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· TECI-4NICAL REPORT 1-4-70-4

SPILLWAY FOR ALUM ALUM CREEK,

CREEK OHIO

l-4ydraulic Model Investigation

by

G. A. Pickering

•

DAM

~>.t~l ~~.mf rFNTER USRARY 1' .'irtMY f:.N II r ·, ,\I HS EXPrt.:, 1f~ r "iTA"',O

VICKS 'lriu I ')tS\I?t'J

April 1970

Sponsored by U. S. Army tngineer District, l-4untingt:on

Conducted by U. S. Army l:ngineer Waterways l:xperiment Station, Vicksburg, Mississippi

This document has been approved for public release and sale; its distribution is unlimited

,

\

TECl-INICAL REPORT l-1-70-4

SPILLWAY FOR ALUM

ALUM CREEK,

CREEK OHIO

Hydraulic Model Investigation

by

G. A. Pickering

April 1970

I

DAM

Sponsored by U. S. Army Engineer District, Huntington

Conducted by U. S. Army Engineer Waterways Experiment Station, Vicksburg, Mississippi

AR M Y· M RC VICKSBURG, MISS.

This document has been approved for public release and sale; its distribution is unlimited

FOREWORD

The model investigation reported herein was authorized by the Office, Chief of Engineers, on

17 September 1968, at the request of the U. S. Army Engineer District, Huntington. The studies

were conducted in the Hydraulics Division of the U. S. ~my Engineer Waterways Experiment Sta­

tion during the period October 1968 to April 1969 under the general supervision of Mr. E. P.

Fortson, Jr., Chief of the Hydraulics Division, and Mr. T. E. Murphy, Chief of the Structures

Branch. The tests were conducted by Messrs. C. R. Styron III, A. C. Spivey, Jr., and G. A.

Pickering under the direct supervision of Mr. J. L. Grace, Jr., Chief of the Spillways and Conduits

Section. This report was prepared by Mr. Pickering.

During the course of the investigation, Mr. W. H. Browne, Jr., of the Ohio River Division

and Messrs. W. D. Barnes, J. E. Moore, and G. A. Bartrug of the Huntington District visited the

Waterways Experiment Station to discuss test results and to correlate them with design work con­

currently under way in the Huntington District Office.

Director of the Waterways Experiment Station during the conduct of the study and the prep­

aranon and publication of this report was COL Levi A. Brown, CE. Technical Directors were

Messrs. J. B. Tiffany and F. R. Brown.

111

b7GS6

\

CONTENTS

FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . .

CONVERSION FACTORS, BRITISH TO METRIC UNITS OF MEASUREMENT .

SUMMARY . . . . .

PART I: INTRODUCTION

The Prototype . . . Purpose of Model Study .

PART II: THE MODEL

Description . . Appurtenances Scale Relations

PART III: TESTS AND RESULTS

Approach Flow Conditions Spillway Capacity . . . Water-Surface Profiles . . Stilling Basin Performance Riprap Requirements

PART IV: DISCUSSION

TABLE 1

PHOTOGRAPHS 1-3

PLATES 1-13

v

Page

111

. . Vll

. lX

1

1 2

3

3 3 4

5

5 5 7 8

10

11

CONVERSION FACTORS, BRITISH TO METRIC UNITS OF MEASUREMENT

British units of measurement used in this report can be converted to metric units as follows:

Multiply By To Obtain

feet 0.3048 meters

miles 1.609344 kilometers

feet per second 0.3048 meters per second

cubic feet per second 0.02831685 cubic meters per second

.. Vll

I

SUMMARY

Tests were conducted on a 1:60-scale model of the Alum Creek Dam spillway to determine

flow conditions in the spillway approach channel, discharge characteristics of the spillway, stilling

basin performance, and flow conditions in the outlet channel. The spillway consisted of an ogee

crest with three 34-ft-wide by 25-ft-high tainter gates, a spillway chute, and a hydraulic-jump type

stilling basin.

