Environmental Evaluation of
Wastewater Disinfection Practices
in Northern New England:
Assessment and Mitigation
prepared for:
U.S. Environmental Protection Agency Region I
Environmental Evaluation Section
Under Contract No. 68-04-1009
November, 1983
vvEPA
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Q o yo{&
Environmental Evaluation of
Wastewater Disinfection Practices
in Northern New England;
Assessment and Mitigation
11 c fpa 1IRRARY REGION 10 MATERIALS
iiiiiiiiii
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TABLE OP CONTENTS
Page
LIST OF TABLES iv
LIST OF FIGURES vi
ACKNOWLEDGEMENTS v i i i
DISCLAIMER X
REPORT
CHAPTER 1 - INTRODUCTION 1-1
Literature Cited 1-6
CHAPTER 2 - COLDWATER FISHERIES HAZARD
ANALYSIS PROCEDURE (CHAP) 2-1
How to Use CHAP 2-2
Initial Determinations 2-3
Self-Sustaining Salmonids 2-4
Put-and-Take Trout Fishery 2-11
Salmonid Passage 2-12
Key Decisions 2-16
Summary 2-20
Literature Cited 2-21
CHAPTER 3 - IMPACT OF CHLORINATED EFFLUENT ON
TROUT FISHERIES OF THE DOG RIVER,
NORTHFIELDf VERMONT - A CASE STUDY 3-1
Materials and Methods 3-3
Results 3-9
Discussion 3-19
Literature Cited 3—31
CHAPTER 4 - IMPACT OF CHLORINATED EFFLUENT ON TROUT
FISHERIES OF THE THIRD BRANCH OF THE WHITE
RIVER, RANDOLPH, VERMONT - A CASE STUDY 4-1
Materials and Methods 4-3
Results 4-15
Discussion 4-39
Literature Cited 4-49
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TABLE OF CONTENTS (Continued)
Page
CHAPTER 5 - DESCRIPTION OF EXISTING DISINFECTION
SYSTEMS 5-1
Background 5-1
Methodology 5-3
Existing Conditions 5-4
Summary 5-23
Literature Cited 5-24
CHAPTER 6 - RECOMMENDED PRACTICES FOR MINIMIZING
EXCESSIVE CHLORINE USE 6-1
Regulatory Policies 6-1
Immediate Operational Improvements 6-4
Minor Modification Improvments 6-9
Major Modification Improvements 6-11
Criteria for Design/Future Expansion 6-14
Summary 6-24
Literature Cited 6-26
CHAPTER 7 - CONCLUSIONS AND RECOMMENDATIONS 7-1
Coldwater Fisheries Hazard Analysis 7-1
Procedure (CHAP)
Northfield Case Study 7-2
Randolph Case Study 7-2
Existing Disinfection Systems 7-4
Recommended Practices for Minimizing 7-5
Excessive Chlorine Use
Implementation 7-5
APPENDICES
APPENDIX A - DIAGRAMMATIC HABITAT MAP OF FISH
SAMPLING SECTIONS IN THE DOG RIVER
NEAR THE NORTHFIELD VT, WATER
POLLUTION CONTROL PLANT (WPCP)
APPENDIX B - LETTER QUESTIONNAIRE ON DISINFECTION
SYSTEMS MAILED TO TREATMENT PLANT
OPERATORS IN MAINE, NEW HAMPSHIRE AND
VERMONT
APPENDIX C - SUGGESTED TEXT OF BROCHURE DESCRIBING METHODS TO
MINIMIZE EXCESSIVE CHLORINE USE
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TABLE OF CONTENTS (Continued)
Page
APPENDIX D - MACROBENTHIC DATA FROM THE RANDOLPH,
VERMONT CASE STUDY
APPENDIX E - WRITTEN COMMENTS RECEIVED ON DRAFT
REPORT
iii
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LIST OF TABLES
Table Page
1-1 In-stream Water Quality Criteria for
Total Residual Chlorine (TRC) 1-2
3-1 Summary of Available Background Data
for the Northfield, Vermont Case Study 3-2
3-2 Water Quality Sampling Stations on the Dog
River, Northfield, Vermont 3-7
3-3 Salmonid Habitat Mapping Units 3-10
3-4 Preliminary Total Residual Chlorine (TRC)
Sampling Results at Northfield, Vermont 3-11
3-5 Water Quality Results from the Dog River,
Northfield, Vermont, November 1982 3-12
3-6 Weighted Percentages of Habitat Type in Fish
Sampling Sections of the Dog River,
Northfield, Vermont 3-19
4-1 Summary of Available Background Data for
the Randolph, Vermont Case Study 4-2
4-2 Water Quality Sampling Transects on the
Third Branch of the White River, Randolph,
Vermont 4-8
4-3 Fish Sampling Sections on the Third Branch
of the White River 4-13
4-4 Selected Randolph Vermont WPCP Operational
Data, 18-23 July 1983 ~ 4-16
4-5 Water Quality Results From the Third
Branch of the White River, Randolph, 4-18
Vermont, July 1983
4-6 Statistical Analysis of Water Quality Data
from the Third Branch of the White River 4-21
4-7 Ranges of Temperature, Dissolved Oxygen,
Dissolved Oxygen Saturation, and pH from the
Third Branch of the White River 4-22
IV
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Table
LIST OF TABLES (Continued)
Page
4-8 Chlorinated Effluent Quality Results for the
Randolph WPCP 4-23
4-9 Flow in the Third Branch of the White River
and at the Randolph WPCP, July 1983 4-27
4-10 Fish Species Captured by Electrofishing
in the Third Branch of the White River,
July 1983 4-27
4-11 Condition Factors of Trout Captured in
Section A and B on the Third Branch of
the White River 4-34
4-12 Weighted Percentages of Habitat Type in the Four
Fish Sampling Sections of the Third Branch of
the White River 4-39
4-13 Summary of Macrobenthic Species Composition,
Numerical Abundance (NO./0.18 m ) and
Diversity from Four Sections of the Third
Branch of the White River, July 1983 4-40
5-1 Type of Disinfection Systems Used in
Northern New England 5-5
5-2 Reported Average Chlorine Dosage Rates 5-7
5-3 Degree of Treatment Versus Reported
Average Chlorine Dosage Rates 5-8
5-4 Mean Concentrations of Effluent Total
Residual Chlorine 5-9
5-5 Average Chlorine Contact Times 5-15
6-1 Water Quality Standards for Coliform Bacteria 6-15
v
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LIST OF FIGURES
Figure
2-1
2-2
2-3
2-4
3-1
3-2
3-3
3-4
4-1
4-2
4-3
4-4
Coldwater Fisheries Hazard Analysis Procedure
(CHAP)
Evaluations Necessary for Put-and-Take Trout
and Self-Sustaining Salmonid Fisheries Portions
of the Coldwater Fisheries Hazard Analysis
Procedure (CHAP)
Decisions and Evaluations for the Salmonid
Passage Portions of the Coldwater Fisheries
Hazard Analysis Procedure (CHAP)
Key Decisions of the Coldwater Fisheries
Hazard Analysis Procedure (CHAP)
Sampling Locations on the Dog River, Northfield,
Vermont, November 1982
Total Residual Chlorine Concentrations
Measured in the Dog River, near the
Northfield Vermont WPCP
Length Frequencies of Trout from the Dog River
Upstream of the Northfield Vermont WPCP,
November 1982
Areas Affected by Chlorinated Effluent in
the Dog River, November 1982
Sampling Locations on the Third Branch of the
White River, Randolph, Vermont, July 1983
Total Residual Chlorine (TRC) Concentrations
Measured in the Third Branch of the White
River, July 1983
Simultaneous Measurements of Effluent TRC
and Flow and TRC at Station II-L over a
12-hour Period
Population Estimates of Trout From Four
Sections of the Third Branch of the White
River, July 1983
Page
Bound
in
Back
2-5
2-13
2-17
3-5
3-13
3-17
3-27
4-9
4-19
4-25
4-29
VI
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LIST OF FIGURES (Continued)
Figure Page
4-5 Biomass of Trout From Four Sections of the
Third Branch of the White River, July 1983 4-31
4-6 Abundance and Biomass of All Trout From the
Four Sections of the Third Branch of the
White River, July 1983 4-35
4-7 Length Frequencies of all Trout From the Four
Fish Sampling Sections on the Third Branch
of the White River, July 1983 4-37
vi i
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ACKNOWLED GMENTS
The guidance and support of the U.S. Environmental
Protection Agency Region 1, Environmental Evaluation Section
Staff, and especially Robert E. Mendoza, Project Officer, and
Kenneth H. Wood, Project Manager, is gratefully acknowledged and
appreciated.
We are indebted to the individuals who provided assistance
during the conduct of the November 1982 field work in Northfield,
Vermont,and the July 1983 field work in Randolph, Vermont
including:
Carl F. Baren, Fisheries Biologist, U.S. Fish and Wildlife
Service
John H. Claussen, District Fisheries Biologist,
Vermont Fish and Game Department
John Gersmehl, Fisheries Biologist, U.S. Fish and
Wildlife Service
Marcel Hebert, Superintendent, Village of Northfield,
Water Pollution Control Plant
Thomas Kelly, Chief Operator, Village of Randolph, Water
Pollution Control Plant
Richard W. Langdon, Vermont Department of
Water Resources and Environmental Engineering,
Agency of Environmental Conservation
Kenneth H. Wood, Environmental Protection Specialist, U.S.
Environmental Protection Agency, Region I
We gratefully acknowledge cooperation of the many Maine,
New Hampshire and Vermont state and federal officials who
provided information or review comments on this report. In
particular, we thank the members of the U.S. Environmental
Protection Agency Technical Review Team:
Carl F. Baren, U.S. Fish and Wildlife Service
Jennie E. Bridge, New England Interstate Water Pollution
Control Commission
viii
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William A. Brungs, Ph.D., Acting Director, U.S. EPA
Environmental Research Laboratory, Narragansett
Rhode Island
David L. Courtemanch, Maine Department of Environmental
Protection
Terry Haines, U.S. Fish and Wildlife Service
Daniel M. Kuzmeskus, U.S. Fish and Wildlife Service
Richard W. Langdon, Vermont Department of Water
Resources and Environmental Engineering, Agency of
Environmental Conservation
Peter M. Nolan, U.S. EPA New England Regional Laboratory
Richard I. Phillips, Vermont Department of Water
Resources and Environmental Engineering, Agency of
Environmental Conservation
Ronald E. Towne, New Hampshire Water Supply and Pollution
Control Commission
Charles F. Thoits III, Chief of Fisheries, New Hampshire
Fish and Game Department
This report was prepared at Metcalf & Eddy, Inc. by the
following individuals:
Richard L. Ball, Jr.
Project Director
Robert J. Reimold, PhD
Project Manager/
Technical Specialist
Paul Geoghegan and
Matthew J. McGinniss
Biologists (Chapters 2,
3, 4,)
Meredith G. Durant
Engineer (Chapters 5, 6)
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DISCLAIMER
This report has been reviewed and approved for publication
by Metcalf & Eddy, Inc., and the U.S. Environmental Protection
Agency. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental
Protection Agency, nor does mention of trade names or commercial
products constitute endorsement or recommendation for use.
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REPORT
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CHAPTER 1
INTRODUCTION
Municipal disinfection practices may adversely
impact coldwater fisheries (e.g. salmon and trout) in northern
New England, where chlorination is the most common disinfection
method at municipal wastewater treatment plants. Yet chlorine is
extremely toxic to most forms of aquatic life, and can be
detrimental to salmonid fisheries (Nolan and Johnson 1977; Nolan
1979; Pagel and Langdon 1981). Concentrations of total residual
chlorine (TRC) from 0.03 to 0.09 mg/1 are acutely lethal to
juvenile rainbow trout (Salmo gairdneri) after 96 hours exposure
(Cairns and Conn 1979). Water quality criteria recommended for
chlorine for the protection of freshwater aquatic life
(Table 1-1) are about one tenth of acutely toxic levels.
Metcalf & Eddy, Inc. (1982) addressed the environmental
impacts of wastewater disinfectants and their byproducts on the
coldwater species of concern in northern New England. These
species include the Atlantic salmon (Salmo salar), brook trout
(Salvelinus fontinalis), rainbow trout (Salmo gairdneri) and
selected fish food organisms. This previous report reviewed the
available literature and recommended the use of a site-specific
hazard evaluation procedure to assess the need for dechlorination
(or an alternative disinfectant) based on the expected beneficial
impacts on indigenous fisheries. In addition, it was recommended
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TABLE 1-1. IN-STREAM WATER QUALITY CRITERIA
FOR TOTAL RESIDUAL CHLORINE (TRC)
Criteria
(mg/1)
Basis
Reference
0.002
0.003
0.002
0.005
0.010
Protection of salmonid
fisheries based on
continuous exposure.
Protection of all
water organisms.
fresh-
Protection of aquatic life
(measured by amperometric
titration or equivalent).
Protection of all fresh-
water organisms (measured
by amperometric titration
in conjunction with a
polarograph).
Protection of freshwater
aquatic life and its uses.
Average concentration not to
be exceeded in 30 consecutive
days.
U.S. EPA (1976)
Brungs (1976)
International
Joint Commission
(1978)
DeGraeve et al.
(1979)
U.S. EPA (1983)
that measures be evaluated for using the least amount of chlorine
for effective disinfection at existing chlorination facilities.
One objective of the present study was to field test and
improve the site specific hazard evaluation procedure, the Cold-
water Fisheries Hazard Analysis Procedure (CHAP). This report
evaluates the magnitude of potential adverse impacts of two
chlorinated municipal discharges on salmonid fisheries and
discusses applicable mitigation measures that protect salmonid
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resources and public health. Another objective of the present
study was to evaluate specific methods and recommend generic
remedial actions to improve disinfection systems and avoid
overchlorination at individual treatment plants.
An improved and expanded version of the Coldwater
Fisheries Hazard Analysis Procedure (CHAP) (Chapter 2) provides a
systematic approach for making site-specific decisions regarding
the need for disinfection, or the need for dechlorination.
Chapter 2 is designed as a users' manual for CHAP, and simplifies
and clarifies the hazard analysis procedure based on the
experience of two case studies, comments received by
participating agencies (Courtemanch 1982; Phillips 1982) and the
results of the chlorination study questionnaire.
CHAP was field tested with case studies at the Northfield
and Randolph, Vermont Water Pollution Control Plants. The
Northfield site, (one of several recommended by state agencies of
Maine, New Hampshire, and Vermont) was selected because it
affected a recreational trout fishery in the Dog River, and had
been the subject of a previous impact evaluation by the Vermont
Agency of Environmental Conservation (Pagel and Langdon 1981).
Field studies were conducted in early November 1982. Results of
the case study of the Northfield wastewater discharge on the Dog
River are presented in Chapter 3. Based on a review of the draft
of the Northfield case study (by the Technical Review Team), it
was concluded that a nore detailed scientific study was necessary
1-3
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to assess the full applicability of CHAP. Consequently, a second
case study was conducted at Randolph, Vermont, on the Third
Branch of the White River. This site was selected because it was
reported to support juvenile Atlantic salmon and self-sustaining
trout populations. Also, the U.S. Fish and Wildlife Service
since 1971 has conducted Atlantic salmon research in the White
River basin as part of the Atlantic Salmon Restoration Project
for the Connecticut River Basin (Baren 1983; Moffitt et al.
1982). In addition, the Randolph site had also been the subject
of preliminary studies by the Vermont Agency of Environmental
Conservation on the environmental effects of chlorination (Pagel
and Langdon 1981). Fieldwork at the Randolph site was conducted
in mid-July 1983 and the results are presented in Chapter 4.
A survey was conducted to obtain detailed information on
existing wastewater chlorination facilities in northern New
England. Results of the survey questionnaire (Appendix B)
including a summary of existing chlorination system operational
characteristics and potential mitigation measures are presented
in Chapter 5.
Recommendations for using the minimum amount of chlorine
to achieve effective disinfection at existing chlorination
facilities are presented in Chapter 6. Recommended improvements
range from immediate and inexpensive operational features to
major facility modifications. A brochure for treatment plant
operators on generic ways to minimize chlorine use while
1-4
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maintaining effective disinfection to protect public health is
presented in Appendix C.
1-5
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LITERATURE CITED
Baren, C. 1983. Fisheries Information on the Third Branch of the
White River. U.S. Fish and Wildlife Service, Fishery
Assistance, Montpelier, Vermont.
Brungs, W. 1976. Effects of Wastewater and Cooling Water
Chlorination on Aquatic Life. Ecological Research Series,
Environmental Research Labs, 600/3-76-698, 45 pp.
Cairns, V.W. and K. Conn. 1979. Acute lethality of wastewater
disinfection alternatives to juvenile rainbow trout. Research
Report No. 92., Wastewater Technology Center, Environmental
Protection Service, Environment Canada.
Courtemanch, D. 1982. State of Maine Department of Environmental
Evaluation and Lake Studies - Comments on the Draft Phase II
Report (Letter to K.H. Wood, U.S. EPA Region I, Boston,
Massachusetts), September 2, 1982.
DeGraeve, G.M. et al. 1979. Chlorine. Pages 67-75 in A Review
of the EPA Red Book: Quality Criteria for Water. R.V.
Thurston et al. (eds.) Water Quality Section, American
Fisheries Society, Bethesda, Maryland.
International Joint Commission. 1978. United States and
Canada. Group 2 Specific Water Quality Objectives.
Metcalf & Eddy, Inc., 1982. Impacts of Wastewater Disinfection
Practices on Coldwater Fisheries (Draft). Prepared for U.S.
Environmental Protection Agency, Region I, Boston,
Massachusetts.
Moffitt, C.M., B. Kynard, and S.G. Rideout. 1982. Fish passage
facilities and anadromous fish restoration in the Connecticut
River basin. Fisheries 7(6): 2-11.
Nolan, P. 1979. Acute Toxic Effects of Chlorinated Primary
Sewage Effluent on Brook Trout and Brown Trout. Manchester
Vermont - Battenkill River. U.S. Environmental Protection
Agency Region I, Boston, Massachusetts, 23 pp.
Nolan, P. and A. Johnson. 1977. Chlorine Toxicity Study, Mad
River - Waterville Valley; July 30 - August 8, 1976, U.S.
Environmental Protection Agency, Region I, Boston,
Massachusetts, 48 pp.
1-6
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Pagel, C.W., and R.W. Langdon. 1981. A Preliminary Study of the
Influence of Chlorinated Wastewater Effluent on the Biologial
Life of Selected Rivers and Streams in Vermont. State of
Vermont Agency for Environmental Conservation, Montpelier,
Vermont, 96pp.
Phillips, R.I. 1982. Environmental Engineer, Vermont Department
of Water Resources and Environmental Engineering (Letter to K.
Wood, U.S. EPA Region I) September 1982.
U.S. EPA 1976. Quality Criteria for Water. U.S. Environmental
Protection Agency, Washington, D.C, 256 pp.
U.S. EPA 1983. Draft Chlorine Criterion Document. U.S.
Environmental Protection Agency, Criteria and Standards,
Washington, D.C.
1-7
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CHAPTER 2
COLDWATER FISHERIES HAZARD
ANALYSIS PROCEDURE (CHAP)
The existing and anticipated municipal wastewater
disinfection practices in Maine, New Hampshire, and Vermont were
evaluated relative to their impacts on coldwater fisheries, as a
basis for development of a hazard evaluation procedure for
coldwater fisheries. This practical hazard evaluation procedure
(Figure 2-1 Bound in Back) is designed to assess impacts of
municipal wastewater disinfection practices (primarily
chlorination) on salmonid fisheries. The hazard evaluation
procedure is a decision flow-chart used to determine if
dechlorination or alternative disinfectants (e.g., ozone,
ultraviolet radiation) should be used to mitigate adverse impacts
on coldwater fisheries due to chlorination. The procedure relies
on careful scientific considerations for making realistic
decisions which safeguard public health and protect aquatic
natural resources.
This Coldwater Fisheries Hazard Analysis Procedure (CHAP)
was developed to account for three types of fisheries resources:
self-sustaining salmonids
put-and-take trout fishery
zone of passage for salmonids
Self-sustaining salmonid populations require a high degree of
protection because they are generally restricted to areas not
2-1
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subjected to man-made influences. Areas for self-sustaining
brook trout (Salvelinus fontinalis) populations and reestablished
spawning areas for the Atlantic salmon (Salmo salar) require
year-round protection. In contrast, areas that support put-and-
take fisheries, or serve only as a zone of passage, may only
require seasonal protection to ensure fish viability. Put-and-
take fisheries or corridors for passage are not considered to be
less valuable, but they may require less effort to ensure their
viability when compared to self-sustaining salmonid populations.
CHAP also addresses warmwater fisheries (which are also of great
recreational value) by recommending the least amount of chlorine
to be used at all wastewater treatment plants to maximize the
protection of aquatic biota and public health.
How to Use CHAP
The Coldwater Fisheries Hazard Analysis Procedure (CHAP)
follows the three levels of protection previously described.
Symbols used in the CHAP flow chart are standard information
processing symbols (Blatt 1971). Each symbol (presented in the
legend of the procedure, Figure 2-1) is used to connote
supporting information, estimates or evaluations, decisions, and
recommendations, as well as show the flow of information.
Key decision points in CHAP include, for example, being
able to decide if adverse impacts are attributable to the
effluent (Step 19, Figure 2-1), and if so, whether these adverse
impacts are due primarily to c'nlorination (Step 20, Figure
2-2
-------
2-1).CHAP is designed so that information necessary for the
decision is collected by the time the key decision points are
reached.
CHAP maximizes the use of existing information. However,
specific site visits and impact evaluation procedures are
recommended if information does not exist. Usually there is lack
of existing information on field documentation of self-sustaining
salmonid populations. Adequate existing information should be
available related to put-and-take fisheries and zones of salmonid
passage.
Initial Determinations
Disinfection. The first step in Coldwater Fisheries
Hazard Analysis Procedure (CHAP) (Figure 2-1) is to determine if
disinfection is required, and if so, what disinfectant is most
suitable. This decision has generally been made already based on
public health considerations, and existing information can be
obtained from the state environmental engineering agency and the
treatment plant operator relative to the basis for this
decision. Chlorination, the predominant form of disinfection in
northern New England (Metcalf & Eddy, Inc. 1982), is assumed
throughout the procedure. Any other disinfectant that might be
in use (or planned) probably has already been the subject of
detailed studies justifying its use. Consequently, in the case
of non-chlorine disinfection, CHAP recommends a review of the
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justification for the alternative disinfectant, and a report
documenting the reasons (Steps 2 and 4, Figure 2-1).
Initial Input. With chlorine as the chosen method of
disinfection, specific information is needed to evaluate the
site-specific hazards. Most of this site-specific information
(Step 6, Figure 2-1) can be obtained from the federal or state
discharge permit, the wastewater facilities plan and the
companion environmental information document or environmental
impact statement. Data which may not be in these documents,
including: a) pH and NH3 characteristics of wastewater and
receiving water; b) USGS locus map of discharge; c) stream
flow data; d) private and public water supplies both upstream
and downstream; can be obtained from state water pollution
control and fish and game agencies.
Salmonid Fishery. After review of existing data, a
determination must be made regarding the type of fishery that
exists downstream from the discharge (Step 8, Figure 2-1). This
determination should include consultation with the state
freshwater fisheries agency and the local field office of the
U.S. Fish and Wildlife Service.
Self-Sustaining Salmonids
Preliminary Impact Evaluation. If a salmonid fishery
exists, a preliminary impact evaluation (Step 9, Figure 2-2) is
needed to determine the type of existing salmonid fishery and
habitat. This preliminary evaluation, to decide if the habitat
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PAGE NOT
AVAILABLE
DIGITALLY
-------
supports (or potentially supports) a put-and-take fishery or
self-sustaining fishery, (Step 10, Figure 2-2) can be done
through a literature search, angler survey, or contact with the
state fisheries agency. If recent accurate and comprehensive
information is not available, it may be necessary to conduct fish
sampling to determine species composition.
Detailed Impact Study. If self-sustaining salmonid
habitat is measurably affected by the discharge, then more
detailed studies are necessary (Step 12, Figure 2-2), to
determine if the habitat is impacted by disinfection practices.
These studies will also determine if adverse impacts are
attributable to constituents in the effluent other than
chlorine. Data from the preliminary impact evaluation (Step 9
Figure 2-2) are used to determine the level of effort (Step 11,
Figure 2-2) appropriate for the detailed impact evaluation.
Field studies appropriate for the detailed impact evaluation
(Step 12, Figure 2-2) include water quality sampling, fish
population assessment, macroinvertebrate sampling and fish
habitat mapping.
Water quality sampling should include temperature,
conductivity, pH, dissolved oxygen (DO), NH3-N, TRC, alkalinity,
chlorine demand, total and fecal coliforms. Station selection
should be based on preliminary total residual chlorine (TRC)
sampling, with at least one transect (control) located upstream
of the outfall. The most downstream transect should be located
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below the downstream limit of TRC detection. At least two
transects should be located between the upstream and downstream
transects. A water quality transect should also be located in
each fish sampling section. The number of stations per transect
and replicates of each parameter will vary with site and cost
considerations. Selection of station location can also be aided
by dye testing of the effluent. Tracking the downstream movement
of the effluent with a small amount of dye will also help in
evaluating mixing characteristics in the river or stream.
TRC monitoring should be conducted with an amperometric
titrator and samples analyzed immediately after collection (APHA
1976). It is important to use this technique, which can result
in detection levels as low as 0.01 mg/1, (Jolley and Carpenter
1982) which corresponds to the lower end of the range of
potential TRC toxicity. Criteria for selection of an alternate
method of TRC determination should include the field conditions
in which the analyst will be working, and the large number of
samples to be processed in a short time. The analyst should
attempt to measure and report the components of TRC expected at
the site based on pH, ammonia concentrations, and other water
quality features. Jolley and Carpenter (1982) provide a helpful
review of aqueous chlorine chemistry and analytic methods.
Fish populations should be assessed in several stream
sections, one upstream (control) section and enough sections
downstream of the outfall to determine the extent of potential
2-8
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adverse impacts. This assessment is most effectively done by
electrofishing. This sampling method is probably the most
nonselective (Lagler 1978) and often may be accomplished with the
cooperation of the state freshwater fishery agency. A more
detailed fish population estimate can be made by mark and
recapture procedures, catch and effort regressions (Ricker 1975;
Seber and Le Cren (1967) or relative estimates made by comparison
of catch per unit effort. The two-step method of Seber and
LeCren (1967) is adequate for a one-time assessment of fish
populations, but not adequate to determine if trout standing
stocks change over time (Platts et al. 1983). The Zippin method,
with four separate fish removals can be used to determine if
small chahges in fish population estimates over time are
significant (Ricker 1975; Platts et al. 1983). Bagenal ( 1978)
provides a review of methods for assessing fish production. The
downstream fish sampling sections should be the closest salmonid
habitats to the outfall and should be similar to the habitat of
the upstream (control) transect, to reduce the variability of the
fish sampling results. It may not be possible to locate such a
section within the area impacted by the effluent, but efforts
should be made to minimize habitat differences.
Habitat should be quantitatively assessed in each stream
section to differentiate habitat effects from effluent effects.
Fish sampling sections can be divided into three to six meter
segments for mapping, using a habitat mapping scheme similar to
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Oswood arid Barber ( 1982). The areal extent of shallow, deep,
fast, slow, available spawning habitat, and available cover
(e.g., overhanging vegetation, undercut banks) are noted. The
percentage areal extent of each habitat can be statistically
compared between the two stream sections to document physical
habitat similarities among fish sampling sections. An added
benefit of this quantitative technique is the resultant map which
serves as a valuable visual record of the stream sections. If
time and expense are a constraint a less intensive habitat
assessment technique could be employed. Platts et al. (1983)
review a variety of stream habitat evaluation techniques.
