Photographic
Tour and Tunneling Machine Progress
Photographic
Tour
The following online photographic tour is provided
to illustrate construction activity taking place from west to east to construct
the San Vicente Pipeline.
Tunneling
Machine Progress
Three tunneling machines
are digging the majority of the 11-mile tunnel. A hard rock tunneling machine,
called a main beam will be used for 1-1/2 miles of the tunnel. It completed
half of this work from the San Vicente Portal in March 2007. It was then removed
and reassembled in the West Shaft where it resumed hard rock tunneling to the
east. Two digger shield machines will excavate the softer ground between the
Slaughterhouse and Central shafts.
West Shaft:
The West Shaft is one of four access points that is used to excavate the San
Vicente Pipeline. The West Shaft is located near Mercy Road and Interstate 15.
Work at this shaft includes inserting the tunnel boring machine, removing excavated
materials from the tunnel, providing fresh air into the tunnel, and delivering
equipment, pipe sections, and concrete.
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The West Shaft is 36 feet in diameter and 115 feet deep. |
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To
keep track of who is underground, miners are required to tag in and out
on the brass board, when entering and exiting the shaft. |
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The first 33 feet of the West Shaft was excavated using this construction
equipment. Once the excavator reached hard rock, the contractor started
using drill and blast methods to continue shaft excavation. |
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Approximately 40 feet below the ground, miners at the West Shaft loaded
explosives in preparation for a blast. This process took up to 2 hours. |
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After blast preparation was complete, the miners were hoisted out of the
shaft using a crane and man-cage. |
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Before the blasts, the 36-foot diameter West Shaft was completely covered
with a “lid” to protect the surrounding area from flying rock
during the blast. The “lid” was placed one half at a time.
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When tunneling work was completed from
the San Vicente Portal in March 2007, the tunnel boring machine was placed
into the West Shaft to begin tunneling 4,000 feet to the east. |
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A
crane lifts and dumps excavated material from a muck bucket outside the
West Shaft. Later a truck will transport the material from the work site. |
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Trains
move people, equipment and excavated materials through the tunnel. |
Central Shaft:
The Central Shaft
is located within the Stonebridge Estates housing development in the Scripps
Ranch area, just south of Stonebridge Parkway. One of the two digger shield
tunneling machines on this project was launched from the Central Shaft and is
tunneling towards the West Shaft.
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The elliptical-shaped Central Shaft is is 70 feet deep, 60 feet long and
32 feet wide.
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Safety is the Water Authority’s number one priority. All personnel
at each construction site must wear hard hats, safety vests, safety glasses,
and steel-toed boots. |
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Earlier in the project, miners were lowered into the 70-foot deep shaft
using this steel man-cage. A cage-type elevator now transports the works
in and out of the tunnel from the Central Shaft. |
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After a starter tunnel was completed, a crane lowered a digger shield tunneling
machine into the shaft in June 2006. The digger machine, which is tunneling
westward towards the west shaft, digs through a softer conglomerate material
using a pick and paddle apparatus at the front of the machine. |
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This photo shows the digger machine operator’s view while tunneling.
The operator relies on computer technology to control the excavation process. |
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As the machine advances underground, precast concrete segments are erected
behind it to stabilize the tunnel walls. A concrete-type grout is placed
behind the segments to ensure they are in good contact with the surrounding
soil.
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As the tunneling machine moves forward, track must be installed so trains
can travel from the shaft to the machine, transporting people, equipment,
and excavated material. Here, the workers are bolting down track. |
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This photo shows the digger gantry. It is the tail-end of the tunneling
machine that supports tunnel shield utilities such as water, power, and
ventilation. |
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Excavated material exits the tunnel machine via conveyor belt and gets placed
into a container. The container is transported to the shaft by rail car
and lifted by crane outside the shaft. |
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A crane lifts the muck bucket to remove the excavated material from the
tunnel. The excavated material will be placed on site. This eliminates the
community impacts of hauling material away from the site. |
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Here the excavated material on-site is being wetted down to help to compact
it. The Water Authority plans to resell the majority of the work site parcel,
which is zoned for institutional use. The agency intends to keep only the
areas needed for the permanent inspection, maintenance, and air ventilation
structures, and for access to these structures. |
Slaughterhouse Shaft:
The Slaughterhouse
Shaft is located in Lakeside west of Highway 67. Controlled blasting was used
for portions of the tunnel going both east and west of the shaft where the underground
geology was not compatible with the tunneling machine selected for the project.
