4 Main Properties of a Gravity Sewer
A gravity sewer is one of the most commonly used sewage system in collecting wastewater and other solid materials from households and transporting them to industrial sewer pipes. This system does not require pumping stations and pumping equipment but, in fact, it depends on the degree of declivity built during its construction and the pull of gravity. This certain feature also plays a role in giving the sewer its self-cleaning velocity. Without the slope or when the degree of declivity is not enough, the system will face the trouble of sewage particles sticking to the walls and accumulating, eventually, this will lead to blockage and the system will require pumping and heavy maintenance procedures done.
The self-cleansing flow of the system is very useful in transporting sewage without the amount of operational costs weighting down on the community just to convey the wastes. It is important to remember that a Gravity Sewer should be installed and laid out as straight as possibly to avoid sewage deposits along the joint and bending areas.
Here are other properties of the Gravity Sewer that you might want to know about:
- Slope of Sewer
During installation, the construction of a gravity sewer system should have a certain level of declivity set to keep the sewage flowing with the pull of the gravity. As the pipes are laid, a certain level of inclination should be allowed to the pipes to keep the motion and the self-cleansing properties of the system. There is a certain velocity flow that the designers should compute for and this will depend on the estimated waste weight that the community is capable of releasing. Failure to do these will lead to total failure of the entire sewage system. Particles, sewage solid wastes and other accumulations can form in joints, bends and even in the interior of the pipes when the velocity is not fast enough to prevent them from sticking. This event will lead to a sewer backup or overflow which will likely cause health issues and wildlife death.
- Design Flow
As mentioned above, there would be a certain velocity range that the designers and contractors will compute for to predict and design the sewer system to withstand the capacity of the sewage that a certain community is capable of producing. The sewer should be able to cope with the changes in the volume of the load that the pipes are responsible in carrying, keeping in mind that the weight and volume of sewage can fluctuate throughout the day. Peaking factor should be utilised to extend capacities in case of a rise in the population.
A Gravity Sewer is expected to have its self-cleaning velocity and for that, the velocity of the load should be at least 2 fps to maintain this feature. Failure to establish this feature can lead to accumulation and eventual blockage of the sewer system rendering the system useless.
- Pipe Size
Even with the self-cleaning velocity feature, the pipes used in an industrial Gravity Sewer pipe should allow cleaning and maintenance equipment inside. The diameter of the pipes should be chosen depending on the population of the community.