Reference Document - MCU24/0023

GJ Gardner Homes Gympie                                                                          23236-001-Rev0
C/- Covey Associates Pty Ltd                                                                       7 August 2023

     Filling across the south-eastern part must be removed such that the currently over-steep batter can be
      reprofiled to 1V:2.5H and surface water must be diverted away from that area and directed as sheet
      flow to the eastern spur.
     Further earthworks cut/fill heights shall be limited to less than 0.5 m unless assessed and approved by a
      geotechnical RPEQ.
     Formalised drainage should be constructed to ensure all stormwater is directed away from the proposed
      structures.

Should any revisions be made to the proposed extent of the development, Tectonic must review these prior to
construction to assess if there are any impacts on slope stability.

4.2    Earthworks
It is anticipated that only minor earthworks (< 0.5 m deep/high) will be required to form final levels for the
residence. Deeper excavations may be required for underground footings and service trenches. Filling
should not exceed 0.5 m high, unless assessed and approved by Tectonic prior to construction.

4.2.1 Site Preparation and Trafficability
Any organic rich topsoil, uncontrolled fill, firm/loose (or weaker) soils and overly wet materials must be
stripped and removed from any pavement or at grade construction areas. Topsoil materials must not be
used in structural fill; however, may be placed across landscaping areas. It is recommended that any at
grade building/pavement subgrades be proof rolled using a minimum 4 tonne pad foot roller to identify any
‘soft spots’. Any such soft spots should be excavated and replaced with select fill material, constructed as
recommended in Section 4.2.3.

The subgrade materials exposed after site stripping and excavations are expected to comprise stiff (or stiffer)
gravelly clays. The clayey soils could be subject to strength loss from repetitive vehicle loading (particularly
from rubber tyred plant) or if they become wet. Due to the potential for poor trafficability during and after wet
periods, placement of a minimum 150 mm thick granular working platform may be required, particularly along
access ways and any laydown areas.

The site should be graded to shed surface water runoff away from construction areas. It should be noted
that during wet weather, the natural soils may cause turbid stormwater run-off. Appropriate erosion and
sediment control measures must be installed prior to commencement of earthworks at this site.

4.2.2 Excavations
Excavations within the soils to the GD investigation depths, should be achievable using small to medium
sized conventional earthmoving plant (e.g. 5 to 14 tonne excavators) with toothed buckets, or ripper
attachments. Although not anticipated, should excavations extend into any low strength (or stronger)
weathered rock, the use of larger earthmoving plant with ripper/hydraulic breaking attachments may be
required.

Temporary, non-surcharged batter slopes may be formed at 1V:1H in the stiff (or stiffer) soils, provided
groundwater seepage is not encountered. Flatter batters may be required if groundwater seepage is
encountered, or if earthworks are undertaken during a period of heavy rainfall. Permanent non-surcharged
batters in stiff (or stiffer) natural soils and controlled fill must be formed no steeper than 1V:2.5H. Where such
battering is not possible, temporary and/or permanent retention will be required.

Existing over-steep cut and fill batters shall be trimmed back to permissible grades as outlined above or
retained.
The above recommendations do not supersede any existing safety regulations or legislation applicable to
excavations (e.g. limits on personnel entry into trenches).




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