Fall/Winter 1997
Volume 13 No.2
5420 Old Orchard Road
Skokie, IL 60077-1083
phone:
(847) 966-6200
Fax: (847) 966-8389
I Overtopping Protection
RCC Overtopping Protection In Harsh
Conditions
By Douglas M. Yadon,
P.E., ESA Consultants Inc.
In 1978, a significant storm event
occurred in southeastern Montana,
resulting in a peak inflow of approximately 17,000 cfs (480 cms) into the
Tongue River Reservoir. The resulting spillway and outlet works
discharges caused $1 million in
erosion damage around the existing
concrete spillway and threatened to
breach the Tongue River Dam. In
1980 the U.S. Army Corps of Engineers conducted an inspection and
designated the dam as unsafe
because of inadequate spillway
capacity and, because of downstream
residents, the dam was classified as
high hazard.
The Tongue River Dam is owned
by the State of Montana and was
constructed between 1937 and 1940
for flood protection and to store
irrigation water. Funding for the
rehabilitation of the dam was secured with the passage of the North-
f
F
ern Cheyenne Indian Reserved
Water Rights Settlement Act of 1992,
which set cost sharing arrangcments
between the state and federal governments. In 1995, the Montana
Department of Natural Resources
and Conservation (DNRC) selected
ESA Consultants Inc. to provide
design and construction contract
administration services. Schedule
requirements in agreements between
sponsoring organizations and in the
funding legislation, plus the need to
maintain normal reservoir operations
for irrigation and flood control
purposes, presented significant
challenges that led to an expedited
design and construction process.
Because of topographic constrain& the only practical location to
achieve additional spillway capacity
was over the top and down the face
(continued on page two)
of the existing zoned earth dam. To
minimize hydraulic loads and scour
at the toe and downstream of the
dam, a stair-step configuration for
the spillway was selected. A scaled
physical model was constructed to
test the hydraulic properties of the
spillway and verify the design of the
ogee weir, stair-steps and stilling
basin size and shape. The maximum
capacity of the spillway is 109,000
cfs (3085 cms), equating to a unit
flow rate of 168 cfs/ft (1.5 cms/m)
with an overflow height of 12.5 ft
(3.8 m).
Because of locally available
aggregate, RCC was selected for use
wherever practical in both the new
RCC emergency spillway and in the
rcconstructed primary spillway. The
emergency spillway was designed
with a width of 650 ft (198.2 m) with
22 steps (2.83 ft [.86 m] rise by 6.75 ft
[2.06 m] tread). The steps, together
with a 4.ft- (1.2-m) thick approach
apron and 10.5.ft- (3.2-m) thick
stilling basin slab (sized to resist
“floating” at peak discharge),
required 58,600 cy (44,750 m3) of
RCC. There were three RCC mix
designs for the primary components
of the emergency spillway. The mix
design for the lower 8.5 ft (2.6 m) of
the stilling basin was as follows:
150 lb (89 kg) cement (Type I-II
low alkali)
3708 lb (2195 kg) aggregate
176 lb (104 kg) water
6 oz (.23 I) water-reducing agent
18 oz (.69 I) air entrainment agent
per cubic yard (m3)
For the top 2 ft (.6 m) of the
stilling basin, the cement content
was increased to 275 Ib/cy (163 kg/
m3) because of exposure to harsh
climatic conditions. The steps used
150 lb/cy (89 kg/m3), protectcd as
described later; and the approach
apron utilized a cement content of
325 lb/cy (192 kg/m3) to resist
damage due to partial inundation
and harsh climatic conditions.
The two stilling basin mixe5 had
anticipated one-year compressive
strengths of 1700 psi (11.7 MPa) and
3200 psi (22.1 MPa). Due to the
extreme climatic condition and
hydraulic loads from the high unit
flow rates, the riser fact of the steps
are precast concrete panels and the
treads have an X-in. 20.cm) cover of
conventional concrete.
The aggregate for the RCC and
conventional concrete was processed and stockpiled under a
separate Phase I contract awarded to
Empire Sand and Gravel Co., Inc. of
Billings, Mont. This contract was for
$7,077.000 which also included
access roads, a temporary bridge,
site preparations, and state park
mitigation resulting from a four-foot
raise to the normal pool. The
aggregate processing was scheduled
for late fall so that the aggregate
would be cool (35° to 40°F [2° to
5°C]) when used the following year
to maximize the permissible time for
RCC laccment.
The Phase II construction
contract was awarded in February
1997 to Barnard Construction Co.,
Inc., of Bozeman, Mont. The total
price of about $8 million included
approximatelv 8,000 cy (6,110 m3) of
conventional concrete, and the
58,600 cy (4,750 m3) of RCC. The cost
of the RCC was $17.50/cy ($22.90/
m3) for mixing, transporting, spreading, compacting. and curing. The
unit price for cement for RCC was
$112/ton. The precast panels were
fabricated on site at a cost of $11.
ft2($125.45/m2).