Flow conditions in the curved approach channel to the spillway were satisfactory for the ex­

pected discharges. The discharge capacity of the original design was slightly greater than expected.

Discharge coefficients and pier and abutment contraction coefficients were determined from model

data.

The original design stilling basin did not perform satisfactorily. However, a satisfactory and

more economical design was developed. Velocities of flow were measured in critical areas of the

approach and outlet channels for use in design of riprap protection.

IX

SPILLWAY FOR ALUM CREEK DAM ALUM CREEK, OHIO

Hydraulic Model Investigation

PART I: INTRODUCTION

THE·· PROTOTYPE

1. Alum Creek Dam will be located 26.0 miles*

ware County, Ohio (fig. 1). The dam and reservoir will

grated system of reservoirs of the Scioto and Ohio River

Basins to provide flood control. A permanent pool for

municip~l water supply storage, recreation, and fish and

wildlife activities will also be provided by the project.

The principal features of the project plan are an earth

embankment, a three-gated spillway, and the outlet works.

2. The ogee weir section with a crest elevation

of 878.0* * is designed to pass the spillway design dis­

charge of 59,600 cfs at a head of 29.8 ft. Flows over

the spillway will be controlled by three 34-ft-wide by

25-ft-high tainter gates. The piers supporting the gates

will be 8 ft wide and will reduce the length of weir

from a gross length of 118 ft to a net length of 102 ft.

The ogee weir profile is based on a design head (Hd) of

25 ft, which is approximately 84 percent of the 29.8-ft

head required to pass the design discharge and will fol­

low the curve described by the equation

above the mouth of Alum Creek in Dela­

be operated in conjunction with the inte-

- N -

J

r- -----, ) ...... ...._ _ _..-../ \ ( • MARION I '-.... /\ /

I I \ I

' I I \

ALUM CREEK \ RESERVOI R

\ e NEWARK

SPRINGFIELD e J \........_ \ ANESVILLE e

.-J

• DAYTON

l \ \ I

0 J I J

/ ~...:._..~--...,

/

\

' \ l_,..

OHIO

KENTU C K Y

SCALE IN MIL ES

./

( ..,..-sc iOTO R. ~ DRAINAGE

"\,.'\ BASI N

) 0 I

I \

/' ... ) I ) PORTSMOUTH

;zo o 20 •o

Fig. 1. Vicinity map

0.270Hd)1.85 + 0.126Hd - 0.4315Hd0.375 (X + 0.270Hd)0.625

Hd0.85

(X + y = 0 .724

upstream from the crest and the curve described by the equation X 1.85 = 2Hd0.85y down­

stream from the crest. The ogee section will be followed by a chute with varying slopes that are

connected by vertical curves and terminate at the toe of the stilling basin. A general plan and

sections of the portion of the dam investigated in this study are shown in plates 1 and 2.

3. The recommended stilling basin will consist of an 88-ft-long, 118-ft-wide horizontal

apron surmounted by two staggered rows of 6-ft-high baffle piers, and a 4-ft-high vertical end sill.

Training walls will extend the full length of the basin with a top elevation of 864.0.

4. Separate conduits for low flow and municipal water supply with multilevel inlets con-

tained in the right nonoverflow section will be provided. The low-flow conduit will be contained

* A table of factors for converting British units of measurement to metric units is presented on page vii. ** All elevations (el) cited herein are in feet referred to mean sea level.

1

in the right training wall and will discharge into· the stilling basin.

PURPOSE OF MODEL STUDY

5. Although the design of the spillway for Alum Creek Dam was based on sound theoreti-

cal design practice, verification of the adequacy of the spillway and appurtenances was desired in

view of the spillway approach con[guration. The model provided a means for determining the

most satisfactory design for the spillway approach and abutments, the need, extent, and design of

riprap in the approach and outlet channels, and the adequacy of the stilling basin design.

