Sequachee Valley news. (Sequachee [Sequatchie], Tenn.) 1896-1952, 1909-01-14

They are now drilling double line Of
| four-inch holes with eighteen-inch in
terspaces on either side Of the power
house to whatever depth may be neces-
sary to reach the assures, which are to
! be filled in with cement: method
which seems to be the very best that
coIld"have been adopted.
In the eastern half of the rock ex-
cavation for the power house the work
has been rendered extremely difficult
and expensive by reason of the cutup
condition of the prehistoric river bed
exposed and the necessity of making
forty feet of excavation of rock in con-
tracted limits where seams and leaks
were continually encountered. This
material was found to be conglomer
ate mass of boulders interspersed with
assures filled with quicksand and green
clay and having a considerable amount
of water: the same conditions being
met with in the construction of the
core wall
The earth excavation of rock for the
power house, intake and tail race has
involved the removal of 200, 900 cubic
yards of loan, silt and sand and grav-
ell and was made extremely difficult by
the constant thrush of water. The
materials thus obtained have been us
ed in forming the earth embaukments
of the core wall to the east of the riv-
er; while the rock excavation has been
utilized in advancing the crib Golfer
dam work across the river around the
lock pit and mower house, and for the
Cyclopean masonry of the dam.
The contingencies of the work re-
quire the construction of more than a
mile of cofferdams, the design in use
being rock filled crib supporting a
clay chamber-the cribs being twenty
feet wide and built to a height of
twenty feet and" constructed of pine
logs and filled with rock; the clay
chambers, five feet in width, being
built of six-inch by eight-inch ranger.
The chamber is filled with clay and
gravel protected on the outside by rip
rap and large stones.
The materials obtained for the mar
ufacture of the concrete used seem to
be of an excellent quality, the gravel
being largely of flint pebbles and well
graded, while the method of dredging
and treating the materials leaves it al
most entirely free from foreign mat.
ters. This material is obtained from
the bottom of the river by means of a
chain bucket dredge carrying its own
screening and washing apparatus, and
has capacity of 100 cubic yards pei
hour.
Little has as yet been done on the
excavation for the foundation of the
dam across tue river. The gauge fol
low water shows about five feet, fol
high water four feet while the heigh'
of the dam will be sixty-tive feet 81
that the base of tine foundation will liz
some twenty-five feet below the bottom
of the river bed, and as about ten fee
of this is sand and other loose mat ria
there will remain fifteen feet of SOLE
rock excavation beneath the river bed
This should be ample for SUSTAINING
the heaviest shocks, and will effect
lively prevent undermining if no Sc
rious assures are encountered.
The quantities of material to b.
handled are as follows as given by th
engineers: Earth excavation, 800, 00
cubic yards; embankment, a., 900 Gu
bic yards; rock excavation, 90, 600 Gu
bic yards concrete masonry, 10, 00
, cubic yards; sand for concrete, 80, OO
X cubic yards; fill in cofferdams 169
600 cubic yards of rock; fill i'll ella,
> chambers, 80, 900 cubic yards of ella,
and gravel. Other materials consist o
steel in powerhouse, stone pavemen
i of embankments, rip-rap and appurt
; enances in lock pit.
The work is being constructed prin
u cipally witHth aid of fifteen S0-foo
3, beam still-leg derricks, with a capaci
= ty OF ntteen tons each, mounted o.
Il cribs; two locomotive cranes. togethe
with three cable ways spanning tn
{ river to the tower Of the powerhouse
their span being 1, $50 feet with SUP
porting capacity of ten tons each; tw
large air compressors, one on eithe
side of the river, furnishing air 70
the drills and for clearing the pump
. after FOODS a feet composed of on
. large river steamboat, a gasoline boat
= twelve barges, 100 feet by 81 feet tw
" derrick boats, with capacity of te
tons each, a floating mixing plant
while a railroad three miles in lengt
y connects with the Nashville, Chatta