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A Marsh-Capron mixer, of | cu. yd. capacity, steam-engine driven,
mixed the concrete and delivered it into buckets of li cu. yd. capacity.



KECONSTRUCTION OF THE STONY EIVER DAM 1031

set on flat cars. These cars were run on a narrow-gauge track from
the mixer out to a point near the west abutment of the dam and directly
under a 3-ton Lidgerwood cableway. The cableway was of 1 000 ft.
span, and was used in turn to deliver the buckets of concrete either to
hoppers and chutes for distribution laterally and under the deck of the
original structure, or, in the case of the new spillway buttresses, into
wooden bucket cars which ran on portable, narrow-gauge tracks along
the top of the buttress forms, and thus allowed the concrete to be
deposited near the ends of the forms. The cableway was also of general
utility in shifting equipment and forms, transporting reinforcing
steel, etc.

Steam was furnished both from a main plant, consisting of two
100-h.p. boilers, on the west hillside just above the spur railroad track,
and also from smaller, individual boilers placed at different parts of
the work from time to time, according to immediate needs. Such
boilers were especially necessary during cold weather because of the
condensation in the long pipe line from the main boiler plant. The
walkway through the original structure, and continuing through the
new spillway, served as a convenient carrier, on which were placed
water, steam, and compressed air pipes, which were tapped wherever
necessary. Water was supplied from a duplicate set of steam plunger
pumps, which were set up in Bay 30 and took water from a sump fed
from the river by the 20-in. sluice-gates.

An 8 by 10-in. compressor proved to be a great utility, especially
in connection with the very convenient Ingersoll-Rand "jack-hammer"
drills. The latter were used to drill holes in the original concrete, for
the purpose of embedding steel dowels, or for blasting — as was especially
necessary in cutting out the base of the deck to allow the passage of
the tie-steel from the anchoring wall at the heel. These air drills were
also used for roughening the original concrete wherever necessary.
Operated by steam, they proved only fairly satisfactory for drilling
purposes in the stone quarries, but were displaced later by a standard
Sullivan steam drill.

For pumping, an 8-in. centrifugal pump and a portable, gasoline-
engine driven, 4-in. diaphragm pump, were used as much as possible,
but in the deeper trenches steam siphons were used.

Cold-Weather Concreting Precautions. — Concrete was placed
throughout the winter of 1914-15 under temperatures as low as 10**



1022 EECONSTRUCTION OF THE STONY EIVER DAM

Fahr. The principal precautions to prevent concrete from freezing
were : First, the water used in mixing the concrete was heated so that
the temperature of the mixed batch, after being away from the mixer
several minutes, was about 55° to 75° Fahr. The water was heated by
live steam to a temperature considerably higher than that last men-
tioned because the aggregate absorbed much heat from the mortar of
the batch, despite the fact that steam pipes were used in the sand and
crushed stone supply bins to heat these materials also.

Secondly, the concrete or earth surfaces against which new concrete
was to be poured were thawed out or warmed. This was accomplished
with a jet of live steam which at the same time served to clean thor-
oughly the surfaces of old concrete.

Thirdly, the freshly poured concrete was covered with canvas. The
canvas covering was usually arranged so as to leave an air space which,
under especially severe temperatures, or with thin concrete, was warmed
with coal-burning salamanders or gasoline torches. At times, also, live
steam was turned in vmder the covering until the concrete had attained
a sufficient set.

As the result of such precautions, little concrete was frozen. Those
surfaces which were frost-bitten were usually in places where the con-
crete was relatively massive, and precautions had consequently been
relaxed.

Cost. — Despite the fact that approximately the same quantity of
concrete was placed in the reconstruction and strengthening as in the
original construction, the later work was done at a considerably less
total cost, due principally to the fact that much of the new concrete
was comparatively massive. Nevertheless, the new work required more
attention and care than if the work had been entirely of a standard
nature and free from the conditions imposed by the existence of the
original structure. Only about 25% of the total cost of the reconstruc-
tion and strengthening was expended in rebuilding (as a new spillway)
the portion of the dam between Buttresses 10 and 19. Had this portion
been rebuilt as a bulkhead section, rather than as a new spillway, the
proportion of the total cost involved therein would have been even less.
TJie remainder of the cost was expended in strengthening the original
structure and in providing features which had not at first been sup-
plied. A considerable quantity of work, especially in the form of



EECONSTKUCTION OF THE STONY RIVEE DAM 1023

cut-off wall underpinning, was not anticipated at the beginning of the
reconstruction.

