B a c calculate the roof area to be drained into each soakaway section plan view.
Soakaway size roof.
In most cases where the soil drains well and the roof area is less than 100m2 you will be able to construct an open chamber type soakaway as follows.
One of the first things to consider when choosing a site for a soakaway is the water table aka saturation line.
A soakaway is a large hole dug into the ground usually around 5 8 metres away from a property or in the middle of a garden.
If surface water from roof drains to driveway calculate roof area.
The two determining factors for soakaway success are the size of the area or volume of water to be drained and the percolation rate of the soil sub soil or in some sites the depth to the water table.
For example 50m2 roof area requires a rubble filled soakaway of 50m 2.
If you have several different surface areas connecting to the same soakaway roof gutter conservatory patio driveway etc then more.
So 10 l x 6 2 w 30 m2 is roof area of one side of roof.
Rainwater from roof gutters conservatories driveways patios and gardens is diverted into it where it then seeps into the ground.
As a broad brush a soakaway size of 1m is sufficient to drain a roof area of approximately 50 square metres under normal conditions.
A soakaway is a tank or trench where water is stored and allowed to soak into the ground rather than discharging to an outfall or sewer.
To calculate the size volume of a rubble filled soakaway the same calculation can be used but the result divided by 0 3.
The most common size of soakaway for residential use is 1 cubic metre 1m as this is what most local authorities seem to specify.
The size volume of the soakaway should be based on a drainage calculation this is relatively easy once a drainage percolation test is completed and you know the surface area where the water is coming from.
1 what is a soakaway.
