Attenuation Tank Installation

Toolbox Talk Record

Ref: TBT-GRW-011  |  Issue: 1  |  Date: March 2026
PresenterProject
LocationDate

What?

Why?

Excavation collapseDeep, wide excavations for attenuation tanks create significant collapse risk if sides are not properly supported.
Crush injuriesPrecast tank sections and heavy crate pallets cause fatal crush injuries if lifting and handling are not controlled.
System performanceIncorrect installation, punctured membranes, or poor backfilling can cause the system to fail and result in flooding.
Do Don't
  • Support or batter excavation sides before anyone enters the tank excavation.
  • Use a lift plan for placing precast sections or heavy crate pallets.
  • Inspect geomembrane wrapping for punctures before and during backfilling.
  • Follow the designer backfill specification for material type and compaction.
  • Secure lightweight geocellular crates against wind displacement during installation.
  • Dewater the excavation to keep the formation dry for tank placement.
  • Ensure safe access and egress is provided within the excavation at all times.
  • Check for buried services before excavating the tank formation area.
  • Obtain temporary works approval if traffic loads will cross the excavation.
  • Record installation details including membrane integrity checks for handover.
  • DON'T enter unsupported excavations for attenuation tank installation.
  • DON'T lift precast tank sections without an approved lift plan in place.
  • DON'T puncture the geomembrane with tools, boots, or sharp aggregate.
  • DON'T backfill with materials that differ from the designer specification.
  • DON'T place heavy plant or traffic loads over the tank without design approval.
  • DON'T leave lightweight crate systems unsecured in windy conditions on site.
  • DON'T compact backfill directly against geocellular crates without protection.
  • DON'T allow water to accumulate in the excavation during tank placement.
  • DON'T skip buried service checks before starting the excavation work.
  • DON'T deviate from the installation sequence in the method statement.

See also: Below Ground Drainage Installation | Excavation Safety Awareness