MCU14/0106 Appendix E - Engineering Report

 

August 2004 -13- 04682104(AB)

 

7.2 Soil Sampling

Tn accordance with SPP2/02 a test pit sampling program was defined based on the broad scale
information obtained from the desktop assessment (Section 4.2) and calculations from the extent
of the proposed disturbance. The Queensland Sampling Guidelines Section 4.2 indicate a
minimum of 1 borehole per 50 m for linear disturbances. The depth of investigation was
established at 3 m, being 1 m below the anticipated ground water level. ASS samples were
recovered from three test pits (GA16-18) to 3 m depth where the proposed development area
extends below RL 5 m AHD.

Soil sampling, handling and testing was conducted as described in Section 4.2.

7.3 Field pH (pH,) and Peroxide pH (pHeox)

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 (pH;) as soon as possible after sampling and then
measuring pH following oxidation of the soil in suspension with a strong oxidising agent
(hydrogen peroxide) provides a simple, relatively conservative test procedure to detect soils
which are not likely to be acid sulfate soils. The test simulates extreme natural conditions and
PH drops following this test may not be entirely attributable to pyrite oxidation.

pH; was measured at the analytical laboratory (Bio-Track). Soil pH; and pHrox are summarised
in Table C1 attached in Appendix C.

Soil field pH was found to range between about pH4 and pH5, being moderately acidic.

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7.4 Summary of Soil Analysis Results

Table 3 shows the ASS action levels adopted by Queensland authorities based on three broad“
texture categories (QASSIT Guidelines - October 1998). These categories have been used to
highlight significant results in Table C1, based on the Action Criteria for greater than
1000 tonnes of disturbed soils.

Golder Associates