ADG Dewatering Management Plan · OPW21/0315

                                                                                        ADG Consulting Pty Ltd


          −    The groundwater associated with indurated sand strata is moderately to highly turbid as a result
               of staining and organic content.
          −    Concentrations of dissolved metals are typically below the available marine water trigger values
               (MWTV’s) provided in ANZECC/ARMCANZ (2000) for the receiving waters, however elevated
               levels of aluminium and particularly iron are expected in the untreated groundwater and have
               the potential to increase following oxidisation of PASS as dewatering progresses or as a result of
               existing acidic groundwater conditions.
          −    Given the location and previous use of the site, groundwater impacts resulting from site
               contamination are not anticipated.
     A groundwater investigation will be undertaken at the commencement of dewatering as described in
     Section 6.5.2 of this report. This assessment will be representative of the groundwater being extracted
     and treated from the entire site, as opposed to localised monitoring well data which is often misleading.
     Based on previous experience with dewatering in the area, ADG expects the groundwater to require
     treatment to increase pH and dissolved oxygen levels, as well as reduce turbidity, suspended sediments
     and dissolved metal concentrations prior to being discharged to the Noosa River.




ADG1290.21 Dewatering Management Plan_Rev0_12.10.21                                                        Page 5