Geotechnical Investigation

                             PROPOSED CALILE HOTEL NOOSA DEVELOPMENT
                             3 – 7 SERENITY CLOSE, NOOSA HEADS

Footing design should also account for potential soil reactivity to be equivalent to Class M. It should be noted
that placement of reactive clay may result in a more severe equivalent site classification, such as H1 or
greater.
All footings should found such that they are not adversely affected by any adjacent excavations, trenches,
retaining walls, or in ground structures 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 15 overleaf.




                        Text Figure 15: Footing depth required to prevent undermining

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.

6.4      Temporary and Permanent Retention
Excavations are expected to range up to around 5.5 m BGL (existing ground levels) and, given that the
planned excavations extends close to some of the site boundaries and underground infrastructure (e.g.
sewer), some form of temporary shoring will likely be required to support the excavation.

Based upon our experience with similar sites, we anticipate that temporary shoring may be achieved by use
of sheet piles, however Unitywater requirements for the sewer/stormwater infrastructure may restrict the use
of sheet piles. Shoring of deeper cuts would likely require lateral restraint, and this is conventionally
achieved by helical steel anchors (similar to screw piles). However, the proximity to neighbouring properties
may require permissions to be obtained for subterranean access. Therefore, where lateral support by
cantilever only is not feasible, it is suggested that internal struts/propping be considered to provide lateral
restraint for the shoring system.

Anchored or propped sheet piles may require pre-drilling to prevent adverse vibrations during sheet pile
installation.
Other shoring methods that could be considered include bored contiguous or secant piles. Non-contiguous
or soldier pile walls are not feasible for the proposed development due to the likelihood that loose sands
would ‘flow’ through gaps between the piles.

An advantage of contiguous or secant pile wall retention systems is that they are ultimately used for the
permanent walls, whereas sheet piles would be temporary to provide retention during construction only,
therefore requiring a permanent structural wall to be constructed. Bored pile walls generally require greater
width (horizontally) for installation as compared to sheet piles and are often more expensive.




7 October 2022
Report No. 22239-001-Rev0                              17