Another integral part of habitat assessment includes the
invertebrate populations. Aquatic invertebrates often are food
for salmonids and some invertebrate species are more sensitive to
chlorine than salmonids. Reduced populations of aquatic
invertebrates may result in a reduction of salmonid populations
due to the decreased food availability. Aquatic invertebrate
populations may be assessed by methods in Lind (1974). A Surber
square foot sampler is suitable for sampling macrobenthos of
running waters, less than 0.3 m depth. The Ekman dredge should
be used for sand, mud or silt bottoms for streams and rivers when
the depth exceeds 0.3 m. A number of upstream (control) samples,
and downstream samples, within the downstream fish sampling
section, should be assessed for benthic species diversity and
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composition. Platts et al. (1983) review steam habitat, fish
population and macroinvertebrate sampling methods and analyses.
Put-and-Take Trout Fishery
In a put-and-take fishery, hatchery reared fish are
stocked in a waterbody and removed by recreational fishing;
no attempt is made to establish a self-sustaining population.
Some stocked areas do not even contain suitable reproductive or
juvenile habitat necessary to naturally sustain reproducing
populations. This Coldwater Fisheries Hazard Analysis Procedure,
(CHAP) is designed to evaluate potential adverse impacts of the
chlorinated effluent on a put-and-take fishery and to
determine whether appropriate mitigation of these adverse impacts
might permit restoration of a self-sustaining fishery.
Impact Evaluation. This impact evaluation (Step 13,
Figure 2-2) differs from the detailed evaluation previously
described (Step 12, Figure 2-2) in that only two areas of field
data collection are required, and water quality sampling and
habitat assessment efforts are reduced.
The sampling scheme for this evaluation is similar to the
detailed impact evaluation (Step 12, Figure 2-2) in that one
water quality sample site (control) should be located in an area
not impacted by the effluent, and others at an area downstream
from the discharge where potential impacts may occur. Water
quality sampling should include at least TRC, DO, temperature and
pH.
2-11
-------
This put-and-take trout habitat assessment requires only a
brief survey of the available salmonid spawning habitat near the
discharge. Spawning habitat of trout consists of well aerated
gravel from 8 to 256 mm in diameter (Oswood and Barber 1982).
Rainbow, brown, and brook trout usually spawn in finer gravel of
smaller tributaries. However, if habitat is available, brown and
brook trout may spawn in the lower reaches of rivers, or in lakes
(Scott and Crossman 1973). Comparisons between impacted areas
and the control should provide information on the magnitude of
existing impacts and address whether the discharge prevents
establishment of a self-sustaining trout population. This
information is then used to determine the benefits associated
with mitigation of existing impacts on the put-and-take fishery.
Salmonid Passage
Salmonids may utilize streams for passage to spawning
grounds. Information collected (Step 7, Figure 2-3) is used to
decide if a stream is used for salmonid passage (Step 14,
Figure 2-3). If the receiving water does not (or will not)
support passage by salmonids to spawning grounds, then a report
should be prepared (Step 15, Figure 2-3) to document the decision
making process and to recommend ways to minimize excessive
chlorine use at the plant. If the stream or river does (or
could) serve as a salmonid passage, then some additional site-
specific data must be obtained.
2-12
-------
SALMONID
PASSAGE
• DETERMINE SALMONIDS OF
CONCERN AND STREAM
SPECIFIC CRITICAL PERIODS
EVALUATE ZONE OF PASSAGE
W PREDICTIVE MODEL
IF NECESSARV
CONOUCT PRELIMINARY
SITE VISIT, IF NECESSARY
MINIMIZE EXCESSIVE
CL2 USE
DOCUMENT IMPACT
EVALUATION
PROCESS
IS
• MINIMIZE EXCESSIVE
YES
CL2 USE
• DOCUMENT IMPACT
EVALUATION
PROCESS
18
LEGENO
ESTIMATES. EVALUATIONS
TESTS. SITE VISITS
MODELING. ETC
DECISIONS
DOCUMENTATION
INFORMATION
(LOW
FIG. 2-3 DECISIONS AND EVALUATIONS FOR THE SALMONID PASSAGE
PORTION OF THE COLDWATER FISHERIES HAZARD ANALYSIS PROCEDURE (CHAP)
-------
Zone of Passage. The TRC concentrations must be less than
0.05 mg/1 (Step 17, Figure 2-3) to ensure passage to and from
spawning grounds.* The criterion of 0.05 mg/1 was chosen since
this is the lower limit of values determined to elicit obligatory
chlorine avoidance behavior in salmonids (Metcalf & Eddy, Inc.
1982). For example, Schumacher and Ney (1980) found
that avoidance responses of rainbow trout were elicited by TRC
concentrations from 0.05 mg/1 to 0.1 mg/1. This zone of passage
can be assessed by determining TRC levels with an amperometric
titrator during the critical (e.g., low flow) migratory period
at the site (Step 16, Figure 2-3). Sampling should include an
upstream control, and downstream transects as far as TRC is
detectable to determine if a zone of passage (TRC <0.05 mg/1)
exists. This sampling will also provide information on the size
of the impacted area (where TRC exceeds 0.05 mg/1). If
anadromous salmonid passage is an issue and interstate waters are
involved, then adjacent states and the U.S. Fish and Wildlife
Service should be involved in this process.
If TRC values are greater than 0.05 mg/1, a report should
summarize these findings and recommend means of minimizing
excessive chlorine use. If a zone of passage cannot be ensured,
additional studies may be necessary to determine costs and
benefits associated with mitigating this adverse impact.
* Maine DEP is evaluating an alternative approach based on the
mixing characteristics of the discharge.
2-15
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Key Decisions
The implementation of the components of Coldwater
Fisheries Hazard Analysis Procedure (CHAP) results in a
comprehensive data base upon which defensible key decisions are
made.
Adverse Impacts Due to Effluent. Comparison of habitats,
water quality and fish populations can be made to determine if
adverse impacts are due to effluent (Step 19, Figure 2-4).
Statistically significant differences between fish populations in
similar habitats above and below the outfall, are evidence of an
adverse effect due to effluent. Water quality sampling results
will enable identification of critical factors that also may
impact coldwater fisheries. For example, the NH^-N sampling
results should be compared to the draft (J.S. EPA site-specific
criterion value (U.S. EPA 1983) to determine if un-ionized
ammonia is a problem at the site. Similarly, the impact
evaluation on the put-and-take fishery will determine if the
effluent is preventing or impairing reproduction. The next step
is to determine if the adverse impacts can be attributed to
chlorination.
Significant Adverse Impact Due to Chlorination. In areas
with depressed fish populations but suitable habitat, the
presence of TRC concentrations >0.03 mg/1 are indicative of an
adverse impact due to chlorine. TRC levels of 0.03 to 0.09 mg/1
are acutely toxic to juvenile rainbow trout (Wolf et al. 1975;
2-16
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
Cairns and Conn 1979). Criteria for determining the significance
of adverse impacts (Step 20, Figure 2-4) include:
1. Would chlorination preclude complete utilization of an
existing or planned Atlantic salmon or wild brook
trout fishery by interfering with fish reproduction,
growth and survival?
2. Would elimination of chlorination significantly
improve a put-and-take trout fishery by allowing
reproduction, better growth, and survival?
3. Would elimination of chlorination ensure or improve
successful passage of migrating salmonids by
eliminating avoidance?
If no significant impact due to chlorination is found, then a
report detailing this finding should be prepared.
Cost of Mitigation. If chlorination has a demonstrated
significant impact on the salmonid or put-and-take trout
fisheries, alternatives for mitigating the impact must be
evaluated (Steps 23 and 25, Figure 2-4). Cost estimates,
environmental impacts, engineering considerations, and public
participation are the main components of this additional
evaluation (Step 22, Figure 2-4) If mitigation costs are
determined to be greater than any derived benefit, then more
innovative mitigation techniques (Step 24 and 25, Figure 2-4)
should be pursued. Cost-effective mitigation techniques
(Step 26, Figure 2-4) include an alternative means of
2-19
-------
disinfection (ozonation, or ultraviolet radiation) (Step 27),
dechlorination (Step 28), and outfall relocation or treatment
process modification (Step 29).
The Coldwater Fisheries Hazard Analysis Procedure (CHAP)
offers a coherent and systematic approach for assessing the site-
specific impacts of wastewater disinfection practices on salmonid
fisheries. CHAP is used to determine if dechlorination or
alternative disinfectants might be necessary to mitigate adverse
impacts due to chlorine's effects on self-sustaining salmon or
trout populations, put-and-take trout fisheries, and areas
critical for seasonal passage by salmon or trout. This procedure
maximizes the use of existing information, but also enumerates
applicable methodologies for collection of supplemental data
(including water quality sampling, fish population assessments,
fish habitat mapping, and benthic invertebrate sampling) required
for detailed impact evaluation. Information from literature
review, field studies and detailed evaluation is used to address
the key issue — whether or not there are significant adverse
environmental impacts from the effluent discharge due to
chlorination. If chlorination impacts are significant, then
mitigation measures must be evaluated. Alternative mitigation
techniques include dechlorination, outfall relocation, treatment
process modification or the use of some other disinfection
process (e.g., ozone or ultraviolet radiation).
2-20
-------
LITERATURE CITED
American Public Health Association. (APHA) 1976. Standard
Methods for the Examination of Water and Wastewater.
Fourteenth Edition. American Public Health Association,
Washington, D.C. 1193 pp.
Bagenal, T. (ed.) 1978. Methods for Assessment of Fish
Production in Fresh Waters. Third Edition; International
Biological Programme Handbook No. 3, Blackwell Scientific
Publications, Oxford, England. 365 pp.
Blatt, J. M. 1971. Introduction to Fortran IV Programming
Using the Watfor/Watfiv Compilers. Goodyear Publishing Co.,
Pacific Palisades, California.
Cairns, V. W. and K. Conn. 1979. Acute lethality of wastewater
disinfection alternatives to juvenile rainbow trout. Research
Report No. 92., Wastewater Technology Center, Environmental
Protection Service, Environment Canada.
Jolley, R.L. and J.H. Carpenter. 1982. Aqueous chemistry of
chlorine: Chemistry, analysis and environmental fate of
reactive oxidant species. ORNL/TM-7788, Oak Ridge National
Laboratory, Chemical Technology Division, Oak Ridge, Tennessee
Lagler, K. F. 1978. Capture, Sampling and Examination of
Fishes. Pages 7-47 in T. Baganal (ed.). Methods for
Assessment of Fish Production in Fresh Waters. Third
Edition. International Biological Programme Handbook No. 3,
Blackwell Scientific Publications, Oxford, England. 365 pp.
Lind, 0. T. 1974. Handbook of Common Methods in Limnology.
The C.V. Mosby Company, Saint Louis, 154 pp.
Metcalf & Eddy, Inc. 1982. Impacts of Wastewater Disinfection
Practices on Coldwater Fisheries (draft). Prepared for U.S.
EPA Region I, Boston, Massachusetts.
Oswood, M. E. and W. E. Barber. 1982. Assessment of fish
habitat in streams: goals, constraints, and a new technique.
Fisheries 7(4):8—11-
Platts, W.S., w.F. Megahan and G.W. Minshall. 1983. Methods
for Evaluating Stream, Riparian, and Biotic Conditions.
General Technical Report, INT-138, U.S. Department of
Agriculture, Forest Service, Intermountain Forest and Range
Experiment Station, Ogden, UT., 70 pp.
2-21
-------
Ricker, W. E. 1975. Computation and Interpretation of
Biological Statistics of Fish Populations. Bulletin 191.
Environment Canada, Fisheries and Marine Service, 382 pp.
Schumacher, P.D., and J.J. Ney. 1980. Avoidance response of
rainbow trout (Saimo gairdneri) to single-dose chlorination in
a power plant discharge canal. Water res. 14: 651-655.
Scott, W. B. and E. J. Crossman. 1973. Freshwater Fishes of
Canada. Fisheries Research Board of Canada, Bulletin 184,
Ottawa, Canada. 966 pp.
Seber, G. A. F. and E. D. Le Cren. 1967. Estimating population
parameters from catches large relative to the population. J.
Animal Ecology. 36:631-643
U.S. Environmental Protection Agency. 1983. Water Quality for
the Protection of Aquatic Life and its uses: Ammonia (Final
Draft). U.S. Environmental protection Agency, Office of
Reserach and Development, Environmental Research Laboratory,
Duluth, Minnesota, 189 pp.
Wolf, E. G., M. J. Schneider, K. 0. Schwarzmiller and T. 0.
Thatcher. 1975. Toxicity tests on the combined effects of
chlorine and temperature on rainbow (Saimo gairdneri) and brook
(Saiveiinus fontinalis) trout. U.S. Energy Research and
Development Administration Contract No. AT (45-1) - 1830.
2-22
-------
CHAPTER 3
IMPACT OF CHLORINATED EFFLUENT ON
TROOT FISHERIES OF THE DOG RIVER -
A CASE STUDY
In order to assess the applicability of CHAP, a field test
of the procedure was conducted in Northfield, Vermont, on the Dog
River, which receives effluent from the Village of Northfield
Water Pollution Control Plant (WPCP). The Northfield WPCP
discharges an average flow of 0.76 million gallons per day (mgd)
(0.03 m^/sec) to the Dog River. The State of Vermont classifies
the Dog River as class C, suitable for recreation, irrigation,
and some industrial uses. The requirement for year-round
disinfection is currently being evaluated by Vermont with the
possibility of seasonal disinfection at the site.
Available background data for the Northfield site
(Table 3-1) revealed a paucity of water quality data,
particularly for total residual chlorine in the river.
Macrobenthic and fisheries data were available in previous
reports (Marcinko 1980; Pagel and Langdon 1981). However,
additional specific water quality and fisheries-related
data including stream flow, water and effluent quality
characteristics, relative salmonid populations, and salmonid
habitat, were prerequisite for implementation of the Coldwater
Fisheries Hazard Analysis Procedure (CHAP). Field investigations
were conducted during a low-flow period in early November 1982.
3-1
-------
TABLE 3-1. SUMMARY OF AVAILABLE BACKGROUND DATA FOR THE
NORTHFIELD, VERMONT CASE STUDY
DISCHARGE
NAME OF FACILITY
AVERAGE FLOW
TRC CONCN'S
OUTFALL TYPE
pH & NH3 CONCN'S
Village of Northfield, VT Water Pollu-
tion Control Plant
0.76 mgd - Trickling Filter Plant
Free chlorine 0.1 to 0.3 mg/1; TRC 2.7 to
3.6 mg/1
Unknown
pH 6.8 to 7.1; TKN - no data
RECEIVING WATER
NAME OF STREAM AND
MAJOR DRAINAGE BASIN
WATER QUALITY
CLASSIFICATION AND
STANDARDS
TYPE OF FISHERY
FLOW DATA
pH & NH3 CONCN'S
SUMMERTIME
TEMPERATURES
PUBLIC HEALTH
PRIVATE AND PUBLIC
WATER SUPPLIES
CONTACT USES
Dog River; Winooski River Basin, VT
Dog River is Class C from discharge to
confluence with Winooski River
(10 kilometers).
Rainbow and Brown Trout
7Q10 - 3.2 cfs (Dog River at Northfield,
VT)
No data
17 to 22 deg C
None known to Vermont Agency of
Environmental Conservation
No formal swimming or boating facilities,
some occasional swimming, boating,
fishing.
Source: Phillips (1982)
3-2
-------
Agencies that assisted Metcalf & Eddy, Inc. during the field work
included: U.S. Environmental Protection Agency Region I; Vermont
Department of Fish and Game; Vermont Department of Water
Resources and Environmental Engineering, and the U.S. Fish and
Wildlife Service.
Materials and Methods
WPCP Characteristics. The Northfield WPCP was designed to
provide secondary treatment (trickling filter) to an average
daily wastewater flow of 1.63 mgd (0.07 m^/sec). The 1982
average daily flow of 0.76 mgd was lower than designed because
industrial flows were not as large as expected. Chlorination is
provided by a 700 lbs/day chlorinator set at its minimum rate of
30 to 35 lbs/day. Chlorine is fed through diffusers into an open
channel and effluent discharged from an outfall terminus located
mid-stream in the Dog River (Figure 3-1). Total residual
chlorine (TRC) content of the effluent is monitored daily in the
Northfield WPCP by the plant operator using the DPD color
comparator method. Effluent flow, measured by a magnetic meter
(Metcalf and Eddy, Inc. 1981), is recorded on a circular chart in
the Northfield WPCP operations building.
Streamflow Measurements. To supplement information
routinely taken by the WPCP operator, streamflow measurements in
this study were taken 20 meters (m) upstream from the WPCP
outfall using a Marsh-McBirney Model 201 water velocity meter
(Boyer 1964). Streamflow measurements were made by determining
3-3
-------
mean velocity at 0.6 the depth in a number of partial sections
across the river. Total streamflow was computed as the sum of
the discharges from the partial sections. U.S. Geological Survey
flow gaging information was also obtained for the Dog River, at
Northfield Falls. This gage (Station Number 04287000) is located
about 2.7 kilometers downstream from the WPCP (White 1983).
Water Quality Sampling. Preliminary total residual
chlorine (TRC) sampling using an amperometric titrator was
conducted to establish locations of four water quality transects,
with three sample stations per transect. This preliminary water
quality sampling was conducted on the effluent, and areas
upstream (23 m) , and downstream (50 m) of the outfall. A
fluorescent dye (Rhodamine WT) was added to the effluent to
locate the discharge plume as an aid to station location and to
determine where total mixing occurred.
Transect I, (Figure 3-1) the control, was located 23 m
upstream of the outfall where TRC levels were <0.05 mg/1 (See
Results). Transects II, III and IV were located 1.2, 13.4 and
26 m downstream of the outfall respectively. Stations were
identified by Roman numerals for transect, and capital letters
for location within a transect (Figure 3-1, Table 3-2).
At each station, TRC, NH3-N, total coliform, fecal
coliform, fecal streptococci bacteria, temperature, dissolved
oxygen, pH and conductivity levels were determined. TRC
concentrations were measured on-site with a Fisher Scientific
3-4
-------
northfield
WpCP7 VAin
legend
fish sampling
SECTION
TRANSECT
1/ Ruins of
NJL former dam
FIG. 3-1 SAMPLING STATIONS ON THE DOG RIVER,
NORTHFIELD, VERMONT, NOVEMBER 1982
-------
TABLE 3-2. WATER QUALITY SAMPLING STATIONS ON THE
DOG RIVER, NORTHFIELD, VERMONT
Distance from Distance from
Station outfall (m) East Bank (m)
I-L
23
upstream
4.6
I-M
23
upstream
9.1
I-R
23
upstream
13.7
II-L
1.2
downstream
4.6
II-M
1.2
downstream
12.8
II-R
1.2
downstream
16.2
I II-L
13.4
downstream
3.7
III-M
13.4
downstream
11.3
I II-R
13.4
downstream
15.2
IV-L
26
downstream
2.0
IV-M
26
downstream
6.0
IV-R
26
downstream
10.0
* L = left
third of river,
facing downstream;
M = middle
of river; R = right third of river.
Model 393 amperometric titrator within five minutes of
collection. TRC detection limits for this study were established
at 0.05 mg/1. Under ideal laboratory conditions, manual
amperometric titration has a lower limit of detection ranging
from 0.012 mg/1 (Jolley and Carpenter 1982) to 0.03 mg/1 (Sugam
1983), and no field method has a reliable limit of detection
below 0.02 mg/1 (Sugam 1983). NH3-N samples were kept
3-7
-------
refrigerated until measured at the lab using an EPA approved
method (U.S. EPA 1979). Total coliform, fecal coliform and fecal
streptococci bacteria samples were collected in sterile "Whirl-
Paks" containing a dechlorinating agent. These samples were kept
on ice until delivered to the lab where bacteria levels were
determined by the membrane filter technique (APHA 1976). In
addition, a chlorophyll a sample was taken at Transect I and
measured by a spectrophotometric method (APHA 1976).
Temperature, dissolved oxygen, pH, and conductivity were
determined in situ using a Hydrolab 4041 water quality sampler.
Fisheries Sampling and Habitat Mapping. Two 60-m sections
of stream were assessed for salmonid fish populations using a
direct current (DC) electroshocker. One section was located
210 m upstream and one 100 m downstream from the outfall
(Figure 3-1). These stream sections were chosen for their
similarity in salmonid habitat. One pass with the electroshocker
was made in each section to estimate the relative salmonid
abundance. Salmonids collected were identified, weighed,
measured for total length to the nearest half centimeter, and
then released. Approximate age determination was made by the
length frequency method.
Relative catch per unit effort (C/f) was used to compare
the fish populations in the two fish sampling sections. Catch
per unit effort was calculated as the number of salmonids
3-8
-------
9
captured per unit time electroshocking per m of fish sampling
section.
Habitat was mapped (Oswood and Barber 1982) in these two
stream sections for quantitative comparisons. Each 60-m section
was divided into 6-m segments, for assessment of: stream depth,
stream flow, forest debris, undercut bank, riparian vegetation
and available spawning area (Table 3-3).
Statistical Analysis. The Kruskal-Wallis nonparametric
test (Sokal and Rohlf 1982) was used to test significant
differences between transects for water quality parameters. A
nonparametric test was used because some water quality parameters
reported were equal to or less than levels of detection. This
nonparametric test requires the rank, not absolute magnitude of
the observation, and makes no assumption about the distribution
of the data.
Weighted mean percentages in each section were calculated
from percentage of habitat type in each segment, weighted by the
segment area. Statistical comparisons of weighted mean
percentage of habitat type between the two sections were made
with t-tests (Sokal and Rohlf 1982).
The significance level for all statistical tests was
P _<_ a = 0.05.
Results
River flow measured about 20 m upstream from the WPCP
outfall was 0.52 m^/sec (11.8 mgd) on November 3, 1982. This was
3-9
-------
TABLE 3-3. SALMONID HABITAT MAPPING UNITS
Unit
Description
Total Area (TA)
Total m within the sampling segment.
Shallow Slow (SS)
Area of water less than 0.5 m deep and
water velocity less than 0.3 m/s.
Shallow Fast (SF)
Area of water less than 0.5 m deep and
water velocity more than 0.3 m/s.
Deep Slow (DS)
Area of water deeper than 0.5 m and water
velocity less than 0.3 m/s.
Deep Fast (DF)
Area of water deeper than 0.5 m and water
velocity more than 0.3 m/s.
Forest Debris (FD)
Area of fallen trees and branches in the
sampling station (fish cover).
Undercut Banks (UB)
Area of eroded stream banks which offer
overhead cover for fish.
Riparian Vegetation
(RV)
Area of overhanging vegetation along
stream banks (fish cover).
Available Spawning
Area (ASA)
Area of stream substrate materials which
have a diameter between 8 mm and 256 mm.
Source: Oswood and Barber (1982)
well below the 0.79 m^/s (18.2 mgd) recorded on the same date at
the USGS flow gage downstream from the WPCP. River flow during
the sampling period (November 2 to 5, 1982) ranged from 0.7 to
2.0 m^/s (16 to 46 mgd) (White 1983). Treatment plant flow
during this period was 0.046 m^/s (1.05 mgd). This represented a
dilution factor of 11:1, receiving water to effluent. Dilution
was in fact higher since the influent flow to the plant is
diluted in the sewer with river water (about 0.02 m^/sec,
3-10
-------
0.46 mgd). This practice prevents solids buildup in the sewer
interceptor and ensures sufficient flow to rotate the trickling
filter arm at the WPCP (Hebert 1982).
Preliminary TRC sampling (Table 3-4) indicated that TRC
levels were nondetectable above the outfall and 50m downstream
from the discharge.
TABLE 3-4. PRELIMINARY TOTAL RESIDUAL CHLORINE (TRC)
SAMPLING RESULTS, AT NORTHFIELD, VERMONT, NOVEMBER 1982
Station
TRC Concentration (mg/1)
23 m upstream
< 0.05 (nondetectable)
Wastewater effluent
1.9
At effluent outfall
00
•
o
50 m downstream
< 0.05
Water quality results (Table 3-5) show that changes in
water quality due to the WPCP were evident at Station II-M,
located 1.2 meters directly downstream from the discharge.
Highest levels of temperature (12.3 deg C), conductivity (235
us/cm), NH-j-N (4.2 mg/1), and TRC (1.4 mg/1) were recorded at
station II-M, directly in the discharge plume (Table 3-5). In
contrast, dissolved oxygen was lowest (8.3 mg/1) at station II-
M. Levels of pH ranged from 6.0 to 7.0 and were highest down-
stream at Transect IV. Chlorophyll a concentration at Transect I
was 1.5 mg/m^. TRC residuals (Figure 3-2) rapidly decayed to
3-11
-------
TABLE 3-5, WATER QUALITY RESULTS FROM THE DOG RIVER, NORTHFIELD, VERMONT, November 1982
Parameter
Temperature
Dissolved
Oxygen
Conductivity
pH
Tota
Col 1 form
Fecal
Streptococci
NH3-N
Total Residual
Chlor 1ne
Unit
Dec
. c
ntg/l
pS/cm
No/IOOml
No/100ml
mg/l
mg/l
Station
L
M
R
L M
R
L
M
R
L
M
R
L
M
R
L
M
R
L
M
R
L
M
R
TRANSECT
1
11.4
11.4
11.4
9.7 9.7
9.5
134
134
133
6.0
6.3
6.5
540
530
390
120
39
79
0.34
0.14
0.02
0.05
< 0.05
< 0.05
11
11.2
12.3
11.4
10.0 8.3
9.6
133
235
133
7.1
6.4
6.5
1700
500
2500
561
10
44
0.4
04.2
0.04
0.05
1.4
< 0.05
1 1 1
11.3
11.7
11.4
10.1 9.5
9.6
132
177
138
6.5
6.0
6.4
1700
1300
1800
50
15
19
< 0.02
2.3
0.23
< 0.05
0.83
< 0.05
IV
11.5
11.4
11.4
9.5 9.7
9.8
138
139
141
7.0
6.9
6.9
2000
1600
1200
210
372
80
0.40
0.59
0.88
0.17
0.10
0.16
• L • left Third of river, facing downstream; M » middle third of river; R » right third of river.
-------
I
M
STATION
LEGEND
TRANSECT I
TRANSECT It
TRANSECT HI
— TRANSECT T3Z
FIG. 3-2 TOTAL RESIDUAL CHLORINE CONCENTRATIONS MEASURED
IN THE DOG RIVER, NEAR THE NORTHFIELD, VERMONT WPCP
-------
less than 0.2 mg/1 at Transect IV, 26 m downstream from the
outfall.
Additions of a small amount of rhodamine WT dye in the
effluent indicated that the effluent was completely mixed in the
stream about 30 to 35 m downstream from the outfall. Complete
mixing near this point was also indicated by the homogeneity of
water quality parameter levels among stations in comparison to
the variability observed at transects II and III.
Total coliform levels near the discharge were low (500/100
ml), but increased downstream (Table 3-5). Fecal streptrococci
levels were lowest at station III-M (15/100 ml) and highest at
station IV-R (280/100 ml). Unfortunately, fecal coliform levels
were not reportable due to an absence of characteristic colonies
and the growth of atypical colonies.
Significant differences in pH levels (a(H') = 0.048) were
recorded between transects. No other significant differences
between transects for water quality parameters were recorded.
However, true replication within a transect was not achieved
because stations L, M, and R were in different locations along
the transect. This ' statistical analysis demonstrates the
"between transect" differences in pH attributable to the WPCP
effluent, when stations are pooled for a transect.
