WATER POLLUTION CONTROL RESEARCH SERIES 11024 ELB 01/71
Storm and Combined Sewer
Pollution Sources and Abatement
ATLANTA. GEORGIA
ENVIRONMENTAL PROTECTION AGENCY • WATER QUALITY OFFICE
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WATER POLLUTION CONTROL RESEARCH SERIES
The Water Pollution Control Research Reports describe the results and progress
in the control and abatement of pollution of our Nation's waters. They provide
a central source of information on the research, development and demonstration
activities of the Water Quality Office of the Environmental Protection Agency,
through in-house research and grants and contracts with the Federal, State
and local agencies, research institutions, and industrial organizations.
Triplicate tear-out abstract cards are placed inside the back cover to facili-
tate information retrieval. Space is provided on the card for the user's
accession number and for additional key words. The abstracts utilize the
WRSIC system.
Inquiries pertaining to Water Pollution Control Research Reports should be
directed to the Head, Project Reports System, Planning and Resources Office,
Research and Development, Water Quality Office, Environmental Protection
Agency, Washington, D.C. 20242.
Previously issued reports on the Storm and Combined Sewer Pollution Control
Program:
11034 FKL 07/70
11022 DMU 07/70
11024 EJC 07/70
11020 08/70
11022 DMU 08/70
11023 08/70
11023 FIX 08/70
11024 EXF 08/70
11023 FOB 09/70
11024 FKJ 10/70
11024 EJC 10/70
11023 12/70
11023 DZF 06/70
11024 EJC 01/71
11020 FAQ 03/71
11022 EFF 12/70
11022 EFF 01/71
11022 DPP 10/70
11024 EQG 03/71
11020 FAL 03/71
Storm Water Pollution from Urban Land Activity
Combined Sewer Regulator Overflow Facilities
Selected Urban Storm Water Abstracts, July 1968 -
June 1970
Combined Sewer Overflow Seminar Papers
Combined Sewer Regulation and Management - A Manual of
Practice
Retention Basin Control of Combined Sewer Overflows
Conceptual Engineering Report - Kingman Lake Project
Combined Sewer Overflow Abatement Alternatives -
Washington, D.C.
Chemical Treatment of Combined Sewer Overflows
In-Sewer Fixed Screening of Combined Sewer Overflows
Selected Urban Storm Water Abstracts, First Quarterly
Issue
Urban Storm Runoff and Combined Sewer Overflow Pollution
Ultrasonic Filtration of Combined Sewer Overflows
Selected Urban Runoff Abstracts, Second Quarterly Issue
Dispatching System for Control of Combined Sewer Losses
Prevention and Correction of Excessive Infiltration and
Inflow into Sewer Systems - A Manual of Practice
Control of Infiltration and Inflow into Sewer Systems
Combined Sewer Temporary Underwater Storage Facility
Storm Water Problems and Control in Sanitary Sewers -
Oakland and Berkeley, California
Evaluation of Storm Standby Tanks - Columbus, Ohio
To be continued on inside back cover....
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STORM AND COMBINED SEWER
POLLUTION SOURCES AND ABATEMENT
ATLANTA, GEORGIA
for the
ENVIRONMENTAL PROTECTION AGENCY
WATER QUALITY OFFICE
by
Black, Crow and Eidsness, Inc.
Consulting Engineers
Atlanta, Georgia
Program Number 11024 ELB
Contract No. 14-12-458
January, 1971
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EPA Review Notice
This report has been reviewed by the
Environmental Protection Agency Water Quality
Office and approved for publication. Approval
does not signify that the contents necessarily
reflect the views and policies of the Environmental
Protection Agency, nor does mention of trade
names or commercial products constitute
endorsement or recommendation for use.
11
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ABSTRACT
Six urban drainage basins within the City of Atlanta, Georgia, served by combined and
separate sewers, are studied to determine the major pollution sources during storm events.
Rainfall frequency analysis and simulation techniques are utilized to obtain design criteria
for alternative pollution abatement schemes.
High frequency storms are shown to cause the worst impact and most of the pollution from
combined sewer areas. Annual BOD from these areas is 2,078,000 pounds, or 460 Ibs/acre,
of which 57 percent is due to storms of two—week or higher frequency. Bypassing of
wastewater treatment plant flows during storms adds 690,000 pounds BOD/year. Runoff
from storm—sewered areas, at 253 Ibs/acre, adds 5,577,000 pounds/year. Overflows and
bypassed flows have severe impact upon the South River, due to their high deoxygenation
rates and coliform concentrations.
Annual BOD reduction from combined sewer areas of 57 percent may be achieved for a
total annual cost of $165,000, by modifying the three regulators and treating 80 percent of
the overflows, in conjunction with storage sufficient to contain a two—week storm.
Alternate, less favorable solutions include storage and treatment at existing treatment
plants, and storage with release to receiving streams after chlorination. Separation of
combined sewers would achieve 60 percent BOD removal for $3,030,000/year.
This report is submitted in fulfillment of Contract 14—12—458 between the Environmental
Protection Agency and Black, Crow and Eidsness, Incorporated.
Key Words: Storm overflow, combined sewer overflow, simulation, frequency analysis,
treatment costs, economic analysis, land use indicators, unit hydrographs.
Seis cuencas urbanas de drenaje en la ciudad de Atlanta, Georgia, servidas por cloacas
combinadas y separadas, han sido estudiadas para determinar las principales fuentes de
contaminacion durante las ocurrencias de lluvia. Elanalisis de frecuencia de lluvia y metodos
de simulacion fueron utilizados para obtener criterios de disefio para diferentes metodos de
controlar la contaminacion.
Se descubrio que las tormentas de frecuente ocurrencia causan el peor impacto y
contribuyen la mayor parte de la contaminacion en las regiones con cloacas combinadas. El
aporte anual de demanda bioquimica de oxfgeno (DBO) de estas regiones es 943,000 kg, 6
516 kg/hectarea, de la cual el 57 por ciento es debido a tormentas confrecuencia de dos
semanas, 6 mayor. El desvio de los flujos en las plantas de puradoras durante las tormentas
anade 313,000 kg de DBO por ano. El escurrimiento de areas con drenaje pluvial, que
contiene 284 kg/hectarea, anade 2,532,000 kg por ano. Los rebosos y desvios producen un
impacto severe sobre el rio South, debido a sus altos coeficientes de consume de oxfgeno y
concentraciones de coliformes.
