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.