Publication: Residential Onsite Wastewater Treatment: Septic …

This NebGuide provides information on septic wastewater tank installation, such as selecting the correct tank size and placement, in order for owners to understand tank design and installation procedures used by installation professionals.

Jan R. Hygnstrom, Extension Project Manager Sharon O. Skipton, Extension Educator Wayne E. Woldt, Extension Specialist

A properly designed, installed and maintained septic tank and effluent treatment system is an approved method of wastewater treatment in Nebraska for private residences in areas where public wastewater treatment systems are not available. The system includes the building sewer line (which starts 30 inches from the house and extends to the septic tank), the septic tank, the effluent treatment component, and all piping in between. A drainfield, also known as a lateral, leachfield or soil absorption field, is most commonly used for effluent treatment. Alternative effluent treatment components may be used. Examples include mounds and constructed wetlands.Where soil has a suitable percolation rate and other site conditions are appropriate, the septic tank/drainfield system is a good choice, and the most commonly used.

Only a Nebraska certified installer, registered environmental health specialist, professional engineer, or someone under their direct supervision may install a septic tank.

This publication gives design and installation information for a septic tank based on Nebraska Department of Environmental Quality (NDEQ) Title 124: Rules and Regulations for the Design, Operation, and Maintenance of Onsite Wastewater Treatment Systems. Local regulations may be more strict than those issued by the state. Contact your city or county health, environmental, zoning or planning department for local requirements.

How does treatment occur in a septic tank?

Wastewater flows from the building sewer line to the septic tank where both heavy and light solids separate from the wastewater. Solids that are heavier than water settle out forming a sludge layer on the bottom of the septic tank (Figure 1). Solids lighter than water float to the top of the wastewater forming a scum layer. A liquid layer of water with suspended solids, nutrients, microorganisms and other pollutants separates the sludge and scum. Anaerobic bacteria those that can live without oxygen begin to break down waste in the septic tank. As wastewater flows into the septic tank, an equal volume of the liquid layer, called effluent, flows out of the septic tank into the effluent treatment system. In a properly designed, functioning and maintained septic tank, scum and sludge will not flow out with the effluent.

While septic tank effluent may appear clear, microorganisms such as bacteria and viruses, nutrients such as nitrate and phosphorous, dissolved materials and very small particles of suspended solids are present. To protect the environment and human health, effluent must receive additional treatment, typically in the drainfield, or in an alternative effluent treatment component.

The location of plumbing within the home, lot configuration and slope of the land help determine placement of the septic tank. To protect the environment and human health, use no less than minimum setback distances (Table I) for the tank and effluent treatment component that will be used. Avoid sites subject to flooding, ponding or surface drainage from surrounding areas. The location must be accessible so contents of the septic tank, known as septage, can be pumped. Typically, hoses on pumper trucks can reach 50 feet. Also, consider the possibility of future expansion and locations for sidewalks, patios, driveways, garages and storage buildings before selecting the tank site. It is not legal to construct a sidewalk or building over a septic tank, as maintenance and inspection would be very difficult, if not impossible.

Distance to:

Go here to read the rest:
Publication: Residential Onsite Wastewater Treatment: Septic ...