Geotch Report December 2021 95141.00.R.001.RevA

                                                                                                 Page 6 of 11




6.3       Site Classification

Site classification of foundation soil reactivity strictly only applies to residential buildings up to two-
storeys and to other buildings of similar size, loading and flexibility as defined in accordance with
AS 2870.

Given the presence of very loose to loose sand with a bearing capacity of less than 100 kPa the site
would be classified as ‘Class P’ (problem site).

The results of the laboratory testing indicate the sand is non-reactive to changes in soil moisture content.
Subsequent surface movement analysis indicates that the characteristic reactive surface movements
(ys) value for the site in its current state is estimated to be less than 20 mm, consistent with ‘Class A’
conditions. Higher ground surface movements could be experienced where imported clayey material is
used as structural fill.

If ‘abnormal’ soil moisture conditions are experienced at the site, which could result in adverse
foundation performance, more extensive foundation works would be required. ‘Abnormal’ soil moisture
conditions are defined in AS 2870 (Clause 1.3.3) and in summary comprise:
•       Unusual moisture caused by drains, channels, ponds, dams or tanks;
•       Recent removal of large trees;
•       Growth of trees too close to a structure;
•       Excessive or irregular watering of gardens adjacent to the structure;
•       Lack of maintenance of site drainage;
•       Failure to repair plumbing leaks.

It should be noted that no assessment of the effect of soil moisture change by trees has been made in
estimating the above ys values (either with respect to the removal of established trees prior to
development of building pads, or the proximity of established or new trees to proposed buildings).
Reference to the requirements in AS 2870 should be made by the building designer in this regard. It
should be further noted that the presence or removal of trees can result in additional surface movement,
due to tree-induced suction changes and tree-induced centre heave. Such tree-induced movement is
not included in the ys calculations used to classify the site.



6.4       Foundations

The subsurface conditions encountered in the bores comprised very loose to loose sand underlain by
medium dense sand at depth (typically within the upper 1 m).

The upper very loose to loose sand is unlikely to be adequate to support high level strip and pad footings
for the proposed development. In addition, loose sand is susceptible to significant settlements.
Densification of the loose sand could allow for high level strip and pad footings to be considered.
Alternatively, a piled foundation will be required to support heavy loads.

High level footings founding in the upper very loose to loose sand would be limited to a maximum
allowable bearing capacity of 50 kPa.


    Geotechnical Investigation, Proposed Youngcare Facility                               95141.00.R.001.RevA
    32 Viewland Drive, Noosa Heads                                                             December 2021