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Aqueducts. 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.

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where are we
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
aqueducts1
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
supply aqueducts and tunnels

Catskill Aqueduct (1915)

Shandaken Tunnel (1928)

Delaware Aqueduct (1944)

Neversink Tunnel (1950)

East Delaware Tunnel (1954)

West Delaware Tunnel (1967)

Supply Aqueducts and Tunnels
types of aqueducts
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
profile of catskill aqueduct
Profile of Catskill Aqueduct

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

cross section of cut and cover aqueduct
Cross-section of Cut-and-Cover Aqueduct

Cut and Cover

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)

delaware aqueduct

10 km

Delaware Aqueduct

Rondout Reservoir

West Branch

Reservoir

flow profile for delaware aqueduct
Flow Profile for Delaware Aqueduct

Rondout Reservoir

(EL. 256 m)

70.5 km

West Branch Reservoir

(EL. 153.4 m)

Valves to control flow?

Sea Level

(Designed for 39 m3/s)

Hudson River crossing

(El. -183 m)

size of the delaware aqueduct
Size of the Delaware Aqueduct
  • How big does the tunnel have to be?
  • What variables do you think are important?
simplified delaware aqueduct

Hydraulic Grade Line:

Simplified Delaware Aqueduct

How high will the water rise?

Rondout Reservoir

(EL. 102.6 m wrt West Branch)

West Branch Reservoir

70.5 km

(Designed for 890 mgd or 39 m3/s)

level to which water will rise

darcy weisbach formula
Darcy-Weisbach Formula

mechanical

viscous

  • Energy loss due to _______ resistance to flow

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]

darcy weisbach equation what about f
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

frictional losses in straight pipes
Frictional Losses in Straight Pipes

Where is temperature?

Capillary tube or 24 ft diameter tunnel

Where do you specify the fluid?

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

0.0002

0.0112

0.0001

0.00005

0.01

smooth

1E+03

1E+04

1E+05

1E+06

1E+07

1E+08

R

swamee jain pipe size equation
Swamee-Jain pipe size equation

Yes!

Do the units work? _________

Moody + Darcy Weisbach =Swamee-Jain

pipe roughness
Pipe Roughness

pipe material pipe roughness e (mm)

glass, drawn brass, copper 0.0015

commercial steel or wrought iron 0.045

asphalted cast iron 0.12

galvanized iron 0.15

cast iron 0.26

concrete 0.18-0.6

rivet steel 0.9-9.0

corrugated metal 45.0

Watch these units!

delaware tunnel diameter
Delaware Tunnel Diameter

Which term dominates?

viscosity

1.01E-06

m2/s

m3/s

m

m

m

m/s2

m

Q

39

L

70500

hf

102.6

roughness

0.0006

g

9.8

The actual diameter!

D

4.12

swamee jain head loss equation
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

tunnel explorations
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?

summary
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
what is a mgd
What is a mgd?
  • Million Gallons per Day
swamee jain excel equation
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

construction of cut and cover aqueduct
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)

electric carriage for moving interior forms
Electric carriage for moving interior forms

Carriage and upper jacks are motor driven. Side jacks and turntable hand driven. (White p. 221)

traveling aqueduct building plant
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)

cut and cover arch
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)

steel forms and locomotive crane
Steel Forms and Locomotive Crane

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

cut and cover aqueduct on curve
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)

peak tunnel grade tunnel ready for concrete lining
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)

completed pressure tunnel lining
Completed Pressure Tunnel Lining

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

hunters brook steel pipe siphon
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)

section homework comments
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?
stream flow below reservoir
Stream flow below reservoir

Which season are the higher controlled flows in?

Why does low flow rate appear to have regular pattern?

What causes flows over 10 m3/s?

Note frequency of flows over 10 m3/s

How do you explain occasional low flows after 1978?

Why did low flow rate increase in 1978?