Original source · versioned page text
25289-001-Rev0 - The Esplanade (1)-compressed
Geotechnical investigation
Proposed Residence - 17 The Esplanade, Sunshine Beach
Geotechnical investigation 19 November 2025 | Ref. 25289-001-Rev0
19 November 2025 | 25289-001-Rev0
See the original
The page text is free to read. Viewing or downloading an original file needs an account.
Log in to see the originalLog in to download the original file
The download may take up to a minute.
Full text of the other 44 pages
Page 2
Document Review
Doc No. Revision Prepared By Reviewed By Date Issued
001 0 Oliver De Silva Ashley Davey 19 November 2025
Doc No. Revision Method of Delivery Issued To
001 0 Electronic Tiani Boulton
([email protected])
Prepared By Reviewed By
Oliver De Silva BAppSc PMEG Ashley Davey BEng (Geological) RPEQ 8159
Engineering Geologist Director/Principal Geotechnical Engineer
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 i
Page 3
Executive Summary This report details the results of a geotechnical investigation undertaken for a proposed residential development at 17 The Esplanade, Sunshine Beach. Preliminary architectural drawings indicate that the development will consist of the construction of a three-level structure, which includes a single level basement. The boreholes and in situ test results indicate a subsurface profile of relatively poorly graded dune sands to the maximum investigation depth of 6.9 m below ground level (BGL). Very loose to loose sands were deepest in borehole BH2, extending to 2.4 m BGL, overlying medium dense sand to depths of 5 m BGL, with underlying dense (or denser) sands. The other borehole and DCP tests indicated shallower transitions to both medium dense and dense sands. Slope stability modelling was carried out considering short-term erosion from a 100 year average recurrence interval extreme storm event (as nominated by the appointed coastal engineering experts, Moffat & Nichol (M&N)); and anticipated regression of the dune over time. The M&N assessment indicated that a large portion of the high dune face would be affected by such a future erosion event, extending approximately 17 m laterally into the dune face; with a localised scarp crest at around RL 23 m AHD. The erosion cut was shown to extend to within 13 m of the subject site’s eastern boundary. Subsequent regressive failures of the erosion profile would then be expected to occur, until the dune face reached a slope angle of about 27°, which could encroach by about 7 m into the subject site. The property is situated on the western side of The Esplanade road reserve, which acts as a buffer between the beach, dune slope and the site. As a result, maintaining the integrity of the road reserve would, in turn, help protect the property. Since the road reserve is owned and managed by Noosa Council (NC), it is anticipated that NC would prioritise its protection before any erosion progresses beyond the reserve and reaches the site. However, if NC determines that the property requires its own protective measures, a shear pile wall would need to be constructed along the eastern boundary. Given our understanding of the ground conditions and the predicted future slope geomorphology, a shear pile wall founded at depth into the dense (or denser) sands may be required to protect the site from coastal erosion. Subject to detailed design, secant or contiguous shear piles, possibly with additional structural support (e.g. raked piles, ground anchors), would be required to cater for the anticipated ‘upstand’ of about 5 m following future erosion (as indicated by our analysis). The shear piles would likely need to be at least 12 m deep BGL. Protection against erosion and adverse interaction with adjacent properties would also be required. This could consist of a grout curtain extending from the eastern boundary at least 8 m westward along the northern and southern boundaries. The following additional recommendations are provided for the proposed development: The proposed residence and any ancillary structures must be supported by footings founded at least 1 m into natural medium dense (or denser) sands. In the areas of deeper cut (i.e. the basement level), high level footings may be adopted. Elsewhere, piles will be required. Excavations close to site boundaries may necessitate the installation of temporary shoring. Ground vibrations during construction must be minimised and monitored. Where excessive vibrations occur, alterations to construction techniques may be required. It is recommended that a dilapidation survey of adjoining structures be completed prior to construction. Collected roof water should be directed by pipes to the council stormwater system along The Esplanade. Hydraulic design should be such that under no circumstances are uncontrolled stormwater flows permitted over the dune face. Geotechnical investigation 19 November 2025 | 25289-001-Rev0 ii
Page 4
Contents
1. Introduction ............................................................................................................................................................ 1
2. Proposed Development ....................................................................................................................................... 1
3. Method of Investigation ......................................................................................................................................3
3.1 Fieldwork ...................................................................................................................................................................... 3
3.2 Geotechnical Laboratory Testing ........................................................................................................................ 3
4. Results of Investigation ...................................................................................................................................... 4
4.1 Site Description ......................................................................................................................................................... 4
4.2 Topography................................................................................................................................................................. 6
4.3 Geology ........................................................................................................................................................................ 7
4.4 Subsurface Conditions ............................................................................................................................................ 8
4.5 Groundwater............................................................................................................................................................... 8
4.6 Geotechnical Laboratory Test Results ............................................................................................................... 9
4.7 Surface Drainage ....................................................................................................................................................... 9
5. Slope Stability Assessment ............................................................................................................................... 10
5.1 Existing Conditions................................................................................................................................................. 10
5.2 Stability Assessment .............................................................................................................................................. 10
5.2.1 Quantitative Assessment .................................................................................................................... 13
6. Geotechnical Recommendations ..................................................................................................................... 16
6.1 Earthworks ................................................................................................................................................................. 17
6.1.1 Site Preparation and Trafficability................................................................................................... 17
6.1.2 Excavations .............................................................................................................................................. 18
6.1.3 Filling ......................................................................................................................................................... 18
6.2 Building Foundations ............................................................................................................................................ 19
6.2.1 Indicative Site Classification .............................................................................................................. 19
6.2.2 Footing Design....................................................................................................................................... 19
6.3 Temporary and Permanent Retention ............................................................................................................ 20
6.4 Drainage ..................................................................................................................................................................... 22
7. Conclusion ............................................................................................................................................................ 22
8. Limitations ............................................................................................................................................................ 22
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 iii
Page 5
Tables
Table 1: Summary of Subsurface Profiles ................................................................................................................................ 8
Table 2: Stability Risk Levels ....................................................................................................................................................... 11
Table 3: Details of Qualitative Risk Assessment for Property (AGS 2007) ................................................................ 12
Table 4: Soil Parameters Adopted for Slope/W Analyses ............................................................................................... 14
Table 5: Slope/W Analysis Results ........................................................................................................................................... 14
Table 6: Retaining Structure Design Parameters ................................................................................................................ 21
Text Figures
Text Figure 1: Proposed layout plan (upper), elevations (middle) and sections (lower), courtesy of
ADG............................................................................................................................................................................................ 2
Text Figure 2: Aerial image of the site and immediate surrounds (courtesy Nearmap, 25 August
2025) .......................................................................................................................................................................................... 4
Text Figure 3: Oblique drone image of the site and surrounds, looking north ........................................................ 5
Text Figure 4: Oblique drone image of the site, looking west ........................................................................................ 5
Text Figure 5: Oblique drone image of the site, looking east ......................................................................................... 6
Text Figure 6: Site plan showing ground surface contours (courtesy Noosa Council [NC] ‘Intramaps’) ........ 7
Text Figure 7: Extract of Laguna Bay 1:100,000 Scale Surface Geology map ............................................................ 7
