Environmental Protection Technology Series
COUNTERMEASURES FOR
POLLUTION FROM OVERFLOWS
The State Of The Art
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EPA-670/2-74-090
December 1974
COUNTERMEASURES FOR POLLUTION FROM OVERFLOWS
The State of the Art
By
Richard Field
Storm and Combined Sewer Section (Edison, N.J.)
Advanced Waste Treatment Research Laboratory
National Environmental Research Center
Cincinnati, Ohio 45268
and
John A. Lager
Metcalf & Eddy, Inc.
Palo Alto, California 94303
Program Element No. 1BB034
NATIONAL ENVIRONMENTAL RESEARCH CENTER
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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REVIEW NOTICE
The National Environmental Research Center -
Cincinnati has reviewed this report and approved
its publication. Mention of trade names or com-
mercial products does not constitute endorsement
or recommendation for use.
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FOREWORD
Man and his environment must be protected from the adverse
effects of pesticides, radiation, noise and other forms of
pollution, and the unwise management of solid waste. Efforts
to protect the environment require a focus that recognizes the
interplay between the components of our physical environment —
air, water, and land. The National Environmental Research
Centers provide this multidisciplinary focus through programs
engaged in
o studies on the effects of environmental
contaminants on man and the biosphere, and
o a search for ways to prevent contamination
and to recycle valuable resources.
Essentially every metropolitan area of the United States
has a stormwater pollution problem, whether served by a
combined sewer or a separate system. This study provides
selected results of a comprehensive investigation and assess-
ment of promising methods of treating or controlling such
pollution.
A. W. Breidenbach, Ph.D.
Director
National Environmental
Research Center, Cincinnati
111
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ABSTRACT
Control and/or treatment of stormwater discharges and combined sewage
overflows from urban areas are problems of increasing importance in
the field of water quality management. Over the past decade much re-
search effort has been expended and a large amount of data has been
generated, primarily through the actions and support of the U. S.
Environmental Protection Agency's (EPA) Storm and Combined Sewer Re-
search and Development Program. Presented in this text are selected
results of a comprehensive investigation and assessment of promising,
completed and ongoing projects, representative of the state-of-the-art
in abatement theory and technology; a look at recent legislation; and
the identification of program needs and emphasis.
Combined sewer overflows are major sources of water pollution problems,
but even discharges of stormwater alone can seriously affect water
quality. Current approaches involve control of overflows, treatment
and combinations of the two. Control may involve maximizing treatment
with existing facilities, control of infiltration and extraneous inflows,
surface sanitation and management, as well as flow regulation and storage,
A number of treatment methods have been evaluated including high rate
screening and microstraining, ultra high rate filtration, dissolved air
flotation, physical/chemical treatment, and modified biological processes.
A swirl flow regulator/solids separator of anular shape construction
with no moving parts has been developed. High rate disinfection
methods including new disinfectants have been applied.
Promising approaches involve integrated use of controls and treatment.
The most disappointing have generally lacked flexibility in their oper-
ation and design. Mathematical models have been developed and success-
fully applied at multiple levels of sophistication and complexity.
IV
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CONTENTS
No. Page
Review Notice ii
Foreword iii
Abstract iv
List of Figures vi
List of Tables vii
Acknowledgements viii
Sections
I Conclusions 1
II Recommendations 2
III Introduction - Problem Definition 3
IV Design Constraints 5
V Management Alternatives 6
VI Results and Costs 10
VII Impact of Legislation 15
VIII R&D Needs and EPA Program Emphasis 18
IX References 28
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FIGURES
No. Page
1 Representative Strengths of Wastewaters 4
2 Storage - Treatment Example 14
3 Overview of Storm Water Management Model Structure 19
4 Isometric View of Swirl Regulator/Concentrator 25
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TABLES
No. Page
1 Summary of Storage Costs for Various Cities 11
2 Comparison of Treatment Alternatives 12
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ACKNOWLEDGEMENTS
The work upon which this publication is based was performed in part by
Metcalf & Eddy, Inc. under the direction and guidance of the EPA's
Storm and Combined Sewer Technology Program pursuant to Contract No.
68-03-0179 with the EPA. The full text was published by EPA under the
title "Urban Stormwater Management and Technology: An Assessment,"
EPA-670/2-74-040.
The authors express appreciation to Ms. Pamela J. Szeeley, Staff
Assistant, Storm & Combined Sewer Section, Advanced Waste Treatment
Research Laboratory, National Environmental Research Center-Cinn.,
Edison, New Jersey, for her cooperation and assistance in editing.
viii
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SECTION I
CONCLUSIONS
All facts point to a real requirement for treating and controlling
stormwater runoff and combined sewer overflows. The multi-billion
dollar treatment plant upgrading and expansion program now going on
throughout the country will do much to alleviate pollution of our
waters. However, means of mitigating the effects of urban runoff
must also be found if we hope to abate the pollution in an optimal
manner. Wet-weather standards are already being instituted by EPA
and some states and localities. Recognizing this, EPA's Storm and
Combined Sewer Technology Program will strive to be a prime support
for this real-world application.
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SECTION II
RECOMMENDATIONS
Before truly effective countermeasures (control or treatment) can be
applied to the urban runoff/combined sewer overflow problem a nation-
wide characterization and evaluation of its impact is needed. New
methods for the determination of pathogenic pollution are required
in addition to a reevaluation of disinfection requirements. Methods
of controlling and treating heavy metals and organics found in runoff
must be developed. Detention, both in-line and upstream, needs
further development to optimize its effectiveness as a pollution
abatement procedure. Improvement of rainfall-runoff models, flow
meters, and stormwater reuse concepts would ease the stormflow control
problem.
The above-mentioned technology is crucial to abating wet-weather
pollution, but equally important is its dissemination and proper use.
The various approaches must be evaluated absolutely and compared
with each other to determine their cost and actual effectiveness
in situ. Coverage of these principles and methods in the appropriate
schools would distribute the information to those persons who are
most in the position to apply it.
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SECTION III
INTRODUCTION - PROBLEM DEFINITION
Simply stated the problem is:
When a city takes a bath, what do you do with the dirty water?
Three types of discharge are involved: combined sewer overflows, storm
drainage in separate systems, and overflows (bypasses) from infiltrated
sanitary sewers. Significantly the storm path and collection system
configuration may have a pronounced influence on combined overflow
quality, resulting in simultaneous discharge mixtures of sewage and
runoff at different points varying from raw to highly diluted as the
system adjusts to a particular storm pattern [1]. The problem con-
stituents of general concern are visible matter, infectious bacteria,
organics, and solids and in addition may include nutrients, heavy
metals and pesticides. Representative comparisons are shown in
Figure 1.
