Summary of Recent Technical Information
Concerning Thermal Discharges into
Lake Michigan
by
Center for Environmental Studies
&
Environmental Statement Project
Argonne National Laboratory
9700 South Cass Avenue
Argonne, Illinois 60439
for the
Environmental Protection Agency
Region V
Enforcement Division
Contract Report 72-1
August 1972
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PREFACE
This report, funded by the U.S. Environmental Protection Agency,
Region V, through an interagency agreement with the Atomic Energy
Commission, is a review of new technical information, relevant to the
environmental effects of thermal discharges into Lake Michigan, which
is not reflected in the existing record of the Lake Michigan Enforcement
Conference.
Between September 28 and October 2, 1970, the Lake Michigan En-
forcement Conference held a workshop in Chicago, Illinois, to consider
proposals for regulating waste heat discharges to Lake Michigan. At this
workshop, testimony was presented by staff of the U.S. Department of
Interior, the power industry, citizens, and various State and Federal agen-
cies. A five-volume record of the proceedings was published.94 Subsequent
meetings of the enforcement conference were held on March 23-25, 1971.
A three-volume record of these proceedings was also published.
Though the records of the proceedings of the Lake Michigan En-
forcement Conference contain a substantial amount of technical data rela-
tive to the environmental effects of the use of Lake Michigan water for
cooling, subsequent studies have produced technical results not previously
presented to the Conference. This document, therefore, is to provide a
summary of these subsequent studies. The intent is that it be used at the
forthcoming Lake Michigan Enforcement Conference, to be reconvened on
September 19, 1972, as an aid in the discussions and deliberations related
to thermal discharges.
The primary sources of information for this report included testi-
mony from local, state, and federal pollution-control agencies; reports
from the Great Lakes Fisheries Laboratory of the U.S. Bureau of Sport
Fisheries and Wildlife; reports from universities performing research on
Lake Michigan; permits issued by the U.S. Army Corps of Engineers;
technical and environmental reports prepared by or for power companies
discharging into Lake Michigan; and environmental impact statements pre-
pared by the Atomic Energy Commission. Results from studies conducted
on bodies of water other than Lake Michigan and reports from the open
literature were cited if they were judged to be particularly relevant and as
time permitted.
The report is structured to discuss separately the physical and
biological aspects of thermal discharges. The section on Ambient Lake
Conditions describes preoperational field studies, thermal-bar measure-
ments, and general lakewide phenomena that are pertinent to power-plant
siting considerations. The ambient lake conditions are the reference points
from which all environmental effects must be measured. The section on
Studies Related to Thermal Plumes describes field measurements of the
physical and biological characteristics of thermal discharges, summarizes
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mathematical modeling techniques, and describes some laboratory tests
on the biological effects of heated water. The section on Intake and Dis-
charge Effects summarizes operational data from most of the power
plants on Lake Michigan, describes the intake and outfall designs of the
five major nuclear facilities sited on the lake, and discusses biological
effects observed at various power plants.
The feasibility of using closed-cycle cooling systems instead of
once-through cooling was discussed at previous Enforcement Conference
hearings. There is little disagreement that the general concept of closed-
cycle cooling is feasible, with the possible exception of certain site-
specific problems. The section on Alternative Cooling Methods de-
scribes several analyses of closed-cycle cooling systems as reported in
some of the Environmental Impact Statements and summarizes available
data on estimated costs of original installations and backfitting. Chemical
discharges from both fossil-fired and nuclear power plants are tabulated
in the section on Chemical Inputs. This section also describes chemicals
used in condensers, process-water systems, cooling towers, and ponds
and reports on recent experiments to study the biological effects of various
concentrations of these chemicals.
The intent was to prepare this report on an intermediate technical
level suitable for the layman as well as the scientist. The review of any
individual reference is necessarily brief and is primarily to call attention
to the source if information in greater depth is required. We have specifi-
cally refrained from drawing conclusions from the material reported here
to minimize the influence of our particular beliefs.
The conclusions cited in this review are abstracted from the origi-
nal documents. Where the conclusions from similar studies are signifi-
cantly different, these differences are identified without discussion.
11
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CONTENTS
Section Page
I. INTRODUCTION 1
II. AMBIENT LAKE CONDITIONS 3
A. Physical Characteristics 3
1. Lake Temperatures 3
2. Inshore Currents 5
3. Thermal Bar 7
B. Biological Characteristics 12
1. Fish 12
2. Plankton 21
3. Periphyton 26
4. Benthos 28
III. STUDIES RELATED TO THERMAL PLUMES 31
A. Physical Characteristics 31
1. Field Data 33
2. Mathematical Modeling 39
3. Hydraulic Modeling 40
4. Effects on Shoreline Ice 40
B. Biological Characteristics 41
1. Waukegan Power Plant 42
2. Point Beach Power Plant 43
3. Blount Street Plant (Lake Monona) 45
4. Michigan City Station 46
5. Bailly Plant 47
6. J. H. Campbell Plant 49
7. Miscellaneous Studies 49
IV. INTAKE AND DISCHARGE EFFECTS 52
A. Inventory of Designs 52
1. Kewaunee Plant Cooling System 58
2. Point Beach Plant Cooling System 60
3. Zion Station Cooling System 60
4. D. C. Cook Plant Cooling System 65
5. Palisades Plant Cooling System 71
B. Biological Effects 71
111
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CONTENTS
Section
V. ALTERNATIVE COOLING METHODS 79
A. Environmental Impact 79
1. Davis-Besse Station 79
2. Enrico Fermi Plant 81
3. Zion Station 83
4. Point Beach Station 88
5. Kewaunee Plant 89
6. Bailly Station 93
7. D. C. Cook Plant 95
8. Palisades Station 96
9. Natural-draft-tower Operating Observations 98
10. Drift Observations 100
11. Theoretical Predictions 102
12. Feasibility 102
B. Monetary Costs 102
1. Pulliam Plant 105
2. Kewaunee Plant 105
3. Point Beach Plant 106
4. Zion Station 107
5. Waukegan and State Line Plants 107
6. Michigan City Plant 108
7. Bailly Nuclear Plant 108
8. D. C. Cook Plant 108
9. Palisades Plant 109
10. General Observations 109
VI. CHEMICAL INPUTS 110
A. Summary of Power-plant Effluents 110
B. Standards Applicable to Power Plants 112
C. Chemicals for Removal of Organic Deposits in
Condensers and Process-Water Systems 114
D. Chemicals for Treatment of Water-Steam System .... 118
E. Chemicals for Treatment of Cooling Towers and
Ponds 118
REFERENCES 121
IV
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FIGURES
No. Page
1. Ambient Lake Michigan Water Temperatures - April 23, 1970 . 9
2. Generalized Schematic Model of the Trophic Structure of Lake
Michigan 13
3. Maximum Estimated Thermal-plume Areas Associated -with
Municipal, Sanitary, Industrial, Power-plant, and Natural
River Thermal Sources 32
4. Thermal Line-Scanner Image of Point Beach Power Plant
Plume 37
5. Schematic of Kewaunee Condenser Cooling System 59
6. Kewaunee Intake and Discharge Structure 61
7. Schematic of Point Beach Condenser Cooling System 62
8. Point Beach Intake Structure 63
9. Schematic of Zion Condenser Cooling System 64
10. Zion Station Water-Intake Structure in Lake Michigan 66
11. Zion Traveling Screens 67
12. Zion Unit 2 Discharge Structure 68
13. Schematic of Cook Condenser Cooling System 69
14. Donald C. Cook Intake System Schematic 70
15. Donald C. Cook Nuclear Plant Circulating System, Units 1 & 2 . 72
16. Schematic of Palisades Condenser Cooling-Water System. ... 73
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TABLES
No. Page
1. Current Velocity Persistence Near Sheboygan, Wisconsin,
1965 6
2. Ecology of Some Important Lake Michigan Fish 15
3. Fish Species in Lake Michigan Near the Kewaunee Site 19
4. Measurement of Residence Time in Thermal Plume 48
5. Power Plant Operating Information 53
6. Summary of Alternative Cooling Decision Factors 90
7. Environmental Impact of Various Cooling Modes 92
8. General Field Observation Data - 1970, Cooling Tower
Plumes, Paradise Power Plant 101
9. Increase In Busbar Cost Over Once-Through Design (Fossil
Fueled Plants) 104
10. Increase in Busbar Cost Over Once-Through Design (Nuclear
Plants) 104
11. Calculated Chemical Discharges into Lake Michigan in
Pounds per Day Ill
VI
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I. INTRODUCTION
Lake Michigan is a precious natural resource with many potential
beneficial uses for man. He uses it for drinking water, recreation, trans-
portation, food production, waste disposal, and cooling, to name a few.
Any of man's uses of the lake will have an effect, though some uses have
significantly greater effects than others.
We are beginning to observe the results of some of our uses of this
body of water, and many have expressed concern about the trends they have
seen. The general public has recently become aware of a number of the
potential problems, and their interest in preserving the lake for its "best
and highest use (uses)" is growing rapidly. This is aptly demonstrated by
the organizing and convening of several sessions of the Lake Michigan En-
forcement Conference over the past few years and the attendant public
interest in them.
The use of Lake Michigan for cooling is receiving a large portion
of the public's attention these days. The magnitude of water being used
and the projected requirement for the future is difficult to comprehend, and
the public is rightfully questioning what the effects will be. Unfortunately
the scientific and technical information needed now to make rational de-
cisions is not available. Only recently have the resources, in terms of
manpower and dollars, been made available to acquire this information.
The results of this developing effort are summarized here for use in the
considerations related to thermal-discharge standards.
The lake areas influenced by the thermal discharges are only of in-
tesest in relation to their biological effects. Temperature controls the rates
of most biological processes (metabolic rates, disease, predation, etc.) and
increases in temperature from the thermal plumes may cause direct and in-
direct effects on biological systems. Potential sources of biological damage
associated with once-through cooling are summarized in the Final Environ-
mental Statement for the Palisades Nuclear Generating Plant.119 They are:
(1) Temperature increases of the cooling water, causing both direct
effects and indirect effects on metabolism, growth, disease,
predation, etc.
(Z) Mechanical and pressure changes that damage small organisms
passing through pumps and condenser tubing.
(3) Impingement on intake screens of larger organisms, principally
fish, drawn into the cooling-water intake.
(4) Chemicals used as biocides (usually chlorine) to remove slimes
from the condenser tubing, and perhaps other chemicals re-
leased to the cooling water from a variety of plant operations,
all of which may be toxic to aquatic life.
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(5) Induced circulation of a water body, both in the local area of
the discharge (which may influence migrations) and in the
wider range of the water body (changing normal seasonal
patterns).
(6) Radiation derived largely from radioactive nuclides taken up
by terrestrial and aquatic organisms, which could potentially
induce radiation damage if concentrations of the nuclides were
sufficiently high.
A seventh could be their combined effects.
Reference 119 presents a rather comprehensive discussion of these
potential sources of biological damage and is recommended as an excellent
summary.
The general subject of effects of temperature on aquatic organisms
has been reported in several scientific reviews that became available in
1971. Since this report is limited specifically to Lake Michigan, and since
it is impractical to review a review, our guide to this wealth of new infor-
mation will consist of a single reference to the publication by Coutant,
"Thermal Effects (Biological): A Review of the Literature of 1971 on
Wastewater and Water Pollution Control." The review describes some
390 references, practically all of which are dated 1971 or 1970.
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II. AMBIENT LAKE CONDITIONS
Adequate knowledge of ambient lake conditions is required for at
least the following three reasons:
1. Standards are being developed to guide our actions in the design
and siting of power-generating stations. Knowledge of ambient conditions
is necessary to evaluate the validity of the standards as applied to different
areas; i.e., do the ambient conditions violate the standards? Knowledge of
ambient conditions is also necessary in the enforcement of the standards.
The baseline from which the standards will be applied must be clearly de-
fined so that subsequent actions may be quantified for evaluation.
2. Adequate background knowledge is required for use in evaluation
of potential sites and for reliable design calculations.
3. Background information in specific areas is necessary for the
observation of potential changes or damage that may incur as the result of
man's use of the lake.
There are data in the literature, and being developed, that describe
the overall lake characteristics such as major circulation patterns, tem-
perature regimes, biological characteristics, and aquatic inhabitants. In
addressing the problem of thermal discharges, however, we are concerned
with the near-shore regions and their specific characteristics, and the ways
in which they differ from the lake norm and from other regions with which
they might be compared.
A. Physical Characteristics
This section describes ambient data, relevant to Lake Michigan,
published since 1970. The summaries are organized with respect to geo-
graphical areas associated with existing power-plant sites.
1. Lake Temperatures
Ambient lake temperatures have been measured periodically in
the Zion-Waukegan area since 1969. Reference 12 presents data in graphical
form that shows the near-shore temperature distribution as a function of
depth. Some of the most pertinent features of the data include the spatial
variability of the temperatures and the documentation of the thermocline.
For instance, an ambient temperature profile obtained in August 1970, east
of the Waukegan Harbor, shows 2 the temperature decreasing from 64.4 to
50°F between the depths of 13 and 16 ft. The ambient surface temperatures
near shore were observed to vary from 62.6°F at Zion to 65.5°F at Waukegan
Harbor, a distance of 4 miles. The ambient surface temperature also in-
creased in the offshore direction to over 70°F at a distance of 6 miles. This
was apparently an upwelling condition.
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The Bio-Test Laboratories reported66 that ambient temperature
differences of as much as 3.6°F in 980 ft made it difficult to clearly define
the perimeter of the thermal plume at Waukegan.
A graphical representation 7 of ambient lake temperatures on
February 16, 1971, 2000 ft south of the Waukegan Generating Station, shows
that, except for a very small region at a depth of about 12 ft, the temperature
is essentially uniform at 32 to 32.5°F at all depths to an offshore distance of
16,000 ft. On March 10, 1971, all top-to-bottom temperatures were deter-
mined to be 32.0°F-68 Ambient temperatures measured on June 2, 1971,
showed69 weak stratification with inshore heating. Inshore surface tempera-
tures were 52-53°F; 2 miles offshore the surface temperature was 47°F, and
the bottom temperature at a depth of 45 ft was 41°F.
Water-temperature measurements 9 at Zion, during April-
December 1971, ranged from 37.8 to 72.5°F, the lowest in April and the
highest in August. The thermal behavior of the Zion-Waukegan area was
summarized as follows:
"Generally, inshore water temperatures were somewhat
higher than offshore during the spring and fall, while the reverse was
true in summer months. A thermal bar was observed in April and
December near the offshore (sampling) stations (approximately two miles
from shore).
"The spring overturn continued until early June, when the
thermocline appeared, ... . Thermal stratification began in June at the
Waukegan station. However, the thermocline was not observed at the
Zion area until early July. The height of summer stratification was found
in August and disappeared during the mid-September sampling period as
fall mixing began in the area." 9
Average monthly water temperatures for the Waukegan, Chicago
and Milwaukee water intakes are compared in Fig. 2.5 of Ref. 26.
Lake temperatures at several stations near the Point Beach
Nuclear Plant were measured, starting in April 1969. There was a general
slow warming trend from April through July, reaching the high 60's, with
only moderate temperature fluctuations. However, in August and September,
upwelling conditions produced temperature fluctuations of greater than 20°F
in several days. The maximum and minimum temperatures during August
were 71 and 46°F, respectively. From August 4 to August 9, the temperature
at the intake dropped from 68 to 48°F.126
Temperature data obtained from April to December 1970 essen-
tially confirmed the 1969 data.127 Similar data obtained in 1971 showed a
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temperature high of only 63°F during mid-September. This is about 8°F
Blower than the highest temperatures observed during August in the 1969 and
1970 studies. The large ambient-temperature fluctuations of up to 20°F ob-
served in 1969 and 1970 were not observed during 1971.128
During studies of a sinking plume,59 ambient lake temperatures,
at depths of 16-36 feet, were observed at Point Beach and a station 2 miles
north during March and April 1971. During March, the bottom temperature
increased slowly from 32 to 35°F, with relatively little fluctuation. From
April 3 to April 17, it increased from 35 to 40°F with daily variations of up
to 3.6°F over periods of 3-6 hr. Ambient-lake-temperature measurements
at the Kewaunee site 31~133 were basically in agreement with the Point Beach
data for the same period. The Kewaunee site is approximately 4.5 miles
north of the Point Beach site.
On the eastern side of Lake Michigan, an ambient-lake-
temperature sensing and recording system was actuated at the Cook Plant
Site in May 1970. Temperatures were measured at various depths at both
300 and 2500 ft offshore. Results of the measurements obtained through
February 1971 are tabulated in Ref. 5. The data consist of daily maximum
and minimum water temperatures obtained at the Cook Plant site and at the
Benton Harbor and St. Joseph water-plant intakes.
Previously unreported data giving the average temperatures of
intake water during 1969 at the J. H. Campbell Plant at Port Sheldon,
Michigan, is presented in Ref. 119. The J. H. Campbell Plant is located
about 40 miles north of the Palisades Plant. These data showed a maxi-
mum temperature of 77°F in August and variations of up to 13°F within one
day.
Average monthly water temperatures near the Bailly Generating
Station for October 1970 through September 1971 are tabulated in Ref. 120.
These data were obtained at the Burns Harbor Plant of the Bethlehem Steel
Company, immediately west of the Bailly site.
2. Inshore Currents
Inshore currents are primarily wind driven and are therefore
quite variable, both spatially and temporally. Relatively little inshore-
current data are available in the literature.
On the west side of the lake, near the Point Beach site, current
velocity measurements -were made at 20-min intervals during August to
October 1965, at a location 2 miles off the coast of Sheboygan. The data,
reported129 in terms of persistence, are shown in Table 1.
Drogues 'were tracked on three separate days in 1971, near the
Kewaunee site, to observe the near-shore currents. Under calm conditions,
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Table 1
Current Velocity Persistence
Near Sheboygan, Wisconsin, 1965129
Current (ft/sec) Persistence (I of time)
0-0.5 68
0.6 - 0.7 10
0.8 - 0.9 12
1.0 or higher 10
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preceded by a 5- 10-mph north wind, the drogues drifted south at an undeter-
mined velocity (due to fog). Under the influence of offshore winds, a drogue
500 ft offshore, moved in an offshore direction (east) at 0.2 fps, and a drogue
200 ft offshore moved south at a speed of 0.4 fps. With an onshore wind, the
drogues moved shoreward and north at 0.16 fps.70
Current measurements taken near the Zion site during 1969 were
reported to range from 0.07 to 1.09 fps, with most values within 0.2- 0.5 fps.
Measurements of inshore lake currents in the Palisades Park,
Michigan, area are summarized in the Palisades Environmental Report
(Revised).2 On the basis of wind records, it was estimated that an along-
shore current flows northward about 33% of the time and southward about
23% of the time. Offshore winds occur about 38% of the time, but these are
expected to have a minimal effect close to shore and the along-shore cur-
rents should tend to persist, once set up, while offshore winds are blowing.
Thus, the frequency of along-shore current flow should be somewhat greater
than cited above.
The Bailly Environmental Report91 cites drogue studies
(unreferenced) as showing that surface currents (upper 5 ft) are directly
wind-driven and respond to wind shifts within 1 hr. At the 5-ft depth, cur-
rents were skewed 27° to the right of the prevailing mean wind. Current
velocities in the upper layer were measured to 1.6 fps. However, typical
velocities were much less.
3. Thermal Bar
The "thermal-bar" mechanism develops when waters reach a
temperature associated with the maximum density of water (39-2°F). As the
surface waters warm in the spring, or cool in the winter, they eventually
achieve a temperature of 39.2°F and, being more dense than the surrounding
water, they tend to sink. This downward flowing region of 39.2°F -water,
called the thermal bar, is visualized as separating the inshore waters from
the mid-lake water. The inshore waters are warmer than midlake water in
the spring and cooler in the winter. During spring, the inshore side of the
thermal bar develops a thermocline separating the rapidly warming surface
water from the deeper, cold water. Offshore of the-thermal bar, vertical
mixing extends from the surface to the bottom due to the absence of a ther-
mocline. The thermal bar often exhibits turbidity and color gradients on
the lake surface at the point of offshore and inshore flow convergence.
The thermal bar is not static. Except for occasional shoreward
movement, its main movement is from inshore to offshore until it eventually
disappears in midlake. The thermal bar lasts for 4-8 weeks in Lake Ontario
(and Lake Michigan) and is believed to be controlled by surface (solar) heat-
ing and the heat capacity of the lake.100
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Ambient-temperature measurements have revealed the presence
of thermal bars on several occasions in the Zion- Waukegan area. Bio-Test
studies12 of ambient lake temperatures, approximately 3 miles north of the
Waukegan Station, recorded the thermal bar on April 23, 1970, approximately
16,600 ft (3.1 miles) offshore. Figure 1 is a graphical representation of the
data and shows fairly uniform temperatures on one side of the bar (39.2°F
isotherm) and thermal stratification on the other. Ambient temperatures in
excess of 48°F were found near shore. On April 30, 1970, no evidence of the
bar was found out to a distance 36,000 ft (6.8 miles). The offshore velocity
for this particular observation was, therefore, at least 0.53 mile/day.
Water temperatures indicating a weakly defined thermal bar
were observed on December 18, 1970.67 The bar was Z9.9ZO ft offshore.
At 4250 ft to the east, or offshore side of the bar, the temperature was
39-6°F from top to bottom; 4260 ft to the west of the bar, the temperature
was 38.8°F. Measurements and analysis of water samples collected from
top, middle, and bottom depths, at both these locations, indicated no signi-
ficant differences in pH, chlorides, conductivity and dissolved oxygen.
The spring thermal bar was again observed and documented 8
on April 20 and May 3, 1971, in the Zion-Waukegan area. Offshore tempera-
ture transects were made from the Zion site, the Waukegan plant, and a
point in between. The bar was located 8000, 8000, and 5000 ft offshore, re-
spectively, at these three locations. The bar was well defined with cooler
water to the east nearly isothermal from top to bottom, while the inshore
water to the west was well stratified, with top to bottom temperatures
varying from 45 to 41°F.
A comparison of water-quality samples taken 600 ft from the
bar, on both the inshore and offshore sides, showed dissolved oxygen and
pH values to be similar. However, there was a tendency toward lower
values for chlorides, conductance, and turbidity in samples taken from the
offshore side, as compared with samples taken from the inshore waters.
Transects made on May 3, 1971, at the Zion site and at a point
between Zion and Waukegan. showed the thermal bar to be 17,000 and
19,000 ft offshore, respectively. The bar was less well defined, with ther-
mal stratification less pronounced on the inshore side. The average velocity
of movement offshore during this period was 0.12 mile/day at the Zion site
and 0.19 mile/day at the test area south of Zion. No chemical measurements
were reported during this observation.
The University of Michigan Willow Run Laboratories reported110
an aerial survey of the thermal-bar development, between Port Sheldon
(J. H. Campbell Plant) and Grand Haven, Michigan, between April 22 and
May 7, 1971. The survey used an infrared scanner to map surface-
temperature regimes and a scanning spectrometer to measure "apparent"
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water-quality variations, primarily in terms of different reflectance spectra.
The report includes a number of pictures of the results.
On April 23, the studies revealed significant shoreline heating
but no indication of a thermal bar. The imagery obtained April 30 showed
a very distinct thermal bar approximately lj to 2 miles offshore. On May 7,
the bar had moved about 4 miles offshore.110 Thus, the average offshore
velocity was about 0.3 mile/day during this period.
Any interaction between the Campbell Plant plume on the
Grand River plume and the thermal bar was not clearly evident. The plume
of the Grand River appeared to be much larger than the Campbell Plant
plume, on both the thermal images and the multispectral images.
The reduced multispectral data show water masses with dif-
ferent spectral characteristics (differences in color, turbidity, etc.). Water
on the inshore side of the thermal bar had decidedly different characteristics
than the offshore water. Also, the water masses associated with the
Grand River had rather sharply defined boundaries, whereas the Campbell
Plant water-mass boundaries were ill-defined. "In general, there was very
little mixing of water masses on the shore side of the bar. Since the wind
on this particular day was less than 5 mph, this was not surprising."
The data of May 7, under somewhat stronger wind conditions,
indicate a considerable amount of mixing on the inshore side of the bar.
Again, there was no apparent indication of the Grand River or Campbell
Plant plumes interacting with the thermal bar. (It was 2 miles further off-
shore.) "The map of different water masses along the shore for May 7 em-
phasizes the complex environment in Lake Michigan and the danger of
drawing conclusions from only a small number of samples.
"Observing the results from the two dates (April 30 and May 7)
we note that there is not a characteristic water mass traceable solely to the
existence of the power plant plume, while the plume of the Grand River is
distinctly outlined and the boundary of the thermal bar is also evident. That
an algae growth difference (and, therefore, spectral differences) across the
thermal bar exists has been documented and reported by Stoermer. 1 The
outfall of the Grand River is also known to contain nutrients, pollutants, and
sediments which characterize its color. Since the power plant discharges
water that has been recycled with only heat added, it seems reasonable to
expect no change in the water's spectral characteristics."
Rodgers has reported on thermal-bar measurements in
Lake Ontario during the spring of 1970. ° Weekly temperature profiles
were measured at 30-60 stations from May 11 to June 24, 1970. Calcula-
tions of heat-content changes in various portions of lake water (due to
surface heating, advection, etc.) indicated higher than average heat-content
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11
changes near the thermal bar. "Very large positive heat content changes
take place in the middle of the lake during the last one to two 'weeks, in the
presence of the thermal bar, associated with small, even negative changes
in heat content along the north shore. It is with a reasonable degree of con-
fidence that it can be said that the differences in heat content change
(between shore and mid-lake) in the latter stages must be due to offshore
advection of heat."101
The speed of movement of the thermal bar was inversely cor-
related with the slope of the lake bottom. Between May 11 and June 8, the
thermal bar moved away from the north shore of Lake Ontario at an average
speed of 0.43 mile/day. The speed away from the south shore was 0.22 mile/
day. During the week of May 19-25, however, the bar actually moved shore-
ward by a distance of 1^ to 2 miles. "Clearly, there are substantial pertur-
bations in the general offshore progression of the bar." 01
In a study of the effect of the thermal bar on the concentration
of several chemicals in Lake Ontario. Weiler and Coker,123 during May 1970,
measured pH, conductivity, dissolved oxygen, calcium, alkalinity, inorganic
carbon, total phosphorous, chlorophyl _a, silicon, nitrate-nitrogen, and trace
metals on both sides of the bar. They summarized their results as follows:
" Discriminant analysis shows waters inside and outside the bar are chemi-
cally distinct with respect to some of the nutrients. These differences in
nutrients are caused by the greater biological activity in the warmer waters
inshore of the bar. However, the bar apparently has no effect on the water
composition as far as the major ions are concerned. The evidence for the
trace elements is not conclusive."123
The role of the thermal bar in containing health-oriented bac-
teria to the inshore area was investigated in two preliminary studies in
Lake Ontario during May 15-22, 1970.83 By measuring coliform, fecal coli-
form, bacterial biomass and 20°C plate counts in one test, and measuring
the diffusion of a tracer bacteria, Ser ratia mar cescens, Menon e_t al. con-
cluded that "sufficient data have been collected to suggest that the thermal
bar has significant effect on the distribution of bacteria in the lake."