Text Figure 8: Extract from NC landslide hazard overlay mapping ............................................................................. 10
Text Figure 9: Slope/W Output – Case 1 ............................................................................................................................... 15
Text Figure 10: Slope/W Output – Case 2 ............................................................................................................................. 15
Text Figure 11: Zone of influence diagrams – footings to be founded below these lines ................................. 20
Figures
Figure 1: Site Plan
Figure 2: Section A-A’
Appendices
Appendix A Borehole/DCP Reports & Explanatory Notes
Appendix B Laboratory Test Certificate
Appendix C Extracts from AGS Guidelines (2007)
Appendix D Limitations
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 iv
Page 6
1. Introduction This report details results of a geotechnical investigation undertaken for a proposed residential development at 17 The Esplanade, Sunshine Beach. The investigation was carried out by Tectonic for Christian Seymour, in accordance with our Proposal P25454-Rev0 dated 8 September 2025. Adapt Planning are the town planners for the development. Moffat & Nichol (M&N) are the coastal engineers for the project and have provided a coastal erosion ‘cut’ profile which could affect the subject site. The geotechnical investigation comprised the drilling of two boreholes using hand auger equipment, located at the eastern property boundary and in the western part of the site. In situ dynamic cone penetrometer (DCP) testing was also conducted adjacent to and within the boreholes, and at three stand-alone locations. Geotechnical laboratory testing was undertaken on one select soil sample. This report presents the results of the geotechnical investigation and slope stability modelling, to address possible slope instability following coastal erosion from a hypothetical future sea surge/storm event assessed by M&N, along with geotechnical recommendations for the proposed development in general. 2. Proposed Development Architectural drawings prepared by Aboda Design Group (Ref. ADG, Project No. NSS032, Dwg. Nos. WD.101 to WD.603 [not inclusive], Rev A, dated 27 June 2025) indicate that a three-storey residence is proposed. The basement level would be ‘dug in’ to the slope, ‘daylighting’ to the east and being completely below ground to the west (~3.5 m below existing ground levels). A full central level would be present above, with a partial third level, allowing for open, elevated courtyard and terraces. Building construction is shown to consist of suspended concrete floors, concrete and masonry walls, full height glazed facades and some lighter weight cladding in select locations. A below ground pool would be constructed along the northern side of the allotment, with the floor of the pool shell being up to about 3 m below existing ground levels. In order to construct the basement level of the residence (and the pool), earthworks will be required comprising excavations of up to about 4 m depth, with some possible minor filling of up to about 0.5 m high to form platforms for slab edges and general landscaping. Deeper excavations may be required for underground services and footings. Extracts from the proposed development plans are illustrated in Text Figures 1 overleaf. Geotechnical investigation 19 November 2025 | 25289-001-Rev0 1
Page 7
Text Figure 1: Proposed layout plan (upper), elevations (middle) and sections (lower), courtesy of ADG Geotechnical investigation 19 November 2025 | 25289-001-Rev0 2
Page 8
3. Method of Investigation 3.1 Fieldwork An experienced geotechnical engineer from Tectonic undertook a site walk-over survey on 24 September 2025 to visually assess indicators of past slope instability. The walk-over included assessment of soil exposures, surface drainage conditions, topography, evidence of erosion or past instability, and vegetation coverage/condition. In conjunction with the walk-over survey, two hand auger boreholes (designated BH1 and BH2) were drilled. Borehole BH1 was drilled within the garden bed along the eastern boundary of the site, whilst borehole BH2 was drilled within the proposed building footprint in the western part of the site. In situ testing utilising the DCP method was completed from surface adjacent to each borehole, and at selected downhole depths. In addition, three standalone DCP tests were conducted, from near the crest of the sand dune and further down the dune face, extending to depths of between 2.1 m and 2.9 m below ground level (BGL). Hand augers were taken to practical refusal at depths of between 3 m and 4 m BGL, with DCP testing extending below the bases of the boreholes to depths of up to 6.9 m BGL. Boreholes were backfilled with drilling spoil and left slightly mounded at the ground surface. Disturbed soil samples were recovered from the auger cuttings. The engineer was responsible for logging soil profiles and maintaining investigation practices in accordance with AS1726 Geotechnical site investigations, supervising in situ testing, and recovering samples. Borehole and DCP reports are attached in Appendix A, together with explanatory notes. Test locations are shown in Figure 1 and subsurface conditions are discussed in Section 4.4. 3.2 Geotechnical Laboratory Testing One selected disturbed soil sample from borehole BH1 was dispatched to a NATA accredited laboratory for geotechnical testing, which comprised a particle size distribution (PSD) test for soil classification purposes. Geotechnical laboratory testing was undertaken in accordance with Australian Standard AS1289 Method for Testing Soils for Engineering Purposes. Laboratory test results are summarised in Section 4.6, and the test certificate is attached in Appendix B. Geotechnical investigation 19 November 2025 | 25289-001-Rev0 3
Page 9
4. Results of Investigation
4.1 Site Description
The site is formally described as Lot 678 on RP48111, covering an area of about 505 m2, with frontage to
the southern extent of The Esplanade along the eastern boundary. At the time of the investigation, an
existing residence occupied the majority of the site, with a swimming pool and garden area in the north-
western part.
The site was accessed via a concrete driveway sloping up from the roadway to the east, which then
entered the site at a level grade. The existing residence (to be demolished) was a three-storey, rendered
blockwork structure, with the ground level terraced into the slope to the west. A survey plan supplied to
us indicates that a water main runs adjacent to the eastern boundary of the property, and a sewer
reticulation main crosses the south-eastern corner of the block.
Blockwork retaining walls, ranging up to about 1.7 m high, retained cuts for the lower level of the
residence along the northern and southern sides.
Some minor (mostly ‘hairline’) cracking was noted in various parts of the rendered structures across the
site. Otherwise, the residence and other structures around the garden areas appeared to be in relatively
good condition, based on a visual exterior assessment, with no signs of structural distress caused by
global slope instability.
A 2025 aerial image of the site and surrounds is shown in Text Figure 2 below.
Subject site
Sunshine Beach
Text Figure 2: Aerial image of the site and immediate surrounds (courtesy Nearmap, 25 August 2025)
Site conditions at the time of our investigation are shown in Text Figures 3 to 5 on the following pages.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 4
Page 10
Residence on The Esplanade
subject site
Main dune
Smaller frontal dune
Text Figure 3: Oblique drone image of the site and surrounds, looking north
Residence on
subject site
Main dune
Smaller frontal dune
Text Figure 4: Oblique drone image of the site, looking west
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 5
Page 11
Minor cracking noted in
rendered structures
Text Figure 5: Oblique drone image of the site, looking east
4.2 Topography
During our site walk-over, topographic features specific to the site were noted, and ground slopes were
recorded using a hand-held clinometer. As illustrated in Text Figure 6 overleaf, the site is located just
above the crest, and over the upper face, of the high dune backing Sunshine Beach. The stoss face of the
dune is generally eastward facing at the site location.
The inferred natural ground slope was generally consistent through the site, at about 8° to the east.
However, the site had been altered by historic cut and fill earthworks associated with construction of the
existing residence, which had formed level areas connected via stairs and retaining walls. In the area
immediately to the east of the site, along the road area, the ground was near flat and appeared to have
been formed by filling works estimated to be up to 1 m in height. Approximately 3 m to the south-east
of the property boundary, this fill was retained by a 0.6 m high timber sleeper retaining wall in poor
condition. The remainder of the abovementioned fill, which formed a near level area extending between
5 m and 10 m east of the site, was graded down to the natural slope. This then transitioned to the top of
the dune slope, with a prominent break in slope over the main dune face which had an overall gradient
of around 30°. At about midway down the dune slope, the slope angle increased to between 30° and 37°,
but was still generally planar in shape.
At the toe of the high dune a trough was present, of around 5 m width. The frontal dune running along
the back of the main beach area was about 1 m height and undulating. Beyond this, the beach dropped
down from about RL 3 m AHD to the shoreline (around RL 0 m AHD).
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 6
Page 12
A selection of the geomorphological features described above are denoted on Text Figures 3 to 5 on the
preceding pages.
Subject site
Text Figure 6: Site plan showing ground surface contours (courtesy Noosa Council [NC] ‘Intramaps’)
4.3 Geology
Available geological information 1 indicates that the site is underlain by Holocene age quartz dune sand
(described as “parabolic dunes”, Ref. extract in Text Figure 7 below).
Approx. site location
Text Figure 7: Extract of Laguna Bay 1:100,000 Scale Surface Geology map
1
Queensland Government, Dept. of Natural Resources, Mines and Energy, 1:100,000 Laguna Bay Surface Geology, Sheet 9545, 2018
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 7
Page 13
4.4 Subsurface Conditions
Detailed descriptions of the subsurface conditions encountered in the boreholes are provided in the
borehole reports attached in Appendix A, along with definition sheets which describe terms and
abbreviations used in the reports. Subsurface conditions encountered in the boreholes are summarised
below and are illustrated as a cross-section in Figure 2 (attached at the end of report text).
The subsurface conditions encountered in the boreholes surrounding the existing residence comprised
initially loose clayey and silty sand fill to depths of 0.4 m and 0.5 m BGL in boreholes BH1 and BH2,
respectively. Then, very loose to loose natural sands were encountered to depths of 0.4 m and 2.4 m in
boreholes BH1 and BH2, respectively. Below this in borehole BH1, medium dense sand was encountered
to a depth of 1.2 m BGL, overlying dense (or denser) sand to the borehole termination depth of 4 m BGL.
In borehole BH2, medium dense sand was encountered to the borehole termination depth of 3 m BGL,
with downhole DCP testing indicating the presence of dense sand below 6.5 m BGL.
Standalone DCP testing undertaken across the dune to the east of the site indicated loose natural sand
to depths of 1.3 m to 1.8 m BGL, then becoming medium dense to depths of 1.9 m to 2 m BGL, overlying
dense (or denser) sand to the DCP termination depths.
Table 1 below provides a detailed summary the subsurface profiles encountered in each borehole and
standalone DCP test (presented left to right from west to east direction, western boundary of site to high
foredune toe).
