slope stability · MCU22/0172

Integra Partnerships                                                                           22339-001-Rev0
                                                                                            13 September 2022

2.3    Groundwater
No signs of groundwater seepage (‘springs’) were observed during our walk-over, nor was groundwater
encountered in the boreholes, with soils being moist.

2.4    Surface Drainage
Most of the stormwater catchment (to the north-east of the property) is anticipated to be intercepted by the
existing infrastructure along Katharina Street and existing grated stormwater inlet pits within the upslope unit
complex driveway. Given the sandy nature of the site and surrounds, rainfall would normally be anticipated
to infiltrate the ground surface. No evidence of significant erosion was observed across the subject site.

2.5    Vegetation
Landscaping was present around the perimeter of the residence, comprising shrubbery and several mature
trees. The mature trees were noted to be relatively straight, exhibiting no obvious signs of distortion which
could be indicative of global slope instability.

2.6    Buildings and Other Structures
The existing residence was a single storey, cut in, slab on ground, brick veneer structure. Terracing by
previous earthworks had occurred during the original construction, supported by masonry blockwork (1.3 m
height) and brick retaining walls (0.7 m height). Landscaping timber sleeper walls approx. 0.6 m in height
were noted beside the existing house midway along the southern boundary.
Based on an external assessment, visible areas of the existing structures and retaining walls appeared to be
in good structural condition and did not exhibit any signs of distress (e.g. cracking, misalignment, etc.) which
could be attributed to slope instability. ‘Hairline’ cracking was observed within the concrete driveway and
within the asphalt along Grant Street.
The timber fences surrounding the property were observed to be slightly ‘wavy’, however this could be
attributed to founding within the very loose to loose sands encountered in the boreholes. The grouted rock
retaining wall on Grant Street (Text Figure 8 above) was observed to be relatively straight and in generally
good condition.



3.0     ASSESSMENT OF LAND STABILITY
3.1    Existing Conditions
The Noosa Council (NC) Planning Scheme 2020 includes a landslide hazard overlay map (Ref. extract in
Text Figure 9), which indicates that parts of the site (including the proposed development area) are within a
Moderate (pale brown shading) landslide hazard zone.


                         Subject Site




Text Figure 9: Extract from NC landslide hazard overlay mapping




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