Due to the facts that the new work was scattered over the entire site
and that it was carried on through the winter, the unit costs were
necessarily high. The fact that the work did not conform to standards
(except in the case of the new spillway superstructure, which constituted
a small proportion of the whole) also contributed to such high unit
costs. For the same reason, the unit costs are not of general value.
Thus the monthly average costs for excavation, exclusive of charges
for plant and overhead expenses, varied from $0.51 for new spillway
channel excavation to $7.68 per cu. yd. for excavation required for
underpinning the original cut-off near the center of the valley. The cor-
responding costs for concrete varied from $3.40 per cu. yd. in place for
Class C concrete in cut-off extensions to $13.43 per cu. yd. for Class B
concrete in curtain-wall and roofs.

The results attained in the reconstruction and strengthening of the
Stony River Dam could have been secured at far less cost — undoubtedly
less than half the cost of reconstruction — had the features involved been
incorporated in the original construction.

Personnel.

In his capacity as Consulting Engineer in charge, the writer made
inspection trips to the work about twice each month, after the recon-
struction had been begun in earnest. Mr. D. N. Showalter represented
the writer as Resident Engineer throughout the entire reconstruction.
Mr. C. W. Hotaling was Superintendent of Construction, having filled
the same position for the Ambursen Hydraulic Construction Company
after it took over the original construction work in March, 1913.

The writer desires to take this opportunity to express his apprecia-
tion of the whole-hearted co-operation of Messrs. Showalter and
Hotaling, as well as of the executive officers of the West Virginia Pulp
and Paper Company, owner; also to acknowledge the valued advice of
Daniel W. Mead and C. V. Seastone, Members, Am. Soc. C. E., with
whom he was privileged to consvilt on several occasions during the
period of reconstruction.



1034 DISCUSSION : reconstruction of stony river dam
DISCUSSION



Mr. J. W. Ledoux,* M. Am. Soc. C. E. (by letter). — Mr. Scheidenhelm

edoux. i^^g written a very exhaustive treatise on the reconstruction of the
Stony River Dam. As a result of his work he has formed two impor-
tant conclusions with which the writer heartily agrees and has been
advocating for a great many years, namely, that most masonry dams
fail due to sliding, and that too little provision is made for excessive
floods.

Heretofore, the engineer was considered conservative when, on
a small water-shed, he provided for a flood of 250 ft. per sec. per
sq. mile, but floods of several times that size are likely to occur, and
it is only a question of time before they do.

Whether provision should be made for the greatest possible flood
that will probably occur at intervals of a calculated number of years
involves several questions:

First. — Complete provision should be made, if otherwise lives may
be lost.

Second. — If only damage to property and the structure itself is
involved, then it becomes a question of whether the cost of making
complete provision is greater or less than that of the damage when
figured on a present-worth basis. For instance, if a dam is seriously
overtopped once every 50 years, causing a wash-out which is estimated
to cost $20 000 to repair, and the cost of making complete provision
to prevent that overtopping would be $10 000, the present worth of
$20 000 to be spent 25 years later at 5% is about $6 000; so, on this
basis, it would be engineering prudence to take a chance, provided no
other inconvenience or damage were entailed than the $20 000. It
involves great expense in many cases to make provision to take care
of a flood equal to 1 600 sec-ft. per sq. mile. Small water-sheds in the
eastern part of the United States, however, are subject to such floods
at very rare intervals, and that means a flow corresponding to a con-
tinuous rainfall of about 2i in. per hour.

The writer visited the Stony River Dam a few days after its failure.
The following is an extract from his report made at that time:

"The caretaker, Mr. Kerr, who lives with his wife at the house
close to the dam, stated that on Wednesday morning, January 14th,
about nine o'clock, he noticed water coming through muddy on the
down-stream side of the dam at the point where it subsequently failed.
By Wednesday night this had become much worse, and on Friday
morning at 1 o'clock he notified Mr. Allen Luke, one of the members
of the firm of the West Virginia Pulp and Paper Company, that he was
afraid the dam was going to break. He was told to open the gates
located on the inside of the dam. He stated to his people that these

* Philadelphia, Pa.



