vvEPA
United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Research Triangle Park NC 27711
EPA-600/7-79-090
March 1979
N on water Quality Impacts
of Closed-Cycle Cooling
Systems and the
Interaction of Stack Gas
and Cooling Tower Plumes
Interagency
Energy/Environment
R&D Program Report
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports in this series result from the
effort funded under the 17-agency Federal Energy/Environment Research and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects; assessments of, and development of, control technologies for energy
systems; and integrated assessments of a wide range of energy-related environ-
mental issues.
EPA REVIEW NOTICE
This report has been reviewed by the participating Federal Agencies, and approved
for publication. Approval does not signify that the contents necessarily reflect
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commercial products constitute endorsement or recommendation for use.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/7-79-090
March 1979
Nonwater Quality Impacts
of Closed-Cycle Cooling Systems
and the Interaction of Stack Gas
and Cooling Tower Plumes
by
G.A. Englesson and M.C. Hu (United Engineers and Constructors, Inc.)
Cameron Engineers, Inc.
1915 South Cjarkson Street
Denver, Colorado 80210
Contract No. 68-01 -4337
Program Element No. EHE624A
EPA Project Officer: Theodore G. Brna
Industrial Environmental Research Laboratory
Office of Energy, Minerals, and Industry
Research Triangle Park, NC 27711
Prepared for
U.S. ENVIRONMENTAL PROTECTION AGENCY
Office of Research and Development
Washington, DC 20460
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ABSTRACT
This report presents the results of a literature survey on the non-water
quality impacts of closed cycle cooling systems and the interaction of
power plant stack gas and cooling tower plumes. The purpose of this report,
prepared for the Environmental Protection Agency (EPA) by United Engineers &
Constructors,Inc. (UE&C), is to document the state-of-the-art concerning the
impact of drift from evaporative cooling towers and the interaction of cool-
ing tower plumes with stack gases from fossil-fueled steam electric genera-
ting stations.
Cooling tower plumes and stack plumes are treated as separate topics, fol-
lowed by a discussion of plume-stack gas interactions. For cooling tower
plumes, plume types, behavior, salt drift generation and deposition, and
inadvertent weather modifications are reviewed. Special emphasis is placed
on meteorological conditions which enhance deposition, icing and fogging,
and cloud formation.
The cooling tower-stack gas interaction discussion emphasizes categories and
mechanisms of interactions, acid precipitation enhancement, case studies of
operating power plants, and practices proposed to reduce or minimize cooling
tower/stack plume interactions.
The adverse biological impacts of acid precipitation, cooling tower drift,
and icing and fogging on the biota are considered. The effects of acid pre-
cipitation on soil, soil biota, vegetation and aquatic biota, including
vegetation, planktonic and benthic organisms, and fish are discussed with
reference to levels causing harm or injury. The nature of cooling tower
drift is examined for areas important to environmental impact assessment.
These include: atmospheric and cooling tower salt loading, cumulative ef-
fects of both, and salt tolerances of plants and animals. Emphasis is placed
on threshold concentrations at which the biota is affected by drift deposi-
tion and the distances from the cooling tower where toxic levels are attained.
ii
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CONTENTS
Abstract i:L
Figures vl
Tables x
Acknowledgments xiv
1. Introduction 1
2. Conclusions and Recommendations 2
Conclusions 2
Recommendations 3
Discussion of Recommendations 4
Salt Drift Deposition 4
Adverse Biological Impacts of Cooling Tower
Salt Drift 4
Acid Formation Enhancement by Cooling Tower/
Stack Gas Interactions 6
3. Cooling Tower Plumes 7
Types of Cooling Towers 7
1 Plume Behavior 8
' References 10
4. Codling Tower Drift - Measurements and Environmental Impact... 12
Introduction 12
Nature of Cooling Tower Drift 12
Salt Drift Measurements 12
Introduction 12
Meteorological Conditions Which Affect Deposition... 13
Saltwater Cooling Tower Drift and Deposition
Measurements 14
B. L. England Station, Unit 3 14
Chalk Point, Unit No. 3 17
Turkey Point 18
Additional Observations on Drift 19
Environmental Effects of Salt Drift 22
Factors Relevant to Environmental Impact
Assessment 22
Naturally Occurring Atmospheric Salt
Loading 22
Cooling Tower Salt Loading 22
Cumulative Salt Load on the Biota 23
Salt Tolerances of the Biota 23
Salt Drift Effects on the Biota 24
Effects of Vegetation 24
iii
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Environmental Factors Affecting Foliar
Injury 24
Acute Vs. Chronic Expression of
Symptoms 25
Plant Differences in Susceptibility 26
Salt Levels that Cause Injury to
Vegetation 26
Salt Deposition Effects on Land Vertebrates,
Freshwater Fish and Other Animals 30
References 32
5. Weather Modification 116
Introduction 116
Fogging-Icing Frequency and Duration 116
Meteorological Conditions Conducive to Fogging and
Icing 118
Adverse Effects of Fogging and Icing 119
Cloud Enhancement 120
Meteorological Conditions Conducive to Cloud
Enhancement 121
Adverse Effects of Cloud Enhancement 121
Precipitation Enhancement Frequency 121
Meteorological Conditions Conducive to Precipitation
Enhancement 122
References 124
6. Stack Plumes 132
Plume Behavior 132
Plume Rise 132
Long Range Transportation 132
Effect of Terrain 133
Stack Gas Composition 133
Introduction 133
Power Plant Emission Rates 135
Sulfur Dioxide and Conversion to Sulfates 135
NOX and Ozone 138
Acid Precipitation 140
References 143
7. Plume Interaction 162
Introduction 162
Categories of Plume Interaction 163
Mechanism of Interaction 163
Acid Precipitation Enhancement 165
Field Studies 167
Keystone Station 167
Chalk Point Station 170
Ratcliffe and Rugeley (Staffordshire, U.K.)
Stations 172
Amos Station 172
Centralia Plant 173
Cayuga and Milliken Stations 173
Minimizing Cooling Tower-Stack Plume Interactions 173
Introduction 173
Separation Distance Between Stack and
iv
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Cooling Towers 174
Use of Tall Stacks 177
References 180
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FIGURES
Number page
3-1 Typical Vertical Profile of Environmental Water Vapor
Mixing Ratio, with the Contribution of the Cooling
Tower Plume Superimposed 11
4-1 Scheme Showing the Possible Relationships Between
Emissions and Direct Depositions on Soils and Plant
Life 38
4-2 Cumulative Mass Distributions of Drift Droplets for
Natural-Draft Cooling Towers 39
4-3 Cumulative Mass Distributions of Drift Droplets for
Mechanical-Draft Cooling Towers 40
4-4 Airborne Sea Salt Collected at Station 4 41
4-5 Air Concentration of Salt Drift as a Function of
Distance from the Sea 42
4-6 Airborne Salt Concentration (ug/rn^) as Affected by
Distance Inland from the Surf 43
4-7 Ambient (Sea Salt) Airborne Salt Concentration as a
Function of Distance from the Shore* 44
4-8 Normalized Airborne Salt Values as a Function of the
Distance Inland (with an Initial Value of One at
Sea Shore) 45
4-9 Natural Drift Deposition Rate as a Function of Distance
from the Sea 46
4-10 Sedimentation Rates of Airborne Salt as Affected by
Distance Inland from the Surf 47
4-11 Average Cl" Concentration, mg/1 in Rainwater, July-
September 1955 48
4-12 Average Cl" Concentration, mg/1 in Rainwater, January-
March 1956 49
vi
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Number
4-13 Exemplary Data for a and dfl in the Near Vicinity
of the Oyster Creek Generating Station at Forked
River, NJ. (Data Published with Permission of
General Public Utilities.) .............................. 50
4-14 Average Sea Salt Concentration and Deposition as a
Function of Distance from the Shore (November 6,
1974 - November 11, 1975) (Unit Operation: Off
During Entire Test Period) .............................. 51
4-15 Average Ambient Ground Level Sea Salt Concentration and
Deposition as a Function of Distance from the Shore
(November 20, 1973 - November 5, 1974) .................. 52
4-16 Average Sea Salt Concentration and Deposition as a Function
of Distance from the Shore (November 6, 1974 - November
11, 1975) (Unit Operation: On During Entire Test
Period) ................................................. 53
4-17 Histogram of Droplets Collected by Film Sampler
(Traverse 15-8, 15-9) ................................... 54
4-18 Drift Droplet Plume, Test Plan No. 2 ...................... 55
4-19 PILLS/SP Consolidated Curve for Cooling Tower Position
27 of Diameter SW-NE 3 ............................ . ..... 56
4-20 Cumulative Drift Distributions of Three Mechanical
Draft Cooling Towers .................................... 57
4-21 APS Station Locations for Monitoring Ambient Air Salt
Loadings and Salt Contributions from Cooling Device
Sources. January 1974 - July 1974. Distances in
Meters .................................................. 58
4-22 Height of Evaporation of Drift Drops ...................... 59
4-23 Layout of Deposit Gauges in Vicinity of Fleetwood Power
Station ................................................. 60
4-24 Chloride Buildup in Bush Bean Leaf Tissue Over 8 Hours
From One Spray Application in Each of Two Humidity
Conditions. High Humidity - 75-80% BH; Low Humidity -
55-70% BH. Control Plants (C) were not Sprayed ......... 61
4-25 Chloride Buildup in Bush Bean Leaf Tissue Over 24 Hours
From One Spray Application in Each of Two Humidity
Conditions. High Humidity - 75-80% RH; Low Humidity -
55-70% BH. Control Plants (C) were not Sprayed ......... 62
vii
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Number Page
4-26 Chloride Accumulation in Bush Bean Foliage Tissue Over
A Period of One Month After One Spraying Per Treatment
at Indicated Intervals with 10, 50 or 100% Sea Water.... 63
4-27 Dogwood Leaf Injury Classes After Simulated Drift
Treatment 64
4-28 Foliar Damage of Red Pine (Pinus Resinosa) 65
4-29 Mean Percentage Foliar Area Injured on the First Three
Sets of Trifoliate Leaves of Three Ages of Bush Bean
(Phaseolus vulearis L.) After 100 Hours Exposure to
Various Sea Salt Aerosol Concentrations 66
4-30 Dogwood Leaf Injury Classes After Simulated Drift
Treatment 67
4-31 Relationship Between Incidence of Foliar Injury in Bush
Bean and Dose of Saline Aerosol 68
4-32 Percentage Reduction of Mean Plant Pod Dry Weight (with
Seeds) of Mature Bush Bean After Exposure to Three
Different Sea Salt Aerosol Concentrations at Three
Stages of Growth (Plant Age at Initiation of
Exposure) 69
4-33 Mean Percent Trifoliate Leaves Injured on Three Ages
of Bush Bean (Phaseolus vulaarts L.) After 100 Hours
Exposure to Different Sea Salt Aerosol Concentrations... 70
4-34 Log Dose-Response Plot for Bush Bean (Phaseolus vulgaris L.)
Trifoliate Leaves Injured Following Exposure to Three
Concentrations of Sea Salt Aerosol for 100 Hours at
Different Stages of Growth. £050 Represents the
Concentration where 507. of all Trifoliate Leaves
Exhibit Injury 71
4-35 Effect of Soil Salinity on Germination of Crop Plants 72
4-36 Salt Tolerance of Vegetable Crops Grown From Late
Seedling Stage to Maturation. Crops are Arranged
in Order of Increasing Salt Tolerance 73
4-37 Salt Tolerance of Ornamentals as Measured by the Decrease
of Top-Growth Weight. The Estimated Soil Salinities at
Which 50% of the Specimens of each Species Died are
Indicated as LD50 74
viii
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Number . Page
4-38 Salt Tolerance of Yield Crops Grown from Late
Seedling Stage to Maturation. Crops are Arranged
in Order of Increasing Salt Tolerance ................... 75
4-39 Salt Tolerance of Forage Crops Grown from Late
Seedling Stage to Maturation. Crops are Arranged
in Order of Increasing Salt Tolerance ................... 76
4-40 Relation Between Soil Salinity and Relative Yield of
Five Crop Plants ........................................ 77
4-41 Relation Between Soil Salinity and Relative Crop Yield
for Tolerant, Moderately Tolerant and Sensitive
Plant [[[ 78
5-1 Incidence of Fog and Seasonal Smoke and S02 ............... 126
5-2 Predicted and Observed Cooling Tower Plume Behavior,
Sept. 7, 1972 ..................................... . ..... 127
7-1 Plume Interactions ........................................ 184
7-2 Comparison of Predicted and Measured Plume Trajectories... 185
7-3 Variation of Acid Drop Concentration with Humidity ........ 186
7-4 Plume Monitoring Patterns ................................. 187
7-5 Particle Concentration for Two Different Flights at
Points Along the Plume Path ............................. 188
7-6 Particle Growth Observed During Merged Plume Case ......... 189
7-7 Particle Concentrations ................................... 190
7-8 Particle Concentrations ................................... 191
7-9 Plume Droplet Residue Size Distributions Sample Numbers
12 and 13 ............................................... 192
7-10 Plume Droplet Residue Size Distribution Sample Number 6... 193
7-11 Plume Droplet Residue Size Distribution Sample Numbers
7 and 8
7-12 Plume Droplet Residue Size Distribution Sample Number 1...195
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TABLES
Number
4-1 Effects of Simulated Rain Acidified with Sulfuric
Acid on Host-Parasite Interactions 79
4-2 Overall Collection Efficiency for Different Types
of Drift Eliminators 81
4-3 Factors Affecting Dispersion and Deposition of Drift
from Natural-Draft and Mechanical-Draft Towers 82
4-4 Atmospheric Variables and Characteristics Affecting
the Dispersion and the Deposition of Drift 83
4-5 Design and Operation Characteristics of Wet Cooling
Systems Affecting the Drift Rates 84
4-6 Summary of Drift Rate and Droplet Size Distribution
Measurement Techniques 85
4-7 Windrose Data for Deposition at Atlantic City 86
4-8 Windrose Data for Deposition at Atlantic City 88
4-9 Observed Deposition at Chalk Point 89
4-10 Comparison of Typical Drift Droplet Measurements 92
4-11 Cooling Tower Composite Drift Mass Emission
Parameters,
93
4-12 Rates of Sodium and Magnesium Mass Emission From
the Turkey Point Cooling Tower. 94
4-13 Representative Drift Emission Data of the Turkey
Point Cooling Tower 95
4-14 Effect of Cooling Tower on Ambient Salt Concentration.... 96
4-15 Vegetation Acutely Affected by Salt Spray 97
4-16 Plants Acutely Affected by Salinity 98
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Number
4-17 Response of Various Ornamental Plants to Seawater
Spray [[[ 99
4-18 Environmental Conditions Producing Visible Salt Injury
to Native Vegetation Near Forked River, N.J ............. 100
4-19 Summary of Sodium and Chloride Seasonal Means and Ranges
for all Species and Sites. Data are Expressed as ug/g
on a Dry-Weight Basis Sampling Period Extended from
May 1974 to April 1975 .................................. 101
4-20 Summary of Sodium and Chloride Concentrations On a Dry-
Weight Basis in Certain Plants ......................... .102
4-21 Extent of Injury to Plants Exposed to Seawater Mist for
Various Lengths of Time ................................. 103
4-22 Effects of Salt-Spray Applications on the Nutrient
Contents and Metabolic Index in Soybean Leaves .......... 104
4-23 Effects of Salt-Spray Applications on the Nutrient
Contents and Metabolic Index in Corn Leaves ............. 105
4-24 Means of Nutrient Contents and Metabolic Index for
Soybeans and Cora from the Chalk Point Cooling Tower
Monitoring Program - 1973 ............................... 106
4-25 Response of Nine Deciduous Woody Species of Plants
to Saline Aerosols ...................................... 107
4-26 Response of Two Coniferous Species to Saline
Aerosols ................................................ 108
4-27 Response of Two Deciduous Woody Species Exposed at
857, Relative Humidity to a Saline Aerosol ............... 109
4_28 Percent of Injured Bush Bean with Relation to
Trifoliate Sodium and Chloride Accumulation in PPM ..... .HO
4-29 Case Studies Comparison of Environmental Drift Effects
for Power Generating Plants .......... . ....... .
4-30 Faunal Salt Tolerances
4-31 Bird Impaction Recorded at Three Mile Island Nuclear
Station Cooling Towers by Month and Tower, July 27,
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Number
5-1 Conditions Before and After Commissioning of the
Power Station 128
5-2 Comparison of Observed and Predicted Plume Lengths 130
5.3 Source and Ambient Data 131
6-1 Fixed Stack Parameters 146
6-2 Trace and Minor Element Stack Emission 147
6-3 Particulate Emission Test Results 148
6-4 AIHL Analyses of Sulfur, Vanadium and Fly Ash Contents
of Fuel Oils Burned During Study 149
6-5a Trace Metals in Fly Ash as a Function of Particle Size....150
6-5b Concentration and Si*e of Trace Metal Particles in
Urban Air 150
6-6 Average Air Pollution Emissions from Various Power
Plants 151
6-7 Typical Composition of Coal Fly Ash .152
6-8 Concentrations and Concentration Ratios for 1973 Runs
on Different Fossil Fuel Components 153
6-9 Specific Concentrations (ug/gm) and Volume Concentrations
of Trace Elements in Coal and Oil Fly Ash 155
6-10 Average F Factors for Various Fossil Fuels 156
6-11 Mechanisms that Convert Sulfur Dioxide to Sulfates 157
6-12 Plants Studied by BNL 158
6-13 Enviroplan Plant Operating Data .159
6-14 Sources of Acidity in Acid Precipitation Collected in
Ithaca, New York, on 11 July 1975 161
7-1 Predicted Maximum Ground-Level Air Concentrations and
Surface Deposition Fluxes of S02 and SO^" During
Worst Case Merging of Lake Erie Generating Station
Stack and Cooling Tower Plumes 198
7-2 Predicted Maximum Ground-Level Air Concentration and
Surface Deposition Fluxes of S02 and SO^ for Non
xii
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Number Page
Merging Cases ........................................... 199
7-3 Predicted Annual Surface Deposition Fluxes of 862
During Plume Merging .................................... 200
7-4 Predicted Annual Surface Deposition Fluxes of S0^~
During Plume Merging .................................... 201
7-5 Particle Frequency (7.) for Flight 4 on Stage 3 of
the Impactor ............................................ 202
7-6 Sources of Acidity in Acid Precipitation in the North-
eastern United States ................................... 203
7-7 Calculated Emission Rates of S02, E^SO^ and NO for Cayuga
and Milliken Stations at 100% Capacity .................. 205
7-8 Comparison of Cooling Tower-Stack Interaction Studies ..... 206
7-9 Summary of Control Alternatives for S02 ................... 208
7-10 Summary Description of Major Flue Gas Desulfurization
Processes ............................................... 209
7-11 Measured Maximum S02 Concentrations (ug/m^) . . ............. 211
7-12 Frequency of Ambient 802 Concentrations Exceeding
Air Quality Standards ................................... 212
7-13 Stack Heights and Associated Generating Capacity of
Power Plants in the Study ............................... 213
7-14 Partial Summary of Power Plant Technical Control
Options - Removal and Energy Efficiency, Costs
and Timing .............................................. 214
xiii
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ACKNOWLEDGMENTS
This project was completed under the direction of T. G. Brna, Project Officer
for the U.S. Environmental Protection Agency (EPA), M. C. Hu, Project Manager
for the United Engineers & Constructors, Inc. (UE&C) and G. A. Englesson,
Technical Director of the Advanced Engineering Department, UE&C, Inc.
Principal contributors were R. K. Guy, J. J. Talbot, U. K. Rath, M. Booth,
D. S. Wiggins, R. E. Munson, C. Murawczyk, M. D. Miller, and F. R. Eure.
Acknowledgments are due to J. Lum for his invaluable consultation during the
course of the study and his critical review of this report.
Acknowledgments are due to A. Policastro, and R. A. Carhart, of Argonne
National Laboratory, S. R. Banna of Air Resources, Atmospheric Turbulence
and Diffusion Laboratory, R. Pena of Pennsylvania State University and W.
Dunn of the University of Illinois for their consultations during the course
of the study.
xiv
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SECTION 1
INTRODUCTION
The objective of this study under contract from the Environmental Protection
Agency was to collect, analyze and correlate available information on: a)
the impact of drift from evaporative cooling towers, especially saltwater
towers, and b) the interaction of cooling tower vapor plumes with stack gases
from fossil-fueled steam-electric generating station.
The results reflect an intense ten man-month effort performed in a three man-
month period (October 1977-January 1978) to complete a thorough state-of-the-
art investigation. Due to the limitation of time and funding,omission of
some of the available data is possible.
The information thus collected and correlated forms a part of an overall
effort sponsored by EPA and is intended to provide background information
for the revision of the water pollution regulations for steam-electric power
plants.
Five tasks were performed to satisfy the requirements of this project. For
each task, several subtasks were carried out to survey and select literature
sources, to review and analyze the data collected, and to tabulate the
relevant information.
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SECTION 2
CONCLUSIONS AND RECOMMENDATIONS
2.1 CONCLUSIONS
1. The limited amount of field data on the quality and impact of
drift from saltwater cooling towers is insufficient to make a
firm, general conclusion on their drift effects.
2. Predictions of drift deposition by various models give wide
variations. A current evaluation by Argonne National Labo-
ratories of 12 different computer models used to predict
drift deposition (including the program used by NRC in the
preparation of Environmental Impact Statements) indicates
that the predicted results may vary from 2 to 10 times
that measured during tests performed at the Chalk Point
Power Station.
3. Cooling tower drift and deposition from natural draft towers
apparently do not increase ambient salt loading to the extent
that a significant impact has been observed. Field data from
the operational Chalk Point and B. L. England Stations indi-
cate that although drift and its deposition from cooling
towers may be significant within the immediate environs of
the station, its impact beyond 1 kilometer (km) may be insep-
arable from the natural salt loading characteristic of those
regions.
4. Insufficient and inconclusive data exist on the degree of salt
injury to the biota caused by cooling tower drift. The only
existing field data obtained from the Chalk Point and Turkey
Point towers indicated that acute drift effects on vegetation
may occur in the immediate environs of the cooling tower,
perhaps up to several hundred meters downwind. Chronic effects
of long-term operation of cooling towers are not known.
5. Enhancement or reduction of acid precipitation or deposition
(a local or regional environmental problem) by wet cooling
tower and stack plume interactions has neither been established
nor demonstrated in the field.
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6. Plume interaction impacts on the biota are not definable at
this time. Interaction between evaporative cooling tower
plumes and stack gases from fossil-fueled steam-electric gen-
erating stations has not been conclusively shown to enhance
or abate acid deposition/precipitation.
7. Based upon field observations, fogging and icing from natural
draft cooling towers are not environmental problems. At most,
only a few millimeters of ice have been observed to accumulate
on surrounding structures. Fogging from natural draft cooling
towers has not been observed under a variety of meteorological
conditions.
For mechanical draft cooling towers, fogging and icing have
been observed. Because of more severe downwash effects and
lower tower heights, the buoyant plume has been observed to
intersect the ground, usually within a few hundred meters.
The tower design significantly affects the probability that
the plume will intersect the ground. Plumes from line me-
chanical draft towers are much more likely to impact the
ground than plumes from round mechanical or fan-assisted
natural draft towers. Rectangular mechanical draft cooling
towers have been observed to cause plume and ground inter-
section about 10 percent of the time. Severe icing has
been observed covering local structures and vegetation with
0.25 in. of ice to a distance of about 250 m.
8. Modification of weather, such as precipitation and cloud
enhancement, by wet cooling towers has been insignificant.
In the few documented cases of weather modification, the
average effects caused by cooling towers have generally been
minimal. Nearly all studies indicate that precipitation
and cloud enhancement for any single sector downwind from a
tower are increased by only a few percent. One study cur-
rently underway at Oak Ridge National Laboratories predicts
that heat rejection from a large cooling tower complex
(3000 MWe) will cause an apparent increase of 15 percent in
the amount of precipitation in the direction of the pre-
vailing wind.
2.2 RECOMMENDATIONS
1. Comprehensive pre- and post-operational studies of cooling
tower drift and deposition using standardized measuring tech-
niques are recommended.
2. Extensive field investigation should be undertaken in the
following areas; a) dose/response relationship of salt
drift, b) cooling tower drift impact on local biota under
the conditions in which flora would normally be exposed,
emphasizing long-term cumulative effects.
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3. Dose-response data from one species should not be applied
to other species for which no experimental toxicity data
exist.
4. Extrapolation of laboratory data to natural situations of
operating cooling towers should be undertaken with caution
until existing saltwater cooling towers are well into the
post-operational stage and a sufficient data base is
available.
5. Both theoretical investigation and field measurements should
be undertaken to determine the quantity and impact of acid
precipitation deposition due to cooling tower/stack gas
interaction.
2.3 DISCUSSION OF RECOMMENDATIONS
2.3.1 Salt Drift Deposition
Comprehensive pre- and post-operational studies of cooling tower drift and
deposition using standardized techniques of measurement are recommended.
For example, analysis of the B. L. England data indicated that the recorded
increase in deposition might not have been caused by the cooling tower but
rather by different prevailing meteorological conditions observed during the
post-operational period. Because only 8 of 52 data sets were considered
adequate, the degree to which micro-meteorological conditions contributed to
an increase in drift deposition is not known. Although the Chalk Point data
indicated that operation of the cooling tower between May 1975 and April 1976
did not change ambient salt concentrations within a 9.6 km radius of the
power station, long-term field studies over a period of several years are
necessary to safely confirm these preliminary conclusions. In addition, in-
land areas where brackish underground or agricultural runoff water may be
used requires particular attention, due to the dearth of information avail-
able on this topic.
2.3.2 Adverse Biological Impacts of Cooling Tower Salt Drift
Because biological impacts of power facilities generate concern and little is
known about threshold concentrations at which vegetation is affected by drift
deposition, this section includes a lengthy discussion of recommendations on
adverse impacts of cooling tower drift. It is generally understood that
operation of a saltwater or brackish water cooling tower will release measur-
able quantities of salt particles into the local atmosphere. The fate of
these particles is not understood in real situations, although some data
suggests that a portion of these particles impinge or settle on vegetation
and other structures at variable distances downwind of the cooling tower.
Local meteorology determines the degree and nature of salt transport.
Environmental reports indicate that operation of the cooling tower may or may
not raise ambient salt levels beyond a limited, measurable distance downwind
of the tower. Major ecological concern focuses on both acute effects of
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higher than background levels and chronic effects of long-term, low-level
salt concentrations on the biota, particularly vegetation; as it has generally
been argued that increased salt loading has negligible, even beneficial ef-
fects on animals.
A substantial body of literature on salt tolerances of plants and animals
exists, including data on the dose-response relationship for selected species.
Most studies indicate that vegetation exhibits variable sensitivity to ambient
salt loading, whereas animals are generally unaffected, provided that enough
drinking water is available. In assessing salt levels that are potentially
harmful to vegetation, particular attention should be paid to biological fac-
tors that determine susceptibility, (including species-specific sensitivity,
stage of development, and phenotype), in addition to aerosol salt concentra-
tion, rate of deposition, foliar accumulation, relative humidity, and size
and degree of hydration of saline particles. All of these factors combine to
produce a complex dose/response relationship, the exact nature of which is
not understood in depth.
More data is needed on the dose/response relationship, particularly with re-
gard to the effects of parameters which describe duration and repetitiveness
of exposure, and the form in which salt is applied under experimental condi-
tions. In addition, knowledge of local meteorological factors which may
alter exposure patterns downwind of a cooling tower is needed to extrapolate
laboratory information on salt sensitivities to real situations in the field.
It is implied that salt impingement on vegetation in laboratory situations
may not be representative of cooling tower salt drift impingement under opera-
tional conditions. This problem needs investigation.
A future concentrated effort should be made to be realistic in the appraisal
of cooling tower effects on local biota by simulating, as best as possible,
conditions under which flora would be exposed. The spectrum of local plant
species that would be tested for salt drift effects should include major
agricultural crops, ornamentals, and other native species. Underlying this
experimental rationale is the fact that in the coastal environments where
saltwater cooling towers would be situated, the vegetation has already been
exposed to variable salt loads for perhaps thousands of years. Studies should
emphasize the long-term cumulative effect of increased ambient salt loading
on growth, reproductive yield in terms of fruit and seed production and
changes in community structure (abundance and diversity). To date, these
studies do not exist. Thus, it becomes impossible to assess the long-term
effects of cooling tower drift on biotic communities. From the experimental
data that exists at present, it may be concluded that a particular species
is deleteriously affected by the aerosol conditions and its rate of deposi-
tion. An extrapolation of the existing experimental dose-response data
(Table 4-17) that provides "armchair" estimates of deposition rates which may
affect selected species is provided. This table provides a spectrum of
susceptibility to salt in terms of sensitive and tolerant species. The
following assumptions are made, regarding the use of this data:
1. Experimental salt drift treatments simulate, as closely as
possible, local ambient conditions of salt impingement on
vegetation.
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2. Field responses of vegetation are similar to laboratory
responses.
3. Total salt deposition, whether from a single exposure or a
series of exposures over a longer period of time, is a
reasonable estimate of hazard to plants.
In addition, dose-response data from one species should not be applied to
other species for which no experimental toxicity data exists, unless some
information is available on the degree of susceptibility of that species to
salt loading. This restriction is intended to reduce the overgeneralization
conmon to impact studies and to emphasize the need for more acute toxicity
data on relevant vegetation. If these conditions are satisfied, then rough
guidelines for permissible drift deposition can be established by comparing
the maximum salt deposition (short-term highs or long-term averages) from an
operating cooling tower with tolerance limits of selected species. For
example, deposition ranges of 1000 to 4200 kg/km2 per month may be represen-
tative of higher-than-average salt loading. Thus, a. conservative (worst
case) estimate of deposition rates causing acute foliar symptoms lies within
this range. But only those species very sensitive to salt would be affected
by these ambient levels.
Extrapolation of laboratory data to natural situations of operating cooling
towers should be undertaken with caution until existing saltwater cooling
towers are well into the post-operational stage, and a sufficient data base
is available.
2.3.3 Acid Formation Enhancement by Pooling Tower/Stack Gas Interactions
The quantity and impact of acid precipitation deposition due to cooling tower/
stack gas interaction have not been determined in the field. It was reported
that at the Keystone Generating Station stack plumes merging with visible
cooling tower plumes caused sulfate generation (a prerequisite to acid genera-
tion) as well as acid generation. This phenomenon (sulfate generation) was
measured in the drift but not in the ground deposition from cooling towers at
Keystone. At Chalk Point the merging plumes resulted in an increase of drift
pH, as acid drift already existed in the stack plume. The observed differ-
ences between these sites is attributed to the fact that at Chalk Point a wet
venturi scrubber supplies enough water for most of the acid production to
occur within the stack plume before any merging with the cooling tower plume
occurs. Since all new coal-fired steam-electric plants will require scrub-
bing, it is possible that acid production during plume merging may be inhib-
ited because of the low S02 levels of the flue gases leaving the stacks.
It is possible to minimize the probability of stack/cooling tower plume
merging with a knowledge of the climatology and the tower and stack designs.
The climatology at a specific site will determine what stack/cooling tower
orientation will limit the duration of plume merging during an annual cycle.
The longest visible cooling tower plumes are produced under high relative
humidities, light winds, stable temperatures, stable lapse rates, and low
ambient temperatures. Evaporation of the cooling tower plume is thereby cur-
tailed, and more water vapor from the plume is condensed. If the stack/cool-
ing tower axis is oriented perpendicular to the wind under these ambient con-
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ditions, the stack and visible cooling tower plume will merge at distances
further downwind, or perhaps not at all. With plume merging further downwind,
dispersion of the stack plume can reduce the concentration level of sulfate,
so that acid production at this juncture could be reduced. After determining
the climatological wind rose at the site for these coincident, critical am-
bient conditions, the stack/cooling tower axis can be oriented perpendicular
to the most frequent wind direction in which these conditions occur, thereby
minimizing the plume merging and acid production. In addition, the stack and
cooling tower can be designed so that under the requisite ambient conditions
the final plume rise for both the stack and cooling tower will not be coinci-
dent.
Although these design guidelines should minimize merging along a vertical
plane, the effectiveness of such a procedure has not been determined. The
procedures to reduce cooling tower/stack plume interactions are suggestions
based on the Gaussian diffusion of the plumes and Briggs1 plume rise formu-
lation, but field validation has not been established.
Acid deposition from precipitation scavenging of stack and cooling tower
plumes has not been measured. At Chalk Point, the simultaneous scavenging
of cooling tower and stack plumes appeared to raise the pH of rainwater ever
that of tower pre-operational data. However, no other studies have been
conducted to measure the acid deposition resulting from simultaneous precip-
itation scavenging of the stack and cooling tower plumes.
6a
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SECTION 3
COOLING TOWER FLUMES
This section is intended to provide'a brief description of cooling towers,
the associated plumes, and the meteorological parameters which affect plume
behavior. In depth discussions of the meteorological effects of vapor plumes
and the ecological effects of salt drift are presented in Sections 4 and 5,
respectively.
3.1 TYPES OF COOLING TOWERS
Conventional cooling towers may be classified as either wet (evaporative)
or dry (non-evaporative). In the evaporative or wet cooling process, direct
mixing of hot water and air results in a rapid cooling effect. This is due
primarily to heat transfer by evaporation (latent heat transfer) and par-
tially to heat transfer directly from the water to the air (sensible heat
transfer). In the non-evaporative or dry process, the exchange of heat occurs
between the air and the hot surface of the tubes containing heated water.
As a consequence, the water experiences cooling by conduction and convection
only.
Two types of wet cooling towers are presently employed in the United States
for condenser cooling water: natural draft (hyperbolic) and mechanical draft
wet cooling towers. Either fresh or saline (sea water or brackish water)
water may be employed in this type of cooling system.
Natural draft cooling towers (NDCT) are designed to utilize the "chimney ef-
fect" produced inside the tower shell. The density differences between the
ambient air entering and the moist air leaving the tower and the effective
tower height provide the driving force for the natural draft. Warm water
enters the tower, and cooled water is collected in the tower basin.
With mechanical draft cooling towers (MDCT), fans are utilized to move the
air through the tower. MDCTs are further classified as induced or forced
draft towers, depending on whether the air is pulled or pushed through the
tower. They are further characterized as counterflow or crossflow, depending
on the relative movement of the air and water. In crossflow towers, the air
travels horizontally across the falling water. In counterflow towers, air
travels vertically through the falling water. Detailed descriptions of cool-
ing tower configurations can be found in a study by Hu and Englesson (1).
Power plants located in coastal areas use waters that contain various concen-
trations of salt, e.g. brackish inland waters, estuarine water or sea water.
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While this permits the conservation of fresh water for other uses, the in-
crease in water salinity reduces the rate of heat transfer.
3.2 FLT3ME BEHAVIOR
The behavior of cooling tower plumes and their characteristics are useful in
assessing both the atmospheric effects of cooling towers and the interaction
of the cooling tower plumes with stack gases. The contents of the plume, the
shape and dimensions of the plume, the evaporation rates of circulating
water, the amount of moisture in the plume, wind speed and atmospheric sta-
bility, plume length and persistence (visible plume length), and the effect
of multiple plumes from more than one cooling tower influence the extent of
interaction.
Cooling towers remove heat from condenser cooling water primarily by evapora-
tion and reject this heat to the air in the form of a hot plume containing
water vapor (2).
Depending on plant operating characteristics and local meteorology, from 1%
to 3% of the circulating water flow is lost through evaporation. Evaporation
is also responsible for the concentration of dissolved and suspended solids
in the circulating water. Water droplets of the same chemical composition
may be entrained in the plume and leave the tower as drift.
Figure 3-1 shows the contribution of the cooling tower plume to the water
vapor mixing ratio of the background environment (3) within the plume. The
atmosphere contains water vapor to a degree which depends on the relative
humidity and the ambient temperature. In some arid or desert areas, the
background water vapor content in the atmosphere is low compared to areas
where natural precipitation is nominal or excessive. Consequently, the ef-
fect of cooling towers will be different in such widely different climatolog-
ical zones. Where the atmosphere can supply adequate amounts of water for
chemical reactions with the flue gases, the effect of the cooling tower water
vapor on these reactions will be insignificant.
The shape of the plume after the plume leaves the tower is important for
modeling. For towers with symmetrical exit ports (natural draft, circular
mechanical draft) the shape of the plume as it exits is independent of wind
direction. For rectangular mechanical draft towers, wind direction plays an
important role in plume shape. A plume leaving a rectangular mechanical
draft tower normal to the tower axis generally has a rectangular shape. As
it moves downwind, it begins to assume a more circular shape, due to atmos-
pheric mixing. A plume leaving the tower parallel to the tower's long axis
will assume a circular shape sooner than a plume leaving the tower normal to
the axis. Consequently, buoyant plumes are categorized as vertical and bent
over. Vertical plumes occur in a motionless and stable atmosphere ("calm"
condition); the bent over plumes (nearly horizontal) occur under "windy" con-
ditions.
Early studies considered the rise of dry, buoyant plumes in a calm environ-
ment and used the Taylor entrainment assumption (4). Later investigations
extended the treatment to moist, buoyant plumes in a calm atmosphere (5).
8
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Other studies have provided extensive analyses of dry, bent over plumes,
including transitions through various turbulence regimes. Recently, these
studies have been expanded to include moist, bent over plumes (6).
Visible plume lengths (short, medium and persistent) depend to a great extent
on the ability of the atmosphere to absorb moisture. In general, plumes are
short in the summer, and become larger as winter advances (7").
The stabilized height of plume rise depends on the height of the capping
inversion. Temperature, wind speed, and relative humidity in the vicinity
of the cooling towers are effective predictors of plume rise and persistence
(8).
Recirculation of and interference between the plumes from clusters of mechan-
ical draft cooling towers have been observed. Increasing stack height and
stack spacing have been shown to reduce recirculation (9).
A summary of cooling tower plume rise is given by Briggs (5). Many observa-
tions of cooling tower plume rise at the 2900-MWe John E. Amos Power Plant,
West Virginia were used in comparing the calculated plume rise (using Briggs'
equation and a cloud growth model proposed by Hanna) with the observed plume
rise. The observed average plume rise of 750 m was higher than the computed
value of 670 m from cloud growth model. Hanna concluded that his plume and
cloud growth model can be satisfactorily used to estimate the plume charac-
teristics and the development of clouds due to cooling tower emissions (10).
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REFERENCES
1. Hu, M. C. and G. A. Englesson, 1977. A Study of Wet/Dry Cooling
Systems for Fossil Power Plants: Water Conservation and Plume
Abatement. UE&C-EPA-771130, November, 1977.
2. Slawson, P. R., J. H. Coleman and J. W. Frey, 1975. Some Observa-
tions on Cooling Tower Plume Behavior at the Paradise Steam Plant.
In; Cooling Tower Environment - 1974. Hanna, S. R. and J. Pell
(eds.) ERM Symp. Ser. CONF-740302, pp. 147-159.
3. Hanna, S. R., 1977. Atmospheric Effects of Energy Generation.
Unpublished manuscript.
4. Morton, B. R., 1957. Buoyant Plume in a Moist Atmosphere. J. Fluid
Mech., 2: 127-144.
5. Briggs, G. A., 1969. Plume Rise. AEC Critical Review Series, TID-
15075, November, 1969.
6. Csanady, G. T., 1971. Bent-Over Vapor Plumes. J. Appl. Meteorol.,
10: 36-42.
7. Barber, F. R., A. Martin, J. G. Shepherd and G. Spurr, 1974. The
Persistence of Plumes from Natural Draught Cooling Towers. Atmos.
Env., 8: 407-418.
