1-22276-01 site plan

Project No. 1-22276                                                                                                                  Page | 26
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




openings or vertical construction joints at regular intervals. Guidelines on articulation are
contained in the Cement and Concrete Association's Technical Note 61 'Articulated Walling'.

           6.4.5       Slab On Ground

Field and laboratory test results indicate that the existing fill and natural soils, along with any
controlled fill, are suitable for slab on ground construction provided that earthworks are
carried out in accordance with recommendations in Section 6.2.

However the existing fill as encountered at the location of BH9 is considered unsuitable for slab
on ground support. A fully suspended system support on pier is recommended in areas of deep
filling.

Sub-Base

It is suggested that a 150mm layer of sub-base be provided under all vehicular trafficked
concrete slabs. The sub-base material should be compacted to a density not less than 95% of
maximum dry density in accordance with AS 1289 5.2.1 (Modified compaction). The sub-base is
provided under a concrete slab to:-

Provide a stable 'working platform' on which to operate construction equipment.

Facilitate the provision of a uniform bearing surface under the slab.

Sub-base material should be of good quality conforming to requirements (minimum) of Material
Type 2.4 as specified in the Department of Transport and Main Roads Technical Standards
MRTS05 Unbound Pavements (July, 2017).

    6.5 Temporary Retention
It is understood that excavation for underground storage tanks and potentially surrounding
contaminated soils (if present) could be expected to be of the order of 4.5m, or deeper.

Considering the subsurface profile encountered, in particular the very loose to loose sandy soils
and a high water table, temporary retention/shoring of the deeper excavations is expected to be
required and recommended.

Shallower excavations may be suitable to batter to the safe batter angles outlined in Section
6.2.8 of this report, where lateral clearance between the top of the excavation batter and
adjacent structures/boundaries/services is available. The presence and rate of groundwater
seepage into the excavation must also be taken into consideration where batter angles are
adopted.

Given the geotechnical model based on the boreholes drilled on site, the underground storage
tank excavation will extend through the fill and upper level loose/medium dense sandy soils, the
indurated sand layer and into the underlying medium dense sandy soils and very stiff clays.

Table 6 presents the geotechnical design parameters for retention design.




                                                                                                            SOIL SURVEYS