Most conventional septic systems consist of a septic tank and drainfield.
The septic tank is a watertight tank designed to separate solids and liquids in waste water. The primary treatment occurs in the septic tank in an environment that does not contain oxygen. Once the solids and liquids are separated, the solids settle to the bottom of the first compartment. Over time these solids accumulate and must be removed to ensure lawful performance. The tank must have its solids pumped out every 3-5 years.
The drainfield is a network of trenches spaced 9 feet apart on center that follow the contour of the land. Water flows from the tank into the trenches where it is absorbed into the soil. The soil environment acts as the final treatment of that wastewater. Conventional gravel trenches are generally 24-3 inches deep and 36 inches wide. The bottom of the trench is filled with clean stone to a depth of 12 inches.
Gravel-less trenches are the same depth as gravel trenches in most cases, but have some other material other than gravel, usually plastic, in the trench. Some gravel-less systems offer a reduction in the linear footage over gravel systems.
The linear footage of the drainfield is determined by the size of the facility and the soil type. The more waste water generated, the larger the drainfield will have to be in order to dispose of the wastewater.
OVERVIEW OF OTHER SYSTEMS
These types of systems are usually used when site constraints limit the installation of a conventional septic system. Usually these constraints are available space and soil depth.
Types of other systems are:
- PPBPS - Prefabricated permeable block panel system
- Subsurface Drip Irrigation
- Low Pressure Pipe