Development Application Part 2 of 2 - Plans and Slope Stability Assessment - OPW13/0022

                                                                              4
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                                                                                                                             BOWLER
7 March 2012




Table 2: Summary of Lab Testing
                                                                          -   -   -       -    -




                                              Soil Classification/Emerson Class Number                                                          ,




     TPNo                     Depth               Clay/Silt       Plasticity                       Linear         Liquid Limit       Emerson

                                                     (%)          Index (%)                   Shrinkage (%)           (%)            Number
                                                                                                                                 I
         2                    0.4-0.6     I          75       I      29               I              11.5     I       32         I      2



The fieldwork exercise aiM included    a structural mapping operation of the site and nearby land, by a

geotechnical engineer from this office, on the 9 February 2012, and included mapping of the area for the
following;

     Slope angles
.    Observe existing vegetation
.     Note any evidence of seepage
      Note any evidence of soil creep
.     Note any evidence of previous slips
.
     Geological features

A desktop study was also carried out of published literature of the slope stability over the area to establish
the potential risk of instability as well as likely geology of the site.


4.0          GEOTECHNICAL ASSESSMENT


This assessment was restricted to the captioned site and nearby surrounding land.


The 1 :250 000 Geological Series Map of Gympie indicated the site contained rock from the Myrtle Creek
Sandstone comprising sandstone, shale, siltstone and conglomerate.


The Sunshine Coast Regional Council overlay maps indicated the site to be surrounded by landslide hazard
areas but that the             proposed house location was not in a landslide hazard area (refer Figure 2).

There were no signs of any previous or existing slips within or surrounding the proposed house location.


A quantitative hazard rating has been assigned to the site, the results of which provided a relative frequency
of 0.21 for the natural strata at the proposed locations.                                          This indicates the site has a ’low’ likelihood of
instability. Refer to the Table 2 below for typical implications with respect to site ’risk’level.

Table 2: Risk Level Implications
Risk Level                                                Exam Ie Implications 1
VH                   VERY HIGH RISK                       Extensive           detailed
                                                                                 investigation and research,
                                                          planning     andimplementation of treatment options
                                                          essential to reduce risk to acceptable levels; may be
                                              -

                                                          too expensive and not practical
H                    HIGH RISK                            Detailed investigation, planning and implementation of
                                                          treatment options r                  quired to reduce risk to acceptable
                                                          levels
M                    MODERATE RISK                        Tolerable    provided treatment plan is implemented to
                                                          maintain    or  reduce risks. May be accepted. May
                                                          require     investigation and planning of treatment
                                                          options.
L                    LOW RISK                             Usually accepted.        Treatment requirements and
                                                          responsibility to be defined to maintain or reduce risk.
VL                  VERY LOW RISK                         Acceptable. Manage by normal slope maintenance
                                                          procedures.




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