Tennessee
Valley
Authority
United States
Environmental Protection
Agencv
Office of Power
Power Research Staff
Chattanooga, Tennessee 37401
Office of Research and Development
Office of Energy, Minerals, and Industry
IERL, Research Triangle Park, NC 27711
PRS-16
EPA-600/7-76-020
October 1976
A STATE-OF-THE-ART
REPORT ON
INTAKE TECHNOLOGIES
Interagency
Energy-Environment
Research and Development
Program Report
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S.
Environmental Protection Agency, have been grouped into seven series.
These seven broad categories were established to facilitate further
development and application of environmental technology. Elimination
of traditional grouping was consciously planned to foster technology
transfer and a maximum interface in related fields. The seven series
are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from
the effort funded under the 17-agency Federal Energy/Environment
Research and Development Program. These studies relate to EPA's
mission to protect the public health and welfare from adverse effects
of pollutants associated with energy systems. The goal of the Program
is to assure the rapid development of domestic energy supplies in an
environmentally—compatible manner by providing the necessary
environmental data and control technology. Investigations include
analyses of the transport of energy-related pollutants and their health
and ecological effects; assessments of, and development of, control
technologies for energy systems; and integrated assessments of a wide
range of energy-related environmental issues.
This document is available to the public through the National Technical
Information Service, Springfield, Virginia 22161.
-------
PRS-16
EPA-600/7-76-020
October 1976
A STATE-OF-THE-ART
REPORT ON
INTAKE TECHNOLOGIES
by
S. S. Ray and R. L. Snipes (TVA/Chattanooga)
and D. A. Tomljanovich (TVA/Norris)
Tennessee Valley Authority
Power Research Staff
Chattanooga, Tennessee 37*4-01
and
Division of Forestry, Fisheries, and Wildlife Development
Norris, Tennessee 37828
EPA Interagency Agreement No. D5-E-721
Program Element No. EHB531
EPA Project Officer: James P. Chasse (EPA/Corvallis)
TVA Project Officer: H. B. Flora (TVA/Chattanooga)
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
This study was conducted
as part of the Federal
Interagency Energy/Environment
Research and Development Program.
Prepared for
OFFICE OF ENERGY, MINERALS, AND INDUSTRY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20^60
-------
DISCLAIMER
This report has been prepared by the Tennessee Valley Authority and
reviewed by the U. S. Environmental Protection Agency and approved
for publication. Approval does not signify that the contents
necessarily reflect the views and policies of either agency, nor
does mention of trade names or commercial products constitute en-
dorsement or recommendation for use.
ii
-------
ABSTRACT
The purpose of this report is to present an updated evaluation of
mechanisms and intake designs for reducing the numbers of fish en-
trained and impinged at water intake facilities. These mechanisms
consist of intake configurations, behavioral barriers to guide fish
past intake entrances, screening devices to remove or divert fish
from cooling water intakes, and fish removal systems to evacuate
fish already within the intake area.
This report summarizes evaluations of available intake technologies
and, more importantly, presents results of recent tests and studies.
Where promising mechanisms are identified, recommendations are made
with regard to tests needed to demonstrate the applicability of a
mechanism for protecting fish in site-specific situations.
This report also addresses the problem of reducing fish losses at
both large-volume, once-through cooling water intakes and lower-
volume intakes at plants requiring only makeup water to replace
losses due to cooling tower blowdown and evaporation. For the
evaluations of devices for reducing impingement and entrainment,
due consideration was given to devices and designs that are capable
of protecting very small fish and eggs.
This report was submitted by the Tennessee Valley Authority Power
Research Staff in partial fulfillment of Energy Accomplishment
Plan No. 77BBE under terms of Interagency Energy Agreement No.
D5-E-721 with the Environmental Protection Agency.
iii
-------
CONTENTS
Abstract ill
Figures vi
Tables viii
Section
1. Introduction 1
2. Conclusions 3
3- Recommendations 5
l<-. Plant Siting and Intake Design 6
General 6
Intake Configuration and Design 6
5. Behavioral Barriers 9
General 9
Electrical Barrier 9
•Sound Barrier 12
Light Barrier 13
Air Bubble Barrier 15
Water Jet Velocity 21
Cable and Chain Screens 21
Louvers 22
6. Physical Barriers 29
General 29
Modification of Existing Vertical Traveling Screen Design . 31
Inclined Traveling Screens 33
Fixed Screens 35
Revolving Drum. Screens 36
Rotating Disc Screens kO
Double-Entry, Single-Exit Vertical Traveling Screens . . . Uo
IV
-------
Single-Entry, Double-Exit (Center Flow) Traveling Screens k3
Perforated Plate Fish Barrier k7
Perforated Pipe Screens U8
Radial Well Intakes 50
Circular Well Screens 50
Horizontal Traveling Screen 5^
Infiltration Barrier 6l
7. Fish Removal Systems 68
Fish Pump 68
Vertical Traveling Fish Basket Collector 71
8. Summary and Discussion 72
References 76
-------
FIGURES
Number Page
1 Typical features of an electric screen used in U.S. . . . 10
2 Air "bubble screen (Elevation View) 16
3 An offshore air bubble intake structure 17
U Indian Point air bubble system 19
5 Louver diversion system-schematic 23
6 Delta fish diversion-louver system 2k
7 Louver system at Nine Mile Point Nuclear Power Station . 27
8 Traveling louvers at the San Onofre Nuclear Power Plant . 28
9 Conventional vertical traveling screen 30
10 Vertical traveling screen installation of WPPSS 32
11 Inclined traveling screen 3^-
12 Revolving drum screen with horizontal axis-schematic . . 37
13 Revolving drum screen with vertical axis-schematic ... 38
1^ Revolving disc screen-schematic kl.
15 Double-entry, single-exit vertical traveling screens-
schematic k2
16 Double-entry, single-exit independently supported screen UU
17 Single-entry, double-exit vertical traveling screen-
schematic lj-5
18 Single-entry, double-exit screen k6
19 Perforated pipe system k$
20 Radial well-schematic 51
21 Basic design of horizontal traveling screen 57
22 Pacific Gas and Electric's horizontal traveling screen
installation - schematic 60
VI
-------
23 Infiltration filter bed - schematic 65
2k Fish dust-pan collectors used with fish pumps 69
25 Screenwell showing fish collector system 70
vii
-------
TABLES
Number Page
1 Recommended Flow for Circular Well Screens 53
2 Inlet Areas for Circular Well Intake Screens 53
3 Diversion Efficiency and Survival of Spring Chinook in
Relation to Approach Velocity and Light Condition on
the Horizontal Traveling Screen 5G
h Diversion Efficiency and Survival of Spring Chinook Fry
in Relation to Approach Velocity and the Duration of
Impingement on Horizontal Traveling Screen Model VII 58
5 Relationship of Screen Mesh Size to Retention of Striped
Bass, Largemouth, and Smallmouth Bass Larvae .... 62
6 Immediate and Delayed Mortality of Striped Bass
Impinged on Test Screens 63
7 Immediate and Delayed Mortality of Largemouth Bass
Impinged on Test Screens 6^
viii
-------
SECTION 1
INTRODUCTION
The purpose of this report is to present an updated presentation of
mechanisms and intake designs that are currently available for re-
ducing the numbers of fish lost due to entrainment and impingement at
cooling water intake facilities. Several reports on available tech-
nologies pertaining to fish protection at cooling water intake
structures were prepared prior to or during 1973- These documents
contained descriptions and evaluations of types of intake locations
and configurations, behavioral barriers for guiding fish past intake
entrances, and mechanical devices to screen or otherwise divert fish
from cooling water intakes. This report briefly summarizes the des-
criptions of available intake technologies described in those documents
and presents the results of tests and studies not found in those re-
ports as well as an update of studies conducted subsequent to the 1973
reports. During the preparation of this report, an additional summary
document was distributed by the Energy Research and Development
Administration (ERDA) on fish protective devices.' The ERDA report,
a compilation of recent designs, concepts, and operating experience
of water intakes used in the United States , is also summarized herein.
The scope of this report is to address the problem of reducing fish
losses at both large-volume, once-through cooling water intakes and
lower-volume intakes at plants requiring only makeup water to replace
losses due to cooling tower blowdown and evaporation. Discussions
are included on plant siting, intake design, behavioral barriers to
guide fish past water intakes, physical barriers to prevent'fish from
entering intakes, and fish removal systems.
An important consideration in the evaluation of an intake screen system
or mitigative device is the smallest fish that these mechanisms and
devices are capable of protecting. Most conventional vertical travel-
ing screens in use throughout the country utilize 9«5 mm opening square
mesh screens. These screens have effectively divided the fish commun-
ity into two sizes: impingeable size (those that are retained by the
screen) and entrainable sizes (those that pass through the 9-5 mm
opening mesh screen). Depending upon the body shape of the species,
velocity through the screen, and position of the fish when it con-
tacts the screen, the impingeable and entrainable size may vary.
Impingement sampling at 13 Tennessee Valley Authority (TVA) electric
-------
power plants has indicated that fish less than 26 to 30 mm in total
length pass through the screens, and that those larger are impinged
against the screens." In the past, efforts have been focused on
devices to reduce impingement, while the entrainment problem has
been regarded as largely unsolvable except where plant siting can
minimize larval fish losses. However, increased attention is currently
being directed at the feasibility of protecting larval fish at water
intakes.
-------
SECTION 2
CONCLUSIONS
1. The protection of fish at water diversions has a long history in
the United States, but the enactment of recent legislation has
resulted in an intensified nationwide examination of entrainment
and impingement effects at power plant cooling water intakes.
2. Because of the requirement in Public Law 92-500, as amended in
1972, for "best technology available for minimizing adverse en-
vironmental impact"regarding the cooling water intake, comparisons
of impact based on type of intakes are desirable. However, the
many variables that affect the number of fish entrapped at an
intake, ranging from hydraulic and structural differences to fish
density and species differences in the source water body, render
these comparisons difficult.
3. Plant siting in least productive areas is important in terms of
mitigation of fish loss. However, in the case of existing plants,
siting for fish protection may not have been a consideration.
k. Many types of behavioral barriers have been tested for their capabil-
ity of guiding fish away from water intakes. To date, most have
limited applicability to power plant intakes although several
successful applications of electrical, air, and louver barriers
have been reported.
5. Several fish pumping or collecting devices have been proposed or
installed to remove fish trapped in intake wells. To date, test
results of recent prototypes have not been reported.
6. One modification to an existing vertical traveling screen has
shown high savings of impingeable-size fish. Water-carrying
troughs attached to each screen panel lift live fish from the
screen well as the screen rotates continuously.
7. Most power plant intake screens are incapable of providing pro-
tection for larval fish. An exception may be a single-entry,
double-exit (center flow) continuous traveling screen with semi-
circular shaped screen panels. The screens consist of 0.5 mm
opening polyester screen. This screen has the potential for pre-
-------
venting larval fish entrainment and diverting live fish back to
the source of water but may require several modifications. To
date, field studies on larval fish survival have not been com-
pleted.
8. Other possible intakes capable of larval fish protection include
low-velocity, filtration-type structures (infiltration beds and
slotted or perforated conduit) and the horizontal traveling
screen with fine mesh screen.
-------
SECTION 3
EECOMMEMDATIOKS
Much effort has been expended in recent years toward development and
evaluation of fish protection systems at water diversions and power
plant intakes. To date, however, there exists no one screening system
that has been deemed "best technology available." Several concepts
and prototypes have been introduced that show promise for fish pro-
tection but too often these same designs present major operating
problems. Site specificity may require unique designs for each site
to satisfy the "best technology" requirement. However, several pro-
posed concepts, if sufficiently developed and evaluated, may be widely
applicable at water intakes.
Areas in need of further study and development are suggested by the
current state-of-the-art of fish protection at water intakes. Several
of these areas are listed below:
1. Assessment of impact of entrainment and impingement losses at
existing intakes on the source water populations.
2. Prediction of fish losses and impact at proposed water intake
sites.
3. Development of methods to crowd, guide, and otherwise control the
movement of fish past water intakes, including control and labor-
atory study of fish response to velocity and temperature gradients,
as well as other stimuli.
k. Protection of larval fish and eggs at water intakes using fine
mesh screening, filtration devices, and low velocity slotted and
perforated conduit.
5. Development of prototype structures from results of the laboratory
tests suggested above.
6. Establishment of a nationwide task force on intake structure, re-
search, and development. To preclude duplication of effort, a
need exists for a timely and efficient means of coordinating
proposed studies, status reports, and results of studies.
-------
SECTION k
PLANT SITING AND INTAKE DESIGN
GENERAL
The importance of plant siting and intake location in reducing adult and
larval fish loss is recognized. In some river systems, however, spawning
migration of many species and transport of eggs and larvae with river
currents may preclude "favorable" siting. Egg and larval forms of
many species of fish are subject to transport with the currents for
at least a short period of time. Consequently, the protection of
adequate numbers of larval fish near power plant intakes is in part
dependent upon the amount of water withdrawn. Therefore, it is desir-
able to avoid withdrawing large percentages of the body of water un-
less larval fish protection is provided for or unless it has been
determined that the amount of entrainment is an acceptable loss.
INTAKE CONFIGURATION AND DESIGN
There are three basic orientations of cooling water intakes with
respect to the shoreline: offshore conduit, shoreline (bankside),
and the intake approach channel. Descriptions of these designs have
been well documented.^ Selection of a design in the past has been
based primarily on factors unrelated to protection of fish. Subse-
quent evaluations of fish entrapment have provided some comparative
information on the magnitude of fish losses at the different types
of intakes. However, because of the many variables associated with
impingement at each site, comparison of intakes among plants is diffi-
cult.
Offshore Intake
Minimization of fish losses, including larval fish, may be achieved
by siting intakes offshore in areas of low densities of fish. On the
other hand, if these intakes are located in areas of high concentrations
of fish, offshore intakes can result in adverse impacts to adult and
larval fish because of their usually high entrance velocities. After
the fish enter the conduit and are pulled toward the intake pumping
structure, their chances of escape are greatly diminished.
An additional problem exists with some offshore intake configurations
-------
which result in a vertical withdrawal as the water enters the conduit.
Fish are much less sensitive to water flowing vertically than hori-
zontally. Since fish can better detect the horizontal flow, a velocity
cap placed horizontally above the end of the intake pipe to convert
vertical flow to horizontal flow has been successful-1- in reducing the
numbers of entrapped fish. Southern California Edison Company, which
installed the first velocity cap in 1956 at the El Segundo Generating
Station, reported 90 percent reductions in fish entrapment.9 This
company has also undertaken testing at Los Angeles, California, to
determine the most efficient design of the velocity cap.
Shoreline or Bankside Intake
The orientation of the intake screen housing flush with the shore-
line offers some potential for lateral movement of fish to escape
entrapment. However, most shoreline intakes contain separate suction
pits for each screen with openings only on the front side. These
openings are usually covered by trashrack bars spaced approximately
9 cm apart and located below a concrete curtain wall. Once inside the
screen well, the fish have no lateral escape route and must pass back
through the trashracks to avoid impingement. In California, one
version of the shoreline design (termed the "Pacific Gas and Electric
Intake Design"3) has the screens placed flush with the shoreline with
no divider walls, allowing free direct and lateral passage of fish.
One large cage-like trashrack located out from the screens excludes
large debris. The approach velocity (velocity of flow through the
trashrack) is designed to be less than the sustained swimming speed
of the indigenous fishes. If the fish passes through the trashracks,
it does not become trapped in a well but may swim laterally along the
face of the screens to avoid impingement.
Approach Channel Intake
The location of the intake screen housing structure at the end of an
approach channel is usually considered less effective for fish pro-
tection than a shoreline orientation because of the entrapment effect
created by the channel.^-5 If the fish follows the intake shoreline,
it eventually encounters the end screen of the pumping structure. A
combination of eddy currents, turbulence and turbidity in the corners
where the end screens meet the channel banks is probably responsible
for the higher impingement usually associated with end screens at
many approach channel intakes.
Biologists at Duke Power Company attribute low numbers of impinged
fish at Buck Steam Station to an intake located flush with the river-
bank and lacking eddy currents. » Conversely, higher numbers of
impinged fish at Duke Power Company's Marshall Plant and Allen Plant
were attributed in part to the location of these intakes at the end
of a cove (Marshall) and a shoreline depression (Allen).
The Tennessee Valley Authority has compared impingement monitoring
results at its nine channel intakes and five shoreline intakes. Of
-------
the former nine channel intakes, five showed very low numbers of
impinged fish while the remaining four produced much higher numbers.
Of the five shoreline intakes, four produced low numbers of impinged
fish, and one produced high numbers. In these cases, the numbers of
impinged fish were not directly related to type of intake. Differ-
ences in impingement among plants may have been caused by differences
in fish densities near the intake; species common to the area; sever-
ity of winter cold shock on threadfin shad; and intake velocities
through the skimmer opening, channel, trashrack openings, and screen.
In addition, impingement at a plant is probably affected by several
other often subtle factors including the following: water elevation,
temperature changes, turbidity, fish migration, schooling behavior,
light conditions, fish condition, etc.
A skimmer wall at the entrance of the approach channel, if deep
enough, may reduce entrainment of larval fish. However, a skimmer
wall may also be selective for bottom dwelling fish and could create
a trap for fish that swim under the wall. In addition, high approach
velocity through the skimmer wall opening, through the channel, or
through the trashracks and screens may seriously reduce the ability
of fish to escape from approach channel intakes and intakes with
skimmer walls. Where constrictions occur in an approach channel
intake, intake velocities may surpass the sustained swimming speed
of many species and sizes of fish and result in a high rate of fish
entrapment.
