Septic System Inspection Brevard County Florida

Septic System Information

      Everything that goes down any of the drains in the house (toilets, showers, sinks, laundry machines) travels first to the septic tank. The septic tank is a large-volume, watertight tank which provides initial treatment of the household wastewater by intercepting solids and settleable organic matter before disposal of the wastewater (effluent) to the drain field.

Function of the Septic  System Tank How Long Liquids Must Remain In Tank Solids Storage Anaerobic Decomposition Flow Into And Out Of The Tank Effluent Filter Flow Buffering Microbes in Septic Tanks Digest, Dissolve, and Gasify Complex Organic Wastes.

FUNCTION OF THE SEPTIC SYSTEM TANK

While relatively simple in construction and operation, the septic system tank provides a number of important functions through a complex interaction of physical and biological processes. The essential functions of the septic system tank are to: receive all wastewater from the house separate solids from the wastewater flow cause reduction and decomposition of accumulated solids provide storage for the separated solids (sludge and scum) pass the clarified wastewater (effluent) out to the drain field for final treatment and disposal.
Primary Treatment   As stated, the main function of the septic system tank is to remove solids from the   wastewater and provide a clarified effluent for disposal to the drain field.   The septic tank provides a relatively quiescent body of water where the   wastewater is retained long enough to let the solids separate by both   settling and flotation. This process is often called primary treatment and   results in three products: scum, sludge, and effluent.
Scum: Substances lighter than water (oil, grease, fats) float to the top,   where they form a scum layer. This scum layer floats on top of the water   surface in the tank. Aerobic bacteria work at digesting floating solids.
Sludge: The "sinkable" solids (soil, grit, bones, unconsumed food particles)   settle to the bottom of the septic system tank and form a sludge layer. The sludge is   denser than water and fluid in nature, so it forms a flat layer along the   tank bottom. Underwater anaerobic bacteria consume organic materials in the   sludge, giving off gases in the process and then, as they die off, become   part of the sludge.
Effluent: Effluent is the clarified wastewater left over after the scum has   floated to the top and the sludge has settled to the bottom. It is the   clarified liquid between scum and sludge. It flows through the septic tank   outlet into the drain field.
HOW LONG LIQUIDS MUST REMAIN IN SEPTIC SYSTEM TANK   Effective volume: The floating scum layer on top and the sludge layer on the   bottom take up a certain amount of the total volume in the tank. The   effective volume is the liquid volume in the clear space between the scum   and sludge layers. This is where the active solids separation occurs as the   wastewater sits in the septic system tank.
Retention time: In order for adequate separation of solids to occur, the   wastewater needs to sit long enough in the quiescent conditions of the septic system tank. The time the water spends in the septic system tank, on its way from inlet to outlet, is known as the retention time. The retention time is a function of the   effective volume and the daily household wastewater flow rate:
Retention Time (days) = Effective Volume (gallons)/Flow Rate (gallons per day)   A common design rule is for a tank to provide a minimum retention time of   at least 24 hours, during which one-half to two-thirds of the tank volume is   taken up by sludge and scum storage. Note that this is a minimum retention   time, under conditions with a lot of accumulated solids in the tank. Under   ordinary conditions (i.e., with routine maintenance pumping) a tank should   be able to provide two to three days of retention time.   As sludge and scum accumulate and take up more volume in the tank, the   effective volume is gradually reduced, which results in a reduced retention   time. If this process continues unchecked-if the accumulated solids are not   cleaned out (pumped) often enough-wastewater will not spend enough time in   the tank for adequate separation of solids, and solids may flow out of the septic system  tank with the effluent into the drain field. This can result in clogged pipes   and gravel in the drain field, one of the most common causes of septic system   failure.
SOLIDS STORAGE   In order to avoid frequent removal of accumulated solids, the septic tank is   (hopefully) designed with ample volume so that sludge and scum can be stored   in the tank for an extended period of time. A general design rule is that   one-half to two-thirds of the tank volume is reserved for sludge and scum   accumulation. A properly designed and used septic system should have the   capacity to store solids for about five years or more. However, the rate of   solids accumulation varies greatly from one household to another, and actual   storage time can only be determined by routine septic tank inspections.
