AD-A26 5 31I ,AD-A265 31Technical Report HL-93-1March 1993

uti Army Corps M 1

of EngineersWaterways ExperimentStation

St. Stephen Powerhouse Fish Lift,Cooper River Rediiersion Project,South Carolina

Hydraulic Model Investigation

by Thomas E. Murphy, Jr., John E. Hite, Jr.Hydraulics Laboratory

DTICS ELECTE

MAY14 1993 DIEjL

Approved For Public Release; Distribution Is Unlimited

93-10445

Prepared for U.S. Army Engineer District, Charleston

The contents of this report are not to be used for advertising,publication, or promotional purposes. Citation of trade namesdoes not con titute an official endorsement or approval of the useof such commercial products.

4MSPRINTE ON RECYCLED P'APER

Technical Report HL-93-I1March 1993

St. Stephen Powerhouse Fish Lift,Cooper River Rediversion Project,South Carolina

Hydraulic Model Investigation

by Thomas E. Murphy, Jr., John E. Hite, Jr.

Hydraulics Laboratory

U.S. Army Corps of Engineers Accesion For

Waterways Experiment Station NTIS CRA&I3909 Halls Ferry Road DTIC TABVicksburg, MS 39180-6199 U,.annoutced

Jutification. ..........

By .......... .................. ............ ..

D~isti ibution I

- Availability Codes

I Avail an~d IorDist Special

Final report

Approved for public release; distribution is unlimited

Prepared for U.S. Army Engineer District, CharlestonCharleston, South Carolina 29402-0919

Ui

US Army Corpsof EngineersWaterways Experiment NStation

LABORATORY

GEET

FRC NPOW~AT)ON CqOflA

PUBLIC AFFAIRS OFFICELABORATORY -U. S. ARMY ENGINEER

WATERWAYS EXPERIMENT STATION

3909 HALLS FERRY ROADVICKSBURG, MISSISSIPPI 391806199

PHONE; (601)634.2502STRUCTURIS

AREA OF AESEAT". - 7 ,

Waterways Experiment Station Cataloging-in-Publication Data

Murohy, Thomas E.St. Stephen Powerhouse fish lift, Cooper River Rediversion Project, South Caro-

lina : hydraulic model investigation / by 1 homas E. Murphy, Jr., John E. Hite, Jr.prepared for U.S. Army Engineer District, Charleston.

72 p. : ill. ; 28 cm. - (Technical report ; HL-93-1)Includes bibliographical references.1. Fishways - ,South C.rol ;- Copcr Ri;'cr. 2. 1',d "!actrhc power plants

-South Carolina- Berkeley County - Environmental aspects. 3. Hydraulicmodels. 4. Diversion structures (Hydraulic engineering) I. Hite, John E. I1.United States. Army. Corps of Engineers. Charleston District. IIl. U.S. Army Engi-neer Waterways Experiment Station. IV. Title. V. Series: Technical report (U.S.Army Engineer Waterways Experiment Station) ; HL-93-1.TA7 W34 no.HL-93-1

PREFACE

The model investigation reported herein was authorized by Headquarters,

US Army (,orps of Engineers, on 26 March 1991 at the request of the US Army

Engineer District, Charleston (SAC). The studies were conducted at the US

Army Engineer Waterways Experiment Station (WES) during the period September

1991 to March 1992. All studies were conducted under the direction of

Messrs. Frank A. Herrmann, Jr., Director of the Hydraulics Laboratory, WES;

Richard A. Sager, Assistant Director of the Hydraulics Laboratory; and

Glenn A. Pickering, Chief of the Hydraulic Structures Division, Hydraulics

Laboratory. Tests were conducted by Mr. Thomas E. Murphy, Jr., Dr. John E.

Hite, Jr., Mr. Robert A. Davidson, and Ms. Olie Blansett, all of the Locks and

Conduits Branch, Hydraulic Structures Division, under the supervision of

Mr. J. F. George, Chief of the Locks and Conduits Branch. This report was

prepared by Mr. Murphy and Dr. Hite and edited by Mrs. Marsha C. Gay,

Information Technology Laboratory, WES.

During the course of the investigation, Messrs. James Joslin, Charles

Harbin, Millard Dowd, Richard Jackson, Francis Limbaker, and William McCollum

of SAC; Messrs. Douglas Cooke and Samuel Chappelear of the South Carolina

Wildlife and Marine Resources Department; and Mr. Ben Rizzo of the US Fish and

Wildlife Service visited WES to observe model operation and correlate results

with design studies.

