Reference Document - Acid Sulfate Soil Report 11_2023- OPW23_0189 · OPW26/0094

                  Project No. PG-10899                                                                                                        Page | 2
                  November 2023
                  Ref: PG-10899, 2023-10-16, ASSMP VER 2
                  DD Sunnyside CD Sunnyside Pty Ltd – Acid Sulfate Soil Management Plan – Proposed Residence, 30 Mossman Court, Noosa Heads




                  Tasks/Actions                        Investigations of ASS to date have targeted soils to a maximum
                                                       depth of 4.0m below the existing ground level. Zones of materials
                                                       with nett acidity above the action criteria have been identified
                                                       over the site at depths greater than 3m below ground level. The
                                                       materials to a depth of approximately 3.0m have been shown by
                                                       testing to not contain acid sulfate. If material below 3m is disturbed
                                                       they will require lime treatment to neutralize acidity.

                                                       In order to assess potential impacts and treatment requirements for
                                                       ASS, the Earthworks Contractor shall prepare an earthworks
                                                       schedule for the proposed construction activities prior to
                                                       commencement of the construction and earthworks activities.
                                                       ASS Treatment:
                                                       The spoil to be removed from site will either be treated onsite prior
                                                       to removal, or:
                                                       • treated on-site in accordance with the procedures given below;
                                                           or
                                                             −   A temporary stockpile and treatment area will be
                                                                 established where all excavated material may be
                                                                 conditioned (dried) and lime treated, for subsequent use for
                                                                 site landscaping or general fill requirements.
                                                             − Bunding will be constructed around the perimeter of the
                                                                 designated ASS treatment pad to intersect and contain run-
                                                                 off from the pad during the soil treatment operations.
                                                             − A suitably sized drain or temporary retention basin will be
                                                                 constructed to collect drainage water from the treatment
                                                                 pad in the vent of heavy rainfall during the construction
                                                                 period. This will be constructed in a manner to protect
                                                                 water quality in adjacent waterways.
                                                             − Alternatively, the basement excavation can be used as a
                                                                 treatment platform with drainage water or run-off collected
                                                                 in the retention basin will be tested to determine the quality
                                                                 of the water.        If the water quality falls outside the
                                                                 performance indicators (described below), the water will
                                                                 be treated prior to discharge from the site.
                                                             − The excavated spoil will be spread out in a designated
                                                                 treatment area in layers up to 0.25m loose thickness. Aglime
                                                                 with a neutralising value of 100% will be applied evenly over
                                                                 the surface and thoroughly blended into the spoil at a
                                                                 uniform minimum rate of 4kg (CaC0 3 )/m3.
                                                             − When incorporation of the lime is complete, Chromium Suite
                                                                 validation testing of the treated spoil will be carried out to
                                                                 establish that sufficient lime has been added (and uniformly
                                                                 mixed) to neutralise the acid generation potential of the
                                                                 spoil. The validation test will be deemed to have passed if
                                                                 the net acidity is 18 mol H+/t. A higher result will require the
                                                                 application of additional lime, until a satisfactory validation
                                                                 result has been achieved.
                                                             − Once lime treatment is complete, the treated spoil will be
                                                                 removed from site or may then be stockpiled for later use
                                                                 for landscaping or for general site fill requirements.
                                                             − Selection of the most appropriate test methods and
                                                                 determination of liming requirements for neutralisation will
                                                                 be the responsibility of the ASS Consultant.
                                                       •     Treated at an off-site facility in accordance with the approved
                                                             ASSMP for the facility.




Document Set ID: 22828362
Version: 1, Version Date: 26/02/2024