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Tri State Presentation - 9-24-15
- 1. LAKE MEAD WATER INTAKE NO. 3 Constructing the highest pressure tunnel in the world to preserve drinking water supply for two million people
- 2. Drought in the Colorado River basin Colorado River supplies 90% of Las Vegas’ water 1983 2013 The Situation
- 3. 3 Lake Mead dropped 150 feet between 2000 and 2015
- 4. HIGH AND LOW LAKE LEVEL ELEVATIONS
- 5. Intake No. 1 Out of ServiceIntake No. 2 Out of Service Saddle Island Elevation 860’ Spillway gates Elevation 1,000’ Hoover Dam Dead Pool - Elevation 897’ Spillway Gate - Elevation 1,224’ Elevation 1,050’ INTAKE NO. 3 INTAKE NO. 2 INTAKE NO. 1 Drought Impacts
- 6. If the lake level falls below 1,050 feet: Intake No. 1 will be out of service Pumping capacity will be reduced A new intake system is needed to preserve existing capacity and water quality if lake levels continue to decline. Lake Mead Water Level Impacts
- 7. Lake Mead Intake No. 3 Approved by SNWA Board of Directors May 2005 Six contracts (originally), $817 Million total (est)… Deferred Pumping Station - three major contracts $650M estimated construction value Completion 2015 (2020 with Pumping Station)
- 8. Challenges Variable Geology: Hard, fractured Weak sedimentary Volcanic rock High tunneling pressures – 17 bar (250 psi) Intake Structure installed in 350 feet of water Intake Structure/TBM docking within a 1-ft tolerance after 3 miles of tunneling Connection to existing operating intakes
- 9. Project Location Lake Mead Las Vegas
- 10. Exist Water Treatment Facility L3P3 PUMPING STATION Intake 3 INTAKE No. 2 CONNECTOR TUNNEL Lake Mead Intake No. 3 Contracts Exist Intake 1 Exist Intake 2 INTAKE No. 2 CONNECTION & MODIFICATIONS Lake Mead Saddle Island
- 11. Exist Water Treatment Facility Intake 3 INTAKE No. 2 CONNECTION Exist Intake 1 Exist Intake 2 INTAKE No. 2 CONNECTION & MODIFICATIONS Lake Mead Saddle Island
- 12. Vegas Tunnel Constructors (Design-Build) ~ $450M Access Shaft • ~ 600’ deep • 30’ finished interior diameter Tunnel • Launch Chamber ~ 202’ long, 47’ W x 35’ H • Starter Tunnel ~ 450’ long, 27’ W x 25’ H • TBM tunnel – 20’ finished internal diameter – ~ 14,904’ long – 14” concrete segmental lining Intake Structure (elev 860) • 96’ high • 16’ diameter riser • Radial inlet Shafts & Tunnel
- 13. 13 Top-Down Shaft Construction Sequence 1) Drill 2) Blast 3) Excavate 4) Map the rock face 5) Initial Support 6) Lower Form 7) Cast Concrete Repeat…
- 15. TBM Assembly Chamber TBM Chamber Excavating Top Heading – Nov 2009
- 17. Beginning of inflow in Starter Tunnel - June 28, 2010 Incursion of Unstable Ground
- 18. Tunnel Flooding Flooding Event June 28th – July 1st, 2010
- 19. Area of Tunnel Inflows Tunnel Realignment New Alignment January 2011
- 20. 20 Realigned Starter Tunnel viewed from Cavern – 03/29/11
- 22. Drilling Jumbo Truck - Hoover Dam Diversion Tunnels http://www.usbr.gov/history/photos/dams007.jpg Back then…
- 23. 23 Tunnel Boring Machine • 24ft Outside Diameter • 600ft Long Trailing Gear • Total Weight 1500 Metric Tons • TBM was designed to be driven in rock with water head up to 17 bar (250 psi) • Capable of grouting and soil improvement ahead of the face • Machine designed and fabricated specifically for this project with strict cooperation between SNWA, Design-Builder, and Supplier (Herrenknecht)
- 24. Contract 01 TBM TRAILING / SUPPORT GEAR - 585’ long, 1500 tons TBM
- 25. Strand Jacks Used to Handle Weight and Depth
- 26. Lowering TBM Down Shaft
- 27. 27 TBM Lowering September 2011
- 28. TBM Positioned At Tunnel Face December 27, 2011
- 29. Local Mfg. of Precast Segments 5 Segments + I keystone = Ring
- 30. 30 Tunnel Segments delivered to Site
- 31. 31
- 34. Took a Toll on the Machine 2013 Mar 29
- 35. 2013/2014 TBM Repairs 3 Repair Stops 4 foot deep niche excavated in front of cutterhead
- 36. 36
- 38. Soft eye
- 41. 41 Stainless Steel Riser Assembly
- 42. 42 Stainless Steel Intake Screen
- 43. Intake Riser - Excavation Spring 2010
- 44. 44 Preparations for Excavation at lake bottom • Additional ground investigation • Bathymetry Survey • Excavation and Blasting done from crane barge • Clam and airlift “Overburden”-15,000 CY • Overburden was 6 ft of desert soil; very small silt layer about 6 inch on top.
- 45. Shaped Charges Placed on rock surface 7.5 kg / charge Placement structure 30 ft x 30 ft Small blasts at surface – Fish Scare 23,000 charges
- 46. 46 Rendering of final excavation at lake bottom
- 47. Total Tremie Concrete = 11,300 cy February and March 2012
- 48. Assembled Intake Structure Conveyed to Intake Site 15 Feb 2012
- 53. 10-ft.
- 56. Cleaning Seal with ROV
- 58. Piece of soft eye during hole through
- 59. 59 Breakthrough on December 10, 2014
- 60. 60
- 61. TBM Removal
- 62. TBM Removal
- 63. TBM Removal - Completed Apr 27, 2015
- 67. Remaining Milestones Intake No. 3 Shafts & Tunnel Operational October 2015 Final Completion January 2016
- 68. 600 800 700 900 1100 1000 1200 1300 Intake3 Intake1 RMWTF AMSWTF BROF IPS-1 IPS-2 IPS-2 Pump Operation Limit El. 1000 IPS-1 Pump Operation Limit El. 1050 Lake Elev. (feet above MSL) Intake2 IsolationGate L3PS 68 Low Lake Level Pumping Station L3PS was approved by the SNWA on December 10, 2014
- 69. L3PS CONTRACT PACKAGES Mass Excavation - Design-Bid-Build Pumping Station - CMAR Underground Mechanical and Electrical Discharge Pipelines – Design-Bid-Build Electrical Feed & Substation – Design-Bid-Build (by CRC)