8. Brerman, P. T., D. E. Seymour, M. J. Butler, M. L. Kramer, M. E.
Smith and T. T. Frankenbery, 1976. The Observed Rise of Visible
Plumes From Hyperbolic Natural Draft Cooling Towers. Atmos. Env.,
10: 425-431.
9. Kennedy, J. F. and H. Fordyne, 1975. Plume Recirculation and Inter-
ference in Mechanical Draft Cooling Towers. In; Cooling Tower
Environment - 1974, Hanna and Pell (eds.), ERDA Symp. Ser. CORF-740302,
pp. 58-87.
10. Hanna, S. R., 1976. Observed and Predicted Cooling Tower Plume Rise
at the John E. Amos Power Plant, West Virginia. 3rd Symposium on
Air Turbulence Diffusion and Air Quality, October, 1976.
10
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600 _
500 _
400 _
1
o
14
00
I 300.
.0
•a
200_
100,
Background and
Plume
10
Water vapor mixing ratio, g/kg
Figure 3-1 Typical vertical profile of environmental water vapor
mixing ratio, with the contribution of the cooling
tower plume superimposed (3),
11
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SECTION 4
COOLING TOWER DRIFT - MEASUREMENTS AND ENVIR01MENTAL IMPACT
4.1 INTRODUCTION
4.1.1 Nature of Cooling Tower Drift
The operation of a closed cycle cooling tower affects two important compo-
nents of the environment: water quality and the atmosphere. The discharge
of blowdown to a water body, the result of control of dissolved solids,
scale, corrosion and bio-fouling, influences water quality. Losses from the
cooling tower in the form of drift and evaporation emit moisture and warm
air to the atmosphere. This report considers only drift losses from closed
cycle cooling systems. Drift losses have considerable potential for bio-
logical impact because drift droplets contain salts (naturally occurring or
from addition of chemicals to treat condenser water) dissolved in the con-
denser cooling water which may increase ambient salt loading on vegetation,
soil and fauna, resulting in alteration of biotic components of an ecosystem
(Figure 4-1). The effect of salt drift may be further compounded when cool-
ing towers are established along coastal waterways (oceanic or brackish)
which possess a naturally-occurring higher level of dissolved salts (3000-
35000 ppm). A major concern is the impact of salt on adjacent agricultural
areas, or forests, with real or potential commercial value and their associ-
ated faunas. Generally, the adaptability of an ecosystem and the magnitude
of the drift effect will determine the impact.
4.2 SALT DRIFT MEASUREMENTS
4.2.1 Introduction
Many different techniques exist to measure droplet size distribution and
drift rate: sensitive paper, coated slides, impaction sampling, cyclone
separator, laser light scattering, high volume sampling, chemical balance,
and the calorimeter technique. Descriptions of their operation have been
summarized in a Westinghouse study (1). For the purpose of this report, it
should be noted that some instruments measure droplet size better than
others, and other instruments measure mass rates more accurately (Table 4-1).
Some of the instruments are mutually exclusive. The droplet size distribu-
tion from natural draft cooling towers was measured by six groups (Figure
4-2), and the droplet size distribution from mechanical draft cooling towers
was measured by five groups (Figure 4-3).
Under similar atmospheric conditions, the same eliminators in the saltwater
12
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and freshwater towers will yield the same drift rate (1). Differences occur
for different types of eliminators (Table 4-2); freshwater tower eliminators
are usually designed to be less efficient in order to minimize pressure drop
and energy penalties. Deviation between maximum and minimum values
amount to a factor of 25 for natural draft cooling towers and 10 for mechani-
cal draft cooling towers. The most efficient eliminators are sinusoidal-
shaped, and limit drift values to 0.0008% of the circulating water rate.
Where there are large bodies of saltwater, natural processes (other than just
cooling towers) also produce salt deposition. Surf and breaking waves form
bubbles from which saltwater droplets are ejected into the air. Also, salt
water vaporizing at the sea-air interface will disburse salt particles into
the air. Along shore areas and during high wind conditions, the turbulent
surf also adds salt droplets to the air. These facts need to be considered
when reviewing salt air concentration and deposition measurements.
4.2.2 Meteorological Conditions Which Affect Deposition-
Natural drift is transported over land where it is deposited either before or
after water in the droplets is evaporated. Many environmental factors affect
spatial deposition: salt flux, size distribution, wind speed and direction,
relative humidity (RH), precipitation, atmospheric stability, topography and
vegetation (Tables 4-3 and 4-4). If a saltwater cooling system is employed,
other factors, such as salt concentration in the circulating water, tower
exit parameters and eliminator design (Table 4-5) necessitate consideration
in the evaluation of drift deposition.
Environmental factors which influence drift rate include: wind speed and
direction, ambient temperature and relative humidity. Relative humidity is
related to drift droplet evaporation rate. At low RH, droplets evaporate
quickly to a smaller salt particle, and the fall velocity decreases. As a
result, the particles remain airborne longer and impact the ground at a
further distance.
Wind speed influences dispersion in two ways:
1. At high wind speeds, the vapor plume (and drift droplets) can
be drawn down into the turbulent wake behind the tower struc-
ture. This phenomenon is known as aerodynamic downwash and
significantly reduces the effective "release height" of the
droplets. Turbulence in the wake brings the droplets to the
ground quickly and results in high deposition rates close to
the tower.
2. The downwind distance where a droplet impacts the ground is af-
fected by wind speed. Droplets can be carried further during
their fall by high wind speeds than by light winds. Deposition
rate decreases as the square of the distance.
Tower location has a great effect on the atmospheric dispersion of drift.
When a tower is located near the sea or on a bay, for example, the sea breeze
becomes a significant climatic factor, whereby winds, which may predominate
from one or two directions, enhance the average salt deposition in certain
13
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sectors.
Precipitation influences deposition in several ways. For example, rain tends
to wash salt from the air. However, the instruments used to measure deposi-
tion are also washed by heavy rains so that deposition rates cannot be deter-
mined at these times (2). Deposition rates increase during drizzle and light
rain (periods when measurements can be taken) (1). Since the rain acts as a
collector, there is an inverse relationship between the salt concentration
and rainfall.
In comparing cooling tower and natural salt drift, characteristics of the
natural drift must be considered. The natural air concentration of salt is
a function of wind direction (Figure 4-4) and distance inland (Figures 4-5 to
4-9). As the wind speed increases, a greater number of large particles are
carried through the air. The average concentration tends to be a quasi-con-
stant level between 10 km and 20 km (Figure 4-8). Increases in wind speed
and precipitation rate also tend to increase natural deposition. Also, eddy
motions on the lee side of obstacles increase deposition. Values ranging
from 380 to 3500 kg/km2 per month have been reported (1).
The natural salt deposition also decreases with distance inland (Figures 4-9
and 4-10). The chlorine content of rainwater decreases by a factor of 5 to
10 for inland sites (Figure 4-11 and 4-12). Quasi-constant levels begin
several kilometers inland because of the more uniform vertical mixing inland,
so that the removal rate approaches a more uniform value (1). Schrecker
et al.(3) determined that at Forked River the concentration of salt in am-
bTent air and deposition reach an asymptotic level of 1 ug/nP and 68 kg/kin^ -
per month, respectively. Concentration and deposition drop quickly within a
few kilometers from the coast (Figure 4-13 and Table 4-6). Since the mea-
sured deposition is considerably larger than expected for the settling speed
of ambient salt particles, the removal of airborne salt near the ground level
is not sufficiently described by gravitational settling.
4.2.3 Saltwater Cooling Tower Drift and Deposition Measurements
Although data on salt drift from operating cooling towers is scarce, there
are a few cases in which reliable measurements have been taken.
4.2.3.1 B. L. England Station, Unit 3—
Atlantic City Electricfs B. L. England Station is located near Marmora, New
Jersey on Great Egg Harbor Bay. Bay water is high in TSS with an average of
50 ppm, while the TDS concentration is an average 30,000 ppm. The baseload
station has two coal-fired boilers (Units 1 & 2) and one oil-fired boiler
(Unit 33 with a total plant nameplate generating capcity of 475.6 MW. Great
Egg Harbor Bay water is used at the maximum rate of 200,000 GPM for condenser
cooling. Units 1 and 2 are cooled on a once-through basis, while Unit 3 is
cooled by a Research-Cottrell Natural Draft hyperbolic, counterflow saltwater
cooling tower.
This is the first natural draft saltwater cooling tower of its kind in the
United States. It is a small tower in comparison to existing hyperbolic
towers, some of which are more than double its size. According to its manu-
14
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facturer, the tower was essentially an experiment to define the state-of-the-
art of saltwater cooling.
The salinity of the make up water ranges from ten (10) to twenty (20) parts
per thousand with an average of sixteen (16) parts per thousand. This is
concentrated by a factor of 1.5 to 2.0 in the recirculated water.
The tower emission drift parameters for the natural draft counterflow salt-
water cooling tower at the B. L. England Station was field measured by
Research-Cottrell Inc. (4). The station is located on Beesley's Point about
4.5 km from the Atlantic Ocean. Fifteen measurements were used to estimate
the overall tower drift emission performance. The mean for the drift rate
was 0.000424% of the circulating water flow with a standard deviation of
0.000123% (99% confidence level of 0.000507%). Given this background infor-
mation, a discussion of salt drift-deposition at the B. L. England Station
follows.
Two studies were performed: one measured drift-deposition during the pre-
operational year and the other measured drift-deposition during one post-
operational year. The instrumentation and measurement techniques utilized
are described in a study by K. Wilber (5). The salient points were that both
salt air concentration and salt deposition were measured near ground level.
In addition, the relative humidity, dry bulb temperature, and wind speed and
direction were measured at each measuring station at the beginning and at the
end of the measurement period.
Unusual phenomena, such as precipitation intensity and dust which occurred
during the measuring period, were noted. The measuring period for salt air
concentration was on the order of several hours, whereas the measuring period
for deposition was about one day. This last point becomes important because
over the time span of one day, the meteorological conditions vary consider-
ably. There were only a limited number of deposition measurements in which
the wind direction came from the same quadrant at beginning and end for all
measuring stations (about 20) during tower operation. Therefore, the average
deposition during tower operation is much more meaningful than that for any
individual case. For any single wind direction sector, the average deposi-
tion value was baaed only upon a few cases in most instances and only In one
sector do the measurements exceed 10 at any one station (Tables 4-7, 4-8).
It should be noted that these wind sectors were determined by averaging
beginning and ending wind directions rather than averaging interim wind di-
rections. The salt air concentration measurements lend themselves to more
reliable correlation with meteorological conditions since the measurement
time period is much shorter.
Certain results can be ascertained from the raw data and the averaged data
presented in the pertinent reports (2,5). For the pre-operational period,
it was not unusual to observe for individual measurements anomalies in either
salt air concentration or deposition. In Run No. 29, for example, the salt
deposition rate was almost 500 kg/km^-mo above background rates at Station
No. 3, while at Station 4 it was about 3 ug/m3 above background. A few miles
inland, such as at Station 3, the deposition values reached a few hundred
15
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kg/km2-mo while at the ocean front, a few thousand kg/km2-mo was not an
unusual reading. The same pattern held for salt concentration. Inland,
concentration dropped from tens to a few ug/m^. At the ocean front, readings
between 50 and 90 ug/m^ were common while values over 100 ug/m^ occurred on
occasion. These tendencies were reflected in the averaged values shown in
Figure 4-14.
Wilber (5) noted other characteristics of the pre-operational data. The
ambient sea salt concentration and deposition values measured at this site
were generally consistent with those measured at Forked River, N.J. (3).
The onshore wind components (ENE to SSW) at Beesley's Point were character-
ized by considerably higher sea salt concentration and deposition values
than those from other directions. Both the average concentration and depo-
sition levels decreased sharply from coast inland regardless of meteorologi-
cal conditions.
During post-operational measurements, higher salt levels were observed up to
about 5 km inland. During pre-operational stages, ambient levels decrease
at distances of 2 km from the drift source (Figure 4-15). The change in
average salt air concentrations was not as gradual as that for deposition.
A marginally significant increase occurred between 0.5 and 4 km, but the
shape of the averaged curve did not differ as in the case of deposition. A
statement regarding the source of drift droplets at B. L. England Station is
relevant. Observations of the tower during high wind conditions revealed
that the major source of the drift appeared to be "blow-through" as opposed
to drift exiting from the top of the tower. Blow-through occurred when
strong winds swept through the tower basin and carried out large droplets of
the circulating water. Measurements near the tower (within 1000 ft.) indi-
cated that the high wind periods coincided with high salt concentrations.
In early 1975, this problem occurred frequently, and high salt concentrations
were recorded at Station 9 which was located adjacent to the switchyard. As
a result, the 1975 data reflect the blow-through problem, which was solved
later by installing larger wind screens in the tower basin.
Instances of significant individual contributions from the cooling tower were
apparent. For example, in Run No. 117 an increase of about 27 ug/m^ occurred
at Station 9 with a wind speed of about 21 mph. This was the highest ob-
served increase and a second maximum occurred during Run No. 123 under simi-
lar conditions. In the later case, the increase was about 8 ug/m-*. The
changes from background values were considerable since the background was
about 1 ug/m^ in these cited cases. Since instances involving about 500
kg/km2-mo were observed during the pre-operational phase, those occasions
during the post-operational phase will be excluded in these comments. How-
ever, increases of 1000 to 4200 kg/km2-mo over background were measured at
inland stations as far as Station No. 3 (3 km inland). At Station 4 (5 km
inland), measurements of more than 1000 kg/km2-mo were observed. The total
deposition, i.e. the background plus cooling tower increment, was quite large
on occasion - about 10,000 kg/km2-mo. This was observed only once at an in-
land station (Run No. 137). Total deposition reached 4242 kg/km2-mo at Sta-
tion 3 during Run No. 152. Usually, significant deposition varied between
1000 and 2000 kg/km2-mo at locations up to 5 km inland. As far as 24 km in-
land, total deposition reaching several hundred kg/km2-mo (Run No. 102) was
16
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occasionally measured, whereas this quantity was not observed (except for one
questionable case) during pre-operational runs.
Measurements show that meteorological conditions affected deposition. For
example, during light rain or drizzle, high relative humidity and winds
coming from the ocean, the deposition increases (Runs No. 102 and 137). Al-
though no analysis on the correlation with meteorological conditions was men-
tioned (2), such a relationship does seem to exist. Future studies should
examine meteorological factors which influence salt deposition, enumerating
more precise cause-effect relationships.
The comparison of pre-operational and post-operational salt levels showed that
the long term average air concentration and deposition levels varied with
local meteorological conditions and distance from shore. The phenomenon of
blow-through undoubtedly increased recorded salt concentrations at Stations
4 and 9, which were located within 1000 ft. of the tower. The correction of
this problem eliminated a major source of drift, so that average salt levels
in the vicinity of the tower at present should be much lower than values in-
dicated in Figure 4-16 (post-operational salt levels).
There are several anomalies associated with the annual averages portrayed in
Figures 4-14, 4-15 and 4-16.
1. During the period November 6, 1974-November 11, 1975 at the
ocean shore line the average concentration and deposition
was 200 to 300% higher when the unit was operating than when
it was not operating.
2. Salt concentration measured inland in 1973-1974, the pre-
operational year, was approximately 4 to 5 times that measured
during the operational year.
3. Concentration is apparently unaffected by the tower while
deposition appears to be significantly affected.
All of these anomalies make it difficult to draw meaningful conclusions con-
cerning the contribution of cooling tower drift to the ambient salt levels.
4.2.3.2 Chalk Point, Unit No. 3—
The Potomac Electric Power Company's (PEPCO) Chalk Point station is located
at the confluence of the Patuxent River and Swanson Creek in the southeastern
corner of Prince Georges County, Maryland, approximately 40 miles southeast
of Washington, D.C. There are four units at Chalk Point, of which three are
presently on line. The three units have a nameplate generating capacity of
1,329 MW. Units 1 and 2 are coal fired, base load boilers, utilizing 7.5 x
10° GPD of Patuxent River water for once-through cooling. Unit 3 is an oil
fired, peaking boiler, utilizing 1.9 x 107 GPD of the once-through discharge
water for recirculating cooling of this 600-MWe unit:.
Annual average salt concentration in the Patuxent River at Chalk Point is
about 7000 ppm. On a monthly basis, values range from 1000 ppm to 13,000
ppm.
17
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The Chalk Point Cooling Tower Project (CPCTP) is the most comprehensive study
of cooling tower drift and the associated environmental effects to date. In
addition to numerous measurements of tower operating characteristics, the
environment surrounding the Chalk Point Station is being closely monitored
for any adverse effects attributable to the natural draft cooling tower, in
this section, the drift measurements which have been conducted will be dis-
cussed.
Argonne National Lab has identified several field measurements as valid for
use in evaluating numerical salt deposition models (6,7). The deposition
measurements at Chalk Point are expressed in terms of number of droplets/m^-
hr, and are given in Table 4-9.
In another study (8), the drift measured by aircraft traverses through and
around the plume was obtained. The collection efficiency for the Chemical
Film Sampler used for these measurements drops quickly for droplets below
20 microns. The complete droplet distribution data summary is given in the
Chalk Point Cooling Tower Project Summary (8). Figure 4-17 illustrates the
distribution of two traverses obtained from flight paths such as in Figure
4-18. The mean mass diameter (MMD) is also shown in Table 4-10 for one test
run.
A few comments are appropriate for the Chalk Point deposition data selected
for further study by Argonne National Laboratories (6,7). ESC obtained de-
position measurements in June of 1976, while ambient measurements of the
winds, dewpoint, and dry bulb temperature were collected by the Applied Phys-
ics Laboratory (APL) of John Hopkins University with a 92-meter instrumented
tower and radiosondes. Tower emission droplet size was measured directly
by ESC, but the Israel-Overcamp-Pringle (IOP) data (unpublished) were in-
ferred. The ESC cases tended to be for slightly stable atmospheric condi-
tions while the IOP cases occurred during slightly unstable conditions.
Hence, ESC deposition rates were about 5 to 10 times higher than the IOP
rates for corresponding distances. Measured droplets of 1500 to 2500 um
could reflect contamination such as rain, spray on coal piles, dew from
trees, emissions from the #3 stack using a scrubber, or blowout. The ESC
samplers were closer to the tower (200 to 1000 m) than the IOP samplers (200
to 3000 m). Droplets less than 100 um were not necessarily recorded although
they were observed; this omission could significantly affect the total drop-
let deposition rates recorded. The IOP data were collected from May through
July of 1975. The ambient meteorological data were measured from a microwave
tower located about 1 km north of the tower, including RH, wind speed and
direction and temperature (6,7).
4.2.3.3 Turkey Point--
Florida Power and Light Company's (FP&L) Turkey Point Station is located
about 30 miles south of Miami at the shore of Biscayne Bay. It consists of
two 430-MWe oil-fueled units completed in 1967 and 1968, and two 730 MWe
nuclear units which began operation in 1972 and 1973. Condenser cooling of
all four units is now provided by a closed-loop saltwater cooling canal sys-
tem. The salinity of the circulating water ranges typically from 30,000 to
41,000 gpm.
18
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Data for saltwater mechanical draft cooling towers are as scarce as those for
saltwater natural draft cooling towers. In each case, salt drift information
for only one or two towers have been measured. The only instrumented measure-
ment of drift emission on a. mechanical draft cooling tower was at Turkey Point
in Florida (9). The tower drift fraction was measured to be 0.00027% with a
drift flux of 7736 ug/n»2-sec, drift mass emission rate of 3.42 gm/s, and a
mass median drop diameter of 120 urn (Table 4-11). Data on magnesium and sodi-
um components to drift emission are given in Tables 4-12 and 4-13. The mea-
surements were taken under different load and meteorological conditions. Fig-
ure 4-19 provides a summary of the available drift emission data for the one-cell
Turkey Point mechanical draft cooling tower. It is significant that this
tower was designed to reduce the drift emission as compared with previous
towers. The newness and the improved eliminator design combined to assure
the the drift emission did not exceed that for the other operating mechanical
draft cooling towers (Figure 4-20).
In another study by Hunter (10) to determine the contribution to salt concen-
trations by drift from the mechanical draft cooling tower, the increase in
the ambient salt concentration due to the tower was less than the measurement
accuracy of approximately 3 to 5 ug/m3. The APS (Airborne Particle Sampler)
stations are shown in Figure 4-21. The effect of the cooling tower on ambient
salt concentration was obtained by using algorithms to estimate the background
salt concentration which would have occurred during each of the cooling tower
tests. This calculated background concentration was subtracted from the
measured concentration to determine the salt deposition attributed to the
cooling tower. When the difference was averaged over the entire 398 measure-
ments during cooling tower operation, the average increase of ambient salt
concentration over the expected background concentration was 0.002 ug/m3 with
a standard deviation of 4.8 ug/m3. This analysis is summarized in Table 4-14.
This clearly indicates that there was no statistically significant increase
in ambient salt concentration during tower operation.
4.2.3.4 Additional Observations on Drift—
A series of qualitative descriptions regarding deposition from saltwater cool-
ing towers was outlined in a Westinghouse report (1). These descriptions in-
clude reports of impacts surrounding the saltwater cooling towers:
1. A three-cell mechanical draft cooling tower in Trinidad
(W. R. Grace Co.), which circulates 20,000 gpm of water a
little less saline than ocean water, has had a noticable
impact on surroundings. Some onsite carbon steel structures
have suffered a fair amount of corrosion. Also, a sugarcane
field located within plant boundaries is not as healthy as
others in the area. However, it is not known whether this
is caused by cooling tower drift or insufficient care.
2. A power plant in Bari, Italy uses a 12-cell tower having 132,000
gpm flow, 18,000 ppm saltwater concentration, and a measured
drift rate of 0.0087.. With this original drift rate, some
olive trees were damaged and occasional arcing of nearby power
lines was observed. A modification to the eliminators reduced
drift rate to 0.00017,,. Since then, no damage to olive trees
or problems with the power lines have occurred.
19
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Two natural draft cooling towers are located at Stella North
Power Station, Lemington, England. The towers are 76 m high,
56 m at the base, serve a total of 240 MW, and have a circulating
water flow rate of 52,000 gpm with 1000 ppm salt concentration.
No environmental problems were experienced within the station's
boundaries or beyond. However, natural growth of vegetation
in the region was scarce.
Based upon more than 200 measurements in England conducted by
the Central Electricity Generating Board on natural draft
cooling towers:
a. Overall droplet diameters range from 60 to 600
microns (um).
b. At a distance of 400 m, the average drop is 240 um
with a range between 100 and 400 um.
c. At 100 m, the average drop size is 400 um with a
range from 200 to 600 um.
d. At 1000 m, the average drop size is 100 um with a
range from 60 to 200 um.
e. The minimum detection limit of drop diameter was
25 um.
Most results were obtained at 90 percent relative humidity
at the Ratcliffe Station (1). Although these numbers very
likely do not reflect downwind droplet sizes from saltwater
cooling towers because of the "solute effect" which decreases
the evaporation (Figure 4-22), they do provide an idea of
droplet size.
At Fleetwood Station, England, two natural draft cooling
towers which are 76 m high and 56 m at base, serve a total
of 96 MW and have a flow rate of 3700 gpm and 4000 ppm
saltwater concentration (Figure 4-23).
The station at Fleetwood is built on land reclaimed from
salt marshes. Pulverized fuel ash has been used to reclaim
more land which is now used for agricultural purposes. This
and the health of the grass, shrubs and trees used for land-
scaping on the station site, all indicate an absence of envir-
onmental impact. It is worth emphasizing that the area has a
typical coastal atmosphere with a natural salt burden and that
the average annual rainfall is some 0.84 m. The latter is
seldom less than 20 mm in any one month.
A botanical survey of the station site listed 110 species of
flowering plants, all typical local species to be expected in
such an area. In the vicinity of the cooling towers the soil
used in reclamation contains clay mixed with rubble and stony
debris. This is largely covered with grass, clover and plantains.
The only part of the site on which vegetation appears to have
been affected by the use of seawater in the towers is a compara-
tively small area around their ponds. This area is subjected
20
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to the blow-out of seawater by wind and is more extensive to
the east of the towers, where spray is blown by the prevailing
westerly winds. This area is being colonized by a few typical
salt-marsh species - Glasswort (Salicornia), Sea Spurrey
(Spergularia sp.) and Common Scurvy-grass (Cochlearia Officinalis)
These two saltwater towers have been operated satisfactorily
since 1955 (12). The environmental consequence of salt drift
deposition from the cooling tower was field investigated (13).
The field data were analyzed and the conclusions of a year's
survey, as reported in (14), are:
a. The analysis of salt precipitation at sites situated around
the station at distances between 400 m and 3660 m has re-
vealed no significant difference between the salt deposition
rates when winds blow from the power station or from the sea.
b. Blow-out from the base of the towers occurs even at rela-
tively low wind speeds and gives significant deposits of
salt at distances of up to at least 100 m from the towers.
c. A measurement of the quantity of salt carried upwards by
the rising stream of air within a cooling tower gave a re-
sult (18 kg hr~l at a tower loading of 30 MW) consistent
with a calculated figure based on the design performance
of the eliminators.
In summary, no problems exist with respect to the performance
of cooling towers using salt water or brackish water. If the
towers are within 5-10 km of the coast,it can be assumed that
the on-shore drift of salt in the atmosphere will be predominant
over any chlorides in carry-over from towers. On-shore drift
diminishes rapidly at a distance of up to 10 km, after which
the atmospheric salt burden remains fairly constant. So that
if sea-water is used in towers more than 10 km inland, con-
sideration may need to be given locally to the possible effects
of carry-over, since the maximum deposition rate from a natural
draft tower can occur up to 3 km away. However, in many areas
in Northern Europe, the rainfall is likely to be sufficient to
reduce any harmful accumulation of chloride in soil or on vege-
tation.
One mechanical draft cooling tower at the Exxon Chemical Co.,
Linden, N.J. has 4 cells, a flow rate of 22,000 gpm and saltwater
concentration of 10 to 12 thousand ppm. Corrosion from drift
is noticable from 150 to 200 m downwind of the tower. Pavement
replaced the natural landscape and vegetation in the immediate
vicinity of the towers so no conclusions concerning effects on
plant life can be drawn.
Two mechanical draft cooling towers located at Chevron Oil Co.,
Perth Amboy, N.J. have 5 cells each. Flow rate for each tower
is 12,000 gpm and salinity is 10 to 15 thousand ppm. The ef-
fects of drift were observed out to 150 m so that a routine
cleaning program for nearby structures was used to reduce cor-
21
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rosion. A tree grove 300 m west of the towers looked healthy.
Even though these descriptions are not quantitative, the design and impact
descriptions do provide an estimation of the overall environmental effects.
However, without knowing the quantitative contribution of cooling tower drift
to natural salt levels, extrapolation of environmental effects to new sites
becomes tenuous. It does seem reasonable to conclude from these case studies
that any problems with excessive drift can be corrected with proper elimina-
tor design.
4.3 ENVIRONMENTAL EFFECTS OF SALT DRIFT
4.3.1 Factors Relevant to Environmental Impact Assessment
The assessment of the potential impact of cooling tower drift on the biotic
components of the environment should include:
1. A comparison of natural atmospheric salt loading to the tower
salt contribution to the atmosphere;
2. An objective determination that the cumulative salt load
(natural plus induced levels) will/will not harm the flora/
fauna of a region;
3. A comparison of pre- and post-operational salt levels in
vegetation;
4. A determination of the salt tolerances or toxicity of plants
and animals found in the area influenced by the tower (14,15,
16,17).
4.3.1.1 Naturally Occurring Atmospheric Salt Loading—
Ambient salt levels are expressed as sea salt, or near-ground level sea salt
concentration in ug/m3, and as deposition, or near-ground level deposition,
flux in kg/km^-mo (Ib/acre-mo). Techniques for the measurement of these fac-
tors have been extensively reviewed (1,10,14,18). Both air salt concentra-
tion and deposition decrease with increasing distance from the sea or saline
water body, approaching nearly a constant minimum several kilometers inland
(Table 4-6, Figure 4-7). Natural salt drift deposition varies from one
locality to another due to geography and local meteorology as well as dis-
tance from shore. Values ranging from 280 kg/km2-mo (2.6 Ib/acre-mo) have
been reported (1,19).
4.3.1.2 Cooling Tower Salt Loading--
Cooling tower salt contribution to the atmosphere has been reviewed (1,10,15,
18). Generally, little data is available on natural versus induced changes
in ambient levels with some exceptions. The Austin-Houghton predictive model
(15) indicated that the cooling tower system at the proposed Forked River Nu-
clear Generating Station in New Jersey (General Public Utilities Service
Corp.) would add less than 10% to the naturally occurring ambient salt levels.
A study by Hunter (10) analyzing the demonstration of salt water mechanical
cooling devices at the Turkey Point Power Plant (Florida Power and Light) re-
ported that the operation of the cooling tower did not increase the back-
ground salt concentration significantly at any of the sampled stations (Table
4-14). Post-operational data from the Chalk Point Study suggested that the
22
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cooling tower operations between May 1975 and April 1976 did not significant-
ly alter the ambient levels of atmospheric salt in an area within a 9.6 km
radius of the power plant (20). However, a comprehensive analysis of pre-
and post-operational background salt concentrations of a major power plant's
cooling towers is needed to eliminate discrepancies in ambient salt measure-
ment techniques, location of sampling stations, and variable meteorological
conditions which occurred in existing measurements.
4.3.1.3 Cumulative Salt Load on the Biota—
A series of comprehensive studies conducted at the Chalk Point Power Plant
(PEPCO), Maryland is the most complete record to date on the cumulative
short-term salt load on the biota (16,20,21,22,23). For example, baseline
studies with post-operational data on ion load (external and internal foliar
sodium and chloride), which is a measure of the concentration of Na+ and Cl"
available to a leaf under natural field conditions, indicated that no statis-
tically significant differences in ion load were observed for four species of
trees common to the Chalk Point Region. Damage to vegetation will be dis-
cussed in a later section.
Scientists at the Boyce Thompson Institute are studying similar problems at
the proposed Indian Point, N.Y., Station (24). However, the units which use
cooling towers are only in the pre-operational stages so that no meaningful
comparison on cumulative salt loading can. be made at this time. Although
other pre-operational studies exist (15,25,26), post-operational studies
should be conducted in order to determine cumulative salt loading on the
biota over time.
4.3.1.4 Salt Tolerances of the Biota—
The general mechanism of salt uptake by plants and animals is relatively
simple, yet distinctly different in plants and animals. Salt droplets are
generated by natural surf action, cooling tower drift or, in rare cases,
auto traffic over salted roads in winter and are carried by the wind and
impinged on vegetation where they are absorbed by the foliage (leaves) (2,5).
These droplets can pass through leaf stems in particle form or in solution
or diffuse through the cuticle into the interior cell layers of the leaf
(27). Salt solution uptake is rapid and efficient (28). Size or degree of
hydration of saline particles determines their potential for damage to
foliage (24). In other cases, salt ions may pass from the soil into the root
tissue. Hindawi e£ al. (27) reviewed the subject of salt penetration into
plants.
For a toxic reaction to occur in animals, the primary route of entry is by
ingestion of sodium chloride, or related salts.
For both plants and animals a substantial body of literature exists on salt
tolerances (24,26). This information is useful in analyzing detrimental
effects of salt loading due to operation of cooling towers through salt
loading on the biota when precise dose-response relationships are defined.
Some problems are evident with existing salt tolerance data as it applies to
cooling tower drift:
23
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1. "The direct effect of airborne salt cannot be separated from
the effect of salt in the soil-solution when salt is present
in irrigation water or the roadside environment;
2. The effects of airborne salt are confounded with the effects
of certain environmental conditions, such as wind, humidity,
or temperature at the seashore; or water stress and vehicular
emissions at the roadside;
3. .'The characteristics of the aerosol, such as concentration dose-
rate, particle size distribution, or chemical composition, to
which plants have been exposed may not be known nor be similar
to what is predicted to occur in the vicinity of a cooling
tower;
4. The plants upon which the experimental information is based
may be unrepresentative of those at the site of the cooling
tower owing to the choice of crops, natural abundance, or
natural selection for tolerance to environmental salt." (24)
In general, biological factors which determine plant susceptibility to salt
may include stage of development, species, phenotype, and physiological con-
ditions during time of exposure, salt deposition and accumulation rate and
precipitation (24,27,28,29,30).
4.3.2 Salt Drift Effects on the Biota
4.3.2.1 Effects on Vegetation—
4.3.2.1.1 Environmental Factors Affecting Foliar Injury—Foliar injury
is related to salt deposition by impaction and the exposure period of salt on
the vegetation (1). The degree of deposition is determined by near-ground
air concentration of salt drift source (cooling tower or saline body of
water). The amount of fine salt that remains on vegetation is influenced by
local meteorology, particularly frequency and amount of precipitation as well
as relative humidity (RH). McCune et al. (24) found that the environmental
conditions most conducive to faliar injury were 85% RH and the absence of
precipitation during and after exposure to experimental saline mists. Swain
(31) demonstrated that in low humidity conditions (less than 707. RH) salt
absorption occurred immediately after a single spraying, suggesting that salt
spray Is absorbed while in solution. Sea water mist formed crystals on the
leaves when allowed to dry after application. However, salt absorption was
initially higher although much slower under "high-burn conditions", that is,
75-80% RH (Figures 4-24, 4-25 and 4-26).
Using glass slide collectors at the proposed Turkey Point Station, Hlndawi
e_t al. (27) recorded different deposition rates on the windward and leeward
side of seashore plants. Leaves on the windward side of native vegetation
showed impaction rates of 4 mg/m2-hr. Thus, impaction rather than sedimenta-
tion accounts for deposition on vegetation in shoreline areas. The excessive
accumulation of Na+ and Cl" ions in plant tissue on the side of foliage
facing the surf or salt drift source resulting in stunted growth on the wind-
ward side is referred to as "molding" (32). Factors which increase the rate
of impaction, such as wind speed and salt concentration, increase the sever-
ity and incidence of injury to plants (27).
24
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Distance from the salt drift source may affect the degree of salt deposition
on vegetation. A comparison of four predictive models of ground-level salt
deposition from a natural draft tower indicates that maximum deposition .(as-
suming extreme weather conditions) may occur 1-3 km downwind (1). However,
if airborne salt levels exceed 100 ug/ra3 for several hours, acute foliar
injury to deciduous vegetation would not be expected to occur in the area
receiving the highest aerosol concentration at 1.6 km downwind of the cool-
ing tower (33).
The severity, distribution and course of development of saline-induced injury
is determined by the dose to which the plant is exposed (24). The validity
of predicting adverse effects solely from data on total salt deposition on
plants is questionable because of insufficient knowledge of effects of pre-
cipitation and dew formation on the overall pattern of saline aerosols and
their availability to plants (24).
4.3.2.1.2 Acute vs. Chronic Expression of Symptoms—Symptoms of foliar
injury can be broadly lumped into acute and chronic effects. According to
Sprague (34) "acute" involves a stimulus severe enough to cause a rapid
response, usually on the order of several hours to days, while "chronic"
refers to a stimulus which continues for a long time. Acute toxicity is
usually lethal, whereas chronic toxicity may be lethal or potentially lethal.
With reference to salt drift, acute plant responses are probably due to high
levels of salt concentration, while chronic symptoms occur in response to
low levels over a long period of time. In general, more experimental data
exists for acute salt toxicity than for chronic toxicity effects on the
biota.
Typical acute toxicity symptoms include marginal foliar necrosis (burn),
lesions, shoot-tip dieback, leaf curl, intervenial necrosis and "molding"
(1,14,24). Under natural conditions, acute injury is associated with
occasional periods of high on-shore winds over a 24-to 28-hour period (14)
causing substantial increases in ambient salt levels (Figure 4-6). These
"dry salt storms" have a noticeable effect on vegetation. Since local plant
species are adapted to those occasional high-concentration short-term salt
exposures, perhaps only these high values would be valid for comparisons with
cooling tower contribution, at least in short-term environmental assessments
(15). Foliar scorch and shoot-tip dieback occurred within three days of a
"dry salt storm" which increased the ambient salt level 300% over a two-day
period (14). Foliar damage, however, was concentrated on the surf-side of
the coastal vegetation less than 375 m from the surf.
Under experimental conditions testing simulated drift injury, acute symptoms
consisted of leaf curling and wrinkling and occasional marginal necrosis with
a visible boundary between necrosis and living tissue without chlorosis (21).
Leaf injury in dogwood trees after spraying with salt mist was expressed as
the percentage of affected leaves divided among four categories of leaf ne-
crosis: 0-25%, 25-50%, 50-75% and 75-100% (Figure 4-27). Symptoms of acute
salt toxicity in white pine consisted of needle-tip dieback on the side of
the plant facing the drift generator, whereas no symptoms of toxicity were
observed on the opposite side (14). In the evaluation of dose-response of
bush beans to salt mist:, McCune et al. (24) classified response as positive
25
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if any Induced lesion was visible and negative if not. In addition, percent-
age of foliar surface affected was viewed as a secondary estimation of foliar
damage. In acute salt toxicity studies, it is important to correlate foliar
damage to the degree of exposure, separating out non-saline induced injuries
(25).
Determination of a cause-effect relation in acute toxicity symptoms of vege-
tation may be confounded by local environmental phenomena. For example, leaf
scorch in hardwoods and needle burn in conifers were not distinguishable from
symptoms of drought injury (35). Sodium and chloride may interfere with
normal stomatal closure, causing excessive water loss which results in leaf
necrosis similar to that caused by drought (36).
Chronic effects on vegetation are less obvious but may include a chlorotic
condition in the interveinal regions, lighter coloration of leaves, slower
growth or changes in plant community structure and diversity (1,29). There
exists a relation between yield of citrus trees and measured airborne salt
concentration near the Mediterranean coast. Lomas and Gat (37) demonstrated
that levels of natural salt drift decrease with increasing distance from
shore and that reduced citrus yield was associated with higher loading near
the coast. Chloride injury to tobacco is not always observable either in
foliar tissue or in decreased yield but may affect the slow rate of burn, the
even-burning properties, and the qualities of the leaf (38). Plant age and
degree of exposure to salt aerosol affected bush bean yield (expressed as
mean plant pod dry weight) under experimental conditions (27). Whereas
three- and five-week old plant pod yield did not show noticable reductions
with experimental treatment of salt aerosol, one-week old plant pod yield
was reduced markedly by treatment concentrations of 25 and 75 ug/nH, respec-
tively (Figure 4-27). In simulated drift studies, cooling tower basin water
caused foliar injury at high doses, hence it was recommended that future
drift studies apply lower doses to determine chronic effects on sensitive
species (23).
In general, the chronic effects of long-term exposure to low levels of am-
bient salt drift (naturally occurring or cooling tower induced) are not
known (14).
4.3.2.1.3 Plant Differences in Susceptibility—Plant species charac-
teristically demonstrate a full range of tolerance to salt loading along a
spectrum from very sensitive to tolerant (14,19,24). Tolerances of selected
species are included in Tables 4-15, 4-16 and 4-17. Lettuce, stone fruits
and tobacco are some of the agricultural crops which may show a decreased
yield because of saline toxicity (38). Under experimental seawater spray
treatments, ornamental vegetation such as flowering dogwood, golden rain
tree, red maple, trumpet creeper, Virginia creeper and wild black cherry, may
be adversely affected by high salt-aerosol concentration (38). Because long-
term field studies of cooling tower drift on vegetation are lacking, future
experimental studies on salt drift toxicity should include tests on a range
of tolerant to sensitive species found naturally or formed in the environs
of the cooling tower (14,24).