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Una reduccion del 57 por ciento del DBO proveniente de areas con cloacas combinadas
puede lograrse por un costo total anual de $165,000, modificando los tres reguladores y
sometiendo a tratamiento el 80 por ciento de los rebosos, mediante embalse de un volumen
suficiente para una tormenta de dos semanas de frecuencia. Otras soluciones no tan
favorables incluyen embalse y depuracion en plantas existentes; tambien embalse con
aplicacion de cloro, previa a la descarga de las aguas al n'o. La separation de las cloacas
combinadas logroria una reduccion del 60 por ciento del DBO, a un costo de $3,030,000
anual.
Este informe se rinde en cumplimiento del Contrato 14-12-458 entre el Environmental
Protection Agency y Black, Crow and Eidsness, Inc.
Sechs stadtische Entwasserungsbecken innerhalb der Stadt Atlanta (USA Staat Georgia), die
von verbundenen und einzelnen Abzugskanale gespeist sind, wurden untersucht, um die
Hauptverunreinigungsquellen wahrend eines Unwetters festzustellen.
Analyse der Haufigkeit des Regens, sowie Nachahmungsmethoden wurden gebraucht, um
Anlage Kriterien fur alternative verunreinigungsverminderung Schemen zu erreichen.
Es liess sich erkennen, dass oftmalige Unwetter den schlimmsten Aufschlag sowie die
meisten Verunreinigungen vo verbundenen Abzugskanalgebieten verursachten. Jahrlicher
Biochemische Sauerstoff Bedarf (BSB) von diesen zwei Gebieten betragt 943,000 kg., oder
516 kg./ha. Zu den Unwetter, die alle vierzehn Tage oder haufiger vorkommen, ist 57
Prozent davon zuriickzufuhren. Ausweichung der Fluten der Abwasserbehandlungsstelle
wahrend des Unwetters fugt weitere 313,000 kg. BSB/Jahr hinzu. Ablauf von den Gebieten,
die mit Abzugskanale ausgeriistet sind, (284 kg./ha.) fugt weitere 2,532,000 kg./Jahr hinzu.
Uberflutungen und Ausweichungen haben schlimme Wirkung auf den South River, da sie
hohe Entoxydierungsgeschwindigkeiten, sowie hohe Kolonbazillen Konzentrationen
besitzen.
Jahrliche BSB Verminderung von verbundenen Abzugskanalgebieten mit 57 Prozent
konnten mit einem jahrlichen Kosten von $165,000 erreicht werden, indem die drei Regler
modifiziert sein werden, ferner, 80 Prozent der Uberflutung bearbeitet wird, und dazu
Lagerung genugend, ein Umwetter von vierzehn Tagen Dauer zu enthalten.
Alternative, jedoch weniger gunstige losungen: Lagerung und Bearbeitung bei den noch
verhandenen Behandlungsstellen, und Lagerung mit Abfluss in Flusse nach chlorinierung.
Trennung der verbundenen Kanale konnte 60 Prozent BSB Beseitigung bei einer Kosten von
$3,030,000/Jahr erreichen.
Dieser Bericht wird gemass Vertrag 14-12-458 zwischen den Umgebungsschutzagentur und
Black, Crow und Eidsness, E.V. iibergeben.
IV
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Six bassins de drainage urbains dans la Ville d'Atlanta, Georgie, servis des egouts combines
et separes, sont etudies pour determiner les sources majeures de la pollution pendant les
evenements d'orage. L'analyse de la frequence de precipitation et les techniques de
simulation sont utilisees pour obtenir des criteres a dessein pour des plans alternatifs a
diminuer la pollution.
II est montre que les orages en grande frequence cause le plus grand impact et la plupart de
la pollution qui vient des egouts combines. II y a une EBO (exigence biochimique
d'oxygene) annuelle dans ces regions de 943,000 kg. ou de 460 kg/hectare dont 57 pourcent
est du aux orages a frequence de deux semaines ou plus rapprochee. Pendant les orages
1'evitement des debits venant des installations qui traitent la perte—eau ajoute 313,000kg.
EBO/an. Le debit venant des regions aux egouts a orage, a 284 kg/hectare, ajoute 2,532,000
kg/an. Les debordements et les debits derives ont un impact severe sur le South River a
cause de hautes raisons de desoxygenation et de concentrations coliformes.
Une reduction annuelle de EBO peut etre achevee pour une somme annuelle de $165,000,
en modifiant les trois regulateurs et en traitant 80 pourcent du debordement conjointement
avec l'emmagasinage suffisant pour contenir un orage de deux semaines. Des solutions
alternatives mais moins favorables comprennent l'emmagasinage et le traitement aux
installations existantes et l'emmagasinage avec 1'echappement aux rivieres de reception apres
la chloruration. La separation des egouts combines accomplirait 1'enlevement de 60
pourcent EBO pour $3,030,000/an.
Ce rapport est presente pour remplir le contrat 14—12—458 entre le Environmental
Protection Agency et Black, Crow and Eidsness, Inc.