Organic loadings in overflows and wet^weather bypasses, while gener-
ally averaging (flow weighted means) less than one-half the strength
of untreated sanitary sewage, must be considered in terms of their
shockloading effect because of their great magnitude. For example,
rates of urban runoff from an average storm intensity of 0.10 in./hr
(0.25 cm/hr) may be expected to be on the order of 5 to 10 times the
dry weather flow contribution from the same area. Likewise, a not
uncommon rainfall intensity of 1.0 in./hr (2.5 cm/hr) will produce
flow rates of 50 to 100 times the dry weather flow.
Even separate storm wastewaters are significant sources of pollution,
"typically" characterized as having (1) solids concentrations equal
to or greater than those of untreated sanitary wastewater, and (2)
BOD5 concentrations approximately equal to those of secondary
effluent. Bacterial contamination of separate storm wastewaters is
typically 2 to 4 orders of magnitude less than that of untreated
sanitary wastewaters. Significantly, however, it is 2 to 4 orders
of magnitude greater than concentrations considered safe for water
contact "activities.
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200
200
RAW
COMBINED
| | STORM
6-7
BOD
SS
DO
5xl07
RAW
COMBINED
I ] STORM
10
TOTAL COLIFORM
MPN/100 ml
TOTAL
NITROGEN
TOTAL
PHOSPHORUS
FIGURE 1. Representative Strengths of Wastewaters
(flow weighted means expressed in mg/L)
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SECTION IV
DESIGN CONSTRAINTS
Precise characterization of the wastewater is virtually impossible be-
cause of the variability in the character of storm and/or combined
wastewater and because of the many physical difficulties in represen-
tative sample collection. Also, because of the intermittency and
variability of stormwater runoff and interrelated system flows, there
is no such thing as an "average" design condition for stormwater treat-
ment facilities. Therefore, a unit or process that performs only when
conditions are right may be too restrictive for practical applications.
In addition, the magnitude, debris content, and brute force of storm
flows may be major constraints limiting options for centralization
(because of high transmission costs) and rendering sophisticated and
complex equipment ineffectual or impossible to maintain.
Finally, in assessing the performance of past projects, the project
scale, pretreatment controls, and location with respect to mainten-
ance and supervisory services are critical factors with respect to
credibility, applicability, and reliability. Likewise it should be
recognized that the sparsity and individuality of real installations
make generalizations difficult and hazardous.
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SECTION V
MANAGEMENT ALTEENATIVES
What then can be done about the problem? First there is a choice as
to where to attack the problem. This may be at the source (e.g. the
streets, gutters, and catchment areas), within the collection system,
at the terminus or strategic intermediate locations of the system, or
combinations of the above including the integrated use of the dry-
weather treatment facilities. Second, there is the choice of how much
control and/or degree of treatment to introduce. This generates into
a cost-effective analysis involving goals, values, and hydrologic-
physical system evaluations (generally assisted by mathematical model
simulations, pilot-scale trials, and new technology transfer). Thirdly,
there is the impact assessment, public exposure, and priority ranking
with other needs.
SOURCE CONTROLS
Examples of source controls include flow attenuation, erosion control,
restrictions on chemical use (de-icing compounds, pesticides), and
improved neighborhood sanitation practices. The theory behind source
controls is to limit the supply of contaminants. The benefits are not
only reduced water pollution but also cleaner and healthier environments,
This point was emphasized in one study [2] which noted:
Initially, one must consider the temporal condition of the
watershed. The general sanitary conditions of the indivi-
dual parcels influence the environment of the entire drainage
basin. Some of the parcel indicators are the housing or
establishment condition, the number of uncovered garbage
cans, piles of rubbish and rubble, autos and animals main-
tained, the presence of privies, and the amount of litter
in the streets which bound the parcel.
The most sensitive parameter to normal environmental cleanliness, as
might be expected, was bacterial contamination with a range approxi-
mately two orders of magnitude computed. Construction activity, vacant
land, and extent of open channel flow greatly influenced total solids
in the runoff.
COLLECTION SYSTEM CONTROLS
Examples of collection system controls include flushing, polymer feed,
inflow/infiltration control, improved regulator devices, sewer separa-
tion, and remote monitoring/control systems. The emphasis, with the
exception of sewer separation, is upon optimal utilization of the
existing facilities. To accomplish this an extensive and dependable
intelligence system is necessary.
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Solids deposition in lines have been a plague to effective mainten-
ance of service since the inception of piped conduits. Considering
the significance of such loads (resultant first flush phenomena)
surprisingly little research has entered this area, at least until
recently [3,4]. Improved regulator devices such as the swirl con-
centrator [5,18,22] offer the potential for effective solids separation
over wide ranges of flow but the ultimate disposal of these solids
will be a major problem. Reclamation through some form of decontam-
ination-classification followed by land filling appears to be a
logical solution.
System controls utilizing in-line storage represent promising alter-
natives in combined or partially combined systems in areas where
conduits are large and flat (i.e., backwater impoundments become
feasible) and interceptor capacity is high. The intent is to assist
a dispatcher (supervisor) in routing and storing stormwater flows to
make the most effective use of interceptor and line capacities. The
necessary components include both sensing (e.g. flow levels, rates,
quality, gate positions, and rainfall) and control devices (e.g. gates,
valves, inflatable dams, regulators, and pumps) operable from a
central facility. As the components become more advanced and oper-
ating experience grows, system control offers the key to total in-
tegrated system management and optimization.
The concept of constructing new sanitary sewers to replace existing
combined sewers largely has been abandoned because of the enormous
cost, limited effectiveness, inconvenience to the public, and ex-
tended time required for implementation.
STORAGE AND TREATMENT
Storage
Storage facilities possess many of the favorable attributes desired in
stormwater treatment: (1) they are capable of providing flow equali-
zation or attenuation and, in the case of tunnels, flow transmission;
(2) they are simple to design and operate; (3) they respond without
difficulty to intermittent and random storm behavior; (4) they are
relatively unaffected by flow and quality changes; and (5) frequently
they can be operated in concert with regional dry weather flow treat-
ment plants for benefits during both dry and wet-weather conditions.
Disadvantages of storage facilities include their large size, high
cost, and dependency on other treatment facilities for dewatering and
solids disposal.
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Physical Treatment
Physical treatment processes in many ways are well suited to storm-
water applications, particularly with respect to solids removal.
These processes include sedimentation, dissolved air flotation,
screening filtration, and special regulator devices. Handicaps
appear to be sensitivities to flows and loadings (although they may
be the most tolerant of the treatment alternatives), high mainten-
ance requirements, and absence of effective utilization in the be-
tween storm periods.
To reduce capital investments, demonstration projects have been
directed towards operations approaching the maximum loading bound-
aries. Applications include their use for pretreatment or roughing,
for the main or sole treatment, and particularly in the case of
microstrainers and filters, as effluent polishing devices.
Biological Treatment
Biological treatment of storm wastewaters must overcome some serious
drawbacks: (1) the biomass used to assimilate the waste constituents
must either be kept alive during times of dry weather or allowed to
develop for each storm event; and (2) once developed, the biomass is
highly susceptible to washout by hydraulic surges or overload.