Salmonid fish populations differed greatly above and below
the outfall. Relative salmonid catch-per-unit effort, C/F,
3-15
-------
(where catch (C) is the number of salmonids collected and
effort (f) is the time in minutes electrofishing per square
meter) was 0.39 upstream and 0.001 downstream of the treatment
plant. The upstream catch consisted of 97 young-of-the-year
rainbow trout, 15 yearling (age 1 + ) rainbow trout as aged by
length frequency, one brook trout, and five brown trout (Figure
3-3). The downstream salmonid catch was one rainbow trout (218
mm, 100 g).
Habitat mapping results (Table 3-6) (Appendix A) revealed
no significant difference in weighted mean percentages between
the two fish sampling sections for shallow slow (SS) and shallow
fast (SF) habitats (SS: a (t's) = 0.48, SF: a (t's) = 0.46), but
weighted mean percentages of available spawning areas (ASA) were
significantly greater upstream ( a(t's) = 0.009). A small area
of deep fast habitat (DF) was present in the upstream section and
absent downstream, while small areas of riparian vegetation (RV)
and deep slow (DS) habitats were present downstream but lacking
upstream. Undercut banks (UB) and forest debris (FD) were
present in small quantities in both sections. Statistical tests
on differences between stream sections for UB and FD habitats
would not be meaningful because the tests would be sensitive to
extremely small changes in the area of these habitats. A small
rise in water level could double the amount of undercut bank.
Similarly, the addition of a fallen log to either section could
3-16
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LEGEND
RAINBOW TROUT
BROWN TROUT
BROOK TROUT
15 20
TOTAL LENGTH (cm)
25
I
30
35
FIG. 3-3 LENGTH FREQUENCIES OF TROUT FROM THE DOG RIVER UPSTREAM
OF THE NORTHFIELD,VERMONT WPCP, NOVEMBER 1982
-------
TABLE 3-6. WEIGHTED PERCENTAGES OF HABITAT TYPE
IN FISH SAMPLING SECTIONS OF THE DOG RIVER,
NORTHFIELD, VERMONT
Habitat Type
Weighted Percentages of Total Area
Upstream of Downstream of
Northfield Northfield
WPCP WPCP a (t's)
SS (Shallow Slow)
SF (Shallow Fast)
ASA (Available
Spawning Area)
UB (Undercut Bank)
FD (Forest Debris)
RV (Riparian
Vegetation)
DS (Deep Slow)
DF (Deep Fast)
50
48
86
<1
<1
0
0
2
52
49
73
<1
2
6
<1
0
0.48
0.46
0.009
make a statistically significant, but not biologically important,
change in available forest debris (FD) cover.
Discussion
Chlorine disinfection influences public health and aquatic
biota. Public health can be adversely affected through
incomplete disinfection which could result in a health hazard
downstream of the sewage treatment plant. Conversely, aquatic
biota can be affected through overchlorination which can kill
aquatic organisms downstream. Consequently, chlorination must be
3-19
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monitored carefully to ensure that public health is protected
without any adverse affects on aquatic organisms.
Public Health. The Dog River, from the Northfield, VT,
WPCP to the confluence with the Winooski River is classified by
the Vermont Department of Water Resources as Class C — suitable
for recreational boating, irrigation, fishing and some industrial
uses. Class C waters are not suitable for public water supplies
or swimming. The Vermont Class C standard requires that fecal
coliform bacteria should be less than 1,000/100 ml. Because
fecal coliform results from this study are unreportable due to
growth of atypical colonies, it is unknown if this standard was
met downstream of the Northfield WPCP. Since the maximum total
coliform levels were 2,500 total coliforms/100 ml, (Station II-R)
it is possible that fecal coliform levels were less than
1,000/100 ml. This compliance may only occur during dry weather
conditions, since runoff, stormwater and combined sewer
discharges could drastically elevate in-stream bacterial levels
after rainfall.
The area upstream of the Northfield WPCP is Class B,
suitable for bathing, recreation, and only acceptable for public
water supply with filtration and disinfection. Total coliforms
in these waters should not exceed 500/100 ml and fecal coliforms
should not exceed 200/100 ml, yet this standard was not met for
total coliforms in two of the three stations in transect I, the
control. During the conclusion of these field studies, an active
3-20
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combined sewer overflow was found on the river about 300 m above
the Northfield WPCP. This combined sewer overflow was the most
probable cause for elevated coliform levels just above the
outfall resulting in violation of the Class B water quality
standards.
Fecal streptococci bacteria are promising organisms for
future use as indicators of fecal pollution. However, there is
no standard for fecal streptococci. The total coliform group
contains some organisms without sanitary significance (Geldreich
1970) and others that can reproduce in streams (Mechalas et al.
1972). Fecal coliforms have been correlated with total
coliforms, not pathogens (Mechalas et al. 1972). Consequently,
fecal streptococci bacteria are being evaluated as indicator
organisms.
None of the standard bacteriological indicators are
sufficient to assess the virological quality of fresh waters
(Payment et al. 1982). No correlation has been found between
presence of viruses and the presence of enteric indicators. The
presence of viruses, however, has been correlated with increased
turbidity (Payment et al. 1982). Thus, although the bacterial
indicators (in the absence of meaningful fecal coliform bacteria
data) appear to be within allowable standards, the potential
risks due to viruses are not known.
Rapid dilution can help protect public health by
dispersing pathogens to low concentrations. The estimate from
3-21
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this study of river flow in the Dog River, 0.52 m3/sec, was lower
than the flow recorded at the USGS gaging station (0.79 m3/sec)
downstream of the Northfield WPCP. At least one small tributary
enters the Dog River between the WPCP and the downstream USGS
gaging station. This may account for the differences in
estimates of river flow. The dilution estimate from this study
of 11:1, river water to effluent, is close to that of Pagel and
Langdon's (1981) estimate of 19:1 for the same site in July 1979.
Based on the results of this study, the public health
appears to be adequately protected by the Northfield WPCP. The
Dog River is shallow, would not be of suitable depth in most
locations for swimming, and is not used as a drinking supply
(Phillips 1982). These characteristics combined with a dilution
ratio of 11:1 and the performance of the Northfield WPCP should
provide adequate public health protection.
Seasonal disinfection could be considered for the
Northfield WPCP. This should be viewed as a cost cutting measure
only, and not a significant benefit to aquatic resources (Metcalf
& Eddy, Inc. 1982). Seasonal disinfection will not be beneficial
to aquatic organisms because any adverse impacts will resume when
disinfection starts. Seasonal disinfection could result in the
establishment of a balanced aquatic community in the winter, then
the annual disruption of this community in the spring when
disinfection resumes. Public health would not be adversely
affected by seasonal disinfection. The river downstream of the
3-22
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Northfield WPCP receives limited water contact or recreational
use during the winter.
Fisheries. Fisheries have been shown to be adversely
impacted below sewage outfalls (Tsai 1968, 1970, 1973). Chlorine
and turbidity cause reductions of diversity and abundance in both
fish and invertebrates below sewage outfalls. Tsai (1973)
reported an absence of brook and brown trout in waters below
sewage treatment plants when TRC levels exceeded 0.02 mg/1.
Sprague and Drury (1969) found rainbow trout avoided TRC
concentrations greater than 0.001 mg/1.
Pagel and Langdon (1981), based on Marcinko (1980), found
a slight decrease in trout populations below the Northfield WPCP
compared to upstream stations. They could not attribute all of
this decrease to changes in water quality. Natural population
variation and changes in habitat were probably factors
contributing to the decrease in trout population. This data also
showed a 30 percent increase in brown trout, less than 149 mm in
length, below the Northfield WPCP, but most trout were concen-
trated at the downstream edge of the sampling station below the
outfall (Marcinko 1980). These apparently aberrant findings were
attributed to the rapid dilution of chlorine in the Dog River.
In contrast, the present study documents a marked decrease
(two orders of magnitude) in downstream salmonid populations.
Relative C/f decreased from 0.39 salmonids/f upstream, to 0.001
salmonids/f downstream of the outfall. The reasons for the
3-23
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differences in fish populations are unclear. Stocking of rainbow
trout has not occurred in the Dog River for 21 years (Claussen
1982). There were few differences in habitat type between stream
sections. The upstream section contained a significantly greater
percentage of available spawning area (a (t's) = 0.009). There
was only a 13 percent difference in percentage of available
spawning area between the upstream and downstream fish sampling
sections but two orders of magnitude difference in trout
population size. This difference in available spawning area is
not great enough to account for the marked differences observed
in fish populations. Marcinko's (1980) observations of brown
trout is further evidence that trout habitat is not limiting
downstream from the outfall.
Except for TRC, water quality does not appear limiting for
salmonids. Un-ionized ammonia, calculated from total ammonia,
never approached the EPA water quality criterion of 0.02 mg/1
(U.S. EPA 1976) even at station II-M, 1.2 m below the outfall.
The high dissolved oxygen levels (8.3 to 10.1 mg/1) were not due
to a temporary phytoplankton bloom as evidenced by the low (1.5
mg/m3) chlorophyll a sample concentration, but were probably
caused by reaeration of the water as it passes through turbulent
shallow areas.
Chlorine concentrations decreased rapidly downstream from
the Northfield WPCP. Both physical (dilution, mixing) and
chemical (reaction, decay) processes are important relative to
3-24
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the aquatic fate of residual chlorine. For example, the dilution
factor calculated from the TRC data (Table 3-5) would show 14:1
(receiving water:effluent) downstream at Transect IV, when in
fact the measured dilution factor of 11:1 was obtained with flow-
rates. Thus the more rapid observed decrease in chlorine concen-
trations probably represented some chemical decay in addition to
the physical mixing and dilution.
Toxicity of TRC varies depending on which form of residual
chlorine is predominant (Metcalf & Eddy, Inc. 1982). The form of
chlorine measured during this study as TRC was primarily mono-
chloramine (NH2C1), a combined form of residual chlorine.
Monochloramine predominates in waters with a near neutral pH and
where ammonia concentrations are above naturally occurring levels
(Jolley and Carpenter 1982). Cairns and Conn (1979) conducted
monochloramine toxicity tests with juvenile rainbow trout (the
most sensitive life stage). The 96 hour LC50 values for rainbow
trout juveniles ranged from 0.03 to 0.09 mg/1 as TRC. Thus, the
areas of the Dog River which would be acutely toxic to the most
sensitive life stages of rainbow trout (based on the November
1982 data) would encompass an area approximately 50 m downstream
from the outfall (Figure 3-4). The zone of avoidance and poten-
tial chronic or long term toxicity can only be inferred. Marked
downstream reduction in trout population was noted as far as
160 m downstream of the outfall in November 1982. Thus,
3-25
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potential chronic effects may be noted at least as far as 160 m
downstream under low flow conditions (Figure 3-4).
A zone of passage for salmonids did not exist in the Dog
River near the Northfield WPCP. All three stations across
transect IV, 26 m downstream from the outfall, had TRC concen-
trations greater than the 0.05 mg/1 criterion for salmonid
passage recommended in Metcalf & Eddy (1982) (Figure 3-2).
Transects II and III had corridors of TRC < 0.05 mg/1, but by
transect IV the plume had spread out far enough to create a block
of TRC concentrations >0.05 mg/1. This agrees with the dye study
of the effluent which showed complete mixing of the effluent 30
to 35 m downstream of the outfall. TRC concentrations returned
to nondetectable levels 50 m downstream from the outfall (Table
3-4). The lack of a zone of passage in the Dog River may inter-
fere with seasonal movement of resident trout in response to
temperature gradients and population density. During low river
flow periods it may result in trapping of trout populations in an
unfavorable environment. However, the ruins of a small dam about
60m upstream from the most upstream fish sampling section (Figure
3-1) probably do not severely restrict passage by resident
salmonids.
Overchlorination could result in occasional incidents of
acute TRC toxicity extending 160m downstream from the outfall.
One of these incidents could kill fish eggs and larvae, destroy a
year class, drive adult fish away and result in an absence of
3-26
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STATION
R M L
I-i —20 m
FLOW
OUTFALL
0 m
NORTHFIELD
WPCP
50 m
[=~
100 m
LEGEND
SIGNIFICANT IMPACT
ON TROUT SURVIVAL
AND PASSAGE
SUSPECTED IMPACT
ON TROUT PRODUCTION
AND PASSAGE
UNKNOWN
160 m
FIG. 3-4 AREAS AFFECTED BY CHLORINATED EFFLUENT
IN THE DOG RIVER, NOVEMBER 1982
-------
fish until recolonization. An episode of overchlorination could
also kill stream invertebrates which are food for salmonids.
Salmonids may not repopulate the area .until the benthic
invertebrate community is reestablished. Pagel and Langdon
(1981) found a change in the benthic community below
the Northfield WPCP. Midges, mayflies, and caddisflies, which
are important food items for trout (Pennak 1978), were dominant
above the outfall, but aquatic worms and nematodes dominated
downstream (Pagel and Langdon 1981).
Occasional episodes of overchlorination are suspected to
have reduced salmonid populations below the Northfield WPCP,
although no violations of the 4 mg/1 TRC effluent limitation were
recorded at the Northfield WPCP in 1982. Such an episode could
be of relatively short duration but have long-lasting effects.
The November 1982 sampling period may have occurred just after a
period of overchlorination and the area had not been recoIonized.
Similarly, some unmeasured constituent of the effluent may be
adversely affecting the downstream area.
Overchlorination could occur at night when wastewater
flows drop, and chlorine is applied at the constant rate of 30
to 35 lbs/day. However, no TRC measurements of the effluent were
taken at night. Daytime TRC levels in the effluent reportedly
ranged from 2.7 to 3.6 mg/1 (Table 3-1), and was 0.5 mg/1 on
November 2, 1982 as measured by the operator with the DPD color
comparator method. Amperometric titration on the same date
3-29
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showed TRC levels of 1.9 mg/1 (Table 3-4) in the effluent,
indicating a potential problem at the treatment plant in the
methods used to measure TRC.
Better control of chlorination could be provided by 1) a
residual chlorine analyzer with a feedback control loop of
chlorination, 2) installation of a new rotameter in the
chlorinator to allow a lower minimum chlorination rate, 3) TRC
analysis during low flow periods using amperometric titration.
3-30
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LITERATURE CITED
American Public Health Association. 1976. Standard Methods for
the Examination of Water and Wastewater. Fourteenth Edition.
American Public Health Association, Washington, D.C. 1193 pp.
Boyer, M.C. 1964. Streamflow Measurement. Section 15 in
Handbook of Applied Hydrology V.T. Chow (Ed.). McGraw-Hill
Book Company, New York.
Claussen, J. 1982. Fisheries Biologist, Vermont Department of
Fish and Game. [Letter to M. J. McGinniss, Metcalf & Eddy,
Inc.] December 14, 1982.
Geldreich, E. E. 1970. Applying bacteriological parameters to
recreational water quality. Journal Amer. Water Works Assn.
61 :113-119.
Hebert, M. 1982. Superintendent, Village of Northfield WPCP,
[Telephone conversation with M. J. McGinniss, Metcalf & Eddy,
Inc.] October, 1982.
Jolley, R. L. and J. H. Carpenter. 1982. Aqueous Chemistry of
Chlorine: Chemistry Analysis, and Environmental Fate of
Reactive Oxidant Species. Oak Ridge National Laboratory,
ORNL/RM-7788 116pp.
Marcinko, M. 1980. A comparison of trout standing stock above
and below municipal wastewater treatment plant discharges in
four Vermont Streams. Vermont Fish and Game Department,
Technical Assistance Project FW-17-T., 13 pp.
Mechalas, B. J., U. U. Hevimian, L. A. Schinazi, and R. H.
Dudley. 1972. An Investigation Into Recreational Water Quality
Water Criteria Data Book, Vol. 4 U.S. Environmental
Protection Agency.
Metcalf & Eddy, Inc. 1981. Wastewater Engineering: Collection
and Pumping of Wastewater. McGraw-Hill, New York, 432 pp.
Metcalf & Eddy, Inc. 1982. Impacts of Wastewater Disinfection
Practices on Coldwater Fisheries (Draft). Prepared for U.S.
Environmental Protection Agency, Region I, Boston,
Massachusetts.
3-31
-------
Nolan, P. 1979. Acute toxic effects of chlorinated primary
sewage effluent on brook trout and brown trout. Manchester
Vermont - Battenkill River. U.S. Environmental Protection
Agency Region I, Boston, Massachusetts 23 pp.
Nolan, P. and A. Johnson. 1977. Chlorine toxicity study, Mad
River - Waterville Valley; July 30 - August 8, 1976, U.S.
Environmental Protection Agency Region I. Boston,
Massachusetts 48 pp.
Oswood, M. E. and W. E. Barber. 1982. Assessment of fish
habitat in streams: goals, constraints, and a new technique.
Fisheries 7 (4):8—11.
Pagel, C. W. and R. W. Langdon. 1981. A preliminary study of
the influence of chlorinated wastewater effluent on the
biological life of selected rivers and streams in Vermont.
State of Vermont Agency of Environmental Conservation,
Montpelier, Vermont, 96 pp.
Payment, P., M. Lemieux and M. Trudel. 1982. Bacteriological
and virological analysis of water from four fresh water
beaches. Water Research 16:939-943.
Pennak, R. W. 1978. Freshwater Invertebrates of the United
States. 2nd Ed. John Wiley & Sons, New York 803 pp.
Phillips, R. I. 1982. Environmental Engineer, Vermont
Department of Water Resources and Environmental Engineering
[Letter to K. Wood, U.S. EPA Region I] September 1982.
Sokal, R. R. and F. J. Rohlf. 1982. Biometry. Second Edition
W. H. Freeman and Company, San Francisco. 859 pp.
Sprague, J. B. and D. E. Drury. 1969. Avoidance reactions
to salmonid fish to representative pollutants. Pages 169-184
In: Advances in Water Pollution Research, Pergamon Press,
London.
Sugam, R. 1983. Chlorine analysis: Perspectives for
compliance monitoring. In Proceedings of the Fourth Conference
on Water Chlorination: Environmental Impact and Health Effects
Volume 4, Book 1. Eds. R.L. Jolley, W.A. Brungs, J.A. Cotruvo,
R.B. Cumming, J.S. Mattice, V.A. Jacobs. Ann Arbor Science,
Ann Arbor, MI. 811pp.
Tsai, C. 1968. Effects of chlorinated sewage effluents on
fishes in upper Patuxent River, Maryland. Chesapeake Sci.
9( 2):83-93.
3-32
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Tsai, C. 1970. Changes in fish populations and migration in
relation to increased sewage pollution in Little Patuxent
River, Maryland. Chesapeake Sci. 11(1):34—41.
Tsai, C. 1973. Water quality and fish life below sewage
outfalls. Trans. Amer. Fish. Soc. 102( 2): 282-292 .
U.S. Environmental Protection Agency. 1976. Quality Criteria
for Water. U.S. Environmental Protection Agency, Washington,
D.C. 255 pp.
U.S. Environmental Protection Agency. 1979. Methods for
Chemical Analysis of Water and Wastes. Environmental
Monitoring and Support Laboratory, Environmental Research
Center, Cincinnati, Ohio.
White, B. 1983. U.S. Geological Survey, Montpelier Vermont
Office, Final streamflow values for (gage 04287000) Dog River,
Northfield Falls, Vermont.
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CHAPTER 4
IMPACT OF CHLORINATED EFFLUENT ON TROOT
FISHERIES OF THE THIRD BRANCH OF THE
WHITE RIVER - A CASE STUDY
As a result of the preliminary field program on the Dog
River, a number of concerns were left unanswered. Based on the
review of the Northfield case study, the Technical Review Team
concluded that a more detailed scientific study was necessary to
assess the full applicability of CHAP. For example, the need was
seen for repetitive water quality sampling (over several days),
macrobenthic sampling to supplement the fisheries data, and for
additional downstream fish sampling sections. Thus, a second
case study was conducted to provide a more comprehensive
foundation for the CHAP procedure. A site was selected in the
White River basin in Vermont. This site was selected because it
affected self-sustaining trout populations and was reported to
support juvenile Atlantic salmon. The Third Branch of the White
River in Randolph, Vermont receives chlorinated secondary
effluent from the Village of Randolph WPCP. The Randolph WPCP
discharges an average wastewater flow of 0.3 mgd, with year round
disinfection. The Third Branch downstream from the Randolph WPCP
is Class C, suitable for recreation, irrigation and some
industrial uses (Table 4-1).
Prior to this study total residual chlorine measurements
downstream from the Randolph WPCP were not available and other
4-1
-------
TABLE 4-1. SUMMARY OF AVAILABLE BACKGROUND DATA FOR
THE RANDOLPH VERMONT CASE STUDY
DISCHARGE
NAME OF FACILITY: Village of Randolph, VT Water Pollution
Chlorine Plant
AVERAGE FLOW: 0.31 mgd - Extended Aeration Plant
TRC CONCN'S: Free Chlorine 0.2 to 0.78 mg/1 TRC 1.3 to 4.0 mg/1
OUTFALL TYPE: Streambank (no diffuser)
Summer 2.5 mg/1
pH & NH3 CONCN's: pH 5.6 - 7.2 TKN Winter 14 mg/1
RECEIVING WATER
NAME OF STREAM AND MAJOR DRAINAGE BASIN: Third Branch of the
White River; Connecticut River Drainage Basin
WATER QUALITY CLASSIFICATION AND STANDARDS: The Third Branch is
Class C from the discharge to Smith Brook (about 1.9 kilometers
downstream) where the classification returns to Class B.
TYPE OF FISHERY: Primarily a put and take rainbow trout
fishery. Area presently utilized by juvenile Atlantic salmon as
nursery grounds and projected as corridor for spawning Atlantic
salmon adults as obstructions are removed downstream. See Page 1
and Langdon (1981) for trout population data.
FLOW DATA: Low flow July-September 7Q10 - 2.3 cfs
pH & NH3 CONCN's: no data
SUMMERTIME TEMPERATURES: 18-23 deg. C
PUBLIC HEALTH
PRIVATE AND PUBLIC
WATER SUPPLIES: None known to Vermont Agency of Environmental
Conservation
CONTACT USES: No formal swimming or boating facilities, but
occasional swimming, boating and fishing.
Source: Phillips (1982).
4-2
-------
water quality data were lacking (Table 4-1) but some macrobenthic
and fisheries data were available in previous reports (Marcinko
1980; Pagel and Langdon 1981). Consequently, implementation of
the Coldwater Fisheries Hazard Analysis Procedure (CHAP) at the
Randolph WPCP required the collection of water and effluent
quality data, streamflow measurements, macrobenthic and fisheries
data.
Field investigations were conducted from 18 to 23 July
1983 during a low river flow period. Agencies that assisted with
the field investigations included the U.S. Environmental
Protection Agency, Region I, (J.S. Fish & Wildlife Service and the
Vermont Fish and Game Department.
Materials and Methods
Treatment Plant Description. Wastewater from the Village
of Randolph, Vermont is treated at an extended aeration plant.
The plant is designed to treat an average daily flow of 0.32 mgd
and a peak flow of 1.14 mgd. Flows in excess of 1.14 mgd bypass
the treatment facilities and are directed to the chlorine contact
tank for disinfection. Both treated and bypassed flows are
disinfected prior to discharge (Dubois and King 1981). At
present, the average flow is 0.289 mgd and the effluent
concentrations of BOD and suspended solids based on plant
operating records are typically well below the NPDES permit
limitations.
4-3
-------
The wastewater treatment system consists of a coarse bar
rack, grit removal chamber, comminutor, a Parshall flame to
measure influent flows, two square aeration tanks equipped with
mechanical surface aerators, two rectangular clarifiers and the
chlorine contact tank. Solids carry over from the clarifiers to
the contact tank is a frequent problem due to the poor settling
characteristics of the floe particles and resuspension by
currents in the clarifier (Dubois and King 1981). These solids
typically settle and accumulate in the chlorine contact tanks.
The solids contained in bypass flows also tend to settle in the
chlorine contact tanks.
In addition to effluent chlorination for disinfection, in-
place piping systems permit the addition of chlorine to the
influent bypass channel (pre-chlorination) as well as to the
return sludge line for control of sludge bulking.
The chlorination system was designed with a capacity to
apply chlorine at a maximum rate of 400 lb/day. Although five
150-lb chlorine cylinders could be connected, normally only three
cylinders are used. Chlorine is withdrawn from the cylinders,
passes through a gas pressure reducing valve to reduce the
pressure to 25 psi and is injected into potable water in one of
two chlorinators. Depending on the time of year and wastewater
flowrate the present dry weather chlorine use varies from 8 to 26
lb/day, with a reported average use of 16 lb/day. During the
past year, the average chlorine dose was approximately 6 mg/1.
-------
The operator has replaced the 400-lb chlorinator rotameters with
50-lb rotameters to more accurately control the chlorine dosage.
Due to accumulated grit the location of the pre-
chlorination diffuser in the by-pass channel could not be
determined through visual inspection and in any case, it is
seldom used. In addition, although the treatment plant plans
indicate that chlorine solution is added to the clarifier
effluent at a manhole located upstream of the chlorine contact
tank, analysis of wastewater samples withdrawn from that manhole
indicated only trace quantities of chlorine. Therefore, the
actual point of chlorine addition must be somewhere downstream of
the manhole.
The chlorinated wastewater enters the contact tank through
an inlet structure with a 90 degree elbow to minimize horizontal
velocity (and possible short-circuiting). The contact tank is
normally operated as a single tank, although during cleaning or
maintenance, it can be converted to two tanks by closing the
central slide gate. The channel baffling provides a length-to-
width ratio in the contact tank of 18:1 (or 9:1 with only one
tank in operation) which is significantly less than the present-
day design standards of 40:1. The contact tank was designed to
provide a 15-minute contact time for a peak flowrate (both
treated and bypassed flows) of 2.8 mgd (Dubois and King 1981).
A dye test using Rhodamine WT dye was conducted on
July 19, 1983 when the average flowrate was 0.34 mgd. At this
4-5
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flowrate the theoretical contact time is about two hours.
The dye solution was introduced at the manhole upstream of the
contact tanks. About 13 minutes after addition, the first of the
dye reached the end of the first channel and about 45 minutes
after addition, dye began to appear in the effluent. The last of
the dye cleared the tank about three hours after it was
introduced. Most of the dye stayed on the surface and dead spots
(no flow or eddies) were observed in corners.
The Randolph, VT WPCP operator collects effluent samples
on a daily basis for chlorine residual analysis using the
amperometric titration procedure. The discharge permit specifies
that the effluent chlorine residual concentration should not
exceed 4.0 mg/1. Effluent total residual chlorine concentrations
typically range from 0.5 to 4 mg/1 based on inspection of the
past 12 months of records.
Although plant records documented the chlorination system
had reliably functioned over the past ten years, a failure
occurred in a chlorine gas pressure reducing valve early on the
first day of the present study. Replacement parts were installed
at 1400 hours two days later. Consequently, the environmental
sampling efforts downstream of the WPCP outfall were postponed
until eight hours after normal chlorine residuals were measured
in the effluent.
Water Quality and Effluent Sampling. Preliminary total
residual chlorine (TRC) sampling was conducted to establish
4-6
-------
locations of six water quality transects, with three sampling
stations per transect. Preliminary water quality sampling was
conducted on the effluent, and areas upstream ( 600 m) , and
downstream (0.5 and 14.5 m) of the outfall. A fluorescent dye
(Rhodamine WT) was added to the effluent to visually locate the
discharge plume as an aid to station location and to determine
where the effluent was completely mixed. TRC samples were
analyzed within ten minutes of collection with a Fisher
Scientific Model 393 amperometric titrator. TRC detection limits
for this study were established at 0.02 mg/1.
