21054-001-Rev0 Tristania Dr

Peter Williams                                                                                   21054-001-Rev0
                                                                                                25 February 2021

2.4   Surface Drainage
The site has a relatively small catchment, with no natural surface features observed that would cause
concentration of surface runoff. Most of the surface water to the west of the property is anticipated to be
intercepted by the existing stormwater infrastructure along the David Low Way. Given the sandy nature of
the site and surrounds, rainfall would normally be anticipated to infiltrate the ground surface. However, as
the proposed residence will occupy a large part 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 evidence of significant erosion was observed across the subject site.

2.5   Vegetation
As illustrated in Text Figure 5 (on preceding page), the ground surface was covered by relatively dense
vegetation comprising mostly shrubs and small to medium sized trees. Some of the tress appeared to have
died and/or were slightly leaning, which may be due to shallow soil creep.

2.6   Buildings and Other Structures
There were no existing structures on the site at the time of the investigation. Surrounding properties to the
south comprised single to double storey structures having slab on ground floors, with observable external
walls noted to be in good condition and showing no obvious signs of distress (e.g. cracking, etc.). The
pavement along Tristania Drive was noted to be in relatively good condition. Minor cracking was evident in
the asphalt seal, which was likely due to consolidation of the surficial materials rather than slope instability.



3.0     ASSESSMENT OF LAND STABILITY
3.1   Existing Conditions
The Noosa Planning Scheme 2020 includes a landslide hazard overlay map (Ref. extract in Text Figure 6),
which indicates that most of the site and development area mapped as having a Moderate (pale yellow
shading) landslide hazard. Areas of Very Low/Low (no shading) landslide hazard are mapped in the north-
eastern and south-western corner of the site.




                                                                  Subject site




Text Figure 6: Extract from NC landslide hazard overlay mapping




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