Slope Stability Report-21190-001-Rev0 Pomona Kin Kin Rd

Phil Brierley                                                                                      21190-001-Rev0
C/- NDD Constructions Pty Ltd                                                                         21 June 2021

4.3       Footings
All footings supporting the proposed shed, workshop and ancillary structures (including retaining walls) must
penetrate through existing/future fill and unsuitable natural soils to found into competent underlying material
as follows:
          In areas containing fill or deeper natural soil profiles, steel reinforced concrete bored piles must
           socket at least 0.3 m in hard XW materials or very low strength (or stronger) weathered rock.
          In areas where cut exposes hard XW materials or very low strength (or stronger) rock at or near the
           subgrade level, footings must found at least 0.2 m into such materials.

Steel reinforced concrete bored piles so founded may be designed using an allowable end bearing pressure
(ABP) of 400 kPa in XW materials or very low strength (or stronger) weathered rock. High level footings in cut
areas may be designed using an ABP of 400 kPa in XW materials or very low strength (or stronger)
weathered rock.

Based on DCP testing undertaken from Tectonic high-level footings should be suitable in areas of cut, with
piles ranging up to about 3 m deep required towards the fill embankment crest. A suitably qualified and
experienced engineer should inspect the footing excavations to confirm appropriate foundation materials
and cleanliness prior to pouring concrete.
Footing design should also account for potential soil reactivity (to be determined by others). The site
classification should consider the potential variation of materials across the building platform.

All footings should found such that they are not adversely affected by (or affect) any adjacent excavations,
trenches, retaining walls (e.g. existing and future 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/batter slopes/excavations/retaining walls/swimming pool, then rising up at 1V:1H,
as illustrated in Text Figure 11.




                  Text Figure 11: Footing depth required to prevent undermining or 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.




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