Wastewater FAQs

What is the Athens “sewer moratorium?”

By definition, a moratorium is an authorized suspension of some activity. In the case of the sewer moratorium in Athens, at the direction of the State of Tennessee, AUB must comply with very stringent guidelines regarding any new sewer connections. The State mandate, called an Agreed Order, is aimed at minimizing the amount of untreated water that must bypass our collection and treatment process during, for instance, a heavy rainfall. The sewer lines, especially individual service lines going to homes, in the AUB area are fairly old. Many have cracks due to age and tree roots that have wrapped around the pipes. These cracks allow storm water and groundwater to inundate the sewer system, which overloads our pipes and our treatment plant. If the overload is heavy enough, not all of the water can be handled, so some must bypass the treatment process. This is what the moratorium is intended to minimize. By and large, unless a septic tank at a location is failing, AUB cannot connect any new sewer services under the moratorium's conditions. However, some exceptions do apply. AUB is continually working to fix old pipes and sewer lines. As we fix and replace old pipes, we are able to add new services per the moratorium’s conditions.


Why is my sewer bill higher than my water bill?

Simply put, treating wastewater is much more expensive than treating drinking water. Your wastewater bill amount is determined by the amount of water that you use. The reasoning is that water you use at home generally goes to an AUB wastewater treatment plant. Exceptions would be watering a garden, washing a car, and so forth. But the vast majority of residential water used ends up at a treatment plant. Calculating wastewater billing based on water usage is standard to the water utilities industry. To meter wastewater is even more expensive. The solids in wastewater will not pass through a meter unless pretreatment of the wastewater (such as grinding and liquefying) is performed before it goes through the meter.


What is the “availability” charge?

AUB has a cost associated with building and maintaining the infrastructure of our utility systems. Regardless of the amount of electricity, natural gas or water sold, there are fixed operating costs incurred by AUB each month. The availability charge helps recover a portion of these fixed costs. For instance, your mortgage, rent, insurance, etc., are costs that remain fixed month to month even if your income changes. Some of AUB’s fixed costs include:

  • Maintaining the wastewater collection system, pump system and treatment facilites
  • Maintenance of lines and poles, pipes and facilities
  • Interstate natural gas pipeline “demand” charges
  • Natural gas storage facility “reservation” charges
  • Safety and Inspection Programs for Customers


What causes wastewater to back up into my house when it rains?

This is usually caused by a partial blockage in the sewer line. Paper towels, for instance, are the worst culprits when it comes to blocked lines, especially on or near the customer's connection to the AUB wastewater system.


How do you treat wastewater and return it to the environment?


After traveling through the collection lines and reaching the treatment plant, the wastewater runs through a bar screen-a large metal rack with rods placed every few inches-to remove large items such as trash, plastic, rags, sticks, etc. Next, the water flows very slowly through settling tanks where floating material such as oil and grease are skimmed off and where solids settle to the bottom. These solids form what is called “primary sludge,” which, along with the oil and grease, is pumped to a solids treatment process. At this point, the water still contains some solids that must be removed. It then is sent through a secondary, aerated treatment process involving microorganisms. The microorganisms use the remaining solids as their food supply. These microorganisms eventually settle to the bottom as well, as they move through large basins called clarifiers. Some of these are circulated back through the process to continue their cleaning work, while others are simply removed as the colony of organisms grows. (Solids that are removed after the primary and secondary treatment phases go through a solids digestion process, where they are heated in the presence of still other biological organisms. After digestion takes place, the remaining material can be reused beneficially, such as to condition and fertilize agricultural soil.) As for the clarified water, it travels from secondary treatment through tanks or channels where either chlorine, ultraviolet light, or a combination of both, are used for disinfection. The clean, disinfected water can now be returned to the environment.


Can I tour a wastewater treatment plant?

Yes. AUB is happy to provide tours to individuals and groups. To arrange a tour, just call us at (423) 745-4501 and tell the person you speak with that you would like to learn more about our processes by taking a tour.