At the time of publication of this report, Director of WES was

Dr. Robert W. Whalin. Commander was COL Leonard G. Hassell, EN.

I

CONTENTS

Page

PR EFA CE ................................................................ i

CONVERSION FACTORS, NON-SI TO SI (METRIC)UNITS OF MEASUREMENT ..................................................... 3

PART I: INTRODUCTION .................................................... 5

Background ........................................................Purpose and Scope of the Model Study ................................ 5

PART II: THE MODEL .................. ................................ 7

Description .......................................................... 7Model Appurtenances .................................................. 7Scale Relations ...................................................... 7

PART III: TESTS AND RESULTS ............................................... 12

Original Design ...................................................... 12Modifications to the Fish Lift Entrances ............................ 15

PART IV: CONCLUSIONS AND RECOMMENDATIONS ................................ 20

PHOTOS 1-15

PLATES 1-39

2

CONVERSION FACTORS, NON-SI TO Si (METRIC)

UNITS OF MEASUREMENT

Non-SI units of measurement used in this report can be converted to S1

(metric) units as follows:

Multiply By To Obtain

cubic feet 0.45359244 kilograms

feet 0.3048 metres

miles (US statute) 1.609344 kilometres

E N N NOR T H CAAR0OL1N A

SUMTER

Ar4AN r

COOPER RIVER REDIVERSION CANAL PROJECT

IER Igur 1.SO Vicnit anSlc Tion Hma

CANA DAMPOWEHOU4

ST. STEPHEN POWERHOUSE FISH LIFT

COOPER RIVER REDIVERSION PROJECT, SOUTH CAROLINA

Hydraulic Model Investigation

PART I: INTRODUCTION

Background

1. The St. Stephen Power Plant is located in Berkeley County, South

Carolina, approximately 1.9 miles* north of the town of St. Stephen (Fig-

ure 1). It is located in the rediversion canal connecting Lake Moultrie and

the Santee River. The powerhouse consists of three main units, each rated

28 Mw. The overall length of the powerhouse is 276 ft and the transverse

width is approximately 150 ft at the base.

2. The fish lift facilities, located on the north side of the power-

house, were intended to provide a means of transferring various species of

game and other desirable fish from the power plant tailrace canal to the

intake canal and Lake Moultrie. After several years of fish lift operation at

St. Stephen Powerhouse, it was determined that the present facilities were

inadequate for transferring the numbers and species of anadromous fish using

the St. Stephen tailrace as a migration route to Lake Mouitrie. The present

fish lift does not provide attraction flow in the tailrace area, where the

desired numbers of fish are likely to be drawn into the fish lift.

Purpose and Scope of the Model Study

3. The purpose of the study was to investigate various alternatives to

improve the fish attraction capabilities of the existing fish lift system.

Specific model tests were conducted to

a. Determine if increasing the attraction flow through the presentfish lift would provide the type flows necessary for properfish attraction.

b. Investigate means of relocating the fish lift entrances to

Non-SI units of measurement used in this report can be converted to SI

(metric) units as shown on page 3.

5

areas that would be more likely to attract migrating fish intothe fish lift system.

c. Determine if structural additions in the tailrace wouldadversely affect present hydraulic conditions in the tailracearea.

6

PART II: THE MODEL

Description

4. The model was constructed to an undistorted scale of 1:25 and repro-

duced about 1,700 ft of the tailrace topography, the downstream face of the

powerhouse, intake piers, spiral cases, draft tubes, and the existing fish

lift entrances. The tailrace walls, tailrace slab, downstream face of the

powerhouse, and portions of the fish lift were constructed of plastic-coated

ply-wood. The spiral cases, draft tubes, and fish lift entrance piers were

constructed of smooth Plexiglas. The downstream topography was constructed of

sand and cement mortar molded to sheet metal templates. Plate 1 is a layout

of the model. Figure 2 shows the mod-l. Figure 3 is a side view of an

intake, spiral case, and draft tube for a powerhouse unit.

Model F 2purtenances

5. Water used in operation of the model was supplied by a circulating

system. Discharges in the model were measured with venturi meters and propel-

ler type flowmeters installed in the inflow lines. Water-surface elevations

were measured with point gages. Average velocities were measured with a Nixon

streamflow series 400 propeller type flowmeter, mounted to permit measurement

of flow from any horizontal direction and at any depth. The tailwater eleva-

tion was maintained with an adjustable tailgate. Various flow conditions were

recorded photographically.

