Geotehnical Investigation Report · OPW22/0140

                             PROPOSED UNIT DEVELOPMENT
                             37 BOTTLEBRUSH AVENUE, NOOSA HEADS

If filling or permanent cuts exceed 1 m high/deep, then these must be retained. Permanent cut and fill batters
up to 1 m high shall not exceed 1V:2.5H. Any permanent soil and fill batters will require erosion protection
(e.g. revegetation or surface protection).
It is likely that above temporary batter slopes may not be able to be achieved in places, due to spatial
constraints, and so temporary shoring will be required (e.g. sheet piles) as per the recommendations in
Section 6.4 below. Excavations in close proximity to existing structures, including on neighbouring
properties, will need to be specifically designed to prevent undermining. It is recommended that footing
exposures or confirmation of foundations via certified building plans be undertaken to assess the possibility
of undermining. If undermining is a potential issue the existing structures may need to be underpinned or
excavations may require temporary shoring.

The advice of a suitably qualified and experienced structural RPEQ must be sought regarding any potential
undermining as well as design and construction of any underpins/temporary shoring (if required).

The above recommendations do not supersede any existing safety regulations or legislation applicable to
excavations (e.g. limits on personnel entry into trenches).
Due to the highly permeable nature of the sands at this site, stormwater is expected to rapidly infiltrate the
ground, making un-sealed surface drainage ineffective for the control of flows. Any sealed areas should be
graded to ensure free drainage of stormwater away from construction areas, and to a control point(s).

6.2.3       Filling
The existing sandy soils (fill and natural) where free of deleterious materials (e.g. vegetation, building debris
etc.) may be reused as structural fill, subject to appropriate moisture adjustment. It should be noted that
compaction of such relatively ‘clean’ sands as structural fill requires the addition of substantial volumes of
water (‘flooding’) combined with the use of vibratory compaction equipment (typically a smooth drum roller or
heavy vibrating plate).

Should importation of fill be required, it is recommended that such fill should comply with the following:

       Minimum CBR of 10%
       Maximum plasticity index of 15%
       Shrink-swell index ≤ 1%
       Maximum particle size of 100 mm

Any fill should be compacted at moisture contents within the range of ±2% of optimum moisture content for
Standard Compaction. Fill material should be placed in 250 mm thick (loose thickness) layers and be
compacted by repeated rolling using a minimum 4 tonne smooth drum roller (or equivalent, with vibration on
if safe to do so) to achieve a dry density ratio of at least 95% of the maximum Dry Density Ratio (DDR),
based upon the Standard Compaction method, or a Dry Density Index of at least 70%.

Confirmatory compaction testing must be carried out at regular intervals. A minimum of two tests per vertical
lift is recommended where structural fill heights are to exceed 300 mm. Further details for control and testing
of fill are given in Australian Standard AS 3798-2007 Guidelines on Earthworks for Commercial and
Residential Developments.

Fill embankment edges must be over-filled by 0.5 m (horizontally) and then trimmed back to well compacted
material.




13 May 2022
Report No. 22151-001-Rev0                              11