4.3.2.1.4 Salt Levels that Cause Injury to Vegetation—Salt damage to
26
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vegetation has been well documented in the literature and good summaries are
available (1,27). Emphasis in this section will be placed on key studies
which present quantitative data on ambient or experimental salt levels that
cause responses in plants. The rationale for presenting this information is
to formulate a data bank on salt toxicity to plants from which rough limita-
tions on cooling tower drift rates may be extrapolated, if possible. Areas
discussed below include: natural salt levels which cause injury, natural
foliar salt accumulation associated with injury, roadside runoff of deicing
salts which cause injury, and experimental concentrations that induce salt
toxicity symptoms.
Field data from the proposed Forked River Power Plant on natural aerosol con-
centrations causing damage are about all that exist. Damage to deciduous
plant species was a function of distance from shore during a "dry salt storm"
(Table 4-18). The conclusions of this study were:
1. The lower threshold for foliar injury to deciduous species
was associated with an airborne salt concentration of about
100 ug/nH for several hours during the growing season. Ever-
green species were less sensitive than deciduous varieties.
2. Long-term average values of less than 40 ug/m^ produced no
visible leaf scorch or related injury for the plant species
studied.
3. Airborne salt concentration greater than 10 ug/m-* may have
long-term effects on the distribution and growth of plants.
Future investigations of power plant sites in the pre-operational stage
should attempt to determine the nature and extent of influence of natural
background salt loading on local flora.
Foliar absorption and accumulation of Na+ and Cl~ are known to be toxic at
high concentrations, causing marginal necrosis in many woody plant species
(17). When leaves accumulate approximately 2000 ppm Na+ or 5000 ppm Cl",
symptoms develop (39). The naturally occurring seasonal variation of foliar
Na+ and Cl~ for four species native to the Chalk Point, Maryland, area are
presented in Table 4-19. Large accumulation of Cl' in dogwood foliage may be
a potential bio-indicator of salt drift (17). Chloride concentrations in
lombardy poplar and dogwood were, respectively, 2105 ppm and 3436 ppm Cl"
and did not seem to cause symptoms of foliar injury in those species (22).
However, avocado and grapefruit showed Cl" toxicity symptoms below 5000 ppm
Cl". Moderate leaf scorch in Vermont silver maples was observed at concen-
trations of 2000 ppm Cl" (41). Table 4-20 presents a partial list of Na+ and
Cl" levels which may cause toxicity symptoms in selected species (22).
Studies of plants along highways where deicing salts have been used provides
some information on salt toxicity symptoms in vegetation. Salt drift from
deicing compounds near Canadian highways was correlated with injury to ever-
greens during the winter season (42). Injury in red pine decreased linearly
over 115-395 ft. from the roadside, while the amount of injury correlated
with foliar Cl" concentration (Figure 4-28. Higher than background levels
of Na+ and Cl" occurred at depths to 18 inches and at distances of 75 ft.
from the road (41). Using silver maple as an indicator of salt injury to
27
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vegetation in the area, moderate leaf scorch was observed in leaves contain-
ing 0.2% Cl", whereas burning, defoliation and tree death were associated
with concentrations greater than .57. Cl~ in leaf tissue. Holmes (43), how-
ever, cited little damage to sugar maple, oak, ash, hickory, black birch and
white pine resulting from winter road salting procedures. For Holmes' data,
salt deposition rates of 700-4000 Ib/acre-mo (78500-449000 kg/kn^-mo) over a
3.5-year period failed to effect foliar injury to sugar maples in the area;
furthermore, these deposition values exceeded natural salt drift at seashore
localities by a factor of 3 to 17 (1).
Garber (44) demonstrated that spraying beans and lettuce with a 57. salt solu-
tion caused foliar injury. In greenhouse experiments, the degree of foliar
injury was related to exposure time of seawater mist application (Table
4-21). Scientists at the Boyce Thompson Institute reported that greenhouse
plants developed marginal wilting in plant leaves when exposed to a salt
aerosol concentration of 900 ug/m3 for 30-40 minutes with salt particles
ranging from 100-150 ug in diameter (45). Moser (14) observed that the ex-
posure of bean plants to 100 ug/m^ sea salt mist for 12 hours resulted in
acute injury, whereas exposure to 10 ug/m3 for 48 hours had no detrimental
effects. Extensive leaf damage in soybeans with salt spray treatments of
7.28 and 14.56 kg/ha-week has been reported (19). Yield reduction for soy-
beans occurred at the 7.28 kg/ha-week treatment and for corn at 1.82-3.64
kg/ha-week treatment. In addition, younger leaves demonstrated greater sen-
sitivity than older leaves in soybeans; while in corn, the opposite was ob-
served - namely, older leaves were more sensitive than younger leaves to salt
sprays.
Comparing Tables 4-22, 4-23 and 4-24, a noticeable reduction of the metabolic
index is apparent with application of salt spray to corn and soybeans. Such
a diagnostic tool would be useful in comparing pre- to post-operational ef-
fects of cooling tower drift on vegetation, provided the necessary baseline
data on foliar concentration of major ions are available.
Simulated salt drift leaf injury in dogwood was induced by repeated applica-
tion of salt spray with a mechanical sprayer apparatus (21). Marginal burn
symptoms appeared after the two highest treatments and the percentage of
affected leaves was directly related to the number of spray treatments (Fig-
ures 4-29 and 4-30). The degree of leaf injury is presented in Figure 4-27.
McCune et al. (24) estimated that foliar necrosis and premature loss of
affected foliage on the most susceptible species of plants at Indian Point,
New York, was induced by total salt deposition greater than 2.4 ug Cl'/cm2 in
6 hr. The most susceptible species in this study were flowering dogwood,
white ash, and Canadian hemlock (Tables 4-25 and 4-26).
In addition, when white flowering dogwood and white ash were exposed at 707.
RH, no foliar symptoms were induced at concentrations of 800-1700 ug Cl"cm~2
for 6-20 hours, but at 85% RH aerosol concentration of 1500-1700 ug Cl~/cm2
induced foliar injury (Table 4-27). The effect of humidity may be related to
the deliquescence of NaCl around 757. relative humidity, thus increasing pene-
tration of salt deposited on leaves at the higher humidities (75-857.) (24).
28
-------
Figure 4-31 depicts the dose-response relationship of bush bean to aerosol
mist experimental treatments (24) for three factors: aerosol deposition,
particle size and relative humidity. The amount of injury produced by dosage
around the median effective dose (£059) was from 5-10% of the foliar surfaces
of the affected leaves. The £050 for an aerosol with 957= of particles be-
tween 50-150 urn in diameter was 48 ug Cl~/cm2. An increase in relative hu-
midity from 50 to 85% during the exposure period increased by two-fold the
incidence of injury in bush bean plants for the same exposure.
The incidence and severity of injury to bush beans increased with increasing
foliar salt concentration (27). In general, low levels of injury were ob-
served at the 5 and 25 ug/nr treatments, whereas more extensive damage and
higher foliar salt accumulation was apparent at the 75 ug/m^ salt concentra-
tion (Table 4-28). These studies indicated that in order to detect detrimen-
tal growth effects, foliar salt levels must be high enough to produce "mod-
erate" amounts of injury, approximately 5-25% of the leaf area. The associ-
ated toxicity level for five-week old plants ranged from 900-12000 ppm Na+
and 6300-41000 ppm Cl~ for lower and upper limits of injury, respectively
(Table 4-28). The degree of foliar injury appears to be correlated with
aerosol concentration, at least for the tested values of 5, 25 and 75 ug/m^
(Figures 4-32 and 4-33). The dose-response relationship for salt spray in-
duced injury to bush beans indicated that their sensitivity to salt spray
increases with age (Figure 4-34). The median effective dose (ED5p) for five-
or th«
week old plants is approximately 70 ug/m->, whereas the ED5Q for the one- and
three-week old plants is around 165
Foliar injury has been reported as a consequence of several cooling systems.
"At Turkey Point, Florida, introduced cultivated plants (bush bean) showed
visible foliar damage and elevated salt concentration in their leaves, indi-
cating the combined influences of the cooling device and east wind drift ex-
posure only at the exposure site which is closest (215 m) to the cooling
canal spray modules (27). Tobacco plants placed closer (150-200 m) to mech-
anical draft cooling towers accumulated more chromium and had less total
leaf weight than those located 600-1400 m away (46). Feder (47) cited foliar
salt injury for several woody species downwind from a saline spray canal. No
significant increase in leaf Cl~ concentration for native perennial vegeta-
tion (Virginia pine, black locust, sassafras and dogwood) occurred during the
partial operation of the Chalk Point cooling tower in 1975 (16). Other work-
ers at the Chalk Point Site found similar results for soybeans, tobacco and
corn (20). The paucity of studies monitoring drift effects of operational
cooling towers on vegetation necessitates a concentrated research effort be-
fore real impacts can be determined. Table 4-29 lists current information on
the effects of cooling tower drift on the environment.
Salt problems on vegetation related to soil salinities and irrigation with
saline water were treated extensively (1,36,39,48). Salt levels available
to plants are a function of:
1. Background salt concentration of ground and surface water,
2. Salinity of irrigation water,
3. Highway runoff that may contain deicing salt compounds,
4. Cooling tower and natural salt spray drift additions.
29
-------
In discussing the effects of cooling tower drift on soil and its associated
vegetation, it is necessary to consider the added effects of drift salts on
agro-ecosystems and on natural communities, whose biotic components and sen-
sitivities to salt have already been determined through evolutionary time.
Estimates of salt deposition from a cooling tower are numerous but have little
basis in reality if not measured from operating cooling towers. For example,
an increase of about 18 mg ClVl in the salinity of irrigation water con-
taining 200 mg Cl~/l is expected in arid zones, assuming all surface salt
(using maximum deposition values from the cooling tower) dissolved in irriga-
tion water. In terms of increased salinity, less than 1 mmhos/cm was added.
This appears negligible when compared to the levels of non-saline and non-
alkaline soils, which have less than 4 mmhos/cm (1).
Plant response to changes in soil characteristics are generally due to changes
in total salt level (osmotic potential) of soil water, or to species-specific
sensitivity to sodium and chloride (1). Increased levels of soil sodium af-
fect plants directly or indirectly. Direct effects may include alteration of
the nutritional balance in plants, resulting in calcium deficiency. This
occurs at levels as low as 4-5% of the exchangeable sodium in sodium-sensitive
crops such as almonds, avocado, citrus and stone-fruits (49). Indirect ef-
fects include inhibition of plant growth due to poor aeration and water trans-
mission. Such changes may result if the quantity of absorbed Na+ is greater
than 10-15% of the total exchangeable soil cations (51).
Toxic levels of chloride have been documented to some extent in the litera-
ture. Specific phytotoxicity is reported for almonds, avocado, citrus, stone
fruits and grapes (1). Chloride ion uptake with Ca++ is twice that of Na+
and may be associated with a co-ion effect (50). Non-sensitive crops thrive
well in soil solution of 850-4250 mg/1 Cl", while tolerable loading for irri-
gation water is usually less than 1700 mg/1 Cl" (1). However, Bernstein et
al. (36) reported injury to almonds, citrus and stone fruits for irrigation
water with a concentration of 100-175 mg/1 Cl".
Plant tolerance to various soil salinities is sometimes a function of age
(1). For example, beets are salinity sensitive during germination (Figure
4-35) but are salt tolerant in later stages of growth (Figure 4-36). At
Chalk Point, Maryland, the results of the first year of cooling tower opera-
tion indicated no appreciable accumulation, or change, in soil pH, Mg, P, K,
Ca, or Na (20).
A series of reference graphs have been compiled and are presented in Figures
4-37 to 4-41. This data should be used in future salt drift monitoring
studies which investigate soil salt loading from cooling towers and its ef-
fect on crops and other vegetation. Again, the need for comparison of pre-
and post-operational data is recommended to determine real or potential ef-
fects on vegetation.
4.3.2.2 Salt Deposition Effects on Land Vertebrates, Freshwater Fish and
Other Animals—
.e detrimental effects of cooling tower salt drift on the fauna in the re-
on of the cooling tower are generally considered negligible (1,26,38,51,
). Edmonds et al. (38) mentioned that synergistic responses to inert aero-
30
-------
sols (Nad) and pollutants such as S02 have been observed but only in extreme-
ly sensitive animals exposed to high experimental concentrations of S02> ex-
ceeding 20 ppm. Salt tolerances of animals are reviewed by Wolgast et al.
(26). For easy reference, Table 4-30 includes a listing of salt tolerance
studies reported through 1972.
Few pre-operational cooling tower studies exist which have attempted to deter-
mine salt loading and its possible consequences on the fauna. Bird impaction
studies at the Three-Mile Island Nuclear Plant evaluated the nature and extent
of mortality or injury to birdlife in the area (29). The results of this
15-month study showed that no increase in mortality occurred during the opera-
tion of the cooling tower when compared to pre-operational data (Table 4-31).
No data, however, was recorded on the effects of salt drift on the avian com-
ponent of the region. Wolgast e_t al. (26) estimated the potential effects of
salt drift on land-dwelling vertebrates from a proposed saltwater cooling
tower (Forked River, New Jersey) and anticipated no direct physiological ef-
fects on vertebrates for the expected salt loading at the site. In fact, a
greater abundance and diversity of small mammals were observed in the coastal
maritime vegetation community, an area of high ambient salt loading (15) than
in the mainland habitats (53). No information was found on drift effects on
fish.
Although excess salt may cause detrimental effects, and animals do have oppor-
tunities to ingest excessively salty food or water containing enough salt to
cause osmotic changes in excess of the amount regulatory mechanisms can
handle, current theories suggest that, at least for mammals and insects, some
animals have evolved salt receptors warning against hypersalinity (54). This
evidence of parallel evolution suggests that compensatory mechanisms for
excessive salt loading may exist, thus allowing some species to regulate their
salt intake, regardless of ambient concentration.
In addition to the direct physiological changes reported, indirect effects to
land vertebrate populations are possible if vegetation communities are altered
significantly by salt drift effects (26). The magnitude and direction of
these changes cannot be predicted until data is gathered on the long-term
effects of cooling tower drift on the biota.
31
-------
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2. Wilber, K. R., 1976. Ambient Sea Salt Measurements in the Beesley
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tl. Central Electricity Generating Board. Use of Salt-Water in Cooling
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32
-------
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12. Gorry, W. L., and M. Cropper. Report on the 20 Years Experience of
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13. Dale, F. W., and M. Cropper. An Investigation of Local Salt Deposition
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14. Moser, B. C., 1975. Airborne Sea Salt: Techniques for Experimentation
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353-369.
15. DeVine, J. C. Jr., 1975. The Forked River Program: A Case Study in
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Douglass, 1977. Potential Cooling Tower Drift Effects on Native
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Pollution and the Impact on Agriculture, Col. State College,
Stanislaus, Tulock, Calif. Jan. 13-14, 1977.
•
17. Curtis, C. R., T. L. Lauver and B. A. Francis, 1977. Foliar Sodium
and Chloride in Trees: Seasonal Variations. Environ. Poll.
14: 69-80.
18. Hittman Associates, Inc. Aug. 1977. Saltwater Cooling Towers: A
State-of-the-Art Review. Preliminary Draft Report HIT-700, Hittman
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19. Mulchi, C. L. and J. A. Armbruster, 1975. Effects of Salt Sprays on
the Yield and Nutrient Balance of Corn and Soybean. In; Cooling
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Ser., CONF-740302, pp. 379-392.
20. Mulchi, D. L., D. C. Wolf, J. E. Foss and J. A. Armbruster, 1976.
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WRRC Special Report No. 3, 53 p.
21. Curtis, C. R., T. L. Lauver and B. A. Francis, 1976. Cooling Tower
Effects on Native Perennial Vegetation. Pre-operational Report.
Special Report No. 2 PPSP-CPCTP-7. Univ. Maryland, College Park,
Maryland. 51 p.
33
-------
22. Curtis, C. R., H. G. Gauch and R. Sik, 1975. Sodium and Chloride
Concentrations in Native Vegetation Near Chalk Point, Maryland. In:
Banna, S. R. and J. Pell (eds.). Cooling Tower Environment - 1974.
ERDA Sympos. Ser. CONF-740302.
23. Curtis, C. R., T. L. Lauver, and B. A. Francis, 1976. Field Research
on Native Vegetation. Final Report FY76, Water Resources Research
Center, Special Report No. 4. PPSP-CPCTP-14. Univ. Maryland, College
Park, Maryland, 121 p.
24. McCune, D. C., D. H. Silberman, R. H. Mandl, L. H. Weinstein, P. C.
Freudenthal and P. A. Giardina, 1977. Studies of the Effects of Saline
Aerosols of Cooling Tower Origin on Plants. J. Air Poll. Contr. Assoc.
27(4): 319-324.
25. Rochow, J. J., 1975. Palisades Nuclear Plant Cooling Tower Drift
Study. Preoperational Study Report.
26. Wolgast, L. J., R. Rogers and W. R. Clark, 1973. Predicted Environ-
mental Impact of Salt Drift from a Proposed Cooling Tower of Land-
Dwelling Vertebrates on the Outer Coastal Plain of New Jersey. Trans.
Northeast Fish and Wildlife Conf. 1972 (Sel pap.) Nevele Country Club,
Ellenville, N.Y., May 14-17, 1972.
27. Hindawi, I. J., L. C. Raniere and J. A. Rea, 1976. Ecological Effects
of Aerosol Drift from a Saltwater Cooling System. Ecological Research
Series, EPA-600/3-76-078.
28. BuKovac, M. J. and. S>. ^. "Vtt-ttner, 1957. Absorption and Mobility of
•Poliar Applied Nutrients. Plant Physiol. 32: 428-435.
29. Mudge, J. E. and R. W. Firth, 1975. Evaluation of Cooling Tower Eco-
logical Effects on Approach and Case History. Presented Before 21st
Annual Meeting American Nuclear Society, June 12, 1975, New Orleans.
30. Nicholas, G. W. and D. M. Sopocy, 1974. Evaluation of Cooling Tower
Environmental Effects. Combustion - Nov. 1974: 34-41.
31. Swain, R. L., 1973. Airborne Sea Salt: Some Aspects of the Uptake and
Effects on Vegetation. Unpublished M. S. Thesis, Rutgers Univ.,
New Brunswick, N.J.
32. Boyce, S. G., 1954. The Saltspray Community. Ecol. Monogrer 24(1).
33. GPU Service Corp., 1974. Program to Investigate the Feasibility of
Natural Draft Salt Water Cooling Towers. Appendix to Applicant's
Environmental Report for Forked River Unit No. 1, Parsippany, N.J.
34. Sprague, J. B., 1973. The ABC's of Pollutant Bioassay Using Fish.
In: Biological Methods for the Assessment of Water Quality, ASTM STP
528, American Society for Testing and Materials, pp. 6-30.
34
-------
35. Strong, F. G., 1944. A Study of Calcium Chloride Injury to Roadside
Trees. Mich. Agr. Exp. Sta. Quart. Bull., 27: 209-224.
36. Bernstein, L., I. E. Francois and R. A. Clark, 1972. Salt Tolerance
of Ornamental Shrubs and Ground Covers. J. Amer. Soc. Hort. Sci.
97: 550-556.
37. Lomas, J. and F. Gat, 1967. The Effect of Wind-Borne Salt in Citrus
Production Near the Sea in Israel. Agr. Meteorol. 4: 415-425.
38. Edmonds, P. R., A. K. Roffman, R. C. Maxwell, 1975. Some Terrestrial
Considerations Associated with Cooling Tower Systems for Electric Power
Generation. In; Cooling Tower Environment - 1974. Hanna, S. R. and
J. Pell (eds.). ERDA Symp. Ser., CONF-740302, pp. 353-369.
39. Bernstein, L., 1975. Effects of Salinity and Sodicity on Plant Growth.
Ann. Rev. Phytopath. 13: 295-312.
40. Eaton, F. W., 1966. Diagnostic Criteria for Plants and Soil. Chapman,
H. D. (ed.) pp. 98-135, Div. Agr. Sci., Univ. Calif. Berkeley, Calif.,
1966.
41. Blaser, R. E., R. E. Haner and L. W. Zelazny, 1972. Effects of De-
icing Compounds on Vegetation and Water Supplies. Smithsonian Sci.
Inform. Exch. No. 64-28404-3.
42. Hbfstra, G. and R. Hall, 1971. Injury on Roadside Trees: Leaf
Injury on Pine and White Cedar in Relation to Foliar Levels of Sodium
and Chloride. Can. J. Botany 49: 613-622.
43. Holmes, F. W., 1961. Salt Injury to Trees. Phytopath, 51: 712.
44. Garber, K., 1964. On the Importance of Aerosol Salt for Plants.
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45. McCune, D. C., et al., 1974. Studies on the Effects of Saline Aero-
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APCA Meeting, Denver, Colorado, by Boyce Thompson Institute for Plant
Research, New York.
46. Parr, P. P., F. G. Taylor, Jr. and J. J. Beauchamp, 1976. Sensitivity
of Tobacco to Chromium from Mechanical-Draft Cqoling Tower Drift.
Atmos. Envirn. 10: 421-423.
47. Feder, W., 1976. Impact of Saline Mists on Woody Plants. Proc. Amer.
Phytopath. Soc. (Abstr).
48. Bernstein, L. and L. E. Francois, 1975. Effects of Frequency of
Sprinkling with Saline Water Compared with Daily Drip Irrigation.
Agron. J. 67: 185-190.
35
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49. Yaron, B., E. Danfors and Y. Vaadia (eds.). Irrigation in Arid
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36
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62. Hanna, S. R., 1977. Atmospheric Effects of Energy Generation.
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68. Ek, N., 1966. Experimental Salt Poisoning in Pigs. Nord. Veterinaer
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69. Tercalfs, R. R. and E. Schoffeniels, 1962. Adaptation of Amphibians
to Salt Water. Life Sci. 1: 19-24.
.70. Strahan, R., 1957. The Effect of Salinity on the Survival of Larvae
of Bufo Melanostictus. Copeis 1959(2): 146-147.
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tion by Savannah Sparrow. Physiol. Zool. 32: 230-238.
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73. NYSE&G, 1974. Cayuga Station Environmental Report No. 1. Application
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Environment. February, 1974, 73.4-30C.
37
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LONG-RANGE
TRANSPORT'
RUN-OFF
LEACHING,
ADSORPTION
ATMOSPHERE
• DIRECT
DEPOSITIONS '
• ' PLANT
• . LIFE
"EMISSIONS
ROOT
ABSORPTION
LONG-RANGE
'TRANSPORT
Figure 4-1 Scheme shoving the possible relationships between emissions
and direct depositions on soils and plant life (21)
-------
1000
"n—n—n—i i i IM
MASS SIZE DISTRIBUTION
'! 4 1 1 i
500
CO
13
B
100
50
10
1- FISH AND DUNCAN
2- RESEARCH-COTTRELL
{UNPUBLISHED)
3- CPU
4- PSU (KEYSTONEJ
5- ESC (CHALK POINT)
6- STANDARD INPUT
USED BY CHEN
f I M »' I I I • I I i . f
0.1 0.2 125 10 20
SO
80 95 98 99 99.8
PERCENT PROBABILITY OF TOTAL MASS SMALLER THAN STATED
Figure 4-2 Cumulative mass distributions of drift droplets
for natural-draft cooling towers (59)
39
-------
5000f
T—\—r~i
T—i 1—r
1000
500
Q
H
i
too
__ ^^M» «*^» «*»^™* |
* ^^*^
5 —
1 ECODYNE. 1973
2 ORGDP. 1973
3 TURKEY POINT, 1974
4 NEW CALIBRATED
ECODYNE DATA. 1976
S ESC. 1971
i i
10
20
30 40 SO 60 70 80
90
95
PERCENT PROBABILITY OF TOTAL MASS SMALLER THAN STATED
Figure 4-3 Cumulative mass distributions of drift droplets
for mechanical-draft cooling towers (59)
40
-------
WNW,
WSW
sw
AIRBORNE PARTICULATE CONCENTRATIONS
N
NNW
NNE
SSW
SSE
NE
ENE
ESE
SE
Figure 4-4 Airborne sea salt collected at Station 4 (3)
41
-------
.001
.01
J
DISTANCE, kilometers
Figure 4-5 Air Concentration of Salt Drift As A Function of Distance From The Sea (1)
-------
MOSEfl
400
300
et
<
Fig. 4-6 Airborne salt concentra-
tion (jjg/m3) as affected by dii-
tance inland from the surf
(14)
200
Ul
I/I
o»
a.
100
1 Averagi
High-level incident
0 6 12 18
DISTANCE INLAND FROM SURF, km
43
-------
20,
18
10
14
12
I I I I I I 1 I
I"
12
n i: "j i ii i i ^
0 2 46 8 10 12 14 16 18
DISTANCE FROM SHORE, mitat
Figure 4-7 Ambient (sea salt) airborne salt
concentration as a function of distance
from the shore
Forked River Saltwater Cooling Program
44
-------
1,2 ANONYMOUS
3,4 GPU(32)
66 10 12 14
DISTANCE, kilometers
Figure 4-8 Normalized Airborne Salt Values As A Function Of The
Distance Inland (with an Initial Value of One at Sea
Shore)
45
-------
I ANONYMOUS
2
3 LOMAS AND OAT(W) , -
4 EDWARDS AND HOLMES191
0.001
DISTANCE, kilometers
Figure 4-9 Natural Drift Deposition Rat* Aa A Function Of Distance Proa The Sea (1)
-------
100 300 500
DISTANCE INLAND FROM SURF, m
Figure 4-10 Sedimentation rates of airborne salt as affected
by distance inland from the surf
47
-------
Figure 4-11 Average Cl~ Concentration, mg/1 In Rainwater, July-Septeober 1955 (61)
-------
Figure 4-12 Average Cl~" Concentration, mg/1 In Rainwater, January-March 1956 (61)
-------
1000
800
f 600
•400
200
Station 1
d
• X
-Stations
Station 4
Station 5
Station 7
Station 8
I
25
20
15
10
8 16 24
DISTANCE FROM SHORE, km
32
Figure 4-13
Exemplary data for*^ and dfl in the
near vicinity of the Oyster Creek
Generating Station at Forked River, NJ.
(Data published with permission of
General Public Utilities.) (15)
50
-------
ENVIRONMENTAL SYSTEMS CORPORATION
1000-
800-
:
»
* *«•
* 5
> a
I
U1 600-
^E
i
400 H
200-
OONCENTRATION -_-^_ —^>- —
DEPOSITION DO
^> Station 1
n
I
\
\
\
\\ ^Station 2
t^V ^Station 3
A ^E^-^^---"" — Station 8 W
-------
mmfww »•
1,000 -
ftAA
OvW «
is 600-
o e
H **
§5 400 -
3~
to
200 -
Mr»wMn«*Bw i»»v«^w wvwrwoum*&v**
Off — .-^»«— HS^"~
* Station 1
V Station 2
IV /
1 / C J Q
\ V /Station 3 Station 5
\/V / /Statlon4 I Stations
X x^ /station 4A (8) 1 1
\ ^*- T3T- ._ — — —_fi_ Station 7—^ >(
^-r-- --"ID » ^
i i i i i i \
4 8 12 16 20 24 28 3
-36
w
-28 5
-24 H
-20 1,1
^ 9
-u 1
••%
-.2 §
- 8
- 4
2
DISTANCfe FROM SHORE
(km)
Figure 4-15 Average Aableat Ground Level Sea Belt Concentration and Deposition a* a Function of
Distance fro* the Snore Obveaber 20, 1973 - Noveaber 5, 1974) (6,7)
-------
ENVIRONMENTAL SYSTB1S CORPORATION
1200.,
1000
800
600
CONCENTRATION
DEPOSITION
- -o--o- -
400-
200
I-40
DISTANCE FROM SHORE
(km)
Figure 4-16 Average Sea Salt Concentration and Deposition as a Function of Distance from the Shore
(November 6, 1974 - November 11, 1975) (Unit Operation: On During Entire Test Period)
(6,7)
-------
15
8 -
H
U
W
O
Ul
I
i
Q
O 5
W
(Q
n
100
200 300
DROPLET DIAMETER
En
n
400
500
Figure 4-17 Histogram of Droplets Collected by Film Sampler (Traverse 15-8, 15-9) (8)
-------
• A
• B
• C
• D
VISIBLE PLUME
VAPOR PLUME
^VVV\vv«.V »A
% \ •*•?*•• "DRIFT • *•• "•• »B
. \ \••.C'. "'• DROPLET \ "».C
,\\ kD.\PLUME ,\V
•A
• B
• C
• D
2L
DOWNWIND DISTANCE:
0.
1.
2.
3.
4.
ALTITUDE;
A.
B.
C.
D.
Upwind from source.
As close to the tower as safety permitted.
Approximate midpoint of the visible plume (L/2).
Near end of the visible plume (L).
Approximately double the visible plume length (2L).
Just below the visible plume.
Intermediate level between the visible plume and ground.
Intermediate level between the visible plume and ground.
As close to the ground as safety permitted.
SAMPLING MODE:
• Horizontal Traverse.
£ Vertical Temperature Sounding.
Figure 4-18 Drift Droplet Plume, Test Plan No. 2 (8)
55
-------
in
Figure 4-19 PILLS/SP consolidated curve for cooling
tower position 27 of diameter SW-NE 3. (9)
DATE: 7/23/74
D PILLS DATA
o SP, SMALL STAIN COUNT
• SP, MEDIUM STAIN COUNT
CONSOLIDATED CURVE
ORDINATE NOTATION: 5 E-l MEANS BxlOj
1 E-2
I I I 1 I i I I I I I I I I I I I I T I
50 ' 100 150 200 250 300 350 400 450 500
DROPLET DIAMETER, inn
-------
3000
1OOC
300
t!
I
5
20
•TURKEY POINT
5 1O ZO 3O 40 5O 6O 70 80 SO S5 S3
PFBfFNTAR-
Figure 4-20 Cumulative drift distributions of three
mechanical-draft cooling towers (9)
57
-------
•N
MODULES
COOLING TOWER
Figure 4-21
APS station locations for monitoring ambient
air salt loadings and salt contributions from
cooling device sources. January 1974 - July
1974. Distances in meters.(10)
58
-------
1000
1
t-
o
K
100
T
H -90%
c • S x 10T?
50 100 ISO 200 250
DROP RADIUS (r I, itm
300
3SO
Figure 4-22 Height of evaporation of drift drops (1)
59
-------
Figure 4-23 Layout Of Deposit Gauges In Vicinity Of Fleetwood Power
Station (1)
60
-------
LJ
3
E
IMMEDIATE
RINSE
2 3 45 6
HOURS BEFORE RINSING
Figure 4-24 Chloride buildup in bush bean leaf tissue over 8 hours
from one spray application in each of two humidity
conditions. High humidity - 75-80% RH; low humidity -
55-70% RH. Control plants (C) were not sprayed (31)
61
-------
UJ
CO
£ 2
H
o:
o
o
o
O
t»
E
48 IE 16
HOURS BEFORE RINSING
24
Figure 4-25 Chloride buildup in bush bean leaf tissue over 24 hours
from one spray application in each of two humidity con-
ditions. High humidity - 75-80% RH; low humidity -
55-70% RH. Control plants
-------
UJ
z>
OT
CO
>" •*
tc °
o
o
g
V.
I
O
o»
100%
50 %x
10% X
•CONTRO'.
0 I 2
TREATMENT INTERVAL,Days
Figure 4-26 Chloride accumulation in bush bean foliage tissue over a
period of one month after one spraying per treatment at
indicated intervals with 10, 50 or 100% sea water (31)
63
-------
100
CO
QJ
UJ
LU
60
20
0
injury
class
• 0-25%-]
0 25-50%
• 50-75%
D 75-100%
1X 2X 3X 4X
TREATMENTS
Figure 4-27 Dogwood leaf injury classes after simulated
drift treatment (21)
64
-------
UJ
O
<
O
cc
o
u_
80
60i
40
20
0
100
DISTANCE, Feet
300 500
700
30 60 90 120 150 180 210
DISTANCE, Meters
B
o 6
357
CHLORIDE^ Percent
(A) Distance from the roadside, and
(B) Foliar concentration of
chloride
Figure 4-28 Foliar damage of red pine (Pinus resinosa) (42)
65
-------
30
& 2S
20
ff 15-
DC
< 10H
3?
5-
w
£—
r
5 25 75
SEA SALT AEROSOL CONCENTRATION
(Exposure initiated at:
week.)
5 weeks, —• . 3 weeks, *•—, 1
Figure 4-29 Mean percentage foliar area injured on the first
three sets of trifoliate leaves of three ages of bush bean
(Phaseolus vulgaris L.) after 100 hours exposure to various
sea salt aerosol concentrations (27)
66
-------
100-
£ 80
Q
UJ
Qi
60-
JS 40
(LI
20-
0
i i
04X
• 3X
O 2X
1X
Tap
No spray
JUL7
JUL 24 AUG 8 AUG 22
Figure 4-30 Dogwood leaf Injury classes after simulated drift treatment (23)
-------
130
10
A *
100
Dos« of saline particles, m Cl/em2
LEGEND
A exposures to 857. relative humidity (RH) to an aerosol
wl?h 56, 28, and 04-13% of the particles between 50 and
150, between 150 and 250, and greater than 250 microns
diameter, respectively.
Oexposures to an aerosol with 95% of the particles between
50 and 150 microns in diameter and 0-857. RH during and
after exposure; 0-50% RH during and after exposure; 0-857.
RH during, 50% RH after exposure; and 0-50% RH during and
85% RH after exposure.
Figure 4-31 Relationship between incidence of foliar Injury in bush
bean and dose of saline aerosol (24)
68
-------
U1H-
Z*
t -J
Z Q.
W-t
o2.
ffiS
25i
0 -
-25-
-50-
-75-
-100 "-T
5 25 75
SEA SALT AEROSOL CONCENTRATION
5 weeks.
3 weeks, -- -+ — 1 week.
Figure 4-32 Percentage reduction of mean plant pod dry weight
(with seeds) of mature bush bean after exposure to three dif-
ferent sea salt aerosol concentrations at three stages of
growth (plant age at initiation of exposure) (27)
69
-------
60i
SEA SALT AEROSOL CONCENTRATION (V9/m )
Figure 4-33 Mean percent trifoliate leaves injured on three
ages of bush bean fPhagenliia jmlgaxis__L.) after 100 hours
exposure to different sea salt aerosol concentrations (27)
70
-------
Figure 4-34 Log dose-response plot for bush bgan(Pha8eolus vulgar is L.)
trifoliate leaves injured following exposure to three concentrations of
sea salt aerosol for 100 hours at different stages of growth. EIPO
represents the concentration where 5071 of all trifoliate leaves exhibit
injury (27)
•98
Q
HI
cc
C/3
HI
LLJ
LJJ
o
u.
QC
5 10 25 75 100
DOSE—SEA SALT AEROSOL CONCENTRATION
-------
IUU
_l
"**-\OATS
\x-
Figure 4-35 Effect of soil salinity on germination of crop plants (1)
-------
w
BEANS
CARROTS
ONION
BELL PEPPER
. LETTUCE
SWEETPOTATO
CORN
POTATO
CABBAGE
BROCCOLI
TOMATO
SPINACH
BEETS
YIELD REDUCTION
0-10% I \
10-25% HUD
25-50% I I
>50%
8
10 12
14
16
18 20
Figure 4-36 Salt tolerance of vegetable crops grown from late
seedling stage to maturation. Crops are arranged
in order of increasing salt tolerance (1)
-------
0-25%
25-50%GHD
>50%
LETHAL
BOUGAINVILLEA
NATAL PLUM
ROSEMARY
EUONYMUS
DRACENA
SILVERBERRY
DODONEA
BOXWOOD
PITTOSPORUM
ARBORVITAE
OLEANDER
BOTTLE BRUSH
HIBISCUS
HEAVENLY BAMBOO
ALGERIAN IVY
BURFORD HOLLY
STAR JASMINE
LANTANA
JUNIPER
PYRACANTHA
XYLOSMA
TEXAS PRIVIT
VIBURNUM
ROSE
PINEAPPLE GUAVA
LD50
m mhos/cm
9
5
6
8
II
12
12
9
12
9
4
4
0
2
4
6 i
* 10
12
Figure 4-37
Salt tolerance of ornamentals as measured by the
decrease of top-growth weight. The estimated soil
salinities at which 50% of the specimens of each
species died are indicated as LD50 (36)
74
-------
Ul
BEANS
FLAX
BROAD6EAN
CORN
RICE PADDY
SESBANIA
SOYBEAN
SORGHUM
WHEAT
SAPFLOWER
COTTON
SUGARBEETS
BARLEY
Jill
YIELD REDUCTION
0-10%
10-25% irrni
25-50% I I
>50%
8
10 12
14
16 18 20 22
Figure 4-38 Salt tolerance of yield crops grown from late
seedling stage to maturation. Crops are arranged
in order of increasing salt tolerance (1,55)
-------
CLOVERS
MEADOW FOXTAIL
ORCHARD6RASS
ALFALFA
BEARDLESS WILDRYE
BIRDSFOOT TREFOIL
HARDING6RASS
PERENNIAL RYE
BARLEY HAY
TALL FESCUE
CRESTED WHEATGRASS
TALL WHEATGRASS
BERMUDA GRASS
YIELD REDUCTION
0-10% I 1
10-25% urn
25- 50% I 1
>50%E=|
ill
8
10 12 14 16 18 20
Figure 4-39
Salt tolerance of forage crops grown from late seedling
stage to maturation. Crops are arranged in order of
increasing salt tolerance (55)
-------
0
o
£
100
80
Q
uj 60
uj 40
P
d20
o:
joo
c
o
£ 80
Q.
3 60
UJ
< 20
UJ
cr
BARLEY
4 12
ECe, m mho/cm
20
ALFALFA
100
80
6O
40
20
4 12 20
ECe, m mho/cm
100
80
60
40
20
CORN
4 12 20
ECe, m mho/cm
COTTON
100
80
60
40
20
4 12 20
ECe,m mho/cm
SORGHUM
4 12
EC0I m mho/cm
20
Figure 4-40 Relation between soil salinity and relative yield of five crop plants (1)
-------
00
MODERATELY
TOLERANT
678 9 10 II 12
ECe, Millimhos/centimeter
13 14 15 16
Figure 4-41 Relation between Soil Salinity and Relative Crop Yield for Tolerant,
Moderately Tolerant and Sensitive Plant (1,49)
-------
TABLE 4-1
EFFECTS OF SIMULATED RAIN ACIDIFIED WITH
••4
VO
SULFURIC ACID ON HOST-PARASITE INTERACTIONS
Host -Pathogen,
System
Greenhouse Studies
Quercus phellos-
Cronartium
fusi forme
Oak-Pine Rust of
Oak
Phaseolus vulgaris-
Pseudomonas
phaseolicola
Halo Blight of Bean
Acidity
Pre-
Inoculation
(PH)
3.2
6.0
3.2
3.2
3.2
3.2
6.0
6.0
6.0
6.0
(56)
of Simulated Rain
Inocu-
lation
(PH)
3.2
6.0
3.2
3.2
6.0
6.0
3.2
3.2
6.0
6.0
Post-
Inoculation
(PH)
3.2
6.0
3.2
6.0
3.2
3.2
3.2
6.0
3.2
6.0
LSD
.05
Disease Measure
Infected Leaves/ Telia/
Plant Infected Leaf
3.8+ 15 +
6.5 115
Dead Leaflets/
Plant*,!
(No.)
O.Oa*
O.Oa
4.2d
4.8d
O.Oa
O.Oa
2. Ob
3.2c
0.77
*ANOVA significant, p = 0.05
•fEach value is the mean of 6 plants/treatment
•$No. of inoculated leaflets (max. 6/plant) which were dead on plants which developed symptoms
characteristic of halo blight
|Each value is the mean of 5 plants.
