FAQ

How much less will an Advanced Enviro-Septic™ (AES) or Enviro-Septic™ Wastewater Treatment System cost than a conventional system?

The cost of a system depends on the specifics of the site, the system size and the particulars of your Council’s approval. In general, you can expect that AES™ Technology will cost 20% less than a conventional pipe in a trench with drainage metal system.

When compared to other Aerated Wastewater Treatment Systems (AWTS) with power requirements, complicated computer control systems, compressors or blowers and a variety of pumps the initial AES installed cost will be less but then there will be no ongoing costs - no 6 monthly service inspections required, no power, nothing to break down and requiring replacement. What a choice!

How much smaller is the AES System compared to a conventional system?

The size of a typical AES System varies depending on site and soil conditions, however you can expect at least a 40% reduction in dispersal field size. This should also translate into lower installation costs.

How does the use of a waste disposal or Insinkerator affect AES?

If the tank is properly sized for waste disposal use and equipped with baffles, the AES system’s size does not need to be adjusted. The use of a waste disposal unit adds considerably more solids to a septic system than are usually present. This typically requires a larger septic tank and more frequent pumping out. Please inform your system designer of your intention to install a waste disposal unit for this reason. Often, waste disposals are installed at a later date after the septic tank system has been determined and installed. If this is the case we recommend that the AES bed size is increased by 10%.

What happens if we put something like excess bleach down the toilet / kitchen sink?

While moderate amounts of bleach and disinfectants don’t measurably disrupt the treatment process, excess use can cause the amount of anaerobic bacteria to plummet in the septic tank. However, tests show less disruption and quick recovery of aerobic bacteria in the AES pipes from this disturbance. The self-colonising bacteria involved in the treatment process thrive on regularity yet adapt to the feasts and famines of shock loading and intermittent use by reducing and recolonising on demand without outside intervention. One of the top benefits of an AES system is that it has no filters to be cleaned or complicated electronic or moving parts to break down.  Self-recovery from a myriad of issues can occur, including cases where the micro-organisms responsible for the treatment are chemically poisoned.   One idea is to use a bucket for bleaching and dispose of outside and not down the sink.

What can be planted above the AES treatment field?

Grasses, flowers and shallow-rooted ground covers are the best choices for vegetation over the treatment field. There should be no trees planted within 3 metres of any part of the treatment field to prevent damage to the system from root infiltration. Avoid planting water-loving plants and trees (willows, bamboo, blackwood etc) as well as gardens for human consumption near the drain field.

Can I drive vehicles over the AES treatment field?

Ride on mowers are fine and heavy vehicles only if it was designed for vehicle traffic loading. This involves the construction of load bearing aggregate layers over the AES bed. Driving over an AES field can cause damage if the system was not designed for traffic bearing loading. If your AES System was not designed and/or installed to allow for vehicular traffic, try to keep traffic over the treatment field to a minimum. Use particular caution with the following as they may compact soils and inhibit oxygen to the system:

  • Farm equipment/grazing animals
  • Construction equipment
  • Repeated use of Farm Bikes, ATV’s, motorcycles, etc.
  • Mowing equipment is fine

 Can an irrigation system be used over the AES System?

No. The additional water from irrigation systems could ‘flood’ the system and adversely affect its operation. For the same reason, drains, sump pumps, gutter systems, etc should not discharge into or near the system. Grading and surface diversions (‘swales’) should be located so as to redirect storm water run-off away from the system. The ground surface over the treatment field should be ‘crowned’ in order to prevent ponding of surface water over the treatment field.

Do you have AES installers in my area?

Check the Designers & Installers page on the website for accredited installers in your area.  Alternatively your local drainlayer is only 3 hours away from becoming accredited by completing the on-line course available on our Environment Technology website.

Can I install AES if I have groundwater issues?

Yes.  Tell your designer to look at these technical drawings

High Groundwater Solution 1

High Groundwater Solution 2

Can I install AES on a flat site?

Yes. The usual site conditions will need to be taken into account, such as the permeability of the soil and the depth of the water table below the AES bed. Ask your wastewater designer or call us for advice.

Do I have to vent my AES System?

Yes. The system relies on aerobic bacterial treatment processes, so a supply of oxygen is essential.  Generally a 3 metre vertical height separation between the low level air inlet at the AES bed of 100mm diameter pipe with a simple vent cap and a similar high level air outlet vent is required. There are a number of ways to minimize the visual impact of these vents – the simplest is using the terminal vent on an adjacent building.

Can the house terminal roof vent be used as the high vent?

The house roof terminal vent functions as the high vent as long as there are no restrictions, air inlet points or other vents between the low vent and the roof level vent on the building. A minimum of 80mm diameter or 2 x 50mm diameter vent pipe(s) are required. Please see Venting for more information.

