The
Tennessee-Tombigbee Waterway is the largest water resource project ever built in the United States. It is one of the engineering marvels of the world. The major features of
the waterway are 10 locks and dams; a 175-foot deep canal connecting the Tennessee
River with the Tombigbee
River
watershed; and, 234 miles of navigation channels. The federal project was designed and
constructed by the U.S. Army Corps of Engineers with annual appropriations from the U.S.
Congress. Corps employees performed most all of the engineering and design work and
served as the construction manager for the project. Actual construction was accomplished
by private contractors selected to build specific components of the project by competitive
bids.
The Mobile District of the Corps was responsible
for the southern 195 miles of the waterway, including 9 of the locks and dams. The
remaining 29 miles of the project, including Whitten Lock and Dam, the third highest single lift lock
east of the Rockies; and, the massive excavation of the so-called Divide Cut, were wert the responsibility of the Corps'
Nashville District.
The Tenn-Tom is the largest earth moving project in history, requiring
the excavation of nearly 310 million cubic yards of soil or the equivalent of more than
100-million dump truck loads. By comparison, the French dug about 105 million
cubic yards in building the Suez
Canal and a total of 210 million cubic yards of earth were removed from the Panama
Canal.
Construction began in December 1972 with the building of the Howell Heflin
Lock and Dam (formerly Gainesville LD) at the southern end of the waterway. A total of
2.2 million cubic yards of concrete and 33,000 tons of reinforcing steel were used in
building the 10 locks. The 110 x 600-foot lock chambers hold an average of about 20
million gallons of water, an amount equivalent
to that used each day by a city
with a population of about 60,000. A series of
culverts, resembling large tuning forks as shown here, were constructed in the bottom of
each lock to allow the lock chambers to empty or fill in about 20 minutes without any
turbulence or whirl pools that might cause safety concerns for boats being locked. The
safe raising or lowering of the water levels inside the chamber is most important since
some of the commercial tows consist of shipments of as much as 6 million gallons of fuel
as well as chemicals. Waterways are the safest mode for moving these kinds of commodities.
The Tennessee-Tombigbee was the first large
water resource project constructed in accordance with the provisions of the National Environmental Policy Act of 1969 (NEPA) [Click your browser BACK button to return to this document]. Major design changes were
made to better accommodate environmental quality as mandated by NEPA. An example of these
changes in the project's design is the nearly 50-mile levee shown above on the left side
of the first photo. The levee was added to prevent the destruction of prime wildlife
habitat along the upper reaches of the Tombigbee River caused by permanent flooding from
the impoudments of 5 locks.
One of the most challenging features
of the waterway to design and construct was the so-called Divide Cut, a 27-mile canal that
connects the Tenn-Tom with Pickwick Lake on the Tennessee River.
To build this navigation canal, which
is 280 feet wide and 12 feet deep, required the removal of 150 million cubic yards of
earth. Seven private contractors, using conventional equipment, completed this awesome
task in less than 8 years.
The deepest cut was 175 feet with an
average excavation of 50 feet along the entire reach of the canal. The two photos shown
here offer a before and after look at this construction challenge.
The dirt removed from the Cut was placed in nearby
valleys. These spoil disposal areas were carefully contoured and landscaped in a manner
that precluded one of the most potentially serious environmental problems associated with
the waterway construction.
Construction of the waterway also
involved the relocation or replacement of 8 railroad bridges and 14 highway
bridges. The
States of Alabama and Mississippi were
responsible for building the highway bridges, which cost $155 million. The
accompanying photo is of a railroad relocation in the Divide Cut, showing a massive earth fill that had to
be built to provide uninterrupted rail service and later was removed when the bridge was
completed.
Special programs were implemented
during construction to help increase regional economic benefits. The waterway region was
one of the most economically depressed sections of the nation at that time. Moreover, many
of these counties are rural and some have majority populations of minorities. Many of the
waterway residents had no working experience or skills in heavy construction crafts.
Some unprecedented measures were
undertaken to help insure that the lives of these economically deprived people were
improved by the waterway's construction. For example, a local hiring preference clause was
included in each construction contract that required the contractor to attempt to hire as
much of his work force as possible from within a 50-mile radius of the waterway.
A very progressive minority hiring program was instituted that included employment goals
for each construction craft. A separate program with specific goals was also established
for female workers. To meet these ambitious objectives, intensive job training efforts
were implemented, including a unique worker-trainee program that required the close
cooperation of the affected
trade unions, the contractors and the Corps of Engineers.
These social programs were very
successful. Construction of the waterway required 25 million man-hours of labor. About 85
percent of these workers came from the waterway corridor. At the end of construction, the
work force included 33 percent minorities and nearly 5 percent female workers. Also,
nearly $450 million of work was subcontracted to minority firms.
Because of these successes, the Carter
Administration selected the Tenn-Tom as a national demonstration project of how to
maximize local economic impacts of a large public works project built in a rural area.
These programs not only accomplished
socio-economic objectives, but they also precluded the typical "boon and bust"
conditions generally experienced when large projects are built in sparsely populated areas
that do not have the infrastructure or services to support a large influx of workers.
Construction was completed on December
12,1984 exactly 12 years after it began. The total cost was $l.992 billion, including
non-federal costs. The waterway will have a physical life of 100 years or more and an
assumed economic life of 50 years. This investment will return economic benefits to many
generations to come.