^Values in a column followed by the same letter were not significantly different,
-------
TABLE 4-1 (cont'd)
RFFETTS OF SIMULATED RAIN ACIDIFIED WITH
oo
STTT.FITRIC Anin ON WIST-PARASITE INTERACTIONS
Host-Pathogen
System
Field Studies
Phaseolus vulgaris-
Meloidogyne
hap la
Root Knot Nematode
on Beans
Phaseolus vulgaris-
Uromyces phaseoll
Rust of Beans
(56)
Acidity of Simulated
Rain Disease Measure
Pre- Inocu- Post-
Inoculation lation Inoculation
(pH) (PH) (PH)
3.2 3.2
6.0 6.0
3.2 3.2
6.0 6.0
Eggs/Plant4" % Root Galled4"'*
3.2 74* 26
6.0 217 50
% Leaf Area Affected At:
7 Weeks 9 Weeks
3.2 22* 48
6.0 31 45
*ANOVA significant, p - 0.05
•*£ach value is the mean of 18 plants/treatment.
$ Percent of root area galled by Meloidogyne hap la.
-------
TABLE 4-2
oo
Eliminator
Case No. Type
1
2 Single louver
3
4
5
6 Double- layer
louvers
7
8
9 Sinus shape
Pitch, cm
3.92
3.92
3.92
6.2
4.4
4.25
____
5.08
Height, cm
5.44
5.44
5.44
13.2
14.7
13.2
____
17.8
Inclination
Angle, °
45
45
45
60
75
60
—
--
—
Air Flow
m/sec
0.91
1.52
2.13
2.13
1.52
0.91
1.52
2.13
2.13
Calculated
Overall Collection
Efficiency
0.9284
0.9816
0.9987
0.7978
0.7516
0.9580
0.9762
0.9576
0.9992
-------
TABLE 4-3
FACTORS AFFECTING DISPERSION AND DEPOSITION OF DRIFT
EROM NATURAL-DRAFT AND MECHANICS-DRAFT TOWERS (1) "~
oo
Factors associated with the design
and operation of the cooling tower
Volume of water circulating in the
tower per unit time
Salt concentration in the water
Drift rate
Mass size distribution of drift
droplets
Moist plume rise influenced by
tower diameter, height and mass
flux
Factors related to atmospheric
conditions
Atmospheric conditions including
humidity, wind speed and direction,
temperature, Pasquill's stability
classes, which affect plume rise,
dispersion and deposition.
Tower wake effect which is especi-
ally important with mechanical
draft towers
Evaporation and growth of drift
droplets as a function of
atmospheric conditions and the
ambient conditions
Other factors
Adjustments for
non-point source
geometry
Collection efficiency
of ground for drop-
lets
Plume depletion effects
-------
TABLE 4-4
ATMOSPHERIC VARIABLES AND CHARACTERISTICS
AFFECTING THE DISPERSION ANp THE DEPOSITION
OF DRIFT (60)
Atmospheric variables
Ambient temperature
Ambient relative humidity
Wind speed and direction
Precipitation (rain and snow)
Concentration of condensation
nuclei
Atmospheric characteristics
Atmospheric stability
Depth of the mixing layer
83
-------
TABLE 4-5
DESIGN AND OPERATION CHARACTERISTICS OF VET
Cooling towers
Spray canals or ponds
Volume of circulating water
in the system per unit rime
Tower features (height, diameter,
and characteristics of drift
eliminators for natural-draft
tower; height, cell diameter,
characteristics of drift elimi-
nators, and number of cells for
mechanical draft tower)
Drift flux and droplets size
distribution
Exit temperature
Efflux velocity
Volume of circulating witer in
the system per unit time
Area, spray nodules spacing, and
spny nozzle characteristics
(droplets size and spray pattern)
Drift flux anJ droplets size
distribution
Spray nozzles exit temperature
Spray nozzles exit velocity
84
-------
00
Ul
TABLE 4-6
SUMMARY OF DRIFT RATE AMD DROPLET SIZE DISTRIBUTION MEASUREMENT TECHNIQUES (I)
Method
Sensitive piper
Coated tilde*
Imp action
Cyclone Separator
tight Scattering
High-Volume
Sampling
Chealcal Balance
CalorlBetry
Measurement Capacity
Drift Droplet Size
Rate Distribution
yea yes
yea yea
yea np
yea no
yea yea
yea no
yea no
yee no
Field Application
good
fair
good
good
fair
good
fair
fair
Calibration
fair
fair
good
good
good
good
none
good
Accuracy Maintenance
Interpretation Result
Drift Rate Particle Site
fair fair none
fair fair none
good - avail
good - SBall
good vary good aoderate
fair fair tm«ll
fair - none
fair - small
Coat
low
low
fair
high
high
low
fair
fair
-------
TABLE 4-7
WINDROSE DATA FOR DEPOSITION AT ATLANTIC CITY (5)
Unit Operation: On During Entire Test Period
Station Number 12394856
Wind Direction NNE
Average Deposition 823.7 116.4 453.5 66.3 63.0 135.4 36.1 96.4
Entries 3. 2. 3. 3. 1. 2. 2. 1.
Wind Direction NE
Average Deposition 0.0 0.0 0.0 1810.2 0.0 0.0 0.0 0.0
Entries 0. 0. 0. 1. 0. 0. 0. 0.
Wind Direction ENE
Average Deposition 1336.0 428.7 563.6 481.5 215.3 623.1 0.0 0.0
Entries 1. 1. 1. 1. 1- 1- 1- *•
» Wind Direction E
Average Deposition 1626.9 394.5 311.7 0.0 883.6 677.1 1215.0 716.2
Entries 1. 1. 1. 0. 1. 1. 1. 1.
Wind Direction ESE
Average Deposition 1098.6 213.1 383.5 386.2 177.0 124.0 3837.5 0.0
Entries 7. 5. 7. 7. 4. 9. 4. 0.
Wind Direction SE
Average Deposition 979.3 389.4 581.9 60.0 115.9 91.3 369.5 69.4
Entries 8. 6. 2. 3. 8. 7. 3. 9.
Wind Direction SSE
Average Deposition 2186.6 1889.4 1222.4 116.4 356.9 115.8 324.0 77.4
Entries 9. 10. 12. 11. 8. 6. 13. 8.
Wind Direction S
Average Deposition 1943.8 861.8 435.3 441.4 155.2 308.7 42.3 71.0
Entries 8. 8. 6. 6. 8. 5. 3. 8.
-------
TABLE 4-7 (cont'd)
Station Number 12394856
Wind Direction SSW
Average Deposition 412.5 695.8 182.2 48.3 17.5 153.5 80.2 26.6
Entries 3. 4. 4. 4. 3. 2. 2. 3.
Wind Direction SW
Average Deposition 594.6 123.9 83.9 89.5 53.3 73.6 5844.5 77.3
Entries
00
VJ
-------
00
TABLE 4-8
WINDROSE DATA FOR DEPOSITION AT ATLANTIC CITY (5)
Station Number
Wind Direction WSW
Average Deposition
Entries
Wind Direction W
Average Deposition
Entries
Wind Direction WWW
Average Deposition
Entries
Wind Direction NW
Average Deposition
Entries
Wind Direction NNW
Average Deposition
Entries
1
498.6
9.
1077.5
2.
186.2
2.
285.5
6.
510.8
2.
2
230.9
10.
38.3
2.
23.0
2.
67.1
6.
103.3
2.
3
45.1
9.
40.4
2.
374.8
4.
80.2
7.
51.9
2.
9
42.8
9.
54.7
2.
56.0
5.
34.9
4.
208.6
3.
4
51.5
5.
553.6
2.
73.2
7.
32.5
2.
115.4
3.
8
41.7
5.
100.3
3.
40.0
6.
20.9
2.
161.2
4.
5
62.9
4.
304.8
1.
660.0
8.
257.4
4.
27.7
2.
6
25.7
3.
40.7
2.
23.4
7.
151.9
9.
36.8
5.
Wind Direction N
Average Deposition 2420.0 198.2 71.2 75.2 60.7 0.0 0.0 0.0
Entries 2. 1. 1. 1. 1. 0. 0. 0.
Cumulative Average 1126.2 459.9 433.9 183.6 165.9 134.4 729.4 81.4
Total Entries 65. 62. 62. 61. 57. 56. 48. 60.
-------
TABLE 4-9
Distance
(m)
240
610
620
710
870
Distance
260
610
620
740
1040
240
300
380
460
520
590
770
990
990
990
# drops/tn^-hr
6/17
Direction
213
221
211
213
210
6/13
AM
Direction
222
249
212
208
203
170
149
Totals
183
151
Totals
182
146
Totals
182
165
Totals
182
167
Totals
OBS
1646
605
288
1119
394
OBS
4289
4745
6487
3704
4834
3601
808
921
6226
219
89
-------
TABLE 4-9 (cont'd)
6/19
Distance Direction OBS
(m)
240 145 4200
370 178 3390
440 173 3113
440 . 183 6714
460 164 4419
6/22
Distance Direction OBS
(m)
240
390
570
770
Distance
(m)
180
180
320
380
490
540
620
188
188
192
183
6/23
Direction
230
174
Totals
90
174
219
Totals
173
214
3711
2339
5121
2393
OBS
10803
3125
120
Totals 37
90
-------
TABLE 4-9 (cont'd)
Distance
On)
270
320
630
630
650
220
90
205
218
212
OBS
2597
10822
2583
715
167
91
-------
TABLE 4-10
COMPARISON OF TYPICAL DRIFT
DROPLET MEASUREMENTS
Traverse
Number
15-2
15-3
15-4
15-5
15-6
15-7
15-8
15-10
15-11
15-12
15-13
MMD (Jtai)
PMS
80
80
40
280
200
80
140
100
40
80
280
Film
329
371
315
329
343
287
399
231
231
343
273
92
-------
TABLE 4-11
COOLING TOWER COMPOSITE DRIFT MASS EMISSION PARAMETERS (9)
v£>
CO
d(center)
Ad
'ptn)
20
20
30
30
40
50
50
50
50
50
50
50
50
50
Composite Drift Flux
(ug/m2-s)
590
881
1,205
958
987
867
600
378
287
240
219
185
171
168
AXj/Ad
(ug/m3-ym)
29.5
44.1
40.2
31.9
24.7
17.3
12.0
7.6
5.7
4.8
4.4
3.7
3.4
3.4
Composite Drift Mass
Emission Rate, ADi
(gg/s)
2.78E 05
4.14E 05
5.61E 05
4.40E 05
4.46E 05
3.82E 05
2.57E 05
1.58E 05
1.16E 05
9.41E 04
8.37E 04
6.89E 04
6.12E 04
5.83E 04
20
40
65
95
130
175
225
275
325
375
425
475
525
575
Note: 2.78E 05 means 2.78 x 10s
TOTAL COMPOSITE DRIFT FLUX
TOTAL COMPOSITE DRIFT MASS EMISSION RATE
MASS MEDIAN DIAMETER of the composite drift mass
density distribution, AX-j/Ad
COMPOSITE TOWER DRIFT FRACTION
(based on the design flow rate of 1260 kg/s)
= 7,736 ug/m2'S
= .3.42 gm/s
= 120 urn
= 0.00027%
-------
TABLE 4-12
SATES OF SODIUM AND MAGNESIUM MASS EMISSION
FROM THE TURKEY POINT POOLING TOWER (9)
Fan Stack Exit Diameter Traverse
Weighted Average Sodium
Basin Water Concentra-
tion per Traverse, mg/1
Weighted Average
Magnesium Basin Water
Concentration per
Traverse, mg/1
Rate of Sodium Emission,
pSfsec
Rate of Magnesium
Emission, /ig/sec
Rate of Sodium
Circulating as Solute
In the Basin Water,
jrg/sec
Rate of Magnesium
Circulating as Solute
in the Basin Water,
SW-NE1
7,390
845
67,000
7.680
SW-NE 2
11,430
1,165
143.630
14,350
SW-NE 3
10,720
1,220
123.150
13,880
NW-SE 1
9,545
1,005
72,860
8.120
NW-SE 2
11,540
1.170
89,550
9.370
Sodium Mass Emission
Fraction, %
Magnesium Mass Emission
Fraction, %
Satt Mass Emission
Fraction, %
Adjusted Rate of Sodium
Emission, /»g/sec
Adjusted Rate of
Magnesium Emission,
jig/*«c
8.86 X 10» 1.37 x 10t° 1.04 X 10" 1.14 X 10w 1.38 X
1.01 X 10» 1.40 X 10» 1.18 X 10» 1.20 X 10» 1.40 X 10*
0.00076 0.00105 0.00118 0.00064 0.00065
0.00076 0.00103 0.00118 0.00068 0.00067
0.00076 0.00104 0.00118 0.00066 0.00066
88.200
9.600
122,100
0.00118
111.700
12,000
0.00066
74,200
8.540
75,500
8,430
13,000
The adjusted rates of sodium and magnesium emission belong to sodium and magnesium basin
water concentrations of 9720 mg/1 and 1055 mg/1, respectively, which are the averag* values
for the test duration.
94
-------
TABLE 4-13
REPRESENTATIVE DRIFT EMISSION
DATA OF THE TURKEY POINT
COOLING TOWER (9)
Oroplet Diameter
Intervals
d'
«m
10
30
50
80
110
150
200
250
300
350
400
450
500
550
600
d"
um
30
50
80
110
150
200
250
300
350
400
450
500
550
600
700
*i.d
«m
20
20
30
' 30
40
50
50
50
50
50
50
50
50
50
100
Drift Emission in
Percent of
Total
7.80
11.18
14.96
11.68
11.85
10.20
6.56
4.23
3.11
2.53
2.22
1.82
1.61
1.53
0.33
700 2250 1550
8.39
Total Drift Emission
Rate:
Mass Median
Diameter
Water Flew Rate:
Drift Fraction:
Sodium Emission
Rate:
Magnesium
Emission Rate:
3.979 g/sec (2.584 g/sec)
125 ,tm
1154 kg/sec
O.OC034% (0.00056%)
94,340
ug/sec
(21,600
ug/sec)
10.310 (2080
ug/sec ug/sec)
Corresponding Bssin Water Concentrations:
Sodium: 9720 rrg/1. Magnesium: 1055 mg/1
Salt Mass Emission
Fraction: 0.00084% (0.001%)
95
-------
TABLE 4-14
EFFECT OF COOLING TOWER ON AMBIENT SALT CONCENTRATION
vo
Sta
3
4
5
6
7
8
9
10
11
3
4
5
6
7
8
9
10
11
21
53
54
59
51
63
50
3
44
21
41
43
43
37
54
40
6
40
A. Summary Statistics for Down Wind
Concentration for Cooling
Minus Background
Tower
Confidence That
Mean
mgr/nr
-0.3101E 01
0.4648E 01
-0.3211E 01
-0.2417E 01
0.2553E 01
-0.1978E 01
-0.1236E 01
-0.4548E 01
0.7658E 00
B. Summary
Std
Dev
ugr/nr
0.3590E 01
0.5593E 01
0.4238E 01
0.3095E 01
0.3611E 01
0.3975E 01
0.3349E 01
0.1170E 01
0.4698E 01
Max
Value
ugr/ar
0.4552E 01
0.3181E 02
0.1637E 02
0.5779E 01
0.1170E 02
0.1022E 02
0.1024E 02
-0.2900E 01
0.1560E 02
Statistics for Down Wind
Concentration
-0.1451E 00
0.1186E 02
0.7576E 00
-0.2935E 01
0.3349E 01
-0.2797E 01
-0.1072E 01
-0.5033E 01
0.3483E 01
0.7726E 01
0.1997E 02
0.6408E 01
0.3166E 01
0.2953E 01
0.4178E 01
0.2370E 01
0.1245E 01
0.9393E 01
Min Increase is Less
Value
ugr/m^
-0.1 USE 02
-0.1520E 01
-0.6419E 01
-0.7797E 01
-0.6590E 01
-0.8790E 01
-0.7463E 01
-0.5504E 01
-0.6409E 01
Minus Background
Than Std Dev
(to
97
57
84
96
61
93
92
_.
85
for Spray Modules
0.1799E 02
0.1036E 03
0.3179E 02
0.7399E 01
0.1342E 02
0.1336E 02
0.8539E 01
-0.3003E 01
0.4857E 02
-0.8405E 01
-0.7852E 01
-0.5484E 01
-0.1138E 02
-0.1011E 01
-0.1173E 02
-0.4251E 01
-0.6554E 01
-0.6938E 01
84
66
81
97
(44)
95
93
__
73
-------
TABLE 4-15
VEGETATTON ACUTELY AFFECTED BY SALT SPRAY* OR)
Beach plum
Bermuda grass
Black gum
Blackjack oak
Camphor weed
Cinnamon fern
Cyperus
False heather
Flowering dogwood
Golden rain tree
Horseweed
Marsh fern
Marsh St. John's
wort
Red maple
Rose
Rose mallow
Royal fern
Sassafras
Scrub oak
Smilax
Spannish oak
Stagger-bush
Sumac
Trumpet creeper
Virginia creeper
Wild bean
Wild black cherry
*Plants showing acute foliar injury after 3 to 15 seawater spray treatments.
-------
TABLE 4-16
PLANTS ACUTELY AFFECTED BY SALINITY
Sensitive to Salt Spray*
Beach plum
Bermuda grass
Black gum
Blackjack oak
Camphor weed
Cinnamon fern
Cyperus
False heather
Flowering dogwood
Golden rain tree
Horseweed
Marsh fern
Marsh St. John's wort
Rose
Rose mallow
Royal fern
Sassafras
Scrub oak
Smilax
Spanish oak
Staggerbush
Sumac
Trumpet creeper
Virginia creeper
Wild bean
Wild black cherry
Sensitive to Saline Soil*
Alfalfa
Algerian ivy
Arborvitae
Beans
Bell pepper
Bottle brush
Boxwood
Broadbean
Burford holly
Cabbage
Carrots
Clovers
Corn
Dodonea
Flax
Heavenly bamboo
Hibiscus
Juniper
Lantana
Lettuce
Meadow foxtail
Oleander
Onion
Orchardgrass
Pineapple guava
Fittosporum
Potato
Pyracantha
Rose
Silverberry
Star jasmine
Sweetpotato
Texas privit
Viburnum
Xylosma
*Plants showing acute foliar injury after 3-15 sea water spray
treatments.
+Plants showing more than a 107. relative yield reduction when
growing in less than 4 m mhos/cm (ECe).
98
-------
TABLE 4-17
RESPONSE OF VARIOUS ORNAMENTAL PLANTS TO SEAWATER SPRAY* (151
Resistant"*
Pachysandra terminalis
Ilex opaca
Ilex glabra
Aesculus parviflora
Enkianthus campanulatus
Prunus laurocerasus
Cotoneaster salisifolia
Ligustrum vulgare nanum
Ligustrum obtusifolium regelianum
Myrica pensylvanica
Abelia x grandiflora
Taxus bacatta repandens
Taxus media 'Hicksi1
Larix decidua
Osmanthus ilicifolia
Buxus sempervirens
Hedera helix
Euonymus alatus
Viburnum rhytidophyllum
Cedrus atlantica glauca
Pinus strobus
Pinus sylvestris
Pinus thunbergi
Pinus nigra
Juniperus horizontalis plumose
Juniperus chinensis pfitzeriana
Elaeagnus angustifolia
Morus alba
Sensitive^
Franklinia alatamaha
Clethra alnifolia
Stewartia ovata grandiflora
Cotoneaster horizontalis
Pyracantha coccinia
Forsythia x intermedia
Magnolia virginiana
Ilex verticallata
Crataegus phaenopyrum
Albizia julibrissin rosea
Ailanthus altissima
Vaccinium pensylvanica angustifolium
Cornus mas
Cornus kousa
Syringe vulgaris
Rhus aromatica
Acer palmatum atropurpureum
Betula pendula
Ginko biloba
Sorbus aucuparia
Gleditsia triacanthos
Cercis canadensis
Very Sensitive§
Cornus florida
Cotoneaster adpressa praecox
Rhus glabra
Platanus acerfolia pyramidalis
Vaccinium corymbosum
Campsis radicans
Koelreuteria paniculata
Malus sp.
*Plants growing at Horticulture Farm 1, Rutgers University, sprayed with
undiluted seawater on three consecutive days.
+No damage.
^20 to 40% of the leaf injured.
§0ver 40% of the leaf injured.
99
-------
TABLE 4-18
ENVIRONMENTAL CONDITIONS PRODUCING VISIBLE SALT INJURY TO
NATIVE VEGETATION NEAR FORKED RIVER. N.J. (15)
§
Distance
From Shore
(meters)
50
650
Ambient Airborne
Salt Concentration
(ug/m3)
382
62
Meteorological
Conditions
Deciduous Vegetation
Damage
Persistent onshore Leaf scorch & twig
winds-15 mph with- dieback up to 375 m
out rain for several from shore
days
Same
No visible damage
Note: The symbol "ug" represents micrograms.
-------
TABLE 4-19
SUMMARY OF SODIUM AND CHLORIDE SEASONAL MEANS AND RANGES FOR ALL
SPECIES AM) SITES. DATA ARE EXPRESSED AS uJz ON A DRY-WEICaTT BASIS
SAMPLING PERIOD EXTENDED FROM MAY 1974 TO APRIL 1975
Na+ Load
Cl~ Load
Species and Site
Virginia pine, site 1, PV-1
Virginia pine, site 2, PV-2
Virginia pine, site 3, PV-3
Virginia pine, site 4, PV-4
Virginia pine, site 5, PV-5
Virginia pine, site 6, PV-6
Black locust, site 1, RP-1
Black locust, site 2, RP-2
Black locust, site 3, RP-3
Sassafras, site 1, SA-1
Sassafras, site 2, SA-2
Sassafras, site 3, SA-3
Dogwood, site 1, CF-1
Mean
51.1
73.7
101.6
73,6
70.7
464.3
99.5
98.0
127.3
86.6
87.6
77.0
54.4
Range
24.1-98.8
43.5-121.6
47.2-176.8
33.1-119.8
38.9-97.9
293.4-631.2
44.8-216.1
45.0-197.9
44.7-291.0
34.5-194.6
43.1-161.5
36.9-154.9
41.8-70.4
Mean
346.8
405.3
409.7
431.0
393.7
1397.7
594.3
434.1
1269.4
157.6
183.7
290.9
2046.3
Range
291.7-434.3
299.1-506.2
326.7-544.2
270.5-718.6
278.6-497.7
506.2-2765.0
298.9-1218.1
275.7-813.3
565.5-2606.7
106.8-181.8
142.3-245.0
151.7-614.6
570.8-3817.2
-------
TABLE 4-20
SUMMARY OF SODIUM AND CHLORIDE CONCENTRATIONS ON
A DRY -WEIGHT BASTS IN CERTAIN PLANTS (221
Na+. ppm
Cl". ppm
Normal*
Tops
Corn
Buckwheat
Sunflower
Oats
Sweet clover
Tobacco
Pea
Saltwort
Broad bean
White mustard
Saltbush
Leaves
Peach
Snap bean
Grape
Tomato
Apple
127
368
392
460
483
575
665
1,790
1,910
3,220
11,400
5,000
200
200 to 600
5,000
China aster
Azalea
Snap bean
Cherry
Sweet corn
Grape
Lettuce
Peach
Poinsettia
Potato
Toxic1
400 to 7,000
Normal*
46,000
3,000 to 5,000
3,000 to 4,000
3,000 to 5,000
50,000
20,000
Toxic+
2,100
78,000
14,000 to 30,000
40,000 .
15,000
10,000 to 15,000
47,000
Intermediate concentration; not low, high, or toxic.
^Growth reduction or toxicity symptoms.
102
-------
TABLE 4-21
EXTENT QF INJURY TO PLANTS EXPOSED TO SEAWATER MIST
FOR VARIOUS LENGTHS OF TIME (15)
Species
Robinia pseudo-acacia
Pinus thunbergi
Pinus strobus
Geranium sp.
Contender snap bean
Hours Under
Mist
0
2
4
6
8
10
12
0
24
0
24
0
24
0
24
Extent of Injury
No injury
Slight tip and margin necrosis
Moderate tip and margin necrosis
Extensive necrosis
Partial defoliation
Complete defoliation
Complete defoliation
No injury
No injury
No injury
No injury
No injury
Complete defoliation
No injury
Extensive necrosis
103
-------
TABLE 4-22
EFFECTS ftP SAT-T -SPRAY APPLICATIONS CM THE NUTRIENT
CONTENTS AND METABOLIC INDEX IN SOYBEAN LEAVES* (19)
Salt (NaCl)
Elements , 7.
treatments ,
kg ha"1 week"1
0
1.82
3.64
7.28
14.56
t significant
Ca
1.30
1.05
1.49
1.35
1.60
1.36
N.S.
M&
0.50
0.37
0.56
0.53
0.67
0.58
0.18
K
1.90
1.70
2.10
2.00
2.20
2.00
N.S.
*
0.33
0.26
0.36
0.34
0.42
0.34
N.S.
£1
0.069
0.260
0.503
0.689
1.310
0.567
0.114
Na
0.065
0.078
0.114
0.142
0.211
0.122
0.091
Metabolic
Indexg (1)
32.10
9.88
7.23
5.08
3.21
11.6
9.54
Mean
difference (0.05)
Coefficient of
variation, %
19.4
22.5
19.1
20.4
13.0
48.8
53.4
^Sampled from entire plant canopy after last treatment.
+Applied as concentrated sodium chloride solution spray on a weekly basis for 8 weeks.
To convert to pounds per acre, divide by 1.1.
^Average of four replications, expressed as percentage dry weight. To convert to parts per
million, multiply by
§Determined by dividing (Ca + Mg + K + P) by (Cl + Na).
yAl.S. indicates insignificant difference between values.
-------
TABLE 4-23
EFFECTS OF SALT-SPRAY APPLICATIONS ON THE NUTRIENT
CONTENTS AND METABOLIC INDEX IN CORN LEAVES* (19)
o
ui
Salt (NaCl)
Elements,^ 7,
treatment,"1"
ks ha'1, week"1 Ca Mg K
0
1.82
3.64
7.28
14.56
t significant
0.43
0.44
0.36
0.30
0.36
0,38
0.10
0.28
0.29
0.24
0.18
0.22
0.24
N.S.
3.18
3.20
2.83
1.90
2.23
2.66
0.89
P
0.32
0.34
0.30
0.22
0.29
0,29
N.S.
Cl
0.312
0.364
0.471
0.804
1.030
0.596
0.094
Na
0.061
0.095
0.110
0.211
0.313
0.158
0.117
Metabolic
Index§ (1)
11.7
9.3
6.0
2.6
2.2
6.5
2.4
Mean.
difference (0.05)
Coefficient of
variation, 7,
16.7
21.6
21.7
21.1
10.2
48.4
23.8
*S amp led from point of ear attachment after last spray treatment.
^Applied as concentrated sodium chloride solution spray on a weekly basis for 8 weeks.
To convert to pounds per acre, divide by 1.1.
^Average of four replications, expressed as percentage of dry weight. To convert to parts
per million, multiply by
Determined by dividing (Ca + Mg + K + P) by (Cl + Na).
#N.S. indicates insignificant difference between values.
-------
TABLE 4-24
MEANS* OF NUTRIENT CONTENTS AND METABOLIC INDE%
FOR SOYBEANS AND CORN FROM THE CHALK POINT
POOLING TOWER MONITORING PROGRAM - 1973+ (19)
Radius,
Mean
difference (0.05)
Coefficient of
variation, T>
Elements, §
19.3
7.2
16.9
12.7
7.5
17.1
Metabolic
on
Ca
Mg
K
I
£a
SI
Index
Soybeans
1.6
4.8
9.6
lificant
1.22
1.56
1.53
1.44
N.S.
0.67
0.55
0.57
0.60
0.07 ..
2.17
1.90
2.00
1.99
N.S.
0.28
0.28
0.29
0.28
N.S.
0.074
0.081
0.085
0.080
N.S.
0.073
0.100
0.081
0.085
N.S.
29.9
23.5
26.9
26.8
N.S.
11.1
Mean
difference (0.05)
Coefficient of
variation, %
Corn
1.6
4.8
9.6
tlficant
0.45
0.48
0.48
0.47
N.S.
0.34
0.27
0.30
0.30
N.S.
2.40
2.30
2.20
2.26
N.S.
0.28
0.28
0.27
0.28
N.S.
0.072
0.071
0.077
0.074
N.S.
0.180
0.224
0.198
0.200
N.S.
14.1
11.2
11.8
12.4
N.S.
17.5
13.6
10.5
10.9
13.2
14.9
11.6
*Each data entry represents the mean of three replications at four sites within each
radius (Figures 3 and 4).
+The data for 1973 represent the baseline information for the Chalk Point Cooling Tower
Monitoring Program.
4The 1.6, 4.8, and 9.6 km equal 1, 3, and 6 miles, respectively.
STissue contents represented on a dry weight basis from samples taken at point of ear
attachment for corn and the entire canopy of soybean leaves at the time of flowering.
*N.S. indicates insignificant difference between values.
106
-------
TABLE 4-25
RESPONSE OF NINE DECIDUOUS WOODY SPECIES
OF PLANTS TO SALINE AEROSOLS
Witch-hazel
Golden rain tree
Red maple
Silk tree
Black locust
Chestnut oak
Forsythia
Flowering dogwood
White ash
Total
2.4 4.8 12 24
0
6
0
2
0
3
0
2
1 3 13 33
24 17 11 5
4 6 15 17
21 13 7 0
(24)*
dose (micro grams
48 72
0 1
8 6
0
2
0
1
1
9
5
5
42
1
18
0
96
3
3
1
0
1
0
6
1
10
0
43
0
19
0
Cl'/cm2)
120 144
0
S
0
1
4 7
0 0
2 3
0 0
3
0
15 18
0 0
12
0
44
0
21
0
192
0
4
3
0
8
0
4
0
4
0
13
0
46
0
22
0
264
1
3
5
0
11
0
6
0
19
0
48
0
23
0
* Exposure period - 4 hours, 95% aerosol salt particles between 50 and 150 microns in
diameter, relative humidity - 85% during and after exposure.
Note: For each species: the upper number is equal to the number of
plants injured by a dose less than or equal to the value given;
the lower number is equal to the number of plants uninjured by
a dose greater than or equal to the value given.
107
-------
o
CO
TABLE 4-26
RESPONSE OF TWO CONIFEROUS SPECIES TO
SALINE AEROSOLS (24)*
12
0
36
0
0
65
40
0
22
55
48
0
43
30
48
0
62
1
60
0
72
0
68
0
92
0
102
0
Total dose (ug Cl cm"2)
Species of Conifer 7.2 14.4 36_ 72 120 180 216 288 576
Eastera white pine
Canadian hemlock
*Plants given single 6 hour exposure at 85% KH to saline particles,
Note: For each species; the upper number is equal to the number of
plants injured by a dose less than or equal to the value given;
the lower number is equal to the number of plants uninjured by
a dose greater than or equal to the value given.
-------
TABLE 4-27
RESPONSE OF TWO DECIDUOUS WOODY SPECIES
EXPOSED AT 85% RELATIVE HUMIDITY TO A SALINE
AEROSOL* (241
Duration of Exposure (hours)
Species of Plant 14 li 1Z IS 20.2 25.4
White flowering dogwood o 4 4 9 14 ^5
15 11 5 0 0 0
White ash o 10 15 20 25 26
40000 0
A mass mean diameter of 1.5 microns at a concentration of 1500-1700
micrograms Cl m~J. For each species: the upper number indicates the
number of plants injured by an exposure less than or equal to the
value given; the lower number indicates the number of plants without
injury after an exposure greater than or equal to the value given.
-------
TABLE 4-28
SHOWS PERCENT OF INJURED BUSH BEAN WITH RELATION TO
TRIFOLIATE SODIUM AND CHLORIDE ACCUMULATION IN PPM
Plant
Salt
Concentration
_«5
Percent
Trifoliate Injury
Sodium Chloride
One week
Three weeks
Five weeks
5
25
75
5
25
75
5
25
75
0
0.3
18.7*
0.7
1.7
17.6*
3.6
5.9
24.0*
84.0
112.0
889.0
204.0
496.0
5820.0
102.0
914.0
12143.0
1148.0
957.0
8630.0
2014.0
6717.0
32886.0
2789.0
6254.0
40700.0
* The injury column value within a particular weekly group is significantly
different at 1% level of probability. Post-exposure conditions varied
for the three ages of plants do not directly compare the three ages of
plants past the termination of exposure.
110
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TABLE 4-29
CASE STUDIES COMPARISON OF ENVIRONMENTAL
DRIFT EFFECTS FOR POWER GENERATING PLANTS
Plant
Hanfoxd No.
Washington
2 NPP,
Proposed
(Freshwater)
Turkey Point,
Florida
Pre-operational
(salt water)
Forked River,
Mew Jersey
Proposed
(Brackish)
Indian Point,
New York
Pre-operational
(Brackish)
Drift Data References
During operation of the plant, cooling 53
tower will cause slight increases in
dispersion of small quantities of
chemicals in drift; chemical deposi-
tion iS less than the acceptable levels
in irrigation practices.
DMS; average difference between measured 10, 27
concentration with cooling tower operat-
ing and expected background concentration
was 2 x 10~3 ug/m2 +4.8 (s); highest
monthly salt aerosol level for the mechan-
ical draft tower was 5 ug/m3; operation of
cooling tower did not increase background
salt concentration by a measurable amount
at any sampling station; no effects attri-
butable to salt aerosol emissions from test
cooling devices detected on indigenous plants
and soil.
DMS; short term exposures (several hours) 14, 15
to about 100 ug/m3 produce foliar injury,
while those with 60 ug/m3 would not; long-
term mean of 10 ug/m3 aerosol salt might
influence distribution and abundance of
plants.
DMS; aerosol salt background levels (11 24, 52
months) X • 1 ug/m3, range 0-6.15 ug/m3.
On-site maximum deposition • 79 kg/ha or
71 Ib/acre; maximum short-term exposure
that will not produce adverse effects on
most susceptible species of plants under
condition most conducive to injury is
exposure « total deposition of 2 ug Cl/cm2
in 6 hours; 857. RH and absence of precipi-
tation during and after simulated saline
mist.
Note: The symbol "ug" represents micrograms.
-------
TABLE 4-29 (cont'd)
Plant
Chalk Point,
Maryland
Status
Pre-operational
(Brackish)
Jack Watson,
Alabama
Southern California
Edison, California
B. L. England,
New Jersey
Po s tope ra t iona1
(Brackish)
Postoperational,
since 1970
(Freshwater)
Pos toperat ional
(Brackish)
Chevron Oil Co.
F. H. Robinson,
Texas
Exxon,
New Jersey
Postoperational,
since 1957
(Saltwater)
Postoperational
(Brackish)
Pos tope rational,
Since 1968
Drift Data
MS; partial operation of cooling
towers from May-October, 1975, had no
discernible effect on local vege-
tation or on tobacco, corn and soy-
beans.
No data.
No observed effects.
QMS; long-term average and deposi-
tion levels higher when plant
operating than when not; drop
deposited 1000 feet downwind;
levels: 2-8 ug fs? (natural
background), 8-28 ug/m3 (induced).
Drift effects observed 100-150 m
from cooling tower; trees 300 m
west of cooling tower were ok.
DMS; mathematical model of deposi-
tion predicted 15 Ibs/acre-month,
1500 feet from cooling tower.
Drift caused metal corrosion 150-
200 m downwind; no visible effects
on vegetation.
References
21, 16, 17
20, 23
18
18
18
18
18
18
Note; The symbol "ug" represents micrograms.
-------
TABLE 4-29 (cont'd)
Flant Status Drift Data References
Fleetwood, England Postoperational No detrimental effects observed; trees ig
(17 years) and shrubs 500 m downwind healthy.
(Saltwater)
Three Mile Island Postoperational No measurable effects on vegetation 29
Nuclear Station, (Freshwater) from cooling tower drift deposition
Pennsylvania on natural vegetation observed; no
effects onbird population.
Cayuga Lake, New York Pre-operational No environmental impact expected; 73
(Freshwater) maximum on-site deposition estimated
at 260 Kg/ha-yr, within 0.4 Km of
the cooling towers.
I. DMS = Drift monitoring studies being conducted on pre- and post-operational level.
-------
TABLE 4-30
FAUNAL SALT TOLERANCES
Species
Ringneck pheasant
Cottontail rabbit
Bobwhite quail
Chicks
Chicks
Turkey poultry
Ducklings
Chicks
Baby Chicks
Adult pigs
Bufo viridla
Bufo melanosttctus
(8% day old tadpoles)
Savannah sparrows
White-footed mouse
Red-backed mole
Level Which Produces Some
Observable Effect
Dose
3 grams
1% NaCl solution
7000 ppm
10000-12000 ppm
4000 ppm
10000 ppm
5000-9000 ppa NaCl in
Solution
5-107. NaCl in solution
57. NaCl ingested with feed
but water supply
restricted
75% seawater (2.347. NaCl
solution)
.75% solution
Mature of Response
Mortality
Weight loss
Decreased growth; 14-47%
Mortality
75-1007. Mortality
Increased Mortality
437. Mortality
Distress
Heavy mortality within
one week
Salt poisoning
Tolerates
Unaffected
.55 molar NaCl-fed 10 days No loss in body weight
.3 M NaCl for 10 days Tolerates drinking water
.1 M NaCl solution Tolerates
References
63
64
65
65 .
65
65
66
67
68
69
70
71
72
72
-------
TABLE 4-31
BIRD IMPACTIONS RECORDED AT THREE MILE ISLAND NUCLEAR STATION COOLING TOWERS
BY MONTH AND TOWER. JULY 27.
Preoperation
July 27-31, 1973
August
September
October
November
December
January, 1974
February
March
April
May
June 1-4
Subtotal Preoperation
Operation
June 5-30, 1974
September
October
November
March, 1975
April
May
Subtotal Operation
Total
Days
Monitored
3
10
11
31
30
20
8
7
31
30
31
4
216
26
30
31
30
31
29
31
208
424
1973 THROUGH MAY 31. 1975 f29^
Tower
1
0
0
0
5
0
0
0
0
0
1
0
0
6
0
0
2
0
0
0
0
2
8
2
0
0
0
0
0
0
0
0
0
1
0
0
1
0
0
5
0
0
0
0
5
6
3
0
0
2
9
0
0
0
1
1
1
0
_0
14
0
0
6
1
0
1
_0
8
22
4
0
0
8
5
2
0
0
0
0
0
1
_0
16
0
0
13
0
0
1
_0
14
30
Total
0
0
10
19
2
0
0
1
1
3
1
_0
37
0
0
26
1
0
2
_0
29
66
115
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SECTION 5
WEATHER MODIFICATION
5.1 INTRODUCTION
Weather modification is becoming an important topic in environmental assess-
ment of the effects of evaporative cooling towers. One of the most easily
observed cooling tower-related phenomena is fogging-icing and the most common
inquiry at environmental hearings concerns its frequency and intensity.
Other weather conditions long suspected to be caused by cooling towers in-
clude cloud enhancement and precipitation. Because of the naturally occur-
ring cyclic nature of climate, enhancement of precipitation and of clouds
resulting from cooling tower (CT) operation is not easily analyzed. Cloud
enhancement as reported in much of the literature, seems insignificant.
The processes involved in producing weather modification directly from wet
cooling towers requires an understanding of cloud physics, including evapora-
tion-condensation, nucleation, and thermodynamics. Such topics will not be
considered in great detail in this report, since only a general description
is necessary to relate the impact of co«ling towers on weather modification.
Numerical models which predict weather modification will be briefly reported
because the models used to predict fogging-icing frequency, plume rise, and
plume length are particularly numerous and have great disparity in results.
Only in papers since 1974 has any serious comparison of numerical models
been made with observed phenomena. This comparison has been restricted to
plume rise, plume length and salt deposition. Although models exist for pre-
cipitation and cloud enhancement, their predictions have not been sufficient-
ly verified by observed data.
