EPA-600/3-78-032
March 1978
Ecological Research Series
POWER PLANT COOLING WATER CHLORINATION
IN NORTHERN CALIFORNIA
Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Corvallis, Oregon 97330
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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 ECOLOGICAL RESEARCH series. This series
describes research on the effects of pollution on humans, plant and animal spe-
cies, and materials. Problems are assessed for their long- and short-term influ-
ences. Investigations include formation, transport, and pathway studies to deter-
mine the fate of pollutants and their effects. This work provides the technical basis
for setting standards to minimize undesirable changes in living organisms in the
aquatic, terrestrial, and atmospheric environments.
This document is available to the public through the National Technical Informa-
tion Service. Springfield, Virginia 22161.
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EPA-600/3-78-032
March 1978
POWER PLANT COOLING WATER CHLORINATION IN
NORTHERN CALIFORNIA
by
S. Hergott, David Jenkins, and Jerome F. Thomas
Sanitary Engineering Research Laboratory
College of Engineering
and
School of Public Health
University of California
Berkeley, California 94720
GRANT NO R803959
Project Officer
Donald Baumgartner
Marine and Freshwater Ecology Branch
Corvallis Environmental Research Laboratory
Corvallis, Oregon 97330
CORVALLIS ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CORVALLIS, OREGON 97330
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DISCLAIMER
This report has been reviewed by the Corvallis Environmental Research
Laboratory, U.S. Environmental Protection Agency, and approved for publi-
cation. Approval does not signify that the contents necessarily reflect the
views and policies of the U.S. Environmental Protection Agency, nor does men-
tion of trade names or commercial products constitute endorsement or recom-
mendation for use.
ii
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FOREWORD
Effective regulatory and enforcement actions by the Environmental Pro-
tection Agency would be virtually impossible without sound scientific data on
pollutants and their impact on environmental stability and human health.
Responsibility for building this data base has been assigned to EPA's Office
of Research and Development and its 15 major field installations, one of which
is the Con/all is Environmental Research Laboratory (CERL).
The primary mission of the Corvallis Laboratory is research on the effects
of environmental pollutants on terrestrial, freshwater, and marine ecosystems;
the behavior, effects, and control of pollutants in lake systems; and the de-
velopment of predictive models on the movement of pollutants in the biosphere.
This report adds significantly to our understanding of residual chlorine
behavior in coastal waters. From this work power plants may be able to re-
structure their disinfection programs and reduce the amount of chlorine reach-
ing the environment as well as reducing costs. Regulatory programs may be able
to use the results to improve effluent guidelines and monitoring programs.
i i i
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PREFACE
The concern for the potential toxicity of chlorinated effluents to re-
ceiving waters biota pampered the study of the nature and persistence of oxidant
residuals in power plant cooling water. The study was designed to provide field
information from operating power plants so that actual operating levels of
residual and their persistence could be defined. The investigation was directed
towards power plants close to the San Francisco Bay Area and located on estuarine
of coastal waters.
iv
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ABSTRACT
This research program was designed to determine the nature, levels, and
persistence of "chlorine" residuals in the cooling water effluents of power
plants located in and around the San Francisco Bay Area. Plants were located
at Potrero and Hunters Point (San Francisco Bay), Contra Costa (San Joaquin
River), Pittsburg (Suisun Bay), and Moss Landing (Monterey Bay).
A survey was conducted of chlorination practices at five power plants
owned and operated by the Pacific Gas and Electric Company. Frequency and
duration of chlorination varied significantly from plant to plant and was con-
trolled analytically by the orthotolidine and/or amperometric methods. All the
plants plan to change to using the amperometric method for future control pur-
poses.
In-plant studies were conducted during chlorination cycles to determine
oxidant residuals at both the condenser inlets and at a point near the outfall.
Both free and total oxidant residuals were measured amperometrically for most
studies. The DPD-FAS method was included in later studies to gain a better
understanding of the nature of the oxidant residual. These results indicated
that most of the oxidant residual at the Hunters Point and Moss Landing power
plants was bromine residual.
Decay studies were conducted at the plant sites on the chlorinated cool-
ing water collected at the outfall. The slowest decay was observed at the
Contra Costa plant where the cooling water was the freshest. The most rapid
decay was at the Hunters Point plant. The presence of sunlight increased the
rate of decay at all locations.
Receiving water studies detected maximum total oxidant residuals at the
surface. The distances from the outfall structures to the 0.02 mg/£ total
oxidant isoconcentration line were determined at three power plants. Total
oxidant residuals were measured at the surface of Monterey Bay above a submerged
outfall structure. Toxicity of receiving water oxidant residual levels was
predicted.
This.report was submitted in fulfillment of Grant No. R803959 by the Sani-
tary Engineering Research Laboratory under the sponsorship of the U.-S. Environ-
mental Protection Agency. This report covers the period October 31, 1975 to
December 31, 1976, and work was completed as of June 30, 1977.
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CONTENTS
Foreword iii
Preface iv
Abstract v
Figures ' Vlil
Tables x
Abbreviations and Symbols xi
Acknowledgment xii
1. Introduction 1
2. Material and Methods 2
3. Results 13
4. Discussion 37
5. Conclusions 44
References 46
Appendix 1 Field Data 48
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FIGURES
Number Page
1 Power plant locations 3
2 Contra Costa power plant .... 5
3 Pittsburg power plant 6
4 Hunters Point power plant 7
5 Potrero power plant 8
6 Moss Landing power plant .. . 9
7 Laboratory comparison of DPD-FAS titrimetric and
amperpmetric titration methods 23
8 Percentage loss of TOR between the COND-IN and
the outfall sampling point for various power plants ... 24
9 Results of decay studies conducted at the Contra Costa
power plant, units 6 and 7 outfall 26
10 Results of decay studies conducted at the Hunters Point
power plant, unit 4 outfall 27
11 Results of decay studies conducted the the Potrero power
plant, unit 3 outfall 28
12 Results of decay studies conducted at the Moss Landing
power plant, units 6 and 7 at ISE 29
13 TOR (mgCl2/£) at the surface of the receiving water at
the Contra Costa power plant,units 6 and 7 31
14 TOR (mgCl2/fc) at receiving water surface at the Hunters
Point power plant,unit 4 32
15 TOR (mgCl2/&) at receiving water surface at the Potrero
power plant, unit 3 33
16 TOR (mgCl2/fc) at receiving water surface at the Potrero
power plant, units 1 and 2 34
17 FOR (mgCl2/fc) at the receiving water surface at the Moss
Landing power plant, unit 6 35
18 Time required for 99% conversion of free chlorine to
HOBr at 25°C and a pH of 8.3 38
19 Principal species of bromine and bromamine after 1-2 min
at various pH and ammonia to bromine ratios 40
20 In-plant study at the Contra Costa power plant 20 Jan
1976, unit 6, condenser #11 49
21 In-plant study at the Contra Costa power plant 10 Feb
1976, unit 7, condenser #14 50
22 In-plant study at the Contra Costa power plant 6 Jun
1976, unit 7, condenser #13 51
23 In-plant study at the Contra Costa power plant 14 Sep
1976, unit 6, condenser #11 52
24 In-plant study at the Hunters Point power plant, 16 Dec
1975, unit 4 . . 53
» »
vm
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FIGURES (continued)
Number Page
25 In-pi ant study at the Hunters Point power plant,17 May
1976, unit 4 54
26 In-plant study at the Hunters point power plant, 26 Aug
1976, unit 4 55
27 In-plant study at the Potrero power plant,23 Feb 1976,
unit 3, N. condenser 56
28 In-plant study at the Potrero power plant, 4 Mar 1976,
unit 3, N. condenser 57
29 In-plant study at the Moss Landing power plant, 12 Apr
1976, unit 7 58
30 In-plant study at the Moss Landing power plant, 19 Apr
1976, unit 7 59
31 In-plant study at the Moss Landing power plant, 14 Jul
1976, unit 6 60
32 In-plant study at the Moss Landing power plant, 14 Jul
1976, unit 7 61
33 In-plant study at the Moss Landing power pi ant,22 Jul
1976, unit 6 62
34 In-plant study at the Moss Landing power plant,5 Aug
1976, unit 7 63
35 In-plant study at the Moss Landing power plant, 23 Sep
1976, unit 6 64
ix
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TABLES
Number Page
1 Power plant operating data 2
2 Chiorination practices at PG&E power plants 10
3 Summary of field study results at Contra Costa power
plant, units 6 and 7 14
4 Water quality and tidal data at the Contra Costa power plant . 15
5 Summary of field study results at the Hunters Point Power
plant (unit 4) and Potrero power plant (unit 3) 17
6 Water quality and tidal data at the Hunters Point and
Potrero power plants 18
7 Summary of field study results at the Moss Landing power
plant, units 6 and 7 19
8 Water quality and tidal data at the Moss Landing power plant . 20
9 Summary of loss of oxidant residual within the power plant
cooling water system 25
10 Summary of decay studies 30
11 Acute and chronic doses of chlorine to marine freshwater
organisms (Mattice and Ziettel) (3) 42
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ABBREVIATIONS AND SYMBOLS
COND-IN -- Condenser inlet sampling point
COND-OUT -- Condenser outlet sampling point
DPD -- N,N-diethyl-p-phenylenediamine
FAS Ferrous ammonium sulfate
FOR Free oxidant residual, mgCl2/&
INJ-PT -- Chlorine injection point
ISE Sampling point at International Shellfish
Enterprises, Inc.
MW Megawatt
OT ~ Orthotolidine method
OUT -- Outfall sampling point
PAO Phenylarsine oxide
PG&E ~ Pacific Gas and Electric Company
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ACKNOWLEDGMENTS
We wish to thank numerous people at the Pacific Gas and Electric Company
who gave us their complete cooperation and much valuable assistance: the
plant superintendents - Mr. D.L. Nix, Mr. M. Samaii, Mr. 0. Pridmore, Mr. R.
Puckett; the plant chemists and chemical engineers - Mr. E. Garcia, Mr. E.
Holt, Mr. S. Chun, Mr. M. Sransjo, Mr. M. Bush; and in the San Francisco
office special thanks are due to Mr. T. Casebolt, Mr. G. Sanders,, and Dr.
C. Walton.
Mr. R. Eissenger and Mr. M. Cox of the International Shellfish Enterprises,
Inc. were very helpful in allowing us to set up a sampling station for Moss
Landing power plant cooling water. Ms. P. Elliot of the California State
Marine Laboratory at Moss Landing arranged for the use of a boat for the re-
ceiving water studies. Dr. J. Elder of Tetra Tech, Inc., Lafayette, Ca.,
allowed us time during his sampling schedule for receiving water studies at
Contra Costa and Pittsburg using a boat owned by Mr. T. Glimme of Parameter
Research. Mr. J. J. Connors of the East Bay Municipal Utility District allowed
us the use of an amperometric titrator while we were awaiting delivery of new
ones. Mr. R. Sakaji, M.S. candidate in Sanitary Engineering, University of
California, Berkeley, was a research assistant on the project and contributed
greatly to its conduct.
The Environmental Protection Agency project officer was Dr. D. Baumgartner,
whose assistance and patience are gratefully acknowledged. Mr. Fred Roberts
of the Corvallis Office of EPA is thanked for reviewing this report.
xn
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SECTION I
INTRODUCTION
Power plants require large volumes of cooling water to carry away waste
heat. Bacterial and algal slimes will attach themselves to the walls of the
piping and decrease the heat transfer across the condensers if fouling is not
controlled. The most economical method currently used to control fouling is
the addition of chlorine to the cooling water.