Table 1: Summary of Subsurface Profiles
Material / Test Location BH2 BH1 DCP1 DCP2 DCP3
Loose Sand Fill 0.0 – 0.5 0.0 – 0.4 NE NE NE
Very Loose to Loose 0.5 – 2.4 0.4 – 0.4 *0.0 – 1.4 *0.0 – 1.9 *0.0 – 1.5
Natural Sands
Medium Dense Natural 2.4 – 5.0* 0.4 – 1.2 *1.4 – 2.0 *1.9 – 2.1 *1.5 – 2.0
Sands
Dense (or denser) *5.0 – 6.9TD 1.2 – 4.2R *2.0 – 2.9TD *2.1 – 2.2R *2.0 – 2.3R
Natural Sands
Notes:
1. Depths noted in m BGL at time of investigation (24 September 2025)
2. NE Denotes not encountered
3. * denotes materials inferred from DCP results
4. TD denotes DCP test termination depth
5. R denotes DCP refusal
4.5 Groundwater
No signs of groundwater seepage (‘springs’) were observed at the ground surface during our walk-over
and no groundwater was encountered in the boreholes. It is expected that an unconfined groundwater
table would exist below the toe of the dune, close to sea level, and fluctuate with tidal and weather
conditions. The groundwater level is anticipated to rise slightly under the dune moving west.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 8
Page 14
Groundwater seepage may develop at shallower depths, particularly following periods of prolonged or heavy rainfall at various levels through the dune profile, possibly being ‘perched’ of zones of indurated sand that may exist. Based upon experience at other similar sites in the area, such seepage would be expected to be transient and of relatively minor lateral extent. 4.6 Geotechnical Laboratory Test Results PSD analysis on one natural sand sample selected from borehole BH1 indicated that the soil generally comprised poorly graded, fine to medium grained sand, that was relatively ‘clean’ (1% trace silt). Full test results (laboratory certificate) are presented in Appendix B. 4.7 Surface Drainage Surface drainage would be expected to follow natural surface contours to the east towards the beach. The site has a relatively small catchment, with the majority of upslope run-off expected to be intercepted by the neighbouring property or the roadside drainage along Stevens Street to the west. Given the sandy nature of the site, rainfall would normally be anticipated to infiltrate the ground surface relatively quickly. However, as the proposed development will occupy the majority of the block, significant run-off from hard surfaces will occur. Nevertheless, where directed into swales rather than pipes, such run-off would be expected to infiltrate into the natural sands relatively rapidly. No significant surface water run-off features were noted across the allotment or adjacent dune face during our assessment (e.g. scour/wash out scars). Geotechnical investigation 19 November 2025 | 25289-001-Rev0 9
Page 15
5. Slope Stability Assessment
5.1 Existing Conditions
The Noosa Planning Scheme 2020 includes a landslide hazard overlay map (Ref. extract in Text Figure 8)
which indicates that the eastern edge of the site, and steeper dune face to the east, have been mapped
as Moderate and High Hazard areas, respectively.
Subject site
Text Figure 8: Extract from NC landslide hazard overlay mapping
It should be noted that the NC landslide hazard mapping is a broad-scale indication of the potential
landslide susceptibility and is superseded by this site-specific assessment. The allotment and adjacent
dune face did not exhibit any visible surface features which would indicate larger scale global slope
instability during our walk-over. No landslide back scarps, noteworthy groundwater seepage or areas of
naturally ‘hummocky’ ground were observed. Medium dense sands were encountered at relatively
shallow depths below surface down the dune face, with the dune standing at around 30° overall.
Generally, sand dune slopes are close to the ‘limit of equilibrium’ where the surface gradient is about 30°,
although often lower (26˚ to 28˚) for very loose sands (as were indicated to be present down the dune in
DCP1 to DCP3 to depths of up to 1.9 m BGL). The limit of equilibrium is the ‘tipping point’ to instability,
where the factor of safety (FOS) of the slope is approximately 1.0. The FOS of a slope is the balance (ratio)
between the forces driving instability (e.g. soil weight, groundwater pressure) and the resisting forces (e.g.
soil friction and cohesion).
5.2 Stability Assessment
The risk assessment for this project has been carried out following AGS 2007 Practice Note Guidelines for
Landslide Risk Management. Relative levels of risk and their implications are given in Table 2 on the
following page.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 10
Page 16
Table 2: Stability Risk Levels
Risk Level Example Implications(1)
VH Very High Risk Unacceptable without treatment. Extensive detailed investigation and research, planning and
implementation of treatment options essential to reduce risk to Low; may be too expensive and
not practical. Work likely to cost more than value of property.
H High Risk Unacceptable without treatment. Detailed investigation, planning and implementation of
treatment options required to reduce risk to Low. Work would cost a substantial sum in relation
to the value of the property.
M Moderate Risk May be tolerated in certain circumstances (subject to regulators’ approval) but requires
investigation, planning and implementation of treatment options to reduce risk to Low.
Treatment options to reduce to Low risk should be implemented as soon as practicable.
L Low Risk Usually acceptable to regulators. Where treatment has been required to reduce the risk to this
level, ongoing maintenance required.
VL Very Low Risk Acceptable. Manage by normal slope maintenance procedures.
Note: (1) The implications for a particular situation are to be determined by all parties to the risk assessment and may depend
on the nature of the property at risk; these are only given as a general guide.
Considering the existing site conditions (Ref. Section 2), and subject to the implementation of
recommendations given below, it is assessed that there should be a Low Risk of global slope instability
affecting the proposed development. Regulators (NC) normally require that a Very Low or Low Risk of
landslide affecting the property must be demonstrated to enable development approval.
Summarised in Table 3 overleaf is our qualitative assessment of landslide risk for the development site. A
summary of qualitative terminology for use in assessing risk to property is attached (taken from AGS
2007).
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 11
Page 17
Table 3: Details of Qualitative Risk Assessment for Property (AGS 2007)
Hazard Likelihood Consequence Assessed Risk Comments
Given the low natural gradients through the
Failure through very proposed building areas and retention
loose to loose natural system proposed, it is considered Unlikely
sands and sand fill that a landslide in these materials would
Unlikely Medium Low
above the foundation affect the proposed development. For a
depth in future potential Medium impact from such
building areas instability the resultant risk would be Low as
per AGS 2007.
The likelihood of a deep failure through the
medium dense (or denser) natural sand
below the proposed foundation depth is
Deep failure through assessed as Rare due to the lack of
the medium dense (or precedence of such movements locally, no
Rare Major Low
denser) sands below signs of any existing slope instability and a
the foundation depth lack of groundwater. Although the
consequence of such a failure would be
Major, the resultant risk is Low as per AGS
2007.
The likelihood of failure of a temporary
retention system, if required as outlined in
Section 6.3, is assessed as Unlikely, subject
Instability of
to detailed design by a suitably qualified
temporary shoring
RPEQ engineer, which accounts for the
system (if required), as Unlikely Medium Low
required factors of safety against slope
discussed in
instability, and construction by a specialist
Section 6.3.
contractor. Although the consequence of
such a failure could be Medium, the
resultant risk is Low as per AGS2007.
While the modelling indicates it is Possible
that an extreme erosion event could affect
the site, the likelihood of a landslide
Retrogressive failure
extending through the future piled wall
of the high foredune
system along the eastern edge of the site
face considering
boundary as outlined in Section 6 is assessed
potential future
as Rare, subject to detailed design by a
erosion from a Rare Major Low
suitably qualified RPEQ engineer,
hypothetical storm
construction by a specialist contractor, and
and wave scenario,
considering the results of our quantitative
impacting the subject
slope stability analysis outlined in Section
site.
5.2.1. Although the consequence of such a
failure would be Major, the resultant risk is
Low as per AGS2007.
The potential impacts on slope stability of the development components have been assessed, and the
measures recommended below in Section 6 have been designed to mitigate those impacts.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 12
Page 18
5.2.1 Quantitative Assessment
In order to estimate the factor of safety (FOS) against slope instability for the proposed development,
numerical analysis has been conducted using Slope/W. The ground surface profile has been modelled
using a combination of architectural layout drawings and slope angles measured in the field by Tectonic.
The analysed subsurface profile was compiled based on the results of our subsurface investigation.
Some inferences regarding subsurface conditions were made between test locations. A minimum FOS
value of 1.5 is the commonly adopted industry standard for long term conditions.
Although the existing sand dune slope would be considered relatively stable in the short term, it is
acknowledged that there were positive gradients dipping down and away, from beyond the eastern edge
of the likely building area, and very loose/loose sands were present in the near surface profile. The longer
term stability of the site could in addition be affected by other factors such as coastal erosion by storm
tides, which could theoretically lead to larger scale failures.
Modelling has therefore been carried out considering erosion from a hypothetical storm and wave
scenario nominated by coastal engineering experts (M&N), and taking into account subsequent
retrogression of the dune over time. Each of the cases analysed are summarised as follows:
Case 1 – Reprofiling of slope due to the modelled storm erosion profile.
Case 2 – Slope stability analysis following regressive failure of the slope from Case 1, with the high
dune ultimately assuming an inclination of 27° (eastern property boundary protected by a shear pile
wall).
The modelled ground surface profile for the initial Case 1 was based on provided survey information
across the subject site (Ref. Next Step Surveying, Project No. NSS032, Dwg No. 3000 001, dated 30
January 2025) with surface profiles beyond the eastern property boundary estimated from slope angles
and measurements in the field by Tectonic. Erosion cut adopted in Case 1 was based on information
provided in the referenced M&N report, which included a combination of short-term erosion from a
100-year average recurrence interval (ARI) storm event. It was indicated in the M&N assessment that a
significant portion of the high dune face would be affected by a future erosion cut, extending
approximately 17 m laterally into the dune face; with a localised scarp crest at around RL 23 m AHD. The
erosion cut was shown to extend to within 13 m of the subject site’s eastern boundary. A toe level of
around RL 1.9 m AHD was adopted; generally consistent with the larger scale erosion cut given by M&N
in their modelling. Subsurface conditions for Cases 1 & 2 were developed using the borehole and DCP
information collected during the investigations.