5.2 FOGGING-ICING FREQUENCY AND DURATION
An evaluation of the fogging-icing frequency includes: induced fogging which
results from the contribution of water vapor at distances beyond the visible
plume and fogging which results from actual visible plume intersection with
the ground. With regard to a direct visible plume and ground intersection,
the downwash in the wake of a cooling tower is a function of tower design
and height. Better aerodynamic cooling tower design and enhanced plume buoy-
ancy will decrease the fogging-icing frequency and duration.
Tower design can be categorized into four basic types: mechanical draft,
natural draft, wet/dry and fan-assisted natural draft. Field studies of the
116
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fan-assisted or wet/dry towers have not been made, so that these will not be
considered.
Since there does not appear to be any measurable downwind contribution of
water vapor from cooling towers, it is difficult to attribute induced down-
wind fogging directly to cooling towers (W. Dunn, personal communication).
Kramer et a^. (1) studied the environmental problems of natural draft cooling
towers (NDCT) at the Amos Plant in West Virginia and found no evidence of
induced fogging.
The question of fogging resulting from a visible plume intersecting the
ground remains unclear. For natural draft cooling towers (NDCT), the consen-
sus is that no fogging will occur unless there is a sharp rise in elevation
and conducive meteorological conditions exist. Several studies support this
contention (1,2,3). Slawson _et §1^(2) did not note ground fog from NDCT's
in a five-year period of observation at the Paradise Steam Plant, and Moore
(3) at the CEGB did not report any ground fog from NDCT's in England.
Spurr (4) in a study of the region surrounding Ratcliffe found no meaningful
statistical increase of fogging incidence (Table 5-1). In fact, a decrease
was noticeable over a period of years (Figure 5-1). Lack of ground fog with
NDCT's was attributed to tower design because the tower was simply too high
to allow the visible plume to intersect the ground even with downwash effects
under high wind conditions, stable lapse rates of temperature, and high hu-
midity. In extreme cases, downwash appeared to reduce plume height to 50%
of the tower height. However, buoyant effects soon raised the cooling tower
plume to its equilibrium height within several kilometers.
Lack of ground fog cannot be used to characterize mechanical draft cooling
towers (MDCT). Hanna (5) noted that downwash occurred 50% of the time with
the MDCT's while NDCT's had fewer problems with downwash. However, plumes
that do touch the ground will rise again within 250 m because of their buoy-
ancy (5).
In an environmental report for Indian Point, a round MDCT design was recom-
mended because of superior aerodynamic characteristics (6). However, only
wind tunnel studies have been used to evaluate the round tower design so that
field characteristics have not been completely determined (7). Downwash is
greatly enhanced by the rectangular MDCT design, and since the MDCT height is
not sufficient to counteract downwash, fog near the tower is expected to be
adversely frequent with winds greater than 2 m/sec, high relative humidity
(approximately 95%) and stable temperature lapse rates. Exit velocity,
buoyant effects of plume and tower heights were not sufficient to counteract
downwash from the rectangular MDCT's. However, despite the problems intro-
duced by the aerodynamically poor design of rectangular towers, fogging ef-
fects are limited usually to the plant property due to the plume's buoyancy.
Factors influencing icing frequency and duration are similar to those causing
fogging. The difference is that during cold weather, the frequency and dura-
tion of cooling tower plumes are enhanced because the much lower ambient tem-
perature leads to condensation of more cooling tower water vapor. The quan-
117
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titative plume frequency and duration comparison at different temperatures
relative humidities and temperature lapse rate classes have not been estab-
lished in field studies. Such studies have been limited to numerical model
predictions. Of course, the ambient temperature must be below freezing to
have icing. Hence, the frequency of temperature below freezing is necessary
to establish the seriousness of icing. Long freezing periods will prevent
accumulated ice from disappearing.
Fogging is dependent upon the tower type, and this is true for icing as well.
At Chalk Point, the NDCT does not cause more than a few millimeters of ice
on structures and wires located on the plant site (8). From field observa-
tions, Slawson et al (2) determined that icing from the NDCT's at Paradise
is not significant.
As in the case of fogging, icing is more of a problem from MDCT's than from
NDCT's. An extreme case occurred at Palisades (Consumer Power Co.) on Lake
Michigan during December, 1976 (9). Extremely heavy icing coated trees and
the ground on the lee wind side of the five rectangular MDCT's. A conserva-
tive (worst case) estimate indicated that five to six inches of ice coated
the trees, and 12 inches lay on the ground. Glaze ice of %-inch thickness
extended as far as 240 m down wind. The cause of this phenomenon was not
documented. Whether there was failure of the eliminators, different opera-
ting conditions, or severe weather was not discussed. Because of the un-
usually cold winter of 1976-77, it is plausible that severe weather seriously
aggravated this icing condition.
Although other reported cases of icing have not been severe, MDCT's do seem
to cause more of an icing problem than NDCT's due to the same reasons as in
the case of increased fogging and because of the larger droplets being en-
trained by the forced draft.
The net icing effect at off-plant locations from MDCT's are not necessarily
worse than for NDCT's. This is because larger droplets leaving the tower
are confined to an area within the plant boundaries, since they have a
larger fall velocity. Actual type comparisons have not been performed in
the literature with regard to field studies of icing; only individual towers
have been evaluated from field studies and from numerical model predictions.
5.3 METEOROLOGICAL CONDITIONS CONDUCIVE TO FOGGING AND ICING
Ambient meteorological conditions for MDCT (mechanical draft cooling tower)
fogging include: wind speeds greater than 2 m/sec, stable temperature lapse
rates, relative humidity greater than 95% and low dry bulb temperatures
(usually less than 50°F). These conditions cause downwash, low dispersion
rates, low evaporation rates and additional condensation, respectively. With
regard to fogging frequency, these parameters have never been correlated
quantitatively with fogging frequency or duration, except with numerical
model predictions in environmental reports. Icing requires freezing temper-
atures; hence, the number of days below freezing is a determining factor of
the icing potential.
118
-------
Site-specific climatology is a prerequisite to establishing regions where
fogging-icing may present particular difficulties. The problem then becomes
one of finding a model accurate enough to establish fogging frequency and
duration. To date, only one study has been prepared to categorize general
regions where the fogging frequency may present potential problems. However,
the model has no verification with field data. The danger of making regional
fogging potential classifications on scales larger than 10 km is that meso-
scale phenomena, caused by conditions such as mountain-valley flow and sea-
breeze regimes, reduce the accuracy of general classifications. Fogging
potential classifications can be more accurately represented by types of
climatology rather than by region. However, to date no such classifications
study has been conducted.
Generally, the major quantitative drawback to the determination of fogging-
icing frequency has been the lack of field studies. Only recently have
models been independently evaluated and the final results are not yet avail-
able (10,11). As complete as this evaluation will be, the field data base
contains only about 39 observations. As a result, only generalizations can
be drawn from present site studies; specifics apply only to a single site.
In addition, nearly all of the field studies were performed at natural draft
cooling towers (NDCT) rather than at MDCT's. Thus, there is a considerable
lack of data on MDCT behavior (12), resulting in a speculative assessment of
atmospheric conditions influenced by MDCT plumes.
5.4 ADVERSE EFFECTS OF FOGGING AND ICING
Fogging-icing effects appear to locally dissipate. Only in rare instances
can the effect at distances of five or more kilometers from cooling towers
be noticed (13). In one instance, a snow crystal cloud extended to 43 km
downwind of the cooling tower and the plume was elevated. But, under ex-
tremely cold ambient conditions and in situations where the ground elevation
rises, such a plume may reach ground levels. Although model results vary
from observed values by factors of two or three (11), most concur within one
order of magnitude. On the basis of model predictions, it is not reasonable
to expect fogging and icing beyond 10 km unless topography within the area
rises substantially. In this case, plume intersection with the ground at
large distances is possible under certain meteorological conditions. Under
these circumstances, some damage to vegetation as a result of icing and ob-
struction of sight due to fogging could occur. For example, a. cooling tower
located in a valley might present such a problem. Nearby airfields might be
adversely affected with visual obstruction due to particularly long cooling
tower plumes. However, the visual obstruction is of short duration (8) and
is of little concern unless the plume happens to be covering certain critical
places, such as the runway.
On the basis of wind tunnel and field studies, MDCT's pose a more serious
fogging and icing threat than NDCT's (5,9,14,15). The Palisades incident (9)
severely damaged vegetation within about 91 meters, but this incident was ab-
normal. Damage to vegetation in the area between about 90 m and 240 m where
ice glaze accumulated from 0.25 to 2.0 inches showed moderate to minimal
damage. No description beyond 240 m is mentioned, NDCT's appear to not
cause much of a problem in this regard.
119
-------
5.5 CLOUD ENHANCEMENT
Although an increase of clouds downwind of a cooling tower has been noted
qualitatively many times (1), the overall quantitative enhancement has not
been established through field studies. Two types of cloud enhancements are
considered in the literature: the condensed cooling tower phase and cloud
physics processes. The former is evaluated by observation of plume lengths
(Tables 5-2 and 5-3). Some of these observations are available through the
Argonne National Laboratory validation progress report (11); these observa-
tions collected from other sources probably contain the best information in
the literature. Another group involving cloud physics processes is not well-
documented, since the cooling tower contribution by this mechanism is subtle.
The cooling tower plume may actually disappear, but because of additional
heat and moisture added to ambient air, it may cause a cloud to form at some
point downwind. This type of cloud would typically occur in a convective
process which forms cumulus type clouds. During a stable process, the cool-
ing tower plume and stratus clouds usually merge so that one is indistin-
guishable from the other.
The enhancement resulting from cloud physics processes has been estimated by
radiosonde data collected at Nashville, Tennessee (5) and a numerical one-
dimensional cloud physics model (16). There are numerous other one-dimen-
sional cloud physics models which are basically the same, however, the Kramer
ot_ al.(16) model has been more frequently evaluated (5).
Hanna (5) has determined that for the single cell 1000 MW station (typical
NDCT now in use) cloud frequency occurrences are 397,. Of course, predicted
cloud occurrences are spread over all directions so that the impact on any
one sector should be less than 39%.
For the two cloud enhancement types, quantitative measurement of cloud en-
hancement has not been verified by field observations. Generally, environ-
mental reports contend that some enhancement is expected but the effect on
any one sector is not significant, probably less than 10%. Perhaps, these
impact statements are supported by unverified numerical models or are refer-
enced by qualitative reports concerning the non-importance of induced cooling
tower clouds. Usually, none is supported by complete field studies. There
is often no delineation between estimated enhancements of natural draft
cooling towers and those of mechanical draft cooling towers. If a numerical
model is used, then the difference is a result of various input parameters
of natural draft cooling towers and mechanical draft cooling towers.
Regarding cloud physics models, Auer e_t al. (17) measured the Aitken Conden-
sation Nuclei (ACN) concentration from four coal-fired power plants. The
mid-size power plant of 1000 MWe produced ACN plumes 200% greater than back-
ground levels for one to two hours down wind. For example, the ACN count
started at about 9000/cm3, but then dropped to about 1000/cm3 after two
hours. The large plant produced ACN for about four hours down wind, in this
case, the width of the ACN plume increased to 25 km and then remained con-
stant at 7 to 10 km out to 50 km. Because such nuclei aid cloud formation,
knowledge of their concentration may be useful in estimating probabilities of
additional cloud formation.
120
-------
In sum, cooling towers modify natural cloud formations (1,5). The extent of
the modification has not been fully established by field observation (see
Table 5-1). Present day cooling towers do not produce clouds when ambient
conditions are not fertile.
5.6 METEOROLOGICAL CONDITIONS CONDUCIVE TO CLOUD ENHANCEMENT
The meteorological conditions which induce additional clouds are determined
by the clouds already present. For a cloud to result from an extended cool-
ing tower plume, the conditions include stable stratification, high relative
humidity (RH), cool temperatures and minimal insolation. Typically, under
these conditions the clouds formed will be of the stratus variety.
Cooling tower plumes are influenced by ambient RH conditions. For example,
for 250 MW towers, all plumes are less than 300 m long with RH less than 75%;
but for RH between 75% and 90%, 40% of the plumes are short, 40% medium and
20% are long (more than 900 m) (4). Brennan e_t aJL. (18) observed that temper-
ature-humidity soundings in the vicinity of towers would serve as effective
predictors of plume rise and persistence. However, no significant relation-
ships between plume rise and wind speed, plant load or ambient temperature
were observed. Other observations (2) indicated that downwash, which is a
function of wind sr ;ed, reduced visible plume length and moisture content
(Figure 5-2).
For induced cumulus clouds, conditions similar to a tropical regime with con-
vective thermals exist, characteristically exhibiting high RH and warm tem-
peratures in generally unstable conditions in which cumulus clouds form. The
cloud dynamics and microphysics involved in cloud formation involve many pa-
rameters such as saturation vapor pressure, droplet concentration, droplet
size, relative humidity, dry bulb temperature, absolute humidity, temperature
lapse rate, latent heat release, vertical velocity and entrainment. The rate
of cloud water production is dependent upon these parameters and is obtained
from equations which are summarized very well by Hanna (5). Because of the
complexity of the process, it is not possible to predict when a cloud will be
formed unless the whole system of equations is used. Several numerical
models have been created to perform this task, with the one of Kramer et al.
(16) seeming to be reliable (5). In general, if conditions are fertile for
natural cloud formation, then a cooling tower will accelerate and augment
the formation.
5.7 ADVERSE EFFECTS OF CLOUD ENHANCEMENT
If it is assumed that cooling tower emissions do not significantly augment
clouds over a specific area, then the adverse effects are small. Perhaps
agricultural areas, such as the grape-growing regions of New York State,
may be particularly sensitive to slightly reduced sunshine, but other areas
would not suffer. However, no data supports this contention.
5.8 PRECIPITATION ENHANCEMENT FREQUENCY
Precipitation enhancement is documented in the literature, but measurement
of the increased frequency for precipitation has not been obtained and docu-
121
-------
mented. Kramer e_t al.(13) measured a maximum of 2.5 cm snowfall from natural
draft cooling tower plumes from the Amos Power Plant when no other precipita-
tion in the area existed. This occurred several times while they were ob-
taining plume data. At a power station with cooling towers in India, monsoon
rain increased by about 25% at a station one kilometer away (19). Even with
non-tropical environments and more environmentally clean stations, precipita-
tion augmentation may exist. Hanna (5) suggested precipitation was enhanced,
but offered no direct evidence.
Martin (20) did not find any statistically meaningful change in the rainfall
around eight natural draft cooling towers at a 2000 MW station (Table 5-1).
In testimony by Montz from the New York State Public Service Commission Staff
(7), precipitation enhancement was not considered significant. Huff (21)
projected less than 1% augmentation of stable rainfall resulting from a 2200
MW plant with two cooling towers rejecting 8.3 x 109 Btu/hr and 14,700 gpm of
water vapor. Snow enhancement from the lake effect would be two to five
inches at this Illinois plant which is about 5% of the annual snowfall. Con-
vective showers might also be augmented.
During the winter of 1975-76, snowfall from the plumes of large natural draft
cooling towers of power plants was observed 8 to 43 km away. Snow accumula-
tions of up to 2.5 cm were found on the ground at about 30 km from the cool-
ing towers, and visibility was restricted to less than 1600 m in the tower
plume near ground level (13). AEP's Amos Plant with three natural draft
cooling towers was used for this observation.
The knowledge of environmental effects caused by injections of large amounts
of waste heat into the atmosphere from large power parks or complexes, such
as those proposed in Louisiana, Florida and Pennsylvania with capacities as
much as 10,000 MWe, is limited. A power center of 15 GWe rejecting heat over
a ten-mile distance to the atmosphere would cause a 10°F temperature rise if
once-through cooling were used, or about a 1°F drop if evaporatively cooled
in a desert region; otherwise the only other predicted observable effect of
cooling towers, wet or dry, would be about a 0.5% increase of cloudiness,
again in a desert region. Once-through cooling of this intensity would cause
a 3 or 4% cloudiness increase in a moist climate, but not in the desert (22).
Precipitation frequency enhancement by cooling towers is not easily documen-
ted because of the natural variability and cyclic nature of precipitation. A
change in precipitation around the locality of a cooling tower may simply be
a normal occurrence.
5.9 METEOROLOGICAL CONDITIONS CONDUCIVE TO PRECIPITATION ENHANCEMENT
In general, conditions which induce clouds will produce additional precipi-
tation. Conditions for precipitation production must be fertile for the
enhancement to occur. Differences between cloud and precipitation formation
involves the additional process of coalescence, whereby a droplet becomes
large enough to counteract upward vertical air velocities and evaporation
below the clouds. In the snowfall at the Amos Plant, Kramer e£ al^. (13) noted
that the snowfall did not occur until the ambient temperature fell below
13.6°F. This seemed to be a necessary condition, but not a sufficient one.
122
-------
High RH and stable conditions existed at the time of this snowfall.
Convective precipitation augmentation by cooling towers has not been ob-
served, except by Selvan e_t aJL. (19). However, insufficient information
exists to quantitatively determine precipitation enhancement, thereby ren-
dering the selection of meteorological conditions beyond general descriptions
useless for estimating enhancement.
123
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REFERENCES
1. Kramer, M. L., M. £. Smith, M. J. Buffer, D. E. Seymour and T. T.
Frankenberg, 1976. Cooling Towers and the Environment. J. Air Poll.
Control Assoc., 26(6): 582-584.
2. Slawson, P. R., J. H. Coleman and J. W. Frey, 1975. Some Observations
on Cooling Tower Plume Behavior at the Paradise Steam Plant. In:
Cooling Tower Environment - 1974. Hanna, S. R. and J. Pell (eds.) ERDA
Symp. Ser. CONF-740302, pp. 147-159.
3. Moore, D. J., 1975. Recent Control Electricity Generating Board Re-
search on Environmental Effects of Wet Cooling Towers, in; Cooling
Tower Environment - 1974. Hanna and Pell (eds.), ERDA Symp. Ser.
CONF-740302, pp. 205-213.
4. Spurr, G., 1974. Meteorology and Cooling Tower Operation. Atmos.
Envir., 8: 321-324.
5. Hanna, S. R., 1977. Atmospheric Effects of Energy Generation.
Unpublished manuscript.
6. USNRC, 1976. Indian Point Unit No. 2, Environmental Statement.
NUREG-0042.
7. Montz, A. C., et al^, 1977. Air Quality and Meteorology Testimony -
Case 80002. Public Service Commission Staff of New York State.
8. Woffinden, G. J., e_t al., 1976. Chalk Point Cooling Tower Project,
Cooling Tower Plume Survey. Technical Summary, Vol. 1, Meteorology
Research, Inc., for Maryland Dept. Natural Resources.
9. Consumer Power Co., Inc., 1977. Report on Drift Deposition and Icing
at Palisades. Unpublished Report.
10. Policastro, A. J., et al., 1977. Progress Report - Validation of
Cooling Tower Plume Rise and Salt Drift Deposition Models. Nov. 1,
1976-Mar. 31, 1977, Argonne National Laboratory, Unpublished.
11. Policastro, A. J., et al^, 1977. Progress Report - Validation of
Cooling Tower Plume Rise and Salt Drift Deposition Models. Feb. 1,
1977-Mar. 31, 1977, Argonne National Laboratory, Unpublished.
124
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12. Champion, E. R., £t £l., 1977. Field Study of Mechanical Draft Cooling
Tower Plume Behavior. Proc. Conf. Waste Heat Management and Utiliza-
tion, May 9-11, 1977, Miami Beach, Florida.
13. Kramer, M. L., D. E. Seymour, M. E. Smith, 1976. Snowfall Observations
from Natural Draft Cooling Tower Plumes. Science 193: 1239-1241.
14. Hanna, S. R., 1975. Meteorological Effects of Mechanical Draft Cooling
Towers of the Oak Ridge Gaseous Diffusion Plant. In; Cooling Tower
Environment-1974. Hanna and Pell (eds.), ERDA Symp. Ser. CONF-740302,
pp. 291-305.
15. Kennedy, J. F. and H. Fordyne, 1975. Plume Recirculation and Inter-
ference in Mechanical Draft Cooling Towers. In; Cooling Tower En-
vironment - 1974, Hanna and Pell (eds.), ERDA Symp. Ser. CONF-740302,
pp. 58-87.
16. Kramer, M. L., e_t al^., 1975. John E. Amos Cooling Tower Flight Program
Data, December, 1974 - March, 1975. Smith-Singer Meteorologists, Inc.
for American Electric Power Service Corp.
17. Auer, A. H. , e_t al. . 1977. The Behavior of Aitken Nuclear Plumes from
Coal-Fired Plants in the Midwest. Preprints on Joint Conference on
Applications of Air Pollution Meteorology, Utah.
18. Brennan, P. T., D. E. Seymour, M. J. Butler, M. L. Kramer, M. E. Smith
and T. T. Frankenbery, 1976. The Observed Rise of Visible Plumes
From Hyperbolic Natural Draft Cooling Towers. Atmos. Env., 10: 425-
431.
19. Selvan, A. M., £££!•» 1976. Rainfall Variations Around a Thermal Power
Station. Atmos. Envir. 10: 963-968.
20. Martin, A.t 1974. The Influence of a Power Station on Climate - A
Study of Local Weather Records. Atmos. Envir., 8: 419-424.
21. Huff, E. A. Potential Augmentation of Precipitation From Cooling
Tower Effluents. Bull. Amer. Meteor. Soc., 53: 639-644.
22. Moore, F. K., 1976. Regional Climatic Effects of Power Plant Heat
Rejection. Atmos. Envir., 10: 806-811.
125
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I
r
oi»e»
CI»TO
10 "
JMM*
n
OIMT
1
I
T
so,
i Nattinqtam
a Sutten Banmqtat
>iO '6° zoo
^4 n^Snekt / lta>on
IO IJO ISO 20O J4O JIO 120
>>4 m"HO, /1 Mun
Figure 5-1 Incidence of fog and seasonal smoke and SO,
126
-------
PLUME BEHAVIOR AT PARADISE STEAM PLANT
300
E
§
200
I
< 100
t-
a
U)
I T
- Theory with
i • 1.0 t£xJ'J for
center line. «b • 3.7 m
•—Observed 0645 to 0745 hr
— — Observed 0815 to 0900 hr
200
400
600
DISTANCE DOWNWIND, m
Figure 5-2 Predicted and observed cooling tower
plume behavior, Sept. 7, 1972 (2)
127
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TABLE 5-1
CONDITIONS BEFORE AND AFTER COMMISSIONING OF THE POWER STATION (4)
to
00
Distance from
Site Ratcliffe (fan)
(a) Rainfall, (mm/yr)
Sutton Bonington
Nottingham
Morley
Derby
Watnall
Newt own Linford
Cranwell
Wittering
Terrington
Skegness
(b) Bright sunshine (h/day)
Sutton Bonington
Nottingham
Morley
Derby
Watnall
New town Linford
Cranwell
Wittering
Terrington
Skegness
4
12
15
16
16
20
56
61
106
112
4
12
15
16
16
20
56
61
106
112
Mean
1960-1967
606
608
724
672
733
682
586
582
584
630
3.61
3.29
3.56
3.59
3.38
3.62
3.99
4.10
4.05
4.09
Mean
1968-1971
627
603
702
697
724
679
618
631
562
589
3.54
3.49
3.55
3.48
3.27
3.37
3.93
3.91
3.87
4.11
Change
4-21
-5
-22
+25
-9
-3
+32
+49
-22
-41
-0.06
+0.20
-0.01
-0.11
-0.11
-0.25
-0.06
-0.19
-0.18
+0.02
Scatter and significance
e.g. Sutton Bonington
increase
95% confidence limits on
means
- + 117 and + 138
respectively
Students of increase
=0.22 for 10 degrees-
of- freedom
Value of 2.23 required
for 5%
significance-increase
not significant
e.g. Newt own Linford
decrease
95% confidence limits
+ 0.24 and + 0.28
respectively
t = 1.63 for 10 degrees-
of- freedom
decrease not significant
-------
TABLE 5-1 (cont'd)
Site
(c) Fog, at 0900 h (days/yr)
Sutton Bonington
Nottingham
Morley
Derby
Watnall
New town Linford
Cranwell
Wittering
Terrington
Skegness
Distance from
Ratcliffe (km)
4
12
15
16
16
20
56
61
106
112
Mean
1960-1967
19
27
._*
32
41
22
25
23
20
21
Mean
1968-1971
12
21
--
16
33
18
23
28
18
12
Change
-7
-6
--
-16
-8
-4
-2
+5
-2
-9
Scatter and significance
e.g. Wittering increase
95% confidence limits
+ 6 and + 2 respectively
t = 1.63 for 10
degrees-of -freedom
increase not significant
e.g. Derby decrease
95% confidence limits
+ 12 and + 2 respectively
t « 2.55 for 10 degrees-
of-freedom
decrease significant
*Not recorded.
-------
TABLE 5-2
COMPARISON OF OBSERVED AND PREDICTED PLUME LENGTHS (2)
Date
2/10/71
3/2/71
3/4/71
9/7/72
9/7/72
Time
065 3 to 0750
1010 to 1050
0640 to 0720
081 5 to 0942
0945 to 1045
Observed
length.
m
5 32 to 866
106 to 167
300 to 465
200
150
Cooling
towers
operating
1
2
1
3
3
K
1.5
1.0
1.5
1.0
1.0
Predicted
length
(Xg), m
407
156
400
196
158
130
-------
TABLE 5-3
SOURCE AND AMBIENT DATA
Date
2/10/71
1/28/71
3/2/71
3/4/71
9/7/72
9/7/72
9/12/72
9/13/72
9/14/72
Time
0653
0932 to
1030
1010 to
1050
0640 to
0720
0704
0900
0710
0800
1022
w,,
m/sec
2.5
2.5
2.5
2.5
3.6
3.8
3.9
2.3
2.8
Tpov,
°K
303.2
308.0
209.7
298.7
310.7
315.7
309.7
309.9
314.3
Ta,
°K
262.8
270.0
280.3
266.0
292.0
293.7
295.4
295.5
297.0
Spo-
g/kg
21.2
26.7
17.1
16.7
30.9
37.9
29.5
29.8
35.6
la-
g/kg
0.87
2.10
4.54
1.88
12.60
13.00
12.67
14.13
15.83
u,
m/sec
11.6
8.7
7.3
7.0
8.0
5.0
9.0
8.0
8.0
'b.
m
.2.3
4.9
3.8
8.1
3.7
18.0
2.0
1.7
2.5
PO.
mb
1012.6
1005,8
1002.4
1002.5
966.8
968.9
968.2
968.9
973.2
131
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SECTION 6
STACK PLUMES
6.1 PLUME BEHAVIOR
6.1.1 Plume Rise
Vertical motion of the plume to the height where it becomes horizontal is
known as plume rise. It is assumed to be a function primarily of the emis-
sion conditions at the stack, primarily exit velocity and temperature. The
exit velocity gives the flue gases an upward momentum, causing the plume to
rise until atmospheric turbulence disrupts its integrity stopping the verti-
cal motion. This is known as the momentum plume rise. Stack gas tempera-
tures are usually much higher than ambient, so that the emissions are less
dense than the surrounding air. Such differences in density give the stack
gases buoyancy, allowing the plume to rise until it is cooled by the atmos-
phere, and the density differential becomes zero. This is known as the ther-
mal plume rise.
Momentum and thermal plume rises combine to produce the plume rise of the
emitted stack gases. These effects are interdependent. Gases with high exit
velocities are cooled faster due to more atmospheric mixing of plume, thus
reducing thermal buoyancy. Low exit velocities cause the plume to become
trapped in the turbulent wake along the side of the stack and to fall rapidly
to the ground (fumigation). Fumigation can usually be prevented by keeping
the exit velocity greater than 10 m/sec. An emission velocity that is 1.5
times greater than the atmospheric crosswind is generally accepted as a per-
missible safety factor to prevent this fumigation phenomenon. Momentum con-
tribution to plume rise is usually insignificant compared to the buoyancy
contribution.
Meteorology and the power plant operating characteristics play important
roles in determining the height to which pollutants rise and disperse. Wind
speed, wind shear and eddy currents influence the interaction between the
plume and atmosphere. Ambient temperatures affect the buoyancy of a plume.
6.1.2 Long Range Transportation
The transportation process is considered on three levels:
1. The near-source or single-plume dispersion problem
2. The multiple plume dispersion problem
3. The long-range transportation
132
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Recent studies have attempted to explain single-plume dispersion by modeling
techniques, multiple plume dispersion within the context of urban diffusion,
and long-range transportation mainly as a meteorological problem. Fox (1)
developed an approximate transportation model which is used to calculate the
ambient concentration of S02 throughout the U.S.
Observations show that pollutants from large emission sources may cause sig-
nificant air concentrations 800 km to 1600 km (500 to 1000 miles) away. Very
high acid precipitation occurs during such periods. The scavenging is often
intensified by the topography (1). Milan and Chung (2) have detected the
stack plume from the 300 m high Sudbury smelter about 400 km away from its
source. An unusually high S02 reading over the northern edge of Toronto
(Canada) obtained by a correlation spectrometer (COSPEC) remote sensor, and
the findings of posterior trajectory analysis of the air parcel over Toronto
at the time of measurement provide bases for Milan and Chung's, observation.
They estimated the total length of the visible plume as approximately 80 km
to as high as 160 km.
6.1.3 Effect of Terrain
Bowers and Cramer (3) have studied the plumes from the Mitchell and Kammer
(Units 1 & 2) powe^ plants located in complex terrain, 2 km apart in the
Ohio Valley, Marshall County, West Virginia. The fixed stack parameters are
given in Table 6-1.
Predicted or calculated plume rises from the Briggs equation were in agree-
ment with the observations for the plume from the Mitchell and Kammer No. 1
units. In every case, the predicted plume rise for Kammer No. 2 exceeded the
observed rise. This was due to the interaction of this plume with the ter-
rain between the stack and the aircraft observations. These aircraft obser-
vations agree well with the measured concentrations near the stack.
An appraisal of the current research in power plant stack plumes in complex
(hilly or mountainous) terrain indicated that turbulence is enhanced over
complex terrain through thermal drainage, up-slope flows, lee waves and
channeling (4). Evidence exists that horizontal spreading of plumes is am-
plified in complex terrain to a greater extent than vertical spreading.
Available models tend to over-predict plume concentrations by factors of
five or more at distances within a few kilometers of the source, but model
predictions improve at greater distances. The models, in general, under-
estimate the initial lateral spread of the plume and overestimate vertical
spread at greater distances. In other words, the observed plume in complex
terrain (compared to flat terrain for similar stability conditions) has a
larger cross-section, and the plume is generally more dilute in the core by
a. factor of two or more (5).
6.2 STACK GAS COMPOSITION
6.2.1 Introduction
Sulfur oxides (SOX), nitrogen oxides (NOx), carbon monoxide (CO), and a
variety of aliphatic organic compounds constitute the major atmospheric
133
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emissions from fossil-fueled power plants. In addition, significant amounts
of trace metals and metalloids, acid mists and polycyclic organic species are
also emitted. Table 6-6 shows the average air pollution emissions from var-
ious power plants according to fuel type (6).
The amount of SOX emitted from a power plant is directly related to the sul-
fur content of the fuel used. The average sulfur content of U.S. coals is
about 2.5%, and the residual fuel oils contain between 0.7 and 5.5% of sulfur
in the form of dissolved H2S, elemental sulfur and organic sulfur compounds.
Natural gas is typically very low in sulfur which is present primarily as
H2S.
About 95% of the sulfur present in fossil fuels is emitted in the form of
sulfur oxides. Due to the reversible and temperature dependent nature of the
conversion reaction, only 1-2% of the sulfur is emitted as 803 which rapidly
reacts with water vapor to produce sulfuric acid. S02 concentrations ap-
pearing at the stack exit typically lie in the range 500 to 3000 ppm, with
1000 to 2000 ppm being common without controls.
The extent of nitric oxide, NO, formation depends primarily upon the 02 and
N2 contents of the feed air, the combustion temperature and the average resi-
dence time of the oxygen and nitrogen molecules in the combustion zone. The
amount of nitrogen dioxide, N02, formed during combustion is generally much
less than that of nitric oxide (NO) and depends on the amount of NO formed
and thus on the combustion temperature. Actual concentrations of NOX are
normally in the range of 300 to 1300 ppm in the stack emissions.
Particulate emissions from coal-fired power plants are much higher than that
emitted by oil- and gas-fired plants as shown in Table 6-6. These particles
contain a wide variety of toxic trace elements including metals, metalloids
and organic species. The major elemental constituents of coal fly ash are
silicon, aluminum, iron, potassium and calcium (Table 6-7).
As many as 37 trace elements have been found in coal (Table 6-8). These are
transferred to slag, fly ash or flue gases on combustion. The specific con-
centrations (ug/gm) and volume concentrations (ug/m3) of the trace elements
in coal and oil fly ash are given in Table 6-9. This comparison indicates
that fly ash is more prevalent from coal than from oil.
Other emissions from fossil fueled power plants include: gaseous hydrocar-
bons, aldehydes, and sulfuric and hydrochloric acid mists. Sulfuric and
sulfurous acid mists are formed in small amounts near the exit of power plant
stacks where the temperature is sufficiently low to allow formation of liquid
water droplets which absorb S02 and 803. Some metal-catalyzed oxidation of
sulfite to sulfate takes place in these droplets which are extremely acidic
and corrosive (6).
With various technologies and fuels available for steam production, no stand-
ard composition can be assigned to stack gases (Tables 6-2 to 6-5). For in-
stance, sulfur contents between Western coal and Eastern coals vary widely;
neither is the sulfur content in oil from different regions uniform. To
complicate matters further, trace elements such as iron significantly affect
134
-------
certain reactions. Participates also have a significant impact on the chemi-
cal reactions. For example, large participates are believed to mitigate acid
production resulting from stack gases (7). Smaller participates may enhance
chemical reactions or have no influence at all. With different particulate
inhibitors such as electrostatic precipitators and various load conditions,
the particulate size distribution emitted by a stack varies from .01 - 100 um
(3). Different technologies create different reactions and particulate dis-
tributions within the boiler because of different flame temperatures, feed
air and air cleaning processes. Consequently, individual plant stack studies
are necessary to accurately represent stack gas composition.
Fuel composition is the most important factor determining stack gas composi-
tion. The literature appears to analyze coal more than oil or natural gas.
However, both oil and coal, which are the major fuel sources for electric
steam generation, are dealt with in this report. In general, Western U.S.
coal has higher ash content and exhibits higher alkaline earth metal contents.
S102, A1203, CaO and Fe203 are major constituents by far in western coals.
Because of the higher concentration for CaO and Na20 in the fly ash, Western
coal is more alkaline than Eastern coal (8). Some of these constituents act
as catalysts in sulfate formation, particularly Fe203. In both coal and oil,
about 95% of the sulfur is emitted as S02 with sulfates usually amounting to
1 or 2%.
This information gives the reader a general characterization of stack gas
composition. Further details as to their importance in sulfate and acid pro-
duction will be provided in a later section.
6.2.2 Power Plant Emission Rates
In accordance with Federal New Source Performance Standards, the emissions
from fossil-fuel fired generating units of 250 x 10& Btu/hr or more heat input
must be expressed in terms of lb/10*> Btu heat input. Pollution concentra-
tions, effluent volumetric flow rate, and heat input rate (fuel rate x fuel
heat content) are required to calculate emission rates. An alternative method
using pollution concentrations is presented by Shigehera (9). This method
uses a ratio F, which is the effluent gas generated per 10*> Btu heat content.
Average F factors for various fossil fuels are given in Table 6-10.
Nitrogen-based anthropogenic emissions are responsible for as much as 30-40%
of the strong-acid anion found in low pH samples in the U.S. However, char-
acterization of NOX emissions is more complex than S02- Of the approximately
24 million tons of NOX emitted annually, 45% is from industrial and power-
generation point sources, while 36% is from transportation sources. In com-
parison, stationary point sources and area sources emitted 87% and 13%,
respectively, of the 32 million tons of S02 emitted annually in the United
States. Both active photochemical reactions and mobile sources complicate
and make the assessment of NOX pollution levels very difficult (1).
6.2.3 Sulfur Dioxide and Conversion to Sulfates
Other than particulates, sulfur oxides and nitrogen oxides are the major air
pollutants emitted from stacks in coal-fired plants. These oxides undergo
135
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thermochemical oxidation with the water vapor from cooling tower plumes and
form basic ingredients for further interaction. This section summarizes the
review of available literature on these topics.
Literally hundreds of articles dealing with this subject are available. Thus,
it is not the intent of this report to make a comprehensive review of S02,
oxidation or atmospheric sulfates. Such studies have already been completed
(10). EPA has completed studies and has prepared a position paper on Regula-
tion of Atmospheric Sulfates (EPA-450/2-75-007, September 1975, NTIS PB-
245760). Some of the salient information pertinent to the interaction phenom-
enon is presented here.
The literature reviewed on the oxidation of SC>2 to sulfate in power plant
plumes does not lead to firm quantitative conclusions regarding rates of con-
version or the mechanisms involved (11) (Table 6-11).
Studies dealing with sulfur oxidation processes in stack plumes have estima-
ted the rates range from 0 to 50%/hr. However, the bulk of literature sup-
ports a rate somewhere between 0.5 to 10%/hr with a reasonable value for many
situations being 2%/hr (10). Several factors affect the rate of oxidation:
meteorological conditions, catalytic chemicals in the stack gas, and back-
ground chemicals. Photochemical reactions are significant with regard to
background. Photochemical reactions caused by the stack plume itself affect
oxidation rates further downwind rather than over the short term, in nearly
all instances, oxidation from the stack gas occurred within a few kilometers
(12), with a high oxidation rate near the stack and a lower rate downwind
(10)! However, recent studies indicate lower rates than previously reported
(10). In coal-fired stack gas plumes, oxidation seldom exceeded 4% - one
third of which came from combustion. On the other hand, for oil-fired
plumes, the oxidation was measured at twice the amount of the coal-fired
plume. This difference may be due to "plume dropout" which is particulate
precipitation of sulfur (12). MacKenzie (13) maintained that 10 to 20 miles
downwind the oxidation rate accelerates, and S02 oxidation is rather slow
under stable meteorological conditions during the first 10 miles or so. The
SO? plume centerline concentration will change only by about 0.2 ppm over
about 20 miles so that oxidations can therefore be significant downwind. A
later paper by Forrest et al.(14), stated that the extent of S0£ oxidation as
measured by aircraft seldom exceeded 5% with essentially all oxidation within
the first few kilometers. This contrasts with the oil-fired plume in which
20% oxidation occurred.
Meteorological factors such as temperature and relative humidity affect oxi-
dation rates. Given equal conditions of other criteria, increased relative
humidity and temperature both mean increased oxidation rates. A numerical
model by Freiberg (15) of oxidation as a function of the emission and the
iron catalytic reactor depicts oxidation as a function of dispersion, rela-
tive humidity and temperature. However, the contention of Forrest and Newman
(14) directly conflicts with this model. No obvious correlation between tem-
perature or relative humidity and the oxidation rate was found by Forrest and
Newman. In addition, there is insufficient evidence in field experiments to
support Freiberg's model.
136
-------
Forrest and Newman of Brookhaven National Laboratories employed a 34S32S
isotope ratio and participate sulfur to total sulfur concentration ratios to
determine the percent of S02 converted to sulfates in the plumes of several
oil and coal-fired power plants (12,14). The plants studied are included in
Table 6-12.
The extent of oxidation in oil-fired plumes (267./hr) was more than triple that
observed for coal (8.570/hr), indicating that significant amounts of sulfate
were dropping out of the plumes. This might cause observations of sulfate
formation to appear to be less than their true values (12).
In summary, these studies indicated a heterogeneous mechanism for the oxida-
tion of sulfur with the consumption or poisoning of available catalyst. No
distinct correlation was found between the extent of S02 conversion with
distance, travel time, temperature, relative humidity, time of day or atmos-
pheric stability.
