We want you to be educated on the topic of septic systems! The first step in education is learning the system components. Today we talk tanks and trenches. Feel free to browse our website for more information, pictures and advice or give our office a call anytime for more information on your system!
THE BASICS
Conventional septic systems consist of two main parts- the tank itself and a soil absorption system. The tank is a watertight tank that holds wastewater discharged from the house for up to 48 hours, allowing scum and sludge to separate from the wastewater. Effluent passes (usually by gravity flow) from the septic tank to the soil- either in the form of a bed or trenches. Septic systems are necessary to treat sewage in areas that lack connection to main sewage pipes provided by local government or private corporations.
DID YOU KNOW??
THE TERM "SEPTIC" REFERS TO THE ANAEROBIC BACTERIAL ENVIRONMENT THAT DEVELOPS IN THE TANK WHICH DECOMPOSES OR MINERALIZES THE WASTE DISCHARGED INTO THE TANK!
THE TANKS
A typical tank consists of one or more concrete or plastic compartments ranging between 1,000 and 2,000 gallons. One end of the tank is connected to the inlet sewer pipe and one end, the outlet, connects to a septic drain field. Generally, these sewer pipe connections are made with a plastic, PVC T-shaped pipe (with older tanks, the connection may be concrete). Tanks typically have two compartments, with manhole-like covers that serve as access. The two compartments are separated by a dividing wall with openings located about halfway between the floor and roof of the tank.
Wastewater enters the first chamber of the tank, allowing solids to settle and scum to float. The settled solids are digested. The liquid component flows through the dividing wall into the second chamber, where further settlement takes place. The excess liquid, which is now actually pretty clear, then drains from the outlet into the drain field (commonly known as the leach field).
CONCRETE SEPTIC TANK:
*Source (not a JT's image) http://www.milanvault.com/septic-tanks/
THE TRENCHES
The trench system consists of shallow, level excavations, usually 1-5 feet deep and 1-3 feet wide. The excavated area is usually filled with 6+ inches of some porous medium, like gravel. Next, is a layer of perforated distribution pipes that are laid in each trench, followed by a semi-permeable barrier (often building paper or straw), and finally the system is covered with soil.
*Source (Not a JT's image): https://www.google.com/search?q=septic+system+trench+design&rlz=1C1AVNG_enUS659US662&espv=2&biw=1920&bih=945&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjZk_73p6jOAhUM12MKHWwrAxAQ_AUIBygC#imgrc=-1DXJXrT7Y66KM%3A
KNOW YOUR TERMS:
Anaerobic Process- a 3-step bacterial respiration process that occurs in the absence of oxygen.
Effluent- the clarified, partially treated liquid which leaves a septic tank. Large solids have been separated by settlement, by floating to coagulate in a grease and scum layer, or by filtration. Effluent moves out of the tank into the absorption/treatment system for further treatment
Scum- the wastewater material which is less dense than water and floats on top of the water
Septage- the mixture of solid wastes, scum, sludge, and liquids pumped from within septic tanks.
Sewage (also known as wastewater)- any urine, feces, and the water carrying human wastes, including kitchen, bath and laundry wastes from the home or business
Sludge- settled solid waste at the bottom of a septic tank. Sludge is semi-solid organic waste
Sources:
http://www.co.thurston.wa.us/health/ehoss/pdf/cms/CMS_Glossary_of_Sewage_Related_terms.pdf
http://www.nesc.wvu.edu/pdf/WW/publications/pipline/PL_FA02.pdf