U.S. DEPARTMENT OF
HEALTH, EDUCATION, AND WELFARE
Public Health Service
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DISCRIMINATION PROHIBITED—Title VI of the Civil
Rights Act of 1964 states: "No person in the United States shall,
on the ground of race, color, or national origin, be excluded from
participation in, be denied the benefits of, or be subject to dis-
crimination under any program or activity receiving Federal fi-
nancial assistance." Therefore, the waste treatment works, like
every program or activity receiving financial assistance from the
Department of Health, Education, and Welfare, must be operated
in compliance with this law.
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Pollutional
Effects
of Stormwater
and Overflows
From Combined
Sewer
Systems
A PRELIMINARY APPRAISAL
U.S. DEPARTMENT OF
HEALTH, EDUCATION, AND WELFARE
Public Health Service
Division of Water Supply and Pollution Control
NOVEMBER 1964
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PUBLIC HEALTH SERVICE PUBLICATION No. 1246
1964
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Contents
Page
SUMMARY v
INTRODUCTION 1
PLAN OF INVESTIGATION.... 4
FUNDAMENTAL DATA FROM
ENGINEERING REPORTS AND
QUESTIONNAIRES 5
CHARACTERISTICS OF COM-
BINED AND STORMWATER
FLOWS 5
Review by Others 5
Data From Engineering Reports and
Completed Questionnaires 10
1. Quantity of Combined Overflows
and Stormwater 10
2. Damages Attributed to Stormwater. 14
3. Water Uses Affected by Overflows... 15
Data From Special Studies 15
1. East Bay Metropolitan Utility
District 15
2. Chicago, III 16
3. Cincinnati, Ohio 18
4. Washington, D.C 18
5. Los Angeles Flood Control District. . 19
Data From Studies by Others 19
ADDITIONAL DATA FROM MU-
NICIPALITIES 20
Land Use 20
Basic Data and Hydraulics for
Interceptors 20
Stream Quality 21
Rainfall and Effects on System 21
Metering of Flow and Regulatory
Devices Used on Combined Systems. 22
Infiltration 23
Para
REMEDIAL METHODS 24
Primary Methods 24
Alternate Methods 25
1. Additional Sewer Capacity 25
2. Control of Infiltration 25
3. New or Enlarged Treatment Plants. . 26
4. Holding Tanks 26
3. Lagoons, Ponds, Lakes 26
6. Guttering Inlet Retention and Street
and Roadway Retention 27
7. Disinfection 27
8. Improved Zoning and Land Use
Control 27
9. Regulation, Diversion, and Moni-
toring 27
Studies by Others 27
COSTS 28
Complete Separation 28
Partial Separation 29
Unit Costs for Individual Separa-
tion Items 29
Alternate Methods 29
1. Holding Tanks 29
2. Chlorine Contact Tanks 30
3. Lagoons, Ponds, and Lakes 30
4. Other Storage Methods 31
5. Other Treatment Methods 31
6. Miscellaneous Methods 31
DISCUSSION 31
CONCLUSIONS 33
RECOMMENDATIONS 34
REFERENCES 34
APPENDIX 37
iii
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Summary
Increasing urban development accom-
panied by progressively more stringent de-
mands on water quality for all uses makes it
necessary to examine the various sources of im-
pairment to water. One of the important
sources which has lacked attention is the storm-
water and overflow from combined sewers.
This situation precipitated a preliminary study
to define the problem and examine existing and
possible solutions along with cost analyses.
Four fundamental questions guided the study
which sought to learn (a) quantity and quality
of the overflows; (b) effects on streams, water
uses, and users; (c) adverse effects, and if any,
existing or suggested control measures and their
effectiveness; and (d) costs necessary for
control.
The study revealed that the quantity of
overflows is significant in terms of annual aver-
age and particularly during times of storms.
Some 59 million people live in U.S. communi-
ties now served by sewer systems which allow
overflows. The annual average overflow is
estimated to contain 3 to 5 percent of the un-
treated sewage and, during storms, as much
as 95 percent of untreated sewage. Storm-
water quantities are in addition to these
amounts. The quality of the overflows reflects
a high degree of pollutional load to water
courses as measured by the usual standards of
biochemical oxygen demand, coliform orga-
nisms, solids, etc. Stormwater alone was dem-
onstrated to carry significant amounts of pollu-
tional load, particularly in the early portions
of storms when a flushing action occurs.
All types of water use were found to be af-
fected and reports of various types of damage
were common, although the job of assigning
finite limits in terms of monetary loss is largely
undone. Precise information on effects was
limited but many reports are available showing
that consumptive and recreational uses of water
receiving stormwater overflows are prevented
because of the frequency of storms and their
pollutional contribution.
Effects were found to be uniformly adverse
and it was learned that control measures do
exist. Complete separation of sanitary and
storm sewers and treatment is now considered
to be the ultimate solution. This includes sepa-
ration of all sources of stormwater from the
sanitary system. It is established that the
separated sanitary wastewater requires treat-
ment, and there is a distinct possibility that
stormwater too may require treatment under
some circumstances. However, at this time
there is insufficient information available to
establish specific guidelines for such require-
ments. Partial separation of sanitary and
storm sewers and/or other contributing sources
such as roof drainage, areaway drainage, etc.,
also is used as a compromise. Other methods
short of complete separation include holding
tanks for stormwater, with or without disinfec-
tion, chlorine contact chambers, lagoons and
other land depressions, increased storage in
sewers and accompanying structures, increased
or new treatment capacity, control measures
within the sewer system, control of zoning and
land use, disinfection alone, and control of in-
filtration. Only a few of these methods have
had actual practice. Others have been consid-
ered but remain to be evaluated. Evaluation
of the effectiveness of all the methods is lacking
or incomplete, primarily because of the scarcity
of available sites and because of the complex
nature of such evaluation. However, many of
the methods appear promising and all should
be investigated, in view of the seriousness of
the problem.
Completely satisfactory cost estimates were
not available but it appears that to provide
complete separation throughout the country the
order of magnitude would be in the $20-30
y
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billion range. Partial separation would cost
a substantial percentage of this figure and all
alternate methods, for which data were avail-
able indicate somewhat lower costs, yet would
be in the multibillion dollar range.
In assembling the cost information no con-
sideration was given to the monetary losses
which would be borne by communities, individ-
uals, businesses, and/or industrial establish-
ments as the results of extensive physical incon-
veniences occurring during construction in
changeover periods. Such losses could be sub-
stantial; for example, retail businesses would
find their market limited during the time streets
are closed to traffic.
None of the basic questions was answered
to the extent that corrective plans of action
could be recommended. However, sufficient in-
formation was found to confirm that the entire
problem is of major importance and growing
worse with increasing urbanization and water
demands. Therefore, concentrated efforts are
necessary to fill in the missing information and
to learn what corrective measures can be applied
to provide the greatest protection at least cost.
Present and long-range effects are involved.
Corrective measures will not happen in a short
time nor can the investigative job be accom-
plished quickly. Therefore, there should be
prompt initiation of a continuing investigation
on a scale which will provide practical results
that can be translated into actual practice with
minimum delay.
VI
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Introduction
Historically the development of our
Nation's sewer systems has followed a general
pattern. Communities were invariably estab-
lished on water courses for a variety of reasons,
such as transportation, water supply, and a
source of power. Diversion of stormwater was
the earliest concern of these communities. Open
ditches were used first and later closed sewer
systems were developed. Discharges were made
directly to watercourses, usually at many points.
In general they followed the most accessible
gravity route. These developments were prior
to the installation of public water supplies.
As public water became available and the
water carriage principle for removing waste
from the household was adopted, it was neces-
sary to collect and dispose of the wastewater.
To accomplish this the existing storm sewers
were used to carry the sewage in addition to
stormwater. Thus, during storms when the
sewers became overloaded, flooding of combined
sewage and stormwater occurred. These devel-
opments created the original problem of com-
bined sewer overflow, although there was little
early recognition of its significance as a serious
source of pollution.
Importantly at the time, there was no sew-
age treatment. The objective was to collect and
discharge all possible contents of sewers into
the nearest watercourses. However, as the
population density increased and the effects of
wastewater discharges became known, the need
for treatment became apparent to those con-
cerned with the protection of the Nation's waters
and the public health.
As the public in many communities became
increasingly aware of the need for treatment
of sanitary wastewater, the many short sewers
discharging untreated domestic waste to various
points in the stream had to be intercepted and
the collection system modified to deliver the
waste at a single point—the treatment plant.
If the system were designed to collect and de-
liver all sanitary waste and stormwater to the
treatment plant, sewers and treatment plant
of adequate size would be far beyond practical
and economic limits. Therefore, a compromise
was necessary—combining the stormwater with
the sanitary wastewater, allowing the excess
during periods of unusually high flow to over-
flow directly to the stream.
Because the overflow is a mixture of sani-
tary wastewater and stormwater, this compro-
mise retains the problem of sending untreated
waste directly to the stream. The ameliorat-
ing factor has been that during the periods of
overflow the stormwater from the system and
already in the stream usually provides addi-
tional dilution to the sanitary waste. How-
ever, with increasing urbanization and its
accompanying demands for high quality water,
the needs for elimination of all sources of water
pollution are steadily intensifying.
The generally accepted engineering prac-
tice in this country has been to design these
combined sewers to handle during storms two
to three times the dry weather flow. Bypass-
ing the excess directly to the watercourse is
accomplished by any of several schemes. Even
though stormwater provides dilution of sani-
tary waste, a disturbing factor which must be
considered is the flushing of accumulated or-
ganic material in the sewers with the early
flooding of stormwater. This phenomenon is
responsible for substantial organic loading of
streams during storms.
Although the general nature of the storm-
water separation problem has been recognized
for many years, technical and economic infor-
mation are lacking on how best to solve it.
Studies on record have been limited and scat-
tered and only a few communities now sewered
actually have provided or plan to install facil-
ities for the separation or treatment of mingled
1
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storm and sewage flows which exceed treatment
plant capacities. A primary reason for this
limited number of communities now with sep-
arate sanitary and storm sewers has been the
high cost of the separation plus the very sig-
nificant possible need for separate treatment
of stormwater.
In recent years, a recognition of the need
to separate sanitary wastewater and stormwater
is seen in the present trend to design and con-
struct new sewer systems for complete separa-
tion. Nevertheless, a substantia] number of ex-
isting sewered communities has some type of
combined system. The latest Public Health
Service inventory of municipal sewerage facil-
ities (1), shows more than 1,300 U.S. communi-
ties with combined sewer systems serving 25.8
million people. Another 630 communities of
33.1 million population have both combined and
separate systems. Table I breaks down by
population size group and by States the U.S.
communities with combined systems only and
those with both combined and separate systems.
Since there now are some 118 million people
served by some type sewer, the 59 million people
affected by the combined systems represent 50
percent of the total sewered population. Most
of the remaining 70 million people are expected
to be served by sewers within the next several
years. This group can benefit substantially
from studies of sewer separation problems
resulting in improved and/or alternative
solutions.
In new suburban communities it is now com-
mon practice for the developer to install sep-
arate systems in the initial construction of
homes. Frequently the developer's responsi-
bility ends with the termination of the storm
sewer at the property line. It then remains
for the county, city, or other responsible
jurisdiction to develop the stormwater col-
lection system further. This is a real step for-
ward but is no final solution in the frequent
instances when the stormwater discharges di-
rectly to a small watercourse and thus continues
to add organic matter and hydraulic loading
far beyond the stream's natural limits.
Congress recognized the problem of com-
bined sewers in its recent consideration of S.649,
introduced by the Honorable Edmund S.
Muskie (D, Me.). In providing testimony on
this bill the current status of combined vs.
Table I.—U.S.
Municipalities
Sewer Systems
With Combined
Population size
3roup
Under 500
500-1,000
1,000-5,000
5,000-10,000. . .
10,000-25,000..
25,000-50,000..
50,000-100,000.
Over 100,000. . .
States
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District of Colum-
bia
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts. . .
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire.
New Jersey
New Mexico
New York
North Carolina . . .
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina....
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Combined systems
only
No. of
com-
muni-
ties
U.S. Totals 1,313
57
168
592
175
171
73
48
99
0
0
1
2
12
1
16
1
0
2
3
0
10
155
202
18
1
27
0
39
8
37
95
29
0
6
4
13
4
28
15
0
53
1
48
123
0
37
158
1
0
20
5
1
0
13
1
43
47
33
0
Population
served
Combined and
separate systems
No. of
com-
muni-
ties
17,864
118,571
1,160,495
908,516
1,893,010
1,909,950
2,258,960
17,581,939
0
0
20,000
64,300
2,057,910
107,000
490,919
2,700
0
21,500
914,515
0
48,905
4,693,140
2,445,065
184,760
107,000
658,620
0
198,650
16,800
954,205
4,252,685
1,185,710
0
44,945
19,600
26,790
80,600
91,350
366,375
0
519,525
1,020
196,855
1,735,680
0
610,280
707,915
0
0
15,925
195,125
55,000
0
10,060
180,000
826,805
425,471
1,315,600
0
25,849,305
17
35
224
130
97
64
27
36
0
13
0
0
0
0
8
6
1
0
2
0
2
29
3
10
3
5
0
31
3
14
67
1
1
20
7
5
0
27
3
0
49
0
0
56
0
6
113
2
0
7
1
1
0
46
4
13
19
52
0
Population
served
630
2
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separate sewers was summarized by Health,
Education, and Welfare Secretary Celebrezze
in part as follows:
"No real knowledge exists today as to what a
national separation program might cost, al-
though estimates have been made in billions of
dollars. Even the extent of pollution caused
by unseparated sewers is not known, although
preliminary studies suggest it is very great . . .
Before instituting a federal program for as-
sistance in the separation of combined sewers,
the ultimate cost and duration of which are
speculative, we need to obtain realistic estimates
of the costs of a separation program . . .
Once reasonably accurate information as to
total cost of a national separation program is
obtained and alternative methods have been
fully explored, we will be able to make informed
decisions among the alternatives and present
recommendations to Congress based thereon.
Consequently, I am unable to support this pro-
vision of the bill at this time, because I do not
think we have adequate information."
In hearings before the Natural Resources
and Power Subcommittee of the House Com-
mittee on Government Operations, May 22,
1963, the separation of sanitary wastewater and
stormwater was discussed in detail. Several
significant facts were brought out in testimony
by David H. Howells, Chief of the Construction
Grants Branch, Division of Water Supply and
Pollution Control of the Public Health Service,
as follows:
1. Conditions during the 19th century,
when many of the Nation's older cities devel-
oped their sewer systems, were such that 20th
century requirements for a higher degree of
water resources management were not pre-
dicted.
2. Most treatment plants handling wastes
from combined systems were developed under a
procedure by which 3 to 5 percent of the annual
sewage flow is discharged directly to the stream,
untreated, through combined sewage overflows.
The stormwater also washes large amounts of
deposited sludge out of the sewers, resulting in
considerable pollutional load to the water-
courses. For example, data from Buffalo, N.Y.,
some years ago indicate that about one-third of
the city's annual production of sewage solids
overflowed without treatment although only 2
to 3 percent of the sewage volume actually over-
flowed.
3. Even though a few studies have been
made on combined wastewater composition and
the influence of combined overflows on streams,
the information is not applicable to other cities
unless the precipitation pattern, character of
the runoff area, capacity and design of sewer
system, and conditions in the receiving waters
are comparable.
It is known that the overflows from com-
bined sewer systems and the discharge of storm-
water from storm sewers create real pollution
problems. The extent of these problems is not
known in sufficient detail to outline a compre-
hensive and sound plan or plans for solution.
Investigation of the problem has been scattered
and generally lacking in depth with results of
limited usefulness. However, the work already
done shows that there are several possibilities
for alternate or modified solutions to supple-
ment or improve existing or planned programs.
It is the purpose of this report to examine
and assess in a preliminary way existing data
on stormwater and combined sewer overflows
in regard to characteristics and pollutional ef-
fects, and to investigate existing and possible
corrective measures for dealing with the
problem.
(744-996 o—64 2
3
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Plan of Investigation
Time limitations and the preliminary na-
ture of this study made it necessary to accu-
mulate and examine data which were readily
available. Sources of data included:
1. More than 50 engineering reports and com-
pleted questionnaires dealing with sewer sys-
tems and/or sewage treatment. In general,
these were preliminary reports or planning
studies and, except for a few written specif-
ically about stormwater, they discussed sep-
aration only as a part of an overall community
problem. These reports discussed communities
with populations ranging from a few thousand
to more than, eight million. The appendix lists
the reports studied.
2. Several special reports prepared by munici-
palities or agencies which covered in detail
studies and recommendations regarding storm-
water separation. Some of these dealt specif-
ically with stormwater separation, and others
as a part of an overall problem, but all had in
common the inclusion of water quality data.
The appendix lists these reports also.