Plume reproducibility measurements showed that the plume can vary from moment
to moment by as much as a factor of two in percentage of total sulfur as par-
ticulate sulfur (14).
If the isotope resists are discarded (the isotope technique is considered
erroneous by Wilson), Forrest and Newman's data indicated that no difference
exists between oil- and coal-fired plumes and that depending on conditions,
sulfur conversion rates of substantially greater than 1% per hour are possi-
ble.
Freiberg (15) developed a model which depicts quantitatively the iron cata-
lized oxidation of S02 to acid sulfate mist in dispersing stack plumes and
indicated that:
1. Relative humidity and temperature strongly influence the rate
of oxidation.
2. Not all of the S(>2 emitted will be converted to HoSOA.
3. Most of the oxidation always happens during the first hour
of plume travel and usually in considerably less time.
4. A maximum value of (SO?) is obtained at a downwind distance
which depends upon atmospheric parameters.
5. Ammonia from air is needed as a buffer to enable the oxida-
tion to proceed in the droplets.
6. No appreciable oxidation occurs below pH • 2 as observed by
Junge and Ryan.
Brosset (16) proposed a model for the catalytic oxidation of sulfur dioxide
in aqueous solution which is related to acidification of rain, based on the
assumption that a catalytic ion and hydrogen sulfite ions form a sparingly
soluble solid phase. This phase is oxidized by oxygen as soon as it is pre-
cipitated, resulting in the formation of sulfate ions and the dissolution of
the solid phase. This model adequately explains the wet deposition of sul-
fate resulting from sulfur dioxide emissions.
137
-------
Garland and Branson (17) studied the SC>2 concentrations over Great Britian
and reported that a value of 1200 m is the mean mixing height for SO?. This
indicates that dry deposition limits the mean lifetime of S02 to about 40
hours.
Enviroplan (18) conducted a study to predict the maximum annual average 24-
hour and 3-hour S02 concentrations produced annually by a new modern 1000 MWe
hypothetical electric power plant that complies with the Federal New Source
Performance Standards for SC>2 emissions from coal-fired power plants. A total
of three plant alternatives were examined: Case One, the use of a scrubber*
Case Two, the use of a scrubber with reheat of scrubbed gases before stack
emissions; and Case Three, the use of low sulfur coal. All cases used a 400-
ft stack height in the analysis. The meteorological data used in the study
were obtained from hourly observations at the Youngstown Airport in Youngs-
town, Ohio for the year 1973.
Table 6-13 summarizes the findings of the Enviroplan study and shows that Case
One had the worst S02 concentrations among the 3 cases. These results are
dependent on factors such as power plant size, fuel burned, meteorological
conditions and stack heights utilized. For a 2000 MWe power plant with a
single 400-ft stack, the maximum 24-hour S02 concentration for Case One will
be less than twice that of a 1000 MWe plant. The concentrations will be
within the government limitations, vis., 100 ug/m^ and 750 ug/m3, respectively
for maximum 3-hour and 24-hour SC>2 concentrations.
The American Electric Power Service Corporation and the Ohio Edison Corpora-
tion continuously monitor the ground-level concentrations of sulfur dioxide
at several monitoring sites. Considering the meteorological conditions and
electric generation in the Upper Ohio Valley, it appears that the power
plants did not adversely affect the ground-level S02 concentrations as had
been expected under the influence of an air stagnation episode. Examination
of a large number of stagnation episodes occurring over a period of two to
three years bears out the findings of this study.
6.2.4 NOy and Ozone
Field studies of the plumes from two coal-fired plants (Pacific Power and
Light Plant at Centralia, WA and the Four Corners Plant at Farmington, NM)
and two gas-fired power plants (Cunningham Plant at Hbbbs, NM, and the Wilkes
Plant at Longview, TX) were made by Hegg et al.(19). Airborne measurements
were made of the concentrations of NO, N02, 03 and S02, temperature, relative
humidity and ultraviolet radiation. Data was collected in 30 flights over an
eight-month period. Ozone concentrations exceeding those of the surrounding
ambient air were never found in these plumes, which were observed to distances
of 90 km (4 hours travel time) from the stacks. Analysis of the plume chem-
istry suggests that over distances and time scales within which plumes are
differentiable from background (the "near-field"), the chemistry is commonly
controlled by the rates at which the plumes mix with the ambient air, rather
than by chemical kinetics. Consequently, the rates of conversion of NO to
N02 are slow and the N02/NO ratios are small (the highest ratio measured was
4.3). This analysis is consistent with the observation that ozone was not
generated in the power plant plumes.
138
-------
Thirty sets of airborne measurements have been obtained by Kornberg et al.(20)
in the plumes from two coal-fired and two gas-fired power plants situated in
different climatological areas. The amount of ozone in power plant plumes
was not greater than ambient ozone to distances at which the plume was still
distinguishable from the ambient air. These field observations are under-
standable if the following observations are considered. The precursors of
ozone in fossil-fuel power plants are nitrogen oxides, primarily nitric oxide.
Nitric oxide must be converted to nitrogen dioxide in the plume before ozone
can be produced. Field data analysis reveals that this conversion rate is
generally controlled by the rate at which a plume mixes with the ambient air
rather than by the relevant chemical reaction rates. Since this mixing rate
is slower than the chemical reaction rates for the production of ozone, the
conversion of nitric oxide to nitrogen dioxide (and hence to ozone) is slower
than would be expected from laboratory or smog chamber experiments. Thus,
the conversion rates are slow enough to make ozone production in power plant
plumes unlikely.
In studies of a large, coal-fired power plant, ozone concentrations within
the plume were depressed below background levels (21), In all traverses
(to 45 km downwind), the depth of this ozone deficit and the ratio of NO to
NOx in the plume both decreased with increasing distance from the plant. A
model which accurately predicted the observed plume profiles of 03, NO, and
NOx from the background conditions, plume geometry, and basic photolytic
cycle indicated that free-radical reactions within the plume did not signifi-
cantly affect oxidant concentrations at the distances sampled. Data on NO,
N02» 63 and S02 in the plume of a 1000 MWe power plant firing a mixture of
oil and coal revealed a drop of ozone concentration in the plume boundaries
and indicated that at 50 km downwind there was an increase in ozone (the
bulge) coincident with low levels of plume S02 (10).
Recent airborne measurements, designed to facilitate understanding the chem-
istry and physics of plumes from fossil power plants, suggest that ozone may
be found in power plant plumes in concentrations exceeding background levels,
although most studies indicate no ozone buildup in plumes (22). Further
studies are required to explain the observed ozone buildup in plumes.
In general, ozone is expected to enhance S02 oxidation. However, in urban
areas, the existence of ©3 was not observed in the stack plumes during short
range field studies (10,19,20,23). There may be 03 production in stack
plumes further downwind or on a regional scale (10,23). However, field
studies indicated that no net ozone production in power plant plumes resulted
from entrainment of ambient ozone (23). Where hydrocarbon and NOx emission
are already present, such as in urban areas, S02 oxidation from ozone becomes
feasible.
Forrest and Newman (14) stated that no evidence existed for increased SO?
conversion even at the fringe of plumes. NOx within the plume depletes ozone
and thereby the S02 oxidation rate near the stack is lower than downwind (10
13). However, nitrogen oxides - ozone chemistry is not well established *
The analysis of the NOX-03 chemistry (24) at four power plants indicated"the
plume chemistry is generally diffusion controlled out to distances measured
(90 km). The NO to N02 conversion rates and N02/N0 ratios were consequently
139
-------
lower than expected from chemical kinetics alone. The consensus is that net
ozone production does not occur within the stack plume; hence, there is no
evidence for increased 802 conversion.
6.2.5 Acid Precipitation
Acidity of rainwater is of concern due to the progressive acidification of
soils, its effect on flora and fauna, and its corrosiveness to metals (25).
Acidic precipitation (rain, snowfall, mist, fog, etc.) in a local area could
be, to some degree, contributed by the interaction of the cooling tower plume
with the stack effluents.
In general, little data is available on the mechanism of acid production
leading to precipitation in the atmosphere (22). Problems relate to the
understanding of sulfur chemistry within the atmosphere. Nitrogen acids are
believed to contribute between 25-40% of the atmospheric acid. However, the
contribution from individual power plants has not been studied. The infor-
mation presented in this section, although not exhaustive, is intended to
give a general description of available data on acid precipitation. It is
assumed that the acidity of rainwater is due to formation of strong acids and
is a result of the atmospheric interaction of pollutants, especially S0£ and
emitted by electric power generating plants.
Chemical analysis of precipitation samples collected from 10 sites in South
Central Maine during June 18, 1974 to September 30, 1974, were used to deter
mine regional deposition patterns of ionic constituents. Acidic pH values
ranging from 3.8 to 5.0 were characteristic of the region. Systematic in-
creases in sulfate and sodium deposition in the samples in one site where
relatively alkaline pH of 5.5 to 7.0 was observed suggest the influence of a
local source. The composition of precipitation near a Kraft paper mill in-
dicates influence of background levels up to 20 km from the source (26).
The Allen S. King Generating Plant near Bayport, Minnesota delivers 420 tons
of sulfur dioxide to the atmosphere daily from a 789- ft (240-m) stack.
Dispersal from this height theoretically minimizes harmful effects of the
stack gases on vegetation. Recorded pH values (pH 4-9) around the power
plant were not significantly different from values obtained in several other
localities in Minnesota (27).
Analysis of recent precipitation samples from the Northeastern United States
showed a pH consistently less than 4.4 when the expected pH based upon
equilibrium with C02 would be 5.6, attributing 65% of the acidity to H2S04,
30% to HN03, and less than 5^ to HCL* 'fhe PH values may be predicted from
chemical content and generally agree with the observed pH to within 0.1 pH
unit. The pattern of acid precipitation apparently has existed since about
1950-1955, but the intensity of acid deposition, especially due to HN03,
increased since then. Analysis of prevailing winds indicates that much of
the acidity originates as a general source over industrial areas in the
Midwest (28).
Precipitation chemistry data from the 1920 *s indicates heavy ionic deposi-
tion, but low acidity (calculated) in Tennessee (pH 7.4) and New York (pH
140
-------
6.15). Summer acidity is currently lower in Tennessee than in the Northeast.
Precipitation chemistry of individual storms reveals some local variation
even within a 93 km range, but a storm in central New York is generally homo-
geneous over 70 km (29).
Studies to determine factors affecting composition of acidic precipitation
formation in the Austin area of Central Texas showed normal rainfall pH
values of 6.5 to 6.6 in the area, with extreme variations from 5.8 to 7.3
(30). Significant calcium levels of 1-4 mg/1 were observed, probably of
natural origin, and appeared to have a buffering effect on acidity. Signifi-
cant sulfate and nitrate ion concentrations occurred during the early stages
of rainfall where the rainfall pH was dependent on the calcium-sulfate ratio.
An experimental study of the kinetics of a reaction system containing micro-
molar quantities of S02, NH3 and particulate matter in the presence of a
relatively large amount of water indicated that very strong acids such as
dithionate ion, sulfate and bisulfate ions were formed if the observed pH
values of 4 to 5 were theoretically justified (25).
Detailed chemical analyses revealed that acid precipitation (pH approximately
5.6) in the Northeastern United States was caused by the strong mineral acids;
namely, sulfuric and nitric acid (Table 6-14). There is a large array of
other proton sources in precipitation, weak acids and Bronsted acids; however,
although these other acids contribute to the total acidity of precipitation,
they have a minimal influence on the free acidity (ambient pH) of acid pre-
cipitation (31).
Rain and snow were collected in plastic beakers either manually or with a
Wong sampler during 58 precipitation events in 1974 at Yonkers, New York,
approximately 24 km north of the center of New York City. Determinations
were made of total dissolved ionic species, free hydrogen ions, total hydro-
gen ions, sulfate, nitrate, chloride and flouride. Conductivity measurements
ranged from 162 to 618 umhos, pH from 3.4 to 4.9, total acidity from 36 to
557 ueg/1, sulfate from less than 1 to 20 mg/1, nitrate from less than 1 to
14 mg/1, chloride from less than 1 to 7 mg/1 and flouride concentrations less
than 0.1 mg/1. These results indicated that precipitation at a suburban lo-
cation adjacent to New York City was consistently acidic and contained concen-
trations of sulfate, nitrate and chloride, which were similar in values found
for other locations in the Northeastern United States (32).
Rainwater samples possess a time-dependent pH which can be correlated with
the surface wind trajectories (33). Standard procedures for determining
the pH of rain samples usually involve substantial delays from the time of
rainfall to the time of analysis. This assumes that no change in pH occurs
during the storage period, although this is not always true.
Particulates have some effect on acidification in the atmosphere. For ex-
ample, particulates emitted from a stack with no controls can act as a buffer
(4). Jones (34) stated that fly ash buffers acid. However, these conclu-
sions may be the result of unique cases since another study supports the be-
lief that the particulates increase chemical reaction rates: the surface
area increases as r2 and the number of particles increases the rates (8).
141
-------
The electrostatic precipitator is less efficient for smaller particles than
for larger ones so that there are about a million more .01 um than 1 um par-
ticles. Because the surface area of 1 um particles is 1()4- larger, Ananth
e_t al. (8) stated that the number of particles was more significant to in-
creased reactions than the increase in area. In addition to providing a sur-
face area for sulfate formation, the particulates also act as catalysts.
These particulates contain oxides of Fe, Ca, Na, Mg, Pb, V and Cd,and when
they come in contact with S02 and sulfates, they act as catalysts for chemical
reactions (8) either to neutralize (Ca, Mg) or produce (Fe, Pb, V, Cd, Na)
acid (34).
142
-------
REFERENCES
1. Fox, D. G., 1976. Modeling Atmospheric Effects in Assessment of the
Problems. Proc. First Int. Symp. on Acid Precipitation and the
Forest Ecosystem. USDA for Ser. Gen. Tech. Rep. NE-23, pp. 57-87.
2. Milan, M. M. and T. S. Chung, 1977. Detection of a Plume 400 Km from
the Source. Atmos. Envir., 11: 939-944.
3. Bowers, J. F. and H. E. Cramer, 1976. Comparison of Calculated and
Observed Characteristics of Plumes From Two Coal-Fired Power Plants
Located in Complex Terrain. 3rd Symp. on Atmos. Turbulence, Diffusion
and Air Quality, Oct., 1976, pp. 463-469.
'4. Koch, R. C., W. G. Briggs, P. H. Hwang, I. Leichter, K. E. Pickering,
E. R. Sawday and J. L. Swift, 1977. Power Plant Stack Plumes in
Complex Terrain. EPA-600/7-77-020.
5. Kolflat, T. D., 1974. Cooling Tower Practices. Power Engineering,
Jan. (1974): 32-39.
6. Natusch, D. F. S., 1975. Characterization of Atmospheric Pollutants
from Power Plants. APTIC No. 79210, Preprint, Illinois University,
Urbana, 23 p.
7. Likens, G. E. and F. H. Bormann, 1974. Acid Rain: A Serious Regional
Environmental Problem. Science, 184: 1176-1179.
8. Ananth, K. P., et al., 1976. Particle Emission Reactivity. Industrial
Environmental Laboratory NTIS PB-259 300.
9. Shigehara, R. T., R. M. Neulicht and W. S. Smith, 1973. Method for
Calculating Power Plant Emission Rates. Air Pollution Abstract No.
54756, APTIC 79114.
10. Levy, A., D. R. Drewer and J. M. Hales, 1976. S02 Oxidation in Plumes:
A Review and Assessment of Relevant Mechanistic and Rate Studies.
EPA-450/3-76-022.
11. Wilson, W. E., et al., 1976. Sulfates in the Atmosphere - A Progress
Report on Project MIST (Midwest Interstate Sulfur Transformation and
Transport). EPA/600/09, Preprint, Air Poll. Control Assoc. No. 76-
30-06, 19 p.
143
-------
12. Forrest, J. and L. Newman, 1976. Oxidation of S02 in Power Plant
Plumes. NTIS BNL-21698.
13. MacKenzie, J. S., 1976. Cayuga Site Report. United Engineers &
Constructors Inc., Philadelphia, Unpublished.
14. Forrest, J. and L. Newman, 1977. Further Studies on the Oxidation of
S02 in Coal-Fired Power Plant Plumes. Atmos. Envir., 11: 465-474.
15. Freiberg, J., 1976. The Iron Catalyzed Oxidation of S02 to Acid Sulfate
Mist in Dispersing Plumes. Atmos. Envir., 10: 121-130.
16. Brosset, C., 1975. The Acidification of Rain Through the Catalytic
Oxidation of Sulphur Dioxide. Swedish Water and Air Pollution Research
Lab, Gothenburg, Sweden, Rept. B252, 34 p.
17 Garland, J. A. and J. R. Branson, 1976. The Mixing Height and Mass
Balance of S02 in the Atmosphere Above Great Britain. Atmos. Envir.,
10: 353-362.
18. Enviroplan, Inc., 1975. Maximum S0£ Concentrations Produced By a
1000 Megawatt Power Plant. Prepared for Environmental Protection
Agency, EPA 230/1-75-002.
19 Hegg, D., P. V. Hobbs, L. F. Radke and H. Harrison, 1977. Reactions
of Ozone*and Nitrogen Oxides in Power Plant Plumes. Atmos. Envir.,
11: 521-526.
20 Kornberg, H. A. and C. Hakkarinen, 1976. Reactions of Nitrogen
Oxides, Ozone and Sulfur in Power Plant Plumes. Electric Power Re-
search 'institute Report EA-270, Palo Alto, California. NTIS PB-260
640.
21. White, W. H., 1977. NOX-03 Photochemistry in Power Plant Plumes:
Comparison of Theory with Observation. 11(10): 995.
22. Terbe, T. W., et al., 1976. Theoretically Numerical and Physical
Techniques for Characterizing Power Plumes. Systems Applications,
inc., Report for EPRI, NTIS PB-253 099.
23. Ogren, J. A. et al., 1976. Determination of the Feasibility of 03
Formation in Power Plant Plumes. NTIS PB-262-093.
24. Moore, F. K., 1976. Regional Climatic Effects of Power Plant Heat
Rejection. Atmos. Envir., 10: 806-811.
25. Esmen, N. A. and R. B. Fergus, 1976. S02-NHo-Particulate Matter -
H20 Reaction System as Related to the Rainfall Acidity. In:
Proceedings of the First International Symposium on Acid Precipita-
tion and the Forest Ecosystem. USDA For. Ser. Gen. Tech. Rep.
NE-23, pp. 205.
144
-------
26. Boyce, S. D. and S. S. Butcher, 1976. The Effect of a Local Source on
the Composition of Precipitation in South-Central Main. In; Proc.
First International Symposium on Acid Precipitation and the Forest
Ecosystem. USDA For. Ser. Gen. Tech. Rep. NE-23, pp. 309-320.
27. Grether, D. F., 1976. The Effects of a High Stack Coal Burning Power
Plant on the Relative pH of the Superficial Bark of Hardwood Trees.
In; Proc. First International Symposium on Acid Precipitation and the
Forest Ecosystem, USDA For. Ser. Gen. Tech. Rep. NE-23, pp. 913-918.
28. Cogbill, C. V. and G. E. Likens, 1974. Acid Precipitation in the
Northeastern United States. Water Resources Research, 10(6): 1133-1137.
29. Cogbill, C. V., 1976. The History of Acid Precipitation in Eastern
North America. In; Proc. First International Symposium on Acid Pre-
cipitation and the Forest Ecosystem, USDA For. Ser. Gen. Tech. Rep.
NE-23, pp. 363-370.
30. Cooper. H. B. H., J. M. Demo, J. A. Lopez, 1976. Chemical Composition
of Acid Precipitation in Central Texas. In; Proc. First International
Symposium on Acid Precipitation and the Forest Ecosystem, USDA For.
Ser. Gen. Tech. Rep. NE-23, pp. 281-291.
31. Galloway, J. N., G. E. Likens and E. S. Edgerton, 1976. Acid Pre-
cipitation in the Northeastern United States: pH and Acidity.
Science 194: 722-23.
32. Jacobsen, J. S., L. I. Heller and P. VanLeuken, 1976. Acidic Precipi-
tation at a Site Within the Northeastern Conurbation, in; Proc.
First Int. Symp. on Acid Precipitation and Forest Ecosystem, USDA
For. Ser. Gen. Tech. Rep. NE-23, pp. 267-279.
33. Kadleuk, J. A. and U. A. Mohren, 1976. Time Dependence of the pH of
Rain. In; Proc. First Int. Symp. on Acid Precipitation and Forest
Ecosystem, USDA For. Ser. Gen. Tech. Rep. NE-23, pp. 207.
34. Jones, H. C., 1973. Preoperational Atmospheric Monitoring in the
Cumberland Plant Area: The pH and Sulfate Content of Precipitation
Air Pollution Effects Section, Environmental Biology, Muscle Shoals,
Alabama.
35. Radian Corp., 1975. Coal-Fired Power Plant Trace Element Study.
Vol. 1 - A Three Station Comparison. NTIS PB-257 293.
36. Crawford, A. R., et al, 1976. Proceedings of the Stationary Source
Combustion Symposium. Vol. Ill - Field Testing and Survey. Exxon
Research and Engineering Co., NTIS PB 257 146.
37. Curtis, C. R., T. L. Lauver and B. A. Francis, 1977. Foliar Sodium
and Chloride in Trees: Seasonal Variations. Environ. Poll.
14: 69-80.
145
-------
TABLE 6-1
FIXED STACK PARAMETERS (3)
Parameter Mitchell Rammer No. 1 Rammer No. 2
Stack Exit Temp. <°K) 441.3 441.3 441.3
Stack Height (m) 365.8 183.2 183.2
Stack Diameter (m) 10.66 4.75 3.35
Plant Elevation
Above MSL (m) 210 197 197
146
-------
TABLE 6-2
TRACE AND MINOR ELEMENT STACK EMISSION (35)
Station:
Coal Type:
lanission Control:
Element
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chlorine
Chromium
Cobalt
Copper
Fluorine
Iron
Lead
Magnesium
Manganese
Mercury
Molybdenum
Nickel
Selenium
Silver
Sulfur
Titanium
Uranium
Vanadium
Zinc
Fly Ash
(Ib/yr-lOOOMW)
Station II
Station I Sub-bituminous
Sub-bituminous Electrostatic
Venturi Scrubber Precipitator
390,000
41
500
9,800
29
16,000
190
1,300,000
430,000
18^000 '
310
1,400
20,000
210,000
1,200
210,000
5,300
530
8,600
2,400
410
17
28,000,000
19,000
140
9,800
6,000
3,900,000
350,000
33
8.2
<3,000
<50
10,000
18
610,000
330,000
6,500
170
1,400
31,000
110,000
670
90,000
2,000
190
350
3,300
1,400
4.1
27,000,000
24,000
35
2,900
940
2,900,000
Station III
Lignite
Cyclone
Separator
6,900,000
1,800
11,000
<70,000
280
630,000
650
17,000,000
410,000
41,000
2,900
20,000
350,000
8,800,000
3,500
4,200,000
68,000
960
33,000
30,000
3,300
<40
83,000,000
190,000
1,400
28,000
33,000
97,000,000
147
-------
TABLE 6-3
PARTICULATE EMISSION TEST RESULTS (36)
Utility
TVA
So.' Elec.
Gen. Co.
Salt River
Project
Test No.
IB
1C
12C
12D
28A
28B
29
30
26
27A
27B
3B
2A
3D
18B
18C
18E
30
33
27A
27B
34
35
Firing
Condition
Base **
Base **
Low NOx
Low NCx
Base
Base
Base
Base
Low NOX
Low NOx
Low NOx
Base
Base
Base
Low NOX
Low NOX
Low NOx
Base
Base
Low N0x
Low NOx
Low NOX
Low NOX
Av.
Gr/SCF
@ Std.
Cond.
4.46
4.45
3.80
3.55
4.93
4.55
3.80
3.78
4.46
4.68
6.02
3.17
3.48
1.93
4.95
5.35
2.36
2.56
2.59
1.85
2.41
1.96
2.02
Reqd.
Efficiency
£
lb./106
BTU
5.32
5.33
4.56
4.26
6.18
5.70
4.72
4.75
5.48
5.75
7.39
4.27
4.27
2.50
6.26
6.85
2.87
3.11
3.18
2.26
2.94
2.34
2.41
Grams/
106 cal.
9.58
9.59
8.21
7.67
11.12
10.26
8.50
8.55
9.86
10.35
13.30
7.69
7.69
4.50
11.27
12.33
5.17
5.60
5.72
4.07
5.29
4.21
4.34
to Meet
0.1 lb./
106 BTU
98.12
98.12
97.81
97.65
98.38
98.25
97.88
97.89
98.18
98.26
98.65
97.66
97.66
96.00
98.40
98.52
96.52
96.79
96.86
95.58
96.60
95.73
95.85
%
' Carbon of
Particulate
13.04
9.11
6.21
8.08
2.69
1.09
1.69
2.01
5.65
3.37
4.08
.92
1.79
1.98
.80
1.16
1.53
.66
.55
.46
.18
.50
.59
Coal
Ash
Wet, %
14.64
18.27
12.30
12.30
15.00
15.00
16.06
13.28
12.12
9.84
9.84
11.49
5.94
6.04
11.49
6.62
6.04
*
Pub. Ser. Co.
of Colorado
* Analyses not available at this time
** Normal firing but at lower than normal excess air levels
HHV
BTU/lb.
Wet
11,281
10,258
10,622
10,622
11,690
11,690
11,461
11,398
11,752
11,632
11,632
10,210
11,068
11,186
10,210
10,780
11,186
-------
VO
TABLE 6-4
AIHL ANALYSES OF SULFUR. VANADIUM AMD FLY ASH CONTENTS OF FUEL OILS BURNED DURING STUDY (36)
Date
9-10-74a
9-ll-74a
9-12-74
10-01-74b
10-04-74
10-ll-74b
10-17-74b
10-25-74
10-30-74
11-07-74
Power Plant
Moss Landing
Moss Landing
Moss Landing
Haynes
Haynes
Haynes
Haynes
Edison
Edison
Edison
% S (w/w)
0.35 + .03
0.40 + .006
Burned Natural Gas
0.45 + .01
0.45
0.46 + .01
0.455 + .005
0.44
0.45
0.45
% Ash (w/w)
0.027 ± .002
0.016 + .001
0.0075 + .0007
0.008
0.0075 + .0007
0.0075 + .002
0.007
0.006
0.012
V, ppm (w)
13.0 + 3.4
13.4 ± 1.3
9.1 + .5
11.3
10.7
10.6 +1.1
14.5
13.4
20.5
V as 7.
of Ash
5.0
8.4
12
15
14
14
21
22
17
a. Analyses shown for this date are means for 6 samples.
b. Separate samples taken for each of two boiler units operating on sampling day. Values shown are
means for the two units.
-------
TABLE 6-5a
TRACE METALS IN FLY ASH AS A FUNCTION OF PARTICLE SIZE (8)
Particle _ Concentration, ppm _ ____
Size: 25 urn 12.5 urn 10 um 3.5 urn 1.5 urn
Element
Al 67,000 54,300 57,300 63,600 59,300
B 300 500 500 500 500
Be 21222
Cd s5 *5 s5 s5 100
Cr 130 130 130 300 300
Cu 150 150 200 200 200
Fe 40,000 59,000 43,500 35,500 32,300
Mn 200 240 290 390 500
Ni 300 200 200 300 300
Pb 300 200 300 300 500
v 200 200 300 200 200
by
a7 Sample collected from a coal- fired steam power plant and analyzed
~ neutron activation and spark source mass spectrometry.
TABLE 6-5b
CONCENTRATION AND SIZE OF TRACE METAL PARTICLES IN URBAN AIR (8)
. Particles
Concentration HMD*-' < 1 um
Metal (ug/m3)
Fe 0.6 -1.8 2.35-3.57 12-35
Pb 0.3 -3.2 0.2 -1.43 59-74
Zn 0.1 -1.7 0.58-1.79 14-72
Cu 0.05 -0.9 0.87-2.78 16-61
Ni 0.04 -0.11 0.83-1.67 28-55
Mn 0.02 -0.17 1.34-3.04 13-40
V 0.06 -0.86 0.35-1.25 41-72
Cd 0 -0.08 1.54-3.1 22-28
Ba 0 -0.09 1.95-2.26 20-31
Cr 0.005-0.31 1.5 -1.9 45-74
Sn 0 -0.09 0.93-1.53 28-55
Mg 0.42 -7.21 4.5 -7.2 17-23
a/ The mass median diameter (HMD) represents the approximate "average"
~ aerodynamic particle size, i.e., 507. of the particles are above this
size and 507. are.below.
Note: The unit symbolized by "um" is a micron, i.e., 10~6 meters. Accord-
ingly "ug" represents a microgram.
150
-------
TABLE 6-6
AVERAGE AIR POLLUTION EMISSIONS FROM VARIOUS POWER PLANTS (6)
Fuel
Goal
Oil
(Values are presented as g/kg of fuel)
Particles*
85
1.7
.1 Gas 2.7
(1-E)
(1-E)
(1-E)
CO
0.25
0.07
negl.
HC NOjj
0.1 10
0.5 17
negl. 70
SOV**
—X
19S
19S
19S
HCOH
0.002
0.1
0.2
* E is the mass collection efficiency of the control equipment,
** S is the percent sulfur content of the fuel by weight.
151
-------
TABLE 6-7
TYPICAL COMPOSITION OF COAL FLY ASH
(Weight Percentages of Oxides)
Major Constituents
A1203 S102 Fer03 KjO CaO
14-30 22-60 3-21 .2-3.5 .5-31.0
Minor Constituents
Li20 Na20 MgO Ti02 PjOj S04*
,01-.07 .2-2.3 .7-12.7 .6-2.6 .1-1.1 .1-2.2
* Soluble Sulfate
152
-------
TABLE 6-8
Element Concentration, ppm
Element
Al
At
Ba
Br
Ca
Cd
Ce
Cl
Go
Cr
Cs
Cu
Eu
Fe
Ga
H£
Ho
K
La
Mg
Mn
Ma
Nl
Pb
Rb
Sb
Coal
10,440
4.45
65
3.7
4,340
0.47
8.2
914
2.9
18
1.1
8.3
0.1
10,850
4.5
0.4
0.122
1,540
3.8
1,210
.8
696
16
4.9
15.5
0.5
Slag
102,300
18
500
2
46,000
1.1
84
100
20.8
152
7.7
20
1.1
112,000
5
4.6
0.028
15,800
42
12,400
295
5,000
85
6.2
102
0.64
Inlet Fly Ash
90,900
110
465
4
25,200
8.0
84
200
39
300
13
140
1.3
121,000
81
4.1
0.050
20,000
40
10,600
298
10,100
207
80
155
12
Outlet Fly Ash
76,000
440
750
...
32,000
51
120
...
65
900
27
...
1.3
150,000
_..
5.0
...
24,000
42
...
430
11,300
...
650
190
55
Concentration Ratios
Slag/
Coal
9.8
3.6
7.7
0.5
10.6
2.3
10.2
0.1
7.2
8.4
7.0
2.4
11.0
10.3
1.1
11.5
0.2
10.3
11.0
10.2
8.7
7.2
5.3
1.3
6.6
1.3
(Inlet (Outlet
fly fly ash)/
ash)/ (inlet
slag fly ash)
0.9
6.1
0.9
2.0
0.5
7.3
1.0
1
1.9
2.0
1.7
7.0
1.2
1.1
16.2
0.9
1.8
1.3
1.0
0.9
1.0
2.0
2.5
12.9
1.5
18.8
0.8
4.0
1.6
_
1.3
6.4
1.4
.
1.7
3.0
2.1
-
1.0
1.2
-
1.2
-
1.2
1.0
-
1.4
1.1
-
8.1
1.2
4.6
-------
TABLE 6-8 (cont'd.)
Element Concentration, ppm
Concentration Ratios
Element
Sc
Se
Si
Sm
St
Ta
Th
Tu
U
V
Zn
Coal
2.2
2.2
23,100
1.0
23
0.11
2.1
506
2.18
28.5
46
Slag
20.8
.080
229,000
8.2
170
0.95
15
4,100
14.9
260
100
Inlet Fly Ash
26
25
196,000
10.5
250
1.4
20
5,980
30.1
440
740
Outlet Fly Ash
36
88
9
___
1.8
26
10,000
1,180
5,900
Slag/
Coal
9.5
0.0
9.9
8.2
7.4
8.6
7.1
8.1
6.8
9.1
2.2
(Inlet
fly
ash)/
slag
1.2
310
0.9
1.3
1.5
1.5
1.3
1.5
2.0
1.7
7.4
(Outlet
fly ash)/
(inlet
fly ash)
1.4
3.5
-
0.9
-
1.3
1.3
1.7
-
2.7
8.0
-------
TABLE 6-9
SPECIFIC CONCENTRATIONS (ug/gm) AND VOLUME CONCENTRATIONS
OF TRACE ELEMENTS IN COAL AND OIL FLY ASH (6)
element
As
Ba
Be
Cd
Go
Cr
Cu
Hg
Mn
Mo
Hi
Pb
Sb
Se
Sn
V
Zn
Coal Fly
ug/gm
10-500
100-1000
1-10
10-100
10-100
10-1000
10-1000
0.1-1.0
100-1000
10-100
10-1000
100-5000
1-100
10-100
1-10
50-5000
1000-10,000
Ash
ug/ra3
60-90
30-110
—
—
1-5
8-20
—
•»•»
12-40
—
10-25
10-15
1-2
8-18
0»4»
5-60
20-70
Oil Fly Ash
UK/Btt
30
9000
—
—
90
66
—
—
45
—
—
—
5
5
—
100-100,000
3500
ug/m3
5
1600
—
—
16
12
—
•••
8
—
—
—
1
1
—
1000-1200
640
Note: The unit symbolized by "ug" is a microgram, i.e., 10"6 grams.
155
-------
TABLE 6-10
AVERAGE F FACTORS FOR VARIOUS FOSSIL FUELS (9)
Fuel
Coal - Anthracite
Coal - Bituminous, Lignite
Oil - Crude, Residuum, Distillate, Fuel Oil
Gas - Natural, Butane, Propane
F Factor. scfd/106 Btu
-------
TABLE 6-11
MECHANISMS THAT CONVERT SULFUR DIOXIDE TO SULFATES (11)
in
Mechanism
1. Direct photo-
oxidation
2. Indirect photo-
oxidation
3. Air oxidation in
liquid droplets
4. Catalyzed oxidation
in liquid droplets
5. Catalyzed oxidation
on dry surfaces
S02
SOo
NH3
SO
Overall reaction
light, oxygen
water
smog, water. NOx
V°4
«jn
S02 organic oxidants,
hydroxyl radical (OH')
liquid water
NHj +
oxygen, liquid water „ »
2 heavy metal ions
OV
so2
SO/
car
, particulate
bon, water *. 4
Factors on which
sulfate formation
primarily depends
Sulfur dioxide concen-
tration, sunlight
intensity.
Sulfur dioxide concen-
tration, organic
oxidant concentration,
OH*,
Anmonia concentration.
Concentration of heavy
metal (Fe, Mn) ions.
Carbon particle concen-
tration (surface area).
-------
TABLE 6-12
PLANTS STUDIED BY BNL (12,14)
Name of Plant
1. Port Jefferson Plant, Port
Jefferson, N.Y.
2. Northport Plant, Northport,
N.Y.
3. Albany Plant, Bethlehem, N.Y.
4. Devon Plant, Milford,
Connecticut
5. Labadie Plant, Missouri
6. Portage des Sioux Plant,
West Afton, Missouri
7. Muscle Shoals Plant, Alabama
(TVA)
8. Kyger Creek Plant,
Charleston, West Virginia
Capacity, MWe
467
1,160
400
454
4 x 600
2 x 500
5 x 290
1,000
Fuel Used
oil
oil
oil
oil
3% Sulfur Pulverized Coal
37, Sulfur Pulverized Coal
Pulverized Coal
Coal
158
-------
TABLE 6-13
ENVIROPLAN PLANT OPERATING DATA (18)
Effective plant size
(megawatts)
Stack height (feet)
Stack diameter (feet)
Gas exit velocity
(feet/second)
Gas exit temperature
Ratio of density of exit
gases to density of ambient
air at same temperature
S(>2 emission rate (tons/hour)
Largest annual average 802
concentration (ug/rn^)
Mpvfimm 2&-hnnr SOj concen-
tration per year (ug/rn^)
Maximum 3-hour SOo concen-
tration per year (ug/m3)
Heat rate (BTU's/KWH)
Pounds of air used'*'
Case One
(scrubber)
1000
400
24.4
100
170°F
0.9929
5.610
1.69
55.01
234.28
9350
11.8416
Case Two
Case Three
(scrubber) (low-sulfur coal)
1000
400
26.3
100
250°F
0.9929
5.786
0.98
40.69
184.32
9644
11.8416
1000
400
24.5
100
300°F
1.0180
5.400
0.95
38.44
173.90
9000
11.8416
per Ib. of coal burned
@ 20% excess air
Total Ibs. of coal^ '
burned per hour
Total Ibs. of air
used per hour
779,167
803,667
750,000
Total Ibs. of
vapor used per hour
9.2266 x 106 9.5167 x 106 8.8812 x 106
0.8811 x 106 0.9088 x 106
159
-------
TABLE 6-13 (cont'd.)
Case One Case Two Case Three
(scrubber) (scrubber) (low-sulfur coal)
Total volume of air(d) 40,568 47,156 47,112
(cubic ft. per second)
Total volume of water 6,228 7,240
vapor (cubic ft. per
second)
Total volume of exit 46,800 54,396 47,112
gases at exit tem-
perature (cubic ft.
per second)
Note: The unit symbolized by "ug" is a microgram, i.e., 10"*> grams.
160
-------
TABLE 6-14
ON 11 JULY 1975 f3n *•
Component
H^COg
day
•c
Dissolved Al
Dissolved Fe
Dissolved Mn
Total Organic Acids
HH03
H,SO,
Concentration
in
Precipitation
fasti
0.62
5
0.53
0.050
0.040
0.005
0.43
2.80
5.60
Contribution to
Free acidity at
pH 3.84
fueq)*
0
0
0
0
0
0
2
40
102
Total acidity in
a titration to
oH 9.0 fueq'i*
20
5
29
5
2
0.1
5.7
40
103
Total
144
210
* microequivalents per liter
161
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SECTION 7
PLUME INTERACTION
7.1 INTRODUCTION
Cooling towers remove heat from condenser cooling water by evaporation and
reject this heat to the air in the form of a hot and humid plume. The cooling
tower plumes consist of water vapor saturated air and liquid water in the form
of suspended droplets. The emissions from the stacks of fossil-fueled plants
are primarily sulfur oxides and nitrogen oxides in addition to the usual con-
stituents C02, N2, 02, particulates such as fly ash and trace elements. Vapor
plumes from cooling towers are similar in most respects to smoke plumes from
stacks, however, size differences are very great. Whereas smoke stacks are
typically less than 100 ft in diameter, many modern cooling towers have dia-
meters of several hundred feet.
The buoyancy of a plume depends on the mixing between the plume and its en-
vironment. For a given set of initial velocity and temperature conditions,
a large plume will rise faster and reach a greater altitude. A vapor plume
starts to cool immediately and results in a visible cloud of liquid droplets.
This condensation will contribute to the buoyancy of the rising plume by re-
leasing the latent heat of vaporization.
The total buoyancy of the cooling tower plume at a fossil-fired power plant
is at least three or four times the buoyancy of the stack plume (1). Stacks
are usually higher than adjacent cooling towers, but the total heat output
from the stack gases is less than that from the cooling tower plumes. Con-
sequently, the final plume rise from both sources is nearly the same, about
500 m. Thus, it is not surprising that the stack and cooling tower plumes
are often observed to merge (1).
