Aerobic septic systems: service, alarms and monitoring contracts

If your septic system has an electrical panel, a small air pump humming somewhere in the yard and an alarm light, it is almost certainly an aerobic treatment unit (ATU). Instead of only letting solids settle, an ATU pushes air into the wastewater so oxygen-loving bacteria can break it down more completely. Arkansas rules treat these units as secondary treatment. The soil guide explains when the ground on a lot pushes the design toward an alternative like this.

What Arkansas requires of an aerobic unit

• An approved model. Only ATUs authorized by the Department of Health may be used, and they must be listed under NSF/ANSI Standard 40.
• An alarm that cannot be unplugged quietly. Appendix D of the onsite rules requires a visible and audible warning device in a conspicuous spot, wired separately from the unit so that cutting the unit's power sets off the alarm.
• A monitoring contract for the life of the system. Owners of alternative systems and holding tanks must keep a contract with a monitoring person registered with the department. Homeowners are not allowed to monitor their own system, and for proprietary units the monitor has to be authorized by the manufacturer.
• Assessments every six months. The contract has to provide for an assessment at least twice a year, covering the system's components, and each report goes to the homeowner, the local health unit and the department's database.
• A licensed installer. Alternate systems must be put in by a licensed installer, and some manufacturers require extra certification to install or maintain their units.

The department also issues a separate Onsite Maintenance Provider license, with its own exam, for the people who service these systems.

Units that discharge to the surface

Some aerobic systems release treated water to a ditch or stream instead of a buried field. The rules allow that only on sites where the soil does not meet the standard for a conventional system, and those discharges fall under the state's general permit for individual home treatment facilities (ARG550000). Water leaving a surface-discharging system must be disinfected first; chlorine, ozone and ultraviolet light are the accepted methods, and a chlorinator has to produce at least a 10 parts per million solution at peak flow.

When the alarm goes off

The rules require the alarm to warn the people in the house of a malfunction or failure, so treat it as a real signal rather than a nuisance to silence. Practical steps while you wait for service:

1. Cut water use: hold off on laundry, the dishwasher and long showers.
2. Look at the panel and note which light is on and whether the air pump is running.
3. Leave the lids on. The ADH rules flag open maintenance ports near the ground as an accident hazard, and the inside of a tank is no place for a homeowner.
4. Call the company on your monitoring contract, or call us and we will pass it to a licensed contractor who works on aerobic units.

Pumping an aerobic system

Aerobic units still collect sludge and still need pumping. EPA suggests alternative systems be inspected about once a year, more often than a conventional tank, and the six-month assessments are where sludge levels get tracked. When pumping is due, see septic tank pumping; for a broken air pump or other failed part, see septic repair.

Buying a house with an aerobic system

Ask for the current monitoring contract and the recent assessment reports. A contract that lapsed years ago usually means nobody has been watching the unit. Our septic inspection guide lists the other records worth requesting.

Questions people ask

Can I service my own aerobic septic system in Arkansas?

Not for the required monitoring. The ADH rules say no homeowner may monitor their own system; assessments must be done by a monitoring person registered with the department under a contract that lasts for the life of the system.

How often does an aerobic system need a service visit?

The rules require an assessment at least every six months under the monitoring contract. Pumping happens when those checks show the sludge has built up.

Why does my aerobic system smell like chlorine?

Units that discharge treated water above ground must disinfect it first, and chlorination is one of the methods the rules accept. A strong sewage smell instead is a reason to call for service.