ANAEROBIC DECOMPOSITION   While fresh solids are continually added to the scum and sludge layers,   anaerobic bacteria (bacteria that live without oxygen) consume the organic   material in the solids. The by-products of this decomposition are soluble   compounds, which are carried away in the liquid effluent, and various gases,   which are vented out of the tank via the inlet pipe that ties into the house   plumbing air vent system.   Anaerobic decomposition results in a slow reduction of the volume of   accumulated solids in the septic tank. This occurs primarily in the sludge   layer but also, to a lesser degree, in the scum layer. The volume of the   sludge layer is also reduced by compaction of the older, underlying   sludge. While a certain amount of volume reduction occurs over time, sludge   and scum layers gradually build up in the tank and eventually must be pumped   out.
FLOW INTO AND OUT OF THE SEPTIC SYSTEM TANK   The inlet and outlet ports of the tank are generally equipped with devices such as baffles, concrete tees, or in more recent years, sanitary tees   (T-shaped pipes with one short and one long leg). Inlets   The inlet device dissipates the energy of the incoming flow and deflects it   downwards. The vertical leg of the tee extends below the liquid surface well   into the clear space below the scum layer. This prevents disturbance of the   floating scum layer and reduces disruptive turbulence caused by incoming   flows. The inlet device also is supposed to prevent short-circuiting of   flows across the water surface directly to the outlet.   The upper leg of the inlet should extend well above the liquid surface in   order to prevent floating scum from backing up into, and possibly plugging,   the main inlet pipe. The open top of the inlet tee allows venting of gases   out of the tank through the inlet pipe and fresh air vents of the household   plumbing.
Outlets   The outlet device is designed to retain the scum layer within the tank. A   sanitary tee can be used with the lower leg extending below the scum layer.   The elevation of the outlet port should be 2 to 3 inches below the elevation   of the inlet port. This prevents backwater and stranding of solids in the   main inlet pipe during momentary rises in the septic system tank liquid level caused by   surges of incoming wastewater.
Typical inlet/outlet tees
Gas Deflection Baffle
Gases are produced by the natural digestion of sludge at the bottom of the   tank, and particles of sludge can be carried upward by these rising gases.   Some tanks have a gas deflection baffle, which prevents gas bubbles (to   which solid particles often adhere) from leaving the tank by deflecting them   away from the outlet and preventing them from entering the drain field.
THE EFFLUENT FILTER   In newer systems, there is often an effluent filter: one of the significant   improvements in septic tank design in decades. They range from 4 to 18   inches in diameter. As we have described, the most serious problem with   septic systems is the migration of solids, grease, or oil into the   drain field, and the filter is effective in preventing this.   A filter restricts and limits passage of suspended solids into the effluent.   Solids in a filtered septic system effluent discharge are significantly less than   those produced in a non-screened septic system.
 FLOW BUFFERING   The septic system tank also provides a buffering of flows between the house and the   drain field. Large surges from the household, such as toilet flushing or   washing machine drainage, are dampened by the septic system tank so that the flows   leaving the tank and entering the drain field are at substantially lower flow rates and extend over a longer period of time than the incoming surges.
MICROBES IN SEPTIC SYSTEM TANKS DIGEST, DISSOLVE, AND GASIFY COMPLEX ORGANIC WASTES   In 1907, W. P. Dunbar conducted tests on the decomposition of vegetable and   animal matter in septic tanks. He stated, "The author has investigated the   subject by suspending in septic tanks a large number of solid organic substances, such as cooked vegetables, cabbages, turnips, potatoes, peas,   beans, bread, various forms of cellulose, flesh in the form of dead bodies of animals, skinned and unskinned, various kinds of fat, bones, cartilage,   etc., and has shown that many of these substances are almost completely   dissolved in from three to four weeks. They first presented a swollen appearance, and increased in weight. The turnips had holes on the surface, which gradually became deeper. The edges of the cabbage leaves looked as though they had been bitten, and similar signs of decomposition were visible   in the case of other substances. Of the skinned animals, the skeleton alone   remained after a short time; with the unskinned animals the process lasted   rather longer. At this stage I will only point out that the experiments were so arranged that no portion of the substances could be washed away; their disappearance was therefore due to solution and gasification."