20
10.3.2 Excavation depth:
The excavation depth is determined by the inlet and outlet pipe, invert levels relative to the bottom of
the tank, and allowing for the minimum base thickness shown. Dimension details of the tank are shown
on the relevant drawing, given in section 6. Ground instability e.g. running sand may necessitate over-
excavation and stabilization with hard core or blinding concrete.
Dry site
Wet site
Tank Width. in mm
“a” minimum in mm
“b” minimum in mm
Dry Site
1650
250
250
Wet site
1650
250
300