3. On-site interviews with representatives of
Cleveland, Ohio.; New York, N.Y.; Philadel-
phia, Pa.; Washington, D.C.; Portland, Oreg.;
Salem, Oreg.; Eugene, Oreg.; Tacoma, Wash.;
Seattle, Wash.; Spokane, Wash.; Vancouver,
Wash.; Kansas City, Mo.; Kansas City, Kans.;
Mission Township Sewer District, Kans.; Min-
neapolis-St. Paul (Minn.) Sanitary District;
State water pollution control agency repre-
sentatives of Oregon, Washington, Kansas, and
Missouri; and several of the Public Health
Service river basin projects, regional offices,
and comprehensive study stations.
4. Correspondence with a number of cities in
various areas throughout the United States.
In evaluating the problem of combined
sewers the following fundamental questions
controlled the study:
1. What is the quantity and quality of the
wastewater ?
2. What effects do the discharged wastes have
on the stream and on water uses and users?
3. If the effects are adverse, what control meas-
ures exist or can be recommended and how
effective will the control be ?
4. How much will the control cost?
To organize the study it was necessary to
search for and tabulate existing information
with certain specific categories in mind. Wide
variations in local conditions create special
problems of placing data in a form to obtain a
common frame of reference. To aid in accumu-
lating the necessary information, a question-
naire was developed. Because of its complexity
and comprehensive nature it was not readily
adaptable for completion by mail. Therefore,
in most instances where used it was completed
from published information or from interviews
with individuals involved in specific municipal
combined systems or separation projects.
Categorically, the primary specifics sought
were:
1. Fundamental statistics such as population;
sewered population served by separate, com-
bined, or both; availability of engineering re-
ports; and treatment plant characteristics and
performance data.
2. Detailed characteristics of combined and
stormwater sewer overflows.
3. Characteristics and frequencies of overflow
in combined system.
4. Water uses affected by overflow from com-
bined sewers.
5. Damage attributed to combined sewer
overflows.
6. Land use.
7. Basic data and hydraulics for interceptors.
8. Stream quality.
9. Rainfall and effects on systems.
10. Regulating devices used in combined
systems.
11. Infiltration to collection systems.
12. Detailed data on remedial action includ-
ing plans for or existence of separate sewers,
treatment, storage, and other methods of han-
dling stormwater and/or combined overflows.
13. Cost data for projects in (12) above.
4
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Fundamental Data From Engineering Reports and Questionnaires
Table II (pp. 6-9) summarizes the funda-
mental statistical information as obtained from
the engineering reports examined and the ques-
tionnaires completed for several municipalities
where engineering reports were not available.
Since the engineering reports were prepared
for a variety of reasons, such as wastewater
treatment needs, relief of flooding conditions,
long-range plans for metropolitan collection
and treatment programs, etc., there is no con-
sistency in format. Further, the dates of the
reports varied from 1946 to 1963. Most reports
were preliminary; therefore, performance data
were not available. In these instances the "1962
Inventory of Municipal Waste Facilities" (1)
was used to supplement the information,
particularly for quantity of wastewater and
treatment performance. These variable factors
point up that a considerable degree of judgment
is necessary in evaluating the information from
the various sources.
Despite the obvious deficiencies in source in-
formation, these reports brought out some
significant facts. They represent 55 communi-
ties in 25 States and the District of Columbia,
with a total population of 20 million and total
sewered population of 23 million. Of the 55
communities, 9 were indicated to have separate
sewer systems, 10 have combined systems, and
36 have combinations of combined and separate
systems. Of those with combined or combined
and separate systems, 9 are in varying stages
of separation programs.
In comparison with the information in
table I, this study indicates a strong sampling
of the large cities. For instance, the 10 larg-
est study cities represent more than 19 million
sewered population. In table II, 55 communi-
ties representing 23 million sewered population
are included. In comparison, there are in the
United States a total of 59 million people in
1,943 communities with combined or semicom-
bined sewer systems (table I). Throughout
the United States the ratio of the number of
communities served by both combined and
separate systems to those served by combined
systems only is 0.48, whereas in this sampling
the same ratio is 3.6. However, in developing
the preliminary study the larger communities
were examined because of the availability of
information from these sources.
In the 55 communities studied, 9 had no
treatment facilities, 25 had primary plants, and
30 had secondary plants, either trickling filter
or activated sludge. Within these totals are
several cities having multiple treatment facili-
ties.
The inability to obtain complete data for
total wastewater flow, treatment plant design,
and treatment performance prevented valid
summations. The available data are neverthe-
less included for their individual use.
Where applicable, the results of personal
interviews as mentioned in the Plan of Investi-
gation are incorporated into table II. Other in-
formation resulting from these discussions is
included later.
Most of the data in the special reports re-
ferred to in the Plan of Investigation deal with
the separation studies and are discussed later.
Characteristics of Combined and Stormwater Flows
Wastewater and stormwater reaching re-
ceiving streams without treatment originate
from combined sewer overflows directly to
streams, stormwater sewer discharges directly
to streams, and/or bypasses of wastewater by
treatment plants and pumping stations, usually
occurring during storms. It is useful to ex-
amine the findings of others who have studied
this problem in specific cases.
Review by Others
In a classical study of overflows from com-
bined sewers McKee (2) found in the Boston,
Mass., area that stormwater runoff equal to the
5
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Table II.—Summary of Sewer and Treatment Information as Obtained From Engineering Reports and
Clfy
Engineer report
Date
Engineer making report
Population
(1960 census)
Estimated tota
sewered
population
Line
No.
28,772
31,283
* 35,525
* 31,500
1
2
b 61,000
d 697,197
0 67,000
¦ 400,000
3
4
1 30,009
130,000
5
3,550,404
4,768,590
6
22,021
876,050
13,200
1,272,372
7
8
33,589
• 30,000
9
208,982
208,000
10
36,991
50,977
36,880
45,000
11
12
30,344
20,028
b 62,178
16,892
30,345
14,400
197,819
16,890
13
14
15
16
14,180
33,443
121,901
475,539
6,765
14,000
33,000
107,000
449,500
6,765
17
18
19
20
21
42,330
42,000
22
21,157
3,556
21,000
• 3,500
23
24
390,639
88,282
415,495
62,000
25
26
1 5,478
36,653
741,324
482,872
15,785
36,655
967,700
1,041,700
27
28
29
30
33,360
N/A
34,000
60,000
31
32
22,170
170,874
1 52,048
7,710,346
30,000
170,875
178,200
8,1 37,000
33
34
35
36
301,598
243,055
37
5,417
6,860
38
72,566
372,676
242,878
91,181
12,773
79,673
65,000
384,000
226,358
100,000
13,175
58,900
39
40
41
42
43
44
Amsterdam, N.Y
Ashland, Ky
Atlanta. Ga
Boston, Moss
Chattanooga, Term
Chicago, III
Clarksville, Tenn
Cleveland, Ohio
Clinton, Iowa
Des Moines, Iowa
Elmhurst, III
Eugene, Oreg
Findlay, Ohio
Hannibal, Mo
Hartford, Conn
Henderson, Ky
Huron, S. Dak
Iowa City, Iowa
Kansas City, Kans
Kansas City, Mo
Kendallville, Ind
Lafayette, Ind
LaPorte, Ind
Lathrup Village, Mich
Louisville, Ky
Manchester, N,H
Massena, N.Y
Michigan City, Ind
Milwaukee, Wis
Minneapolis, Minn
Mishawaka, Ind
Mission Twnshp. Main Sewer
District No. 1, Kan.
Napa, Calif
Nashville and Davidson,Tenn.
New Haven, Conn
New York, N.Y
Omaha, Nebr
Oswego, N.Y
Portland, Maine
Portland, Ores
Providence. R.I
Pueblo, Colo
Redding, Calif
St. Joseph, Mo
See footnotes at end of table.
Yes..
Y«..
No.
Yes.
Yes.
Yes.
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes«
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
Yes..
No. .
Yes..
Yes..
No.
Yes.
Yes.
No.
No.
Yes.
Yes.
Yes.
1947
1957
William S. Lozier Co., Rochester, N.Y. . . .
J. Stephen Watkins & Howara K. Bell,
Lexington, Ky.
1962-
1963
1948 &
1952
1962
1961
1963
1958
1963
1959
1961
1961
1959
1964
1953
1962
1963
1953
1958
1963
1963
1962
1957
1963
1962
1946
1962
1957
1960
1962
1959
1961
Charles A. McGuire & Associates, Boston,
Mass.
L. A. Schmidt, Jr, & Polk, Powell & Hen-
derson, Chattanooga, Tenn.
Black & Veatch, Kansas City, Mo
1962
1959
1946
1958
1963
1956
1953,
1955,
1960,
J. Stephen Watkins, Lexington, Ky —
Stanley Engr. Co., Muscatine, Iowa. .
Consoer, Townsend & Associates, Chicago,
Veenstra & Kimm, Des Moines, Iowa ....
Baxter & Woodman, Crystal Lake, III
Cornell, Howland, Hayes & Merryfield,
Corvallis, Oreg.
Jones, Henry & Williams, Toledo, Ohio..
Stanley Engr. Co., Muscatine, Iowa
Metcalf & Eddy, Boston, Mass
J. Stephen Watkins, Lexington, Ky.; Robt.
E. Martin, Louisville, Ky.
Schoell & Madson, Hopkins, Minn
Veenstra & Kimm, Des Moines, Iowa
Truman Schlop. Kansas City, Kans
Black & Veatcn, Kansas City, Mo
Clyde E. Williams & Associates, South
Bend, Ind.
Heniy B. Steeg & Associates, Indianapolis,
Ind.
Charles W. Cole & Son, South Bend, Ind...
Ajrres, Lewis, Norris & May, Ann Arbor,
Metcalf & Eddy, Boston. Mass
Fay, Spofford & Thornaike, Inc., Boston,
Mass.
William S. Lorier Co., Rochester N.Y. . . .
Boyd E. Phelps, Inc., Michigan City, Ind...
Alvord, Burdick & Howson, Chicago, III . .
Toltz, King, Duvall. Anderson & Associates,
Inc., Minneapolis, Minn.
Charles W. Cole & Son, South Bend, Ind...
Black & Veatch, Kansas City, Mo
George S. Nolte, Palo Alto, Calif
Genovese & Cahn, New Haven, Conn.
Greeley & Hansen, Chicago, III
William S. Lozier Co,, Rochester, N.Y.
Metcalf & Eddy, Boston, Mass
Ken R. White, Denver, Colo
Clair A. Hill & Associates, Redding, Calif.
Black & Veatch, Kansas City, Mo
6
-------
Questionnaires. Where Necessary, Information Token From "1962 Inventory Municipal Waste Facilities"
Line
No.
Type sewer* and population
served, if available
Separate
Combined
Separate
and
combined
Type of treatment
Treatment facilities
designed for
Average
flow
(mgd)
P.E.
(f ,000's)
Population equivalent
(BOD) P.E.
Untreated
waste
Treated
waste
Average
flow
(mgd)
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
X
X
b 39,000
X
X
b 28,000
30,000
X
• 636,200
50,000
X
•636,200
* 45,000
X
h X
.. X
hX
X
X
X
X
X
247,580
X
62,000
X
X
X
b 187,000
X
14,000
X
X
166,000
"X
X
52,000
X
" 332,000
X
X
50,000
X
hX
X
X
None
Trickling filter and primary
(2 plants)-
Primary
None
Primary plant and
activated sludge plant.
14 plants—8 activated
sludge, 5 trickling filter,
1 primary
None
3 plants—2 activated
sludge, 1 primary.
None
N/A
3.95
b 9.0
N/A
42.0
3.5
N/A
1 3.5
213.1
Trickling filter (2 plants)
Activated sludge.
Trickling filter
Activated sludge.
Primary
.... do
Primary '
Trickling filter.
.... do
None
None '
Trickling filter.
30.0
6.0
10.0
3.0
3.0
43.5
7.2
3.0
4.0
Primary.
Trickling filter
Enters Detroit system.
115.0
1.44
9.0
6.0
Activated sludge (8 plants).
None
102.88
Primary
Activated sludge.
....do k
Primary
Activated sludge.
Trickling filter
.... do
Activated sludge
Primary (3 plants)
Activated sludge (11 plants)
Primary (3 plants)
Activated sludge (1 plant)
Primary under construction
(1 plant)
4plants—1 Activated sludge,
3 Primary.
None
Primary
Activated sludge
Trickling filter
Primary
None
6.0
10.0
155.04
134.0
8.0
16.0
4.0
54.0
32.1
1,319.1
72.04
0.82
60.0
60.0
30.0
2.01
N/A
41.5
b 90.0
N/A
420
35
1,269.4
' 35.0
1,540
220
50,0
150.0
30.0
30.0
360.0
31.0
37.5
35-45
1,550
7.7
60.0
60,0
524.61
N/A
38.0
N/A
910.0
65.5
70.0
55.0
556.0
N/A
N/A
243.4
N/A
N/A
N/A
b 50,314
N/A
206,000
6,200
•7,975,000
• 47,000
1,562,000
N/A
391,800
28,210
170,000
43,600
18,000
N/A
N/A
42,700
33,800
649,000
730,100
• 6,765
19,825
19,500
N/A
N/A
N/A
N/A
43,260
2,380,250
1,630,000
51,700
• 60,000
33,970
356,000
N/A
N/A
N/A
N/A
N/A
N/A
b 28,400
N/A
167,500
755
•781,600
• 47,000
349,000
N/A
98,000
13,035
51,000
3,130
• 11,830
Kl/A
N A
8,600
6,200
649,000
729,650
N/A
12,530
3,600
N/A
N/A
N/A
3,730
190,055
1,110,000
4,410
• 9,000
3,395
171,000
N/A
N/A
N/A
N/A
500.0
N/A
200.0
18.5
520,164
565,000
•110,000
N/A
144,780
331,000
124,000
N/A
• 1 4,800
144,780
N/A
N/A
b 4.4
N/A
12.9
0.58
• 1,263
• 1.320
6 228
N/A
26.1
4.7
12-13
3.48
1.8
41.0
N/A
2.5
4.0
51.7
N/A
0.96
4,65
3.21
N/A
N/A
NI
IA
2.5
7,8
187.325
145.0
8.5
6.0
3.1
38.05
27.2
> 858.8
N/A
1.18
N/A
73.45
84.6
N/A
1.8
•15.0
flee footnotes at end of table.
-------
Table II.—Summary of Sewerand Treatment Information as Obtained From Engineering Reports and Que*ti
lon-
City
Engineer report
Date
Engineer making report
Population
(1960 census)
Estimated total
sewered
population
St.Paul, Minn.. .
Salem, Oreg....
Seattle, Wash...
Sedalia, Mo....
Spokane, Wash.
Syracuse, N.Y...
Tacoma, Wash..
Texas City, Tex..
Utica, N.Y
Washington, D.C
Yakima, Wash..
Totals where applicable
Yes..
1960
Yes..
1960
Yes..
1958
Yes..
1956
No. .
Yes..
Yes..
1961
1957
Yes..
Yes..
1946
1957
Yes. .
1963
Toltz, King, Duvall. Anderson, & Asso-
ciates, Minneapolis, Minn.
Cornell, Howland. Hayes, and Merry-
field, Corvallis, Oreg.
Brown & Caldwell, San Francisco, Calif...
Burns & McDonnell Engineering Co., Kan-
sas City, Mo.
O'Brien & Gere, Syracuse, N.Y
Brown & Caldwell, San Francisco, Calif...
William S. Lozier, Rochester^ N.Y
Board of Engineers—S. A. Greeley, F. A.
Marston, G. J. Requardt.
Cornell, Howland, Hayes, & Merryfield,
Corvallis, Oreg.
313,411
49,142
557,087
23,874
181,608
216,038
147,979
32,065
100,410
764,000
43,284
282,070
52,000
558,000
21,000
120,000
221,065
1 50,000
32,000
n 600
1,323,470
N/A
p 20,000,000
" 23,000,000
• 1962.
b For portion reported only.
0 As reported from municipality.
d Part of population served by other facilities.
* Estimated.
dry weather sanitary discharge is produced by
a rainfall intensity of approximately 0.01
in./hr. after impervious surfaces are wetted.
By combining this relationship with the proba-
bility of rainfall occurrence, the proportion of
sewage that will escape through overflow struc-
tures for any given capacity of the interceptor
was determined. When the flow in the sewers
is twice the average dry-weather flow approxi-
mately 2.7 percent of the total annual flow of
domestic sewage may be expected to overflow to
the receiving stream. The basic data for this
study were developed for low intensity, pro-
longed rains but were projected to include high
intensity storms. During storms the percent-
age of sewage lost by overflow would be quite
high. For instance, in a storm intensity of only
0.1 in./hr., 82 percent of the sewage during the
storm would overflow from a system designed
for twice the dry-weather flow, and if designed
for three times the dry-weather flow the same
storm would allow the overflow of about 73
percent. For storms of 0.5 in./hr., the overflow
would be 97 and 94 percent, respectively.