DISCUSSIOX: RECOXSTKUCTIOISr OF STONY RIVER DAM 1025

gates could not be opened on account of the stairway leading to them Mr.
being covered with ice, the temperature being below zero. Ledoux.

"By 2.30 A. M. conditions had become so grave that he notified by
telephone the town of Maysville and others located down stream along
the banks of the Stony River and Potomac. The water was rushing
through the large and increasing space underneath the dam, and by
Thursday morning at 9 o'clock the water had fallen in the dam 3 ft.
At 9.30, two bays, or 30 ft., broke down, and in half an hour three
more failed. By 11 o'clock the water was about 13 ft. below the spill-
way, and by 6 p. M., only 4 or 5 ft. of water remained in the dam. By
Friday morning it was entirely empty.

"The dam was built on a clay formation and under the up-stream
toe was a cut-olf wall, from 3 to 4 ft. thick. For a distance of 600 ft.
or more, on the east side of the valley, this cut-oif wall extended down
to rock, which, from all accounts, is of an indifferent quality, charac-
teristic of the bituminous coal formation in the vicinity of the Middle
Kittanning. The cut-off trench proved to be very difficult, due to its
depth, the number of boulders encountered, and water-bearing soil, so
that the material sometimes caved behind the shoring and made the
work dangerous. The engineers in charge of the work figured that
a considerable amount of money could be saved by not continuing on
rock, which appeared to be increasingly difficult to reach toward the
west end, and so notified the principals of the Paper Company. Not
wishing to take any chances, the Company advised a conference with
able consulting engineers, which was had, and it was decided to step
up the cut-off wall until it had a depth of about 5 ft., and, according
to information given me by the Superintendent of the Whitmer Lumber
Company, these engineers concurred in the recommendation of the
local engineers that it would be safe to make this change, on account
of the quality of the material being very compact clay, sand, and gravel.

"At the west end of the break, this cut-off wall was not more than
5 ft. deep and about 2J ft. in thickness. The break extended from
Abutment 11 to Abutment 16, and the dam is further damaged to
Abutment 19. The stepping up from rock to earth began suddenly
between Abutments 15 and 16, the first step being about 11 ft., and
at Abutment 11, the bottom of the cut-off trench was more than 20 ft.
higher than it was at Abutment 16. It is quite probable that unequal
settlement occurred due to the change from rock to earth, as this is
where the break took place, and it is hard to understand how engineers
familiar with the Austin Dam failure could have consented to any
such curtailment of depth of the cut-off trench.

"The writer does not think that the failure of the dam was due
to the Ambursen type of superstructure, but it is very clear that,
with this type, it is no more safe to economize on the depth of founda-
tion than with any other, because if it is built on an earth foundation
and water can flow through vmder it in material quantities, failure is
certain to take place.

"The strongest claim of the advocates of the hollow dam, particu-
larly the Ambursen, is that it is much more economical than the solid
gravity type, but, as a matter of fact, on account of its structural
complication, with its forms, reinforcement, and necessity of more
expensive concrete, it costs not much less for equal stability and utility;



1026 discussion: reconstruction of stony river dam

Mr. but, in order to make the comparison more favorable to their type, they

Ledoux. economize in the foundations, which, in the writer's judgment, should

be as thoroughly taken care of as with the gravity dam. The case in

point is certainly a flagrant illustration of their bad judgment in this

respect.

"According to the plans of the dam revealed in a paper presented
by Mr. Bayles in Engineering News, of January 22d, 1914, it is going
to be a very difficult matter to decide just how far to carry the repairs
so as to prevent subsequent failure of some other portion.

"It is the practice of conservative engineers never to build a masonry
or concrete gravity type of dam unless they can found it on rock for
practically the entire distance, and, in addition thereto, it is the
practice to carry a cut-oif wall down far enough underneath the main
foundation to be practically impervious to water. The writer does not
see what advantage the Ambursen type of construction possesses which
makes this requirement unnecessary, but, in the case of the Stony River
Dam, none of the main structure was founded on solid ledge rock and
only two-thirds of the cut-off trench.

