A Conventional Septic System is the least expensive and least complex absorption type of system that can be installed. The entire system is below the ground with the exception of the septic tank riser. This riser is placed above the surface to allow for easy access to the filter.

Two types of conventional systems can be installed. The first is the standard system that consists of a gravel cell and distribution laterals. The other type of system (shown above) utilizes diffusion chambers, which create a void in the soil that allows for water to collect until it percolates through the soil down to the water table. At

Billingsley Engineering we install the diffusion type system because we believe it allows for a greater absorption area. This will increase the life span of the system.

A Conventional Septic System utilizes only one septic tank and an absorption field. The tank shown above is a double-compartment tank. A septic tank for a three-bedroom house is approximately six feet wide, eight feet long, by five feet tall. The size and volume of the tank depends on the number of bedrooms in the house. It is constructed using pre-cast concrete and is watertight. All the joints on the risers are sealed with a tar based epoxy which forms and sticks to the risers when installed creating a watertight seal. The center wall inside the septic tank creates a barrier to help keep the solids in the first half of the tank.

As effluent water is retained in the septic tank, solids settle to the bottom of the tank and fats float to the top creating a soft layer of crust. As this is occurs, natural bacteria biodegrade the majority of the solids leaving a partially treated zone of water in the middle of the tank. Should solids pass to the second half of the tank, a filter is installed on the outlet that will stop any solids as small as 1/8th to 1/32nd of an inch from exiting the tank.

As water flows into the tank from the house, partially treated effluent then flows through the filter and into the absorption field. The combination of the double compartment tank and the filter greatly decreases the chance of solids making it to the absorption field. The filter must be cleaned periodically to keep it from becoming plugged.

The absorption field for this type of system consists of a couple rows of diffusion chamber placed on top of the sand. These chambers create a void in the ground that allows for water to collect until it percolates through the sand below. As the effluent percolates through the sand it is naturally filtered leaving all of the bacteria and harmful substances behind before reentering the ground water.