The sewers are generally designed as open channels except when it is specially required to design them as conduits carrying sewage under pressure as in the case of inverted siphons. Thus various empirical formulae which are used for the design of open channels are used for the design of sewers. The following empirical hydraulic formulae are commonly used for the [...]
In this article we will discuss about the velocity of flow in sewers. Minimum Velocity of Flow in Sewers - Self Cleansing Velocity: A sewer should be so designed that the solid matter present in the sewage is not deposited at the bottom of the sewer and thus clogging of the sewer is prevented. The deposition of the solid matter [...]
Based on the cross-sectional shapes the sewers may be classified as: 1. Circular Sewers 2. Non-Circular Sewers. 1. Circular Sewers: Sewers of circular section are most commonly used. These are best suitable for diameters up to 1.5 m. The various advantages of circular sewers are as indicated below: (i) A circular section gives the least perimeter for a given area, [...]
The sewers may be of the following types: 1. Brick Sewers 2. Cement Concrete Sewers 3. Asbestos Cement Sewers 4. Stoneware or Vitrified Clay Sewers 5. Cast Iron Sewers 6. Steel Sewers 7. Plastic Sewers 8. Fibre Glass Reinforced Plastic (FRP) Sewers 9. Pitch Fibre Sewers. Type # 1. Brick Sewers: Bricks have been used for the construction of sewers, [...]
The various steps involved in the laying and testing of sewers are: 1. Setting out Sewer Centre Line 2. Alignment and Gradient of Sewers 3. Excavation of Trenches, Timbering and Dewatering 4. Laying and Jointing of Pipe Sewers 5. Testing of Pipe Sewers 6. Backfilling of Trenches. Step # 1. Setting out Sewer Centre Line: This is the first step [...]
The various forces exerted on a sewer are explained as follows: 1. Internal Pressure of Sewage 2. Temperature Stresses 3. Forces due to External Load. 1. Internal Pressure of Sewage: Most of the sewers are designed to run partially full in which case sewage flows through sewers under gravity and hence no internal pressure is exerted by the sewage on [...]