They also stated, however, "The single recovery of
S. marcescens, although suggestive, is not sufficient evidence to support
our hypothesis of the thermal bar's barrier effect to the offshore movement
of bacteria. One possibility which must be considered is whether or not the
offshore movement of the thermal bar is greater than the diffusion rate of
the tracer organism. If such was the case, the diffusion of the tracer or-
ganism would never be affected by the thermal bar and eventually would be
o -a
dilutedbeyond recovery." Furthermore, the tests were not made in the
absence of the thermal bar for purposes of comparison.
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12
B. Biological Characteristics
In aquatic ecosystems there are natural fluctuations both spatially
and temporally, in biota and physicochemical conditions. In addition, there
is a natural progression of lakes toward eutrophication. To distinguish be-
tween changes due to natural factors and those due to man, it is necessary
to acquire and analyze data, both before and after man's activities, in suf-
ficient quantity and quality to allow such determinations to be made.
Reference 5 provides an elementary summary of the Lake Michigan
ecology. "Although Lake Michigan is showing signs of eutrophication and
major changes have occurred in the fish populations, the lower levels of the
food chain appear to be relatively unchanged from that generally described by
Bersamin15in 1958 ... . The productivity of fish population is highly depend-
ent on the productivity of crustaceans in this lake. A generalized food chain
for Lake Michigan would be: production of green algae, primarily diatoms,
which are grazed by crustacean zooplankters. These crustaceans are in
turn grazed on by plankton feeders, which include nearly every species of
fish in Lake Michigan, at least during some phase of their life history.
Many of these fish species later become piscivorous (fish eating) and feed
on other fish species when they reach a certain size."119 Figure 2 depicts
the general trophic structure for the lake at present.
1. Fish
The recent history of Lake Michigan has seen a drastic species
change in the fish population. A summary of the commercial production50
from 1879 to 1968 shows a drastic reduction in lake trout, lake white fish,
and lake herring, fluctuations in smelt, and an increase in bloater and par-
ticularly in alewives.
Historically, the Lake Michigan offshore waters had a fish popu-
lation dominated by lake trout, lake white fish, lake herring, bloater, and
burbot. Brown and rainbow trout were also present, but these normally used
streams for spawning, and it was there that most were available to sports
fishermen. In the shallower, inshore waters, the white fish, lake herring,
yellow perch, a number of species of small suckers, minnows, and darters
were found. All of these fishes were subject to substantial year-class fluc-
tuations due to natural causes, such as very successful or unsuccessful
spawns, species competition, and species interactions.
In about 1936 the predatory sea lamprey was introduced into
Lake Michigan from below Niagara Falls. Predation by the sea lamprey,
added to that of man, reduced the population of large fish such as lake trout
and the lake white fish to a point where commercial lake-trout fishing was
virtually abandoned. The alewife and smelt were also introduced, and with
the top predators having been reduced by predation, the alewife exploded
into huge population densities in the mid-60's.
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In the late 60's the coho salmon was introduced into the system
as a top predator. It is now a locally important sport fish. More recently, -
other predators such as chinook salmon, sockeye salmon, steelhead, splake
(a trout hybrid), and lake trout have apparently been successfully stocked.
Some fish taken recently show signs of scarring, indicating that the lamprey
is still present, although reduced by the many control methods.
A thorough summary of the life histories, migratory patterns,
spawning habits, temperature preferences, etc., of the principal fish of
Lake Michigan is presented in Appendix V-2 of the final Environmental
Statement of the Palisades Nuclear Generating Plant.1 Table 2 summarizes
the ecology of some of the important Lake Michigan fish.
In the immediate Zion-Waukegan area, commercial fishing was
reported to be nonexistent. Historical records of catch activity indicate
that most fishing takes place 9 miles or more offshore. Fish that are com-
mercially important in the general area are bloaters, yellow perch, and
smelt. Forage fish, which also inhabit the area, are important to the sup-
port of both the sport and commercial fisheries. The most abundant is the
alewife. Sport fishing in this area is very popular.2
Commercial fishermen have reported 21 fish species near the
Zion area. Of these, 15 species were captured by gill nets and minnow
seining during field tests by Bio-Test Laboratories between March and
October 1970.2 Seventeen species were collected from April through
December 1971 by minnow seining in the inshore areas in conjunction with
studies of the Waukegan station intake and discharge.72
The two most abundant fishes taken during the 1970 test period
were the alewife and the yellow perch. Other fairly common specimens were
the smelt, bloater, and spottail shiner.26'73 The coho salmon was the most
frequently taken salmonid game fish. Statistical data on the weight, length
and sex of the various species versus location of capture are given in
Ref. 73. In a number of instances, particularly for the alewife, spottail
shiner, smelt, and yellow perch, considerably more females than males
•were taken from the inshore areas at both Waukegan and Zion. Immature
individuals were most commonly taken along the shoreline.73
The most abundant species near Zion during the 1971 tests were
the alewife and spottail shiner. Emerald shiners, bloaters, longnose dace,
and smelt were present in low numbers intermittently throughout the sum-
mer and fall of 1971.72
Stomach-content data for fish collected in the Zion-Waukegan
area were summarized in Table VIII of Ref. 73. The salmonids fed most
frequently on forage fishes, especially alewives. Amphipods, probably
Pontoporeia affinis, were important food items for the white sucker,
-------
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sculpins, and the one white fish that was collected. Although Pontoporeia
has been reported as an important food for alewives and occurs commonly"
in the area, it was not heavily used by the alewives captured in the study.
Shoreline minnows, white suckers, and smelt fed heavily on chironomid
larvae. Yellow perch and smelt fed more frequently on forage fish in the
Waukegan area than at Zion. Zooplankton (cladocerans and copepods) were
used by more fish at Waukegan than at Zion, except for the alewife.73
The relative frequency of fish eggs in the stomachs of nine
species showed a rather wide utilization of fish eggs for food. The fish eggs
were probably the eggs of more than one species, since they were found over
such a long period, from March through October. Alewives, smelt, and
perch were found in the area during their anticipated time of spawning, and
the eggs of these species •were probably among those commonly found in the
stomachs.
Reference 122 states "Although no direct data exist, it is ques-
tionable if the waters off the Zion site could provide grounds suitable for
spawning of any fish on a large scale due to the ever-present scouring
action of waves. Spawning presumably occurs in protected harbors where
there are quiet waters." Bureau of Sport Fisheries and Wildlife records42
for various fish spot-checked by trawling at 3-40 fathom depths off Waukegan
from 1967 to 1971 (October, November, April and May) suggest that, except
for smelt, alewife and bloater, the ratio of young to adult is much less than
50%.122
Plankton net tows have shown that this area does not contain
significant amounts of either fish larvae or pelagic fish eggs, yet analysis
of stomach contents suggests that spawning of some species may take place.73
Supplement IV of the Zion Environmental Impact Report27 states,
"Based on preoperational monitoring accomplished thus far, it appears
fairly certain that spawning grounds for lake trout and white fish do not
exist in the Zion area. Preoperational studies have shown that adults of
these species are absent from the predicted area of discharge during spawn-
ing season. "
Recent collections by state fisheries and game personnel have
shown the species of fish listed in Table 3 to be present at the Point Beach
and Kewaunee area.98 This was confirmed by gill-net sampling by Bio-Test
Laboratories in 197 I.70
The most abundant sport fish found in the area during 1971 was
the lake trout.70 Virtually all had been stocked in Wisconsin waters by
Federal or State agencies, as indicated by their clipped fins. The bulk of
the fish taken were year-class V (1966) fish. They were predominant in the
spring and fall; year-class III and IV fish were more in evidence during the
summer months.
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Stomach analysis of the lake trout revealed alewives comprised
57%, by volume, of the total food items. Other items included smelt, shiner-s,
and sculpins. A large number were taken with empty stomachs. This oc-
curred during October 1971, when they were near spawning conditions.70
Reference 129 states there are no known spawning or nursery
grounds for fish in the area of the Point Beach Power Plant site. Samples
taken from the Point Beach discharge flume by the Wisconsin Department
of Natural Resources, between March and May 1971, resulted in a total catch
of eight sculpin, two samples with a "few" smelt eggs, and one possible
salmonid egg.129
During a 3-yr period (1968-1970) of preoperational surveys
conducted by the State of Michigan96 in the area of the Palisades Plant,
28 species of fish were captured by gill netting, seining, or trawling. Gill-
net catches were dominated by alewives (55%) and yellow perch (39%).
Shoreline seining disclosed a predominance of longnose dace and spottail
shiners. Aside from alewives, the trawl catches were composed princi-
pally of smelt, trout, perch, and bloaters. Among the salmonids, the total
catch for 3 yr was 32 lake trout, 8 coho salmon, and 10 chinook salmon,
nearly all of which were from plantings made at nearby Port Sheldon and
New Buffalo.96 There were significant diurnal differences in the catches.
Perch was the most abundant game fish sampled throughout the
summer and fall. Since no young-of-the-year perch were captured, it was
postulated that they were inhabiting the zone 3- 18 ft deep, an area that was
not sampled. Very few adult alewives were taken in the inshore area dur-
ing daytime seining, but large numbers were captured at night on
May 14, 1970.
Bloaters were the only species of Coregonus caught in any
abundance during the 3-yr period. Only four lake herring were taken
during the test period.
A Great Lakes Fishery Laboratory cruise report described
fishing to locate spawning grounds of lake trout and white fish in south-
eastern Lake Michigan. "Catches (during November 1971) of ripe, spent,
and gravid female lake trout in several areas off Benton Harbor (D. C. Cook
Plant site), South Haven (Palisades Plant site), and Saugatuck suggest that
this species spawned in large numbers along the entire southeastern shore
of Lake Michigan. All males were in spawning condition. Of 183 fish over
23 inches long, 31% had healed lamprey scars and 1.1% had fresh wounds.
"The only whitefish taken were a single female off New Buffalo
and 6 ripe males off Saugatuck. The evidence ... suggests that whitefish
spawn in suitable locations (probably mostly reefs) along the southeastern
-------
21
Lake Michigan shore, but not in great numbers. Fairly large catches of
lake trout were made off New Buffalo and Saugatuck in the December nets.
Nearly all were males."19
Fish, taken inshore at the Bailly Plant site (September 19-20,
1970) by seining, included about 200 yellow perch, less than 3 in. long, sev-
eral small bluegills, two small largemouth bass, and several species of
unidentified minnows.91 Fish taken in gill nets included 88 yellow perch,
two white suckers, and one longnose sucker. Yellow-perch age groups were
III, IV, V, and VI with twice as many females as males. The perch were
feeding primarily on crayfish (from extensive areas of rip-rapping in the
area) and other fish.
Additional fish data specific to the Cook Plant area are given
in Ref. 65. A tabulation of the 1970 catch data for game fish taken off of
Berrien County, Michigan (site of the Cook Plant), revealed the following
abundance percentages: smelt, 62%; perch, 31%; chinook salmon, 6%; and
trout (lake, brown, rainbow, and steelhead), 4%.
2. Plankton
Generally, Lake Michigan has low algae populations compared
with those of most surface waters, with centric diatoms predominating. 4
During the summer, however, the southeast sector of the lake contains
algae close to the shoreline of the type commonly found in eutropic situa-
tions.87 There is an apparent relationship between the areas of the lake
shore, where nuisance algae occur, and the proximity of sources of plant
nutrients contributed by major tributaries.119
The background data on plankton in the Zion-Waukegan area were
summarized as follows:26
"Water samples for plankton counts were collected in the Zion
area in April 1968, and in August, October and December 1969, and monthly
since. Despite a problem in comparing population because different sam-
pling techniques were used, the species of plankton identified in the spring
of 1968 were similar to those of 1969 and subsequent studies ... .
"In August 1969, the plankton population near Zion was composed
of green algae, blue-green algae, diatoms, protozoans, and crustaceans with
the diatoms usually comprising more than 80 percent of the total plankton.
This plankton population was not evenly distributed in the water column but
was most numerous at the 15 to 20 foot depth.
"In October 1969, the total plankton population was similar in
composition to that observed in August. Diatoms usually comprised more
than 75 percent of the total plankton population at all depths sampled. In
-------
22
addition to members of the genera Fragilaria and Tabellaria, species of
Asterionella were observed more frequently in the October samples. Al-
though temperatures •were similar throughout the water column, the plankton
populations were most numerous at the 10 to 13 foot depth.
"Plankton samples taken during December, 1969, were obtained
from a much wider section of the lake than earlier samples and are there-
fore believed to more accurately represent the existing population. Most of
the samples were taken between the 5 and 15 foot depths, ... . The total
population was composed of the same planktonic forms observed in August
and October, 1969; however, the diatoms comprised more than 90 percent
of the population (rather than 75 percent). The diatoms Tabellaria and
Fragilaria were still represented; however, species of Stephanodiscus re-
placed Asterionella as a dominant form.
"The 1970 and 1971 studies to determine the thermal effects on
both phytoplankton and zooplankton found in the Waukegan area produced
comparable data on planktonic population to those in the Zion study. With
respect to phytoplankton, these more extensive studies confirmed earlier
observations and led to the conclusion that most species encountered were
classical to Lake Michigan, however, the diatom Stephanodiscus hantzschii-
tenuis was a notable exception. It was found to be the most dominant species
in April, May and June and has been associated with organic enrichment
(Stoermer and Kopczynska, 1967). This species also represents more
than 5 percent of the August and September populations."2
It should be noted that the relative abundance of diatoms meas-
ured by the Industrial Bio-Test Laboratories in the Zion-Waukegan area in
August, October, and December 1969 (80, 75, and 90%, respectively), con-
trasts sharply with the data of Schelske and Stoermer, which indicated
that diatoms comprised 10% of the phytoplankton samples taken from the
midlake part of southern Lake Michigan during the summer of 1969.
A more detailed reporting69 of plankton samples obtained in the
Zion-Waukegan area from April to December 1971 revealed the following:
Chrysophyta (golden-brown algae) was the most abundant algae division.
Diatoms, the most numerous of which were Fragilaria crotonensis,
Stephanodiscus binderanus, S. hantzschii-tenuis, Rhizosolenid eriensis,
Asterionella formosa, and Tabellaria flocculosa, comprised more than 90%
of the April-August population, about 50% of the September-October popula-
tion, and more than 70% of the November-December population. The Cyano-
phyta (blue-green algae) was the second most abundant, the percentages
ranging from 0.2 to 42% of the phytoplankton. Chlorophyta (green algae) had
an abundance of 0.2-7.6% of the total phytoplankton.
The largest standing crops of diatoms were observed in April,
May, and June when temperatures were below 56°F, with inshore waters
-------
23
containing more than offshore waters. The temperatures at this time were
above what is considered optimum for several of the dominant species. 9
Comparison of Chrysophyta populations -with the concentrations
of silicon dioxide, total phosphate, and nitrate-nitrogen revealed (a) that
silica increased gradually in the spring and then declined concurrently with
decreasing diatom populations during August (the quantity of silica generally
declines as diatom populations increase), (b) total phosphates decreased
gradually from June through October, and minimum amounts coincided with
the fewest diatoms, (c) nitrate-nitrogen remained uniform from May through
September and increased during the fall (this may be attributed to a reduced
uptake of nitrates by phytoplankton during a period of minimum population
growth).
The blue-green algae comprised less than 5% of the phytoplank-
ton from April through August 1971. However, from September through
December, percentages at various sampling locations varied from 11 to 67%
of the phytoplankton, primarily due to an increase of Collosphaerium
naegelianum. It was noted that blue-green algae populations did not exceed
25% of the total during the 1970-1971 study.
Zooplankton data acquired by the Industrial Bio-Test Labora-
tories were summarized2 as follows: "Additional data on zooplankton, also
obtained in 1970 and 1971 studies, revealed that the most common classes
present in Lake Michigan near the Zion station were copepods, cladocerans
and to a lesser extent, rotifers. The most abundant zooplankton crustacean
in Lake Michigan, the Cyclops bicuspidatus thomasi, was found to be the
dominant species representing the copepods. Other common copepods ...
were Eurytemora affinis (present in large numbers in September and
October), Cyclops vernalis (quite common in October and present in low
numbers in September), and Diaptomus ashlundi (found in moderate numbers
in January and December and again only in significant numbers in
September). The most abundant Cladocera throughout the study was found
to be the Bosmina longirostris. Daphnia retrocurva and Ceriodaphnia
quadrangula were also present in significant numbers in August. Rotifers
were represented predominantly by Conochilus and Asplanchna
priodonta ... . "26
A more detailed reporting of zooplankton studies in 1971 stated
that a seasonal variation was clearly observed. "The major portion of the
zooplankton community was composed of copepods during the spring months.
Then, with the higher water temperatures of July through September, the
cladocerans predominated. As the water temperature decreased, the
copepods again predominated.1
Plankton samples obtained at the Kewaunee site in 197 I70 re-
vealed that diatoms were the most abundant members of the phytoplankton,
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24
followed by blue-green algae and green algae. The diatoms were most
abundant in May (91%), and the fewest numbers were observed in November
(66%). Blue-green algae comprised 2-26% of the population, the lowest and
highest values occurring during May and November, respectively. The
larger counts were due to an increase in Coelosphaerium naegelianum.
Green algae and miscellaneous forms always accounted for less than 8% of
the total. These results are similar to the Zion studies.
The five most abundant species were Fragilaria pinnata,
F. crotonesis, Tabellaria flocculosa, Coelosphaerium naegelianum, and
Stephanodiscus hantzschii-tenuis. All are diatoms except the blue-green
algae C_. naegelianum.
Zooplankton samples were obtained in the Point Beach and
Kewaunee areas by The University of Wisconsin-Milwaukee1 128 and at
Kewaunee by Bio-Test Laboratories.70 The Bio-Test data identified 13
species of cladocerans, 11 species of copepods, and two immature stages
of copepods during 1971. This included small numbers of five genera not
reported in The University of Wisconsin data of 1969126 and three genera not
reported in the 1971 data.128
The most numerous species identified in the Bio-Test studies
at Kewaunee were Bosmina longerostris, Chydorus sphaericus, Cyclops
bicuspidatus thomasi, and two species of Daphnia; The University of
Wisconsin data from Point Beach and Kewaunee listed Bosmina, Cyclops,
Diaptomus, Daphnia and rotifers as the most abundant. Both studies found
numerous copepod nauplii. The rotifer population was reported to be much
higher in 1971 than in 1969 and 1970.128'70
Dr. Ayers conducted limnological studies at the Cook Plant site
in 1969 and 1970. On July 10, 1970, phytoplankton samples were obtained
at 53 stations. The 53 samples contained 59 dominant or codominant (six
stations had two species of approximately equal numerical superiority)
groups, of which 49 were diatoms.7 The number of samples in which the
various species were dominant are Tabellaria fenestrata (32), Cyclotella sp.
(seven), Milosira sp. (six), and Fragilaria crotonensis (four). The species
Milosira sp. and Cyclotella sp. were most dominant in the surf zone, and
F. crotonensis was more dominant in stations farthest offshore.
The investigators made the following comments concerning
their data:5
a. "There appears to be an increase (in numbers of species,
at least) of blue-green algae from spring into fall.
b. Green algae appears to have a peak in late summer that
may or may not be supported by subsequent data.
c. The persistence of flagellates is unexpected and may or
may not be supported by subsequent data."
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25
Examining their data for river-associated phytoplankters, they
concluded that the evidence from the July 10 survey shows no demonstrable
effect of the St. Joseph River on the Cook Plant phytoplankton.7
Variations from station to station in the diversity index, number
of species, and organism density, during the July 10, 1970, tests forced them
to conclude "that small •water masses, each with different biotic characteris-
tics, move through the Cook Plant area."7
Zooplankton data obtained on July 10, 1970, also indicated a
patchiness from station to station, but it was not as pronounced as phyto-
plankton patchiness. Although the Cyclopoid copepods were occasionally
present in the greatest numbers, Bosmina cladocerans dominated the sam-
ples most frequently. The most abundant zooplankters had the following
sample frequencies: Cyclopoid copepods (eight), Diaptomus copepods (none),
Bosmina cladocerans (37), Polyphemus cladocerans (two), and Asplanchna
rotifers (none).
Copeland and Ayers34 provide an interpretation of biological data
obtained during lakewide sampling during 1969 and 1970. "Inspection of the
phytoplankton data tends to confirm the general trends observed in other
studies. In general, total phytoplankton abundance was greater near the
south end of the lake and near shore than in the northern end and in the cen-
tral lake. This was the expected situation. However, relative abundance of
the various algal groups did not follow the expected pattern. In only about
half of the samples did diatoms represent more than half the algal cells
present. Their relative abundance was lowest at some of the open lake
stations, particularly toward the northern end. When diatom abundance was
low, the green algae usually were found to be high, and vice versa. The
other groups tended to remain at rather low levels except for an occasional
peak in the blue-green's and dinoflagellates, but these peaks seldom repre-
sented more than 50% of total phytoplankton. Since phytoplankton abundance
can rise and fall rather quickly, and since samples from different stations
in this study were widely spaced in time, even within a single cruise, it is
unwise to draw any more detailed conclusions from this data."
Copeland and Ayers34 interpret zooplankton data obtained during
lakewide sampling in the following manner. "Comparison of the zooplankton
data with other studies is particularly difficult because of differences in
sampling techniques and schedules used by various investigators. The list
of species present was as expected, and few anomalies were present in their
relative abundance. Either the Calanoid copepods (especially Diaptomus) or
the Cyclopoid copepods were usually the most abundant group, although they
were outnumbered in a few samples by Daphnia. Total zooplankton abun-
dance fluctuated greatly from sample to sample, and no clear temporal or
geographic trends could be seen."
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3. Periphyton
"Periphyton are defined as the complex assemblage of aquatic
organisms, especially green and blue-green filamentous algae, that grow
attached to permanent substrates such as rocks, logs, steel pilings, etc. in
shoreline areas. In addition to the larger algae, there are less obvious
diatoms, many bacteria, protozoa, and invertebrate animals which constitute
the periphyton community. Under normal conditions periphytic growth is
considered to be beneficial because it is a food source to many fish or fish
food organisms. Some of the bottom feeding fish, such as carp and suckers,
will browse directly on the filamentous algae. Forage fish feed on the proto-
zoa and invertebrates. As the algae die and decompose, the organic material
released becomes nutrients for other algae and invertebrates, all of which
constitute the aquatic food chain of the littoral area.
"It is only when the periphyton growth exceeds the rate at which
fish and invertebrates can assimilate it into the normal food chain that the
growth becomes excessive and a nuisance. Excessive growth can create
problems, both aesthetically and practically, when the filamentous algae
break away and float onto beaches to decay, enter municipal waterworks, or
clog equipment maintained in the lake."74
Periphyton samples, collected from natural substrates in the
Zion area in 1969 (no month given), indicated that the filamentous green
algae, Cladophora, was the most common organism in the periphyton
community.
A more thorough study74 summarizes the results of periphyton
samples collected from April 1970 to March 1971 from both permanent and
artificial substrates near the Zion Station and the Waukegan Station. Peri-
phyton growth was measured from May until November, at which time a
combination of ice, water temperature less than 50°F, and stormy weather
inhibited growth.
Permanent substrate growths were characterized by the cold-
water genera Ulothrix and Stigeoclonium in the spring and Cladophora in
the summer. Cladophora glomerata dominated during July and August and
was found on most substrates through October, at which time Ulothrix zonata
reappeared. The appearance and disappearance of diatoms and blue-green
algae had no such clear-cut trend.74
The cold-water genera Ulothrix and Stigeoclonium grew abun-
dantly on artificial substrates before the appearance of Cladophora.
Cladophora first appeared on the artificial substrates at Zion in June, be-
came abundant in July, and disappeared in August. Ulothrix was the most
abundant green algae in the Zion area from August through November.74
The Waukegan intake supported Cladophora during July and August, although
it was not abundant.
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Cladophora persisted on the permanent substrates until October,
• but its growth on the artificial substrates occurred only during July and
August. This differential persistence demonstrated the value of studying
both substrates.74
Abundant diatom growth of several species occurred near Zion
during the entire sampling period. In contrast, abundant growth at the
Waukegan intake occurred only during spring and summer months and was
limited primarily to two species. The data indicate that diatoms have a
limiting upper temperature for maximum growth between 55 and 70°F, with
a sharp inhibition at temperatures above 70°F.74
The Zion area did not support abundant blue-green algae growth
during any season. Abundant growth in the Waukegan intake was restricted
to the period from July to October. The report postulated that blue-green
algae growth is not expected to increase near Zion after startup because the
underwater, offshore discharge is designed to prevent warm water from
reaching the nearshore substrates suitable for periphyton growth.
Chlorophyl _a and biomass data indicate the largest amount of
periphyton growth on artificial substrates was supported in the Waukegan
intake canal during August and September. The water temperatures were
between 67 and 70°F. After September, periphyton growth was greater on
artificial substrates in the Zion area. Except for an early October chloro-
phyl a analysis, the late September to November growth near Zion was sig-
nificantly larger than growth in the warmer waters near Waukegan.