Based on the subsurface conditions at the site, and the extent of proposed earthworks, it is anticipated
that the majority of the building loads for the proposed residence and ancillary structures will be
transferred by high-level footings into the natural medium dense (or denser) sands underlying the site.
However, in some locations where medium dense (or denser) sands will be at depth, piled foundations
will be required. A surcharge load of 5 kPa was modelled in areas where the building loads are to be
transferred via piled foundations to the underlying soils and in landscaped/driveway areas, whilst 30 kPa
was applied across the proposed building area were medium dense (or denser) sands are expected at
bulk earthworks levels to represent the distributed load from the proposed three level structure.
The soil parameters adopted for the analyses are summarised in Table 4 and are based on interpretation
of the site investigation, in situ testing and laboratory test results. The parameters are consistent with
the low to mid-range values recommended for similar materials in Appendix D of Australian Standard
AS4678-2002 Earth Retaining Structures. Due to the dune slope and high permeability soils, a
groundwater table is not anticipated within the slope and therefore, was not modelled.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 13
Page 19
Table 4: Soil Parameters Adopted for Slope/W Analyses
Material Description Unit Weight (kN/m3) Cohesion, c (kPa) Friction Angle, ɸ (degrees)
Very Loose/Loose Sands 17 0 27
Medium Dense Sands 18 0 34
Dense (or denser) Sand 19 0 36
* Depends on type of fill used and compaction achieved
Commonly adopted industry standards generally require minimum FOS values against slope instability of
1.3 and 1.5 for short-term and long-term conditions, respectively. Administering authorities such as NC
normally require a minimum FOS of 1.5 or greater for long-term conditions. Results of the stability
analyses are presented in Table 5, with the Slope/W outputs shown in Text Figures 9 & 10, overleaf.
Table 5: Slope/W Analysis Results
Analysis Description Factor of Safety
Case 1 Unstable, over-steep dune face following potential future erosion cut after
0.5
significant storm event
Case 2 Slope stability analysis following regression of the slope from Case 1 to a
long-term stable profile of 27°, with the eastern property boundary 1.5
protected by a shear pile wall
Results of the analyses indicates the following:
Case 1 – It was noted that the modelled storm erosion cut would not initially affect the site.
However, the dune face following the storm erosion cut would have an unstable FOS of 0.5, due to
the over-steep nature of this profile.
Case 2 – Following regression of the dune from the future erosion cut to a long-term stable profile
of 27°, if the eastern property boundary is protected by an engineer designed and certified shear pile
structure the potential critical slip surface takes the form of a deep-seated failure into the underlying
dense (or denser) sands. Such a slip surface results in a FOS of 1.5, allowing for retrogression of the
slope from Cases 1. The pile wall structure would be significant, with deep piles (at least 12 m BGL)
and a concrete capping beam, possibly in combination with lateral restraint due to the pile ‘upstand’
of about 5 m.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 14
Page 20
Text Figure 9: Slope/W Output – Case 1
Text Figure 10: Slope/W Output – Case 2
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 15
Page 21
6. Geotechnical Recommendations Based on the modelled 100-year ARI erosion cut profile, and the subsequent regressive failures of the slope to equilibrium (27°), the subject site would require protection from erosion. From a geotechnical perspective, the requisite FOS could be achieved utilising a shear pile wall positioned along the eastern property boundary. However, the property is situated on the western (landward) side of The Esplanade road reserve, which acts as a buffer between the beach dune slope and the site. As a result, maintaining the integrity of the road reserve would, in turn, help protect the property. Since the road reserve is owned and managed by NC, it is anticipated that NC would prioritise its protection before any erosion progresses beyond the reserve and reaches the site. However, if NC determines that the property requires its own protective measures, a shear pile wall would need to be constructed along the eastern boundary. Given our understanding of the ground conditions and the predicted future slope geomorphology, a shear pile wall founded at depth into the dense (or denser) sands may be required to protect the site from coastal erosion. Subject to detailed design, secant or contiguous shear piles, possibly with additional structural support (e.g. raked piles, ground anchors), would be required. The adopted structure should comprise piles structurally tied together at the surface using a steel- reinforced concrete capping beam. An ‘A-frame’ structure may ultimately be required (i.e. vertical and raked piles) to achieve the required shear force resistance, at least if micro-piles are adopted, especially where allowance is given for the anticipated upstand ranging up to about 5 m high indicated by the stability analyses. A summary of the minimum piling requirements for the shear pile wall is given as follows: Case 4: Shear pile wall along eastern edge of building area: Minimum Pile Length (below existing ground): 12 m Upstand Height: 5m Unfactored resistance to normal shear forces: 160 kN/m* *The quoted resistance to normal shear forces is as utilised within the scope of the program Slope/W. It is noted that this does not necessarily relate to actual design parameters, and designers must undertake finite element analysis to assess soil/structure interactions and calculate both bending and shear stresses in the piles. Retaining structures should also undergo rigorous checks of global and internal stability. The designer must be satisfied that the geotechnical data presented is adequate to allow the analyses to be undertaken with a high degree of confidence. For a non-contiguous pile wall system such as micro-piles, a grout ‘curtain’ would need to be installed along the length of the wall to prevent the flow of sand between the piles. Based on the highest modelled vertical face of about 5 m height along the eastern boundary, such a grout ‘curtain’ should be installed down to at least 7 m below the ground surface (existing). Whilst the proposed structure would prevent erosion along the eastern boundary of the property, there is potential for the design erosion event to remove sand from the neighbouring properties to the north and south, exposing the side boundaries of the site to instability and erosion. The extent of the side boundary erosion protection required has been determined by a line drawn at 27° extending upwards from the estimated dune toe, following extreme storm erosion, and subsequent retrogressive failures. Erosion protection is required to extend from the shear pile wall to an equivalent distance of 8 m from the eastern property boundary, along the northern and southern boundaries. The erosion Geotechnical investigation 19 November 2025 | 25289-001-Rev0 16
Page 22
protection shall taper from a minimum depth of 2 m BGL in the west, deepening to the east to tie into the shear pile wall along the eastern edge. Whether the pile wall will also need to extend around the side boundaries will depend on the dimensions and strength of the grout curtain installed and its ability to provide at least emergency support to the retained sand. This should be considered as part of the detailed design. General geotechnical recommendations for site development are provided in the following sections. 6.1 Earthworks Bulk excavations in the order of up to 4 m depth are anticipated for the basement level construction. Isolated deeper excavations may be required for underground services and footings. The pool is shown to be below ground, and will require excavation of up to about 3 m below existing ground levels, close to the site’s northern boundary. Filling is anticipated to be for landscaping only, and should be less than 0.5 m high. The advice give herein should be treated as preliminary to aid in project planning, and Tectonic must review detailed design drawings for the residence prior to construction. 6.1.1 Site Preparation and Trafficability Following clearing of existing vegetation, any tree stumps and large roots should be ‘grubbed out’. Any organic rich topsoil should then be stripped and set aside. Similarly, all foundations and remaining structural elements from the existing residence should be removed. Based on the boreholes and site observations, stripping depths to remove existing unsuitable upper soils should be relatively shallow, however, deeper areas of unsuitable materials may be present across the site, particularly related to the existing structure (e.g. retaining wall backfill, service trenches, footing excavations). Topsoil materials must not be used in structural fill; however, may be placed across landscaping areas. It should be noted that compaction of such relatively ‘clean’ sands as structural fill requires the addition of substantial volumes of water (‘flooding’) combined with the use of vibratory compaction equipment (typically a vibrating plate). Care must be taken with the use of vibratory equipment (e.g. compactors or sheet piling) to ensure that there are no adverse impacts on surrounding structures. The impacts from ground vibration must be closely monitored and managed during construction. It would be prudent to conduct a dilapidation survey of neighbouring structures prior to commencement of construction; and furthermore it is recommended that a suitably qualified and experienced civil/structural RPEQ is engaged to provide a vibration management plan for the proposed construction works. The exposed natural subgrade following excavations will likely be in a loose condition (even where indicated to be denser in our investigation boreholes) and must be compacted by several passes of a vibrating plate or minimum 4 tonne vibrating smooth drum roller, in conjunction with surface application of ample water, to achieve the required compaction. Due to the potential for development of poor trafficability during construction, placement of a minimum 150 mm thick granular working platform may be required across laydown areas. Specific platform design would be required prior to mobilisation and trafficking of any heavy mobile plant on the site (e.g. mobile cranes, concrete pumps or piling rigs). Due to the highly permeable nature of the sands at this site, stormwater is expected to rapidly infiltrate the ground, making un-sealed surface drainage ineffective for the control of flows. Any sealed areas Geotechnical investigation 19 November 2025 | 25289-001-Rev0 17
Page 23