Scale Relations

6. The accepted equations of hydraulic similitude, based on the

Froudian criteria, were used to express mathematical relations between the

dimensions and hydraulic quantities of the model and prototype. General rela-

tions for the transference of model data to prototype equivalents are

presented in the following tabulation:

7

Scale RelationshipCharacteristic Dimension* Model:Prototype

Length Lr 1:25

Area A - L2 1:625r r

Velocity V - L1 1 2 1:5r r

Discharge Q - L5 / 2 1:3,125r r

Volume V - L3 1:15,625r r

Weight W - L3 1:15,625r r

Time T - LI/ 2 1:5r r

* Dimensions are in terms of length.

8

a. Looking upstream

El 4"

EL ... '0 .

b. Looking downstream

Figure 2. 1:25-scale model of St. StephenPowerhouse tailrace (Continued)

c. Looking upstream toward powerhouse and fish lift entrances

LI•r ENTANCE

•PTREAM FI•k

VF'TENTRME

d. Side view looking toward north wing wall and fish lift entrances

Figure 2. (Concluded)

10

,-4

I-4

44a

.0

I,)

ho

PART III: TESTS AND RESULTS

Original Design

Fish attraction flow of 240 cfs

7. Initial tests were conducted with the original design to determine

flow patterns in the tailrace with various combinations of powerhouse units

operating and a total fish attraction flow of 240 cfs through both fish

entrances. Photo I shows surface flow patterns in the tailrace with units 1,

2, and 3 operating with a total discharge of 24,500 cfs (8,166 cfs/unit), and

a tailwater elevation of 23.1.* The fish attraction flow of 240 cfs was con-

sidered a normal operating condition for these tests. For the initial tests,

a weir was not used in the fish entrances. The entrance was open from the

fish slab elevation of 4.0 to the water surface. A circulating, low-velocity

flow was present on the surface near the fish entrances. Surface flow

increased along the left (looking downstream) training wall as the training

wall intercepted the expanding flow from the boil at unit 3 and directed it

downstream. Slack-water areas formed behind and immediately downstream of

both training walls.

8. Velocity measurements recorded near the surface in the vicinity of

the fish lift entrances and along the fish slab are shown in Plates 2 and 3.

Return flow from the draft tube discharge caused upstream velocities in the

vicinity of both fish entrances and dominated flow patterns in this area. It

should be noted that all velocity measurements in this investigation are

average velocities. Velocities 50 and 125 ft downstream from the fish

entrances were in a downstream direction and higher than velocities at the

fish entrances. Flow conditions in these areas were the result of the draft

tube discharge at unit 3.

9. Tests were conducted with units I and 2 operating equally with a

total discharge of 16,400 cfs, a tailwater elevation of 20.8, and fish attrac-

tion discharge of 240 cfs. These flow conditions are shown in Photo 2. With

these conditions, flow exited the draft tubes and continued down the right

half of the channel. Some of the flow from the draft tube boil at unit 2

* All elevations (el) cited herein are in feet referred to the National

Geodetic Vertical Datum (NGVD).

12

spread toward the left training wall (north wing wall) forming an eddy at the

fish lift entrances and in the tailrace area downstream from unit 3. Smaller

eddies were observed downstream in the shear zone formed from the draft tube

discharge and upstream flow along the north (left) training wall. Approxi-

mately 1,000 ft downstream from the powerhouse, a slow upstream eddy was

present along the left bank toward the powerhouse.

10. Velocity measurements obtained near the surface with the flow con-

ditions shown in Photo 2 are shown in Plates 4 and 5. Velocities measured at

the fish entrances were generally in a downstream direction, but were low.

The velocities measured over the fish slab at distances of 50 and 125 ft down-

stream from the fish lift were all in an upstream direction and were less than

2.2 ft/sec.

11. Tests were then conducted with only unit I operating at a discharge

of 8,200 cfs, a tailwater elevation of 16.6, and a fish attraction discharge

of 240 cfs. With these conditions, flow exited the draft tubes and continued

down the right side of the channel for approximately 1,000 ft, at which point

an upstream eddy returned some of the flow along the left bank toward the

powerhouse and along the left training wall all the way to the fish entrances.

Photo 3 shows surface flow patterns for these conditions.

12. Velocities measured near the downstream fish entrance were gen-

erally in a downstream direction and higher than those observed with two and

three units operating, as shown in Plates 6 and 7. However, the upstream flow

from the large eddy caused the flow exiting the downstream fish entrance to

circulate in a tight eddy between the fish lift entrance and the left training

wall, and no velocities in a downstream direction were measured at distances

of 50 and 125 ft downstream from the fish entrances. Velocities measured near

the center of the upstream fish entrance were in a downstream direction.

