RFI - Acid Sulfate Soils Assessment

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Calile Malouf Investments Pty Ltd                                                               22239-002-Rev1
                                                                                                    6 June 2023


3.0     SITE DESCRIPTION AND PROPOSED DEVELOPMENT
The subject site is described as Lots 10 and 11 on SP195871, covering a combined area of approximately
2.4 hectares with frontage to Serenity Close and Banksia Avenue along the northern/western and eastern
boundaries, respectively. The site is zoned for tourist accommodation and is bounded to the north by high
density residential units and environmental management and conservation reserve to the south.
The site is located on the southerly and south-east facing flanks of an inland dune which crests along
Serenity Close to the north. Ground surface elevations across the site range from RL 9 m to RL 22 m AHD.
The site has been partially cleared in the past, with some minor earthworks and small structures having been
carried out in the past. Any existing structures are expected to be demolished as part of site development.
The site location and contours are shown in Text Figure 1 below.




Text Figure 1: Site location and contours (courtesy of Noosa Council ‘IntraMaps’)

Design drawings showing the proposed building works (Richards + Spence, Project No. 2100004, Drawing
Nos. SD-A-01-01 to 07, dated 22 May 2023), indicate that the proposed development will comprise buildings
ranging between three and four stories, over a single to double level basement carpark. Buildings forming
separate eastern and western wings are proposed, connecting by at grade structures, pathways and
carparking.
Building details have not been supplied at this stage, however we anticipate that the structures will include
concrete framing, on-grade and suspended concrete floors, and masonry retaining walls.
While no earthworks details were available at the time of reporting, provided plans indicate that excavations
for the proposed development will generally range up to about 9 m deep primarily occurring in the more
elevated north-eastern corner. Filling is generally anticipated to be less than 1.5 m high to form final levels,
however some filling up to about 3 m high is proposed along the southern edge of the west wing building.
Based on the proposed development and anticipated earthworks, ground disturbance below an elevation of
RL 5 m AHD will not occur.
Text Figure 2 overleaf provides a layout plan and some cross-sectional views of the proposed development.




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Calile Malouf Investments Pty Ltd                                                          22239-002-Rev1
                                                                                               6 June 2023




                                                    Western Wing Section
Eastern Wing Section
Text Figure 2: Level four layout plan (upper) and some cross-sectional views (lower) of the development,
courtesy of Richards + Spence


4.0     SITE WALKOVER INSPECTION
An inspection of the site was completed by an environmental scientist from Tectonic on 10 January 2023.
The inspection included examining the landscape and vegetation characteristics of the site to determine if
ASS is likely present within the area. No common visual indicators of ASS, such as unconsolidated, organic
or estuarine sediments, wetland-dependent vegetation were observed during the assessment, with the
dominate vegetation typically comprising remnant regrowth. Text Figure 3 below illustrates the general site
conditions at the time of the inspection.




Text Figure 3: Drone ariel image taken during the site assessment




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Calile Malouf Investments Pty Ltd                                                                           22239-002-Rev1
                                                                                                                6 June 2023


5.0         REGIONAL GEOLOGY
Published geological information 1 indicates that the site is underlain by Anthropogenic deposits comprising
“man-made deposits of gravel, sand and silt being generally associated with land-fill or mining” (Ref: Text
Figure 4). This is generally due to the area having been previously developed for residential use. The site is
in proximity to Pleistocene age dune sand deposits which are present to the east, and Holocene age alluvial
deposits which are present in lower areas to the south and west. Based on previous subsurface conditions
encountered during geotechnical investigation, the site is understood to be typically underlain by the dune
sand deposits comprising loose to dense sand, consistent with more elevated areas to the east. Such dune
sand deposits are not typically associated with the formation or presence of ASS.
While some potential exists for ASS to be present in Quaternary age alluvium, which is present to the south
and east of the subject site, proposed works are not likely to significantly disturb soil in these areas or extend
below RL 5 m AHD.




                                                               Subject Site




Text Figure 4: Extract of Laguna Bay Surface 1:100,000 Geology Map


6.0         REGIONAL ASS MAPPING
An extract from the Queensland Government’s Redcliffe to Teewah ASS Map 2 (NR&M-SEA-I-A0 3261)
covering the region is shown in Text Figure 5. Mapping indicates that the site is located above the outer limit
of Holocene/estuarine ASS (i.e. above RL 5 m AHD). The site is therefore characterised as “land with a
low probability of acid sulfate soil occurrence”.




