Reference Document - OPW23 0189

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.