187440-GEO-Site Classification Report[A] (1)

5.0      Site Classification________________________________________________________
In accordance with AS2870-2011 “Residential Slabs and Footings Construction” a site classification of Class “P” is
applicable to this site due to abnormal moisture conditions – trees and recently removed trees on site and trees on
adjacent sites.
This site is subject to abnormal moisture conditions which must be alleviated or allowed for in the design of the footing
system.
In the absence of these abnormal moisture conditions, the designing engineer should recognise that the natural soils
encountered on this site result in a “Class M” site classification applying to this site.

On the basis of the findings in this investigation, including visual-tactile identification of the soil profile combined with
this writer’s local knowledge and experience, the characteristic surface movement (Ys) on this site – under normal
conditions – has been estimated to be in the range of 20mm to 40mm.

         5.1      Ys – Characteristic surface movement________________________________________________
Based on the sub-surface soil profile and results from the laboratory testing, a soil classification Class M has been given
to the site, with an expected characteristic soil surface movement of (Ys) range between 20mm to 40mm. Please refer to
below table for details of site-specific variables used to calculate resultant Ys value.

                                                   Depth of Soil Suction          Depth of Soil         Ys – Characteristic
      Climate Zone          Soil Classification
                                                     Change (Hs m)                Cracking (m)          Surface Movement

         Zone 1                     M                        1.8m                      0.75m                     30


         5.2      Yt – Tree Effect_________________________________________________________________________
The Yst value has been calculated based on what was visually inspected on site at the time of fieldwork, taking into
consideration the proposed house siting (see Appendix A) and soil conditions as provided within this soil report. Existing
and recently removed property trees and/or trees planted within the nature strip of new and existing properties have the
potential to negatively influence the soil moisture conditions across areas of the house footprint within their zone of
influence. The zone of influence of trees is highly dependent on soil reactivity, tree type, potential growth, and tree
height at maturity along with its distance from the house siting. As a general rule-of thumb, a trees zone of influence can
be estimated using the QBCC guidelines.
To alleviate potential foundation issues relating to these variables, foundation designs should be site specific with future
tree growth in mind and include provisions for suitable site drainage. Where applicable, additional consideration should
be given to the effects of change in soil moisture conditions attributed to trees that have been recently removed.

         5.3      Classification Note_____________________________________________________________________
This investigation is based on a limited geotechnical assessment. Should the subsurface conditions encountered during
construction vary from those described above, Intrax must be advised of these variations to provide comment or inspect
the site where necessary. Based on experience with similar soils and with reference to Table D1 of AS2870-2011, the use
of standard footings as presented in AS2870-2011 is only applicable to building with a loading and a construction style
similar that of a residential dwelling as described in section 3.1 of AS2870-2011.

In assessing the classification for this site, and unless specifically noted, this report has not considered any future tree(s)
to be planted as part of either site or roadside landscaping. If additional information is known by the owner, future
owner, any stakeholder, or any consultant, this information must be provided to the design engineer to ensure that the
footing system is adequate for the conditions which are expected.




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