1-22276-01 site plan

Project No. 1-22276                                                                                                                  Page | 22
February, 2020
Ref: 1-22276, 2020-02-28, BR VER 2
Wessel Petroleum Pty Ltd – GEOTECHNICAL INVESTIGATION - Proposed Service Station Reconstruction, 52-54 Mary Street and Weyba Road,
Noosaville




       6.4 Building Foundation System

           6.4.1       Design Considerations

The foundation system for the proposed building should be designed and constructed to
accommodate the potential ground movement resulting from the differential settlement of the
weak fill and natural soils together with volume instability of the clay soils.

There is the potential for differential settlement resettling from densification of the fill and very
loose to loose natural sands under loading. The weak material extended to depths of between
0.3m and 2.4m at the borehole locations. For the anticipated structural loadings and the limiting
design allowable bearing pressures as outlined in Table 3, potential settlements would be a
maximum of 25mm at the borehole locations, except in BH9 where deep fill to 2.4m depth
(possible U/G tank backfill) where the potential value would increase to the order of 40mm.

Foundation Options

Both high level and deep support foundation systems could be considered for the proposed
development provided the designs accommodate the above considerations and earthworks are
carried out in accordance with the recommendations outlined in this report.

           6.4.2       High Level Footings

High level strip/pad footings should extend through uncontrolled fill and found a minimum of
200mm into controlled fill (provided existing fill and loose natural soils have been removed
or appropriately treated), or natural competent material.

Table 4 outlines allowable bearing capacities for high level footings on the site.

TABLE 4                ALLOWABLE BEARING CAPACITIES FOR HIGH LEVEL FOOTINGS
                                                                                     Allowable Bearing Capacity (kPa)
                              Material
                                                                                   Strip Footing          Pad Footing
                                      - Existing                                        NR                     NR
Fill
                                      - Controlled & Certified                        100-150               100-150
                                      - Very loose to Loose                             NR                     NR
Sandy Soils                           - Medium Dense                                    100                    125
                                      - Dense / Very Dense                              400                    450
Notes:
1. The allowable bearing capacity available in the controlled and certified fill will be dependent on the GTA
    undertaking the supervision works together with the base preparation and quality of the fill.



The base of all pad and strip footings founding in sand should be individually recompacted
using a vibrating plate compactor prior to placement of reinforcing steel and concrete as soils
may be loosened during the excavation process by machinery action.

If the sand is dry, it should be saturated and left for a short period prior to compaction. Should
any loose areas be encountered in the footing excavations, the density of these areas must be
improved. Dynamic cone penetrometer tests should be carried out to confirm the adequacy of
the founding soils. Note that it may be necessary to use formwork to prevent trench side
collapse in the sand profile.




                                                                                                            SOIL SURVEYS