Fish attraction flow of 500 cfs

13. To evaluate the effects of increased fish attraction flows, tests

were conducted with all three units operating with the appropriate tailwater

elevation and with 500 cfs discharging from the downstream fish entrance only.

A 500-cfs discharge through the present system would need to be supplied from

additional water sources other than the fish lift to prevent excessive turbu-

lence, which would be harmful to fish in the system. The upstream fish

entrance was closed for these tests. Surface flow patterns with all three

units operating are shown in Photo 4. Because of the configuration of the

13

fish lift, the flow discharging from unit 3 separated at the downstream end of

the fish lift, resulting in the formation of an eddy near the downstream fish

entrance. The flow pattern resulting from unit 3 operating also forced the

flow from the fish entrance against the left training wall.

14. Velocities measured with all three units operating and a fish

attraction discharge of 500 cfs for the downstream entrance only are shown in

Plates 8 and 9. The velocities measured near the center of the downstream

fish entrance were greater than 3.8 ft/sec, which was considerably higher than

those measured with a discharge of 240 cfs. Velocities 50 and 125 ft down-

stream from the fish lift entrance were comparable to those measured with a

discharge of 240 cfs from the fish lift, indicating that the draft tube dis-

charges dominate the flow patterns in these areas even with 500 cfs discharg-

ing from the fish lift entrance.

15. Surface flow patterns with units I and 2 operating and a fish

attraction discharge of 500 cfs (Photo 5) indicate eddy patterns similar to

those observed with a fish attraction discharge of 240 cfs (Photo 2). Veloci-

ties measured with units I and 2 operating and a discharge of 500 cfs are

shown in Plates 10 and 11. Velocities greater than 4.5 ft/sec were measured

near the center of the downstream fish entrance, but no velocities in the

downstream direction were measured over the fish slab at distances of 50 and

125 ft downstream from the fish lift entrance. The surface flow patterns and

velocity measurements indicate that an attraction flow of 500 cfs does not

result in downstream flow along the left training wall with units I and 2

operating.

16. Surface flow patterns with unit I operating with a fish attraction

discharge of 500 cfs are shown in Photo 6. Large eddies formed in the tail-

race area downstream from units 2 and 3, and flow was observed in the down-

stream direction along the left training wall. Velocities measured along the

fish slab are shown in Plates 12 and 13. Velocities measured near the center

of the downstream fish entrance were as high as 8.4 ft/sec, and velocities

were in the downstream direction 50 and 125 ft downstream from the fish

entrance near the training wall. This type of flow pattern along the left

training wall should be favorable for fish attraction; however, the velocities

at the entrance may be too high for the fish to enter the lift.

17. Photos 7 and 8 show a close-up of flow conditions near the fish

lift entrance with unit 1 operating at 8,200 cfs, a tailwater elevation of

14

16.6, and a fish attraction flow of 500 cfs. In Photo 7, only the downstream

fish entrance is open, whereas in Photo 8 both entrances are open. Photo 7

shows the eddy downstream of the fish entrance to be less concentrated and

further away from the training wall.

Modifications to the Fish Lift Entrances

18. The maximum flow that can presently be discharged through the

original design fish lift entrances without excessive turbulence during the

chamber filling operation is less than 240 cfs. The flow patterns and

velocity measurements obtained during the initial tests indicated that a much

greater discharge was needed to alter the circulation pattern in the tailrace

and produce downstream flows along the left training wall with either unit I

or units 1 and 2 operating. A discharge of 500 cfs from the fish lift pro-

duced flow in the downstream direction with only unit 1 operating. Testing

efforts were therefore directed toward developing modifications that moved the

entrances to the fish lift downstream to an area closer to the end of the left

training wall. These wall extensions did not cause a measurable rise in the

tailrace water-surface elevation or significantly increase velocities in the

tailrace area.

19. All tests of modifications to the fish lift entrances were con-

ducted with all three units operating equally at a powerhouse discharge of

21,300 cfs (7,100 cfs/unit) and a tailwater elevation of 26.0. Flow condi-

tions similar to these are normally experienced at St. Stephen Powerhouse

during the period of greatest fish migration. Therefore, the US Army Engineer

District, Charleston, and the US Army Engineer Waterways Experiment Station

(WES) agreed to use a discharge of 7,100 cfs/unit for the remainder of the

testing program. Total fish attraction flow was 500 cfs, and flow through the

fish entrances was controlled by a weir set at an elevation to produce an

average velocity of 5 ft/sec exiting the entrance. It was decided in a meet-

ing with personnel from the Charleston District, South Carolina Wildlife and

Marine Resources Department (SCWMRD), and US Fish and Wildlife Service (USFWS)

that an average velocity of 5 ft/sec exiting the fish entrance would be

required for attraction flow. For these tests, as in previous tests, with the

original design, the 500-cfs flow was supplied by a single pipe located far

enough upstream from the fish entrances to allow for smooth flow in the

15

modified fish channel and entrance, Flow patterns were determined only at the

new entrances and the areas downstream from these entrances.