Except by their possible location away from high concentrations of
larval fish, none of the three intake orientations offers any mitiga-
tion in entrainment of larval or young juvenile fish.
8
-------
SECTION 5
BEHAVIORAL BARRIERS
GENERAL
To minimize the problem of fish entrapment at cooling water intakes,
several behavioral screening methods have been evaluated for safely
diverting fish. It is emphasized here, as in several of the reports
on this subject, that, before any device of this type can be fully
evaluated from a biological standpoint, a thorough understanding of
several pertinent biological characteristics of the fish to be pro-
tected is required. Particularly important are the species of con-
cern, their sizes and swimming ability, the effect of water temperature
on their swimming ability, and behavioral characteristics such as
schooling and preference for specific zones or strata of the water
column. The remainder of this section is a summary of available fish-
protective behavioral barriers.
ELECTRICAL BARRIER
Description and evaluation of the feasibility of guiding fish with
electricity is well documented. "3 Typically, an electric barrier
(Figure l) consists of an array of electrodes suspended across the
intake which, when energized, prevents fish passage. The first
patent for this type of barrier was taken in 1910.
The results from studies on guiding fish by electric barrier have
been varied. Electric barriers have been successfully used to stop
upstream-migrating salmon. If a fish swims too far into the electric
field, it is stunned and carried downstream. Upon recovery, an
upstream-migrating fish swims back toward the electrode and eventually
is guided to one side of the river where the bypass is usually located.
On the other hand, downstream-migrating fish (or fish approaching an
intake channel or structure) which are stunned by an electric field
are likely to be carried by the current toward the intake screens.
The effects of electric fields on fish are discussed by Maxfield.12
Holmes ^ discussed the experience of electrical fish diversion systems
in California and the Pacific Northwest up until 19^-8. Results of
his research indicated that some of the first systems were successful,
but ultimately all the electric barriers were removed and evaluated
as failures.
-------
ELECTRODE LINE
OVERHEAD »-
-GROUND LINE ON STREAM BOTTOM
UPSTREAM MIGRATING SALMON
DIRECTION OF FLOW
FISH BY PASSING
IN SLUICEWAY
PLAN
i—CABLE SUPPORT
iOLID CORE ELECTRODE CASING
GROUND LIME RECESSED
WITH BOTTOM
ELEV. A-A
FIGURE 1, TYPICAL FEATURES OF AN ELECTRIC SCREEN USED IN U,S, (2,7)
10
-------
Recent work in electrical systems has been concerned with guiding
techniques. Laboratory experiments discussed by Maxfield^ and
Trefethen14 give some results on the configuration of the electrode
array and its angle to the flow. Maxfield's work on the potential
pulse frequency and pulse duration of his system showed that, when
using an array of several rows of electrodes lj-5.7 cm apart, the
optimum potential was 60 volts and the most effective pulse fre-
quency was two pulses per second. Trefethen found that positioning
the electrodes at an angle of kO degrees to the flow and spacing
them 30.5 cm apart was the most efficient and practical arrangement.
Trefethen achieved a diversion efficiency of 68 percent of salmon
fingerlings with an electric screen using a voltage gradient of one
volt per centimeter and pulse frequency of 8 pulses per second with
a pulse duration of Uo milliseconds. Maxfield discussed a full-scale
experiment at the Cascade Reservoir in Idaho. The electrodes were
arranged in parallel rows to allow for a sequence of pulses which
were designed to guide the fish toward the bypass. This laboratory
test gave diversion efficiencies up to 80 percent for adult squaw-
fish.
Recent research conducted at the Connecticut Yankee Atomic Power
showed the use of an electric barrier to exclude fish from a 2*1.9
nP/sec intake mounted flush with the shoreline. Results showed some
reduction in numbers impinged, but size and species selectivity was
apparent. Problems were encountered because of the excessive time
that fish remained in the area between the electric barrier and the
traveling screens between tests. Additionally, ice formation
necessitated removal of the floating electrode booms during winter
months. However, project biologists believed the results of these
tests were encouraging enough to warrant further testing of additional
designs and modifications of the electric barrier. •*•"
At a few plants, electric barriers were installed with no preoperational
baseline data describing the extent of the fish impingement problem.
Furthermore, too often little or no postoperational biological testing
of barriers has been conducted to evaluate the effectiveness of the
mechanism. For example, in the 19^0 's Northern Indiana Public Service
Company (NIPSCO) installed an electric fish screen at their 215 mega-
watt Michigan City plant because migrating minnows and perch had
previously threatened plant operation each spring and fall. The
electrodes were spaced 30.5 cm apart in two rows spaced ^5-7 cm apart.
Voltages varied from 300 to 600 volts, pulse rate varied from 1 to 5
per second, and the water approach velocity was 20.7 cm/sec. This
electric barrier is currently being used in conjunction with an air
curtain. The barrier was labeled a success^- since it has been in
operation for more than 27 years, but there has never been any con-
trolled biological testing of the system.^ Too often the only
criterion for the success of these devices is whether or not plant
operation is interrupted by fish impingement. The installation's
satisfactory operation for 27 years led to the installation of an
additional electric barrier at another NIPSCO klh megawatt plant.
11
-------
The successful use of the electric fish barrier for prevention of
impingement and entrainment at water intake systems appears doubtful
at this time for several reasons.
1. Approach velocities at most water intakes may "be too high for
most guidance devices or barriers.
2. Most studies have shown low or marginal reductions in impinge-
ment losses following installation of electric barriers at
large intakes.
3. The electric barrier requires much trial-and-error fine-tuning
to provide optimal operation.
k. The effect of an electric gradient is dependent on the fish
species and size of the organism.
5. Since they operate as a behavioral device for juvenile or adult
fish, the electric guidance devices are not designed to reduce
entrainment of larval fish or small, weak-swimming post-larval
fish.
6. If a fish is stunned by the electric field, it may be carried
into the intake.
7. An electric barrier has not been developed for use in estuarine
or ocean waters.
8. The electric barrier may present a danger to humans and animals.
Electric barriers appear to have the most promising application at
intakes where one or few species of a limited size range are to be
protected. The electric screen, with all its published theory and
application, is sometimes summed up as follows: "so little is known
about how an electric field stimulates a fish that it is difficult
to design a successful electrical guiding device."1
SOIMD BARKEER
Attempts have been made to use sound barriers for diversion of fish
around power plant intakes. Fish have been shown to respond to
various intensities and frequencies of sound. A sound barrier "typi-
cally uses underwater speakers located at various depths and locations
to broadcast the frequencies desired. The fish trying to avoid the
sound outputs are guided to an area where a bypass or safe fish re-
moval system is located. A wide variety of sound-generating devices
has been investigated, but none has been very successful. The prob-
lems associated with varying intensities and frequencies for different
species seem to be the main reasons for lack of success.
After an extensive research effort to guide fingerling Chinook salmon
12
-------
-• Q
in the late 19^-0's, Burner and Moore concluded that certain fishes
may be frightened momentarily by any noise but adjust to disregard
it (become conditioned) almost instantaneously and that at no time
did a sound frequency or intensity influence the action of the fish
enough to be utilized in guiding young salmon into safe passages
around dams and diversions.
19
Vanderwalker indicated that fish respond to selected frequencies
and concluded that repeated exposures did not affect the sensitivity
and acclimation of the fish to the frequencies.
The use of sound barriers proved to be unsatisfactory for repelling
fish at Indian Point' and Surry^O Power Plants. The Surry sound
barrier was designed and installed by Virginia Electric and Power
Company (VEPCO) for the purpose of reducing impingement. VEPCO
recognized at Surry that fish became acclimated to repetitive sound.
Rock-and-roll music, which produced ultimate discordance with varying
frequencies and amplitudes, was subsequently used. This sound
barrier was partially successful and did reduce the fish impingement
problem but the company concluded that this concept was not the
solution to their particular situation. The sound barrier was sub-
sequently replaced by a mechanical device to reduce the fish problem.
Based on the results obtained by VEPCO, Schuler and Larson conducted
sound avoidance experiments in California to test the reaction of
black perch, shiner perch, kelp surfperch, greenfish, and northern
anchovy. Rock music, a killer whale tape, and a range of frequencies
from 20 c/s to 15,000 c/s resulted in no observable fear reaction when
played through the underwater speakers. Experiments suggested that
the fish did not respond to the tape replay of a live sound with the
same reaction they would have given to the live sound because of the
absence of a shock wave which would have been associated with the
live sound.
In addition to the music experiments, Schuler and Larson performed
experiments with an underwater pneumatic impact device which pro-
duced a shock wave ("popper"). It was found that most fishes avoided
the immediate area of the "popper" by at least 3 ^ when it was cycled
continuously at rates of 2 to 15 cycles per minute. Further, the
"popper" appeared to be more effective in open water as opposed to a
confined forebay. Fishes toward the upper part of the water column
showed a greater response to the "popper".
LIGHT BARRIER
The use of light to guide fish has been investigated as a possible
fish barrier for water intakes. It has been shown that under cer-
tain conditions some fish can be repelled by lights while others
are attracted. In general, it appears that the use of light as a
barrier screen is not considered reliable.
22
Fields has done extensive work on guiding migrant salmon with
13
-------
artificial light and concluded that "under some conditions artificial
light can repel migrants and divert them from certain areas. In
such situations, the problem is one of balancing various environmental
stimuli so that light intensity overrides velocity, turbidity, depth,
and temperature. Under other conditions artificial light can attract
migrants and concentrate them in particular areas. Some degree of
light adaptation is necessary before attraction will occur,"
22
Fields stated that all dark-adapted downstream-migrant salmon and
steelhead trout can be guided by light repulsion when they are in
relatively clear water flowing at more than 30 cm/sec. Any light
perceivably brighter than the adaptation light will elicit the
avoidance response under controlled conditions. For example, in
areas of current velocity of 1.2 m/sec or greater, unshaded lights
placed along the stream banks will move the downstream migrants away
from the bank. For silver salmon, a constant light is more effective
than an interrupted or flashing light because the fish float into or
through the light barrier during the dark phase of the cycle. It is
more difficult to guide fry by repulsion because of their lesser
swimming ability and their choice of lower-velocity waters. It
also appears that fry are more likely to adapt to the light.
Fields found guidance by light attraction inevitably involved a
certain degree of light adaptation. Fields expected that under
normal conditions dark-adapted fish would not be guided by light
attraction. Attraction guidance is more effective when the original
adaptation illumination is then followed by a reduction in illumina-
tion. For example, a light barrier constructed at a 90 angle may
block all downstream migrants. The length of time that the fish can
remain stationary against the flow while resisting the light is the
fish adaptation time to the higher-intensity light. When a fatigued
condition is reached by the migrants, they are pulled by the water
current into the higher illumination area. After the migrants leave
the higher-illumination area, they are attracted to a downstream
light area of the same or lesser illumination. The brighter the
initial adapting area and the longer the adaptation period, the
better the movements of migrants can be controlled. Fields also
found that as the light-adapted fish are subjected to sudden darkness,
they are unable to maintain a visual orientation and are swept down-
stream at the mercy of the water currents.22 Striped bass were
found to quickly adapt to and pass through an intense illumination
barrier. 3
The unpredictability of individual fish species' reactions to lights
precludes a general recommendation for use of lights at water intakes.
However, it has been suggested' that lights may serve to improve fish
guidance when used to complement other barriers or removal systems
which rely on the visual responses of the fish. The use of lights
in conjunction with the Detroit Edison Monroe Power Plant fish pump
increased the pumping efficiency by 1.5 to 2.0 percent. Prior to
installation of the lights, efficiency was 80 to 90 percent. Addi-
tionally, the use of lights apparently resulted in an increase in the
-------
2k
removal of smaller-size fish than had previously been pumped.
AIR BUBBLE BARRIER
1 2
The air curtain (Figure 2) has been summarized in several references. '
Impingement of alewife, a schooling shad species similar in size
and appearance to threadfin shad, has reportedly been reduced due
to the presence of air bubblers at Wisconsin Public Service Company's
Pulliam Plant and Kewaunee Nuclear Plant on Lake Michigan.lj25
The Kewaunee air bubbler, located at an offshore intake structure,
is shown in Figure 3. Although no controlled tests have ever been
conducted, the company believes the bubblers are effectively exclud-
ing the alewife. ^ Prior to the installation of the air bubble
barrier, there had been several shutdowns of the plant caused by
schools of alewives blocking the screens. Since the air screen
installation, there have been only one or two shutdowns. Occasional
outages of the air bubbler compressor have been accompanied by
heavy impingement of alewife on the screens. However, operation of
the bubblers did not eliminate impingement. Occasionally, schools
of alewife break through the air curtain, but these occurrences are
not of the magnitude and frequency experienced without the barrier.
The Northern Indiana Public Service Company's (NIPSCO) Michigan
City plant bubbler is believed to effectively divert alewife while
larger fish are diverted by the electric screens at the same intake.-'-?
Brett and MacKinnon*^ reported that a bubble barrier failed to guide
young spring salmon during their nighttime migration. When the
bubble barrier is accompanied by continuous or flashing light, the
number of fish deflected by the air screen appeared to increase.
Bates and Vanderwalker, 2? testing spring Chinook salmon, also
found high deflection rates with air screens during daylight con-
ditions but poor results during dark conditions. Best results were
obtained during daylight hours with an approach velocity of 58
cm/sec. They stated that "the effectiveness of an air bubbler screen
in deflecting downstream migrants is a function of the fish's ability
to see it." The visual ability of fish is limited during nighttime
hours or when the fish are located in highly turbid waters. They
tried the use of artificial lights to solve the nighttime problem
but found that the lights did not improve the diversion efficiency.
They concluded that additional studies with various lighting techni-
ques might improve the nighttime effectiveness.
pfi
Smith reported a successful use of a 200-fathom long air curtain
to guide herring into a weir for commercial harvest. Guiding was
successful if the fish were not overcrowded or pushed too fast.
29
Imamura and Ogura reported the air curtain to be effective for
driving Trachurous japonicus in Japan but that long-term crowding
could not be accomplished.
15
-------
n.
FIGURE 2. AIR BUBBLE SCREEN (ELEVATION VIEW) (2,7)
16
-------
WATER SURFACE
V
-
o0
AIR BUBBLE
SCREEN AROUND
THE PERIPHERY OF
CONE
INFLOW
INTAKE STRUCTURE
CONSISTS OF 3 INVERTED
CONES PLACED IN THE
SHAPE OF AN
EQUILATERAL TRIANGLE
FLOW TO SHORELINE
SCREENWELL
FIGURE 3, AN OFFSHORE AIR BUBBLE INTAKE STRUCTURE, (7)
-------
Bell'3 stated that fish show an immediate response (probably a
fright response) to a bubble barrier. However, he concluded that
"experiments with salmonid fish indicate that bubble screens are not
effective in either stopping or guiding."
A recent laboratory study by Bibko, Wirtenan, and Kueser23 showed
that an air curtain effectively blocked the movement of young-of-
the-year striped bass even during darkness. Results of this study
showed that young striped bass would not cross an air-bubble screen
at temperatures of ^.5 C or 11.1 C, but they would drift passively
through the air screen when the water temperature was 0.8 C. Gizzard
shad did not cross the established air screen at 11.1 C but contin-
ually passed through at ambient water temperatures of 0.8 C and k.5 C.
It was also found that the passage of young striped bass is not
restricted at any water temperature if an opening of 5 cm or more
was allowed in the bubble barrier.
21
Schuler and Larson found little diversion of fish into a flume
bypass using a screen placed at a 30° angle to the flow. When air
bubbles were tried in conjunction with the screen, results were not
substantially increased. However, they believe that the failure was
primarily due to the breakdown of the air curtain due to high water
velocity and insufficient air pressure. Nearly 100 percent diver-
sion was obtained in the intact lower part of the air curtain.
Alevras has discussed Consolidated Edison's use of an air bubble
installation at the Indian Point Power Plant on the Hudson River
estuary. This system, shown in Figure ^, consists of two vertical
rows of horizontal bubbler pipes which release air at 1.2 m inter-
vals directly in front of the intake screens. Since installation
the number of impinged fish has been lower,but the reduction varies
by species. The air bubble screen appeared to repel some fish
species but not others.32
Kupfer and Gordon^3 stated that the city officials of Milwaukee ini-
tiated a study for a permanent bubbler system across the Milwaukee
River after reviewing the work of the United States Bureau of
Commercial Fisheries on their successful guidance of Atlantic
herring in clear water using bubble barriers. The purpose of the
air curtain was to prevent alewife from migrating upriver where
they die in large numbers and cause sanitation problems.
The bubbler system contained 152 m of plastic pipe traversing the
river on a ^5° angle to the flow. A chain was attached to the pipe
to hold it on the bed of the river. Clogging of holes 0.3 mm in
diameter spaced 15.2 cm apart resulted in a change to 0.5 mm diameter
holes spaced 5 cm apart. During a six weeks evaluation in spring
196^, the operation of the curtain appeared overall to retard the
upstream alewife migration. Initial results were inconsistent and
statistical analyses were not reported.
Field and laboratory tests were conducted in 1966-67 by the Tennessee
18
-------
AIR SUPPLY
&J-
WHARF ' - • .