Examples of biological treatment applications to,stormwater include
(1) the contact stabilization modification of activated sludge,
(2) high rate trickling filtration, (3) bioadsorption using rotating
biological contactors, and (4) oxidation lagoons of various types.
The first three are operated conjunctively with dry weather flow
plants to supply the biomass and the fourth involves long term storage
of the flows. With the exception of lagoons, some form of pre-unit
flow equalization and control is essential.
Physical-Chemical Treatment
Physical-chemical processes are of particular importance to stormwater
treatment because of their adaptability to automated operation, rapid
startup and shutdown characteristics, and very good resistance to
shock-loads. Most practical applications, necessarily, will stop far
short of the tertiary levels now piloted or in service on sanitary
wastewaters. However some projects through repetitive treatment use
in non-storm periods may achieve a high degree of beneficial reclama-
tion [6]. Drawbacks to physical-chemical treatment include high
initial costs (may be largely offset by reduced land requirements),
high chemical requirements, and increased sludge (by dry weight) to
be disposed of.
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One full-scale plant application on combined sewage has an attractive
innovation: the use of waste lime sludge from a nearby water treat-
ment plant as a clarifying aid, is to be tested [7].
Disinfection
The most commonly used disinfectants under the research program are
chlorine, sodium or calcium hypochlorite, chlorine dioxide, and ozone.
Because the disinfectant and contact demands are great in stormwater
applications, current research centers on (1) high rate applications,
(2) use of alternative disinfectants, and (3) on-site generation of
disinfectants. From the standpoint of safety in storage and transport
the use of hypochlorites predominates in current full scale applica-
tions .
INTEGRATED (COMPLEX SYSTEMS)
By far the most promising approaches to urban stormwater management
involve the integrated use of control and treatment with an areawide,
multidisciplinary perspective. Mathematical models have been developed
and successfully applied at many levels of sophistication and com-
plexity. These models vary from simple "mass-diagram" balances of
runoff, storage, treatment, and overflows to those capable of represent-
ing the whole gamut of urban stormwater runoff phenomena (including
both quantity and quality).
Integrated approaches are notably demonstrated in programs underway
in Chicago, San Francisco, Seattle, Washington, D.C., Rochester, and
elsewhere.
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SECTION VI
RESULTS AND COSTS
As representative of one facet of source controls, a recent study [8]
concluded:
Current street cleaning practices are essentially for
aesthetic purposes and even under well-operated and
highly efficient street sweeping programs, their effi-
ciency in the removal of the dust and dirt fraction
of street surface contaminants is low.
The removal efficiency of the dust and dirt fraction (contributing
most heavily to water pollution effects) averaged 50 percent whereas
the pickup of litter and debris ranged from 95 to 100 percent. Im-
provements to 70 percent removals and possibly as high as 90 percent
were considered feasible under the best conditions. Costs were in-
dicated in a range from $2.18 to $8.42 per curb mile ($1.35 to $5.23
per curb Km) swept.
Detroit (4) found the cost of in-system controlled storage to be as
low as $0.02 to $0.04 per gallon ($0.005 to $0.01 per liter) of
storage based upon the most favorable sites. This range was approxi-
mately 1/10 the estimated cost for large off-line facilities. Re-
presentative storage costs from other projects adjusted to ENR 2000
are summarized in Table 1. Removals by sedimentation may be estimated
by conventional criteria.
A hypothetical comparison of alternate treatment processes based upon
an assumed 25 mgd (1.095 cu m/sec) installation is summarized in
Table 2. Since the feed to the units varies continuously in both
quantity and quality (storms do not repeat themselves), the effi-
ciencies should be regarded as gross indicators only. Similarly the
cost estimates are based upon one or at most only a few installations
and may not be fully equitable in terms of completeness of facilities
and difficulties encountered in construction.
A simplified example will serve to illustrate an advantage of inter-
grated (complex) approaches. Assume a design composite storm over-
flow for a combined catchment area is three hours long and the hydro-
graph is triangular shaped with a maximum value of 25 mgd (1.095 cu
m/sec) occurring at the end of the first hour. Total containment in
storage would therefore require a capacity of 1.56 million gallons
(5.90 Ml) which at a unit cost of $.50 per gallon ($.13 per liter)
would cost $780,000 to construct. Similarly a treatment facility
designed for the maximum flow rate might cost (25 mgd x $30,000/mgd)
$750,000. A 10 mgd (0.44 cu m/sec plant, however, coupled with a
10
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Table 1. SUMMARY OF STORAGE COSTS FOR VARIOUS CITIES
a
Location
Seattle, Wash.
Control and monitoring
system
Automated regulator
station
Minneapolis-St.Paul, Minn.
Chippewa Falls, Wis.
Storage
Treatment
Jamaica Bay, N.Y. , N.Y.
Basin
Basin and sewer
Humbolt Ave . .Milwaukee , Wis .
Boston, Massachusetts
Cottage Farm Stormwater
Treatment Station
Chicago, Illinois
Storage basins
Collecting, tunnel and
pumping0
Storage
mil. gal.
32.0
—
2.8
10.0
23.0
4.0
1.3
2,736.0
2,834.0
5,570.0
Capital cost
$
3,500,000
3,900,000
7,400,000
3,000,000
744,000
186,000
21,200,000
21,200,000
2,010,000
6,200,000
568,000,000
755,000,000
1,323,000,000
Storage
cost
$/gal.
0.23
—
0.26
2.12
0.92
0.50
4.74b
0.21
0.27
0.24
a ENR = 2000.
b Includes pumping station, chlorination facilities, and outfall.
c Includes 193.1 km (120 miles) of tunnels.
NOTE: $/acre x 2.47 = $/hectare, $/gal. x 0.264
= $/liter, mil gal. x 3.785 = Ml
11
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Table 2. COMPARISON OF TREATMENT ALTERNATIVES
Process
Dissolved air flota-
tionb (split flow)
Same w/chemt add'n
Microstrainer
Ultrafine screen
Ultrahigh rate
filtration
Chemical clarifi-
cation using waste
lime sludge
Contact stabilization
modification of
secondary plant
High rate trickling
filter modification
of secondary plant
Design Loading
Rate
3,200 gpd/sq ft
25 mg/L
25 gpm/sq ft
24 gpm/sq ft
2,570 gpd/sq ft
108 Ib BODS/
1,000 cf
Plastic media-
40 mgad; Rock
media- 12 mgad
Estimated
removals
or range, %
BOD5
40
52
10-50
15
8-36
60
83
65
SS
60
78
70
40
38-73
60
92
65
Capital Cost
per mgda
$35,000
—
13,000
7,800
63,000C
54 ,000
78,300
68,000
a Based on 25 mgd facility.
b Includes ultrafine screens as pretreatment.
c Extrapolated from bench scale data.