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CONTENTS
Section Number
Section I
Section II
Section III
Section IV
Section V
Section VI
Section VII
Section VIII
Section IX
Section X
Section XI
Section XII
Section XIII
Section XIV
Section XV
Section XVI
Abstract
Figures
Conclusions
Recommendations
Introduction
Description of Study Area
Methods of Study
Rainfall and Runoff
Combined Sewer Overflows
Storm Water Flows
Wastewater Treatment Plants
Other Sources of Pollution
Effect of Zoning and Land Uses on Pollution
Comparative Assessment of Pollution Sources
Conditions in the Stream
Pollution Abatement Approaches
Key Personnel
Acknowledgements
References
Appendices
Page Number
iii
vii
1
7
11
13
21
31
47
77
87
97
101
113
121
129
149
151
153
155
vii
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FIGURES
Figure Number Page Number
1 Location Map 14
2 Upper South River Drainage Basin — Storm and Combined Sewer
Mapping 15
3 Upper South River Drainage Basin — Area with Combined Sewers 17
4 Location of Monitoring Stations 24 — 25
5 Raingage and Chart 26
6 Rainfall Intensity—Duration—Frequency Curves (1903 — 1951) 32
7 Rainfall Intensity—Duration-Frequency Curves (2-week, 1 —month,
6—month, and 1—year storms) 35
8 Recorded Total Daily Precipitation, 1969 36
9 Recording Raingage Network 37
10 Distribution of Total Rainfall Volume for Atlanta Storms 38
11 Unit Hydrograph, Boulevard, Station 2 42
12 Unit Hydrograph, McDaniel Street, Station 3 43
13 Unit Hydrograph, Caspian, Station 5 44
14 Location of Major Combined Sewer Overflows 48
15 General Dimensions — Confederate Avenue Combined Sewer Overflow 50
16 Photographs - Confederate Avenue Combined Sewer Overflow 51
17 General Dimensions, Boulevard Combined Sewer Overflow 52
18 Photographs — Boulevard Combined Sewer Overflow 53
19 General Dimensions, McDaniel Street Combined Sewer Overflow 55
20 Photographs, McDaniel Street Combined Sewer Overflow 56
21 Photographs, McDaniel Street Combined Sewer Overflow 57
22 Variation of BOD with Time and Flow for Complex Storm 59
23 Variation of BOD with Time and Flow for Simple Storm 60
24 BOD Concentrations at Beginning of Overflow 62
25 Total Runoff BOD vs. Rainfall Duration for Single, High Frequency
Storms — Boulevard, Station 2 64
26 Total Annual BOD vs. Rainfall Duration for High Frequency Storms —
Boulevard, Station 2 65
27 Comparison of BOD Pollution from Combined and Storm Sewered Areas 66
IX
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Figure Number Page Number
28 Reservoir Storage of BOD from Boulevard and Confederate Overflows 69
29 Reservoir Storage of BOD from McDaniel Street Overflow 70
30 Storm Water Runoff Monitoring Sites 78
31 Photographs - Flow Level Recording Stations 80
32 Bypassing Record, Atlanta's Wastewater Treatment Plants within Upper
South River Basin 88
33 South River Wastewater Treatment Plant 90
34 Flow Diagrams: Plant A, Modified Aeration; Plant B, Trickling Filtration:
Sludge Treatment Facilities 91
35 Aerial View, Intrenchment Creek Wastewater Treatment Plant 93
36 Flow Diagram, Intrenchment Creek Wastewater Treatment Plant 94
37 Location of Sanitary Landfills 99
38 Drainage Area No. 1 — Confederate Avenue Combined Sewer Overflow 104
39 Drainage Area No. 2 — Boulevard Combined Sewer Overflow 105
40 Drainage Area No. 3 — McDaniel Street Combined Sewer Overflow 106
41 Drainage Area No. 5 - Caspian Street, Middle Branch South River 107
42 Theoretical Annual Average Dissolved Oxygen Profiles in South River for
2-week storm 114
43 Photographs - Gaging and Sampling Station; Flow Level Recorder, South
River at Klondike Road 122
44 Photographs - Flow Level Recording Stations, Jonesboro Road; Bouldercrest
Road 123
45 McDaniel Street Combined Sewer Overflow 135
46 Storage Area, McDaniel Street Overflow 136
47 Boulevard and Confererate Avenue Combined Sewer Overflows 137
48 Storage Area, Boulevard and Confederate Avenue Overflows 138
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CONCLUSIONS
1. High frequency storms cause significantly greater total annual pollution from
combined sewer overflows than low frequency storms. Provision for storage of
overflows from a small storm of two—week recurrence interval will enable
treatment of 80 to 88 percent of the total annual BOD released in combined
sewer overflows in the South River Basin, City of Atlanta.
2. Total annual BOD from combined sewer overflows and intercepted flows amounts
to 2,767,000 pounds. Of this amount, 2,078,000 pounds occurs as combined
sewer overflow, with an average yield of 460 pounds/acre. The remainder is due
to bypassing of wastewater treatment plant flows as a result of the deleterious
effect of intercepted combined flows upon influent quality.
3. The impact upon the South River of pollution from individual high frequency
storms is more severe than that from storms of low frequency. A two—week
storm causes anaerobic conditions in the South River at Klondike Bridge,
approximately 19 miles below the study area. A one—year storm lowers dissolved
oxygen (DO) levels to one mg/1 at this point. Extended duration, low intensity
rainfall causes DO to vary around three mg/1.
4. The primary sources of pollution during storm events over the study area, in order
of decreasing total annual BOD load, are as follows:
Ibs BOD/year
A. Storm drainage from urban areas (22,042
acres) 5,577,000
B. Combined sewer overflows to
Intrenchment Creek (3,550 acres) 1,633,000
C. Bypassing of flows from Intrenchment
Creek interceptor 506,000
D. Combined sewer overflow at McDaniel
Street (968 acres) 445,000
E. Intrenchment Creek wastewater treatment
plant effluent 185,000
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Ibs BOD/year
F Bypassing of flows from South River
wastewater treatment plant 183,000
G. South River wastewater treatment plant
effluent 146,000
Of these sources, combined sewer overflows and bypassed flows have the greatest
impact upon the South River, due to their high deoxygenation rates and high
coliform concentrations. Calculations indicate that such bypassing of all
treatment plant flows during a two-week storm occurring over the Atlanta urban
area, will cause anaerobic conditions to occur in the South River at Snapfinger
Creek. Prevention of bypassing during the same storm will cause the DO profile to
reach a deficit of 7.5 mg/1 further downstream at Flat Bridge, with the critical
point falling outside the South River Basin.
5. The impact upon the South River of bypassing intercepted storm flow at the
wastewater treatment plants is far more severe than release of the same flow as
combined sewer overflow at the point of interception. The difference in impact is
due to the large amount of untreated sewage entering the interceptor from areas
served by separate sewer systems. In addition to storm flows, the Intrenchment
Creek interceptor carries sewage from 46 percent of the area contributing to the
Intrenchment Creek wastewater treatment plant. Bypassing of all flow occurs due
to the grit, grease and mud introduced by intercepted combined flows.
6. Wastewater treatment plant effluents during dry weather flow are the primary
sources of pollution, causing significant impact upon stream water quality.
Combined effluent flows from the two treatment plants average 44 cfs and
constitute approximately 75 percent of the streamflow at Bouldercrest. Under
these conditions, the critical DO concentration occurs near Panthersville Road,
yielding an average deficit of 4.5 mg/1.
7. The average annual BOD from storm sewer areas amounts to 55 percent of that
from combined sewer areas. A one—year storm of two—hour duration yields
4.744 and 3.940 Ibs BOD/acre/hour of rainfall respectively, for combined and
storm sewer areas. By contrast, a two-week storm of five-hour duration yields
0.694 and 0.334 Ibs BOD/acre/hour of rainfall, respectively.
8. Twenty-five percent reduction in annual pollution from combined sewer areas
may be achieved by modifying regulators to eliminate interception of storm
flows. Estimated total cost of this approach is $50,000. Further pollution
reduction may be achieved by constructing reservoirs at the overflow sites to store
overflows from all two-week storms and major fractions of larger storms.
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9.
Treatment of the overflows by screening, dissolved air flotation and chlorination
will enable 57 percent reduction in total annual BOD from overflows and
bypassed flows. Total annual cost is estimated at $161,000.
