Att 9 - Geotech and PASS report

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    The chromium reducible sulfur values (SCR) where greater than 0.01 %S indicates a significant
     level of sulfide, and where greater than 0.03 %S then the soil has a potential acidity level
     exceeding the QASSIT guideline value. Samples of the natural sandy clay from Bores 1 and 2,
     the natural silty sand from Bore 3 and the clayey sand filling in Bore 4 tested returned SCR values
     equal to or greater than 0.03 %S.
    Where the total actual acidity (TAA) value exceeds 18 mol/t then the soil has an acidity level
     exceeding the QASSIT guideline value. Only the clayey sand filling tested from Bore 4 returned
     TAA value of greater than 18 mol/t, all of the remaining samples tested were alkaline with the
     ability to neutralise (ANC) any potential acid generated.

Generally, the action criterion from the chromium suite of tests, which triggers a requirement for ASS
disturbance to be managed is as follows:
    Net Acidity (TAA + SCR + SNAS – ANC/1.5) of greater than or equal to 0.03 %S

The above action criterion was exceeded in only the one sample of clayey sand filling tested from Bore
4. Using the results of the laboratory testing, the addition of lime to neutralise the ASS in the
disturbance to any clayey sand filling would be required at a rate of up to 2.75 kg of lime per tonne.
                                                                                         3
Assuming an overall stockpile density, after ‘bulking up’, of approximately 1.5 tonnes/m , this equates
                                                      3
to a lime application rate of approximately 4.25 kg/m (Liming rates assume a safety factor of 1.5, and
97% lime neutralisation).

No other samples tested exceeded the action criterion, indicating treatment to neutralisation any ASS
is considered not necessary.




9.     References

1.     Australian Standard AS 2870-2011 “Residential Slabs and Footings”, Standards Australia

2.     Ahern, C R, Ahern, M R, and Powell, B, “Guidelines for Sampling and Analysis of Lowland Acid
       Sulfate Soils (ASS) in Queensland 1998”, QASSIT, Department of Natural Resources,
       Resources Sciences Centre, October 1998.

3.     Dear, S E, Moore, N G, Dobos, S K, Watling, K M, Ahern, C R, and O’Brien, l E, “Queensland
       Acid Sulfate Soil Technical Manual: Soil Management Guidelines”, Department of Science,
       Information Technology, Innovation and the Arts, 2014.

4.     Ahern, C R, Sullivan, L A, and McElnea, A E “Laboratory Methods Guidelines 2003 – Acid
       Sulfate Soils” in “Queensland Acid Sulfate Soil Technical Manual”, Department of Natural
       Resources and Mines, August 2003.

5.     Australian Standard AS 3798-2007 “Guidelines on Earthworks for Commercial and Residential
       Developments” Standards Australia.

6.     Australian Standard AS 2159-2009 “Piling – Design and Installation”, Standards Australia.

7.     Australian Standard AS 4678-2002, “Earth Retaining Structures”, Standards Australia




Geotechnical Investigation, Proposed Commercial Development                           90151.00.R.001.docx
11-19 Hilton Terrace, Tewantin                                                                  May 2017