RFI - 21370-001-Rev1 66 Seaview Tce

                              PROPOSED RESIDENCE
                              66 SEAVIEW TERRACE, SUNSHINE BEACH

piles are not anticipated to be suitable for this site. A suitable alternative to screw piles could be grout-
injected, CFA piles, provided that construction water loss is carefully monitored and controlled. Steel
reinforced concrete bore piles may be possible; however, the use of sacrificial liners (e.g. Formatube) would
be required.
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.

Ultimately, the advice of a specialist piling contractor should be sought regarding pile design and
construction. However, where steel screw piles are adopted site specific load testing and the results of this
geotechnical investigation should be considered by the structural engineers in validating any generic torque
to capacity ratios provided as part of the proposed design. An assessment of potential vibration effects on
nearby structures and monitoring requirements should also be included.
Footing design should also account for potential soil reactivity to be equivalent to Class M. It should be noted
that the placement of reactive clay may result in a more significant equivalent site classification, such as Class
H1 (or higher).

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/swimming
pool, then rising up at 1V:1H, as illustrated in Text Figure 12. Where consideration is given to the use of high
level footings to the eastern side of the residence, structural designers should allow for the deepest founding
depth of either:

       taking footings below the zone of active earth pressure (within this zone reduced foundation capacity
        and adverse interaction with the seaward retention system are anticipated); or
       the arrangement should comply with Text Figure 12, with the relevant plane taken from the
        equivalent ground level at the front of the exposed micropiled wall following the most onerous
        erosion case in the stability modelling (Ref. Section 5.2.1).




                            Text Figure 12: Footing depth required to prevent undermining




28 April 2022
Report No. 21370-001-Rev1                                18