,*?_: •.•?••». •
TWO ROWS
OF AIR BUBBLERS
SPACED 46 cm <
PILING'
4 ' ,
FIXED SCREEN
SCREENWELL
DIRECTION OF
FLOW
FIGURE 4, INDIAN POINT AIR BUBBLE SYSTCM, (?)
19
-------
Valley Authority to evaluate the effectiveness of an air curtain
for "leading, holding, and herding fish."^4 The objective of the
study was to evaluate the potential use of an air curtain in the
harvest of commercial fish species. Laboratory tests were performed
on gizzard shad, small mouth buffalo, carp, and largemouth bass in
a 18.3 mx 2.k mx 2.U m flume using an air curtain produced from
holes on 1.9 cm centers in an air base.
Results of the tests included the following:
1. Carp and gizzard shad could be contained significantly longer
than largemouth bass and small mouth buffalo.
2. Carp could be crowded into a small space before breaking through
the curtain. Crowding of gizzard shad was less successful.
3. Tests designed to evaluate the effectiveness of the curtain in
guiding fish to a bypass were unsuccessful. All species except
gizzard shad passed through the bubbles rather than being
guided along the air curtain. When a current of 21.3 cm/sec
was created in the flume, these species readily passed through
the curtain. In both stagnant and flowing water all gizzard
shad were retained by the curtain, but none was guided the full
length of the curtain to the bypass.
Results of field tests comparing the bubble curtain with a conven-
tional lead net in guiding fish showed higher guiding rate with the
conventional net, but the difference was not significant.
In several of the studies on air curtains, it was emphasized that
the bubbler must extend all the way to the bottom of the flume or
water column. Fish were able to find gaps between the hose and the
flume floor and would readily circumvent the barrier by passing
through this bubble-free zone.
Evaluations on two prototype air curtains have recently been com-
pleted. Arkansas Power and Light Company (AP&L) installed a 122 m
long air curtain across the entrance of the cooling water intake
canal at the Arkansas Nuclear Plant - Unit One, located on the Dar-
danelle Reservoir.35 Water depth in the location of the curtain
was approximately k.6 m and air holes were spaced at 25 mm intervals.
Testing was performed between fall 197^- through summer 1975. Results
of the one year of testing showed the air curtain to be ineffective
in repelling impingeable-size fish of 38 species. During the test
periods approximately 9*5 million fish were impinged on the intake
screens, approximately 5 million of which were impinged during air
curtain operation. Difference in impingement while the curtain was
in the "on" and "off" modes were not significant during the fall,
winter, and summer. In the spring, numbers of impinged fish were
significantly higher with the operation of the air curtain. Thread-
fin shad contributed 91 percent of the total number of fish impinged
during this study.
20
-------
In 1973 a lj-9 m long air curtain was installed at the entrance to
the cooling water intake at Northern States Power's (NSP) Prairie
Island Nuclear Plant in Minnesota. A one-year evaluation beginning
September 197^- indicated that the air curtain was largely ineffective
at deterring most fish species.^ Crappie and freshwater drum were
deterred 19 percent and 9-8 percent, respectively, but the operation
of the curtain increased the numbers of carp (5«3 percent), silver
chub (kO percent), and white bass (31.7 percent). Overall, the
operation of the air curtain resulted in a 7.1 percent increase
in fish entering the intake channel. However; during the months
of April, May, and July significant deterrence (65.5 percent, 30.8
percent, 30.0 percent, respectively) was found for total number of
fish, resulting in a recommendation that the air curtain be operated
only during these months.
WATER JET VELOCITY"
?7
Bates and Vanderwalker ' studied the guidance of spring Chinook
salmon with water jet barriers. Fish diversion ranged from 60 to 80
percent under varied water pressures, array angle, and approach
velocities. These preliminary studies indicated some promise in
diverting fish with a water jet system. Limitations include the
large volume of water that would be required at a large installation
and extensive maintenance on the jet orifices because of rusting
and clogging. There has not been any research or development done
on a water jet system in the last few years.
CABLE AND CHAIN SCREENS
•yj
The Department of Fisheries of Canada^ experimented with a traveling
cable screen to guide downstream-migrating fry. The system was de-
signed to take advantage of the fish's tendency to avoid objects
moving through the water. Cables hanging at close intervals were
positioned diagonally across the river to form a screen. In this
experiment the hanging cables were not very effective, as the fish
tended to swim through the cable screen.
oQ
Fields et al. tested the effectiveness of a stationary chain
barrier using three age groups and four salmonid species. The
laboratory tests were performed in still water during daytime and
nighttime periods. Fish were forced to enter one of two channels,
identical except that one of them included a chain barrier at its
entrance. A chain barrier with spacings of 2.5 cm produced a day-
time deflection of 66 percent. Although this result was statistically
significant, it was not large enough to be of practical importance;
the deflection expected by chance alone was 50 percent. The chain
barrier was even less effective in the dark, producing a nighttime
deflection of only 56 percent. Unequal illumination in the channels
during the daytime was more effective than the chain barrier in con-
trolling behavior of the fish. For example, 89 percent of the fish
avoided entering the brighter channel, while only 66 percent avoided
entering the channel blocked by the chain barrier.
21
-------
OQ
Fields et al. y also investigated the use of chain barriers in flowing
water by using two angles, two densities of chain spacing, two velo-
cities of water, and three species of hatchery-reared fish. They
found that the overall average deflection of fish by the chain
barriers was 53.6 percent as compared to a 50 percent deflection
which might be expected by chance alone. The greater influence of
unequal illumination over the chain barrier effect on fish behavior
was indicated again in this study. The researchers concluded from
these two studies that chain barriers were of "no practical value
in guiding young salmon..." in either still or moving water.
•37
Brett and Olderdice, working with migrating sockeye salmon, also
experimented with chain barriers. Studies were conducted with a
maximum water velocity of ^5 cm/sec; chains spaced at intervals of
5, 10, and 15 cm; and chain placed ^5° to the flow. Maximum average
deflections of 9*4- and 71 percent were obtained in daytime and night-
time, respectively, using 5 cm spacing of chains.
LOUVEES
The concept of the louver for the protection of fish at water in-
takes arose from earlier attempts to prevent moss growth in California
irrigation canals. The earliest attempts to guide fish with
louvers were in 1952 at the U. S. Fish and Wildlife Service Coleman
Fish Hatchery.
The success of the louver barrier depends on the ability of the fish
to detect and avoid abrupt changes in velocities and flow directions.
A typical louver barrier (Figure 5) consists of a series of narrowly
spaced vanes placed 90 to the flow and a bypass. Flow straighteners
(Figure 5) often are placed downstream of the louvers. The most
efficient diversion of fish is achieved by optimizing at each site
the approach velocity, louver slat spacing, louver array angle to
flow, and the bypass velocity and shape. The most effective louver
slat spacing and array angle to flow depend to some extent upon
species, size, and ability of the fish to be diverted. Bates and Logan
and Bates and Vinsonhaler^2 discussed in detail the relationships of
fish swimming speed, louver angle, and approach velocity as they
affect the ability of the fish to avoid entrainment through a
louver barrier.
In 1957 the U. S. Bureau of Reclamation and the U. S. Fish and
Wildlife Service developed and tested the Tracy Fish Collecting
Facility, a louver system designed to protect fish at the entrance
to the Delta-Mendota Canal in California. ^ This system (Figure 6)
consists of a primary and secondary array of louvers, bypasses, tanks
to hold fish, and transport trucks to return fish to the natural
water. Water depth in the 25.6 m wide pumping canal varies from
6.6 m to 7.9 m> an
-------
ro
oo
CLEAR SPACE BETWEEN BARS
FIGURES, LOUVER DIVERSION SYSTEM-SCIATIC (2)
-------
LOUVERS (TYP.)
OUTLET TRANSITION
AREA
GATE STRUCTURES
& ACTUATORS
(TYP.)
TRASH RACKS
(TYP.)
INTAKE TRANSITION AREA
BYPASS TRANSITION
(TYP.)
MAIN CHANNEL AREA
(BAYS)
PRIMARY CHANNEL
CONTROL PLATFORM
CONTROL PANEL
TRASH RAKE
OVERHEAD RAIL
(TYP.)
FIGURE 6, DELTA FISH DIVERSION-LOUVER SYSTEM (2,3,7)
-------
species, fish size, approach water velocity, bypass to channel
velocity ratio, louver array angle, slat spacing, time of day,
and debris level. The 97.5 m long primary louver is placed 15
degrees to direction of flow. Four evenly spaced bypasses are
provided along the length of the primary louvers. Louver slats
are placed 90° to direction of flow and spaced 25 mm apart. Results
obtained from tests on the primary louver array in 1957 showed an
overall guiding efficiency of approximately 97 percent.
In 1958, tests of the secondary louver system showed a 76 to 86 per-
cent guiding efficiency of all fish less than 25 cm in length when
approach velocities did not exceed 91 cm/sec. Nearly all (95 to 99
percent) of those fish 3.7 to 10 cm long were guided to the bypass.
A bypass to approach water velocity ratio of 1.4:1 improved guiding
efficiency over a 1 to 1 ratio. The increased efficiency was fish
species and size dependent.
In 19614- a series of tests was conducted by the California Water
Resources Agency and the Bureau of Reclamation to determine the
effect of louver slat spacing and guiding efficiency of several
fish species at the Tracy Fish Collecting Facility. ° Tests of
four slat spacings (2.5 cm, 3.7 cm, 6.U cm, and 10 cm) were per-
formed on the secondary louver array. The original 2.5 cm louver slat
spacing was found to be superior for all sizes of those species
(striped bass, white catfish, shad, and smelt) which appeared in
sufficient numbers to permit an evaluation.
ko
Bates and Jewett J found a 98 percent deflection of immature migrating
steelhead with a louver barrier at the Maxwell Irrigation Canal,
Umatilla River, Oregon. Louver slat spacing was 5.0 cm. Efficiencies
remained above 90 percent when the slat spacing was increased to 10.8 cm.
kk
Ducharme reported a five-year evaluation of a louver barrier at Ruth
Falls Power Plant in Nova Scotia. Guiding efficiency of 2-year-old
Atlantic salmon smolts, 35-2 to 37.7 cm in length, increased from
57 percent during the first test year to 80 percent after 5 years
and several modifications. Louver slats were placed 5.1> 10.2, 15.2,
and 30.5 cm apart and 90 degrees to direction of flow. Optimum by-
pass to approach velocity ratio was determined to be 1.0 : 1.5.
Approach velocities ranged from 0.2.k to 1.06 m/sec. An increase in
guiding efficiency occurred at the higher approach velocities after
completion of modifications to the bypass. Comparison of slat spacing
tests led to the conclusion that the optimum spacing for guiding
efficiency as well as "economy of bypass water" might be a "wide
bar spacing at the widest part of the louvers, with gradual reduction
in bar spacing leading towards the bypass."
i-)-\
Schuler and Larson found for several coastal species in California
that the highest degree of guidance was obtained with slats placed
2.5 cm apart, louver array 20 degrees to flow, bypass velocity 1.5 times
that of approach velocity, approach velocity 0.6 cm/sec, and bypass
design curved with no abrupt changes in direction.
25
-------
A louver barrier (Figure 7) has been proposed for the offshore
intake of the Nine-Mile Point Nuclear Power Station No. 2 to be
located on Lake Erie.' An extensive experimental testing program
has been undertaken to design the facilities. Five to 13 cm long
alewives were tested on a 2k m long hexagonal-shaped louver. Water
flows into the structure along its periphery and fish are guided to
the center of the structure where they are then induced to enter a
bypass.
Most studies on louvers indicate a decreased guiding efficiency with
increase in debris load. To assist in cleaning, one variation's
design (Figure 8) includes a vertical traveling louver similar to
the conventional vertical traveling screen.3 Several vertical louver
screens are placed side-by-side to form a continuous line of louvers
for guiding fish to a bypass.
A 5-year cooperative study by the California Department of Fish
and Game, California Department of Water Resources, U. S. Fish and
Wildlife Service, and the U. S. Bureau of Reclamation was initiated
in 1970 to develop fish screens to divert fish past the proposed
large volume Peripheral Canal. 5jW it was expected that 80 per-
cent of the anadromous fish resources in the Central Valley could be
affected by the Peripheral Canal diversion. The screen would have
to be capable of protecting eggs and larvae as well as juvenile and
adult fish to be satisfactory. In 1973 it was recommended that the
louver concept be dropped from further consideration as a screening
alternative. Satisfactory guiding efficiencies were not expected
for eggs or fish smaller than 37 mn.
A disadvantage of the fixed louver system is that the shallow angle
of louvers with respect to the channel flow requires a rather long
line of louvers, which increases the cost of the intake relative
to other intake designs. Additionally, since the louver system
does not remove trash, conventional screens downstream of the louvers
may be required.
26
-------
PLAN VIEW
AVE. APPROACH
VEL. = 3 cm/sec
6.5 nr/sec
ROOF SLOT OPENING TO REMOVE
LOUVER PANELS FOR CLEANING OR
REPLACEMENT (TVP.)
'BYPASS
' E.'IT.
VEL.= 1.1
B
HEATED BAR RACKS (TYP.)
FLOW TO SCREENWELL (TYP.)
FISH TO BYPASS
LOUVERS SET AT 2.5 cm CLEAR SPACING,
CONSTRUCTED OF WOOD OR PLASTIC
TO PREVENT FRAZIL ICE FORMATION.
LOUVERS CAN BREAK AWAY IF CLOGGtD
AND BE REMOVED IN SCREENWELL.
ELEVATION VIEW
SECTION B
FIGURE 7. IDUVER SYSTEM AT NINE MILE POINT NUCLEAR POWER STATION, (7)
27
-------
ro
00
VELOCITY CAP
FLOW
ELEVATION VIEW OF
VELOCITY CAP
CIRCULATING
WATER PUMPS
DISCHARGE
TRAVELING
SCREEN
INTAKE
GUIDING
VANES
TRAVELING
BAR RACKS
FISH BUCKET
COLLECTOR
PLAN VIEW OF SCREENWELL
FIGURE 8. TRAVELING LOUVERS AT THE SAN ONOFRE NUCLEAR POWER PLANT, (?)
-------
SECTION 6
PHYSICAL BARRIERS
GENERAL
Because of debris and fish present in the raw cooling water and the
need for continuous plant operation, power plants require fool-proof
screening devices to prevent clogging of the condenser tubes. By
far the most common screen system in use today is the vertical trav-
eling screen (Figure 9)- This screen consists of an endless belt
of removable screen panels drawn over sets of top and bottom sprockets.
Screen panels are usually 2.k m to ^.3 m wide and 0.6 m high with
9.5 mm square opening screen. A narrow lip, or ledge, is provided
at the bottom of each screen panel to lift debris and objects that
do not adhere to the screen. The vertical traveling screen is
usually not rotated and cleaned until a specified pressure differen-
tial resulting from clogging exists across the screen. This varies
from a few hours to several days depending on debris load. In some
cases the breakup of aquatic vegetation causes such a rapid buildup
on the screens as to necessitate continuous rotating and washing.
The number of screens located at a plant ranges from a few to 20 or
more. They are typically installed side-by-side in a single concrete
housing with each screen, or set of screens, separated completely
by partitions. The distance from the screens to the front side of
the intake structure curtain wall varies from less than a meter to
several meters. Water enters through an opening located below the
curtain wall. The opening contains vertical steel bars (trashracks)
typically spaced approximately 8 cm apart which are designed to
screen any debris large enough to damage the traveling screens.
Advantages of the conventional vertical traveling screen include the
following:
1. Commercial availability.
2. History of reliable performance, long service life, and minimal
maintenance.
3. Application to sites with fluctuating water levels.
k. Standardization and availability of components.
A serious drawback to these screens is the harm done to fish impinged
on and entrained through them. The design creates a trapping effect
29
-------
SCREEN DRIVE
SPRAY NOZZLES
FOR CLEANING
SCREEN BASKETS Y I
") —ft
. FLOOR OF SCREEN
/ / STRUCTURES
FIGURE 9, CONVENTIONAL VERTICAL TRAVELING SCREEN, (2,7)
30
-------
for fish by virtue of its single opening to the screen well. Once
inside the well the fish are surrounded by concrete walls and trav-
eling screens with the only route of escape back through the trash-
racks. Since this is also the area of greatest velocity, the chance
of escaping the well, especially for smaller fish with less swimming
capability, becomes minimal. Since most vertical traveling screens
are operated intermittently rather than continuously, fish can be
impinged against the screen for long periods of time. In addition,
the screens are not designed to remove live fish from the well.
The narrow lip, or ledge, on the bottom of the screen panels is in-
adequate to retain active fish. As the screen panel lip clears the
water, the fish may flip off and become reimpinged. Repeated im-
pingement may continue until the fish become exhausted and die trying
to avoid contact with the screens. Any live fish that are carried
on the ledge are exposed to the high-pressure system screen wash
used to clean the screen as it rotates.
Recent concern with protecting fish at power plant intakes has re-
sulted in a search for alternative screening devices capable of
minimizing fish losses while insuring continuous plant operation.
This review briefly discusses those screens which appear to be viable
alternatives or adjuncts to the use of vertical traveling screens.
