POWER September 2022 - 21

TOP PLANT
two limited mobility grout (LMG) lines
were used for void filling and permeability
reductions in soft soil and weathered
rock in the epikarst zone.
Meanwhile, several challenges presented
themselves on the project,
including dealing with the highly weathered
rock the dam was originally built on
in the 1950s and addressing public concerns
over dam safety. Yet, the biggest
obstacle revolved around space.
" The most specific challenge related to
the completion of the project was around
the limited working area of the crest of the
dam, which originally consisted of about
a 20-foot-wide by 800-foot-long working
surface, " said Holbrook. " To overcome
this challenge TVA lowered the dam crest
by 10 feet, and also constructed upstream
and downstream buttresses, which had
multiple benefits to the project. One of
these being the final constructed work
platform that was approximately 120 feet
by 800 feet long. "
Holbrook continued: " A great level of
project planning and sequencing still had
to be orchestrated during construction
so that the project could utilize four independent
operations that had specific
spacing requirements to maintain dam
safety at all times. The team utilized
production rates from past projects and
the test section to develop the detailed
sequencing plan that allowed the tight
working area to be the most productive
while meeting our dam safety and personnel
safety requirements. "
Successful Projects Require
Teamwork
A joint venture comprised of Treviicos
South Inc. and Nicholson Construction
Co. executed the construction of the
seepage barrier wall. It included 307
50-foot-diameter
secant
pile
installations
from 80 ft. to 180 ft. in depth. " To
complete this task, the contractor had to
construct onsite infrastructure to include
a concrete batch plant, desanding plant,
and water treatment plant that supported
construction, " explained Holbrook.
Meanwhile, Phillips & Jordan Inc.
worked on rockfill berms on the upstream
and downstream faces of the
dam; drainage improvements downstream;
widened the crest to provide a
better working footprint for the cutoff
wall; added redundancy of internal erosion
protection; and added dam stability
during construction and operation.
Baker's Construction Services Inc., a
Tennessee-based site preparation contractor,
helped manage vegetation and
September 2022 | POWER
debris, and assisted in upgrades to publicly
accessible site facilities.
During the height of the project (Figure
1), manpower peaked at about 200
workers. This included specialty workers
(such as drill rig operators, grout plant
operators, and concrete batch plant operators),
and local trades and labor. " By
utilizing our local building trades through
the union, we were able to find qualified
workers within the region to support the
work, " Holbrook said.
A Focus on Safety
Safety was a top priority for project
managers. Holbrook explained that TVA
requires all personnel working onsite
to complete Occupational Safety and
Health Administration (OSHA) " 10-hour
training, " which gives supervisors and
craft personnel a solid safety baseline
before starting work. Holbrook also mentioned
a long list of additional courses
that everyone was required to complete,
and even more that were assigned based
on job duties.
" TVA and our contractors' management
highly promoted and encouraged
safety
involvement
and
awareness,
which created much enthusiasm among
the craft to participate, " he said. The effort
paid off, as the project logged 2,068,530
work hours without a lost time injury.
The
COVID-19
pandemic
caused
some disruption, but the project managed
the situation successfully. " TVA's
overriding priority was to ensure the
health and safety of everyone supporting
the project. Therefore, we took deliberate
actions like hosting virtual meetings
for workers not directly involved with
construction, socially distancing, continuously
deep cleaning, and encouraging
good hygiene, " Lawanda Hayes, TVA
Project Manager, told POWER.
Saucier noted that the project installed
more than 300 instruments for monitoring
the dam's safety during construction,
and most of the instruments will remain
available for future use, providing an ongoing
real-time dam health monitoring
system. The instruments will supplement
TVA's existing dam safety inspections
and monitoring program, which is
routinely conducted by a combination
of TVA staff from the dam safety, plant
power generation, and construction departments.
" While TVA's Dam Safety
program is regularly recognized as being
among the best in the world, these
instruments mark a continuous improvement
to our efforts to keep the dams
safe for operation, " he said.
www.powermag.com
POWER POINTS
Winning Attributes
✔ The Boone Dam project was the
largest dam safety modification
project ever undertaken by TVA in
its 89-year history.
✔ The project was completed ahead
of schedule and under budget, while
recording 2,068,530 work hours
without a lost time injury.
✔ The project installed more than
300 instruments for monitoring the
dam's safety during construction,
many of which will continue
to provide a real-time health
monitoring system for the dam.
Crossing the Finish Line
The hydrogeneration units at Boone Dam
consist of three turbines, which are capable
of providing 81 MW of clean energy.
Saucier explained that one of the
generating units was temporarily shut
down during project construction because
a temporary dam safety protection
feature blocked the discharge tube from
that generating unit. When the cutoff
wall was finished, the temporary protective
measure was cleared from the river
channel and the generating unit was restored
to operation. While no significant
upgrades were made to the unit while
it was out of service, the downtime did
provide an opportunity to complete regular
maintenance activities to ensure safe
long-term operation going forward.
The Boone Dam project achieved final
completion in May 2022. " In the end, the
project did not lose a single production
shift due to COVID and was able to finish
ahead of the planned schedule, " said
Saucier. In fact, the projected finished 17
months earlier than originally expected,
and under budget. " TVA went to great
lengths negotiating contracts to ensure
we were obtaining the best rates and being
good stewards of the resources allocated
to complete the project, " Hayes said.
In addition to a POWER Top Plant
award, the Boone Dam project has won
multiple technical awards from international
professional societies dedicated
to the practice of dam engineering and
construction. " Boone Dam is truly a
gem, both to us who live in the area and
to the world far beyond our borders, "
said Saucier. ■
-Aaron Larson is POWER's
executive editor.
21
http://www.powermag.com
POWER September 2022

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