March 31, 2025
• Reducing pressure on overloaded mains drainage systems
• Potential of bill rebate for surface drainage costs from your sewerage company
• Cost-effective to install, and can be retrofitted relatively easily
Here is what to expect when we build you a soakaway system from 1st Clear flow, a step by step guide to the process so you are aware of all the necessary work needed for the size of soakaway you require.
To ensure that the earth in the selected area is permeable, a soil percolation test is carried out. This involves digging a hole and filling it with water, then waiting to see how long it takes for the water to dissipate. Firstly, a suitable position for the soakaway must be established, by law this must be 5 metres from any walls of the building and at least 2.5 metres from the boundaries of the property.
Infiltration drainage should also not be built if the water table reaches the bottom of the device at any time throughout the year, if there is any contamination in the runoff which could then pollute a nearby groundwater source or resource. A calculation must be made in relation to the size of area where the rainwater will be collected from i.e. roof/gutter size. As a rule, 1 cubic metre of soakaway is sufficient for 50m2 of surface area collecting rainwater, such as the combined area of roofs and hardstanding’s.
As for the soakaway crates, there are several different types available, depending on the area in which it is to be used for example if it’s under a driveway etc. The pit is marked out based on the crate size plus 150mm around each edge, a digger is used to excavate the hole.
Once the hole is dug the pit is then lined with geotextile membrane which is pervious, allowing water to flow through but stops soil entering the void within the crates. The stacked crates are then positioned into the pit and the geotextile is then wrapped around the crates and sealed. Ground gulleys are dug and 110mm drains are laid down from the rainwater downpipes at a slope to the Soakaway connection.
The pit and gulleys are then filled around the sides of the crates and the piping with shingle, 150mm of compacted sand and shingle is added on top to reach ground level where new or removed topsoil and turf can be replaced.
A silt trap can also be fitted upstream of the soakaway if required to prevent sediment or larger particles going into and potentially blocking the soakaway. It collects the particles in a bucket which can be lifted out and cleaned acting as a filter.
At some stage your soakaway could get blocked and need cleaning, common signs that it may be blocked are waterlogged ground around the soakaway and the overflow of drains and pipes leading to the soakaway. The main causes of a blocked soakaway are a build-up of debris including silt and leaves. Flooding due to very heavy rain, a compression of the earth around the soakaway due to traffic, parking or other factors. If the crates used have inspection channels, jet washing, alongside a submersible pump can help remove any silt and debris build up.
