REFERENCE DOCUMENTS - RAL25/0004 (As Published)

        9.          ASSESSMENT OF SITE CONTAMINATION RELATED RISK

        9.1.1.      AEC 1 – NORTHERN NIGHT SOIL AND BOTTLES DISPOSAL AREA
                    The assessment confirms that the historical disposal of night soil and bottles, ceramics and possibly other
                    inert materials has occurred in this area. A reported concentrated night soil metal can burial area has not
                    been identified to date.
                    The fill profile within the northern night soil and bottles disposal area is not immediately evident and can
                    appear as a natural soil horizon. However, the presence to date of mostly infrequent inert wastes
                    indicates a fill depth of around 1mbgl within trenches.
                    The chemical composition of the fill does have some elevated heavy metals but, within the limitations of
                    the assessment, does not indicate the presence of any additional broad and widespread chemical
                    contamination noting some elevated impacts at locations TP27 and TP75.

        9.1.2.      AEC 2 – SOUTHERN RUBBISH DISPOSAL AREA
                    The assessment confirms that the historical disposal of general rubbish has occurred in this area.
                    The fill profile within the southern rubbish disposal area is generally able to be readily identified due to
                    differences in soil properties and presence of waste materials.
                    The fill depth ranged from around 0.1 to 0.6mbgl with an average of 0.35mbgl although deeper
                    occurrences may be present associated with the infilling of any deeper natural depressions or constructed
                    pits.
                    Various exceedances of ecological and human health criteria are associated with heavy metals present
                    within the fill, as well as the presence of general wastes and asbestos materials. Some results exceed
                    those for public open space usage.
                    It is likely that this impact also extends under the building platform housing the shed and office.

        9.1.3.      LEACHATES
                    Whilst heavy metals do not appear to be leaching into underlying natural soils at any level of concern, the
                    total concentration and waste classification results for some metals exceed general landfill disposal
                    criteria where fill material that is interspersed with the more concentrated wastes over both AEC. This
                    does not immediately necessitate alternate disposal options but will require consideration for remediation
                    planning. Most options for on or off-site management or disposal remain valid for the bulk of the material
                    requiring remediation to progress EMR removal.

        9.1.4.      LANDFILL GAS
                    DSI 1 field screening occurred when soil pore spaces would likely have been saturated due to monsoonal
                    conditions experienced during the works. This means there was potential for any LFG to be suppressed
                    and not detected during the DSI 1 monitoring. However, additional LFG assessment was undertaken
                    during DSI 2 works including installation and monitoring of 7 LFG bores as well as within the 4
                    groundwater bores that indicate LFG generation is unlikely to be a current concern for the site, however,
                    an additional monitoring round is recommended in Spring.




        125 Lot 105 SP118458 Cooroy DSI 12062024 Rev0                                                 Lot 105 SP118458, Cooroy, QLD, 4563
        12/06/2024                                                    75                           Detailed Site Contamination Investigation
Document Set ID: 23717062
Version: 0, Version Date: 01/01/1900