Scg 28045(S) · MCU18/0048

3     SITE DESCRIPTION

The construction area has a gradient in the order of 12%.

Vegetation on the construction area (and nearby surrounds) consists of grasses and scattered trees.

The trees are located on and adjacent the proposed construction site.

The trees are of a height and proximity that could affect the moisture conditions within the proposed construction
site. Refer to the appendices to the rear of this report for guidance on Trees and Construction.

The existing surface drainage is good and sub-surface drainage is good.


4     FINDINGS

The soil profiles encountered are shown on the attached borelog sections.

No water table was encountered during our testing program.

reased concrete volumes. Temporary shoring or similar maybe required.

The sandy soils encountered are susceptible to collapse when unconfined. This may effect excavations and
result in additional earthworks and increased concrete volumes. Temporary shoring or Forma-Tube may be
required to retain the sands prior to concreting.

The samples classified on-site were assessed as having negligible plasticity, therefore laboratory testing was
considered unnecessary.

We have assessed the expected differential movement of the soil profiles encountered to be the equivalent of a
site with a Ys of less than 20mm.

For buildings within the scope of AS 2870-2011 a maximum allowable bearing pressure of 100 kPa is available
within the natural soils at the following depths:

                                Test Site 1 - 1500 mm         Test Site 2 – 1700 mm

The following foundation material will provide a safe bearing capacity (100 kPa) for buildings within the scope of
AS 2870-2011 and is shown shaded on the attached logs;

            FOUNDATION MATERIAL - NATURAL MEDIUM DENSE SILTY SAND

5     SITE PREPARATION DETAILS

We recommend scraping this site free of all organic material and debris. The area of the garage should then cutg
and filled to form a level pad. The fill should be clean material from the cut, laid out in 150mm (maximum) layers
and tracked rolled with the excavator (six passes in each direction) and extended out 2.0m (minimum) from the
building footprint. This fill must not exceed 300mm in depth beneath the slab. A small surface spoon drain
with a suitable outflow should be excavated at the base of the cut. Cut batters of 1 to 2 (vertical to horizontal)
and fill batters of 1 to 3 will be stable providing all fill is compacted as above and exposed banks are protected
against erosion.

For the main level the proposed construction areas should then be levelled suitable for the construction of a block
base. The bases must be filled with a clean granular material such as sand, crusher dust or deco rock. The fill
is to be free of organic material and have no clay content. The fill is to be wetted and compacted in 150mm
layers with a vibrating plate making 6 passes (3 in each direction). Temporary back propping to the block base
should be provided throughout the compaction process. The compaction is to be sufficient to achieve a blow
count of 7 blows per 300mm with an approved Perth Sand Penetrometer. Test results must be presented for
approval prior to commencing slab preparations. Where a timber floor is being used, grasses can be left in place
and site cuts are not required unless the need exists to reduce the fall across the site. A spoon drain must be
constructed across the high side of the house.

Where a retaining wall is required, a cut batter of 1 to 2 (vertical to horizontal) in the sand profile taken from the
base of the proposed wall should be excavated. These earthworks must incorporate shallow surface spoon
drains at the base and along the high side of the cut. Drains must have an efficient outflow down-slope and clear
     SCG Consulting Engineers                                2                                     SCG Ref: 28045(S)