In March 2007 a digger shield machine was inserted into the tunnel at the Slaughterhouse
Shaft and is tunneling west toward the Central Shaft.
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The Slaughterhouse Shaft is 70 feet deep and 36 feet in diameter. Ventilation
ducts like those pictured are used at all of the shaft and portal sites
to provide fresh air to the miners below. |
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All of the construction equipment used in the tunneling process is lowered
into the shaft using a crane. |
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Early in the project, the San Vicente Pipeline tunnel starts to take shape
at the bottom of the Slaughterhouse Shaft as the tunnel advances away
from the shaft by drilling and blasting. The machine pictured here is
used to drill holes in the rock face. Once the holes were drilled into
the rock, explosives were loaded into the holes to blast the next section
of the tunnel. |
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This is the view inside the excavated tunnel from the Slaughterhouse Shaft.
Shotcrete has been sprayed onto the tunnel walls and roof. |
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Looking down from the top of the shaft, you can see one of the loaders
hauling rock that has been blasted from the tunnel. The material is put
in the rectangular bucket on the left and then lifted out of the shaft
with the crane. |
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This is the location of where the blasted tunnel section from Slaughterhouse
Shaft meets the perfectly rounded section excavated by the tunnel boring
machine from the San Vicente Portal. |
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Two digger shield tunneling machines are being used to tunnel the San Vicente
Pipeline. One from the Central Shaft and the other from Slaughterhouse Shaft.
Here, a piece of the digger shield is being installed into the tunnel. This
digger shield machine will need to tunnel the longest section of the tunnel,
over 21,000 feet in length. |
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Here, a tunnel support segment is being unloaded off the tunneling machine
to install and provide tunnel wall support. |
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Behind the digger shield machine are conveyor belts. The belts transport
the excavated material to the muck trains, which transport the material
out of the tunnel. through the San Vicente Portal. |
San Vicente
Portal:
The only horizontal access along the San Vicente
Pipeline is the San Vicente Portal, located near the base of the San Vicente
Dam and Reservoir in Lakeside. A portal is different from a shaft because it
is excavated horizontally into the side of a hill rather than vertically into
the ground. The San Vicente Portal is about 13 feet in diameter.
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Development of the San Vicente Portal began in December 2005. |
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The San Vicente Portal was started using the drill and blast method. About
65 feet of the tunnel was blasted before the tunnel boring machine was
used to excavate the rest of this tunnel section. |
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Miners loaded explosives into holes drilled in the face of the portal
before the blast. |
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Prior to blasting, all of the miners left the area. Typically, the explosives
removed about 10 feet of rock per blast, to advance the tunnel. |
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After the blast, the miners waited for the air to clear before entering
the tunnel. The area was then watered down for safety. The broken rock
in the tunnel was hauled away before another round of blasting began. |
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The tunnel boring machine cutterhead arrived at the portal in May 2006.
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The front of the assembled tunnel boring machine with the proud Water Authority
team pictured in front. |
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In June 2006, the 400-foot tunnel boring machine was completely assembled
and ready to be pushed into the tunnel and begin advancing westward toward
the Slaughterhouse Shaft. |
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The tunnel boring machine operator relies on computer technology to control
the machine so the finished tunnel is located exactly where it’s supposed
to be. |
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A major milestone was achieved in January 2007 when tunnel sections from
the San Vicente Portal and Slaughterhouse Shaft were connected using the
hard rock tunnel boring machine. The tunnel boring machine tunneled over
5,000 feet to meet up with the tunnel section coming from Slaugherhouse
Shaft using drill-and-blast tunneling methods. |
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Once the tunnel boring machine’s work was complete at the west end
of the tunnel, it was disassembled and transported by truck to the West
Shaft. |
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Before being placed into the West Shaft to tunnel a 4,000 foot tunnel section
going east, the tunnel boring machine was refurbished. |
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Now the digger shield tunneling West from the Slaughterhouse Shaft is supported
from the San Vicente Portal. Excavated material from tunneling activity
at the Slaughterhouse Shaft are removed by muck train through the San Vicente
Portal. |
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Here you see the excavated materials being dumped from the muck train at
the San Vicente Portal. The materials will be later picked up by a truck
and transported off site. |
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