NOTE: gpd/sq ft x 0.283 = cu m/min/ha
gpm/sq ft x 0.679 = 1 sec/sq m
lb/1,000 cf x 16.077 = g/cu m
mgad x 9.357 = ml/day/ha
mgd x 0.0438 = cu m/sec
12
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storage capability of .56 million gallons (2.12 Ml), would accomplish
the same objectives for $580,000 (see Figure 2). Of particular im-
portance is the opportunity for the treatment plant to operate at its
design capacity for a sustained period of time.
While prototype installations in operation today are still relatively
few in number some impressive results have been obtained. The in-
system storage concepts have proven feasible to operate and maintain
with a major curtailment of overflow occurances and durations. Off-
line storage and detention-chlorination facilities are proven performers
with additional benefits for backing up overloaded treatment works
innovated. Stormwater facilities constructed in parallel with conven-
tional dry weather flow treatment plants have introduced dual use
functions improving even dry weather performance as well as increasing
treatment capacities during storm periods. Direct treatment systems
have been slower in coming into use and, in more than a few cases,
have been adversely affected by the fickleness of storm misbehavior.
In the authors' opinion, two important points are to be made:
1. Some form of storage (flow equalization) must be considered
in any stormwater treatment installation; and
2. Municipal stormwater pollution abatement programs must be
scaled and implemented giving full recognition to the
limitations in available data and the relative immaturity
of the state-of-the-art.
13
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Q
o
5
5
o
>
o
25-i
o
s
o
«l
u.
a;
UJ
>
O
25-1
20-
TOTAL STORAGE
1.56 mg x $ 0.50/gal
= $ 780,000
TOTAL TREATMENT
25 MGD x $ 30,000 /MOD
= $ 750,000
TIME, MRS
(a) Separate Approach
NET STORAGE
0.56 mg x $ 0.50/gal
TREATMENT
10 MGD x $ 30,000/MGD = $ 300,000
TOTAL $ 580,000
= $ 280,000
4.0
(b) Integrated Approach
FIGURE 2. Storage-Treatment Example
14
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SECTION VII
IMPACT OF LEGISLATION
The urban runoff problem has received recognition from the Federal
government. Since 1965, various acts of legislation have supported
the thrust in developing countermeasures against the environmental
impacts of urban runoff.
Enough light was borne on the stormwater problem in the early 1960's
by the U.S. Environmental Protection Agency's (EPA) predecessor, the
U.S. Public Health Service, to create recognition from our legislators.
The Federal Water Pollution Control Act (FWPCA) was amended by the
Water Quality Act of 1965 (PL 89-234) and the Clean Water Restoration
Act of 1966 (PL 89-753) to authorize funds for the development of new
and improved methods for controlling pollution caused by combined
sewer overflows or stormwater discharges. The 1965 Act created a
viable Federal involvement in research, development, and demonstration.
Today this EPA program is under the jurisdiction of the Storm & Com-
bined Sewer Section of the National Environmental Research Center-
Cincinnati.
The initial Acts authorized funds for demonstration grants for new
and improved methods for controlling storm generated pollution to states,
municipalities, intermunicipal, or interstate agencies in amounts of up
to 75 percent of the estimated project costs. Contracts were also made
available to private enterprise for the implementation of worthwhile
projects. The more recent FWPCA Amendments of 1972 (PL 92-500) pro-
vided continued support of these extramural activities (Sec. 105.
(a) (1)).
1972 FWPCA AMENDMENTS PLACE NEW EMPHASIS ON STORMWATER
The 1972 Amendments place new and stronger emphasis on urban runoff as
a source of pollution. "An accelerated effort..." is stressed "...to
develop, refine, and achieve practical application of waste management
methods applicable to nonpoint sources of pollutants to eliminate the
discharge of pollutants including, but not limited to, elimination of
runoff of pollutants...." (Sec. 105. (d)(l)).
"In recognition of the serious conditions which exist in Lake Erie..."
the Amendments authorize development of "...a demonstration wastewater
management program for the rehabilitation and environmental repair of
Lake Erie." It is further stipulated that "such a program include
measures to control....area sources of pollution, including....urban
runoff and rural runoff...." (Sec. 108.(d)(l) & (2)).
15
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Research and investigation for reducing total sewage flow has been
stimulated by the FWPCA Amendments (Sec. 104.(o)CD) "...in order to
reduce the requirements for, and the costs of, sewage and waste treat-
ment services." A significant way to reduce sewer flows would be to
reduce infiltration and other extraneous stormwater inflows. EPA's
Research and Development program has joined hands with their Office
of Air and Water Programs to make the required reports to Congress
(Sec. 104.(o)(2)) on methods of reducing the total flow of sewage.
Grants for the construction of treatment works will not be approved
as of July 1, 1973, "...unless the applicant shows.... that each sewer
collection system discharging into such treatment works is not subject
to excessive infiltration" (Sec. 201.(g)(3)). Authority was given to
make grants for the sewer system evaluation studies necessary to carry
out this requirement (Sec. 201.(g)(4)). Furthermore, the Office of
Research and Development, by these Sections of the Act received impetus
to continue their research and development against infiltration and
inflows.
Construction grant applications and area wide or basin wastewater
treatment management plans are being encouraged to include "...the
necessary waste water collection and urban storm water runoff systems.."
for the control and treatment of storm generated pollution (Sec. 208.
(b)(2)(A) & 212. (2) (B)).
COMPTROLLER GENERAL'S REPORT - MARCH 28, 1973
Because of the seriousness of the combined sewer overflow problem, the
Comptroller General of the United States, on March 28, 1973, submitted
a report to Congress on the "Need to Control Discharges from Sewers
Carrying Both Sewage and Storm Runoff." Findings revealed that com-
bined sewer overflows "...are a major pollution problem and prevent
many areas from attaining Federal and State water quality goals." The
report recommended that the EPA require states to identify, study, and
.submit abatement plans for combined sewer overflow pollution and to
consider the award of construction grants for these abatement faci-
lities.
Treatment standards mandated by the new Amendments call for secondary
treatment by July 1, 1977; best practicable treatment by July 1, 1983;
and non-polluting discharge by 1985. Water quality objectives may remain
beyond reach so long as attention is not given to the treatment and
control of stormwater runoff and combined sewer overflows.
16
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STATE AND LOCAL REQUIREMENTS
On the state and local level, regulations concerning water pollution
abatement have been tightened. Illinois [9, 10, 11] and Georgia [12]
have promulgated their requirements for overflow control and treatment.
In an effort to curb channel erosion and downstream siltation, the
State of Maryland [13, 14, 15] requires the land developer to attenuate
runoff so as not to allow flow releases (for up to two year storms) to
occur any faster than before site construction.