' Proposed.
* In preparation.
b Separation program underway.
1 Built since date of report.
' Two primary plants under contract.
Thus, even with a comparatively light rainfall,
significant pollution in terms of organic load
and bacterial contamination will be discharged
directly into the watercourse. Even with in-
terceptors designed to collect flows as great as
9 times the dry-weather flow, 82 percent of the
sewage would be overflowed from storms of
0.5 in./hr. McKee concluded that design of in-
terceptors sufficiently large to provide protec-
tion of the streams was not economically
feasible.
McKee also brought out the significant fact
that, although the total percentage of sewage
lost is low in the Boston area, the frequencies
of storms causing high loss of sewage to the
streams is far too high for adequate protec-
tion of receiving water. He found that for
interceptors designed for 1.5 to 3 times average
dry-weather flow, overflows may be expected
5 to 6 times per month in the summer, which
is much too frequent for waters to be used for
bathing or shellfish propagation.
Camp (3), in recognizing the public health
problem of discharging high quantities of path-
8
-------
naires. Where Necessary, Information Taken From "1962 Inventory Municipal Waste Facilities"—Con.
Line
No.
Type sewers and population
served, if available
Treatment facilities
designed for
Population equivalent
(BOD) P.E.
Average
flow
(mgd)
Separate
Combined
Separate
and
combined
Type of treatment
Average
flow
(mgd)
P.E.
(1,000's)
Untreated
waste
Treated
waste
45
46
47
48
49
50
51
52
53
54
55
16,900
X
94,000
X
265,170
Primary
. .. ,do.m
134.0
49.5
10.1
N/A
2.6
40.0
27.5
27.0
2.5
0.8
0.3
290.0
11.0
N/A
910.0
450.0
71.2
35.5
27.7
176.0
200.0
100.0
25.0
1.3
2.0
1,791.0
82.8
N/A
1,630,000
286,000
558,030
558,030
• 95,000
250,000
N/A
150,000
• 8,850
• 380
N/A
1,200,000
93,000
N/A
1,110,000
212,000
501,100
501,100
•9,500
175,000
N/A
123,000
• 1,320
"160
N/A
• 290,000
60,500
N/A
145.0
11.2
N/A
N/A
2.35
19.86
42.0
-16.75
•2.25
•0.11
N/A
180.8
4.6
N/A
464,000
120,000
X
Activated sludge (3 plants).
Primary (2 plants)
Trickling filter (3 plants).. • •
X
h 150,000
hX
do
Primary (2 plants)
* 24,000
X
• 8,000
X
Trickling filter (1 plant). . . .
Activated sludge (1 plant).
Primary (1 small plant)....
X
X
Primary
Trickling filter (3 small
plants).
56
9
10
36
No treatment—9 r
Primary—25 r
Secondary— r30
C)
(")
C)
C)
C)
k Plus 1 very small trickling filter plant.
1 Incomplete—data not available for 2,327,000 popula-
tion.
m Extension to secondary plant underway.
n Does not represent total for community.
ogens into watercourses by combined sewer over-
flows, concluded from studies at Concord, N.H.
and by reviewing others' work, that chlorina-
tion in amounts of not more than 10 times the
average dosage required for dry-weather flow
should be applied to combined overflows.
Palmer (4), in studies at Detroit to support
the installation of combined sewers, disagreed
with conclusions of others that the quality of
stormwater from a combined sewer shows high
pollution during the early period of overflow,
but he did not substantiate this opinion with
data. However, samplings of stormwater alone
from a catch basin indicated a high first flush
of contamination. First samples contained col-
iform MPN's of 930,000 per 100 ml and BOD of
234 mg/1 while samples three hours later had
MPN's of 25,000 and BOD of 96 mg/1. Palmer
(5) later obtained similar results in sampling
stormwater from several catch basins. In this
work Palmer also substantiated McKee's find-
ings on frequencies of overflows during summer
months as did Johnson (6) in Washington, D.C.
Camp (7) believes that the only completely
p Estimated to nearest million.
' Includes multiple plants in several communities.
* Incomplete data do not allow for valid totals.
satisfactory solution to the problem of pollu-
tion by combined sewer overflows is the com-
plete elimination of the combined overflows
but he feels that, in view of the enormous cost,
some consideration may be warranted to pro-
ceed with the compromise of partial separa-
tion as a first step.
Riis-Carstensen (8) verified the data of
McKee in Buffalo and added a method of com-
pensating for variables in population density
and runoff coefficient.
Shifrin and Horner (9) in St. Louis found
the sewage discharged by combined sewer over-
flow to vary from 2.23 to 3,09 percent of total
annual flow.
In Washington, D.C. it was estimated that
an average of 3.3 percent, or 3.6 mgd of sewage,
is lost by overflow from combined sewers (10).
Johnson (11) presented data which showed that
in Washington, D.C., at several overflow points
the average number of overflows varied from 5
to 16.8 per month in the summer and from 3.8
to 4.7 per month in the winter.
9
-------
Others who agree with these findings are
Greeley and Langdon (12) in studies of New
York City; Benjes et al. (13) at Kansas City,
Mo.; and Grameson and Davidson. (14) at
Northampton, England.
complete information is available. This lack
of specific information is understandable be-
cause the complexities inherent in a collection
system, even in a small community, make it
necessary to carry on a comprehensive, time-
consuming, and expensive study to obtain the
kind of data needed for a thorough evaluation.
Data From Engineering Reports
and Completed Questionnaires
The first attempt to consolidate informa-
tion on the quantity and quality of these over-
flows was made by examining the 50-odd
engineering reports and questionnaires. The
questionnaires were designed to obtain such
data; therefore, the appropriate portions were
compiled from this source (table III).
In all, 39 municipalities revealed informa-
tion to some degree relating to the desired ob-
jective, although the generally known fact was
further confirmed that only scattered and in-
1. Quantity oj Combined Overflows and
Stormwater
Because data from the engineering reports
were lacking or incomplete regarding quanti-
ties of combined sewer overflows, the informa-
tion from published reports (2) (3) (4) (5)
(6) (7) (8) (10) (11) (12) (13) (14) was used
for estimation purposes. These reports gen-
erally confirmed the introductory statement
that from 3 to 5 percent of untreated waste-
water annually reaches watercourses by com-
bined sewer overflows but that up to 95 percent
of such wastewater overflows during storms.
Estimates here for annual amounts will be con-
Table III.—Summary of Characteristics of Combined and Stormwater Sewer
City
Pollulional load expected
at timet of overflow (P.E.)
Treated
Untreated
Number of
Points of
overflow
Bottlenecks
Combined *ewer overflow
Water uses which may be or are
affected
Ute'
Degree1
Dollar
lots
Line
No.
Amsterdam, N.Y.
Ashland, Ky
Atlanta, Ga
19,200
48,000
30.
1..
1..
Numerous.
Boston, Mass.
4B.
Chattanooga, Tenn.
Chicago, IIT
100,000
i 8,400,000
20.,
362.
Throughout
main sys-
tem.
*
Many.
Cleveland, Ohio.
420.
Des Moines, Iowa.
EFmhursl, III
Eugene, Oieg....
Firtdlay, Ohio —
Hartford, Conn...
Entire sys-
tem.
12
1
1,2,3,
4,5,7,
8,9,10,
12,13
4,5,13
1-13
1,3,4,
5,8,9,
10,11,
12
mi-gr.
Many
9
3
Mary.
29,...
Many.
80-100. .! N/A..
5,7,8
3,4,5,
7,8,9,
10,11
mi-mo
mi-gr..
-------
fined to the conservative side of the range at 3
percent overflow. If it is assumed that domes-
tic wastewater contribution averages 100 gpd,
then the annual overflow of untreated waste
would amount to 28 billion gallons from the
25.85 million people served by combined sewers
only. Because some of the waste from the 33
million people served by combined and separate
systems wrould not be subjected to overflow dur-
ing storms, the total overflows from this source
would be something less than the 36 billion
gallons per year which might be lost by over-
flow if no separate systems were included.
However, it is estimated that the majority of
these 33 million people are affected by com-
bined systems. This would indicate, then, that
the total annual overflow would be somewhat
less than 64 billion gallons but probably not
much less. In other terms this would be equiv-
alent to untreated waste from nearly 1.75 mil-
lion people. It is important to recognize that
these amounts represent only the amounts of
sanitary wastewater which normally should go
to a treatment plant. The enormous amounts
of stormwater are added to these quantities.
Quantities of stormwater alone discharged
by sewers vary so greatly in different areas, as
do the amounts running off, that it is difficult
to estimate the totals without special studies for
this purpose. Added to this is the fact that,
after a system is designed and installed, there is
little evidence of volume measurements of total
stormwater flow. Rainfall records can be used
but actual runoff coefficients would have to be
determined along with a study of the sewer
system to establish a reliable basis for estima-
tion. The influence of infiltration also must be
included.
However, some idea of the amounts of sur-
face runoff from storms may be obtained from
certain assumptions. If the impervious area is
assumed to be one-third of the total for an urban
community served by sewers, then for each acre
there will be about 9,000 gallons of stormwater
Overflows as Compiled From Engineering Reports and Questionnaires
Line
No.
Combined sewer
overflow—Continued
Miles of
stream
affected
Stream
studies
com-
pleted
Benthos
studies
com-
pleted
Sludge
banks
in evi-
dence
Biochemical
Oxygen
Demand
Suspended
Soiids
Damages attributable
Damage °
Degree b
Dollar loss
1
2
3
4
5
6
7
8
9
10
11
12
1,7
Yes
1/2,3,
4,5,6,
7
2,7
1-7
1,4,6,
7
mi-gr
5—loss
of in-
dustry
S6-
$10
million.
20
Yes
Yes
No
Yes...
mo-gr. .. .
C)
25
Yes
Yes
Yes
Yes
1,701,000
lbs in
1961.
1,2,3
1
1,2
1,2,3
mo-gr....
xc
No. .. .
mo-gr....
See footnotes at end of table.
11
744-006 O—64 8
-------
Table III.—Summary of Characteristics of Combined and Stormwater Sewer
City
Pollutional load expected
at times of overflow (P.E.)
Treated
Untreated
Number of
Points of
overflow
Bottlenecks
Combined sewer overflow
Water uses which may be or are
affected
Use'
Degree 1
Line
No.
Dollar
loss
Henderson, Ky. .. .
Huron, S. Dak
Kansas City, Kans..
Kendallville, Ind. . .
LaFayette,lnd. ...
La Porte, Ind
Louisville, Ky
Michigan City,Ind.
Milwaukee, Wis. . .
Minneapolis, Minn.
Mishawaka, Ind
MissionTwnshp.Main
S. D. No. 1, Kans.
Nashville, Tenn
New Haven, Conn.
New York, N.Y. . .
Portland, Maine...
Portland, Oreg....
Pueblo,Colo..
Redding, Calif.
St. Joseph, Mo.
Salem,Oreg...
Seattle, Wash.
Sedalia, Mo...
Syracuse, N.Y.
Tacoma, Wash.
Texas City,Tex..,
Washington, D.C.
(¦)
C)
10.
3..
20.
Many.
. . .do.
21....
168....
storm-
water.
131
com-
bined.
>100..
Many.
.. .do.
23.
8+.
21....
218 ±.
18....
165...
Many.
None.
Many.
.do.
.do.
20.
'100
4
Many.
86.
7..
General.
Many...
At each
man-
hole.
~80.. .
Many.
13
I,2,3,
7,8,9,
II,12,
13
4,5,6,
4,6,11
3,4,5,
7,8,9,
11,12,
13
1,4,5,
8,10,
13
4,5,6,
7,8,12,
13
3,7
4,5,8,
11,12
3,4,5,
7,8,10,
11,13
mi-gr.
mi-gr.
mi-gr.
mi-gr.
mi-gr.
mi-gr.
(0
* Uses and corresponding numbers assigned as follows:
domestic water supply—1, commercial water supply—2,
industrial water supply—3, bathing—4, swimming—5, shell-
fish—6, commercial fishing—7. sport fishinq—8, power—9,
irrigation—10, shipping—11, rishand wildlife—12,aesthetic
—13.
b Degree assigned as follows: minimal—mi, moderate—
mo, great—gr, and excessive—xc.
° Damages and corresponding numbers assigned as follows:
basement flooding—1, nuisances—2, property damage—3,
real estate values—4, use restricted—5, increased treatment
cost—6, recreational use impaired—7.
d Rough estimates of values as follows: domestic water
supply—$50 million, commercial water supply—$5 million,
industrial water supply—$10 million, bathing—$1 million,
swimming—$1 million, shellfish—$5 million, commercial fish-
ing—$5 million, sport fishing—$5 million, hydroelectric
power—$100 million, irrigation—$5 million, commercial
shipping—$100 million, fish and wildlife—$10 million,
a osmetic—$10 million.
¦ Rough estimates of values as follows: basement flooding—
$0.5 million, nuisances—$0.5 million, property damage—
$1 million, real estate values—$2 million, use restricted—
-------
Overflows as Compiled From Engineering Reports and Questionnaires—Continued
Line
No.
Combined sewer
overflow—Continued
Miles of
stream
affected
Stream
studies
com-
pleted
Benthos
studies
com-
pleted
Sludge
banks
in evi-
dence
Biochemical
Oxygen
Demand
Suspended
Solids
Damages attributable
Damage 0
Degree b
Dollars loss
1 3
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
1,4
1,3
1,2
1.2
1.2.3
1.2.4
1.3
1
1
1,2,7
1
1,3,4
1,6
1
1,4,7
1,2,3,7
1,2,3,
4,5,6,7
1.2
1,2,3
1.3
1.2
1,2,3,
4,5,7
1.3
mo-gr
mo-gr
mo-xc
mo-gr
mo-gr
mo-gr
mo-gr
mo-gr
9r, xe
92 mg/1
1 72.000
Ibs./day.
72 mg/1
22,720
Ibs./day.
mo-gr
mi-gr
Yes...
Yes..
mi-mo
12
No..
mo
mo
mi
To Portland
harbor.
30
Yes...
No..
mi-gr
(*)
Yes...
Yes...
Yes .
1,2,3
mi
0
0
Yes...
Yes...
No
1,2,7
gr
$2 million, increased treatment costs—$1 million, recrea-
tional use impaired—$2 million.
' Average per year.
' Estimated tc be 0.6-3.5 percent of BOD reaching point
of diversion; also plant bypass amounts to 1.7-3.1 percent
of BOD reaching treatment plant, and loss of BOD from
selected regulators varies between 0.06 and 3.5 percent of
BOD reaching treatment plant. Total amount in terms of
weight unknown.
h Estimated that 2.6-3.1 percent of total raw wastewater
discharged by overflow with sformwater.
1 Under the fishing category the total summer value as-
signed was $1,120,000/yr.
k Maximum damage estimated as caused by basement
flooding—$1500—$2,000/house.
* Many exist but exact number could not be determined.
-------
for each inch of rainfall. This amounts to about
5.8 million gallons for each square mile for each
inch of rain. In the 50 States there are some
11,400 communities of all sizes, having a total
area of 43,100 square miles. The area of the
1,943 communities discussed in this report is not
known; therefore, projections cannot be made
for these totals. As a specific example, though,
Chicago with 190 square miles of sewered area
serving 3.5 million people would, under these
assumptions, have a stormwater runoff of 1.1
billion gallons for each inch of rain. Similar
projections can be made for other communities.
For these reasons no overall estimate of
amount of stormwater is included. Some of the
details are discussed in the special studies
sections.
2. Damages Attributed to Stormwater
Although many cities realize the need for
comprehensive studies of the stormwater prob-
lem, adequate funding most often is not avail-
able; therefore the studies contracted for are
limited to the pressing needs most apparent to
the public. This is clearly documented in the
reports studied, as shown in table IV, which
delineates the importance of damages in the
opinion of the investigating engineers and the
communities.
Table IV.—Damages Attributed to Combined Sewer
Overflows as Shown by Data Obtained from 35
Communities
Number
Damage
commu-
Relative degree of
nities
damage
reporting
Public health—basement
33
Minimal—excessive.
flooding.
Minimal—excessive.
Nuisances
19
Property damage—houses,
15
Minimal—great.
boats, etc.
Real estate values
9
Minimal—great.
Use restricted
4
Minimal—great.
Increased treatment cost..
5
Moderate—excessive.
Recreation area use im-
11
Minimal—great.
paired.
By far the most frequent problem discussed
is that which occurs when combined sewers sur-
charge and residence and business basements are
flooded with a combination of untreated sewage
and stormwater. This not only causes a nui-
sance and a financial loss but is an obvious pub-
lic health hazard. Since 33 of the 35 communi-
ties reporting damages stressed this problem, it
appears that basement flooding was a primary
factor in their authorizing the studies. This is
confirmed by discussion in the reports, some of
which contain strong language on this point.