Can the low vent be installed at the distribution (d-box) or splitter box (where this is required in the design) and the high vent be installed at the end of the field?

Yes. The low vent may be attached to the d-box and the high vent may be attached to the end of the field. If this configuration is used in cold climates, the d-box must be insulated to prevent it from freezing.  Please see Venting for more information.

Can the low and high vents be located at same end of field?

Yes. The low vent can be located at the same end of the field as the high vent as long as long as there is a continuous serial connection incorporating all the AES pipes between both inlet and outlet vents. This will mean that there has to be an even number of AES rows in the bed. The high vent will require some support or be constructed of some sufficiently ridged and anchored pipe.

How deep can the AES System be buried?

Usually the limiting factor on how deep an AES System can be buried is the depth to the seasonal high water table or some other restrictive feature. If the soil profile in your area includes relatively impermeable higher level layers and there are free draining horizons at depth and the water table is not a restriction then the AES field can be constructed at a suitable depth to make use of this enhanced permeability.

Should the raised connection components be glued together?

Yes. Glueing is highly recommended to ensure connections remain assembled during the backfill procedures.

The outer fabric does not meet or overlap the AES coupler. Should I be concerned?

No. During installation the fabric will typically reach or cover part of the fitting. We recommend sandwiching the white accelerator fabric within the coupling if possible. If the fabric falls short of reaching the fitting, it is not cause for alarm. Installers can very easily pull or push the pipe to make it slightly longer or shorter. If a space remains between the fabric and fitting, the System Sand will bridge over exposed pipe perforations, preventing additional System Sand from entering the pipe and suspended solids from exiting the pipe.

Why is System Sand so important?

The System Sand that surrounds the AES pipes enhances the supply of oxygen and facilitates efficient dispersal of treated wastewater. In most cases locally supplied washed concrete sand meets the required specification. In order for the System Sand to function optimally, it is critical that the correct type and amount of Sand is used in construction. Installers must use approved sand material, approved either by sieve analysis by a testing laboratory or by supplying a sample to ET for cost free analysis. ‘Spec Checker’ sand analysis equipment is available from ET to installers dealing with a variety of sand sources. See our System sand technical bulletin for an in depth discussion on System Sand functions and the importance of obtaining a sieve analysis.

Should I compact the System Sand after I put it in place?

No. After System Sand is spread between rows we recommended that the installer straddle each row of pipe and walk heel-to-toe its entire length, ensuring that System Sand fills all void spaces beneath and between the AES pipes. Pneumatic-tyred equipment and/or mechanical compactors should not be used to compact System Sand, backfill or fill extension areas. Mechanical compaction will damage the soil’s ability to disburse liquid and may inhibit air supply to the entire system.

Can a septic tank filter be used with AES Technology?

Yes, however, effluent filters are not recommended due to their tendency to cut off the essential air supply to the AES pipe system even when they are properly installed and maintained. This is an issue if the terminal vent on the house is being used as the high level air outlet vent – in other words the air flow to the outlet is dependent upon an air flow across the top of the septic tank.

If you are required by your local authority to use an effluent filter in a gravity fed system, the effluent filter selected must allow the free passage of air to ensure the proper functioning of the system. The design should also incorporate an air bypass to allow for the filter becomeing blocked for any reason including lack of maintenance. If a filter is used the manufacturer’s installation and maintenance instructions should be followed carefully and inspect the filter regularly.

Do septic systems freeze in extremely cold conditions?

No. AES systems were thoroughly tested in Canada in order to confirm that extreme winter conditions do not have an adverse effect on the functioning of the system. In general septic systems are not prone to freezing. Bacterial activity generates heat, and the septic field is regularly dosed with warmer water from the septic tank. Distribution boxes can freeze because of improper venting or a lack of foam insulation, but even this is rare even in cold continental climates.

Do you offer AES design review and inspection classes to health officers and building inspectors?

Regulators, health officers and inspectors are welcome to access our online AES Certification course

Do you have to be an Installer or Designer to undertake AES training?

No. We provide training classes free of charge whether you just want to learn more about our system or if you are seeking certification. Our AES Certification course is available online for all who are interested.

How long does AES Technology last?

If the system is designed, installed and maintained properly, there is no limit to the life expectancy of an AES System. In the very rare event that the system malfunctions due to some form of abuse usually that the air supply is compromised, AES may be rejuvenated in as little as 72 hours by draining the system and restoring the air supply eliminating the need for a replacement.

Still have questions?

Contact us.  If you or your client has any questions please feel free to contact Et on 0800 WasteH20 and any one of our staff will be happy to assist you.