Attachment 4 - Geotech Report · MCU23/0030

                              50 NOOSA PARADE, NOOSA HEADS
                              PROPOSED RESIDENCE

Soil excavated below 1 m BGL will be mixed with a neutralising agent (fine agricultural lime) at rate of
19 kg lime per m3, as calculated from quantitative testing results.
Agricultural lime will be spread across the excavation zone at the prescribed rate, which will then be
excavated and mixed through in layers not more than 0.5 m deep at a time. This process will allow for
thorough mixing of the lime throughout the excavated material during the excavation process.
Once the material has been mixed and treated it will be sampled for verification testing. It is noted that
treated material may be stored on-site while verification testing is completed, however due to the spatial
limitations, treated soil may be transferred to designated storage stockpiles offsite while verification testing is
completed. If material is removed from site prior to completion of verification testing, all materials (including
volumes of soil, treatment rates and storage locations) must be recorded and tracked by the Contractor.
And, material must be stored in a fashion that will allow further treatment if necessary, with suitable drainage
management at the storage site to ensure that any surface water runoff and leachate is able to be captured
and effectively treated to ensure that no waters are released without meeting the required site release
criteria described in Table 5.
Following excavation of the basement to the design level, a lime guard layer will be applied to the
subgrade soil at rate of 1 kg lime per m2, prior to construction of the blinding slab, or basement floor.
The recommended liming rates assume the use of fine grained agricultural lime with a purity of not less than
90%, a soil bulk density of 1.8 tonnes per cubic metre, and a factor of safety of 1.5 to allow for incomplete
mixing and the reactivity of the lime. These rates are based on the results of the limited laboratory analysis
performed on the samples collected during previous investigations. The applicability of these rates to the
broader scale of the entire excavation is a function of the degree to which the samples taken during the
investigation are representative of the material to be excavated as a whole.

8.2.1        Verification Testing

To verify treatment of excavated ASS material, verification testing will be carried out at a rate of
1 test per 250 m3 of treated soil.
Verification testing will not be required for material encountered from the existing ground surface level to a
depth of 1 m BGL. As it is expected that approximately 1000 m3 of soil will be excavated from below 1 m
BGL during basement construction, 4 verification tests will be required.
Each verification sample will be taken by compositing treated material from no less than six subsample
locations (including at depth) from treated soil within the treatment area. The laboratory test regime for
validation testing will involve the measurement of pH, net acidity (the sum of actual, potential and residual
acidity) and acid neutralising capacity (ANC). Where the pH post treatment is greater than 6.5 and the ANC
is not less than 1.5 times the net acidity, then the validation shall be deemed successful.
If analysis of any verification sample/s indicates unsuccessful treatment, re-treatment of the represented soil
will be required prior to completion of another series of verification testing. This procedure should be
repeated until successful treatment has been verified.

8.2.2        Agricultural Lime Availability

To help demonstrate that appropriate quantities of lime have been used as specified to neutralise the ASS,
quantities of lime delivered to the site, verified by delivery dockets, will be maintained by the Contractor. The
lime usage shall quantify volumes of soil treated.
It is expected that that approximately 20 tonne of agricultural lime will be required for soil treatment during
construction. The contractor should ensure that a stockpile of at least 2 tonne of fine-grained agricultural
lime be kept at the treatment site during the construction period. This stockpile should be stored in a fashion
so as to prevent the unplanned release of the lime into the environment, through erosion or runoff.




2 February 2023
Report No. 22500-001-Rev0                               16