TyRe I fish entrance modification

20. The type I entrance modification moved the downstream fish entrance

approximately 130 ft downstream from its original location, as shown in

Plate 14. This modification provided an 8-ft-wide entrance with attraction

flow discharging along the north wing wall in a downstream direction. The top

of the entrance weir was at el 13.5. Velocity measurements with the type I

entrance modification are shown in Plates 15 and 16. These velocities indi-

cated that flow in a downstream direction existed along the training wall

throughout the depth of flow and increased in magnitude near the surface. The

initial concept to attract fish was to provide an avenue of flow with a veloc-

ity higher than that of the tailrace flow from the powerhouse discharge. The

type I entrance modification did not provide these higher velocities.

TVDes 2. 3. and 4 fish entrance modifications

21. Types 2, 3, and 4 entrance modification concepts, shown in

Plates 17-19, were developed in a meeting between the Charleston District and

WES personnel. Since the type 2 and 3 modifications were similar to the

type I entrance modification, they were not tested because of the performance

of the type 1 entrance modification. Since the type 4 entrance modification

would require considerable excavation, it was decided to test methods that did

not require additional excavation.

jyRe 5 fish entrance modification

22. The type 5 entrance modification consisted of an 8-ft-wide fish

entrance located approximately 215 ft downstream from the original entrances,

as shown in Plate 20. The top of the entrance weir was at el 13.5. This

modification provided downstream attraction flow in the vicinity of the eddy

area near the end of the north wing wall. Velocity measurements, shown in

Plates 21 and 22, indicated that surface velocities downstream from the fish

entrance were higher than the velocity of the tailrace flow.

TyRe 6 fish entrance modification

23. The type 6 entrance modification (Plate 23) was tested to determine

the effect of directing attraction flow more toward the center of the tailrace

channel, but otherwise was identical to the type 5 entrance modification.

Velocity magnitudes (Plates 24 and 25) were similar to those measured with the

type 5 entrance modification in place, but flow patterns differed slightly'

16

because of the angle of the flow directed from the fish entrance. The

entrance weir elevation was at 13.5. Velocities along the left bank were

lower with the type 6 entrance modification.

Type 7 fish entrance modification

24. The type 7 entrance modification, shown in Plate 26, consisted of

two fish entrances. The upstream entrance was 6 ft wide and located at the

downstream end of the present north wing wall. The top of the entrance weir

was at el 19.3. Approximately 40 percent of the fish attraction flow

(200 cfs) discharged from this entrance. Attraction flow was released toward

the left bank of the tailrace channel. The downstream fish entrance was 8 ft

wide and located 25 ft from the end of the north wing wall. The top of the

entrance weir was at el 18.5. Approximately 60 percent (300 cfs) of fish

attraction flow discharged from this entrance. This modification provided

attraction flow directly to the eddy area behind the north wing wall through

the 6-ft-wide entrance. Velocities with the type 7 entrance modification are

shown in Plates 27 and 28. The surface velocities on the left bank could be

excessive for the existing bank protection.

Tv~es 8. 9. and 10 fish entrance modifications

25. Further testing consisted of installing various types of wall

extensions to cut off eddy areas behind and downstream of both tailrace wing

walls. These walls were used as additions to the types 8, 9, and 10 entrance

modifications. These modifications were designed to provide downstream flow

along a wall to at least one fish entrance. It was decided in the previously

mentioned meeting with the Charleston District, SCWMRD, and USFWS that down-

stream flow along a wall leading to a fish entrance was an important design

feature even when velocities along the wall were lower than the velocity of

the tailrace flow from the powerhouse units.

26. The type 8 entrance modification (Plate 29) was a refined version

of the type 1 entrance modification. The downstream fish entrance was

extended approximately 88 ft downstream to a point just beyond the area in the

tailrace where the flow from the boil caused by the unit 3 discharge travels

in a downstream direction along the north training wall. This modification

provided flow along the training wall and could also be beneficial to fish

traveling up the right side of the channel and across the tailrace. The top

of the entrance weir was at el 13.5. Velocities measured with the type 8

entrance modification are shown in Plates 30 and 31. Photo 9 shows the

17

surface flow conditions with the type 8 entrance modification in place. Flow

patterns and velocities measured at various depths inside the north wing wall

were in a downstream direction.

