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Lake History:
Then and now
How to build a dam, 101
How do you build a dam in the
middle of a river? An aerial photograph of the dam site taken on
August 19, 1958 (Fig. 1) gives the reader an excellent view of just
how engineers accomplished this feat. Engineers have to contend with
this problem every time they design a dam. Regardless of the size,
type, material make-up, even location of a dam, one thing is always
true. You must deal with the river that will eventually create the
reservoir behind the dam you are building. In Hartwell Dam’s case
engineers decided to use steel and earth cofferdams to push the
river to one side (South Carolina embankment) which would allow the
block foundation area to remain dry. This process only involved
those block sections that were constructed in the river channel.
The block sections constructed on dry land on the Georgia and South
Carolina embankments did not have to contend with the river flow.
In Fig. 2 you get a close up
view of one of the block foundation areas seen from the air in Fig.
1. The huge steel cofferdams that are compacted with earth form a
giant wall at left background looming high above the block
foundation area. Behind this wall of steel and earth is the Savannah
River making its way around the construction site on its way to the
Clarks Hill Reservoir. At this time the Richard Russell Dam has yet
to be authorized for construction. Workers are readying the
foundation area for the first concrete pour which will form the
foundation for the blocks construction. Your view is downstream and
you can see the faint outline of the U.S. 29 (Louie Morris Memorial
Bridge) in the background.
In Fig. 3 you get another aerial
view of the dam site from approximately the same location as the
photograph in Fig. 1, however nearly a year has passed. Workers have
completed the block foundation work and have formed six of the
initial blocks. The river is now able to flow between three of the
blocks. Concrete blocks have been formed in the area to the right
that allowed the river to flow downstream a year earlier.
If you look closer at the blocks
three of them have conduit openings in the face. Nearly a year
later on April 22, 1960 (Fig. 4) and the gaps between the blocks
have been poured with concrete. The dam base blocks now span the
entire width of the Savannah River. Three emergency conduits called
sluices will allow the river to continue flowing downstream. The
sluice at far left is only temporary and once the dam is completed
it will be sealed off. In the future when the dam is in full
operation the two remaining sluices and tainter gates at the top of
the spillway will function as emergency release points of water if
the need arises.
Fig. 1. Only a small portion of
the river channel to the right of the steel cofferdams is allowing
water to flow downstream while preparation of the foundation for
block construction is ongoing.
Fig. 2. The ancient Savannah
River bed is cleared all the way to its rock foundation in
preparation for a concrete pour.
Fig. 3. You get an excellent
view of how engineers constructed the dam in the middle of the
Savannah River without impeding its flow downstream.
Fig. 4. The completed portion of
the concrete dam now stretches across the main Savannah River
channel. The temporary sluice at far left will be sealed off as the
spillway and remaining sluices can release excess water if the need
arises.
 David Coughlin is researching
and preparing to write a book about the history of Hartwell Lake and
its dam. For more information visit
www.hartwelllakehistory.com.
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