1. 26 – Wastewater Conveyance System Design 2
April, 25, 2013
Professor Doran
CEE 410

2. CEE 410

3. CEE 410

4. Separate handling, treatment and reuse of: Blackwater Greywater
Yellow-water
CEE 410

5. Learning goals for today are to improve understanding of:
Force Main Design
Structural Considerations for Sewer and Force Main Construction
Review of Drawing Notations for Sewer and Force Main Construction
Team Design Time

6. Learning goals for today are to improve understanding of:
Force Main Design
Structural Considerations for Sewer and Force Main Construction
Review of Drawing Notations for Sewer and Force Main Construction
Team Design Time

7. Learning goals for today are to improve understanding of:
Force Main Design
Structural Considerations for Sewer and Force Main Construction
Review of Drawing Notations for Sewer and Force Main Construction
Team Design Time

8. Learning goals for today are to improve understanding of:
Force Main Design
Structural Considerations for Sewer and Force Main Construction
Review of Drawing Notations for Sewer and Force Main Construction
Team Design Time for Design Project B

9. Key Force Main Design Concepts
Hydraulics
Layout
Installed Depth

10. Key Force Main Design Concepts
Hydraulics
Layout
Installed Depth
Materials
Utility Crossings
Stream Crossings

11. Key Force Main Design Concepts
Static Head Normally Discharge Elev – Maximum Operating Level in Pump Station (not emergency)
Force Main Hydraulics

12. Key Force Main Design Concepts
Static Head Normally Discharge Elev – Maximum Operating Level in Pump Station (not emergency)
BUT – intermediate conditions (high point along route) may control
Force Main Hydraulics

13. Key Force Main Design Concepts
Static Head Normally Discharge Elev – Maximum Operating Level in Pump Station (not emergency)
BUT – intermediate conditions (high point along route) may control
Design Velocity 2.0 – 5.0 ft/s (0.60 – 1.5 m/s)
Force Main Hydraulics

14. Key Force Main Design Concepts
Use standard pipe sizes
Long-radius bends, wyes preferred over standard bends and tees
Hazen-Williams normally used
C ~ 120 for Ductile Iron; C ~ 130 for PVC or HDPE
Force Main Hydraulics

15. Key Force Main Design Concepts
Equivalent length normally computed to include pipe length together with bends, tees, valves
Minor loss calculations normally only used for entrance (pump suction) and discharge (at end of main), and reduction and expansion fittings
Force Main Hydraulics

16. Key Force Main Design Concepts
Force Main Hydraulics

17. Key Force Main Design Concepts
Force Main Hydraulics

18. Key Force Main Design Concepts
Force Main Hydraulics

19. Key Force Main Design Concepts
Air Release Valve at High Points in Force Main
Force Main Hydraulics

20. Key Force Main Design Concepts
Air Release Valve at High Points in Force Main
Force Main Hydraulics

21. Structural Considerations
16,000 lb (7,260 kg)
Structural Considerations

22. Structural Considerations
Failure Load
Allowable Load = LF(Failure Load)
Structural Considerations

23. Structural Considerations
Marston’s “C”
H/B
For Flexible Pipes (DI, Plastic): W = C ω BD where,           
W = Dead load due to backfill (kN/m),
C = A dimensionless coefficient,
ω = Unit weight of the backfill soil (kN/m3),
B = Width of the trench at the crown of the pipe (m), and
D = Pipe Diameter (m)
Structural Considerations

24. Structural Considerations
Need to add Live Load and Superimposed Load
Marston’s “C”
H/B
For Flexible Pipes (DI, Plastic): W = C ω BD where,           
W = Dead load due to backfill (kN/m),
C = A dimensionless coefficient,
ω = Unit weight of the backfill soil (kN/m3),
B = Width of the trench at the crown of the pipe (m), and
D = Pipe Diameter (m)
Structural Considerations

25. Structural Considerations

26. Structural Considerations
F = 2PAcos45°
F = PA
F = PA
Structural Considerations

27. Structural Considerations
F = 2PAcos45°
F = PA
F = PA
For 12-in Dia Pipe with P = 100 psi
F = 2(100 lbf)π62(sq in)(0.707)
(sq in)
F = 16,000 lbf
Structural Considerations

28. MH Numbering
Drawing Nomenclature

29. MHA1a
MHA1b
325 LF 8-in San
305 LF 8-in San
MHA1c
Drawing Nomenclature

30. Drawing Nomenclature Table of Manhole Gravity Sewer Connections MH No.
North
East
South
West
A1a NA
8-in IE
A1b IE IE
A1c IE IE
A1d
Note: Compass directions are approximate; see drawings.
Drawing Nomenclature

31. Drawing Nomenclature 6-in FM c El 6472.50 L 806 LF 6-in FM
22 ½ deg EL
c El L
6-in FM
45 deg EL
c El L
Drawing Nomenclature

32. H2S + 2 O2  H2SO4
Drawing Nomenclature

33. H2S + 2 O2  H2SO4
Drawing Nomenclature

34. Typical Submersible Pump Sta

35. Typical Submersible Pump Sta