HOW A STANDARD SEPTIC SYSTEM WORKS
Your basic septic system usually consists of at least three parts:
The septic tank is basically a storage chamber for the raw sewage. The solids sink to the bottom of the tank, becoming part of the "sludge" layer. The next layer contains the liquid which will flow to the drainfield. On top of the liquid layer floats the "scum" layer composed of lighter liquids such as cooking oil, detergent byproducts and grease. Naturally occurring bacteria break down the solids and reduce the size of the sludge layer. An outlet baffle device with a filter is required by Florida code on all new installations of septic tanks to help keep solids out of the drainfield.
Drawing credit: Northern Arizona University
Septic
tanks should be watertight. As waste
water enters the system, the same amount is expelled into the drainfield. The
bacteria that thrive in a septic tank are called "anaerobic bacteria" because
they do not require oxygen. These bacteria are essential to the proper
functioning of a septic system as they degrade and decompose the solids. It is
not necessary to add bacterial additives to your system, no matter what the
advertisers say, and some additives may cause harm.
The tanks we install are concrete, multichambered septic tanks with filters. In our experience, concrete is superior to the fiberglass tanks used by some contractors. Some installers use fiberglass due to ease of transport and handling, but in our opinion there is no advantage for the homeowner.
Why get your tank pumped and how often should you have it done? See our page on Taking Care of Your Home Septic System for more information. It is generally suggested that you have your tank pumped every 3 to 5 years on a regular maintenance schedule, which will help prevent premature drainfield failure.
It is our opinion that using a plastic box provides no benefit to the customer and that there is no application in which a plastic box outperforms a concrete box.
The
Drainfield or Soil Absorption System
The drainfield or soil absorption field is generally a system of perforated pipes set underground in a bed of crushed rock that allows the effluent to seep slowly into the ground, undergoing further cleansing. The drainfield may be designed as "trenches" or a "bed". If trenches are used there are usually 2 or more parallel trenches approximately 3 ft. wide. Gravel is placed around the pipe in the trenches and covered by fabric that prevents clogging of the pipe with dirt. Beds are used when space or soil considerations indicate their use instead of a trench system.
The Infiltrator Chamber System is an alternative to the gravel and pipe method of drainfield construction. Infiltrator chambers are specially designed units made of a resin material that are installed in 2 to 3 foot wide trenches or beds. They have a greater effluent filtration capacity than the stone and pipe systems so require as little as half the space to give equal performance. This can be a major advantage when lot size is small and results in less disruption of the landscape. For more information you can access the Infiltrator Chamber System Company website.
The size of the drainfield is determined by the number of square feet that is specified in the Health Department permit. The requirements are based on a number of factors, some of which are the type of soil, the location of the water table, and the number of bedrooms in the house (which is an indicator of future water usage based on number of residents). Some soils are better suited to septic systems than others. Well aerated soil with good permeability is desired. Clay soil will generally have lower permeability and will require a larger drainfield than a system located in sandy soil.
Before a permit is issued a site evaluation must be performed, which identifies these criteria by boring holes at several locations on the lot and examining the soil in these holes. The location of any surface water, such as a lake, and underground water supplies, such as wells, must be identified. Wells should be located at least 75 feet from any part of a septic tank system. Septic tanks and drainfields must be also be located at least 75 feet away from the high water line of natural bodies of water such as ponds, lakes or rivers. Runoff from roof gutters and surface drainage patterns must be taken into consideration when siting a drainfield location so that it will not become saturated by surface water.
Florida Code requires that the bottom of the drainfield be 24 inches above the water table so some systems will need fill to raise the area where the drainfield will be installed. This is often called a "mound" system, which is described in detail in our section about Mounds and Dosing Systems
WHAT ABOUT MOUNDS AND DOSING SYSTEMS?
Mounded septic tank systems are required by Florida code when the water table is shallower than 36 inches below natural grade or when restrictive soils (e.g. limestone rock, pipe clay) are found 42 inches or less below natural grade.
Mounds are more expensive than a standard below grade drainfield and require much more space. Every effort should be made to locate your system in an area that does not require a mound. On some lots there is no other option except to use a mounded system. However, by careful selection of the areas chosen for the site evaluation you may avoid having to install a mound. As a Master Septic Tank Contractor, Anthony Gaudio can perform the site evaluation and select the best location for your system.
The elements of a mounded system are listed below.
In some cases, dosing systems are required to pump effluent from a gravity fed septic tank into a raised mound drainfield or to a remote underground drainfield. A dosing system may also be required in some commercial applications when the gallons per day usage or size of the drainfield necessitates its use.
The elements of a dosing system as installed by Apalachee Backhoe and Septic Tank, LLC are:
We have experienced service technicians available to attend to any problems with these systems, although the high quality pumps and equipment we use require less service and maintenance than many others. We are able to service pumps and dosing systems installed by other companies.
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