Conventional Septic Tank-Drainfield System
A conventional septic system consists primarily of two components, the septic tank and the drainfield. The septic tank provides some treatment to the wastewater while retaining the solids. Distribution/disposal of the wastewater occurs in the drainfield. Drainfield materials can be rock/pipe, chambers or multi-pipe. Each of these materials allows the effluent to be dispersed in the soil where final treatment occurs.
A conventional system is installed below the ground surface where the soil/groundwater conditions are good. These systems are usually gravity fed (no pumps required) due to the depth of installation.
A mound system is required when soil or groundwater conditions are as such that a “below grade” drainfield cannot be installed. This type of system typically requires a pump as the drainfield is higher than the outlet of the septic tank. A raised or mound system is required in areas where an elevated groundwater table is present.
A mound system produces an unsightly “hump” and can occupy a significant amount of space because of shoulder and sideslope requirements. A 4-foot shoulder is required around the drainfield and then the sideslope. The shoulder and sideslope can add 18 feet or more to the total length and width of the area occupied by the drainfield. Aerobic treatment-ATU-drip irrigation systems can be installed in place of the conventional system. In doing so, the mound height is reduced by a minimum of 12-15 inches and the overall footprint is reduced by about 50%. Best of all, aerobic treatment-ATU-drip irrigation systems can be installed at the same cost as the conventional mound: USUALLY LESS because they require significantly less fill. In addition, certain soil conditions are not required to be removed or excavated when using an aerobic treatment-ATU-drip irrigation system. This further reduces the cost of the system