Att 9 - Geotech and PASS report

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     Care should be taken not to over-wet clay soils as this can lead to problems associated with
      trafficability and workability. Clayey soils should not be over-compacted (ie. not more than 102%
      Standard) or placed too dry of OMC, as this can lead to future swelling and softening with
      changes to moisture content or inundation from water.
     Filled batters should be overfilled and then cut back to the required design batter angles in order
      to maximise compaction of the material in the batter faces.
     Field density testing should be carried out to confirm the standard of compaction has been
      achieved and the placement moisture content. The frequency of testing should be carried out in
      accordance with AS 3798-2007. Level 1 inspection and testing of filling must be undertaken
      where the filling exceeding 0.5 m in depth is to support buildings, pavements or settlement
      sensitive structures or Level 2 otherwise.
     On completion of earthworks, it is important that the upper surface of new filled areas be
      prevented from ‘drying out’ as this could lead to significant post construction swelling beneath the
      building foundations and floor slabs which could damage the buildings. Where clay material is
      exposed at subgrade level, it is recommended that a minimum 150 mm thick layer of granular
      material (minimum CBR 10%) placed over any exposed clay subgrade to reduce the potential
      dry-out at the top of the filled platform.

The above procedures will require geotechnical inspection and testing services to be employed during
construction. DP is suitably qualified to conduct earthworks testing and supervision services that will
be required during earthworks construction.



8.2    Excavation

Based on the ground conditions encountered, excavations in the filling and natural soils could be
undertaken using conventional small to medium sized earthmoving equipment, such as drotts,
backhoes or 8-15t (or larger) excavators.

The use of pneumatic tools or rock breakers may be required if any concrete is encountered.

It should be recognised that the excavatability estimates are based on materials encountered at the
bore locations only and that conditions may prove more difficult (or easier) for excavatability beyond
these bore locations and the depths drilled as part of this investigation.



8.3    Batter Slopes

Near vertical temporary excavations less than 1 m depth in dry soils are likely to be suitable for the
short term installation of underground services provided there are no sensitive services or structures,
or vehicular trafficked areas are located close to the excavation. Excavations in sands have the
potential to ‘collapse’ unexpectedly in a trenching situation, particularly where groundwater seepage is
encountered. Excavations in these materials should be considered unstable and shoring of trench
excavations in wet sands will be required.

All excavations greater than 1 m depth will need to be benched or battered for stability and prior to
personnel entering the excavation.



Geotechnical Investigation, Proposed Commercial Development                             90151.00.R.001.docx
11-19 Hilton Terrace, Tewantin                                                                    May 2017