OPW052025 Report - Part 2

5.2             Slope Stability Assessment
5.2.1           Qualitative Assessment
The risk assessment for this project has been conducted following AGS 2007 Practice Note Guidelines for
Landslide Risk Management. Relative levels of risk and their implications are given in Table 2 overleaf
and the Qualitative Terminology for Use in Assessing Risk to Property is also attached in Appendix C.

Table 2: Stability Risk Levels

 Risk Level                        Example Implications (1)
 VH        Very High Risk          Unacceptable without treatment. Extensive detailed investigation and research, planning, and
                                   implementation of treatment options are essential to reduce risk to Low; may be too
                                   expensive and not practical. Work is likely to cost more than value of 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 regulators’ approval) but requires
                                   investigation, planning, and implementation of treatment options to reduce 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 required.
 VL        Very Low Risk           Acceptable. Managed by normal slope maintenance procedures.

Note: (1) 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.

Considering the existing site conditions, and subject to the implementation of recommendations given in
Section 6, it is assessed that there would be a Low (L) Risk of global slope instability affecting the
proposed development. Regulators (NC) normally require that a Very Low or Low Risk of landslide
affecting property must be demonstrated to enable development approval. Summarised in Table 3
overleaf is our qualitative assessment of landslide risk for the site. A summary of qualitative terminology
for use in assessing risk to property is attached in Appendix C (taken from AGS 2007).




Geotechnical Investigation & Slope Stability Assessment
9 April 2025 | 25050-001-Rev0                                                                                                                  14