Gears, Inc., of Crested Butte,
Colo, provided an Aran 280
pugmill to mix the RCC, which was
then transported to the placing
surface using conveyors and
Superswingers provided by Rotec
Industries of Elmhurst, III. The
conveyor system was designed for a
capacity of 130 cy / hr (99 m3 / hr) but
did peak at 160 cy/hr (122 m3/hr)
after a breaking-in period. The
original specifications required that
the contractor work two IO-hour
shifts per day, six days a week.
However, because of hot weather
conditions and other technical
considerations, the contractor
worked a single night shift each day
during the hotter months of August
and September 1997.
RCC placement began in the
stilling basin in mid-May with the
steps completed by late August. The
last of the RCC was placed for the
approach apron in late September.
To minimize RCC surface damage
and lift joint cleaning, a Case 55OE
rubber tracked dozer was used to
spread the RCC.
The reconstruction of the
principal spillway is currently in
process under a Phase III contract
awarded to Empire Sand and
Gravel for $14.4 million, and is to be
completed b y spring of 1999. Weak
fractured rock locally referred to as
“clinker”) will be excavated from
beneath the new conventional
concrete labyrinth weir and flip
bucket and replaced with 46,000 cy
(35,145 m3 of RCC with a cement
content of 140 lb/cy (83 kg/m3).
This RCC was bid at an equivalent
unit cost of $21.09/cy ($27.60/m3)
for mixing, transporting, spreading,
compacting, and curing. Cement for
RCC was bid at $1 IO/ton. The RCC
will provide a positive upstream
Cutoff beneath the weir, a firm
foundation for anchoring the
conventional concrete floor slab,
and a stabilizing mass at the flip
bucket discharge. An additional
10,000 cy (7,646 m3) of conventional
concrete will be used to construct
the labyrinth weir, spillway chute,
flip bucket, and 700 ft (213 m) of
liner for a 9-ft (2.7-m) diameter
tunnel
FalllWinfer 1997
RCC Newsletter
Concrete Batch Plant is Key for Warehouse Pavements
warehouse Specialists, Inc. (WSI), a
premier owner and operator of
warehouse facilities in the U.S., is also
one of the most innovative and cost
conscious. WSI recently selected
roller compacted concrete as the
replacement pavement for four
Wisconsin facilities totaling over
57,000 sy (47,658 m2). This, however,
was RCC with a twist. The contractor,
Murphy Concrete & Construction
(MCC), mixed the RCC in its ready
mix concrete plant. In addition,
MCC’s asphalt crews were trained to
place the concrete pavement. This use
of available equipment and personnel
provided significant savings for WSI
and resulted in the largest series of
RCC placements to use ready mix
concrete batch facilities.
with PCA and the O’Hare site visit
helped solidify WSI’s decision to go
with RCC. However, a major concern
remained regarding the ability of
MCC to properly place RCC pavement without having prior RCC
construction experience.
RCC. Typically, RCC is produced in a
high-volume pug mill mixing plant.
However, with MCC’s modem ready
mix plants nearby, plans were made
to use one of the MCC plants.
The plant was a Rex Model S
concrete paving plant with a batch
Cost and Performance Bring
RCC to Wisconsin
WSI has been in the warehouse
business since 1966. Virtually all of
its facilities are paved with asphalt or
unsurfaced aggregate. These flexible
pavements have not held up to the
year and tear of warehouse operations resulting in frequent repairs
and high maintenance costs. In an
effort to improve operations, WSI
looked for a high-performance
pavement at a reasonable cost. The
design criteria called for a lowmaintenance pavement to withstand
heavy truck loading of over 400
vehicles per day. RCC pavement,
with engineering properties similar
to conventional concrete, proved to
be the right choice.
Intrigued but needing more solid
information, WSI, under the direction
of Kevin Wentland, investigated
carefully. With help from Bill Gault
of Medusa Cement, WSI and MCC
spoke with cement industry experts,
culminating in a visit to the Portland
Cement Association headquarters.
They learned about RCC’s cost
benefits, design considerations and
construction techniques through a
personal presentation by PCA staff.