Chlorine presents problems when its toxic effects carry over into re-
ceiving waters. Brungs (1) conducted a comprehensive review of the litera-
ture dealing with chlorine toxicity to freshwater fish for both continuous
and intermittent treatment. Based on these studies he recommended inter-
mittent chlorine limits in the discharge of power plants that vary from
0.2 mg/i to 0.04 mg/Jl total residual for up to 2 hr per day depending on the
degree of protection desired. Basch and Truchan (2) studied the effect of
intermittent chlorination on brown trout (Salmo trutta) at five Michigan power
plants. They found the 48-hr total residual chlorine intermittent concentra-
tions lethal to 50 percent of the brown trout to range from 0.14 to 0.17 mg/£
and 0.18 to 0.19 mg/£ for fish exposed to two and four 30 min chlorination
cycles, respectively. Mattice and Zittel (3) conducted a comprehensive review
of the literature dealing with the toxicity of chlorine to both freshwater and
marine organisms. Based on this research they determined both acute and
chronic toxicity thresholds and conclude that marine organisms appear more
susceptible to acute doses of chlorine whereas freshwater organisms appear
more susceptible to chronic concentrations.
The increasing awareness of the toxicity of chlorine residuals has
prompted regulatory control of chlorine discharges in power plant cooling
waters. The Environmental Protection Agency has established free chlorine
discharge guidelines of 0.5 mg/£ maximum and 0.2 mg/£ average concentration for
up to two hours per day from any one unit (4). The California Central Coast
Regional Water Quality Control Board has set daily maximum limits of 0.02
mg C12/& undissociated free available chlorine and 0.1 mg C12A total avail-
able chlorine in power plant discharges (5). The San Francisco Bay Regional
Water Quality, Control Board has set even stricter limitations of an instan-
taneous maximum chlorine residual of 0.0 mg/£ (6).
This study was conducted to determine the nature, levels, and persistence
of chlorinated compounds in the discharges of five power plants in Northern
California. In-plant studies were conducted to understand the demands for
chlorine in the cooling water system and to determine the levels reaching
the receiving waters. Decay studies conducted at the outfalls together with
measurements of oxidant residuals in the receiving water provide a base for
estimating the persistence and zone of influence of the chlorinated compounds.
1
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SECTION 2
MATERIAL AND METHODS
POWER PLANT LOCATION AND DESCRIPTION
A map showing the location of the five power plants studied is presented
in Figure 1. Water quality varied from fresh at Contra Costa to marine at
Moss Landing.
A summary of the operating data for each plant is presented in Table 1.
All the plants have the capability of burning either fuel oil or natural gas.
The plants rarely operated at maximum capacity. Usually the newer, more
efficient units in any plant operated continuously and the older units were
used during peak demand periods and during periodic shutdowns of the other
units.
TABLET. POWER PLANT OPERATING DATA
POWFR GROSS GENERATING Nn OF
KUWhK CAPACITY
PLANT (MW) UNITS
Contra Costa
Pittsburg
Hunters
Poi nt
Potrero
Moss Landing
1300
2060
400
330
2110
7
7t
3
3
7
SOURCE OF
INTAKE WATER
San Joaquin
River
Suisun Bay
San Francisco
Bay
San Francisco
Bay
Monterey Bay
COOLING WATER
FLOWRATE*
(m3/sec)
43.2
45.4
18.2
16.5
63.1
(gpm)
684,000
720,000
288,000
262,000
1,000,000
*A11 units in operation.
tUnit 7 cooled by a spray canal.
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HUNTERS
POINT
SACRAMENTO
MONTEREY
BAY JA MOSS LANDING
MONTEREY
t
T
SCALE I IN. = 2O.5 Ml.
Figure 1. Power plant locations.
-------
Plan diagrams of the once-through cooling water systems at each of the
power plants are presented in Figures 2 to 6. Cooling water is diverted
from its source and pumped through the cooling system by circulating water
pumps located at the intake structures. The cooling water first passes
through bar racks which prevent large objects from entering the system.
Smaller objects are removed by travelling screens which rotate periodically
and are cleaned with high pressure water.
Heat exchange between cooling water and saturated steam occurs in the
condensers which consist of bundles of 22.2 mm (7/8 in.) or 25.4 mm (1 in.)
diameter aluminum-brass or copper-nickel alloy tubes. There is one condenser
per unit which is divided into two halves. The heated flows of cooling water
combine immediately after the condenser and are discharged to the receiving
water at the outfall structure.
Cooling water sampling locations are indicated for each power plant in
Figures 2 to 6. Cooling water could generally be sampled at the condenser
inlets (COND-IN), condenser outlets (COND-OUT), and at outfall manholes (OUT)
Very convenient sample taps had been set up at the COND-IN because this was
where oxidant residuals were routinely measured by plant operating personnel.
Sampling at the COND-OUT was more difficult even though taps generally existed
or were readily installed because samples had to be pumped out against a vacuum
of about 25.4 cm (10 in.) of mercury. Outfall manholes generally existed as
part of a discharge structure so that samples taken from these manholes were
representative of the water being discharged to the receiving water. At Moss
Landing, Units 6 and 7 discharged into Monterey Bay,.242 m (800 ft) off shore,
at a depth of 6.1 m (20 ft). A sampling point approximately midway between
the condensers and the outfall was furnished by the International Shellfish
Enterprises, Inc. (ISE).
CHLORINATION PRACTICES
Chlorine is injected intermittently into the cooling water flow to con-
trol slime-causing organisms. In PG&E plants, liquid chlorine is withdrawn
from one-ton cylinders, evaporated, and injected into a water line to produce
a concentrated chlorine solution. This solution flows to the point of in-
jection in a well behind the travelling screens and in front of the circulat-
ing water pumps. Oxidant residuals are routinely measured at the COND-IN
and the chlorine injection rate is adjusted to give the desired residual.
These adjustments are rarely needed on a daily basis, however the residual
monitoring is important to insure proper operation of the chlorinators which
are somewhat unreliable when subjected to the frequent startups and shutdowns
encountered in intermittent chlorination.
A summary of chlorination practices for the newest units at each of the
five PG&E power plants is presented in Table 2. The newest units were chosen
for study because they were the largest and most frequently operated. A
great deal of variation in frequency, duration, and levels of chlorination
existed. Frequency varied from I/week to 4/day and was changed during the
year to meet changing demands. Duration of chlorination ranged from 15 to 40
min. All the plants seek to maintain a 0.5 mg/£, residual at the COND-IN
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SAN JOAQUIN RIVER
iHf
\
COOLING WATc.0
INTAKE STRUCT JRI
UNITS 8 IT
1
WTAW UPES "SlA
UNITS «i7 w \
%.-
-^,
V4
I1
TURBINE
GENERATOR
BUILDING
UNITS (IT
T
R^CMSCHAROE PIPES
; UN.T56t7
0
PLAN
100 200 300
400 FT
O SAMPLING LOCATIONS
Figure 2. Contra Costa Power Plant
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-------
Cnlonne.
inection
o
Coo/ma Ivtr.
Intake
Discharge.
Structure.
Unit
Structure.
conduits Unit /
Structure.
Units
Unit-1
af/sc/ira.
tunnel
Unit*
discharge
Structure.
turb
oerierator
Unit
0/isc.harge.
-turbine ' aenerator
Csofina Wtr.
Intaiu?
+ftjcturc
Units 12(3
chlorine.
inection
ntake, tunncj
Units /, Z, (3
50 100 ISO ZOO FT.
SAMPLING LOCATIONS
Figure 4. Hunters Point Power Plant.
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co
Francisco Soy
Coo/sna
/nfakt
Units t
DfSCJtorae
Structure n
Unit 3^ \
In-tairt Structure.
Unit
, ] flety FM
Area
Turbine.
Generator
Building
Unit 3 ?
Chlorine /r>jec*>on
SAMPLING LOCATIONS
Turbine
Generator
Quildina
Units / JZ
Units
X 2
[| '.di3chQrg(
H4 conduit-
0
KX) 230 JOO iOOFT.
Figure 5. Potrero Power Plant.
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'*,T ^><&
SHELLFISH //-^ S^
ENTERPRISES
( ISE)
SAMPLING LOCATIONS
PLAN
2&Q400 600
Figure 6. Moss Landing Power PI ant.
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TABLE 2. CHLORINATION PRACTICES AT PG&E POWER PLANTS
POWER
PLANT
CONTRA COSTA
PITTSBURG
HUNTERS POINT
POTRERO
MOSS LANDING
UNIT(S)
6,7
5,6
4
3
6,7
CHLORINATION SCHEDULE
FREQUENCY
I/week
Varies with Season
Min. , I/week
Max. , I/day
4/day
2/day
I/day
DURATION
(min)
40
30
30
30
30
15
CRITERIA
AT
COND- IN
(mg Cla/O
TOR ,0.5
TOR, 0.5
FOR ,0.5*
TOR, 0.5*
TOR, 1.0
ANALYTICAL METHOD
NOV. 1975
Ampero-
metric
OT
Ampero-
metri c
OT
OT
CURRENT/FUTURE
Amperometri c
Arnperometric
Amperometri c
Amperometri c
OT/Amperometric
*Lowered to 0.4 mg/5, in January 1977.
OT = Orthotolidine Method.
TOR = Total Oxidant Residual.
FOR = Free Oxidant Residual.
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except .for Moss Landing where a 1.0 mg/£ residual for a shorter duration was
used. Hunters Point was the only plant to measure a free residual and use it
as their criterion for dosing. The orthotolidine (OT) method was used at all
the plants until recently because it was the most portable and was the easiest
for the operators to learn and use. All the plants are currently using or are
in the process of changing over to the amperometric titration method.
FIELD STUDY PROCEDURES
In-Plant Studies
Field studies were conducted at four of the power plants. No studies were
conducted at the Pittsburg plant because no convenient sampling point existed
near the outfall. Studies were conducted during normal chlorination cycles
and were designed to monitor existing chlorination practices, therefore no
changes were made in chlorine injection rate, duration, or frequency of
chlorination cycles to accommodate this work.
At the beginning of the study, oxidant residuals were determined solely
by the amperometric method. During the course of the investigation, the DPD-
FAS titrimetric method was added in an attempt to distinguish between bromine
and chlorine residuals.
Cooling water samples were collected for the determinations of the water
quality parameters listed in Tables 4, 6, and 8. At the COND-IN triplicate
1-liter grab samples were taken before, during, and after chlorination, both
from a condenser being chlorinated and from one that was not. Samples were
taken at the outfalls during chlorination. A small excess of sodium arsenite
was added to all samples taken during chlorination to destroy oxidant residuals.
No interference from this procedure was found in any of the analytical methods
but there was some evidence that the sodium arsenite did not always react
instantaneously with the oxidant residual. This would probably result in
lower concentrations of NHs-N and organic nitrogen in those samples taken
during chlorination.
Decay and Receiving Water Studies
Decay studies were conducted on chlorinated cooling water collected at the
outfalls. Two 8-liter (2.1 gal } containers lined with polyethylene bags were
filled with cooling water. One container was covered to exclude sunlight.
No effort was made to keep temperatures constant. Oxidant residuals were
determined by the amperometric titration method in both containers over a
period of approximately 60 min.
