6. Noosa River DMP Ver0 (Combined)

                                                              Noosa River - Sediment Sampling Report
                                             BMT (OFFICIAL)



3.3 Analytical Results

Metals and Metalloids
Results for metal and metalloids are presented in Table 3.2. Most metals and metalloids were detected
either below the LOR (antimony, beryllium, boron, cadmium, mercury and silver) or at low
concentrations across the study area. The 95% UCLs were calculated from parameters with greater
than 25% detection across all the sampling locations. The 95% UCL for all metals/metalloids were
below the NADG screening level and NEPM guideline values.

Nutrients and Carbon Content
Nutrient concentrations were sampled at all sites, and there are no relevant guideline values for marine
sediments. Apart from ammonium (NH4), other inorganic forms of nutrients (NO2, NO3) were below the
LORs in all samples. Ammonium was detected in ~40% of the samples and concentrations ranged
between <0.2 to 5.7 mg/kg (95% UCL = 2.7 mg/kg) and were typically higher in the upper strata. Total
Nitrogen (TN/TKN) was detected in ~58% of the samples and ranged from <20 to 320 mg/kg (95% UCL
= 134). Total Phosphorus (TP) was detected in all samples and ranged between 7 to 80 mg/kg (95th
UCL = 41.8 mg/kg).

Other Contaminants
Other contaminants that were tested at the top horizons at three sites (BH6, BH3 and BH4) including
PAHs, BTEXN, Organotin compounds, Organophosphorus Pesticides, Organochlorine Pesticides and
PFAS, were recorded below the LOR for each sample. The only exception was trace concentrations of
C10-C14 and C15-C15 TPH fractions at BH3 and BH4 however the sum of all TPHs were well below
the NAGD screening level.

Regardless, additional analysis was undertaken for total petroleum/recoverable hydrocarbons and
BTEXN on remaining samples. All results from additional analysis were recorded below the LOR.

Note: The LOR for PAHs was higher than the target PQL, however this is not an issue as the NAGD
screening level for sum of PAHs (10 mg/kg) is significantly higher than the LOR (0.5 mg/kg) used.

Acid Sulfate Soils
Acid sulfate soil test results are shown in Table 3.3.

The pHF and pHKCL values for the samples ranged from 6.9 to 9 and 5.9 to 9.5, respectively, indicating
that actual ASS was not present in the sediment samples within the dredge area. Actual acidity (TAA)
was below the LOR at all locations indicating that the sediments are not actual acid sulfate soils. The
only exception was site BH8 0.5-1.0 which recorded a 4 mole H+ / t TAA.

The results of the pHFOX test for all samples ranged from 2.1 to 6.3, which is lower than pHf and pHKCL
values. Given the slight to moderate reaction is noted and pHfox is typically <6, this is a moderate
indicator that PASS is present. Chromium Reducible Sulfur (CRS) was above the LOR at all locations
therefore potential acid sulfate soils (PASS) is likely to be present.

The net acidity (ex ANC) ranged between 0.04 and 0.39 (% S) in all samples. All sites met or exceeded
the National Acid sulfate soils guidance action criteria of 0.03% S for net acidity (excluding ANC)
(therefore requiring management). The overall liming rate (excluding ANC) comprising all samples
within the dredge area ranged between 2 and 18 kg CaCO3/t.




A10342 | 005 | 01                                    23                                      14 April 2022