Locations of water quality sampling transects are
presented in Figure 4-1 and Table 4-2. Transect I, the control,
was located 600m upstream of the outfall where TRC levels were
<0.02 mg/1 (see Results). An additional transect, AB, was
located in Ayers Brook (Figure 4-1) 400m upstream of its
confluence with the Third Branch. Sampling transects were
identified by Roman numerals and the three stations within each
transect by capital letters. Station L was located near the left
bank, M in the middle and Station R near the right bank, facing
downstream. Only Stations L and R were sampled in Transect AB.
At each station TRC, total coliform, fecal coliform,
alkalinity, NH3-N, temperature, dissolved oxygen and pH
were determined on days 4, 5, and 6, except for the station in
Ayers Brook which was only sampled on day 6. TRC concentrations
were measured within ten minutes of collection. However, TRC was
4-7
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TABLE
THIRD
4-2. WATER QUALITY SAMPLING TRANSECTS ON THE
BRANCH OF THE WHITE RIVER, RANDOLPH, VERMONT
Transect
Location
Distance from WPCP
outfall (m)
I
Upstream of WPCP
600
II
Just downstream from outfall
0.5
III
Downstream from outfall
14.5
IV
Middle of fish sampling
Section B
150
V
Upstream of Fish Sampling
Section C
450
VI
Upstream End of Fish Sampling
Section D
890
AB
Ayers Brook, 400m upstream of
confluence with Third Branch
-
not sampled at transect VI because it was not possible to meet
this time limitations due to logistical constraints. Alkalinity
and ammonia samples (acid preservative) were kept refrigerated
prior to analysis. Alkalinity was determined by potentiometric
titration to a pH = 4.5 and reported as mg/1 as CaCOj (APHA
1976). Ammonia nitrogen was determined by the acidimetric method
following alkaline distillation and was reported as mg/1 ammonia
nitrogen with a detection limit of 0.1 mg/1 (APHA 1976). Total
and fecal coliform bacteria samples were collected in sterile
"whirl-pak" containers that included a dechlorinating agent.
Bacteria samples were kept refrigerated until delivered to the
4-8
-------
$
0 200
LEGEND
I H WATER QUALITY TRANSECTS
FISH AND MACROINVERTEBRATE
SCALE IN WITTERS SAMPLING SECTIONS
FIG. 4-1 SAMPLING LOCATIONS ON THE THIRD BRANCH
OF THE WHITE RIVER, RANDOLPH, VERMONT, JULY 1983
-------
laboratory where coliform assays were performed by the membrane
filter technique (APHA 1976). Total coliform assays used the
M-Endo Agar media and fecal coliform assays the MF-C media
ampules. Coliform bacteria results were expressed as numbers per
100 ml. Temperature, dissolved oxygen and pH were determined on-
site using a Hydrolab 4041 water quality sampler.
Chlorinated effluent samples were collected on days 4, 5
and 6 for analysis of TRC, NH3-N, alkalinity and total and fecal
coliforms. Samples of unchlorinated effluent were collected on
days 2, 4 and 5 for analysis of chlorine demand using a
colorimetric method (APHA 1976). Chlorine demand analyses were
conducted at 22 deg C. using a commercial hypochlorite solution
and chlorine demand residual analyses were conducted with the
ferrous-DPD titrimetric method (APHA 1976). Chlorine demand was
computed as the difference between the applied dosage and the
total chlorine residual after a contact time of 15 minutes.
A nocturnal, low effluent flow evaluation of TRC
concentrations in the effluent and Third Branch was conducted on
days 3 and 4. Effluent samples from the exit of the chlorine
contact chamber, and river water from stations II-L and III-L
were collected hourly from 2330 hours on day 3 to 1100 hours on
day 4. Samples were analyzed for TRC within five minutes by
amperometric titration. Effluent flow was monitored during
sample collection. Effluent flow measurements were taken from
the recording chart in the operations building which operates
4-11.
-------
from a float-actuated transmitter located at the V-notch weir of
the chlorine contact tank.
Streamflow Measurements. Streamflow measurements were
taken on days 3, 4, 5 and 6 at a location 51 m downstream from
the WPCP outfall using a Marsh-McBirney Model 201 water velocity
meter. Streamflow measurements were made by determining mean
velocity at 0.6 the depth in a number of partial sections across
the river. Total streamflow was computed as the sum of the
discharges from the partial sections (Boyer 1964).
Fisheries Sampling. Four sections of the river were
assessed for salmonid populations by electrofishing (Table 4-3).
Stream sections were chosen for their similarity of habitat using
a preliminary habitat checklist. Quantitative trout population
estimates in each sampling section were made with the method of
Seber and Le Cren (1967), where the population size is estimated
from two successive electrofishing catches. A direct current
electrofisher was used and blocking seines (except at the
downstream end of section D) assured that sampling was conducted
on a closed population. The electrofishing effort was the same
for each of the catches.
Salmonids collected after both passes were identified,
weighed to the nearest gram, measured for total length to the
nearest millimeter and released. Non-salmonid fish species
composition was noted but these fish were not enumerated.
Population estimates and 95 percent confidence limits for each
4-12
-------
TABLE 4-3. FISH SAMPLING SECTIONS IN THE
THIRD BRANCH OF THE WHITE RIVER
*
Distance from
Section Location Length (m) WPCP outfall (m)
A
Upstream
from WPCP
151
650
B
Downstream
from WPCP
96
93
C
Downstream
from WPCP
58
460
D
Downstream
from WPCP
80
890
* From outfall to upstream end of section.
salmonid species were calculated and presented as numbers of fish
per hectare and kilograms of fish per hectare. Condition factors
(K1 = 100W/L*3) were calculated for each salmonid species captured
in the first pass through sections A and B (Figure 4-1), where
K1 = condition factor, W = observed total weight, L = observed
total length, and b = the slope of the regression line of Log W
on Log L (Bagenal and Tesch 1978). This condition factor is
recommended when the range of fish lengths is large (Bagenal and
Tesch 1978). Condition factors are used to compare the condition
of fish and are based on the assumption that heavier fish of a
certain length are in better condition. Typical ranges in the
value of K1 cannot be listed because condition factors are
location and species-dependent.
4-13
-------
Salmonid habitat mapping. Habitat was mapped in each fish
sampling section to differentiate habitat effects from chlori-
nated effluent effects. The mapping technique involved the con-
struction of diagrammatic maps to scale of each sampling section
showing stream habitat features (Oswood and Barber 1982). Each
section was divided into 6-m or 12-m segments for assessment of:
river depth, water velocity, forest debris, undercut bank, rip-
arian vegetation and available spawning area (see Table 3-3 for
habitat definitions). Weighted mean percentages of habitat type
in each section were calculated from percentage of habitat type
in each segment, weighted by the segment area.
Macrobenthic sampling. Three replicate inacrobenthic
invertebrate samples were collected in riffle sites of the four
fish sampling sections with a Surber sampler (Lind 1974).
Each replicate sample consisted of a total of two square
feet (0.18 m'') of riffle area bottom. The bottom substrate was
disturbed to a depth of 10 to 15 cm and all rocks larger than 3.5
cm were scrubbed free of macrobenthos with a small hand brush.
Samples were preserved in 10 percent formalin in the field.
Preserved samples were processed and analyzed for species
composition, numerical abundance and species diversity. Species
diversity was calculated for the lowest taxonomic level in each
sample with Simpsons index (Simpson 1949). This index, D, is
S 2
calculated as: 1 - I pi , where p^ is the portion of
i=1
individuals of the ith species, and S is the number of species.
4-14
-------
D is the probability that two randomly selected individuals will
not belong to the same species (Green 1979).
Statistical Analyses. Water quality and macrobenthic
results were statistically analyzed using the nonparametric
Kruskal-Wallis test at a significance level of a = 0.05 (Sokal
and Rohlf 1982). If significant differences between treatments
were found, a distribution-free multiple comparisons test based
on rank sums was used to identify which treatments differ from
one another (Hollander and Wolfe 1973). Nonparametric tests were
used because some water quality parameter results were equal to
or less than levels of detection. Nonparametric tests require
the rank of the data, and make no assumptions about their
distribution.
Water quality results were analyzed with transects as
treatments, and with day of the study as treatments. When
transects were treatments, data from all days were pooled for
each transect. When days were treatments, data from all
transects were pooled for each day.
Results
WPCP Operational Data. Operational data obtained during
the study period at the Randolph WPCP are summarized in Table
4-4. During this period the plant flowrate and chlorine usage
were somewhat below the reported average values (see Materials
and Methods). However, little rain had fallen in preceding weeks
so lower groundwater levels may have decreased infiltration rates
4-15
-------
TABLE 4-4. SELECTED RANDOLPH, VERMONT
WPCP OPERATIONAL DATA, 18-23 JULY 1983
Wastewater
Flow, mgd
pH Pounds
Day
Influent
Effluent
Influent Effluent chlorine used
1
0.214
0. 197
7.4 6.7 8
2
0.227
0. 199
7.3 6.8 0*
3
0.233
0.202
7.5 6.7 0*
4
0.225
0. 199
7.3 6.7 10
5
0.254
0.229
7.5 6.8 9
6
0.230
0.209
12
* See
Materials
and Methods
for discussion of chlorination system
failure.
Source: Randolph WPCP Operating Records
and consequently decreased wastewater flowrates. Because the
chlorine requirement typically decreases with decreasing flow-
rates, the relatively low chlorine usage was probably related to
the low wastewater flows.
Water quality and effluent sampling. Preliminary TRC
sampling indicated that TRC levels were below levels of detection
(<0.02 mg/1) 600 m upstream of the outfall, 0.68 mg/1 0.5 m
downstream of the outfall and 0.05 mg/1 14.5 m downstream of the
outfall. Qualitative observation of the rhodamine dye plume
indicated that the effluent was completely mixed with receiving
waters about 50 m downstream of the outfall.
Total residual chlorine levels in the Third Branch ranged
from a high of 0.18 mg/1 near the outfall to <0.02 mg/1
4-16
-------
(Table 4-5, Figure 4-2). TRC levels did not vary significantly
over the three samplings dates (H = 0.91, a (H) >0.975) but did
vary significantly between transects (H = 32.7, a (H) < 0.005).
Transects I and V had significantly lower levels of TRC
(Table 4-6).
No significant differences (Table 4-6) in total and fecal
coliform levels between transects in the Third Branch were
observed over the three day sampling period (total coliforms: H =
6.48, 0.5> a (H)>0.1; fecal coliforms: H = 0.331, a (H)>0.995).
Levels of total and fecal coliforms found in Ayers Brook, tran-
sect AB, were within the range of values observed at transect I,
the control. However significant differences were observed be-
tween days (total coliforms: H = 26.74, a (H)<0.005; fecal coli-
forms; H = 47.83, a (H) <0.005). Further analysis indicated that
total coliform levels in the Third Branch were significantly
lower on day 4, and there were no differences between days 5
and 6. Fecal coliform levels were significantly different on all
days, with day 5 having the highest levels followed by days 6 and
4 (Table 4-6).
No significant differences in alkalinity levels were found
between days (H = 0.975, a (H) >0.995). Alkalinity was found to
vary significantly between transects (H = 42.73, a (H)<0.005).
Transects V, VI and II had significantly greater alkalinity than
the other stations. No significant difference were found between
4-17
-------
TABLE 4-5. WATER QUALITY RESULTS FROM THE THIRD BRANCH OF THE WHITE RIVER, RANDOLPH VERMONT, JULY 1983
Total
Fecal
Total Residual
Parameter
coli forms
coli forms
nh3-n
Alkalinity
Chlorine
Unit
No/100
ml
No/100 ml
mg/1
mg/1
mg/1
Station
*
L
M
R
L
M
R
L
M
R
L
M
R
L
M
R
DAY
TRANSECTS
4
I
500
600
200
8
34
10
<
0.1
<
0.1
<
0.1
33.6
34.6
36.7
<
0.02
< 0.02
<
0.02
II
600
900
400
12
5
38
<
0.1
<
0.1
<
0.1
40.9
38.8
37.8
0.09
0.06
0.03
III
300
300
100
15
12
15
<
0.1
<
0.1
<
0.1
42 .6
38 .6
38.6
0.03
0.03
0.04
IV
800
400
500
0
16
0
<
0.1
<
0.1
<
0.1
39.9
39.9
39.9
0.02
0.03
0.02
V
1000
200
100
7
0
3
<
0.1
<
0.1
<
0.1
64.0
64.0
65.1
<
0.02
< 0.02
<
0.02
VI
900
400
200
18
18
1
0.18
<
0.1
0.12
65.1
65.1
65.1
5
I
1000
2 400
2800
301
28 3
319
<
0.1
<
0.1
<
0.1
33.5
33.5
35.5
<
0.02
< 0.02
<
0.02
II
3100
2200
1600
319
46 3
359
<
0.1
<
0 .1
<
0.1
45.7
41.6
39.6
0.18
0.0 4
0.06
III
2200
2600
2500
338
39 4
29 0
<
0.1
<
0.1
<
0.1
42.6
38.6
38 .6
0.03
< 0.02
0.06
IV
1700
1800
1900
322
305
235
<
0.1
<
0.1
<
0 .1
42.6
39.6
40.6
0.03
0.08
0.02
V
300
CG
CG
161
147
169
<
0.1
<
0.1
<
0.1
68 .0
68 .0
69 .0
<
0.02
< 0.02
<
0.02
VI
800
1 400
500
19 4
150
162
<
0.1
<
0.1
<
0.1
67.0
67 .0
68.0
6
I
1000
1000
1200
93
134
132
<
0.1
<
0.1
<
0.1
34.5
34.5
35.6
<
0.02
< 0.02
<
0.02
II
CG
2300
4200
1 44
127
91
<
0.1
<
0.1
<
0.1
52.8
41 .6
37.5
0.17
0.03
0.04
III
2100
1900
4800
97
116
85
<
0.1
<
0.1
<
0.1
40 .6
37 .5
39 .6
0.06
0.05
0.03
IV
1200
1500
1500
78
73
92
<
0.1
<
0.1
<
0.1
39.6
39.6
38.6
0.03
0.0 4
0.03
V
1200
400
CG
65
77
53
<
0.1
<
0.1
<
0.1
66 .0
66 .0
65.6
<
0.02
< 0.02
<
0.02
VI
500
500
1100
75
85
1 46
<
0.1
<
0.1
<
0.1
66.0
65.0
68 .0
NS
NS
NS
AB
NS
800
NS
NS
275
NS
NS
0.05
NS
NS
110
NS
NS
NS
NS
L = left third; M = middle third; R = right third of river facing downstream
@ See Figure 4-1 for station locations
CG = confluent growth
NS = Not sampled
-------
0.15 -
A 22 July 1983
\ ®
/ /
\-v / \
\ v.
/ /
/ /
/ /
\ / N . \
, \
I E HI ET Y
TRANSECT
LEGEND
LEFT
MIDDLE
RIGHT
FACING
DOWNSTREAM
FIG. 4-2 TOTAL RESIDUAL CHLORINE (TRC) CONCENTRATIONS
MEASURED IN THE THIRD BRANCH OF THE WHITE RIVER, JULY 1983
-------
TABLE 4-6. STATISTICAL ANALYSIS OF WATER QUALITY
DATA FROM THE THIRD BRANCH OF THE WHITE RIVER
Parameter
Differences
by day
Differences^
by transect
Total Coliforms
AAA
No significant
differences
Fecal Coliforms
No significant
differences
Alkalinity
No significant
differences
I III IV II
V VI
TRC
No significant
differences
I V IV III
II
* Any two values connected by the same line are not
significantly different (a = 0.05).
transects I, III, IV, and II (Table 4-6). The highest levels of
alkalinity were found in Ayers Brook, transect AB.
Ammonia nitrogen concentrations were generally less than
0.1 mg/1 at all stations, except stations VI-L and VI-R on day 4,
and transect AB on day 6 when concentrations were 0.18 mg/1, 0.12
mg/1, and 0.05 mg/1 respectively. These total NH3-N concentra-
tions correspond to toxic un-ionized NH3-N concentrations of
0.002 mg/1 and 0.001 mg/1, respectively (U.S. EPA 1976).
Temperature, dissolved oxygen, dissolved oxygen percent
saturation and pH from the six water quality transects in the
Third Branch, and transect AB showed little variation during the
study period (Table 4-7). Temperature ranged 4.5 deg. C, from
16.1 in transect I to 20.6 deg. C in transect VI. Dissolved
oxygen only ranged 1.9 mg/1 from 6.2 mg/1 in transects III, IV,
4-21
-------
TABLE 4-7. RANGES OF TEMPERATURE, DISSOLVED OXYGEN,
DISSOLVED OXYGEN SATURATION AND pH
IN THE THIRD BRANCH OF THE WHITE RIVER
Transect
Temperature
(deg. C)
Dissolved
oxygen
(mg/1)
Dissolved
oxygen
saturation (%)
PH
I
16.1-17.0
7.0-8.1
75-85
6.2-6.6
II
16.4-17.4
6.3-7.8
68-82
6.6-7.2
III
16.4-18.0
6.2-7.9
68-84
6.6-7.0
IV
17.0-18.1
6.2-8.0
68-87
6.4-7.0
V
17.9-18.7
6.2-7.8
70-87
6.7-7.4
VI
18.2-20.6
6.4-8.0
73-90
6.9-7.5
AB
17.3-17.4
7.7*
82
7.9-8.0
* Same value obtained at left and right bank station.
and V, to 8.1 mg/1 in transect I. Dissolved oxygen saturation
levels ranged from 68 to 90 percent. Levels of pH varied from
6.2 in transect I, to 7.5 in transect VI, downstream from the
WPCP and confluence with Ayers Brook (See Figure 4-1).
Temperature and dissolved oxygen levels in Ayers Brook were
comparable with those of the Third Branch of the White River.
Higher levels of pH (7.9 to 8.0) were noted in Ayers Brook than
in the Third Branch.
TRC levels, total and fecal coliforms, and alkalinity, in
the chlorinated effluent increased during the study period and
reached a maximum on day 6 (Table 4-8). Effluent chlorine demand
was analyzed on four samples of unchlorinated effluent, with two
4-22
-------
TABLE 4-8. CHLORINATED EFFLUENT QUALITY RESULTS
FOR THE RANDOLPH WPCP
Total Fecal
TRC coliforms coliforms NH-^-N, Alkalinity
Day
(mg/1)
(No/100 ml)
(No/100 ml)
(mg/1)
(mg/1)
4
0.62
14
0
<0.1
73.5
5
0.67
128
2
<0.1
92.4
6
0.82
6400
16
<0.1
94.4
samples collected on day 2 and one sample each collected on days
4 and 5. At an applied dosage of 6.0 mg/1 (representing a
typical dosage at the plant), the chlorine demand ranged from 3.5
to 5.4 mg/1 and the breakpoint concentration ranged from 8 to 17
mg/1. The breakpoint is the point at which further chlorine
additions exist as free chlorine (Jolley and Carpenter 1982).
The highest break point concentration was determined on the Day 4
sample and the greatest demand associated with a dose of 6.0 mg/1
was computed for the Day 4 sample as well as the afternoon sample
collected on Day 1 . Levels of NH3-N remained below levels of
detection on all three days. Low effluent flow period TRC
results are shown in Figure 4-3. Effluent TRC, TRC levels at
station II-L (0.5 m downstream from the outfall) and effluent
flow showed similar trends. TRC levels in the effluent and
station II-L were at their lowest from 0200 to 0500 hours when
effluent flow was lowest. The high effluent TRC levels from 2300
to 0200 hours resulted from adjustments to the chlorination
4-23
-------
system after repairs (See Materials and Methods, WPCP
characteristics).
Stream flow. Stream flow dropped from 9.2 mgd on 20 July
to 8.1 mgd on 23 July while WPCP flow, measured at the same time
varied from 0.21 mgd to 0.34 mgd (Table 4-9). These flows
resulted in effluent dilution factors that ranged from 43:1 to
varied from 0.21 mgd to 0.34 mgd (Table 4-9). These flows
resulted in effluent dilution factors that ranged from 43:1 to
23:1 for this low river flow period. Rainfall during the study
period was 5.0 mm on 22 July.
Fisheries. Three species of trout, three species of
minnows, two species of suckers and one sculpin species were
captured in the Third Branch (Table 4-10). Estimates of trout
population and biomass and their 95 percent confidence intervals
provide a comparison of species composition and abundance between
transects (Figures 4-4, 4-5). Rainbow trout were the most
abundant (number/hectare) salmonid captured with peak abundance
occurring in section B, 92.5 m downstream from the WPCP
outfall. Brown trout were the second most abundant salmonid with
peak abundance in section D, 890 m downstream from the outfall.
Brook trout were the least abundant salmonid captured with peak
abundance in section A, 650 m upstream from the outfall.
As shown in Figure 4-4 estimates of brown trout abundance
for sections B, C, and D were within the 95 percent confidence
interval for the estimate of brown trout abundance in the
4-24
-------
4 0
o>
E
DC
0
—I
1
O
_l
<
Z)
a
in
LLI
QC
3.0
2.0
<
o 10
2200
2400
200
0400 0600
TIME, HOURS
0800
1000
1200
FIG. 4 3 SIMULTANEOUS MEASUREMENTS OF EFFLUENT TRC AND FLOW,
AND TRC AT STATION II-L OVER A 12 HOUR PERIOD
-------
TABLE 4-9. FLOW IN THE THIRD BRANCH OF THE
WHITE RIVER AND AT THE RANDOLPH WPCP, July 1983
Date
(Time)
EDT
River Flow
downstream
from WPCP
mgd (mVs)
WPCP flow
mgd(m3/s)
Dilutiog
Factor
20 July
(0730)
9.2 (0.40)
0.21 (0.01)
43:1
21 July
(1100)
7.8 (0.34)
0.28 (0.01)
27:1
22 July
(1200)
8.2 (0.36)
0.34 (0.01)
23: 1
23 July
(1200)
8.1 (0.36)
0.21 (0.01)
37: 1
* (River flow-WPCP flow)/WPCP flow.
TABLE 4-10. FISH CAPTURED BY ELECTROFISHING IN
THE THIRD BRANCH OF THE WHITE RIVER, JULY 1983
Common Name Scientific Name
rainbow trout Salmo gairdneri
brook trout Salvelinus fontinalis
brown trout Salmo trutta
common shiner Notropis cornutus
creek chub Semotilus at romaculatus
fallfish Semotilus corporal is
blacknose dace Rhinichthys attratulus
longnose dace Rhinichthys cataractae
white sucker Catostomus commersoni
longnose sucker Catostomus catostomus
slimy sculpin Cottus cognatus
4-27
-------
control, section A. Rainbow trout abundance population estimates
in section B were within the 95 percent confidence interval for
the estimate in section A. Sections C and D had similar rainbow
trout populations estimates, but lower than sections A and B.
Brook trout population estimates for sections C and D were within
each others 95 percent confidence interval, and well below the
lower than 95 percent confidence interval for A. Population
estimates were not possible for brook trout in section B because
equal numbers of fish (6) were captured on the first and second
electrofishing passes.
Biomass estimates of rainbow trout showed similar trends
as population estimates with rainbow trout having the greatest
salmonid biomass (kg/hectare) with peak biomass in section B
(Figure 4-5). Brook trout biomass estimates showed the same
trend between sections as population estimates with greatest
biomass in section A, the control. Unlike the population
estimates, brown trout biomass was smallest among salmonids with
the greatest biomass in section B. Biomass estimates were not
possible for brown trout in section A, and brook trout in section
B because the second pass through the section yielded trout
biomass greater than the first pass. This indicates either
different sampling effort between passes or selection by the
sampling gear (electroshocking) for smaller fish on the first
pass.
4-28
-------
600
BROWN TROUT
400 -
200 -
1000 -i
800 -
LU
CC
<
h-
O
LU
^ 600
QC
111
CD
400 -
200 -
{
RAINBOW TROUT
MEAN
I
LEGEND
95% CONFIDENCE
INTERVAL
400
200 -
BROOK TROUT
n I i r-
A I B C
WPCP
I
SECTION
FIG. 4-4 POPULATION ESTIMATES OF TROUT FROM FOUR SECTIONS
OF THE THIRD BRANCH OF THE WHITE RIVER, JULY 1983
-------
4.0 -r
BROWN TROUT
2.P
~i I r
25 -1
RAINBOW TROUT
20 -
1
MEAN
II
LEGEND
95% CONFIDENCE
INTERVAL
"" f ""
A | B
WPCP
BROOK TROUT
c
~r
D
SECTION
FIG. 4-5 BIOMASS OF TROUT FROM FOUR SECTIONS OF THE
THIRD BRANCH OF THE WHITE RIVER, JULY 1983
-------
Population estimates (trout/hectare) of all trout were
fairly uniform between sections, and the population estimate for
section B was within the 95 percent confidence interval for the
population estimate in section A (Figure 4-6). The upper bound
of the 95 percent confidence interval for trout population in
section D overlapped the lower bound of the same confidence
interval in section A. Section C had the lowest trout population
estimate. Biomass estimates (kg/hectare) showed the same trend
between sections A and B, with transects C and D having much
lower biomass estimates (Figure 4-6).
Length frequencies for all trout captured in the four fish
sampling sections indicated a decrease in the frequency of age 1+
trout (greater than 17.5 cm total length) in sections C and D
(Figure 4-7). Sections A and B had similar distribution of age 0
(2.5 cm to 7.5 cm total length), age 1 (7.5 cm to 17.5 cm total
length), and other than age 1 trout.
Condition factors were used to compare the well being or
health of fish, based on the assumption that heavier fish of a
given length are in better condition (Bagenal and Tesch 1978).
Chronic effects due to the chlorinated effluent could appear as
decreased condition factors in the trout from transect B,
compared to the upstream control. Condition factors calculated
for trout in sections A and B indicated that fish were in better
condition downstream from the outfall in section B than in
section A 650 m above the treatment plant (Table 4-11). This
4-33
-------
analysis assumes that salmonids are territorial and will remain
in an area long enough for chronic effects to influence the
conditon of the fish as measured by a ratio of weight to length.
TABLE 4-11. CONDITION FACTORS OF TROUT CAPTURED IN SECTIONS
A AND B ON THE THIRD BRANCH OF THE WHITE RIVER
Condition factor K1 x 10~3
Brown Rainbow Brook
Section trout trout trout
A 4.9 1.7 1.1
B 5.5 1.9 1.7
Habitat Mapping. Habitat mapping results indicated
obvious habitat differences between fish sampling sections
despite efforts to minimize these differences (Table 4-12).
Oswood and Barber (1982) found trout populations best correlated
with forest debris, deep fast, and riparian vegetation. The
electrofishing observations of this study indicate that most
trout were captured from deep slow habitat. For these reasons
section A was considered to have the best trout habitat followed
in order by sections B, D, and C.
