Geotechnical Report

                              PROPOSED UNIT DEVELOPMENT
                              31 BOTTLEBRUSH AVENUE, NOOSA HEADS

Piles so founded may be designed using an allowable end bearing capacity of 300 kPa. High level footings,
where achievable in deeper cut areas, may be designed using an allowable bearing capacity of 100 kPa
provided that they are founded in the natural medium dense (or denser) sands.
Given the sandy soil profile and depths of footings required, steel screw piles are considered to be a suitable
foundation type for the proposed unit development generally. However, in areas of cut exposing medium
dense (or denser) sands at the subgrade level conventional high-level footings may be adopted. It should be
noted that excavation for concrete strip footings (or similar) may loosen the base. Therefore, the use of a
vibrating plate would be required to densify any high level footing bases prior to the placement of reinforcing
steel.

Due to the presence of loose sands, together with the close proximity of adjacent residences, open bored
piers or driven piles are not considered to be suitable for this site. The advice of a specialist piling contractor
must be sought regarding feasibility, design and installation of the piling system for this site, including an
assessment of potential vibration effects on nearby structures, and monitoring requirements.

Footing design should also account for potential soil reactivity to be equivalent to Class S. It should be noted
that placement of reactive clay may result in a more severe equivalent site classification, such as M or greater.

All footings should found such that they are not adversely affected by any adjacent excavations, batter
slopes, trenches, retaining walls, or in ground structures (e.g. swimming pool) that are not designed to
support building loads. Footings should found at least below a plane extending 1 m horizontally from the
base of trenches/excavations/retaining walls/swimming pool, then rising up at 1V:1H, as illustrated in Text
Figure 10.




                        Text Figure 10: Footing depth required to prevent undermining



It will be important to ensure close supervision of screw pile installation, as piling will not encounter drilling
refusal at the recommended founding depth, and piles could extend to much greater depth than necessary.

If any soil conditions encountered during construction are found to differ from those noted in the geotechnical
investigation, Tectonic should be notified immediately, and an inspection carried out to determine if changes
to footing design are required.




17 December 2020
Report No. 20370-001-Rev0                                12