RFI - Attachment G - Acid Sulfate Soils Investigation

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6.     Laboratory Testing

Preliminary field screening and chemical laboratory tests for ASS were carried out with reference to
the QASSIT Guidelines (Ahern et al 1998), the Soil Management Guidelines (Dear et al 2014) and the
Laboratory Methods Guidelines (Ahern et al 2004).

Samples were recovered from the bores at regular intervals and were screened by measurement of
pH after the addition of distilled water (pHf) and peroxide (pHfox). The pHf test provides a preliminary
indication of past oxidation of sulfides resulting in the presence of actual acid sulfate soils (AASS). The
pHfox test provides a preliminary indication of the presence of unoxidised sulfides and therefore,
potential acid sulfate soils (PASS).

Based on the results of the screening tests and visual inspection of the samples, selected samples
were subjected to more rigorous Chromium Suite analytical testing. The results of this testing are
discussed further in Section 7.2.2 and detailed report sheets in Appendix D.




7.     Comments

7.1    Previous Investigation

DP previously carried out a geotechnical investigation this site as part of an earlier proposed
commercial development which also included the adjacent industrial development to the south. The
results of the previous investigation are present in the report entitled “Report on Geotechnical
Investigation, Proposed Commercial Development, Lot 1 Noosa Metro, Eenie Creek Road, Noosaville”
DP Project 47928 dated 10 July 2009.



7.2    Acid Sulfate Soils

       7.2.1 What are Acid Sulfate Soils

Acid sulfate soils (ASS) are naturally occurring sediments and soils containing iron sulfides or sulfidic
materials, often located over extensive low-lying coastal areas, predominately below RL 5m AHD.
These soils are generally found close to the natural ground surface, but may also be found at depth
within the soil profile

ASS includes actual acid sulfate soils (AASS) and potential acid sulfate soils (PASS). AASS and
PASS are often found within the same soil profile, with AASS generally overlying PASS. AASS are
highly acidic resulting from the oxidation of soil materials that contained sulfides. PASS are soils that
contain iron sulfides or sulfidic materials, which have not yet been oxidised.

       7.2.2 Criteria for Evaluation of Acid Sulfate Soils

The criteria on which the results of screening tests (pHf and pHfox) were assessed as indicative of
possible actual acid sulfate soils (AASS) or potential acid sulfate soils (PASS) were based on the
QASSIT Guidelines as follows:



Acid Sulfate Soils Investigation, Proposed Medical Centre                               94967.00.R.001.docx
36 & 40 Hofmann Drive, Noosaville                                                                 May 2019