Understanding Your Septic System
More than one third of the residents in Scott County use some form of sewage treatment method other than a municipal or city sewer system. This “other method” of treatment is called an Onsite (or sometimes subsurface) Sewage Treatment System (or SSTS). If designed and installed properly, an SSTS can be a cost effective and environmentally safe method of treating wastewater generated within the home.
Sewage contains bacteria, viruses, nutrients, some chemicals, and a small amount of heavy metals. These contaminants must be treated before they reach the groundwater, in order to prevent the spread of disease and environmental contamination. An SSTS can provide a high degree of treatment if the system is properly designed, constructed, and maintained. An SSTS treats sewage by using biological, physical, and chemical processes.
A standard septic system is generally made-up of two parts: a septic tank and a septic drainfield (or soil treatment system). The soil treatment system usually consists of either an in-ground system (trench system) or an aboveground system (mound system). An SSTS professional can determine which type of soil treatment system is needed, simply by analyzing your local soil conditions and determining the depth to the seasonally saturated soil (water table).
All wastewater containing human wastes, nutrients, dirt and other contaminants must be collected and delivered to the septic tank for primary treatment. Bacteria which occur naturally within the waste will begin breaking down the organic materials in the sewage. The wastewater remains in the tank for about 36 hours, which provides enough time for the sewage to settle into three layers. The floating scum layer, which forms near the top of the tank, consists primarily of soaps, greases and toilet paper. The sludge layer contains the heavy organic and inorganic material that settles to the bottom of the tank. The liquid layer, which forms between the scum and sludge layers, consists of water, liquids, and some suspended solids. It is this liquid layer that is allowed to exit the tank to next be treated by the soil treatment system. By settling and capturing all of the solids and preventing them from entering the soil-treatment system, your septic tank will help to extend the life of your drainfield.
To help prevent unwanted materials from leaving the tank, baffles are placed over the inlet and outlet pipes. These baffles stop any floating materials from entering the soil treatment system. If either floating scum or sludge is allowed to enter the soil treatment system, the effective life of the system can be greatly reduced. This will likely lead to the occurrence of expensive repairs!
Solids can enter your soil treatment system if a large amount of water is used in a short period of time. This can occur, for example, if you wash seven loads of laundry in one day rather than washing one load each day of the week. Large quantities of water entering the tank may agitate the existing solids layer, and increase the risk of solids entering the soil treatment system. As the suspended particles are flushed into the soil treatment system by the excess water, those particles can plug pipes or soil pores and slow the rate at which the soil is able to accept wastewater for the final treatment phase. The addition of a garbage disposal in your home without also enlarging your septic tank capacity can introduce more problems for your soil treatment system. The food particles from a garbage disposal tend to be very small, and thus remain suspended longer in the liquid layer within your septic tank. This increases the likelihood that they will flow out into the soil treatment system, again causing premature failure of your soil treatment system. Adequate pumping of your septic tank will help to reduce the chances of that occurring.
Your septic tank should be cleaned (maintained), by a licensed SSTS Maintainer, approximately every two to three years, with the exact frequency depending upon levels of use. The licensed maintainer that you choose will inspect your tank to determine if it needs to be pumped. If pumping is required, they will then remove all of the scum and sludge that have accumulated in your tank. The cleaning of your tank must be performed through the 24-inch tank maintenance hole rather than through one of the 4-inch inspection pipes. As a homeowner, you should make certain that this is the case. Failure to utilize the larger and more centrally located maintenance hole will result in your tank being only partially emptied. This will increase the chances of the remaining solids floating out of your tank as it begins to refill, and finding their way into your soil treatment system where they can damage and shorten the life of your drainfield.
For More Information on Subsurface Sewage Treatment Systems (SSTS):