Macrobenthos. The average macrobenthic species diversity
index (D) (Table 4-13) is the mean of the three separate
diversity index values calculated for each replicate sample (Data
for each sample are tabulated in Appendix D). Distribution-free
multiple range testing of the species diversity indices
4-34
-------
2000
40 -i
uj
CC
<
I—
a
LLI
X
<
cc
(D
O
1
20 -
"" f r
A | B
WPCP
SECTION
LEGEND
MEAN
95% CONFIDENCE
INTERVAL
FIG. 4-6 ABUNDANCE AND BIOMASS OF ALL TROUT FROM FOUR
SECTIONS OF THE THIRD BRANCH OF THE WHITE RIVER, JULY 1983
-------
15 -i
10-
SECTION A
TOTAL AREA = 1,840 m5
ml
m
10 T
5 -
>
o 0-
z
111
D
a
ID
GC 10"|
LL
5-
m a
SECTION B
TOTAL AREA = 1,022 m2
M-
SECTION C
TOTAL AREA = 894 m2
10t
J1
1
SECTION D
TOTAL AREA = 1,026 m"
~1
20
ns
—r~
25
"I
30
TOTAL LENGTH (cm)
LEGEND
I I BROWN TROUT
BROOK TROUT
RAINBOW TROUT
FIG. 4-7 LENGTH FREQUENCIES OF ALL TROUT FROM THE FOUR
FISH SAMPLING SECTIONS ON THE THIRD BRANCH OF THE
WHITE RIVER, JULY 1983
-------
TABLE 4-12. WEIGHTED PERCENTAGE OF HABITAT TYPE
IN THE FOUR FISH SAMPLING SECTIONS
OF THE THIRD BRANCH OF THE WHITE RIVER
Habitat
Avail-
Section
Shal-
low
slow
Shal-
low
fast
Deep
slow
Deep
fast
For-
est
deb-
ris
Ripa-
rian
vega-
tation
Under-
cut
bank
able
spawn-
ing
area
A
0.74
0.17
0.04
0.01
0.10
0.10
< 0.01
0.83
B
0.51
0.20
0.24
0.0
0.08
0.07
0.01
0.55
C
0.63
0.41
0.0
0.0
0.06
0.06
0.0
0.58
D
0.49
0.44
0.07
0.04
0.09
0.03
0.02
0.76
revealed that section B had significantly lower diversity than
section D. However diversity was not significantly different
between the remaining sections. Similarly, section B was
significantly lower in numerical abundance than section A and no
significant differences wre found between the other sections.
Discussion
Chlorinated effluent from the Randolph WPCP had few
adverse impacts on water quality and aquatic biota. Chlorine was
not detected below transect IV (150 m downstream from the
outfall) and the extent of the environmental impact due to
chlorinated effluent during the three day study period was
confined to the area between the WPCP outfall and the confluence
of Ayers Brook with the Third Branch. The TRC monitoring results
and the qualitative dye study during the low flow study period
4-39
-------
TABLE 4-13. SUMMARY OF MACROBENTHIC SPECIES COMPOSITION,
NUMERICAL ABUNDANCE AND DIVERSITY FROM FOUR SECTIONS
OF THE THIRD BRANCH OF THE WHITE RIVER, JULY 1983
Taxon
Section
B
Plecoptera
Perlidae (nymph)
Neoperla clymeme
Ephemeroptera
Baetidae (nymph)
Species A
Baetis cf.
Ephemerellidae (nymph)
Drunella (Ephemere 1 la) cornuta
Drunella (Ephemerella) lata
Serratella (Ephemerella) serrata
Heptageniidae (nymph)
Heptagenia cf.
Epeorus cf.
Rhlthrogena cf.
Leptophlebiidae (nymph)
Paraleptophlebia cf.
Siphlonuridae (nymph)
Isonyc hia cf.
Trichoptera
Brachycentridae (larvae)
Brac hyc entrus nigrosoma
Glossosomatidae (larvae)
Glossosoma sp.
Hydropsychidae (larva)
Hydropsyche sp.
Philopotamidae (pupae)
Dolophilus Sp.
Trentonius distinctus
Polycentropodidae (larvae)
Species A
Unknown family (pupae)
Species A
Species B
Megaloptera
Corydalidae (larvae)
Nigronia sp.
Coleoptera
Elmidae
Stenelm'is sp. (larvae)
Stehelnis sp. (adult)
Diptera
Chironomidae (larvae)
Tipulidae (larvae)
Hexatoma sp.
Species A
Total No. of Taxa Identified
Average Diversity (D)*
65
3
2
1
6
3
127
154
139
1
1
9
52
1
6
2
2
22
33
35
18
13
1
2
6
3
39
7
1
1
4
2
42
1 1
4
43
14
21 10 17 19
0.76 0.58 0.81 0.86
@ Numerical abundance is the total number of individuals from
three separate 0.18 m samples. See Appendix D for results of
each replicate sample.
* Average index (D) is the mean of the three separate diversity
index values calculated for each replicate sample.
-------
indicated that the chlorinated effluent traveled down the left
bank for about 50 m before dispersing across the river. At this
point TRC levels decayed to less than 0.05 mg/1.
The rapid decay of TRC observed in the Third Branch was
probably due to the high proportion of free residual chlorine in
the effluent. TRC is the sum of free residual chlorine (hypo-
chlorous acid - HOCL) and combined residual chlorine (primarily
chloramines). Monochloramine is the principle chloramine en-
countered under typical conditions of wastewater chlorination
when ammonia concentrations are typically high (Jolley and
Carpenter 1982). However, the Randolph WPCP effluent contained
negligible amounts of ammonia nitrogen (less than 0.1 mg/1).
Thus the TRC measured at the Randolph WPCP probably consisted of
a mixture of hypochlorous acid and chloramines (mono and di-
chloramine), based on effluent ammonia and pH (6.7-6.8) (Jolley
and Carpenter 1982). The stability of free residual chlorine in
natural waters is quite low (Jolley and Carpenter 1982).
According to Johnson (1978), Snoeyink and Marcus determined that
free residual chlorine (HOCL, OCL~) in nitrified secondary
effluent dosed with 3.1 mg/1 chlorine decays rapidly with half
lives of 8 to 28 minutes.
The trout fishery of the Third Branch did not appear to be
adversely affected by chlorinated effluent. The principal
toxicants in secondary wastewater efluents are typically residual
chlorine and un-ionized ammonia (Paller et al. 1983). The
4-41
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observed levels of un-ionized ammonia, temperature, pH and
dissolved oxygen in the third branch were well within the ranges
suitable for salmonids and other fresh water biota. (Soderberg
et al. 1983; U.S. EPA 1976; U.S. EPA 1983). Despite the fact
that detectable TRC levels were found on the day of
electrofishing, no significant differences in trout abundance or
biomass were observed between section A, upstream of the WPCP,
and section B, downstream of the WPCP. Both trout population and
biomass estimates in section B were within the 95 percent
confidence intervals of the estimates of the same parameters in
section A 650 m upstream from the WPCP. Sections C and D further
downstream had significantly lower trout population and biomass
estimates than sections A and B. These differences are
attributed to the reduced trout habitat quality in these
sections. Unfortunately these were the only comparable habitats
to section A and B available in the Third Branch downstream from
the confluence of Ayers Brook. Section C in particular was poor
trout habitat because it lacked deep water habitat during the low
flow warm weather period. Section C was also lacking in fish
cover such as forest debris, riparian vegetation and undercut
bank. Sections A and B contained a wide variety of habitat with
relatively large amounts of fish cover and deep water habitat.
Condition factors of fish above and below the WPCP were
contrasted to determine if the treatment plant had a chronic
effect on resident trout populations. The results showed no
4-42
-------
decrease in the condition factor of trout downstream from the
outfall. This indicated that the chlorinated effluent had no
effect on condition factors, or any effect was masked by movement
of fish from unaffected areas to section B. A zone of salmonid
passage existed adjacent to the Randolph WPCP during the three
day low flow study. Each transect on each day had at least one
station with TRC levels less than 0.05 mg/1 which should allow
passage of resident and migratory salmonids (Metcalf & Eddy, Inc.
1982). The Randolph WPCP has a streambank discharge which can
lessen the impact of chlorinated effluent on aquatic biota (Tsai
1973).
The Randolph WPCP effluent adversely affected the
macrobenthos in section B about 150 m downstream from the
Randolph treatment plant. Significant reductions in species
diversity and abundance were noted in the benthic samples from
section B. The macrobenthos can be a better indicator of long
term environmental effects because they are less capable than
fish of avoiding potential toxicants such as TRC. Typically,
wastewater effluents decrease macrobenthic species diversity and
increase the abundance of a few tolerant species (Warren 1971).
In the Third Branch, both diversity and abundance decreased in
samples from section B downstream of the effluent outfall
indicating that the WPCP may be having a toxic effect on the
macrobenthos (Warren 1971). Decreased macrobenthic species
diversity and abundance noted in Section B, downstream of the
4-43
-------
Randolph WPCP may have reflected previous episodes of
overchlorination or the release of an unknown toxicant. Whether
this was due to chlorine remains unclear. The macrobenthos noted
further downstream in sections C and D, were similar to the
upstream control area.
The chlorination system at the Randolph WPCP performed
satisfactorily during the study period. Effluent grab samples
are collected and analyzed for chlorine residual using the
iodometric method of chlorine residual amperometric titration
analysis titration, which is the most precise method of residual
analysis available to operators (see Chapter 6 Recommended
Practices for Minimizing Excessive Chlorine Use). The low
wastewater flow study of effluent and receiving water TRC levels
showed that the chlorination flow pacing system was adequate.
High levels of TRC did not appear in the effluent during low
wastewater flow periods. Thus, the WPCP could not be the cause
of potentially undetected nocturnal overchlorination which might
result in TRC toxicity to aquatic organisms. Initial mixing of
the chlorine solution could not be evaluated because the chlorine
solution feed point was not located as indicated in the design
drawings. The minimum chlorine contact time of 45 minutes
estimated from the dye study, appeared to be adequate. However,
the observed minimum contact time of 45 minutes was much lower
than the theoretical contact time of 120 minutes and indicated
that short-circuiting was occurring. Approximately two feet of
4-44
-------
sludge was found at the inlet to the chlorine contact tank. This
accumulated sludge probably exerts a chlorine demand that must be
satisfied before a chlorine residual and hence disinfection can
be achieved. Effluent quality of the Randolph WPCP changed
during the study period, particularly with respect to
concentrations of total and fecal coliform. An increase in
concentrations of total and fecal coliform bacteria was noted in
the effluent on day 6, a Saturday and may have been due to the
lack of fulltime staffing.
Public health was protected downstream from the WPCP out-
fall. Class C water quality standards were met in all samples
taken downstream of the treatment plant during the three day
study period in July, 1983. This was in spite of the elevated
coliform levels in the effluent on the third day of water quality
sampling. The Randolph WPCP was not the only factor affecting
the distribution of coliform bacteria in the Third Branch. Water
quality standards for coliform bacteria were not met upstream
from the Randolph WPCP. This stretch of river is class B, and
total and fecal coliform should not exceed 500 and 200 per 100
ml, respectively. This class B standard was exceeded in seven
out of nine total coliform samples and three out of nine fecal
coliform samples. This indicated that there were sources of
coliform bacteria to the Third Branch upstream of the Randolph
WPCP. This finding has public health implications because an
4-45
-------
area of the river between the outfall and transect I was used as
a bathing area during the study period.
In contrast to the Metcalf & Eddy findings, Pagel and
Langdon (1981), based on the 1979 fisheries data of Marcinko
(1980), observed a clear decrease in trout populations downstream
from the Randolph WPCP. They observed that rainbow trout
populations dropped from 178 per hectare upstream of the
treatment plant to 23 per hectare downstream of the plant, as
opposed to the Metcalf and Eddy estimates of 527 rainbow trout
per hectare upstream of the outfall, and 665 per hectare
downstream. Similarly, brown trout numbers in 1979 were reduced
from 131 per hectare upstream to 28 per hectare downstream of the
treatment plant (Pagel and Langdon 1981). The present study
showed a slight increase in brown trout population from 217 per
hectare upstream of the outfall to 227 per hectare downstream.
Pagel and Langdon (1981) did not present confidence intervals so
it is impossible to evaluate the precision of their estimates.
However, Pagel and Langdon (1981) dilution calculations, and
average width of their electrofishing stations indicate that the
Third Branch was at a much higher flow level during their 1979
study than during the present study. The lower river flow levels
during the present study could have concentrated fish into
smaller fish sampling sections and the resulting population and
biomass estimates per hectare would be higher than the same
estimates obtained during a higher river flow period. This
4-46
-------
analysis does not explain the large drop in trout populations
observed by Pagel and Langdon (1981) downstream from the
outfall. Stocking of trout has not occured in the study area,
and fish kills have not been reported downstream from the WPCP
(Lawrence 1983).
While the Randolph WPCP influenced macrobenthic species
diversity and abundance in 1983, the treatment plant had very
little influence on the bottom fauna in 1979 (Pagel and Langdon
1981). Both the 1979 and 1983 benthic samples were dominated by
mayflies, caddisflies and midge larvae.
The chlorinated effluent of the Randolph WPCP had little
to no effect on trout populations but a measurable adverse effect
on diversity and density of macrobenthos of the Third Branch
during the low river flow period in July 1983. Chlorine
generally decayed rapidly to less than 0.05 mg/1 within 50 m from
the outfall, and the high proportion of free residual chlorine
probably accounted for the rapid decay. Although detectable
levels of TRC were found in the fish sampling section just
downstream (93 m) from the outfall, there were no significant
differences between trout populations or biomass estimates for
sampling stations upstream and immediately downstream of the
treatment plant. A zone of passage was assured at the outfall
during the three days of sampling during low river flow.
Significant reductions in macrobenthic diversity and abundance
however, were noted about 150 m downstream from the Randolph
4-47
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treatment plant. After repair of the chlorinator the
chlorination system at the Randolph WPCP operated reliably and
the class C coliform standards were met in all samples collected
downstream from the outfall.
Since few adverse environmental impacts were noted, few
improvments were recommended at the Randolph WPCP, other than
removal of accumulated sludge from the chlorine contact tanks.
However, certain minor improvements to the chlorination system
may be warranted to provide additional protection if an Atlantic
Salmon fishery is ever restored to the Third Branch of the White
River at Randolph. Increased longitudinal baffling in the
chlorine contact tank was recommended to improve disinfection
efficiency by lengthening contact times and would potentially
reduce TRC levels in the effluent. Addition of a chlorine
residual analyzer to the automatic chlorine feed rate control
system would assure that the least amount of chlorine would be
used and guard against the possibility of overchlorination.
These minor improvements were recommended to help ensure the
success of future salmon restoration efforts on the Third Branch
of the White River.
4-48
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LITERATURE CITED
American Public Health Association. 1976. Standard Methods for
the Examination of Waste and Wastewater. Fourteenth Edition.
American Public Health Association, Washington, D.C. 1193 pp.
Bagenal, T.B. and F.W. Tesch. 1978. Age and Growth. Pages 101—
136. in T. Bagenal (ed.) Methods for Assessment of Fish
Populations in Fresh Waters. Third Edition, International
Biological Programme Handbook No. 3. Blackwell Scientific
Publications.
Boyer, M.C. 1964. Streamflow Measurements. Section 15 in
Handbook of Applied Hydrology. V.T. Chow (ed.) McGraw-Hill
Book Company, New York.
Dubois and King, Inc. 1981. Facilities Planning Report for the
Village of Randolph, Vermont. Prepared for the Board of
Trustees, Randolph, Vermont.
Green, R.H. 1979. Sampling Design and Statistical Methods for
Environmental Biologists. John Wiley and Sons. 257 pp.
Hollander, M. and D.A. Wolfe. 1973. Nonparametric Statistical
Methods. John Wiley and Sons. 503 p.
Johnson, J.D.. 1978. Measurement and persistence of chlorine
residuals in natural waters. Pages 37-63 in R.L. Jolley (ed.)
Water Chlorination: Environmental Impact and Health Effects,
Vol. 1. Ann Arbor Science Publishers, Inc. Ann Arbor,
Michigan.
Jolley, R.L. and J.H. Carpenter. 1982. Aqueous Chemistry of
Chlorine: Chemistry, Analysis, and Environmental Fate of
Reactive Oxidant Species. Oak Ridge National Laboratory,
ORNL/RM-7788. 116 pp.
Lawrence, D. 1983. Fish and Game Warden, Vermont Department of
Fish and Game. [Telephone converstaion with P. Geoghegan,
Metcalf & Eddy, Inc.] September 15, 1983.
Lind, O.T. 1974. Handbook of Common Methods in Limnology. The
C.V. Mosby Co., St. Louis, 154 pp.
Marcinko, M. 1980. A comparison of trout standing stock above
and below muncipal wastewater treatment plant discharges in
four Vermont streams. Vermont Fish and Game Department,
Technical Assistance Project FW-17-T., 13 pp.
4-49
-------
Metcalf & Eddy, Inc. 1982. Impacts of Wastewater Disinfection
Practices on Coldwater Fisheries (Draft). Prepared for U.S.
Environmental Protection Agency, Region I. Boston,
Massachusetts.
Oswood, M.E. and W.E. Barber. 1982. Assessment of fish habitat
in streams: goals, constraints, and a new technique.
Fisheries 7(4):8—11•
Pagel, C.W., and R.W. Langdon. 1981. A preliminary study of the
influence of chlorinated wastewater on the biological life of
selected rivers and streams in Vermont. Stat of Vermont Agency
of Environmental Conservation, Montpelier, Vermont. 96pp.
Paller, M.H., W.M. Lewis, R.C. Heidinger, L.J. Wawronwicz.
1983. Effects of ammonia and chlorine on fish in streams
receiving secondary discharges. Journal Water Pollution
Control Federation. 55(8): 1087-1097.
Phillips, R.I. 1982. Environmental Engineering, Vermont
Department of Water Resources and Environmental Engineering.
[Letter to K. Wood, U.S. EPA Region I] September 1982.
Seber, G.A.F., and E.D. Le Cren. 1967. Estimating population
parameters from catches large relative to the population.
J. Animal Ecology 36:631-643.
Simpson, E.H. 1949. Measurement of Diversity. Nature 163:688.
Soderberg, R.W., J.B. Flynn and H.R. Schmittou. 1983. Effects
of ammonia on growth and survival of rainbow trout in intensive
static water culture. Trans. Amer. Fish. Soc. 112(3):448-451.
Sokal, R.R. and F.J. Rohlf. 1982. Biometry. Second Edition.
W.H. Freeman and Co., San Francisco. 859 pp.
Tsai, C. 1973. Water quality and fish life below sewage
outfalls. Amer. Fish. Soc. 102(2):282-292.
U.S. Environmental Protection Agency. 1976. Quality Criteria
for Water. U.S. Envrionmental Protection Agency, Washington,
D.C. 255 pp.
U.S. Environmental Protection Agency. 1983. Water Quality for
the Protection of Aquatic Life and its Uses: Ammonia (Final
Draft). U.S. Environmental Protection Agency, Office of
Research and Development, Environmental Research Laboratory,
Duluth, Minnesota, 189 pp.
4-50
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Warren, C.E. 1971. Biology and Water Pollution Control. W.B.
Saunders Company, Philadelphia, PA. 434 pp.
4-51
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CHAPTER 5
DESCRIPTION OF EXISTING DISINFECTION SYSTEMS
Comprehensive information about the chlorination systems
presently in use in New England is essential to develop useful
recommendations for reducing the levels of residual chlorine
discharged from wastewater treatment plants. To obtain this
information, EPA and the states of Maine, New Hampshire and
Vermont cooperated in sending a survey questionnaire to the
operators of all municipal wastewater treatment plants in the
three-state area. The results of the survey are discussed below
and recommendations for improved disinfection practices are
presented in Chapter 6.
Background
In recent years, the increasing concern regarding the
potential harmful effects of chlorine residuals on fish and other
aquatic organisms has led to studies to identify methods for
reducing effluent chlorine levels (Sepp and White 1981; Garreis
and Parrish 1982). These studies evaluated wastewater dechlori-
nation systems or mitigation measures employed downstream of the
chlorination systems to reduce effluent concentrations of
chlorine. Implementation of a dechlorination system typically
involves installation of special equipment or structural renova-
tion. In addition, past studies have focused on increasing the
efficiency of the chlorination processes so that the required
5-1
-------
bacterial kill, as measured by coliform bacteria in the effluent,
can be accomplished with less chlorine. If the efficiency of the
chlorination process is improved, two important benefits will
result:
1. The effluent chlorine residual concentrations should
be lower because less chlorine is required to
accomplish the desired level of disinfection.
2. Cost savings will be realized because less chlorine is
used.
Although in some cases, protection of particularly sensi-
tive aquatic resources may dictate installation of a dechlori-
nation system, the associated operations and maintenance invest-
ment will cost less if the system is coupled with efficient
chlorination processes.
Through extensive chlorination pilot plant studies, the
following critical components of chlorination systems were
identified (Sepp and White 1981):
1. Rapid and thorough mixing of chlorine solution with
the wastewater.
2. Minimum of 30 minutes contact time should be provided
at peak flows.
3. Plug flow contact mode with minimal short-circuiting
or dead spots.
5-2
-------
4. Automatic closed loop system to pace chlorine feed
rates according to variations in flowrate and residual
levels.
The recommendations developed during this present study are based
upon the findings of these previous research efforts and upon
established guidelines for design of wastewater treatment plants
by the New England Interstate Water Pollution Control Commission
(NEIWPCC 1980). By incorporating information obtained through a
questionnaire survey, the recommendations are tailored to the
municipal disinfection systems presently in use in northern
New England.
Methodology
Based on previous research efforts, a questionnaire was
developed (see Appendix B) to obtain detailed information on
existing chlorination systems. The questionnaire was mailed to
the operators of 220 municipal wastewater treatment plants in
Maine, New Hampshire and Vermont. The operators were asked to
describe physical systems as well as operational techniques by
supplying information on:
1. treatment processes
2. effluent quality
3. type of disinfectant
4. feed rate control systems
5. equipment and facilities used for initial mixing
6. chlorine contact facilities
5-3
-------
7. method and frequency of residual chlorine measurement
8. amount of chlorine used and typical residual
concentrat ions
9. frequency of equipment maintenance
10. system reliabilty
Completed questionnaires were received from 152 treatment
plant operators (approximately 70 percent). The operators
provided useful responses and frequently supplied additional
comments regarding the operation of the treatment plants.
Information from the completed questionnaires was transferred to
a computer data base for compilation and evaluation. This data
base can be easily updated or expanded as disinfection systems
are modified and improved. In addition, the data base is
available if EPA should request additional analyses or comparison
with data subsequently obtained in other studies, or if one of
the participating states should desire additional state-specific
information.
Existing Conditions
After reviewing available information on the most
efficient chlorination system design and operation, data from the
questionnaires were analyzed. Through this analysis, existing
conditions were characterized and typical problem areas were
identified.
Type of Disinfection System. As shown in Table 5-1 ,
chlorine gas disinfection is the most commonly used system at
5-4
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TABLE 5-1. TYPE OP DISINFECTION SYSTEMS USED IN NORTHERN NEW ENGLAND*
Total
number Chlorine gas Hypochlorite Liquid Chlorine Ultraviolet None
State responses Number Percent Number Percent Number percent Number Number Percent
Maine 57 44 77 7 12 3 5 1 2 4
New Hampshire 48 22 46 22 46 1 2 - 3 6
Vermont 47 40 85 6 13 1 2
Overall 152 106 70 35 23 5 3 1 5 3
* Data obtained from questionnaire survey
municipal wastewater treatment plants in northern New England.
Approximately 70 percent of the plants use chlorine gas, 23
percent use hypochlorite and 3 percent use liquid chlorine. Five
respondents (3 percent) reported that wastewater disinfection is
not presently used.
Dechlorination. At this time, wastewater dechlorination
is not widely used in northern New England. The questionnaire
responses indicated that dechlorination systems are presently
used at only two treatment plants in New Hampshire and three
plants in Vermont.
Seasonal Disinfection. Approximately 55 percent of the
questionnaire respondents in Maine utilize seasonal disinfection,
that is disinfection of wastewater effluent for only half of the
year, from April through October. Where allowable, seasonal
disinfection is advantageous because it allows for protection of
downstream recreational uses during the summer months, but
chemical usage and operating costs are decreased by discontinuing
disinfection in the winter when the need for protecting
5-5
-------
recreational use of the receiving water is minimal. While the
disinfection systems are operational, the reported effluent fecal
coliform concentrations are less than or equal to 200 MPN/
100 ml. Wastewater disinfection is practiced throughout the year
by 45 percent of the Maine questionnaire respondents, and the
effluent fecal coliform concentrations are less than or equal to
15 MPN/100 ml. Many of these plants discharge to marine waters
which may be used for shellfishing.
In New Hampshire, 90 percent of the questionnaire
respondents practice seasonal disinfection. Between April and
November, the wastewater effluent is discharged with a total
coliform concentration less than 240 MPN/100 ml. At the
treatment plants which disinfect effluent throughout the year,
the requirement for continual disinfection is occasionally
coupled with a more stringent effluent coliform limitation.
Wastewater disinfection is practiced throughout the year
by treatment plants in Vermont. The majority of these plants
reported that effluent is discharged with total and fecal
coliform concentrations of 500 MPN/100 ml and 200 MPN/100 ml
respectively.
Chlorine Dose. As indicated in Table 5-2, the average
chlorine dose exhibits a wide variation from state to state as
well as from plant to plant. The information presented in this
table is based upon the average chlorine dosage rate as reported
by the individual operators in the questionnaire survey.
5-6
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TABLE 5-2. REPORTED AVERAGE CHLORINE DOSAGE RATES'
State
Total
Number
Responses
Mean
Chlorine
Dose
(mg/1)
Median
Chlorine
Dose
(mg/1)
Range of
Chlorine
Dose
(mg/1)
Maine
35
6.6
3.4
0.75 - 30
New Hampshire
31
9.2
7.3
1.2 - 30
Vermont
23
3.8
2.6
0.2 - 12
Overall®
89
6.8
5.0
0.2 - 30
respondents.
@ Only 89 of 152 respondents supplied information on chlorine
dosage.
A direct relationship exists between required coliform
kill and chlorine dosage rate. Without altering the facility,
more chlorine is usually necessary to achieve a higher quality
effluent containing fewer coliform bacteria. However, the dosage
rate is also a function of a variety of other factors including:
type of wastewater treatment and effluent characteristics,
contact time, and efficiency of initial mixing.
As shown in Table 5-3, the questionnaire survey results
confirm that higher chlorine dosages are associated with plants
which provide less treatment. In other words, greater chlorine
doses are typically used at primary plants and the smallest
chlorine doses are associated with secondary plants.
Mean Residual Chlorine Concentrations The information on
effluent mean residual chlorine concentrations obtained from the
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TABLE 5-3 DEGREE OF TREATMENT VERSUS REPORTED AVERAGE
CHLORINE DOSAGE RATES*
State
Primary
Extended
Aeration
Aerated
Lagoons
Pull
Secondary
Maine
8.8
(5.7)@
4.7
(3.0)
-
3.0
(2.4)
New Hampshire
16.9
(11)
10.6
(7.0)
8.5
(9.0)
6.2
(6.5)
Vermont
6.2
(6.2)
5.2
(4.7)
4.4
(3.3)
4.0
(4.0)
Overall
11.1
(9.1)
6.0
(4.0)
6.8
(6.5)
4.1
(3.8)
* Mean of reported average chlorine doses for all treatment
plants.
@ Numbers in parentheses represent median of reported average
chlorine dosages.
completed questionnaires is summarized in Table 5-4. Of the 97
respondents who provided total residual chlorine data, only
two reported effluent concentrations less than 0.1 mg/1. The
questionnaire responses indicated that residual chlorine levels
were generally lowest in wastewater treatment plants in Maine.
New Hampshire has both the largest number of treatment plants
discharging residual concentrations in excess of 1.0 mg/1 as well
as the highest state average. However, permits issued by the
state of Vermont allow treatment plants to discharge effluent
with residual chlorine concentrations as high as 4.0
mg/1 residual chlorine.
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TABLE 5-4. MEAN CONCENTRATIONS OF EFFLUENT TOTAL RESIDUAL CHLORINE
Number
State
Total
number
responses
which
reported
TRC*
TRC exceeding
0.5 mq/1
Number Percent
TRC exceeding
1.0 mq/1
Number Percent
Average
TRC
(mg/1)
Median
TRC
(mg/1)
Range
TRC
(mg/1)
Maine
57
40
25
63
5
13
0.94
0.65
0.1 - 9.3
New Hampshire
48
31
29
94
20
65
1.65
1.50
0.2 - 4.0
Vermont
47
26
19
73
9
35
1.15
0.95
0.04 - 3.8
Overall
152
97
73
75
34
35
1 .22
1.0
0.04 - 9.3
* TRC = Effluent total residual chlorine mean concentration, rag/1.