"Fortunately, no lives were lost, but that was probably due to the
gradual emptying of the dam. If the break had taken place suddenly,
when the dam was full, like that at Austin, Pa., it is probable that
there would have been some loss of life, although the towns were far
enough down stream so that they could be notified by telephone at
least an hour before the water reached them.

"From an inspection of the construction, which is very readily made
from a concrete walk, running longitudinally within and throughout
the entire length of the dam, the writer is convinced that the super-
structure was built in a workmanlike manner, but the concrete appears
to be somewhat softer than it should, according to the best practice.
On account of the large amount of snow all around and the debris
in the valley on the down-stream side of the dam, and the ice on the
up-stream side, it was impossible to make any close inspection of the
soil or the geological formations.

"In one of the bays are several gates for letting off the water in
case of emergency, or for any other reason, and there is also in an
adjacent bay a large gate for the same purpose. An archway entrance
goes through the wall between these two bays. At the side of one of
them is a concrete stairway and an iron hand railing, and this, at the
time, was covered with ice, due to drippings from a crack in the
up-stream portion of the dam, making the valves inaccessible. A
casual inspection, however, showed that this ice could have been chopped
off with a hatchet or axe in a few minutes, or poles or a ladder could
have been run down from the concrete walk to the floor where the
valves were located in the adjacent bay. If these gates had been opened
wide from Wednesday morning, it is quite probable that the water
in the dam would have been so lowered as to prevent failure. It i?
better, however, for the engineering profession, that the dam did fail,
as it will further impress upon their minds the necessity of care and
thoroughness in the design and construction of dams in general.

"The nature and abundance of suitable soil and the depth of the
bed-rock indicate that the proper type of structure would have been an
earthen dam with a concrete spillway on either the east or the west



DISCUSSION : RECONSTEUCTION OF STONY RIVER DAM 1027

side-hill, and this could probably have been built safely at as low a Mr.
cost as the type that was adopted." Ledoux.

J. K. Finch,* Assoc. M. Am. Soc. C. E. (by letter). — When the fail- Mr.
ure of the Stony Eiver Dam was first reported, and before complete ^'°*^'^-
details were available, the writer pointed outf that dams of this type
were particularly weak as regards sliding. Articles on the inclined
slab and buttress dam always emphasize the great stability of these
dams against overturning, but fail absolutely to call attention to their
weakness as regards sliding. When the buttresses extend down to rock,
the rock surface should be roughened and the buttress well bonded to
it. When the dam is founded on a spread footing, four important
points must be considered.

1. — The material just below the floor of the valley, on which the
spread footing between the buttresses is placed, must be of a satisfac-
tory, compact, substantial character that will not "flow" even when wet.

The idea has seemed to be prevalent in the minds of some designers
that the slab and buttress dam of this type can be set down anywhere,
on the surface of almost any kind of ground. In a pamphlet adver-
tising a dam of this type, it is described as built on "a foundation
of quicksand and hay." Without knowing the details, it is difficult
to criticize the design, but the writer hardly considers it as con-
servative engineering. This particular type is advantageous, of course,
from the standpoint of economy, when the depth to rock is great, but
the foxmdation material is certain to be wet at times, and a soft rock,
hardpan, compact gravel and, in certain cases, a compact clay, would
seem to be the foundation range for a dam of this character.

2. — The unit pressure on the bottom of the spread footing should
be low and uniform, and the possibility of upward pressure on the
footing, or of back-wash undermining it, should be guarded against.

If the slab is inclined at the usual angle of about 45°, uniform
pressure at the base of the buttress can be secured by making the
base about 1.3 of its height. It is usually assumed that the entire
weight of, and pressure on, the slab is transmitted to the foundation
through the buttress. A small "wash-wall" at the down-stream edge
of the dam prevents undermining of the footing and also confines the
foundation material, but, in the writer's opinion, this should not be
counted on to resist sliding. Weep-holes are provided in the footing
in order to eliminate upward pressure on the base.

