Step-by-step process for designing a Septic Tank
The capacity of the septic tank has been determined by the frequency and the number of users along with which the sludge has been removed. The liquid capacity of the septic tank is about 70 litres to 130 litres per user. In the case of a small number of users, 70 litres of septic tank can be taken. A brick wall is used for making septic tanks which should be at least 20 cm thick. In addition, the foundation floor of the septic tank should be made with cement concrete with a 1:2:4 design mix. The walls and the top of the floor of the septic tank should have to be plastered along with a minimum thickness of 12mm.
Different parts of the Septic tank
This wastewater treatment system has several parts which include the following:
Inlet Pipe
This part helps to transfer the wastewater from the residence.
Outlet Pipe
Through the outlet pipe, the liquid effluent exits the septic tank.
Septic Tank
This is constructed with fibreglass, concrete, or plastic which helps to retain and treat the wastewater for a specific period of time.
Baffles
This part plays an important role as an internal wall of the septic walls. This partition helps to ensure that the solid waste does not exit the septic tank immediately thus helping to facilitate the setting process of the solid wastes.
Distribution Box
This part has been employed to distribute the effluent from the septic tank to the leach field or drain field.
Drain Field or Leach Field
This part has an interconnected network of perforated pipes which has been buried in the soil. This part has been acting as the recipient of the treated effluent from the septic tank.
Different types of septic tanks
Steel Septic Tanks
This type of septic tank has been made of steel. This type of septic tank is higher in cost and has less lifespan.
Steel septic tanks can deteriorate quickly as compared with the other types of septic tanks.
Concrete Septic Tanks
Concrete septic tanks are easy to install and have a specific gravity of about 2.40, which makes this septic tank strong enough to stand with buoyant forces while placed in the ground.
PVC Septic Tanks
The PVC septic tanks have been made with polyethylene plastics so they are known as the poly septic tanks. This type of septic tank is lighter in weight which can be a good alternative to the steel septic tank and concrete septic tank.
Advantages of septic tank
➢ Septic tanks can be repaired by using locally available materials.
➢ The septic tank is a simple and robust technology and any kind of problem related to flies or odour can not be created in case of using the septic tank correctly.
➢ Very little space is required for the construction of the septic tanks as it is constructed underground.
➢ Fewer operation expenses are required for the construction of the septic tank as well as it has a long service life.
Methods of Septic tank construction
Excavation and Foundation for septic tank
Excavation is the first step in the construction of the septic tank. Careful planning is required to ensure the right size and shape of excavation for installing the septic tank. Making a strong foundation is also necessary for providing stability and longevity to the septic tank.
The foundation of the septic tank should have to be stable and level to provide a solid base for the septic tank. This foundation helps to distribute the septic tank’s weight and prevent the settling of the septic tank unevenly.
Constructing the septic tank
The construction of the septic tank can be done by using reinforced concrete or by installing a prefabricated tank which is made of fibreglass, concrete, or plastic. In the case of using reinforced concrete, the walls and floors of the septic tank have been constructed along with sufficient thickness. Thus, the septic tank stands with the soil pressure and can prevent leakage. The walls of the septic tanks are about 10 cm in thickness and have been reinforced with steel mesh. The floor of the septic tank should have slightly sloped towards the inlet pipe which helps in the collection of the sludge.
The installation of the internal components
The internal components of the septic tank have been constructed after constructing the septic tank structure. In this context, the inlet and outlet pipes are important for performing the operations of the septic tank. These pipes of septic tanks have been made with PVC which is fitted with T-pieces. The T-pieces of these pipes help to reduce turbulence while the wastewater enters and exits the septic tank. This is important to maintain the proper separation of the liquid and solid wastes. Baffles have been installed to direct the wastewater’s flow and prevent the escape of the solids into the outlet pipes. In the case of a two-chamber septic tank, the first chamber of the tank helps to allow the solid wastes to settle and the second chamber helps in clarifying the effluent. The event pipe is another component of a septic tank which involves the escape of the gases safely thus reducing the risk of pressure build-up.
Sealing and covering the septic tank
This is the final method of septic tank construction. A reinforced concrete slab has been used for sealing the septic tank and preventing the entry of the contaminants thus ensuring the durability of the septic tank.
To learn more, watch the following video tutorial.
Video Source: Ian Construction
Maintenance of the septic tank
Regular maintenance of the septic tank is necessary to ensure its long-term durability. The inspection and the pump out of the septic tank are needed every 3-5 years which helps to remove the sludge and scum from the septic tank.
Installing an advanced septic tank system
The installation of the advanced septic tank helps to offer enhanced treatment which includes the installation of the additional filtration, multiple chambers or aeration units. These advanced septic tank system helps to improve the effluent quality.