WSI found that thousands of square
yards (m2) of RCC for industrial
applications have been placed in
Canada, with similar harsh climatic
conditions as those found in Wisconin. These pavements have provided
years of productive service life. In
addition, WSI visited the completed
RCC pavement for the O’Hare
Reservoir project (see RCC Newsletter
Spring/Summer 1997). Discussions
‘<
Industry Team Assembled
Although MCC was an experienced
concrete and asphalt paving contractor, they had never worked with
RCC. WSI and MCC realized that for
the highest quality RCC pavement,
the proper paving equipment and
expertise in placing the RCC would
be necessary. WSI contacted Tim
McLaughlin of Standard General
Construction Inc. (SC), Birmingham,
Ala. SG had both RCC paving
experience and an available heavyduty RCC paver. Ron Peltz of Peltz
Contracting Inc., Alliance, Neb.,
another RCC specialty contractor,
also provided valuable assistance
during construction. Thus WSI had
gathered a strong industry team of
MCC, SG and Peltz to bring RCC
pavement technology to Wisconsin
Concrete Batch Plant Mixes RCC
For the initial project, WSI chose to
replace a deteriorated asphalt pavement for a warehouse facility in
Appleton One of the unique aspects
of this project was the use of MCC’s
ready mix batch plant to mix the
capacity of 12 cy (9.2 m3). Procedures
for mixing the RCC in a rotary drum
ready mix plant had to be altered,
especially mixing time and batch
size. The dry consistency of RCC
(only 6.1% water content) required
that the mixing time be increased
from the normal 60 second batch
time to 3 to 4 minutes per batch.
Because of the bulking tendency of
the zero-slump RCC, individual
batches were reduced from 12 cy (9.2
m3) t o 8 to 9 cy (6.1 to 6.9 m3). After
mixing, the RCC was discharged
directly into dump trucks and
hauled to the nearby placement site.
Asphalt Crew Takes on
Concrete Pavement
Using a ready mix plant was not the
only unusual aspect of this project.
MCC’s skilled asphalt paving
division now had the task of placing
a concrete pavement. However, the
nature of RCC made the operation
not much different from placing
asphalt. Tim McLaughlin of SG
(continued on page four)
PORTLAND CEMENT ASSOCIATION
5420 Old Orchard Road
Skokie, IL 60077-1083
Route to:
Pavements
continued from page 3
trained MCC’s asphalt crew to
operate SG’s ABG 511 paver, which
is a heavv-duty asphalt type paver
with a vibrating screed and dual
tamping bars. It is capable of
producing RCC compacted to
greater than 90% modified proctor
density prior to any rolling. Ron
Peltz of Peltz Construction provided additional assistance in the
paver’s operation resulting in
improved surface appearance.
RCC was placed at full-depth,
from 5 in. (127 mm) for car parking
areas, to 7-11 in. (178-279 mm) in
the shipping dock and truck parking lot. Paving widths varied from
10 to 15 ft (3 to 4.6 m). Dual steel
drum rollers compacted the RCC to
a minimum 9 8 % density. Gene
Vandemark, General Manager of
MCC’s Concrete Division, noted
that this was the first time the
concrete and asphalt divisions had
ever worked together in a single
paving project. Both divisions were
able to modify and integrate their
operations to successfully manufacture and place the RCC pavement.
More RCC to Come
The first project in Appleton was
considered a trial project. By the
e n d of the project, WSI saw that the
construction team had produced a
high-quality,
densely-compacted
concrete pavement with excellent
surface texture. WSI felt confident
that they would avoid the high
maintenance expenses previously
experienced with flexible pavements, at an initial cost only slightly
above asphalt. Because of this
success, two more facilities were
constructed in Appleton. Not to
miss out on a cost-saving opportunity, the ARG; paver was then
transported 80 miles (129 km) west
to Wisconsin Rapids to pave a
fourth warehouse. Each of these
facilities was approximately 14,000
sy (11,700 m2). With warehouse
operations throughout the U.S., WSl
is considering use of RCC at many
of these facilities.
m
RCC Newsletter is published
by the Portland Cement Association, an organization of cement companies in Canada and
the United States.
Direct comments, address
changes and subscription requests to Wayne Adaska,
Portland Cement Association,
5420 Old Orchard Road,
Skokie, Illinois 60077-1083
(847/966-6200).
Items from this newsletter
may be reprinted, with
acknowledgement,
without
prior permission.
RCC Seminar/Construction Tour
A technical seminar on RCC dam
and dam rehabilitation methods is
scheduled for May 18-19, 1998, in
Allentown/Bethlehem, Pa. This
seminar will feature a construction
tour of the New Penn Forest Dam
which incorporates many current
design and construction’concepts for
RCC dams.
The seminar will begin with a
day-long technical session presented
by a variety of speakers experienced
in both the design and construction
of RCC gravity dams and RCC
overtopping protection projects. The
construction tour the following day
will give participants the opportunity to observe the actual construction of the largest volume RCC dam
east of the Mississippi River, which
will utilize an all-conveyor delivery
system.
Don’t miss this opportunity to
learn from the experts and see a
major RCC dam under construction
For more information, including a
copy of the program, contact Randy
Bass, Portland Cement Association,
517 Haralson Dr., Lilburn, Georgia
30047, phone 770-921-5894.
rE