Geotech Report - Initial Findings

Essence of Peregian
215-219 David Low Way, Peregian Beach
Project No. 007-160A,
27 April 2010




       SECTION 5 - GEOTECHNICAL DESIGN DISCUSSION
       5.1       Ground Model

       The results of the investigation indicate that the stratigraphy encountered at the bore locations generally
       comprised a discontinuous layer of fill and/or possible fill up to approximately 0.8m depth that was underlain
       by very loose to loose sands to approximately 1.2m to 3.9m depth with a layer of silty clay encountered in
       Bores 1 and 2, then medium dense to dense sands and dense, weakly cemented indurated sands. Strength
       inversions were encountered in the sands and indurated sands. For the ground conditions encountered at
       the test locations, geotechnical design will need to particularly consider at least (but not exclusively) the
       following key issues:

                 the condition of the existing fill material;
                 excavatability;
                 groundwater control during construction;
                 estimated site settlement;
                 retaining wall pressures;
                 suitable foundation types and founding level;
                 presence of ‘strength inversions’ and their effect on footing design;
                 the potential for significant settlement and/or liquefaction of the very loose sands;
                 potential for settlement in surrounding areas; and
                 construction issues.

       Discussion of geotechnical design parameters, as well as design and construction recommendations and
       suggestions are detailed in the following sections.

       5.2       Existing Fill Condition and Performance

       It is not known whether the existing fill material at the site is ‘controlled’ (i.e. it is not known whether the
       existing fill has been placed and uniformly compacted to an appropriate engineering specification).
       Supporting documentation should be obtained and checked to confirm whether the fill has been placed in a
       controlled manner to a specification that is appropriate for the proposed development. If documentation
       does not exist, or the specification is not appropriate for the proposed development, then it is suggested that
       the existing fill be assumed to be uncontrolled.

       If the fill cannot be shown to be controlled, then consideration should be given to the potential for variations
       in both the composition and degree of compaction of the fill. The presence of voids within uncontrolled fill as
       well as potential soft/loose zones or inclusions of deleterious materials may lead to potentially significant
       future total and differential settlements, possibly occurring over relatively short distances.

       To minimise the risk of potentially adverse settlement occurring, it is recommended that all uncontrolled fill
       present in settlement sensitive areas be removed and replaced/recompacted as controlled fill.




butlerpartners.com.au                                                                                            Page 8