1. Aqueducts

2. Where Are We? We estimated the land area needed to supply water to NYC
How large a pipe is needed to carry the water to NYC?
We will look at the construction of the Catskill Aqueduct
We will figure out how large a pipe is needed to carry the water from the Delaware system

3. Aqueducts
How does NYC get the water from upstate reservoirs down to the city?
Pressurized Tunnels
Deep pressurized, bedrock tunnel
water flows under pressure just like in the pipes in your apartment
Grade Tunnels
Not pressurized
water surface is in the tunnel
water flow is similar to water flow in a stream

4. Supply Aqueducts and Tunnels
Catskill Aqueduct (1915)
Shandaken Tunnel (1928)
West Delaware Tunnel (1967)
East Delaware Tunnel (1954)
Neversink Tunnel (1950)
Delaware Aqueduct (1944)

5. Types of Aqueducts On Hydraulic Grade Below Hydraulic Grade
Following natural surface
open channel
cut-and-cover
Above natural surface
embankment
viaduct
Below natural surface
grade tunnel
Following or above natural surface
wooden pipe
reinforced concrete pipe
steel pipe
plastic pipe
Below natural surface
pressure tunnel

6. Profile of Catskill Aqueduct
Small Scale profile of Catskill Aqueduct, Ashokan Reservoir to Silver Lake Reservoir. (White p. 46)

7. Cross-section of Cut-and-Cover Aqueduct
Construction of cover embankment. Rock was usually excavated to a 6 on 1 slope. Minimum thickness of concrete along sides 20 ins., but usually thicker owing to disintegrated condition of surface rocks. (White p. 50)

8. Delaware Aqueduct
Rondout Reservoir
10 km
West Branch
Reservoir

9. Flow Profile for Delaware Aqueduct
Rondout Reservoir
(EL. 256 m)
70.5 km
West Branch Reservoir
(EL m)
Valves to control flow?
Sea Level
(Designed for 39 m3/s)
Hudson River crossing
(El m)

10. Size of the Delaware Aqueduct
How big does the tunnel have to be?
What variables do you think are important?

11. Simplified Delaware Aqueduct
Rondout Reservoir
(EL m wrt West Branch)
West Branch Reservoir
70.5 km
Hydraulic Grade Line:
level to which water will rise
(Designed for 890 mgd or 39 m3/s)

12. Darcy-Weisbach Formula
Energy loss due to _______ resistance to flow
viscous
Decrease in energy expressed as potential energy
Is proportional to the kinetic energy
f = friction factor [dimensionless]
L = length of pipe [L]
D = diameter of pipe [L]
g = acceleration due to gravity [L/T2]
V = average velocity of water in pipe [L/T]
hf = loss of head [L]

13. Darcy-Weisbach Equation (Function of Flow)
Solve for D

14. Darcy-Weisbach Equation: What About f?
f is a function of (V*D/ν) ______________
f is a function of pipe ___________
Take Fluid Mechanics (and Hydraulic Engineering) to learn how to use this equation...
Reynolds number
roughness

15. Frictional Losses in Straight Pipes
Capillary tube or 24 ft diameter tunnel
Where do you specify the fluid?
Where is temperature?
0.1
Moody Diagram
0.05
0.04
0.03
0.02
0.015
0.01
0.008
friction factor
0.006
0.004
laminar
0.002
0.001
0.0008
0.0004
0.0112
0.0002
0.0001
0.01
smooth
1E+03
1E+04
1E+05
1E+06
1E+07
1E+08 R

16. Swamee-Jain pipe size equation
Yes!
Do the units work? _________
Moody + Darcy Weisbach =Swamee-Jain

17. Pipe Roughness Watch these units! pipe material pipe roughness e (mm)
glass, drawn brass, copper
commercial steel or wrought iron 0.045
asphalted cast iron 0.12
galvanized iron 0.15
cast iron 0.26
concrete
rivet steel
corrugated metal 45.0
Watch these units!

18. Delaware Tunnel Diameter
viscosity
1.01E-06
Which term dominates?
m2/s
m3/s m
m/s2 Q 39 L
70500 hf
102.6
roughness
0.0006 g
9.8
The actual diameter! D
4.12

19. Swamee-Jain Head Loss Equation
Calculate head loss given a new flow…
Energy loss measured as lost potential energy
Darcy-Weisbach equation
Swamee-Jain equation for f
Reynolds number

20. Tunnel Explorations
How long does it take water to get from Rondout to West Branch (70.5 km)?
What is the Reynolds number?
What happens to head loss in the tunnel if the flow rate is decreased?
Where does excess PE go?

21. Solve the tunnel size using Moody?

22. Summary
Catskill and Delaware water is transported to NYC without use of pumps
We can calculate the size of a tunnel based on the required flow rate
The diameter of the tunnel, surface roughness, length, and elevation drop determine the maximum flow rate

23. What is a mgd?
Million Gallons per Day

24. Swamee-Jain Excel Equation
=0.66*('roughness'^1.25*('L'*'Q'*'Q'/g/'hf')^4.75+'viscosity'*'Q'^9.4*('L'/g/'hf')^5.2)^0.04

25. Construction of Cut-and-cover Aqueduct
Shows steel form and carriage; also locomotive crane used to place concrete, move outside forms, and assist in excavation. (White p. 220)

26. Electric carriage for moving interior forms
Carriage and upper jacks are motor driven. Side jacks and turntable hand driven. (White p. 221)

27. Traveling Aqueduct Building Plant
Traveling crushing concrete, mixing, and form-moving plant completing last section of aqueduct adjoining shaft 1 of contract 12. This plant built 7500 feet of aqueduct in two seasons. (White p. 223)

28. Cut-and-cover Arch This section was cast between steel
forms with steel plate in expansion joints at 60-ft intervals. Steel plates 6” x 3/8” were places in both invert and arch joints to act as water stops. (White p. 236)

29. Steel Forms and Locomotive Crane
Continuous method was here used, forms being used “telescoping.” 60- to 75-foot section concreted daily. (White p. 374)

30. Cut-and-cover Aqueduct on Curve
Arch cast with aid of steel forms built wedge-shaped in 5-foot lengths to 200 feet radius. Section 17 feet high by 17 feet 6 inches wide. (White p. 237)

31. Peak Tunnel (Grade Tunnel) Ready for Concrete Lining
Footing courses are in place. Center track for hauling material to upper portion of contract 11. Tunnel is 3450 feet long on tangent.(White p. 243)

32. Completed Pressure Tunnel Lining
Note smooth finish and close joints at invert and springing line. Concrete surface very dry. (White p. 331)

33. Hunters Brook Steel Pipe Siphon
Laying of steel pipe on concrete pedestal blocks. Later pipe was filled with water, covered with concrete and earth and lined with 2 ins. of mortar. (White p. 467)

34. Hudson River Crossing

35. Section/Homework Comments
How can you meter the alum into your filtration plant? (remember the peristaltic pump limitations)
What range of alum dosage should you be able to provide?
What happened to the stream flow below the reservoir in 1978?

36. Stream flow below reservoir
Why does low flow rate appear to have regular pattern?
Which season are the higher controlled flows in?
Note frequency of flows over 10 m3/s
What causes flows over 10 m3/s?
Why did low flow rate increase in 1978?
How do you explain occasional low flows after 1978?