3. — The cut-off wall should extend down to impermeable material,
below any seams which might communicate between the reservoir
floor and the stream bed below the dam.

Practically all the failures of these dams have been due primarily
to inadequate cut-off walls. Note especially the Pittsfield, Mass., Dnin

* New York City. c .■.■

t In a letter to Engineering New-s, January 22d, 1914, p. 202.



1028 DISCUSSION : keconsteuction of stony rivek dam

Mr. and the less fortunate Stony River Dam. It is said that engineers
should profit by the expensive experience of others, but, unfortunately,
some engineers are still willing to "take a chance", usually, however,
at the expense of others. It is also far from rare to find cut-off walls
built without reinforcement in soft material requiring sheeting and
where the sheeting is subsequently pulled. It would assuredly seem
that all cut-off walls which are not built in compact earth in an
unlined trench, or in a trench in which the sheeting is left in place,
should be reinforced.

4. — Stability against sliding must be adequately provided for.

In the letter previously mentioned the writer said:

"A simple calculation shows that in the case of the Stony River
Dam a coefficient of friction of about 0.52 is required to prevent
sliding. * * * the soil at the dam site [is described] as 'a yellow clay
mixed with fine sand or gravel which is underlain by a stiff blue clay,
and some seams of a black material occurring in places.' At the
best, this material could not be counted on to give a higher coefficient
than 0.70 to 0.80 and when wet might give as low as 0.35. Moreover,
the design shows weep-holes in the spread flooring, indicating that the
designer expected water might, as it doubtless would, occur under
the base. ' Under these conditions it is difficult to see what factor of
safety there was against sliding except the shearing value of the
concrete of the cut-off wall (which in this design is unreinforced)
and the small 4-ft. wash wall at the lower edge of the floor that should
most certainly not be counted on as offering any resistance."

Lack of stability against sliding is a well-recognized point of
weakness in reinforced concrete structures of the retaining type, and
must always receive careful consideration. In retaining walls, it is
provided for by projections on the base, and, in the case of a dam
of this type, Mr. Scheidenhelm has described the various methods
available, and has finally selected the method of utilizing the upper
portion of the cut-off wall for this purpose. The writer has been
advocating the same method of design in teaching a class in rein-
forced concrete, and is pleased to see this feature treated so completely
and thoroughly in this paper. The slab and buttress dam, properly
and conservatively designed, offers economic advantages which un-
doubtedly make it a most desirable type in certain locations; Mr.
Scheidenhelm's paper clears up one of the important points regarding
its design, which has long been neglected, and is a most valuable con-
tribution to the literature of the subject. It is indeed unfortunate
that the West Virginia Pulp and Paper Company, which, like many
mother concerns, did not try to economize at the expense of safety,
but, on the other hand, insisted from the first on a reliable structure,
should have been, through no fault of its own, the victim of such
an unnecessary and expensive experience.



DISCUSSION : KECONSTRUCTION OF STONY RIVER DAM 1039

One other point in the design of these dams remains to be Mr
settled, namely, their architectural treatment. A design for a dam '""^ '
at Coatesville, Pa.,* by Alexander Potter, Assoc. M. Am. Soc. C. E.,
illustrates the only attempt, so far as the writer is aware, to design
one of these structures of really pleasing appearance. In the Stony
River Dam, as the author pointed out, no such treatment was con-
sidered necessary, but it is more and more evident that, in engineering
structures which are near cities or much traveled highways, the appear-
ance must be considered. Too often work of this kind is attempted
by a designer who knows nothing of the fundamental principles
involved, or it is left to a young architect who is familiar only with
house architecture and attempts to apply it to a totally different
structure, or applies some inappropriate form of ornamentation that
detracts from, rather than enhances, its appearance.

The Engineering Profession lacks in any "tradition", regarding
the proper treatment of engineering structures, such as the architect
has in the treatment of buildings and on which he is prone to lean,
as many believe, too heavily. Many of the engineering works in
Europe, which have been held up as examples of good engineering
architecture, are merely house architecture applied to engineering
work. The true solution of the problem is in developing a suitable
treatment, forming, for engineering structures, a tradition based on



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