@ Percent of respondents which reported mean concentrations.
The relatively large number of New Hampshire treatment
plants discharging high residuals may be the result of a policy
which was in effect until 1981. Due to difficulties in
accurately determining low chlorine residuals, operators were
encouraged until 1981 to maintain a residual of at least 2 mg/1
to ensure complete disinfection. It is possible that operators
are still trying to maintain this residual level.
As was noted in Chapter 1 of this report, chlorine
concentrations of 0.03 mg/1 to 0.09 mg/1 are acutely lethal to
rainbow trout after 96 hours exposure and consequently,
recommended water quality criteria have been set at about one-
tenth of these concentrations. In many cases the samples
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analyzed for chlorine residual concentrations are collected from
the effluent end of the contact tank. The chlorine residual
concentration which is discharged through the outfall to the
stream would be somewhat less than the reported residual
concentrations due to chemical reaction and decay occurring
downstream of the sample collection point. In addition, because
of chlorine decay and dilution of the discharged effluent by the
receiving water, the chlorine residual concentrations in the
stream will be significantly less than chlorine concentrations in
the discharged effluent. Nevertheless, the reported residual
chlorine levels are cause for concern. For example, to meet
water quality criteria, the combination of dilution and chlorine
decay within the allowable mixing zone which reduces the
concentration by a factor of 100 to 200 may be required for an
effluent containing 1.0 mg/1 residual chlorine. Particularly
during low flow periods, the necessary dilution may not be
available in many streams and the discharge of a chlorine
residual of 1.0 mg/1 could result in adverse impacts on aquatic
ecosystems. At treatment plants in Vermont, which may discharge
residual chlorine concentrations up to 4.0 mg/1, a reduction
factor of 400 to 800 within the allowable mixing zone may be
required to meet water quality criteria for the protection of
sensitive species.
Initial Mixing of Chlorine With Wastewater. Pilot plant
studies have demonstrated that the most effective chlorination
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systems include rapid and thorough mixing of chlorine solution
with wastewater in an area of highly turbulent flow followed by
an adequate quiescent plug flow contact time to achieve bacterial
kill (Sepp and White 1981). These systems facilitate bacterial
kill by maximizing the contact between wastewater and
chlorine. The most thorough mixing is achieved by systems in
which the chlorine solution is fed through diffusers into a
hydraulic jump, into a pipeline flowing full, or immediately
upstream of a mechanical turbine mixer installed to mix chlorine
solution and wastewater. Without the provision of adequate
initial mixing, bacterial contamination of the receiving waters
may occur if some portion of the flow passes through the system
without coming in contact with the chlorine solution.
Alternatively, the discharge of toxic residual chlorine
concentrations may result from the overchlorination of some
portion of the flow.
Of the 152 operators who responded to the questionnaire,
32 percent reported that initial mixing was accomplished by
introducing the chlorine solution into a turbulent pipeline or
flume, 9 percent reported that mixing was achieved by a hydraulic
jump, and 4 percent reported using a mechanical mixer. In
addition, 28 percent of the respondents reported that an over-
and-under or side baffling system was used to accomplish initial
mixing, 6 percent reported use of a drop or submerged weir,
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4 percent did not have a mixing system, and no information was
available for 16 percent of the systems.
For those treatment plants which perform initial mixing
through a baffle system, an overall mean residual chlorine
concentration of 1.37 mg/1 was computed. Overall mean residual
concentrations were computed by adding together the reported
residual concentrations for all the plants with a particular type
of mixing system, and then dividing by the number of plants. For
those treatment plants which use a turbulent pipeline for initial
mixing, the overall mean residual concentration was computed as
1.34 mg/1. Although effective mixing of chlorine and wastewater
can be accomplished in turbulent pipelines, the rather high
overall mean residual chlorine concentration computed for this
type of mixing system may be indicative of ineffective use of
disinfectant. Varying flows at the treatment plant may result in
periods of quiescent flow and therefore little mixing at the
point of chlorine introduction. Alternatively, mixing may be
effective, but the dosage may be too large at these particular
plants. Although hydraulic jump or mechanical mixing systems are
not widely used, the computed overall mean residual chlorine
concentrations associated with these types of systems were
0.80 mg/1 and 0.70 mg/1, respectively. These computed residual
concentrations, which were markedly less than those associated
with the turbulent pipeline or baffle systems, support the
conclusion that thorough initial mixing is important and, if
5-1 2
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conducted properly, can improve disinfection efficiency and lead
to reduced residual chlorine levels.
In addition, 47 percent of the operators reported that
chlorine solution was added directly to the chlorine contact tank
with diffusers used at 79 percent of these plants. Introduction
of chlorine solution directly to the contact tank is much less
likely to yield adequate or effective disinfection because the
turbulence is not sufficient to ensure that all the wastewater
comes in contact with the chlorine solution. Some portion of the
flow may then pass through the contact tank without being
disinfected while another portion may be overchlorinated and
leave the system with a high chlorine residual concentration.
Chlorine Contact Time. It is vital that adequate
detention volume and hence sufficient contact time is available
to achieve the required bacterial kill. Disinfection is not an
instantaneous process, and chlorination contact tanks in northern
New England should have sufficient volume to provide a minimum of
15 minutes contact time at maximum wastewater flowrates unless
the effluent is discharged to a shellfishing area, in which case
the contact tank should provide a minimum contact time of 30
minutes (NEIWPCC 1980). However, as previously discussed,
research efforts have recommended a minimum contact time of 30
minutes to ensure adequate disinfection and minimize effluent
chlorine residual concentrations (Sepp and White 1981; WPCF
1976). Effective disinfection is dependent upon both adequate
5-13
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chlorine doses and adequate contact time. If available contact
time is decreased, effluent coliform permit limitations can still
be met if the chlorine dosage rate is increased. However, the
increased dosage may result in increased levels of chlorine
residual in the effluent. Similarly, if contact time is
increased, the required disinfection may be accomplished with
less chlorine. Therefore, if the impact of chlorine residuals on
receiving water biota is a concern, it may be advisable to
consider providing additional contact time (WPCF 1976).
For each treatment plant, contact times were computed for
the four reported flowrates (existing average and peak flows;
design average and peak flows) by dividing the total contact
volume by the flowrate. The total contact volume was determined
from dimensions reported for the contact tanks and the outfalls.
For example, the present peak flows as reported in the question-
naires were used in computing the existing theoretical peak flow
contact times. The computed contact times for each regime were
averaged for each state and are presented in Table 5-5, indicate
that according to present-day design standards (NEIWPCC 1980),
most of the treatment plants provide sufficient contact time at
the existing and design peak flowrates.
Finally, to determine whether lower effluent residual
chlorine concentrations could be related to longer contact times,
the mean effluent residual concentration for each plant and the
computed contact times at average flow were analyzed. The
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TABLE 5-5. AVERAGE CHLORINE CONTACT TIMES
Contact Time
(minutes)
State
Existing
peak
flow
Design
peak
flow
Existing
average
flow
Design
average
flow
Maine
45(63)
37
121(143)*
84
New Hampshire
46(54)
22
135(187)
66
Vermont
63(83)
37
111(94)
63
Overall
51(67)
32
122(143)
72
* Numbers in parentheses are standard deviations.
analysis indicated that the relationship between these two
variables had no statistical significance. Although these
results appear to contradict previous research efforts which
found that longer contact times result in decreased residual
concentrations, the contact times used in this analysis were
based upon the assumption that all of the contact volume was
effectively utilized. As noted previously, short-circuiting
inhibits utilization of the entire volume and thereby causes the
actual contact time to be an unquantifiable fraction of the
theoretical contact time. It is likely that a statistically
significant relationship exists between effluent residual
concentrations and actual contact times. But without quantifying
actual contact times through onsite testing, this cannot be
confirmed.
5-15
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In Maine and Vermont, the state average theoretical
contact time computed for design peak flows was greater than
thirty minutes. In New Hampshire, the theoretical contact time
at the design peak flows may be less than adequate at many
treatment plants. To compensate for insufficient capacity, an
increased chlorine dose would be necessary at these treatment
plants to effectively disinfect at design peak flowrates.
However, in many instances the present peak flows have not
approached the design peak flows and therefore, the theoretical
contact times associated with the present peak flows compare more
favorably with design recommendations. At present, the
theoretical contact times available at the plants were generally
sufficient, but as flows increase and approach the design values,
the chlorine contact times will become inadequate at many plants.
It is important, however, to exercise caution in
evaluating this information because it is based upon the
theoretical chlorine contact times computed usinq the total
available contact tank and outfall volumes. In actuality, dead
spots or improperly located feed systems may reduce the effective
chlorine contact volume, thereby causing actual contact times to
be significantly less than the computed theoretical contact
times. In addition, short-circuiting or other deviations from
the optimal plug flow regime may result in some portion of the
flow receiving less than adequate detention time. This fact was
confirmed by investigations involving measurement of chlorine
5-1 6
-------
concentrations before and after chlorine contact chambers, which
revealed actual contact times significantly different from the
theoretical or computed contact times (White 1972). It has also
been reported that all but the most carefully designed contact
tanks allow a significant percentage of the flow to pass through
in less than the design contact time and that gross short-
circuiting occurs in many of the older contactors (WPCF 1976).
The questionnaire responses indicated that the average age of
disinfection systems in the three-state area was approximately
nine years. It is probable that many of these systems were
constructed prior to the development of improved contact tank
designs which maximize the opportunity for contact.
WPCF (1976) notes that an outfall pipe provides the best
configuration for maintaining a plug flow condition during
chlorine contact and recommends that within contact tanks, plug
flow may be achieved by placing baffling parallel with the
longitudinal axis to create long narrow channels. This type of
baffling would minimize short circuiting and facilitate a plug
flow contact mode. The overall length to width ratio of 40:1 is
recommended (WPCF 1976).
The information obtained through the survey indicates that
with the exception of coastal treatment plants which discharge
effluent through an outfall, the length to width ratios of the
contact tanks seldom approach the recommended value of 40:1.
Most of the contact tanks have horizontal baffles which are not
5-17
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as effective in producing plug flow to ensure complete contact of
wastewater and chlorine solution.
In order to more accurately evaluate a particular contact
system, dye may be added at the inlet to the contact tank, the
flow pattern can be observed and the dye concentration
subsequently measured at the outlet to determine the time of
travel in the tank. Without conducting tests on a case-by-case
basis, it is difficult to evaluate the actual effectiveness of
the contact systems. Only ten percent of the questionnaire
respondents reported that a dye tracer study had been
conducted. Thus, it is recommended that a program of visual
inspection and/or dye testing be conducted by the states to
obtain the information required to analyze and improve the
contact tank hydraulics on an individual basis.
Chlorine Feed Rate Control. The chlorine demand at any
given time is determined by the wastewater flow and its
constituents, both of which are highly variable. Therefore, it
is important to maintain a flexible feed system which allows the
chlorine feed rate to be increased or decreased as the chlorine
demand increases or decreases. In theory, a closed feedback loop
system including an automatic residual chlorine analyzer provides
the most reliable means of controlling chlorine dosage and
residual levels in the effluent. The chlorine feed mechanism in
this system is electrically connected to the plant flowmeter, and
the feed rate setting is based on a signal sent from the flow-
5-18
-------
meter. The actual feed rate is trimmed accordinq to a second
electrical signal sent from the automatic residual chlorine
analyzer. This system offers the advantages of automatic
response to changing wastewater characteristics, continuous
control, and requires little operator attention other than daily
calibration of the analyzer. As concentrations of chlorine-
demanding substances increase, the effluent chlorine residual
will temporarily decrease, and the resulting signal to the feed
mechanisms will result in an increased feed rate to satisfy the
increased demand. However, the analyzer is easily clogged by
effluents with high suspended solids concentrations, and this
automatic system may not be cost-effective for small treatment
plants.
Another type of automatic control system involves pacing
the chlorine feed rate on the flowrate. While this system does
not have the capability to automatically adjust the dosage
according to measured effluent residuals, maintenance require-
ments are less. The chlorine feed rate is automatically
controlled only by a signal from the flowmeter, so if
concentrations of chlorine demanding substances increase at a
constant wastewater flowrate, the chlorine feed rate would not
adjust automatically. An operator would have to analyze effluent
residuals and manually reset the chlorine feed rate to compensate
for the altered wastewater characteristics.
5-19
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Finally, the chlorine feed rate may be set and adjusted
manually. This type of feed system offers the least flexibility
and effective control of disinfection, requires frequent operator
attention to read the flowmeter, analyze the chlorine residual
concentration and manually set the chlorine feed rate. Without
frequent operator attention, this system adds chlorine solution
at a constant rate and does not respond to changes in wastewater
flow or constituents. Hence, overchlorination is likely to occur
with this type of system.
According to the 152 treatment plant operators responding
to the questionnaire, both manual and some type of automatic
chlorine feed rate control systems were available at 84 plants
(55 percent), manual systems only were available at 51 plants (34
percent), and 2 plants (1 percent) had only automatic feed rate
control systems with no manual system as backup. Ten percent of
the respondents did not provide information on the feed rate
control system. However, many operators reported that use of the
automatic systems had been discontinued due to improper system
design or solids fouling of the automatic analyzer. The chlorine
feed rate was manually controlled at 85 treatment plants
(56 percent), automatic control systems were used at 49 plants
(32 percent), and both systems are used at two plants
(1 percent). For various undetermined reasons, the major portion
of the respondents appeared to be using the least effective means
of controlling chlorine feed rate.
5-20
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An overall mean residual chlorine concentration of
1.21 mg/1 was computed for those treatment plants which both
reported a mean residual chlorine concentration and used an
automatic feed rate control system. For those treatment plants
which used a manual feed rate control system and also reported a
mean residual chlorine concentration, the computed overall mean
residual concentration was 1.23 mg/1. This information indicated
that in the three states surveyed, the use of an automatic feed
rate control system apparently did not result in lower effluent
residual concentrations. However, lower effluent residuals could
be achieved by adjusting the settings on the automatic system.
The fact that the mean residual chlorine concentrations
are similar and rather large for both plants using manual and
automatic feed rate control systems, may be indicative of the
widespread need to ensure adequate disinfection by providing a
high residual chlorine level.
Chlorine Residual Analysis. The automatic chlorine
residual analyzer is advantageous because residual levels are
automatically and frequently monitored, thereby allowing the
chlorine feed rate to be altered as the chlorine demand varies to
maintain a specified effluent residual concentration. However,
satisfactory control may be achieved if manual sample collection
and residual analysis is conducted frequently with the feed rate
adjusted accordingly. At most treatment plants, the chlorine
demand can vary significantly during a given 24-hour period, and
5-21
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therefore, the feed rate should be adjusted several times each
day. A total of 54 respondents (36 percent) reported that
residual chlorine was measured more than once each day. About
half of the operators in Maine and New Hamshire measured residual
levels more than once a day, but only three operators in Vermont
determined residual chlorine levels twice each day. Only 36
respondents (24 percent) reported that the chlorine feed rate was
adjusted more frequently than once each day. At plants with only
one daily adjustment in chlorine feed rate, overchlorination may
be occurring during low flow periods, and similarly during peak
flow periods chlorination may be inadequate.
Chlorination System Maintenance. To ensure efficient
disinfection and minimal concentrations of residual chlorine, the
chlorination system equipment should be frequently maintained and
calibrated. Wastewater chlorination results in additional solids
removal as suspended solids in activated sludge effluent react
with chlorine residual and settle out of solution. Unless the
contact tank is frequently cleaned, these solids accumulate and
begin to decompose, recontaminating the effluent and reducing the
disinfection efficiency (Sepp and White 1981). It is therefore
recommended that the contact tanks be frequently cleaned to
maintain efficient use of chlorine as well as to achieve
consistently good effluent quality. Cleaning of the contact
tanks is best accomplished if the plant has two contact tanks so
that the flow can be directed through one tank while the other is
5-22
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temporarily shut down for cleaning. The questionnaire responses
indicated that about 47 percent of the plants had two contact
tanks. Routine maintenance of the contact tank occurred at least
twice a year at about 43 percent of the plants.
Summary
Characteristics typical of chlorination systems at
treatment plants in northern New England were determined by
conducting a questionnaire survey and compiling the responses.
Some of the characteristics which may be contributing to
inefficient disinfection or overchlorination included:
Effluent limitations not sufficiently stringent to
protect water quality
Inadequate initial mixing systems
Insufficient chlorine contact due to short-circuiting
or dead spots
Lack of adjustment in chlorine feed possibly causing
overchlorination
Insufficient routine maintenance including equipment
cleaning and calibration.
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LITERATURE CITED
Garreis, M.J. and W.F. Parrish, Jr. 1982. Operation DO-IT and
Operation TIDE: Controlling Chlorine in the Environment Office
of Environmental Programs, Department of Health and Mental
Hygiene, State of Maryland.
New England Interstate Water Pollution Control Commission
(NEIWPCC). 1980. Guides for the Design of Wastewater
Treatment Works, Prepared by the Technical Advisory Board of
the New England Interstate Water Pollution Control Commission.
Sepp, E. and G.C. White. 1981. Manual for Wastewater Chlorination
and Dechlorination Practices. Prepared for California State
Water Resources Control Board.
Water Pollution Control Federation (WPCF), Technical Practice
Committee, Subcommittee on Chlorination of Wastewater. 1976.
Manual of Practice No. 4 Chlorination of Wastewater.
White, G.C. 1972. Handbook of Chlorination, Van Nostrand
Reinhold Company.
5-24
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CHAPTER 6
RECOMMENDED PRACTICES FOR MINIMIZING
EXCESSIVE CHLORINE USE
In an extensive study conducted to recommend disinfection
techniques to optimize the use of chlorine, the following
components of disinfection systems were identified as critical to
effective disinfection (Sepp and White 1981):
initial mixing - thorough and accomplished in three
seconds.
minimum of 30 minutes at peak flow,
measured by first appearance of dye in
contact tank effluent.
provide equal detention for all portions
of flow, minimize back mixing and short-
circuiting in long narrow conduits.
rate should be automatically responsive
to both changes in flow and chlorine
demand.
chlorine residual - iodometric procedure with amperometric
analysis end point.
This chapter identifies steps which may be taken to
improve the efficiency of wastewater disinfection to maintain the
required pathogen kill while simultaneously reducing effluent
chlorine residuals, based on site-specific information obtained
from wastewater treatment plants in Maine, New Hampshire and
Vermont.
Regulatory Policies
State and Federal agencies should implement policies which
actively encourage the reduced usage of chlorine. During routine
6-1
contact time
contact tank
chlorine feed
-------
plant visits, state engineers can evaluate the plant chlorination
system and suggest improvements. During such visits the
importance of minimizing chlorine use and possible optimization
techniques can be discussed with the operator. For example,
Vermont allows effluent chlorination up to a maximum of 4.0 mg/1
total residual chlorine. However, questionnaire responses
indicated that some operators may be misinterpreting this to mean
that a residual of 4.0 mg/1 should be maintained. Such operator
misunderstanding and overchlorination could easily be corrected,
if it occurs. Particularly in New Hampshire, where earlier
regulatory policy specified that a residual of 2.0 mg/1 should be
maintained, every effort should be made to encourage the
operators to reduce residual levels.
To most effectively implement techniques to increase
disinfection efficiency and reduce levels of residual chlorine in
the plant effluents, the revised regulatory policies should be
coupled with programs for operator education and training.
Educated plant staff, knowledgeable about the chlorination
process and concerned about the impacts of excessive residuals,
are vital to ensure the process works correctly and safely using
a minimum amount of chlorine. In addition, educated operators
are necessary to achieve maximum benefit from the structural and
instrumentation improvements. Without proper operation, the most
sophisticated chlorination system may fail to improve the overall
disinfection process.
6-2
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Agencies may perform chlorine hazard evaluations as
described in Chapter 2 to assess the environmental impact of a
chlorinated discharge at a particular site. This procedure
includes an assessment of the receiving water to determine the
capability of the stream to support appropriate or desired
fisheries. Identification of particular discharges posing the
greatest chlorine toxicity hazard will allow the available funds
to be used where the most significant water quality improvement
and fishery development can be achieved.
Agencies can review chlorination system design standards
to ensure more efficient use of chlorine in new or upgraded
facilities to minimize effluent residuals. Current state water
quality regulations and NPDES permits may be re-evaluated from
the standpoint of chlorine toxicity to aquatic organisms.
Seasonal chlorination instead of year-round chlorination may be
reasonable. Maine is in the fourth year of a testing program to
reduce chlorine use by requiring only seasonal chlorination;
between October 1 and April 15, chlorination is not required
unless the plant discharges to a shellfish area or to a public
drinking water supply. A revision of the state water quality law
to allow this on a permanent basis is now pending. The State of
Vermont is also evaluating seasonal chlorination as an alterna-
tive to year-round chlorination. In New Hampshire, waivers from
the requirement of year-round disinfection are granted on a case-
by-case basis. As previously discussed, the questionnaire survey
6-3
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responses indicate that about 90 percent of the New Hampshire
treatment plants are practicing seasonal disinfection.
For a given facility, increased contact time will result
in lower chlorine residual concentrations without increasing
effluent coliform concentrations. In the future as new plants
are built and old plants are expanded, the states may want to
consider requiring a minimum of 30 minutes contact time at
maximum flow rates. Although providing additional contact volume
involves siginificant capital expenditure, in some cases it may
be necessary to protect sensitive aquatic species by minimizing
chlorine residuals. As an alternative to the requirement of
additional contact volume, dechlorination equipment may be less
expensive and equally effective.
The State of Vermont is considering instituting a policy
of required dechlorination at all treatment plants where the
effluent TRC exceeds 1.0 mg/1 and results in an instream TRC
greater than 0.025 mg/1 at the seven-day once in ten-year low
stream flow (7Q10).
Immediate Operational Improvements
Improvements in routine operation and maintenance
practices can be implemented with little or no increase in
operating costs. Proper operation of the chlorination system and
regular maintenance is essential to adequately disinfect the
wastewater to meet effluent coliform standards. Without a
comprehensive operation and maintenance program, equipment and
6-4
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structures can rapidly deteriorate, and investments in capital
improvements may be wasted. Operators can take some immediate
steps to improve the chlorination system.
One of the many benefits associated with good overall
plant performance and efficient operation of a treatment plant is
that less chlorine is required to disinfect higher quality
effluent. For example, primary effluent has a higher chlorine
demand which makes it more difficult to disinfect than secondary
effluent and organic nitrogen compounds present in primary
effluent also inhibit the chlorination process (White 1972).
This was also confirmed by the results of the questionnaire
survey. In the three states surveyed, primary treatment plants
generally required the largest chlorine doses, and plants with
full secondary treatment required the smallest chlorine doses.
In addition, the levels of coliform bacteria are reduced during
the secondary treatment process (WPCF 1976). High solids and
organic levels in the effluent increase the chlorine demand and
necessitate the addition of more chlorine to achieve the required
level of disinfection (WPCF 1976). The operator can reduce
chlorine use by ensuring that other wastewater treatment
processes are properly operating to consistently produce effluent
which is low in organics and other substances which exert a
chlorine demand.
Chlorine Residual Analysis. The amount of chlorine needed
to achieve the required degree of disinfection can only be
6-5
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determined by analysis of bacterial content and chlorine residual
in the effluent. The chlorine requirement varies with time,
flowrate and specific characteristics of the waste. Frequent
bacteriological and chlorine residual analyses are recommended to
obtain information to better control chlorine dosage and effluent
residuals. It is particularly important to take measurements
whenever the incoming flow rate changes significantly such as
during the morning peak flow. At these times changes in the
wastewater characteristics could affect the chlorine demand.
For the purposes of accurate chlorine residual
determination and process control, grab samples should be
collected and analyzed rapidly. Composite samples would provide
an invalid determination of chlorine residual due to chlorine
decay and would not allow for immediate adjustment in the
chlorine feed rate to achieve the desired residual level. To
maximize the accuracy of the residual determination after the
sample is collected, it is also important to avoid turbulence and
unnecessary exposure to light.
The recommended method of measuring total chlorine resi-
dual is the iodometric method using an amperometric titrator for
end point detection. The advantages of this method include
repeatability, accuracy and relatively little interference from
common oxidizing agents, temperature changes, turbidity or color
(White 1972). Residual determination using amperometric titra-
tion is also advantageous because the chlorine residual analyzers
6-6
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presently available operate on the amperometric method. Conse-
quently, calibration of the analyzers should be by amperometric
titration.
Purchase of an amperometric titrator (about $1,000) would
be required. To measure the total residual, the reducing agent
phenylarsine oxide (PAO) is added so that it will reduce the
iodine which is released in proportion to the combined chlorine.
The total chlorine residual is computed as the difference between
the PAO added and that remaining (White 1972). This method can
also be used to distinguish the amounts of free and combined
chlorine. An operator now using the DPD colorimetric or titri-
metric methods could measure chlorine residuals more accurately
by changing to the iodometric-amperometric titration method of
analysis. With precisely calibrated equipment, this method can
differentiate residual concentrations within 0.01 parts per
million (White 1972).
Operation/Maintenance. The operator can keep the
chlorination system working effectively only if routine
surveillance and maintenance is performed to keep equipment in
operating condition. The chlorination system should be checked
daily for proper operation (i.e. chlorine feed rate at required
level, adequate water supply pressure, proper chlorinator
injector vacuum). The chlorine contact tanks should be checked
for solids accumulation or slime buildup on walls. These
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deposits exert a chlorine demand and should be removed whenever
they are observed.
Keeping records of plant operation will establish a
history of plant performance, serve as a source of information
for plant operation, maintenance and as justification for expen-
ditures. Daily records provide an important tool for diagnosis
and identification of the chlorine requirements specific to each
plant. In addition, regulatory agencies use disinfection records
to assess compliance with state regulations. Data on the exist-
ing facility that should be readily available for reference
include: design reports, as-built plans, specifications and
equipment manufacturer's information. Daily operating records
should note: chlorine quantities used, chlorine residuals and
chlorine dosage rate; total flow as well as maximum and average
daily flow; results of bacteriological analyses; and any
operational problems and the corrective action taken.
Rotameter Sizing. The operator should check that the
chlorinator or hypochlorinator rotameter is properly sized for
the actual daily applied chlorine dosage. If the normal chlorine
dosage rate is low compared to the rotameter maximum reading, it
is difficult to accurately set the dosage to the desired range
and overchlorination may frequently occur. The operator should
contact the manufacturer's service representative to obtain a
rotameter sized for the actual range of chlorine used at the
plant. The operator can easily install the new rotameter. This
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will provide greater control and accuracy in setting the chlorine
dosage rate. This modification should require a capital
expenditure of no more than $500 per chlorinator.
Minor Modification Improvements
In order to implement the modifications discussed in this
section, an engineering study should be conducted to plan and
design the most suitable type of improvement for a particular
facility. The capital costs associated with these improvements
will vary significantly depending on the existing structures and
equipment at a given plant.
Initial Mixing. Proper mixing is one of the most
important factors in efficient chlorine disinfection (WPCF 1976).
Any improvement that can be made to improve complete mixing of
the chlorine solution with wastewater will increase the
effectiveness of the chlorination system. To evaluate the
adequacy of the existing mixing system, a series of grab samples
should be taken and analyzed for consistency of the chlorine
residual. Samples should be taken downstream of the mixing
system as the flow enters the chlorine contact tank. A
significant variation of residual concentrations in the samples
would indicate that chlorine mixing is not adequate. The
operator should first check that the chlorine solution outlet is
not blocked. If there is no diffuser, the addition of one will
aid in distributing chlorine solution.