Closely related to basement flooding, but not in-
cluded as an item in the questionnaire, is the
problem of street flooding. Most of the com-
munities reporting basement flooding problems
also suffer street flooding.
Little attention was given to the public
health aspect of such flooding although the re-
porting engineers no doubt realize that health
hazards do occur each time untreated sewage
backs up into basements or streets.
Only two cities reported on the quality
of overflows, which may or may not be of simi-
lar quality to the waste waters entering base-
ments. This lack of data is believed traceable
to the fact that where excessive flooding occurs
the physical evidence alone should provide suf-
ficient stimulus for correction. Yet, many of
these situations with their continuing health
hazards persist. It appears of fundamental
importance to the public that more information
be obtained on the quality of these floodings and
their health aspects.
Damages were classified in the tabulation.
More than half of the situations studied con-
sidered overflows as nuisances and nearly half
claimed damages to property. These assess-
ments may be related to house and street flood-
ing. About one-third related the damage to
waterways in terms of recreational impairment.
Attempts were made by three cities to as-
sign dollar values to the losses. One assigned
values to each damage; another stated that a
loss of industry resulted and that waste treat-
ment costs were increased by $10 million. A
third estimated the maximum damage caused
by basement flooding to be $1500-$2000 per
house.
Only seven cities mentioned the pollutional
load imposed on streams at times of overflow
and there is an apparent lack of uniformity in
measuring this load. For instance, two cities
reported the load in pounds of BOD at times
of overflow; one reported total pounds BOD
average per year; one gave a total weight for
one specific year; one reported the loss as a
percentage of the BOD reaching the point of
14
-------
diversion but did not include actual quality
data, and one reported the total loss as a per-
centage of total raw wastewater. One city re-
ported BOD and suspended solids data for com-
bined sewer overflows. No other quality data
were available.
Obviously more complete studies are
needed to obtain meaningful quality informa-
tion for overflows.
Altogether, 30 cities of the 39 supplying
information tabulated or mentioned the number
of points of overflow in the system. These
varied from 1 to 420. Similarly, 25 communi-
ties reported bottlenecks in the system. A few
counted the number of bottlenecks but most
found this a difficult task and settled for a num-
ber described as "many."
3. Water Uses Affected by Overflows
Related to the assessment of damages by
overflows was the tabulation of water uses
potentially or actually impaired by combined
sewer overflows. For discussion purposes these
are grouped in eight general classifications. In-
formation was available from 19 communities.
The categories and number of communities con-
sidering each are as follows:
Fishing 14
Bathing and swimming 13
Water supply 11
Aesthetic 9
Fish and wildlife 8
Commercial shipping 8
Hydroelectric power 6
Irrigation 6
This tabulation shows that recreational,
commercial, and public health requirements are
fairly evenly divided and that all are quite
important in the opinion of the communities.
Water uses were affected in varying degrees
from minimal to great, with a relatively even
scattering. One city estimated and reported
dollar amounts for each use, while another
valued sport fishing at 22,000 man-days, and
still another placed a summer value on fishing
affected at $1,120,000.
Few cities reported the length of stream
affected. Only eight of the communities have
made stream studies and only three have in-
cluded benthos studies. Seven cities stated that
there were sludge banks in evidence and four
said there were not.
Data From Special Studies
Because the 50-odd engineering and com-
munity reports contained little real data on
characteristics of combined and stormwater
overflows, it was necessary to utilize the data
from only a few cities where special investiga-
tions have been made and from which the in-
formation was made available. The areas
studied were the East Bay Metropolitan Utility
District, Oakland, Calif.; Chicago, 111.; Cin-
cinnati, Ohio; Washington, D.C.; and Los
Angeles County, Calif.
The studies differed in pattern and back-
ground conditions and results therefore could
not be consolidated as representative of condi-
tions throughout the United States. Thus the
data for each community are presented
separately.
1. East Bay Metropolitan Utility District
Of the six cities connected to the waste-
water treatment plant, only Oakland retains
combined sewers, 5 in number, which are con-
nected to the treatment facilities by diversion
structures. These structures divert all the dry-
weather flow into an interceptor and during
storms permit bypass of stormwater-diluted
wastewater through outfalls to San Francisco
Bay.
In spite of the essentially separate collec-
tion system, wastewater flows in the interceptors
increase substantially during storms. How the
stormwater reaches the interceptors is not
known, but it is presumed that rising ground-
water (infiltration) and flow from connected
roof leaders, catchbasins, basement sumps, and
yard drains all contribute. Because the treat-
ment plant will not accommodate the increased
hydraulic load, it is necessary to bypass the
plant during storms. Extensive sampling of
the various features of the system was initiated
because of the existing conditions.
Table V includes analytical data from two
interceptors for periods of heavy rainfall and
dry weather. The dilution effects of storm-
water are apparent.
15
-------
Table V.—Analyses of Interceptor Flow During
Wet and Dry Weather at East Bay Metropolitan
Utility District—All Data Are Average
Determination
South interceptor
North interceptor
Com-
puted
charac-
teristics
of wet
weather
flows to
plant 1
(mg/1)
Wet
weather
flow
Dry
weather
flow
Wet
weather
flow
Dry
weather
flow
DO (mg/1). . .
Total sulfides
B(^D9(mg/1)..
Chlorides
„ (mg/1)
SS (mg/1). . .
4,9
0
178
128
162
0.5
.3
449
264
336
5.5
.03
195
129
162
0.8
.1
285
227
5.0
.01
180
162
128
1 Based on proportions of 0.8 from south interceptor and
0.2 from north interceptor.
Table VI condenses the results of special
sampling during storms to show the characteris-
tics of combined sewer overflows, separate
stormwater from storm sewers, stormwater
from a creek not ordinarily receiving waste-
water, and the treatment plant bypass. The
indications are that the stormwater both in
sewers and in creeks contain substantial pollu-
tional loads as measured by organic and in-
organic standards. Large numbers of coliform
organisms also are present. The high degree of
load imposed by combined sewer overflows is
clearly shown. Since there is reason to believe
that these results are fairly typical, the implica-
tion is that the overall organic and coliform
loading to the Nation's receiving waters is
enormous.
Another way of measuring the effect of
stormwaters on watercourses is by examining
conditions at pumping stations when it is neces-
sary to bypass during storms. Table VII pre-
sents data from such situations. Samples were
taken upstream and downstream from, and at,
the station. At the same time samples were
taken from a nearby stream which does not re-
ceive wastewater overflows. The organic and
bacteriological quality of the water upstream
from the discharge is approximately equivalent
to that in the stream not receiving waste; how-
ever, the inorganic load imposed by erosion into
the creek is apparent in the concentrations of
solids and sand. The effect on the stream by the
wastewater is clearly shown throughout the
table; for example, the increase in BOD and
coliform counts.
2. Chicago, Illinois
A special report on water quality in the
Illinois River System, as requested by the De-
partment of Justice, was prepared by the Public
Health Service and published in January 1963
(15). The report was pertinent to the latest
litigation concerning the diversion of Lake
Michigan water at Chicago. In connection
with this investigation a small project was
Table VI.—Characteristic! of Combined Sewer Overflows, Storm Sewer Flows, Watershed Streams, and
Treatment Plant Bypass at East Bay Metropolitan Utility District
Determination
Combined sewer overflow!
(14 samples from various
stations)
Mini-
mum
Maximum
Averase
Storm sewer flows (21
samples from various
stations)
Mini-
mum
Maxi-
mum
Aver-
as*
Creek samples from
areas not receiving
wastewater (Ave sam-
ples from various
stations)
Mini-
mum
Maxi-
mum
Aver-
as*
Treatment plant effluent by-
passed in bay (sampling during
nine different periods)
Mini-
mum
Maximum
Average
DO (mg/l)
BOD (mg/l)
Total Solids (mg/i).
Vol. Solids (mg/l).
Susp. Solids (mg/l).
Conform (MPN/
ml)
Chlorides (mg/l)...
Oil & Grease
. (mg/l)
Sand (mg/l)
pH
2.4
13
132
83
60
2,300
619
8
0
6.8
9.6
153
1,327
291
1,120
2,400,000
619
66
276
7.4
6.9
59
400
144
203
293,000
619
33
76
7.1
0
3
726
168
16
4
300
2
7
6.3
13.2
>700
726
168
4,400
70,000
10,260
162
868
7.8
7.3
87
1,401
168
613
11,800
5,100
32
158
6.9
2.8
<5
1,401
158
780
130
540
0
193
8.2
35
1,401
158
1,620
62,000
540
100
1,074
4.8
17
1,401
158
1,176
13,800
540
25
560
1.2
45
500
100
108
62,000
9.5
320
1,100
600
770
>7,000,000
4.9
133
800
350
253
>1,408,000
12
106
255
116
133
111
16
-------
Table VII.—Stream Quality Conditions at Time of Bypassing of Pumping Stations
Determination
Upstream
Point of discharge
Downstream
Mini-
Maxi-
Av-
Mini-
Maxi-
Av-
Mini-
Maxi-
Av-
mum
mum
erage
mum
mum
erage
mum
mum
erage
7.8
10.0
9.5
7.8
10.0
8.9
7.2
9.9
8.5
<1
21
6.8
21
360
92
5
60
25
229
748
469
78
543
385
352
2,482
918
70
185
124
70
276
174
90
355
185
23
644
269
64
278
129
53
568
274
620
4,250
1,990
10,800
70,000
48,200
980
126,500
40,500
12.8
13
12.9
13.0
13.8
13.4
12.5
13
12.75
16
26
21
26
46
36
18
24
21
0
15
9.2
5.2
33
17.1
5.8
13
10.5
0.0005
366
133
0
101
45
.0076
216
100
7.3
7.5
7.4
7.2
7.6
7.4
7.3
7.7
7.5
Another stream of
receiving overflow
Mini-
mum
Ma vi-
lli um
Av-
erage
DO (mg/1)
BOD (mg/1)
Total Solids (mg/1)
Vol. Solids (mg/1)
Susp. Solids (mg/1)
Coliform (MPN/100ml).
Temp. 0 C
Chlorides (mg/1)
Oil & Grease (mg/1).. .
Sand (mg/1)
pH
7.0
3
5,380
542
6,820
620
9.6
16
6,672
620
16,005
4,250
8.3
9.5
6,026
581
11,412
2,435
12.5
15
4,774
12.5
15
4,774
12.5
15
4,774
initiated to study combined sewer overflows in
the Chicago area.
Since 1856, when the first combined sewers
were installed to serve 7 square miles of the
"Loop," the combined sewer system has been ex-
panded to include more than 3,600 miles of
sewers serving 190 square miles and 3.5 million
people.
The total pollution load to Chicago water-
courses by stormwater overflows from the com-
bined sewer system has not bean determined by
field measurement. Estimates place the annual
sanitary and industrial waste overflows to the
canals in the range of 3 to 5 percent of total
annual flows for sanitary sewage interceptors
designed for 1.5 to 3 times the average dry-
weather flow. However, it is pointed out that
the first slug of such waste may be several times
the strength of normal sewage flow.
To obtain on-site data, a small test site was
studied with the intent of extending the data for
full-scale estimates. The study area was desig-
nated as the Roscoe Street sewer, covering an
area of about 8.6 square miles on the north side
of the city. Interconnections between Chi-
cago's major sewers serving adjacent drainage
areas provide relief drainage for localized
storms and also obtain economy of design.
This often results in indistinct drainage
boundaries. In this instance, about 2.4 square
miles of the Roscoe Street area is connected
to the Kostner Avenue sewer. For this study
the interconnected area was assumed to be
tributary to the Roscoe Street sewer. The imj
pervious area was estimated to be 42 percent of
the total area. Gaging and sampling during
storm periods continued in this area throughout
the study.
The study was carried on for a 9-month
period, mostly in 1962, during which time there
were 31 storms. The total BOD load dis-
charged to the stream during this period was
computed at 278,300 lbs., or an average daily
amount of 1,010 lbs.
It was recognized that many factors could
change these amounts but they were the best
figures available to produce a simple projection
for estimating the total BOD overflow load to
the canal system. Flow data from three major
treatment plants were used for the computation
and on this basis the average total BOD over-
flow load was calculated to be 46,900 lbs./day,
or a population equivalent of 281,400.
The report concluded that the discharge
of raw sewage and industrial wastes mixed with
stormwater during periods of storm runoff con-
stitutes a significant intermittent source of pol-
lution of the Chicago waterways. It points out
the various damages to waterways and losses of
use caused by stormwater overflows and adds,
"More important, however, is the danger to
public health from the pathogenic bacteria and
viruses which may be present in raw sewage.
Although the concentration of BOD and sewage
solids, with exception of the first flush, may be
reduced by dilution during runoff periods, the
pathogens remain a serious menace to any pub-
lic use of the streams receiving these dis-
charges."
17
-------
3. Cincinnati, Ohio
The preliminary results of a study on ur-
ban land runoff as a factor in stream pollution
recently became available (16).
This study covered a 27-acre residential and
light industrial drainage basin with separate
sewers. The resident population is about 240, a
density of 9 persons/acre as compared with the
overall city density of 10/acre. The area con-
tains single-family homes, several small apart-
ments, stores, restaurants, a firehouse, church,
and several other public buildings. The im-
permeable area is about 37 percent and the
ground slope is 2 to 3 percent.
Stormwater was sampled for about 1 year.
Table VIII shows the seasonal variations of the
Table VIII.—Seasonal Variations of Constituents of
Stormwater Overflows From a Study of a 27-Acre
Area in Cincinnati, Ohio
Table IX.—Mean Concentrations of Constituents
in Urban Land Rvnoff vs. Time From a Study of a
27-Acre Area in Cincinnati, Ohio
1962
1963
Constituent
July-
Septem-
ber
Octo-
ber-
Decem-
ber
Janu-
ary-
March
April-
June
July-
Sep-
tem-
ber
Suspended solids.
Volatile suspended
solids
COD
BOD
NOz-N
NOs-N
NOj-N
Organic N
POs
Mean concentrations (mg/1)
180
160
260
250
190
43
41
63
62
48
110
84
110
100
100
30
28
12
19
15
0.07
0.03
0.06
0.05
0.07
.41
.26
.44
.44
.52
.97
.79
.49
.82
.50
1.2
1.9
1.8
2.0
2.0
1.2
.81
.47
.66
1.1
quality of the stormwater overflows, and table
IX shows the effect of time in a given storm on
the concentrations of constituents. The pollu-
tional load was measured by BOD and COD
is about equal to that expected from the effluent
of a secondary sewage treatment plant, while
the suspended solids are about the concentra-
tion found in raw domestic sewage. Nutrients
are high. BOD is the only constituent that
shows much change in relation to the season.
Table IX demonstrates the flushing effect
with time and is equally true for short- and
long-duration storms.
Bacteriological examination of the storm-
water revealed that coliform counts and fecal
Time after start of runoff
Parameter
0-15
15-30
30-60
60-
1S0
min-
min-
min-
min-
120
utes
utes
utes
utes
min-
and
utes
over
(ms/1)
Suspended solids. . . .
390
280
190
200
160
Volatile suspended
solids v
98
69
47
58
38
COD
170
130
110
97
72
BOD
28
26
23
20
12
Total Nitrogen—N...
Phosphate PO< (total
3.6
3.4
3.1
2.7
2.3
soluble as POO —
.99
.86
.92
.83
.63
streptococci counts were rather high. Fifty
percent of the coliform counts were in excess of
58,000/100 ml and 50 percent of the fecal strep
counts were in excess of 20,500/100 ml. These
results are of special significance in areas
where the receiving water is to be used for
swimming.
A computation was made to compare
stormwater to sanitary wastewater from the
same area. In terms of the ratio of storm-
water to sanitary wastewater the various com-
ponents were as follows: suspended solids, 140
percent; volatile suspended solids, 44 percent;
COD, 25 percent; BOD, 6 percent; PO<, 9 per-
cent; and total nitrate nitrogen, 11 percent.
The report emphasizes the fact that urban
runoff is a significant factor in considering
waste loadings from urban sources.
4. Washington, D.C.
Limited sampling was carried on over a
period of about 1 year to obtain information
about street runoff. Runoff was sampled at
various catch basins during storms but no at-
tempt was made to return to the same site later.
Several samples were taken at each site during
each storm. No attempt was made to correlate
the information to the overall problem. Re-
sults are shown in table X. The concentrations
found for BOD, chlorides, and suspended solids
point to a substantial pollutional load from
stormwater.