Treatment of storm runoff from areas served by separate sewer systems was found
to be infeasible. The benefits and economics of several feasible alternatives for
pollution abatement are shown below, in order of increasing cost—benefit ratio:
Annual BOD Removed
Cost—Benefit Ratio
Alternative
Ibs
Percent
$/lb BOD
Regulator Modification
Intrenchment Creek
McDaniel Street
Storage, Screening,
Flotation, C12
Intrenchment Creek
McDaniel Street
Storage, Diversion
toWWTP
McDaniel Street
Storage, Chlorination
Intrenchment Creek
McDaniel Street
Sewer Separation
506,000
183,000
692,000
189,000
48,000
256,000
70,000
1,665,000
18
7
25
7
3
60
0.0057
0.0074
0.17
0.19
0.23
0.31
0.29
1.82
10. Correlation of pollution load from combined sewers with detailed land use is
unrealistic for all but very low frequency storms, in an industrial area. Correlation
with population density is significant. Percentage of undeveloped land may also
be significant. Pollution from storm sewer areas, and combined sewer areas at very
high flow rates, may be correlated with land use.
11. For small urban areas such as those considered in this study, continuous
monitoring of rainfall and runoff should be undertaken in such a way as to enable
accurate determination of short time interval variations. One—day recording
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charts proved sufficient in this study. Weekly charts permit accurate reading of
hourly variations only, which is not adequate to define unit hydrograph
characteristics.
12. For the subbasins considered in this study, 15—minute records of rainfall and
runoff were sufficient to define the unit hydrographs. Higher frequency records,
such as five—minute readings, are desirable since they permit accurate assessment
of synchronization of rainfall and runoff records as well as better definition of
unit hydrograph characteristics.
13. Derivation of unit hydrographs for a number of small urban subbasins requires
one rainfall monitoring station for each subbasin. A single rain gage for all
subbasins is not sufficient since travel time of a storm across the whole area may
be relatively slow by comparison with the concentration time of each subbasin.
This causes records at some stations to indicate the presence of runoff prior to
onset of rainfall. Accurate synchronization of rainfall and runoff records is most
important for derivation of average unit hydrographs.
14. Infiltration to the combined sewer system is not a significant problem in the
Atlanta area, due to the abundance of clays and other impervious materials.
15. Utilization of scow floats to measure interceptor flows is successful only when
such flows do not surcharge the interceptor, causing the water level to rise in the
manhole and the scow float to strike the top of the conduit.
16. Direct stage measurement of storm overflows using stilling wells and water level
recorders is limited by very high flow velocities accompanied by large suspended
and floating materials. These devices must be located in protected areas with
lower flow velocities.
17. Samples collected by automatic sampling devices tend to freeze in the sampling
tubes during extremely cold weather. Furthermore, the location of these
vacuum-operated devices at safe heights above expected peak flow levels limits
the volume of samples that may be collected for analysis.
18. The automatic triggering device utilized during this study is not reliable.
Dampness deteriorates electrical contacts and solenoids, causing failure of
apparently well insulated parts. The consequent necessity for manual triggering of
the automatic samplers reduces their usefulness and indicates the need for an
improved triggering device.
19. No significant differences exist between water quality analyses of simultaneous
samples obtained by grab and automatic sampling techniques. However, grab
sampling enables detailed coverage of the initial few minutes of overflows, during
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which variations in water quality are significant. Automatic sampling is more
suitable for longer time intervals, in order to cover an entire period of overflow.
20. A trend of decreasing rainfall in a southwesterly direction may exist in the
Atlanta area.
21. The COD/BOD ratio of storm water is higher than that for combined sewage.
Values found in this study were 3.60 and 2.07 respectively. However, the average
COD at the three combined sewer stations was 297 mg/1, compared to 60 mg/1 for
the storm sewers.
22. The six months originally scheduled for data acquisition in this project proved to
be insufficient. After development of accurate rating curves, evaluation of water
quality data was possible. However, the evaluation indicated the need for
improvement of data in certain areas, in order to obtain statistical validity of
resulting relationships. Fourteen months of data acquisition were required.
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RECOMMENDATIONS
1. The City of Atlanta should modify existing regulators at the Confederate Avenue,
Boulevard and McDaniel Street overflows at a cost of $50,000. Automatic gates at
these points will eliminate interception of combined flows and subsequent
bypassing of waste treatment plant flows, thereby reducing by 25 percent the
annual BOD released to the South River due to combined sewers.
2. Further study should be undertaken to determine settling characteristics, chlorine
demand and deoxygenation rates of combined sewer overflows at the two
proposed reservoir sites. This will enable more accurate assessment of BOD
removal due to settling in the reservoirs, the need for oxygenation of the effluents
from the reservoirs, and the required chlorine dosage.
3. Following reevaluation of the feasible treatment alternatives, consideration should
be given to implementing that combination of treatment processes yielding the
greatest reduction in total annual BOD at the lowest cost—benefit ratio. If the lab
studies confirm accuracy of the assumptions underlying the present economic
analysis, this combination will include storage, screening, dissolved—air flotation
and chlorination of overflows at the McDaniel Street and Intrenchment Creek
reservoir sites at a total annual cost of $161,000. When combined with regulator
modification, it would yield 57 percent removal of total annual BOD from
combined sewer overflows and bypassed flows.
4. Design of facilities to store and treat combined sewer overflows should utilize a
high—frequency design storm. This is in direct contrast to present practice, which
utilizes 10—15 year design storms at considerable, unnecessary expense. A design
storm of two—week recurrence interval, in conjunction with treatment facilities
designed to empty the reservoirs within 10 hours of overflow cessation, will
enable treatment of 80 percent of total annual BOD from combined sewer
overflows in the South River Basin, City of Atlanta.
5. Whenever storage of combined sewer overflows from high frequency storms is
feasible, consideration should be given to the possibility of precluding
interception of combined flows, and treating all stored overflows at the reservoir
site, as recommended in this study. When storage near the overflow site is not
feasible, consideration should be given to two alternatives:
A. Locate treatment facilities at the overflow site to treat the relatively
small flows from high frequency storms. Capacity of interceptors would
be restricted in order to avoid hydraulic overloading of sewage
treatment facilities.
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B. Increase interceptor capacity to enable storage and treatment of
overflows from high frequency storms at the existing treatment plant
site. Additional facilities would be required to handle the tremendous
volumes of flow.
Consideration of these alternatives and of the pollution loading and impact of
high frequency storms will permit the most effective management of physical and
financial resources available for combatting pollution from urban areas.
6. Further studies of combined sewer pollution should ensure synchronization of all
timing mechanisms on rainfall and water level recorders. In urban areas of the size
utilized in this study, 15-minute rainfall and runoff observations are adequate.
