Acid Sulfate Report

                               25 EDWARD STREET, NOOSAVILLE
                               PROPOSED DUPLEX DEVELOPMENT

6.3       Quantitative Laboratory Analysis
Quantitative laboratory analyses were completed on 6 samples using the Chromium Reducible Sulfur (SCR)
suite of testing in order to quantify the severity and nature of any acidity or potential acidity present in the soil
profile. The quantum of any actual acidity was assessed using Titratable Actual Acidity (TAA), and
potassium-chloride extractable sulfur (SKCl) was used to assess the nature of the measured actual acidity.
Potential acidity was measured by the SCR method which specifically measures inorganic oxidisable sulfur.
These methods are set out in the QASSIT guidelines and associated ASS management documents.
Based on the nature of the proposed disturbance an action criteria of 0.03%S (18 mol H+ per tonne) was
adopted for comparison with the combined actual and potential acidity results.
Samples obtained from BH1, and above the groundwater table in BH2 (typically 0.0 m to 1.0 m BGL),
contained no actual or potential ASS above the defined action criteria. Samples obtained from below the
groundwater table in BH2 (typically below 1.0 m BGL) contained no actual acidity, but did contain levels of
PASS which exceeded the 0.03%S action criteria, ranging from 0.039%S to 0.062%S.

6.4       Risk Characterisation
Sands sampled from below the groundwater table (below 1.0 m BGL), from BH2 were characterised as
containing levels of oxidisable sulfur (PASS), averaging 0.05 %S (31 mol H+ per tonne). This material
presents a moderate risk if disturbed, and should be avoided where possible. This underlying acidic soil is
not likely to be disturbed by the proposed works and thus presents a low risk to the overall development of
the site.
Where construction of deep stormwater/sewer infrastructure or the proposed pool is expected to disturb soil
from below 1.0 m BGL, the risk posed by disturbance of potential acidity within the underlying sand may be
mitigated by conventional lime neutralisation of the disturbed material, combined with management of any
construction site runoff. Recommended measures for management of acidic, non-sulfuric soil are set out in
Section 7.0 below.


7.0       MANAGEMENT RECOMMENDATIONS
Where works are only expected to disturb soils within 1.0 m of the existing ground surface, these works may
proceed without specific management measures for ASS. However, should disturbance of the sands at and
below 1.0 m BGL occur, the following management measures should be adopted:

▪     Where sands below 1.0 m BGL are disturbed, fine grained agricultural lime shall be mixed with the
      disturbed material prior to treated material being reused on site, or exported off site. The neutralising
      agent (fine grained agricultural lime) shall be applied at a rate of 2 kg per cubic metre.
      It is anticipated that the only works which may disturb this material would be for construction of sewer
      reticulation, to tie in with the existing sewer main. Some of the deeper pool construction may also be
      likely to disturb soils below 1.0 m BGL. This is expected to disturb less than 100 m 3 of acidic material in
      total, therefore the total risk associated with the works is very low.

▪     Verification testing for confirmation of effective neutralisation of treated soil is not considered a suitable
      for these works. However, effective treatment should be demonstrated by maintaining records of lime
      delivered and used on site, which shall be maintained by the contractor. It is also recommended that
      photographic evidence of lime treatment be recorded and maintained where lime treatment is
      undertaken.

▪     It is expected that conventional erosion and sediment control measures shall be applied in accordance
      with current industry best practice to contain and control site runoff during construction. This will help to
      mitigate any potential for mobilisation of acidity to ground and surface waters as a result of the works.

▪     Contained site water should be monitored and maintained within a pH range of 6.5 to 8.5.




25 August 2017
Report No. 17265-001-Rev0                                10