size
                                                          Gap                A deficiency of a particular
                                                                             size or size range within the
                                                                             total range
Note, AS1726-2017 provides terminology for additional attributes not listed here.



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