However, five-minute intervals are preferable in order to obtain unit hydrographs
that reflect accurately the response of the areas to rainfall. Hardware and
computation costs rise sharply with increasing sampling frequency.
7. Automatic triggering devices should be improved in order to fully utilize the
advantages of automatic samplers. Either better insulation of electrical
components or utilization of a purely mechanical device may increase reliability.
8. Automatic samplers should be improved to prevent freezing of samples in the
lines during cold weather. Continuous pumping of a small volume of the flow to
be sampled may alleviate this problem.
9. The simulation procedure followed in this study should be applied to other areas
of the United States. It offers much greater efficiency of data collection and
utilization than has been achieved in previous studies. It also yields insight into
the effects of a full range of rainfall characteristics upon pollution from combined
sewers.
10. Subsequent studies following the simulation approach of this report should utilize
both grab and automatic sampling techniques, in order to relate water quality to
flow and time. Coverage of the entire period of runoff requires long sampling
intervals, whereas coverage of the initial overflow and peak flows requires
sampling at short intervals. Grab sampling is most suitable for such short time
intervals.
11. Correlation of pollution load from combined sewers with population density in an
industrial area could be improved by consideration of population equivalent of
industrial wastes.
12. Minor additional study should be undertaken to determine the unit hydrographs
for areas contributing to the Confederate Avenue, Harlan Drive and Federal
Prison Branch monitoring stations. This would permit utilization of existing water
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quality data at these stations, thereby doubling the number of areas considered in
the correlation analysis of pollution load and land uses. Monitoring intervals at
these stations were too long to enable calculation of adequate unit hydrographs
for this study.
13. Periods of data acquisition on such projects as this should be of sufficient length
to enable accurate determination of rating curves. Concurrent acquisition of water
quality data may be conducted; however, any proposed schedule should recognize
that after completion of the rating curves, analysis of the relationships between
water quality parameters and flow rate will probably reveal additional areas of
required water quality data. Advance consideration of this need will enable
substantial improvement in statistical validity of these relationships.
14. In conjunction with other communities utilizing the South River, the City of
Atlanta should determine a point below which water quality will be maintained
for a purpose higher than effluent disposal. The potential demand for this water
resource for recreation and other uses should be considered prior to establishment
of the point.
15. Quality of the effluent from existing wastewater treatment plants should be
upgraded as necessary to meet the water quality standards at the established
point. Downstream sources of raw waste should be treated regardless of water
quality standards, although it is recognized that these municipalities are not
within jurisdiction of the City of Atlanta.
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SECTION I
INTRODUCTION
Scope and Purpose
The present project covers an engineering investigation and comprehensive technical study
to evaluate principal pollution sources within the upper South River basin in Atlanta,
Georgia, and to compare alternate solutions and remedial measures to the existing situation.
Correlation of pollutional load data and of storm runoff quantity and quality to zoning and
land use is also included in the purpose of the study.
Recognized pollution sources contributing to present conditions in the stream are overflows
from combined sewer systems; storm runoff from urban and other areas, eventual bypasses
of untreated wastes at wastewater treatment plants; and continuous discharges of treated
wastes in volumes too large for the assimilative capacity of the receiving stream.
A further purpose of the study is an evaluation of the benefits, economics and feasibility of
alternate schemes for control of pollution. This evaluation, although specific for the study
area, may be applicable to other cities with similar conditions.
General Background of the Project
Combined sewer overflows have been long recognized as a major source of water pollution.
However, until very recently, not too much work had been directed to quantitative
investigation and assessment of their pollutional significance. A large fraction of the
population, concentrated in the older and most populous metropolitan areas, is served by
combined sewer systems. Separation of sanitary and storm systems in these areas would
represent an almost insurmountable problem for the Nation.
In addition, recent investigations of characteristics of storm runoff from urban areas have
demonstrated that these discharges also constitute a large source of pollution for receiving
streams. Therefore, complete sewer separation would not fully protect these waters from
urban pollution.
The South River basin in Atlanta, Georgia, is a notorious example of stream deterioration
on account of pollution originating from a number of sources deriving from metropolitan
growth within the basin. Since the upper boundaries of the basin lie entirely within the City,
all flow from the headwaters of the stream is polluted at its origin. Part of the basin is served
by combined sewers, ending at major overflow points. Existing open streams originate at
these overflow points or at ends of storm sewers. Water supply for the area comes from the
Chattahoochee River basin, and reaches the South River only after being used and
discharged as waste.
11
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As an intrastate stream, the South River falls under jurisdiction of the State Water Quality
Control Board, which requires secondary treatment of all municipal wastes. At present the
upper stream reaches are used solely for the transport of wastewater treatment plant
effluent, which constitutes a significant fraction of the dry weather stream flow. In previous
years expanding development of the study area has caused conversion of sections of the
headwater channels to closed culverts. The trend is expected to continue in the future.
Investigation Procedure
The study included field surveying and mapping of portions of the storm and combined
sewer system. Continuous monitoring stations were located at five points within the area to
determine volume and distribution of rainfall. Six subbasins were chosen for detailed study,
three of which were combined-sewer areas. Overflows and intercepted flows from these
three areas were recorded and monitored for various water quality parameters. Runoff from
the remaining three storm-sewer areas was also recorded and monitored. Additional flow
recording stations were located on Intrenchment Creek and at four points along the South
River. Samples were taken periodically at these stations for water quality analysis. Data
were collected from January, 1969, until April, 1970.
The IBM 360 computer was utilized extensively throughout the study. Factors affecting
concentrations of various water quality parameters were determined, and equations were
developed from the data to predict these concentrations during periods of storm runoff.
Unit hydrographs relating rainfall to runoff in each subbasin were developed. Existing
rainfall records in the Atlanta area were utilized to calculate intensity—duration—frequency
curves for storms with return periods ranging from two weeks to one year, since preliminary
analysis of the data indicated that the small, high frequency storms contribute significantly
to the total annual pollution load upon the South River. A series of simulated rainstorms,
typical of those occurring in Atlanta, was created from these curves. For each storm the unit
hydrograph calculated from the data was utilized to determine the variation of flow rate
with time at the monitoring point. The equations relating BOD concentration to time and
flow rate were then utilized to determine the pollution load resulting from each simulated
storm, in terms of pounds BOD. The series of simulated storms covered a full range of
frequencies and durations. The results were analyzed to establish the relative pollution
impact of storm sewers, combined sewers, and wastewater treatment plant effluents and
bypasses. Also analyzed was the effect of land uses and storm characteristics upon pollution
loads and water quality in the South River. Based upon the results, various pollution
abatement schemes were considered, to determine the most effective approach to alleviating
the quantity and impact of pollution from urban areas served in part by combined sewers.