2

PART II: THE MODEL

DESCRIPTION

6. The model (plate 1, fig. 2), built to an undistorted scale ratio of 1:60, reproduced

900 ft of the curved approach channel, a 960-ft-wide section along the dam (including the spill­

way), and 1200 ft of the exit channel. The weir, gate piers, tainter gates, training walls, stilling

1 l

J J

Fig. 2. The model

basin, and nonoverflow sections were fabricated of sheet metal ; the stilling basin elements were

made of waterproofed wood. Topography in the approach and exit was reproduced by cement

mortar molded to sheet metal templates.

APPURTENANCES

7. Water used in operation of the model was supplied by pumps, and discharges were

measured

vided a

by means of venturi meters.

reference plane for measuring

Steel rails set to grade along the sides of the flume pro-

devices.

a point gage, and velocities were measured with

by a gate at the downstream end of the flume.

Water-surface elevations were measured by means of

a pitot tube. Tailwater elevations were regulated

3

SCALE RELATIONS

8. The accepted equations of hydraulic similitude based on the Froudian relations were

used to express mathematical relations between dimensions and hydraulic quantities of the model

and the prototype. General relations for transference of model data to prototype equivalents are

as follows:

Dimension Ratio Scale Relation

Length Lr 1:60

Area Ar - L2 r 1:3600

Velocity Vr - L 1/2 r 1:7.746

Discharge <lr - LS/2 r 1:27,886

4

PART III: TESTS AND RESULTS

APPROACH FLOW CONDITIONS

9. Although the approach channel to the spillway made an abrupt change in alignment up­

stream from the spillway (fig. 3a), no adverse flow conditions were observed in this area for either

controlled or uncontrolled flows. Flow conditions in the approach area with the spillway design

flood (59,600 cfs) are shown in photograph 1. Current directions and velocities measured in the

approach area near the bottom of the channel with discharges of 42,000 and 59,600 cfs are shown

in plate 3.

10. During development of the final design for the prototype project, the retaining wall

forming the right side of the inlet channel was eliminated and the length of the nonoverflow por­

tion of the darn was increased at the right abutment (fig. 3b). Observations of flows in the

model indicated that this revision would have little, and certainly no detrimental, effect on flow

conditions in the approach area. Also, no change in the capacity of the spillway could be de­

tected from this revision.

SPILLWAY CAPACITY

11. The capacity of the spillway was found to be greater than expected. The spillway de­

sign flood (59,600 cfs) was passed at pool el 906.6 rather than the computed pool el 907.75.

Head-discharge relations for uncontrolled flow obtained from the model with the original design

spillway (4-ft-radius abutments) are shown in plate 4. These data were obtained by introducing

various constant discharges into the model and noting the corresponding upper pool elevations after

sufficient time had been allowed to permit stabilization of flow conditions.

12. Although the original spillway design was sufficient to pass the spillway design flood

with a pool elevation lower than anticipated, the left trunnion of the third gate was submerged

during this flow condition. In an effort to eliminate this, the radius on the abutments was

changed from 4 to 6 ft. This revision resulted in a slight reduction in pool elevation for the

spillway design flood. Head-discharge relations for both controlled (gated) and uncontrolled flows

with the 6-ft-radius abutments are shown in plate 4. These data were obtained by introducing

constant discharges into the model with various gate openings and noting the corresponding pool

elevation. The gate opening is defined as the vertical distance from the gate seat to the bottom

lip of the tainter gate.