18
-------
Table X.—Summary of Analytical Data From Selected Catch Basin Sample* During Storms in Washington,
D.C., 1959-63
BOD (mg/1)
Chloride* (mg/1)
Sutpended solids (mg/1)
Sample location
Mini-
Maxi-
Aver-
Mini-
Maxi-
Aver-
Mini-
Maxi-
Aver-
mum
mum
age
mum
mum
age
mum
mum
age
Catch basins at 11 locations
6
625
126
11
160
42
26
36,250
2,100
5. Los Angeles Flood Control District
The water Conservation Division of the Los
Angeles Flood Control District has been in-
terested for many years in the quality of storm-
water for purposes of spreading onto land
areas to obtain replenishment of groundwater
supplies. Results of studies carried on during
the 1932-34, 1957-58 and 1962-63 storm seasons
are contained in an unpublished report (17).
Average results of the sampling programs
are shown in table XI.
Table XI.—Average Chemical Quality Charac-
teristics of Stormwater From Los Angeles County
Dates
DO
(mg/1)
BOD
(mg/1)
SS
(mg/1)
CL
(mg/1)
1932-34
6.4
8.0
7.5
6.9
8.2
16.1
7,330
1,534
2,909
20.4
1957-58
1962-63
19.9
The studies showed a steady increase in
BOD for each of the three periods and in-
conclusive trends for other components meas-
ured. The sampling also showed the first flush-
ing effect for BOD. In the early period of
storms the BOD concentration of stormwater
was as high as 70 mg/1 and then decreased as
the storms progressed and leveled off to a range
of 10 to 20 mg/1.
The 1962-63 studies showed that the first
storm of the season was responsible for much
higher coliform counts in the stormwater than
were succeeding storms. Samples from the first
storm contained coliform counts ranging from
380,000 to 1,100,000 per 100 ml at 6 stations,
whereas the counts in later storms ranged from
800 to 80,100 per 100 ml. The conclusion
reached was that the first storm flushed ac-
cumulated organic dirt rich in coliforms into
the receiving waters.
Data From Studies by Others
Studies of stormwater runoff have been
reported from time to time at various loca-
tions. These studies have been concerned with
local problems and the methods vary somewhat
with the individual communities.
Palmer (4) sampled catch basins during
storms in Detroit in 1949 and again in 1960
(5). His conclusions made it clear that the
studies were inadequate to provide a solution.
He observed that in some instances the quality
of the runoff became worse as the storm pro-
gressed and in others it became better, while in
still others there was no apparent pattern.
Sylvester (18) in 1959 and 1960 sampled
Seattle street gutters during storms and found
that the highest constituent concentrations usu-
ally were found when antecedent rainfall had
been low.
Riis-Carstensen (8) discussed an extensive
program of gaging and sampling of combined
sewer flow in Buffalo, N.Y. He computed that
in 1 hour during a storm the combined sewage
carried 28.4 times the normal amount of sus-
pended solids. He also observed that any eval-
uation of the pollutional effect of combined
sewage overflows based on volume alone may
be grossly misleading because of the wide varia-
tion in constituent strengths.
In 1954, studies were made of surface run-
off at Oxney, England (19) from a 611-acre
estate with separated sewers. It was concluded
that, on the basis of assumed treatment plant
effluent levels of 20 mg/1 for BOD and 30
mg/1 for suspended solids, the separate system
reduced the BOD loading on the stream, but
increased the suspended solids loading by 6 or
7 times. Studies were made in Moscow in 1936
(20) of stormwater runoff and in Leningrad
in 1948-50 (20) in an area of cobblestone streets.
19
-------
Samples taken from 1945-48 from summer rain-
water drainage from streets and parks in Stock-
holm, Sweden, were reported (21). Storm-
water samples from residential, park, school,
sports ground, business and flat areas in Pre-
toria, South Africa, were reported in 1961 (22).
A summary of the data accumulated from
this work appears in table XII.
Table XII.—Summary of Quality Characteristics of Stormwater and Combined Sewer Overflows for Various
Cities as Reported by Others
Constituent
Seattle (18)
Stormwater
Buffalo, N.Y. (8)
Combined sewer overflow
Oxney,
England
(19)
Storm-
water
Moscow.
USSR
(20)
Storm-
water
Lenin-
SS&
(20)
Storm-
water
Stockholm,
Sweden (21)
Stormwater
Pretoria,
South Africa (22)
Stormwater
Bird Ave.
Baily Ave.
Resi-
dential,
park,
sports
ground
Business
and
flat
areas
Before
storm
During
storm
Before
storm
During
storm
BOD (mg/l). ...
10
162
100
127
121
100 max.
18-285
36
17-80
18-3100
30-8000
30
29
34
28
Total solids
(mg/l).
Susp. solids
(mg/l).
Conform (MPN/
100ml).
Org. N (mg/l)...
NOj-N (mg/lj.
Soluble P (ms/I) ¦
Total P (>ig/l) ¦ • .
Fixed residue
(mg/l).
Dissolved solids
(mg/l).
Volatile solids
(-ns/D.
498
158
754
544
461
126
785
436
2,045. . .
1,000-
3,500
14,541
16 000
40-200,000
240,000
5.4
230,000
3.5
2 8 max
210-2420
108
228
154
Additional Data From Municipalities
The questionnaire used in the present study
was designed to incorporate comprehensive data
on all aspects related to the combined sewer
and stormwater overflows. Because of the
many different objectives of the reports studied,
many questions were wholly or partially un-
answered. Some of the points which were
brought out are discussed in the following
sections.
and alleys, etc., and the proportion of each area
which is impervious. Conversely, the facts are
needed also to understand and make intelligent
correlations with other data about existing sys-
tems. Only scattered and mostly incomplete
information was available for land use. For
instance, 10 cities gave some data but only 1
had detailed information. This information
has quite limited usefulness and is therefore
not tabulated.
Land Use
One of the fundamental types of data re-
quired in the design of a stormwater or com-
bined sewer system is detailed knowledge of
land use. This involves the various use classi-
fications; i.e., residential, commercial, streets
Basic Data and Hydraulics for Interceptors
Only scattered and incomplete data were
given for most of the 12 cities which included
information. For example, only one city in-
cluded runoff coefficients with the other statis-
20
-------
tics. The many different conditions encoun-
tered in each city surest detailed analyses of
individual cities' problems, especially in regard
to the complexities of interceptors. To compile
and correlate meaningful data on interceptor
design and discharge, which would be useful
throughout the United States, appears beyond
the scope of a preliminary report.
Stream Quality
Again, only a few reports contained stream
quality data and those which did made no at-
tempt to correlate the pollutional discharge
with quality of the stream. This is understand-
able because most of the reports are prelimi-
nary and, if recommending treatment, base the
requirements on something less than a detailed
stream survey. The data as provided are dis-
cussed earlier in connection with table III.
Other information has been discussed in connec-
tion with the special reports, except that "which
follows.
In Chicago it was estimated that an average
total of 8.4 million pounds of BOD per year
are discharged as the result of overflows in
storms. This compares with 46.9 million
pounds BOD as secondary treatment effluent,
and 4.0 million pounds BOD as primary treat-
ment effluent.
Minneapolis reports the BOD load result-
ing from storms in percentages. This dis-
charge was estimated at 0.6 to 3.5 percent of
the BOD reaching the points of diversion;
however, the concentration at the points of di-
version was not available. Minneapolis fur-
ther estimates that the plant bypass due to
storms amounts to 1.7 to 3.1 percent of the
BOD reaching the treatment plant; and the
BOD discharged from selected regulators
varies between 1.7 and 3.1 percent of the BOD
reaching the treatment plant.
Others such as Chattanooga, Tenn.; Cleve-
land, Ohio; Hartford, Conn.; Manchester,
N.H.; Salem, Oreg.; Syracuse, N.Y.; Utica,
N.Y.; and Yakima, "Wash., determined dissolved
oxygen, BOD, and coliform counts above and
below the point of discharge.
There are much published data relating the
effects of sanitary sewage, both treated and
untreated, to stream quality, but very little
about the effects of storm water on streams. The
special studies discussed earlier point out some
of these information deficiencies.
The increasing amounts of stormwater from
the ever increasing urban populations have seri-
ous public healt h overtones, particularly in view
of the lack of valid information. The water
uses adversely affected and the physical dam-
ages as earlier discussed further emphasize the
problem. Overflows during heavy and pro-
longed storms, estimated to contain as much
as 95 percent of the sanitary sewage, reinforce
the belief that combined sewer systems now
present a very real pollution hazard.
Rainfall and Effects on System
Factors relating rainfall and its effects on
the collection system are considered in detail in
the design of the sewers.
One of the most common methods of de-
sign of storm sewers is by the so-called rational
method represented by the formula Q=CiA,
wherein Q is the runoff rate in cfs, C is a se-
lected coefficient of runoff expressed as the ratio
of runoff to rainfall, i is the mean intensity of
rainfall in in./hr., and A is the tributary area
in acres. Judgment is needed in establishing
values for C. Considerable judgment also is
needed in using the rainfall data. For instance,
it is necessary to establish the period or recur-
rence interval during which each section of a
given facility will be called on at one time or
another to carry a storm flow equal to or in ex-
cess of its capacity. At this frequency, sur-
charge or local flooding will result. General
flooding would result in the event of a prolonged
high intensity rainfall which exceeds the in-
tensity for the design frequency. Many factors
are considered in the selection of a design fre-
quency ; for example, economic implications of
local flooding; type, nature, and extent of areal
development which might be subject to damage
by flooding; magnitude of applicable rainfall
intensities; size or extent of tributary area; and
economics of construction.
Design of combined sewers frequently is
based on the same storm flow considerations as
for storm sewers, except that they are sized to
21
-------
overflow beyond some factor of the dry-weather
flow, frequently two to three times.
Usually an assumption is made to establish
the amount of rain which will fall before run-
off occurs. This amount is attributed to the
wetting of surfaces, filling of depressions in im-
pervious surfaces, retention on vegetation, in-
filtration into the soil, and surface detention re-
quired to build up a film of water sufficiently
thick to cause flow. This assumption is a guess
at best, but establishes a base from which run-
off amounts are computed. These assumed
rainfall amounts range from 0.01 to 0.04 in./hr.
Many measurements have been made of
overflows occurring from combined systems and
the dilution factors at the overflow points, but
measurement of the actual quantities overflowed
in relation to rainfall intensities and duration,
along with frequencies and analytical data of
the amounts overflowed, is lacking in the en-
gineering reports. This again made it neces-
sary to use the limited data from the special
studies.
Metering of Flow and Regulatory Devices
Used on Combined Systems
Of the more than 50 reports examined,
only 15 indicated that the wastewater is or had
been metered. Undoubtedly many others have
made spot checks or even special studies. To
appraise the problem fully, a more comprehen-
sive metering arrangement would be necessary
than that permitted by spot checks.
The use of regulating devices in combined
systems was indicated by 21 cities. The types
and numbers, where available, are shown in
table XIII.
This sampling shows that the regulator
types are fairly evenly divided between leaping
devices, side weirs, and gates, with 7, 8, and 11
Table XIII.—Types of Sewage Flow Regulators in Use in Combined Systems From Cities Studied
City
Leap-
ing de-
vices
Side
weiri
Gates
Si-
phons
Me-
chanical
means
Other
Condition or remarks
Atlanta, Ga
2 drop inlet inter-
ceptors.
Good.
Leaping devices-
poor. Mechani-
cal—good.
4 percent need re-
pair at one time.
Good.
Constant mainte-
nance required.
Poor.
New.
Good.
Large number of
regulators in use.
Good.
Good.
Good.
Total of 86, mostly
orifice.
Chattanooga, Tenn....
Chicago, III
2
9
X
Cleveland, Ohio
60
55
2
80-100
19
0
14
14 perpendicular
weirs.
200 unclassified .
Eugene, Oreg
Hartford, Conn
Huron, S. Dak
X
X
Kansas City, Mo
X
6
X
Manchester, N.H
1
20
4
Minneapolis, Minn....
Mishawaka, Ind
X
X
1 7 float operated
24 orifices.
X
Mission Township,
Main Sewer District
No. 1, Kans.
Nashville, Tenn
Electrically-oper-
ated valves.
2
19
New Yorn, N,Y
X
Portland, Maine
18
X
Portland, Oreg
Salem, Oreg
20
Syracuse, N.Y
X
Valve and
float-con-
trolled.
X
Dams and orifices
Tacoma, Wash
X
X
Texas City, Tex
X
* Estimated to be 100 side overflows and 100 perpendicular overflows.
X Devices in use but in unknown numbers.
22
-------
cities respectively using the three types. Ori-
fice-types were indicated to be in use in quantity
in several of the larger cities. Many cities use
combinations of types.
There is insufficient information to evalu-
ate the various types as to best choice for the
purpose. Undoubtedly, performance is im-
proved by proper maintenance of regulating
devices and by providing designs which tend to
balance flow conditions throughout a system.
There are many instances of surcharging at
points of regulation in dry weather due to poor
design or maintenance or because changes in
the system have rendered an existing regulator
essentially useless.
Infiltration
A major problem in many collection sys-
tems is infiltration. In this discussion, infiltra-
tion includes that water entering a sewer system
by way of defective joints, cracks, breaks, or
from manhole sites.
In the early years of sewer design and con-
struction, experience proved that large amounts
of water infiltrated all types of sewers. Ac-
cordingly, design criteria were developed to
allow for infiltration in new sewers. The gen-
eral philosophy was that, since storm sewers
carry innocuous rainwater, the installation of
tight sewers was of minor importance. Like-
wise, since combined sewers and interceptors
were and are designed to receive certain amounts
of stormwater, there was general belief that
liberal allowances should be made for infiltra-
tion. Sanitary sewers by nature restrict the
carriage of stormwater, but many cities allow
area way drains, foundation drains, or even roof
leaders to be connected to sanitary sewers.
Therefore, the sanitary sewers are designed for
varying amounts of water other than sanitary
wastewater. In all instances examined, the de-
sign criteria for sanitary sewers include allow-
ances for infiltration. There is an increasing
awareness that these design allowances can be
reduced because of improved joints, more rigid
inspection, and improved methods for correct-
ing leaks and breaks. However, these changes
are slow and far from universal. Meanwhile
the added tax burden is enormous.
To continue the 50-year-old philosophy that
infiltration is a necessary evil to be tolerated
at the same old rate is poor engineering judg-
ment and administrative procedure. The effects
of excessive infiltration are most prevalent in
sanitary sewer systems and interceptors. Many
cities report the yearly amount of infiltration
to equal or exceed the amount of sanitary waste-
water. This can only mean the installation of
larger sewers and severe limitations on existing
sewers as growth occurs. It means providing
relief in the form of new sewers or tolerating
overflow to the stream with resulting deteri-
oration of stream quality. As for treatment,
it means the added cost of a larger plant to
accommodate the increased hydraulic load or
bypassing the excess flow to the watercourse,
thus negating the purpose of the treatment
plant.
To illustrate the general problem, there is
included here a study of infiltration from all
sources to the sanitary sewers of one residential
area served by so-called "separate" sewers. In-
filtration in this instance included groundwater
and direct connections from foundation drains,
downspouts, area drains, etc. At Mission Town-
ship Main Sewer District No. 1, Johnson Coun-
ty, Kans., Weller and Nelson (23) found that
over a 4-year period the average wastewater flow
in the sanitary sewer system was more than 3
times the average water used. Thus, the major
flow originated from sources other than the
water supply. It was concluded that during
moderate storms the major stormwater entry
into the sewers was from house foundation
drains which apparently were connected di-
rectly to the sewers. Other sources of direct
connections and their proportions, based on resi-
dences rather than people, included downspouts,
13 percent; flooding through surface entry into
basement, 7 percent; areaway or patio drains, 5
percent; and driveway drains, 3 percent. Of
these, the driveway drains were considered to
be the most important from a hydraulic loading
standpoint.
Infiltration is somewhat less important in
storm sewers because the treatment plant is not
affected. However, it is reasonable to assume
that by utilizing all possible improvements in
materials, design, and construction it would be
possible to reduce the size of new pipe required,
or for existing pipe to carry more runoff.
23
-------
Pumping stations and other appurtenances
also are directly affected by the quantity of in-
filtration in any type sewer.
Existing infiltration allowances vary
widely. Interceptor design allowances from
only a few sources are reported to average from
500 to 4,000 gpd per acre. Assuming a metro-
politan area of 3,000 acres, the infiltration would
range from 1.5 to 12 mgd. It also is reported
for sanitary sewers that infiltration allowances
of 50 gcd are made. For a city of 1 million
sewered population this would amount to 50
mgd in the sanitary system. Hydraulieally,
this can mean collection and treatment facilities
for a city of approximately 500,000. The cost
burden is obvious.
Corrective measures involve both new and
existing sewers. New sewers involve the use of
more rigid specifications, including new joint-
ing methods, more stringent construction re-
quirements, and improved construction inspec-
tion and testing. Also required is a continu-
ing followup to prevent illicit connections, such
as roof leaders and yard drains, where excluded
by design. For existing sewers with breaks or
bad joints it no longer is necessary to excavate
and repair or replace faulty sections or joints.
Television inspection and inplace sealing meth-
ods have become available in recent years.
Continued improvements of these and other
methods are expected.
