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Aqueducts

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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Aqueducts

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

  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 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)

  8. 10 km Delaware Aqueduct Rondout Reservoir West Branch Reservoir

  9. 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)

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

  11. 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

  12. 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]

  13. Darcy-Weisbach Equation (Function of Flow) Darcy-Weisbach 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 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

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

  17. 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!

  18. 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

  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 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?

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