The City and County of San Francisco, California, has passed a 1970
resolution [16] for a special time schedule to regulate discharges
from combined sewers. A recent regulation in Orange County, Florida [17]
states that a complete stormwater management system be provided to
handle all stormwater runoff in "prime recharge areas." It also states
that treatment is required for stormwater in all drainage systems.
This regulation is the first to deal so specifically with the control
and treatment of urban runoff as opposed to combined storm and sanitary
flows.
17
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SECTION VIII
RESEARCH & DEVELOPMENT NEEDS AND EPA PROGRAM EMPHASIS
Looking ahead, the Storm and Combined Sewer Pollution Control Program
needs are vast and numerous. Some of the newer approaches being em-
phasized by the program are discussed below.
CHARACTERIZATION AND EVALUATION
Simulation Models
The capability to analyze various component flows and pollution loads
throughout a sewerage system are the keys to better design of control
and treatment systems. Due to complexities of the rainfall-runoff-flow
phenomena, past analyses have been less than adequate, resulting in
poor estimates of flow and predicted system responses to a storm. EPA
now has available a "descriptive" Storm Water Management Model (SWMM)
which can overcome former analytical deficiencies. Figure 3 depicts
a schematic overview of the model structure. The Program is in the
initial phase of demonstrating the application of this method for
"decision-making," that is, its ability to analyze a major combined
sewer system; to select and to design control and treatment approaches
based on cost—effectiveness; and to eventually design a computerized
means of overall management of the system during storm flows.
EPA is presently seeking a municipal location where a development and
operational demonstration can be made of totally automated "real-time"
or feed-forward" control of a sewerage system during storm flow condi-
tions. This system would be based on in-line routing and storage in a
sewer network for control and subsequent treatment.
Simplified models requiring simple inputs need to be developed for
early stage planning. Extensions to the SWMM will enable total basin
planning by interfacing it with dry weather municipal flow and benefi-
cial potable and sub-potable water supply and resource features. The
eventual goal is to demonstrate a "total urban intelligence system,"
whereby a regional system which employs runoff impoundment and recharge
for aesthetic, recreational, and supply purposes; and integrated wet
and dry weather wastewater routing and treatment could be planned,
designed, and operated real-time by a mathematical Urban Water Resource
Management Model.
18
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RUNOFF
(RUNOFF)
INFILTRATION
(INFIL)
DECAY
(OUAL)
DRY WEATHER
FLOW
(FILTH)
TRANSPORT
(TRANS)
INTERNAL
STORAGE
(TSTRDT)
EXTERNAL
STORAGE
(STORAG)
RECEIVING WATER
(RECEIV)
Note: Subroutine names are shown in parentheses.
FIGURE 3. Overview of SWMM Model Structure
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Nationwide Assessment of Urban Runoff Impacts
A project has been sponsored by EPA to characterize, evaluate the
impacts, and determine costs for the control of urban stormwater
runoff (not combined sewage) pollution on a nationwide basis—a
consideration which has been stressed by the 1972 Amendments to the
FWPC Act, and which is needed to set enforcement guides and appro-
priate financial backing. Such information would be extremely useful
in planning and implementing the best available and most cost-effec-
tive means of control and treatment of urban stormwater discharges.
Combined Sewage Sludge
Due to priorities of the problem at hand, the sludge handling aspects
of combined sewer overflow treatment processes have just now been given
due consideration and investigation. A recently authorized effort will
characterize sludges and solids resulting from overflow treatment and
make recommendations for the most appropriate systems for their hand-
ling and disposal. Recommendations will consider on-site disposal at
the wet weather plant and pump back to the municipal treatment works;
and will result in a handy reference for designers of future complete
combined sewer overflow treatment and control systems.
Uniform Procedures For Analysis And Evaluation of Storm Flow Charac-
teristics And Treatability
Since the quantitative and qualitative nature of the wet weather flow
problem is such that the application of conventional dry weather flow
field procedures and analytical determinations are not adequate for
stormwater and combined sewage characterization and treatability
evaluations, a set of standardized procedures specific to this problem
is being formulated under EPA contract. Such a set of procedures would
not only help in the deduction, comparison and statistical interpreta-
tion of data collected to date, but also in formulating evaluations of
future projects. In this way, data comparison and performance evalua-
tions will be more meaningful and more adaptable to planning and design.
Flow Measurement
The quantitative and qualitative measurement of storm overflows is
essential for process design, control, evaluation, and enforcement.
"Urban intelligence systems" require real-time data from rapid, remote
sensors in order to achieve remote control of a sewerage network.
Sampling devices do not provide representative aliquots; and in-line
measurement of suspended solids and organics is needed. Conventional
rate-of-flow meters have been developed mainly for relatively steady-
state irrigational, streams, and sanitary flows and not for the highly
varying surges encountered in storm and combined sewers. In these
sewers, a measuring device may be subjected to very low flow rates,
submergence, reverse flow and surcharge, all during a single rainstorm.
These severe flow conditions rule out the reliable and accurate appli-
cation of conventional devices, such as weirs and flumes, at many
20
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locations. Consequently, the Storm and Combined Sewer Technology pro-
gram is deeply involved in the development and demonstration of sophis-
ticated and new flow-measuring equipment. Two efforts are being initi-
ated to develop reliable obstructionless means of measuring both gravity
and pressurized flow at one gaging point utilizing the principles of
electromagnetics and passive sound, respectively. Passive sound instru-
ments offer the additional benefit of an extremely low power require-
ment; thus rendering them amenable to installation at remote overflow
locations (where power may not exist) and for integration into citywide,
in-sewer, sensing and control systems.
The program has contributed to the development of a prototype monitor
capable of instantaneous, in situ measurement of suspended solids based
on the optical principle of suspended solids depolarizing polarized
light. This device is now being demonstrated. Two other projects are
in the process of developing a sampler that will gather flow representa-
tive samples [20] , and an automatic, rapid, on-line monitoring device
for concentrations of organics, respectively.
Consideration of Trace Pollutants
Characterization studies revealed a significant amount of trace pollu-
tants in the runoff which included heavy metals (lead, zinc, cadmium,
mercury, copper, chromium) pesticides and PCB's, nutrients, chemical
deicers, and non-biodegradable and refractory organics. Street cleaning
and chemical use limitations are ways to reduce these pollutants, but
specific stormwater treatment methods are also needed.
Pathogen Detection
High coliform counts in surface runoff or combined 'sewage could lead to
unnecessary stormwater disinfection requirements and overdesigned faci-
lities. Parameters for pathogenic contamination have been taken almost
blindly from municipal pollution control practice and applied to storm-
water and combined sewer flows when in fact, high concentrations of
fecal and total coliform can come entirely from animal and soil sources.
EPA is attempting to define more realistic methods to determine patho-
genic pollution (either directly or indirectly) and associated disinfec-
tion requirements.
CONTROL METHODOLOGY
New Sewer Design
A demonstration is being sought for the development of a master plan for
a community-wide sewer collection system based on an advanced method.