Total oxidant residuals were determined in receiving waters by forward
amperometric titrations at all plants except Moss Landing where samples were
taken for later titration using the back titration method for free oxidant
residual. This was necessary because of the turbulence and wave action at
the outfall which caused the micrometer needle of the titrator to vibrate and
made the end-point very difficult to read. Receiving water samples were
generally taken at the surface although some samples were taken at depths of
11
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1,2, and 3m (3.3, 6.6, and 9.9 ft). Sampling point locations were determined
by reference to features on shore and in some cases by a rope attached to the
outfall structure.
ANALYTICAL METHODS AND EQUIPMENT
Oxidant-Residual Measurement
Amperometric Titration
Oxidant residuals were determined amperometrically using Fischer and
Porter (Model 17T1010) portable titrators. Total oxidant residuals (TOR)
were determined by a direct titration according to Standard Methods (7). TOR
could be determined in approximately 1.5 min by applying some suggestions
made by Manabe (8). These included the use of a graduated cylinder modified
to measure a 200 m£.sample quickly and the addition of up to 90% of the titrant
before turning on the stirrer. The back titration procedure described by
White (9) for the determination of free oxidant residual (FOR)'was adopted
because of an unstable end-point experienced during a direct titration. The
term "oxidant residual" has been used rather than "chlorine residual" because
the amperometric method measures bromine and iodine residuals in addition to
chlorine residuals.
DPD-FAS Titrimetric Method
The DPD-FAS titrimetric method of Palin (10,11,12) was used to distinguish
chlorine and bromine residuals. Three separate titrations give: (A) free
chlorine plus free and combined bromine; (B) combined chlorine; (C) free and
combined bromine. The separate determination of free and combined bromine is
not possible. Some anomalous results were obtained using this method in some
of the saline waters.
Water Quality Measurement
Organic nitrogen, chloride, bromide, and suspended solids were all de-
termined according to Standard Methods (7). Ammonia-nitrogen was determined
by the phenolhypochlorite method of Solbrzano (13). This method was found to
be well suited for fresh, marine, and estuarine waters by Zadorojny et al.(14).
12
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SECTION 3
RESULTS
IN-PLANT STUDIES
Persistence and decay of oxidant residuals at the outfalls and in the
receiving waters can best be explained after the nature and disappearance of
the residual inside the plants are understood. The in-plant studies were
conducted to establish the nature of the oxidant residual and to gain an
understanding of the demands in the cooling water systems at each of the power
plants. Each plant was studied separately because of variations in water
quality, chlorine dosage, frequency and duration of chlorination, and flow
time through the system.
In-plant studies were conducted over a period of one year to be inclusive
of varying water quality conditions. Results at each of the four plants
studied are presented in Appendix 1 (Figures 20 to 35). The graphs show the
temporal variation of oxidant residual during a chlorination cycle. Also
shown is the chlorine dose calculated on the basis of the chlorine injection
rate determined by power plant personnel and the cooling water flow rate.
The calculated dose may not be precise because the chlorine injection rate
was difficult to read accurately and the only value usually known for the
cooling water flow rate was the original design value.
Contra Costa Power Plant
The results of the in-plant field studies conducted at the Contra Costa
Power Plant are summarized in Table 3. Water quality and tidal data corre-
sponding to most of these studies are presented in Table 4.
A combined residual of from 0.10 to 0.40 mg Cl2/£ formed by the time the
cooling water reached the COND-IN, (approximately 1.2 min of flow time) and
generally remained unchanged at the outfall when the dilution effect was taken
into account. It appeared that the FOR which disappeared accounted for most
of the loss of residual between the COND-IN and the outfall.
The DPD-FAS results for the study of 14 September 1976 indicated a com-
bined chlorine residual of 0.10 rngA at the COND-IN and 0.03 mg/£ at the out-
fall, both of which compare favorably with the amperometric titration results.
The FOR of 0.20 mg C12A determined amperometrically titrates as bromine
residual by the DPD-FAS method since titration "A" equals titration "C".
Cooling water at Contra Costa varied from 0.3% to 6.1% seawater. Most
of the water quality data show the effects of tidal changes. The addition of
13
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TABLE 3. SUMMARY OF FIELD STUDY RESULTS AT CONTRA COSTA POWER PLANT
UNITS 6 AND 7
DATE
20 Jan
10 Feb
16 Jun
14 Sep
DOSE
CALCULATED -
mgCl2/£
76 1.6
76 1.6
76 1.2
76 1.3
AMP.
TOR
mgCl.A ,
0.75
0.50
0.55
0.30
CONDENSER- INLET
TIT. DPD-FAS*
FOR A B C
TigCl2AmgCl2AmgCl2MmgCl2/*
0.45
0.10
0.36
0.20 0.20 0.10 0.20
OUTFALL MANHOLEt
AMP.
TOR
mgCWl
0.18
0.23
0.18
0.04
TIT.
FOR
mgCW*
0.03
0.00
0.08
0.00
DPD-FAS*
ABC,
mgC!2/£ mgCl2/£ mgC!2/&
_-
0.00 0.03 0.00
*Results of three titrations are: A = Free chlorine plus bromine residuals.
B = Combined chlorine residuals
C = Bromine residuals
tChlorinated cooling water flow was diluted with an approximately equal volume of unchlorinated
water immediately after the condenser.
-------
TABLE 4. WATER QUALITY AND TIDAL DATA AT THE CONTRA COSTA POWER PLANT
DATE/SAMPLE
20
#11
#14
10
#13
#13
#13
16
#13
#13
#13
7
#13
14
#11
#12
#11
6
#13
Jan 1976
COND-IN
COND-IN
Feb 1976
COND-IN
COND-IN
COND-IN
Jun 1976
COND-IN
COND-IN
COND-IN
OUT DUR
COND-IN
Sept 1976
COND-IN
COND-IN
COND-IN
OUT DUR
COND-IN
DUR
DUR
BEF
DUR
AFT
BEF
DUR(+)t
DUR(-)f
T
AFT
BEF
DUR(+)t
DUR(-)t
AFT
NH3-N
mg/£
0
0
0
0
0
0
0
0
0
0
0
0
0
.04*
--
.11*
.09*
.10*
.091
.066
.078
.082
.078
_ _
.019
.012
.009
.017
Org-N
mg/£
0
0
0
0
0
0
0
0
0
0
0
0
0
0
.13
.29
.21
.20
.42
.40
.43
.41
.36
.33
.31
.33
.34
.32
Cl"
mg/£
50
50
563
648
901
1180
1019
__
__
746
1032
913
-«
761
Br"
SUSP
SOLIDS TIME OF TIDAL DATA
mg/a rng/X, P" "'^ TIME ELEVATION, ft§
_
-
1
1
1
3
3
3
3
2
3
_
3
.
3
-r
-
.2
.6
.9
.9
.6
.5
.4
.8
.9
_
.5
..
.4
22 0930-1200 Hi 0602
19 -- Lo 1213
42 0930-1120 Hi 1039
30 -- Lo 1841
35
111 7.5- 1010-1100 Hi 0646
118 7.7 Lo 1415
128
114
88
34 7.7- 1030-1250 Hi 0835
37 8.0 Lo 1403
34
32
41
+3.9
+1.0
+4.0
+0.2
+3.8
-0.2
+3.0
+1.4
*Determined by nesslerization.
tSamples taken during chlorination cycle from the condenser being chlorinated.
^Samples taken during chlorination cycle from a condenser not being chlorinated.
§Ft above datum at Golden Gate Bridge.
-------
chlorine generally caused a decrease in amnonia-nitrogen concentrations but
this was more evident at the other power plants. Compared with earlier studies
the much lower combined residual detected on 14 September 1976 is explained
by the very low NH3-N concentration.
Hunters Point and Potrero Power Plants
The results of the in-plant studies conducted at the Hunters Point and
Potrero Power Plants are summarized in Table 5. Water quality and tidal data
corresponding to these studies are presented as Table 6.
In general FOR equalled TOR both at the COND-IN and at the outfall. An
exception was the study of 17 May 1976 which detected a combined residual at
the outfall of 0.13 mg C12A which had formed during the approximately 0.9
min of flow time from the COND-IN.
The DPD-FAS results for the study of 26 August 1976 at Hunters Point
revealed a small combined chlorine residual at the COND-IN which the ampero-
metric method failed to detect. The DPD results at the COND-IN are difficult
to explain since titration C should never be greater than titration A. At
the outfall a total residual of 0.45 mg Cl2/fc was identified as bromine
residual by the DPD-FAS method.
A TOR of 1.0 mg C12A was desired at the COND-IN for the studies of 23
February 1976 and 4 March 1976 at the Potrero Power Plant. This criterion
was lowered to 0.5 mg/fc and was the criterion during the studies on the 15th
and 17th of October 1976. The studies of 4 March 1976 and 15 October 1976
revealed essentially no loss of oxidant residual between the COND-IN and
outfall manhole which corresponded to a flow time of approximately 0.4 min.
Cooling water at Hunters Point and Potrero varied from 79% to 96% sea-
water. Ammonia-nitrogen concentrations determined on samples collected at the
COND-IN decreased by up to 0.091 mg/£ during chlorination. A decrease in
organic nitrogen was also evident during chlorination.
Moss Landing Power Plant
The results of the in-plant studies at the Moss Landing Power Plant are
summarized in Table 7. Water quality and tidal data are presented in Table 8.
The results generally indicate much higher oxidant residuals at the COND-
IN than the 1.0 mg/Jl desired by the plant chemist. Measurements by the
amperometric and DPD-FAS methods were often on the order of two times the
value determined by the plant chemist during the OT method.
At the COND-IN, FOR was generally greater than or equal to TOR. Since
FOR can never be greater than TOR, an error (probably in the TOR measurement)
was indicated. Approximately 1 min was required to measure out a 200 mH
sample, transfer it to the titration jar, add the KI and pH 4 buffer, and
perform the TOR titration. During this time the oxidant residual was
reacting with species in the water and decaying. On the other hand, the
back titration method for FOR fixes the concentration as soon as the sample
16
-------
TABLE 5. SUMMARY OF FIELD STUDY RESULTS AT THE HUNTERS POINT POWER PLANT
(UNIT 4) AND POTRERO POWER PLANT (UNIT 3)
C12
DOSE
CALCULATED
DATF
AMP.
TOR
mgd2/£ mgCl2/£
Hunters
16
17
26
19
Dec
May
Aug
Oct
Pt.
76
76
76
76f
1
1
2
1
.6
.6
.5
.2
0.
0.
1.
0.
85
72
00
65
TIT
CONDENSER- INLET
DPD-FAS*
FOR A B C
mgCl
_
0.
1.
0.
2/fc mgC";2/£ mqCl2/& mgCl2/&
_ _ _ - -
72
00 0.60 0.10 0.90
65
m
0
0
0
0
OUTFALL MANHOLEt
AMP. TIT. DPD-FAS*
TOR FOR A B
gCl2/*mgCl2/£mgCl2/*mgCl2/£r
.50
.50 0.37
.70 0.70 0.45 0.00
.24 0.24
C
ngCl2/l
0.45
--
Potrero
23
4
15
27
Feb
Mar
Oct
Oct
76
76
76
76
2
1
0
0
.0
.6
.9
.9
1.3-1.5
0.8-
0.73
0.73
1.0
-
-
_
_
0
0
0
0
.5-0.6 -
.4-0.5 -
.35
.28
__
--
--
M *
*Results of three titrations are:
A = Free chlorine plus bromine residuals.
B = Combined chlorine residual.
C = Bromine Residuals.
tHunters Point - the cooling water flows through both condensers of Unit 4 and are chlorinated simultan.