MODIFICATION OF EXISTING VERTICAL TRAVELING SCREEN DESIGN
Provision for Escape Routes Inside Intake Suction Pit or Screen Well
Increasing the distance between the vertical traveling screen and
the trash racks and providing escape routes through the side walls
has been investigated by Washington Public Power Supply System
(WPPSS).^7 A design has been proposed based upon modifications to
the existing water intake system for the WPPSS Nuclear Project No. 1
located on the Columbia River (Figure 10). The intake structure
would consist of two vertical traveling screens having 6 mm screen
mesh openings. Fish-escape slots through the side walls would be
provided to the left and right of the screens. Since shoreline in-
dentations or dead-water areas tend to attract fish, the structure
wouT.d be located on the low-water bank of the river, with access to
the structure provided by a trestle from the high-water bank.
Conventional Vertical Traveling Screens Equipped With Fish Troughs
A modification to the intake screens at Virginia Electric Power
Company's (VEPCO) Surry Power Station has, resulted in substantial
reductions in mortality of impinged fish. »^9 The Surry Station
is a 1,560 megawatt nuclear power plant with once-through cooling located
in an area on the James River where saline concentrations range from
zero to 15 parts per thousand. As a result, both freshwater and
marine species are abundant around the plant site.
Modification to the intake screens included continuous rotation (3 m/min)
to reduce the impingement time for a fish to two minutes or less.
In addition, compartmented metal troughs were attached to each screen
31
-------
U)
ro
3 PUMPS 0.79 M3/SEC
TRAVELING SCREEN
ACCESS TRES
BRIDGE CRANE
DISCHARGE
CHUTE
MAXIMUM FLOOD OF
RECORD
TRAVELING SCREEN (6.4
MM MESH)
NORMAL HIGH WATER 108.5 M
TRASH RACK
EXTREME LOW WATER 10lu5 M
TO PLANT*
TOP OF
STOP LOGS
FISH ESCAPE SLOTS
FISH ESCAPE SLOTS
FIGURE 10, VERTICAL TRAVELING SCREEN INSTALLATION OF WPPSS
-------
panel frame to increase the efficiency of removing fish. These
troughs maintain a minimum 5 cm of water depth as the screen rotates
out of the water. As the trough rotates around the head sprocket,
the fish and water are spilled into a common return trough which
empties back into the river downstream of the intake. The high
pressure (63,000 to 8^,000 kg/m2 or 90 to 120 psi) screen wash was
also replaced with a low pressure (7,000 to 10,500 kg/m2 or 10 to
15 psi) wash system to assist in safe removal of fish from the
screens to the river.
Data collected during the first two years of operation (197^- to 1976)
showed a 93.8 percent immediate survival of total number of fish
sampled. For 26 species survival was 100 percent and for anchovies,
a sensitive group of fish, overall survival was 83 percent.
Because of the continuous operation of these screens, increased
maintenance is required over conventional intermittent operation.
The Surry screen panels are k.3 meters wide and carry 9 mm opening
wire mesh screen. It is now believed that maintenance could have
been reduced substantially by increasing the number and decreasing
the width of the screens. Narrower screens would reduce the weight
of the overall structure and consequently the wear on the moving
parts. Reducing the screen speed from 3 m/min to 1.5 m/min is being
considered and is expected to reduce maintenance costs considerably.
In addition, the use of currently available light-weight polyester
and Nitex screens would reduce the weight of the screen panels and
would also be expected to reduce maintenance costs. This material
is currently being used or considered for use on at least a few power
plant intake screens in the United States.
INCLINED TRAVELING SCREENS
Two types of inclined traveling screens exist. The first type is
very similar to the conventional vertical traveling screen with the
exception that it is inclined at a small angle (generally between 10°
and 15°) with the vertical. On this screen, fish, as well as debris,
can be retained more easily than on the conventional vertical travel-
ing screens because of the angle of screen and lip.
This type of inclined screen is used by a small number of installa-
tions and has basically the same advantages and disadvantages as the
conventional traveling screen. The installation cost of this type
of screen is slightly higher than for the conventional screen be-
cause of the longer screen well and other modifications needed.2
The second type of inclined screen is an inclined downstream screen
positioned at an extreme angle with the vertical (Figure 11). Although
it is still in its experimental stage, it has been used in Canada.
Fish protection was the basis for design of this screen. The screen
panel lips are made of pliable brush material rather than the con-
ventional metal plate. The combination of a screen with a small angle
to the horizontal and the pliable brush assembly provide a safe
33
-------
GATE LIFT
U>
-IT-
HORIZ. SCREEN
WITH SHUTTER
SHUTTER HOIST-
TRASH BIN
BY PASS FLUME'
INCLINED SCREEENS
BRUSH
ASSMEBLY
INCLINED SCREEfi
LFISH COLLECTION
TROUGH AND
TRASH RACK
STOPLOG
GUIDES
SCREEN
CLEANING
DEVICE
WATER LEVEL
Fl GJRE 11, INCLINED TRAVELING SCREEN, (2,7)
-------
passage for fish. The fish are moved up the screen, while remaining
immersed in water, and are safely deposited in the debris trough.
The screen return runs horizontally over the sluice trough. The
cleaning system is similar to the system used by the conventional
traveling screen but with lower spray pressure. This system de-
sign avoids some of the undesirable features of the conventional
vertical traveling screen, e.g., fish are guided instead of being
impinged, fish remain in water, and the fish are not subjected to
as high pressure in cleaning.2>5 Limitations to the use of this
system include higher cost than with the conventional vertical
traveling screen and need for stable water elevation.
FIXED SCREENS
Fixed screen intakes are the second most common physical screening
device used by power plants with most of them installed at smaller
and older plants. Fixed screening devices are usually considered
for intakes where suspended debris is negligible, resulting in
minimal cleaning requirement.^
The most common 'type of fixed screen is the vertical installed de-
vice located in front of the intake pumps. The mesh size, as for
any other screen, is determined by the size of debris or fish which
must be screened. The screens, generally mounted in a frame, are
installed in vertical tracks on the intake channel walls and are
usually lifted out of the water for cleaning. A fixed screen system
generally consists of two sets of screens with at least one set of
back-up screens in position at all times.
An irrigation pumping station of Universal Land Company of Pasco,
Washington, contains five, vertical fixed screens, each 2.7 m wide
with 3.2 cm opening mesh. ' Most large debris is excluded from the
intake by a chain-link fence. The pumping capacity of the station
is U.5 m^/sec with maximum velocity of 15 cm/sec. The intake device
has been in use since 1969 and no fish impingement problems have
been observed. With increased wave action, maintenance problems
result from debris and slime which clog the screens.
A variation of the fixed screen system is a vertically inclined
fixed screen. The screen may be used to guide the fish into safe
areas or bypasses. Schuler and Larson^ in 197^ tested 16 mm opening
mesh stainless steel screens installed at angles of 90, ^5, and 30
degrees to flow in a test flume. Mean velocity was 60 cm/sec. Results
with screens were generally poor. With a relatively steep angle of
30 degrees, impingement of small fish was approximately 80 percent
and other fish were guided with only marginal success.
Simple fixed screens are an economical method of screening where
suspended debris is negligible. However, if debris-free, low velocity
water is not available, operating and maintenance costs for cleaning
and handling these screens may become excessive.
35
-------
Several undesirable features of the fixed screen system include the
following:
1. Operators must be available at all times to maintain the screens.
2. There is the possibility that a heavy load of debris or fish
could completely clog the intake and perhaps cause plant shutdown
and/or screen collapse.
3. Long impingement times between cleaning periods result in total
mortality of fish.
REVOLVING DRUM SCREENS
A drum screen installation consists of a large perforated drum which
may be installed with either a vertical or a horizontal axis of
rotation (Figure 12). The horizontal drum, extended across the
stream flow, rotates slowly with its slightly exposed upper surface
moving downstream. Debris is not efficiently removed and is washed
off into the downstream side of the screen by the flow through the
screen. A spray cleaning system, similar to that of the conventional
traveling screen, can be installed to transport all fish and debris
into a sluice trough. Drum screens may be designed as impinging or
nonimpinging, depending upon the size of the fish to be separated,
the velocity of the screen, and the rate of flow in the channel.
Although revolving drum screens are used widely to screen water in
irrigation screening devices, they are seldom used at power plants
in the United States. At an irrigation intake, debris removal is not
as important as at a power plant or industrial intake.1»2,5 A major
drum screening installation of an irrigation fish bypass structure
exists on the Tehama-Colusa Irrigation Canal operated by the U. S.
Bureau of Reclamation. In this system the drum screen is placed at
an angle to guide fish to a bypass.1>2>5
There are generally two types of vertical axis drum systems in use with
U. S. water intakes. One type (Figure 13) consists of vertical drum
screens rotating in an opening in front of the pumps. This design
enables removal of debris and fish by the passing water current. The
performance of this "type depends on a strong directional passing current.
The second type involves rotation of the screens around the pump in-
take itself. This design has been supplied by a major manufacturer
for relatively low-volume power plant intakes. High-pressure and
other cleaning systems have been used, but no satisfactory method
has been developed to clean the debris from either type of screen.
Although the horizontal screen is only partially submerged, the verti-
cal revolving drum is completely submerged and could be designed to
work under fluctuating water levels. One problem with the vertical
drum system is the tendency for debris to accumulate around the drums.
Both designs could be placed at an angle to the flow to provide for
possible guiding to a bypass.
A version of the second type of vertical drum screen has been developed
by Prior Land Company of Pasco, Washington.^ The features of this
irrigation pumping intake system, such as trash barriers, fish
escape slots, and pumps, are similar to their vertical traveling
36
-------
1 1^" M.UW IU rUnK ilKUUUKt
»--«-
> ":
tf ;
t
|
= :{
f
t '
f
,_ FISH AND DEBRIS
[ COLLECTION CHAMiJEL
1- !!
FLOW OUT
1 ;:"~
LIU UJJ —
V
*— _^ || ' ,
:j=~=
^~"*^ ^\
'II
L* t \ \L
\^
"REVOLVING i
r
DRUM
FLOW IN
SCREEN
PLAN
..FISH AND DEBRIS
COLLECTION CHANNEL
SECTION A-A
FIGURE J2, REVOLVING DRUM SCREEN WITH HORIZONTAL AXIS-SCHEWTIC, (2,7)
37
-------
RIVER FLOW
D<
•
•A
D<
.TRASH BARS
PPf
" - •* *."•
PLAN
SPRAY JET PIPE
rFOR CLEANING
SCREENS
PUMPS
TRASH BARS
HIGKpWATER
LOV^WATER
SCREENS
&
TO PLANT
v:!
.-/
K
SECTION A-A
FIGURE 13. REVOLVING DRUM SCREEN WITH VERTICAL AXIS-SCHEWTIC (2,7)
-------
screen intakes. The unique feature of this system is that the water
screening function is performed by cylindrical screen cages rotating
around the vertical suction intakes of the pumps at 2 r/min. A 1.2 m
diameter, 6.^ mm mesh screen cage 7.3 m long surrounds the suction
line of each 0.8 m3/sec pump, equipped with an adjustable vertical
sparger and brush system for cleaning. The theoretical maximum
average approach velocity is 13.k cm/sec and minimum velocity is 7.3 cm/sec,
This system has been in operation for about two years. The system
had mechanical difficulties and required major overhaul during the
nonirrigation season. Because of the uniqueness of screen-cage
system design and lack of operating experience, operation and
maintenance problems, such as excessive wear of the nylon thrust
bearings of the drive mechanism and problems caused by windy condi-
tions t have been higher than desired. ' However, this design is
better suited for a large range of water elevations than are hori-
zontal and conventional rotating screens. The vertical drum screens
described here are not sufficiently developed to provide protection
for fish; and they boast only marginal effectiveness in handling
debris.
A drum screening installation has the advantages of fewer moving
parts than the conventional vertical traveling screen and economical
operation and maintenance. '5 Also, more total screen mesh can be
used as effective screen area.
2 5 28
There are also disadvantages to a drum installation: ' '
1. The drum system has a poor record of self-cleaning.
2. Side and bottom seals are often ineffective, so that fish and
debris can pass through them.
3. Since the horizontal drum screen is partially out of the water,
use of the entire screen is not achieved.
k. Unless the drums can be adjusted with the water level fluctua-
tions, they would not be considered useful in waters varying more
than a few inches in elevation.
5. Drum screening systems cost considerably more than the convention-
al intake.
Three horizontal drum screens are currently being used by the State
of California in water diversion sites for fish protection.^" The
intake volumes at these plants range from i.h nP/sec to 85 m3/sec.
In addition, this screen is being considered for possible use at
the 623 m^/sec Peripheral Canal diversion in California. This would
require several miles of 0.35 to 0.14-8 cm mesh drums. Biologists
working on the project believe that the use of finer screening for
eggs and fish larvae is impractical at this site.5° Essentially no
testing of fish diversion has been conducted on the screens to date.
However, it has been noted that salmon and steelhead larvae seem to
avoid impinging on the screens while black bass larvae impinge and
get carried over the revolving drum. A collection trough can be in-
stalled on the lee side of the drum to transport fish and debris back
39
-------
to the water body.
Drum screens are used extensively in major power plant intakes in
Europe and are highly regarded there for efficiency in water screening
and serviceability. Although European designs include several types,
none were designed from the viewpoint of preventing fish impingement
and entrainment. Hypes which are available and commonly used include
the single-en try and double-entry cup screens.
In the single-entry cup screen, the water enters at the end (side)
of the large rotating drum and passes out through screen mesh on the
periphery. This screen is limited in size to about 9 m in diameter
because of the cantilever design of the shaft support.
In the double-entry cup screen, the water enters the rotating drum
at both ends (sides) and passes out through the screen. Maximum
size is 18.3 m in diameter. Modifications are being made, e.g., in-
stalling buckets to safeguard fish. These designs require mounting
the drum screens on a structure substantially larger and more costly
than that required for conventional vertical traveling screens handling
the same intake flows. These screens are easier to maintain, have
fewer mechanical parts, and prevent carryover of debris into the
screen water system.2
ROTATING DISC SCREENS
A typical rotating disc screen is suitable only for relatively small
flows and small water.level fluctuations. This screen (Figure 1^),
a flat disc covered with screen mesh and rotating about a horizontal
axis, is set in the water channel perpendicular to the flow. As the
screen rotates, debris and impinged fish are washed into a sluice trough
by high-pressure sprays. The screen has low initial cost and, because
of few moving parts, low maintenance cost. However, it offers no
real advantage for fish protection over other screens while it incor-
porates most of their disadvantages (need for high pressure sprays,
probability of fish impingement, need for large screen structure to
limit screen approach velocities).
DOUBLE-ENTRY, SINGLE-EXIT VERTICAL TRAVELING SCREENS
The double-entry, single-exit vertical screen installation appears
similar to the conventional traveling screen but has several signifi-
cant differences. This installation draws water in through, both faces
of the traveling screen and passes it out through' one end of the
screen, thus doubling the screening area over the conventional travel-
ing screen.
One design has the screen faces mounted parallel to the intake flow
(Figure 15). In this installation, there is no fish and debris carry-
over to the pump intake, since any carryover debris will be returned
to the incoming water for recycling. Drawbacks to this type of double-
entry, single-exit screen include possible buildup of debris resulting
-------
ROTATION
SECTION A-A
A
RUBBISH
HOOD
RUBBISH.
TROUGH
MESH SCREEN
SYPHON PIPE
TO PUMPS
UNSCREENED
WATER
ELEVATION B-B
FIGURE 14, REVOLVING DISC SCREEN-SCHEWTIC ,(2,7)
-------
VERTICAL
TRAVELING
SCREENS
I
iiiiiiiiimmiiiiiiLLJiiiiumiiiiiiiiiiiimi
t t JM f t
CIRC. WATER
PUMPS
BLANK PLATE
VERTICAL TRAVELING
SCREEN
SCREEN FACE
-SPRAY SYSTEM
-TRASH TROUGH
SCREEN FACE
SECTION A-A
FIOJRE 15, DOUBLE-ENTRY, SINGLE-EXIT VERTICAL TRAVELING SCREENS-SCHEMATIC (2,7)
-------
in increased head losses and entrapment of fish.
A second type of double-entry screen installation is mounted on a
platform (Figure 16). Since there is no confining structure surround-
ing the screens, fish trap areas are avoided. In addition, cost for
this -type of installation may be less than that for the first type
of double-entry screen, as well as less than that for the conventional
vertical traveling screen.^
SINGLE-ENTRY, DOUBLE-EXIT (CENTER FLOW) TRAVELING SCREENS
In the single-entry, double-exit (center flow) traveling screens
(Figure 1?) the water enters the center of the screen and passes from
the inside to outside of the screening surface. The entire screen
surface that is immersed is thus utilized as screening area. Since
fish and debris are retained inside the screen, the possibility for
debris carryover back to the intake is eliminated. The accumulated
fish and debris are cleaned off the screen by gravity and a spray
wash into an overhead sluice trough. The advantages and disadvantages
of the single-entry screen are similar to those of the double-entry
screens.
This type screen has been used in Europe for about 30 years. The
European design (Figure 18) incorporates a modification which pro-
vides a potential increase in fish protection. The screen panels
consist of semicircular screen mesh baskets which provide increased
screening area and facilitate removal of fish. The basket panels
utilize a vertical lip along the bottom to retain debris and fish
in the basket until it rotates directly over the sluice trough. This
lip probably increases the efficiency of retaining live fish after
the panels rotate out of the water. The screening material and mesh
size varies according to the fish to be protected and the type and
size of debris to be screened.51?52
Central Power and Light Company employs this type of screen system ,
at their TOO megawatt Barney M. Davis Steam Plant in southeast Texas. -5>-?