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A turbulent flow condition is necessary to achieve the
rapid and thorough mixing which is prerequisite to effective
disinfection. Therefore, chlorine solution should be injected
through diffusers located in an area of either natural or induced
turbulence. Depending on the physical layout and available
hydraulic head, turbulence can be increased by construction of an
underflow baffle or overflow weir. Alternatively, the chlorine
solution injection point could be relocated to a point of greater
turbulence such as at a hydraulic jump or Parshall flume. In
some instances, it may be more practical to install a mechanical
mixer to create turbulent conditions.
Control Systems. The choice of chlorine control system
that should be used at a plant is dependent on the degree of
control necessary. The three control systems available are
manual, flow-proportional, and compound loop. In the manual
control system, the chlorine feed rate remains constant until
changed by the operator. Without frequent operator attention
this system will result in under- or over-chlorination. Normally
the feed rate is set for proper disinfection at peak flows which
results in overchlorination during most of the day. This
undesirable condition may be mitigated by use of a flow-
proportional control system.
A flow-proportional control system automatically and
continuously converts wastewater flow information into a
chlorination control signal which varies the chlorine dosage.
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This system works well as long as the chlorine demand of the
wastewater remains proportional to the flow. Since this is not
always true, the operator must take samples from the chlorine
contact tank and measure the chlorine residual at least every
four hours, adjusting the feed rate accordingly. Almost all
chlorinators and hypochlorinators can be operated in an automatic
mode paced by flow. The compound loop control system is
discussed under major modifications.
Chlorine Contact Tank Inlet. If the wastewater enters the
chlorine contact tank with a large horizontal velocity, short
circuiting and inadequate chlorine contact may result. The inlet
structure of the chlorine contact tank should be designed to
minimize horizontal velocities. Existing contact tanks with a
straight horizontal pipe inlet structure should be modified
either by placing a baffle in the tank in front of the inlet or
by installing an elbow on the pipe.
Major Modification Improvements
The modifications presented in this section would be the
most difficult and costly to implement. Significant
reconstruction and hence significant cost may be associated with
these modifications.
Chlorine Contact Tanks. The operator should investigate
the adequacy of the contact tanks and outfall. The contact
volume should be sufficient to provide at least 15 minutes
contact time at peak flows and a minimum of 30 minutes if the
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plant discharges to a shellfishing area. If this is not
available, construction of additional contact tanks should be
considered. The recommended practices for design of new chlorine
contact tanks are discussed in later portions of this chapter.
Short-circuiting may occur in the contact tanks if the channel
length-to-width ratio is significantly less than 40 or if the
baffling system does not promote even flow through the tank.
Short-circuiting occurs when dead spots or back eddies in the
tank reduce the effective contact volume and allow some of the
wastewater to flow too quickly through the tank. This results in
a reduced effective contact time and requires additional chlorine
for disinfection. The operator can identify a possible short-
circuiting problem by checking if the overall channel length-to-
width ratio in the tanks is less than 40.
The extent of a short-circuiting problem may be quanti-
tatively evaluated through dye testing. This procedure involves
introducing dye at the upstream end of the contact tank where the
chlorine solution is injected, observing the passage of dye
through the tank, and monitoring the effluent dye
concentration. In this manner, dead spots in the tank can be
identified, and the actual contact time can also be determined
and compared with the theoretical contact time and design
criteria. Alternative evaluation techniques include use of
tracers such as confetti, salt solution, or frequent measurement
of chlorine concentrations in the contact tank influent and
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effluent. However, the dye and confetti testing are advantageous
because the flow pattern in the contact tank is visibly
highlighted. If the testing indicates serious short circuiting,
then flow baffles and vanes could be constructed to direct the
flow, minimize dead spots and increase the effective contact
time.
Control Systems. Although automatic compound loop control
systems are complex, they offer a positive method for
continuously monitoring chlorine residual and minimizing chlorine
use. The compound loop system requires input signals from a flow
meter and from a chlorine residual analyzer. Generally, the
flow-proportional signal is used to control the feed-rate valve
and the residual chlorine signal to vary the vacuum differential
across the feed-rate valve. The proportioning pump or throttling
valve of a hypochlorite system can also be controlled by signals
from a flowmeter and chlorine residual analyzer.
An automatic control system is particularly advantageous
for optimizing chlorine use at smaller treatment plants where an
operator is normally present for one 8-hour shift. Unless the
plant is equipped with an automatic compound loop control system,
it is impossible for an operator working 8-hours per day to
maintain continuous control of chlorine residual. An automated
control system would be less expensive than providing operator
coverage 24-hours per day.
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Disadvantages of the compound loop system include its
cost, maintenance requirements of the residual analyzer and the
possible installation difficulties in an existing chlorinator or
hypochlorinator room. However, due to the additional degree of
chlorine residual control, this type of system is recommended for
large treatment plants (over 1.0 mgd) and at any treatment plant
where close control of the disinfection process is necessary to
minimize effluent chlorine residuals and protect aquatic life.
Dechlorination Systems. In some cases, protection of
particularly sensitive aquatic organisms may necessitate the
installation of a dechlorination system. For example, although
an optimized chlorination system may reduce typical residual
concentrations to 0.1 mg/1, a reduction factor of 20 would be
necessary to meet a receiving water criterion of 0.005 mg/1
within the allowable mixing zone. Particularly during periods of
low stream flow, this dilution factor may not be available.
The equipment used in a sulfur dioxide dechlorination
system is essentially the same as is used for chlorination.
These systems are discussed in greater detail in the next
section.
Criteria for Design/Future Expansion
General. The levels of coliform bacteria permissible in
receiving waters are specified by state regulatory agencies. The
coliform standards for the three states are summarized in
Table 6-1.
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TABLE 6-1. WATER QUALITY STANDARDS FOR COLIFORM BACTERIA
State
Use designation
Coliform Bacteria
Maine
Class A
recreation, water supply
after disinfection
not greater than 20
fecal coliform/100 ml
New
Hampshire
Vermont
water supply after dis-
infection; specifically
excludes wastewater
discharges
water supply with dis-
infection if necessary
not greater than 50
total coliform/100 ml
not greater than 100
total coliform/100 ml and
no fecal coliforms
attributable to domestic
or industrial discharges
Maine
Class B
recreation, water supply
after treatment and fish
and wildlife habitat
not greater than 60
fecal coliform/100 ml
New swimming, fish habitat
Hampshire and water supply after
adequate treatment
not greater than 240
total coliform/100 ml
Vermont bathing, irrigation, fish
habitat, water supply with
treatment and disinfection
not greater than 500
total coliform/100 ml or
200 fecal coliform/100 ml
Maine
Class C
boating, fishing, habi-
tat water supply and
contact recreation -
only if treated
not greater than 1000
fecal coliform/100 ml
New boating, fishing and in-
Hampshire dustrial water supply un-
less naturally occurring or
due to combined sewer overflow
not greater than 1000
total coliforms/100 ml
Vermont boating, fish and wildlife
habitat and industrial uses
not greater than 1000
fecal coliform/100 ml
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In contrast to these allowable receiving water concentra-
tions, typical bacterial concentrations in untreated domestic
wastewater are on the order of millions of coliform bacteria per
100 ml. The careful design of an efficient disinfection system
is necessary to achieve a sufficient bacterial kill to meet
receiving water standards without the use of excessive quantities
of chlorine. Minimizing the use of chlorine will decrease
operating expenses, and reduce the possibility of chlorine
causing harmful impacts on aquatic organisms. It is important to
take care in the design of chlorination feed, mixing, contact and
residual analysis systems, and it is equally vital that operation
and maintenance is frequent and thorough to maintain efficient
operation. Without adequate operation and maintenance including
calibration and cleaning, the investment of capital in efficient
design may be wasted.
Information on the design of efficient chlorination
systems is presented in this section so that as growth requires
the construction of new treatment plants and the expansion of
existing plants, the new chlorination systems can be designed and
constructed to reliably achieve low residual chlorine levels and
a thoroughly disinfected effluent.
Dosage Capacity. The chlorination system must have
sufficient capacity to reduce the number of coliform bacteria to
the levels required by the state water quality regulations under
worst case conditions (high flow and loads). Typical chlorine
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dosage ranges for treated domestic wastewater effluents are
listed below (Metcalf & Eddy, Inc. 1979; Great Lakes Mississippi
River Board of State Sanitary Engineers 1978)
Degree of Treatment Chlorine Dosage, mg/1
Primary Effluent 5-20
Activated Sludge Effluent 6-12
Sand Filter Effluent 4-6
Nitrified Effluent 3-6
The chlorine system should be able to provide at least these
dosage rates at peak design flows. In addition, the New England
Interstate Water Pollution Control Commission (NEIWPCC)
recommends providing a dosage capacity of 25 mg/1 chlorine at
design average flow (NEIWPCC 1980).
In addition to effluent disinfection, the chlorine system
and associated pipe system should be designed for: chlorine feed
to the plant headworks for odor control; disinfection of possible
bypassed flows; and for plant process controls such as sludge
bulking in an activated sludge plant or to eliminate filamentous
growths in filters.
Duplicate chlorinators, each capable of supplying the
design maximum dosage rate, should be provided. Although the
initial dosage rates may be very small relative to future peak
rates, the dosage system should be equipped with chlorine
solution flowmeters and regulators (rotameters) sized so that
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initial chlorine dosage rates will be near the midpoint of the
flowmeter scale. If the rotameter is sized only for future
dosage rates, it may be difficult for an operator to accurately
regulate or achieve low chlorine dosages. Therefore,
chlorinators should be specified with one rotameter for initial
low dosages and one for future peak rates.
Chlorine Injection and Mixing. Chlorine solution should
be injected into the wastewater flow either through a diffuser or
directly into the propeller of a mechanical mixer for
instantaneous and complete mixing. The diffuser may be a plastic
or hard rubber pipe with drilled openings at least 3/8-inch in
diameter. Velocities through the diffuser orifices should be high
(15 feet per second at peak flows) to assist in mixing.
The effective mixing of chlorine solution with wastewater
is accomplished by injecting the solution at a point where the
wastewater flow is turbulent. Turbulence may be induced by
constructing hydraulic jumps, over and under baffles, submerged
weirs, venturi flumes or by installing a mechanical mixer. A
disadvantage of mechanical mixers is the additional electrical
operating costs. When using a mechanical mixer, the flash mix
chamber should provide a maximum detention time of 30 seconds at
peak flow. The mixing system should be designed to minimize the
release of chlorine (chlorine stripping) to the atmosphere. Such
releases result in the use of additional chlorine, increase
costs, and are also a health hazard. Chlorine stripping may be
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minimized by 1) ensuring that the chlorine diffuser is as deep as
possible but at least two feet below the minimum wastewater
level, and 2) preventing turbulent flow after the chlorine
solution is mixed with the wastewater.
Chlorine Contact Tanks. The two most important factors in
the disinfection of wastewater are contact time and chlorine
residual. The chlorine contact tanks should have a sufficient
capacity to provide a contact time of 15 to 30 minutes at the
peak design flow with all tanks in operation. Thirty minutes
detention time is normally required for wastewater discharges to
shellfish areas (NEIWPCC 1980). New treatment facilities in
Vermont will be required to provide a 30 minute contact time at
peak flow. Increasing contact time will reduce the amount of
chlorine required for disinfection. The required tankage should
be provided by constructing at least two tanks so that while one
tank is out of service for cleaning or maintenance, chlorine
contact can continue in the other tank.
Because of the importance of adequate contact time, the
design of the contact tank must maximize plug flow conditions and
prevent short-circuiting. The reduced contact time which is
associated with short-circuiting necessitates the use of
additional chlorine to achieve the required disinfection. A
properly designed contact tank will minimize short-circuiting and
therefore also reduce chlorine usage. Effective plug flow may
also be achieved in long outfall pipes which always flow full.
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To minimize short-circuiting in the contact tanks, a
serpentine flow pattern is created by installing walls or baffles
to channel the flow through the tank. The ratio of channel
length to channel width should be at least 40:1 and may be as
high as 70:1. The side water depth in contact tanks ranges from
6 to 15 feet, and is typically about 7 feet.
In addition, it is important to design the contact tank so
that minimal solids settling occurs. Velocities at minimum flow
should be at least 0.2 feet per second.
Despite all precautions, some solids will invariably
settle out in the contact tank due to flocculation and low
velocities. Slime buildup may also occur on the walls. To
facilitate maintenance and cleaning (to remove the accumulated
solids), the tank floor should be sloped and a dewatering system
provided. Flushing hydrants should be located for use in washing
down the tanks and a scum skimmer should be installed before the
tank outlet.
Chlorination Equipment. Chlorine is available in several
forms but is most commonly applied as liquid/gaseous chlorine or
sodium hypochlorite. In a liquid/gaseous system, chlorine gas is
drawn from liquid chlorine storage at a controlled rate,
dissolved in water and injected into the wastewater. Dosage is
adjusted by means of a feed-rate valve calibrated in pounds of
chlorine per day. A hypochlorite system requires corrosion-proof
tanks for the storage of hypochlorite solution, chemical solution
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feed pumps to inject the chlorine solution and a feed-rate
valve to control the amount of chlorine used. While hypochlorite
systems can be installed in either large or small plants, because
of their safer operation, they are usually used in small
plants. Liquid/gaseous systems typically have a higher capital
cost but lower operating and maintenance costs than hypochlorite
systems.
Both systems have similar controls which may be used
either manually or automatically. In automatic mode, a system
which continuously converts wastewater flow measurements into a
control signal is used to regulate the chlorine feed rate. This
mode has the advantage of automatically modifying the chlorine
dosage as the chlorine requirement changes during the day with
varying wastewater flows. Automatic proportioning of chlorine
dosage to the wastewater flow can provide good residual chlorine
control if the chlorine demand remains reasonably constant.
However, chlorine demand typically fluctuates with
wastewater flow, contact time, temperature, pH, BOD, and
substances which react with chlorine such as ammonia and hydrogen
sulfide. Proper disinfection can best be achieved by
consistently maintaining the correct chlorine residual in the
effluent. A more precise method of maintaining a desired
chlorine residual is with the use of a loop control system. In
this system, a sample of chlorine contact chamber water is pumped
to a chlorine residual analyzer which amperometrically analyzes
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the sample for free chlorine residual. The analyzer sends a
signal to a chlorine solution feed rate controller which compares
the measured residual to the desired residual level set by the
operator and then adjusts the chlorine feed rate accordingly. A
signal from the wastewater flowmeter simultaneously adjusts the
chlorine feed rate to accommodate changes in flow. A recorder
may be installed to provided a permanent record of the chlorine
residual. This control system minimizes the amount of chlorine
usage to achieve and maintain the desired chlorine residual.
Because slime build-up in the sample lines can cause
significant error in residual measurement, it is important to
install these lines so that they can be easily cleaned (White
1972). In addition to frequent flushing of the sample lines with
a strong chlorine solution to kill organic slime, the analyzer
should be inspected and calibrated daily to ensure continued
accuracy of residual determination.
Dechlorination. As noted in Chapter 5, effluent total
residual chlorine concentrations resulting from existing
chlorination systems typically range as high as 4.0 mg/1. If the
effluent is discharged into waters where these levels of chlorine
may be harmful to aquatic life, it is necessary, after
disinfection, to remove the excess chlorine from the effluent.
This is commonly done by adding a reducing agent such as sulfur
dioxide to the chlorinated wastewater. The reaction of sulfur
dioxide with both free and combined chlorine residual is nearly
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instantaneous. The same techniques and equipment used for
liquid/gaseous chlorination may also be used for dechlorination
using sulfur dioxide. This includes sulfur dioxide storage,
sulfonators (similar to chlorinators), injectors, diffusers and
chlorine residual monitoring. Generally, sulfur dioxide is added
at a rate of 1.0 to 1.1 mg/1 per mg/1 of chlorine residual plus
an additional amount of sulfur dioxide in order to maintain a
sulfur dioxide residual of 0.2 to 0.5 mg/1. A capacity to dose 5
mg/1 sulfur dioxide at the peak design flow should be provided.
Excess sulfur dioxide dosages will result in extra chemical costs
and a decrease in dissolved oxygen in the effluent due to the
oxygen demand of sulfur dioxide. The sulfonator needs only a
flow signal if the chlorine residual analyzer is used to maintain
the chlorine residual at a constant level.
At small treatment plants (less than 1 mgd) dechlorination
could be more easily performed using sodium metabisulfate instead
of sulfur dioxide. This chemical is usually received in dry
form, dissolved to form a solution and injected into the flow by
a diaphragm pump. Approximately two gallons of water are
required per pound of metabisulfate. Dosage is controlled by a
signal from the chlorine residual analyzer. Sodium metabisulfate
is added at a rate of 1.5 mg/1 per mg/1 of chlorine residual.
The system should be designed to dose up to 5 mg/1 metabisulfate
at peak flow.
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Summary
The recommendations presented in this chapter were
developed based on information obtained through the questionnaire
survey which is described in Chapter 5. The questionnaire survey
is an excellent tool for obtaining statistics which describe
existing disinfection systems in a general sense. However,
specific recommendations for improving disinfection practices are
best developed through inspection of individual treatment
facilities and discussions with treatment plant operators to
obtain detailed information on system characteristics. There-
fore, the recommendations discussed in this chapter are necess-
arily not site specific. Nevertheless, these recommendations do
provide a comprehensive basis for developing and initiating
improvements in existing disinfection systems. As the existing
systems outgrow their useful lives, the information presented in
this chapter can be used in the design and construction of
efficient chlorination systems which minimize chlorine use and
result in non-toxic residual chlorine concentrations in the
receiving waters. It is important for the state agencies and
treatment plant operators to evaluate the existing chlorination
systems in the light of desired receiving water uses. In this
manner, it is possible to identify a variety of simple and
inexpensive corrective measures which can be employed immediately
to reduce chlorine usage and effluent residuals. Corrective
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measures to reduce chlorine use are presented in a brochure
contained in Appendix C.
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LITERATURE CITED
Great Lakes Upper Mississippi River Board of State Sanitary
Engineers, 1978. Recommended Standards for Sewage Works (10
State Standards).
Metcalf & Eddy, Inc. 1979. Wastewater Engineering: Treatment
Disposal Reuse, McGraw-Hill.
Metcalf & Eddy, Inc. 1982. Impacts of Wastewater Disinfection
Practices on Coldwater Fisheries (Draft). Prepared for U.S
Environmental Protection Agency, Region I, Boston,
Massachusetts.
New England Interstate Water Pollution Control Commission.
1980. Guides for the Design of Wastewater Treatment Works.
Sepp, E. and G.C. White. 1981. Manual for Wastewater
Chlorination and Dechlorination Practices. Prepared for
California State Water Resources Control Board.
Water Pollution Control Federation (WPCF). 1976. Technical
Practice Committee. Subcommittee on Chlorination of
Wastewater, 1976. Manual of Practice No. 4, Chlorination of
Wastewater.
White, G.C. 1972. Handbook of Chlorination, Van Nostrand
Reinhold Company.
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CHAPTER 7
CONCLUSIONS AND RECOMMENDATIONS
Coldwater Fisheries Hazard Analysis Procedure (CHAP)
The Coldwater Fisheries Hazard Analysis Procedure (CHAP)
offers a coherent and systematic approach for assessing the site-
specific impacts of wastewater disinfection practices on
fisheries of northern New England. CHAP is useful for
determining if dechlorination or alternative disinfectants are
necessary to mitigate adverse impacts due to chlorine's effects
on self-sustaining salmon and trout populations, put-and-take
fisheries, critical fishery habitat, and areas critical for
seasonal passage by salmon or trout. This systematic procedure
maximizes the use of existing information, but also enumerates
applicable methodologies for collection of supplemental data
(including water quality sampling, fish population assessments,
fish habitat mapping, and benthic invertebrate sampling) required
for detailed impact evaluation. Information from literature
review, field studies and detailed evaluation is used to address
the key issue - whether or not there are significant adverse
environmental impacts from the effluent discharge due to
chlorination. If chlorination impacts are significant, the CHAP
procedure prescribes specific mitigation measures for
evaluation. Alternative mitigation techniques include
dechlorination, outfall relocation, treatment process
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modification or the use of some other disinfection process (e.g.
ozone or ultraviolet radiation).
Worthfield Case Study
Based on the November 1982 sampling results, the fisheries
of the Dog River, Vermont were adversely affected by the
chlorinated effluent from the Northfield WPCP. The adverse
impacts extending more than 160 m downstream from the wastewater
treatment plant outfall were due to overchlorination from the
manual chlorinators used at the plant. These chlorinators, set
at their minimum rate, overchlorinated effluent at night when
wastewater flows at the plant decreased. The case study
recommended that the chlorinators should be modified to provide a
lower rate of chlorination, or automatic chlorinators should be
installed that are flow paced to the wastewater flow.
Amperometric titration was also recommended to provide more
reliable and accurate monitoring of effluent chlorine residual.
Randolph Case Study
The chlorinated effluent of the Randolph, Vermont WPCP had
little to no effect on trout populations but a measurable adverse
effect on the diversity and density of macrobenthos based on a
case study of the Third Branch of the White River conducted
during a low river flow period in July, 1983. Chlorine generally
decreased rapidly to less than 0.05 mg/1 within 50 m from the
outfall. This marked downstream decrease in chlorine
concentrations was probably due to rapid chemical decay of free
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residual chlorine and instream mixing and dilution. Although
detectable levels of TRC were found in the fish sampling section
just downstream (93 m) from the outfall, there were no
significant differences between trout population or biomass
estimates for sampling stations upstream and immediately
downstream of the treatment plant. A zone of passage was assured
at the outfall during the three days of sampling during low river
flow. Significant reductions in macrobenthic species diversity
and abundance, however, were noted about 150 m downstream from
the Randolph treatment plant. After minor repair of the
chlorinator, the chlorination system at the Randolph WPCP
operated reliably, and the class C coliform standards were met in
all samples collected downstream from the outfall.
Since few adverse environmental impacts were noted there,
few improvements were recommended at the Randolph WPCP other than
removal of accumulated sludge from the chlorine contact tanks.
However, certain minor improvements to the chlorination system
may be warranted to provide additional protection if an Atlantic
Salmon fishery is ever restored to the Third Branch of the White
River at Randolph. Increased longitudinal baffling in the
chlorine contact tank was recommended to improve disinfection
efficiency by lengthening contact times and would potentially
reduce TRC levels in the effluent. Addition of a chlorine
residual analyzer to the automatic chlorine feed rate control
system would assure that the least amount of chlorine would be
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used and guard against the possibility of overchlorination.
These minor improvements were recommended to help ensure the
success of future salmon restoration efforts on the Third Branch
of the White River.
Fewer adverse impacts were noted at the Randolph site
relative to those noted at the Northfield Vermont site. This was
due to the better instream mixing available in the Third Branch
of the White River at Randolph as well as the improved
chlorination system and effluent quality. The flow-paced
chlorination system at Randolph operated reliably and ensured
that overchlorination was not a significant problem as suggested
at the Northfield wastewater treatment plant.
Existing Disinfection Systems
Characteristics typical of chlorination systems at
treatment plants in northern New England were determined by
conducting a questionnaire survey and compiling the responses.
Major characteristics contributing to inefficient disinfection or
overchlorination of these plants included:
Effluent limitations not sufficiently stringent to
protect water quality.
Inadequate initial mixing systems.
Insufficient chlorine contact time, short-circuiting or
dead spots.
Lack of adjustment in chlorine feed possibly causing
overchlorination.
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Insufficient routine maintenance including equipment
cleaning and calibration.
Recommended Practices for Minimizing Excessive Chlorine Ose
State agencies and treatment plant operators should
evaluate the existing chlorination systems in light of desired
receiving water uses. In this manner, a variety of simple and
inexpensive corrective measures can be immediately identified and
employed to reduce chlorine usage and effluent residuals.
Techniques were recommended to improve existing chlorination
systems and minimize effluent chlorine residual concentrations.
Although some of the techniques and systems discussed in
Chapter 6 may not be cost-effective for all municipalities, as
the existing systems outgrow their useful lives, this information
will be useful in the design and construction of efficient
chlorination systems which minimize chlorine use and result in
non-toxic residual chlorine concentrations in the receiving
waters. A draft brochure (Appendix C) was designed to help
treatment plant operators to reduce chlorine use.
Implementat ion
The appropriate state agencies in northern New England can
adapt the Coldwater Fisheries Hazard Analysis Procedure (CHAP) to
meet their needs for assessing the site specific impacts of
wastewater disinfection practices on salmonid fisheries. CHAP is
used to determine if dechlorination or other measures might be
necessary to mitigate adverse impacts due to the effects of
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chlorine on aquatic resources. A special statewide interagency
group might be helpful to provide interaction between water
pollution control and fisheries interests, as typically, the
state water pollution control and fishery officials are members
of different departments or agencies. Interagency cooperation is
required since the environmental impact of disinfection practices
generally comes under the purview of more than one state agency.
The level of effort required to implement CHAP will vary
from site to site. Detailed evaluations such as those conducted
at Northfield and Randolph, Vermont will not be required at every
discharge site. Most dischargers will only require a preliminary
impact evaluation and a review of alternatives, which may require
little or no field work. The level of effort for the field study
portions of the detailed impact evaluation may vary from the
minimal effort at Northfield to the more comprehensive effort at
Randolph. For example, about 80 person-hours were required to
conduct the three day field study (not including data analysis
and report writing) at Northfield, Vermont. Almost 300 person-
hours were needed to conduct the week long field study at
Randolph, Vermont. This field effort at Randolph did not include
the time to process water quality or the macrobenthic samples.
The state should have the ultimate responsibility for
implementation of CHAP. However, certain portions of the
procedure could be conducted by the individual discharger. Even
if the discharger were responsible for most of the procedure, the
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state would retain oversight by making the initial decisions,
holding potential scoping sessions and reviewing and approving
the reports that are the required end-products of CHAP.
The specific recommendations developed in this study for
the Northfield and Randolph treatment plants should be
implemented. At Northfield these included the modification of
the chlorination system to allow a lower chlorine dosage rate and
the use of amperometric titration to provide more reliable and
accurate monitoring of effluent chlorine residual. Few
improvements were recommended at the Randolph WPCP other than the
removal of accumulated sludge in the chlorine contact tank, since
the chlorination system reliably maintained low effluent
concentrations of total residual chlorine during the July 1983
study. However, certain minor modifications such as increased
baffling in the chlorine contact tank and an automatic chlorine
control system including residual analysis may be warranted in
the future to further reduce chlorine use and to help ensure the
success of salmon restoration efforts on the Third Branch of the
White River.
The states should implement recommendations for minimizing
the potential for overchlorination at treatment plants as
described in Chapter 6. Funding for minor modifications, such as
an amperometric titrator, are not grant-eligible for federal
funding under the U.S. EPA Construction Grants Program. However,
7-7
-------
at this time major modifications such as additional chlorine
contact tanks should be grant-eligible.
The success of this program is ultimately dependent on
state agencies which must make a diligent effort to evaluate
individual treatment plants and educate plant operators about the
dangers of overchlorination and methods for reducing chlorine
residuals. The suggested text in Appendix C can be developed
into a brochure to distribute to individual treatment plant
operators. The brochure will increase operator awareness and
offer generic ways to improve existing disinfection systems.
7-8
-------
APPENDICES
-------
APPENDIX A - DIAGRAMMATIC HABITAT MAP OF FISH
SAMPLING SECTIONS IN THE DOG RIVER
NEAR THE NORTHFIELD VT, WATER
POLLUTION CONTROL PLANT (WPCP)
-------
PAGE NOT
AVAILABLE
DIGITALLY
-------
To help the State and the EPA obtain information on current chlorination
practices, please answer this questionnaire as completely as possible.