should be graded to ensure free drainage of stormwater away from construction areas, and to a control point(s). 6.1.2 Excavations Excavations through the soils should be achievable using conventional earthmoving plant (e.g. excavators with toothed buckets). Temporary, unsurcharged cuts in the very loose to loose sand could be formed at 1V:2H, and at 1V:1.5H in medium dense (or denser) sand, for batters up to 4 m in height. Flatter batters or temporary retention may be required if groundwater seepage is encountered or if sloughing of dry sand occurs at the batter surface. Deeper cuts, if required, may require temporary shoring, unless assessed and approved by Tectonic during construction. Permanent cuts or fills greater than 1 m must be retained. Permanent cut and fill batters up to 1 m high shall not exceed 1V:2.5H. Any permanent soil and fill batters will require erosion protection (e.g. revegetation or surface protection). It is likely that the temporary batter slopes will not be able to be achieved due to spatial constraints. Thus, temporary shoring will likely be required, as per the recommendations in Section 6.3 below. Excavations in close proximity to existing structures and infrastructure (e.g. underground services in along the eastern property boundary), including neighbouring properties, will need to be specifically designed to prevent undermining. If undermining is a potential issue the existing structures may need to be underpinned or excavations may require temporary shoring. The advice of a suitably qualified and experienced structural RPEQ must be sought regarding any potential undermining and design and construction of any underpins/temporary shoring (if required). The above recommendations do not supersede any existing safety regulations or legislation applicable to excavations (e.g. limits on personnel entry into trenches). 6.1.3 Filling The natural sandy soils where free of deleterious materials (e.g. vegetation, organics etc.) may be reused as structural fill, subject to appropriate moisture adjustment. It should be noted that compaction of such relatively ‘clean’ sands as structural fill requires the addition of substantial volumes of water (‘flooding’) combined with the use of vibratory compaction equipment (typically a smooth drum roller or heavy vibrating plate). Should importation of fill be required, it is recommended that such fill should comply with the following: Minimum CBR of 10 % Maximum plasticity index of 15 % Shrink-swell index ≤ 1 % Maximum particle size of 100 mm Any fill should be compacted at moisture contents within the range of ±2 % of optimum moisture content for Standard Compaction. Fill material should be placed in 250 mm thick (loose thickness) layers and be compacted by repeated rolling using a minimum 4 tonne smooth drum roller (or equivalent, with vibration on if safe to do so) to achieve a dry density ratio of at least 95 % of the maximum Dry Density Ratio (DDR), based upon the Standard Compaction method, or a Dry Density Index of at least 70 %. Confirmatory compaction testing must be carried out at regular intervals. A minimum of two tests per vertical lift is recommended where structural fill heights are to exceed 300 mm. Further details for Geotechnical investigation 19 November 2025 | 25289-001-Rev0 18
Page 24
control and testing of fill are given in Australian Standard AS 3798-2007 Guidelines on Earthworks for Commercial and Residential Developments. 6.2 Building Foundations 6.2.1 Indicative Site Classification Site classification for footing design is determined in accordance with AS 2870-2011 Residential Slabs and Footings, and depend on the depth of cut / fill undertaken at a site, variations in the natural soil profile, and the reactivity of the in situ soil and any imported fill materials. Based on the results of the investigation, it is recommended that a site classification equivalent to Class M is used in relation to the assessment of flexibility requirements for ground slabs, footing and plumbing design. The footing design recommendations given below must also be considered. 6.2.2 Footing Design No design loadings were available at the time of reporting. Footings for the proposed residence and any ancillary structures (e.g. retaining walls, pool etc.) must penetrate through any fill materials and unsuitable natural soils (i.e. very loose to loose sands) to found at least 1 m into medium dense (or denser) natural sands. High-level footings may be possible in areas of deeper excavation where medium dense to dense (or denser) sands are exposed at or near the subgrade. This would be subject to an assessment by a suitably qualified and experienced geotechnical RPEQ (including verification testing). High-level footings, so founded, could be designed using a maximum allowable bearing pressure of 100 kPa. Elsewhere (excluding the shear pile wall), based on the results of the investigation, pile founding depths for the building of up to 3.5 m BGL (existing ground levels) are anticipated. Deeper piles may be necessary subject to an assessment of building loads at the detailed design stage. Excluding the shear pile wall, steel screw piles would be an appropriate footing option, where required. Piles may be designed using a maximum allowable end bearing pressure of 600 kPa in medium dense sands, or at least 1 MPa in the deeper dense sands. Due to the presence of very loose to loose upper sands, together with the restricted site conditions and close proximity of adjacent houses, open bored piers or driven piles are not recommended for this site. A possible alternative to screw piles could be grout-injected, CFA piles, provided that construction water loss is carefully monitored and controlled. Steel reinforced concrete bored piles may be possible; however, the use of sacrificial liners (e.g. ‘Formatube’) would be required. If steel screw piles are adopted, it will be important to ensure close supervision of installation, as piling may not encounter sufficient drilling resistance (from torque measurement) in sands at the suggested founding depth, and piles could extend to much greater depth than necessary. It is therefore recommended that site specific dynamic load testing be conducted on screw piles, if adopted, at a minimum. Where tension or compression capacity developed in the footings is critical for the future structure (e.g. resistance to uplift forces from high winds), then cyclic load tests (including measurement of deflections under tension and compression cycles) should also be undertaken prior to construction. Kentledge for static testing, or simulated cyclic loads, should prove the piles to a minimum of two times the expected working load within tolerable deflections. Geotechnical investigation 19 November 2025 | 25289-001-Rev0 19
Page 25
Ultimately, the advice of a specialist piling contractor should be sought regarding pile design and
construction. However, where steel screw piles are adopted site specific load testing and the results of
this geotechnical investigation should be considered by the structural engineers in validating any generic
torque to capacity ratios provided as part of the proposed design. An assessment of potential vibration
effects on nearby structures and monitoring requirements should also be included.
Footing design should also account for potential soil reactivity to be equivalent to Class M.
All footings should found such that they are not adversely affected by any adjacent excavations, trenches,
retaining walls, or in ground structures that are not designed to support building loads. Footings should
found at least below a plane extending 1 m horizontally from the base of
trenches/excavations/swimming pool, then rising up at 1V:1H, as illustrated in Text Figure 11.
Where consideration is given to the use of high level footings to the western side of the residence,
structural designers should allow for the deepest founding depth of either:
Founding footings below the zone of active earth pressure (within this zone reduced foundation
capacity and adverse interaction with the seaward retention system are anticipated); or
The arrangement should comply with Text Figure 11, with the relevant plane taken from the
equivalent ground level at the front of the exposed piled wall following the most onerous erosion
Case 2 in the stability modelling (Ref. Section 5.2.1).
Text Figure 11: Zone of influence diagrams – footings to be founded below these lines
It is recommended that footings be inspected by a suitably qualified and experienced engineer prior to
placement of steel reinforcement and pouring of concrete to confirm allowable bearing pressures and
cleanliness of excavations.
If any soil conditions encountered during construction are found to differ from those noted in the
geotechnical investigation, Tectonic should be notified immediately and an inspection carried out to
determine if changes to footing design are required.
6.3 Temporary and Permanent Retention
Excavations are expected to range up to around 4 m BGL (existing ground levels) and, given that the
planned excavation extends close to some of the site boundaries and underground infrastructure (e.g.
underground services), some form of temporary shoring will likely be required.
Based upon our experience with similar sites, we anticipate that temporary shoring may be achieved by
use of sheet piles, however Unitywater and NC requirements for their infrastructure may restrict the use
of sheet piles. Shoring of deeper cuts would likely require lateral restraint, and this is conventionally
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 20
Page 26
achieved by helical steel anchors (similar to screw piles); and the proximity to neighbouring structures
would require permissions to be obtained for subterranean access. Therefore, where lateral support by
cantilever only is not feasible, it is suggested that internal struts/propping be considered to provide
lateral restraint for the shoring system.
Anchored or propped sheet piles may require pre-drilling to prevent adverse vibrations during sheet pile
installation (where penetration of the deeper dense sands is required).
Other shoring methods that could be considered include bored contiguous or secant piles.
Conventional non-contiguous or soldier pile walls are not feasible for the proposed development due to
the likelihood that loose sands would ‘flow’ through gaps between the piles. Their use may however be
possible where additional grout panels are included in the design.
An advantage of contiguous or secant pile wall retention systems is that they are ultimately used for the
permanent walls, whereas sheet piles would be temporary to provide retention during construction only,
therefore requiring a permanent structural wall to be constructed. Bored pile walls generally require
greater width (horizontally) for installation as compared to sheet piles and are often more expensive.
The advice of a specialist shoring contractor must be sought regarding feasibility, design and installation
of the proposed retention system. It will be necessary to conduct numerical analysis to optimise the
retention system. Detailed design will also need to account for relevant factors of safety to maintain the
temporary and long-term stability of the retention system.
Retaining structures greater than 1 m high, or those required to support surcharge loads or sloping
backfill, will require engineer design and certification of construction. Retaining wall design should be
carried out in accordance with AS4678-2002 Earth retaining structures.