Located on the Laguna Madre, the Davis Plant entrains and impinges
species characteristic of an estuarine environment. In addition, the
intake channel experiences an extremely heavy influx of vegetation for
up to 10 months of the year. A 0.5 mm opening square-mesh,polyester
screen was originally selected to divert this vegetation. The very
fine mesh precludes any entanglement of vegetation around the screen
wires and, therefore, increases the efficiency of screen cleaning.
Continuous rotation of the screen (0.5 to k m/sec) provides for mini-
mal head loss buildup due to clo.gging of the fine mesh screens.
Currently, both Nitex and polyester screens are being used to compare
strength and durability.
Data collected on the survival of crustacean and juvenile fish indi-
cates high survival for the former and variable survival for the
latter. An accurate evaluation of impingement survival has been
hampered by the large volume of marine grass which entangles the fish.
-------
FIGURE 16, DOUBLE-ENTRY/ SINGLE-EXIT INDEPENDENTLY SUPPORTED SCREEN, (83)
-------
CIRC. WATER PUMPS
EMERGENCY SCREEN
BYPASS GATE
VERTICAL
TRAVELING
SCREEN
INFLOW
lt\njn
V
i/---:.--|l -
V
^^
X
v
SCREEN
*• • " " * .
»•
;••
•
P
•
..•..-.-••• <• • :• • • •
V
EMERGENCY
BYPASS GA1
'- '•- x • .«
SECTION A-A
FIGURE J7. SINGLE-ENTRY/ DOUBLE-EXIT VERTICAL TRAVELING SCRSIEN-SCHEWTIC (2,7)
-------
FIGURE IS, SINGLE-EIYTRY/ DOUBLE-EXIT SCREEN (51)
-------
Separating the fish from the marine grass results in a higher mor-
tality estimate than would be expected merely from the impingement.
Likewise, "because of the difficulty in retrieving fish apart from
the vegetation, estimates of larval fish survival have not been con-
ducted at this plant.-^
With the following modifications, this type of screen may afford
increased protection for larval through adult size fish compared
to the conventional vertical traveling screen:
1. Bottom of screen panel should be modified to hold enough water
to support fish during the upward rotation of the screen from
the water surface to the overhead sluice trench.
2. Backup screen should be provided to support the fine mesh screen
which is subject to tearing when punctured.
3. Screen wash spray velocity should be adjusted to prevent descaling
and injury to fish as they are removed from the panels.
k. Intake velocity and screen speed (impingement time) should be
adjusted to provide minimal injury to fish.
5. Sluice design should afford minimal stress and injury to fish
being returned to the source water body.
This screen shares the advantage with the conventional vertical trav-
eling screen of being suitable for use in waters experiencing large
fluctuations in water level. In addition, the use of this screen is
not limited to relatively low volume intakes since the number of screens
that can be used is unlimited. For this reason, this screen may be
feasible as a backfit to existing plants using large volumes of
cooling water in a once-through cooling mode, although extensive
pump station structure alterations may be required.
PERFORATED PLATE FISH BARRIER
The perforated plate system was designed for use as a screening de-
vice in small irrigation ditches in California. The size of the
perforations vary with the minimum size of fish to be screened. The
surface of the plate is kept free of debris by a wiper bar composed
of a hardwood, metal, or synthetic material. The desired approach
velocity can be obtained by using a variation of heights, widths, and
perforation sizes. A bypass provides for diversion of fish past the
intakes.
In 19^7 E. W. Murphey-5-3 of the California Bureau of Fish Conservation
designed a perforated plate system. This plate was placed at a 32°
angle with the channel and included h- mm diameter perforations. Initial
tests performed by Wales and Murphey55 in California yielded 99 percent
efficiency in removal of fish, but no tests for survival of these fish
were run. Besides the low operating cost and high efficiency, the
initial cost of material and construction is very low in comparison
to other screening devices.
The State of California currently has a vertically-positioned perforated
-------
plate which uses a wiper mechanism to clean it of fish and debris.
The intake flow is 11.3 nP/sec. It is not known to what extent safe
fish diversion is attained.
PERFORATED PIPE SCREENS
The perforated pipe screen (Figure 19) is a pipe intake located in
the stream and positioned so that the stream flow can wash debris
downstream. The number and size of perforations in the pipe deter-
mine velocities through the perforations. In this system, low approach
velocities can be attained without significantly increasing the com-
plexity and cost of the system. Shorter pipes or larger pipe diameter
tends to produce a more uniform velocity distribution. Additions of
sleeves to the inside of the pipe may be used to produce a more even
distribution of flow.
The B.A.S.F. Wyandotte Chemical Corporation has installed a perforated
pipe intake system in the Wisconsin River at Port Edwards, Wisconsin.^
This system was designed for a water supply of 0.22 m3/sec but presently
provides 0.19 nH/sec. it consists of one k.6 m long, 0.6 m diameter
pipe perforated with 12.7 mm by 12.7 mm slots providing a ho percent
open area. The theoretical maximum average approach velocity at full
capacity is 6.U- cm/sec. The first perforated pipe was placed in a
dredged trench and silt plugged the perforations. A second perforated
pipe was installed in 1968 and has required no maintenance since in-
stallation.
A design has been proposed for the Central Columbia River1"' which
features a slotted perforated pipe intake at the bottom of the river
(see Figure 19). The system is designed to provide a water supply
of 1.58 m3/sec through two cylindrical pipes mounted approximately
0.6 m above the river bed. The perforated pipes are lj-,6 m long and
0.92 m in diameter with 9.5 mm by 38 mm rectangular slots providing
an open area of ^0 percent. The theoretical maximum average velocity
through the perforations at full capacity is approximately 15 cm/sec.
The design was based on the swimming capability of indigenous fish.
The Detroit Steel Corporation has installed a perforated pipe intake
in the Ohio River at Portsmouth, Ohio. ' Although the facility was
designed to provide a continual water supply of 5.7 m3/sec, it is
presently pumping only k.k m3/sec through two 12.2 m long, 1.2 m
diameter pipes perforated with 6.k mm by 100 mm slots with open area
of 20 percent. The theoretical maximum average approach velocity at
full capacity is about 10.^ cm/sec. Annual maintenance programs are
undertaken in which divers clean the pipes by backflushing with air
and water and repair them as necessary.
The perforated intake should be located at sufficient depth to prevent
water cavitation and at a sufficient distance from the bottom to pre-
vent intake of debris and mud. Based upon the operating experiences
of the Wyandotte Chemical Corporation and the Detroit Steel Corporation,
the system has been reliable.
-------
SURGE SUPPRESSOR
A
BACKWASH
GATE--^^
s
X
}
n
-S t
n^-
X-,
L
s
(
ID 11-
— I_-~T~. y
l-^zl*::
1
—
i
1
=3
^«
MAXIMUM FLOOD OF RECORD 114 m
CAISSON
_NORMAL HIGH WATER 107m
46cm
EXTREMEJ.OW WATER 104.5m [~ ;
61 cmTp 9 '^m ^j .'•
*•"''•' ' j '•' •''} ''-••' '
J \ ^
Q 1 A rr,-*J
PERFORATED PIPE INTAKE
120" SLOTTED STEEL PIPE
40% OPENINGS
SLOTS 9.5mm x 38,0mm
FIGURE 19, PERFORATED PIPE SYSTEM, (2,7)
-------
The perforated pipe intake has the following advantages:
1. There is flexibility in locating the structures in the water bodies.
2. There is flexibility ii size, shape, and location of perforations.
3. The intakes are relatively inexpensive.
1+. Since there are no moving parts in a perforated pipe intake, opera-
tion and maintenance are not complex.^j^7
The concept of the perforated pipe offers high potential for protecting
very small fish. Depending on the velocity of the river, the velocity
through the openings in the pipe, and size openings in the pipe, it
appears this system could significantly reduce the numbers of larval
fish entrained into a plant. A disadvantage may be possible clogging
with resultant higher velocities throughout the remainder of the pipe
and poor efficiency (reductions in the open area of the pipe). Pro-
visions for backflushing the pipes can be incorporated into the design.
RADIAL WELL INTAKES
The radial well intake (Figure 20) is a type of infiltration system
which uses natural, in-place, permeable material instead of artificially
prepared filter beds. Slotted pipes are placed horizontally in sand
or gravel beds on the bottom of the river. An installation consists
of several of these radial pipe screens, each surrounded by the per-
meable gravel pack, and the central shaft into which the pipe screens
empty. Each radial pipe screen can be back-washed separately.3
The feasibility of using a radial well intake depends primarily on
the availability of permeable substrate and reasonably clean water.
Where the appropriate geological conditions are available, operating
costs for this intake are often lower than those for conventional
wells because of lesser actual pumping head, lower maintenance costs,
and greater pumping efficiency .5°
For small-capacity intakes, it appears that the cost of the radial
well would be competitive with that for conventional intake designs.
For very large capacity intakes, however, the cost could be substantially
greater than for a conventional intake because several widely scattered
radial wells might be needed. Radial wells have been reliable in
their service history of more than 35 years. When suitable site con-
ditions are available, this system is attractive for minimizing the
environmental impact of an intake system.2
CIRCULAR WELL SCREENS
A variation of the perforated pipe concept is the circular well screen,
a cylindrically shaped screen having a continuous slot opening. This
design provides for greater hydraulic efficiency than the perforated
pipe. The slot design combines a sharp outer line of contact with a
profile that abruptly widens inwardly, providing only two points of
contact for debris.57 This feature calls for potentially less clogging
than a comparable size hole in a perforated pipe. The circular well
50
-------
PUMPS
GROUND
WATER LEVEL
VD
O
CONCRETE CAISSON ,
RIVER
' SARD AND GRAVEL
' AQUIFER v •. \
HORIZONTAL SCREEN PIPES
60m to 90m LONG
FIGURE 20, RADIAL WELL-SCHEMATIC (56)
-------
screen can be cleaned by hydraulic backflushing and is usually found
to clog at a slower rate than mesh screens.
Colorado State University in 1956 conducted extensive laboratory
tests to determine the hydraulic characteristics of well screens.5°
The tests verified the criterion of 15 cm/sec as the upper limit velo-
city through the slot to prevent rapid clogging. The tests also in-
dicated optimum combinations of screen diameters and lengths. According
to their results^multipie screens of limited length perform more effi-
ciently than single but longer screens. Table 1 shows the recommended
flow rates for single lengths of one manufacturer's circular well
screens for a range of screen diameters from 15 to 76 cm. Table 2
shows the inlet areas available for selected sizes of screen openings.
Circular well screens have been in use for many years as underground
well water screens. They are also being used throughout the United
States as municipal and industrial water supply intake screens located
in lakes and reservoirs. At least one power plant in the United States
filters raw cooling water with well screen. A circular well screen
intake was installed by the Kentucky Power Company in 1963 to screen
makeup cooling water at the 1,000 megawatt Big Sandy Plant in eastern
Kentucky.59 Eight 60.9 cm diameter screens, each 9.1 m long with 3.8mm
slot width, are used to screen the 0.6l to 1.23 m3/sec makeup cooling
water. The screens are cleaned by backflushing with air blasts
approximately once every eight-hour shift. Clogging by coal particles
initially necessitated diver cleaning. Levels of coal particles in
the Big Sandy River have declined and the diver cleaning has not been
required during the past two years. Minor clogging by slivers of ice
during the winter months has occasionally been experienced also. The
company concluded that the circular well screen intake is optimal for
this plant. No data are available regarding the degree of impingement
and entrainment of fish.
A laboratory study to determine the feasibility of protecting larval
fish using a well screen intake at the proposed Phipps Bend Nuclear
Plant on the Holston River in east Tennessee is being undertaken by
the Tennessee Valley Authority.°0 The objective of the study is to
determine to what extent larval and postlarval fish can avoid being
impinged on or entrained through small slot (0.5 to 2.0 mm) well
scroen. Fish will be exposed to a range of "river" velocities and
velocities through the screen. The success of this concept relies
completely on the ability of the fish to detect and swim away from
the screen.
Similar research was initiated by Delmarva Power and Light Company in
1976 for the purpose of developing an intake for the Summit Power
Station. ^ Approximately 30 tests of several species ranging in
length from 8 mm to 50 mm were conducted on 1 mm slot width circular
well screen. Testing will be resumed at the beginning of the 1977
larval fish season. A preliminary report on the 1976 tests is currently
being prepared.
52
-------
TABLE 1. RECOMMENDED FLOW FOR CIRCULAR WELL SCREENS (58)
TABLE
Intake
Screen
Diamete:
r(m)
Recommended Maximum
per Single Length of
m^/sec
.15 .010
.20 .017
.30 .038
.la .060
.51 .088
.61 .135
.76 .211
2. INLET AREAS FOR CIRCULAR WELL INTAKE
Flow
Screen
SCREENS (58)
(Areas in square meters per lineal meter of screen
for selected sizes of screen openings)
Screen
Diameter,
Meters
.15
.20
.30
Ai
.51
.61
.76
1.5 mm
0.21
0.27
0.28
0.35
0.33
0.39
O.U9
2.0 mm
0.25
0.32
0.33
0.^3
O.lj-2
o.ij-9
0.61
2.5 mm
0.28
0.36
0.38
O.lj-9
OA8
0.57
0.71
3.8 Tmn
0.26
0.3^
0.50
0.62
0.62
0.75
0.93
5.0 mm
0.30
0.39
0.57
0.59
0.73
0.88
1.10
6.2 mm
0.32
o.te
0.52
0.66
0.82
0.99
1.23
53
-------
HORIZONTAL TRAVELING SCREEN
The basic concept of the horizontal traveling screen is a continuously
rotating screen which provides for impingement of fish for a short
duration followed by release of the organism into a high velocity
bypass and return to the source water body downstream of the intake.
In all designs the fish are never lifted above the water surface.
Larger fish may guide along the traveling screen to the bypass or
swim directly upstream away from the screen rather than impinge on
it. The length of time a fish is impinged depends on the length of
the screen and the screen speed.
Review of intake-related literature reveals the horizontal traveling
screen to be one of the few concepts that are encouraging for pro-
tection of fish eggs and larvae. A review of the biological tests
conducted on these screens follows a brief description of several of
these prototype screens.
Six prototype horizontal traveling screens were developed by the Bureau
of Commercial Fisheries, Columbia Fisheries Program Office, at Port-
land, Oregon. In 1971, members of the Bureau of Reclamation and the
National Marine Fisheries Service developed and tested the latest
version, the Model VII. The Model VII, located in an experimental test
flume near Troy, Oregon on the Grand Ronde River, underwent fairly
extensive biological and mechanical testing until 1973, when it
ceased operation. Descriptions of these prototype installations were
presented in the Leaburg Canal feasibility study°2 and are summarized
below. The results of mechanical and biological studies on the latest
Model VII horizontal traveling screen at Troy, Oregon and evaluations
for future use have been presented in detail in several reports."2-68
The first model was constructed at the Carson National Fish Hatchery,
Carson, Washington, about 1965. ° The structure consisted of a con-
tinuous screen, resembling a conveyor belt on edge, placed at an angle
of 20 degrees with the direction of flow in a flume approximately
1.83 m wide and 1.22 m deep. A 0.31 m wide and 1.22 m deep bypass was
constructed at the downstream end of the structure. A spiral-wound,
carbon steel wire was used for the screening material. The screen
itself was 90 cm wide with 8 mm openings and a 72 percent effective
oppr area. The screen was hung on a 6.8 mm hand chain which was
supported and guided by a metal track. The track was supported on
each side and had a continuous slot in its center to allow passage
of the screen hangers. The chain was supported at each end of the
structure by a pocket sheave of 56.5 cm in diameter which was connected
to the reduction gear of 10 to 170 r/min and motor assembly. Maximum
speed attained by the chain was 1.5 m/sec. Eyebolts were welded to
the chain to connect the screen and chain. The screen was strengthened
throughout with flat metal.
The Model II screen was then designed to minimize the drag of the
screen as it traveled on its return upstream. All of Model II features
were similar to Model I except that the screen was lifted out of the
-------
water on its return upstream. The screen traveled downstream at an
angle of 20° with the flow direction and was then raised at a 22°
angle to a height of 6l cm. As the screen traveled upstream, it was
lowered at an angle of 22 back to its original position.
The Models I and II horizontal traveling screens were tested at the
Carson National Fish Hatchery, Carson, Washington. Test fish,
hatchery-reared spring Chinook salmon 9 "to 15 cm long and coho salmon
5 to 8 cm long, were used to test the models at water velocities of
about 1.0, 0.8, and 0.5 m/sec. Results of the tests indicated very
good recovery in the bypass.
Model III was installed and tested in the Maxwell Irrigation Canal
near Hermiston, Oregon, during 1966. Model III was similar to Model
II in that it was lifted out of the water on its upstream return, and
the screening material was similar to that of the earlier models.
The screen in Model III was supported by attachment to a continuous
wire rope rather than by the individually suspended hooks attached
to a chain. Rollers and track similar to the trolley-conveyor type
were used to support and guide the screen.62,66
Model IV was installed at the Bureau of Commercial Fisheries' fish
testing facility near Troy, Oregon. The upstream screen travel was
lifted free of the water as in previous models. The principle differ-
ences between Models IV and III were in the screen support and guidance
system. The screen had to be designed for flows as great as 10 times
the flows tested for Mpdel.,111. The screen was attached to move along
a suspended wire rope. »
Model V was constructed and tested in 1968 within an 8.5 m by 1.8 m
flume at the Stanfield Irrigation Canal, Umatilla River near Echo,
Oregon. Like previous models, the screen hung vertically at an angle
of 20° to the flow direction and returned upstream above water. Model
V represented a change from Model IV in the suspension system. Changes
were from tower-supported to cable suspension support structure panels
and from a continuous belt to individual panel screens. The main sus-
pension structure consisted of a single main wire support between two
end support towers on each bank of the structure. The screen was a
stiff cantilevered design of individual screen panels used to eliminate
any need for support and/or drive mechanism at the bottom of the screen.
