2016-03-01 Planning & Organisation Committee Agenda

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          Geotechnics | Environment | Groundwater                                             Page 2 of 3

 samples. On completion, the bores were observed for groundwater seepage and then backfilled with
 spoil tamped into the holes.

 The field work was undertaken by experienced geotechnical personnel who logged the bores,
 collected disturbed samples for visual and tactile assessment.

 3.     Field Work Results

 The subsurface conditions encountered in the bores are described in detail on the attached borehole
 logs. In summary the subsurface conditions encountered in the bores typically comprised filling to
 between 4.1 m and 5.9 m depth. The filling typically comprised a gravelly sandy clay overlying a sandy
 clay which was in turn underlain by a silty clay in Bores 2, 3, and 5.   The filling was underlain by
 natural sandy then silty clays.

 No groundwater seepage was observed during the investigation; however, it should be noted that
 groundwater depths and ground moisture conditions are affected by climatic conditions and soil
 permeability, and will therefore vary with time.

 4.     Comments

 4.1   Appreciation of Ground Conditions

 DP previously carried out geotechnical investigations on the site in 2006 and 2008. In the area of the
 site, uncompacted to poorly compacted filling with foreign material (ie. bricks, timber, steel sheeting,
 steel pieces, tree roots) was encountered up to 4.7 m depth. As mentioned above, filling was
 encountered to between 4.1 m and 5.9 m depth in the recent bores. The near surface filling
 encountered in the bores at the time of this investigation appear to be clean of any foreign, deleterious
 material or topsoil material rich in organics or root matter. Any organics or foreign material including
 concrete, plastic, wire and bricks encountered within the recent bores was encountered typically in the
 sandy clay filling material below 1    m depth consistent with the ‘uncontrolled’ filling previously
 encountered.

 The settlement of ‘uncontrolled’ filling cannot be reliably predicted as it is unknown whether the filling
 has been placed and uniformly compacted to an appropriate engineering standard. The presence of
 voids within the ‘uncontrolled’ filling as well as potential soft/loose zones or inclusions of deleterious
 materials may lead to potentially significant settlements, with possible large settlement over short
 distances (ie. differential settlements) where looser pockets occur in the filling.

 4.2    Recommendations for Future Construction

 Given the above, future development on the site will need to be planned, designed and constructed in
 accordance    with sound   and   proper engineering    principles, and  more   specifically take  into
 consideration the potential long term settlement or creep of the ‘uncontrolled’ filling.

  178 Eumundi-Noosa Road, Noosaville                                                     September 2015

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