The effects and economic burden through-
out the country imposed by extensive infiltration
appear to warrant a major effort toward im-
provement of existing situations and the en-
couragement of new installations which will
excludo as much infiltration as possible.
Remedial Methods
The 50-plus engineering and special re-
ports examined are not necessarily representa-
tive of the national problem, but they formed
the only available sample. Since they repre-
sent a sizable portion of the population affected
by combined sewer overflows and stormwater
discharges, the variety of solutions considered
or initiated by these communities is significant
in assessing the overall problem. A tabula-
tion was made (table XIV) from these reports
showing various remedial measures considered,
recommended, and executed to solve the prob-
lem of control and treatment of combined sewer
overflows and stormwater sewer discharges.
Some explanation is necessary in order to in-
terpret the data to the best advantage. Be-
cause of the differing environmental influences
and other factors peculiar to each community,
and because of the comprehensive nature of en-
gineering investigations, many solutions are
considered and in some instances several simul-
taneous courses of action are recommended.
For these reasons there are multiple entries in
the table.
For convenience in evaluating this infor-
mation, the courses of action are grouped in two
general headings—primary and alternate.
The primary course of action, sewer separation,
is subdivided into separate storm sewers, sepa-
rate sanitary sewers, separate roof drains,
separate yard and areaway drains, separate air-
conditioner flows, separate foundation drains,
separate catch basin drains, and separate water
cooling systems.
Primary Methods
The first two of these "Primary" subdivi-
sions appear in the forms shown because some
communities considered the installation of new
separate storm sewers with the use of existing
combined sewers for sanitary purposes, while
others considered the construction of new sani-
tary sewers with the use of existing combined
sewers for stormwater.
Complete separation requires all the
courses of action indicated. It is obvious from
the data that not only has complete separation
not become a reality but the frequency of its
consideration and recommendation is low. The
financial consideration of making the required
changes in existing sewered communities is
enormous. Therefore, the tendency has been to
recommend the course of action which will fit
most practically the community's economic
capability. Most often this has resulted in se-
24
-------
Table XIV.—Remedial Measures for the Control
and Treatment of Combined Sewer Overflows
and Stormwater Sewer Discharges as Obtained
From Various Reports Discussing More Than 50
Communities in the United States.
Action
Remedial measure
Con-
Recom-
Exe-
sidered
mended
cuted
(a) Primary
Sewer separation;
Separate storm sewers
Separate sanitary sewers
Separate roof drains
Separate yard and areaway
drains
Separate air conditioner Flows...
Separate foundation drains
Separate catch basin inlets
Separate water cooling systems. ,
45
36
9
35
29
7
26
21
3
10
7
1
11
6
1
13
9
1
10
7
1
9
5
0
(b) Alternate
Treatment:
New treatment works
Expand, enlarge existing plants..
Holding tanks*
Lagoons, ponds, lakes*
Storage:
Additional sewer capacity
Bleed to treatment or streams**- ¦
Guttering
Inlet retention
Street and roadway retention....
Miscellaneous:
Improved zoning and land con-
trol use
Control of infiltration
Regulation, diversion, and mon-
itoring
4
4
2
4
2
1
9
4
2
9
3
1
27
22
5
3
3
1
4
3
1
1
1
1
5
4
2
4
3
3
9
7
2
2
~Also classed as storage.
~~Considered with operation of holding methods.
lecting the degree of partial separation beyond
separate sewers which can be done with the
greatest ease and least cost and yet provide
maximum benefits.
The table indicates that, in addition to sepa-
rate sewers, the change most commonly recom-
mended is to connect roof drains with storm
sewers. This can be done by direct connection
to the sewers or by connection of the roof drains
to catch basins. The data further show that,
while engineering studies have led to recom-
mendations in several locations to provide all
the steps for complete separation, the communi-
ties usually have chosen not to execute the com-
plete list. Undoubtedly, the major factor in
these compromises is the heavy financial
burden.
Further analysis of the data reveals that
only one of the communities surveyed is im-
plementing recommendations for a complete
separation program. This is being accom-
plished under a planned 60-year program and
is not in reality providing total separation be-
cause of incomplete cooperation on the part of
individual property owners and because of other
technical factors.
It is also clearly shown that many com-
munities did not consider total separation, but
for those which did, some two-thirds to three-
fourths of the engineers recommended total sep-
aration. That a higher proportion of the com-
munities did not consider total separation is
understandable since many of the studies were
authorized specifically for such purposes as the
alleviation of local flooding or treatment needs.
Alternate Methods
Alternate methods considered are grouped
under the three headings of (a) treatment, (b)
storage, and (c) miscellaneous. However, the
methods are here discussed in the order of their
frequency of consideration.
1. Additional Sewer Capacity
Of the alternate methods considered, by far
the most frequent recommendation was for ad-
ditional sewer capacity. This is logical since
the individual studies revealed that the present
systems were inadequate to handle the combined
and stormwater flows. Reasons for the in-
adequacy include both increased number of con-
nections and increased concentration of popu-
lation. Addition of industrial wastes, although
largely undefined as to specific quality, is ft
factor. Increased infiltration is a further con-
tributor, as is an increase in runoff due to a
larger area of paved or other impervious
surface.
2. Control of Infiltration
The next most frequent method and posi-
tive recommendation was control of infiltration.
25
-------
This has been discussed in detail earlier in this
report.
3. New or Enlarged Treatment Plants
Treatment methods also were considered by
a number of communities. Considerations were
about equally divided between new or expanded
wastewater treatment plants, and holding tanks
and lagoons or natural bodies of water. None
of these methods is a new solution, but there is
considerable diversity of opinion as to the rela-
tive merits of the holding-type treatment and
much work is needed to clarify the various
factors.
One of the alternates is the construction of
additional treatment facilities or the enlarge-
ment of existing treatment plants to accom-
modate the added load imposed by overflows
and/or stormwater. In some respects this is
not an alternate solution, but when considered
in the light that the plant would be provided
or enlarged to prevent the discharge of exces-
sive high-strength overflows, then it is an alter-
nate. Separate treatment of stormwater alone
could become necessary. In reality, it is not
known whether this will become necessary or,
for that matter, feasible, because of the many
variables. Valid comparisons with other meth-
ods of solution must await more factual
information.
There is some overlap in the classification
of the alternate methods. For instance, hold-
ing tanks, lagoons, ponds, and lakes are stor-
age devices as well as treatment methods.
4. Holding Tanks
There has been much interest in the use of
holding tanks because they permit a delay of
high peak discharges sufficiently long to allow
a leveling of load to the sewers. When holding
tanks are used to contain the flow within the
system, that is, to prevent or limit overflow,
the problem is transmitted to the treatment
plant. This procedure requires that the treat-
ment plant be able to handle the load. If it
cannot, then the excess will be bypassed and
the result is the same as with no holding tanks,
except that grit and other heavy solids can be
removed in the holding tank.
Another use of the holding tank is for
treatment. The treatment may be removal of
solids, or such removal plus chlorination for dis-
infection of pathogenic organisms. In Boston,
for instance, holding tanks are used and the
retained flow, after chlorination, is discharged
directly into Boston harbor on each outgoing
tide.
Holding tanks are not new. Columbus,
Ohio, as an example, has had them for 30 years.
New York City recently announced plans for
an extensive system of holding tanks which will
receive overflows from combined sewers, pro-
vide hypochlorination to the influents through
three vertical pipes in each inlet sewer, and
return the effluent to the system for transfer to
existing wastewater treatment plants (24).
There will be four plants designed to hold a
total of 37.5 million gallons for this purpose.
The announced aim is to eliminate beach
pollution.
5. Lagoons, Ponds, Lakes
Lagoons, ponds, and lakes, also suggested,
are similar to holding tanks. These bodies of
water will hold and level the flow, and they
also will act as stabilization ponds if the flow is
held for an appreciable time. The use of these
may have been suggested by a natural depres-
sion, such as a quarry, near an area needing sur-
charge capacity, as was the case at Buffalo,
N.Y. In other instances, the depression may
be designed and built for the purpose.
Lake Temescal in Oakland, Calif., is an
artificial lake which is used as a balancing res-
ervoir. Originally it was a water supply reser-
voir but was abandoned for this use as the
watershed was developed. Concurrent with
use as a stormwater holding device has been
its use for recreational purposes. Lakes in the
Seattle, Wash., area have been considered for
the same purpose. On the other hand, Tacoma,
Wash., built a lagoon to control stormwater
damage in nearby areas.
Lagoons also provide possibilities for mul-
tiple water use. They have been considered
in the Chicago area where industrial water
sometimes is short. The stored water would
receive treatment prior to use by the industry.
One community considered the use of surge
tanks to store temporarily in storms the water
discharged from large water users.
26
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6. Guttering, Inlet Retention, and
Street and Roadway Retention
A method judged to be of somewhat lesser
potential is a. program of storage through the
use of guttering, catch basin, inlet retention,
and roadway detention. With proper design
there can be some delay in the runoff reaching
the sewer system which will reduce the over-
flows at diversion points in the system.
7. Disinfection
Separate chlorination of stormwater and/
or combined overflow in continuous contact
chambers is another alternate method. Camp
(3) reported results of tests to determine chlo-
rine dosage requirements and discussed the ap-
plications of the method. He indicated that
in many instances it should be possible to use
unlined earthen chambers as contact tanks.
Contact surface areas required were roughly
from 1 acre for a tributary area of 1 square
mile to 5 acres for a tributary area of 10 square
miles. He found that, a chlorine dose of not
more than 10 times the average required for
dry-weather flow would be adequate.
8. Improved Zoning and hand Use
Control
Improved zoning and control of land use
are factors which must be considered in pro-
viding alternate solutions. Constant changes
in zoning with resulting change in land use and
surface characteristics as well as population
densities impose conditions for which existing
sewer systems were not designed. These con-
tinuing changes suggest that advance planning
on an area wide basis would be of significant help
in making it possible to use a collection system
to best advantage.
9. Regulation, Diversion, and
Monitoring
Regulation, diversion, and monitoring com-
prise still another method of control. Minne-
apolis, Minn., is considering a plan of automatic
control and regulation of its combined system
to reduce the frequency of overflows. This is
in conjunction with the city's long-range sepa-
ration program and in concept utilizes the sewer
capacity for storage. Also, Cincinnati, Ohio, is
considering a monitoring program to evaluate
and hopefully arrive at a solution to its problem
of excessive overflows.
Studies by Others
During their work on metropolitan Seat-
tle's sewerage and drainage survey, Brown and
Caldwell (25), in 1957, compiled information
from 16 other cities in the United States and
Canada regarding separation of combined sys-
tems. While there have been changes since this
survey, the results in general remain valid.
Nine of the 16 cities studied by Brown and
Caldwell are included in the current study.
These include Baltimore, Md.; Boston, Mass.;
Buffalo, N.Y.; Chicago, 111.; Detroit, Mich.;
St. Louis, Mo.; Minneapolis, Minn.; New York,
N.Y.; Oakland, Calif.; Portland, Oreg.; Spo-
kane, Wash.; St. Paul, Minn.; Toledo, Ohio;
Vancouver, British Columbia; Washington,
D.C.; and Winnipeg, Manitoba.
Three cities (Baltimore, Oakland, and
Toledo) have sewers and storm drains which
are principally separate. Five (Chicago, De-
troit, St. Louis, Spokane, and Winnipeg) have
mostly combined sewers; and 8 (Boston, Buf-
falo, Minneapolis, New York, Portland, St.
Paul, Vancouver, and Washington) have com-
binations of separate and combined systems.
Roof drainage is allowed to discharge to
the ground surface in half of these cities. In
several, the roof drainage goes into the street
gutter by way of a surface drain or leader from
the house.
Foundation drainage is discharged to the
sanitary sewers in seven of the cities (Buffalo,
St. Louis, Oakland, Spokane, Toledo, Washing-
ton, and Winnipeg) except in a few cases where
storm drains are deep enough to receive it. In
Baltimore and Vancouver, storm sewers, where
provided, are designed to receive foundation
drainage. Seven of 10 citie9 reported that pres-
ent residential drainage practices must be modi-
fied to conform to separation programs under-
way. Boston, Buffalo, and St. Paul indicated
that cost and other obstacles made it infeasible
to require alteration of connections to effect
complete separation.
The cities of Buffalo, St. Louis, Minneap-
olis, Spokane, Toledo, and Vancouver allow
27
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basement drains into the sanitary system while
Washington does not.
Five cities (Baltimore, Boston, Buffalo,
Minneapolis, and Washington) are currently
financing separation with general funds or have
done so in the past,; however, most of their work
applies to systems nearly complete or is of com-
paratively minor nature. Washington is a
notable exception where a major project is being
financed by general funds.
Most of the cities report financing as the
major problem in a separation program. Five
cities (Buffalo, Chicago, Detroit, St. Louis, and
New York) either indicated or implied that no
separation was proposed.
The study revealed a trend toward separa-
tion as water quality standards improve, but
that separation depends on local factors and
that each case must be worked out in the light
of controlling conditions.
In general, it is believed that the final
answer will depend on: (a) the capacity of exist-
ing sewers, (b) the frequency and intensity of
rainfall, (c) the importance and uses of the
water into which is discharged the overflow of
diluted sewage and stormwater, and (d) the
cost of construction and maintenance.
Costs
Complete Separation
Estimated costs for complete separation as
reported by 16 cities are given in table XV.
Toronto, Ontario, is included in the table as a
matter of interest, but is not included in the
computations. The 15 U.S. cities represent
sewered populations of approximately 21 mil-
lion and indicate a total cost of $9.4 billion.
Table XV.—Estimated Costs for Complete Sep-
aration of Stormwater and Sanitary Sewers
City
Chicago, III
Cleveland, Ohio....
Concord. N.H
Detroit, Mich
Haverhill, Mass....
Kansas City, Kans...
Lawrence, Kans.,, .
Lowell, Mass
Milwaukee, Wis....
New Haven, Conn..
New York, N.Y....
Portland, Oreg
Seattle, Wash
Spokane, Wash
Toronto, Ontario. . .
Washington, D.C, ,,
Total
Total project
cost
$2,300,000,000
470,000,000-
700,000,000
8,000,000
1,315,000,000
30,000,000
20,000,000
30,000,000
70,000,000
425,000,000
10,000,000
4,000,000,000
100,000,000-
250,000,000
145,000,000
50,000,000
285,000,000
214,000,000
9,662,000,000
Cost/acre
$17,000
12,000-
18,000
10,500
1 7,745
13,500
12,000
8,250
'16,363
25,000-
30,000
3,100-
7,750
3,890
1,800
17,000
18,000
»12,427
Cost I
capita
$482
360-535
280
360
650
187
915
780
440
560
492
260-652
260
415
250
3 468
1 Based on actual project cost.
' Using the average costs for those cities reporting ranges.
U.S. only.
Eight are large cities with serious problems
and therefore may provide an unbalanced
sampling for projection purposes. Indicated
costs per acre of city area vary from $1,800 to
$30,000 and average $11,800. Computed on a
per capita basis, the ranges are narrower, from
$187 to $915, with an average of $465.
Even though there is considerable reason
to doubt the validity of direct projection of these
costs to obtain a total estimate for the United
States, they are offered here as a base from
which other estimates can be drawn.
Assuming that this is a representative
sample and using the total number of people (59
million) served by combined sewer systems and
by combinations of combined and separate sys-
tems as shown in table I, the total United
States cost for complete separation would be
$27.4 billion. This assumes that all communi-
ties fall within the limits of the sample, which
is believed to be too small to be reliable.
It might at first be predicted that the cost
per capita is less in large cities than in small
communities; however, this is not demonstrated
in the data. The eight large cities represent
about 20.5 million people and the average cost
per capita is $400, while the nine smaller cities
total about 0.6 million and the average cost is
$540 per capita. Therefore, the total cost could
well be more than $27.4 billion. Further, these
cost figures do not represent 1964 dollars. Most
are from preliminary estimates and some are
several years old.
28
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These rather crude manipulations of data
indicate that total separation costs could amount
to $25-$30 billion, or even more.
Partial Separation
Costs of partial separation are more diffi-
cult to bracket because of the varying degrees
of separation proposed. Therefore, less reliance
is placed on the ability to place the cost estimates
in a common frame of reference.
Partial separation costs vary with the
extent of separation of roof drains, area way
drains, foundation drains, air conditioning and
other cooling water, and yard drains. One city
will permit certain of these waste sources in the
sanitary sewer while others will not (25). Some
will permit combinations such as allowing
owners to pump foundation drains to sanitary
sewers.
The project may be separation of sewers
only, or it may be separation of sewers plus sep-
aration of one or more of the additional sources
of stormwater in sanitary sewers.
With these conditions as background, the
available partial separation costs are shown in
table XVI.
