RFI -Attachment 6 - Geotechnical Investigation Report CORE.pdf

Walsh Consulting Engineers



Exposed soil (i.e. on batters or drains etc.) should be protected from erosion and scour by appropriate
measures such as re-vegetation and hydro-seeding, protective matting, or hard facings. Concentrating
surface runoff should be avoided unless adequate erosion/scour protection and flow dissipation is
constructed. Temporary sediment control should be adopted during construction where surface water will
flow offsite.

6.5         Drainage
Site drainage should be designed to readily remove surface water, minimise water infiltration into the slope,
and to prevent ponding of water on subgrade areas during construction and also adjacent to foundations,
perimeter slabs, and driveways once construction is completed.
Roof water, including overflow from rainwater tanks, and water collected from hard surfaces (e.g. driveways)
must be directed by pipes or lined channels to a legal point of discharge.
Shallow subsurface cut-off drains should be installed upslope of building areas in order to intercept and
divert potential subsurface seepage. Diversion drains should be constructed above the crest of any cut or fill
embankments.

6.6         Aggressivity of soils
Chemical analysis can provide an indication of the potential for long term damage to foundations, buried
pipelines, in-ground structures, services and other infrastructure. Soil texture is also important in this regard,
as granular soils allow oxygen exchange (oxidation) to occur more readily and are also more permeable.
Australian Standard AS 2159-2009 Piling - Design and installation provides the range of exposure
classification of the surface of steel piles and concrete piles based on the range of chemical conditions in the
soil and the possibility of changes in groundwater levels.
Table 4 displays the exposure classifications for steel and concrete piles in soil, based on the results of
laboratory testing on selected samples, in accordance with Table 6.4.2(C) and Table 6.5.2(C) of AS 2159-
2009.
Table 4: Soil aggressivity exposure classifications.
                   Sample                                                 Exposure                Exposure
  Sample                        Geological        Material Type
                    Depth                                             classification for      classification for
  Location                        Origin            (USCS)
                  (m BGL)                                             steel piles in soil   concrete piles in soil

      BH6        0.4 – 1.1     Aeolian Soil        Sand (SP)           Non-aggressive         Non-aggressive



7.0      ASSESSMENT OF LAND STABILITY
7.1    Existing Condition
The Noosa Planning Scheme 2020 includes a landslide hazard overlay map. The overlay map indicates that
the site includes moderate and high landslide hazard areas. Image 5 below presents an extract of the
overlay map.




J001390-001-R-Rev0                                     9