12
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SECTION II
DESCRIPTION OF THE STUDY AREA
General
The City of Atlanta, capital of Georgia, is the center of a fast growing metropolitan area
with a population presently exceeding 1.3 million. It is located on the Piedmont Plateau, at
the foot of the Blue Ridge Mountains, in the north central part of the State. Because of its
location, the terrain is rolling to hilly and several ridges cross the area. A subcontinental
divide cuts through the heart of the City, separating drainage into two major river basins;
namely, the Apalachicola, including the Chattahoochee and Flint rivers, that is tributary to
the Gulf of Mexico, and the Altamaha, discharging into the Atlantic Ocean and entirely
located within the State of Georgia (see Figure 1).
The South River is located within the Altamaha basin, its headwaters reaching downtown
Atlanta. This river runs approximately southeast for about 62 miles and ends at Jackson
Lake, northeast of the City of Jackson, Butts County. The lake also receives contributions
from the Yellow and Alcovy Rivers. Waters from Jackson Lake form the Ocmulgee River
that joins the Oconee to form the Altamaha.
The upper South River basin has well defined drainage boundaries consisting of natural
ridges, most of them utilized by the numerous railroad companies that serve the Atlanta
area as the most convenient routing for their multiple tracks. Elevation of these ridges
generally reaches or slightly exceeds 1,000 feet above sea level.
The study area lies entirely within the upper South River basin, and includes parts of
Fulton, Clayton and DeKalb Counties. Boundaries of this area were defined in the Plan of
Operation for the study. It encompasses a total of 41.5 square miles, covering all the
drainage area of the river down to the Bouldercrest Road bridge. Conditions in the river
were also monitored at Klondike Road bridge, about 16 miles downstream of Bouldercrest.
Approximately 33 square miles of the upper South River basin fall within the city limits of
Atlanta. Topographical information and storm and combined sewer records were lacking or
incomplete for this area. As a part of this contract, all elements of these sewer systems were
located in the field and plotted in detail on topographic maps previously prepared for the
City. Mapped area, city limits and basin boundaries are indicated in Figure 2.
Headwaters of the basin include, to the west and south, additional areas outside of Atlanta
proper. Flow contributions enter the Atlanta area from parts of the basin located within the
city limits of East Point and Hapeville, to the west, and within Mountain View and Forest
Park to the South. Unincorporated areas of Clayton County are also located at the
headwaters of the basin south of corporate Atlanta.
13
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/ N.
CAROLINA
TENNESSEE
4
\
•
\
N ^
S. CAROLINA
I ATLANTA
•SOUTH R
» BASIN
I
I
ALABAMA
! GEORGIA
GULF OF MEXICO
\
14
LOCATION MAP
ATLANTA
SOUTH RIVER BASIN
AND
ALTAMAHA BASIN
Figure 1
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ATLANTA CITY LIMITS
STUDY AREA BOUNDARY
STORM AND COMBINED
SEWERS FIELD LOCATED
AND PLOTTED ON MAPS
•• SOUTH RIVER BASIN BOUNDARY
Figure 2
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Most of the upper South River basin is highly developed, but conditions vary widely with
location, the northern portions being in general more developed than those to the south.
Land uses vary accordingly, extremes ranging from dense downtown commercial and heavy
industrial areas, to agricultural and entirely undeveloped tracts. Residential neighborhoods
cover large fractions of the area Industrial zones are generally concentrated on strips along
the ridges, following location of railroad tracks.
Sewered Areas
Combined sewers are found in areas at the north end of the basin, where growth of the City
was initiated during the last century. As required by urban growth and by the advent of
plumbing and sanitary facilities within the City, natural drainage courses were converted,
step by step, into combined sewers. These sewers were extended by sections, farther
downstream, as the City grew. A variety of cross sections is found in these old combined
sewers, many of which were built of dry masonry and stone slabs, or of brick and other
construction materials.
When, early this century, deterioration of streams in urban areas became a problem because
of increasing discharges of untreated sewage, construction of diversion works or regulator
structures to separate dry weather flows, and of interceptors, to convey them to treatment
plants, was initiated. These are the structures presently existing at combined sewer areas.
Other areas within the basin, developed later, are served by separate sewer systems of more
recent construction.
More distant sections where development is only beginning to take place are still unsewered.
Areas of the City of Atlanta that are presently served by combined sewer systems are
indicated in Figure 3.
South River Headwaters
At the headwaters, three separate branches join to form the South River, as can also be seen
in Figure 3. The north branch presently originates as an open course at the McDaniel Street
combined sewer overflow, its drainage area actually encompassing a combined sewer system
with headwaters reaching the Spellman College campus. During dry weather, there is no
flow in the first section of the north branch. Below the south expressway, a short distance
downstream, it receives additional contributions from a smaller combined sewer serving the
area adjacent to Pryor Road, north and south of University Avenue, and down to Joyland
Place.
The branch Hows southeast through the Lakewood Park area, bypassing the lake at the
park's oval racetrack. Thence it flows under Lakewood Avenue and through South Bend
16
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••• SOUTH RIVER BASIN BOUNDARY'
Figure 3
-------
Park, where slopes are very steep, accounting for a fall of 50 feet in a distance of only about
a thousand feet. Not far downstream it meets the other branches to constitute the South
River.
The middle branch is formed at the confluence of two smaller streams draining the Sylvan
Hills area, just west of Stewart Avenue and north of the Lakewood Freeway. One of these
streams originates at the end of a storm sewer discharging at the south side of Deckner
Avenue. It flows through Perkerson Park and under Caspian Street. A short distance
downstream the two streams merge into the middle branch. The branch crosses under
Stewart Avenue, continues through a number of structures that form a partially built storm
sewer system, then flows through the Atlanta fair grounds and into the lake at Lakewood
Park. The lake serves a flow regulation purpose. It overflows through a box culvert located
at its southwest end, its waters reaching the north branch at a point about a quarter-mile
below Lakewood Avenue in the South Bend Park area.
The south branch originates at the City of East Point and flows east into corporate Atlanta.
It drains an area generally located south of the Lakewood Freeway and west of Interstate
75, and presently flows as an open stream for a distance of about four miles before reaching
the confluence of the branches.
The north and south branches merge to form the South River a short distance south of
South Bend Park, about 500 feet east of Macon Drive. From this point the river flows
southeast to the Jonesboro Road bridge where a control station was established, and then
almost due east until it leaves the City of Atlanta and enters DeKalb County. Just
downstream of the Jonesboro Road bridge the river receives the effluent and occasional
bypasses from the City's South River plant. Effluent volumes usually exceed base flows of
the stream at this point.