Design for temporary and permanent retaining structures could be carried out using a pressure
distribution applicable to the wall type and based on the parameters listed in Table 6. These values do
not include allowance for hydrostatic pressures, backslopes (assumed to be horizontal), nor transient (e.g.
construction) or adjacent footing loadings.
Table 6: Retaining Structure Design Parameters
Lateral earth pressure coefficients
Unit weight Ka Ko Kp
Retained material Friction angle (°)
(kN/m3) (Cantilever wall) (Non-yielding
wall)
Very Loose/Loose
17 27 0.38 0.55 2.66
Sands
Medium Dense
18 34 0.28 0.44 3.54
Sands
Dense (or Denser)
19 36 0.26 0.41 3.85
Sands
Future Controlled
* * * * *
Fill*
Note: * Depends on fill material type and level of compaction.
Retaining structures must be founded as per the recommendations in Section 6.2.2 above with the
footings also designed to account for lateral loads imposed by the retaining wall. Detailed design must
include an assessment of internal and global stability.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 21
Page 27
6.4 Drainage
Adequate site drainage must be installed to ensure that stormwater runoff is directed away from building
walls, footings, batters and retaining walls. Although unlikely, if groundwater seepage is encountered
during excavations, Tectonic must be notified to assess the impact on stability.
Subsurface drainage must be installed behind any retaining walls (e.g. slotted ‘aggi’ pipe wrapped in
filter ‘sock’ placed in gravel backfill). Depending on matters such as the extent of drainage installed and
site-specific groundwater conditions, the designer must make an assessment of hydrostatic pressure to
be accounted for in the design of the retaining structure.
Collected roof water should be directed by pipes to the council stormwater system along The Esplanade.
Hydraulic design should be such that under no circumstances are uncontrolled stormwater flows
permitted over the dune face; where channelised erosion and scour features could be allowed to
develop.
Design of the stormwater system should be undertaken by a suitably qualified and experienced RPEQ.
7. Conclusion
Based on the findings of our assessment it is concluded that a Low Risk of slope instability could be
achieved for the proposed development, subject to the following:
Implementation of the recommendations given in this report in formulating the feasibility of the
development, and preparing the final design; and
Review of the detailed design by Tectonic to confirm compliance with the recommendations herein.
Confirmation of the deeper subsurface profile present along the eastern boundary would be required to
enable detailed design of the shear pile wall system, if required, via further ground investigation
following access being facilitated by the demolition of the existing residence. This should comprise a
borehole taken to a depth in the order of 20 m BGL, using a rotary drill rig capable of solid flight
augering and deep cased wash boring, with standard penetration tests (SPTs).
8. Limitations
Your attention is drawn to the document Limitations, which is included in Appendix D 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.
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 22
Page 28
LEGEND CLIENT PROJECT “- APPROX. HAND AUGER LOCATIONS CHRISTIAN SEYMOUR GEOTECHNICAL INVESTIGATION AND SLOPE STABILITY ASSESSMENT FOR PROPOSED RESIDENCE D 17 THE ESPLANADE, SUNSHINE BEACH 4 APPROX. SECTION LINE A-A' KAB 13/11/20: DRAWING TITLE NOTES ‘ SITE PLAN BASEMAP C CHECKED BY ACD 13/11/20 PROJECT NO. DOC NO. FIGURE NO. SCALE @ APPROX. DCP LOCATIONS TESY OF NE, Al 5 1 REVISION
Page 29
ELEVATION (m AHD) 0 10 20 30 40 50 60 70 80 90 100 35 35 30 30 S on The Esplanade Bae 25 25 5 pprox Ground Surface. 20 am 20 ood 15 ” 15 g Ban « 19) <-> ~~ 10 Sunshine Beach ” 2 ‘ o ‘ » 5 0 -5| 5 -10| -10 -15| -15 -20| -20 0 10 20 30 0 30 60 70 80 90 100 DISTANCE (m) POST LEGEND MATERIAL GRAPHIC ~ ee z B Fu | aed = Cie ic piety SR as ‘ W300 ™ ™ op "18/11/2025 ° SS Se Christian Seymour San ry V 1:300 | 17 The Esplande, Sunshine Beach AD 18/11/2025 ae ee ee Proposed Residence H 1:300_V_1:300 [a3 Doh et Eo Coord Sytem: WGAZ020 Zone 58 Height Dctume: AHO Subsurface Section A- A’ man 089 =
Page 30
Appendix A
Borehole/DCP Reports & Explanatory Notes
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 23
Page 31
Borehole No.
BH1
Page 1 of 1
Engineering Log - Borehole Project No.: 25289
Client: Christian Seymour Commenced: 24/9/2025
Project Name: Proposed Residence Completed: 24/9/2025
Hole Location: 17 The Esplande, Sunshine Beach Logged By: BC
Hole Position: 511227.0 m E 7079650.0 m N MGA2020 Zone 56 Checked By: OD
Drill Model and Mounting: Hand Auger Inclination: -90° RL Surface: 24.00 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: KAB
Drilling Information Material Description and Observations
Relative Density
Classification DCP TEST
Penetration
Pocket
Consistency
Graphic Log
Samples Material Description
Penetrometer
Condition
Recovery
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
secondary and minor components, colour
Water
Remarks RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
Clayey SAND (FILL), fine to coarse grained,
dark grey, medium plasticity clay fines, with D to
L
organics, with fine to coarse sized subangular M
to subrounded gravels
SP
DS_0.5-0.6m SAND, fine to medium grained, grey brown,
(DUNE SAND)
becoming grey MD
23.0
1 Augered to 1.1m
becoming pale grey
Not Encountered
D
22.0
2
HA
M
TECTONIC 3.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 25289.GPJ <<DrawingFile>> 18/11/2025 10:57 10.02.00.04 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 3.00.2 2021-03-30 Prj: Tectonic 3.00.2 2021-03-30
Augered to 3.0m
21.0
3
VD
Augered to 4.0m
20.0
4
Hole Terminated at 4.00 m
Refusal on very dense sand
19.0
5
18.0
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit VE - Very Easy Level (Date) U## - Undisturbed Sample (## mm) D - Dry VS - Very Soft
AD/V-Auger Drilling V Bit E - Easy DS - Disturbed Sample M - Moist S - Soft
RT - Rotary Tri-cone Bit Inflow BDS- Bulk Disturbed Sample W - Wet F - Firm
RD - Rotary Drilling F - Firm SPT - Standard Penetration Test VSt - Very Stiff
Partial Loss
NMLC -Rock Core H - Hard H - Hard
VH - Very hard Complete Loss
HA - Hand Auger Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols < PL MD - Medium Dense
Core recovered (hatching and Soil Descriptions D - Dense
indicates material) = PL
Based on Unified Soil < PL VD - Very Dense
Core loss Classification System Fr - Friable
Page 32
Borehole No.
BH2
Page 1 of 1
Engineering Log - Borehole Project No.: 25289
Client: Christian Seymour Commenced: 24/9/2025
Project Name: Proposed Residence Completed: 24/9/2025
Hole Location: 17 The Esplande, Sunshine Beach Logged By: BC
Hole Position: 511206.0 m E 7079665.0 m N MGA2020 Zone 56 Checked By: OD
Drill Model and Mounting: Hand Auger Inclination: -90° RL Surface: 27.00 m
Hole Diameter: 100 mm Bearing: 360° Datum: AHD Operator: KAB
Drilling Information Material Description and Observations
Relative Density
Classification DCP TEST
Penetration
Pocket
Consistency
Graphic Log
Samples Material Description
Penetrometer
Condition
Recovery
Tests soil type: plasticity or particle characteristics,
Moisture
UCS Blows per 100 mm
Symbol
Method
secondary and minor components, colour
Water
Remarks RL Depth (kPa)
(m) (m) 0 5 10 15 20 25
100
200
300
400
500
Silty SAND (FILL), fine to medium grained,
dark grey, with rootlets
L
SP SAND, fine to medium grained, grey, (DUNE
SAND)
Augered to 1.0m
26.0
1
Not Encountered
HW
VL
M
HA
25.0
2 becoming pale grey
L
TECTONIC 3.00.2 LIB.GLB Log 1 TECTONIC BOREHOLE 25289.GPJ <<DrawingFile>> 12/11/2025 13:58 10.02.00.04 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 3.00.2 2021-03-30 Prj: Tectonic 3.00.2 2021-03-30
MD
24.0
3
Hole Terminated at 3.00 m
Target depth
23.0
4
22.0
5
21.0
6
Method Penetration Water Samples and Tests Moisture Condition Consistency/Relative Density
AD/T-Auger Drilling TC Bit VE - Very Easy Level (Date) U## - Undisturbed Sample (## mm) D - Dry VS - Very Soft
AD/V-Auger Drilling V Bit E - Easy DS - Disturbed Sample M - Moist S - Soft
RT - Rotary Tri-cone Bit Inflow BDS- Bulk Disturbed Sample W - Wet F - Firm
RD - Rotary Drilling F - Firm SPT - Standard Penetration Test VSt - Very Stiff
Partial Loss
NMLC -Rock Core H - Hard H - Hard
VH - Very hard Complete Loss
HA - Hand Auger Plastic Limit VL - Very Loose
Graphic Log/Core Loss L - Loose
Classification Symbols < PL MD - Medium Dense
Core recovered (hatching and Soil Descriptions D - Dense
indicates material) = PL
Based on Unified Soil < PL VD - Very Dense
Core loss Classification System Fr - Friable
Page 33
CLIENT : Christian Seymour SHEET : 1 OF 1
CONTRACTOR :
PROJECT : Proposed Residence
LOCATION : 17 The Esplande, Sunshine Beach
PROJECT No. : 25289
TEST: DCP1 TEST: DCP2 TEST: DCP3
LOGGED: BC 24/9/2025 CHECKED: OD LOGGED: BC 24/9/2025 CHECKED: OD LOGGED: BC 24/9/2025 CHECKED: OD
Depth (m)
Depth (m)
Depth (m)
Blows per 100 mm Blows per 100 mm Blows per 100 mm
0 5 10 15 20 25 0 5 10 15 20 25 0 5 10 15 20 25
HW HW
1 1 1
2 2 2
TECTONIC 3.00.2 LIB.GLB Log IS DCP 3 PER PAGE 25289.GPJ <<DrawingFile>> 12/11/2025 13:58 10.02.00.04 Datgel Lab and In Situ Tool - DGD | Lib: Tectonic 3.00.2 2021-03-30 Prj: Tectonic 3.00.2 2021-03-30
3 3 3
4 4 4
5 5 5
6 6 6
Comments Comments Comments
Page 34
TERMS USED ON LOGS
DRILLING/EXCAVATION METHOD
AD* Auger Drilling RD Rotary Blade or Drag bit NQ Diamond Core - 47 mm
*V V-Bit RT Rotary Tri-cone bit NMLC Diamond Core - 52 mm
*T TC-Bit RA Rotary Air HQ Diamond Core - 63 mm
HA Hand Auger HMLC Diamond Core – 63mm
ADH Hollow Auger BH Tractor Mounted Backhoe
EX Tracked Hydraulic Excavator
WATER
GROUNDWATER NOT The observation of groundwater, whether present or not, was not possible due to drilling water,
OBSERVED surface seepage or cave in of the borehole/test pit.