Potrero - Chlorinated cooling water was diluted with an approximately equal volume of unchlorinated
water immediately after the condensers.
^Cooling water flows through the condensers were chlorinated separately for this study.
-------
TABLE 6. WATER QUALITY AND TIDAL DATA AT THE HUNTERS POINT AND POTRERO POWER PLANTS
00
DATE/SAMPLE -
Hunters Point
16 Dec 75
COND-IN DUR
17 May 76
COND-IN BEF
COND-IN DUR
OUT DUR
COND-IN AFT
26 Aug 76
COND-IN BEF
COND-IN DUR
OUT DUR
COND-IN AFT
Potrero
23 Feb 76
N. COND-IN BEF
N. COND-IN DUR
OUT DUR
N. COND-IN AFT
4 Mar 76
N COND-IN BEF
N COND-IN DUR
OUT DUR
S COND-IN AFT
NH3-N
mg
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
i/l
06*
134
047
036
119
128
037
024
140
055
000
032
075
118
059
077
104
Org-N
mg/
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
i.
33
18
08
03
14
34
28
28
36
27
20
21
26
20
16
21
17
Cl"
g/A
15.4
18.2
17.7
--
17.9
18.7
--
18.4
16.8
16.5
16.5
16.4
16.7
16.8
--
16.8
Br-
mg/fc
71
70
__
70
72
__
__
73
67
71
70
71
63
64
--
66
S.S.
nH
pn
mg/A
14
27 7.0
19
19
21
31 7.5
28
28
27
13
11
12
10
18
15
17
20
TIME OF
TIDAL
DATA
STUDY TIME ELEVATION
it
1100-1145
1040-1120 Hi
Lo
1040-1120 Hi
Lo
2100-2215 Hi
Lo
2100-2215 Hi
Lo
1655
0959
1422
0813
2026
2509
2625
2000
+5
-1
+7
+1
+4
+2
+5
+1
.8
.1
.1
.6
.8
.7
.7
.6
*Determined by nesslerization.
tFt above datum at Golden Gate Bridge.
-------
TABLE 7. SUMMARY OF FIELD STUDY RESULTS AT THE MOSS LANDING POWER PLANT
UNITS 6 AND 7
DATF
C12
DOSE
PAl Pill ATFI"
CONDENSER- INLET
AMP.
»
onLOULn l L.U
TOR
mgCl
12 Apr
19 Apr
14 Jul
22 Jul
5 Aug
23 Sep
76
76
76
76
76
76
2.
2.
2.
2.
1.
2.
2/1
2
2
1
1
3
1
mgCl2/Jl
1.35-
1.65
1.45-
2.10
1.40-
1.80
1.30-
2.10
0.80-
1.20
1.00-
1.70
, TIT.
FOR
mgCl2/£
1.60-
1,90
1.40-
2.20
0.90-
1.35
1.00-
1.80
DPD-FAS*
A
mgC!2/£
--
1.70-
2.00
1.25-
1.65
0.50-
0.80
1.10-
1.70
B
mgC!2/£
--
0.00
0.00
0.05
0.00
C
mgCla/fc
--
1.80-
2.20
1.60-
2.00
0.70-
1.20
1.70-
2.20
AMP.
TOR
mgCl2/£
0.15-
0.18
0.23-
0.31
0.15-
0.20
0.05-
0.15
0.24-
0.40
ISE SAMPLING POINTt
TIT.
FOR
mgd2/£
0.10-
O.T4
0.05-
0.10
0.30-
0.40
DPD-FAS*
ABC
mgCl2/& mgC!2/£ mgC!2A
0.08- 0.05- 0.03-
0.11 0.10 0.05
*Results of three titrations are: A = Free chlorine plus bromine residual.
B = Combined chlorine residual.
C = Bromine residual.
tChlorinated cooling water was diluted with an approximately equal volume of
unchlorinated water immediately after the condensers.
-------
TABLE 8. WATER QUALITY AND TIDAL DATA AT THE MOSS LANDING POWER PLANT
ro
o
DATE/SAMPLE
12 Apr 76
7-1 COND-IN
7-2 COND-IN
7-1 COND-IN
7-2 COND-IN
19 Apr 76
7-1 COND-IN
7-2 COND-IN
7-1 COND-IN
7 ISE DUR
7-2 COND-IN
14 Jul 76
6-1 COND-IN
6-2 COND-IN
6-1 COND-IN
6 ISE DUR
6-1 COND-IN
22 Jul 76
6-1 COND-IN
6-2 COND-IN
6-1 COND-IN
6-1 COND-IN
BEF
DUR(+)*
DUR(-)t
AFT
BEF
DUR(+)*
DUR(-)t
AFT
BEF
DUR(+)*
DUR(-)t
AFT
BEF
DUR(+)*
DUR(-)t
AFT
NH3-N
mg/Si
0.096
0.021
0.114
0.137
0.058
0.005
0.033
0.016
0.037
0.046
0.000
0.038
0.010
0.047
0.072
0.010
0.120
0.093
Org-N
mg/H
0.20
0.09
0.19
0.25
0.16
0.08
0.12
0.10
0.04
0.19
0.19
0.19
0.19
0.19
0.30
0.19
0.30
0.26
Cl"
gM
19.0
18.7
18.8
18.5
18.9
19.0
18.8
19.1
18.6
--
--
19.1
18.8
18.9
Br~
mg/Ji
78
82
81
82
68
70
67
74
82
--
--
--
80
78
--
74
SUSP.
SOLIDS
mg/£
19
22
21
21
31
14
15
19
20
12
14
8
12
8
15
9
11
10
TIME OF
- pH STUDY
7.9- 1240-
8.0 1330
7.8 1300-
1350
8.1- 1300-
8.2 1400
8.0- 1300-
8.1 1350
TIDAL
TIME
Hi
Lo
Hi
Lo
Hi
Lo
Hi
Lo
0838
1438
1533
0840
1403
0720
0908
1327
DATA
ELEVATION
ft
+4
+0
+4
-0
+4
-0
+3
+2
.7
.5
.1
.6
.8
.4
.5
.8
(continued)
-------
TABLE 8 (continued)
DATE/SAMPLE
NH3-N
mg/£
Org-N
mg/l
Cl"
gA
Br"
mg/fc
SUSP. TIDAL
SOLIDS _u TIME OF IIUrtL
" CTiinv
mg/£ blUUY TIME
5 Aug 76
6-1
6-1
6-2
COND-IN
COND-IN
COND-IN
BEF
DUR(+)*
DUR(-)t
6 ISE DUR
6-1
23
6-1
6-1
6-2
COND-IN
Sept 76
COND-IN
COND-IN
COND-IN
AFT
BEF
DUR(+)*
DUR(-)t
6 ISE DUR
6-1
COND-IN
AFT
0
0
0
0
0
0
0
0
0
0
.074
.016
.072
.045
.074
.052
.045
.071
.017
.103
0.
0.
0.
0.
0.
0.
22
17
21
17
23
19
18.8
19.1
18.7
73
--
70
70
23 8.2- 1300- Hi 0826
1
1
1
1
0.25
0.
0.
0.
22
16
30
--
18.6
67
8 8.3 1400 Lo 1307
8
6
8
3 8.9 1300- Hi 1044
5 1350 Lo 1656
4
2
4
DATA
ELEVATION
ft*
+3.8
+2.7
+5.4
+0.3
*Samples taken during chlorination cycle from the condenser being chlorinated.
tSamples taken during chlorination cycle but from a condenser not being chlorinated.
above datum at Golden Gate Bridge.
-------
is mixed with excess phenylarsine oxide and pH 7 buffer. Another contributing
factor to this result was the flashing off of iodine during stirring in the
forward titration for TOR.
The DPD-FAS results indicated little or no combined chlorine residual
at the COND-IN. Some combined chlorine was indicated at ISE both by the
amperometric and DPD-FAS methods. Most of the DPD-FAS results must be re-
garded with suspicion because of the discrepancy between titrations A and C.
Cooling water at Moss Landing varied from 95% to 99% seawater. Ammonia-
nitrogen concentrations determined on samples collected at the COND-IN decreased
by up to 0.075 mg/Ji due to chlorination. A decrease of organic nitrogen during
chlorination was observed in 4 of the 6 studies.
Summary
The DPD-FAS titri metric method was added to the field studies to gain a
better understanding of the nature of the oxidant residual at the power plants.
The results of two studies that were conducted in the laboratory comparing this
method with the amperometric method are presented in Figure 7. Chlorine
(sodium hypochlorite) was added to 4-liter samples of San Francisco Bay water
and oxidant residuals were determined for a period of 40 min. A good correla-
tion between FOR determined amperometrically and titration A of the DPD-FAS
method was obtained. TOR determined by the amperometric method was equal to
or slightly less than TOR calculated from the DPD-FAS results (titration A
plus B). The discrepancy between amperometric and DPD TOR data appeared to
result from the underestimation of combined chlorine residual by the ampero-
metric method. Results of titration C indicated that most of the FOR was
bromine residual.
Table 9 summarizes the disappearance of oxidant residual observed for all
the in-plant studies. Loss of residual is expressed as a percentage of the
chlorine dose. The table does not included the decrease of oxidant residual
due to dilution immediately after the condensers. The measured TOR at the
outfalls has been doubled before the percentage loss was calculated for those
plants where such a dilution occurred. Flow times between the sampling points
at each plant are indicated. Results at Contra Costa are separated for
Units 6 and 7 because of the different flow times from the COND-IN to the
outfall.
The table shows that the disappearance of TOR generally depends on the
flow time through the system. This is especially evident from the COND-IN
to the outfall because of the wide variation of flow times that existed.
Figure 8 is a graph of the percentage loss of TOR between the COND-IN and the
outfall sampling point as a function of flow time.
DECAY AND RECEIVING WATER STUDIES
Decay studies were conducted on the chlorinated cooling water collected
at the outfalls to determine the approximate life of oxidant residuals in the
receiving waters. Oxidant residuals were measured at various locations in
22
-------
30 JUN 76
S.F. BAY WATER AT SERL
pH 7.6, Cr 16.0 g/l, NH,-N 0.36mg/
CHOOSE 3.05mg/l, TEMP 21.0 °C
20
TIME, min
4.0
3.0
JM
O
e»
2.0
g
CO
ui
CE
| 1.0
x
o
0.0
7 JUL 76
pH7.7, NH3-N 0.45 mg/l
Cl DOSE 4.00 mg/l, TEMP IZO°C
KEY: A TOR (DPD-calculated)
TOR (AMPEROMETRIC)
FOR (AMPEROMETRIC)
A FREE Cl2+BROMINE (DPD)
B COMBINED CI2 (DPD)
C BROMINES (DPD)
1
10
20
TIME, min
30
40
Figure 7.
Laboratory comparison of DPD-FAS titrimetric
and amperometric titration methods.
2.3
-------
70
POTRERO P. P. - UNIT 3
CONTRA COSTA P.P. - UNIT 7
CONTRA COSTA P. R - UNIT 6
A HUNTERS POINT P. P. - UNIT 4
O MOSS LANDING P.P. - UNITS 6
2345678
FLOW TIME - COND-WTO OUT, min
Figure 8. Percentage loss of TOR between the
COND-IN and the outfall sampling point for
various oower nlants.