A screen of a 13 mm stretched nylon mesh net gave a 9 mm head loss with
a velocity of 73 cm/sec. The screen deflected 97 percent to 100 percent
of the young steel head and coho salmon test fish. The self-cleaning
system was sufficient to keep all screen netting clean. The bypass
velocity was 1^0 percent of the approach velocity.
Model VI was installed in the previously described test facility at
Troy, Oregon in 1969. Model VI was similar to Model V in that a
roller and track system was used to guide and a cantilevered stiff
leg to support the screen. The major difference between Models VI and
V was that the screens were mounted in individual rectangular spring-
tensioned panels in Model VI. The panels traveled downstream across
55
-------
the river with the individual panels fully closed. As the screen
panels passed around the curve to the upstream track, they opened
to reduce the pressure drop over the screen and any overflow. The
open panel feature eliminated the need to lift the screen from the
water on its upstream travel, thus allowing a low profile structure."2
Model VII evolved from research and development of the six previous
models. This model consists of a series of continuously moving screen
panels hung vertically in a 30° to 60° triangular configuration with
the panels traveling diagonally downstream. The panels travel up-
stream parallel to the intake channel as shown in Figure 21. The
individual screen panels, like those in Model VI, are spring-tensioned
for overflow and reduction of drag. 3
Several reports referencing the results of the Model VII horizontal
traveling screen experiments have stated that probably reduction in
entrainment of larval fish and eggs could be expected. Examination
of the results of the experiments and subsequent personal communication^
indicated that the ability to reduce entrainment of small larval fish
with a horizontal traveling screen is, for the most part, speculation.
Biological testing was conducted between May and December 1972, both
on the Model VII horizontal traveling screen in Troy and in the
laboratory on a stationary screen.°3 The screen consisted of 0.7 mm
diameter galvanized wire cloth having a 2.5 mm clear opening, yielding
a 60 percent total open area.
The fish tested included four size groups of spring Chinook salmon:
170 mm, 70 mm, 35 mm, and 26 mm mean total length. Diversion efficiency
and survival (Tables 3 and h) were high for all sizes of Chinook sal-
mon tested at normal velocities of 15 cm/sec and k6 cm/sec. Fry
survival ranged from 82 percent to 100 percent for impingement dura-
tions up to 30 minutes with a velocity of U6 cm/sec and up to 60
minutes with a velocity of 15 cm/sec. Survival of sac fry diverted
at 15 cm/sec approach velocity was virtually 100 percent for impinge-
ment times of up to 60 minutes. Oxygen stress was not observed after
12 minutes of impingement. Survival of sac fry at lj-6 cm/sec was 99
percent for impingement time of 2 to 15 minutes. The major injury
symptom was internal hemorrhaging in the yolk sac and caudal peduncle
areas of fry tested at U6 cm/sec and greater velocities. The hemor-
rhaged areas showed almost complete recovery after ^8 hours.
Although the results of tests at the Troy flume were encouraging, there
was no testing of species other than salmon. Salmon species are larger
in the egg and larval stage compared to the species indigenous to
other areas of the United States.
A cooperative study by the California Department of Fish and Game,
California Department of Water Resources, U. S. Bureau of Sport
Fisheries and Wildlife, and the U. S. Bureau of Reclamation in 1972
and 1973^57^ involved laboratory testing of small mesh screen for
use on horizontal traveling screens. The purpose of the tests was to
determine the feasibility of bypassing egg, larvae, and adult striped
56
-------
SEAL
FISH AND
DEBRIS BYPASS
PANELS NORMALLY
OPEN ON BACKSIDE
PANELS IN EMERG
OPEN POSITION
(TO PASS DEBRIS
OVERLOAD)
FIGURE 21, BASIC DESIGN OF HORIZONTAL TRAVELING SCREEN, (2,7)
57
-------
TABLE 3. DIVERSION EFFICIENCY AND SURVIVAL OF SPRING CHINOOK IN RELATION
TO APPROACH VELOCITY AND LIGHT CONDITION ON THE HORIZONTAL
TRAVELING SCREEN. (63)
Normal
approach
velocity
cm/sec
15
30
70 mm Size Fingerling
Light
condition
Day
Night
Day-
Night
Number
of
tests
3
5
6
Diversion
efficiency
(percent)
98.U
97.9
91-5
Survival
(percent)
97.6
98.5
99.7
170 mm Size Fingerling
Number
of
tests
5
k
2
5
Diversion
efficiency
(percent)
99.8
98.6
99-6
99.8
Survival
(percent)
97. ^
100.0
99-7
99.9
TABLE 14-. DIVERSION EFFICIENCY AND SURVIVAL OF SPRING CHINOOK FRY IN RELATION
TO APPROACH VELOCITY AND THE DURATION OF IMPINGEMENT ON HORIZONTAL
TRAVELING SCREEN MODEL VII. (63)
Normal
approach
velocity
cm/sec
15
30
26 mm sac fry
Duration of
Impingement
(minutes)
6
30
60
2
6
15
30
60
Number
of
tests
12
11
12
9
11+
12
6
2
Diversion
efficiency
(percent)
99- ^
99-5
91.1
99.8
97.8
98.9
96.5
96.6
Survival
(percent)
100.0
100.0
99.^
98.5
99.7
99.6
90.6
39.1
35 m
Number
of
tests
--
—
—
—
9
6
2
2
m buttoned-up fry
Diversion
efficiency
(percent)
—
—
—
—
98.7
97.6
99.8
98. k
Survival
(percent)
--
—
—
—
100.0
9^.3
82.1
21.5
-------
bass past the 620 to 790 m^/sec Peripheral Canal intake located on the
Sacramento River.
The Peripheral Canal project tested the survival of striped bass eggs
impinged on a laboratory model horizontal traveling screen. Survival
ranged from 85 percent to 95 percent at velocities less than 0.3 m/sec.
At higher velocities survival was inversely related to both water velo-
city and impingement time. Survival and retention of striped bass
larvae on 0.5 mm mesh opening screens were more variable. Nearly
all larvae were recovered and survived when impinged at 7.5 cm/sec
and 30 cm/sec. However, retention and survival of larvae impinged
at 15 and 23 cm/sec ranged from kO percent to 80 percent, respectively.
Some of the variability was attributed to slight differences in sizes
of the larvae used in the experiments. Larvae become smaller in cir-
cumference during their first four or five days of life due to absorp-
tion of the yolk sac. This allowed them to pass through the screens
more easily. Larvae older than four days grow sufficiently to com-
pensate for absorption of the yolk sac. Results of the tests conducted
by the California Fish and Game personnel indicated that a screen mesh
of 0.5 mm clear opening was needed to retain 100 percent of those
larvae if.5 to 5.0 mm long. Based on these results, a screen with 1 mm
clear opening could be expected to retain 20 to 35 percent of this
size fish.
The conclusion from the tests was that the screen opening necessary
to retain all striped bass larvae would have to be no greater than
0.38 mm.™ They further concluded that "neither the technology at
hand nor that expected to be developed over the next several years
is likely to provide the capability to screen fish eggs and larvae
from a diversion of the size contemplated. Hence, the only practical
solution to protect these early development stages is to curtail di-
version when eggs and larvae are passing the intake site in greatest
abundance. Since the horizontal traveling screen and filter concepts
would require at least several additional years of intensive research
and development, with no real assurance that they could be perfected,
these concepts should be dropped from further consideration." The
horizontal traveling screen is, in fact, no longer being considered
for use at the Peripheral Canal.70
Currently, the only horizontal traveling screen known to be operating
is located at the Pacific Gas and Electric Company's Van Arsdale Dam
on the Eel River in northern California. This 9.9 m3/sec capacity
screen (Figure 22) was installed in 1972 for the purpose of diverting
migrant juvenile salmon. This screen consists of 51 panels, each 0.9 m
wide by 3.14- m high. The screen length facing the incoming flow is
18.7 m with a normal water depth ranging from 1.8 m to 3.0 m. Maximum
screen speed was 6k m/min. The screen has 9'5 mm diameter holes and
an open area of 1+9 percent. The screens are suspended, guided, and
driven at the top with a guide rail at the bottom. Power is provided
by a 30-hp electric motor driving a variable speed hydraulic pump.
Mechanical wear and maintenance problems have plagued the system, pre-
cluding continuous operation. At present, the screen is run only
59
-------
CD
\
\
\
0
SCREENED /
WATER / "
BAFFLE
FIGURE 22, PACIFIC Cv\s Ato ELECTRIC'S HORIZONTAL
TRAVELING SCREEN INSTALLATION-SmEmTIC, (7)
60
-------
infrequently to maintain the system in working order. Very little
biological testing has been possible.71j?2
A feasibility study aimed at protecting larval fish with fine mesh
screens was begun by the Tennessee Valley Authority as an outgrowth
of the evaluations of the horizontal traveling screen. The objective
of the laboratory flume study was to evaluate screening and mortality
of larval fish based on fish species and size, velocity, impingement
duration, and size of screen opening.73 Approximately 700 tests of
10 species were conducted between April through August 1976. A pre-
liminary report of the first three species indicated (Table 5) that
the 0.5 mm square-mesh opening screen was required to retain (impinge)
greater than 95 percent of striped bass 5.5 mm to 7.5 mm in total length.
This retention was reduced to approximately 30 percent by the 0.97 mm
opening screen. For the slightly larger (6 mm to 9 mm in total length)
largemouth bass, retention by the 0.97 mm and 1.3 mm opening screens
was approximately 75 and 70 percent, respectively. Seventy-five per-
cent of the smallmouth bass 10.5 mm to 15.5 mm in total length were re-
tained on the 1.3 mm opening screen.
Immediate and delayed mortality (Table 6) was variable for the sensi-
tive striped bass with best survival occurring at impingement durations
less than eight minutes. Survival for largemouth (Table 7) and small-
mouth bass was appreciably higher (greater than 90 percent for ^0 of
U2 tests of smallmoiith bass). Although the results of these tests
can be applied to a horizontal traveling screen system, other screen
support designs are being investigated for use with continuous trav-
eling fine mesh screens. A final report on TVA's fine mesh screen
study is scheduled for late 1976.
INFILTRATION BARRIER
Infiltration systems are commonly used by municipalities for water
purification. Some of these filtration intakes have been used on an
experimental basis for small-scale power plant intake systems. Bio-
logically, the concept of the infiltration intake appears to offer
much in the way of protection of larval, juvenile, and adult fish.
Some research has been conducted in this area on the feasibility of
using a high-capacity sand filter in a marine environment'^ and on
fouling control techniques.75 Two apparent drawbacks, high cost and
need for clear water, are frequently mentioned concerning continued
development of this method. A typical infiltration system is shown
in Figure 23.
The filtration process is usually preceded by a sedimentation process
to reduce the rapid clogging of the filter. A typical filter is a
fine-grain layer of sand or crushed coal supported on a bed of gravel.
Fine particles that cannot be removed by plain or chemical sedimenta-
tion are usually removed by the filtration bed; suspended particles
and bacteria adhere to the fine grains of the filter when water is
passed through the system. With the increase in particles being
trapped in the filter, the pressure difference through the filtration
61
-------
TABLE 5. RELATIONSHIP OF SCREEN MESH SIZE TO RETENTION OF STRIPED BASS,
LARGEMOUTH, AND SMALLMOUTH BASS LARVAE (73)
Mesh Size
(Clear Opening in mm)
Striped Bass
0.50
0.97
1.30
Small mouth Bass
1.30
1.80
2.51
Largemouth Bass
0.50
0.97
1.30
1.80
Average percent
entrained
1.97
67. 5^
88.83
6.27
2U.15
63 M
1.1^5
214-. 00
29.99
76.32
Number
of tests
83
57
8
13
23
9
17
26
27
1
Standard
Deviation
2.62
17 Al
13.13
21.28
30.50
2k. 66
2.11
27.03
25.01
0
Range
0
20
58
0
0
27
0
0
0
- lU.29
- 97.78
.5^-100.00
- 76.92
- 90.00
.78-100.00
- 5.71
- 78.79
- 98.77
62
-------
TABLE 6. IMMEDIATE AND DELAYED MORTALITY OF STRIPED BASS IMPINGED ON TEST SCREENS (73)
Velocity 15 cm/sec 30 cm/sec 46 cm/sec
Elapsed Time Immediate 48 hrs. Immediate 48 hrs. Immediate . *t^ hrs.
(no.tests) (Wo.tests)(wo. tests)
Test Duration
(minutes)
ON 0.5 26.93 (18) 73.72 27.53 (9) 80.09 23.43 (13) 85.22
w Range ( 0-71.9) ( 0-100) ( 0-87.5) (37.5-100) ( 0-85.7) (29.0-100)
1.0 14.64 (6) 73.77 15.73 (6) 76.33 19-29 (10) 76.13
Range (1.96-38.9) (51.0-91.7) ( 4.2-45) (45.2-94.6) ( 0-100) (53-3-100)
2.0 23.04 (6) 68.35 14.16 (6) 73.50 33.67 (9) 79.78
Range (7.7 -55.7) ( 6.7-100) ( 0-25.0) (39-0-100) ( 0.9-100) (49.6-100)
4.0 27.53 (5) 84.82 23.20 (6) 77.81 41.20 (10) 85-57
Range (7-9 -83.3) (71.1-100) ( 3.2-70.6) (34.6-100) (11.1-88.9) (51.4-100)
8.0 34.64 (5) 86.97 43.78 x (6) 90.84 67.97 (9) 93.28
Range (16.5-81.6) (64.5-100) (11.1-79-8) (77-3-100) (25.0-98.5) (82.1-100)
16.0 70.64 (6) 97.07 85.00 (6) 100.00 96.85 (10) 100.00
Range (29.4-95.8) (94.1-100) (64.9-100) (100-100) (70.0-100) ( 100-100)
-------
TABLE 7. IMMEDIATE AND DELAYED MORTAL!TY OF LARGEMOUTH BASS IMPINGED ON TEST SCREENS (73)
-Average Percent Mortality
Velocity 15 cm/'sec 30 cm/sec 46 cm/sec
Elapsed Time Immediate 48 hrs. Immediate 48 hrs. Immediate 48 hrs.
(No. tests) (No. tests) (No. tests)
Test Duration
(minutes)
0.5
1.0
2.0
4.0
8.0
16.0
Range
Range
Range
Range
Range
Range
3.27 (4) 7.57
(0-11.1) (2.0-15.0)
2.86 (4) 10.1*
(0-6.9) (1.7-22.7)
1.45 (3) 4.89
(0-4.3) (0-13.0)
2.22 (3) 13.08
(0-3.6) (3.9-24.6)
3.22 (3) 16.17
(0-6.9) (2.8-41.4)
8.90 (3) 21.49
(6.3-H.8) (11.8-37.5)
6.50 (5) 3^.35
(0-25) (3.5-55.0)
6.74 (5) 31.67
(0-16.9) (1.5-77.5)
11.42 (6) 31.41
(2.1-27.3) (6.3-71.4)
4.72 (5) 40.51
(o-io.o) (3.3-60.0)
19.70 (5) 38.94
(0-77.4) (5.5-83.9)
33.34 (4) 45.70
(4.0-95.5) (4.0-95.5)
19.80 (9) 37.30
(0-75.0) '.o-ioo)
3.25 (3) 27,32
(0-5.4) (13.5-35-8)
4.89 (2) 11.96
(1.4-8.3) (7.2-16.7)
8.62 (3) 82.57
(6.0-10.5) (66.8-100)
6.48 (2) 81.48
(5.6-83.9) (70.4-92.6)
40.86 (3) 75.04
(12.5-76.2) (55.9-95.2)
-------
PUMP STRUCTURE
•PUMP STRUCTURE
DISTRIBUTION
STRUCTURE
FILTER
MATERIAL
LOW WATER
FIGURE 23, INFILTRATION FILTER BED-SCHEMATIC (47)
65
-------
bed increases. When the pressure difference is excessive, the filter
will be backwashed to remove the trapped particles. The filter may
be divided into sections which can be individually backwashed to en-
sure continuously available water supply. After the water is drawn
through layer filters, it is drawn into the intake by various systems,
such as perforated pipes and circular well screens.7^»'5
The operational history of these systems includes the experiences of
several installations. The city of Kennewick, Washington installed
a filtration system on the Columbia Eiver to provide a high quality
water supply. The system was plagued with many problems of rapid
clogging and was replaced by a radial well system. 7
A filtration installation utilizing a coarse grade gravel backfill was
installed in 196? by the Oregon Fish Commission for the Elk River
Salmon Hatchery. Backflushing was required to keep fine particles
from clogging this system. New filter beds which were recently added
are composed of a finer-grade gravel backfill with 35 cm diameter circular
well screen underdrains. Although the new system worked well, it
did not yield the capacity for which it was designed and a larger
capacity system has now been designed.'
In California, several successful infiltration beds are in use at
irrigation diversions. Two of these are discussed by Menchen.?"