Basically the new method is the old combined sewer concept which incor-
porates in-line storage for wet-weather flow along with flow conveyance.
The method will include up-to-date hydrologic and hydraulic theory
which employs the complete momentum equation for unsteady storm
flow and adequate low-flow velocities to prevent solids buildup.
21
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Comparisons will be made with conventional combined and separate sewer
designs which do not consider in-line control and employ older concepts
such as the Rational Method and the Kutter or Manning equations. These
methods have been the subject of much criticism. Comparisons will be
based on cost-effectiveness for stormwater pollution control and an
analysis of collection system inadequacies arising from inexact concepts.
A task is being implemented to develop a combined sewer design for
adequate carrying velocity at low flow dry-weather conditions to avoid
the first flush phenomena. Present design criteria is based on carrying
velocities (2 to 3 fps) occurring at maximum, one half, or full-pipe flow
rates. This stems from the antiquated philosophy: less pumping means
optimum design (with dependence on periodic storm flows for the higher
flow rates to maintain the sewers by flushing deposited solids). The
philosophy of employing low velocities during dry-weather and high during
wet-weather has backfired. Today we recognize that combined sewer purging
by storm flow creates our overflow first flush pollution. Combinations
of steeper sewer slopes and different sewer cross sectional shapes (with
less cross sectional area at the bottom) are ways to maintain adequate
solids carrying velocities at all flow rates. For a correct economic
evaluation added costs for sewer and pumping station installation and
power should be compared to capital and operational costs for conveyance,
storage, and treatment of the first flush which would otherwise result.
Upstream Impoundment
Upstream storage or other control processes to decrease the stormwater
runoff effect on lower portions of the system require further develop-
ment and demonstration. Aside from the main objective of controlling
stormwater pollution (while offering greater flexibility for control
and treatment), upstream control can: (1) preclude the need for addi-
tional sewer line capacity and associated construction requirements;
(2) alleviate shock loadings due to storm flow scouring velocities;
(3) relieve the often occurring expense of constructing facilities
downstream near watercourses in unstable soil with high water table.
Examples are the temporary storage or attenuation of stormwater at the
building or immediate area through the use of holding tanks; seepage
pits, possibly for recharge; roof tops; parks, playground, greenbelts
and other open spates; backyard detention facilities; porous pavement;
or neighborhood, decentralized stormwater collection sumps including
storage facilities under streets. Upstream control systems should
automatically regulate discharge from storage to the groundwater, a
watercourse, or sewer system. Plans for reuse of stored water for irri-
gation, street cleaning, sewer flushing, aesthetic and recreational
ponds, potable and sub-potable supply, and other purposes are also
encouraged.
Catch Basins — Good or Bad?
The so-called control practice being studied by EPA's program is the
conventional employment of catch basins. Despite the purported reduced
need for catch basins, they are still used regularly. For the most
part, the various catch basin configurations are inefficient for their
22
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intended purpose — solids removal. Answers will be sought to such
questions as:
1. What is their actual need as used today?
2. Can new types be developed, or existing ones be improved by
recommending cost-effective cleaning procedures and schedules
or other physical alterations?
Runoff Attenuation By Porous Pavement
A method for attenuating flows that has exhibited pilot-scale feasi-
bility [19] is the installation of porous pavement. If used for high-
ways, streets, and parking lots, it would have the potential for reduc-
ing capacities and associated costs for both sewer and wet-weather flow
treatment systems and groundwater recharge, features attributable to
the porous pavement's ability to equalize flows entering or divert
flows away from the sewerage system. Even more important are the safety
features which could be realized, that is, an increased coefficient of
friction to prevent wet skidding or hydroplaning accidents, and en-
hanced visibility of pavement markings due to more rapid removal of
rainwater and rougher surfaces. A full-sieed demonstration project
has been initiated in the Woodlands — a new town community near Houston,
Texas — to demonstrate the benefits of porous pavement. In addition,
the efficiency of street vacuum cleaning to reduce pollution load from
streets will be demonstrated.
Dual Use Facilities
Wet-weather overflow control and treatment facilities built in con-
junction with new or existing sewerage works is emphasized as a first
consideration.
Surge facilities (or existing combined sewers) at the municipal plant
could serve a dual function in equalizing not only wet-weather flows
but dry-weather flows as well. In this way, a single future treatment
system can readily be designed for storm and sanitary flow conditions.
This could also assist presently overloaded sanitary plants in obtain-
ing more uniform operation. Short-term storage would even out the
daily cycle of dry-weather flows, allowing more efficient use of the
treatment process over the entire 24 hours. Equalization also permits
reduced treatment process design capacity.
Wet-weather treatment systems integrated with the sanitary plant can
demonstrate their synergistic benefit by being utilized to take over
during repairs, polishing secondary effluents, or increasing dry-
weather treatment capacity during the vast majority of the time, when
it is not raining.
23
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At present, officials are considering the award of demonstration grants
to state and local governments for the evaluation of physical-chemical
processes applying the dual treatment concept, such as screening
coupled with deep-bed, dual-media, ultra-high-rate filtration; and
activated carbon adsorption. Both treatment schemes would be aided by
chemical additions.
Swirl and Helical Separators
The EPA program has refined and is demonstrating the swirl flow reeu-
lator/solids-liquid separator [5,18,22]. The device, of simple annular
shape construction, requires no moving parts. It provides a dual
function, regulating flow by a central circular weir while simulta-
neously treating combined wastewater by a "swirl" action which imparts
liquid-solids separation. The low-flow concentrate is diverted via a
bottom orifice to the sanitary sewerage system for subsequent treat-
ment at the municipal works, and the relatively clear liquid overflows
the weir into a central downshaft and receives further treatment or is
discharged to the stream. Figure 4 shows an isometric view of the
swirl regulator/concentrator. The device is capable of functioning
efficiently over a wide range of combined sewer overflow rates, and
can effectively separate suspended matter at a small fraction of the
detention time required for conventional sedimentation or flotation.
For these reasons, projects are underway to perfect swirl units to
take the place of grit chambers [23] and primary sedimentation units.
Development is proceeding on a helical or spiral-type regulator/sepa-
rator based on principles similar to those of the swirl device. This
device is beneficial as its solids separation action is created by
only a bend in the sewer line.
Comparisons of Screening Devices
Screening is adaptable to the intermittent and variable hydraulic and
solids characteristics of storm caused flows, and accordingly fine mesh
screening devices and microstrainers have been developed for the program.
To enhance previous work and allow better selection and design in the
future, EPA has awarded two grants to Fort Wayne, Indiana, and to Onon-
daga County (Syracuse), New York. Multiple screening options are being
tested at these locations to directly gain this needed comparative data.
Hydrologic-Hydraulic Design Rationale
Urban hydrology is a field which is almost devoid of modern research
investment. As a consequence, too little is known about the rainfall-
runoff process and still less about rainfall-runoff quality, particu-
larly for sewered catchments. More research is needed to develop a
more complete understanding of the entire urban runoff pollution
problem.