24
-------
TABLE 9. SUMMARY OF LOSS OF OXIDANT RESIDUAL WITHIN
THE POWER PLANT COOLING WATER SYSTEM
APROXIMATE
FLOW TIME
POWER PLANT
Contra Costa
Hunters Point
Potrero
Moss Landing
UNIT
6
7
4
3
6,7
INJ PT
TO
COND-IN
1.2
1.2
1.5
0.9
0.8
(min)
COND-IN
TO
OUTFALLt
1.5
0.9
0.9
0.4
6-7
TOTAL
2.7
2.1
2.4
1.3
7-8
TOR
(%)
INJ PT
TO
COND-IN
55-75
54-67
44-59
19-44
10-32
LOSS
COND-IN
TO
OUTFALLt
8-21
6-17
10-34
0-19
41-64
TOR
(%)*
REMAINING
AT OUTFALLt
17-24
27-31
24-40
54-78
16-27
*Percent loss does not include that caused by dilution immediately
past the condensers.
tISE at Moss Landing
the receiving waters to determine the extent of the area affected by the
power plant discharge during chlorination.
'The results of the decay studies conducted at the outfalls are presented
in Figures 9-12. The loss of oxidant residual between the point of chlorine
injection, the COND-IN, and the outfall are shown. The effect of the 1:1
dilution which occurred between the COND-IN and the outfall sampling point
is indicated by a dotted line for all plants except Hunters Point where flows
to both condensers were chlorinated simultaneously. Table 10 is a summary
of the decay studies. It should be remembered that the results are based on
field studies and that no attempt was made to keep temperature constant. In
most cases temperature increased in the "light" experiments and decreased in
the "dark" experiments.
The results of receiving water studies are presented in Figures 13-17
in the form of isoconcentration lines of TOR at the surface. Surface TOR
was always found to be the highest compared to samples taken at various
depths. Whenever possible the 0.02, 0.05, and 0.10 mg C!2/£ isoconcentration
lines are shown together with the enclosed surface areas. These areas give
an approximation of the regions affected by various levels of TOR. The re-
ceiving water studies conducted at Contra Costa, Potrero, and Hunters Point
were for a time period greater than the normal chlorination cycles at these
plants.
25
-------
1.8
1.6
V-4
o
fl.2
J 1.0
ui
K 0.6
1-
0 0.2
- 10 FEB 76
^-DOSE
:
yCOND-IN
^DILUTION .TOR (DARK)
/OUT 4 xTOR ILIGHT)
-^^* / h
'0 10 20 30 40
TIME, min
50 60
70
DOSE
16 JUN 76
:OND-IN
DILUTION TQR (DARK)
)UTtX'FOR ( /TOR (LIGHT)
Qir i r-^
1 \ \
10 20 30 40
TIME, min
50 60
70
Figure 9. Results of decay studies conducted at the
Contra Costa power plant, Units 6 and 7 outfall
26
-------
1.6
DOSE
17 MAY 76
TOR (DARK)
TOR (LIGHT)
f
I I
10
20 30 40
TIME, min
50 60 70
2.4
2.2
2.0
- 1.8
*^
CM
a i.e
Ot
6 1,4
§ 1.0
ui
(E
£ °'8
| 0.6
x
0 0.4
0.2
0.0
DOSE
26 AUG 76
COND-IN
TOR (DARK)
TOR (LIGHT)
i h
10 20 30 40
TIME, min
50
60
70
Figure 10. Results of decay studies conducted at the
Hunters Point Power Plant, Unit 4 outfall.
27
-------
I I I I
20 30 40
TIME, mln
70
I I I I
20 30 40
TIME, mln
70
Figure H- Results of decay studies conducted at the
Potrero power plant, Unit 3 outfall.
28
-------
o
o»
O
x
o
20 30 40
TIME, min
DOSE
_cvl
o
o
o
X
14 JUL 76
TOR (DARK)
TOR (LIGHT)
20 30 40
TIME, min
50 60
70
Figure 12. Results of decay studies conducted at the
Moss Landing "power plant, Units 6 and 7 at ISE,
29
-------
TABLE 10. SUMMARY OF DECAY STUDIES
TOR AFTER
DATE
10 Feb
16 Jun
17 May
CO
0 26 Aug
23 Feb
4 Mar
19 Apr
14 Jul
76
76
76
76
76
76
76
76
POWER PLANT
Contra Costa
Contra Costa
Hunters Point
Hunters Point
Potrero
Potrero
Moss Landing
Moss Landing
INITIAL
TEMP
°C
34.5
24.0
30.0
20.0
20.0
24.0
27.0
INITIAL
TOR
0.
0.
0.
0.
0.
0.
0.
0.
23
16
52
72
61
43
22
20
"DARK"
OR
"LIGHT"
EXPOSURE
Dark
Light
Dark
Light
Dark
Light
Dark
Light
Dark
Dark
Light
Dark
Light
30
mgCla/*
0.14
0.12
0.09
0.07
0.10
0.03
0.20
0.12
0.20
0.15
0.08
0.08
0.05
MIN
% OF
INITIAL
TOR
61
52
56
44
17
6
28
17
33
35
35
40
25
60
ngCW*
0.12
0.09
0.08
0.06
0.15
0.08
0.13
0.10
0.03
0.05
0.02
MIN
% OF
INITIAL
TOR
52
39
50
38
21
11
21
23
13
25
10
TIME TO REACH
0.1 mgCl2/&
min
>90
45
20
8
30
10
38
>90
60
22
16
8
-------
SAN JOAQUIN RIVER
8 JUL 76
HI WATER- 1447
LO WATER-0837
STUDY- 1025-1050
0.00
0.00
INTAKE STRUCTURE
UNITS 6 ft 7
UNITS
COND-IN
0.44
OUT
SO.16
(UNIT 6)
SCALE' I IN. = 200 FT
PLUME BOUNDARY
3 DEC 76
HI WATER- 1259
LO WATER-2033
STUDY-1550-1625
0.00 (13.2)
0.00
0.01
(23.0)
UNIT 6
COND-IN
0.50
0.02
(22.0)
0.02
(26.0)
OUT
SO.I8
(UNIT6)
0.02
(24.0)
0.02
(26.0)
0.03
(27.2)
0.02 ( 0.00
(21.0) < (13.2)
I K 0.04
0.05 (27.3)
I (27.3)
( TEMP. - °C - IN PARENTHESES)
Figure 13. TOR (mgCl2/0 at the surface of the receiving water at
the Contra Costa power plant, Units 6 and 7.
31
-------
ro
19 OCT 76
HI WATER 0959
LO WATER 1557
STUDY 1320-1410
COND-IN
~0.65
COND-IN
~0.68
0.02
126000 FT2 /
17 NOV 76
HI WATER 0811
LO WATER 1445
STUDY 1130-1210
S.F. BAY
0.05
15600 FT'
3 NOV 76
HI WATER 0941
LO WATER 1617
STUDY 1410-1500
COND-IN
~0.65
0.02
23 NOV 76
HI WATER 1228
LO WATER 1940
STUDY 1320-1350
1500 FT2
0.05
2800 FT3
SCALE' I IN. = 200 FT
Figure 14. TOR (mgCl2/£) at receiving water surface at the Hunters Point Power Plant, Unit 4.
-------
to
CONO-IN
~0.73
15 OCT 76
HI WATER 0701
LO WATER 1135
STUDY 1125-1205
UNIT 182 INTAKE
COND-IN
~0.70
17 NOV 76
HI WATER 0810
LO WATER 1442
STUDY 0945-1020
0.05
16000 FT'
S.F. BAY
COND-IN
~0.73
27 OCT 76
HI WATER 1533
LO WATER 0939
STUDY 1350-1450
OUT n»oo FT
-0.2&
19 NOV 76
HI WATER 0929
LO WATER 1621
STUDY 0930-1012
00 FT2
24900 FT'
SCALE:
= 200 FT
Figure 15. TOR (mnCl2/$,) at receiving water surface at the Potrero power plant, Unit 3.
-------
CO
15 OCT 76
HI WATER 1711
LO WATER 1135
STUDY 1400-1530
27 OCT 76
HI WATER 1533
LO WATER 0939
STUDY 1130-1200
225000 FT
S.F. BAY
COND-IN ~0.69
0.05
II5000FT2V
SCALE' I IN. = 300 FT
Figure 16. TOR (mnCl2/^) at receivinn water surface at the Potrero Power Plant, Units 1 and 2.
-------
0.00
OCEAN
WAVES
0.12
+
UNIT 6
DISCHARGE STRUCTURES
UNIT 7
0.06
+
0.09
MONTEREY
BAY
0.00
+
SCALE- I IN. » 20 FT
Figure 17. FOR (mgCl2/JO at the receiving water surface at the
Moss Landing power olant, Unit 6.
35
-------
The results at Contra Costa (Figure 13) show the effects of chlorine
addition to one condenser of Unit 6. The study of 8 July 1976 was conducted
during a flood tide so that no residual was detected downstream from the point
where the discharge canal meets the river. The study of 3 December 1976 shows
the effects of an ebb tide. A TOR of 0.02 mg Cl2/£ was detected some 150m
(500 ft) down the San Joaquin River near the intake structure for Units 6 and
7. The plume boundary was clearly visible and its presence was confirmed by
both oxidant residual measurement and temperature readings.
Results at Hunters Point due to chlorine addition to one condenser of Unit
4 are presented in Figure 14. A TOR of 0.02 mg Cl2/fc was measured up to 150m
(500 ft) from the outfall structure. The dilution effect of varying tidal
stages is evident. The studies of 19 October 1976 and 3 November 1976 were
conducted at lower tides than the other two studies. Tidal effects are very
pronounced because the discharge structure is submerged at high tides but not
at low tides.
Results at Potrero are presented in Figures 15 and 16. Figure 15 shows
the effects of chlorine addition to one condenser of Unit 3. A TOR of 0.02
mgd2/Jt was detected up to 168 m (550 ft) from the outfall structure and is
drawn into the No. 1 and 2 Unit intake. Tidal effects were not as evident as
at Hunters Point because the Potrero outfall structure is never fully submerged.
Figure 16 shows the effects of chlorine addition to all condensers of Units 1
and 2. These units are very old and chlorination of each condenser separately
is not possible. A TOR of 0.02 mgd2/5, was detected up to 400 m (1300 ft)
from the outfall structure.
A study was conducted in the receiving water at Moss Landing on 23 Sep-
tember 1976 (Figure 17). It was very difficult to keep the boat in the dis-
charge plume in Monterey Bay because of the force of 37.9 m3/sec (600,000 gpm)
of cooling water reaching the surface. It was difficult at times to determine
the exact location of the plume because of waves continually moving the boat.
A maximum TOR of 0.16 mg Cl2/£ was determined at the surface at a time when the
TOR ranged from 1.2 to 1.7 mg/£ at the COND-IN and from 0.31 to 0.33 mg/£ at
ISE.
36
-------
SECTION 4
DISCUSSION
NATURE OF THE OXIDANT RESIDUAL
The nature of the oxidant residual at each of the power plants is im-
portant for understanding the decay and persistence in the receiving waters.
None of the methods currently available for the routine measurement of oxidant
residuals unequivocally identify the compounds that make up the residual.
This is especially true for oxidant residuals in estuarine and marine waters.
When chlorine is added to seawater that is free of ami no-nitrogen, bromide
(present at a concentration of approximately 70 mg/£) is oxidized to bromine
as follows:
HOC1 + Br" = HOBr + Cl"
Figure 18 shows the time required (based on reported rate constants) to
convert 99% of the chlorine to bromine at a temperature of 25°C and a pH of
8.3 for varying percentages of seawater (15). The reaction proceeds to 99%
completion within 10 sec in highly saline water, but very little bromine is
formed in water containing less than 3% seawater. A similar oxidation of
iodine occurs. Total oxidation of the iodide in seawater to iodine would
account for a TOR of 0.035 mg/8, as chlorine.