Tributaries
The stream receives several tributaries within the upper basin, most of them from the north
side. Most important for this study is Intrenchment Creek, originating at the overflow of the
Boulevard combined sewer and also receiving overflows from the Confederate Avenue or
Stockade combined sewer at a point near Georgia National Guard. The Intrenchment Creek
basin encompasses part of downtown Atlanta, where the State Capitol and City Hall are
located. Intrenchment Creek flows east until it crosses Atlanta city limits, then runs
approximately southeast through DeKalb County to the location of Atlanta's Intrenchment
Creek Wastewater Treatment Plant. Effluent from this plant, and occasionally bypassed
flows, are discharged into the creek. Intrenchment Creek enters the South River 1.1 miles
upstream of Bouldercrest Road bridge.
Downstream of Bouldercrest the South River basin widens. By the time the stream reaches
the Klondike Road bridge, 16 miles below, the drainage area encompasses approximately
182 square miles and includes small fractions of Henry and Rockdale counties. A large
18
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number of tributaries join the river upstream of Klondike. Most important of them, from
the north side, are Sugar Creek, Doolittle and Doless Creeks, Shoal Creek, Cobbs Creek,
Snapfinger and Barbashela Creeks and Pole Bridge Creek. Poole Creek, Blue Creek, and
Conley Creek enter the river from the south. Many of these tributaries receive polluted
storm runoff from urban areas and discharges from municipal and industrial outfalls. The
basins of Sugar, Doolittle and Doless, and Shoal Creeks encompass highly developed areas.
Pollution Sources
Known pollution sources within the area are numerous, and a complete analysis and
evaluation of all of them is almost impossible within reasonable limits of time and cost.
Pollutional contributions to the stream from combined sewer overflows, storm runoff from
certain areas, treatment plant effluents, and bypassed flows are considered most significant
and assessment of their magnitudes has been undertaken. Highly significant also, but more
difficult to estimate, is pollution from industrial wastes, continuously or occasionally
reaching the stream. Numerous potential industrial sources of pollution are found to exist
within the basin. A complete investigation of the industrial waste problem, however,
exceeds the study limitations.
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SECTION III
METHODS OF STUDY
Location and Mapping
Storm and Combined Sewer Systems
Since maps of the storm and combined sewer systems were not available, the task of
location, leveling and mapping of these systems was included in the project and scheduled
for completion at an early date.
Surveying crews established a network of reference elevations, located in the field and
plotted on aerial contour maps all existing elements of these systems, and obtained invert
and top—of—rim elevations at all manholes, catchbasins and pipes at headwalls or other
hydraulic structures. Sewer sizes and materials were also investigated and included in the
mapping for the systems. Maps are on matching reproducible cronaflex to a scale of one
inch equals 200 feet and have 2—foot contours. The set consists of fifty sheets, including an
index. They served as a basis for the study.
Assessment of the Infiltration Problem
As a part of the storm and combined sewer survey, an assessment of the infiltration problem
was made. Visual inspection at every manhole of the combined sewer system indicated that
infiltration is not a significant problem in this area. This conclusion was supported by
information obtained through the City of Atlanta from their sewer maintenance crews.
Therefore it was deemed unnecessary to conduct additional conductivity measurements,
flow observations and smoke tests to locate leaks and illicit connections. An abundance of
clays and other impervious materials contributes to this lack of an infiltration problem.
Establishment of Basin Boundaries
Boundaries for the upper South River basin, and for each of the smaller drainage areas given
separate consideration in the study, have been established from the contour and storm
drainage maps described before. Contours at 2—foot intervals and detail of the existing
sewer systems permit accurate determination of drainage boundaries. For areas outside
corporate Atlanta, U.S. Geological Survey quadrangles and maps from Atlanta Region
Metropolitan Planning Commission and other sources were utilized.
Selection of Monitoring Sites
As a part of the statement of work included in the contract, monitoring sites within the
study area were selected during the preliminary steps of the study. Selection included all
21
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three known major overflow points, as well as interceptors originating at these points. It also
included three points at streams fed from storm runoff, for purposes of comparison. Control
stations along the river were located upstream of the outfall of South River wastewater
treatment plant and also at points below, where pollutional loads from this and the
Intrenchment Creek plant effluents and bypasses could be expected to influence more
directly conditions in the stream. A bypass at the interceptor entering Intrenchment Creek
plant was also monitored. Finally, a station was established at the Klondike Road bridge,
located about 20 miles downstream of the South River plant, where the river shows
recovery at normal or dry weather flow conditions. Location of all monitoring sites and of
recording rain gages appears in Figure 4.
Recording Gage Network
A first-order Environmental Science Services Administration (ESSA) station exists at
Atlanta airport. However, large variations in distribution, timing, and other storm
characteristics were expected between the small drainage areas under study. It was
anticipated that a rather dense recording rain gage network would be necessary.
Four recording rain gages were installed early during the study at selected locations within
the upper South River basin. Information from these stations was to be supplemented by
that from the Airport station and from an existing recording gage maintained at the Atlanta
Stadium, in the center of the basin's combined sewer area.
The four project rain gages were of the weighing and recording type, Catalog No. 5—780
from Belfort Instrument Company, Baltimore, Maryland. They consist of four major
elements: The collector, the weighing mechanism, the chart drive, and the housing. A
photograph of one of the installed instruments and a reproduction of a typical record chart
can be seen in Figure 5. The collector diameter is eight inches. Weighed amounts of
precipitation are recorded on a chart as inches of rainfall, and can be read to the nearest
hundredth of an inch. Charts are six inches high; recorders are single traverse type. The chart
drive is spring wound and runs eight days in one winding. All instruments were equipped
with time scale gears adequate for operation with eight—day charts. Later in the study, gears
were replaced in gages at Stations 51 and 52 to operate on one-day charts, permitting a
much more accurate reading of rainfall in short time intervals.
Establishment of Gaging and Sampling Stations
Measurement of quantity and quality of flows entering the stream, and flowing at different
points along it, was one of the key aspects of the investigation.
The nature of conditions at these monitoring sites necessitated both continuous and event
monitoring.
22
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Continuous monitoring was considered to be required at stations along the river and at
smaller streams where a base flow was found to exist at all times. It was also established at
the interceptors where dry weather flow characteristics were of interest to the investigation.
Event monitoring was needed mainly at overflow points where no flow exists at normal dry
weather conditions, and at bypass lines to existing treatment facilities.
Flow Measurement
Flow monitoring was generally accomplished through installation of flow level recorders and
development of rating curves at each of the selected monitoring sites.