13. The discharge coefficients shown in plate 5 were computed by substituting model data

into the equation

where

Q- CLH~/2

Q = total discharge over spillway, cfs

C - discharge coefficient for free uncontrolled flow

L - net length of spillway crest, ft

He - total energy head on crest, ft

5

--r -.-

a. Original design

;;J;:.

j

,

b. Revised area

Fig. 3. Approach channel to spillway

These data were obtained with walls placed in the approach area of the model (fig. 4) to

eliminate abutment contraction effects and with the crest piers removed to eliminate the pier

contraction effects. Using these coefficients and calibration data obtained with the piers in

Fig. 4. Alignment walls in headbay

coefficients (plate 6) were determined from the equation place, the pier contraction

Q = C(L - 4KpHe)H;12 The abutment contraction coefficients Ka (plate 7) were then deter­

calibration data obtained with the piers in place and the walls removed by using the mined from

equation

WATER-SURFACE PROFILES

14. Water-surface profiles over the spillway crest and along the spillway chute were observed

along the center line of the gate bays and next to the gate piers for discharges of 42,000 and

59,600 cfs and are shown in plates 8 and 9, respectively. These profiles indicate that, with the

design discharge (59,600 cfs), the upper surface of the nappe will be approximately 2 ft below the

gate trunnion and that the training walls will not be overtopped at any location.

7

STILLING BASIN PERFORMANCE

15. The design of the original stilling basin was based on a discharge of 42,000 cfs, and

stilling basin tests were conducted to develop a basin that would provide good energy dissipation

for a discharge of 42,000 cfs and adequate energy dissipation for the spillway design flood of

59,600 cfs. The stilling basin tests were conducted with tailwater elevations set according to the

tailwater rating curve shown in plate 10.

Type 1 (Original) Design

16. The original stilling basin (fig. 5, plate 2) consisted of a 120-ft-long apron at el 817.0

I

-I

I

1 T '

Fig. 5. Type 1 (original) design stilling basin

terminated with a 6-ft-high vertical end sill. For a discharge of 42,000 cfs, the normal tailwater

elevation was not sufficient to maintain a hydraulic jump within the basin and spray action (photo­

graph 2) occurred.

Alternate Designs

17. Since the original basin design did not perform

were tested in an effort to effect good energy dissipation.

described in table 1.

satisfactorily, several alternate designs

The original and alternate designs are

18. One and two rows of 6-, 8-, or 10-ft-high baffle piers were placed at various positions

within the basin (types 2-11 designs); and observations of flow conditions in the basin and exit

8

channel were made with discharges of 8500, 20,000, 42,000, and 59,600 cfs. Two rows of 6-ft­

high baffle piers placed 68 and 82 ft downstream from the toe of the spillway chute (type 3 de­

sign) were found to be the optimum number, size, and location of the baffle piers with the apron

at its original elevation (817 .0) and length (120 ft).

19. In the interest of economy, tests were conducted with the stilling basin apron shortened

to 88 and 98 ft (types 12-15 designs) . The 88-ft-long basin with two rows of 6-ft-high baffle

piers placed 50 and 63 ft downstream from the toe of the spillway chute with a 4-ft-high end sill

functioned satisfactorily for all expected discharges and tailwater conditions.

20. In an effort to further effect economy by reducing the amount of rock excavation, the

basin apron was raised to el 823.0 (types 21-23 designs). The hydraulic jump could not be con­

tained within the basin even with two rows of 12-ft-high baffle piers placed in the basin. There­

fore, the basin apron was lowered to el 819.5 (types 16-20 designs). With the apron at this ele­

vation, the jump could be contained in the basin with two rows of 8-ft-high baffle piers, but the

jump was unstable and would periodically move from 5 to 10 ft downstream from the toe of the

spillway chute. Waves in the exit channel were considerably higher with the apron at el 819.5

than with the original elevation. Thus, it was decided that the basin apron should remain at

el 817 .0.

Type 12 (Recommended) Design

21. The recommended stilling basin consisted of an 88-ft-long apron at el 817.0 with two

rows of 6-ft-high baffle piers placed 50 and 63 ft downstream from the toe of the spillway chute

and a 4-ft-high vertical end sill (fig. 6 and plate 11 ). The return walls at the ends of the trammg

' H 7 21

Fig. 6. Type 12 (recommended) design stilling basin

9

walls were eliminated smce they had little effect on flow conditions in the ex1t area with the

shortened basin.