GROUNDWATER NOT The borehole/test pit was dry soon after excavation. However, groundwater could be present in
ENCOUNTERED less permeable strata. Inflow may have been observed had the borehole/test pit been left open
for a longer period.
SAMPLING AND TESTING
SPT Standard Penetration Test to AS1289.6.3.1-2004
5,4,10 N=14 5,4,10 = Blows per 150mm. N = Blows per 300mm penetration following 150mm seating
30/65mm Where practical refusal occurs, the blows and penetration for that interval are reported
RW Penetration occurred under the rod weight only
HW Penetration occurred under the hammer and rod weight only
HB Hammer double bouncing on anvil
DS Disturbed sample
BDS Bulk disturbed sample
FV Field vane shear test expressed as uncorrected shear strength (sv = peak value, sr = residual value)
PP Pocket penetrometer test expressed as instrument reading in kPa
U50 Thin walled tube sample - number indicates nominal sample diameter in millimetres
DCP Dynamic cone penetration test
CPT Electronic cone penetration test
CPTu Electronic cone penetration test with pore pressure (u) measurement
Rev1
August 2024
Page 35
METHOD OF SOIL DESCRIPTION
USED ON LOGS
CLASSIFICATION AND INFERRED STRATIGRAPHY
Soil is classified and described in borehole and test pit logs using the preferred method given in AS1726 – 2017.
The material properties are assessed in the field by visual/tactile methods.
Particle Size Plasticity Properties
Major Sub Division Particle Size
Division
BOULDERS > 200 mm
COBBLES 63 to 200 mm
Coarse 19 to 63 mm
GRAVEL Medium 6.7 to 19 mm
Fine 2.36 to 6.7 mm
Coarse 0.6 to 2.36 mm
SAND Medium 0.21 to 0.6 mm
Fine 0.075 to 0.21
SILT 0.002 to 0.075
CLAY < 0.002 mm
NOTE: The U line is an approximate upper bound for most materials.
Data which plot above the U line may represent unusual/problem soil
behavior, or unreliable data and should be considered carefully.
MOISTURE CONDITION AS1726 - 2017
Coarse Grained Soils
Symbol Term Description
D Dry Sands and gravels are free flowing.
M Moist Soils are darker than in the dry condition & may feel cool. Sands and gravels tend to cohere.
W Wet Soils exude free water. Sands and gravels tend to cohere
Fine Grained Soils
Symbol Description
w < PL Moist, dry of plastic limit, (hard and friable or powdery)
w = PL Moist, near plastic limit, (soils can be moulded at a moisture content approximately equal to the plastic limit)
w > PL Moist, wet of plastic limit, (soils usually weakened and free water forms on hands when handling)
w = LL Wet, near liquid limit
w > LL Wet, wet of liquid limit
CONSISTENCY AND DENSITY AS1726 - 2017
Symbol Term Undrained Shear Symbol Term Density Index % SPT “N” #
Strength
VS Very Soft 0 to 12 kPa VL Very Loose Less than 15 0 to 4
S Soft 12 to 25 kPa L Loose 15 to 35 4 to 10
F Firm 25 to 50 kPa MD Medium Dense 35 to 65 10 to 30
St Stiff 50 to 100 kPa D Dense 65 to 85 30 to 50
VSt Very Stiff 100 to 200 kPa VD Very Dense Above 85 Above 50
H Hard Above 200 kPa
In the absence of test results, consistency and density may be assessed from correlations with the observed behaviour of
the material.
# SPT correlations are not stated in AS1726 – 2017, and may be subject to corrections for overburden pressure and
equipment type.
Rev3
November 2024
Page 36
Appendix B
Laboratory Test Certificate
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 24
Page 37
Material Test Report
Report Number: SL25-1262A-33
Issue Number: 1
Butler Partners (Regional) Pty Ltd
Date Issued: 01/10/2025 Sunshine Coast Laboratory
Client: Tectonic Geotechnical PtyLtd 1/6 Runway Drive Marcoola QLD 4565
924 David Low Way, Marcoola QLD 4564 Phone: 0461 255 681
Contact: Ashley Davey Email: [email protected]
Project Number: SL25-1262A Accredited for compliance with ISO/IEC 17025 - Testing
Project Name: Tectonic
Project Location: the Esplanade, Sunshine Beach
Client Reference: 25289
Work Request: 1903 Approved Signatory: Chris Davidson
Sample Number: SC25-1903A Laboratory Manager
NATA Accredited Laboratory Number: 19529
Date Sampled: 26/09/2025
Dates Tested: 26/09/2025 - 29/09/2025
Sampling Method: Sampled by Client
The results apply to the sample as received
Preparation Method: AS 1289.1.1 - Sampling and Preparation of Soils
Site Selection: Selected by Client
Sample Location: The Esplanade, Sunshine Beach , Depth: BH1 0.5-0.6
Material: SAND with trace clay/silt and gravel - SP
Material Source: UNKNOWN
Particle Size Distribution
Particle Size Distribution (AS1289 3.6.1)
Sieve Passed % Clay Passing Limits Silt Sand Gravel Cob
0.075
0.425
4.75 mm 100 Sieve
0.15
1.18
2.36
4.75
0.3
0.6
(mm)
2.36 mm 98 100
1.18 mm 98
90
0.6 mm 97
0.425 mm 87 80
Percent Passing
0.3 mm 52 70
0.15 mm 2
60
0.075 mm 1
50
40
30
20
10
0.1 0.2 1 2 3 4 5 10 20 30
Particle Size (mm)
This document shall not be reproduced except in full without approval of the laboratory.
Report Number: SL25-1262A-33 Results relate only to the items tested/sampled. Page 1 of 1
Page 38
Appendix C
Extracts from AGS Guidelines (2007)
Qualitative Terminology for Use Assessing Risk to Property
& Some Guidelines for Hillside Construction
Geotechnical investigation
19 November 2025 | 25289-001-Rev0 25
Page 39
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX C: LANDSLIDE RISK ASSESSMENT
QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY
QUALITATIVE MEASURES OF LIKELIHOOD
Approximate Annual Probability
Implied Indicative Landslide
Description Descriptor Level
Indicative Notional Recurrence Interval
Value Boundary
10-1 5x10-2
10 years The event is expected to occur over the design life. ALMOST CERTAIN A
20 years The event will probably occur under adverse conditions over the
-2
10 100 years
design life.
LIKELY B
-3
-3 5x10 200 years
10 1000 years The event could occur under adverse conditions over the design life. POSSIBLE C
5x10-4 2000 years
The event might occur under very adverse circumstances over the
10-4 10,000 years
design life.
UNLIKELY D
-5 5x10-5 20,000 years
10 The event is conceivable but only under exceptional circumstances
100,000 years RARE E
over the design life.
