4895-Geotech Assessment

Mr Max Richardson                                                                                   20362-001-Rev0
C/- Long View Consulting Engineers Pty Ltd                                                             28 July 2021

Ground surfaces should be graded to shed surface water runoff away from construction areas. It should be
noted that during wet weather, the natural soils may cause turbid stormwater run-off. Appropriate erosion
and sediment control measures must be installed prior to commencement of earthworks at this site.

4.3    Footing Design
Footings for the proposed residence and any ancillary structures (e.g. retaining walls) must penetrate
through any future fill and residual soils to ‘socket’ at least 0.3 m into very low strength (or stronger) phyllite.
Normally dimensioned, conventional high-level footings would likely be appropriate in cut areas, extended
locally via the use of steel reinforced concrete bored piles (or ‘bucket piers’) in fill areas or where soil depths
are greater.

Footings could be designed with an allowable bearing pressure of 400 kPa very low strength (or stronger)
phyllite.

Footing design should also account for the characteristic surface movement (ys), to be advised by others
following completion of a ‘soil test’ for the residence in accordance with QBCC requirements.
All footings should found such that they are not adversely affected by any adjacent excavations, trenches, or
retaining walls 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, then rising up at 1V:1H, as
illustrated in Text Figure 10.




           Text Figure 10: Footing depth required to minimise the risk of undermining and surcharge loading

Footing bases must be cleaned following mechanical excavation to expose undisturbed materials over the
full base area. Where piles are required, it is essential that the piling contractor have a ‘mud bucket’ or
similar to enable clean out of the pile bases. A suitably qualified and experienced engineer should inspect
the footing excavations to confirm appropriate foundation materials and cleanliness prior to pouring
concrete.
If any soil conditions encountered during construction are found to differ from those noted above, Tectonic
must be notified immediately and an inspection carried out to determine if changes to footing design are
required.




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