What is a septic system?

What are the components and function of a "typical" septic system?

The septic tank component.

What is a Soil Absorption System (SAS)?

What are the different types of soil absorption?

What are the possible signs and causes of a failing septic system?

How can I contact local regulators?

 

What is a septic system?
The privately owned wastewater treatment system (POWTS) is an effective, long-standing method for collecting, treating, and disposing of sewage from rural and suburban homes and businesses. Septic systems are used in every country and in the majority of Wisconsin rural homes. Simply put, the raw wastewater from your home or business is being disposed of on the property rather than being piped to a municipal sewage treatment plant.

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What are the components and function of a "typical" septic system?
In a typical modern system, wastewater flows from a house or building to a septic tank and finally to an absorption area (In certain situations a dosing tank is required when the effluent from the septic tank can not be fed to the absorption field by way of gravity).

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The Septic Tank Component.
The modern tank is normally constructed of prefabricated reinforced concrete. The tank (assuming watertight integrity) is normally "full" of liquid and waste all the time. Therefore, if 100 gallons of water is discharged to the septic tank, it will push 100 gallons of effluent (clarified wastewater) out of the tank to the absorption area (or pump chamber). After entering a properly sized tank, the wastewater separates as either floating debris (i.e. greases) referred to as the "scum layer", more dense solids which settle to the bottom commonly called "sludge" and effluent the clarified wastewater between the scum and sludge layers. Minimal treatment does occur in the septic tank, anaerobic bacterial action and the conversion of organic nitrogen to ammonia. The anaerobic treatment is slow and incomplete and therefore the tank requires pumping (performed only by a licensed septage hauler) a minimum of every three years. Finally, something should be said of the baffles and/or outlet filter (if present). The baffles, which are probably the most important component of the tank, cover both the inlet and outlet openings inside of the tank. The baffles direct the flow so that only the clarified effluent flows to the absorption area (again a pump chamber may be necessary). Systems installed after July of 2000 require a filter be placed at the outlet of the tank. The filter replaces the outlet baffle and prevents an additional 10-25% of suspended particles from leaving the tank. Under "normal" usage the filters are cleaned every three years.

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What is a Soil Absorption System (SAS)?
The SAS (commonly referred to as the drainfield) is a component consisting of sands and/or other textural material and gravel which serves as the final stage of the wastewater treatment process. Typically, in this region four types of absorption components are commonly installed: conventional below grade (non-pressurized), below-grade (pressurized), at-grade and mound. In any instance, the absorption areas basically work under the same concept. Clarified liquid waste (effluent) is dispersed either by gravity (trickle flow) or via a pumping system (dosing) into the soil absorption system. Refer to each individual system for more detailed information.

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Different types of Soil Absorption System (SAS)

   Non-Pressurized Below Grade "Conventional Component"
The modern conventional soil absorption system (SAS) is a trench design using either perforated pipe and gravel or graveless leaching chambers. The aggregate trench distributes the effluent by gravity through a four-inch perforated distribution pipe. A more recent alternative to the aggregate trench is the graveless leaching chamber commonly called a "turtle shell". The chambers is buried at least 12" below the ground leaving an open void. Effluent is discharged in an opening at one end of the chamber. The uses for either type of conventional SAS vary and you should consult with a qualified licensed professional for the best application.

   Pressurized Below Grade "In-Ground Pressure Component"
The in-ground pressure is another type of below-grade SAS. The major distinction between this system and the non-pressurized conventional is that the effluent is supplied through a distribution network by pressure dosing from a pump tank. Pressure dosing allows for more even distribution of the effluent over the entire system area during each dosing period. All Pressure distribution systems require special plan approval from the Wisconsin Department of Commerce - Safety & Building Division.

   At-Grade Component
As the name implies, the system is installed at the surface of the ground. As with below-grade pressurized systems, the at-grade system is also a pressure distribution system. At-grade system designs tend to be long and narrow and therefore require additional site considerations when testing for and placing one on a site.

   Mound Component
The mound system is in effect the same system as the at-grade. The major difference is that this system requires washed sand below the aggregate or leaching chambers. The effluent is supplied by a pump through a pressurized piping network. The purpose of the sand is to create the necessary separation above a limiting condition in the soil beneath. The separation is necessary for the proper removal of bacteria and viruses from the untreated wastewater.

   Aerobic Treatment Highly-Treated Effluent
Today's technology has allowed for more innovative solutions to the above mentioned components. As shown above the "in-situ........... soil at the site is tasked with the job of treating the wastewater. Highly treated effluent completes much of the treatment before the wastewater is discharged to the ground and the soil serves only as a final polishing agent. The advantages to this type of treatment are many; including massive reduction in the amount of area needed verses untreated systems, possibly eliminating the need for unsightly mound systems and unlimited life expectancy. Certain aerobically treated wastewater has >95% contaminant removal, which eliminates the need for replacing a failed system. In many situations a failing systems can be reclaimed through the proper use of aerobic treatment. Odors are drastically reduced or completely eliminated through proper design and installation.

The arguments against aerobic treatment are few. The most common being the initial cost. It is true, aerobic treatment is more expensive "initially". However, over time when a system using raw wastewater is failing, the aerobic treatment unit is actually cleaning the SAS (drainfield). Eventually the untreated system fails and needs to be replaced. Who knows what codes changes and regulations will be requiring in the future - possibly aerobic treatment! Not to mention the cost of re-landscaping, possible septage back-ups and other inconveniences - all with associated costs. Maybe even worse, the property may no longer have enough suitable area for a septic system and you are forced into installing a holding tank!

Another argument is that these systems require maintenance or they don't work like they are supposed to! Well more than likely these two go hand in hand. Homeowners who don't properly maintain these systems will experience problems. However, with proper attention aerobic treatment has proven time and time again that it can and does work.

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Possible Signs and Causes of a Failing Septic System
The following is a common list of signs and possible reasons of a failing septic system.
    Sewage at the ground surface
    Sewage backing in dwelling
    Improper/poor system location
    Improper/poor construction techniques
    System installed in "unsuitable" soils
    Inadequate sizing "overloading" the system
    Frequent freezing problems
    Driving/paving over system
    Use of additives
    Baffles missing from septic tank
    Old age (systems eventually fail)

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Contacting local regulators

   Chippewa County Zoning & Solid Waste
   711 N Bridge
   Chippewa Falls, WI 54729
   715-726-7940

   Dunn County Zoning Department
   800 Wilson
   Menomonie, WI 54751
   715-232-1401

   Eau Claire County Health Department
   920 2nd Ave.
   Eau Claire, WI 54701
   715-839-4718

   District Wastewater Specialist -
   Mr. Leroy Jansky

   3 E Spruce St.
   Chippewa Falls, WI 54729
   715-726-2544

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