Conventional Septic Tank/Drainfield
The conventional septic system consists of two components, the septic tank and the drainfield. The septic tank is where the solids in the wastewater accumulate. The drainfield is where disposal of the wastewater occurs. The tank does provide some degree of treatment to the wastewater but most of the treatment occurs in the drainfield, specifically in the soil in which the drainfield is placed. In fact, the most important component of the system is the soil.
A conventional system can be installed completely below the soil surface if the soil conditions are good and the groundwater is deeper in the soil profile. These types of systems allow for gravity flow of the wastewater through the tank and into the drainfield.
A raised or mound system is required in areas where an elevated groundwater table is present. Mound systems can be unsightly and often create space that is essentially useless except to run a lawn mover over (drip systems can significantly reduce mound height and overall footprint). Conventional and mound systems can be constructed using materials such as rock and pipe or alternative drainfield products such as chambers or multi-pipe. All of these convey the wastewater across the bottom of the drainfield or absorption surface
Every conventional system (in-ground, mounded or LPP) will fail at some point in time. Drainfield failure is the result of microbial activity that occurs while the “pollutants/contaminants/nutrients” are being broken down by bacteria in the soil. A bio-mat builds up over the absorption surface of the drainfield as a result of the microbial activity. This bio-mat severely impedes water movement into the soil. When water cannot move into the soil, a back-up into your house will result. If your system contains a pump, a “blowout” in your yard will usually occur when the drainfield is in failure.
Low Pressure Distribution (LPP) Systems
Here in Florida, a low pressure distribution system is required when the drainfield square-footage exceeds 1000 square feet. This system, like the conventional, consists of two components, the septic tank and the drainfield. The difference between the two is that this system has a distribution network setup inside the drainfield. It usually consists of 1 ¼” PVC pipe with specific sized holes spaced evenly the length of the drainfield. This type of system distributes a determined number of gallons of wastewater somewhat evenly throughout the drainfield. A pump is required in order to distribute the wastewater. This type of system can be installed in the traditional rock/pipe, chamber, or multi-pipe drainfield.
Advanced Treatment/Drip Irrigation Systems
Advanced treatment, nutrient reduction, aerobic (ATU) treatment, drip systems are names that can generally be used interchangeably to describe this type of system; although there are differences. These systems provide a high degree of treatment to the wastewater before it is disposed of into a drainfield. The water that comes out of the system is odorless and colorless. If you were to hold a glass of wastewater from this type of system up to a glass of your tap water, you would be hard pressed to visually detect a difference.
This type of system consists of a trash tank (septic tank), where the solids are retained, an aerobic treatment unit, a dose tank with pump and a drainfield. These types of systems usually are not followed by a conventional drainfield but with a dripfield.
Aerobic treatment systems (of which there are several manufacturers to choose from) effectively recycle all of the water consumed within a home or business and disperses it into the soil via a ½” diameter subsurface drip irrigation tubing. The wastewater is slowly and uniformly distributed through emitters that are usually spaced every 1 or 2 feet through timed distribution events throughout the day over the entire dripfield area.
These types of systems have advantages over a conventional or low pressure system. Virtually 100% reuse of wastewater is obtained. That is, almost 100% of the wastewater is recycled and applied via a subsurface drip irrigation line 6 to 9 inches below the soil surface in the root zone of plants, shrubs or grass. Whatever type of plant is placed within the area of the drip line will be irrigated by the treated wastewater.
Reduced setbacks to property lines and foundations can be obtained due to how accurately drip irrigation works.
Reduction in the required drainfield square-footage is obtained due to the quality of the wastewater being disposed. Reductions range from 25% to 40% depending on the advanced treatment/ATU product utilized in the design. The reduction in the required drainfield square-footage along with the small diameter of the drip irrigation line directly relates to a significant reduction the footprint. A reduced footprint also relates to a reduced digout (if required). A reduced footprint mean that there is
With advanced treatment/drip irrigation systems, the overall footprint of the drainfield can be reduced by up to 60% over a conventional system. This allows for construction of larger homes on smaller lots or simply more construction on any given site (circular drives, pools and patios, detached garages, etc.) or more usable space or “green space for your yard. Drip systems can be installed in areas that conventional systems simply cannot otherwise occupy. Because drip systems are pressurized, great flexibility exists in the way the drip tubing can be laid out and installed.