RFI - Acid Sulfate Soils Assessment

6 June 2023                                                                         Project No. 22239-002-Rev1



Calile Malouf Investments Pty Ltd
Attention: Mr Michael Malouf

Email: [email protected]


ACID SULFATE SOIL ASSESSMENT FOR PROPOSED HOTEL DEVELOPMENT
3-7 SERENITY CLOSE, NOOSA HEADS


Dear Michael,


1.0     INTRODUCTION
Tectonic has undertaken an acid sulfate soil (ASS) assessment for the proposed hotel development at 3-7
Serenity Close, Noosa Heads. This letter presents the results of our assessment taking into consideration
State guidelines and Noosa Council (SCC) requirements pertaining to ASS.
In summary, while the some nearby local geology does include Quaternary age alluvium with potential to
contain ASS, proposed site development will not involve disturbance of these units or any soil below an
elevation of RL 5 m AHD. Therefore, excavations associated with the proposed development will not
disturb or impact soil profiles associated with the formation or occurrence of ASS. This position is
supported by published ASS risk mapping and conforms with performance outcome PO1 of the NC’s ASS
Overlay Code (i.e. development does not disturb ASS).
No further site assessment or specific management measures regarding ASS are warranted for the
proposed works.


2.0     INFORMATION ON ACID SULFATE SOIL
ASS is common in low-lying coastal areas of Queensland, typically in Holocene to Pleistocene age alluvial
sediments located below RL 5 m AHD. Such areas are often characterised by the presence of estuaries,
swamps, floodplains, salt marshes and mangroves, primarily occurring in estuarine based alluvial soil.
ASS affected soils contain iron sulfides, most frequently pyrite, which, when exposed to air can oxidise to
form sulfuric acid. Existing acidity attributed to the historic oxidation of iron sulfides may also be present
because of previous exposure of ASS material either by human interference or by natural processes.
When these soils are maintained in their natural setting (generally anaerobic conditions below the
groundwater table or sea level), the iron sulfides are unable to oxidise, therefore the ASS remains in a stable
state, and in equilibrium with the surrounding environment. However, where disturbances such as civil
construction or development expose ASS to aerobic conditions, the iron sulfides are able to oxidise and form
sulfuric acid, resulting in the soil becoming acidic.
The resulting creation of large volumes of acidity can occur rapidly, resulting in significant impacts to local
waterways, sensitive terrestrial environments, or in extreme cases, public health.




                                              Tectonic Geotechnical Pty Ltd
                                              PO Box 899, Buderim, QLD 4556
                                                   Office: 07 5478 9016
                                                 www.tectonicgeo.com.au
                                                   A.B.N. 83 165 727 828