When ammonia-nitrogen is present in seawater, there is a competition
between the ammonia and the bromide ion for chlorine. A number of reactions
are possible, depending on pH, chlorine dose, concentration of NH3-N, salinity,
and reaction time. The formation of chloramines is generally favored by high
NH3-N, low salinity, high pH, and low chlorine dosage.
Using an equilibrium model, Sugam and Helz (16) suggest that free bromine
and bromamines predominate over the chlorine species at salinities above
approximately 0.3 g/& with ammonia concentrations "typical" of estuarine and
marine waters. The predominant species in seawater containing 0.08 mg NH3-N/£
dosed at 1.0 mgd2/£ at pH 8.1 were tribromamine (NBr3) and dibromamine
(NHBr2). Equal amounts of monochloramine (NH2C1) and HOBr were estimated to
exist in a typical seawater of 35 g/£ salinity at pH 8 containing 0.12 mg/H
NH2-N dosed at 0.5 mgd2/£. The model for 0.3 g/£ salinity is very complicated
showing both chlorine and bromine compounds with no species in abundance be-
tween pH 6 and 8.
Sollo £t al_. (17) performed studies on the resulting speciation when
solutions containing both ammonia and bromide were dosed with chlorine and the
37
-------
1000
2.0 Cl 2 DOSE, mg/l
10
10 20
% SEA WATER
40 50
KDO
Figure 18. Time required for 99% conversion of free chlorine
to HOBr at 25°C and a pH of 8.3
38
-------
residuals were determined after 2 nrin. Solutions containing 0.41 mg/£ NH3-N
and bromide concentrations of 3 and 25 mg/£ dosed at 2 mgCl2/£ are interesting
because they most closely model the conditions existing in the cooling waters
studied in this investigation. Very little free bromine existed over the
entire pH range tested (4.3 to 9.0). At pH 7.4 and 25 mg/£ Br~ a total
halogen concentration of 2.8 mg Br2/£ was detected which was significantly
lower than the 4.5 mg Br2/& expected. The entire residual was determined to
be combined bromine and was believed to be NHBr2 whose instability might ex-
plain the lower than expected total halogen residual. At pH 7.4 and 3 mg/£
Br~ the entire 4.5 mg Br2/A total halogen residual was determined to be chlorine
residual.
Figure 19 after Johnson and Overby (18) shows the bromine species postu-
lated to be present after 1 to 2 min as a function of both pH and the loga-
rithm of the initial mole ratio of ammonia to bromine. These data suggest
that HOBr and NBr3 would predominate after 1 to 2 min under conditions that
exist at the Hunters Point, Potrero, and Moss Landing Power Plants if a total
conversion of chlorine to bromine is assumed. NHBr2 would be predominant at
somewhat higher ammonia concentrations than were measured at the power plants.
At Contra Costa both chlorine and bromine compounds are suggested with pre-
diction of individual species being difficult. It is apparent that both
chlorine and bromine residuals generally exist when chlorine is added to
estuarine and marine waters. Both the amperometric and DPD-FAS methods were
used to determine oxidant residuals. The amperometric titration method for
total residual determines all oxidant residuals whether they be chlorine,
bromine, or iodine. It is apparent from Figure 11 that the amperometric free
residual determination measures both free chlorine and bromine residual.
Since the DPD-FAS method does not distinguish between free and combined bro-
mine residual, it is possible that some combined bromine existed and was picked
up by the amperometric method as "free residual." This has been suggested by
Johannesson (19), Palin (11), and Sugam and Helz (16). Therefore, the so-
called "free chlorine" residual measured by the standard amperometric method
in estuarine or marine water is neither totally "chlorine" nor totally "free."
CHLORINATION PRACTICES
Chlorine dosage at many of the power plants was decreased during the
course of this study. This was done both as a reaction to an awareness of
greater than expected residuals and to decrease the residual in the dis-
charge stream. Those plants using the OT method to set the chlorine dose were
often chlorinating at twice the desired level because of the inaccuracies of
the analytical method.
Total chlorine use per day for the four power plants located on.the San
Francisco Bay System averages about 0.30 metric tons/day (0.33 tons/day)
based on 1971 figures (20). This represents 1.25% of the total average daily
use of chlorine of 34 metric tons/day (37.5 tons/day) for the 1975-76 season
as estimated by Russell and Home (21) for the waste treatment plants dis-
charging to San Francisco Bay.
39
-------
-2
Q.
CO
d5
O
X
o
5
-P.
o
t-i
u.
o
x
H
IT
HOBr
OBr'
IMHBn
NH2Br
6
PH
8
10
Figure 19. Principal species of bromine and bromamine
after 1-2 min at various pH and amnonia to bromine ratios.
Lines represent equal equivalent concentrations. Hypobromous
acid separation from bromine given for 10-5 V± bromide.
(After Johnson and Overby 18).
-------
DEMANDS IN COOLING WATER SYSTEM
Table 9 and Figure 8 indicate that the loss of oxidant residual in the
cooling water system was a function of flow time. The longer the cooling
water was held within the plant, the lower was the oxidant residual that
reached the receiving water. This loss of residual was due to many factors
including reaction with ammonia-nitrogen, demand by inorganic reducing agents,
reaction with organic nitrogen, and uptake by organisms living in the cooling
water system. It is difficult to say which of these are the most important.
Table 9 and Figure 8 suggests the flow time through the cooling water system
may be a good method to estimate the oxidant residual to be expected at various
locations from varying doses of chlorine.
DECAY AND RECEIVING WATER STUDIES
The decay studies (Figures 9-12, Table 10) show that the most persistent
residual occurred at the Contra Costa Power Plant. From 50% to 52% of the
0.16 and 0.23 mg/H TOR determined at the outfall remained after 60 min in
those samples covered to exclude sunlight. From 38% to 39% of the 0.16 and
0.23 mg/£ TOR lasted for the same time period in samples exposed to sunlight.
This persistence is likely explained by a slowly decaying combined chlorine
residual that occurred at Contra Costa.
The highest concentrations of TOR remaining after 30 and 60 min were at
Hunters Point and Potrero. However, this was due mostly to the greater
initial concentrations of 0.43-0.72 mg/£ TOR. The lowest concentrations of
TOR in decay studies were found at Moss Landing where the long flow time to
the outfall sample point produced small initial TOR's of 0.22 and 0.20 mg
Cl2/£. These were approximately the same initial TOR's which existed at the
Contra Costa outfall, however the oxidant residual at Moss Landing decayed to
much lower values. After 60 min at Moss Landing from 0.02 to 0.05 mgCl2/&
remained while at Contra Costa from 0.06 to 0.12 mg/fi, remained. The major dif-
ference between the oxidant residuals is the predominance of bromine residuals
at Moss Landing which decay more rapidly than chlorine residuals (17,18,19).
The presence of sunlight appeared to speed up the rate of decay at all
plants. This effect was most noticeable during the initial 20 min of decay
at Contra Costa on 16 June 1976 when a FOR existed. After 20 min only
combined residual existed and the effect of sunlight on decay became less
pronounced. The significance of the oxidant residuals can be assessed in
two ways. The first approach is to consider the effect on an organism such as
a fish that is located at the discharge initially and then swims with a parcel
of water away from the plume. The second method is to consider the effect
on an organism that remains in one spot and is subjected to intermittent
doses of chlorine. Such a case would be representative of benthic organisms
located in the sediments overlain by the discharge.
The first approach has been addressed by Mattice and Zittel (3). Table
11 is derived from their data and shows several dose-exposure time combinations
that result in acute toxicity; the chronic toxicity threshold is also indicated
for marine and freshwater organisms. At Contra Costa the cooling water
41
-------
discharge is into a canal that has an approximate residence time of 12 min. In
the canal average TOR concentrations were on the order of 0.05 mgCl2/fc.
According to Mattice and Zittel, this combination of chlorine dose and ex-
posure time would not result in acute toxicity to freshwater organisms. It
is very close to Mattice and Zittel's acutely toxic level for marine organisms.
A TOR of 0.02 mgCla/i was detected for a distance of some 150 m (500 ft) down
the San Joaquin River. Assuming an average water velocity of 0.55 m/sec (1.8
ft/sec) this results in an exposure time of 4.6 min at this TOR concentration.
This TOR level is at Mattice and Zittel's chronic toxicity level for marine
organisms. For freshwater organisms the dose/exposure time stated to be
acutely toxic to freshwater organisms by Mattice and Zittel is 0.02 rng/A for
200 min.
TABLE 11. ACUTE AND CHRONIC DOSES OF CHLORINE TO MARINE AND
FRESHWATER ORGANISMS (Mattice and Zittel} (3)
MARINE ORGANISMS
FRESHWATER ORGANISMS
TOR
mgC!2/£
0.20
0.15
0.10
0.05
0.02*
DURATION
min
0.50
1.0
2.5
13
TOR
0.10
0.05
0.02
0.01
0.0015*
DURATION
min
25
60
200
550
--
*Chrom"c toxicity threshold.
Current velocities in the discharge plumes have been determined by PG&E
at the Hunters Point and Potrero Plants. At Hunters Point the time to reach
the 0.02 mg/£ TOR isoconcentration line is 45 sec. Assuming that the velo-
city is constant between the outfall and the 0.02 mg/£ TOR isoconcentration
line, the estimated time to reach 0.05 mgA TOR is between 11-28 sec; with the
same assumption, the time to reach the 0.10 mg/£ TOR isoconcentration line is
7 sec. These dose/exposure times are far below the values quoted by Mattice
and Zittel to be acutely toxic to both freshwater and marine organisms. Con-
centrations of TOR exist in the receiving water that are above the chronic
toxicity threshold for both freshwater and marine organisms.
At Potrero, with an average discharge concentration of 0.3 mg/fc TOR, the
time to the 0.02 mg/A TOR isoconcentration line is approximately 3 min. Using
the same assumptions as for Hunters Point, the time to the 0.1 rng/A TOR iso-
concentration line is estimated to be between 48-56 sec; from the 0.1
42
-------
TOR to the 0.05 mg/Z TOR isoconcentration line is between 20-65 sec. The
exposure between the 0.3 mg/£ TOR discharge and the 0.1 mg/Jl TOR isoconcentra-
tion line (assumed to be an average of 0.2 mg/£ TOR) is predicted to be acutely
toxic to marine organisms. Acute toxicity is not predicted according to the
Mattice and Zittel data beyond this area. Chronic toxicity to marine organisms
is predicted to exist out to the 0.02 mg/£ isoconcentration line and consider-
ably further for freshwater organisms.
The 0.16 mgCl2/£ maximum concentration measured at the surface of Monterey
Bay at the outfall from the No. 6 and 7 Units at Moss Landing could only have
existed for a flow time of a few seconds from the discharge pipes located at a
depth of 6.1 m (20 ft). At a distance of some 15.3 m (50 ft) from the dis-
charge, a residual of 0.09 mgC!2/£ was detected. For this residual to be
acutely toxic by Mattice and Zittel's criterion, an exposure time of some 2.5
min must exist. It is questionable whether such a contact time existed between
the discharge structure and a point some 50 ft away on the surface. These
chlorine levels are above those suggested by Mattice and Zittel as chronic
toxicity threshold values for both freshwater and marine organisms.
