Sewer pipes are laid beginning with their outfall ends towards their starting ends. The advantage gained in starting from the tail end (outfall) is the utilization of the tail sewers even during the initial period of construction. This ensures that the functioning of the sewage scheme does not have to wait until the completion of the entire scheme.
Mark proposed alignment on the ground by locating the different points along the alignment.
Locate the position where manholes/chambers are required as pre the drawing.
Slopes in excavation should be provided using the side rail and rod method.
Excavate trenches along the proposed alignment. Width of the trench at the bottom should be kept 15 cm more than the outer diameter of the sewer pipe.
Lay sewer pipes between the two chambers or inspection chambers.
Keep the road/passment position for the minimum crossing length of sewer line.
R.C.C. hume pipes are generally used for the such crossings.
10 cm bedding concrete of grade M10 should be laid along the sewer line, up to half the depth of pipe which is called ‘haunching’, so that the sewer alignment is not disturbed 10 cm bed concrete may be laid before the laying of sewer pipes.
Manhole/chamber should be constructed at different locations as per the drawings.
Back filling of trenches should be done immediately to avoid any accidents.
Laying of Sewer Pipes
Slopes of sewer line
Dia. Of Pipe
|
Slope for velocity 0.75 m/s
|
100 mm (4”)
|
1 in 57
|
150 mm (6”)
|
1 in 100
|
200 mm (8”)
|
1 in 145
|
250 mm (10”)
|
1 in 195
|
