Table 2   Site Factors S
(a) For general structures

Soil profile

 Site factor (S)

A profile of rock materials with rock strength Class L (low) or better

 0.67
A soil profile with either:
(a) rock materials Class EL (extreme low) or VL (very low)
     characterized by shear wave velocities greater than 760 m/s; or
(b) not more than 30 m of:
         medium dense to very  dense coarse sands and gravels;
         firm, stiff or hard clays; or
         controlled fill		 1.0
A soil profile with more than 30 m of:
      medium dense to very dense coarse sands and gravels;
      firm, stiff or hard clays; or
      controlled fill		 1.25
A soil profile with a total depth of 20 m or more and containing 6 to
12 m of:
      very soft to soft clays;
      very loose or loose sands;
      silts; or
      uncontrolled fill		 1.5
A soil profile with more than 12 m of:
      very soft to soft clays;
      very loose or loose sands;
      silts; or
      uncontrolled fill
characterized by shear wave velocities less than 150 m/s		 2.0

 

(b) For domestic structures

Soil profile

 Site factor (S)

Normal soil: any soil profile other than soft

 1.0
Soft soil: any soil profile with more than 5 m of:
        soft clay;
        loose sand;
        silt; or
        uncontrolled fill		 2.0