Venting the BIOROCK

BIOROCK Venting Guidelines

The venting for the BIOROCK Sewage Treatment System is site specific, which is why we emphasise the need for recommended installers to install the plant. However, there are some rules that must always be obeyed in order that the BIOROCK receives enough air to oxygenate the media correctly.

Both the Biorock Filter and the Settlement or Septic Tank must be vented independently.  They share a common Air Inlet but a separate Air Outlet Vent must be provided for each tank, just as every fireplace must have its own chimney in order for the draw to be sufficient.

Like a chimney, the pipework must have as little restriction to airflow as possible. This is achieved by the following:

• As short a lateral distance between the respective tank and vertical chimney as possible.
• The underground section of the Air Outlet Vent connecting the respective tank to the vertical section of the Air Outlet Vent (chimney) must slope upwards, all the way, towards the chimney.
• The underground section of the Air Outlet Vents should run in a straight line from the respective tank to the vertical section of the Air Outlet Vent (chimney).  If this is not possible, the underground section of the Air Outlet Vents must have no more than one directional bend.  If a directional bend is required it must be a sweeping bend, not a 90 degree bend.
• The air outlet pipes MUST be situated in clear, open air space, not surrounded by trees, tall structures, at the bottom of a slope, etc. as this will stop the air currents and may even cause down-draughts. The Biorock cannot work unless the venting is correct. Please use a trained installer as venting is site specific.

The minimum vertical difference between the top of the Air Inlet and the top of the Air Outlets is as follows:

• 5 metres with a normal rain cowl fitted
• 4 metres with a wind fan fitted.

The heights above are MINIMUM differences. Your site may require higher air outlet pipes, depending on the site restrictions to airflow.

The required airflow volumes to the Biorock are as follows:

BIOROCK 6  11M³/Hour

BIOROCK 10 22M³/Hour

BIOROCK 15 33M³/Hour

In order that the airflow is enough, it must be checked on a still day with an Anomometer.

The ventilation pipework must have an internal diameter of no less than 100mm.

The Air Outlet Vent must be as close to the respective tank as possible and no further than 10m away.

Where the Soil Vent Pipe on the house is within 10m of the Settlement Tank then this will act as its Air Outlet Vent and no additional pipe work is required for the Settlement Tank. 

No air admittance valves or other obstructions to air flow should be fitted to any part of the air ventilation system.

The top of the Air Outlet Vents must be open to the wind and air currents.  They must not be sited in the vicinity of trees, bushes, at the bottom of a slope or hill or other structures that may act as a wind break and protect the top of the Air Outlet Vents from wind and air currents.

 If the Air Outlet Vents are run up walls, posts or other structures then the top of the vent must clear the top of the support structure by a minimum of 300mm.

Examples of incorrect venting - why you need TRAINED, competent BIOROCK installers!

This vent from the BIOROCK is not high enough. It is around 1.4M tall. There is no possibility of enough air being drawn through the plant. It is also sited underneath a tree.

 This vent pipe from the BIOROCK has its opening suffocated by foliage and branches. The draw will be severely restricted. The pole is also blocking the wind when it comes from the direction of the pole. The vent pipe must be in open airspace at least 300mm. clear of the top of the pole.

  This house is using the existing Soil Vent Pipe as the vent for the settlement tank. Unfortunately, it cannot work as the vent air flow is blocked by the wall itself. The vent pipe should be extended to clear the roof line.

Example of correct venting by a TRAINED BIOROCK installer

This vent pipe is 5 metres tall and the top is positioned well clear of the support pole. It is 60 metres away from taller trees and also has a wind fan fitted to help with the air flow on calm days. This plant is achieving a superb effluent quality in single figures and the owners are delighted with the system.