LP SEPTIC

A decentralized wastewater treatment system consisting of a septic tank and a trench or bed subsurface wastewater infiltration system (drainfield). A conventional septic system is typically installed at a single-family home or small business.

The gravel/stone drainfield is a design that has existed for decades. The name refers to the construction of the drainfield. With this design, effluent is piped from the septic tank to a shallow underground trench of stone or gravel. A geofabric or similar material is then placed on top of the trench so sand, dirt, and other contaminants do not enter the clean stone.

Effluent filters through the stone and is then further treated by microbes once it reaches the soil below the gravel/stone trench.

Gravel/stone systems are relatively large in overall footprint and may not be suitable for all residential sites or conditions.

Aerobic Treatment Units (ATUs) use many of the same processes as a municipal sewage plant, but on a smaller scale. An aerobic system injects oxygen into the treatment tank. The additional oxygen increases natural bacterial activity within the system that then provides additional treatment for nutrients in the effluent. Some aerobic systems may also have a pretreatment tank and a final treatment tank including disinfection to further reduce pathogen levels.

The benefits of this system are that it can be used in homes with smaller lots, inadequate soil conditions, in areas where the water table is too high, or for homes close to a surface water body sensitive to contamination by nutrients contained in wastewater effluent.

From an aerobic treatment unit, there are two options for drainage: drip or spray irrigation. A pump tank will dose the wastewater at an appropriate pressure to drip distribution or spray irrigation. The main advantage of the drip distribution system is that no large mound of soil is needed as the drip laterals are inserted into the top of the soil, and it requires less surface area. Spray distribution systems are basically a lawn sprinkler system, which requires the greatest level of wastewater pretreatment because of the risk of human contact. However, spray systems bring all the benefits of landscape irrigation in times of drought without the use of additional groundwater.