Information was available from 18 com-
munities totalling 2.1 million people. Esti-
mated costs for the various projects covered
Tabic XVI.—Eiti mated Costs for Partial Separation
of Stormwater and Sanitary Seweri
Cily
Total project
cost
Coit/
acre
Coit/
capita
Des Moines, Iowa
Elmhurst, III
Eugene, Oreg
Find lay, Ohio
Granite City, III
Hannibal, Mo
Kendallville,lnd
Lafayette, Ind
La Porte, Ind
Lathrup Village, Mich.
Louisville,JKy.......
Michigan City, Ind....
Minneapolis, Minn. . .
Mishawaka, Ind
Napa, Colo
Seaalia, Mo
Seattle, Wash
Tacoma, Wash
Total
$25,000,000
8,770,000
3,410,000
15,108,000
13,200,000
613,000
969,000
5,024,000
9,187,000
961,500
30,538,000
3,500,000
30,000,000
4,392,000
1,549,000
4,470,000
69,000,000
7,960,000
17,800
3,100
4,900
3,040
972
640
1,860
$170
237
76
500
330
43
143
120
437
302
73
95
69
129
52
213
124
53
233,651,500
'3,187
'176
> Average.
total $244 million. Cost per acre was available
from only seven cities, but from those the varia-
tion was great—from $640 to $7,800 and aver-
aging $3,045. The cost per capita ranged from
$48 to $500 with an average of $176.
Using the same assumptions as for total
separation, the nationwide United States cost
for partial separation would be $10.4 billion.
Although this total is believed to be far less
reliable than the estimate for total separation,
it shows the order of magnitude of the prob-
lem's financial aspects.
Unit Costs for Individual Separation Items
Little information was available for single-
item costs in a separation project.
Seattle and Tacoma provided unit cost
estimates as follows:
House sewer reconnections $40.00
Catch basin reconnections 80.00
Manhole connections 100.00
New house sewers 300,00
Washington, D.C., estimated the following
unit costs for changes of plumbing and house
connections:
Single-family house, unfin-
ished basement $1,200
Single-family house, no base-
ment 2,000
Small apartment with base-
ment 1,750
Larger apartment, at least 5,000
Shop with storage basement-_ 2,000
Shops, no basement 4,500
Shops, store, office building,
with basement 5,000
All unit-cost information is believed to be
too limited to make any generalization for other
areas.
Alternate Methods
1. Holding Tanks
More data were available for holding tanks
than for other alternate methods. Available
costs appear in table XVII.
-------
Table XVII—Available Costs for Holding Tanks
for Temporary Impoundment of Combined and/or
Stormwater Overflows
City
Clinton, low a
Haverhill, Mass
Lawrence, Mass
Lowell, Mass
Mission Township Main
Sewer District No. 1, Kans-
New York, N.Y.
Jamaica Bay
Eastchester Bay
Upper East River
Total project
cost
$2,655,000
25,000,000
21,000,000
53,000,000
4,000,000
65,000,000
35,000,000
81,000,000
Cost per
acre
$1,400
8,800
9,500
9,150
1.000
5.1 50
2,1 30
3 5,304
Cost
per
capita
$88
545
300
590
67
0)
(')
(')
* 318
1 Unknown population served.
2 Averase.
There are wide variations in the extent and
characteristics of holding tank projects, which
account for the range in unit costs. The cost
information may be useful to establish ranges,
but again the many local factors make it diffi-
cult to generalize from averages. The New
York City project, for instance (24), has been
under study for some time but actual construc-
tion costs are not firmly established. It will
eventually cover three drainage areas in and
around New York City and will be done in
three phases over a period of several years.
The available estimates for these projects total
$181 million, while the estimate for total sepa-
ration was $4 billion. However, the holding
tank project covers only a part of the area in-
cluded in the total separation estimate. Eval-
uation of the effectiveness of this holding tank
project of necessity will not be possible for some
time.
There is little operational information
available from any source to evaluate the hold-
ing tank method. Columbus, Ohio's holding
tanks, built in 1934, are reported to be gen-
erally successful. However, cleaning opera-
tions are reported to result in load problems
at the wastewater-treatment plant which re-
ceives the settled material. Odor complaints
also have been received during tank cleaning
operations.
No uniformity in design criteria is appar-
ent. Some tanks may be designed for short-
time balancing to control surcharging while
others are designed for partial treatment by
settling and chlorination of the overflow. Rela-
tionships between tributary area and holding
tank capacities are necessary but these rela-
tionships are subject to considerable modifica-
tion by local conditions.
2. Chlorine Contact Tanks
Cost information for three cities with chlo-
rine contact tanks was located. These costs ap-
pear in table XVIII. Unit costs were quite
uniform at about $4,200/acre. Per capita costs
of two were in close agreement, in the order of
$250, while the third was about $100 less. All
three being in the same geographical area im-
poses limits on the general usefulness of this
information elsewhere.
Since chlorine contact tanks have little
effect on the removal of solids or BOD their
primary purpose of partial disinfection is lim-
ited in ultimate usefulness as compared to com-
plete separation and treatment and some of the
other methods. However, the control of coli-
form organisms and viruses as protection for
water supply, recreational, shellfish propaga-
tion, crop irrigation, or other water uses must
be assigned high priority. The method needs
extensive evaluation in several locations to es-
tablish its long-range merits.
Although the cost of chlorine contact tanks
is far less than separation and holding tanks,
the cost of chlorine in the operation must be
included in the full cost. For the three cities
from which information was available, this cost
amounted to about 50 cents/person/year.
Table XVIII.—Costs of Chlorine Contact Tanks for
Partial Disinfection of Combined and/or Storm-
water Overflows
City
Total project
cost
Cost per
acre
Cost
ptr
capita
Haverhill, Mais
Lawrence, Mass
Lowell, Mass
1 S11,500,000
' 9,800,000
»23,700,000
$4,050
4,400
4,060
$250
140
264
1 Annual chlorine cost, $30,000.
' Annual chlorine cost, $24,000.
1 Annual chlorine cost, $56,000.
3- Lagoons, Ponds, and hakes
Although lagoons, ponds, and lakes have
been used as control methods, cost data were
meager. In some reported instances, existing
30
-------
ponds, lakes, or quarries were used and this
made it difficult to assign costs to the projects.
In other instances, cost breakdowns were not
clear because the storage facilities were included
as a part of multiple use projects involving
other installations.
With these limitations, costs were available
for only three installations as shown in ta-
ble XIX.
Table XIX.—Costs of Lagoons Used for Controlling
Stormwater Flow
City
Exeter, N.H
Richards Gebaur Air Force
Base, Mo
Takoma, Wash
Total
project
cost
$320,000
280,000
115,000
Cost
per
acre
S640
700
1 39
Cost
per
capita
$80
19
1 Estimated From incomplete data.
These costs have no degree of reliability
for comparative analyses except that unit costs
appear to be substantially below other alter-
nate methods discussed.
4. Other Storage Methods
Specific costs were unavailable on the other
storage methods considered.
Those cities which have provided addi-
tional sewer capacity have not made clear the
costs for this purpose because other sewers are
involved in the projects. Special analyses of
these projects would be necessary to break out
the costs attributable solely to extra storage
capacity.
Similar analysis problems were apparent
in considering guttering, inlet retention, and
street and roadway retention.
5. Other Treatment Methods
Where new and/or expanded treatment
works were considered, costs again were in-
cluded with other treatment benefits and were
not amenable to separate accounting.
6. Miscellaneous Methods
Although three communities have insti-
tuted improvements in zoning and land use
control, specific costs or values of benefits were
not available. Only two cities are studying
regulation, diversion, and monitoring to evalu-
ate their usefulness and costs in relation to
stormwater overflows. Their studies were in
the preliminary stages and hence the informa-
tion was quite limited. However, each city in-
dicated expenditures of about $1 million for
installation of monitoring and regulation
equipment.
Discussion
Only a sampling of the overall problem of
stormwater and combined sewer overflows was
possible in this preliminary investigation with
its limited sources of in formation. N evertheless
this sampling should sufficiently indicate the
character and magnitude of the problems and
hopefully it will provide guidelines toward
solutions.
Stormwater and overflows from combined
sewers constitute problems which increase with
urbanization and the attendant rise in water
usage. The problems vary from basement
and street flooding to gross pollution of water
courses which often must be used for high
quality purposes such as drinking water sup-
plies. Local studies by various cities over a
period of many years have recognized the prob-
lems, and some are proceeding under enormous
financial burdens toward corrective measures.
There are many indications of local study
and partial action on the problem but there has
been no nationwide assessment. Local experi-
ences make it clear that many factors peculiar
to each area make it difficult to generalize con-
cerning corrective measures. Weather condi-
tions, land contours, and land uses, differ from
place to place. Streams vary in size, character,
and in the use that is made of them. Types of
sewers, concentration of population, incidence
of industry, and other factors have their
influence.
This report attempts to define the problems
and it explores possible solutions along with the
all-important costs.
81
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Reliable data are difficult to accumulate be-
cause most sources were but preliminary studies,
and many of these explored only a single phase
of the problems arising from stormwater and
combined overflows. This made it necessary to
selectively extract data which in many cases
were mixed with other project studies. Despite
the limitations inherent in this method of ap-
proach, it is felt that the study here documented
reveals many significant facts.
Problems posed by combined sewer systems
are of major significance. Fifty-nine million
people live in 1,940 U.S. communities whose
sewer systems are wholly or partially of the
combined type which must carry both municipal
sewage and excess stormwaters. If a majority
of these communities share the all-too-common
problem of sewer overflow and inadequate treat-
ment plant capacity in periods of heavy rain-
fall, there is cause for real concern.
The study reveals that many communities
experience overflows from combined sewers in
significant quantity even in dry weather. In
fact, some systems are designed to accommodate
this situation. This means that unknown quan-
tities of relatively high pollutional strength
wastewater are being discharged untreated to
receiving streams. Few cities systematically
measure the quantity or quality of these
discharges.
In terms of quantity, the study reveals that
an average of 3 to 5 percent of all raw waste-
water is annually discharged by overflow from
combined sewers to watercourses. Based on the
59 million population affected by combined
sewers or partially combined sewer systems and
figuring the minimum 3 percent overflow,
nearly 65 billion gallons of raw sewage per year
enter the Nation's watercourses during storms.
This amount does not include the stormwater
which was not estimated as to total quan-
tity. However, the combined overflows would
contribute to the watercourses annually about
100 million pounds of BOD attributed to domes-
tic wastewater only. Most of this could be pre-
vented if the overflow conditions did not exist.
The degree of bacterial contamination con-
tributed to the watercourses by overflows was
shown to be far beyond that which will allow
the streams to meet accepted standards. Storms
which occur in the summer on the average of
once every few days overtax the receiving
waters and render them unsuitable for recrea-
tional and other uses.
It was also confirmed that stormwater alone
carries significant organic, inorganic, and bac-
terial contamination to streams. The greatest
load occurs at the beginning of the storm. Par-
ticularly disturbing is the widespread confirma-
tion that during storms up to 95 percent of the
sanitary waste is discharged to the stream by
overflow.
Based on quantity and quality analyses of
stormwater and combined overflows, the prob-
lem is of major significance. However, there is
much to be learned in order to define the entire
problem more clearly.
Evidence of various damages caused by
stormwater and overflow^ was common. The
most frequent is basement flooding with its
obvious health implications. Included among
other damages were nuisances, decreased prop-
erty values, impaired recreational use of
waters, and increased treatment cost. It was not
possible to relate dollar values to these damages
but the amounts implicated are enormous.
Studies are needed to establish damage-cost
relationships. The full range of water uses is
affected.
Throughout the study it was repeatedly
demonstrated that investigations of the many-
faceted stormwater and combined sewer over-
flow problem are meager, scattered and gen-
erally incomplete. Such fundamental factors
as the effect of such discharges on stream qual-
ity are relatively undocumented. Without
doubt, deleterious effects are imposed on streams
but the precise degrees are largely unknown or
unavailable. Obviously, to place the problem
in proper perspective, more work is needed in
this area.
Another of the persistent problems is the
gross hydraulic load imposed on the sewer sys-
tem and treatment facilities by infiltration.
When cities of 1 million population deliber*
ately design their sewer system to accommodate
50 gpd/capita, or 50 mgd of infiltration, the
time is overdue to investigate means of elimi-
nating or materially reducing such practice.
Improvements in jointing materials, in detec-
tion of sewer leaks, and repair methods should
be investigated thoroughly.
Adding to the overall problem is the omis-
sion in most of the source information of any
82
-------
consideration of industrial contributions to the
overflows. Industrial wastes intensify the
problem and there are strong indications from
some sources that the industrial waste con-
tribution is substantial.
The second phase of the study examines
methods and costs for solving the problem.
Complete separation of storm and sanitary
sewers and treatment of all waste, both sani-
tary and storm would provide ultimate pro-
tection to watercourses. Short of this are
various compromise measures with varying de-
grees of benefits.
A few separation projects are underway,
mostly in larger cities, and all under long-range
plans. Invariably, even though the needs are
clear, the projects are delayed or reduced be-
cause of the enormous financial burdens.
Rough estimates of complete separation costs
for the United States are in the 25 to 30-
billion-dollar range, and possibly more.
Not considered in assembling the cost in-
formation is the monetary loss which occurs as
the result of physical inconveniences during
the construction period in a separation project.
Extensive excavation is necessary in streets and
other areas and progress usually is slow. Indi-
viduals, businesses, industrial establishments,
and, in fact, entire communities are subjected to
temporary economic loss because of inaccessi-
bility. Here again it was not possible to as-
sign dollar values, but the amount would no
doubt be substantial.
The complex and long-range nature of the
problem makes it a fundamental part of metro-
politan regional planning. In this regard,
planners need to be supplied more and better
information.
Partial separation, in the various degrees
considered and executed, can provide substantial
relief. Several cities have initiated this type
of program, perhaps in the hope that full sep-
aration can be provided later. As would be
expected, costs are somewhat less than for com-
plete separation but still are impressive. The
degree of protection afforded to receiving
waters is unknown in detail and requires fur-
ther evaluation.
Alternate methods have been considered
and used, though most have received only cur-
sory evaluation. New York has launched the
most extensive program utilizing alternate
methods. A series of combined overflow hold-
ing tanks is being installed with chorination
of the effluent prior to its return to the sanitary
treatment system. This method was selected
because of its smaller cost in comparison with
total separation. Evaluation of its effective-
ness will not be known for some time.
Other methods in use include lagoons, lakes,
or abandoned quarries; and chlorine contact
chambers. Several other methods have been
considered and it is expected that still others
having more effectiveness, perhaps at less cost,
will be developed. Intensive study of separa-
tion methods and alternate solutions is strongly
recommended. There is real concern that in-
creasing urbanization will result in combined
sewer and storm water overflows discharging
organic loads to the Nation's streams which will
increase at a rate greater than existing or
planned corrective efforts can handle.
The preliminary study of the nature and
characteristics of stormwater and combined
sewer overflows, their effects on watercourses,
and possible solutions to problems created re-
vealed the following:
1, Approximately 59 million people in
more than 1,900 communities are served, by
combined sewers and combinations of combined
and separate sewer systems.
2. Existing sewer systems are inadequate
to handle sanitary wastewater and stormwater
without creating excessive overloads at treat-
ment plants and throughout the sewer systems,
and as a result these overloads are discharged
to the available water courses.
3. Stormwater and combined sewer over-
flows are responsible for major amounts of pol-
luting material in the Nation's receiving
waters and the tendency with growing urban-
ization is for these amounts to increase.
4. Both combined overflows and storm-
water contribute significant amounts of pollu-
tional materials to watercourses.
5. These discharges affect all known water
uses adversely in the receiving water courses.
-------
6. Significant economic loss results from
the damages caused by these discharges al-
though precise levels of these damages remain
to be determined.
7. Damages occur more frequently during
the summer storm season but many systems
are so overloaded that overflow occurs during
dry weather throughout the year.
8. Infiltration is a major problem contrib-
uting to hydraulic overloading of sanitary,
combined, and storm sewers.
9. Complete separation of stormwater
from sanitary sewers and treatment of all waste
is the ultimate control measure to provide maxi-
mum protection to receiving waters.
10. Other solutions which have been con-
sidered, separately or in combination, include:
(a) partial separation of roof, yard, area way,
foundation, and catch basin drains rrom sani-
tary and combined sewers; (b) expanded or
new treatment facilities; (c) holding tanks,
with or without chlorination; (d) disinfection;
(e) storage using lagoons, lakes, quarries, and
other depressions; (f) storage using guttering,
streets and roadways, and inlets; (g) addi-
tional sewer capacity; (h) regulation and con-
trol of flow through the sewer system; and (i)
improved planning and zoning.
11. Evaluation of the effectiveness of all
methods except complete separation is unavail-
able because of the lack of installations to
study.
12. Total costs for complete separation
based on scattered information are estimated
to be in the $20 to $30-billion range.
