civil engineer

1. Introduction to
Sewerage Network Design
Presented by Mazhar Alam

2. Basic Definitions
• Sewage
• Sewer
• Sewerage

3. Basic Definitions
Sewage
It is mainly liquid waste containing some
solids produced by humans and
industry. Foul water , waste water.
Grey water-Non faecal. From washing
Black water-Contains faecal matter. It
needs full treatment.

4. Basic Definitions
Sewer
An artificial conduit (or pipe) or system
of conduits used to convey sewage
from source to sewage treatment
facility.

5. Basic Definitions
Sewerage
The system of sewers that conveys
wastewater (sewage) to a treatment
plant or disposal point.
It includes all the chambers, manholes,
gravity mains, pumps, rising mains, air
valves, washouts etc

6. Design of Sewerage Network
Information Required
•Design Criteria
•Master Plan Layout Drawing
•Levels

7. Design of Sewerage Network
Design Criteria
It describes the parameters to be used in
design;
•Sewage generated per person
•Minimum, maximum & proportional velocity
•Minimum slopes
•Peaking factors
•Pipe diameters and material etc
•Minimum Backdrop height.

8. Design of Sewerage Network
Sewage generated per person
It depends on the type of occupancy or
land use details of the facility to be served.
e.g. residential, commercial, recreational.
Qasr Al Sarab sewage generated from
villas - 275 l/p/d
Hotels – 298 l/p/d

9. Design of Sewerage Network
Min. , Max., Proportional velocity
Min. velocity is normally 0.75m/s at full
capacity to allow for self cleaning.
Max. velocity is 2.5 to 3.0m/s.
Proportional velocity is the actual velocity
at given flow. 0.6m/s

10. Design of Sewerage Network
Minimum slopes
For a given diameter and roughness
minimum slope is required to achieve min.
velocity.
Dependent on the pipe diameter and
roughness e.g. for dia=200 and k=0.6 the
minimum slope is 1:240.
For lager dias the minimum slope is 1:1000

11. Design of Sewerage Network
Peaking Factor
Babbitt A/(P)^B ( A=0.176,B=5.096)
Abu Dhabi (18+sqrt(P))/(4+sqrt(P))
Harman 1+(14/(4+sqrt(P))

12. Design of Sewerage Network
Pipe dias & material
In the UAE
Minimum pipe dia is 200mm for main line
and
150mm for house connection pipe.
Material;
uPVC – for smaller dias
GRP – for larger dias

13. Design of Sewerage Network
Minimum backdrop height
•Avoid direct fall
•Splashing
•Erosion of benching
•Smooth transition
•Minimum value. 600mm to 700mm

15. Design of Sewerage Network
Master Plan Layout Drawing
•Plot – types and land use details
•Road corridor – ROW for services
•Location of STP or final disposal point

16. Design of Sewerage Network
Levels
•Spot Levels
•Contours
•Finished Road Levels

17. Design of Sewerage Network
Steps in design
• Marking the network on layout.
• Calculating the population
• Hydraulic design
• Final presentation drawings.

18. Design of Sewerage Network
Steps in design
Marking the network on layout.
• Gravitating the network
• House connection chambers- at each plot
• Manholes- maximum spacing
• Angle b/w incoming & outgoing sewer.
• Max. no. of connections to a manhole.

19. Design of Sewerage Network
Steps in design
Population calculations.
• Type of plot single storey or multi rise.
• Type of occupancy i.e. villa, hotel, office,
school, restaurant etc.
• Equivalent population.

20. Design of Sewerage Network
Steps in design
Hydraulic design.
• Spread sheet - Excel
• Software – WinDes, PipeMate, Sewer
CAD.

21. Design of Sewerage Network
Steps in design
Final presentation drawings.
To show pipe dias, invert level, cover
levels, manhole types etc.
• Manhole schedule
• Layout drawings

23. LINE DIAGRAM- SEWAGE NETROWK

24. Phase III
• Commissioned in 1993
• The Works provided an additional capacity of 25700 m3
/d
• Client : • Sharjah Municipality
Drainage Section (SMDS)
• Civil Contractor: • Six Construct
• PM /M&E RE :
• Consultant :
• M&E Contractor: • PCL
• Halcrow
• Martin Davis
• Civil RE : • Stephen Smythe
LINE DIAGRAM- SEWAGE NETROWK

26. 3D VIEW - WINDES

27. 3D VIEW - WINDES

28. MANHOLE SCHEDULE – WINDES OUTPUT

29. LOND SECTION - WINDES

30. Questions