27. There was concern that fish might remain in the low-velocity circu-

lating flow behind the north wing wall. A wall was installed from the end of

the north wing wall to the left bank, shown in Plate 32. Surface velocities

with the type 8 entrance modification in place and the wall blocking off the

eddy area behind the north wing wall are also shown in Plate 32. This type

wall caused only slight changes in the flow patterns, and velocity magnitudes

were the same as without the wall. The eddy area was still present downstream

from the wing wall.

28. The north wing wall was extended 300 ft downstream to the left berm

with the top of the wall extension at el 26. Photo 10 shows surface flow

patterns with the type 8 entrance modification and the wall extension in

place. This extension to the north wing wall prevented the eddies from

developing behind and downstream of the original wing wall, as can be seen by

comparing Photos 9 and 10. Flow along the wall extension was in a downstream

direction.

29. The type 9 entrance modification (Plate 33) provided two fish

entrances. The upstream entrance was 8 ft wide and located approximately

88 ft downstream from the present fish entrances. Approximately 380 cfs or

76 percent of the fish attraction flow passed through this entrance. The top

of the entrance weir was at el 16. The downstream entrance was 6 ft wide and

located approximately 130 ft downstream of the present entrances at the bend

of the north wing wall. Attraction flow through this entrance was approxi-

mately 120 cfs or 24 percent of the total attraction flow, and the top of the

fish entrance weir was set at el 21. Plates 34 and 35 show velocity measure-

ments with the type 9 entrance modification, and Photo 11 shows surface flow

conditions with this modification in place. This modification provided down-

stream flow along training walls leading to both fish entrances.

30. To investigate the effect of preventing the low-velocity eddy from

developing behind both the north wing wall and the south training wall, the

wall modifications shown in Plate 36 were tested. The north wing wall exten-

sion was the same as tested with the type 8 entrance modification. The south

training wall was extended 337.5 ft downstream and a wing wall 195 ft long was

angled to the top of the right bank berm at el 26. The extension to the south

18

training wall eliminated a large eddy and slack-water area that formed behind

the original training wall and down the right bank of the tailrace canal. The

extension to the north wing wall eliminated the eddy along the left bank

previously observed with the type 8 entrance modification in place. Flow

conditions with the type 9 entrance modification and the wall modifications to

both the north wing wall and south training wall are shown in Photo 12. The

tailwater elevation was lowered to 24.25 to prevent overtopping of the south

wing wall. No eddies were observed with this flow condition.

31. The extension on the south wing wall was removed to observe flow

conditions in the tailrace area with the type 9 entrance modification and the

north wing wall extension in place. As seen in Photo 13, the wing wall exten-

sion eliminated the eddy from forming along the left bank. However, eddies

did develop behind the south training wall and along the right bank.

32. In the type 10 entrance modification (Plate 37), the 6-ft-wide fish

entrarce in the type 9 entrance modification was moved to the end of the north

wing wall in an attempt to provide attraction flows in the vicinity of the

downstream end of the wing wall. This entrance was approximately 215 ft down-

stream from the present fish entrances. The weir elevation was the same as

with the type 9 entrance modification and the flow distribution through the

entrances was approximately the same. The type 10 entrance modification com-

bined the features from the type 8 and type 5 entrance modifications. The 6-

ft-wide downstream entrance supplied fish attraction flow in the vicinity of

the'eddy area behind and downstream from the north wing wall. The 8-ft-wide

upstream entrance may be helpful in intercepting migrating fish that move

upstream along the south side of the channel and cross over to the north side

of the tailrace canal. Velocity measurements with type 10 entrance modifica-

tion in place are shown in Plates 38 and 39.

33, Photo 14 shows flow conditions for the type 10 entrance modifica-

tion with and without wing wall additions. The north wing wall additions did

prevent the eddy from forming behind the wing wall; however, an eddy still

formed downstream along the left bank. Photo 15 shows surface flow conditions

with the type 10 entrance modification in place and the 300-ft extension to

the north wing wall. As in previous tests with the type 9 entrance modifica-

tion (Photo 13), flow was trained in a downstream direction along the wall,

eliminating eddies along this portion of the left bank of the tailrace canal.

