220328 - Edwards Street - Slope Stability Assessment

Bev Jenner Const.                                                                               22073-001-Rev0
C/- Westera Partners                                                                             25 March 2022

similar means. Given the sandy soil profile and depths of footings required in some areas, steel screw piles
are considered to be a suitable foundation medium.

If steel screw piles are adopted, it is recommended that site specific static load testing be conducted, 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.

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 advised by Unearthed to be equivalent to
Class S.

All footings should be founded such that they are not adversely affected by or affect any adjacent
excavations, trenches, retaining walls, or in ground structures that are not designed to support building
loads. Footings should be founded 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.




                           Text Figure 9: 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.
It will be important to ensure close supervision of screw pile installation, as piling will likely not encounter
drilling refusal or ‘high’ torque readings at the recommended founding depth, and piles could extend to much
greater depth than necessary.

Should bored piles be adopted, it is essential that the piling contractor have a ‘mud bucket’ or similar to
enable clean out of the pile bases. It is recommended that bored pile sockets be inspected by a suitably
qualified and experienced engineer prior to placement of steel reinforcement and pouring of concrete to
confirm allowable bearing pressures and cleanliness.




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