Appendix 5. Geotechnical Engineering Report [As Published] · 132007.2399

October 2007                                    -7-                            077682076(AB)


excavation and filling earthworks during subdivision (eg. civil works to form roads,
underground services and realign the golf tees). SPP2/02 is therefore applicable to this site
and an assessment of potential disturbance of ASS is required.

5.1       Investigation Aims

The aims of this investigation were to:

•     Conduct a preliminary ASS assessment, partly in accordance with SPP 2/02 and
      Queensland Sampling Guidelines;

•     Identify the presence or absence of ASS in the proposed disturbance area; and

•     Provide an indication of the likely location of ASS and treatment methods.

The results of the preliminary ASS investigation follow.

5.2       Soil Sampling


In accordance with SPP2/02 a borehole sampling program is to be defined based on the broad
scale information obtained from the desktop assessment (Section 4.1) and calculations of the
extent of the proposed disturbance. The Queensland Sampling Guidelines Section 4.2
indicate a minimum of 6 boreholes per hectare for sites of between 1 and 2 hectares (less than
half of the site is located below RL 5 m AHD). A total of six ASS boreholes would therefore
be required to satisfy the Guidelines.

Due to the preliminary nature of current project planning, a preliminary ASS investigation
was carried out comprising two boreholes (BH5 and BH8) within the lowest-lying south-
western part of the site (golf tee realignment area). Four additional boreholes will be required
to satisfy the required density of testing specified in the Queensland Sampling Guidelines and
these should be carried out once more detailed information is available regarding the proposed
development.

The depth of investigation, being 3 m, was established as at least 1 m below the anticipated
depths of disturbance, being up to 2 m for service trenching.

Soil sampling, handling and testing was conducted as described in Section 3.2.

5.3       Field pH (pHF) and Peroxide pH (pHFOX)


A typical consequence of the oxidation of pyrite in soils and the formation of sulfuric acid is a
drop in soil pH. Measuring field pH (pHF ) as soon as possible after sampling and then
measuring pH following oxidation (pHFOX ) of the soil in suspension with a strong oxidising
agent (hydrogen peroxide) provides a simple, relatively conservative test procedure to detect




                                      Golder Associates