19

PART IV: CONCLUSIONS AND RECOMMENDATIONS

34. The flow patterns and velocity measurements recorded during initial

tests indicated a discharge of at least 500 cfs through the original design

fish entrances was needed to produce desired flow conditions for fish attrac-

tion. A 500-cfs discharge through the present fish lift system would create

excessive turbulence during the chawber filling operation resulting in harm to

the fish within the system.

35. Tests were conducted with wall extensions along the fish slab to

move fish lift entrances to areas where flow would discharge through the

entrances and continue in a downstream direction. These tests were conducted

with the three turbine units operating at equal discharges. The recommended

discharges through the fish entrances for these modifications was 500 cfs.

Flow at the fish entrances was controlled by a weir set at an elevation to

produce an average velocity of 5 ft/sec. These modifications to the fish lift

entrances varied the locations of the entrances (a distance of 88 ft to

240 ft) downstream of the original design entrances. Some modifications pro-

vided one entrance (types 1, 3, 5, 6, and 8), while others were designed with

two entrances (types 2, 4, 7, 9, and 10).

36. Wall extensions to the existing wing walls were placed in the model

to eliminate dead areas and eddies along the left and right banks downstream

of and behind existing walls. These walls trained the flow from the power-

house and fish entrances in a downstream direction. A wall from the end of

the north wing wall to a point approximately perpendicular to the left bank

was tested to eliminate the eddy area behind the north wing wall. This type

wall extension only relocated the eddy to an area just downstream of the new

wall.

37. The wall additions to the fish slab did not adversely affect

hydraulic conditions in the tailrace area. There was no significantly mea-

surable increase in water-surface elevations downstream of the draft tube out-

lets. Velocity magnitudes and distribution were also approximately the same

over the tailrace slab and downstream riprap protection.

38. The recommended design for improving fish attraction capabilities

is the type 9 entrance modification. This modification provided for two fish

entrances. The upstream entrance was located approximately 88 ft downstream

of the present fish entrances. This placed the upstream entrance as close to

20

the powerhouse as possible, yet at a point far enough downstream where the

boil from unit 3 discharge would not adversely affect flow conditions at the

entrance. This entrance could also be beneficial in intercepting fish that

move across from the south side of the tailrace. The downstream entrance of

the type 9 entrance modification was located approximately 130 ft downstream

of the present entrances at the bend of the north wing wall. This provided an

entrance in an area of lower velocity than the upstream entrance and would

benefit species of fish that prefer slower, less turbulent flow. Downstream

flow along walls leading to both entrances was provided in the type 9 entranie

modification.

21

Photo 1. Surface flow patterns, original design, discharge24,500 cfs, tailwater el 23.1, fish attraction flow 240 cfs,

units 1, 2, and 3 operating

Photo 2. Sorfrc2e flow patterns, original design, discharge16,400 cfs, tailwater el 20.8, fish attraction flow 240 cfs,

units I Pnd 2 operating

Photo 3. Surface flow patterns, original design, discharge8,200 cfs, tailwater el 16.6, fish attraction flow 240 cfs,

unit 1 operating

Photo 4. Surface flow patterns, original design, discharge24,500 cfs, tailwater el 23.1, fish attraction flow 500 cfs(downstream fish entrance only), units 1, 2, and 3 operating

Photo 5. Surface flow patterns, original design, discharge16,400 cfs, tailwater el 20.8, fish attraction flow 500 cfs

(downstream fish entrance only), units I and 2 operating

Photo 6. Surface flow patterns, original design, discharge8,200 cfs, tailwater el 16.6, fish attraction flow 500 cfs

(downstream fish entrance only), unit I operating

Photo 7. Close-up view of surfaceflow patterns, original design,discharge 8,200 cfs, tailwaterel 16.6, fish attraction flow

. . 500 cfs (downstream fish entranceonly), unit 1 operating

Photo 8. Close-up view of surfaceflow patterns, original design,discharge 8,200 cfs, tailwaterel 16.6, fish attraction flow500 cfs (both fish entrances

open), unit 1 operating

Photo 9. Surface flow patterns, type 8 entrance modification,discharge 7,100 cfs per unit, tailwater el 26.0, fish attrac-

tion flow 500 cfs, units 1, 2, and 3 operating

Photo 10. Surface flow patterns, type 8 entrance modification, northwing wall extended 300 ft, discharge 7,100 cfs per unit, tailwater

el 26.0, fish attraction flow 500 cfs, units 1, 2, and 3 operating

Photo 11. Surface flow patterns, type 9 entrance modification,discharge 7,100 cfs per unit, tailwater el 26.0, fish attrac-