22. Stilling basin action with normal tailwater conditions and discharges of 8500, 42,000,

and 59,600 cfs is shown in photograph 3. Water-surface profiles and velocities measured with the

type 12 design and discharges of 8500, 20,000, 42,000, and 59,600 cfs are shown in plates 12

and 13. The elevation to which the tail water could be lowered before spray action occurred with

the type 12 design for various discharges is shown in plate 10. This curve indicates that, with

the spillway design discharge of 59,600 cfs, the tailwater can be lowered 3 ft before spray action

will occur.

RIPRAP REQUIREMENTS

•

23. Riprap protection will be provided on the earth embankment face and on critical areas

of the exit channel. Although the model scale was such that the riprap could not be reliably re­

produced in the model, velocities, from which the required riprap size could be determined, were

measured in the critical areas. These velocities, measured with discharges of 42,000 and 59,600 cfs,

are shown in plate 3.

10

PART IV: DISCUSSION

24. Flow conditions in the spillway approach of the model were satisfactory for all ex­

pected discharges. No unacceptable turbulence or velocity was present.

25. Flow around the original abutments caused the left trunnion of gate 3 to be submerged

during the spillway design discharge. The radius on the abutments was changed from 4 to 6 ft to

eliminate this undesirable condition.

26. The capacity of the spillway, as determined by the model tests, was slightly greater

than expected. Discharge coefficients and pier and abutment contraction coefficients computed

from model data were comparable to those shown in Hydraulic Design Charts 111-3, 111-5, and

111-3/1 of the Corps of Engineers Hydraulic Design Criteria for heads on the crest equal to and

greater than the spillway design head. However, with smaller discharges, all of these values were

less than expected.

27. Water-surface profiles observed along the spillway chute near the training walls indicated

that the elevation of the walls was sufficient to contain the flow for the expected discharges.

28. The stilling basin as originally designed did not perform satisfactorily for the expected

range of discharges and tailwater elevations. A satisfactory design was developed by adding two

rows of baffle piers, reducing the height of the original end sill, and reducing the length of the

basin apron. Also, the return walls at the end of the training walls were eliminated.

29. Although the riprap that will be provided for protection of critical areas from high ve­

locities and wave action could not be reliably reproduced in the model, velocities from which the

required riprap size could be determined were measured in these areas.