24
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FOUL SEWER
OVERFLOW
LEGEND
a Inlet Ramp
b Flow Deflector
e Scum Ring
d Overflow Weir and Weir Plate
e Spoilers
f Floatables Trap
g Foul Sewer Outlet
h Floor Gutters
FIGURE 4. Isometric View of Swirl
Regulator/Concentrator
25
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A project was implemented to study the methods currently in use to de-
scribe and predict rainfall intensity duration relationships as they
relate to storm and combined sewer flow, and to non-sewered urban run-
off. This study will evaluate the relative merits of particularly
those which involve empiricisms and statistics or rainfall prediction
based on limited historical data. A document will be developed to aid
engineers and planners in assessment, design, and control. The aim
will be to provide recommended methods for determining cumulative
runoff volumes and flow rates for design and operation of combined
sewer overflow and stormwater runoff control and treatment facilities.
Beneficial Use of Stormwater
A previous project evaluated the reuse of stormwater runoff for aesthetic,
recreational, and sub-potable and potable water supply purposes in the
new Columbia, Maryland Development [21].
In Mount Clemens, Michigan, a series of three "lakelets" have been in- ,
corporated into a park development. Treatment is being provided so that
these lakes are aesthetically pleasing and to allow their waters to be
used for recreation and reused for irrigation. The Mount Clemens design
has won the ASCE Conceptor award in the state. Other projects have shown
the feasibility of reclaiming stormwater [6].
Because of their value in urban planning, more demonstrations are needed.
A new EPA project is part of a planned community being developed near
Houston. Entitled "Maximum Utilization of Water Resources in a Planned
Community," the study will focus on how a "natural drainage system" can
be integrated into a reuse scheme for recreation and aesthetic purposes.
Runoff will flow through low vegetated swales and into a network of wet-
weather ponds, strategically located in areas of porous soils, as well
as into variable volume lakes. This attenuation process will allow some
of the runoff to seep into the ground and retard the flow of water down-
stream, thus preventing floods caused by development. A twelve acre man-
made lake, used as a pilot, will be the main focal point. Concentrations
of various biocides, nutrients, and disinfectant residuals in runoff and
their effect in the receiving lake system will be measured. Evaluation
of a multi-process and flexible stormwater pilot plant which will treat
runoff before it enters the lake will also be part of this program. The
pilot system evaluations will result in control recommendations for a
larger 400 acre lake to be built in the future.
Considering urban runoff as a benefit as opposed to a wastewater, along
with the concept of new community development which blends into and en-
hances its environment rather than upsetting it, will be employed' and
thoroughly evaluated for the first time. Hopefully, it will be shown
that man and the natural environment can coexist.
26
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EDUCATION
Storm generated pollution ranks high along with domestic and industrial
sources and yet remains unstressed in the schools. With wet-weather
control requirements evident, now is the time to encourage universities
to cover the concepts of stormwater runoff and combined sewer overflow
pollution in proper perspective in their graduate and undergraduate
school water pollution control curriculum.
EPA has sponsored the development of a course manual which will eventu-
ally be distributed to colleges throughout the country for easy and
direct incorporation into their respective curriculums. This project
is extremely valuable since it will give today's students an initial
background in a newly developed technology which is receiving national
emphas is.
A thorough mathematical modelling seminar has been presented at the
University of Massachusetts on August 19-23, 1974. Presentation of the
second seminar is anticipated during the summer of 1975. This program
is needed as rational solutions to urban hydrologic problems by simula-
tion models have been slow in reaching consulting engineers. Modelling
requires detailed understanding and instruction. To enhance its effect,
the seminar will start at an elementary level before continuing with
model development and user instruction.
CONCEPT RECRUITMENT
Many more ideas and concepts could be added — some may be more signi-
ficant than those discussed. Submission of ideas, project proposals,
or grant applications to the EPA is strongly encouraged.
27
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SECTION IX
REFERENCES
1. San Francisco Master Plan for Waste Water Management: Preliminary
Comprehensive Report. Department of Public Works. City and
County of San Francisco. (September 1971)
2. Cleveland, J. G., P. R. Walters, et al. Storm Water Pollution
From Urban Land Activity. Avco-Economics Systems Corporation,
Washington, D.C. No. 11034 FKL. NTIS No. PB-195-281. Environ-
mental Protection Agency, Edison, N.J. July 1970. 325 p.
3. Monroe, D. W. and J. P. Pelmudder, A Flushing System For Combined
Sewer Cleansing. FMC Corporation, Santa Clara. No. 11020 DNO.
NTIS No. PB-195-223. Environmental Protection Agency, Edison,
N.J. March 1972. 235 p.
4. Watt, T. R., R. G. Skrentner, and A. C. Davanzo, System Monitor-
ing And Remote Control. Metro Water Department, Detroit,
EPA Draft Report Proj. No. 11020 FAX. Environmental Protection
Agency, Edison, N.J. November 1972.
5. Sullivan, R. H., et al. The Swirl Concentrator As A Combined
Sewer Overflow Regulator Facility. American Public Works Asso-
ciation, Chicago, EPA-R2-72-008. NTIS No. PB-214-687. Environ-
mental Protection Agency, Edison, N.J. September 1972. 179 p.
6. Neijna, M. S., M. L. Woldman, P. L. Buckingham, R. E. Colman,
and J. L. Simons. Conceptual Engineering Report — Kingman Lake.
Roy F. Weston, Inc., West Chester, Pa. No. 11023 FIX. NTIS
No. PB-197-598. Environmental Protection Agency, Edison, N.J.
August 1970. 149 p.
7. Bachman Stormwater Treatment Plant: Monthly Report. City of
Dallas. Proj. No. 11020 FAW. Environmental Protection Agency,
R&D, Region IT, November 1972.
8. Sartor, J. D. and G. B. Boyd, Water Pollution Aspects Of Street
Surface Contaminants. Final Report. URS Research Company,
San Mateo. EPA-R2-72-061. NTIS No. PB-214-408. Environmental
Protection Agency, Edison, N.J. November 1972. 236 p.
9. Illinois Pollution Control Board, Illinois Water Pollution Control
Rules, Ch. 3, Parts I and IV (March 1972) in Environment Re-
porter 766:0501. p. 39-40, 46-48
28
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10. Illinois Pollution Control Board, Regulation No. R70-3, Second-
ary Treatment Dates, Mississippi River (January 1971)
11. State of Illinois Environmental Protection Agency, WPC Tech-
nical Policy 20-24, Design Criteria — Waste Treatment Plants
and Sewer Overflows (Revised July 1971) Sec 39 25 p.
