Slope Stability Report · EXE22/0013

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 nature of the
       through the                  Rare               Minor           Very Low       underlying soils, the gentle gradients
       residual soils on                                                              of the natural slope. The consequence
       slopes <15 º                                                                   of such instability would be Minor with
                                                                                      the resultant risk being Very Low.
  2.   Failure of existing                                                            This has been assigned as almost
       timber retaining            Almost          Insignificant          Low         certain due to the observed
       walls located to the        Certain                                            performance of the existing timber
       rear of the                                                                    type retaining walls. The consequence
       property.                                                                      would be insignificant due to the
                                                                                      landscape nature and height of walls
                                                                                      (<1.0 m) with the resultant risk being
                                                                                      Low . The design and construction of
                                                                                      these walls had not been supplied,
                                                                                      therefore have not been
                                                                                      independently verified by STA. The
                                                                                      stability/ integrity of the existing
                                                                                      retaining walls remain 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 ‘Low’. This level of risk is acceptable; manage by
normal slope maintenance procedures.