The Merced Irrigation District (MID) of California built six "Gabion
fish screens" which are designed to screen 0.57 to 1.7 m^/sec of water.
The Gabion screen consists of a thick wire cage filled with cobble and
extends across the river to form a leaky dam. A perforated pipe,
located beneath the Gabion screen, is covered with 15 to 20 cm of
river run gravel. This 9«75 m long, 0.91 m diameter pipe has 33 per-
cent open area and passes O.lj-5 m^/sec of water with 0.3 m of head.
Most of the water enters through the pipe, but some water also passes
through the porous cobble-filled Gabion screen. An emergency control
structure was installed to bypass the perforated pipe in case it should
become clogged. In the 3 years of operation the screens have re-
quired very little maintenance, and no clogging problems have occurred.
Therefore, provisions for backflushing have not been incorporated into
the design. However, water and gravel were relatively clear and un-
silted in this case, and these results may not be applicable in other
less clean environments.
An infiltration system is used to provide makeup water to the Montour
Power Plant of the Pennsylvania Power and Light Company. ' One of three
units was in service in 1971. The unit was designed for 1.0 m3/sec
but now provides only 0.71 m^/sec. The finer-graded top material in
the filter bed was washed away during the first winter of operation
and was replaced with a O.U6 m layer of 19 mm diameter stone.
The major operational problem of the Montour system has been clogging
of the bed with algae and fine particles. After several hours of
operation, several feet of water pressure differential develops between
the river and the pump house. The frequent backwashing which has been
66
-------
necessary Increases the natural turbidity of the river. The unit was de-
signed for a water fluid backwash, but because of unsatisfactory conditions,
air lines were installed to aid in backwashing. In addition, the
top 1 m of filter material has been replaced with clean material
which is contained in baskets for stability.^7
The feasibility of using a high capacity sand filter in a marine
environment has been studied. Stober et al.?^ and Strandberg75
discuss the biological model studies, fouling control techniques,
and the design concepts for this method. They proposed the use of
the sand filter to alleviate damage to sac fry and conducted filtra-
tion studies of the proposal near Kiket Island, Puget Sound, Washington
in 1972. The system consisted of seven filter units, with a total
surface area of 11,000 m^ required for the design capacity. The
design infiltration velocity was ^,100 to 6,800 cm3/sec/m2. A cross-
section of the proposed filter unit is shown in Figure 25. Fifty
filter units, 1.5 m wide and 18.3 m long made up the filter bed in
one filter section. The filter bed was composed of both a crushed
and graded anthracite coal bed supported by a layer of gravel.7^
Filter flow velocities of 0.305 to 0.6l cm/sec, which are acceptable
filtration rates of 3,^00 to 6,800 cm3/sec/m2, did not affect the lateral
and vertical mobility of juvenile and larger fish above the filter
surface.75 These velocities were tested with an anthracite and four
gravel layers.
The high capacity rapid sand filter has pany attractive features for
screening water intakes of power plants:^7>'^>75
1. Low sink flow rate (approach velocity) which does not affect the
mobility of weak-swimming fish.
2. Flat filter surface which eliminates obstructions or traps for
fish and small organisms.
3. Low profile and space requirements.
However, the sand filter system has some undesirable features also.
1. May be less reliable than other screen systems because of clogging.
2. May require more maintenance for infiltration screening because of the
backwashing procedure and the necesslty^for keeping the entrance
channel and filter bed in condition.^s^'
67
-------
SECTION 7
FISH REMOVAL SYSTEMS
This section presents a review of fish pumps and fish elevators
which are designed to physically remove fish which become entrapped
in intake structure screen wells.
FISH PUMP
Experimental fish pumps are currently being used to alleviate fish
impingement at several power plants in the United States. In 1952,
a fish run caused the traveling screens to collapse at the Contra
Costa Steam Plant of the Pacific Gas and Electric Company.77 The
company subsequently installed a fish removal system. The device,
much like a closed dustpan (Figure 2k), was placed even with the
base of the curtain wall in front of the screen. Trash pumps (volute
type) are used to draw the fish into the collector which transports
them to the discharge area. The device has been running continuously
with relatively few mechanical problems since it was installed. A
survival of 98 percent was reported at the plant with fish sizes
ranging up to 35.5 cm.
A more recent version of the fish pump is being tested at Detroit
Edison's Monroe plant. Fish are removed from the intake screen face
by a dustpan collector, similar to the one at Contra Costa. This
large 20 cm volute pump makes it possible for a k2 cm northern pike
to pass unharmed through the system. Apparently the fish pump has
significantly reduced the mortality rates. The initial tests were
so encouraging that six additional collectors were to be installed
at the Monroe plant. The fish pump (Figure 25) was placed in opera-_
tion in September 1973 and resulted in 80 percent survival of fish.'
Modification to the fish collector, including increasing the open
area for fish entry and the addition of lights to attract the fish
toward the dustpan, increased efficiency; however, results are stiU
preliminary. The company believes that the fish pump is the best
available technology for their situation.
A fish pump has been intermittently in operation at TVA's Browns
Ferry Nuclear Plant since March 1975.79 The 15 cm pump is connected
by plastic and metal pipe to the dustpan-shaped fish collector located
about mid-depth in the screen well in front of one screen. As designed,
the fish enter the intake well and swim toward the surface behind the
curtain wall apparently to avoid the high velocity water between the
opening and the lower part of the screen. In so doing, they encounter
68
-------
PUMP SUCTION PIPING
FISH COLLECTORS
TRAVELING SCREENS
FIGURE 24, FISH DUST-PAN COLLECTORS USED WITH FISH pur-ps, (7)
-------
-25cm DISCHARGE PIPE TO POOL
-FAIRBANKS MORSE VOLUTE PUMP
r\
-BALL VALVE
\
TU
-20cm INLET PIPE
A FLOOR LEVEL
•TRASH BARS
NORMAL WATER LEVEL
-CONCRETE SKIMMER WALL
BARRIER SCREENS
D D
FISH COLLECTING .PAN
TRAVELING SCREEN
-< WATER FLOW
ELEVATION VIEW
FIGURE 25, SCREF.NWELL SHOWING FISH COLLECTOR SYSTEM, (7)
70
-------
the fish collector and are pulled up through the 15 cm diameter pipe,
through the bladeless impeller pump, to a holding tank (where they
are held and observed 2k hours to determine delayed mortality), and
returned to the reservoir. The pumping success is denoted as the ratio
of fish pumped of the sum of those impinged on the screen plus those
pumped. After mortality of the impinged fish (assumed to "be 100 per-
cent) and the pumped fish are factored together, a net savings in
numbers of fish from the screen well is determined. To date, during
limited testing in spring-summer 1975 > the Browns Ferry fish pump
has shown a U8 percent reduction in total number of impinged fish
from the test screen well. Immediate and delayed mortality reduced
the overall savings to 27 percent. Testing will be resumed at the
startup of the plant, which has been shut down since March 1975.^9
Fish pumps have also been tested experimentally in California at the
Huntington Beach Generating Station and the El Segundo Generating
Station in conjunction with velocity capped intakes. The effective-
ness of the fish pumps in removing the trapped fish was limited be-
cause the fish did not concentrate in the quiet zones where the pump
was located.
VERTICAL TRAVELING FISH BASKET COLLECTOR
This scoop-shaped device is designed to travel vertically along the
upstream side of a stationary barrier system located perpendicular
to flow. Fish and water are carried out of the canal or screen well
and spilled into a bypass trough. The prototype model tested at the
secondary louver canal at Tracy, California, was 6.1 m by 2.1 m by
0.9 m. Evaluation was aimed primarily at mechanical performance.
Biological studies were limited to visual observation of the effects
of the system on juvenile threadfin shad and striped bass. It was
found that "few of the impinged fish were injured in the transfer.. .'.'8°
About one percent of the 10,000 threadfin shad were estimated to have
been maimed by the rubber scraper mounted on the collection basket.
71
-------
SECTION 8
SUMMARY AND DISCUSSION
The use of barriers and fish guidance technologies to block or direct
the movement of fish has a long history. Research in this area has
been conducted for many years for the protection of many coastal anad-
romous species. Until recently, however, the designs for power plant
cooling water intakes have generally not included provisions for the
protection of aquatic life. With the enactment of Public Law 92-500
and the 1972 amendments which require "best technology available for
minimizing adverse environmental impact" at cooling water intakes,
increased attention is currently being focused on fish protection in
the design and location of power plant intakes.
Several areas of intake-related research have arisen or intensified
as the result of this legislation:
1. Impact assessment of impingement and entrainment of aquatic life
at existing power plant intakes.
2. Selection of most favorable sites for new power plants and intakes.
3. Development of intake screening systems for new plants that will
reflect "best technology available."
k. Development of fish impingement and entrainment mitigative devices
for modifying existing intakes which may not meet "best technology
available."
Power plant and intake siting is among the best means for minimizing
fish losses at cooling water intakes. However, the selection of most
favorable sites is normally complicated by several factors, such as
area geology, accessibility to location, relative location with
respect to critical system load areas, cost constraints, etc. An
additional problem is that of quantitatively sampling the biota of
an area and predicting the amount of removal and the impact of that
removal on the remaining biotic community. In a river situation
where many species are transient over areas several miles long
during spawning migrations, the entire river may be unfavorable
for part of the year. During the subsequent period in which larval
fish and eggs of many species are transported with the river
currents, the entire river may be considered productive area.
Further, seasonal or diurnal movement of fish from shallow to deep
water may preclude favoring deep water intakes over shallow water
intakes in some situations.
72
-------
Another plant siting enigma can arise in the choice of an unproductive
body of water which may be ecologically depressed because of pollu-
tant stresses but which may be capable of renewal given a reduction or eli-
mination of input of the pollutants. In this case, the potential for
that water body should be evaluated and compared with other unstressed
or less-stressed sites.
INTAKE DESIGN
The three general types of intake configurations include: (l) approach
channel, (2) off-shore conduit, and (3) shoreline or bankside. A
potential for fish impingement and entrainment exists in all three
designs. Hanking them for potential harm is difficult because im-
pacts among plants are usually not directly comparable. Many varia-
bles may contribute to the number of fish lost at a power plant intake,
including the following:
1. Water velocities throughout the intake system.
2. Flow patterns and eddy currents.
3. Size of the intake structure.
k. Volume of water taken in.
5. Morphometric characteristics of the intake basin.
6. Turbidity.
7. Water temperature patterns.
8. Type of source water body: marine, freshwater, river reservoir, lake.
9. Fluctuation in the water level.
10. Presence or absence of skimmer wall and underwater deflection dams.
11. Fish species characteristic of the area.
12. Standing crop of fishes subject to impingement and entrainment.
The approach channel intake, in conjunction with conventional vertical
traveling screens, may create a trapping effect for fish. The presence
of a skimmer wall at the entrance of the channel, coupled with high
velocities, may increase this entrapment effect. Several offshore
conduit intakes with high entrance velocities have experienced prob-
lems with large numbers of fish entrained into the conduit. Conven-
tional vertical traveling screens mounted in separate wells along the
shoreline have also experienced high rates of fish impingement and en-
trainment.
Examples of modifications to each of these basic designs exist in which
the impingement of fish has been significantly reduced. These modi-
fications include removal of screen well partitions and installation
of behavioral barriers, moving screens, and fish removal systems. The
channel is necessary for the optimum use of a louver barrier or hori-
zontal traveling screen. The velocity cap has substantially reduced
fish losses at offshore intakes. Elimination of separate screen wells
provides for increased lateral escape from the shoreline intake.
None of the three intake configurations appears to offer any advantage
for larval fish protection, apart from their location away from areas
of high larval fish density. A few concepts have been proposed for
73
-------
new and existing intakes which may provide for larval fish protection.
These concepts generally include either active or passive screening.
The former usually includes impinging the fish on a continuously
rotating (horizontal or vertical) fine mesh screen for a short dura-
tion and returning them back to the source water body via a bypass
or sluice. Passive screening involves a low intake velocity (< 15
cm/sec) through a permeable substrate or small opening conduit from
which the larval fish must be capable of swimming away to avoid im-
pingement or entrainment.
BEHAVIORAL BARRIERS
In the diversion of juvenile and larger fish past large-volume water
intakes, most behavioral barriers have not shown much promise. Of
all the barriers tested, louvers appear to have the best record of
fish diversion and may be capable of diverting small post-larval
fish. However, behavioral barriers have not shown successful guidance
of larval fish. For this reason, they should be considered only
for existing large-volume intakes where cost constraints prohibit
modifications for larval fish protection. In the design of new plant
intakes, consideration should be given to the protection of larval
fish as well as juvenile and larger fish.
The effectiveness of all the behavioral barriers can be expected to
vary according to the species and size of fish. It is important to
evaluate each barrier based on the species to be diverted at each in-
take. In this regard, special behavioral or physiological character-
istics may influence the feasibility of the device. For example, in
some areas of the Southeast, from 50 to 98 percent of the fish im-
pinged at power plants are clupeid species, of which threadfin shad
constitute a large percentage.°1 The annual impingement cycle shows
that the majority of the fish are entrapped during the late winter
when the water temperature is lowest. During this period, moribund
threadfin shad can often be seen swimming in a jerky, uncoordinated
manner. It is at this time that these moribund shad are copiously
impinged. Since the fish are in a severely stressed condition, in-
capable of swimming against the intake water current, the installation
of a behavioral barrier probably would have little or no effect on
that species. Careful consideration (which may include extensive
laboratory testing) of the many species and physical factors which
affect impingement should precede the decision to install a fish
barrier. Congleton, 2 describing the many variables associated with
fish impingement, expressed the need for controlled laboratory testing
of the fish's responses to both mechanical screens and behavioral
barriers prior to field installation of full-scale devices.
PHYSICAL SCREENING BARRIERS
The use of physical screening barriers to reduce fish losses at water
intakes is promising. As discussed earlier, methods have not yet been
-------
devised to reduce the entrainment of smaller larval fish at large-
volume plants already in existence and having vertical traveling
screens. However, in the design of new power plants or other water
use facilities, particularly lower volume intakes (less than 8.5
m3/sec), physical screens are available which offer substantial
reductions in fish losses over conventional vertical traveling
screens having 9.5 mm mesh screens. The applicability of each screen
is highly dependent on site-specific characteristics. Special con-
ditions imposed on several of the devices include the following:
1. Stable water levels (horizontal traveling screen, revolving drum
screens).
2. Clean substrate (infiltration beds and dikes).
3. Low velocity (perforated pipe, circular well screen).
k. Backflushing provisions (perforated pipe, circular well screen).
5. Ice-free condition (horizontal traveling screen, revolving drum
screens).
The mechanical screens offering the greatest protection for the
smallest size fish appear to be the infiltration beds; circular well
screen; perforated pipe; horizontal traveling screen; and single-
entry, double-exit screen or center flow screens. The first three
are attractive by virtue of their lack of moving parts but may present
possible clogging problems. The horizontal traveling screen requires
many moving parts and to date has no demonstrated mechanical reliabil-
ity. However, given a reliably operating screen, the horizontal
traveling screen probably would provide safe diversion of larval as
well as postlarval fish.
The addition of fish troughs to conventional traveling screens has
resulted in a high degree of success for increasing survival of im-
pingeable size fish. However, without any reduction in screen opening
size, larval and small post-larval fish entrainment remains the same.
Incorporating fine mesh screens into this design may result in an
increased number of fish being safely returned to the source water.
FISH PUMPS AND ELEVATORS
Fish pumps have been used with varying success for juvenile through
adult fish, but probably offer little or no reduction in larval fish
losses. The fish elevator concept has not been used as a mitigative
device at power plant intakes.
75
-------
REFERENCES
1. Maxwell, W. A. Fish Diversion for Electrical Generating Station
Cooling Systems, A State-of-the-Art Report. Southern Nuclear
Department, Engineering Consulting Division, NUS Corporation.
Dunedin, Florida. March 1973. 78 p.
2. Development Document for Proposed Best Technology Available for
Minimizing Adverse. Environmental Impact of Cooling Water Intake
Structures. U. S. Environmental Protection Agency. Washington,
D. C. EPA 1*1)0/1-7 V015. December 1973. 175 p.
3. Sonnichsen, John C., Jr., Bruce W. Bentley, George F. Bailey, and
Roy E. Nakatani. A Review of Thermal Power Plant Intake Structure
Designs and Related Environmental Considerations. Hanford
Engineering Development Laboratory. Richland, Washington. May
1973. 77 p. plus appendixes.
k. Lake Michigan Intakes: Report on the Best Technology Available.
Lake Michigan Cooling Water Intake Technical Committee. August
1973. ^-2 p. plus appendixes.
5. Riesbol, H. S. and R. J. L. Gear. Application of Mechanical
Systems to Alleviation of Intake Entrapment Problem. In: Pro-
ceedings of the Atomic and Industrial Forum and the U. S. Department
of Interior on Engineering Aspects on Siting and Operating Power
Plants. February 1973. ?1 p.
6. Mayo, Ronald D., William T. James, and James. L. Congleton. A
Rational Approach to the Design of Power Plant Intake Fish Screens
Using Both Physical and Behavioral Screening Methods. Technical
Reprint No. 15. Kramer, Chin and Mayo, Consulting Engineers. 1973-
7. Sonnichsen, J. C., W. E. Farr, and H. S. Riesbol. Fish Protective
Devices: A Compilation of Recent Designs, Concepts, and Operating
Experience of Water Intakes Used in the United States. Hanford
Engineering Development Laboratory. Richland, Washington. Energy
Research and Development Administration. HEDL-TME 75-38 UC-79-
July 1975. 86 p.
