Northern Utah Onsite Wastewater Systems
What is an Onsite Sewer System?
What is a Onsite Sewer System?
An Onsite Sewer System, or septic system, is a mini treatment plant buried on your property to treat and dispose of your household wastewater. Septic systems usually consist of three components:
The septic tank is basically a watertight separation chamber for the raw sewage made of concrete, fiberglass, or plastic. The solids sink to the bottom of the tank, becoming part of the "sludge" layer. The next layer contains partially clarified wastewater that will flow to the drain field. On top of the liquid layer floats the "scum" layer composed of lighter liquids such as cooking oil, detergent byproducts and grease. Naturally occurring bacteria break down the solids and reduce the size of the sludge layer. An outlet baffle device with a filter is recommended to help keep solids out of the drain field.
The liquid in the septic tank (the effluent) flows by gravity to a distribution box. The distribution box evenly distributes the effluent from the septic tank to each lateral in the drain field. If the distribution box is not level more effluent will flow to one area of the drain field than the others. This will cause an overload on that section and may cause it to fail.
The drain field or soil absorption field is generally a system of perforated pipes set underground in a bed of crushed rock that allows the effluent to seep slowly into the ground, undergoing further cleansing.
The drain field may be designed as "trenches" or a "bed". If trenches are used there are usually 2 or more parallel trenches approximately 3 ft. wide. Gravel is placed around the pipe in the trenches and covered by fabric or straw that prevents clogging of the pipe with dirt. Beds are used when space or soil considerations indicate their use instead of a trench system.
The Infiltrator Chamber System is an alternative to the gravel and pipe method of drain field construction. Infiltrator chambers are specially designed units made of a resin material that are installed in 2 to 3 foot wide trenches or beds. They have a greater effluent filtration capacity than the stone and pipe systems so require as little as half the space to give equal performance. This can be a major advantage when lot size is small and results in less disruption of the landscape. For more information you can access the Infiltrator Chamber System Company Website.
The size of the drain field is determined by the number of square feet that is specified in the Health Department permit or certified designer. The requirements are based on a number of factors, some of which are the type of soil, the location of the water table, and the number of bedrooms in the house (which is an indicator of future water usage based on number of residents). Some soils are better suited to septic systems than others. Well aerated soil with good permeability is desired. Clay soil will generally have lower permeability and will require a larger drain field than a system located in sandy soil.
Before a permit is issued a site evaluation must be performed, which identifies these criteria by boring holes at several locations on the lot and examining the soil in these holes. The location of any surface water, such as a lake, and underground water supplies, such as wells, must be identified. Wells should be located at least 75 feet from any part of a septic tank system. Septic tanks and drain fields must be also be located at least 75 feet away from the high water line of natural bodies of water such as ponds, lakes or rivers. Runoff from roof gutters and surface drainage patterns must be taken into consideration when siting a drain field location so that it will not become saturated by surface water.
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