13. Costs for partial separation are esti-
mated to be a substantial fraction of those for
complete separations and costs for alternate
methods are estimated to be in the multibillion-
dollar bracket.
Recommendations
Based on the study reported herein, recom-
mendations for action are as follows:
1. Comprehensive studies should be ini-
tiated to expand on the preliminary study and
explore in depth its objectives. These studies
should be sufficiently detailed to provide an un-
derstanding, on a national basis, of the present
limits, reliable predictions for the future? meth-
ods of solution, and costs. In the examination
and evaluation of methods for correction, proj-
ects must be sufficiently large to be assured of
practical results. In the economic analysis full
recognition should be given to evaluation of
present and potential losses or deleterious ef-
fects in relation to protection of the nation's
waters for public use.
2. Extensive followup studies should be
carried on to provide full evaluation of the cor-
rective methods.
3. Demonstration projects for the develop-
ment of new or improved methods for control-
ling the discharge of sewage and stormwater
from combined sewer systems would provide an
effective mechanism for the conduct of these
studies and the acquisition of actual design, con-
struction, and performance data. They would
have the added advantage of representing an
attack on the problem as well as providing in-
formation for future action,
4. Final recommendations for solution of
the problem on a massive basis must await re-
sults of the studies recommended herein.
References
1. U.S. department of Health, Education, and
Welfare, Public Health Service, "1962 Inven-
tory Municipal Waste Facilities" in 9 volumes,
PHS Publication 1065, Washington, D.C.
(1963).
2. McKee, J. E., "Loss of Sanitary Sewage
Through Storm Water Overflows." Journal of
Boston Society of Civil Engineers, 34, 2, 55
(Apr. 1947).
3. Camp, T. R., "Chlorination of Mixed Sew-
age and Storm Water." Journal of Sanitary
Engineering Division, American Society of
Civil Engineers, 87, SAl, Part 1,1 (Jan. 1961).
4. Palmer, C. L., "The Pollutional Effects of
Storm-Water Overflows from Combined Sew-
ers." Sewage and Industrial Wastes, 22, 2,154
(Feb. 1950).
5. Palmer, C. L., "Feasibility of Combined
Sewer Systems." Journal Water Pollution
Cordrol Federation, 35, 2, 162 (Feb. 1963).
6. Johnson, C. F., "Nation's Capital Enlarges
Its Sewerage Systems." Civil Engineering, 28,
2,56 (June 1958).
84
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7. Camp, T. R., "Overflows of Sanitary Sewage
From Combined Sewerage Systems." Sewage
and Industrial "Wastes, 31,4,381. (Apr. 1959).
8. Riis-Carstensen, E., "Improving the Effi-
ciency of Existing Interceptors." Sewage and
Industrial Wastes, 27, 10, 1115 (Oct. 1955).
9. Shifrim, W. G., and Horner, W. W., "Effec-
tiveness of the Interception of Sewage-Storm
Water Mixtures." Journal of Water Pollution
Control Federation, 33, 6, 650. (June 1961).
10. Moorhead, G. J., "Overflows From Com-
bined Sewers in Washington, D.C." Journal
Water Pollution Control Federation, 33, 7, 711
(July 1961).
11. Johnson, C. F., "Equipment, Methods, and
Results From Washington, D.C., Combined
Sewer Overflow Studies." Journal Water Pol-
lution Control Federation, 33, 7, 721 (July
1961).
12. Greeley, S. A., and Langdon, P. E., "Storm
Water and Combined Sewage Overflows."
Journal Sanitary Engineering Division, Am-
erican Society of Civil Engineers, 87, SA1, Part
1,57 (Jan. 1961).
13. Benjes, H. H., Haney, P. D., Schmidt, 0. J.,
and Yarabeck, R. R., "Storm-Water Overflows
From Combined Sewers." Journal Water Pol-
lution Control Federation, 33, 12, 1252 (Dec.
1961).
14. Gameson, A. L. H., and Davidson, R. N.,
"Storm-Water Investigations at Northamp-
ton." Journal and Proceedings Institute of
Sewage Purification, Part 2, p. 105 (1963).
15. U.S. Department of Health, Education, and
Welfare, Public Health Service, Division of
Water Supply and Pollution Control, Great
Lakes-Illinois River Basins Project, "Report on
the Illinois River System—Water Quality Con-
ditions." Part I Text, Chicago, 111. (1963).
16. Weibel, S. R., Anderson, R. J., and Wood-
ward, R. L., "Urban Land Runoff as a Factor
in Stream Pollution." Journal Water Pollu-
tion Control Federation, 36, 7, 914 (July 1964).
17. Los Angeles County Flood Control District,
Water Conservation Division, internal mem-
orandum titled "Interpretation of Data Col-
lected During Storm Water Sampling Pro-
grams." Los Angeles, Calif. (Aug. 13,1963).
18. Sylvester, R. O., "An Engineering and
Ecological Study for the Rehabilitation of
Green Lake." University of Washington,
Seattle, Wash. (1960).
19. Wilkinson, R., "The Quality of Rainfall
Runoff Water From a Housing Estate." Jour-
nal Institute Public Health Engineers, London
(1954).
20. Shigorin, G. G., "The Problem of City Sur-
face Runoff Water." Vodosnabshenie i Sani-
tarnayaTekknika,2,19 (1956).
21. Akerlinch, G., "The Quality of Storm
Water Flow." Nordisk Hygienisk Tidskrift
(Stockholm), 31,1 (1950).
22. Stander, G. J., "Topographical Pollution—
The Problems of the Water and Sanitary En-
gineer." 40th Annual Conference, Institute
Municipal Engineers, National Institute Water
Research (1961).
23. Weller, L. W., and Nelson, M. K., "A Study
of Storm Water Infiltration Into Sanitary Sew-
ers." Joumal Water Pollution Control Federa-
tion, 35,6,762 (June 1963).
24. Anon., "City Plans to Treat Storm Water."
Engineering News-Record, 172,22, 36 (May 28,
1964).
25. Brown and Caldwell, "Summary of Drain-
age and Sewer Separation Survey, April 1957."
pp. 208-9 in "Metropolitan Seattle Sewerage
and Drainage Survey, a Report for the City of
Seattle, King County, and the State of Wash-
ington on the Collection, Treatment and Dis-
posal of Sewage, and the Collection and Dis-
posal of Storm Water in the Metropolitan
Seattle Area." Brown and Caldwell, Civil and
Chemical Engineers, San Francisco, Calif.
(Mar. 1958).
85
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Appendix
Engineering Reports, Completed Questionnaires,
and Special Reports Referred to in Study of
Combined Sewer Overflows and Stormwater
Discharges
Engineering Reports and Completed
Questionnaires
1. "Sewage Treatment Works and Intercepting
Trunk Sewers for the City of Amsterdam,
N.Y." William S. Lozier Co., Rochester, N.Y.
(Aug. 1947).
2. "Preliminary Report on Sanitary Sewage
Collection and Treatment for Ashland, Ken-
tucky." J. Stephen Watkins, Lexington, Ky.
and Howard K. Bell, Lexington, Ky. (Dec. 15,
1957).
3. Questionnaire completed by city of Atlanta,
Ga. (1963).
4. "Engineering Report on Sewerage and Sew-
age Disposal for the Metropolitan District Com-
mission of Boston." Charles A. Maguire and
Associates, Boston, Mass. (1962—63).
5. Questionnaire completed by city of Chat-
tanooga, Tenn. (1963).
6. "Report on Pollution From Overflows—The
Metropolitan Sanitary District of Greater
Chicago." Black and Veatch, Kansas City, Mo.
(1962).
7. "Sanitarv Sewerage System—Study and Re-
port for Clarksville, Tennessee." J. Stephen
Watkins, Lexington, Ky. (Nov. 1961).
8. "Report on Combined Sewer Overflow
Studies, Cleveland, Ohio." Stanley Engineer-
ing Company, Muscatine, Iowa (1963).
9. "Engineering Report on Stormwater Relief
Facilities, Trunk Sanitary Sewers, Sewage
Treatment Facilities, Intercepting Sewers,
Clinton, Iowa." Consoer, Townsend and Asso-
ciaites, Chicago, 111. (1958).
10. "1963 Report Sanitary Sewage Systems,
City of Des Moines, Iowa." Veenstra and
Kimm, Des Moines, Iowa (1963).
11. "City of Elmhurst, Illinois, Sewer System
Improvements, Engineer's Report." Baxter
and Woodman, Crystal Lake, 111. (1958).
12. "Sewer Study Report for City of Eugene,
Oregon." Cornell, Howland, Hayes and Merry-
field, Corvallis, Oreg. (1961).
13. "Report on Sewers, Findlay, Ohio." Jones,
Henry and Williams, Toledo, Ohio (1961).
14. "Report on Sewerage System Improve-
ments, Hannibal, Missouri." Stanley En-
gineering Company, Muscatine, Iowa (1959).
15. Questionnaire completed by city of Hart-
ford, Conn. (1963),
16. "Report on Present and Future Needs—
Water and Sewer Systems for Henderson, Ken-
tucky." J. Stephen Watkins, Lexington, Ky.
and Robert E. Martin, Louisville, Ky. (1953).
17. "Huron, South Dakota, Report on Muni-
cipal Trunk Sewer System." Schoell and Mad-
son, Hopkins, Minn. (1962).
18. "Report on Sanitary Sewerage System,
Iowa City, Iowa." Veenstra and Kimm, Des
Moines, Iowa (1963).
19. "Engineering Report—Sewer Separation
and Sewage Treatment for City of Kansas City,
Kansas." Truman Schlup, Kansas City, Kans.
(1953).
20. "Report on Master Plan for Trunk Sewers
and Sewage Treatment Facilities for Kansas
City, Missouri." Black and Veatch, Kansas
City, Mo. (1958).
21. "Sanitary Sewers and Storm Drainage.,
Kendallville, Indiana." Clvde E. Williams and
Associates, South Bend, Ind. (1963).
22. "City of Lafayette, Indiana—A Master
Plan for Sewers." Henry B. Steeg and Asso-
ciates, Indianapolis, Ind. (1963).
23. "City of LaPorte, Indiana—Sewerage and
Drainage." Charles W. Cole & Son, South
Bend, Ind. (1962).
24. "Report of Intercepting Sewers and Sew-
age Treatment for the City of Lathrup Village,
Michigan." Ayers, Lewis, Norris and May,
Ann Arbor, Mich. (1957).
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25. "Report to Board of Louisville and Jeffer-
son County Metropolitan Sewer District Upon
Drainage." Metcalf and Eddy, Boston, Mass.
(1963).
26. "Report on Proposed Sewage Works, Man-
chester, New Hampshire." Fay, Spofford and
Thorndike, Inc., Boston, Mass. (1962).
27. "Intercepting Trunk Sewers for the Village
of Massena, New York." William S. Lozier
Company, Rochester, N.Y. (1946).
28. "Engineering Report — Storm Drainage,
Sewage Collection and Treatment—City of
Michigan City, Indiana." Boyd E. Phelps,
Inc., Michigan City, Ind. (1962).
29. "Report on Reduction of Pollution From
Sanitary and Combined Sewers—Metropolitan
Sewer District—Milwaukee, Wisconsin." Al-
vord, Burdick & Howson, Chicago, 111. (1957).
30. "Expansion of Sewage Treatment Works
in the Minneapolis-St. Paul Metropolitan
Area—Minneapolis—St. Paul Sanitary Dis-
trict." Volumes 3 and 4, Toltz, King, Duvall,
Anderson & Associates, Minneapolis, Minn.
(1960).
31. "City of Mishawaka, Indiana, Report on
Sewerage and Drainage." Charles W. Cole &
Son, South Bend, Ind. (1962).
32. "Report on Sanitary Sewer Capacity and
Surface Drainage Survey for Mission Town-
ship Main Sewer District No. 1, Johnson Coun-
ty, Kansas." Black & Veatch, Kansas City, Mo.
(1959).
33. "Storm Water Separation and Drainage
Needs Napa County and Vicinity, California."
George S. Nolte, Palo Alto, Calif. (1961).
34. Questionnaire completed by city of Nash-
ville, Tenn. (1963).
35. "New Haven, Connecticut, East Street
Watershed Study—New Haven Redevelopment
Agency." Genovese & Cahn, New Haven, Conn.
(1962).
36. "Report, Elimination of Marginal Pollu-
tion—Jamaica Bay—to Department of Public
Works, New York, New York." Greeley and
Hansen, Chicago, 111. (1959).
37. Questionnaire completed for Omaha, Neb.
(1963).
38. "Report on Final Phases for Sanitary Sew-
ers, Sewage Treatment Works and Incinerator
for the village of Owego, New York." Wil-
liam S. Lozier Company, Rochester, N.Y.
(1946).
39. "Long Range Sewerage Program for Pre-
sumpscot River Basin Within Portland." Met-
calf & Eddy, Boston, Mass. (1958).
40. Questionnaire completed by city of Port-
land, Oreg. (1963).
41. Questionnaire completed by city of Provi-
dence, R.I. (1963).
42. "Pueblo, Colorado, Preliminary Reports
Proposed Storm Sewers for Special Improve-
ment District 61-2 and 63-2." Ken R. White,
Denver, Colo. (1963).
43. "City of Redding—Master Sewerage Plan,
An Engineering Report Concerning the Present
Capabilities and Future Requirements of the
City of Redding Sewerage System." Clair A.
Hill & Associates, Redding, Calif. (1956).
44. "Report on Long Range Plan for St.
Joseph, Missouri." Black & Veatch, Kansas
City, Mo. (1953).
45. "Supplemental Sewerage Report." Black
& Veatch, Kansas City, Mo. (1955).
46. "Report—Main Sewer Extensions and
Sewage Treatment—Proposed Improvements."
Black & Veatch, Kansas City, Mo. (I960).
47. "Salem, Oregon—Preliminan? Engineering
Study of Sewage Collection and Treatment Fa-
cilities for the City." Cornell, Howland, Hayes
& Merryfield, Corvallis, Oreg. (1960).
48. "Metropolitan Seattle Sewerage and Drain-
age Survey—A Report for the City of Seattle,
King County and the State of Washington on
the Collection, Treatment, and Disposal of
Storm Water in the Metropolitan Seattle
Area." Brown & Caldwell, San Francisco,
Calif. (1958).
49. "Sedalia, Missouri—Report on Storm and
Sanitary Sewerage System Improvements."
Burns & McDonnell Engineering Company,
Kansas City, Mo. (1956).
50. Questionnaire completed by the city of
Spokane, Wash. (1963).
51. "Report on Investigation of the Main Inter-
cepting Sewer System. O'Brien & Gere, Syra-
cuse, N.Y. (1961).
52. "Metropolitan Tacoma Sewerage and
Drainage Survey—A Report for the City of
Tacoma, Washington, on the Collection, Treat-
ment and Disposal of Sewage and the Collec-
tion and Disposal of Storm Water." Brown &
Caldwell, San Francisco, Calif. (1957).
53. Questionnaire completed by city of Texas
City, Tex. (1963).
54. "Sewage Treatment Works for the City of
Utica, New York." William S. Lozier, Roches-
ter, N.Y. (1946).
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55. "Report to District of Columbia Depart-
ment of Sanitary Engineering on Improve-
ments to Sewerage Systems." Board of En-
gineers—Samuel A. Greeley, Frank A. Mars-
ton, Gustav J. Requardt (Feb. 28, 1957).
56. "An Engineering Study of Waste Treat-
ment and Infiltration for the City of Yakima,
Washington." Cornell, Howland, Hayes &
Merryfield, Corvallis, Oreg. (1963).
Special Reports
1. Chanin, G., "Summary of Storm Water
Studies at the East Bay Municipal Utility Dis-
trict's Wastewater Treatment Plant." Oakland,
Calif, (undated memorandum); information
also obtained by interview.
2. U.S. Department of Health, Education, and
Welfare, Public Health Service, Division of
Water Supply and Pollution Control, Great
Lakes-Illinois River Basins Project, "Report
on the Illinois River System—Water Quality
Conditions." Part I Text, Chicago, 111. (1963).
Also cited as reference 15 in text.
3. Weibel, S. R., Anderson, R. J., and Wood-
ward, R. L., "Urban Land Runoff as a Factor
in Stream Pollution." Journal Water Pollu-
tion Control Federation, 36, 7, 914 (July 1964).
Also cited as reference No. 16 in text.
4. Board of Engineers—Samuel A. Greeley,
Frank A. Marston, Gustaf J. Requardt, "Re-
port to District of Columbia Department of
Sanitary Engineering on Improvements to
Sewerage Systems" (Feb. 28,1957). Also cited
in list of engineers' reports.
5. Los Angeles County Flood Control District,
Water Conservation Division, internal mem-
orandum titled, "Interpretation of Data Col-
lected During Storm Water Sampling Pro-
grams." Los Angeles, Calif. (Aug. 13, 1963).
Also cited as reference No. 17 in text.
89
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