Diatoms were the most abundant form of periphyton in the
Kewaunee and Point Beach areas. Fragilaria was the most abundant diatom
represented by nine species. F. vaucheriae was the most abundant species
in studies using plexiglass substrates,126"128'131"133 whereas samples from
natural substrates near Kewaunee in 1971 showed _F. vaucheriae to be in
low abundance.70 The difference was most likely attributed to the different
substrates, (in general, there is a lack of permanent substrates along the
shoreline in that area.)
Bio-Test studies70 reported periphyton samples taken from
•wooden pilings and riprap contained strands of filamentous green and blue-
green algae intermixed with several species of diatoms. The most obvious
species of filamentous green algae was Ulothrix zonata, which was more
abundant in May and November than in August. (The University of Wisconsin
studies were limited to periphytic diatoms.)
There are few results of periphyton studies to report for 1970-
1971 that are specific to the southeastern shore of Lake Michigan. Two
periphyton samples were obtained from a 6-ft-deep, plastic, subsurface
float in October 1969.5 The samples were only qualitatively examined to
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determine the dominant periphyton types in the Cook Plant area in the fall.
The periphyton were very sparse and were dominated by diatoms of the
genera Gomphonema, Nitzschia, Synedra, Achnanthes, and Cymbella. The
dominant diatom was Gomphonema sp., though Melosira varians was also
quite abundant. One green algae, Stigeoclonium, was present in some num-
bers. No Cladophora was present.
A very brief tabulation of the dry weight per square meter of
approximately one month's growth of periphyton in the Palisades area, dur-
ing May-August 1969, is given in Ref. 30. No species identification is
reported.
Periphyton samples were obtained at the Bailly Station site in
September and October 1970. These data were taken in the presence of the
thermal discharge from the existing Bailly Plant and therefore will be dis-
cussed in Section III below.
4. Benthos
In April 1968 and August, October, and December 1969, bottom
organisms were collected off Zion at offshore distances out to 5600 ft.
The 1969 samples were generally similar in composition to the samples
collected and reported by Beer and Pipes in April 1968.13 The benthic or-
ganisms found in the Zion area were generally dominated by crustaceans,
but oligochaete worms were most numerous in the shallower areas. The
fingernail clams (Pelecypoda), Sphaeriidae, and the snails (Gastropoda)
usually composed less than 15% of the benthos found.26
In depths shallower than 10 ft, benthic populations at Zion were
almost nonexistent, probably as the result of scouring by wave action and
the frequent shifting of bottom sediments. At depths of 10-20 ft, oligo-
chaetes (aquatic worms) became the most abundant organism. Tubificids
were the most abundant shallow-water species, and Stylodrilus heringianus
was reported as the most abundant deeper-water species. In waters deeper
than 20 ft, the burro-wing amphipod, Pontoporeia affinis, became the domi-
nant benthic representative.2
Samples obtained at Zion from April through December 1970
showed the benthic populations peaking (approximately tripling) during July
and August, because of reproduction, and then slowly declining during the
fall months. Pontoporeia affinis was the dominant organism, accounting for
50-83.4% of the total population. Oligochaete worms, midges (Chironimidae),
and fingernail clams (Sphaeriidae) ranked second, third, and fourth,
respectively.
Samples obtained during 1971 confirmed crustaceans (Ponto-
poreia affinis) as the most abundant benthic organism, with population
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29
densities similar to those of 1970. Oligochaetes, consisting primarily of
tubificids, composed the second most abundant category, with fingernail
clams third. Snails and insect larvae together composed only about 10% of
the total benthos. The tubificid population density was somewhat higher in
1971 than in 1970. The total benthic population densities varied among vari-
ous sampling areas, but no clear trends were apparent throughout the year. 9
Low numbers of benthos were collected during 1971, at depths
less than 20 ft, from the clay and rock substratum that underlies the shallow
waters near Kewaunee. Chironomidae (midge larvae) was the predominant
group of organisms, probably because of its ability to construct cases and
avoid being swept away by wave action. Different chironomid genera, with
the exception of Heterotrissocladius, were observed each season.70
Reference 121 cites (without reference) a brief study of the ben-
thos at Point Beach in 1968: "The Point Beach benthos was so depauperate
that use of benthic organisms as indicators (for long range environmental
effects) was abandoned."
Benthic samples were obtained at the Point Beach Power Plant
at monthly intervals, from May through August 1971 by Argonne National
Laboratory.109 The samples, obtained from depths of less than 40 ft, con-
firmed that the benthic population was very sparse. Unlike the conditions
at Kewaunee, the most common organism collected was the amphipod,
Pontoporeia affinis, with population densities of 0-100 organisms/m2. This
density is extremely low compared to data from Zion, where population
densities ranged from 4000 to 16,000/m2 (Ref. 77).
Bottom samples for benthic invertebrates were collected in the
Palisades area from May 1968 to October 1970.30 The benthic samples were
typical of those found in Lake Michigan, the major taxonomic groups being
amphipods (primarily Pontoporeia sp.), aquatic earthworms (Oligochaeta),
freshwater clams (Sphaeriidae), aquatic insects (primarily Chironomidae),
flatworms ( Turbellaria), leeches (Hirudinea), and hydra (Coelenterata).
Densities of the amphipods, oligochaetes and pelecypods increased with in-
creasing depth. Chironomidae were the predominant organisms at depths
less than 20 ft.119
The abundance of benthic organisms was low in the Bailly region,
as compared with other aquatic life in Lake Michigan. Of the organisms
present during September and October 1970, oligochaete worms (Tubificidae),
comprised 52% of the total benthic organisms. Most of the species of oligo-
chaetes present were characteristic of eutrophic, but not grossly polluted,
waters. The two genera of midge larvae present, Chironomus and
Cryptochironomus, are characteristically found in eutrophic and polluted
sediments. The amphipod, Pontoporeia affinis, is a cold-water form and
found only at the station in deepest water.91
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30
Ayers found that limited sampling for benthos in the Cook Plant
area, during 1969 and part of 1970, was difficult to interpret.5 In a report7 .
on the initial phase of a large-scale sampling program at the Cook site on
July 1970, he concluded the benthic macrofauna increased strongly with depth
between 15 and 80 ft. Chironomids were present in low abundance over much
of the area and dominated the benthos in depths less than about 20 ft.5
Reference 34 summarizes lakewide benthos data acquired during
1969 and 1970 in the following way. "The benthos samples were also about
as expected from previous studies. In most cases, total benthos abundance
was between 1000-5000 organisms per square meter, but it occasionally was
much higher. Only 3 stations (Sheboygan, Zion, and 20 miles southeast of
Waukegan) had very high benthos abundance, and even these had more nor-
mal abundance on at least one cruise. Beeton, in reviewing the work of
other investigators, mentioned that the proportions of amphipods and oligo-
chaetes reported in the fauna had shifted from 48/39% respectively to
65/24% between 1931-32 and 1963-64. In the present samples, however, the
proportion was nearer to the earlier figures stated above than to the latter.
This may be due in part to selection against small forms, especially oligo-
chaetes, by the sampling and sorting process used on the present study."
The lack of benthos in the inshore areas of Lake Michigan was
confirmed by Copeland and Ayers in their description of changes in their
sampling locations. The station at the Kewaunee Nuclear Plant was moved
to 3.5 miles offshore because at 1 mile the sediments were hard and un-
sampleable with little or no benthos; the Point Beach Station was moved to
4 miles offshore for these same reasons; the Bailly Nuclear Plant station
was moved to 2 miles offshore because, while the sediment was sampleable,
there was little or no benthos.
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over the period of record (1965-1969). These maximums occurred some-
time in the summer when river-water temperatures are naturally higher
than the lake temperatures. The river inputs -would be relatively smaller
on an average basis.
Thus Fig. 3 visually contrasts peak plume areas associated with
natural and manmade thermal discharges to the lake. In some situations,
municipal, industrial, and power-plant heated effluents are discharged to
a river that is a tributary to Lake Michigan. Under these circumstances,
it was not possible to separate the contributions of each source to the
plume area shown in the figure. Each of these situations is marked with
an asterisk. The power-plant sources have been singled out by name;
other sources have been designated by the fact that they are municipal (M),
industrial (I), natural (R), or combinations of these sources. The numbers
refer to the radius of the semicircles, in feet, that have the same areas as
the thermal plumes they represent.
1 . Field Data
An observation of the sinking-plume phenomena at the
Point Beach Plant was reported by Hoglund and Spigarelli.59 Temperature
recorders were placed on the bottom of Lake Michigan near the plant dis-
charge. Analysis of the data revealed that the discharge water interacted
•with the lake bottom as long as the ambient lake temperature was 39.2°F
or less. When the ambient lake temperature exceeded 39.2°F, there was
little indication of temperature perturbations on the bottom as a result of
the thermal discharge. The data are presented in terms of the percentage
of the time the various recorders were influenced by the plume. The pos-
sible biological implications of this work are discussed later in this section.
Ten thermal plumes have been mapped at the Waukegan Plant
by Industrial Bio-Test Laboratories over a period from February 21, 1970,
to June 2, 1971.66-68 Tne plume data were obtained by boat transverses,
vertical profiles being taken at stationary boat locations. Data locations
•were determined using boat radar equipped with a variable-range finder.
Wet- and dry-bulb air temperatures -were acquired, along with ambient
•wind direction and speed. Power-plant factors such as plant electrical
loading, condenser -water flow, and intake and discharge temperatures were
also obtained. The data were presented in graphical form generally -with
horizontal sections showing isotemperature contours. In most instances,
vertical cross sections of the plume also showing isotherms were provided.
The plumes were obtained on the following dates: February 21, 1971 (shows
sinking-plume phenomena); April 23, 1970; May 19, 1970; May 27, 1970;
August 24, 1970; September 30, 1970; October 21, 1970; November 11, 1970;
February 16, 1971 (sinking plume); and June 2, 1971 (cooperative field day).
The Bio-Test authors have summarized their field investiga-
tions by indicating that the Waukegan plumes are quite variable in size,
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34
configuration, and general characteristics, and are most influenced by wind
and wind-induced currents. They observed that the plumes appeared to re-.
spond quickly to wind-induced current movement and were principally di-
rected in a downwind direction. They stated that the outer perimeters of
the plumes were found difficult to locate, mainly because of the tempera-
ture variability of the ambient water. They stated further that the heated
effluent affects the lake-bottom temperature only a short distance from the
outfall, except when the wind blows parallel to the shore or slightly onshore,
causing the plume to remain in shallow water close to the shore. Heated
water -was found to extend more than a mile down-wind on such occasions
with a strong along-shore breeze.
The heated-plume water was stated to rise quite rapidly after
the initial momentum of the discharge velocity •was reduced. When winter
lake ambient temperatures were either at or near freezing, the plume was
stated to sink to the lake bottom and to spread over the floor. It was found,
however, that the plume mixed with the ambient water quite rapidly under
these conditions.
Consumers Power Company has available two documents sum-
marizing 1970 and 1971 in-house thermal-plume temperature surveys per-
formed at various company plants throughout Michigan.31'32 Of particular
interest are those studies relating to plants on Lake Michigan. The 1970
field surveys consisted of making temperature measurements at various
water depths throughout an established grid of marker buoys in the survey
area. The temperatures acquired were plotted as a function of position for
particular depth levels, and isotemperature contours were then drawn.
Power-plant operating data in the form of plant electrical output, condenser
cooling-water flows, and cooling-water intake and discharge temperatures
were recorded. Ambient wind speed and direction, air temperature, and
relative humidity were the atmospheric variables recorded.
Three temperature surveys were performed at the J. H. Campbell
plant on July 10, August 26, and September 9, 1970. Only water surface
temperatures were measured on these three field days. On September 9,
vertical temperature measurements were additionally made at five stations.
Two temperature surveys were performed at the B. C. Cobb plant, located
on Muskegon Lake, which empties into Lake Michigan. The surveys were
made on July 16 and July 17.
The 1971 field surveys were somewhat more extensive in that
the surveys also included water chemical sampling and drift-bottle studies.
The water sampling results were not included in the report. Three field
studies were performed at the Big Rock Point Plant: June 30, July 1, and
July 2, 1971. Six field studies were made at the J. H. Campbell Plant:
June 17, June 18, July 7, July 8, August 3, and August 4, 1971. Five studies
were made at the B. C. Cobb Plant: June 23, June 24, June 25, August 5,
and August 6, 1971 .
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35
In a brief summary of these plume measurements, the report
stated that the heated-plume water was buoyant and spread into relatively
thin layers on the surface of the receiving waters. The extent of mixing
with adjacent waters was stated not to be well defined; however, it appeared
that maximum mixing occurred after the plume had cooled down to within
5.4°F of the ambient receiving water.
A compilation of 1971 field data gathered by Argonne National
Laboratory relating to physical measurements of thermal discharges for
several power plants sited on the lake have been reported by Frigo and
Frye.51 The field investigations basically consisted of temperature, water
current, and meteorological measurements. Water temperatures were
measured by boat using a submerged boom with probes attached at various
depths.
Ambient water current and meteorological information consist-
ing of wet- and dry-bulb air temperatures, and wind speed and direction
were typically recorded for each plume investigation. Power-plant operat-
ing data were acquired from utility personnel. The report also describes
plume measurements made using airborne infrared imagery techniques. A
study of the sinking-plume phenomenon was also described.
Plume measurements were made at the Point Beach Plant dur-
ing March and April (sinking-plume study), on May ZO, June 25, and July 20;
two plumes on July 21 and August 31; two plumes and an airborne infrared
imagery study on September 1; two plumes on October 28; and a near-field
jet study on November 3, 1971. Two plume measurements were made at
the Waukegan Plant on June 2. This -was part of a cooperative field effort
and is described separately in this section. Plume data were also obtained
at the State Line Plant on August 4 as part of another cooperative effort.
Most of the data obtained at the various plant sites -were reported in graphi-
cal form. The figures present horizontal and vertical plume sections with
isotherms drawn on 1°C intervals. The authors indicated that the datawould
be used as input to analytical modeling efforts within their organization.
A joint field day was conducted at the Waukegan Plant on June 2,
1971, to compare, among other things, various plume measurement tech-
niques. The results showed rather remarkable agreement between plume
isotherms measured by two different organizations using in situ measure-
ments obtained from moving boats. An airborne infrared mapping of the
plume was only in fair agreement with the other two after the infrared data
were corrected to account for plume-measurement time differences.
Thermal-plume temperature studies (September 19 and Octo-
ber 28, 1970) were reported on for the Bailly Power Station.91 The tem-
perature measurements were made by taking surface and vertical temperature
profiles at numerous offshore sampling positions in the lake. Meteorological
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36
parameters such as •wind speed and direction, cloud cover, air temperature,
and relative humidity •were recorded in addition to the plant operating pa-_
rameters of electrical output, cooling water flows, and cooling water intake
and discharge temperatures. The data were presented in conventional iso-
therm plots, but for the surface isotherms only.
Scarpace and Green have reported on a series of studies using
airborne infrared imagery techniques to map thermal plumes at the
Point Beach and Edgewater Power Plants.105 In this preliminary reporting
they pointed out a rather interesting and apparently not uncommon plume
phenomenon •which is readily apparent in an infrared image of the Point Beach
plume shown in Fig. 4. The discharge temperature during infrared mapping
was stated to be 78.3°F; the intake on the ambient -water temperature was
6l.5°F. Thus the darker areas -within the figure represent higher tempera-
ture conditions. The authors attribute the wavelike patterns to "thermal
fronts" moving out-ward from the discharge since they have thermal pictures
of the plume every 5 min and can therefore follow frontal motion.
The authors also noticed cyclic temperature oscillations at a
fixed location within the Point Beach plume at a depth of 9 ft. Although it
was not stated whether these in situ measurements were made concurrently
•with the infrared measurements, the authors believed that such bulk-
temperature oscillations suggest that the thermal fronts are not just a sur-
face phenomenon. Infrared techniques would measure only the temperature
of the first tens of microns of the surface •water.
In a more recent paper,106 Scarpace and Green discuss additional
infrared plume measurements made at the Point Beach Plant between Sep-
tember 14 and 17, 1971, and additionally speculate on plausible explanations
for the presence of the thermal fronts. Apparently the fronts seem to be
the strongest in very calm weather and are not evident during high-sea ob-
servations. The strength of the fronts seems to vary from day to day.
Horizontal plume temperature gradients larger than 0.9°F/ft -were said to
be observed with frontal motion. It -was also observed that secondary waves
•were superimposed on the thermal fronts. The secondary waves were dis-
covered with near-infrared photographs; they were just barely visible with the
infrared imagery. Explanations for the secondary waves were also discus sed .
In summary, the authors felt that the presence of moving ther-
mal fronts adds a significant dimension to the already complicated biological
and physical aspects of heated discharges.
A comprehensive infrared study of three power -plant sites on
Lake Michigan was reported on by Stewart, Brown, and Polcyn.110 The
broad purpose of the study -was to conduct multispectral diurnal surveys
of power -plant effluents into Lake Michigan and to investigate, where pos-
sible, the various effects and interactions between these plumes and the
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37
CO 4-1
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38
natural ecology of the lake. Specifically, the report furnished (a) plume
imagery data, (b) an analysis of imagery gathered on growth and movement.
of the thermal bar, (c) a study of wind effects on plume distribution, and
(d) a study of the relationship between the thermal bar, natural river out-
falls, and power-plant discharges.
Infrared scans -were made on the J. H. Campbell Plant on
April 22, 23, and 30 and May 28, 1971. The data showed extreme plume
variability, dependent on wind speed and direction and wind history. Com-
plete plume reversals -within a 2-hr period were noted; subtle changes were
noticed in a span of 25 min.
The Michigan City Plant was studied on April 23, April 30,
May 7, and May 28, 1971. The smallest plume occurred on the day of the
strongest winds. A wave pattern in the April 23 data was noticed. (These
"waves" looked much like the thermal fronts described by Ref. 106.)
The Bailly Plant was investigated on April 23, April 30, May 7,
and May 28, 1971. The April 23 data shows some thermal-wave-pattern
structure in the plume.
Some of the imagery data for the plants were presented in three
unique forms as a result of computer analysis of the data. In one form the
plumes were shown contoured into discrete temperature contour bands, the
sum of these bands representing a mosaic for the entire plume. The sec-
ond display form involved color-coded temperature contours. The third
display form involved the use of computer symbol signatures combined with
color overlays to denote the temperature contours. The data results were
also tabulated to provide plume areas for a particular 1 °F temperature
interval.
A bibliography of thermal-plume field investigations conducted
on large lakes was reported on by Tokar.114 This report was a state-of-
the-art survey, which attempted to identify existing thermal-plume field
data that could be used to support or verify analytical plume-modeling ef-
forts associated with heated-water discharges into the Great Lakes. The
report is somewhat dated in that most of the reviewed plume data, with a
few exceptions, were of a 1970 origin or earlier. Nevertheless, much of
what the report concluded on the plume field investigations up to 1970 is
perhaps appropriate even to this date.
The author concluded that the major difficulties associated with
using existing field data for validating or improving analytical predictive
methods are: (a) The transient nature of the plumes makes it difficult to
obtain truly characteristic data by normal techniques, (b) Many partial
investigations of thermal plumes are being performed by a number of
groups, often at the same location. Dilution of effort appears to be common.
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39
(c) Different mathematical models require different kinds of data, so that
data that are sufficient for one study may not be sufficient for another.
The report also provided an inventory of all the major power
plants sited on the Great Lakes and information indicating plant siting in
terms of electrical output versus state and lake distribution.
2. Mathematical Modeling
In two reports, one by Asbury and Frigo4 and the other by
Frigo,53 thermal-plume field data were used to develop and validate a sim-
ple phenomenological relationship for predicting the surface areas of ther-
mal plumes in lakes. According to the authors, the relationship they obtained
represents a useful rule of thumb for predicting surface areas of buoyant
plumes from surface discharges. The actual relationship was presented
as an eyeball data fit on log-log graph paper.
An analytical expression for the data of Asbury and Frigo was
obtained by Elliott and Harkness43 using a least-squares fit. Their rela-
tionship is
— = 1.0 - 0.456
where 8 and 90 are the plume excess temperatures at any point within the
plume and at the immediate point of discharge, respectively, A is the total
area, in square feet, of the plume up to the 8 excess isotherm, and Q is
the volumetric discharge rate, in cubic feet per second, of the cooling water.
In Ref. 53, Frigo correlated much of Argonne National
Laboratory's 1971 plume field data, taken at various Lake Michigan-sited
power plants, with the phenomenological model. All the new data fell within
the data scatter envelope of the phenomenological relationship, and it was
concluded that the validity of the relationship was further strengthened.
A state-of-the-art report concerning the mathematical model-
ing of thermal discharges into large lakes was reported on by Policastro
and Tokar.92 Sixteen analytical models were critically reviewed discussing
individual model treatment of geometric, kinematic, hydrodynamic, and
thermodynamic variables. The models reviewed did not represent all of
those that could be used for lake applications. Therefore a bibliography of
other models holding potential merit in this regard was also included. One
of the models reviewed has been used to make plume temperature predic-
tions for the Zion Station discharges into Lake Michigan. All the material
in the report is highly technical, including its six pages of conclusions and
observations.
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40
A -workbook containing computational procedures in the form
of nomograms for estimating the temperature distribution and physical
spread of heated discharges originating from submerged discharges has
been authored by Shirazi and Davis.108
3. Hydraulic Modeling
Hydraulic-model studies of the proposed Zion Station Unit 1 dis-
charge have been made by the Alden Laboratories.26'78 The purpose of
these studies was to determine the temperature-dilution patterns and ef-
fects of the condenser cooling -water discharge on Lake Michigan. The
model was adjusted and operated to reproduce prototype conditions at the
point of discharge. The test facility and test procedures were designed to
simulate field conditions expected at both Zion discharge structures. The
tests -were conducted for a variety of conditions of lake depth and flow.
The test results were presented in pictorial form showing water -temperature
distributions in the vicinity of the discharge in plan and vertical views.
The analytical-plume-modeling efforts for the Zion Station are
also given in Ref. 26. Together they form a complementary set of data and
are discussed in relation to each other in testimony given at the Illinois
Pollution Control Board Hearings on January 24, 1972, by D. W. Pritchard."
Dr. Pritchard pointed out that the analytical-modeling results overestimated
plume lengths in relation to the hydraulic-modeling results for the higher
excess isotherms. For lower excess temperatures (<9°F), the two forms
of modeling were said to be in complete agreement. The plume areas pre-
dicted by the two modeling techniques show the analytical method to predict
larger areas by a factor of 1.65.
Alden Laboratories have also performed hydraulic-modeling
studies for the D. C. Cook Plant.64 An undistorted model was used -with a
1/75-scale ratio to model the discharge region as accurately as possible.
The experimental features of the tank limited the hydraulic-modeling re-
sults to the equivalent of 4000 ft in either direction along the shore and out
to 4000 ft offshore. Preliminary trials indicated that the 3°F excess iso-
therm (used in water-quality regulations) could not be closed within the
tank, so analytical procedures were used to complete the task. Most of the
information gathered thus far was performed on the basis of the discharge
structures using three discharge slots. Tests are currently being per-
formed on the basis of using two slots per discharge.
4. Effects on Shoreline Ice
The main source of information on shore ice development and
destruction, and on the potential effects of thermal discharges on this ice,
is work by Ayers.8 During the winters of 1969-70 and 1970-71, aerial
photographic ice-reconnaissance surveys of the entire shoreline of
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41
Lake Michigan were performed to observe and photograph the alongshore
ice and open-water areas in the vicinity of nuclear and fossil-fuel power
plants. On-foot photographic records of the shore ice conditions -were ob-
tained at the Cook Plant site and at the sites of existing thermal discharges.
As a result of these activities, Ayers has derived abundant evi-
dence that the shore ice along the Lake Michigan shore has a complex
structure called "the storm icefoot, lagoon, and outer barrier." The method
of formation and details of this compound structure are discussed in Ref. 8.
Ayers et al. state that evidence from two winters of ice studies
"does not show that discharges of waste heat cause extensive melting of
shore ice with the resulting exposure of the beaches to wave erosion. In-
stead, the data show that the usual outfall structure, a sheet-pile flume
leading out into the water, will have shore ice continuing up to the very
sides of the flume ... (However) At Campbell there has been, both "winters,
a considerable area of shore ice melted, but beach erosion has not been
evident."8
Using an analysis of lake currents and wind -direction patterns,
Ayers et al. concluded that during two-thirds of the winter the Cook Plant
plume "will not have significant contact with the shore ice and the natural
processes of ice-building and ice-destruction will be in control. "The
Cook Plant thermal plume appears, at this time, to be an ice-destructive
force potentially operative about a third of the time in winter. During this
time it will be a destructive force wandering randomly along the shore,
staying in contact with the shore ice for very limited periods at any local
point. Since its ice destructive force will always be preceded and followed
by the natural forces of ice-building and ice-de struction, we conclude that
the effect of the Cook plume on local shore ice will be only a limited dimi-
nution in the amount of ice present."8
B. Biological Characteristics
Coutant36 summarized the concern about thermal discharges as
follows:
"We visualize the power plant as a large artificial predator acting
on these populations. Our opinion has been molded by laboratory experi-
ments which have shown that thermal shocks may lead to death or induce
secondary effects that ultimately affect survival of the organism or its
population. We may fail to realize, however, that these devastating results
are not obligatory in the entrainment process. Rather, they occur only as
a result of specific combinations of temperature and duration of exposure."
This section describes studies performed and testimonies presented
that are relevant to these effects of "temperature and duration of exposure"
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42
on aquatic organisms. Many of these organisms are of immediate impor-
tance to man through commercial fisheries, sport fisheries, or biological
nuisances.119 Others are important as food-chain contributors to those
species of more direct interest. Still others are important components of
the entire ecosystem, -without which other processes in the lake could not
proceed.119
A division was made in this report between thermal-plume effects
and intake and discharge effects. Problems with fish kills on intake screens
and mechanical damage due to pumping -were easily relegated to the section
on intakes and discharges. However, some of the temperature-related ef-
fects, such as periphyton growth and fish behavior, were not clearly sepa-
rable into the specific sections. Thus, a somewhat arbitrary decision was
made to describe those studies that were performed primarily in the intake
or discharge in the section on Intake and Discharge Effects. Those studies
that included lake measurements as well as intake and discharge measure-
ments are reported here.
