Septic systems are individual wastewater treatment systems that use the soil to treat small wastewater flows, usually from individual homes. There are many types of septic systems in use today. While all septic systems are individually designed for each site, most septic systems are based on the same principles.
Septic Tank
Septic Tank- The effluent septic tank is designed to retain waste water and allow heavy solids to settle to the bottom of the tank. These solids are partially decomposed by bacteria to form sludge. Grease and light particles float, forming a layer of scum on top of the waste water. Baffles are installed to help prevent scum and solids from escaping to other parts of the system. Newer septic tanks can have a partial concrete dividing wall in the center, thus making two compartments. This helps ensure the sludge does not get forced out of the baffle towards the downstream component.
Pump Tank
Pump Tank- Pump Tanks generally consist of a chamber that is of concrete, fiberglass or polyethylene that collects effluent from the septic tank. Typically the chamber contains a pump, pump control floats, and a high-water alarm float.
Aerobic Treatment Unit(ATU)
Aerobic Treatment Unit(ATU)- An aerobic treatment unit pretreats wastewater by adding air to break down organic matter, reduce pathogens, and transform nutrients. Compared to conventional septic tanks, ATUs break down organic matter more efficiently, achieve quicker decomposition of organic solids, and reduce the concentration of pathogens in the wastewater.
Gravity System
Gravity System- Consists of a septic tank which flows effluent by gravity to a distribution box (D-box); one or more connections to this D-box drain into trenches typically filled with gravel. Only a small part of the drainfield is used at any one time. Requires a minimum of 48 inches of permeable soil above a restrictive layer to be used on new construction. Least amount of maintenance required of any system type but requires the greatest soil depth in order to provide adequate treatment of the effluent.
Pressure Distribution System
Pressure System- Consists of a septic tank and pump tank with pressurized lines leading to individual trenches. This allows dosing of the drainfield and use of the entire drainfield at once. Requires at least 30-36 inches of permeable soil above a restrictive layer to be used on new construction. Maintenance is required to assure the orifices do not plug over time.
Sandfilter to Pressure Distribution System
Sandfilter to Pressure Distribution System- Consists of sand placed in a watertight box built into the soil. Effluent is spread evenly over the surface of the sand via a pressurized network. The sand layer treats the effluent and is collected in the bottom of the filter box from which it is then pumped to a drainfield. The drainfield in this case is a pressure distribution system, which finishes the treatment process and then disposes of the wastewater. Requires at least 18 inches of permeable soil above a restrictive layer to be used on new construction. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.
ATU to Gravity System
Aerobic Treatment Unit(ATU) to Gravity System- Consists of a watertight tank with an aeration chamber where sewage and microorganisms come in contact with each other in the presence of dissolved oxygen. Blowers, compressors or air pumps supply the air. The treated effluent is then drained into a conventional gravity drainfield. To meet the highest treatment standards a disinfection unit must be part of the device to reduce the bacteriological counts. With disinfection the system could be used on a site with only 24 inches of soil. Without disinfection the system would require at least 4 feet of soil. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.
ATU to Drip Irrigation System
ATU to Drip Irrigation System- Consists of a watertight tank with an aeration chamber where sewage and microorganisms come in contact with each other in the presence of dissolved oxygen. Blowers, compressors or air pumps supply the air. The treated effluent is then pumped through sub-surface drip lines installed only six inches below the surface. An advantage of this system is that it is installed in the root zone of plants which can take up nutrients, like nitrates, before they make their way to the groundwater.
Glendon Biofilter System
Glendon Biofilter System- Consists of different layers of sand and gravel placed in a watertight box built into the soil. Effluent is pumped into the bottom of the filter and allowed to wick itself up through the sand and over the rim of the box into the soil. Several boxes or pods may be used to accommodate varying site conditions and number of bedrooms. A splitter along with a timing device is used to assure even flow to all pods. This system can be used in situations where a lot has 18 inches of soil and only12 inches if 5 acres or greater. The complexity of this system and the situations in which it is used requires periodic maintenance and proper operation to assure continued performance standards be met over time.