-6 5x10-6 200,000 years
10 1,000,000 years The event is inconceivable or fanciful over the design life. BARELY CREDIBLE F
Note: (1) The table should be used from left to right; use Approximate Annual Probability or Description to assign Descriptor, not vice versa.
QUALITATIVE MEASURES OF CONSEQUENCES TO PROPERTY
Approximate Cost of Damage
Description Descriptor Level
Indicative Notional
Value Boundary
Structure(s) completely destroyed and/or large scale damage requiring major engineering works for
200% CATASTROPHIC 1
stabilisation. Could cause at least one adjacent property major consequence damage.
100%
Extensive damage to most of structure, and/or extending beyond site boundaries requiring significant
60% MAJOR 2
stabilisation works. Could cause at least one adjacent property medium consequence damage.
40%
Moderate damage to some of structure, and/or significant part of site requiring large stabilisation works.
20% MEDIUM 3
Could cause at least one adjacent property minor consequence damage.
10%
5% 1% Limited damage to part of structure, and/or part of site requiring some reinstatement stabilisation works. MINOR 4
Little damage. (Note for high probability event (Almost Certain), this category may be subdivided at a
0.5% INSIGNIFICANT 5
notional boundary of 0.1%. See Risk Matrix.)
Notes: (2) The Approximate Cost of Damage is expressed as a percentage of market value, being the cost of the improved value of the unaffected property which includes the land plus the
unaffected structures.
(3) The Approximate Cost is to be an estimate of the direct cost of the damage, such as the cost of reinstatement of the damaged portion of the property (land plus structures), stabilisation
works required to render the site to tolerable risk level for the landslide which has occurred and professional design fees, and consequential costs such as legal fees, temporary
accommodation. It does not include additional stabilisation works to address other landslides which may affect the property.
(4) The table should be used from left to right; use Approximate Cost of Damage or Description to assign Descriptor, not vice versa
Australian Geomechanics Vol 42 No 1 March 2007
68039 Landslide Risk Management Issued 10/7/07
Page 40
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX C: – QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY (CONTINUED)
QUALITATIVE RISK ANALYSIS MATRIX – LEVEL OF RISK TO PROPERTY
LIKELIHOOD CONSEQUENCES TO PROPERTY (With Indicative Approximate Cost of Damage)
Indicative Value of 1: CATASTROPHIC 2: MAJOR 3: MEDIUM 4: MINOR 5:
Approximate Annual 200% 60% 20% 5% INSIGNIFICANT
Probability 0.5%
A – ALMOST CERTAIN 10-1 VH VH VH H M or L (5)
-2
B - LIKELY 10 VH VH H M L
C - POSSIBLE 10-3 VH H M M VL
D - UNLIKELY 10-4 H M L L VL
-5
E - RARE 10 M L L VL VL
-6
F - BARELY CREDIBLE 10 L VL VL VL VL
Notes: (5) For Cell A5, may be subdivided such that a consequence of less than 0.1% is Low Risk.
(6) When considering a risk assessment it must be clearly stated whether it is for existing conditions or with risk control measures which may not be implemented at the current
time.
RISK LEVEL IMPLICATIONS
Risk Level Example Implications (7)
Unacceptable without treatment. Extensive detailed investigation and research, planning and implementation of treatment
VH VERY HIGH RISK options essential to reduce risk to Low; may be too expensive and not practical. Work likely to cost more than value of the
property.
Unacceptable without treatment. Detailed investigation, planning and implementation of treatment options required to reduce
H HIGH RISK
risk to Low. Work would cost a substantial sum in relation to the value of the property.
May be tolerated in certain circumstances (subject to regulator’s approval) but requires investigation, planning and
M MODERATE RISK implementation of treatment options to reduce the risk to Low. Treatment options to reduce to Low risk should be
implemented as soon as practicable.
Usually acceptable to regulators. Where treatment has been required to reduce the risk to this level, ongoing maintenance is
L LOW RISK
required.
Acceptable. Manage by normal slope maintenance procedures.
VL VERY LOW RISK
Note: (7) The implications for a particular situation are to be determined by all parties to the risk assessment and may depend on the nature of the property at risk; these are only
given as a general guide.
Australian Geomechanics Vol 42 No 1 March 2007
68039 Landslide Risk Management Issued 10/7/07
Page 41
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX G - SOME GUIDELINES FOR HILLSIDE CONSTRUCTION
GOOD ENGINEERING PRACTICE POOR ENGINEERING PRACTICE
ADVICE
GEOTECHNICAL Obtain advice from a qualified, experienced geotechnical practitioner at early Prepare detailed plan and start site works before
ASSESSMENT stage of planning and before site works. geotechnical advice.
PLANNING
SITE PLANNING Having obtained geotechnical advice, plan the development with the risk Plan development without regard for the Risk.
arising from the identified hazards and consequences in mind.
DESIGN AND CONSTRUCTION
Use flexible structures which incorporate properly designed brickwork, timber Floor plans which require extensive cutting and
or steel frames, timber or panel cladding. filling.
HOUSE DESIGN
Consider use of split levels. Movement intolerant structures.
Use decks for recreational areas where appropriate.
SITE CLEARING Retain natural vegetation wherever practicable. Indiscriminately clear the site.
ACCESS & Satisfy requirements below for cuts, fills, retaining walls and drainage. Excavate and fill for site access before
DRIVEWAYS Council specifications for grades may need to be modified. geotechnical advice.
Driveways and parking areas may need to be fully supported on piers.
EARTHWORKS Retain natural contours wherever possible. Indiscriminatory bulk earthworks.
Minimise depth. Large scale cuts and benching.
CUTS Support with engineered retaining walls or batter to appropriate slope. Unsupported cuts.
Provide drainage measures and erosion control. Ignore drainage requirements
Minimise height. Loose or poorly compacted fill, which if it fails,
Strip vegetation and topsoil and key into natural slopes prior to filling. may flow a considerable distance including
Use clean fill materials and compact to engineering standards. onto property below.
FILLS Batter to appropriate slope or support with engineered retaining wall. Block natural drainage lines.
Provide surface drainage and appropriate subsurface drainage. Fill over existing vegetation and topsoil.
Include stumps, trees, vegetation, topsoil,
boulders, building rubble etc in fill.
ROCK OUTCROPS Remove or stabilise boulders which may have unacceptable risk. Disturb or undercut detached blocks or
& BOULDERS Support rock faces where necessary. boulders.
Engineer design to resist applied soil and water forces. Construct a structurally inadequate wall such as
Found on rock where practicable. sandstone flagging, brick or unreinforced
RETAINING
Provide subsurface drainage within wall backfill and surface drainage on slope blockwork.
WALLS
above. Lack of subsurface drains and weepholes.
Construct wall as soon as possible after cut/fill operation.
Found within rock where practicable. Found on topsoil, loose fill, detached boulders
Use rows of piers or strip footings oriented up and down slope. or undercut cliffs.
FOOTINGS
Design for lateral creep pressures if necessary.
Backfill footing excavations to exclude ingress of surface water.
Engineer designed.
Support on piers to rock where practicable.
SWIMMING POOLS Provide with under-drainage and gravity drain outlet where practicable.
Design for high soil pressures which may develop on uphill side whilst there
may be little or no lateral support on downhill side.
DRAINAGE
Provide at tops of cut and fill slopes. Discharge at top of fills and cuts.
Discharge to street drainage or natural water courses. Allow water to pond on bench areas.
SURFACE Provide general falls to prevent blockage by siltation and incorporate silt traps.
Line to minimise infiltration and make flexible where possible.
Special structures to dissipate energy at changes of slope and/or direction.
Provide filter around subsurface drain. Discharge roof runoff into absorption trenches.
Provide drain behind retaining walls.
SUBSURFACE
Use flexible pipelines with access for maintenance.
Prevent inflow of surface water.
Usually requires pump-out or mains sewer systems; absorption trenches may Discharge sullage directly onto and into slopes.
SEPTIC &
be possible in some areas if risk is acceptable. Use absorption trenches without consideration
SULLAGE
Storage tanks should be water-tight and adequately founded. of landslide risk.
EROSION Control erosion as this may lead to instability. Failure to observe earthworks and drainage
CONTROL & Revegetate cleared area. recommendations when landscaping.
LANDSCAPING
DRAWINGS AND SITE VISITS DURING CONSTRUCTION
DRAWINGS Building Application drawings should be viewed by geotechnical consultant
SITE VISITS Site Visits by consultant may be appropriate during construction/
INSPECTION AND MAINTENANCE BY OWNER
OWNER’S Clean drainage systems; repair broken joints in drains and leaks in supply
RESPONSIBILITY pipes.
Where structural distress is evident see advice.
If seepage observed, determine causes or seek advice on consequences.
Australian Geomechanics Vol 42 No 1 March 2007 113
Page 42
PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007 114 Australian Geomechanics Vol 42 No 1 March 2007
Page 43
tect¢nic Appendix D Limitations
Page 44
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. Limitations August 2024 | Rev2
Page 45
PO Box 899 tectonicgeo.com.au [email protected]
Buderim
Geotechnical QLD 4555
investigation
19 November 2025 | 25289-001-Rev0 27