A septic tank or treatment system treats and disposes of waste water from toilets and kitchens (black water) and bathrooms, laundries (grey water). It is generally made up of a series of processes to break down the waste using bacteria until it is in a suitable form for disposal into the soil (the final filtration process before the water enters the creek/river systems). Such a system is used in non-sewered areas.
Septic testing involves the gathering of information required for the design of a system that is appropriate for the site under investigation. Soils will vary in their ability to absorb waste water (effluent) therefore a geotechnical study of the area is necessary. The soil tester will, in consultation with the client, establish a suitable waste water disposal area. The area will need to be based on number of bedrooms, soil type and setbacks from waterways, recreational areas, boundaries etc. If at all possible we will design the waste water disposal area (land application area) above the Q100 flood levels.
Percolation testing and sampling is carried out to assess the absorption capabilities of the soils. Discussions are held with the client as to the choice of disposal method for the effluent. It may be one of the following procedures:
Disposal Methods:
Note: Not all these options may be appropriate to your site but can be clarified in discussions with our staff.
- Turf Valve: (movable sprinklers)
- – simple
- – reduced costs
- – requires sprinklers to be manually moved
- – < 20% slope
- – NOT used for septic systems
- Fixed Sprinklers:
- – >20% slope
- – doesn’t require manual movement of sprinklers
- – NOT used for septic systems
- – grid of sprinklers fixed in place approx 3m apart
- Surface Drip Irrigation:
- – ease of installation
- – can be used in garden
- – NOT used for septic systems
- Sub surface drip irrigation:
- – can get closer to house than surface spray
- – keeps underground
- – NOT used for septic systems
- Bed (wide trench):
- – can be used for treatment plants or septic systems
- – keeps it underground
- – can be closer to the house
- Trenches:
- – keeps it underground
- – can be closer to the house
- – must fit on block (available area)
- – can be used for treatment plants or septic systems
- Sub surface drip irrigation:
- – can get closer to house than surface spray or drip
- – keeps underground
- – NOT used for septic systems
- AES system
- – Septic style system that produces above advanced secondary level treatment (according to supplier)
- – utilises underground pipes for treatment of waste water after septic tank
- – Total land application area can be reduced