1 . Waukegan Power Plant
A number of studies of the biological effects of thermal dis-
charges have been undertaken by the Bio-Test Laboratories for Common-
wealth Edison. The studies use the heated discharge of the Waukegan
power plant.
Following preliminary studies in 1968, reported by Beer and
Pipes,13 fish collections were made near the Waukegan and Zion areas
from March through October 1970. Thirteen species were taken in the
Waukegan area and 1 7 in the Zion area. The most dominant fish were
alewife, smelt, spottail shiner, chub, and yellow perch. The data indicated
that alewives seemed to prefer the warm discharge water throughout the
test period; the coho salmon seemed to prefer it only during the spring.
During 1971, alewives were again the most abundant in the
sampling area, with very large concentrations in the discharge during
August and September. A heavy concentration of adult spottail shiners
was observed in the Waukegan discharge in June, but no young-of-the-year
were taken in subsequent samples.
Fish that were present throughout the year in both the Waukegan
intake and discharge canals were carp, goldfish, and white suckers. Sport
fish taken during early spring and late fall included brown trout, rainbow
trout, and coho salmon. They were found mainly in the intake canal, though
a few were captured in the discharge.72
Phytoplankton samples taken in May to September 1970 indicated
no significant differences in total population densities between the intake and
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43
discharge canals. Offshore densities were somewhat lower than the canal
densities. Diversity and evenness indexes showed little difference among
populations in the intake, discharge, and offshore during the sampling pe-
riod.28 These results were essentially confirmed during the 1971 studies.72
Monthly sampling of zooplankton in and out of the Waukegan
plume was carried out from June through October 1970. Generally, there
were more organisms inside than outside the plume.
Ayers6 conducted studies at the Waukegan Station on June 30,
1969 (intake temperature, 55°F; outfall temperature, 6l.9°F), and found an
apparent phytoplankton kill of 10%. There was no evidence of heat-stimulated
recovery in the near region of the plume. The population-density ratio,
with respect to a station 2000 ft from the outfall, was 0.6:1.6
The zooplankton numbers indicated similar trends with the pop-
ulation density reduced 15% at the outfall and a ratio (plume/outfall) of
0.2:1 at 2000 ft.6
"In summary, the biological data show kill-off of both phytoplank-
ton and zooplankton in passage through the plant. In both types of plankton
there appears to have been continuation of die-off between the outfall and
the nearby portion of the plume. Benthos results showed nothing attribut-
able to the plant except bottom scour due to currents in the intake and
outfall."6
2. Point Beach Power Plant
The plankton, periphyton, and benthos communities of inshore
waters "were sampled near the Point Beach Nuclear Plant by Argonne
National Laboratory, during 1971, to determine the biological effects of the
thermal discharge.109 With respect to phytoplankton, it was concluded from
vertical tows for plankton that no significant differences existed between
plume and nonplume water in terms of plankton biomass. However, fluoro-
metric analysis of phytoplankton samples showed considerable variation
in chlorophyl a concentration (proportional to phytoplankton productivity)
at the sampling stations. Initially (nearest the discharge), there seemed
to be an inhibition in chlorophyl _a. Approximately 1400 ft from the dis-
charge an increase had occurred, and at greater distances the levels de-
creased to near ambient concentrations. A significant increase in
chlorophyl a concentration was observed in the plume in July, when an up-
welling resulted in elevated nutrient concentration.
With respect to periphyton, its growth was significantly greater
at the three stations nearest the discharge. Growth at all other stations
was similar to that at the control areas. Periphyton productivity, as meas-
ured by 14C uptake, was significantly higher at a station 5000 ft from the
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44
discharge than at the control station and at a station nearer the discharge.
The elevated temperature near the discharge apparently did not stimulate .
periphyton production during the period of the study.
Fish were routinely collected by Argonne National Laboratory102
from several locations, including the discharge canal, the beach zone near
the discharge, and a control beach zone approximately 2 miles north of the
Point Beach plant. Hand seining was used in the shallow beach zones, and
scuba divers speared large fish in the discharge canal. This sampling dis-
closed that during the summer months of May through July, alewives were
the most abundant fish in the discharge canal and the beach zone. Dense
schools were observed in the discharge canal and often out into the lake as
far as 150 yards from the discharge. Carp were the most commonly ob-
served fish, both in the discharge and beach zones. Schools of 10-30 fish
swam in and out of the discharge canal along the sides and bottom through
temperature gradients of up to 18 F. Suckers were observed each time
divers entered the discharge (June-September). Smallmouth bass of vari-
ous sizes were observed only in the discharge. Trout and salmon were not
observed in the discharge channel during the higher-temperature periods
(>72°F). Trout and salmon also frequented the near-field plume region as
evidenced by good catches made by boat fishermen.
The spatial distribution of fish in and around a thermal plume
was observed by Argonne National Laboratory during tests to examine the
feasibility of acoustic fish-locating equipment. On October 28, 1971, si-
multaneous echo-sounding and temperature measurements were made as
a boat traversed through the Point Beach Nuclear Plant thermal plume.
Observations were made in daylight and after dark. The major difference
observed bet-ween the day and night runs was the presence of a large num-
ber of schools of fish during the day and the complete absence of schools
during the night. The number of individual fish observed at night is almost
seven times greater than during the day. In general, during both the day
and night series, the majority of fish (species unknown) were in -water less
than 55°F, and at no time were fish detected in plume water warmer than
59°F. Many fish, however, have been observed in the discharge canal in
much higher temperatures.103
An interesting study of the effect of thermal discharges on the
swimming patterns of coho salmon past the Point Beach Nuclear Plant has
been released by The University of Wisconsin - Madison.57 The fish were
tracked by underwater telemetry equipment and a special temperature-
sensitive ultrasonic transmitter attached externally to the fish. All fish
tracked in 1971 were adult coho salmon captured at Algoma, Wisconsin.
The fish were displaced 23 miles southward and released for tracking at
a point approximately 0.9 mile southeast of the Point Beach water-intake
structure.
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45
Preliminary analysis of the 1971 tracking data indicates that
three general patterns of movement were followed by the fish tracked in
the Point Beach area: 1) Five fish closely folio-wed the shore line and def-
initely did encounter the plume; 2) two fish swam approximately 0.3-
0.6 mile offshore and may or may not have come into contact with the
plume; and 3) four fish definitely did not encounter the plume.
Of the five fish that definitely contacted the thermal plume, two
made a course change of about 90° at a. point considered to be the location
of the plume interface and subsequently swam approximately parallel to the
interface. At the location of course change of these fish, the temperature
increase across the plume interface was from 52 to 59°F in the first case,
and from 55 to 61 °F in the second. A third fish twice encountered the plume
edge very near the hot -water -discharge structure, and upon each contact
changed swimming direction by 180°. The temperature rise across the
plume interface in this area -was from 59 to 70°F. The fish was swimming
northward at 1.6 ft per second. Immediately before first contacting the
plume, his speed increased to 2.5 fps. After first contact with the plume,
the fish changed direction and swam south, approximately 0.1 mile, at
0.8 fps. After turning northward again, he was swimming at 0.7 fps while
approaching the plume for a second time. After the second contact, the fish
swam 0.75 mile southward at 2 fps before turning north and approaching
the discharge area a third time. The transmitter signal was then lost after
the fish had been tracked to within 0.2 mile of the discharge structure. The
tracking signal was also lost from two other fish which had entered the
plume area before sufficient data on their behavior at the plume interface
could be obtained.
Of the other fish that encountered the plume, all four exhibited
a marked increase in swimming speed during the track segment immedi-
ately preceding contact with the plume. Three of these fish were lost in
the plume due to transmitter failure, but the fourth was tracked through the
plume. While passing through the plume, this fish decreased its swimming
speed slightly from 2.3 to 2 fps. Two of the fish that were among those lost
in the plume due to transmitter failure were later captured in their home
stream area (Algoma, Wis.) by sport fishermen.
The effect upon fish resulting from power -plant shutdowns dur-
ing emergency or normal situations were referred to briefly in Ref. 129.
It was stated that it was significant to note that operating experience for the
first six months at the Point Beach Station showed that with 20 shutdowns,
occurring primarily in the winter months, no fish are known to have been
killed and no other adverse effects were observed.
3. Blount Street Plant (Lake Monona)
A study to assess distributional responses of fishes to operation
of a power plant with once-through cooling on Lake Monona was reported by
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46
Neill and Magnuson.80 Integration of field and laboratory results suggested
that fishes were distributed within the outfall area according to their dif- .
ferent temperature preferences. Preferred temperatures of six
Lake Monona fishes were measured by allowing each of several specimens
to behaviorally regulate the temperature of its tank. The midpoint of the
preferred (laboratory-determined) temperature range agreed well with the
median body temperature of the fish as measured in the outfall area dur-
ing afternoon tests. For example, carp, 89.2 (laboratory)/87.1 °F (field);
blue gill, 86.5/84.9°F; large mouth bass, 84.4/85.5°F; black crappie, 82.9/
82.9°F; rock bass, 81 .1/81.5°F; and yellow perch, 74.1/80.8°F. (For yellow
perch, temperatures below 79.7°F were not available in the outfall area.)
Temperature was a major factor governing fish distribution in
that fish tended to be most abundant in that part of the habitat having tem-
peratures within the species-preferred range of temperature as determined
in the laboratory. Disparate distribution of some specific fish species of
different size resulted from the influence of factors other than size-related
differences in preferred temperature. For example, spatial segregation
between young and adults of two species, carp and yellow bass, probably
did not reflect size differences in preferred temperature. Adult carp were
concentrated in the outfall area during summer, but the young carp were
not, even though thermal regulatory behavior of young carp indicated that
they preferred temperatures between 86 and 92.3°F, temperatures avail-
able only in the outfall area. Young yellow bass avoided the outfall area;
larger yellow bass were relatively abundant there and were particularly
concentrated near the jets. Yet, large yellow bass stayed near the bottom
in water not much warmer than the reference areas where the young lived,
indicating that temperature alone was not the dominant factor. Water -
velocity effects were offered as one explanation for the above-mentioned
behavior. Explanations of this behavior were not offered in the report.80
Laboratory experiments80 with bluegills and yellow perch con-
firmed that fish may be attracted to food-rich environments, but suggested
that the attraction to food does not override the behavioral thermal regu-
lation. Provided an environment with the preferred temperature is avail-
able, the fraction of time spent in a food-rich environment is likely to
decrease abruptly as the temperature diverges from the preferred. Fishes
may, however, briefly foray from an environment offering the preferred
temperature, but not food, into cooler or •warmer (even lethally warm)
•water -where food is available.
4. Michigan City Station
Biological data were obtained from the intake, outfall, and sta-
tions 400 and 1000 ft from the outfall, at the Michigan City Station on
June 28, 1969.6 The temperatures were: intake, 64°F; outfall, 77.4°F. The
data indicated some kill-off of phytoplankters because the outfall population
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47
density was 14% less than that of the intake. Phytoplankton densities in the
plume were larger than those in the outfall. The ratio was Z.45:l at 400 ft
and 1.34:1 at 1000 ft. Some of the increase was associated with the blue-
green algae, Oscillatoria, and the yellow-brown alga Dinobryon, but the in-
vestigators could not tell if it was due to plant heat or to foreign -water
masses drifting in from the southwest.6
The zooplankton showed a decrease from intake to discharge of
2.9:1, and many dead or broken organisms were observed in the outfall
sample. Zooplankton densities in the plume, relative to the outfall, varied
from 5.3:1 to 0.2:1. As in the phytoplankton data, Ayers et al. were unsure
whether drifting water masses affected the data.6
The waste heat from the Michigan City Generating Station did
not appear to affect the benthic organisms.6
Table 4 summarizes direct measurements of the time required
for a plastic bag, nearly filled with water, to travel from the mouth of the
plant outfall to a point -where ambient lake temperature was reached.5 The
short duration of bag drifts was unexpected. Ayers et al. indicate that,
even in larger plumes, the duration of the greater than ambient tempera-
tures is probably too brief to trigger excess algae blooms.5
5. Bailly Plant
Field data were obtained on two days during September and
October 1970 at the Bailly Plant, located between Michigan City and Gary,
Indiana. The purpose was to compare samples of the pertinent biological
parameters obtained from the plume area and the adjacent ambient waters.
A summary of the results91 indicated higher concentrations of diatoms,
dinoflagellate s, and blue-green algae in samples taken from the warm water.
However, concentrations of golden-brown algae (other than diatoms) and
green algae were similar for samples both inside and outside the plume.
Concentrations of green algae increased with decreasing distance from
Burns Ditch. The growth was higher near shore than 4000 ft offshore.91
The periphyton showed greater concentrations of Cladophora
glomerata both within the thermal plume and in adjacent areas than in areas
along the southwest shore of the lake.91 Zooplankton were three to four
times more abundant within the thermal plume than outside it. In general,
most forms found in the plume are characteristic of eutrophic conditions.
The most abundant organism was the cladoceran, Daphnia retrocurva, fol-
lowed by the copepod, Eurytemora affinis. Individuals of these species
found within the plume were infested with fungus, -whereas those collected
outside did not exhibit any fungus.91
A large concentration of yellow perch were found in the plume
at the time of sampling. The intake/discharge temperatures -were 66/81°F
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48
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49
on September 19 and 52.3/66.Z°F on October 28, 1970. It was speculated
the fish may have been attracted by the greater abundance of zooplankton
in the region of the thermal plume.
6. J. H. Campbell Plant
A biological survey in the vicinity of the J. H. Campbell Plant
was performed by the Michigan Water Resources Commission during
August 11-13, 1970. The plant was operating with an intake temperature
of 63°F and a discharge temperature of 77°F. Bottom trawling for fish re-
vealed no consistent differences between plume and nonplume areas. Most
of the fish collected were young-of-the-year smelt. Yellow perch were
next in abundance.
Large amounts of filamentous green algae, Cladophora, were
collected in the trawl through the plume area. The origin of the algae was
unknown.
Plankton algae samples exhibited no gross numerical differences
or changes in community structure between the discharge and ambient
waters.116
Results from the benthic sampling indicated a statistically sig-
nificant increase in number of species found near the discharge canal. Al-
though there "was a slight increase in total population near the discharge
area, the population samples were not significantly different from the con-
trol points. It was speculated that the use of nutrient-laden water from the
Pigeon River, for cooling, may have caused the increase in species.116
It was concluded116 that the increased benthic productivity in
the plant's outfall was the only adverse effect that could be attributed to
the warm-water discharge.
7. Miscellaneous Studies
Several papers have been published during the last two years
that provide laboratory temperature-tolerance data for several
Lake Michigan fish. Edsall ej: jtL41 tested juvenile and young adult bloaters
for tolerance to high temperatures. The "ultimate" upper lethal tempera-
ture (the lethal temperature that cannot be increased by increasing the ac-
climation temperature) for the juvenile bloaters -was 80.1°F, slightly higher
than that for the young adult bloaters. The thermal tolerance of juvenile
bloaters was slightly less than that of brook trout, but higher than that of
other Salmonidae.
Brungs reported the exposure of fathead minnows to elevated
water temperatures of 78.8-93.2°F. He found that reproduction was more
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50
sensitive than survival, growth, or egg hatchability in assessing the effect of
temperature The number of eggs produced/female, the number of eggs/ ,
spawning, and the number of spawnings/female were gradually reduced at suc-
cessive temperatures above 74.3°F. No spawning or mortality occurred at
89.6°F which was the lowest temperature where growth was apparently reduced.
McCormick et al.82 studied the thermal requirements of cisco
larvae by determining growth rates, mortality, and net biomass gain as a
function of temperature. Temperatures between 55.4 and 64.4 F were rec-
ommended as most suitable for sustained production of larval cisco. The
24-hr median lethal temperature for ciscos acclimated to 37.4 F -was 67.6°F.
The avoidance mechanism, or selection of preferred tempera-
tures, as described above, was also illustrated in an experiment described
by Raney104 during testimony before the Michigan Water Resources
Commission. He cited one test in which six alewives, acclimated at 77 F,
chose 82°F water when given the choice between 74 and 82°F, and chose
80°F water when the alternative was 86°F. In a similar test, six other ale-
wives, acclimated at 77°F, chose 83°F water over 75°F water and then chose
80°F water when 86°F was the alternative. He said, "This illustrates the
expected reaction of a species, such as an alewife, if and when it comes
close to a heated plume."
Testimony by Lauer79 before the Michigan Water Resources
Commission included data related to several aspects of thermal effects on
lake biota. Concerning phytoplankton, experiments have shown the diatom,
Asterionella formosa, was capable of one division per day at 50°F and two
divisions per day at 68°F. Under optimum growing conditions, some algae
are capable of three generations per day. Most algae species studied have
a lethal temperature in the range of 91-113°F, the majority being near 111°F.
Diatoms that require cooler temperature (stenotherms) are generally most
sensitive to temperature change and can withstand an 18 F temperature
change.
Lauer79 stated that at none of 10 operating power plants had he
observed a discernible shift in species diversity resulting from the -water
temperature increase. He attributed this to the relatively short exposure
time of the organisms to the heated water.
The doubling time of zooplankton crustaceans such as copepods
and cladocera is very dependent on temperature.79 Doubling times of 0.2-
2 days have been observed for these organisms at temperatures of approxi-
mately 77°F. The population turnover rate (100% replacement by a new
crop) may be as rapid as 4 days or less at 77°F, and up to 22 days or longer
when temperatures are lower. Twenty-five of a 28% average loss per day
at summer temperatures has been observed to be due to predation. The
maximum temperature tolerance of the majority of zooplankton species
studied range between 86 and 95°F.
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51
Using lake-bottom temperatures measured continuously during
March and April 1971 during a study of the sinking-plume phenomenon at
'the Point Beach Plant, Hoglund and Spigarelli59 used the data of Colby and
Brooke25 to predict the hatching time of lake herring eggs subjected to the
observed temperatures during their incubation period. For the conditions
studied (2000 ft from discharge, 2 1 ft deep), the calculations predicted the
lake herring emergence would be advanced about 7 days as a result of ex-
posure to the sinking plume.
A rather significant development related to the problem of
power-plant design and site selection has been reported by Coutant. He
described steps being taken to develop quantitative mathematical predict-
ability of detrimental biological effects of thermal discharges. For instance,
a "survival nomogram" (a graphical representation of lethal temperatures
versus time, •with acclimation-temperature parameters) may be prepared
for many aquatic species for which sufficient data may be available. Then,
with the aid of a time-at-temperature graph, developed by analyzing the
velocities and temperatures an organism will experience while passing
through the plant and plume, one may determine if lethal conditions will be
experienced by the organism being studied. If this type of analysis is per-
formed during the design stage of the plant, then engineering changes that
affect the temperatures or velocities may be incorporated to minimize the
problem. For those who prefer the mathematical approach, these data are
easily converted to a set of regression equations.
With the acquisition of sufficient data related to sublethal effects,
such as equilibrium loss and increased susceptibility to predation, the meth-
od described above may be used to estimate the probability of these effects
or to design the plant to minimize them.
If accepted, this approach clearly defines the type of laboratory
and field data that must be acquired to make full use of its utility.
-------
52
IV. INTAKE AND DISCHARGE EFFECTS
A. Inventory of Designs
Summary operational data for most power plants on or in the prox-
imity to Lake Michigan can be found in either the Department of the Army,
Corps of Engineers, "Application for Permit to Discharge or Work in
Navigable Waters and their Tributaries-Eng Form 4345," or in the Federal
Power Commission's Statement Form, "Steam-Electric Plant Air and Water
Quality Control Data for the Year ended December 31, 1971, FPC Form 67."
Both of these forms contain fairly comprehensive submissions from the
various utilities concerning cooling-water operational data for their various
power plants.
The Army Corps permit application must be completed by any person
or entity seeking to directly or indirectly discharge or deposit refuse matter
into navigable waters or their tributaries. The policy has been to interpret
the discharge of waste heat as refuse, and, therefore, utilization of once-
through condenser cooling by electrical power-generating facilities requires
the submission of a corps application.
The FPC form contains information on air as well as water quality-
control data. The form must be completed for every steam-electric station
having a generating capacity of 25 MWe or greater that belongs to an elec-
trical utility system with a capacity equal to or greater than 150 MWe. It
is also required if the 25-MWe plant lies within a National Air Quality
Control Region, regardless of whether the facility is part of a larger
system.
Space limitations preclude the incorporation of the complete Corps
and FPC forms for all the major steam-electric power plants sited on or
next to the Lake. Only selected facts from these documents have been in-
cluded here to give the reader a perspective for the relative sizes between
the various individual operating plants and their respective cooling-water
requirements. Table 5 presents these selected data for those plants with
a 75-MWe nameplate rating or greater. The rationale for selecting the
75-MWe rating is suggested by EPA's specific cognizance of heated dis-
charges greater than 0.5 x 1 O9 Btu/hr. A 0.5 x 109-Btu/hr thermal-
discharge rate roughly corresponds to the waste-heat discharge from a
33% efficient, 75-MWe nuclear plant. Table 5 is not inclusive for yet
another reason. Heated effluents are being discharged into the Lake, either
directly or indirectly, by several industrial facilities such as U.S. Steel
South Works in Chicago, Inland Steel, Youngstown Steel, American Oil,
Union Carbide, and others in the industrial sectors along the Indiana
shoreline.
-------
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58
To better understand the mechanisms of power-plant cooling, the
current design features of the cooling systems for five major nuclear
power plants sited on Lake Michigan will now be described.
1. Kewaunee Plant Cooling System
The condenser cooling-water system for the Kewaunee Plant
is shown schematically in Fig. 5. Briefly, the cooling water is withdrawn
from the lake at three intake ports located about 14 ft below the lake sur-
face. Steel trash grills with 1-ft-square openings are installed above the
intake openings to prevent large debris from entering the system. In addi-
tion, an air-bubble screen around the periphery of the intake structure
discourages possible fish penetrations. Most of the intake structure and
the entire 10-ft-dia intake pipe leading from the structure to the plant is
buried below the bottom of the lake. The cooling water is drawn through
the intake ports, in a downward direction, at about 0.9 fps. It flows by
action of gravity through the 10-ft-ID intake pipe and empties into the
forebay of the screenhouse. The water velocity in the intake pipe at full
flow is about 11 fps. The screenhouse forebay acts as a stilling basin to
reduce the water velocity before the water passes through a bar or trash
grill (size unknown) and the traveling or rotating screens.
Each traveling screen has a 3/8-in. mesh. Each screen is a
continuous belt constructed of screening panels with a shelf at the lower
edge of each panel. The screen is rotated upward in a plane normal to the
waterflow direction. Any debris larger than about 3/8 in. is thus "caught"
by the screen, and as the screen moves upward out of the flowing water,
the debris falls off into the shelves. These shelves are backwashed auto-
matically, the debris being sluiced to a strainer casket, where it is collected
and eventually removed for onsite burial. A hypochlorinating system is pro-
vided to inject sodium hypochlorite, if necessary, into the inlet of the travel-
ing screens to prevent the buildup of bacterial slime on the condenser tubes.
After the water passes through the screens, it is still within a
large basin, which helps to distribute the waterflow evenly to the circulating-
water-pump intakes located at the bottom of the basin. The circulating-
water pumps then deliver this water to the condenser. While the circulating
pumps are operational, the water surface level in the basin is liable to be
many feet below the lake surface level, which allows lake water to be drawn
into the intake system by gravitational flow.
As the cooling water flows through the condenser it picks up
heat. The heated cooling water is returned to the lake by means of a dis-
charge basin located at the shoreline. The basin is approximately 40 ft wide
at the shoreline discharge point. During the winter, to control the formation
of ice in the system, the circulation flow will be reduced to 287,000 gpm
with a corresponding rise in temperature of the cooling water of about 29°F.
-------
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Under this operation, a portion of the discharge water is returned to the
intake via a 10-in. recirculation line. Figure 6 shows the intake and dis-
charge structures in much greater detail.
2. Point Beach Plant Cooling System
The condenser cooling-water system for the Point Beach Plant
is schematically shown in Fig. 7. The Point Beach Plant has two generating
units and, therefore, two independent condenser cooling systems. The in-
take structure is made of steel piling forming a hollow cylindrical structure,
standing upright on the lake bottom, and filled with staggered limestone
blocks. In addition, thirty-eight 30-in.-dia pipes pass through the intake
structure about 5 ft above the lake bottom. The lakeside ends of these pipes
are covered with lyg' x 2-in. gratings. Figure 8 is an isometric view of the
intake design. Most of the intake water flows through the void spaces be-
tween the limestone blocks. The isometric sketch is not correctly drawn,
because the blocks are shown closely fitted when in reality they are some-
what more randomly oriented.
During normal, as opposed to wintertime, operation, both 14-ft-
dia intake pipes are used to conduct the water to the plant screenhouse
forebay. At full flow, the water velocity in both intake pipes can approach
5.4 fps. After entry into the forebay, the water passes through bar grates
spaced about 2 in. apart, then through traveling screens using 3/8-in. mesh
size. The design water velocity through the screens is about 1.1 fps. The
debris collected on the traveling screens is sluiced to a strainer basket
having 3-in.-square openings. The small-sized debris and the wash water
are returned to the Unit 2 discharge flume. After passing through the
traveling screens, the water divides between the circulating pump intakes
for the two units. From this point on, the two cooling systems are inde-
pendent, each having its own pumps, condensers, and discharge structures
(outfalls). Both discharges are nominally 35-ft-wide canals extending out
into the lake approximately 150 ft. Each outfall is at a 60° angle with shore.
The average water discharge velocity within the flume is about 2.2 fps.
During winter operation, or whenever the intake water tempera-
ture falls below 40°F, 108,000 gpm of the discharge water is recirculated
to the intake structure to prevent the formation of ice in the cooling system.
This is accomplished by reversing the flow in one of the 14-ft intake pipes.
At this time, the other pipe will maintain a higher intake flow of 428,000 gpm.
Under these flow conditions and while at full plant power, the temperature
rise for the cooling water will be about 31.5°F, instead of the normal 19.3°F
rise.
