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Show Volume X Issue III THE OGDEN VALLEY NEWS Page 11 May 15, 2004 Septic Systems 101 In the last issue of the Ogden Valley News as part of an educational series on septic systems, I took a stab at explaining why it is important for homeowners with septic systems to properly inspect and maintain their systems. This article is dedicated to defining what a septic system is, the components of a septic system, and the types of septic systems that are allowed in Utah. A 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: Septic Tank The septic tank is basically a watertight separation chamber for raw sewage. The tank is 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. Distribution Box 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. Soil Absorption Field 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 two 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 shown below 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. However, Utah does not give any credit towards the required square footage when using these systems. 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 evaluating the soil in a test pit on the lot. 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. The following conventional septic systems can be subcategorized by the type of absorption system used: Standard Absorption Trench Standard trenches are narrow, 1 to 3 feet wide, and have one distribution pipe per trench. Trenches are generally more desirable than absorption beds because trenches can provide five times more absorption area than beds and can be used to follow contours on sloping sites. plastic, with a large internal void space, are placed end to end in the bottom of a trench and backfilled with natural soil. Chambered systems are used in a trench instead of gravel fill. Alternative Onsite Sewer Systems There are three types of “Alternative Systems” allowed in Utah. While conventional systems can be permitted on lots with slopes up to 25%, alternative systems can only be permitted for sites with an existing slope of 4% or less. At-Grade Systems At grade systems are similar to a conventional system except that they are installed at the soil surface. They are generally used in areas where a shallow groundwater table or shallow bedrock prohibits the use of a conventional system. In Utah, the bottom of the absorption field must be 24” from groundwater and 48” from bedrock. An advantage of the At-Grade System is that effluent enters natural soils that usually have the highest permeability and provide the best treatment. Absorption Bed. Absorption beds consist of a wide trench with more than one distribution pipe. Absorption beds may be preferred when the potential site is level and soils consist of sands and loamy sands (perc rate between 1 and 30 min/in). Deep Wall Trench. A deep wall trench is similar to the standard trench except the depth of the trench below the distribu- Earth Fill Systems An Earth Fill System is a system where suitable soil (earth fill) is brought in between the bottom of the absorption system and the natural soil surface. These systems are used where a high groundwater table or inadequate depth to an impervious layer are encountered. These systems can be costly because they must be sized for a minimum of 3 bedrooms, perc rate of 60 min/in, and the area of fill must include a 100% replacement area. The earth fill must sit for a minimum of one year for stabilization and must have a perc rate of 15 to 45 min/in after that time. Mound Systems Mound systems are a proven alternative system that is used when a high groundwater table or impervious layer is encountered. The three components of a mound system are a septic tank, dosing (pumping) chamber, and an elevated mound. The dosing chamber is designed to distribute a predetermined amount of effluent while the mound assures that the effluent is properly treated. These systems are popular and have proven effective in treating effluent in eastern states where high ground water is a problem. Mound systems, however, are quite a bit more costly than traditional systems because sand must be imported for the mound and because of the addition of the pump and pump vault. If you have any questions regarding the components mentioned or types of septic systems, give us a call at (801) 391-7481 or log onto www.river-logic.com for more information. In future issues of the OGDEN VALLEY NEWS, I will give you more information on septic systems including tips on tion pipe is 2 or more feet. A deep wall trench may be used to reach more permeable soils at depth if groundwater is not a problem. Chambered Trench Systems. Chambered systems, typically made of inspecting and maintaining your septic system. Note: This article was provided by River Logic, an Eden-based company that provides perc testing, septic design services, as well as septic system trouble shooting. Another Home Sold by Dick Payne & His Million Dollar Team Lot #14 Durfee Creek 5772 East 2200 North $289,000 in Eden FREE Market Analysis at Your Home. Call NOW 940-4040 The Dick Payne Homeselling System Dick Payne |