An AOSS is an on-site sewage treatment system that is not a conventional onsite septic system. A typical AOSS in Virginia consist of a, septic tank, treatment unit, pump chamber, conveyance line, distribution system, and an absorption field (trenches, pad, drip tubing, etc.). However, the exact set of components that make up your system will be site and system specific. These non-conventional septic systems include: aerobic tank or ATU’s, peat filter systems, single and recirculation sand filters, mound systems, drip dispersal, spray and low pressure dispersal. Manufacturers of these systems include but are not limited to: Advantex, Aquarobic, Puraflo, Eco-Flo, Whitewater, FAST, BEST, American Drip, and Geoflo. All of these systems are approved for use in Virginia.
These AOSSs allow homes to be built on land that cannot support a traditional septic system. However, to protects public health, the waters of the state and the environment AOSS are regulated in Virginia under 12VAC5-613-140. This regulation requires all AOSS be properly designed, meet minimum performance standards and be properly maintained and inspected at least once a year. It is believed by regulators and manufacturer that proper operation and maintenance of these systems will ensure that all AOSS function as designed. The full text of the regulations can be read at this link.
None of these AOSS systems is ideal and all are expensive to build, maintain and replace. The three chamber system known as aerobic tank or ATU system is becoming the most popular AOSS, but it is sensitive to improper use and maintenance and its air blower and “zoner” only last a couple or three years out in the field resulting in an average annual operating cost of over a thousand dollars. (My system has cost me more than $12,000 in the last 10 years between pumping, inspections, repairs, parts and service calls.) They are great when they work, but you need to baby them. Also, not all licensed inspector are honest or capable. One particular company always finds your tanks in need of pumping (even in a two person household where the tanks were both pumped months earlier. Once that is in the database with the department of health, it must be pumped again.
The other non-traditional systems are essentially other methods of replacing a traditional leach field with other filtering methods. One of the simplest systems to operate is the peat systems like Puraflo and Eco-Flo. These systems have the fewest mechanical parts to fail.
The peat media filter system is a traditional septic tank with peat filtration system instead of a leach field. The filtration system is the aerobic portion of the treatment and is located in tanks which are filled with peat moss over a gravel base. The filtered septic tank effluent is collected under gravity in the pump tank. A timed dosing system pumps the effluent through an inlet manifold located at the base of the treatment modules. An orifice plate is located inside the top of each inlet manifold which allows the flows to be split equally and fed simultaneously to each biofilter module. The inlet manifold is connected to the base of the biofilter module and is fed upwards to a rectangular distribution grid located 6 inches below the top of lid. The effluent percolates laterally and vertically through the depth of the peat fiber treatment media and emerges as a clear, innocuous liquid from the base of the system. The treated effluent is then collected and dispersed.
The peat is an excellent media for allowing the natural secondary treatment of the sewage waste to take place: Absorption and filtration of any impurities chemical adsorption, and microbial assimilation. As a result, these systems are typically capable of removing 90% or more of the polluted mater (characterized as BOD, SS, Coli forms and E. Coli). The life of these systems are 15 years if properly used and maintained (or less with improper use) until the media is exhausted and needs to be replaced.
When the media is exhausted is when the owners of these systems find out what the true operating expense of Puraflo and Eco-Flo is. A Puraflo system will cost in the neighborhood of $1,400-$1,500 per pod while an Eco-flo system will cost approximately $3,500 per unit. This cost should include removing old peat and gravel, cleaning the drainage holes and testing drainage, installing new gravel and peat. The Puraflo peat comes from Ireland (no joke) in 1000 lb bags. Ecoflo peat comes in smaller bags from Canada. Each of the Puraflo pods will take 1.25 bags of peat. Eco-Flo pods take 30 bags of Eco-Flo peat, 15 bags per side of the pod. Additional costs include pumping the system during repairs and replacing landscaping. All in this could cost $15,000 for a 5 bedroom home. This work needs to be done under permit from the Department of Health and should only be done by a trained and licensed service provider who has been certified by the manufacturer.
The peat media filter system is a traditional septic tank with peat filtration system instead of a leach field. The filtration system is the aerobic portion of the treatment and is located in tanks which are filled with peat moss over a gravel base. The filtered septic tank effluent is collected under gravity in the pump tank. A timed dosing system pumps the effluent through an inlet manifold located at the base of the treatment modules. An orifice plate is located inside the top of each inlet manifold which allows the flows to be split equally and fed simultaneously to each biofilter module. The inlet manifold is connected to the base of the biofilter module and is fed upwards to a rectangular distribution grid located 6 inches below the top of lid. The effluent percolates laterally and vertically through the depth of the peat fiber treatment media and emerges as a clear, innocuous liquid from the base of the system. The treated effluent is then collected and dispersed.
The peat is an excellent media for allowing the natural secondary treatment of the sewage waste to take place: Absorption and filtration of any impurities chemical adsorption, and microbial assimilation. As a result, these systems are typically capable of removing 90% or more of the polluted mater (characterized as BOD, SS, Coli forms and E. Coli). The life of these systems are 15 years if properly used and maintained (or less with improper use) until the media is exhausted and needs to be replaced.
When the media is exhausted is when the owners of these systems find out what the true operating expense of Puraflo and Eco-Flo is. A Puraflo system will cost in the neighborhood of $1,400-$1,500 per pod while an Eco-flo system will cost approximately $3,500 per unit. This cost should include removing old peat and gravel, cleaning the drainage holes and testing drainage, installing new gravel and peat. The Puraflo peat comes from Ireland (no joke) in 1000 lb bags. Ecoflo peat comes in smaller bags from Canada. Each of the Puraflo pods will take 1.25 bags of peat. Eco-Flo pods take 30 bags of Eco-Flo peat, 15 bags per side of the pod. Additional costs include pumping the system during repairs and replacing landscaping. All in this could cost $15,000 for a 5 bedroom home. This work needs to be done under permit from the Department of Health and should only be done by a trained and licensed service provider who has been certified by the manufacturer.
Thank you for your informative article. Wayne Franklin
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