11

Type

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

Length of Apron

ft

120

120

120

120

120

120

120

120

120

120

120

88

88

98

98

120

120

120

88

88

120

120

120

Apron El

ft msl

817.0

8 17.0

81 7.0

817.0

817.0

81 7.0

81 7.0

817.0

817.0

81 7.0

81 7.0

817.0

817.0

817.0

817.0

819.5

819.5

819.5

819.5

819.5

823.0

823.0

823.0

Baffle Height

ft

6

6

6

6

8

8

8

10

10

10

6

8

6

6

8

12

6

8

10

10

12

No. of Rows

2

2

1

1

2

2

1

2

2

1

2

2

2

1

2

2

2

2

2

2

2

Table 1

Stilling Basin Designs Investigated

Distance from Baffle Piers to

Toe of Chute, ft Row 1 Row 2

75

68

68

82

68

75

68

75

68

68

50

50

60

60

66

66

50

50

75

60

60

89

82

82

89

89

89

63

63

73

81

81

63

63

89

75

75

End Sill Height

ft

6

6

6

6

6

6

6

6

6

6

6

4

4

4

4

6

6

6

4

6

6

6

6

Basin Action

Spray over end sill

Hydraulic jump toe located 10 ft downstream from toe of chute

Jump 5 ft downstream from toe of chute

Jump 10 ft downstream from toe of chute

Jump 25 ft downstream from toe of chute

Jump at toe of chute

Jump 10 ft downstream from toe of chute

Jump 5 ft downstream from toe of chute

Jump at toe of chute, very rough in exit area

Jump at toe of chute, very rough in exit area

jump 5 ft downstream from toe of chute

Toe of jump well up on slope of chute

Toe of jump well up on slope of chute

Jump at toe of chute

Jump 5 ft downstream from toe of chute

Spray over end sill

jump 25 ft downstream from toe of chute

jump 15 ft downstream from toe of chute, very rough in exit area

Jump 25 ft down~tream from toe of chute

Jump 10 ft downstream from toe of chute

Forced jump at baffle piers

Forced jump at baffle piers

Forced jump at baffle piers

Photograph 1. Flow conditions in approach area. Discharge 59,600 cfs, pool el 906.5, gates open full

Photograph 2. Spray actton m type 1 stilling basin. Discharge 42,000 cfs, tailwater el 850.2

o. DISCHARGE 8.500 CFS, TAIL WATER EL 833.1

b. DISCHARGE 42,000 CFS, TAILWATER EL 850.2

Photograph 3. Flow conditions with type 12 (recommended) design stilling basin

Unclassified Security ClassificatiOn

DOCUMENT CONTROL DATA • R & D (Security claealllcallon of IIIIa, body of •b•lract and lndexln~ -notation muel be entered when the overall report Ia claeeltled)

I. ORIGINATING ACTIVITY (Corporate author) :z.. REPORT SECURITY CLASSIFICATION

U. S. Army Engineer Waterways Experiment Station Unr!bc:cified Vicksburg, Mississippi "=2~b.~G~Ao~u~P~>!.!lii:.!IL-----------1

3. REPORT TITLE

SPILLWAY FOR ALUM CREEK DAM, ALUM CREEK, OHIO; Hydraulic Model Investigation

4. DESCRIPTIVE NOTES (Type of report and lncluelve datee)

Final report II· AU THO RCSI (Firat name, middle Initial, Ia at nama)

Glenn A. Pickering

e. REPORT DATE 7a. TOTAL NO. OF PAGES 7b. NO. OF REFS

April 1970 33 None Ia. CONTRACT OR GRANT NO . h. ORIGINATOR'S REPORT NUM'BERCS)

b. PROJECT NO. Technical Report H-70-4

c.

d.

lib. OTHER REPORT NO(S) (Any other numbere that_,. be aeaf#Jed till• report)

10. DISTRIBUTION STATEMENT

This document has been approved for public release and sale; its distribution IS unlimited.

1 t. SUPPLEMENTARY NOTES

13. ABSTRACT

12. SPONSORING MILITARY ACTIVITY

U. S. Army Engineer District Huntington, West Virginia

Tests were conducted on a 1 :60-scale model of the Alum Creek Dam spillway to determine flow conditions in the spillway approach channel, discharge characteristics of the spillway, stilling basin performance, and flow conditions in the outlet channel. The spillway consisted of an ogee crest with three 34-ft-wide by 25-ft-high tainter gates, a spillway chute, and a hydraulic-jump type stilling basin. Flow conditions in the curved approach channel to the spillway were satisfactory for the ex­pected discharges. The discharge capacity of the original design was slightly greater than expected. Discharge coefficients and pier and abutment contraction coefficients were determined from model data. The original design stilling basin did not perform satisfactorily. However, a satisfactory and more economical design was developed. Velocities of flow were measured in critical areas of the approach and outlet channels for use in design of riprap protection.

DD .'!-: .. 1473 llt&~L.AC&e DD ~OIItM 1471, t .IAN ••• WHICH 1e Da.OL.&T& ~Dill AlltMY ue&. Unclassified

security Clautncation

Unclassified Security Classification

, 4 . LINK A LINK B LINK C KEY WORDS

ROLE WT ROLE WT ROLE WT

Alum Creek Dam Hydraulic models

Open channel flow Spillways

Stilling basins

•

.

Unclassified Security Classlflcation