HYSON-CELLS

all constructed on clay

Relief of hydrostatic pressure

• On the left hand side of the drain the wall is "bleeding" due to seepage of trapped water being released under hydrostatic pressure
• All water on the base has resulted from this "bleeding"
• The site is on "black cotton clay" and there is significant heave at the change from dry to wet seasons. The cells accommodate this heave without fracture.
• No subsurface drains were used
• No expansion joints used
• No non-return valves
• No steel reinforcing required
• The cell fill was 18% "Ashcrete" (waste ash plus cement)
• Drain runs at 8 metres per second