3. Zion Station Cooling System
The schematic flow diagram for the Zion Station condenser
cooling system is shown in Fig. 9. Details of the intake structure are shown
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in Fig. 10. The inlet ports are about 1 7 ft below the water surface. The
roof structure is located above the two large intake ports to prevent vortex
motions in the inlet water, as well as to provide more of a horizontal ve-
locity gradient around the intake. Water not only enters through the larger
two center ports but additionally through 45 small-diameter holes located
around the periphery of the intake. These smaller ports serve a double
purpose. In the wintertime, warm discharge water is recirculated through
them to prevent system icing. These smaller ports eventually lead to the
center intake pipe shown in Fig. 10, via a common plenum, the thawing box.
All three 16-ft-dia intake pipes lead to the forebay. At full circulating flow,
the average water-intake velocity at the two larger ports will be 2.47 fps
while the 16-ft intake pipes will have a 5.6-fps average flow velocity.
An isometric drawing of one of Zion's 12 traveling screens is
shown in Fig. 11. The bar grill has vertical 2-in. openings. The flow ve-
locity will be 1.2 fps at the grill face and about 2 fps at the traveling screens.
After passing through the screens, the water is withdrawn by the respective
circulating pumps for each unit and eventually is discharged to the lake about
760 ft offshore. The total transit time from intake to discharge is about
2 min. The discharge structure for Unit 2 is shown in Fig. 12. The dis-
charges are 154 ft on either side of the centerline for the intake pipes.
Each structure consists of a rectangular box with outlet louvers located on
the offshore end and on the side away from the intake pipes. The outlet from
the discharge structure consists of 14 ports roughly 7 ft wide by 3 ft high.
The ports are directed so as to form a 45° angle with both the intake lines
and the shore.
During winter operation, part of the discharge water is recir-
culated to the intake structure by flow reversal in the central 16-ft-dia
intake pipe. The cooling-water circulation rate and temperature rise for
winter were not specified.
4. D. C. Cook Plant Cooling System
The condenser cooling-water system for the Cook Plant is sche-
matically shown in Fig. 13. The intakes are surrounded by octagonal-
shaped, heavy structural frames provided with bar racks and 8 by 8-in.
grating on all sides. The top of each frame is covered with a steel roof.
At full flow, the intake water velocity through the grating interstices will
be 1.27 fps. Figure 14 shows a vertical view of a typical intake structure
along with the grills of parallel vertical bars with 2|-in. openings between
them. The water velocity through the grills is about 1 fps. The traveling
screens have 3/8-in.-square openings, and the water velocity through the
screens will be at most 2 fps. The debris collected by the screens will be
removed as solid waste. Units 1 and 2 have different condenser cooling-
water flow requirements due to differences in turbine designs.
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Note: Pipes shall have a minimum 3.0' cover
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Specific details concerning the discharge-structure designs are
lacking. It is known that the structures will be located about 1198 ft offshore
and will be submerged. The lake depth at the discharge locations will be
about 16 ft. Each structure will extend about 4 ft above the lake bottom
and will have two horizontal slot openings to produce a water-jet exit ve-
locity of 1 3 fps. Details concerning the orientation of the jet openings are
not given. Figure 15 shows a plan view in detail of the Cook circulating
water system. The cooling-water transit time from the circulating pump
discharge to the condenser inlet is about 35 sec. The transit time through
the condensers is about 6 sec and from the condenser outlet to the point of
discharge into the lake is about 184 sec.
Winter-season deicing capability is provided by recirculating
a portion of the warmed discharge water from either Unit 1 or 2 through
the center 16-ft-dia intake pipe in which flow will be reversed. Close in-
spection of Fig. 15 can show how this is accomplished by appropriately
manipulating roller gates and sluice gates in the screenhouse. Specific
flow and temperature data for the cooling system operating in the winter
mode was not given.
5. Palisades Plant Cooling System
The schematic for the Palisades Plant condenser cooling sys-
tem is shown in Fig. 16. Cooling water is withdrawn from the lake at about
3300 ft offshore. The intake consists of a vertical 11-ft-dia pipe, with its
opening located about 6 ft from the lake bottom. A 60-ft-wide, 60-ft-long,
12-ft-high box is centrally located over the intake. The box has a steel
plate for its top and 2-in. vertical bars, spaced 10 in. apart, around the
sides. The trash rack located inside the screenhouse consists of a grating
with vertical bars about 1 in. apart. The discharge canal is a structure
about 37 ft wide at the shore, opening to 100 ft at the point of discharge,
about 108 ft from shore. The average discharge velocity across the 100-ft-
wide opening will generally be less than 2 fps. The cooling-water transit
time from the condenser header to the point of discharge into the lake is
roughly 25 sec.
During winter operation, about 17,000 gpm of discharge water
will be withdrawn from the discharge canal and returned to the intake.
A special pump will be used for this purpose.
B. Biological Effects
As stated in Section III.B, this section includes summaries of studies
performed primarily in the intake and discharge canals. Similar types of
studies that included measurements in the lake part of the plume are re-
ported in the above-mentioned section. Therefore, reference to both sec-
tions will be necessary for a complete review.
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The biological effects on organisms passing through the pumps and
condensers were studied by the Bio-Test Laboratories at the Waukegan
Generating Station during 1971.7 Phytoplankton samples taken during this
period indicated no significant differences in total population densities be-
tween the intake and discharge canals. (Ayers et al. reported an apparent
10% phytoplankton kill in his Waukegan measurements. )
Initial findings of the effects of zooplankton passing through the con-
densers showed an average mortality of 5.8% due to mechanical effects
and another 1.6% due to thermal stress. (Comparisons were made with and
without heat addition in the condensers.) Even in July and August, when the
discharge water reached a maximum temperature of 88°F, 90% of the zoo-
plankton survived. Other studies10'22'58'90 (some of which relate to salt-
water) were cited as showing that water temperatures below 99°F have little
effect on the survival rate of most zooplankton. However, they found over
80% mortality when this temperature was exceeded.72
Size was found to be an important factor in the mortality rates.
Zooplankton exceeding a length of 0.9 mm suffered 17% mortality; smaller
organisms suffered only 4% mortality.7
Reference 72 cited studies that showed, "Organisms subjected to a
sudden temperature rise occasionally assume a condition of complete in-
activity simulating death. However, within a few hours after being returned
to temperatures far below their lethal level, these 'dormant' organisms
would resume their normal active conditions."23 The zooplankton popula-
tion at the Waukegan Station showed an average recovery rate of 1.4% 4 hr
after entrainment, resulting in a total mortality of only 6% from condenser
passage.
Preliminary studies at Waukegan indicated condenser passage had
little if any lethal effect on zooplankton egg viability. Results from Sep-
tember to December 1971 showed, in each of four species tested, egg via-
bility increased from 1 to 7% as a result of passage through the condenser.72
Periphyton samples collected from April 1970 to March 1971, from
artificial substrates in the Waukegan intake and discharge canals, indicated
more rapid growth in the warm discharge water during June and July. The
increased growth was due to nonfilamentous green algae, periphytic diatoms,
and filamentous blue-green algae, and not to forms of Cladophora. Growth
in the discharge canal was reduced during midsummer when water tempera-
tures exceeded 70°F. After September the growth again increased, but was
not as large as that which occurred on substrates located away from the
influence of the warmed water.74
Samples taken during 1971 (Ref. 72) showed that, as in the 1970
study, the dominant members of the periphyton community in both the
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intake and discharge canals were diatoms. Despite some differences in
distribution and abundance of particular species between the intake and
discharge, the total species, composed mainly of diatoms, was often quite
similar. The green algae species, Stigeoclonium, which was found to be
abundant in the discharge canal only in late June 1970, proliferated in both
canals in the 1971 sampling period. It was abundant in the intake when
temperatures ranged from 50 to 60°F, but also grew well in the discharge
temperatures of 70-79°F. Both the intake and discharge supported much
larger growths of periphyton in December 1971 than in December 1970.
The thermal discharge from the Point Beach Nuclear Plant has been
the subject of a number of studies since the unit went into operation in
December 1970. Reference 128 describes a preliminary study, primarily
to develop experimental techniques, that used the two separate cooling sys-
tems to study the mechanical damage and combined mechanical-thermal
damage on phytoplankton and zooplankton. Although experimental difficulties
were experienced, the preliminary results indicated no significant mortality
to phytoplankton. Samples of zooplankton taken from the intake and discharge
of both units were similarly surveyed, and results show that the physical
damage incurred by passage through the plant was more critical than the
thermal impact. That is, the lethal effects of heating and pumping were
essentially the same as the effects of pumping alone. The percentage of
animals killed by the entrainment experience varied from 8 to 19%, de-
pending upon the season.121
Testimony given at the Wisconsin hearings125 by Dr. Wright,
Westinghouse Environmental Systems Department, described results of
studies (unreferenced) by his organization at "a variety of locations through-
out the United States." Problems related to flow were generally more sig-
nificant than those related to the increased temperatures. Phytoplankton
survive both the passage through the condenser and the residual time in the
thermal plume and still maintain their photosynthetic activity. In some
cases, there was an increase in the productivity within the plume. Depend-
ing on the species and life stages sampled, a 5-20% loss in mobility of
zooplankton was observed as a result of passage through the pumps and
condenser.
Studies on whitefish egg entrainment and effects on phytoplankton
and zooplankton productivity, as a result of passage through the intake
structures, pumps, and condensers, were reported by the EPA Grosse lie
Laboratory.44 Samples were taken daily at the Big Rock Nuclear Plant
during November 1971 and at the Escanaba Power Plant during November 30-
December 4, 1971. These plants were chosen because of their proximity
to whitefish spawning grounds.
After pumping more than 6 million gallons of intake water at the
two plants, the investigators reported finding no eggs at the Big Rock intake
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and an insignificant number in the Escanaba intake. The results on phyto-
plankton productivity were inconclusive because of a low and variable
population density at the intake.44
The low live/dead zooplankton ratio at the Big Rock Plant inlet
indicated that damage was inflicted on the zooplankton while being drawn
through the intake pipe (2000 ft offshore) or the population was adversely
affected by severe storms during the sampling period. The differences in
the live/dead ratios between the inlet and discharge was equivalent to a
55% mortality of the population observed. The mortality would be 29% if
the discharge live/dead ratio were applied to the forebay population. They
concluded, "Regardless of whether the mortality is 29 or 55%, there ap-
pears to be significant population mortality."
The live/dead zooplankton ratios obtained at the Escanaba Plant
were much higher than those observed at Big Rock. The higher survival
rate could have resulted because of less stress imposed upon the orga-
nisms by the shoreline intake. The data indicated a 7% mortality in
passing through the plant.
Brauer _e_t al. studied the influence of the intake and outfall on the
distribution and abundance of zooplankton in Lake Monona. Sampling on
13 days in the summer and fall of 1969 and 1970 showed that Diaptomus,
Daphnia and cyclopoid copepods were two to seven times as abundant in
the water near the outfalls as in the control area. The maximum zooplank-
ton density occurred in or very near the discharge currents, which sug-
gested that the animals were being brought into the plume area rather than
being produced in situ. Observations that a many-fold increase in zooplank-
ton density took place in periods as short as 6 hr after the pumps were
started, plus the fact that the ratio of young to adult animals in the outfall
samples was not noticeably high, support the conclusion that the organisms
were brought into the area via the intake. This continuous input of zoo-
plankton simulated a rapid local production of zooplankton and probably
contributes to a higher concentration of fishes in the outfall area than in
the reference area.
The studies indicated that judicious location of intakes (at a depth
of minimum organism densities) is one way in which a power company
could reduce its biological effects.
Personnel of the Wisconsin Department of Natural Resources col-
lected samples from the Point Beach discharge canal to determine to what
extent fish eggs and fry were drawn through the cooling-water system.
Samples were collected on 14 days during March 3-May 27, 1971. The
specimens recovered consisted of one sculpin (partially deteriorated), a
few smelt eggs, and one salmonid egg (white). Since whitefish and lake
herring are late fall and winter spawners, the sampling was discontinued
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until November, at which time sampling was performed twice a week until
March 1972. This time the specimens consisted of 4-j smelt (2-3 in.),
two salmonid eggs (white), and one small unidentified egg. The investi-
gators concluded from these studies that the intake and discharge structures
from the Point Beach Unit No. 1 are of negligible concern to the spawning
grounds, eggs, and fry of whitefish and lake herring in Lake Michigan.
Operating experience with entrainment of fish during interim opera-
tion at low power is summarized in Ref. 119 for the Palisades Nuclear
Plant. The principal mortality was sculpins in January and February 1972.
The total number of fish impinged on the screens and counted daily from
February 24 to March 26, 1972, ranged from zero for 22 days up to 15 per
day for 10 days.119
A large fish kill was reported at the J. H. Campbell Plant in early
February 1971. The circumstances were summarized in a Michigan Water
Resources Commission memorandum. 7 (1) The problem had existed for
7-10 days. (2) A rough estimate was that several hundred thousand fish had
been killed by impingement on the screens. (3) The species were mostly
gizzard shad, with some alewives and yellow perch. It was speculated that
attraction of fish to the warm water that was discharged to prevent ice jams
in the intake channel was the cause of the problem.
The occurrence of gas-bubble disease in fish in the discharge of a
power plant in North Carolina was reported by the North Carolina Wildlife
Resources Commission. Gas-bubble disease can occur when the blood of
a fish becomes supersaturated with gases. This condition may result when
a fish at equilibrium with air-saturated water is subjected to an increase
in temperature, a decrease in pressure, or both. More commonly, gas-
bubble disease develops when a fish is exposed to an environment super-
TQ
saturated with dissolved gases.
Gill nets, electrofishing, and mid-water trawls were used to obtain
monthly fish samples at the Duke Power Company Marshall Steam Station.
Three species of fish were found to be afflicted with the disease during the
•winter of 1969-1970, whereas 13 species showed symptons during the winter
of 1970-1971. "Pop-eye" was the major diagnostic feature observed in the
majority of cases. Relatively few fishes had bubbles on their head or fins,
O Q
or in the mouth or the viscera.
Several fish mortalities involving a few hundred black crappie were
observed during late February 1971. The symptoms exhibited by the dying
fishes implicated gas-bubble disease as a principal factor.
Marcy137 reported on the survival of fish larvae in the discharge
canal of the Connecticut Yankee Atomic Power Plant. The plant cooling
water, heated to about 22°F above ambient river water, is discharged into
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a 1.14 mile long canal before returning to the Connecticut River. Non-
screenable fish larvae less than 0.6 in. in length, were sampled at the
plant intake and discharge, and at three points along the canal. The studies
revealed that no fish of nine species entrained in the condenser cooling-
water system survived passage to the lower end of the canal when water
temperatures were above 86°F. The survival rate immediately after
passing through the plant was 34.5% when the discharge temperature was
82°F and 16.6% when the discharge temperature -was 92°F. The majority of
dead specimens were mangled, and this condition was more apparent in
larger specimens. When the discharge temperature was 95°F, 100% mor-
tality occurred during passage through the plant.
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V. ALTERNATIVE COOLING METHODS
A. Environmental Impact
At the September 28, 1970, Workshop Session of the Third Lake Michi-
gan Enforcement Conference, a report, entitled "Feasibility of Alternative
Means of Cooling for Thermal Power Plants Near Lake Michigan" was
entered into record by Federal EPA representatives. The object of this
report was to establish the engineering and economic feasibility of various
closed-cycle condenser cooling methods that could alternatively be used in
the place of once-through cooling. The report examined the situation for
a modern 40% efficient 1000-MWe fossil plant (or some plant with an equiva-
lent thermal discharge loading) sited along four shoreline reaches of
Lake Michigan. The alternatives considered were: mechanical and natural-
draft evaporative cooling towers, mechanical and natural-draft "dry" cooling
towers, cooling ponds, and spray canals. Representative meteorological data
for the four reaches of the lake were obtained and then used as input data
to computer codes to generate engineering performance and monetary cost
data for the alternatives.
The report concluded that the alternative cooling systems considered
are feasible alternatives to once-through cooling around Lake Michigan, and
the impact of alternative cooling systems on the environment appears to be
minor. Those potential problems that do exist with the alternatives could
be avoided, or at least alleviated, through proper site selection and engi-
neering design.
Several specific studies have been made concerning the possible
environmental impact of alternative cooling systems for the major nuclear
power stations sited on the Great Lakes. Presently, four of the 12 U.S.
nuclear stations, either operating or under construction on the Great Lakes,
will use closed-cycle cooling in the form of evaporative towers. Two of
these plants are situated along Lake Michigan, and the other two on Lake Erie.
Although this report is primarily concerned with Lake Michigan, it was
felt that much of the environmental rationale concerning the installation of
closed-cycle cooling at the two Lake Erie plants could be equally germane
to Lake Michigan issues.
The following pages contain information extracted either from util-
ity environmental reports or from U.S. AEC environmental statements made
on nuclear power plaints pursuant to the National Environmental Policy Act
of 1969. The information is qualitative in nature. Nevertheless, this infor-
mation is presented to give the reader additional perspective on the environ-
mental issues surrounding closed-cycle cooling.
1. Davis-Besse Station
The 915--MWe Davis-Besse Station, on Lake Erie, will use a
single 493-ft-tall natural-draft tower.115 Studies of the climatic effects of
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an earlier proposed 370-ft tower, by Travelers Research Corporation,
indicated that the tower would "emit a highly visible but elevated plume,
which will, on the average, persist 1.2-2.3 miles downwind. It may, in
cold weather, persist as much as 20 miles downwind an estimated 6% of
the time (22 days)." The visible plume would touch the ground less than
2% of the time, on an annual basis. During rare winter conditions the tower
plume could cause some icing on structures at or near ground level, at a
distance of 1-2 miles from the tower, in the downwind direction.
More recent studies were performed by NUS Corporation for the
actual 493-ft-high tower under construction at the Besse site.115 Two-year
site meteorological data were correlated with Toledo meteorological data,
which, in turn, were used to predict the environmental effects of the opera-
tion of the cooling tower. Computer codes were used to calculate plume
rise, dispersion, and transport on an hourly basis upon input of hourly
meteorological data. The results were examined to determine consistency
with the actual Besse site meteorological data and the occurrence of local-
ized lake breeze effects, and also to assess anomalous situations of plume
downwash. The NUS analysis concluded that the average visible vapor
plume •would be 1.5 miles long. Visible plumes longer than 5 miles were
estimated to occur only 3% of the total hours of the year. As long as the
plume remained aloft during these periods, the plumes would represent
only an aesthetic problem.
It was further estimated that there could be a maximum annual
increase of 3.5 hr in the occurrence of fog conditions resulting from tower
operation. An annual average of 831 hr of fog occurs naturally; therefore
the 3.5-hr figure represents a 0.42% increase. The increased occurrence
of fog conditions does not represent discrete cases of induced fog, but
rather the possibility of fog occurring earlier and lasting longer than normal.
Lake breeze effects could increase the possibility of fog calculated for the
study; however, this effect was not considered to be significant.
Predicted increases in induced fog under icing conditions were
estimated to be less than 1 min at maximum. Lake breeze effects were not
considered to change the icing calculations since the lake breeze is not a
major effect during the winter, when the lake surface is generally warmer
than the land surface.
Downwash conditions resulting in the plume being brought to
ground elevation were calculated to occur as often as 12.8% of the time
(1121 hr/yr), with most hours occurring under offshore winds. The winter
downwash could possibly result in icing on surfaces less than 3000 ft away
at a rate of 0.03-0.07 in. of ice per hour. These downwash calculations
reflected maximum limits of occurrence and actual observations at operating
natural draft towers in this country have not confirmed downwash behavior.
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The Environmental Report115 stated that the temperature excess
of blowdown effluent over the ambient Lake Erie receiving water will be
limited to a maximum of 20°F by supplying ambient lake water to a collecting
basin to dilute the tower blowdown. The maximum quantity of heat dis-
charged to the lake is expected to be no greater than 1.38 x 108 Btu/hr, as
opposed to 62.10 x 108 Btu/hr for once-through cooling. This corresponds
to a 45 to 1 reduction in heat input to the lake. The blowdown will enter the
lake through an offshore high-velocity discharge with a normal flow of
9225 gpm. On occasions the flow may reach as high as 13,800 gpm.
Tower drift was estimated to be a negligible problem since the
expected drift losses would be 0.01% of the tower circulating flow, or 48 gpm.
For an assumed tower concentration factor of two and an assumed lake water
salt content of 225 ppm, the maximum amount of salt deposited on the land
was estimated to be 3.7 x 10"4 (lb/yr)/sq ft, assuming a uniform salt distri-
bution over a 10-square-mile area. Assuming a 30.5-in. annual rainfall,
the salt concentration was estimated to be 2 ppm if all the salt deposited
was taken by the rain. Terrestrial effects arising from drift losses were
therefore assumed to be of little concern.
The Environmental Report also addressed the potential impact
of the tower on bird kills.115 Collision kills with the tower by migratory
waterfowl were considered to be most likely at night or during times of
heavy fog, but in any event, they were assumed to be minor in relation to
the total migratory populations. Resident birds were not expected to be
destroyed by collisions with the tower.
2 . Enrico Fermi Plant
The Fermi Plant environmental report indicates that two
natural-draft evaporative towers, approximately 400 ft high, will be used
for condenser cooling.39 The report stated that the possible effects of the
towers on the local environment can be conveniently considered to be of
two kinds: (l) presence of water from the towers in the form of plumes,
fog, icing, or precipitation; and (2) influence on natural condensation and
precipitation processes. The report states, "The quantitative assessment
of the two kinds of effects at this time can be made only from observations
of releases from similar cooling towers in similar climates and from
incomplete theoretical calculations."
Two early independent analyses of the extent of the tower
plumes indicated that an airport two miles west of the plant might be
influenced at most by 8-18 hr/yr. The diffusion models used to calculate
these distances were credited with yielding unusually conservative values
because they did not take into account the plume's inherent buoyancy.
Additional estimates of the plume's horizontal extent were gained from
observations of the Keystone natural-draft towers in western Pennsylvania.
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For a six-month observational period, the plumes on only 11 different days
extended as much as a mile. Although the climate in the Keystone plant
area is somewhat different from that of southeastern Michigan, it is be-
lieved that the Keystone information offers a realistic idea of what can be
expected at the Fermi site.39
Minor modifications of the microclimate in the vicinity of the
Fermi site, resulting from plume shadowing, were anticipated. However,
the actual effects or the magnitude of these effects has not been assessed.
Fog formation was only discussed in a qualitative way. The inference was
that it would take an unusual set of meteorological conditions to bring the
tower plumes to the ground.
Ground icing conditions were stated to possibly arise under
either of the following conditions: (l) With strong winds (>25 mph), there
is a potential of downwash icing in the immediate vicinity of the towers,
provided that there is the additional joint occurrence that objects downwind
are below 32°F and the atmosphere has a high relative humidity. An analy-
sis of 10-yr records of hourly observations at the Detroit City Airport
showed that the joint occurrence of the above-mentioned conditions occurred
for less than 0.1% of the observations. In any event, the extent of icing in
this manner should be confined to an area two to four tower heights down-
wind. (2) Lake breeze circulations during early spring were also hypothe-
sized as being the second possible means for causing ground icing. No
estimates were given as to the potential number or duration of these periods.
This issue, according to the report, awaits successful application of numer-
ical models presently being formulated.
Comparative calculations were made assuming that if all the
water evaporated from both towers over a year were evenly deposited over
a 25-square-mile area, it would amount to 1.4 in. of precipitation. This is
compared with a normal annual rate of about 31 in. The report went on to
state that observations of actual cooling towers rarely show observable
precipitation, and when precipitation did occur, it was not established
whether it was the result of natural processes being stimulated by tower
effluent.
The influence of tower effluents on natural condensation and
precipitation processes was discussed. Although the total amount of heat
and water released from a cooling tower is small in comparison to a small
shower, the nature of the atmosphere is such that at times small perturba-
tions may give rise to more extensive reactions. Several were enumerated
and discussed:
a. Cumulus or stratocumulus clouds induced to form sooner,
or last longer, or grow denser and deeper.
b. Natural fog induced to last longer.
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c. Natural precipitation induced to increase locally at other
times.
d. Thunderstorm activity induced to either increase or de-
crease, depending on the nature of the atmosphere.
Our understanding of the natural process of condensation and precipitation
is far from complete.39 Therefore the extent to which a cooling tower
affects the above processes cannot be reliably estimated from a theoretical
standpoint. However, actual observations show that increases in local
cloudiness are common in some areas. Changes in precipitation were
small and much less frequent. Additionally, no reports of thunderstorm
modifications are known to date. Further elaboration on the above four
items was given within the report39 but, again, only from a qualitative
viewpoint.
Tower blowdown is returned to Lake Erie at the shoreline. The
blowdown's temperature excess is expected to range between 12 and Z3°F.
The maximum heat discharged in this manner is expected to be less than
o / f^j
0.78 x 10 Btu/hr, or 1.5% of the once-through requirement. The returned
water will have roughly three times the concentration of dissolved solids
(500 ppm) than appear locally in the lake. Additionally, free chlorine will
be present in concentrations estimated to be less than 0.1 ppm.
It is estimated that a maximum total of 19,500 gpm will be
evaporated and lost by drift from the towers and a small pond used in the
closed cooling system. Drift from both towers is expected to be less than
a maximum of 0.1% of the tower circulating flow. By assuming the 0.1%
figure, together with a solids-concentration factor of three, the investiga-
tors estimated that the dissolved solids emitted to the atmosphere would
be less than 5300 Ib per day.
3. Zion Station
Several recent studies have investigated closed-cycle cooling
systems for nuclear power plants along Lake Michigan. The first such
study was that of the Sierra Research Corporation in which evaluations
were made to determine the possible environmental impact of operating the
2200-MWe Zion Nuclear Generating Station with evaporative cooling towers .26
Several cooling-tower configurations were considered for the Zion site:
70 mechanical-draft tower cells, each 60 ft high, 70 ft wide, and 40 ft deep;
10 combination mechanical-natural-draft towers 250 ft high and 300 ft in
diameter; five natural-draft towers, 350 ft high and about 300 ft in diameter;
and three natural draft towers 500 ft high and about 500 ft in diameter.
Basically, the calculations made for fog frequencies required
the input of tower design parameters together with historical meteorological
data for the Zion site. Since the requisite meteorological data were not
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available for the Zion site, recourse was made to U.S. Weather Bureau
data, gathered at the Chicago (Midway) and Milwaukee airports, which pro-.
vided tabulations of the frequency of various combinations of temperature,
humidity, and wind speed. Atmospheric stability and wind assessments
required for the tower fog calculations were obtained from determinations
made by the NUS corporation for the Zion plant in relation to radiological
dispersion issues.
