6. Noosa River DMP Ver0 (Combined)

    Project No. PG-5412                                                                                                     Page | 3
    January, 2023
    Ref: PG-5412, 2022-11-03, GR VER 3
    International Coastal Management – Acid Sulfate Soil Investigation - Noosa River Dredging Program, Noosa River, Noosa




5.0 LABORATORY TESTING

Testing was carried out on selected samples retrieved from the site investigation
program and was directed towards assessing the testing for acid sulfate presence in
the area previously identified as a hot spot.

Testing was undertaken by Pacific Geotech.

Laboratory testing included:-

•       pH/pHfox testing – screening tests to qualitatively assess the acid sulfate soil
        potential of the soils.
•       Chromium Suite testing – qualitative testing of the acid sulfate soils.
The results of the laboratory testing are presented in Appendix C.

Additionally, historical testing was undertaken for the works as part of the Noosa River
– Sediment Sampling Plan Report by BMT dated 14th April, 2022.

The results of this provided testing are appended to this report.

6.0 ACID SULFATE SOIL LABORATORY TESTING

Laboratory testing was undertaken in general accordance with the
recommendations outlined in the QASSIT 'Acid Sulfate Soils Laboratory Methods
Guidelines 2004'. The results of the testing program are appended to this report.

The testing program comprised of initial screening tests on recovered samples,
followed by quantitative testing using the Chromium Reducible Sulfur (CRS) suite.

Screening Tests

Screening tests were undertaken on each soil sample collected from the bores. Two
small sub-samples of each soil sample were prepared; one sub-sample from each
sample was mixed with approximately 20mL of distilled water, and the other sub-
sample mixed with approximately 20mL of hydrogen peroxide (H2O2), buffered to a
pH of 5.4 with sodium hydroxide.

Slurry pHs were measured with a calibrated pH meter. The pH of the distilled water/soil
slurry (pHF) was measured approximately one hour after mixing, whilst the pH of the
hydrogen peroxide/soil slurry (pHFOX) was measured approximately one to two hours
after mixing.

The pH screening tests can be used for the preliminary identification of a potential or
actual ASS using a combination of three trigger factors as follows:

        a) The strength of the reaction with peroxide is a useful indicator but cannot be
           used alone. Organic matter and other soil constituents such as manganese
           oxides can also cause a reaction.