12. Georgia Water Quality Control Act. Georgia Code Annotated
(Supplemental 1966) Ch. 17-5 and Ch. 88-26, as Amended by
Public Acts of 1971 and Senate Bills 493 and 494, 1972 Legis-
lature, Sec 2, 3, 10, 21A (1972) in Environment Reporter
S-103-104 751:0101-0106
13. State of Maryland, Sediment Control Law, Annotated Code Ch. 245,
Acts of 1970 (April 1970)
14. State of Maryland Department of Natural Resources, Rules and
Regulations, Sediment Control 8.05.03.01 Annapolis (April 1972)
P. 1
15. State of Maryland, A Letter Opinion, Attorney General. Annapo-
lis (April 1971)
16. California Regional Water Quality Control Board - San Francisco
Bay Region, Special Time Schedule for the City and County of
San Francisco Relative to Regulation of Discharges from Com-
bined Sewers, Resolution No. 70-93, Amending Resolution No. 67-64
(November 1970)
17. Orange County Planning Department, Orange County Florida Sub-
Division Regulations, Sec 9.6.1 - 9.6.6 (October 1972)
18. Field, R. The Dual Functioning Swirl Combined Sewer Overflow
Regulator/Concentrator, EPA-670/2-73-059. Environmental Pro-
tection Agency, Edison, N.J. September 1973. 49 p.
19. Thelen, E., W. C. Grover, A. J. Hoiburg and T. I. Haigh.
Investigation of Porous Pavements for Urban Runoff Control.
Franklin Institute Research Laboratory, Philadelphia.
No. 11034 DUY. NTIS No. PB-227-516. Environmental Protec-
tion Agency, Edison, N.J. March 1972. 142 p.
20. Shelley, P. E., and G. A. Kirkpatrick, An Assessment of Auto-
matic Sewer Flow Samplers. Hydrospace-Challenger, Inc. Rock-
ville. EPA-R2-73-261. Environmental Protection Agency,
Edison, N.J. June 1973. 233 p.
29
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21. Mallory, C. W. The Beneficial Use of Storm Water. Hittman
Associates, Inc. Columbia, Md. EPA-R2-73-139. NTIS No.
PB-217 506. Environmental Protection Agency, Edison, N.J.
January 1973. 266 p.
22. Sullivan, R. H., et al. Relationship Between Diameter and
Height For Design Of A Swirl Concentrator As A Combined Sewer
Overflow Regulator. American Public Works Association, Chicago.
EPA-670/2-74-039. NTIS No. PB-234 646/AS. Environmental Pro-
tection Agency, Edison, N.J. July 1974. 93 p.
23. Sullivan, R. H., et al. The Swirl Concentrator As A Grit
Separator Device. American Public Works Association, Chicago.
EPA-670/2-74-026. NTIS No. PB-233 964/AS. Environmental Protec-
tion Agency, Edison, N.J- June 1974. 44 p.
General References
1. Field, Richard, and E. J. Struzeski, Jr. Management and Control
of Combined Sewer Overflows. WPCF Journal. 44;7 p. 1393-1415,
July 1972.
2. Field, Richard, and P- Weigel. Urban Runoff and Combined Sewer
Overflow. Annual Literature Review, WPCF Journal. 45:6;
p. 1108-1115, June 1973.
3. Field, Richard, and P. J. Szeeley. Urban Runoff and Combined Sewer
Overflow. Annual Literature Review, WPCF Journal.
46^:6; p. 1209-1226, June 1974.
4. Field, Richard. Combined Sewer Overflows. Civil Engineering-ASCE.
4-3:2; p. 57-60, February 1973.
5. Lager, J. A. and W. G. Smith. Urban Stormwater Management and
Technology: An Assessment. Metcalf & Eddy, Inc., Palo Alto,
California. EPA-670/2-74-040. Environmental Protection Agency,
Edison, N.J. September 1974.
30
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-670/2-74-090
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
COUNTEKMEASURES FOR POLLUTION FROM OVERFLOWS;
THE STATE OF THE ART
5. REPORT DATE
December 1974; Issuing Date
6. PERFORMING ORGANIZATION CODE
'. AUTHOR(S)
Richard Field
'8. PERFORMING ORGANIZATION REPORT NO.
John A. Lager
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Storm & Combined Sewer Section Metcalf & Eddy, Inc.
(Edison, New Jersey 08817) Western Regional Office
AWTRL, NERC Palo Alto, Calif. 94303
Cincinnati, Ohio 45268
10. PROGRAM ELEMENT NO.
1BB034/ROAP 21ASY/TASK 01
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
National Environmental Research Center
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Summary Report
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES Publication based on EPA Contract No. 68-03-0179. Full text
published by EPA under title "Urban Stormwater Management and Technology: An
Assessment," EPA-670/2-74-040
16. ABSTRACT
Control and/or treatment of stormwater discharges and combined sewage overflows from
urban areas are problems of increasing importance in the field of water quality manage-
ment. Over the past decade much research effort has been expended and a large amount
of data has been generated, primarily through the actions and support of the U.S.
Environmental Protection Agency's (EPA) Storm and Combined Sewer Research and Develop-
ment Program. Presented in this text are selected results of a comprehensive investi-
gation and assessment of promising, completed and ongoing projects, representative of
the state-of-the-art in abatement theory and technology; a look at recent legislation;
and the identification of program needs and emphasis. Combined sewer overflows are
major sources of water pollution problems, but even discharges of stormwater alone can
seriously affect water quality. Current approaches involve control of overflows,
treatment and combinations of the two. Control may involve maximizing treatment with
existing facilities, control of infiltration and extraneous inflows, surface sanitation
and management, as well as flow regulation and storage. A number of treatment methods
tiave been evaluated including high rate screening and microstraining, ultra high rate
filtration, dissolved air flotation, physical/chemical treatment, and modified bio-
logical processes. A swirl flow regulator/solids separator of annular shape construc-
tion with no moving parts has been developed. High rate disinfection methods including
new disinfectants have been applied. Promising approaches involve integrated use of
controls and_treatment. The most disappointing have generally lacked flexibility in
their operation and design. Mathematical models have been developed and successfully
applied at multiple levels of sophistication"and complexity.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
Disinfection, Drainage, *Water pollution,
*Waste treatment, *Sewage treatment, *Sur-
face water runoff, *Runoff, *Waste water,
*Sewage, Contaminants, *Water quality,
*Cost effectiveness, ^Storage tanks,
*Storm sewers, *0verflows-sewers, *Com-
bined sewers, *Hydrology, ^Mathematical
models, Hydraulics
b.IDENTIFIERS/OPEN ENDED TERMS
c. cos AT I Field/Group
Drainage systems, Water
pollution control, pollu-
tion abatement, *Storm
runoff, *Water pollution
sources, *Water pollution
effects, *Wastewater treat
uent, *Urban hydrology,
^Combined sewer overflows
13B
8. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)'
UNCLASSIFIED
21. NO. OF PAGES
39
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
31
U. S. GOVERNMENT PRINTING OFFICE: 1975-657-590/5333 Region No. 5-11
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