Drainage Field Soakaway Systems
Soakaway systems have a drainage field, which is a shallow, covered excavation made in unsaturated soil. Pre-treated wastewater is discharged through piping onto porous surfaces that allow wastewater to filter through the soil. The soil accepts, treats, and disperses wastewater as it percolates through the soil, ultimately discharging to groundwater.
Stage 1
Percolation Test
A percolation test is required to determine whether a soakaway system installation can be carried out at a property. The percolation test is to identify if the soil is suitable, and it will also determine the size of the drainage field.
Stage 2
Calculate Vp
The Vp is calculated using the measurement of soil porosity gained from the percolation test and the number of people served by the tank.
Stage 3
Excavate and Install Drainage Field
Once the size has been established, the correct area will be excavated, and a slotted drainage pipe will be installed in a continuous loop.
Drainage fields
The design of a drainage field system works to disperse partially-treated effluent. As a result, it serves as a critical final stage for off-mains drainage. Such a setup is vital for septic tanks. This is because the law restricts them from discharging straight into watercourses.
Drainage field systems also serve as an effective alternative to sewage treatment plants. This applies in areas of limited watercourse access. The system filters the waste through the soil. This ensures further treatment and safe ground dispersal. Before installation begins, accurate porosity and percolation tests need to take place. These tests verify that the receiving ground has the necessary absorption capacity.
Drainage fields typically consist of a system of slotted irrigation pipes, which allow the effluent to percolate into the surrounding soil. Biological treatment then takes place naturally in the aerated layers of soil to ensure that the correct discharge and treatment of foul water has occurred.
The appropriate design of a drainage field is covered in BS6279, and is also well documented in Building Regulations Document H and the Environment Agency PPG4 Document. Albeit less common than previously, drainage fields still offer a viable route for those who require a discharge of treated/partially treated effluent.
Our Working Process
Get In Touch
Give us a quick call and explain if you require a new drainage field or the replacement of an existing field.
Percolation Test
We require a percolation test to be carried out before any soakaway installation, as a requirement from building control. This will determine the size of the required field.
Evaluate figure and provide a quote
Our engineers will evaluate the figures of the percolation test, calculate the required size of the field, and provide a quote for this.
Excavate and Install
We will then excavate the required area, install the drainage field pipe, have an inspection from building control and then reinstate the area.