The second approach has been investigated by Dickson ejt aJL (22) who
studied the effects of intermittent chlorination on goldfish and on proto-
zoans obtained from attached growths. LC-50 values for goldfish were found
to be a function of total exposure time during a 24-hr period. In the tempera-
ture range of 17-22.5°C, 2-hr exposure/day resulted in an LC-50 of 1.18 mg/£
TOR; with 3-hr exposure the LC-50 was 0.71 mg/£ TOR and with 4-hr/day exposure
the LC-50 fell to 0.63 mg/£ TOR. These authors concluded that 2-3 exposures
of 15-30 min/day at a TOR of 0.5-0.75 mg/2, would not result in lethality to the
goldfish. Concentrations in the ranges stated above were never detected in
the receiving waters at any location sampled during this study. Indeed, only
in early studies at Hunters Point and Potrero, before the reduction in chlorine
dosage by PG&E took place, were such levels detected in the outfalls. It
might, therefore, be concluded that with current chlorination practice no
lethality would result from chlorine toxicity in cooling water to fish with the
same response as goldfish.
43
-------
SECTION 5
CONCLUSIONS
CHLORINATION PRACTICE
1. Chlorination frequency varied among the five power plants studied from
I/week to 4/day. Duration of chlorination varied from 15 to 40 min per
cycle.
2. Oxidant residual determined at the condenser inlets was the criterion
used by the power plants to determine the level of chlorine dose.
3. During this study the chlorine dose to produce the desired residual of
approximately 0.5 mgCl2/£ at the condenser inlets was reduced. This re-
duction resulted from a more precise measurement of chlorine residuals
throughout the cooling system that was afforded by the amperometric method
used by us as compared to the OT method routinely used by power plant
personnel.
4. All of the plants are currently using or are in the process of obtaining
amperometric titrators due to more stringent regulations that require
accurate measurement of oxidant residuals.
IN-PLANT STUDIES
5. Total chlorine usage per day for the four power plants located on San
Francisco Bay averaged about 0.3 metric tons/day (0.33 tons/day) based on
1971 figures. This represented 1.25% of the total average daily use of 34
metric tons/day (37.5 tons/day) estimated for 1975-76 for waste discharges
entering San Francisco Bay.
6. Oxidant residuals determined at the condenser inlets were often signifi-
cantly higher than the 0.5 or 1.0 mg/£ desired by plant personnel, es-
pecially at those plants using the OT method for control of chlorine
residual.
7. At Contra Costa, where the cooling water was the freshest, a combined
residual of from 0.10 to 0.40 mgCl2/£ existed from the condenser inlet to
the outfall.
8. At Hunters Point, Potrero, and Moss Landing, where cooling water ranged
from 79% to 99% seawater, total oxidant residual generally equalled
free oxidant residual at the condenser inlets. Some combined residual
44
-------
was detected at the outfall of Hunters Point and at a sample point 6-7
min of flow time from the condenser inlet at Moss Landing.
9. The DPD-FAS results indicated that most of the oxidant residual at Hunters
Point and Moss Landing was bromine residual.
10. The disappearance of total oxidant residual through the cooling water system
generally depended on the flow time. At Moss Landing where the total flow
time in the system was 6 to 7 min, from 16% to 27% of the oxidant input
remained at the outfall. At Potrero where the total flow time in the system
was only 1.3 min, from 54% to 78% of the oxidant input remained at the
outfall.
DECAY AND RECEIVING WATER STUDIES
11. The slowest decay at the outfall was observed at Contra Costa where 50%
to 52% of the total oxidant residual of 0.18-0.23 mg/a measured at the
outfall remained after 60 min in the samples covered to exclude sunlight.
For the samples exposed to sunlight, 38% to 39% remained after the same
time period.
12. The most rapid decay at the outfall was observed at Hunters Point where
17% to 28% of the total oxidant residual of 0.52-0.72 mg/2, measured at the
outfall remained after 30 min in the samples covered to exclude sunlight.
For the samples exposed to sunlight, only 6% to 17% remained after the same
time period.
13. Maximum total oxidant residuals were found to exist at the surface of re-
ceiving waters likely because of the natural buoyancy of the warmer ef-
fluent.
14. During the chlorination cycle at Contra Costa, an 0.02 mgC!2/£ residual
was measured some 150 m(500 ft) from the point where the discharge canal
meets the San Joaquin River.
15. During the chlorination cycle at Hunters Point, 0.02 mgClzA residual
was measured up to 150 m (500 ft) from the No. 4 outfall and up to 168 m
(550 ft) away from the No. 3 outfall at Potrero, and up to 400 m (1300 ft)
from the No. 1 and No. 2 outfall at Potrero.
16. A maximum residual of 0.16 mgCla/^ was measured at the surface of Monterey
Bay above the outfall from the No. 6 and No. 7 Units at Moss Landing.
17. Using the approach of Mattice and Zittel, it was determined that all ef-
fluents produced receiving water oxidant residual levels that would be
predicted to demonstrate chronic toxicity to marine organisms; the re-
ceiving water from two plants (Hunters Point and Moss Landing) showed
levels that would be predicted to demonstrate chronic toxicity to fresh-
water organisms. Acutely toxic levels to freshwater and marine organisms
existed in the receiving waters at the Potrero site.
45
-------
REFERENCES
1. Brungs/W. A. Effects of residual chlorine on aquatic life. J. Water
Poll. Control Fed., 45:2180-2193, Oct 1973.
2. Basch, R. E. and J. G. Truchan. Toxicity of Chlorinated Power Plant
Condenser Cooling Waters to Fish. Environmental Protection Agency, Duluth,
Minnesota. Publication Number 600/3-76-009., Apr 1976. 105 p.
3. Mattice, J. S. and H. E. Zittel. Site-specific evaluation of power plant
chlorination. J. Water Poll Cont Fed., 48:2284-2308, Oct. 1976.
4. Federal Register, Vol. 39, No. 196, Oct. 8, 1974.
5. California Regional Water Quality Control Board, Central Coast Region,
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Landing Fossil Fuel Power Plant, Units 1-7, Monterey County, Order No.
76-09, NPDES No. CA0006254, San Luis Obispo, California, 1976.
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CA0005657, Oakland, California, 1976.
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Amperometric Method. Environmenta Protection Agency, Corvallis, Oregon.
Publication iiumoer 660/2-73-039, Aug. 1974. 45 p.
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10. Palin, A. T. The determination of free and combined chlorine in water by
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873-880, Jul 1957.
11. Palin, A. T. The determination of free residual bromine in water. Water
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12. Palin, A. T. Current DPD methods for residual halogen compounds and ozone
in water. J. Amer Water Works Assoc., 67:32-33, Jan. 1975.
46
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13. Solorzano, L. Determination of ammonia in natural waters by the phenol-
hypochlorite method, Limnol. and Oceanog., 14(5):799-801, Sep. 1969.
14. Zadorojny, C., S. Saxton, and R. Finger. Spectrophotometric determination
of ammonia, 0. Water Poll. Control Fed., 45:905-912, May 1973.
15. Selleck, R. E., A. D. K. Laird, and H. H. Sephton. Optimization of
Chlorine Application Procedures and Evaluation of Chlorine Monitoring
Techniques. University of California. (Proposal to Electric Power
Research, Inc., Palo Alto, Mar. 25, 1976). Publication Number UCB-Eng-
4180, 80 p.
16. Sugam, R. and G. R. Helz. Speciation of Chlorine Produced Oxidants in
Marine Waters. University of Maryland. (Presented at Workshop on the
Fate and Effects of Chlorine on the Marine and Estuarine Environment.
Solomons, Maryland, Mar. 16-18, 1976).
17. Sollo, F. W., T. E. Larson, and F. F. McGurk. Colorimetric Methods for
Bromine, Env. Sci. and Tech., 5;240-246, Mar. 1971.
18. Johnson, J. D. and R. Overby. Bromine and Bromamine Chemistry, J. San. Eng.
Div., Proc. Amer. Soc. Civil Engrs. SA5:617-628, Oct. 1971.
19. Johannesson, J. K. The Bromination of Swimming Pools, Am. J. Public
Health, 50:1731-1736, Nov. 1960.
20. Pacific Gas and Electric Company. An Evaluation of the Effect of Cooling
Water Discharges on the Beneficial Uses of Receiving Waters at: Contra
Costa Power Plant, Pittsburg Power Plant, Hunters Point Power Plant, and
Potrero Power Plant, San Francisco, California, Jul 1973.
21. Russell, P. P. and A. J. Home. The Relationship of Wastewater Chlorina-
tion Activity to Dungeness Crab Landings in the San Francisco Bay Area.
Sanitary Engineering Research Laboratory, Berkeley, California. UCB/SERL
Report No. 77-1, Jan. 1977. 37 p.
22. Dickson, K. L., J. Cairons, Jr., B. C. Gregg, D. I. Messenger, J. L.
Plafkin, and W. H. Van der Schalie. Effects of intermittent chlorination
on aquatic organisms and communities, J. Water Poll. Control Fed., 49:35-
44, Jan. 1977.
47
-------
APPENDIX I
FIELD DATA
-------
1.4
1.2
I.O
_e\j
6
01
£
,0.8
o
H- 0.6
X
o
0.4
0.2
O.O
T
CHLORINE INJECTION RATE: 1400-I6OO lbs/24 hrs
CHLORINE DOSE (CALCULATED): 1.6 mg/1
KEY: COND-IN OUT
O TOR (AMPEROMETRIC)
a FOR t AMPEROMETRIC)
TOR AT COND-IN
* TWO TIMES MEASURED VALUES
I 1 1 I
I I
J I
O93O O934 O938 0942 0946 095O 0954 O958 1002 IO06 IOIO 1014
TIME
Figure 20. In-plant Study at the Contra Costa Power Plant
20 Jan 1976, Unit 6, Condenser #11.
49
-------
1.4
1.2
I.O
M
0
o>
O.8
O
CO
0.6
X
o
O.4
0.2
o.oi
i i i i i i i i r
CHLORINE INJECTION RATE: I4OO-I6OO lbs/24 hrs
CHLORINE DOSE (CALCULATED): 1.6 mg/I
KEY: COND-IN OUT
O
TOR lAMPEROMETRIC)
TOR AT COND-IN
/- i \JT\ H i v,\srauin
£-- -
TOR AT OUT
* TWO TIMES MEASURED VALUES
I |_ I I I I
I i
j I
1024 IO28 IO32 IO36 IO4O IO44 IO48 IO52 1056 IIOO 1104 1108
TIME
Figure 21. In-plant Study at the Contra Costa Power Plant
10 Feb 1976, Unit 7, Condenser #14.
50
-------
1.4
1.2
I.O
_CM
O
0.8
to
UJ
cc
0.6
X
o
0.4
0.2
O.Q
I I I I I I I I
CHLORINE INJECTION RATE: 1600-1100 lbs/24hrs
CHLORINE DOSE (CALCULATED): 1.7-1.2 mg/l
KEY: COND-IN OUT
O TOR (AMPEROMETRIC)
O FOR (AMPEROMETRIC)
1 T
-TOR AT COND-IN
* TWO TIMES MEASURED VALUES
I I I I I
I I
I
I I
I
1010 1014 1018 1022 1026 1030 1034 1038 1042 (046 1050 1054
TIME
Figure 22. In-plant study at the Contra Costa Power Plant
6 Jun 1976, Unit 7, condenser #13
51
-------
1.4
1 1 1 1 1 1 1 1
CHLORINE INJECTION RATE' IIOO-I2OO lbs/24h«-
CHLORINE DOSE (CALCULATED); 1.3 mg/l
1.0
o
0.8
o
§
o:
z
<
o
X
o
0.6
0.4
0.2
0.0
.
