Testing of Sewers

Testing of Sewers

The sewers after being laid and jointed are tested for watertight joints and also for correct straight alignment as described below

 1.       Test for Leakage (Sewer Testing)

2.       Test for Straightness of Alignment and Obstruction (Sewer Testing)

 Types of Sewer Tests

 1.   Sewer Testing for Leakage (Water Test)

 The sewer testing is ensure no leakage through the joints after giving sufficient time to these joints to set in. For this purpose sewer pipe sections are tested from manhole to manhole under a test pressure of 1.5m of water head i.e. depth of water in the manhole is maintained at about 1.5m. The lower end of the sewer is first of all plugged.

The water is then filled in the manhole at the upper end and is allowed to flow through the sewer line. The sewer line is watched by moving along the trench and the joints which leak or sweat are repaired. The leakage pipe if any will also be replaced.



 2.   Sewer Testing for Straightness of Alignment and Obstruction

 The straightness of the sewer pipe can be tested by placing a mirror at one end of the sewer line and a lamp at the other end. If the pipe line is straight, the full circle of light will be observed. However, if the pipe line is non-straight, this would be apparent and the mirror will also indicate any obstruction in the pipe barrel.

 Any obstruction present in the pipe can also be tested by inserting at the upper end of the sewer a smooth inserting at the upper end of the sewer a smooth ball of diameter 13mm less than internal diameter of the sewer pipe. In the absence of any obstruction, such as yarn or mortar projecting through the joints etc. the ball shall roll down the invert of the sewer pipe and emerge at the lower end.


 


Steps in Laying of Sewer Pipe / Sewage Pipes

 The laying of sewage pipe consists of the following steps.

 1.  Locate the positions of the manhole on the ground along the longitudinal section of the sewer line. It is common practice to lay sewer line between two manholes at a time.

 2.  The center line pegs of the sewer are driven at a distance of every 7.5 m or 15m.

 3.  The center line of the sewer line should be properly maintained by providing an off-set line usually marked at a distance of 2m to 3m. The off-setline helps in locating the sewer center line when excavation is carried out to laying of sewer pipe.

 4.  The trench is excavated between two manholes and the bedding layer of concrete is provided for soft soil while in case of rocky or hard soil, no bedding. The sewers are laid down between two manholes.

 5.  After completing the laying of sewer pipe between two manholes. Further excavations are carried out for laying of sewer pipe between the next consecutive manholes. The process is continued form the outfall end of the sewer towards the starting end till the entire sewers is laid out.

 6.  The refilling of trenches is started after the sewer line is properly laid in position, aligned, jointed and test for leakage and alignment.



Purpose of Sewage Treatment

 The sewage is treated before its final disposal because of the following reasons:

 1.       To kill the pathogenic bacteria present in the sewage which may result in water born diseases like cholera, typhoid, dysentery etc.

2.       To avoid unhygienic condition in the area because of highly fouled sewage.

3.       To protect aquatic life from harmful effects of sewage directly discharged into the water body (river or sea).

4.       The stagnant sewage may percolate into the soil and pollute the ground water reservoir which may lead to epidemics.

5.       Treatment makes the possibility of reuse of valuable fresh water for agriculture purposes.

6.       The treated sewage may be used for reclamation of land.

Comments

Post a Comment

Popular posts from this blog

NOTCHES AND WEIRs

Image
   NOTCH ,WEIR AND ITS TYPES Notch A  notch  may be defined as an obstruction over which the flow of liquid occurs   In case of measuring tank or reservoir, the opening is provided at the side of the tank such that the liquid surface in the tank is below the top edge of the opening. Weir A  weir  is a notch on a large scale used for measuring the flow of a river, canal etc. It is a concrete or masonry structure of substantial breadth built across the river in the direction of flow. This allows the excess water to flow over its entire length to the downstream side. Thus a weir is similar to a small dam constructed across the river, with a difference that the excess water flows downstream only through a small portion called  spillway  and in case of weir, the excess water flows over its entire length. Nappe and crest The sheet of water flowing through a notch or over a weir is known as  nappe  or  vein . The bott...
Read more

THE BASICS OF REBAR: A COMPREHENSIVE GUIDE FOR BEGINNERS

Image
 THE BASICS OF REBAR: A COMPREHENSIVE GUIDE FOR BEGINNERS The Basics of Rebar If you have ever wondered what gives strength and stability to the concrete structures that we see around us, the answer is (most commonly) rebar. Rebar, short for reinforcing bar, is the steel rods that are embedded in concrete that provide tensile strength to what is actually and prevent cracking. Rebar comes in different shapes and sizes, but the most common type is deformed steel rebar, which has ridges or indentations along its surface to create a better bond with the concrete. Deformed steel rebar has been used in the construction industry for over a century, and it has revolutionised the way we build. With rebar, and using elements such as beams,  beam ties , rebar mesh, and reinforced walls, we can create taller, stronger, and more durable structures that can withstand natural disasters, environmental changes, and human activities. Some of the most iconic buildings in the world, such as...
Read more

What are different diameters of steel used in construction field?

         In the construction industry, the appropriate selection of materials is crucial as they form            the fundamental basis for determining the strength and durability of structures. TMT (Thermo-Mechanically Treated) Steel is one of the essential components in construction as it stands out for its exceptional strength and ductility in building structures. Thus, contributing to the prolonged longevity and durability of the structures. In this article, we will delve into the different sizes of  TMT steel bars  and their different uses in the construction industry. These TMT Steel bars come in different sizes based on their varied diameters. The different diameter of steel bars are as follows: 8mm Steel Rod 10mm Steel Rod 12mm Steel Rod 16mm Steel Rod 20mm Steel Rod 25mm Steel Rod 32mm Steel Rod, etc TMT bars of varied sizes, play a pivotal role in diverse infrastructure initiatives, the versatility of TMT bars is ...
Read more