Effluent from a septic tank or a package sewage treatment plant can be discharged into a properly designed and sized drainage field or soakaway also known as drainage field, sub surface irrigation field or herring bone.
The purpose of a soakaway for a septic tank is to biologically treat the effluent by naturally occurring bacteria as it passes through soakaway as well as allowing the water to be distributed into the ground. The role of a soakaway for a sewage treatment plant is purely distributional as the effluent has already been treated in the plant.
A septic tank soakaway will not last forever as it receives high loads of small suspended solids in the waste water. This slowly silts up the soakaway making it less efficient until it is unable to discharge the water into the ground at the same rates as produced by the household, this then leads to the drainage backing up or spilling out.
Sizing and design of a soakaway is standardized under BS6297:2007+A1:2008. Put simply a soakaway is a perforated pipe surrounded in stone, the width and length of the soakaway is determined by the ground conditions, size of flow and quality of discharged effluent.
There are many factors to be taken into account when designing a soakaway including the porosity of the sub soil material, the size of the property and number of residents it is serving and the type of treatment system. This must be carried out professionally and accurately as this part of the system is critical to the effectiveness of the whole drainage system.
Environmental Drain Services Ltd has the expertise to design, specify and install the correct type of soakaway to suit the ground conditions in your area.