Post on 14-Jan-2017
LAKE MEAD WATER INTAKE NO. 3Constructing the highest pressure tunnel in the world
to preserve drinking water supply for two million people
Drought in the Colorado River basin Colorado River supplies 90% of Las Vegas’
water
1983 2013
The Situation
3
Lake Mead dropped 150 feet between
2000 and 2015
HIGH AND LOW LAKE LEVEL ELEVATIONS
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
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
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)
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
Project Location
Lake Mead Las Vegas
Exist Water Treatment
Facility
L3P3 PUMPING STATION
Intake 3
INTAKE TUNNEL
DISCHARGE PIPELINES
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
Exist Water Treatment
Facility
Intake 3
INTAKE TUNNEL
INTAKE No. 2 CONNECTION
Exist Intake 1
Exist Intake 2
INTAKE No. 2 CONNECTION & MODIFICATIONS
Lake Mead
Saddle Island
Vegas Tunnel Constructors (Design-Build) ~ $450MAccess 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 & TunnelAs deep as the Wynn is tall!
13
Top-Down Shaft Construction Sequence
1) Drill2) Blast3) Excavate4) Map the rock
face5) Initial Support6) Lower Form7) Cast ConcreteRepeat…
Shaft ExcavationCompleted
January 2010
TBM Assembly Chamber
TBM Chamber Excavating Top Heading – Nov 2009
TBM Assembly Chamber
Beginning of inflow in Starter Tunnel - June 28, 2010
Incursion of Unstable Ground
Tunnel Flooding
Flooding EventJune 28th – July 1st, 2010
Area of Tunnel Inflows
Tunnel Realignment
New Alignment
January 2011
20 Realigned Starter Tunnel viewed from Cavern – 03/29/11
Starter Tunnel
CompletedJune 2011
Drilling Jumbo Truck - Hoover Dam Diversion Tunnelshttp://www.usbr.gov/history/photos/dams007.jpg
Back then…
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)
Contract 01
TBM TRAILING / SUPPORT GEAR - 585’ long, 1500 tons
TBM
Strand Jacks Used to Handle Weight and Depth
Lowering TBM Down Shaft
27 TBM Lowering September 2011
TBM Positioned At Tunnel Face
December 27, 2011
Local Mfg. of Precast Segments
5 Segments + I keystone = Ring
30 Tunnel Segments delivered to Site
31
Segment Transport
3,000 feet at
13.5 bar WHAT PSI IS 13.5
BAR ?
195.80 PSI
Took a Toll on the Machine
2013 Mar 29
2013/2014 TBM Repairs
3 Repair Stops
4 foot deep niche excavated in front of cutterhead
36
Soft eye
25’ 10”
41 Stainless Steel Riser Assembly
42 Stainless Steel Intake Screen
Intake Riser - Excavation
Spring 2010
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.
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 Rendering of final excavation at lake bottom
Intake Structure Installation
Total Tremie Concrete = 11,300 cy
February and March 2012
Assembled Intake Structure Conveyed to Intake Site
15 Feb 2012
Concrete Batch Plant
Concrete Transport Barge
Intake Structure Tie in
10-ft.
ROV Intake Inspection
Cleaning Seal with ROV
Lowering Bulkhead
Piece of soft eye during hole through
59
Breakthrough on December 10, 2014
60
TBM Removal
TBM Removal
TBM Removal - Completed Apr 27, 2015
Tunnel Steam Cleaner
Remaining Milestones
Intake No. 3 Shafts & Tunnel
Operational October 2015 Final Completion January 2016
600
800
700
900
1100
1000
1200
1300
Intake 3 Tunnel
Inta
ke 3
Inta
ke 1
Connector Tunnel
RMWTF
AMSWTF BROFIPS-1 IPS-2
IPS-2 Pump Operation Limit El. 1000
IPS-1 Pump Operation Limit El. 1050
Lake Elev. (feet above MSL)
Inta
ke 2
Isola
tion
Gate
L3PS
68
Low Lake Level Pumping Station
L3PS was approved by the SNWA on December 10, 2014
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)
Questions? Questions ?