The presence of cooling towers (especially hyperbolic cooling towers which
discharge their plumes at high altitude) at fossil-fuel power plants with
stacks of heights similar to those of the towers engenders the distinct pos-
sibility that under the "right" meteorological conditions and relative ori-
entation of the stack and the cooling towers the plumes will commingle. This
interaction of large quantities of water with high concentrations of sulfur
dioxide may reasonably be expected to lead to the formation of sulfurous and/
or sulfuric acid droplets (2).
Generally, natural draft cooling towers are built in groups of two to four
spaced 200 to 500 m apart. Mechanical draft towers are traditionally built
in lines or "banks", in which 10 to 20 fan units are located in one 200-m
162
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long structure. Recently, some mechanical draft units have been arranged
into doughnut-shaped structures, presumably to increase the plume rise from
the group (1).
The separating distance between the boiler smoke stack and the cooling
towers(s) is most often determined from other plant layout considerations;
for example, the availability of land for the plant. When the sources such
as the stack and the cooling towers are very close to each other, the plumes
will at times combine or commingle. If the plumes are very far apart and the
atmospheric conditions are stable, i.e., the winds are calm, the plumes will
rise separately. Wind speed and direction play an important role in the
plume merger. Thus, the wind rose at the plant location should be used to
determine the relative location of the cooling towers with respect to the
stack while establishing the plant arrangement and layout.
7.2 CATEGORIES OF PLUME INTERACTION
Sanaa (3) classified the interaction between the plumes broadly into three
different cases (Figure 7-1). In the first case, the tower plume containing
suspended droplets of water mixes with the relatively hot stack plumes. This
may result in a temporary defogging; but chemical reactions nevertheless take
place, and the products will eventually be deposited as the mixed plume cools
along its path. In the second case, the slightly cooled stack plume encoun-
ters the tower plume with its entrained liquid water, absorbing the oxides
and resulting in a corrosive drizzle. In the third case, both plumes spread
more or less in parallel and intersect at some distance away from their
sources. This distance depends upon the wind velocity, atmospheric stability
and the distance between the stack and the cooling tower.
7.3 MECHASISM OF INTERACTION
The mechanism of interaction between two neighboring plumes is not well
understood (4). In general, it is not known if evaluation of plume effects
near the tower will enhance plume performance predictions further downwind.
Davis (5) modified a single buoyant jet model of Hirst to include effects of
neighboring jet interaction for possible application to multiple-cell mechan-
ical draft cooling towers. The merging processes of neighboring plumes with-
in the zones of flow establishment and established flows of Hirst were used
by Davis to define a merging zone explaining the asymmetry generated by
interaction.
In this zone, it was assumed that the merging plumes make additive contribu-
tions both with respect to temperature and velocity. The merging zone con-
tinues until the profiles are smooth, i.e., the difference between neighbor-
ing temperature peaks and valleys is small. Recently, Kannberg (6) collected
a large set of laboratory data for a two-dimensional plume source applicable
to the analysis of Davis and was able to adjust the entrainment coefficients
in the model to produce a very good fit. with the data (Figure 7-2).
Although this phenomenon of interaction has been verified at plume level, the
question of whether there is an attendant environmental impact, i.e., whether
detectable quantities reach receptors at the ground, is still highly prob-
163
-------
lematic (2).
When plumes merge, chemical reactions may lead to the production of undesir-
able substances such as sulfates. It is known that the conversion of S02 to
sulfates by oxidation occurs more rapidly in a humid environment. However,
no models of this phenomenon have yet been suggested. Current research ef-
forts are studying chemical reactions in turbulent mixtures (1), but no one
has developed a useful practical model. Donaldson and Hilst (7) pointed out
that chemical reactions in inhomogeneously mixed fluids, such as a stack plume
merging with a cooling tower plume, may proceed slower than reactions in a
homogeneously mixed fluid. Studies by Thomson (8) in the Keystone plume may
permit the development of practical models for this phenomenon (1).
The Chalk Point Cooling Tower project studied interactions between the cool-
ing tower water vapor plume and the fossil power plant stack gas plume, es-
pecially the potential for the formation and the subsequent fate of sulfuric
acid mist (2).
A model of the particulate distribution at the ground level due to interaction
of the cooling tower plumes with stack plumes indicated that the rates of the
chemical reactions are not sufficiently known to make useful or accurate pre-
dictions concerning the quantities of the various species. However, for pur-
poses of this study, assuming that only the lumped principal reactions are of
importance is justified because of the relatively short residence times before
mixing. The concentration distribution, C, of these reactants in the stack
plume can be expressed by means of the equation:
C(x,y,z) = Q/Or<7x *zx u) expj-%
where Q is the intensity of the source, H the effective stack height, u the
mean wind speed and the d's are standard deviations from the Gaussian dis-
tribution.
The mixing zone height, ZM, is approximately equal to that of the tower effec-
tive height. Thus if complete mixing of the plumes at the zone of interaction
is assumed, the source strength, M, can be computed for the mixed plume. The
effect of the energy release due to mixing and reactions is insufficient to
influence the plume height. Therefore, the ground-level concentrations of
the particulate aerosol distribution at any downwind distance can be computed
by means of the simplified equation (3).
C(x,o,o) - M/Ordx dzx u) exp|(-%)(ZM/dzx)2|
This shows that the ground-level concentration (GLC) is dependent on the ef-
fective stack or tower height, wind speed, and intensity of the source or the
source strength. However, the above equations do not have any term relating
to the separation distance, L, between the cooling tower and the stack.
164
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7.4 ACID PRECIPITATION ENHANCEMENT
Insufficient data is available for stack gas-cooling tower plume interac-
tions. For the most part, existing literature provides unsophisticated ex-
planations and non-quantitative descriptions. Three field studies included
some quantitative analyses of plume merging cases (9,10,11). The rest of the
literature deals with unsubstantiated hypothetical cases. The field studies
are site specific in their analyses so that extrapolation to general circum-
stances is unreliable. For instance, the Chalk Point Study (9) analyzed the
stack plume in which a wet scrubber was used whereas Dittenhoefer et al. (10)
and Stockham (11) analyzed the stack plume at the Keystone plant which has no
scrubber. These and other field studies are presented in detail in a later
section.
A completely hypothetical case study was performed in an environmental li-
censing application in New York State by the Niagara Mohawk Power Corpora-
tion for the Lake Erie Generating Station (12). This study included a nu-
merical model estimation of the chemical decay of S(>2 to 864 ; removal by
precipitation scavenging was also predicted. The estimates of reaction
rates, deposition rates and removal efficiencies were chosen on the basis of
data in the literature although some judgement in the data interpretation
was necessary. The data used to estimate rates and removal were obtained in
laboratory experiments, making its applicability to atmospheric processes
questionable. Because of these problems, only the worst case and annual
coverage calculations are included. The results are presented in Tables 7-1
through 7-4.
Measurements of rainwater pH after passing through both the stack and cooling
tower plumes are virtually non-existent. The role of precipitation scaven-
ging of 804™ is not obvious, possibly because of several factors: the small
emission of 802 from a particular stack, the inefficient process of precipi-
tation scavenging by droplet-particle collision, and the short time that the
S02 c*m be absorbed by drops passing through the plume.
For example, Li and Landsberg (13) measured the rainwater pH after drops
passed through both the stack and cooling tower plumes at Chalk Point for
several rainfalls and obtained values from 3.4 to 4.6 during operation of the
small stacks. The pH ranged between 4.0 to 4.8 for rainfall when the large
stack (Unit 3) commenced operation. After the cooling tower became opera-
tional, pH frequency distribution shifted to a higher mode (4.0 to 4.5 in-
stead of 3.5 to 4.0). Even though the S02 emissions were higher during the
postoperations period, no explanation was offered for the observed increase
in pH. Perhaps, the cooling tower plume diluted the acid already present.
Apparently, sulfur dioxide oxidation was not a significant factor at the
site.
Other studies considered only rainwater pH resulting from the stack plume
interaction with the atmosphere. Dana et al. (14) found that sulfate concen-
tration in rainwater due to the plume's presence did not appear to be signi-
ficantly affected at downwind distances less than 10 kilometers (Section
7.5.5). The only measurable plume-related species collected were S02 and the
H ion. The lowest rainfall pH under the plume measured 3.89. Rainfall rates
165
-------
varied from 0.8 to 2.4 mm/hr, and the average drop diameter was 0.03 to 0.1
cm. The H2S04 scavenged by rain was calculated to be 178 Ib/hr, or 45% of
the amount emitted from the stack. Hence, the H2SO^ from S02 oxidation was
minimal. The data of Hales et al.(15) also agreed with that of Dana et al.
Although increases in SO^ were observed in rain below the plume, the increase
was not obvious. The H ion concentration distribution did reflect the plume
location.
From a laboratory experiment, Esmen et al^. (16) concluded that rainwater
acidity through atmospheric scavenging accounted for the formation of very
strong acids. This conclusion was based upon the kinetics of a reaction sys-
tem containing micromolar quantities of S02, NH3 and particulates in the
presence of large volumes of water. However, the results of the Chalk Point
study (17) contradicted the results of Dana et ail. (14) and Hales e_t al. (15)
by demonstrating that for post-operational periods the total SO^ in precipi-
tation was three times that for remote areas. The reasons for this dichotomy
may be explained by two observations. One, limestone dust and fly ash buffer
acids (18,19). Two, oxides of Fe, Ca, Na, Mg and Pb play an important role
as catalysts in acid rain, but their role depends on their concentration and
accessibility to 803.
Plume rise may be a function of buoyancy, and in some cases, the plume rise
from the stack and cooling tower may coincide. Plume rise from a single
stack where nearly all emissions are less than 20 microns has been described
(20). Murphy (21) discussed the plume rise from a chimney row of single
source moment unless plumes in a stable atmosphere. However, cooling tower
plume rise is more complex due to the influence of latent heat release during
condensation and the plume mass on plume rise. Latent heat provides addi-
tional buoyancy, although Hanna (1) contends that the difference is not suf-
ficient to alter the rise significantly.
Part of the cooling tower plume with droplets whose mass is not large enough
to be completely non-Gaussian may have a tendency to drift downward over dis-
tances. In effect, the plume centerline may have a tendency to fall over a
limited distance after leaving the tower as the height distribution of the
mass changes. For a single tower, numerous models exist to estimate the
plume rise (1,22). The evaluation by Argonne indicates that some of these
are fairly reliable (22). Unfortunately, this is not the case for multiple
cell cooling tower plume rise models (R. A. Carhart, pers. comm.). Hanna
and Gifford (23) theorized that the Briggs' formula for the multiple plume
enhancement factor could be used for multiple cell cooling towers although
they had no field evidence for confirmation.
In summary, additional sulfate production during visible merging of cooling
tower and stack plumes, dispersion both from atmospheric turbulence and
structural wake effects, plume rise from buoyant effects and meteorological
conditions are processes useful in estimating the probability and quantity
of acid drift-deposition. However, most of the work to date has been of a
hypothetical nature. Field measurements are rare. Model generalizations
are tenuous not only because of the few verified cases but also because of
the different plant designs. Field data for stack gas-mechanical draft cool-
ing tower plume merging are non-existent. Dispersion enhancement resulting
166
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from structural wake effects has not been extensively studied. In addition,
wind tunnel studies indicate that small changes in structural design might
have large impacts on the dispersion in a region out to about 10 building
heights, thereby rendering general application of individual studies unreli-
able. No reliable process exists to determine the revision in atmospheric
dispersion within a cooling tower structure wake and how the wake will affect
plume rise. Buoyancy effects for plume rise prediction are somewhat better
parameterized for various plant designs. At least the theoretical formulae
for natural draft cooling tower plume rise due to buoyancy has been verified
from field studies. Mechanical draft cooling tower plume rise formulae are
not nearly as trustworthy.
Meteorological conditions conducive to stack gas-cooling tower plume merging
have been established reasonably well in the literature,if it is assumed that
an important criterion for acid drift-deposition is the commingling of the
stack and a visible cooling tower plume. The longer than usual visible cool-
ing tower plumes occur during light winds, high relative humidity (greater
than 80 or 85%), low temperatures, and stable temperature lapse rates. The
light winds and stable temperature lapse rates assure low dispersion rates
both within and beyond the plant wake region. High relative humidity reduces
the evaporation rate for the cooling tower plume so that plume length is en-
hanced. The cold temperature may be a reflection of a stable temperature
lapse rate rather than an additional causative factor for visible cooling
tower plume enhancement. However, the longer plumes do generally occur in
winter rather than summer. Knowledge of meteorological conditions, cooling
tower and stack plume rises and orientation of the stack and cooling tower
permits the estimation of the frequency for stack gas-visible cooling tower
plume merging. Orientation is significant because if the wind is perpendicu-
lar to the stack-cooling tower axis, dispersion will have an increased oppor-
tunity to mitigate both the droplet concentration of the cooling tower and
the chemical concentration of the stack gas before merging, i.e., the plumes
will merge further downwind.
7.5 FIELD STUDIES
Field studies have been conducted in several fossil-fired power stations, and
plume merger and plume interaction have been investigated. This section
examines the results of such studies at the following power plants: Key-
stone; Chalk Point; Ratcliffe and Rugeley (Staffordshire), U.K.; Mitchell &
Kammer; Centralia; and, Amos. A complete summary is found in Table 7-8.
7.5.1 Keystone Station
The Keystone electrical power generating station is located near Sheluc,
Pennsylvania. It is a mine-mouth, coal-fired plant with twin units, each with
a capacity of 900 MWe, and a total capacity of 1800 MWe. Associated with
each unit are a chimney stack, 244 m in height, and two natural draft, hyper-
bolic cooling towers each 99 m in height, 75.2 m diameter at the base. The
cooling towers were designed and built by Research-Cottrell, operate with
counter-current flow and have a total cooling capacity of 560,000 gpm. The
167
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tower design bases are: range^1) = 28°F, approach^) • 18°F, wet bulb » 72°F,
dry bulb • 86.5°F, and relative humidity » 50%. The center-to-center distances
between the stack and the cooling towers are 830 ft and 1125 ft.
At the Keystone Plant, about 10,000 gpm of water were evaporated and 120 million
Btu/min of heat released through the cooling towers when the station operated
at 80-86% of its rated 1800-MWe capacity. The plume rose to about 200 m and
travelled downwind about 200 m before evaporating.
Observations recorded at the Keystone plant can be summarized as follows:
1. When the ambient temperature was 25-30°F and the relative
humidity was high (80%), the visual portion of the plume
persisted for many miles and could be seen to merge with
the stratus cloud cover. At higher ambient temperatures
and lower relative humidities, the visible plume attained
an altitude of 200 meters and a downwind distance of 100-
200 meters.
2. In most instances, the cooling tower plume commingled with
the stack plume. The most significant differences were the
decrease in relative humidity from about 80% to 62% and a
decrease in S02 concentration near the station from about
0.03 ppm to 0.017 ppm. No enhancement of the ground-level
humidity was indicated as a result of the overhead plume.
The humid plumes from the cooling towers became mixed with the discharges
from the power station stacks at downwind distances ranging from 200 to 1,000
meters. The plumes from the two sources remained mixed at downwind distances
of 11,270 meters, the farthest point at which aerial traverses were made.
While the cooling tower plume was visible normally 200 to 300 meters, the
mixing was visually observed. Evaporation of the cooling tower plumes was
confirmed by the profiles (Figure 7-3) of the humidity and sulfur dioxide
obtained along the axis of the plume path (Figure 7-4). Cascade impactors
mounted on a helicopter sampled droplets in the merged Keystone plumes. Re-
sults indicated that the number ratio of acid drops at pH = 4-5 to neutral
drops at pH ** 6-7 increased from .05 to 3.0 as relative humidity increased
from 50% to 95%. Furthermore, the smallest drops had the highest acidity.
Thomson (8) also reported that the smallest drops, i.e., those found in the
last stage of the impactor, were associated with the highest acid concentra-
tions .
The lack of correlation between the acid droplets and sulfur dioxide concen-
trations suggested that the plumes did not mix uniformly but may have just
commingled. It was determined that acidity in the stack plume increased when
the S02 and cooling tower plumes merged. Similar results, also verified on
the Keystone plant, were reported by Thomson (8).
When relative humidity was low, stability near-neutral, and solar radiation
intense, the production of new Aitken particles was the primary mechanism of
"(1)Temperature difference between hot water in and cold water out.
(2) Temperature difference between cold water out and inlet air wet bulb.
168
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S02 oxidation. In the case of merger (100% relative humidity) between the
stack plume and the cooling tower plume, the formation of sulfate on existing
particles predominated over the formation of new particles. During cases
with intermediate meteorological conditions, both processes were of equal im-
portance.
Out of seven flights of a light aircraft making crosswind and longitudinal
plume penetrations, in only one case, flight no. 4, did significant inter-
action between the stack plume and cooling tower plume occur. During this
flight, the visible merged plume was detected out to 50 km downwind of the
plant (over 110 min of plume travel time) and could be attributed to high
atmospheric relative humidity, a stable lapse rate and low wind speed. Al-
though similar conditions of stability and wind speed prevailed during flight
no. 7, the slightly lower relative humidity and higher temperature caused the
liquid plume to evaporate very near the towers and hence no visible merging
was observed.
A significant growth of particle size was observed only in flight no. 4, due
to absorption of 862 from the stack plume by liquid water of the cooling
tower plume (see Table 7-5). Many of these droplets grew to sizes of 0.3
microns or greater. Thus, sulfate production accounted for much of this par-
ticle growth. The highest rate of particle growth (flight no. 4) occurred
when the average plume temperature was at its lowest (1.6°F); lowest growth
(flight no. 5) occurred during the case of highest temperature (62.1°F).
Thus, temperature played a significant role in conversion of S02 to sulfate
within the commingled power plant plumes. The conversion rate was of the
order of 0.57. per hour. The sulfate particles collected in cases of low rel-
ative humidity and a non-merging plume were of significantly smaller size
than those found during the merging plume case. The increase in modal sul-
fate particle diameter was about 0.3 to 0.5 microns (10).
The merged plumes produced an increase in the number of Aitken particles bet-
ween 89 and 106 minutes downwind along with a very rapid Increase in large
particle concentrations (Figures 7-5 and 7-6). When the liquid plume disin-
tegrated (visible plume disappeared), the large particle concentration de-
creased although it was almost one order of magnitude larger than the original
stack value. It was believed that the chemical mechanisms caused a rapid
growth of large particles (Figure 7-7). When the ratio of Aitken to large
particles is nearly equal, then particle growth is comparable to particle
generation as demonstrated in three of the flights (Figure 7-8).
From this data, it is apparent that the stack plume merging with the visible
cooling tower plume does affect sulfate production. Although Dittenhoefer
and dePena (10) were not able to measure the acidity of the droplets, they
did make a projection for the conversion of SO2 to H2S04. Based on the as-
sumption that particles are droplets of H2S04 at 95% relative humidity and
that the actual mass of solute contained within each size interval followed
the Kohler curves for H2S04, the conversion rate of S02 to H2S04 was esti-
mated to be approximately 0.5 percent/hr. This is a crude estimate, but the
order of magnitude is believed to be correct.
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Meteorological conditions which enhanced visible plume merging of the stack
and cooling tower plumes to 50 kilometers were high relative humidity (95%),
stable temperature lapse rate and light winds. Similar conditions for
another flight existed, but no visible merging was observed; the relative
humidity was slightly lower and the ambient temperature higher.
Effluents other than S02 and water from the stack and cooling tower may also
mix (11). Mixing was verified by the presence of acid droplets in the visi-
ble cooling tower plume and by the humidity and sulfur dioxide profiles along
the axis of the plumes after the cooling tower plume evaporation. In all in-
stances, the humid cooling tower plumes commingled with the stack plumes. In
the aircraft measurements, the droplets were classified in pH intervals
(Figures 7-9 through 7-13). As the relative humidity increased so did the
acid drop concentration. The SC>2 concentration had little effect on the acid
concentration possibly because of non-uniform mixing. Even though the stack
is 244 m and the cooling tower 99 m high, the buoyancy of the plumes rendered
the height difference ineffective; the equilibrium height of both the stack
and cooling tower plumes were approximately the same level. The plumes
merged at distances from 200 to 1,000 m downwind. They remained merged until
the end of the aircraft traverses at 11 km. The frequency of merging in this
study concurred with observations at the AMOS plant by Kramer et al.(24) in
which the merging of the stack and cooling tower plumes occurred 47 out of
54 times within a short distance of release. There was no measurement of
chemicals after the merging in the latter study. It should be noted that
all of these field studies have involved natural draft cooling towers. To
date, stack-cooling tower plume merging field studies have not been performed
on mechanical draft cooling towers.
7.5.2 Chalk Point Station
Chalk Point Station of the Potomac Electric Power Company (PEPCO) is located
at the confluence of the Patuxent River and Swanson Creek in Prince Geroges
County, Maryland, about 40 miles SE of Washington, D.C. Units 1 and 2 of the
station are coal-fired, and base-loaded and employ once-through cooling.
Units 3 and 4 are designed for peaking (cycling) services using oil as fuel
and are rated at 660 MWe gross and 630 MWe net.
The Marley cooling towers for Units 3 and 4 are 400 ft (100 m) high and 283
ft (71 m) in diameter at the base (shell support). The crossflow cooling
towers have a total cooling capability of 260,000 gpm. The design bases for
the towers are: range =• 30°F, approach =» 12°F, wet bulb = 78°F, dry bulb =
93.5°F, and relative humidity - 50%. The diameter at the tower exit is 180
feet. The plant uses brackish water from the river with an average salt con-
centration of 7000 ppm. The boiler flue gases pass through a wet venturi
scrubber that uses brackish water. The stack plume, therefore, may contain
NaCl, H2S04 and S(>2 in addition to water.
Measurements in the plume interaction zone followed the test plan illustrated
in Figure 7-14. Measurements of S02 and H2SO^ mist concentrations were made
in the interaction zone. S02 concentrations were measured by a MRT Theta
electro-chemical cell sensor. l^SO^ acid concentrations were measured by
(a) chemical film sampler for droplets larger than 30 microns in diameter,
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and (b) the cascade impactor for droplets smaller than 30 microns. In both
cases, the droplet collection surface was treated with quinine which reacts
with H2S04 to form Stabler 7 fluorescent quinine sulfate which was detected
by ultraviolet light.
The boiler exhaust system includes a wet venturi scrubber that adds a signi-
ficant amount of water to the boiler gas plume in the form of both droplets
and vapor. Temperatures and concentrations of water and boiler plume con-
stituents are much higher within the plume prior to dispersion. Reaction
rates are, therefore, likely to be much higher in the exhaust system than at
any time after emission from the stack. Therefore, it appears that reactions
involving S(>2 and water would occur within the boiler duct and stack system
prior to mixing of the stack gas plume with the cooling tower plume. Since
the boiler plume already contains sufficient water for the chemical reactions
to occur, the addition of more water from the cooling tower plume during
mixing is likely to have only a small effect. There is insufficient experi-
mental evidence to indicate any chemical reactions take place in the inter-
action zone of the stack gas and cooling tower plumes.
Baselines of ambient S02 concentrations beyond the edge of the plumes were
less than 0.01 ppm, while typical smoke plumes ranged from 1 to 12 ppm. The
highest concentrations of sulfuric acid were detected in the stack gas plume
before mixing with the cooling tower plume (using the impactor sampler).
This quantity, however, was near the threshold sensitivity of the analytical
method (on the order of 150 ug/m'). Because of plume diffusion and low reac-
tion rates in the interaction zone, concentrations were lower in the interac-
tion zone measurements.
These studies demonstrated the relationship of acid precipitation to efflu-
ents of dry (stack) and wet (cooling tower) plumes of the power plant. In
general, the distribution of acidity in precipitation is governed by the
source strength at the stacks and meteorological variables such as wind
speed, wind direction, rainfall rate and amount.
Summer shower type of rain was analyzed for 1973 while Units 1 and 2 (once-
through cooling; no towers) were the only source of S02> The pH of rain
varied from 3.0 to 5.7. The hydrogen ion (ff*~) concentration for each rain
is very much wind dependent and falls off with distance from the maximum
value near the power plant stacks. Before the cooling tower of Unit 3 was
on, the pH for several rainfalls in the summer of 1974 ranged from 3.4 to
4.6. During cooling tower testing, when the boiler was burning at a low
rate, the pH shifted to a range of 4.0 to 4.8. Several rainfall and pH read-
ings were taken in 1975 when Unit 3 was used regularly and operated at a
high burning rate. When the large stack (Unit 3) and cooling tower are on
and the total amount of S(>2 increases, the rain becomes less acid close to
the stacks. This suggests that the interaction of dry plumes with the wet
cooling tower plumes has lowered the acidity in close proximity of the plant
(13).
Chemical analysis shows that sulfate and nitrite are the main ingredients of
acidity. Hence, the main source of low pH values were indeed attributable
to SC>2 and NO from the combustion of coal (25).
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Most of the acid formation occurred in the stack gas plume before mixing with
the cooling tower plume, so that the wet Venturi scrubber provided signifi-
cant H20 in both droplet and vapor form within the exhaust gas duct and the
stack thereby causing much higher reaction rates within the stack. The
highest H2SO^ concentration was detected in the stack gas plume before mixing
with the cooling tower plume. However, the exact concentration was not
determined since it was below the measurable threshold value of the instru-
ment.
The presence of stable visible plumes was observed during cold and high hu-
midity conditions. Even under these conditions, however, the decrease in
visibility was not considered to be a hazard to aircraft because of the
limited distance over which it extended.
Thus, at Chalk Point interactions between the cooling tower plume and the
stack gas plume were limited. The stack gas plume was saturated with water
from combustion products and from a wet Venturi scrubber. Therefore, chemi-
cal reactions that require moisture occurred prior to mixing with the cooling
tower plume, and the additional water supplied by the cooling tower plume
had little effect.
Concentrations of sodium chloride and sulfuric acid were very low. Occasion-
ally sulfuric acid was detected in the stack gas plume, but it was generally
below the measurable threshold sensitivity (4 ug/m^ for droplets larger than
30 microns and 150 ug/np for smaller droplets).
7.5.3 Ratcliffe and Rugeley (Staffordshire. U.K.) Stations
The normal pH for the cooling water is 8.2, but the droplets collected under
the cooling tower plumes varied between 2.4 and 7.3 (26). Lower pH values
were observed when the plumes (before eliminator modification at Ratcliffe)
had traveled several kilometers and the droplets were diluted by a factor of
3. The cooling tower droplets appeared to become acidic fairly quickly (some
droplets collected at 400 m downwind in light winds had pH • 3.5), but Martin
et al. (26) thought it more likely that on these occasions the S02 had come
from low-level sources rather than from the stack plume.
Observations of natural rainfall under the stack plume at Rugeley in
Staffordshire, which has one dry and several wet cooling towers, showed no
significant difference in pH from that at rainfall stations in the area which
were not under the plume (26).
7.5.4 Amos Station
The John E. Amos Plant, located 12 miles northwest of Charleston, West
Virginia in the Kanawha River Valley, is coal-fired and has three units with
a total generating capacity of 2900 MWe. Three Research-Cottrell natural
draft cooling towers are in a line, 200 m apart. The two towers for Units 1
and 2 have a height of 132 m, top radius (RQ) of 29 m, initial vertical speed
(W0) of 4.6 m/s and are each capable of servicing a generator of 800 MWe.
The third tower for Unit 3 has a height of 150 m, top radius of 40 m, initial
vertical speed of 4.2 m/s and services the 1300 MWe turbine. There are two
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stacks each 274.3 m (900 feet) high, one services both Units 1 and 2 and the
other Unit 3.
Kramer et al. (24) reported that in 47 of the 54 tests the plumes of the cool-
ing towers and stacks merged, as observed visually, within a short distance
of the release points. Their study did not include measurements of the
chemical and physical nature of the droplets before and after the merging,
but they contend that there is the possibility of interaction. Hanna (27)
reported that vertical profiles of ambient temperature, dewpoint and wind
speeds to heights of about 1500 m were obtained, and photographs of the plume
were taken from a light aircraft. Merging of multiple plumes from the three
cooling towers was observed. He proposed a plume and cloud growth model and
made the following assumption to account for the plume merger: the plume
radius grows to one-half of the distance between the towers, and then the
cross sectional area of the model plume increases so that it is equal to the
sum of the previous area of all the plumes.
7.5.5 Centralia Plant
Test results indicated that the 802 emission rate was 12,632 Ib/hr and the
H2S04 emission rate was about 395 Ib/hr (based on 27. conversion of S02 to 80s
in the boiler) (14). The NO emission rate was not measured but presumed to
be about 7,000 Ib/hr. The mean pH beneath the plume centerline was
4.20; the minimum pH was 3.89.
The amount of t^SCty scavenged up to 7 miles (11 km) was calculated to be
178 Ib/hr or 45% of the amount emitted from the stack.
7.5.6 Cayuga and Mil liken Stations
Measurements of acidity in precipitation have been recorded for the North-
eastern U.S. (Table 7-6). Calculated emission rates for S02, H2S04 and NO
for the Cayuga and Milliken Stations at 1007. capacity are given in Table 7-7.
Based on Centralia data, the lowest pH under the center line of the plume
during rainfall at Cayuga and Milliken was predicted to be 3.5. This in-
cluded a background contribution from the surrounding atmosphere equivalent
to pH « 4.0.
7.6 MINIMIZING COOLING TOWER-STACK PLUME INTERACTIONS
7.6.1 Introduction
From the previous information presented, it is apparent that plume interac-
tion is a complex phenomenon involving many factors. Natural parameters such
as humidity, temperature, wind speed and direction, rate of precipitation and
other meteorological factors are obviously not controllable. Therefore, to
minimize the adverse impact on the environment, design parameters which con-
tribute to the plume interaction must be controlled. These include: separ-
ation distance between stack and cooling tower, various S02 removal processes
and the use of tall stacks.
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The principal approach to control adverse plume interaction is likely to be
S02 control. The major alternatives available for S02 control are given in
Table 7-9 together with a partial listing of their characteristics. Use of
naturally clean fuel, flue gas desulfurization (FGD), fuel pretreatment such
as mechanical coal cleaning, coal liquefaction, coal gasification, and al-
ternative coal combustion systems such as fluidized bed coal combustion and
magnetohydrodynamics (MHD) are some controls for SC>2 generation. Table 7-10
presents a summary of various FGD processes now in use.
Fine participates and nitrogen oxides are precursors that accelerate the for-
mation of sulfate from S02« Fine particulate control may be necessary to
prevent intrinsic health and welfare effects as well as the possible syner-
gistic effects related to particulate sulfur oxide combination. Control of
precursors such as catalytic particulates (vanadium, etc.) and photochemical
oxidants without also restricting S0£ emissions might be of limited value
(28).
Other supplementary or intermittent control techniques include: use of very
tall stacks, fuel switching, load shifting, and curtailment of operation
when short-term or seasonal local meteorology forecasts indicate poor disper-
sion. Among these, much work has been done in the area of tall stacks and a
detailed review of this topic will be presented.
Heights of the cooling tower and the stack must be sized so that the differ-
ences in plume buoyancy do not balance out. By making the stacks taller and
the cooling towers shorter, the mixing of the stack and tower plumes can be
avoided. Reliance on tall stacks and precursor control to reduce local SCH
or sulfates could result in increased rainfall acidity. Recent evidence
suggests that this would only aggravate the already serious acid rain prob-
lems discussed earlier (28).
7.6.2 Separation Distance Between Stack and Cooling Towers
Generally, natural-draft cooling towers are built in groups of two to four
with spacings of 200 to 500 m. Mechanical-draft towers are traditionally
built in lines or "banks" in which 10 to 20 fan units are located in one
200-m long structure. Recently, some mechanical draft units have been ar-
ranged into doughnut-shaped structures, presumably to increase the plume rise
from the group (1).
Briggs (29) assumed that the plume rise from multiple sources was enhanced
by a factor E^ over that of a single source and recommended that:
where:
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En • plume rise enhancement factor
n " number of sources
s • center-to-center spacing between adjacent sources
hi m plume rise from one source
These formulas are for bent-over buoyant plumes and were tested against plume
rise observations of TVA's Colbert, Shawnee and Widow's Creek Power Plant
stacks. For calm conditions when buoyant vertical plumes are generated, a
crude but simple method is suggested for predicting the height of the plume
merger and subsequent behavior. This method is based on the geometry and
velocity variations of a single buoyant plume. If n sources were clustered
in an area of maximum center-to-center dimension D, the plumes will merge at
a height Zm - 4D/(n)%.
The characteristics of the merged plume can be roughly predicted by assuming
a single combined source at a virtual origin Z - 1 - (np Z^. If this
equation is applied to clusters of sources, then (n - l)s should be replaced
by the maximum diameter of the clusters. This method was tested with data
from multiple smoke stacks, with n as great as 9 (TVA), but has not yet been
(October 1976) tested with data from cooling towers.
It is possible to calculate the spacing necessary to keep the enhancement
factor below a certain value. When the number of sources is only two, i.e.,
n • 2, the enhancement factor is:
E2"
8 spacing
For various g» ( •ume r^gg) ratios, the enhancement factor has been calcula-
ted as follows:
.£. 0.5 0.8 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5
hl
E2 1.1825 1.402 1.1187 1.082 1.060 1.046 1.036 1.030 1.025 1.018
The data indicate that when spacing is about 1% times the plume rise, the
merged plume will rise 8.2% higher than the single plume.
As stated in a previous section, the meteorological conditions, plume rise
from buoyant effects, and stack-cooling tower axis orientation to the wind
are significant factors affecting plume commingling. Separation distance
between the stack and cooling tower plumes increases the probability that the
stack gas and visible cooling tower plume will not merge. Increased disper-
sion increases the evaporation rate of the cooling tower plume so that the
visible plume is shorter. The stack-cooling tower orientation provides the
same advantage for evaporation when the wind is perpendicular to the axis.
Cost limitations restrict the distance at which the cooling tower can be
spaced from the stack. Furthermore, there have been no studies explicitly
evaluating the effectiveness of various separation distances. The value of
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separation distance has, therefore, not been experimentally evaluated for
reduction of stack gas - visible cooling tower plume interaction and the re-
sulting acid-drift-deposition.
A multi-faceted hypothetical evaluation including separation distance is
feasible in order to crudely estimate the problem of acid-drift deposition.
Evaluation of stack-cooling tower separation alone is not sufficient. This
type of evaluation has been performed for the Niagara Mohawk Power Corpora-
tion as part of their license application for the Lake Erie Generating Sta-
tion (12). This analysis evaluated the acid drift-deposition on the basis of
chemical decomposition of S0£ to 80^ from available literature, estimated
plume trajectories from the stack and cooling tower, the frequency of meteo-
rological conditions expected to result in the maximum coexistence of the
plumes at the same elevation, acid deposition predicted by a numerical model,
and acid precipitation scavenging predicted by a model. The results were
given in terms of the worst case and the annual average. The accuracy of
such a study is questionable considering that the state-of-the-art for esti-
mating structural wake effects is deficient, and deposition models predict
results within a factor of two or more of observed results. More often,
deposition models are reliable to one order of magnitude (22). Since this
particular study has not been verified with field experiments, it may only
provide a first order estimate.
To reduce the potential of stack gas - visible cooling tower plume merging,
the following should be evaluated: the coincidence of high relative humidi-
ty, light winds, stable temperature lapse rates, wind direction parallel to
the stack - cooling tower axis, and the design parameters of the stack and
tower. Although merging frequency potential estimates based upon coincident
meteorological conditions and design parameters are crude, it is reasonable
to expect that the potential adverse effects from acid drift-deposition can
be deduced by following this procedure. The stack and cooling tower design
parameters, such as plume temperature, exit velocity, exit diameter, and flue
gas and tower air flow rates, determine under what circumstances the stack and
cooling tower plumes will rise to equivalent, or nearly equivalent, levels as
a result of the buoyant effects. If the stack - cooling tower axis is orien-
ted perpendicular to the wind under these coincident meteorological condi-
tions, the merging probability is minimized. If the wind rose for such con-
ditions is established from on-site data, then a first order estimate of the
merging problem can be ascertained and the stack-tower axis can be oriented
accordingly. In the same manner, the stack and cooling tower design para-
meters can possibly be selected to minimize coincident plume elevations.
In general, the separating distance between the boiler smoke stack and the
cooling tower(s) is most often based on the availability of land for the
plant. When effluent sources such as the stacks and the cooling towers are
very close to each other, the plumes will combine or commingle. If they are
very far apart, the plumes will rise separately. This is true if the atmos-
pheric conditions are stable, i.e., the winds are calm. The wind speed and
the wind direction will play an important role in the plume merger. Thus the
wind rose at the plant location should be used in determining the relative
location of the cooling towers with respect to the stack when establishing
the plant arrangement and layout.
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To establish guidelines on the separation distance between the stack and the
cooling tower, their plume dimensions (plume rise, length, width or diameter
at any downwind distance, the ground-level concentration, etc.) must be
known. The interaction will be minimum when the plumes rise separately and
do not merge. This occurs when the stack and the cooling tower are very far
apart. There are advantages and disadvantages to increasing the tower
spacing. An advantage is that the chances of cloud and rainstorm interaction
are less if the plumes do not merge. A disadvantage is that the chances of
high ground-level concentrations of fog drift and cooling water chemical ad-
ditives are increased if the plumes do not merge but stay closer to the
ground.
7.6.3 Use of Tall Stacks
Of many available methods for limiting ground-level pollutant concentrations,
many times tall stacks are the simplest, most effective and least costly.
However, a theoretically explicit, field validation of the soundness of using
tall stacks is often hampered by the lack of comparable pre- and post-opera-
tional data.
In a study at the Alma Power Plant, appropriate air quality and meteorologi-
cal measurements were made for several years before and after conversion from
short to tall stacks (Table 7-13). Comparison of these data show that the
tall stack reduced ambient levels of S(>2 by 507. to 95% in the vicinity of the
plant (Table 7-12). This study also found that the use of a Turner-Briggs
dispersion model in a valley situation gave fairly accurate and reliable es-
timates of air quality. The model was useful in designing the tall stack,
assessing its impact, and locating air quality monitors (30).
Unlike the practice in many other portions of the United States, the plants
in the Upper Ohio Valley were either originally built with tall stacks or
were retrofitted with them when the benefits of doing so became apparent.
Since stack height is a critical factor in the behavior of the discharged
flue gases, all of the plants in the area are listed in Table 7-13 with their
stack heights and the generating capacity associated with each stack. From
this table, it is readily apparent that all of the major plants have stacks
at least 500 ft high. The smaller plants with lower stacks, constituting
less than 10% of the generating capacity, are fairly well dispersed so that
no area is especially influenced (31).
A common method for achieving the standards of maximum ground-level concen-
tration of S02 is to release the S02 through tall stacks so that it will be
dispersed and reduced to an acceptable level of concentration prior to
reaching the ground. This has been considered a rather short-sighted solu-
tion since it in no way reduces the amount of S02 emitted into the air (32).
Tall stacks reduce ground-level concentration of S02, but increase sulfate
aerosol formation by reducing losses of S02 and by increasing the atmospheric
residence time, which results in increased S02 to sulfate conversion (33).
One problem related to stack height and plume merging problems, but which
has not been studied except in wind tunnels, is the cooling tower wake ef-
fect. Bogh (34) and Kennedy et al.(35) determined that wake effects can be
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significant. However, the applicability of the wind tunnel study results to
the field is questionable because of boundary effects at the plume walls (35).
