Soakaways
HOW DOES A SOAKAWAY WORK
A vital part of any septic tank, the drainage field / soakaway manages the flow of liquids into the surrounding earth. Whether you”re looking to replace an existing drainage field/soakaway, installing a new one or have one in need of vital maintenance, the soakaway construction and installation specialists at Simple Eco can help.
A septic tank and drainage field/soakaway isn’t the best solution for every property. It”s important that when considering soakaway construction, you don”t construct it too close to existing boundaries, buildings or roads. Simple Eco will able to help you assess your property and, if necessary, recommend suitable alternatives – such as a self-contained sewage treatment plant.
The length of the soakaway drains is determined by the number of bedrooms in the property and the porosity of the soil. New regulations state that for any house up to and including 3 bedrooms, the minimum size sewage system that can be installed is for 5 persons, with one extra person added for each extra bedrooms.
The porosity can only be determined by a percolation test which measures the time it takes for water to drop 1mm in the percolation test hole. From this time, known as a V Value, the length of drain required can be calculated.
Soakaways are required to be a minimum of:
- 10m from a watercourse or ditch
- 50m from water abstraction points
- 15m from any building, and sufficiently distant from any other soakaway, including roof water.
- 2 metres from a boundary
Other Regulations:
- The soakaway or drainfield area should be downslope of groundwater sources
- No watr supply pipes or underground services should be within the soakaway area
- No access roads, driveways or paved areas should be within the soakaway areas. This includes fields with tractors and agricultural vehicular traffic.
- The water table or bedrock must not, at any time, be within 1.2 metres of the bottom of the soakaway trench
- No rainwater must be allowed to enter the system – you might consider ”Rainwater Harvesting” instead.
A Looped Soakaway System
Any soakaway is very much dependant on the sub soil permeability. This is most important when considering and planning a new soakaway.
A porosity test can be carried out to determine the size of the soakaway required. The lower the sub soil permeability the bigger/longer a soakaway system needs to be.
Another important factor in the operation of a soakaway is the level of the natural water table in the sub soil. If the water table rises above the base of the soakaway the capacity to function is greatly reduced. We can overcome high water table conditions by the use of an effluent pump unit. These units can be accommodated inside some treatment plants or added separately to the outlet side of a septic tank.
An Effluent Pump In Use
A septic tank soakaway is not the same as a rain water soakaway. Septic tank soakaways disperse slow flows over a 24 hour period. Rain water soakaways disperse high flows over short periods i.e. during heavy showers. If you need advice on a rain water soakaway please contact us.
