Appendix B - Global Stability Assessment Report

EXAMPLES OF GOOD HILLSIDE PRACTICE

Vegetation retained

  
 
 
 
  
  
  
 
 
  
 
    
  
   

Surface water interception drainage

Watertight, adequately sited and founded \
rool water storage lanks (with due regard for \
impact of potential feakage)) ————_______

Flexible structure
Roof water piped off site or stored
On-site detention tanks, watertight and

adequately founded. Potential leakage
managed by sub-soil drains ~~.

Vegetation retained ~~ MANTLE OF SOIL AND ROCK

  

   
 
 
  

a FRAGMENTS (COLLUVIUM)
i OFF STREET ~ Pier footings into rock
~ PARAS “—- Subsoil drainage may be
required in slope

‘— Cutting and filling minimised in development
‘~~ Sewage effluent pumped out or connected to sewer.

Tanks adequately founded and watertight. Potential
leakage managed by sub-soll drains

\——~ Engineered retaining walls with both surface and
subsurface drainage (constructed before dwelling)

EXAMPLES OF POOR HILLSIDE PRACTICE

Unstabilised rock topples
and travels downslope

 

Vegetation removed

 
  
   
 
   
 
 
 
 
  
  
 
 
   
 
 
 
 
  
 
   
  

Discharges of roatwater soak Steop unsupported
away rather than conducted off cut falls
site or to secure storage for re-use

 

Structure unatle to tolerate
setiement and cracks

Poorly compacted fill setties
unevenly and cracks pool

Inadequate walling unable
to support fill

Loose, saturated fil shdes

and possibly flows downsiope
Inadequately supported cut fails — Roofwater introduced into'slope
Saturated ,
slope fails \

Vegetation so. _ . Dwelling not founded in bedrock
removed i gfe : 4

Mad flow i wy
ie

 

Absence of subsoil drainage within fit
*\——— Ponded water enters slope and activates landslide

~Possible travel dowaslope which impacts other development downhill

This figure is an extract from PRACTICE NOTE GUIDELINES FOR LAND SLIDE RISK MANAGEMENT as presented in
Australian Geomechanics Journal and News, Volume 42, No 1, March 2007, which discusses the matter more fully.