The main relevancy of this problem to plume merging is the effect of the aero-
dynamic and tower emission design upon the cooling tower plume rise. It is
assumed that the stack is of sufficient height that no entrainment occurs as
a result of any nearby structures. The Kennedy-Fordyne study of model rec-
tangular mechanical draft cooling towers concluded that spacing does reduce
the recirculation ratio. In addition, the orientation of the wind with re-
spect to the tower affected the recirculation because of the entrainment
around the tower ends. The value of zero for which the maximum recirculation
ratio occurs appeared to generally decrease as the ratio of the exit velocity
to wind speed decreased. For a wind blowing at 90° to the tower axis, the
presence of a second tower at half a tower length downwind greatly in-
creased the air entrainment. Increasing the mechanical draft cooling tower
length means the tower height should be increased; otherwise, the entrainment
around the end of the tower is enhanced. The trajectory and spreading of the
plumes are affected far more by the ratio of exit velocity to wind speed than
by buoyancy. In order to better anticipate plume rise and dispersion, these
factors should be taken into consideration when designing mechanical draft
cooling towers.
For natural draft cooling towers, the aerodynamic problems are not nearly as
severe as for mechanical draft cooling towers since tower height determines
the recirculation problem. Increasing the height noticeably reduces the en-
trainment, thereby minimizing the plume rise when compared with lower tower
heights. The effects of tower structures are presently being modeled by Bogh
(34) in order to provide a systematic process to evaluate the wake effects
for various tower designs. Huber (38,39) modified the dispersion parameters
to account for wake effects. Even though this wind tunnel model study was
applied to building wake effects on stack effluents, some characteristics may
be useful in anticipating tower structure effects, particularly for mechani-
cal draft cooling towers. Huber found the ratio of the wake modified to the
Pasquill-Gifford index decreased to nearly 1.0 at distances equal to 10
building heights. For 15 cases in a reported on-site study, there were no
significant differences in the ratios between stable and unstable conditions.
Simple mathematical representations of different parts of the flow field may
provide a more refined and accurate approach to this problem (36). As yet,
insufficient data exists to fully examine the wake effects (36).
Hatcher (37) performed a wind tunnel dispersion analysis in a building wake
and reported that at some distance downwind, generally eight building heights
for his structure, the rate of dispersion was independent on the release po-
sition and building orientation. Buildings enhanced only vertical dispersion
for elevated releases. Minor changes in the building design can drastically
alter the dispersion characteristics.
Although all of these dispersion studies estimating the wake effects are
useful to characterize Gaussian flows, they do nothing to analyze the effects
on large particle drift which is characterized by a ballistic trajectory.
Only these droplets from a cooling tower which are less than 100 or 200 mi-
crons, depending upon the turbulence conditions, can be analyzed in a
n—»°<«m regime. Unlike the tunnel studies by Bogh (34) and Kennedy et al.
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(35) which attempt to analyze the effect of structural designs on plume rise
and dispersion, studies by Huber (36,38,39) and Hatcher (37) are concerned
more with dispersion.
In general, the introduction of tall smoke stacks and particulate removal de-
vices have reduced the local "soot problem". Whether these procedures have
altered (positively or negatively) the regional "acid problem" is an unan-
swered question (40). The use of a single stack to serve a power plant with
multiple boilers has been analyzed by Hamburg (41) as a possible alternative to
multiple tall stacks for pollution abatement. His analysis indicated that a
single stack serving multiple boilers was more effective than much taller
multiple stacks in reducing ground-level S02 concentrations. Furthermore,
the single stack is considerably less costly to install and maintain than are
multiple tall stacks and should be less objectionable to aviation and aes-
thetic sensitivities. Whether considered for new plants or retrofitting
existing plants and whether or not scrubbers are used, the single stack ap-
pears to be a practical and economically attractive alternative for local
pollution abatement (41).
Another alternative to lower ground-level air pollution concentrations is to
reheat stack gases to higher exit temperatures. This produces a greater
plume rise plume interaction. Thus, the effects of reheating are similar to
that of a tall stack. Enviroplan (42) presented five alternate methods of
stack gas reheating now in use. A steam injection method was utilized in a
large number of demonstration projects.
A total system evaluation of several S(>2 control technology alternatives po-
tentially available to the utility sector is presented in Table 7-14. The
table clearly shows the difference in S02 emissions, energy efficiency, costs
and timing when various control techniques are used.
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REFERENCES
1. Harnia, S. R., 1977. Atmospheric Effects of Energy Generation. Un-
published manuscript.
2. Pell, J., 1975. The Chalk Point Cooling Tower Project. In: Cooling
Tower Environment - 1974, Hanna and Pell (eds.). ERDA Symp. Ser
CONF-740302, pp. 88-127.
3. Sanna, K. R. H., 1973. A Method of Calculation of Ground Level Con-
centration of Particulates Due to Interaction of Cooling Tower Plumes
with Stack Plumes of Large Power Plants. Paper presented at Environ-
mental and Geophysical Heat Transfer Conference, ASME HTD, Vol 4
pp. 26-30. '
4. ShirarL, M. A., B. A. Tichenor and L. D. Winiarski, 1977. EPA's
Cooling Tower Plume Research. J. Pow. Div., ASCE, 103: 1-13.
5. Davis, L. R., 1975. Analysis of Multiple Cell Mechanical Draft Cool-
ing Towers. EPA Ecological Research Series, EPA 660/3-75-039.
6. Kannberg, L. D., 1976. An Experimental/Analytical Investigation of
Deep Submerged Multiple Buoyant Jets. PhD. dissertation, Oregon State
University, Corvallis.
7. Du, C., P. Donaldson and G. R. Hilst, 1972. Effect of Inhomogeneous
Mixing on Atmospheric Photochemical Reactions. Envir. Sci. Tech 9-
812-816. '
8. Thomson, D. W., 1976. Environmental Impact of Evaporative Cooling
Tower Plumes. Report Prepared for ERDA (contract No. (11-1) 2463) by
Dept. Meteorology, Penn State University Park, 44 p.
9. Wbffinden, G. J., et al., 1976. Chalk Point Cooling Tower Project,
Cooling Tower Plume Survey. Technical Summary, Vol. 1, Meteorology
Research, Inc., for Maryland Dept. Natural Resources.
10. Dittenhoefer, A. and R. dePena, 1977. A Study of Production and Growth
of Sulfate Particles in Coal Operated Power Plant Plumes. Paper
Presented at International Symposium on Sulfur in the Atmosphere,
Sept. 7-14, 1977. Yugoslavia.
11. Stockham, J., 1971. Cooling Tower Study. IIT Research Institute,
Chicago, NTIS PB-201 216.
180
-------
12. Niagara Mohawk Power Corp. (NMPC), 1975. Lake Erie Generating Station
Application. For New York State Board on Electric Generation Siting
and the Environment.
13. Li, Ta-Yung and H. E. Landsberg, 1976. Level and Causes of Acidity
of Precipitation Near a Major Power Plant. Institute for Fluid
Dynamics and Applied Mathematics, Univ. Maryland, Tech. Note BN-832.
14. Dana, M. T., D.~R. Drewer, D. W. Glover and J. M. Hales, 1976. Pre-
cipitation Scavenging of Fossil-Fuel Effluents. EPA-600/4-76-031.
15. Hales, J., et al., 1973. Advances in the Theory and Modeling of
Pollutant Gas Washout. Battelle Pacific NW Lab, NTIS BNWL-SA-4684.
16. Esmen, N. A. and R. B. Fergus, 1976. S02-NH3-Particulate Matter -
H20 Reaction System as Related to the Rainfall Acidity. In; •
Proceedings of the First International Symposium on Acid Precipitation
and the Forest Ecosystem. USDA For. Ser. Gen. Tech. Rep. NE-23,
pp. 205.
17. Montz, A. C., et al., 1976. Rainfall Variations Around a Thermal
Power Station. Atmos. Envir. 10: 963-968.
18. Ananth, K. P., et al., 1976. Particle Emission Reactivity. Indus-
trial Environmental Laboratory NTIS PB-259 300.
19. Jones, H. C., 1973. Preoperational Atmospheric Monitoring in the
Cumberland Plant Area: The pH and Sulfate Content of Precipitation
Air Pollution Effects Section, Environmental Biology, Mussel Shoals,
Alabama.
20. Moser, B. C., 1975. Airborne Sea Salt: Techniques for Experimenta-
tion and Effects on Vegetation. In: Cooling Tower Environment -
1974. Hanna, S. R. and J. Pell (eds.), ERDA Sympos. Ser., CONF-
740302, pp. 353-369.
21. Murphy, B. L., 1976. Plume Rise From a Row of Chimneys. 68th
Annual Meeting of APCA, Boston.
22. Policastro, A, J., et «d., 1977. Progress Report - Validation of
Cooling Tower Plume Rise and Salt Drift Deposition Models. Feb. 1,
1977-Mar. 31, 1977, Argonne National Laboratory, Unpublished.
23. Hanna, S. R. and F. Gifford, 1975. Meteorological Effects of Energy
Dissipation at Large Power Plant Parks. Bull. Amer. Meteorol. Soc.
156(10): 1069-1076.
24. Kramer, M. L., M. E. Smith, M. J. Buffer, D. E. Seymour and T. T.
Frankenberg, 1976. Cooling Towers and the Environment. J. Air Poll.
Control Assoc., 26(6); 582-584.
181
-------
25. Li, Ta-hung, 1976. Cooling Tower Influence on the Rainwater pH Near
a Major Power Plant. Proc. First International Symposium on Acid
Precipitation and the First Ecosystem. USDA For. Ser. Gen. Tech.
Rep. NE-23, pp. 333.
26. Martin, A. and F. R. Barber, 1974. Measurements of Precipitation
Downwind of Cooling Towers. Atmos. Envir., 8: 373-381.
27. Hanna, S. R., 1976. Observed and Predicted Cooling Tower Plume Rise
at the John E. Amos Power Plant, West Virginia. 3rd Symposium on
Air Turbulence Diffusion and Air Quality, Oct., 1976.
28. U.S. Environmental Protection Agency, 1975. Position Paper on Regu-
lation of Atmospheric Sulfates. EPA-450/2-75-007 (NTIS PB-245 760).
29. Briggs, G. A., 1975. Plume Rise From Multiple Sources, in; Cooling
Tower* Environment - 1974. Hanna and Pell (eds.), ERDA Symp. Ser.
CONF-740302, pp. 161-178.
30. Mutch, J. J., 1977. The Effectiveness of a Tall Stack for Reduction
of Ambient Sulfur Dioxide Concentrations: A Field Investigation.
J. Air. Poll. Control Assoc., 27(6): 567-571.
31. Frankenberg, T. T. and K. J. Skipka, 1974. Meteorology, Power Genera-
tion and Sulfur Dioxide Concentrations During a Major Air Stagnation
Episode. Combustion. July 1974: 6-11.
32. Fox, D. G., 1976. Modeling Atmospheric Effects An Assessment of the
Problems. Proc. First Int. Symp. on Acid Precipitation and the
Forest Ecosystem. USDA For Ser. Gen. Tech. Rep. NE-23, pp. 57-87.
33. Wilson, W. E., et al., 1976. Sulfates in the Atmosphere - A Progress
Report on Project MIST (Midwest Interstate Sulfur Transformation and
Transport). EPA/600/09, Preprint, Air Poll. Control Assoc. No. 76-
30-06, 19 p.
34. Bogh, P., 1975. Experience with Combined Wind Tunnel Plume Model
Analysis of Cooling Tower Environmental Impact. In: Cooling Tower
Environment-1974, Hanna and Pell (eds.), ERDA Sympos. Ser. CONF-
740302, pp. 265-269.
35. Kennedy, J. F. and H. Fordyne, 1975. Plume Recirculation and Inter-
ference in Mechanical Draft Cooling Towers. In; Cooling Tower
Environment - 1974, Hanna and Pell (eds.), ERDA Symp. Ser. CONF-740302
pp. 58-87. '
36. Huber, A., 1977. Incorporating Building/Terrain Effects on Stack
Effluents. Preprint on Joint Conference on Application of Air Pollu-
tion Meteorology, Utah.
182
-------
37. Hatcher, R. V. and R. N. Meroney, 1977. Dispersion in the Wake of a
Model Industrial Complex. Preprint on Joint Conference on the Appli-
cations of Air Pollution Meteorology, Utah.
38. Huber, A., et al., 1977. Building Wake Effects of a Squat Building on
Short Stack Effluents - A Wind Tunnel Study. Environmental Protection
Agency, Research Triangle Park, North Carolina.
39. Huber, A., et al., 1976. Building Wake Effects on Short Stack Efflu-
ents. Preprint of AMS Third Symposium on Atmospheric Turbulence
Diffusion, North Carolina.
40. Newman, L., 1975. Acidity in Rainwater: Has an Explanation Been
Presented? Science, 188: 957-58.
41. Hamburg, F. C., 1975. Feasibility of a Single Tall Stack in Power
Plant Construction. TRW, Environmental Services, NTIS PB-255 952, 102 p,
42. Enviroplan, Inc., 1975. Maximum S02 Concentrations Produced by a
1000 Megawatt Power Plant. Prepared for Environmental Protection
Agency, EPA 230/1-75-002.
43. Galloway, J. N., G. E. Likens and E. S. Edgerton, 1976. Hydrogen
Ion Specification in the Acid Precipitation of the Northeastern United
States. Proc. First International Symposium on Acid Precipitation
and the Forest Ecosystem, USEA For. Ser. Gen. Tech. Rep. NE-23, pp.
383-396.
44. Moore, D. J., 1975. Recent Control Electricity Generating Board
Research on Environmental Effects of Wet Cooling Towers. In: Cool-
ing Tower Environment - 1974. Hanna and Pell (eds.), ERnA~Symp. Ser.
CONF-740302, pp. 205-213.
45. MacKenzie, J. S., 1976. Cayuga Site Report. United Engineers &
Constructors Inc., Philadelphia, Unpublished.
46. Moore, F. K., 1976. Regional Climatic Effects of Power Plant Heat
Rejection. Atmos. Envir., 10: 806-811.
183
-------
• I tOWCll riVMC MIXINt
MIM me* HUMC.
H tTACK fLOKC UIXINt
»ITN 10Wf«
TN(
Fig. 7-1 Plume interactions (3)
184
-------
10 JO «0 50 CO 70 to 10 ISO
Horizontal Ontonce (x/0)
LEGEND
U0 • initial jet velocity
x, y, z co-ordinates
D - jet diameter
F = densimetric Froude number
R - Uc/Uo
L » jet spacing
Fig. 7-2 Comparison of predicted and measured plume
trajectories
(a) with vertical discharge, R « -.01 and 0.5,
F = 11, L/D - 2.5;
(b) with dilution showing effects of jet spacing
L relation to diameter D ( 6).
185
-------
10
fl-O
0.01
I'll I I
20
40 60 60
RELATIVE mtUOm, X
100
Fig. 7-3 Variation of acid drop concentration with humidity (4)
186
-------
Wind
-Monitoring traverses-
vertical section
Upwind
vertical
•scent
Ground level traverse
beneath plume
Helicopter depart
Helicopter arrive
Fig. 7-4 Plume monitoring patterns ( 4)
187
-------
10"
o
s
,A
LJLI
o
10s
O
oc:
I04
AITKEN PARTICLES
LARGE PARTICLES
20 40 60 80 100
PLUME TRAVEL TIME (M1N)
120
Figure 7-5 Particle concentration for two different
flights at points along the plume path (10)
-1.0
o
o
cc
2
Ul
8
d
O
IT
188
-------
00
SO
.1200
:!. .IOOO
oc
ui
UJ
_J
o
-0800
.0600
.0400
< .0200
IxJ
20 40 60 80 100
PLUME TRAVEL TIME (MIN.)
12O
Flgur* 7-6 Particle growth obearvtd during merged plme case (10)
-------
wr4
CO
UJ
o
fe
2
UJ
CO
LJ
_J
O
a:
LJ
o
o
icr:
10
-6
Large Particles
-Aitken Particles
0
J.
JL
20 40 60 80 100
PLUME TRAVEL TIME (MIN)
120
Fig. 7-7 Particle concentrations (10)
190
-------
XIO
) 20 40 60 80 100
PLUME TRAVEL TIME (MIN.)
Fig. 7-8 Particle concentrations (10)
120
191
-------
•umber of drops
Av«il«t>X« for • icing
00
Satnpl* NunMr 12
SMpl« HunlMr 13
ISO
200 2SO 300
R««idu« Slz« (Micron*)
3 SO
400
450
soo
Fig. 7-9 Plume droplet residue size distributions
sample numbers 12 and 13 (11)
192
-------
100
Number of drop*
available for •imlng
94
TOO
Residua Size- (Microns)
Fig. 7-10 Plume droplet residue size distribution
sample number 6 (11)
193
-------
100
II
4J
a
4J
W
VI
4J
c
Humber of drops
availsble for sizing
Sample Number 7 88
200 250 300 350
Residue Size (Microns)
400
•ISO
500
Fig. 7-11 Plume droplet residue size distribution
sample numbers 7 and 8 (11)
19A
-------
10
number o£ drop*
available tor mlalng
«0 60
Residua Size (Micron*)
XOO
Fig. 7-12 Plume droplet residue size distribution
sample number 1 (11)
195
-------
100
S
<•*
II)
•o
V
u
e
tf
VI
60
g «°
£
20
Number of drops
pH available for sizing
2-3 19
62
57
20 40 60 80
Residue Size (Microns)
ICO
Fig. 7-13 Flume droplet residue size distribution
sample number 3 (11)
196
-------
VO
DOWNWIND DISTANCE i
Section^
0.
I.
2.
3.
4,5.
Upwind from source.
As close to water plume source as safety would permit
As close to smoke plume source as safety would permit
Slightly downwind from the beginning of interaction zone
Selected locations in the interaction zone based on the
existing meteorological environment
SAMPLING MODE;
Horizontal Traverse
Vertical Temperature
Sounding
Fig. 7-14 Flume interaction, test plan no. 3 (11)
-------
\o
oa
TABLE 7-1
MAXIMUM GROUND-LEVEL AIB COMCENTRATIOMS AND SURFACE DEPOSITION FLUXES OP Sf
DURING WORST CASE
Caae 1
Cl max to/"3'
C2 max
F, (ug/m2-sec)
1 max
F2 max (ugM2-«««c)
ga.se. 2.
Cl max (us/*3)
MERGING OF LAKE ERIE GENERATING STATION
Neutral Stability,
5.5 m/s Wind,, No Ba^p
3.22 @ 18.25 km downwind
0.24 & 25 km
0.065 @ 18.25 km "
0.00048 (? 25 km
Neutral Stability,
15 HI/B Windr Ng Rfllt^
2.03 (a 19 km downwind
0.093
-------
TABLE 7-2
VO
\0
PKETtTCTED MAXIMUM CROPHD-'LEVEL AIR CO^GENTRATION AND SURFACE DEPOSITION
FLTOCES OF SO- AND SQ." ^OR NON-MERGING CASES
Case 3
(ug/m3)
max
1 max
2 max
(ug/m*-sec)
(ug/m2-sec)
Case 4
'1 max
(ug/m3)
C2 max (u8/n»3)
Fl max (ug/m2-«€c)
F2 max
Neutral Stability,
5.5 m/s Wtnd No
3,65 @ 20.25 tan downwind
0.193 @ 25 km "
0.036 @ 20.25 km "
0.00019 @ 25 km "
Neutral Stability
15 m/s Wind. No Raj,n
2.15 @ 19.75 km downwind
0.081 @ 23.5 fan "
0.022 @ 19.75 km "
0.000081 @ 23.5 km
Neutral Stability
.5 rn/a Wind. 1 tn/ir Rainfall
1.87
0.072
0.18
0.008
@ 11.25 km downwind
@ 13.50 km "
@ 14.5 km "
@ 18.25 km
Neutral Stability
m/s Wind. 1 mn/hr Rainfall
1.50 @ 15.0 km downwind
0.05 @ 16.0 km "
0.143 @ 19.0 km
0.0054 @ 21.25 km "
Legend: Cj ntfx is peak ground-level air concentration of SO .
C2 max ** peak ground-level air concentration of SO^".
Fl max is peak 8urface
of SO .
2 max
surface flux of SO
Note: The symbol "ug" represents micrograms,
-------
TABLE 7-3
AMWITAT. STTTtTArF TOTPORTTTQW FT1IXFS OF
S02
MIRING PU1ME MERGING
Downwind
Distance
(km)
8
10
12
14
16
18
20
22
24
With
Precipitation
2
(pg/m -^
0.215
0.225
0.225
0.215
0.201
0.184
0.165
0.145
0.125
Without
Precipitation
(pg/m2-3 )
0.045
0.054
0.059
0.062
0.064
0.065
0.064
0.063
0.062
Annual Deposition
(mg/n.2)
Pomfret f1) Sheridan (2)
0.62S
0.699
0.751
0.778
0.791
0.781
0.771
0.749
0.728
0.308
0.360
0.388
0.402
0.408
0.403
0.398
0.386
0.375
(1) One of the sites for Lake Erie Generating Station of Niagra
Mohawk Power Corporation.
(2) Another site for Lake Erie Generating Station of Niagra
Mohawk Power Corporation.
200
-------
Downwind
Distance
(km)
14
16
18
20
22
24
TABLE 7-4
PRF.niCTED ANNUAL SimffACE RFPOSTTTON TT.TTYttg
""4
With
Precipitation
2
10.69
10.66
10.36
9.83
9.15
8.34
Without
Precipitation
2
(ug/m - s)
0.36
0.39
0.42
0.44
0.46
0.47
Annual Deposition
(fflg/m2)*
Pomfret (1)
9.71
10.04
10.27
10.16
9.93
9.71
Sheridan
5.05
5.20
5.28
5.24
5.15
4.97
(2)
*Multiply all rates by 10
-3
(1) One of the sites for Lake Erie Generating Station of Niagra
Mohawk Power Corporation.
(2) Another site of the Lake Erie Generating Station of Niagra
Mohawk Power Corporation.
201
-------
TABLE 7 -5
PARTICLE FREQUENCY (%) FOR FLIGHT 4 ON STAGE 3 OF THE IMPACTOR (10)
Upwind Downwind
12-2 Km 32.7 Km 49.0 Km
Non-Sulfate 88 91 88 30
Mixed* 4 7 6 16
Sulfate 82 6 54
*Volume fraction 75% 80% 87%
of sulfates with-
in the mixed
particles
202
-------
TABLE 7-6
SOURCES OF ACIDITY IN ACID PRECIPITATION*
IN THE NORTHEASTERN UNITED STATES (43)
Concentration in
Precipitation
(mgA)**
Contribution to
Free Acidity at
PH s 4.19 (ueq/1)
Contribution to
Total Acidity in
a Titration to
pH- 9.0 (ueq/1)
H2C03
Clay
NH4
Al
Fe
Mn
RCOOH
HNOg"14"
H, SO/*
0.62
5
0.195
0.036
0.040
0.005
1.1
2.26
2.80
0
0
0
0
0
0
5
23+*"
afc"*
--***
5+
11"
4
2
0.1
17
23
at
TOTAL
64
99
*Sample collected February 27, 1975 at Ithaca, New York.
**The total chemical composition is as follows: H, 65 ueqA ; Ca, 7.4 ueqA
Mg, 1.6 ueqA ; Na, 2.1 ueqA ; NH^ 10.8 ueq/1 ; Al, 4.0 ueqA ; Fe, 2.6
ueqA ; Mn, 0.1 ueqA ; S04, 58.2 ueqA ; N03, 36.4 ueqA ; Cl, 5.6 ueqA ;
P04, 0.2 ueqA ; and dissociated organic acid, 5 ueqA . The ion balance
agrees within 10%, which is the equivalent of 0.04 pH units.
***H2C03 was removed from system by N2 purging. If the H2C03 was not re-
moved and the system was at equilibrium with the atmosphere, there would
have been 5,000 ueqAcontribution to total acidity and no contribution
to free acidity in a titration to pH » 9.
"'"This assumes that all of the particulate is montmorillonite; most likely
the contribution to total acidity is an order of magnitude less than
5 ueqA because of minerals other than montmorillonite with much lower
exchange capacities.
203
-------
Notes to Table 7-6, continued:
assumes that all of the NH^ is converted to NHg which is subse-
quently removed by the ^ purge. The most likely value is between 4
and 11 ueq/1 .
contribution to the free acidity is determined by a stoichiometric
formation process in which a sea salt anionic component is subtracted
from the total anions (Cogbill and Likens 1974).
pH-4.0, 1.57. of the total sulfate is present as HSO ~; thus total
acidity for sulfate is greater than the free acidity.
NOTE: The symbol "ueq" represents microequivalents.
204
-------
TABLE 7-7
Substance
so2
H2S04
NO
AND MILLIKEN
Plant
Cayuga
Milllken
Cayuga
Milllken
Cayuga
Milllken
STATIONS AT 1007.
fl
Ib /106
1.176
3.724
0.037
0.116
0.7
0.7(a
CAPACITY (45)
kitoBlon Rate
Btu Ib /hr
9,353
10,999
293
316
5,567
'* 1,896
(a) Assumed value might be as high as 1 lb/10 6 Btu.
205
-------
TABLE 7-8
COMPARISONS OF COOKING TOWER-STACK INTERACTION STUDIES
Investigator
Stockham (11)
Plant
Keystone
Dittenhoefer and
de Pena (10)
Keystone
Results
Acidity increased when stack plume
merged with cooling tower plume. The
number ratio of acid to neutral drops.
pft=4-5 to pB=6-7, increased from 0.05
to 3.0 as RH increased from 50% to
957.. Decrease in RH from 80% to 62%,
S(>2 concentration near to station de-
creased from .030 ppm to 0.017 ppm.
Droplets grew to 0.3 urn* after 90 min-
utes of plume travel in interaction
zone due to sulfate production. High-
est rate of particle growth was at
lower temperatures. The conversion
rate of S02 to ^SCfy was 0.5% per hour.
Li and Landsberg (13) Chalk Point
Woffinden ( 9 )
Chalk Point
Moore (44)
The rain close to the stacks was less
acidfc due to interaction. Plume inter-
action lowered the acidity of rain.
pH of rain was in the range of 3.4 to
4.6 prior to cooling tower operation
and shifted to 4.0 to 4.8 range with
cooling towers in operation.
Concentration of H2S04 acid was very
low. Chemical reactions that require
moisture have occurred prior to plume
merger due to wet scrubbing, and the
additional water supplied by cooling
tower plumes has little effect.
Ratcliffe,U.K. pH of droplets collected under the
cooling tower plumes varied between
2.4 and 7.3 after several km distance.
The droplets became acidic fairly
quickly. At 400 m, pH of droplets was
3.5.
Moore (44)
Kramer (24)
Dana (14)
Rugeley, U.K.
Amos
Centralia
No significant difference in pH
occurred due to interaction.
In 47 of 54 tests, the plumes merged,
The mean pH beneath the plume center-
line was 4.20, the lowest pH being 3.89,
Tests indicated that H^SO^ emitted
from the stack at 395 Ib/hr and about
45% of this scavenged up to 7 km.
206
-------
TABLE 7-8 (cont.)
Investigator Plant Results
MacKenzie (45) Cayuga and Predicted lowest pH under plume center*
Mllllken line was 3.5, with background at pff-4.0.
* The symbol "urn" represents microns.
207
-------
TABLE 7-9
SUMMARY OF CONTROL ALTERNATIVES FOR SOo (281
Sulfur
Removal
Efficiency
Control Technique C31 S Base).
Nonregenerable (lime/lime-
stone) scrubbing (new plants)
Nonregenerable scrubbing
(existing plants)
Regenerable scrubbing
(new plants)
Physical coal cleaning
Is3 Coal liquefaction (solvent
00 refined cleaning)
Lov-Btu Gas
Pipeline quality
Fluid lied Bed
Refuse combustion
Low sulfur western coals
SIP compliance coal
(Eastern)
Desulfurired residual
90
90
80-95
30-50
75-85
80-98
98+
90+
20
75-85
33-70
85
Incremental
Annual
Energy Cost, Capacity, Likely
% gmnalty. 1 mills/kHh Timing 10° tons Coal Applicability
3-7 3.0 1975-77
3-7 4.4-6.1 1975-77
3-7 3.4-7.0 1980
3-10 0.6-1.6 1974-80
20 10 1985
10-40 6-16 1980-85
1980
40 HA 1980
1985
Minimal 0-3 1985
Minimal Minimal 1985-90
Minimal 0-5.3 I960
Minimal 1.0-3.0 1975
2.0 1980-M
230
(1980)
60
(1980)
—
—
110
13
200
29
50-100
150
50
250
95
MA
All new utilities and large
Industrial boilers
Boilers - 100 MW - 20 yr age
Hew utilities and large
industrial boilers
All coal coobustors
Existing and mine-mouth
power plants, industrial
boilers, small point sources
Rev and large existing
power plants
Snail and area sources
•aw power plants and
industrial boilers
Coal mix, 10-20 refuse
western and fringe eastern
boilers
Eastern existing boilers
Existing oil burners
Other
Environmental
Effects
Waste disposal
problems
Haste disposal
problems
Reduced waste
disposal problems
Land, air, waste dis-
posal at cleaning site
Sulfur and other emis-
sions partially con-
centrated at central
plants; increased min-
ing necessary; uniden-
tified air, water and
solid waste problems
Substantial reductions
in NO, emissions possible
Benefits due to solid
waste reduction
Increased partlculate
control
Also removes Vanadium
Comments
Operation load factor 801,
1000 MM power plant
Operation load factor 601,
300 MW power plant
Limited data on utilization
and costs
Cleaning costs $l.SO/ton
Economics of scale possible
Energy penalty reduced by
combined cycle application.
Capital Intensive.
Minimal energy penalty If
used to replace electric heat
Energy efficiency can be
greater than conventional
power plants
Energy penalty for transpor-
tation to eastern arees
Cost for 1 S or less
compared to 3 S coal
oil 0.3
and other trace elements
-------
TABLE 7-10
SUMMARY DESCRIPTION OF MAJOR FLUE GAS DESULFURIZATIQN PROCESSES (28)
Process
Lime/limestone
scrubbing
Operating Principles
Nonregenerable process/wet
absorption in scrubber by slurry;
insoluble sulfites and sulfates
disposed of as waste
S02 Particulate
Efficiency
Up to 90 percent SO, re-
moval/99 percent fly ash
removal by most scrubbers
Development Status
32 full-scale units (9829 MW) in
operation or planned for start-
up by 1977
Double alkali process
Magnesium oxide
scrubbing
Wellman-Lord
Nonregenerable process/wet
absorption in scrubber; react-
ants and soluble; reaction pro-
ducts precipitated and removed
from recycled reactant solution
outside of scrubber; most common
reactant, sodium sulfite
Regenerable process/wet absorp-
tion by magnesium oxide slurry;
fly ash removed prior to or after
scrubbing; magnesium oxide re-
generated by calcining with car-
bon; S0_ by-product can be con-
verted to sulfuric acid or sulfur
Regenerable process/sodium base
scrubbinjg with sulfite to produce
bisulfite; regeneration in an
evaporative crystalizer. Sulfate
formed either purged or.removed
by selective crystallization
High efficiency 90 percent
S02 removal/high particulate
removal as above
90 percent S02 removal/par-
ticulates removal as re-
quired by prescrubber
90 percent S0~ removal;
particulate removal as above
by pre-scrubber
Active area but no fullscale
demonstration as yet; 2 units
operating; G.M. installed a unit
on a coal-fired boiler in
February 1974; several sulfate
removal schemes under study
One full-scale unit on test at
Boston Edison 150 MW oil-fired
unit; Potomac power unit started
in 1973 (coal-fired 100 MW)
Reliably operated ( 9000 hours)
in Japan; full-scale demonstra-
tation scheduled at Northern
Indiana Public Service coal-fired
115 MW boiler to start December
1975
aTwenty-six units (13772 MW) under consideration have not yet selected a specific FGD process.
Seven'units (655 MW) arc operating or planned uuing processes not summarized here.
-------
TaBLB 7-10 (cont'd)
Process
Lime/limestone
scrubbing
Application
Implementation
Double alkali process
to
t—'
o
Old or new power plant; An additional 21 units
coal- or oil-fired
As above with poten-
tially lower cost and
greater ease of opera-
tion favoring some in-
roads into smaller
plants
Advantages
Cheapest of existing
processes; elimination
of partlculate control
requirement
(10349 MW) planned for in-
stallation by 1980; 15
units (8-99 MW) considered
for unspecified date; 4-5
years lead time needed for
new plants; 3 years retro-
fit of old plants
Research-Cottrell estimates Potentially cheaper and
$600 million a year market more reliable
by 1979; a second genera- than lime/limestone
tion lime/limestone system; system
lead times as above for
power plants
Disadvantages
Waste and water pol-
lution problems; re-
heat of scrubber exit
gases needed; supply
and handling of
large volumes of
reactant may be
problems
Similar to above
and all throw-
away systems
Magnesium oxide
scrubbing
Similar to lime/lime-
stone but oil-fired
boilers will not re-
quire partlculate con-
trol upstream of
scrubber
4 additional units (850 MW)
planned or under consider-
ation; lead times as for
lime/limestone systems
May be more reliable
than lime/limestone
process; no known waste
disposal problems; re-
generation facility need
not be located at utility
Cost of regeneration;
marketing of sulfur
products; reheat
WeiIman-Lord
As above
5 additional units (1800 MW) More reliable than lime/
planned by 1980; lead times limestone system based on
same as for limestone sys-
tems
Japanese experience;
simplicity of unit
operations in regener-
ator; waste disposal
problems reduced
Some bleed of solu-
tion to remove
undesirable reac-
tion products a
source of water
pollution, other-
wise as above
-------
TABLE 7-11
MEASURED MAXIMUM SQ± CONCENTRATIONS
-***—***" ••*2 »Tt""-1*
(30)
Before Modification
Site 1
Site 2
3-Hour
Average
1457
2140
24-Hour
Average
540
1517
Annual
Average
70«
57*
After Modification
Site 1
Site 2
Site 3
Site 4
Site 5
658
458
626
487
589
131
79
157
73
142
17*
9c
15b
10b
v
16b
Federal & Wisconsin
Standard
1300
365
80
NOTE: The symbol "ug" represents mlcrograms.
aJanuary-December 1973
bOctober 1974-September 1975
cMay-October 1974
211
-------
TABLE 7-12
FREQUENCY OF AMBIENT SO CONGENTRATIONS
f; AIR QUALITY STANDARDS (30)
Old Stacks
Site 1
3-hr Average
24-hr Average
Number of
Excesses
1
12
Average
days
per year
0.7
6.9
Percent
of days
per year
0.2
1.9
New Stack
Number of
Excesses
0
0
Site 2
3-hr Average
24-hr Average
13
12
8.8
8.0
2.4
2.2
0
0
212
-------
TABLE 7-13
STACK HETCTTS AND ASSOCIATED GENERATING
CAPACITY OF POWER PLANTS IN THE STUDY
Power Plants Stack Height. Ft Generating Capacity
Steubenville-East Liverpool Area
Sammls
Toronto
Tidd
Cardinal
Windsor*
Mounds ville Area
Burger
Rammer
Mitchell
Southern Area
Willow Island
SpOTO
Kyger
Western Area
Muskingum
Phllo
500
500
850
1,000
650
188
188
825
825
272
272
850
600
600
1,200
13»
216
600
600
535
535
535
825
825
150
150
182
376
386
980
650
172
110
120
600
600
150
150
557
450
225
1,600
60
180
600
450
430
215
430
840
600
100
100
107
*Plant was placed in cold
reserve during 1973.
213
-------
TABLE 7-14
PARTIAL SUMMARY OF POWER PLANT TECHNICAL CONTROL OPTIONS - REMOVAL
AND ENERGY EFFICIENCY, COSTS AND TIMING
Extraction
East coal
Eaet coal
ho
1— > Eeat coal. S.M.
•P-
Veat coal. S.M.
Vut coal, S.M.
Eaat coal. S.H.
Eavc coal, S.M.
Eut coal, S.K.
Eait coal, S.K.
Oil mil. onshore
Tr»n»i>OTtatlon
Rail
Kail
Rail
Rail
Rail
Rail
Rail
Rail
Rail
Oil
pipeline
System
Preceding
Physical coal clean
fhyalcal coal clean
None
None
None
Chemical coal clean
Coal liquefaction
Gaflfy. low Btu
nuldlxed bed
coabuatlon
Refinery
domeatlc
TrantBortatlon
Rone
Hone
Hone
None
None
Done
Rooe
Bone
Hone
Oil
tankei
Ottlltatton
Conr. boiler
Conr. boiler line
ecrubber
Conv. boiler HgO
acmbber
Conv. boiler
Conv. boiler line
ecrubber
Conv. boiler
Conv. boiler
Conv. boiler
Coablned cycle
Conv. boiler
SO,
t^leolona,
lb/10* Ben
2.02
0.2
0.50
1.61
0.16
1.93
0.7
0.017
0.07
1.83
(28)
Overall
Syicen
Efficiency
0.324
0.307
0.349
0.369
O.M9
0.3SO
0.276
0.329
0.376
0.321
Overall
Coot.
MllWWhr
10.0
12.4
11.3
11.3
13.3
10.3
13.2
•10. e
11.2
Eetloated
year of
Application
Current
1973
1980
Current
1975
.1980
1985
1985
1988
Current
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/7-79-090
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
Qf
Cycle Cooling Systems and the Interaction of Stack
Gas and Cooling Tower Plumes
5. REPORT DATE
March 1979
6. PERFORMING ORGANIZATION CODE
7 AUTHOR(S)G.A. Englessonand M.C. Hu (United
Engineers and Constructors, Inc.)
I. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
ameron Engineers, Inc.
1915 South Clarkson Street
Denver, Colorado 80210
10. PROGRAM ELEMENT NO.
EHE624A
11. CONTRACT/GRANT NO.
68-01-4337
12, SPONSORING AGENCY NAME AND ADDRESS
EPA, Office of Research and Development
Industrial Environmental Research Laboratory
Research Triangle Park, NC 27711
13. TYPE OF REPORT AND PERIOD COVERED
Final: 10/77 - 1/78
14. SPONSORING AGENCY CODE
EPA/600/13
NOTES IERL-RTP project officer is Theodore G. Brna, MD-61, 919/541-
The report gives results of a literature survey of the nonwater quality
impacts of closed-cycle cooling systems. Following discussions of cooling tower
and stack gas plumes, interactions of these plumes are considered. For cooling
tower plumes, plume types, behavior, salt drift generation and deposition, and inad-
vertent weather modifications are reviewed. Meteorological conditions enhancing
deposition, icing and fogging, and cloud formation are emphasized. The discussion
of cooling-tower/stack-gas plume interactions focuses on interactions, acid precipi-
tation, case studies of operating power plants, and control practices to reduce or
minimize these interactions. Adverse biological impacts of acid precipitation, cool-
ing tower drift, and icing and fogging on biota are treated. Effects of acid precipita-
tion on soil, soil biota, vegetation, and aquatic biota (including planktonic and benthic
organisms and fish) are considered relative to levels causing harm or injury. This
examination includes: atmospheric and cooling tower salt loading, cumulative effects
of both, and salt tolerances of animals and plants. Emphasis is on threshold concen-
trations at which biota is affected by drift deposition and the distance from the cool-
ing tower where toxic levels result.
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Pollution ice Formation
Electric Power Plants
ooling Towers Fogging
Flue Gases Clouds
Plumes Biology
[eteproloj
station
8. DISTRIBUTION STATEMENT
Unlimited
Soils
Aquatic Biology
Pollution Control
Stationary Sources
Salt Drift
Acid Rain
Biological Impacts
13B 08L
10B
13A,07A,13I 14G
21B
04B
19. SECURITY CLASS (ThisReport)
Unclassified
20. SECURITY CLASS (This page)
Unclassified
21. NO. OF PAGES
131.
06C
080LJ>8M
1A
22. PRICE
EPA Form 2220-1 (9-73)
215
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