The results show that ground fog, as a result of mechanical-
draft tower operation, could be expected somewhere around the plant
(which may include Lake Michigan as well) a maximum of 650 hr/yr. It
was stated that a ±20% variation in this number could be expected in any
given year due to natural variability. The maximum frequency at any one
point was calculated to be 90 hr/yr at 1.5-2.5 miles north of the plant
using Milwaukee meteorological data. Chicago meteorological data also
show a maximum frequency in that location but only 50 hr/yr. Using
either the Chicago or Milwaukee data, the investigators predicted that
fogging would most likely occur from northwest through the north and
easterly directions. Predicted fog frequency is least to the \\eoi of Zion
station. Fog-frequency estimates as a result of tower operation for various
towns or locations were given as: Waukegan Airport, 20-40 hr/yr; the
town of Zion, about 25 hr/yr; Waukegan, 18 hr/yr; Winthrop Harbor and
along highways northwest of the site, 40-60 hr/yr; and the lake shore
1-2 miles north of the plant, 50-90 hr/yr.
Most occurrences of fog would be between 0 and 34°F. The
winter months, December, January, February, and March, show the highest
fog frequency; June, July, and August the least. The most favorable hours
for fog formation are from 3 to 7 A.M. The greatest majority of all
cooling-tower fogs should be observed between 12 midnight and 10 A.M.
Most fogging episodes were said to be short-lived, with a. duration of
2-4 hr. Very few situations are expected with a persistence over 6 hr.
A fog duration of up to 12 hr or more could infrequently occur when the
tower fog mixes with natural fog. The report concludes that if an average
duration of 3 hr is assumed for a fogging episode as a result of tower opera-
tion, then the mechanical-draft towers would produce ground fog on a maxi-
mum of 25 days/yr at any one point.
The fog frequencies computed for the taller towers were con-
siderably lower, decreasing with tower height. For the 500-ft-tall towers,
estimated ground fog frequencies ranged from 5-40 hr/yr, the distance of
maximum frequency being 12.4 miles from the site. Ground-fog frequencies
for the 350-ft towers were estimated to occur between 15 and 75 hr/yr,
9.31 miles being the distance of maximum frequency. Fog frequencies for
the 250-ft tower were 25-100 hr/yr, the distance of maximum frequency
being 7.4 miles. With fog persistence of 2-4 hr, individual fog episodes
were expected to occur 5-30 days/yr with these taller towers. The pre-
dicted ground-fog frequencies are significantly lower with increasing tower
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85
height, and when fog does occur it generally occurs further from the plant
with increasing height. However, because ground-fog frequencies are less
with the taller towers, this does not imply that the tower plumes will dissi-
pate close to towers. Rather, plumes from the towers will frequently per-
sist for distances as great as 10-20 miles, but only rarely will these plumes
contact the ground. The distribution of fog from these taller towers with
respect to the time of the day, the month, and the direction were stated to
be similar to the mechanical-draft situation.
A summary chapter in the Sierra Report was devoted to inter-
preting the results. Although the physics of the problem formulation is
based on accepted and understood models, these models nevertheless have
never been verified against long-term tower tests and should therefore be
interpreted as state-of-the-art estimates. It was estimated that the calcu-
lated values should be correct to within ±25%, at a confidence level of 95%.
Natural fog at Milwaukee and Chicago (Midway) averages 260 and
160 hr/yr, respectively. It was estimated that about 35% of the tower-fog
cases would coincide with measurable natural fog. When fogs occur together,
the fog density would naturally be greater in the tower plume. In general,
the intensity of the fog at the ground under such situations should produce
visibilities in range of 200-1000 ft, that of dense natural fog.
Since most tower fogs would occur when temperatures are
below freezing, some icing was anticipated whenever the supercooled fog
made contact with solid objects at the ambient temperature. But, because
fog situations will seldom last longer than several hours, heavy icing of the
kind that would endanger vegetation or structures would not be expected.
The report cautioned, however, that any icing on highways could be a
serious hazard.
The Sierra report mentioned that under certain wind conditions
downwash and aerodynamic distortion, not only from the towers themselves
but also from nearby plant building structures, could to a small extent
increase the frequency of ground fog. The number of such incidents would
decrease with increasing tower height. Such effects could be minimized
with the 500-ft towers.
The Environmental Report26 summarized additional problems
that could result from cooling-tower operation. Since the Waukegan air-
port is about 3.25 miles away, it was suggested that both the vapor plumes
and tall towers, if used, could represent aircraft hazards. It was further
suggested that the water evaporated by the towers (66 cfs) might legally be
construed as a Chicago area water diversion and hence apply against the
3200 cfs internationally allocated for the Illinois-Lake Michigan diversion.
The report additionally pointed to the undesirable aesthetic impact of
either the resultant tower plumes or the towers themselves, particularly
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86
the taller ones. Tower blowdown and drift problems were not pointed to as
being significantly consequential. The blowdown thermal-discharge rate to"
the lake would be roughly 0.96 x 108 Btu/hr, compared to 150 x 108 Btu/hr
for once-through cooling.
Several other alternative closed-cycle cooling systems were
investigated for the Zion station: a 3000-acre cooling pond, a 300-acre
spray pond, and dry cooling towers. The 3000-acre pond was ruled out
because land use in the area precluded everything except a possible loca-
tion several miles west of the site. Because of elevation changes and
distances involved, the pumping-energy requirements of this alternative
would reduce the capability of the station more than any other evaporative-
type alternative. In addition, the pond site would require a number of
residences and farms to be displaced. The 300-acre spray-pond alternative
was rejected, partially because of available land limitations and partially
because potentially severe fogging and icing problems were anticipated.
The dry cooling towers were rejected as being viable alternatives, primarily
because of excessive costs.
The Illinois State Water Survey published a document summa-
rizing their findings concerning the potential effects of cooling-tower efflu-
ents on the atmosphere with emphasis on the Zion Plant.62 A literature
search was made covering basically three topical areas: fog and icing,
clouds and precipitation, and severe weather. More attention had been
given in the literature to fog and icing problems associated with tower
effluents than any other potential weather effects. The report stated that,
"The majority opinion appears to be that fog and icing are usually minor
problems with natural-draft towers employing evaporative cooling, since
these towers usually extend to heights of 350 ft or more into the atmosphere
so that the plume seldom, if ever, sinks to ground level. Mechanical-type
towers release their effluent at a much lower level (50-75 ft) and in a much
more turbulent condition due to fan-forced ejection, so that there appears to
be a high probability of tower-induced fog and icing at or near the ground
on occasions. However, the frequency of such occurrences cannot be
assessed accurately with existing observational data."62
Very little quantitative data on the effects of cooling towers on
clouds and precipitation could be found. The report stated, "Occasional
observations of light drizzle or snow attributed to tower effluents have
been reported. Also, there have been several reports of tower plume con-
tributing to cloud formation downwind; apparently, these are usually
stratus-type clouds and observations of cumulus developments have been
rare. A few mathematical calculations have been made to determine the
cloud and precipitation producing potential of cooling tower plumes, but no
meteorologically acceptable analyses have been made to assess quantita-
tively the possibility that these plumes augment precipitation and cloud
systems associated with naturally occurring storms."62
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87
The literature provided little information on any observed or
calculated effects of towers on severe weather. The report concluded,
"From consideration of atmospheric physics and dynamics, one would
expect that any severe weather event resulting from cooling tower effluents
would be attained only through a triggering or stimulation effect." In another
paragraph the report went on to state, "In general, we conclude from avail-
able information in the literature that a very distinct void exists in our
knowledge of the effects of cooling tower plumes on clouds and precipitation,
with regard to both initiation and stimulation of these weather events.
From climatological observations and cloud physics research, it is known
that cumulus clouds and rain showers or thunderstorms can be triggered by
small inputs of energy. Consequently, it is extremely important that re-
search be initiated to combine existing knowledge of plume and cloud prop-
erties into mathematical models that will provide reliable quantitative
estimates of the plume effect on downwind clouds and rainfall."62
The report summarized several specific findings related to
Zion itself. Calculations showed that the amount of moisture that could be
added to the atmosphere from Zion would be very small compared to
natural fluxes in storm clouds. However, the addition of tower effluents
could occasionally result in additional precipitation and possibly other
undesirable intensification of naturally occurring weather events.
The meteorological effects from the interaction between
cooling-tower effluents and lake breezes in the Zion area were stated to
"likely result in additional snowfall under certain synoptic weather
conditions." The analyses indicated that in spring "there would be days
where a cooling tower plume would thicken on existing naturally occurring
fog, but most of the time this fog would not persist more than 1 to 2 miles
inland. Only very occasionally would a weather situation exist in which
convective storms could be intensified by the lake breeze-tower plume
interaction. Again, the general conclusion must be that accumulated
knowledge is insufficient at this time to define in quantitative terms the
effects of the interaction of cooling tower plumes with a lake-influenced
atmosphere."
A numerical model was used to estimate the amount of additional
rain or snow, under steady light rain or snow conditions, that would result
from tower operation at Zion. The results showed that the tower plume
could lead to a small rainfall (trace amounts) within a few thousand feet of
the tower. The additional rainfall amounts were said to be trivial, a fraction
of 1% annually. Predictions on snowfall indicated that the total annual snow-
fall would be increased 1-2 in. within this lake-effect zone. There were also
some indications using the model that the tower plumes could trigger a
thunderstorm under special weather conditions.
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88
Under a section titled, "General Conclusions and Recommenda-
tions" the report stated, "At this time meteorologists have not acquired
adequate information to define in quantitative terms the meteorological
consequences of the large amounts of heat energy and water vapor that are
released into the atmosphere from cooling towers associated with nuclear
power plants. The interaction between tower effluent and the atmosphere
is very complex and dependent upon local conditions of climate and topog-
raphy Although it was not the purpose of this report to compare the
meteorological consequences of lake and atmospheric dissipation of waste
heat, the authors consider it appropriate at this point to present several
relevant facts pertaining to this problem. First, it is much more difficult
to establish the meteorological consequences of atmospheric dissipation
of waste heat from large nuclear power plants than it is to evaluate the
meteorological ramifications of once-through cooling on Lake Michigan.
This is because in both time and space the lake is much more stable with
respect to its meteorological properties Secondly, the lake cooling
spreads out the heat dissipation over a much longer time period than
cooling towers and, therefore, localized effects on the weather are likely
to be less pronounced with lake cooling than with cooling towers. Strictly
from the meteorological standpoint, it appears that environmental effects
are likely to be no greater, and probably smaller, with dissipation of
waste heat into Lake Michigan compared with atmospheric release from
cooling towers."
4. Point Beach Station
Alternate closed-cycle cooling systems were investigated for
potential use at the 1046-MWe Point Beach nuclear station in Wisconsin.129
It was estimated than an 850-acre pond would be required for this purpose.
The most significant environmental impact of this alternative was stated
to be the elimination of land resources that presently support agricultural
activities and small-game shelters.
With evaporative cooling towers, it was recognized that
natural-draft tower plumes seldom return to the ground; thus the occur-
rence of ground-level fog or icing would be negligible. Some enhancement
of cloud formation and precipitation was suggested. Two natural-draft
towers, each 370 ft high and 400 ft in diameter, were contemplated for the
Plant. With the natural-draft towers, it was stated that there would be a
significant objectionable aesthetic impact. The towers would be three
times the height of the tallest existing structures. With mechanical-draft
towers the occurrence of fog would be more frequent. Four tower assem-
blies, each 73 ft wide, 60 ft high, and 360 ft long, were considered.
The report129 indicates that the normally observed ground fogs
are quite thin near the lake and suggests that the fogs created by
mechanical-draft towers would probably extend from the ground to the tops
of the towers and for a considerable distance downwind of the towers.
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89
Conditions favoring this occurrence "would be limited mixing or inversion
breakup (fumigation)." Whenever onshore breezes were present, there
would be the likelihood that some of the moisture from the towers "could
settle on forests and crop lands. When ambient temperatures are low
enough, the moisture could freeze on tree limbs and lower story vegetation
and could affect the wildlife cover." It was also indicated that "there would
undoubtedly be some effect on seasonal crop characteristics due to increased
moisture." The environmental impact for the alternative cooling systems is
contrasted against once-through cooling in Table 6.129
In the Point Beach Environmental Statement,121 it was estimated
that a visible tower plume would be seen during much of the year: at least
50% of the year for mechanical draft towers and 95% of the year for natural-
draft towers. Most of the plumes would occur close to the facility. How-
ever, under restrictive conditions the plumes could extend downwind as far
as 30-40 miles for the natural-draft towers and as far as 15-20 miles for
the mechanical-draft towers. Although the actual size of the plume and the
distance it persists depend on meteorological factors, the plume will roughly
be cigar-shaped and, under restrictive conditions, would have a maximum
width of about 2 miles and maximum depth of about 1000 ft. Further, it
was anticipated that cooling towers would increase the amount of fog at a
particular point on the order of 1-11 and 5-75 hr/yr at the point of maxi-
mum effect for natural and mechanical draft towers, respectively.
Ground-fog calculations for the alternative 850-acre cooling
pond indicated that ground plumes would extend from the pond to 1, 5, and
10 miles on the order of 45, 30, and 5 hr/yr, respectively.121 The maximum
number of hours per year of fog due to the cooling pond at any point at
1, 5, and 10 miles is estimated to be 8, 5, and less than 1 hr/yr, respec-
tively. Pond fogging will occur almost exclusively in the winter, and the
incremental environmental impact in terms of contributing to reduced
visibility and icing should be inconsequential in relation to the occurrence
of natural fog.
A spray canal system was additionally investigated. The plant
would require a 30-acre canal with about 140 spray modules. A crude
analysis was performed which indicated that potential fogging and icing
resulted in occurrences of approximately 150, 80, 20, 4 hr/yr at 1/2, 1,
5, and 10 miles from the canal, respectively.121
5. Kewaunee Plant
Several closed-cycle alternative cooling systems were investi-
gated in relationship to the 540-MWe Kewaunee Plant in Wisconsin.130
A single 450-ft-high, 480-ft-dia, natural-draft evaporative tower and
three parallel banks of mechanical-draft towers, each bank 50 by 350 ft,
were proposed as alternatives to once-through cooling. In a Westinghouse
study concerning evaporative towers for the Kewaunee site, the potential
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91
environmental impact of such towers was discussed and most of the following
material on towers have been abstracted from this report.1
The meteorological effects of evaporative towers were con-
sidered. Icing and fogging could occur and cause problems on nearby roads
or in the plant's electrical switchyard about 10 days annually. This did not
count the number of times the tower plumes might influence natural fogging
or icing conditions by making them more severe or of longer duration in
the vicinity. Cooling-tower drift problems were discussed and implied to
be of minimal consequence off site. Except for certain tower chemicals,
"Watering lawns in residential areas with average city water would result
in as much or more dissolved solids deposit as would drift from cooling
towers using Lake Michigan water." Drift was calculated to add roughly
400 Ib of dissolved solids per year in the plant vicinity.
Slowdown, while singled out as an environmental issue, was
only discussed briefly by noting that it contains not only increased con-
centrations of dissolved solids, but also some chemicals.
The Westinghouse report additionally provided a quantitative
evaluation of the potential biological impact of cooling towers as contrasted
against once-through cooling for the Kewaunee Plant. Through a series of
rather simple calculations and arguments, it was shown, based on con-
servatively assumed population, fractional capture, and mortality estimates,
that a maximum fish kill of 7650 Ib/yr can be expected with once-through
cooling. Closed-cycle tower cooling was stated to result in zero fish kill.
The fish-kill equivalent of plankton mortality (including meroplankton)
resulting from plant operation was also calculated using estimated values
of lake plankton biomass, cooling-system flow rates, fractional losses in
the condenser and in the towers and plumes, and a two-to-one fish-to-
plankton-kill biomass ratio. The estimated maximum values of fish kill
due to once-through and closed-cycle cooling were 2900 and 236 Ib/yr,
respectively. The net estimated overall fish and fish-equivalent kill
range was stated to be 1680-10,550 Ib for once-through cooling and 120-
270 Ib for closed-cycle cooling. 10,550 Ib/yr represents an average of
30 Ib/day. A calculation was made to show that the increased fuel-energy
cost alone, resulting from closed-cycle tower operation versus once-
through cooling, amounts to $600,000/yr. This figure corresponds to a
biological cost of 10,550 minus 270 or 10,280 Ib of fish per year, or about
$60/lb. This figure was then compared to the cost of fish produced at a
hatchery, $1.50/lb. The report concluded that, "The great disparity in
the cost per pound of fish suggests that better commitment of total resources
could be made by building fish hatcheries instead of cooling towers." The
environmental impact of various alternative cooling-tower schemes for the
Kewaunee Plant is summarized in Table 7 as abstracted from the Westing-
house Report.
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92
Table 7
Environmental Impact of Various Cooling Modes
Area of Impact
Fish
Plankton
Fuel Resource
Effluents to
Air and Land
Effluents to
Water (Plume)
Parameter
Flow Rate, GPM
Air Screen Effectiveness, 1
Fish Capture at intake, %
Fish Transport Mortality, 1
Estimated Annual Damage, Ib/year
Condenser Mortality, %
Cooling Tower Mortality, \
Plume Mortality, 1
Meroplankton Mortality, Ib/year
Estimated Equivalent Fish Damage Ib/year
Heat Rate Btu/Kw-HR
Fuel Penalty for Towers, \
Fog Persistence Due to Towers, Days /year
Drift, GPM
Salt Fallout, Ib/acre/year
Chemical Release
Radionuclide Release, pCi/1
Thermal Plume:
Discharge Temperature Above Ambient, °F
Acres Affected at +1°
Acres Affected at +4°
Acres Affected at +10°
Acres Affected at +18°
Once- through
413,000
0-501
0.34
100
2300-7650
10-20
0
10-201
725-1450
1450-2900
10,440
0
0
0
0
Nil
5
20
2720
252
7
0.7
Closed- Cycle
Cooling Towers
28,000
0-501
0.0017
100
1-32
10-20
100
4-8
59-118
118-236
11,070
6
10
400
400
Nil
89
20
141
72
28
4
These values are assumed or estimated based on scant data; values should be verified by field
or laboratory work.
210CFR-20 Limit = 100 pCi/1
10CRF-50 Limit = 20 pCi/1
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93
A cooling-pond alternative, between 650 and 1500 acres, was
investigated for the Kewaunee Plant.130 The most significant environmental
impact of the pond would be the removal of 650- 1500 acres of crop and
pasture land. A spray canal was also considered for the plant. No particu-
lar environmental impacts were cited for the spray canal other than sug-
gesting that fish damage similar to that of cooling towers can be expected
as a result of blowdown to the lake.
6. Bailly Station
An evaporative natural-draft cooling tower will be used at the
Bailly Generating Station in Indiana for its 685-MWe nuclear unit.91 Two
possible adverse meteorological effects resulting from tower operation
were cited: fog and drift. Calculations for the southern end of Lake Michigan
indicated, "relative humidity and temperature combine in such a manner that
there is a high probability of producing fog from a cooling tower only 0.11%
of the time (0.4 days per year)." The probability for ground fog from a
natural-draft tower was stated to be even lower.
Three atmospheric conditions were discussed that could con-
ceivably limit the plume rise from a tower and thereby increase the poten-
tial for contributing to natural fog: a strong atmospheric temperature
inversion, the presence of a high wind, and tower downwash. The report
considers none of these three to be credible mechanisms for contributing
to natural fog. Two types of atmospheric temperature inversions--a
surface-based radiation inversion and a subsidence inversion--were also
considered as potential mechanisms for causing a plume to be trapped at
low levels and thereby possibly contributing to existing natural ground
fogs. These were subjected to qualitative arguments, and it was concluded
that the tower plume would very likely penetrate the radiation inversion or
rise to a sufficient height in a subsidence inversion (~1000 ft) insuring that
a natural-draft tower plume would not likely play a contributing role in
existing ground fog. In citing reference material within the report, the
investigators stated that, "Surveys of operating cooling towers in the
United States and in Europe confirm that natural draft cooling towers do
not cause or intensify ground fogging conditions."91
Drift and evaporative losses from the Bailly tower are estimated
to be about 7100 gpm or 15.6 cfs . This quantity was stated to represent only
about 0.04% of Lake Michigan's natural evaporative losses over the entire
lake. It was therefore assumed that the Bailly tower losses will have no
significant impact on the lake.
Tower blowdown was not expected to be a problem since most
of the impurities in the blowdown water will be the same as those in the
lake. Some chemical treatment of this water, mainly in the form of
sulfuric acid and chlorine (hypochlorite ions), is anticipated. The investi-
gators, however, estimated this to be of such low concentrations when dis-
charged that no adverse effect on the lake is expected.
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94
The possible synergistic effects resulting from, the combination
of the cooling-tower plume with existing atmospheric constituents were dis-
cussed. It was felt that since no such adverse effect has been documented
at other natural-draft cooling-tower installations and since the regional
air-pollution indices are stable or declining, this would not be a problem.
Consideration was also given to the possible effects associated with the
tower plume blending with the stack effluents from the operating fossil-
fired units at the Bailly site. The speculation is that sulfur dioxide in the
stack effluents could be oxidized and then combined with the tower vapor to
form an acid mist. The statement was made that since other larger coal-
fired plants with natural draft towers have not reported any adverse effects,
no problem is anticipated at Bailly. Further arguments were developed
stating that the oxidization of sulfur dioxide in a combined plume could be
catalized by certain fly-ash constituents. Since the Bailly fossil units
remove 99% of the fly ash through electrostatic precipitators, it was
inferred that this would reduce the probability of acid mist.
Mechanical-draft cooling towers were also considered as an
alternative to natural-draft towers. Land-area requirements for the
mechanical towers were estimated to be roughly 23 acres, as opposed to
4.5 acres for natural-draft towers. This excess land area, for the
"economical arrangement" of mechanical-draft towers at the Bailly site
is not available; therefore this alternative was rejected. From an environ-
mental point of view, mechanical-draft towers were noted to have a greater
probability of producing ground fog than natural-draft towers. Since the
Bailly site is located in an industrial area near a highway, this potential
problem could be significant. It was stated that mechanical-draft towers
are best suited for areas where fog is unlikely or in sparsely settled areas.
Cooling ponds, spray ponds, and cooling canals were noted as
having a potential for producing ground fog and for evaporating more water
than cooling towers. They were primarily rejected as alternatives because
of limited land availability. Dry cooling towers were also mentioned as an
alternative. They were rejected, however, because their use would signifi-
cantly decrease the plant efficiency unless special turbines could be made
available. The requisite turbines could not be fabricated in time to meet
the unit's operating date. The towers were additionally rejected because
there was some doubt whether a dry-tower system could be physically
incorporated into the Bailly site because of its anticipated size.
Once-through cooling was also considered for the new Bailly
unit with either a shoreline or offshore discharge. It was indicated that a
detailed cost-benefit analysis would probably show this option to be the
best choice. It was rejected as a viable alternative since it was believed
that once-through cooling might be prohibited on Lake Michigan in accord-
ance with the recommendations of the Third Lake Michigan Enforcement
Conference. The utility stated that even though no existing law prohibits
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95
once-through cooling, it could ill afford an operating-license delay of well
over one year as recently experienced by the Palisades Plant and then end
up installing duplicate facilities.
7'• D. C. Cook Plant
The environmental report for the 2200-MWe Donald C. Cook
Nuclear Plant65 outlines four alternative cooling systems which could be
used to backfit the present once-through system. It was estimated that a
cooling pond would have to be at least 5000 acres and have a minimum
depth of 8-12 ft. This alternative was considered totally impractical, since
land acquisitions of the required area are not readily or realistically
available in the surrounding scenic dunes area. The sandy soil in the
general area would not be suitable to retain water without the costly instal-
lation of asphalt or some comparable material. The pond was estimated
to consume roughly 40,000 gpm of lake water, three-quarters of it through
evaporation and the remainder through seepage losses. Aesthetically the
pond would be the most desirable of the alternatives considered. From an
ecological point of view, there would be no significant effect other than
those anticipated from the displacement of farm and recreational land.
Two natural-draft evaporative towers, each 500 ft high and
520 ft in diameter, were considered as another alternative. The towers
would consume about 30,000 gpm of water. The meteorological effects
resulting from the discharge of this quantity of water vapor from two
localized points 500 ft above the ground were said to be unknown. Under
certain atmospheric circumstances the plumes could cause fogging and
contribute to icing conditions in the winter. The report states that this
alternative would constitute a significant aesthetic intrusion along the
scenic shoreline and would completely destroy the low-profile Cook Plant
design. During cold weather the vapor plume would be visible several
thousand feet in the air, again an aesthetic cost. From a land-use point of
view the two towers would require the leveling of 40 acres of presently
undisturbed dune land.
Fourteen mechanical-draft towers, each 73 ft wide, 400 ft long,
and 60 ft high, were considered for the Cook Plant as another alternative.
The mechanical-draft system would consume about 30,000 gpm of lake
water when in operation. The system would also require some 90 acres of
dune land for installation. One of the major disadvantages of a mechanical-
draft-tower system is discharging the water vapor and droplets at a
relatively low altitude above ground; this could result in serious icing
problems on plant-access roads and on public highways . Since mechanical
towers have such a low profile, they would not detract from the plant's
low profile. However, because of their bulk, they might have a significant
adverse effect upon the plant's appearance from the lake. Ecological
effects on the lake from blowdown discharges from either the mechanical-
or natural-draft towers were thought to be insignificant.
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Dry cooling towers were discussed, but they were not con-
sidered a viable alternative for a plant the size of Cook. The report in-
dicated that even if they were feasible they could not be used at the Cook
Plant because the steam turbines presently installed could not operate
with them.
8. Palisades Station
The Environmental Statement for the 715-MWe Palisades
Nuclear Generating Station119 discusses several closed-cycle cooling
alternatives to the plant's presently used once-through system. (The plant
will be backfitted by November 1973 with mechanical-draft towers as part
of a settlement with interveners at a licensing hearing.) The closed-cycle
cooling alternatives considered were mechanical- and natural-draft evapo-
rative towers, dry towers, and cooling and spray ponds. One of the principal
impacts of the evaporative towers was considered to be the addition of
chemicals to the lake via blowdown and the addition of chemicals and water
to the surrounding land as a result of drift. (The blowdown issue is dis-
cussed in more detail in Section VI of this report and will not be covered
here.) The Environmental Statement concluded that once-through cooling,
with appropriate modifications to the present facility, would cause less of
an impact on the lake than that resulting from the Palisades Plant operating
with cooling towers.
