Morris Shepard Dam,
owned by the Brazos River Authority, impounds water for
hydroelectric power and forms Possum Kingdom Lake in
central Texas. The dam, completed in 1941, is a slab
buttress dam, the largest of its kind in the U.S. When
the south gates were opened, extensive damage was done to
the river channel bank. The result was a severely limited
use of these gates and a reduction in usable reservoir
capacity.
The solution was to extend the spillway hearth and
direct the flow into the channel. Before this could be
done, a 360' x 140' area averaging 20' thick of large
stone, used to reduce erosion, had to either be removed
or consolidated.
SOLUTION
Working with
the Freese & Nichols Engineers, Fort Worth, The Judy
Company, Inc. determined there would be significant
savings by consolidating the stone with grout. Anchor
bars were needed to tie the new spillway to the
consolidated rock mass.
The original design required building a coffer dam in
the deep part of the river. Working with the prime
contractor, M. K. Eby, Bedford, Texas, it was proposed,
part of the mass be consolidated under water and the
coffer dam lap onto the stone. This resulted in
significant savings in time and dollars.
The stone was
consolidated with a cement/flyash/sand slurry and
injected into holes drilled to the bottom of the fill.
The grout was mixed adjacent to the work area and pumped
into place. The underwater work was performed by Midwest
Marine Contractors, Olathe, Kansas. At completion, 5,800
cubic yards of grout was placed.
Rock anchors were installed by The Judy Company Inc.
in the consolidation fill and in the shale foundation
bedrock. The majority of the anchors were 1.75" in
diameter and tested to 56,00 lbs. At completion, a total
of 575 were installed.
When completed, the job was honored with the Marvin M.
Black Excellence in Partnering award.
