Slope Stability Report

The potential implications for the associated risk level are outlined within the table below:‐
        Risk Level                                            Implications
  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 the value of the 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 regulator’s approval)
                           but requires investigation, planning and implementation of treatment options
                           to reduce the 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 is required.
  VL (Very Low Risk)       Acceptable. Manage by normal slope maintenance procedures.
Note: 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.

 The table below outlines our qualitative assessment of landslide risk for the development site.
         Hazard           Likelihood Consequence          Assessed                 Comments
                                        to Property         Risk
  1.   Shallow failure                                                                Rare due to the gentle gradients of the
       through the                  Rare               Minor           Very Low       natural slope and to the extent of
       residual soils on                                                              development including retaining walls
       slopes <15 º                                                                   adjoining the site. The consequence of
                                                                                      such instability would be Minor with
                                                                                      the resultant risk being Very Low.
  2.   Failure of the                                                                 This has been assigned as possible due
       existing timber            Possible         Insignificant       Very Low       to the wall being of timber
       retaining walls to                                                             construction and the limited lifespan
       the Northern and                                                               expected for timber walls. The
       Eastern boundary                                                               consequence of failure would be
       lines.                                                                         insignificant with the resultant risk
                                                                                      being Very Low. Note, the design and
                                                                                      construction details of these walls had
                                                                                      not been supplied, therefore have not
                                                                                      been independently verified by STA.
                                                                                      The stability/ integrity of the existing
                                                                                      retaining walls remains the
                                                                                      responsibility of the owner/ builder
                                                                                      and design engineers.
  3.   Deep seated failure                                                            Whilst the consequence of such a
       within the residual         Barely              Major           Very Low       failure would be major, the likelihood
       soil profile or            Credible                                            is barley credible due to relatively
       weathered rock.                                                                gentle gradients and absence of
                                                                                      evidence of instability of such nature.
                                                                                      The resultant risk is Very Low.

 On the basis of the qualitative risk assessment of likelihood and consequence presented in the table
 above, the risk of the area assessed is determined as ‘Very Low’. This level of risk is acceptable;
 manage by normal slope maintenance procedures.