The report mentioned several advantages of natural-draft
towers over mechanical-draft systems: reduced requirement for corrosion
inhibitors, less drift, and a long-term monetary cost advantage. The dis-
advantages of a natural-draft tower for the Palisades location were thought
to be the aesthetic impact of a 400-ft-high structure on the naturally scenic
sand dunes and the possibility that a tall tower would disperse fog and drift
and cause icing over a wide area beyond the plant site. There -was a greater
possibility for the plume from a tall tower to affect traffic on nearby high-
ways; plumes from a mechanical-draft system would be expected to pri-
marily affect onsite areas. Dry cooling towers were dismissed as a viable
alternative for the Palisades Plant primarily because the existing turbine
and condenser system could not accept backfitting without a rather severe
penalty in plant operating efficiency and further the state of the art on dry
towers is still in its infancy for an installation the size of the Palisades Plant.
Cooling and spray ponds were also considered as alternatives. The cooling
pond would require a minimum of 1000 acres, and building the pond in the
immediate plant vicinity would require the destruction of the scenic sand
dunes. The possibility of building a pond about a mile inland was also con-
sidered; however, this alternative would have meant destroying 1000 or
more acres of agriculturally productive land. These were felt to be
unacceptable alternatives by the utility. The spray pond was rejected
because its reliability was thought to be too variable under changing
meteorological conditions. The loss of 30 acres of dune land required for
the pond, the great possibility of local icing during winter operation,
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97
unknown drift problems, and the possibility of fogging under adverse
humidity conditions were significant adverse effects making the spray
pond an undesirable alternative.
NUS Corporation evaluated the potential environmental impact
of operating the Palisades Plant with either a 490-ft-high, 485-ft-base-
dia, natural-draft tower or two 50-ft-wide, 470-ft-long, 62-ft-high,
mechanical-draft towers.33 Requisite meteorological data for the Palisade's
site were obtained from Muskegon County Airport, located about 70 miles
north of the site. The meteorological data were analyzed to determine
under what conditions evaporative towers could produce or intensify local
fog conditions.
Natural fog frequencies were correlated against the time of
day, the month of the year, atmospheric stability, wind speed, cloud cover,
and the relative humidity defect (defined as the difference between saturated
relative humidity and the ambient relative humidity). Fog conditions are
dependent on wind direction and more likely to occur for winds from the
east through southwest directions. Also fog is more likely to occur under
neutral and stable atmospheric conditions, particularly between 10:00 P.M.
and 9:00 A.M., and is most often observed with some cloud cover. The
relative humidity defect was the single parameter of greatest importance
in fog formation. For defect values approaching zero, there was a 90%
or greater probability that fog conditions were observed. The report
stated, however, that fogs do exist and can form under conditions when the
relative humidity defect is different from zero, that is, when the atmosphere
is unsaturated. It was determined that the probability of fog formation could
be adequately represented by a single relationship with the relative humidity
defect.
Calculations were performed that yielded estimates of visible
plume persistence, the possibility for induced fogging and icing, and poten-
tial downwash events. With regard to the persistence of a visible plume,
it was felt that the phenomenon represents only an aesthetic problem.
The proposed mechanical-draft facility was found to have a
lower incidence of long plume lengths. About 45% of the visible plumes
were calculated to be dissipated within 350 ft of the towers. Visible plume
lengths longer than 2 miles were estimated to occur for five of the total
hours of the year.
For the proposed natural-draft tower, visible plumes longer
than 2 miles were estimated to occur as frequently as 44% of the total hours
of the year, 65% of these hours occurring during the winter season. In
terms of the aesthetic effects of the visible plume, the areas of greatest
potential concern were the communities of Covert and South Haven. The
estimated percentage of the time the visible plume was calculated to pass
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over these towns was presented in tabular form in the NUS report.33 For
Covert, conditions favoring the downwash of tower plumes over the nearest .
major highway 1-196 were investigated. The frequency of such possible
occurrences for the natural-draft tower were estimated at 2 hr of fogging
and 0.2 hr of icing during the spring, 0.3 hr of fogging during the fall, and
2.7 hr of fogging and 2.2 hr of icing during the winter. These calculations
were stated to be upper limits because observations of actual cooling-tower
installations have not confirmed such downwash phenomena. The report
indicated that mechanical-tower operation under conditions favoring down-
wash would not affect highway 1-196 but only roads and structures on the
plant site.
The probability of induced fogging, calculated for the mechanical-
draft tower, indicated an increase of natural-fog duration a maximum of
14 hr/yr, 6.25 miles northeast of the site. This was the maximum value in
any direction. There are 798 hr of fog occurring naturally in the vicinity;
the median duration of each fog episode is 2 hr. An increase of 14 hr of
duration was then compared with the average fog beginning 1 min earlier and
lasting 1 min longer. This was thought not to be a significant overall change.
The natural-draft tower was found not to induce ground-level fog. The
probability of induced icing was examined. The results showed similar
percentages to increased fog probabilities and therefore were not considered
a significant problem. Again the natural-draft-tower results indicated no
increase.
Several recently published reports in the open literature contain
information relevant to this survey. These are now considered.
9. Natural-draft-tower Operating Observations
A final report describing a cooling-tower field study at the
1800-MWe Keystone Generating Station in western Pennsylvania was pub-
lished in January 197 I.113 The purpose of the study was to describe and
evaluate the potential effects that emissions of water vapor and heat from
325-ft-high, natural-draft, evaporative-cooling towers have on the local
environment and climate. During the period of field observations in
September, November, and December 1969, when the Plant was operating
at one-sixth of its design capacity, no adverse weather effects due to the
operation of the facility were shown conclusively. Drift drizzle beneath
the towers was not detected, nor was any increase in ground-level humidity
underneath the plume path. Long-term pre- and posttower climatological
data from nearby meteorological stations were studied, and only in one
situation was a possibility of precipitation enhancement noted for the two-
year period analyzed.
General observations had shown the visible tower plumes nor-
mally to rise to an altitude of about 650 ft and travel downwind another
650 ft before evaporating. During periods of high humidity and low
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99
temperatures (25-30°F), the plume was observed for thousands of feet
downwind. Casual observations indicated infrequent cloud initiation during
periods of otherwise clear skies. However, the tower plume would often
merge with low stratus clouds. In addition, the tower plume mingles with
the stack effluent from the fossil-fired generating units. Mixing of the two
plumes was confirmed by the presence of acid droplets in the visible por-
tion of the cooling-tower plume.
The report concluded that the full environmental effects of
natural-draft towers could not be stated conclusively from the study because
the actual field observations were intermittently made over one season only,
the plant was not operating at or near full power, and field instrumentation
was lacking in several essential areas.
Hosier reported on a single fogging incident observed during
two years of investigation at the Keystone Plant in which a plume reached
the ground in the vicinity of the natural-draft towers. It was surmised that
an inversion on this occasion was just at the proper height and strength to
confine the plume and its vertical oscillations within the inversion. Photos
taken from an aircraft on the same day and within several minutes of the
Keystone ground-fog incident showed that the injection of water vapor and
condensation nuclei by steel mills in the Pittsburgh area resulted in fog and
a dense cloud extending a hundred miles downwind. The steel mills were
apparently injecting their effluents at the same level as the surrounding
terrain through many small-diameter sources. Hosier stated that had a
power plant injected effluents at the same level, a similar result would have
been expected.
Decker37 has reported on the relative probability of evaporative
cooling systems to produce sufficient ground fog to obstruct visibility. The
results of his survey are given below in the order of increasing probability
of surface fogging. This information was obtained from observational data.
Type of Cooling System
Tall, natural-draft towers, standing
fully equippedwith drift eliminators .
Tall, natural-draft towers, alone
but without drift eliminators.
Tall, natural-draft towers, close to
fossil-fueled smokestacks emitting
acid-producing stack gases.
Mechanical-draft towers emitting
at low level.
Slack water, ponds, and lakes, and
spray ponds.
Probability of
Obstructing Visibility
Extremely low, virtually zero.
Low, but likely to occur with high
humidity and stagnation.
Low to substantial, depending on
prevalence of wind direction and
spacing of stack and tower(s).
Substantial, but highly variable de-
pending upon wind and orientation
or grouping of units.
Low to substantial, depending upon
the stagnation of the atmosphere and
confinement of humidified air.
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Colbaugh et aL,24 in an interim report, noted that there is a
lack of quantitative information for the reliable assessment of the effects
of cooling-tower plumes on the environment. For this reason, a compre-
hensive field investigation of natural-draft-tower plumes was initiated at
the Tennessee Valley Authority's 2808-MWe coal-fired Paradise Power
Plant in Kentucky. The plant has three natural-draft towers, each 436 ft
high and 321 ft in diameter at the base. Tower circulating flow is
290,000 gpm. The towers are designed to reduce the cooling water to
72°F at yearly average atmospheric temperatures of 57.4°F dry bulb and
52.2°F wet bulb and a cooling range of 27.5°F.
General field observations of plume behavior were initiated in
December 1969. A more comprehensive program began in January 1971
to collect, compile, and analyze plume configurations under various mete-
orological conditions. Preliminary results were presented for observations
made during 130 days throughout the 1970 calendar year. These are shown
in Table 8. The data show considerable monthly variation in plume length.
Preliminary evaluation of more recently gathered data has revealed no
significant adverse effect that can be attributed to tower operation. On one
occasion, however, there was a measurable increase in the temperature
and moisture content downwind of the visible plume, with mist being
detected both under the visible plume and downward.
10. Drift Observations
Two recent documents have reported on drift measurements
made on mechanical- and natural-draft towers using different experimental
methods for drift determination. Reference 47 associated the commonly
used drift emission rate of 0.2% of the tower circulating flow as possibly
originating with early developmental tower studies and before efficient
drift-eliminator designs were put into practice. Measurements made on
a commercial mechanical-draft tower (fan diameter, 28 ft; circulation
flow, 12,500 gpm; range, 23°F; approach, 7°F) indicated the tower to have
a 0.005% drift rate. A more extensively studied mechanical-draft tower
(fan diameter, 18 ft; circulation flow, 6050 gpm; range, 10°F; approach, 7°F)
was investigated using a laser-scattering technique and an isokinetic-
sampling technique. The laser-scattering technique yielded a drift rate
of about 0.0055%; the isokinetic method gave about 0.0076%. A natural-
draft hyperbolic-tower (no specifications were given) determination showed
drift to be around 0.005% via isokinetic sampling. The laser-scattering
method yielded drift percentages around 0.00012% for particles larger
than 145 ^im. The 0.005% drift rate was said to be best representative of
state-of-the-art natural-draft towers.
In Ref. 75, isokinetic sampling was conducted on the Homer City
natural-draft cooling tower. The tower is a counterflow design with a full
circulating flow of 208,000 gpm. The tower is stated to be 389 ft high with
a 276-ft-dia base. Measurements indicated the drift for the tower under
full rated conditions to be 0.0025%.
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A guaranteed drift level of 0.002% has been used for two natural-
draft cooling towers recently sold to the Potomac Electric Power Company -
for its Chalk Point Station.2
11. Theoretical Predictions
Portman has reported on an analytical study for analyzing the
downwind extent of fog from a cooling-canal spray for a steady wind blowing
perpendicular to the canal. His analysis was conservative in that it should
overestimate the downwind extent of fog and the frequency of occurrence for
a particular distance. The analysis showed that the plume extent downwind
decreases with increases in air temperature, diffusion intensity, and wind-
speed variation with height, and with decreases in air water-vapor content,
canal temperature, canal length, and efficiency of vapor transfer to air at
the canal.
The analysis was applied to an 800-ft canal at 55 and 75°F, these
temperatures being representative of winter hot-water temperatures of a
once-through and a closed-cycle cooling system, respectively. With the
Detroit City Airport temperature-wind-humidity statistics, a spray canal
in the Detroit area operating at 55°F all year would produce a fog at 1 mile
distance less than 2.5% of the time. For a canal at 75°F, the value is less
than 10%. It was emphasized that these estimates should be regarded as
upper limits.
12. Feasibility
Dry natural-draft cooling towers each 394 ft high with a
357-ft-dia base are being operated in Razdan, Soviet Armenia.1 The power
plant consists of three 200-MWe units, each matched with a natural-draft
dry tower. One tower has been in service since January 1971. Apparently,
the success of the Razdan operation is leading to the development of hard-
ware and dry natural-draft towers for 800- to 1 200-MWe unit capacities.
B. Monetary Costs
To aid in evaluating the impact of the Lake Michigan thermal-
discharge regulations proposed at the March 24, 1971, session of the
Lake Michigan Enforcement Conference, federal representatives presented
a summary outlining EPA's position concerning the status of existing
facilities that would or would not have to consider alternative cooling
schemes to be in compliance with the proposed regulations. However,
little specific data were presented to permit an evaluation of the cost of
implementating these regulations. This section summarizes available cost
information as abstracted from recent documents.
The report entitled "Feasibility of Alternative Means of Cooling for
Thermal Power Plants Near Lake Michigan," presented at the Lake Michigan
Enforcement Conference in September 1970, discussed closed-cycle cooling
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systems and estimated the costs for using them. Tables 9 and 1095 sum-
marize these costs in terms of utility-rate increases to the average resi-
dential customer. These tables are based on the assumption of newly
constructed 1000-MWe fossil and nuclear power plants and show the effects
of low (Case I), normal (Case II), and high (Case III) values of the economic
factors involved in the analysis. These two tables were not intended to
demonstrate the costs associated with the backfitting of existing plants, but
rather represent cost estimates for power plants originally designed to
accommodate these alternatives.
The cost of backfitting cooling facilities was subsequently discussed
by Mr. Tichenor at the recent Michigan,84 Wisconsin,125 and Indiana 3 state
hearings. An Edison Electric institute report, referenced in his testimony,
suggested that retrofitting an existing plant using evaporative towers would
cost $10-12/kW. A Mr. Woodson134 was cited as estimating the capital cost
of converting an 800-MWe plant from once-through to closed-cycle cooling
at about $3,000,000, or $3.8/kW. Mr. Warren, of the FPC, was cited95 in
estimating the cost of backfitting all of the 15,000 MWe of capacity existing
and under construction on Lake Michigan as $150,000,000 or $10/kW. How-
ever, according to the testimony, none of the above estimates included the
cost of reduced generating capacity, increased fuel costs, and increased
operating and maintenance expenditures. According to the testimony, these
items could add an additional $10-15/kW in equivalent capital investment
to the initial capital investment. Adding these costs to the initial capital-
cost values shows a range of backfitting costs of $14-27/kW. Given a plant
load factor of 80% and a fixed charge rate of 14%, a $14-27/kW range is
equivalent to an increase in busbar cost of about 0.3-0.6 mill/kW-hr.
Mr. Tichenor cited an American Electric Power Service Corporation
estimate for backfitting the D. C. Cook Nuclear plant with natural-draft
cooling towers. An initial capital investment of $32,000,000 or about
$15/kW was quoted. The company estimated the summer capability loss
to be 80 MWe. According to the testimony, if this capacity loss was made
up with an equivalent amount of gas-turbine peaking units, the capability
loss would require a capital investment of $8,000,000. Adding to this an
equivalent investment of $5/kW for operation and maintenance and increased
fuel expenses, the total backfitting capital cost was estimated to be $24/kW
($52,800,000 for the 2200-MWe plant). With an 80% load factor and a 14%
fixed-charge rate, the increase in busbar cost was indicated to be approxi-
mately 0.5 mill/kW-hr.
Cost figures were cited for the Palisades Nuclear Power Plant to
backfit with mechanical-draft towers and radioactive-emissions-control
equipment: $15,000,000 in capital equipment, with $3,000,000 annually
being required for the fixed charges on the capital, reduced efficiency, and
increased operation and maintenance costs. With an assumed 80% load
factor, $3, 000,000/yr corresponds to a busbar cost of 0.6 mill/kW-hr.
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Table 9
Increase In Busbar Cost Over Once-Through Design
(Fossil Fueled Plants)
95
Cost Increases (Mills/KW-HR)
Case
I
II
III
Wet Wet Cooling Spray Dry Dry
Mech. Nat. Pond Canal Mech. Nat.
(Mills/KW-HR) Draft Draft Draft Draft
4.57 0.079 0.142 0.
5.94 0.096 0.179 0.
7.53 0.117 0.218 0.
Economic Factors
Case Plant Capital Fixed Charge
Cost ($/KW) Rate (%)
I 110 11
II 135 14
III 160 17
Table 10
012 0.049 0.46 0.43
021 0.058 0.58 0.53
039 0.070 0.70 0.64
Fuel Cost Land Cost
(*/106 Btu) ($/Acre)
25 250
30 500
35 1000
Increase in Busbar Cost Over Once-Through Design"^
(Nuclear Plants)
Cost Increases (Mills/KW-HR)
Busbar Cost Wet
Once-Through Mech.
Case (Mills/KW-HR) Draft
I-N 4.37 0.085
II-N 5.83 0.108
III-N 7.60 0.135
Economic Factors
Case Plant Capital Fixed Charge
Cost ($/KW) Rate (%)
I-N 135 11
II-N 160 14
III-N 185 17
Wet
Nat. Cooling
Draft Pond
0.138 0.021
0.177 0.033
0.219 0.061
Fuel Cost Land Cost
U/106 Btu) ($/Acre)
15 250
19 500
24 1000
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105
Cost estimates were also presented for modifying existing discharge
designs to conform with mixing zone limitations. Tennessee Valley Authority
data on the 3450-MWe Browns Ferry plant indicated that a backfitted diffuser
system would cost an additional $2,900,000 (roughly equivalent to 0.02 mill/
kW-hr). Modifications to the once-through system for the 2600-MWe
Cumberland Plant were estimated to cost $4,100,000 (about a 0.03 mill/kW-
hr busbar cost equivalent).
Estimates for backfitting the 1047-MWe Waukegan and the 944-MWe
State Line plants with modified discharges were given as $9,000,000 and
$11,500,000, respectively.20 With plant-load factors of 65% and a fixed-
charge rate of 14%, the increase in busbar costs were calculated to be
about 0.2 and 0.3 mill/kW-hr, respectively.
In summary, Mr. Tichenor's testimony given at the three state
hearings concluded that:
1. For power plants initially designed to accommodate closed-
cycle condenser cooling systems, the increase in busbar costs over once-
through cooling is expected to be around 0.2 mill/kW-hr for an evaporative
tower system (nominally a 1% residential rate increase).
2. The increased cost for backfitting with an evaporative tower
system is estimated to be around 0.6 mill/kW-hr (nominally a 3% resi-
dential rate increase).
3. Increased costs due to modifying existing discharges range
widely from 0.02 to 0.3 mill/kW-hr (nominally a 0.1-1.5% residential rate
increase).
These busbar costs were related to the average residential consumer
around Lake Michigan by assuming the consumer pays roughly 20 mill/kW-
hr for his electrical power.
1. Pulliam Plant
Evan W. James, Wisconsin Public Service Corporation, stated
at the Wisconsin hearings125 that decreasing the heat content of the 392-MWe
Pulliam plant discharge by 50% would cost some $3,770,000 in capital in-
vestment. Annual costs, including carrying this investment, operating costs,
and maintenance costs, were stated to approximate $1,035,000 annually. If
the plant went to a completely closed system rather than a tempering sys-
tem, the above costs were stated to roughly double.
2. Kewaunee Plant
Backfitted mechanical-draft cooling towers at the 540-MWe
Kawaunee Nuclear Plant were estimated by Mr. James to be $10,000,000 in
construction costs.125 Tower operation was stated to decrease the capacity
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of the plant by 7.1% and the efficiency by 3.8%. The cost of these towers in ^
terms of investment, losses in plant performance, and operation and main-
tenance was stated to be about $3,650,000 annually. This revenue require-
ment expressed as an evaluated cost was given as $24,300,000.
The Kewaunee Environmental Report130 listed additional cost
figures for backfitted cooling schemes. For a single, natural-draft evapora-
tive tower, the added construction costs for tower installation would be
$16,902,000. Annual operating costs and capacity makeup were said to cost
around $2,037,000 per year. The total additional annual cost for backfitting
to a natural draft tower would then be $4,577,000 per year.
For mechanical-draft towers, backfitting costs were stated to
be $10,118,000 in construction or, equivalently, $1,510,000 per year. Annual
operating and maintenance costs, together with makeup of capacity, were
said to be $2,105,000. Thus the total additional annual cost resulting from
the backfitting of mechanical-draft towers is $3,615,000.
The costs that would result from backfitting with a cooling lake
were estimated to be $18,068,000 in capital costs or, equivalently, $2,700,000
annual cost. Operating and maintenance and capacity makeup costs were
given as $2,675,000 per year. The total incremental annual cost resulting
from the backfitting of a cooling lake is thus given as $5,375,000 per year.
A spray-canal system was also investigated. The capital in-
vestment in such a system was estimated to be $11,410,000, or when con-
verted to an annual cost, $1,710,000 per year for amortization and interest.
Operating and maintenance costs, together with generating capacity makeup,
were estimated to add an additional $2,208,000 per year. The total annual
cost for a backfitted spray-canal system was given as $3,918,000.
3. Point Beach Plant
Testimony given at the Wisconsin hearings125 by Mr. Patterson,
Sargent and Lundy Consulting Engineers, estimated the construction costs
of backfitting the 1046-MWe Point Beach Plant at $23,510,000 for a cooling
lake, $22,936,000 for a mechanical-draft evaporative-tower system, and
$31,797,000 for natural-draft evaporative towers. These costs reflect
interest and estimated escalation charges and, in addition, land purchases
for the cooling-lake alternative. With the costs for capability and efficiency-
loss makeup and operating and maintenance expenses evaluated on a present-
worth equivalent-investment basis, the evaluated cost of the cooling lake
was estimated to be $49,759,800; the mechanical-draft tower system,
$45,350,000; and the natural-draft towers, $56,493,400.
The Environmental Statement for the Point Beach Plant121 pro-
vided additional information on the estimated yearly costs of backfitting the
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entire plant with alternative cooling systems: $7,600,000 per year for
mechanical-draft towers, $9,500,000 per year for natural-draft towers,
$9,100,000 per year for a spray-canal system, and $9,200,000 per year for
a cooling lake.
4. Zion Station
The Environmental Report for the Zion Station26 discusses the
economic costs associated with backfitting the Plant with six alternative
cooling schemes. The costs represent additional capital investments,
capital-investment equivalents for loss of capability, and added operating
costs to implement the particular alternative. For mechanical-draft cooling
towers, the estimated installation costs were $72,000,000, with loss of
capability and operating expenses estimated to be $45,000,000, totaling
$117,000,000.
For natural-draft towers, the installation costs were estimated
to be $79,000,000, with capability loss and operating costs amounting to an
equivalent $45,000,000, totaling $124,000,000.
Installation charges on dry mechanical-draft cooling towers
were estimatedto be $343,000,000, with an additional $ 1 03,000,000 requiredfor
capability loss and operating expenses, yielding $446,000,000 for the present
total worth. The addition of specially constructed spray ponds and even
spray devices within the lake itself were considered along with a cooling lake
as the remaining alternatives. No cost estimates were made for these.
The reader should be aware of the fact that the Zion cost
estimates were based on specialized tower designs. Air traffic in the
Zion vicinity requires limitations on the maximum tower height; 250 ft was
used as a design basis.
5. Waukegan and State Line Plants
Cost estimated for backfitting the Waukegan and State Line
Power Plants with subsurface high-velocity discharges were presented in
a letter from O. D. Butler, Commonwealth Edison, to the Chairman of the
Four-State Enforcement Conference.20 The letter stated that the initial
capital investment, including escalation, contingency, and top allowances
for backfitting the Waukegan Station with mechanical- and natural-draft
cooling towers, would be (as revised) $14,174,000 and $19,448,000, re-
spectively. With the equivalent capital investment for operating expenses
and loss in capacity included, the total cost of backfitting the Waukegan
station with towers was given as $21,390,000 and $25,755,000, respectively.
For the State Line Plant, the total costs for backfitting with
mechanical- and natural-draft towers were estimated to be (as corrected)
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$37,128,000 and $51,195,000, respectively. The estimated capital investment
alone for the State Line plant towers was given as $26,983,000 and
$38,657,000, respectively.
6. Michigan City Plant
Mr. C. W. Kern, Northern Indiana Public Service Company, pro-
vided a capital-cost estimate of $14,227,491 for backfitting the 719-MWe
Michigan City Generating Station with an evaporative-tower system. This
plant has four units; one 500-MWe unit is currently under construction.
Much of the cooling-system facilities originally designed for this unit were
still usable for the closed-cycle tower system, and this estimate reflects
the situation. No other information concerning operating expenses or
capacity makeup costs were given.
7. Bailly Nuclear Plant
In the Environmental Statement for the 685-MWe Bailly Plant,120
two cooling schemes were discussed: a natural-draft evaporative tower (to
be used at the facility) and an alternative once-through system. The capital-
cost differential between the tower and the once-through system was given
as $7,000,000. The operating-cost differential evaluated on a present-worth
basis, assuming a 30-year plant life and discount rate of 8.75%, showed the
tower to require an additional $4,000,000; the total evaluated cost differ-
ential thus was $11,000,000. The Bailly plant is currently under initial
phases of construction. Hence these cost estimates are for a new facility
with the cooling system optimized for both alternatives; i.e., these are not
backfitting-cost differentials.
8. D. C. Cook Plant
Testimony by John Tillinghast, Indiana & Michigan Electric
Company, concerning backfitting the D. C. Cook Plant with evaporative-
cooling towers was given at the Michigan hearings.84 The capital cost for
natural-draft towers was stated to be $55,935,000, including interest and
escalation. (These figures update information given earlier on the D. C.
Cook Plant.) In addition to this, $6,000,000 per year was estimated to
account for operating and power-loss replacement costs. These costs were
translated to the consumer by proposing that they could be divided equally
among the 358,545 utility customers. With this so done, the bills of these
customers were stated to increase on the average between 7.5 and 9%, or
by about $41 per year.
