Calculation tools

We undertake an extensive range of calculation services for our products and solutions to make your job easier. Below you will find our calculators for stormwater attenuation tank sizing and flotation.

Tank dimensions calculator

Attenuation tank sizing
The required capacity for attenuation tanks depends on a number of factors which are unique to each project.

We can model the circumstances on a project using Microdrain software to calculate the volume of water storage required. To undertake this exercise, we need the following information:

  • Impermeable drained area (i.e. roads/car parks)
  • Max. rate of discharge permitted from the site
  • Storm return period, now typically 1 in 100 yrs
  • Geographical location
  • Approx. depth of drainage system
  • Plan area where attenuation is to be located

Flotation calculator

In some situations, particularly where the groundwater level is high relative to the tank, there might be a risk of flotation.

Given the tank dimensions, invert level and groundwater level, we can undertake a check calculation and establish whether any special measures are needed.

Factor of safety against flotation must be equal to or greater than 1.2.