                                                                        Subject Site




Text Figure 5: Maroochy-Caloundra Acid Sulfate Soils Map 2 (NR&M-SEA-I-A0 3331)


1
    Department of Natural Resources, Mines and Energy, 1:100,000 Laguna Bay Surface Geology Map, Sheet 9545, 2018




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Calile Malouf Investments Pty Ltd                                                            22239-002-Rev1
                                                                                                 6 June 2023


7.0     APPLICATION TO NOOSA COUNCIL REGULATION
Development involving ASS must comply with the requirements of state and local regulations pertaining to
ASS. Locally, NC has developed the ASS Overlay Code, and its attendant guidelines, as part of the Noosa
Plan 2020. The purpose of the ASS overlay code is to ensure that the generation or release of acid and
metal contaminants from disturbance of ASS does not have adverse effects on the natural environment,
built environment, infrastructure or human health. This is achieved through compliance with the following
development performance outcomes:
    a) development ensures that the release of acid and associated metal contaminants into the
       environment is avoided by either:
            i.     not disturbing ASS when excavating or otherwise removing soil or sediment, extracting
                   groundwater or filling land; or
           ii.     treating and, if required, undertaking ongoing management of any disturbed ASS and
                   associated drainage waters.
While the site is located within ASS Overlay Code Area 2, being situated between RL 5 m and RL 20 m
AHD, the proposed works will not involve disturbance of soil or groundwater conditions at or below 5 m AHD
and therefore does not have potential to disturb ASS.
Based on our site observations, assessment of the regional geology, published ASS risk mapping proposed
works are not likely to present any significant risk associated with possible ASS disturbance.
The proposed development is therefore deemed to meet performance outcome PO1 of the NC’s ASS
Overlay Code (i.e. development does not disturb ASS).


8.0     RECOMMENDATIONS
Proposed earthworks associated with the development would have a negligible risk of encountering ASS or
affecting groundwater conditions which may impact ASS prone areas. The proposed development may
therefore proceed without need for any further specific ASS or dewatering management measures. No
further site assessment regarding ASS is warranted for the proposed development.


9.0     LIMITATIONS
Your attention is drawn to the document Limitations, which is attached at the end of this report. The
statements presented in this document are intended to advise you of what your realistic expectations of this
report should be, and to present you with recommendations on how to minimise the risks associated with the
services provided by Tectonic for this project.
Please contact the undersigned should you wish to discuss any of the above matters.

Yours faithfully

TECTONIC GEOTECHNICAL PTY LTD




Mark Thomson BSc, CPESC
Senior Environmental Scientist

Attachments:                Limitations




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                                               LIMITATIONS


This document has been prepared for the purpose outlined in Tectonic’s proposal and no responsibility is
accepted for the use of this document, in whole or in part, for any other purpose.

The scope of Tectonic’s Services are as described in Tectonic’s proposal, and are subject to restrictions
and limitations. Tectonic did not perform a complete assessment of all possible conditions or
circumstances that may exist at the site referenced in the report. If a service is not expressly indicated, do
not assume it has been provided. If a matter is not addressed, do not assume that any determination has
been made by Tectonic in regards to it.

Conditions may exist which were undetectable given that economic and time constraints limit the practical
extent of geotechnical investigation. Variations in conditions may occur between investigation locations,
and there may be special conditions pertaining to the site which have not been revealed by the
investigation and which have not therefore been taken into account in the document. Where variations exist
on site, additional studies and actions may be required.

Tectonic’s opinions are based upon information that existed at the time that the work was performed. The
passage of time, man-made or natural events, may alter the site conditions. It is understood that the
Services undertaken allowed Tectonic to form an opinion of the actual conditions of the site at the time the
site was visited and cannot be used to assess the effect of any subsequent changes in the quality of the
site, or its surroundings, or any laws or regulations.

Any assessments made in the preparation of this document are based on the conditions indicated from
published sources and the findings of the investigation described. Actual subsurface conditions may differ
from those indicated in the document (e.g. between boreholes or test pits). No warranty is included, either
express or implied, that the actual conditions will conform exactly to the assessments contained in this
document.

Where data supplied by the client or other external sources, including previous site investigation data, have
been used, it has been assumed that the information is correct unless otherwise stated. No responsibility is
accepted by Tectonic for incomplete or inaccurate data supplied by others.

This document is provided for the sole use by the Client and its professional advisers. No responsibility
whatsoever for the contents of this document will be accepted to any person other than the Client. Any use
which a third party makes of this document, or any reliance on or decisions to be made based on it, is the
responsibility of such third parties. Tectonic accepts no responsibility for damages, if any, suffered by any
third party as a result of decisions made or actions based on this document.




Rev 1 (March 2016)