The Environmental Report65 for the Cook Plant added that the
cost of backfitting the plant with mechanical-draft towers would be about
$63,000,000. An annual penalty of about $3,400,000 would be incurred as
the result of losses in plant efficiency. The cost of backfitting the plant
with a cooling pond was said to be about $60,000,000. A significant loss in
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i plant efficiency would result with pond operation. This loss, when translated
, into dollars, represented an additional operating cost of about $6,000,000
per year.
9. Palisades Plant
Cost estimates for backfitting the 700-MWe Palisades Power
Plant with evaporative towers perhaps represents the best information
currently available, since this plant is actually effecting a change from
once-through to mechanical-draft cooling towers. In a letter from R. C.
Youngdahl, Consumers Power Company, to L. R. Rogers, USAEC,13
Mr. Youngdahl estimated the capital cost of backfitting with a mechanical-
draft tower system as $20,000,000 and the increased annual operating cost
as $4,500,000. In the Environmental Statement for the Palisades Plant,119
the 4,5-million-dollar value was used to calculate an equivalent present-
worth value of $47,000,000 based upon a 30-year plant life and a 8.75%
yearly discount rate. The incremented cost of the mechanical-draft towers,
backfitted over the presently installed once-through system, was then
estimated to be $67,000,000 on a present-worth basis. Relative costs cited
the report for backfitting with high-velocity onshore or offshore discharges
ranged from 1 to 5 million dollars, respectively.
10. General Observations
John Z. Reynolds, Consumers Power Company, testified at the
Michigan hearings84 concerning the cost of outfitting Consumer's 750-MWe
system, present and proposed, with towers. He estimated that $76,000,000
would be required in capital costs and $73,000,000 additional would be
required to account for the 3-5% system-capacity losses. Total annual
costs, including fixed charges, added fuel costs, and operating and main-
tenance costs were estimated to be about $31,000,000 per year. Total
capital costs, including equivalent costs, were projected to be about
$244,000,000.
Mr. Wayne Wingert, Detroit Edison Company, testified at the
Michigan hearings84 that it would require about $200,000,000 in capital cost
to convert the Detroit Edison System to closed-cycle cooling. He stated
that this investment, including operating costs, maintenance, etc., would
result in a total annual cost of $43,000,000 or roughly an increase of 12%
in production cost per kilowatt hour, which would mean slightly less than
a 6% direct increase in the customer's bill.
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n
VI. CHEMICAL INPUTS
A. Summary of Power-plant Effluents
Only limited information is available as to the chemical effluents
discharged to Lake Michigan from the power plants around its shoreline.
Significant data are available in the applications for permits to discharge,
submitted to the Army Corps of Engineers. The operators of all power
plants have been requested to file such applications within the past year.
Of the 27 power plants discharging, or to discharge into Lake Michigan or
near the mouth of its streams, 18 applications were available at the time
they were reviewed in the Region V EPA Office.
Examining the information in the applications revealed a number of
inconsistencies and a substantial lack of the information required. Chemical
analyses of intake and effluent water were not available with precision ade-
quate to allow the calculation of incremental loads by direct subtraction,
except in unusual circumstances. The best information, and it is believed
the most pertinent, was given in the applications for Plants No. 13, 14, and
16, the proposed Zion Nuclear Plant, and the operating Waukegan and
State Line Plants. For these cases, chemical constituents actually added
or expected to be added to the coolant streams were identified and numer-
ical values given. Accordingly, the effluents of all other plants were pro-
rated on the basis of the data for these three. (Due to variability in the
composition of the effluent from the sluicing operation, the data in the
application for the Waukegan Plant lacked internal consistency; for this
reason, upon request, Commonwealth Edison provided average analyses
for eight monthly samples,21 and these data were used in the calculations.)
This procedure uses the tacit assumption that water-treatment practices
and procedures are the same for all the other plants as for those for which
the data are available. This is not entirely true, and the magnitude of the
inaccuracies cannot be evaluated at this time. Nevertheless, the results,
summarized in Table 11, are probably approximately correct and of suffi-
cient value to justify their publication.
Two separate categories were established, nuclear and coal-fired.
In each category, the prorating was done in terms of the average power
level at which the plants were operated, calculated, and shown for 18 of the
plants in Table 5. The input information was the average megawatt-hours
per day output of the plants, as provided by the power companies on the
Corps of Engineers applications. These numbers were believed to be
inaccurate in a few cases and were not available in several other cases.
In these instances, an overall average operating megawatt level was
assigned as follows: Using plant capacities from Federal Power Commis-
sion statistics,49 average plant factors were calculated for the available
12 coal plants (52.7%) and two nuclear plants (64.0%). The coal-plant
average -was multiplied by the plant capacity to obtain the average mega-
watt levels for the remaining coal plants, and the nuclear-plant average
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3.3 Standard Manufacturing Processes
3.3.1.1 Chlorination
3.3.1.2 Filtration
3.3.1.3 Clarification
3.3.1.4 Lime-Soda
3.3.1.5 Ion Exchange Processes
3.3.1.6 Evaporation
3.3.1.7 Reverse Osmosis
3.3.2 Boilers
3.3.3 Condenser
3.3.4 Condensate Treatment
3.3.5 Ash Handling
3.4 Auxiliary Processes
3.4.1 Condenser Cooling Water Heat Disposal Systems
3.4.1.1 Once-through Condenser Cooling
3.4.1.2 Cooling Device on Condenser Discharge with
Recirculation
3.4.1.3 Cooling Device on Condenser Discharge
3.4.1.4 Cooling Device on Condenser Discharge with Partial
Recirculation and/or Dilution
3.4.2 Service Water Systems
3.4.3 Sewage Plants
3.4.4 Cool Storage
3.4.5 Oil Leakage
3.4.6 Hydrovactors
3.4.7 Other On-site Activities
3.4.8 Accidental Potential Pollution Sources
3.5 Typical Future Manufacturing Processes
3.6 Normal In-plant Pollution Control
4. Standard Raw Waste Loads
4.1 Concept of Standard Raw Waste Load
4.2 Waste Load Data Sources
4.3 Standard Raw Waste Loads from Standard Manufacturing Processes
4.3.1 Water Treatment
4.3.2 Boiler
4.3.3 Condenser
4.3.4 Condensate Treatment
4.3.5 Ash Handling
4.4 Standard Raw Waste Loads from Auxiliary Processes
4.4.1 Heat Disposal Systems
4.4.2 Service Water Systems
4.4.3 Other Waste Water Sources
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Typical waste loads are tabulated, and some methods of reducing quantities *
of waste are outlined. The standards are intended to facilitate consideration
of the effects of power plants on the environment.
C. Chemicals for Removal of Organic Deposits in Condensers and Process-
Water Systems
When natural waters are passed through circuits of the kind used in
power plants, fouling deposits that interfere with the flow of water and heat
form on all surfaces with which the water comes in contact. These deposits
may be in the form of hydrous oxides of metals, suchas iron and chromium;
they may be scales, such as carbonates or sulfates of calcium and magne-
sium; or they may be organic in nature. The organic deposits are formed
by the deposition of living organisms, followed by their continued growth.
In the presence of sunlight, the organic deposits are typically algal, whereas
in unirradiated heat-transfer equipment, they are typically bacterial.
For removal of the slime formed in power-plant condensers and
other heat exchangers (such as those in the process-•water systems),
chlorine, added to the cooling water, has been found to be effective and in-
expensive. In most power plants, it is injected into the cooling water in the
form of elemental chlorine or in the form of a strong solution of sodium
hypochlorite for a few relatively brief (10 or 15 min typically) periods per
day. This system is called shock defouling. A considerable fraction of the
organisms in the deposits are killed, and the organic material and much of
the scale are dislodged and carried out in the cooling water. Organic ma-
terial formed on all parts of the system downstream of the condenser reacts
with residual chlorine and helps to reduce its level at the point of discharge
to the lake.
In addition to its toxicity to the slime bacteria, chlorine has the ad-
vantage that it is chemically unstable in water and is quickly degraded in
nature. This reaction is catalyzed by light; the data of Hancil and Smith,56
as treated by Draley,40 show that under the laboratory ultraviolet illumina-
tion, the time in seconds to reduce the concentration of free chlorine from
c0 to c is t = 7.8 In (c0/c). This advantage is partially lost if ammonia is
present in the cooling water, since the chloramines formed by reaction be-
tween ammonia and chlorine have longer lifetimes in natural waters than
does the free chlorine (which exists in the form of hypochlorous acid or the
hypochlorite ion).
The optimum utilization of chlorine for defouling would require that
the chlorine and chloramines be decayed or dissipated before discharge of
the effluent stream to the lake (or other natural bodies of water in more
general terms). A common chlorination practice, though by no means
universally practiced, which helps to achieve this condition, is to have the
total circulating-water stream divided into parts, only one of which is
chlorinated at a time. The remixing of the chlorinated and unchlorinated
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streams then leads to the removal of chlorine by the so-called chlorine-
demand constituents of the untreated water. It is also possible to remove
residual chlorine chemically by adding reducing agents such as sodium
sulfite or bisulfite. For example, in one installation a ratio of sodium bi-
sulfite to residual chlorine of 3.8:1 decreases the residual chlorine level
from 1 to below 0.1 ppm in less than 5 sec.89
The use of chlorine and the problems pertinent to the avoidance of
significant toxic doses to the lake (or other receiving waters) are the sub-
jects of the recent analysis by Draley.40 The need for (a) standards,
(b) discharge monitoring, and (c) development of calculational knowledge
and skills are emphasized.
Significant new publications related to chlorine and its toxicity con-
cern standards and the effects of dilute solutions on fishes.
In the area of standards, the Michigan Water Resources Commis-
sion, Water Quality Control Division, issued in the spring of 1972 an
Interim Effluent Standard for Industrial Discharges of Chlorine (to be re-
viewed as to adequacy and suitability on or before December 1972). It
specifies that "Waste streams shall contain not more than 0.05 mg/'t/ of
total chlorine (free and combined) in the discharge to receiving waters
after utilizing available dilution and at a point to be determined by the
Chief Engineer of the Commission, where application of chlorine is on a
continuous basis; or contain not more than 0.5 mg/'t of total chlorine (free
and combined) in the discharge to receiving waters after utilizing available
dilution and at a point to be determined by the Chief Engineer of the Com-
mission, where continuous application of chlorine will be limited to not
more than 30 minutes during any 2-hour period."
Oh December 20, 1971, William A. Brungs forwarded to
Mr. Francis T. Mayo, Regional Administrator for EPA Region V,
"Water Quality Criteria Recommendations for Residual Chlorine in Re-
ceiving Waters for the Protection of Fresh Water Aquatic Life," by the
Staff of the National Water Quality Laboratory, Duluth, Minnesota.45 Four
separate levels of residual chlorine, that would be applicable to
Lake Michigan or other receiving water, were identified, in terms of tox-
icity and usage. During continuous use at 0.01 mg/liter or less, trout
reproduction and some important fish food organisms would probably not
be protected and the situation could be partially lethal to sensitive life
stages of sensitive fish species. For continuous usage at 0.002 mg/liter
most aquatic organisms should be protected. For intermittent use at
0.1 mg/liter, not to exceed 30 min/day; or 0.05 mg/liter, not to exceed
2 hr/day, significant kills of aquatic organisms should not occur and the
aquatic ecology should not be adversely affected. These recommendations
require the use of the amperometric titration method; some of the other
methods commonly used in the determination of residual chlorine have
been shown to be inaccurate. The National Water Quality Laboratory
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recommendations were reissued about June 1972. There were no changes
in the specific recommendations. The text was modified, apparently with
the objective of assisting the reader in considering possible applicability of
the criteria.
The same document summarizes the literature that is most perti-
nent to quantitative effects of low levels of residual chlorine on a number
of varieties of fish species. Twenty-four references are given. Dr. Brungs
has prepared a more extensive literature review on the effects of residual
chlorine on aquatic life.18 Covered are the aqueous dilute solution chemis-
try of chlorine, its effects on aquatic life, chlorinated wastewater treatment
plant effluent, chlorination for antifouling, and results of standard bioassays.
The following general statements resulted from the review: (1) Tests of
residual chlorine toxicity should be conducted using continuous-flow bioas-
say procedures and the most precise, sensitive, and appropriate analytical
method for determining residual chlorine; (2) typical environmental vari-
ables do not significantly affect residual chlorine toxicity, although at lower
pH toxicity may be increased as a result of the greater proportion of free
chlorine present, but this difference is slight; (3) trout, salmon, and some
fish-food organisms are more sensitive than warm-water fish, snails, and
crayfish; (4) chronic toxicity effects on growth and reproduction occur at
much lower concentrations than acutely lethal concentrations; (5) most of
the lethal effects of residual chlorine occur within 12-24 hr, with lethal
effects of free chlorine being more rapid than those of chloramines;
(6) chlorination of wastewater results in a variety of chlorinated com-
pounds in addition to chloramines, and this aspect needs much greater re-
search emphasis; (7) residual chlorine is more persistent than the few
minutes or hours indicated by some authorities; (8) dechlorination with
sodium bisulfite, sodium thiosulfate, and sulfur dioxide, among others,
greatly reduces or eliminates toxicity due to residual chlorine, and the po-
tential chronic toxicity resulting from such additional treatment requires
further research; (9) substitutes for chlorination of wastewaters or cooling
waters should be used whenever feasible, but only after adequate acute and
chronic toxicity studies to determine the potential environmental impact of
the substitutes, and their efficacy as adequate disinfectants must be verified.
The Staff of the Michigan Water Resources Commission has under
way a program to assess, under field conditions, the effects of chlorinated
condenser cooling water on aquatic life. Truchan and Basch118 have re-
ported observation of a major fish kill and concomitant analyses for total
residual chlorine near the Karn-Weadock power plant complex near the
mouth of the Saginaw River. A maximum 1.36 mg/liter of residual chlorine
was detected during the period of measurement (corresponding to the time
of addition of chlorine in the plant). This study shows that intermittent dis-
charges of chlorine from power plants can be acutely toxic to fish life in the
discharge channel, perhaps partly because fish sometimes congregate in the
vicinity of plant-water discharges. Caged fish studies at the same plant
were reported by Basch and Truchan11 and Wuerthele and Truchan.135
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Short-term tests at chlorine levels up to 0.4 mg/liter were run. Fathead
minnows suffered no mortality during the exposure periods. Rainbow trout,
however, suffered 90% mortality after exposure to an average total residual
chlorine (TRC) concentration of 0.106 mg/liter for 16.18 hr out of the 62-hr
test period. Mortality was also observed after the second exposure for
5.52 hr out of the 29-hr test period. Acknowledging the fact that the fish in
the study were caged and could not avoid the discharge, the results do indi-
cate that intermittent low-level discharges of chlorine from power plants
can be toxic to certain fish species resident in the discharge area.
Massey, also of the Bureau of Water Management, described the
avoidance of chlorine discharges and the killing of fish at the Big Rock Point
power plant in May 1972.81 The TRC level in the discharge channel rose,
briefly out of control due to a malfunction, to a maximum measured value
of 3.05 mg/liter. The highest readings obtained in the plant by
Consumers Power personnel using the orthotolidine color comparator
was 0.2 mg/liter TRC. Instances of apparent incorrectly low readings
through the use of the orthotolidine comparator have also been recorded
at other sites.
Fish kills due to chlorine discharge in power-plant circulating
water have also occurred in other water bodies, including salt water.
Fairbanks, Collings and Sides48 have reported such events in the
Cape Cod Canal.
The Michigan Bureau of Water Management has also done caged-
fish field research downstream of municipal wastewater-treatment plants.
In one study, sponsored by EPA, toxicity to rainbow trout has been shown
at distances up to 0.8 mile downstream. Fathead minnows appeared
adversely affected up to 0.6 mile downstream. Total residual chlorine
concentrations less than 0.1 mg/liter were toxic to fathead minnows. The
rainbow trout 96-hr total residual chlorine PL-50 concentration below
two plants was 0.023 mg/liter.86
Alternatives to chlorine defouling, receiving increasing attention,
are mechanical methods of removing fouling deposits. Mechanical devices
can consist of balls, plugs, or brushes; they are blown through the tubes of
heat exchangers such as steam condensers by the force of the flowing fluid
or by mechanical devices. Automatic systems are offered by Amertap
Corporation and American M. A. N. Corporation. The Amertap system
circulates sponge-rubber balls in a special bypass cooling-water stream.
The M. A. N. System uses nonmetallic brushes, which are restrained in
the tubes by plastic baskets attached to the ends of each tube. By revers-
ing the flow of the cooling water, the operator can automatically "shoot"
the tubes with the brushes. The Amertap system has received most favor-
able attention by American power companies; it is being installed in
Commonwealth Edison's Zion Nuclear plant.
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American experience with the Amertap system is limited, and it is ».
not yet possible to say whether it will provide a desirable substitute for
chlorine defouling in all situations. In particular, the entrainment of small
debris sometimes leads to plugging when the debris and the ball enter a
tube at the same time and restricts flow when it is entrapped in the ball-
collecting device. Mechanical treatment is not ordinarily used in other
places in power plants where defouling is required. Of particular note are
the service-water systems used to remove heat from a number of auxiliary
items of equipment at a typical plant. The installation of mechanical sys-
tems for each of these heat exchangers has been unattractive, and plants
using mechanical treatment for condenser tubes still chlorinate service-
water systems. In these cases it remains necessary to examine the con-
centration of residual chlorine after dilution with the main circulating-water
stream. At Zion the resulting solution is more dilute than the maximum
appropriate concentration in the EPA-recommended criteria.46
D. Chemicals for Treatment of Water-Steam System
Steam-boiler systems are typically treated with chemicals to mini-
mize the formation of scale and corrosion products on steam-generator
surfaces and to minimize corrosion in the remainder of the system. Makeup
water is characteristically highly purified to minimize the amount of scale-
forming chemicals, such as dissolved calcium and magnesium. Reducing
agents such as hydrazine and sulphite are commonly added to maintain very
low oxygen contents (oxygen accelerates corrosion of the steel system).
Phosphate is added to help tie up the small residual amounts of calcium
and magnesium and to serve as a corrosion inhibitor. Morpholine is added
as a volatile corrosion inhibitor that will distil with the steam and protect
return piping. Chromate has been used in some systems because of its
effectiveness as a corrosion inhibitor. Since the last Enforcement Confer-
ence, no hew information considered valuable to the Lake Michigan problem
has been encountered.
E. Chemicals for Treatment of Cooling Towers and Ponds
The use of cooling towers simplifies the treatment of waste heat,
but adds complexity in water treatment. Cooling-tower recirculating sys-
tems, and in particular the towers themselves, have corrosion and fouling
problems that are more difficult to treat adequately than once-through
cooling systems. Bacterial and algal slimes sometimes grow rapidly on
the aerated cooling-tower circuits. Some companies are now trying to
develop new and optimized chemical treatments. Although there has been
no universally used chemical treatment of recirculating circuits, and
hence no standard content of additives in the blowdown, a group of chemical
additives is commonly encountered. Mixtures of chromate, zinc, and phos-
phate are commonly used for corrosion control. Microbial problems are
controlled by addition of chlorine, hypochlorites, and nonoxidizing organics,
such as chlorophenols, quaternary amines, and organometallics. Silt
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deposition is controlled by use of polymers such as lignin-tannin disper-
sives, polyacrylamide, polyacrylates, polyethyleneimine, and other poly-
electrolytes. Acid or alkali is used for pH control, and organic phosphorus
compounds such as organic phosphates, aminomethylene phosphonate, and
polyesters are often used to control corrosion and scale formation and to
provide dispersing effects.54
The Atomic Energy Commission, in its environmental statement
for the Palisades Plant,119 has warned of the possibility that cooling towers
might prove, overall, more adverse to the environment than once-through
cooling and discharge to Lake Michigan. The following is quoted from the
Summary and Conclusions section of that document:
"The use of the (cooling) towers reduces impingement, entrainment
and thermal impact on fish and other aquatic biota. However, they intro-
duce a long-term adverse impact of chemicals from continuous blowdown ...
of concentrated salts which would accumulate in Lake Michigan over the
long-term operation of the cooling towers and cause serious degradation
of the water quality of Lake Michigan in the vicinity of the Plant. The in-
creased concentration would result in phosphate enrichment of the lake
water and reconcentration of zinc and chrornate in biota.
"Cooling towers introduce terrestrial environmental impacts on
floraand fauna ... from chemicals deposited by the drift, evaporation... of
lake water, fogging under certain meteorological conditions, and icing in
the winter. Although the (Palisades) towers are hidden from view, they
will cause an adverse aesthetic effect from the lake side and will have a
noise impact on the area.
"(For Palisades) the cooling towers will not only require an increase
in capital and operating costs of the order of about $67,000,000 but will re-
sult in a decrease of about 3% in net electrical output due to the electrical
power required for the fans in the towers."
These statements are supported by an appended 18-page review
and evaluation of "Cooling Tower Chemicals--Potential Environmental
Degradation." Also included is a discussion of blowdown treatment to re-
move the toxic elements chromium and zinc. Commercially available
methods for these removals could be applied to recirculating cooling water
system blowdown.
There are some notable differences between the treatment of re-
circulating cooling-tower circuits with chlorine and the treatment of once-
through circulating-water circuits with chlorine. Since the chlorine in the
recirculating circuit must not only clean the condenser tubes, but also the
surfaces in the cooling tower, it is no longer possible to add chlorine only
to the extent necessary to last for passage through the condensers. Instead
it is necessary to overcome the total chlorine demand in the entire
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recirculating system, both in the form of dissolved chemicals and organic
deposits on surfaces. Chloramines, produced by the reaction of free
chlorine with nitrogen-bearing compounds, are lost to a considerable
extent by volatilization in the aeration while passing through the cooling
tower.55 It is also possible to chlorinate by adding enough free chlorine
to initiate the "breakpoint" reaction, in which the chloramines are oxidized
to nitrous oxide, which is in turn lost by aeration. The techniques and the
operating procedures for cooling-tower circuits have not yet been well
established, and remain to be optimized. Additionally it will be necessary
to establish some procedure in which the residual chlorine in the recircu-
lating cooling water is not discharged to the natural body of water through
the blowdown during periods of chlorination. Possibly blowdown could be
suspended for periods; plants now being built have included holding ponds
in the blowdown circuit so there is time for chlorine decay before dis-
charge. Separately pumped dilution streams are possible, and chemicals
could be added to remove the residual chlorine. No cooling-tower recircu-
lating cooling circuits are operating on Lake Michigan. The Palisades Nu-
clear Plant, the Bailly Nuclear Plant, and the Michigan City Plant are
planning to operate in this fashion.
No cooling ponds are proposed for use on the shores of Lake Michigan.
For other installations, such cooling ponds have effected certain simplifi-
cations. Short-term chemical additions are discharged, in a more dilute
form, over a longer period of time. Unstable chemicals like chlorine are
typically completely decayed away before reaching the point of blowdown,
and so are not significantly present in the plant discharge.
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REFERENCES
1. Anonymous, "Dry Cooling Tower Uses Steel Structure," Electrical
World, April 1, 1972.
2. Anonymous, "Contract," Electrical World, May 1, 1972, p. 106.
3. Asbury, J. G., "Effects of Thermal Discharges on the Mass/Energy
Balance of Lake Michigan," ANL/ES-1, July 1970.
4. Asbury, J. G., and Frigo, A. A., "A Phenomenological Relationship for
Predicting the Surface Areas of Thermal Plumes in Lakes," ANL/ES-5,
April 1971.
5. Ayers, J. C., et al., "Benton Harbor Power Plant Limnological Studies,
Part VII, Cook Plant Preoperational Studies, 1970," Special Report
No. 44, Great Lakes Research Division, The University of Michigan,
Ann Arbor, Michigan, March 1971.
6. Ayers, J. C., et al. , " Benton Harbor Power Plant Limnological Studies,
Part IV: Cook Plant Preoperational Studies, 1969," Special Report
No. 44, Great Lakes Res. Div., The University of Michigan, 1970.
7. Ayers, J. C., et al., "Benton Harbor Power Plant Limnological Studies,
Part IX, The Biological Survey of 10 July 1970," Special Report No. 44,
Great Lakes Research Div., The University of Michigan.
8. Ayers, J. C., O'Hara, N. W., and Yocum, W. L., "Benton Harbor Power
Plant Limnological Studies, Part VIII, Winter Operations 1970-1971,"
The University of Michigan, Great Lakes Research Division, Special
Report No. 44, June 1971.
9. Aynsley, E., and Jackson, M. R., "Industrial Waste Studies: Steam
Generating Plants." Draft final report of Freeman Laboratories, Inc.,
for the Water Quality Office of the Environmental Protection Agency,
May 1971.
10. Badger, R. G., and Roessler, M. A., "An Ecological Study of South
Biscayne Bay and Card Sound," Zooplankton, pp. 1-29, Progress Re-
port to U.S. Atomic Energy Commission and Florida Power and Light
Company, University of Miami, 1971.
11. Basch, R., and Truchan, J., A Caged Fish Study on the Toxicity of In-
termittently Chlorinated Condenser Cooling Waters at the Consumers
Power Company's J. C. Weadock Power Plant, Essexville, Michigan,
December 6-10, 1971.
12. Beer, L. P., "Natural and Unnatural Water Temperatures in Zion-
Waukegan, Illinois Area of Southwest Lake Michigan," Proc. 14th Conf.
Great Lakes Res. 1971, International Assoc. Great Lakes Research,
1971, pp. 507-521.
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13. Beer, L. P., and Pipes, W. O., "A Practical Approach, Environmental
Effects of Condenser Water Discharge in Southwest Lake Michigan,"
Commonwealth Edison Co., Chicago, Illinois, 1968.
14. Beeton, A. M., "Changes in the Environmental and Biota of the Great
Lakes," in Eutrophication: Causes, Consequences, Correctives,
National Academy of Science, 1969, pp. 150-187.
15. Bersamin, S. V., "A Preliminary Study of the Nutritional Ecology and
Food Habits of the Chubs (Leucichthys) and Their Relation to the Ecol-
ogy of Lake Michigan," Papers of Michigan Academy of Science, Arts
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