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

                                                                                                                     ADG Consulting Pty Ltd


                      1        Introduction
                               ADG Consulting Pty Ltd (ADG) was engaged by David & Craig Dodd care of SCG Consulting Engineers (SCG)
                               to prepare a Dewatering Management Plan (DMP) for the proposed residential development within
                               property described as Lot 149 on N21859, situated at 30 Mossman Court, Noosa Heads, Queensland.
                      1.1      Proposed development
                               The proposed development comprises the construction of a two‐storey residential building overlying a
                               single level in‐ground basement on the 610 m2 site. The supplied information indicates that excavations
                               will extend to a maximum depth of approximately 2.4 m below ground level (bgl; existing), corresponding
                               to a maximum excavation elevation of approximately RL ‐0.7 m AHD (assuming 400 mm basement slab
                               thickness). Localised deeper excavations may be required to facilitate other structural elements (i.e. pile
                               caps and footings), where required.

                               Groundwater depths have not yet been assessed, and it is understood that a geotechnical and acid sulfate
                               soil investigation for the site is planned in the near future and could be used to update the DMP with site
                               specific details at a later date, if required. Groundwater seepage was recorded at 1.6 m below ground
                               level (approx. 0.5 m AHD) during preliminary geotechnical works (drilling) on a neighbouring site by
                               Douglas Partners (2021). Standing groundwater levels are therefore conservatively expected to occur at
                               an approximate elevation of around RL 1.0 m AHD.

                               These conditions and the sites’ proximity to the adjacent Noosa canal (tidally connected part of Noosa
                               River catchment) suggest that dewatering of the site will be necessary to allow the basement to be
                               constructed in dry conditions. Based off information provided by SCG and ADG’s experience in the local
                               area, it is noted that acid sulfate soil conditions are likely to be present, which has the potential to affect
                               water quality during construction dewatering.
                      1.2      Relevant guidelines
                               The DMP was prepared with reference to the following documents:
                                    Australian and New Zealand Guidelines for Fresh and Marine Water Quality. 2018. Australian and
                                     New Zealand Governments and Australian state and territory governments (ANZG), Canberra ACT,
                                     Australia.
                                    Australian and New Zealand Guidelines for Fresh and Marine Water Quality. 2000. Australian and
                                     New Zealand Environment and Conservation Council and Agriculture and Resource Management
                                     Council of Australia and New Zealand (ANZECC/ARMCANZ).
                                    Environmental Protection (Water & Wetland Biodiversity) Policy 2019. Department of Environment
                                     and Science (DES), Queensland Government.
                                    Noosa River environmental values and water quality objectives. 2022. Department of Environment
                                     and Science (DES), Queensland Government.
                                    Guidelines for Managing Risks in Recreational Water. 2018. Australian Government, National Health
                                     and Medical Research Council (NHMRC).
                                    Monitoring and Sampling Manual 2018, Version 2 June 2018. 2018. Department of Environment
                                     and Science (DES).
                                    Queensland Water Quality Guidelines 2009, Version 3. 2013. The Department of Environment and
                                     Heritage Protection (DEHP).
                      1.3      General environmental duty
                               The Environmental Protection Act 1994 describes that all persons in Queensland have a “General
                               Environmental Duty” and that “a person must not carry out an activity that causes, or is likely to cause
                               environmental harm unless the person takes all reasonable and practicable measures to prevent or
                               minimise the harm”.




                          ADG1580.23 Dewatering Management Plan_Rev0_28.09.23                                                           Page 1




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