Any additional information or comments would be appreciated and space is
provided for sketches, descriptions, etc. Please return the questionnaire
by March 25, 1983 in the attached stamped envelope to: Meredith Durant
Metcalf & Eddy, Inc., 50 Staniford Street, Boston, Massachusetts 02114.
If necessary, please make any corrections to your address on the attached
mailing label. Your cooperation is appreciated.
CHLORINATION STUDY QUESTIONNAIRE
Description of Facilities
1. Facility Owner:
2. Facility Telephone Number:
3. Brief description of the treatment process:
(please include major process units and pre-
intermediate and post chlorination points)
4. a. What is the design flow? Annual average mgd, peak mgd.
b. What is the present flow? Annual average mgd, peak mgd.
5. When was the present disinfection system made operational?
6. Disinfection requirements imposed by State and/or Federal discharge permits:
Time of year disinfection is required
Total coliform level No./100ml. day average
Fecal coliform level No./100ml. day average
Residual chlorine mg/1
7. Type of disinfection presently used: chlorine gas .liquid
chlorine , hypochlorite , other
(if other, please specify type and disregard the remainder of this questionnaire).
-------
8. Please specify the following average characteristics for your facility
(or typical ranges if average values are not available).
a) Chlorine Chlorine
dose mg/1 residual mg/1
b) Effluent Concentrations
BOD5 mg/1 TSS mg/1
NH3 mg/1 PH
a. Where is chlorine solution fed: pipeline flowing full , open
channel , flume , manhole or chamber , entrance
to contact tank , other (please describe).
b. If chlorine solution is fed into a manhole or chamber what are
the dimensions
10. a. Are diffusers provided for solution feed? Yes , No .
b. If yes, please provide a cross section which shows the type and location.
c. In cases other than pipelines flowing full what is the average depth of
flow above the diffusers? .
11. How is initial mixing achieved: flume , hydraulic jump ,
turbulent pipeline , submerged weir , over-and-under
baffles , mechanical mixer , other (please specify)
12. If contact is provided using a tank, please complete the following:
a. Number of tanks provided ,
how many tanks are presently used .
b. Dimensions of each tank; length , width , depth
of flow , number of passes ,
width of each pass .
c. Type of effluent weir .
d. Weir length .
13. Has a dye tracer study ever been performed to determine the actual contact
time provided in the tank: Yes , No .
If yes, please describe the results including flow rate and measured
contact time.
14. If an outfall provides contact time, please describe the following
outfall characteristics:
a. Size: Length:
b. Is the pipe fully submerged: Yes , No
-------
15. a. Are there provisions for dechlorination of your effluent: Yes , No
b. If so, what process is used .
c. Dose rate: actual mg/1, design (maximum) mg/1.
16. How often is routine maintenance performed on the following equipment:
(where applicable)
Evaporator Chlorinator
Hypochlorite feed pumps Residual Analyzer
Mixing equipment Contact tank
17. Please provide information on emergency operation of the disinfection
system:
a. Is emergency power available? Yes , No .
b. Is there a disinfection system failure alarm? Yes , No .
c. How many disinfection system failures have occurred in the last
twelve months?
d. Is there a backup chlorination system? Yes , No .
e. If yes, please describe how it is actuated:
18. If you use liquid chlorine, please complete the following:
number of evaporators , size lb/day.
19. a. If you use chlorine gas or liquid, please complete the following:
1) How many chlorinators are provided: .
2) What size is each unit: .
3) How many lb/day of chlorine is presently used:
4) What is the lb/day usage based upon: scale readings
feed rate over 24 hours , other
(please describe).
-------
20. a.
b.
c.
5) If available, what is your average lb/1000 gal. usage:
6) Where does your injector water come from:
b. If you use hypochlorite, please complete the following:
1) What grade solution is supplied:
_percent.
2) What is the volume of each delivery:
Storage tank volume:
3) How many gals/day are presently used:
How can you control the feed rate: manual , automatic
both .
If both, which do you presently use: manual , automatic
If automatic control is provided and you do not use it, please
explain why:
21. If control is manual, how many adjustments are made per day:
22. If control is automatic, how is feed rate paced:
flowrate only , flowrate paced with trimming by residual
analyzer , other (please describe)
23. If feed rate is paced by flowmeter, is the reading on:
influent flow , effluent flow , other (describe)
24. a. If a residual analyzer is used, where is the sample collected from:
b. What type of analyzer is used:
c. What is the estimated travel time from the sampling point to the
analyzer unit: min.
d. If travel time is not known, please answer the following:
Pipe size Pipe length
Pumping rate
e. How often is the analyzer calibrated: (please describe method)
-------
25. a.
If a residual analyzer Is not used, how is the residual measured:
amperometric
DPD colorimetric
, DPD titrimetric
, other (please describe)
b. How often are residual levels monitored:
c. What is the usual time lapse between sample collection and residual
measurement:
27. Please provide any general comments on the systems efficiency, problems
with operation, suggestions for improvements or other aspects.
28. On a separate sheet, please sketch your disinfection process (include
chlorine feed points, location of initial mixing, location of residual
sampling points). Also show the contact facility including location
of baffling, inlet and outlets for flow and any areas where flow seems
to stop or eddy. Alternatively, provide a photocopy of the construction
record drawings for the disinfection system or the disinfection
schematic from the O&M manual.
26. a. Do you analyze effluent for coliform levels: Yes
, No
b. If yes, do you test for total
How often are measurements taken
»
do you test for fecal
-------
SUGGESTED TEXT OF BROCHURE
DESCRIBING METHODS TO MINIMIZE
EXCESSIVE CHLORINE USE
-------
METHODS TO MINIMIZE THE
USE OF CHLORINE IN
WASTEWATER TREATMENT
WATER POLLUTION CONTROL AGENCY
STATE OF
CITY , STATE
PftODtXXD IN COOPERATION WITH
DA ENVIRONMENTAL PROTECTION AGENCY
REGION 1
ENVIRONMENTAL EVALUATION SECTION
BOSTON. MA 02203
22 DECEMBER 1983
-------
Introduction
The purpose of disinfection is to destroy disease-causing
organisms (pathogens) before the wastewater is discharged to the
receiving water. The organisms of specific concern include
protozoans, bacteria and viruses which are generated by humans
and discharged with their waste products into the wastewater
collection and treatment system. These organisms must be
destroyed or rendered harmless to minimize the transfer of
disease or infection from one individual to another. In the
United States wastewaters have generally been disinfected with
chlorine since it is effective and has been less costly than
other disinfection methods.
The effectiveness of the disinfection system is measured
by determining the number of fecal coliforms in a sample volume
of disinfected plant effluent (MPN/IOOml). Fecal coliforms are
used as indicators of the sanitary quality of water because these
bacteria, which originate only in the digestive tracts of warm-
blooded animals, are more resistant to the effect of
disinfectants than most of the pathogens. Therefore, destruction
of these fecal coliform bacteria indicates that the disease-
causing pathogens have also been destroyed.
The effectiveness of chlorine as a disinfectant depends
upon its concentration, the degree of mixing, the contact time,
the types of organisms present and the physical and chemical
properties of the wastewater.
Substances in the wastewater such as organics and
suspended solids consume chlorine, that is, they have a chlorine
demand. This chlorine demand must be satisfied before any
chlorine is available for disinfection purposes. The chlorine
dosage, therefore, must be sufficient to satisfy both the demand
and provide sufficient residual for disinfection. Effectiveness
of organism kill generally increases at higher chlorine dosages
and concentrations, longer contact times, higher temperatures,
lower pH's, and with lower wastewater suspended solids, organics
and ammonia-nitrogen concentrations.
-------
In recent years, wastewater disinfection practices have
been the subject of increasing public concern because chlorine
residual compounds have toxic effects on fish and other aquatic
organisms. In addition, chlorine can combine with organics in
the effluent to form chlorinated hydrocarbon compounds. These
compounds, suspected of causing cancer, are a cause for concern
for downstream users who reuse the receiving water for drinking
water supply. Many states, including Maine, New Hampshire and
Vermont, are encouraging seasonal chlorination where possible, to
reduce the discharge of chlorine compounds during the winter and
reduce operating costs at the treatment plants.
The best way to minimize the introduction of chlorine
products to the environment is to first improve the efficiency of
the entire treatment system. Because more chlorine is required
to disinfect effluent which is high in solids or organics, it is
important that the treatment system be operated to produce the
best quality effluent possible prior to disinfection. The
disinfection process can then be improved using the information
in this brochure to achieve the required degree of disinfection,
as measured by coliform kill, with less chlorine. The result
will have a two-fold benefit. The amount of potentially harmful
chlorine products introduced to the environment, will be reduced
and cost savings to treatment plants will result as the chlorine
usage is decreased. The purpose of this brochure is to provide
operators with the information necessary to reduce the use of
chlorine by ensuring that the chlorination process is
efficient. Disinfection systems typically consist of several
component systems which must be properly designed, installed and
maintained to minimize chlorine use. These systems are as
follows:
Feed rate control
Initial mixing
Chlorine contact
Residual analysis
Operating records
Each of these systems is discussed in this brochure.
-------
Peed Rate Control
An automatic control system can be used to maintain
continuous control of the chlorine residual concentrations. This
system includes a residual analyzer which continually measures
residual concentrations, a compound loop chlorinator and a flow
signal. The chlorine feed rate is set (paced) according to the
wastewater flowrate and adjusted (trimmed) by a signal from the
residual analyzer. For example, if the residual analyzer
measures an effluent residual concentration above the pre-
determined set point, the chlorine feed rate is automatically
adjusted to reduce the residual concentration usually by closing
a motorized valve in the chlorinator. This level of control is
important because a change in flowrate will always alter the
amount of chlorine required for disinfection, but the chlorine
demand can also change without a change in flowrate.
Other types of automatic control systems pace chlorine on
the basis of wastewater flowrate only. In other words, as the
flowrate increases or decreases, the chlorine feed rate increases
or decreases accordingly. These flow-proportional systems do not
use a residual analyzer so the chlorine feed rate does not
automatically change as the chlorine demand changes. The
systems, which only pace chlorine feed rate to wastewater flow,
do not give as close control as systems where feed rate is also
trimmed by residual analyzer feedback. For best control of
chlorine dosage the system should be calibrated to the range of
flowrates which are presently occurring rather than the design
flowrates. If during periods of extremely high or low flow, the
flow-proportional system does not provide the correct dosage
rate, the operator should switch to manual chlorination.
-------
If the chlorine feed rate is not automatically adjusted
according to flow and residual concentrations, over or under-
chlorination may occur frequently. This is particularly true at
treatment plants where the feed rate must be adjusted manually.
At all treatment plants, the chlorine control and feed
systems should be checked daily for leaks, blockages, and to
maintain proper settings. Operators using manual chlorine feed
systems should check the residual concentration several times
each day, particularly during low flow periods, and adjust the
feed rate accordingly.
The chlorinator rotameter should be properly sized for the
actual daily chlorine dose required. For example, if a plant has
a required dosage rate of 20 lb/day, a rotameter with a maximum
capacity of 50 lb/day would provide more control and waste less
chlorine than a rotameter with a capacity of 200 lb/day. Using
an oversized rotameter, it will be difficult to accurately
maintain the dosage in the desired range, and overchlorination
could occur frequently. The operator can obtain a new rotameter
by contacting the chlorinator service representative. The
operating records should be studied to determine the present
average and peak chlorine usage. The new rotameter(s) should be
selected to supply these chlorine requirements. Rotameters are
inexpensive (less than $500) and can be easily installed by the
operator. Through proper dosage control, the use of chlorine can
be reduced and cost savings will result.
-------
Initial Wising
Rapid and thorough mixing of chlorine solution with
wastewater is critical to achieve effective disinfection.
Initial mixing is best accomplished by injecting the chlorine
solution through diffusers at a point where the wastewater flow
is turbulent. Mechanical mixers, flumes or over-and-under
baffles are commonly used to create turbulence. Nixing should be
completed before the flow enters the contact tank. Otherwise,
chlorine will be wasted.
If the area of initial mixing is visible, the efficiency
of mixing may be checked by inspection. If the mixing area is
not visible or mixing appears to be inefficient operators can
also check the efficiency of mixing systems by collecting a
series of grab samples at several points downstream of the point
of chlorine addition. The sample points should be located in a
line which forms a right angle with the line of flow. These
samples should be analyzed for residual chlorine concentration in
the plant lab. If the samples contain approximately the same
amount of chlorine, this indicates the mixing system is
effective. If the chlorine concentrations vary widely between
samples, this indicates that initial mixing is inefficient. The
efficiency of initial mixing should be tested periodically.
-------
It is also important to minimize the release of chlorine
gas to the atmosphere (chlorine stripping). Chlorine stripping
not only wastes chlorine but it is also dangerous because
chlorine gas is toxic and corrosive. It can endanger the plant
staff and damage equipment and structures. If the operator
notices excessive chlorine odor, equipment and/or structural
corrosion near the point of chlorine injection, this may indicate
chlorine stripping. Chlorine stripping can be reduced by
ensuring the chlorine diffuser is at least two feet below the
minimum wastewater level and preventing any additional turbulence
after mixing (such as dropping into an effluent pump station wet
well).
Several modifications can be made to improve initial
mixing. If space and hydraulics permit, constructing a hydraulic
jump, over-and-under baffles, a submerged weir or venturi flume
will improve initial mixing. Initial mixing can also be improved
by installing a mechanical mixer at the point of chlorine
injection. To obtain a mixer, the operator should contact a
manufacturer's representative and provide him with the
requirements of the service, including dimensions of the mixing
area. Normally, mechanical mixers have a low power requirement
(on the order of 3 hp), but it is important to check that the
plant can provide this additional power if a mixer is
installed. Engineering assistance will generally be needed to
effectively improve initial mixing.
-------
Chlorine Contact
The contact system should provide a minimum of 15 minutes
contact time at peak wastewater flows. Plants discharging to a
shellfishing area are required to provide 30 minutes contact time
at peak flows. It is important that all portions of the flow
receive equal contact time (plug flow). Short-circuiting, which
occurs when some of the flow passes through the tank more quickly
than other portions of the flow, decreases the effectiveness of
disinfection and may require the use of extra chlorine.
The operator can evaluate the contact tank by adding
confetti to the influent end of the tank. By watching the
movement of the confetti, flow patterns and/or dead spots on the
water surface can be observed.
The operator can also evaluate the contact tank by
conducting a dye test. Rhodamine WT is a fluorescent dye which
is typically used. The dye is added to the wastewater at the
point of chlorine injection (or at the next convenient upstream
point). By watching the flow of dye through the tank, the
operator can identify flow patterns and observe any dead spots or
eddies. The minimum contact time can be determined by measuring
the length of time between chlorine addition and the first
appearance of dye in the contact tank effluent. If the dye is
obtained in solid form, it should be dissolved in water prior to
use. Alternatively, a fluorometer (device which measures dye
concentration) can be used to measure dye concentrations in the
effluent at periodic intervals. By making a graph of the
measured dye concentrations versus elapsed time, the average
contact time can be estimated as the time at which the largest
dye concentration is measured.
-------
The contact time(s) determined through these tests are
associated with the specific wastewater flow rates occurring at
the time of testing. The contact time will decrease as the
wastewater flowrate increases. Dye testing should be conducted
at times of high wastewater flowrates to best estimate the
contact time at peak flowrates. If the contact time at peak flow
is estimated to be less than fifteen minutes, the possible
upstream relocation of the diffusers should be considered to
provide additional contact time. The long-term and expensive
solution to the problem of inadequate contact time would be
construction of an additional contact tank.
If the dye test results show dead spots or eddies which
disturb the flow pattern, additional longitudinal baffles can be
constructed to divide the tank into long narrow channels. The
construction of channels will improve the flow pattern and may
increase the contact time. The baffling should be installed to
form channels with a total length at least 40 times more than the
channel width. If chlorine solution is thoroughly mixed with the
wastewater upstream of the contact tank, the baffles can be
constructed of wood, fiberglass or PVC. However, it will be
necessary to take the tank out of service during installation.
If chlorine solution is added directly to the chlorine contact
tank, the baffles should be constructed of concrete.
Chlorine reacts with suspended solids in the wastewater,
causing the solids to settle out of solution and accumulate on
the bottom of the tank. Unless removed, these solids will exert
a chlorine demand and reduce the efficiency of disinfection. The
tank(s) should be checked frequently for solids or slime build-
up, and cleaned if either occurs.
-------
Residual Analysis
Chlorine residual analysis provides important information
which can be used to control the chlorine feed rate and it is
important for compliance with effluent permits. To maintain
effluent chlorine residuals and effluent coliform concentrations
at or below the desired levels, residual measurements (analysis)
should be more frequent. It is important to check the chlorine
residual at times when the wastewater flowrate is changing,
particularly as flows decrease. Residuals should be measured
more frequently at primary plants than at secondary plants.
An automatic analyzer is advantageous because residual
concentrations are continually monitored. However, daily
calibration of the analyzer is important. A grab sample should
be collected from the effluent and tested in the lab using the
amperometric titration procedure for total chlorine. If the lab
results differ significantly from the analyzer reading, the
analyzer should be calibrated.
If an automatic analyzer is not available, the iodometric
method with amperometric titration to determine the end point is
reliable, convenient and capable of accurately determining very
low residual concentrations. Although amperometric titration
systems cost about $1,000, this cost can easily be recovered if
the chlorine use is reduced with more accurate information on
residual chlorine levels. The DPD colorimetric test also
provides good results although turbid effluent may interfere with
the results. The orthotolidine method should not be used for
determining residual concentrations. This method cannot
accurately determine low residuals, it is unreliable and is
adversely affected by many conditions.
If analysis indicates chlorine residual concentrations are
exceeding the desired levels and if effluent coliform
concentrations are less than the permit levels, the chlorine feed
raf.P flhnnlH t-nrnpd Hnun .
-------
Operating Records
Whenever the chlorine residual concentration Is measured,
It should be recorded In the plant operating logs. Other readily
available data such as wastewater flowrate or time of day should
also be recorded. It is also important to record the amount o£
chlorine used each day as well as to describe any corrective
procedures.
By keeping records of chlorine usage, wastewater flows,
residual concentrations, etc., the operator will be familiar with
normal operating conditions and will be able to quickly recognize
trends away from the normal condition. Once a problem has been
identified, it may be possible to review past operating records
to quickly determine an effective solution. Although keeping
operating records is required by the state, these records also
provide the operator with important information which can be used
to identify and correct potential problems.
-------
FOR FURTHER INFORMATION
CONTACT:
NAME, ADDRESS «
PHONE NO. OF STATE
CONTACT
-------
APPENDIX D - MACROBENTHIC DATA FROM
THE RANDOLPH, VERMONT CASE
STUDY
-------
TABLE D-1. MACROBENTHIC SPECIES COMPOSITION, NUMERICAL ABUNDANCE AND DIVERSITY
FROM FOUR SECTIONS OF THE THIRD BRANCH OF THE WHITE RIVER, RANDOLPH VERMONT, JULY, 1983
Section A Section B Section C Section D
Taxon "1 2 3~ 1 2 5~ ~I 2 5~ ~~1 5
Plecoptera
Perlidae (nymph)
Neoperla clymeme
Bpheoeroptera
Baetidae (nymph)
Species A
Baotis c£.
2
1
2
5
1
3
3
Epheraerellidae (nymph)
Druneila (Ephemerella ) comuta
16
24
25
3
1
2
1
1
3
Drunella (Ephemerella) lata
1
1
1
2
Serratella (Bphemerella) serrata
1
1
1
2
1
19
6
21
12
Heptageniidae (nymph)
Heptagenia cf.
1
5
4
2
5
Epeorus cf.
1
4
1
1
Rhithrogena cf.
3
1
Leptophlebiidae (nymph)
Paraleptophlebia cf.
31
56
40
1
4
1
5
Siphlonuridae (nymph)
isonychia cf.
1
1
7
4
3
1
1
2
Trlcboptera
Brachycentridae (larvae)
Brae hyc erttrus n i g cos oaa
35
22
97
1
2
5
3
5
25
1
1
2
Glossosomatidae (larvae)
Clossosoaa Sp.
1
1
1
2
Hydropsychidae (larva)
Hydropsyche sp.
55
42
42
1
9
24
2
11
13
18
Ph ilopotamidae (pupae)
Dolophilus sp.
1
Trentonius distinc tus
1
Polycentropodidae (larvae)
Species A
3
6
Unknown family (pupae)
Species A
1
1
1
1
1
1
1
Species B
2
Megaloptera
Corydalidae (larvae)
N lgrortia sp. 2
Coleoptera
Elmidae
sceneJmis sp. (larvae) 11 15 3 3
Steneiais sp. (adult) 11 11 1 4 2 2
Dlptera
Chironomidae (larvae) 6 1 7 2 1 10 7 16 10 17
Tipulidae (larvae)
Hexatoaa sp. 1 2 2 27 21 4 5 4 4 2 4 8
Species A 1
Diversity Index (D) 0.79 0.70 0.74 0.39 0.64 0.72 0.00 0.77 0.79 0.89 0.81 0.8
§ Abundance is reported as a number of individuals per 2 ft6 (0.18 m ).
-------
APPENDIX E - WRITTEN COMMENTS RECEIVED
ON DRAFT REPORT
-------
STATE OF MAINE
Department of Environmental Protection
'%7a™leT\*1v MAIN 0FFICE: RAY BUILDING, HOSPITAL STREET, AUGUSTA
*'C Of W* mail ADDRESS State House Station 17, Augusta, 04333
JOSEPH E. BRENNAN HENRY E. WARREN
GOVERNOR COMMISSIONER
December 15, 1983
I METCALF & EDDY
hle SUB I.
Kenneth Wood
U.S. Environmental Protection Agency
DEC 9. 21983
JFK Federal Building j D>*> vi s s
Boston, Mass 02203
Dear Ken:
Following is a list of comments I made to you over the phone regarding the
draft document "Environmental Evaluation of Wastewater Disinfection Practices
in Northern New England":
CHAPTER II,
1. Metcalf and Eddy (M & E) has still not proposed any decision criteria
for various steps of the procedure (see my letter of March 29, 1983 as
they have not addressed any of those comments). It was my hope that
the agencies involved could come to some consensus about criteria for
chlorine use, however, M & E has not produced the information needed.
2. M & E has not used any of the data and information gained from the two
case studies to revise CHAP. As CHAP stands now (in its original
form), it has been shown by the case studies to be unworkable. It ,„is
obvious to me that the fish studies are not sensitive enough to detect
impact. Water quality data also appears insufficient. M & E should
not continue to propose this procedure if they can't make it work with
their own case studies. This agency could not adopt CHAP in its
present form.
3. I think there should be some "default" values proposed where the CHAP
process could be avoided. For instance, at what predicted residual
concentration is chlorine considered safe and at what level would it
be considered an unmitigable impact. This CHAP analysis should be
used only within the "gray" area between these values to determine if
an impact really does occur.
4. I think the habitat evaluation is unnecessary except for the selection
of sample sites.
5. What portion of a stream is adequate for passage (<0.05 mg/1)? Maine
law allows only 1/4 of any stream width to violate water quality
criteria for purposes of a mixing zone. Zone of passage may be
handled much better through this type of regulation. o q
• Portland •
REGIONAL OFFICES
• Bangor•
• Presque Isle •
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CHAPTER III,
1. I do not see any changes between this draft and the draft results that
were submitted last spring. As I recall there were numerous comments
critical of that work particularly in reference to the very
speculative nature of their conclusions.
CHAPTER IV,
1. It appears that fish sampling is too insensitive to detect effects
even where there is a measureable residual. I would suspect that the
notoriously high variance associated with sampling fish may be an
insurmountable problem.
2. It appears that the detection limit for their NH3 analysis is 0.1
mg/1. This is five times the EPA recommended criteria.
3. Macroinvertebrates look more promising as a technique but it appears
their sampling effort was insufficient to make a judgement(see my
letter, May 12, 1983). Taxonomy must be consistent for the entire
sample in order to do diversity measures. Other analytical techniques
should also be used. Diversity has a number of known weaknesses and
should not be considered the definitive method of analysis.
I am having our Operations and Maintenance staff review Chapters V and VI.
Any additional comments will be forwarded to you. At this point I think there
is still substantial need for improvement before this document shoud be
accepted. They appear to have ignored comments which have been submitted in
the past.
Sincerely,
Dave Courtemanch
Biologist
Division of Environmental Evaluation
and Lake Studies
ad/
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617-437-1534
HAGOP BOGHOSIAN, Chairman
FRED R. GAINES, Vice - Chairman
JOHN B. CASAZZA. TREASURER
RONALD F. POLTAK, EXECUTIVE DIRECTOR
December 16, 1983
CONNECTICUT
MAINE
MASSACHUSETTS
NEW HAMPSHIRE
NEW YORK
RHODE ISLAND
VERMONT
-Yv
\"
Kenneth H. Wood
Environmental Evaluation Section
U.S. Environmental Protection Agency
J.F.K. Federal Building
Boston, MA 02203
RE: Wastewater Disinfection Study
Dear Ken:
The following are comments on the operator's booklet for minimizing
the use of chlorine in wastewater treatment. These comments are from
Kirk Laflin and the staff at the New England Regional Wastewater Institute
(NERWI) following their review of the draft booklet this week. I relayed
the comments to Meredith Durant, Metcalf and Eddy, this morning over the
phone.
l//page 1, line 4: protozoans are also organisms of concern
~ page 2, following first paragraph: insert a section on seasonal chlorination
including the reasons, costs savings, which States are practicing or
planning to implement.
page 2, after break: the best way to minimize the introduction of chlorine
products to the environment is first to make sure that the effluent
from the secondary clarifier going into the disinfection process is
of high quality i.e. low solids content. Stress the importance of
reducing solids content of waste flow before disinfection.
page 3: the flow analyzer should be calibrated using normal daily flows
rather than design flows; it should be noted that chlorine pace is
inaccurate at very low or very high flows, during which the operator
should switch to manual chlorination.
v-^page 5, par. 2: typo "mixing".
^spage 7, last par., last line: remove last line recommending use of salt
solution to evaluate the chlorine contact tank. The higher specific
gravity of the brine solution interferes with its ability to mix
with the secondary effluent and produces a high percentage of error
in evaluation results.
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Kenneth Wood
December 16, 1983
Page 2
page 9, par. 1, line 1: chlorine residual analysis ^s important.
page 9, par. 3: this section on chlorine testing procedures should be
expanded to describe the advantages and disadvantages of each
method, including factors of reliability, cost, and ease of
analysis (i.e. amperometric techniques are reliable, expensive
but may save money in the long run). Explain why the orthotolodineu"
method should not be used. Since some States rely on coliform
results as a regulatory control measure, add a section on what
testing procedures are recommended by EPA for coliform analyses.
Thank you for the opportunity to comment. Any questions regarding these
comments should be directed to Kirk Laflin, Director of NERWI, 2 Fort Road,
South Portland, ME 04106, (207)767-2649. The Commission is very interested
in distributing this material to operators through NERHI, so please keep us
advised of your publication schedule.
Attached is a list of suggested recipients of the final published report.
Environmental Evaluation of Wastewater Disinfection Practices in Northern
New England, including State agency O&M contacts, State agency water quality/
biologist contacts, and wastewater treatment plant operators' associations
in the region. (Some of our suggestions for State recipients in ME, NH and VT
may duplicate suggestions forwarded to you by those States.)
Sincerely,
JEB:jpc
Encls.
CC: Durant, M&E
K. Laflin, NERWI
Jennie E. Bridge
Environmental Scientist
~~: 031011 A3 SfJV
"Aa -o c:
£8616 1030 ,
K.S
'ONI 'AQ03 9 J1V313W
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