tion flow 500 cfs, units 1, 2, and 3 operatingM 'MAN

Photo 12. Surface flow patterns, type 9 entrance modification, northand south wing walls extended, discharge 7,100 cfs per unit, tailwater

el 24.25, fish attraction flow 500 cfs, units 1, 2, and 3 operating

Photo 13. Surface flow patterns, type 9 entrance modification, northwing wall extended 300 ft, discharge 7,100 cfs per unit, tailwater

el 26.0, fish attraction flow 500 cfs, units 1, 2, and 3 operating

a. With wing wall addition

b. Without wing wall addition

Photo 14. Surface flow patterns, type 10 entrance modification, withand without north wing wall extension, discharge 7,100 cfs per unit,tailwater el 26.0, fish attraction flow 500 cfs, units 1, 2, and

3 operating

Photo 15. Surface flow patterns, type 10 entrance modification, northwing wall extended 300 ft, discharge 7,100 cfs per unit, tailwater

el 26.0, fish attraction flow 500 cfs, units 1, 2, and 3 operating

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Form ApprovedREPORT DOCUMENTATION PAGE oMB No 0704-0188Publc reporting burden for this collection of information is estimated to average 1 hour oer reipOnse. including the time for (evievirng instrucltons ,earchnq ersting data tourýet.

gatheing and ma�lntamlnin the data needed, and completing and reviewing the collection of Information Send comments regarding this burden estimate or any other asoect of thiscollection of informatin, including tuggestion; for reduing this Ourden to WasheNgton Head•uartert Ser•uies. O,recorate for information Ooeration, and Reodls. r2 S letetonDavis Highway. Suite 1204. Arlington, VA 22202-4302, and to the Office of Management and Budget. Paperwori Reduction Project (0704.0 89). Washington, DC 20503

1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE 3. REPORT TYPE AND DATES COVEREDMarch 1993 Final Report

4. TITLE AND SUBTITLE S. FUNDING NUMBERS

St. Stephen Powerhouse Fish Lift, Cooper River RediversionProject, South Carolina; Hydraulic Model Investigation6. AUTHOR(S)

Thomas E. Murphy, Jr.John E. Hite, Jr.

7. PERFORMING ORGANIZATION NAME(S) AND ADORESS(ES) 8. PERFORMING ORGANIZATIONREPORT NUMBER

USAE Waterways Experiment Station, Hydraulics Technical ReportLaboratory, 3909 Halls Ferry Road, Vicksburg, MS HL-93-139180-6199

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING/MONITORINGAGENCY REPORT NUMBER

USAE Districi, Char!eston, PO Box 919,Charleston, SC 29402-0919

11. SUPPLEMENTARY NOTES

Available from National Technical Information Service, 5285 Port Royal Road, Springfield, VA 22161.

12a. DISTRIBUTION/ AVAILABILITY STATEMENT 12b. DISTRIBUTION CODE

Approved for public release; distribution is unlimited.

13. ABSTRACT (Maximum 200 words)The St. Stephen Power Plant is located in Berkeley County, South Carolina, approximately 1.9 miles north

of the town of St. Stephen. It is located in the rediversion canal connecting Lake Moultrie and the Santee River.Included in the project is a reinforced concrete fish lift structure located on the north side of the powerhouse. Thepresent fish lift structure does not provide sufficient attraction flow in the tailrace area, where the desired numbersof fish are likely to be drawn into the fish lift system.

Tests were conducted on a 1:25-scale model of the powerhouse, fish lift entrances, and downstream tail-race canal. The purpose of the study was to investigate various alternatives to improve the fish attraction capabili-ties of the existing fish lift system. Walls were extended downstream from the original design fish lift to providenew entrance locations in areas more suitably located for fish attraction. The type 9 entrance modification is therecommended design. This modification provided for two fish entrances. The upstream entrance was locatedapproximately 88 ft downstream of the present fish entrances, and the downstream entrance was located approxi-mately 130 ft downstream of the present fish entrances at the bend of the north wing wall. Both entrances pro-vided downstream flow along a wall leading to the entrance.

14. SUBJECT TERMS 15. NUMBER OF PAGESDraft tubes Powerhouse 72Fish lift Tailrace canal 16. PRICE CODEHydraulic models17. SECURITY CLASSIFICATION 18. SECURITY CLASSIFICATION 19. SECURITY CLASSIFICATION 20. LIMITATION OF ABSTRACT

OF REPORT OF THIS PAGE OF ABSTRACT

UNCLASSIFIED UNCLASSIFIED I IINSN 7540-01-280-5500 Standard Form 298 (Rev 2 89)

P90 102dt AYýd 91