Approved Plans & Documents - EXE22/0017

PRACTICE NOTE GUIDELINES FOR LANDSLIDE RISK MANAGEMENT 2007
APPENDIX C: LANDSLIDE RISK ASSESSMENT
QUALITATIVE TERMINOLOGY FOR USE IN ASSESSING RISK TO PROPERTY

QUALITATIVE MEASURES OF LIKELIHOOD

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Approximate Annual Probability Faptboa taditavelinudsial Af gk 5 iglia a
Indicative Notional Recurrence Interval
Value Boundary
107 Sak 10 years The event is expected to occur over the design life, ALMOST CERTAIN A
ts 10 years 20 years The event will probably occur under adverse conditions over the | aeppy #
design life. SER
3
pxy a 1000 years ere ‘The event could occur under adverse conditions over the design life. _| POSSIBLE c
5x10 : :
Tsond yee The event might oceur under very adverse cirumstences over he [on neat y 5
5x10> 20,000 years abt = = - =
B 100,000 years The event is ennesivable but only under exceptional circumstances | RARE z
5 , over the design life.
10 RAT 1,000,000 years 200.000 vears [The event is inconceivable or fanciful over the design life. BARELY CREDIBLE F
Note: (1) The table should be used from left to right; use Approximate Annual Probability or Description to assign Descriptor, not vice versa.
QUALITATIVE MEASURES OF CONSEQUENCES TO PROPERTY
Approximate Cost of Damage
SSarsaive Notional Description Descriptor Level
indi D
Value Boundary
pps, Siructure(s) completely destroyed and/or large scale damage requiring major engineering works for BMaeTROne
a stabilisation. Could cause at least one adjacent property major consequence damage.
teo% Extensive damage to most of structure, and/or extending beyond site boundaries requiring significant
60% Bee i 5; MAJOR 2
ne) stabilisation works. Could cause at least one adjacent property medium consequence damage.
ange Moderate damage to some of structure, and/or significant part of site requiring large stabilisation works. =
20% : a MEDIUM 3
1am Could cause at least one adjacent property minor consequence damage.
5% tee Limited damage to part of structure, and/or part of site requiring some reinstatement stabilisation works. MINOR 4
Little damage. (Note for high probability event (Almost Certain), this category may be subdivided at a
%
0.5% notional boundary of 0.1%. See Risk Matrix.) EISTEICAN? 5
Notes: (2) The Approximate Cost of Damage is expressed as a percentage of market value, being the cost of the improved value of the unaffected property which includes the land plus the
unaffected structures.
(3) The Approximate Cost is to be an estimate of the direct cost of the damage. such as the cost of reinstatement of the damaged portion of the property (land plus structures), stabilisation

works required to render the site to tolerable risk level for the landslide which has occurred and professional design fees, and consequential costs such as legal fees, temporary
accommodation. It does not include additional stabilisation works to address other landslides which may affect the property.
(4) The table should be used from left to right; use Approximate Cost of Damage or Description to assign Descriptor. not vice versa

91 Australian Geomechanics Vol 42 No 1 March 2007