What is an evapotranspiration bed?
An evapotranspiration (ET) bed treats wastewater by using evapotranspiration the loss of water from the soil by evaporation and by transpiration from plants growing there. In lined systems, the ET bed is lined with a natural clay, synthetic or concrete liner.
How do you make an absorption trench?
Absorption trenches are excavated and the bottom filled with aggregate or crushed rock. Either perforated piping, self-supporting arch trenching or box trenching is placed in the trench. The piping is layered over with geotextile fabric, hay or newspaper, several centimetres of sand and then soil.
What is aerobic septic system?
Aerobic Wastewater Treatment Aerobic bacteria convert organic matter into new biomass and carbon dioxide while air is continuously circulated throughout the tank. The air that is forced into the tank mixes with the wastewater and the microorganisms feed on the waste that is found in the water.
What is ETA bed?
An evapotranspiration absorption bed. Evapotranspiration absorption (ETA) beds reduce reliance on effluent absorption into the soil by maximising water loss through evaporation and transpiration. Effluent is distributed through the bed by a system of slotted pipes.
What does an absorption trench do?
Absorption trenches or beds are used to release effluent below the surface through narrow and deep trenches, or wide and shallow beds. Effluent flows by gravity or is pumped along the length of the trench or bed through distribution pipes, and is then filtered through gravel or sand to the underlying soil.
How deep should a trench be?
Trenches 5 feet (1.5 meters) deep or greater require a protective system unless the excavation is made entirely in stable rock. If less than 5 feet deep, a competent person may determine that a protective system is not required.
What is water absorption trench?
Water-absorbing trenches are shallow excavations designed along the contour slopes of a site. They create temporary sub-surface storage of stormwater runoff, thereby enhancing the natural capacity of the ground to store and drain water.
At what depth must an excavation be supported?
*Each country will have specific regulations. For example, OSHA in the United States still specifies a depth that trench shoring must be used, which is currently 5 ft or 1.5 metres deep. However, if the trench is less than this depth, a competent person must determine if a protective system is required.
When to use an evapotranspiration bed ( et )?
ET beds are used where the soil cannot treat wastewater before it percolates to groundwater, such as in rocky soils, or where the soil prevents wastewater from percolating from the application field, such as in heavy clay soils. ET systems are designed according to local evapotranspiration and rainfall rates, which vary across Texas.
How is effluent distributed in an evapotranspiration absorption bed?
Effluent is distributed through the bed by a system of slotted pipes. Vegetation cover must be well maintained to ensure strong growth for maximum uptake by transpiration. The surrounding landscape and vegetation must also be maintained to minimise shading and maximise exposure.
What is the process of evapotranspiration in plants?
An evapotranspiration absorption bed. Cross section of an ETA bed (unlined) (after Patterson, 2006). Evapotranspiration is the process that removes water from land covered by vegetation through evaporation (loss of water from soil or wet vegetation) and transpiration (loss of water from small openings in the leaves of plants and grasses).
When is the base of a bed used for percolation?
When the base of the bed is used for soil absorption (percolation) of effluent in addition to the evaporative demand of the surface, the system is called an evapotranspiration/absorption bed (ETA). The term ET/A is used to describe both an ET bed and an ETA bed.
