Reference Document - MCU25 0060 (As Published)

sacrificial liners (e.g. formatube, etc.) would be required. Cast in place continuous flight auger (CFA) piles
may also be suitable for foundation piles (and shoring piles) provided a small rig capable of traversing
the site can be sourced. It is generally expected however, that helical steel screw piles would be the most
suitable solution for the parts of the building requiring deeper footings from a cost and constructability
perspective.
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.
If steel screw piles are adopted, it will be important to ensure close supervision of installation, as piling
may not encounter sufficient drilling resistance (from torque measurement) in sands at the suggested
founding depth, and piles could extend to much greater depth than necessary.
It is therefore recommended that site specific static load testing be conducted from screw piles, if
adopted, at a minimum. Where tension or compression capacity developed in the footings is critical for
the future structure (e.g. resistance to uplift forces from high winds), then cyclic load tests (including
measurement of deflections under tension and compression cycles) should also be undertaken prior to
construction. Kentledge for static testing, or simulated cyclic loads, should prove the piles to a minimum
of two times the expected working load within tolerable deflections.
Footing design should also account for potential soil reactivity to be equivalent to Class M. It should be
noted that placement of reactive clay (which is not recommended) 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 9. This would also be
applicable when considering possible adverse interactions with buildings on adjacent properties.




                  Text Figure 9: Footing depth required to minimise risk of undermining




Proposed Residential Development
25 August 2025 | 25038-001-Rev0                                                                                 16