8. TVA Impingement Monitoring Reports. Division of Forestry, Fisheries,
and Wildlife Development, Tennessee Valley Authority. Norris,
Tennessee. June 1976.
76
-------
9. Downs, Dallas I. and Kenneth R. Meddock. Engineering Application
of Fish Behavior Studies in the Design of Intake Systems for
Coastal Generating Stations. Presented at the American Society
of Civil Engineers National Water Resources Conference, January
21-25, 197^.
10. Personal communication. Thomas Edwards, Duke Power Company,
Charlotte, North Carolina.
11. Edwards, T. J., W. H. Hunt, L. E. Miller, and J. J. Sevic. Fish
Impingement at Four Duke Power Company Steam Generating Facilities.
Duke Power Company. Charlotte, North Carolina.
12. Maxfield, Galen H. , Kenneth L. Liscom, and Robert H. Lander.
Leading Adult Squawfish ( Ptychochei lus Oresonensis) Within an
Electric Field. U. S. Fish and Wildlife Service. Special Scientific
Report: Fisheries No. 298. April 1959-
13. Holmes, H. B. History, Development^ and Problems of Electric Fish
Screens. Fish and Wildlife Service, U. S. Department of Interior.
Special Scientific Report: Fisheries No. 53. June 19^8.
1^. Trefethen, Parker S. Exploratory Experiments in Guiding Salmon
Fingerlings by a Narrow D. C8 Electric Field. U. S. Fish and
Wildlife Service. Special Scientific Report: Fisheries No. 158.
June 1955. ^2 p.
15. Hymen, A. M. , W. H. Mowbray, and S. B. Saila. The Effects of
Two Electrical Barriers on the Entrainment of Fish at a Freshwater
Nuclear Power Plant. Symposium by Fisheries and Energy Production.
16. Personal communication. Dr. Saul Saila, University of Rhode Island,
Kingston, Rhode Island.
17. Personal communication. Terrance Virnig, Northern Indiana Public
Service Company, Michigan City, Indiana.
18. Burner, C. J. and H. L. Moore. Attempts to Guide Small Fish with
Underwater Sound. U. S. Fish and Wildlife Service. Special
Scientific Report: Fisheries No. k03. February 1962. 30 p.
19. Vanderwalker, J. G. Response of Salmonoids to Low Frequency
Sound. Marine Bio Acoustics. Volume 2: p. ^5-58. W. N. Lavolga,
Editor. Pergammon Press. 1966.
20. Ristroph, J. D. A Free Ride for Fish. Virginia Electric and
Power Company- Richmond, Virginia.
21. Schuler, V. J. and L. E. Larson. Experimental Studies Evaluating
Aspects of Fish Behavior as Parameters in the Design of Generating
Station Systems. Presented at the meeting of the American Society
of Civil Engineers, Water Resources Engineering Program held at
Los Angeles, California. January
77
-------
22. Fields, P. E. Migrant Salmon Light-Guiding Studies at Columbia
River Dam. Third Progress Report on Fisheries Engineering Research
Program. U. S. Army Corps of Engineers. 1966. 21 p.
23. Bibko, P. N., L. Wirtenan, and P. E. Kueser. Preliminary Studies
on the Effects of Air Bubbles and Intense Illumination on the
Swimming Behavior of the Striped Bass (Morone Saxitalis) and the
Gizzard Shad (Porosoma Apedianum). In: Entrainment aria. Intake
Screening, Proceedings of the Second Entrainment and Intake
Screening Workshop. Report No. 15: 293-3C4. February 1973.
2k. Personal communication. John Malaric, Detroit Edison Power
Company, Detroit, Michigan.
25. Personal communication. Edward Neuman, Wisconsin Public Service
Corporation, Green Bay, Wisconsin.
26. Brett, J. R. and D. MacKinnon. Preliminary Experiments Using
Lights and Bubbles to Deflect Migrating Young Salmon. Journal
of the Fisheries Research Board of Canada. 10(8): 51»-8-559. 1953.
27. Bates, D. W. and J. G. Vanderwalker. Exploratory Experiments on
the Deflection of Juvenile Salmon by Means of Water and Air Jets.
Fish Passage Research Program. U. S. Bureau of Commercial
Fisheries. Seattle, Washington. 19&9. H P»
28. Smith, Keith A. Air Curtain Fishing for Maine Sardines. Commer-
cial Fisheries Review. Vol. 23(3).
29. Imamura, Y. and M. Ogura. Study on the Fish-Gathering Effects of
Air Curtains. Journal of the Tokyo University of Fisheries.
Vol. 1*5, No. 2.
30. Bell, Milo C. Fisheries Handbook of Engineering Requirement and
Biological Criteria. U. S. Army Corps of Engineers. Portland,
Oregon. February 1973.
31. Alevras, Ronald A. Status of Air Bubble Fish Protection System
at Indian Point Station on the Hudson River. Consolidated Edison
Company. In: Entrainment and Intake Screening, Proceedings of the
Second Entrainment and Intake Screening Workshop. Report No. 15:
289-291. February 1973-
32. Personal communication. Harold E. Pierce, Consolidated Edison
Company of New York, New York, New York.
33. Kupfer, George A. and William G. Gordon. An Evaluation of the
Air Bubble Curtain as a Barrier to Alewives. Commercial Fisheries
Review. Vol. 28, No. 9. September 1966.
3^. Personal communication. Richard Fitz, Tennessee Valley Authority,
Norris, Tennessee.
78
-------
35. Arkansas Power and Light Company. Biological Evaluation of Air
Curtain at Arkansas Nuclear One-Unit 1. Little Rock, Arkansas.
February 1976.
36. Grotbeck, Lawrence M. Evaluation of an Air Curtain as a Fish
Deterrent Device at the Prairie Island Nuclear Generating Plant
Cooling Water Intake. Northern States Power Company. St. Paul,
Minnesota . 1976 .
37. Brett, J. P. and D. F. Olderdice. Research on Guiding Young
Salmon at Two British Columbia Field Stations. Fisheries Research
Board of Canada, Bulletin 117. 1958.
38. Fields, P. E., G. L. Finger, and L. A. Verhoeven. The Use of a
Chain Barrier to Guide Young Salmon. University of Washington,
School of Fisheries. Seattle, Washington. Technical Report No. 1.
39. Fields, P. E., G. L. Finger, R. J. Adkins, R. E. Carney, and R.
Pyke. A Factorial Study of the Response of Steelhead Trout,
Chinook and Silver Salmon Fingerlings to Chain Barriers in
Moving Water. School of Fisheries, University of Washington.
Report No. 13. June 1955.
kO. Hyde, H. C. Fish Collection Facilities, Louver Slat Spacing Tests
at Tracy Fish Collecting Facility. State of California. Office
Report. The Resources Agency. Department of Water Resources,
Delta Fish Protective Facility. January 1967.
iH. Bates, D. W., 0. Logan, and E. A. Personen. Efficiency Evaluation,
Tracy Fish Collecting Facility, Central Valley Project, California.
U. S. Department of the Interior, Fish and Wildlife Service, Seattle,
Washington and Bureau of Reclamation, Region 2, Sacramento,
California. 1960. 70 p. plus appendixes.
k2. Bates, D. W. and Russell Vinsonhaler. Use of Louvers for Guiding
Fish. Transactions of the American Fisheries Society. Eighty-Sixth
Annual Meeting. Toronto, Ontario, Canada. 1956. p. 38-57
^3. Bates, Daniel W. and Stanley G. Jewett, Jr. Louver Efficiency in
Deflecting Downstream Migrant Steelhead. Transactions of the
American Fisheries Society. 90: 336-337. 1961.
Ml-. Ducharme, L. J. A. An Application of Louver Deflectors for Guiding
Atlantic Salmon. (Salmo salar) Smolts from Power Turbines. Journal
of the Fisheries Research Board of Canada. 29: 1397 -I^OU. 1972.
U5. Interagency Ecological Study for the San Joaquin Estuary. Calif-
ornia Department of Fish and Game. California Department of Water
Resources. U. S. Bureau of Sport Fisheries and Wildlife. U. S.
Bureau of Reclamation. 1973.
79
-------
k6. Interagency Ecological Study for the San Joaquin Estuary. Califor-
nia Department of Fish and Game. California Department of Water
Resources. U. S. Fish and Wildlife Service. U. S. Bureau of
Reclamation. 197*1-.
k7. Schreiber, D. L., C. D. Becker, and J. J. Fuquay. Appraisal of
Water Intake Systems on the Central Columbia River. Washington
Public Power Supply System. Richland, Washington. March 1973.
k&. Memorandum. Letter from J. D. Ristroph, Executive Manager
Environmental Services, Virginia Electric and Power Company,
Richmond, Virginia to R. S. Thorsell, Edison Electric Institute.
April 25, 197^.
it-9. Water Screening Without Fish Entrapment in Virginia. ASCE Civil
Engineering Conference. 1975.
50. Personal communication. J. Robinson, The Resources Agency,
Department of Fish and Game, State of California, Sacramento,
California.
51. Passavant Corporation. Passavant Screening Equipment. Bulletin
1002. Birmingham, Alabama. January 1976.
52. Personal communication. Kenneth R. Siddle, Industrial Sales
Manager, Water Division, Passavant Corporation, Birmingham, Alabama.
53. Personal communication. Frank Mosely, Central Power and Light
Company, Corpus Christi, Texas.
5^. Personal communication. Scott Murray, Central Power and Light
Company, Corpus Christi, Texas.
55. Wales, J. H., E. W. Murphey, and John Handley. Perforated Plate
Fish Screens. California Fish and Game. 36(4): 392-403. 1950.
56. The Ranney Company, Division of Layne-New York Company. Ranney
Water Collector Systems. Westerville, Ohio. November 1975-
57. Personal communication. Johnson Division, Universal Oil Products
Company, St. Paul, Minnesota. March 1972.
58. Johnson Division, Universal Oil Products Company. Johnson Well Screens
Modernize Water Intake Design. Bulletin 1071- St. Paul, Minnesota. 1972.
59. Personal communication. W. G. Mathews, Big Sandy Plant, Kentucky
Power Company, Louisa, Kentucky.
60. Personal communication. Intake Research and Development Program
Task Force, Tennessee Valley Authority, Chattanooga, Tennessee.
6l. Personal communication. John Miller, Delmarva Power and Light
Company, Wilmington, Delaware.
80
-------
62. Eugene Water and Electric Board, Eugene, Oregon. Traveling Fish
Screen, Leaburg Canal Feasibility Report. Prepared by Cornell,
Howland, Hayes and Merryfield, Corvallis, Oregon. January 1971.
39 P.
63. Prentice, Earl F. and F. J. Ossiander. Fish Diversion Systems
and Biological Investigation of Horizontal Traveling Screen,
Model VII. In: Entrainment and Intake Screening, Proceedings of
the Second Entrainment and Intake Screening Workshop. Report
No. 15: 205-2lU. February 1973.
6k. Farr, W. E. and E. F. Prentice. Mechanical Operation of Horizontal
Traveling Screen Model VII. In: Entrainment and Intake Screening.
Proceedings of the Second Entrainment and Intake Screening Workshop.
Report No. 15: 215-222. February 1973.
65. Bates, D. W. Diversion and Collection of Juvenile Fish with
Traveling Screens. U. S. Department of the Interior. Washington,
D. C. Fishery Leaflet 633. March 1970.
66. Bates, D. W. and J. G. Vanderwalker. Preliminary Designs of
Traveling Screens to Collect Juvenile Fish. U. S. Department of
the Interior. Washington, D. C. Special Scientific Report:
Fisheries No. 608. July 1970.
67. Bates, D. W., E. W. Murphey, and M. G. Beam. Traveling Screen for
Removal of Debris from Rivers. U. S. Department of Commerce,
National Marine Fisheries Service. Special Scientific Report:
Fisheries No. 6^5. 1971.
68. Memorandum. D. A. Tomljanovich to C. J. Chance. Evaluation of a
Horizontal Traveling Screen. Tennessee Valley Authority. July 1975.
69. Personal communication. Earl F. Prentice, Bureau of Reclamation,
Seattle, Washington.
70. -Personal communication. Bill Heubach, The Resources Agency,
Department of Fish and Game, State of California, Sacramento,
California.
71. Strassburger, A. G. Horizontal Traveling Fish Screen. Pacific
Gas and Electric Company. Presented at the Ij-lst meeting of the
Hydraulic Power Conference, North Carolina, April 25-27, 1972.
72. Personal communication. Doug Green, Pacific Gas and Electric
Company, San Francisco, California.
73. Tomljanovich, D. A., John H. Heuer, and Clyde W. Voigtlander
Preliminary Analysis of Studies of Fine Mesh Screening of Larval
Fish. Division of Forestry, Fisheries, and Wildlife Development.
Tennessee Valley Authority. Norris, Tennessee. May 1976.
81
-------
?U. Stober, Q. J., C. H. Hanson, and P. B. Swierkowski. A High
Capacity Sand Filter for Thermal Power Plant Cooling Water Intakes,
Part I: Model Studies and Fouling Control Techniques. In:
Entrainment and Intake Screening, Proceedings of the Second Entrap-
ment and Intake Screening Workshop. Report No. 15: 317-33^. Feb-
ruary 1973.
75. Strandberg, H. V. A High Capacity Sand Filter for Thermal Power
Plant Cooling Water Intakes, Part II: Design Concept. In:
Entrainment and Intake Screening, Proceedings of the Second
Entrainment and Intake Screening Workshop. Report No. 15: 335-3^3.
February 1973.
76. Menchen, R. S. Perforated Pipe Used to Screen and Trap Juvenile
Salmonids. Progressive Fish Guitarist. 37(2): 85-89. 1975.
77. Kerr, J. E. Studies on Fish Preservation at the Contra Costa Steam
Plant of the Pacific Gas and Electric Company. State of California,
Department of Game and Fish. Fish Bulletin No. 92. 1953.
78. Monroe Position Statement on Monroe Intake Program. Detroit
Edison's Monroe Plant, Detroit, Michigan. March 197^.
79. Memorandum. Letter from B. G. McKinney, Power Research Staff,
Tennessee Valley Authority, Chattanooga, Tennessee to T. K. Donovan,
Division of Environmental Planning, Tennessee Valley Authority.
April 5, 1976.
80. Prentice, E. F. Vertical Traveling Fish Basket Collector. National
Oceanic and Atmospheric Administration. In: Entrainment and Intake
Screening, Proceedings of the Second Entrainment and Intake Screening
Workshop. Report No. 15: 223-22^. February 1973.
81. Griffith, J. S. and D. A. Tomljanovich. Susceptibility of Thread-
fin Shad to Impingement. Prepublication copy. Tennessee Valley
Authority. 1975.
82. Congleton, James L. Development of Biological Design Criteria for
Fish Screens and Barriers. In: Entrainment and Intake Screening,
Proceedings of the Second Entrainment and Intake Screening Workshop.
John Hopkins University, Baltimore, Maryland. Report No. 15:
February 1973.
83. Personal communication. Kenneth Garrison, Florida Power Corpora-
tion, St. Petersburg, Florida.
82
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA -600/7-76-020
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
5. REPORT DATE
October 1976
A State-of-the-Art Report on Intake Technologies
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
S. S. Ray, R. L. Snipes, and D. A. Tomljanovich
8. PERFORMING ORGANIZATION REPORT NO.
FRS-16
9. PERFORMING ORGANIZATION NAME AND ADDRESS
TYA, Power Research Staff
Chattanooga, TN 37^01 and,
TVA, Division of Forestry, Fisheries, & Wildlife
Development, Norris, IN 37828
10. PROGRAM ELEMENT NO.
EHB531
11. CONTRACT/GRANT NO.
EPA-IAG-D5-E-721
12. SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
MILESTONE; 8/75-3/76
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
EPA project officer is J.P. Chasse (EPA, ERL, Corvallis, Oregon 97330).
TVA project director is H.B. Flora (TVA, Chattanooga, TN 37^01)
16. ABSTRACT
The report presents an updated evaluation of mechanisms and intake designs for
reducing the number of fish entrained and impinged at water intake facilities.
These mechanisms consist of intake configurations, behavioral barriers for guiding
fish past intake entrances, physical screening devices to physically remove or
divert fish from cooling water intakes, and fish removal systems to evacuate
fish already within the intake area. The report summarizes evaluations of available
intake technologies. More importantly, it presents results of recent tests and
studies. Where promising mechanisms are identified, recommendations are made with
regard to tests needed to demonstrate the viability of a mechanism for protecting
fish in a particular situation. The report considers reducing fish losses both
at large-volume, once-through cooling water intakes and at lower-volume intakes
at plants requiring only makeup water to replace losses due to cooling tower
blowdown and evaporation. In evaluating devices for reducing impingement and
entrainment, consideration was given to devices and designs that can protect very
small fish and larval eggs.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COS AT I Field/Group
Pollution
Electric Power Plants
Cooling Water
Water Intakes
Fishes
Pollution Control
Stationary Sources
Screens (Protec tors)
Fish Impingement
Fish Entrainment
13B
10B
13A
13M
06C,08A
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Report)
Unclassified
21. NO. OF PAGES
20. SECURITY CLASS (Thispage)
Unclassified
_2L
22. PRICE
EPA Form 2220-1 (9-73)
83
------- |