KEY= COND-IN
A
B
C
OUT
O
a
b
c
TOR lAMPCROMETRC)
FOR IAMPEROMETRIC)
FREE CL2 + BROMINES W>PD)
COMBINED CL2 (DPD)
BROMINES (DPD)
TWO TIMES MEASURED VALUES
TOR AT CONO-IN
FOR AT COND-IN
1036 IO4O IO44 1046 IO52 1056 IIOO 1104 1108 III2 1116 1120
TIME
Figure 23. In-plant Study at the Contra Costa Power Plant
14 Sept 1976, Unit 6, Condenser #11.
52
-------
1.6
1.4
1.2
I.O
_CM
O
o»
E
O.8
o
to
U)
QC
I-
1
X
o
0.6
O.4
O.2
0.0
I i i I I I i
CHLORINE INJECTION RATE: IOOO lbs/24hrs
CHLORINE DOSE (CALCULATED): 1.6 mg/l
KEY: COND-IN OUT
O
TOR (AMPEROMETRIC)
TOR AT COND-IN
1102 1106 1110 1114
1118 1122
TIME
1126 1130 1134 1138 1142
Figure 24. In-plant Study at the Hunters Point
Power Plant,16 Dec 1975, Unit 4.
53
-------
1.6
1.4
1.2
1.0
0.8
1
55
o
x
o
0.6
0.4
0.2
0.0
III|IIT^
CHLORINE INJECTION RATE: IOOO lbs/24hrs
CHLORINE DOSE (CALCULATED): 1.6 mg/l
KEY:
COND-IN OUT
O
D
TOR (AMPEROMETRIC)
FOR (AMPEROMETRIC)
TOR a FOR AT COND-IN
I04O 1044 IO48 1052 1056 IIOO 1104 HOB 1112 1116 1120
TIME
Figure 25. In-plant Study at the Hunters Point Power Plant
17 May 1976, Unit 4.
54
-------
1.6
1.4
1.2
- 1.0
s.
6
o»
6
-!0.8
CO
Ul
cr
0.6
X
o
0.4
0.2
0.0
, n
T
T
T
T
T
T
T
CHLORINE INJECTION RAiE = 1500 lbs/24hrs
CHLORINE DOSE (CALCULATED): 2.5 mg/l
KEY: COND-IN
A
B
C
OUT
O
D
Q
b
c
TOR (AMPEROMETRIC)
FOR (AMPEROMETRIC)
FREE CL2+ BROMINES (DPD)
COMBINED CL2 (DPD)
BROMINES IDPD)
1040 1044 1048 1052 1056 1100 1104
TIME
1106 1112 1116 H20
Figure 26. In-plant study at the Hunters Point Power
Plant, 26 August 1976, Unit 4
55
-------
1.6
1.4
1.2
1.0
CM
O
0.8
U
o:
X
o
O.6
O.4
0.2
0.0
1 I I
CHLORINE INJECTION RATE: 1750 lb«/24hr*
CHLORINE DOSE (CALCULATED): 2.O mcj/l
KEY: COND-IN OUT
O TOR (AMPEROMETRIC)
TWO TIMES MEASURED VALUES
I I I i i
I I
2100 2104 2IO8 2112 2116 2I2O 2124 2128 2132 2136 2I4O 2144
TIME
Figure 27. In-plant Study at the Potrero Power Plant
23 Feb 1976, Unit 3, N. Condenser.
56
-------
1.6
1.4
1.2
1.0
_(M
O
0>
0.8
o
UJ
(C
5 0.6
x
o
0.4
0.2
0.0
I
I
T
T
CHLORINE INJECTION RATE: 1400 lbs/24hrs
CHLORINE DOSE (CALCULATED): 1.6 mg/l
KEY: COND-IN OUT
O
TOR (AMPEROMETRIC)
TOR AT COND-IN
TWO TIMES MEASURED VALUES
I I I I 1
0900 0904 0908 0912 0916 0920 0924 0928 0932 0936 0940 0944
TIME (PM)
Figure 28. In-plant study at the Potrero Power Plant, 4
March 1976, Unit 3, N. Condenser
57
-------
I I
CHLORINE INJECTION RATE: 4OOO lbs/24 hrs
CHLORINE DOSE (CALCULATED): 2.2 mg/I
KEY: COND-1N
TOR (AMPEROMETRIC)
CONDENSER
7-2
CONDENSER
7-1
TOR AT ISE*
I24O 1245 1250 1255 I3OO I3O5 1310 1315 I32O 1325 I33O 1335 I34O
TIME
* TWO TIMES MEASURED VALUES
Figure 29. In-plant Study at the Moss Landing Power Plant
12 April 1976, Unit 7.
58
-------
2.2
2.0
1.8
1.6
_CM
U
a>
E 1.2
UJ
(C
1 Ofl
0.6
0.4
0.2
0.0
~~i iiiiiTr
CHLORINE INJECTION RATE: 4000lbs/24hrs
CHLORINE DOSE (CALCULATED): 2.2 mg/l
KEY
CONDHN ISE
O TOR (AMPEROMETRIC)
T 1 T
A
1255 1300 1305 1310 1315 1320 1325 1330 1335 1340 1345 1360 1355
TIME
* TWO TIMES MEASURED VALUES
Figure 30. In-plant study at the Moss Landing Power
Riant,19 April 1976, Unit 7
59
-------
I I i j I I I I f T
CHLORINE INJECTION RATE: 38OO Ibs/24 hrs
CHLORINE DOSE (CALCULATED): 2.1 mg/l
KEY:
CONO-IN
ISE
O TOR (AMP.)
FOR (AMP.)
TOR AT
COND-IN
O.O
1305 1310 1315 I32O 1325 1330 1335 I34O 1345 1350 1355 1400
TIME
TWO TIMES MEASURED VALUES
Figure 31. In-plant Study at the Moss Landing Power Plant
14 July 1976, Unit 6.
60
-------
2.2
2.0
1.8
1.6
1.4
O
o»
o
I/)
O O.8
§
O.6
O.4
O.2-
O.CH
T 1 1 1 1 1
COND-IN
-A 'A,
1 r
-CONDENSER 7-1
KEY: COND-IN
TOR I
CONDENSER 7-2
CHLORINE INJECTION RATE' 38OO lbs/24hrs
- CHLORINE DOSE ICALCULATED): 2.lmg/l
RIC)
| FOR flAMPERON ETRIC)
A FREE CL2+8 HOMINES IDPD)
B COMBINED CLg (DPD)
C BROMINES (DPJD)
i j m i J
1400 1405 1410 1415 1420 1423 1430 1435 44O t445 I45O 1455
TIME
Figure 32. In-plant Study at the Moss Landing Power Plant
14 July 1976, Unit 7.
61
-------
2.2
2.0
1.8
1.6
1.4
CM
O
6 1.2
a
X
o
0.8-
06-
0.4-
02
QO
CHLC RINE INJECTION RATE; 38OO lbi/24 hrs
RINE DOSE (CALCULATED): 2.1 mg/l
KEY
J_
COND-IN
CONDENSER 6-1
COND-IN
A
B
C
TOR
FOR
FREE
COM!
(AMPEROMEFRIC)
(AMPEROME
BR<3
INED CL,
BROMINES (DPI
D ' D ' D
rmc)
MINES (DPD)
1
I30O I3O5 1310 1315 I32O 1325 I33O 1336 I34O 1345 I35O 1356
TIME
Figure 33. In-plant Study at the Moss Landing Power Plant
22 July 1976, Unit 6.
62
-------
~~li I 1 1 1 1 1 r
CHLORINE INJECTION RATE= 23OO tbs/24hrs
CHLORINE DOSE (CALCULATED): 1.3 mg/l
1 - 1
ISE
O
D
Q
b
c
TOR (AMPEROMETRIC)
FOR (AMPEROMETRIC)
FREE CL2+ BROMINES (DPD)
COMBINED O_2 (DPD)
BROMINES (DPD)
x
O
_c»
O
e 1.2 -
g
O.8 -
0.6 -
0.4 -
0.2 -
O.O
I40O 1405 1410 1415 1420 1425 I43O 1435 1440 1445 I45O 1455
TIME
> TWO TIMES MEASURED VALUES
Figure 34. In-plant Study at the Moss Landing Power Plant
5 August 1976, Unit 7.
63
-------
2.2
2.0
1.8
1.6
\ 1.4
_CM
O
1.2
IS i.o
O OB
x
O
O.6
O.4-
O.2
0.0
CHLORINE INJECTION RATE: 38OO lbs/24 N"S
CHLORINE DOSE (CALCULATED): 2.1 mg/l
KEY: COND-IN BE
O TOR (AMPEROMETRIC)
FOR lAMPEROMETRlC)
! I
1255 1300 1305 1310 1315 I32O 1325 I33O 1335 I34O 1345 I35O
TIME
TWO TIMES MEASURED VALUES
Figure 35. In-plant Study at the Moss Landing Power Plant
23 Sept 1976, Unit 6.
64
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
REPORT NO.
EPA-600/3-78-032
2.
4. TITLE AND SUBTITLE
"Power Plant Cooling Water Chlorination in
Northern California."
3. RECIPIENT'S ACCESSIOt^NO.
5. REPORT DATE
March 1978
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
S. Hergott, David Jenkins, and Jerome F. Thomas
UCB/SERL No. 77-3
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Sanitary Engineering Research Laboratory
College of Engineering & School of Public Health
University of California
Berkeley, CA 94720
10. PROGRAM ELEMENT NO.
1BA608
11. CONTRACT/GRANT NO.
R-803959
12. SPONSORING AGENCY NAME AND ADDRESS
U.S. Environmental Protection Agency
Corvallis Environmental Research Laboratory
200 S.W. 35th Street
Con/all is, OR 97330
13. TYPE OF REPORT AND PERIOD COVERED
extramural 11/75 to 12/76
14. SPONSORING AGENCY CODE
EPA/600/02
15. SUPPLEMENTARY NOTES
16. ABSTRACT
A survey was conducted of chlorination practices at five power plants owned and
operated by the Pacific Gas and Electric Company. Frequency and duration of chlori-
nation varied significantly from plant to plant and was controlled analytically by
the orthotolidine and/or amperometric methods. All the plants plan to change to
using the amperometric method for future control purposes.
In-plant studies were conducted during chlorination cycles to determine oxidant resid-
uals at both the condenser inlets and at a point near the outfall. Both free and
total oxidant residuals were measured amperometrically for most studies. The DPD-FAS
method was included in later studies to gain a better understanding of the nature of
the oxidant residual. These results indicated that most of the oxidant residual at
the Hunters Point and Moss Landing power plants was bromine residual.
Decay studies were conducted at the plant sites on the chlorinated cooling water col-
lected at the outfall. The slowest decay was observed at the Contra Costa plant
where the cooling water was the freshest. The most rapid decay was at the Hunters
Point plant. The presence of sunlight increased the rate of decay at all locations.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
chlorination
industrial wastes effluents
electrical measurements
oxidizers
coastal waters
cooling water effluents
San Francisco Bay
decay studies
Field 13
Group 13B
18. DISTRIBUTION STATEMENT
Release to oublic
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
78
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
a U.S. GOVERNMENT PRINTING OFCICE: 1978-796-325/100 REGldN 10
65
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