Flow level recorders utilized were Stevens, Type F, Leupold & Stevens Instruments, Inc.,
Portland, Oregon. Construction of gaging stations and general installation details were in
accordance with U.S. Geological Survey established practice. Stilling wells were fabricated
of 14—gage corrugated aluminum pipe, with bottoms and cleanout doors. Water inlet pipes
were sized to dampen surges of the water surface as required by stilling well diameters.
For flow level recording at interceptors, scow floats were installed at selected manholes a
short distance downstream of the regulators.
Rating curves for all gaging stations were developed by stage—discharge measurements with
current meters. Price Type AA current meters, Scientific Instrument Co., Inc., Milwaukee,
Wisconsin, were employed for discharge measurements within the velocity and depth ranges
of these instruments. For low flow and shallow depth measurements, Pigmy type current
meters mounted on top setting wading rods were used. Whenever possible, discharge
measurements were verified by use of alternate methods or formulas in addition to current
meter measurements at certain stages. Samples of discharge measurement notes and rating
curves are included in Appendix D.
Sampling Procedures
Both grab and automatic sampling procedures were employed during the investigation.
Automatic sampling was more extensively used, generally being more advantageous.
Four Serco Model NW 3—8 automatic samplers, Sanford Products Corporation, Minneapolis,
Minnesota, were utilized. These samplers operate on a preset vacuum, and are capable of
collecting 24 sequential samples at equally spaced time intervals. Depending upon the clock
being used, five—, fifteen—, and sixty—minute sampling intervals can be obtained. Samples
are collected through individual flexible hoses ending at a protective sampling head that is
placed at the stream or sewer to be sampled.
Automatic sampling at points of continuous flow was accomplished by simply starting clock
mechanisms of the samplers at the selected times. Application of vacuum to the sample
23
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A GAGING OR SAMPLING SITES
LEGEND
1 - CONFEDERATE AVE. (COMBINED SEWER) " '
2 - BOULEVARD (COMBINED SEWER)
3 - Me. DANIEL ST. (COMBINED SEWER)
4 - HAfiLAN DRIVE (SOUTH BRANCH SOUTH R.)
5 - CASPIAN ST. (MIDDLE BRANCH SOUTH R.)
6 - FEDERAL PRISON BRANCH
7 * SOUTH RIVER, JONESBORO RO.
8 - SOUTH RIVER, BOULDERCREST RD.
15 - SOUTH RIVER, DOWNSTREAM OF SOUTH RIVER WWTP
16 - BY PASS, INTRENCHMENT CREEK WWTP
17 - SOUTH REIVER, KLONDIKE ROAD
-• — SOUTH RIVER BASIN BOUNDARY '
I WASTEWATER TREATMENT PLANTS
40 - SOUTH RIVER TREATMENT PLANT
41 - INTRENCHMENT CREEK TREATMENT PLANT
» RECORDING RAIN GAGES
50 - ATLANTA AIRPORT r
51 - STEWART - LAKEWOOD
52 - ATLANTA STADIUM
53 - GEORGIA NATIONAL GUARD
54 - JOHNSON MOTOR LINES
55 -GREEN BROTHERS
--— DRA'INAGE AREA BOUNDARY
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24
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Recording Raingage
Stewart Avenue North of Lakewood Freeway
(Station 51)
•-•;
Typical Raingage Weekly Chart
26
Figure 5
-------
bottles was performed with a vacuum pump in the laboratory. At each sampling station an
adequate setup for the samplers was prepared, including means for protecting them from
theft or vandalism.
Samples were retrieved at the end of each sampling period, usually within four to six hours,
and were taken to the laboratory for analysis. A significant fraction was collected during the
cool weather part of the year, offsetting the need for sample refrigeration prior to retrieval
and analysis.
For event sampling, as in the case of overflows and bypasses, an automatic triggering device
was developed so that automatic sampling would be started only when flow was initiated at
the sampling station. The purpose of this type of sampling was primarily to monitor events
beginning at times when no personnel would be available to manually start the sampler or to
take grab samples.
The triggering devices prepared for use in conjunction with the automatic samplers consisted
of a solenoid capable of unblocking the escape of the sampler's clock when energized by
means of a battery operated electric circuit. Closing of the circuit was accomplished by
contact of a stainless steel wire with a screw in the wheel of the flow level recorder. Contact
adjustment was easy, permitting start of the clock at a predetermined flow depth increase.
Four hundredths of a foot was generally selected. With this arrangement, the first sample
was taken one sampling interval after beginning of the event.
Operation of triggering devices was successful when first used, but many difficulties were
soon experienced. Although high voltage batteries were utilized, electrical contacts proved
deficient, and the apparently well—insulated solenoids were affected by dampness.
Consequently during the latter part of the study, the sampler had to be triggered by hand. It
was also found that equal time—interval sampling was not desirable for some events, and
that too much time was elapsing between the beginning of the event and collection of the
first sample.
Main difficulties with grab sampling of the initial phases of overflows were with personnel
availability at the right time and place. Commencement of rainfall proved difficult to
predict. After storms commenced, traffic conditions always worsened in the area, making it
impossible to reach the sampling locations in time.
When possible, grab sampling of the initial overflow discharges gave a better coverage of the
variation of quality with time during these events. Simultaneous grab and automatic
sampling at a few stations for verification of the performance of automatic samplers in
obtaining representative samples produced no significant differences.
Difficulties were encountered in establishment of rating curves, due to the short time
allocated for data acquisition. The large number of sites to be gaged, the unpredictability of
heavy storms and the variability of available personnel combined to limit the number of
27
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occasions during which rating curve points might be established at each site. The unsteady
peak rates of storm runoff hindered accurate gaging at these high flows.
Until sufficiently well defined rating curves were developed, it was not possible to relate
concentrations of water quality parameters to flow rate, as discussed subsequently in this
report. This in turn delayed assessment of areas for which additional water quality data were
needed to improve statistical validity of conclusions. For this reason the six months
originally scheduled for data acquisition proved to be insufficient.
Additional problems were encountered with location of stilling wells and weirs at sites
yielding very high flow velocities during periods of runoff. One complete stage-level
monitoring station and one weir were lost during the period of study. Equipment was
generally located in partially protected areas with lower flow velocities. Any error due to
this adaptation of the ideal procedure should be minimal since the rating curves related flow
to water level in the stilling well.
Measurement of storm flows in the interceptors occasionally was complicated by
surcharging within the manhole, especially at the McDaniel Street interceptor. This caused
the scow float to rise to the top of the pipe, preventing accurate flow measurement.
Sample volumes obtained by the automatic samplers were insufficient to perform the full
range of tests conducted during the study, thereby necessitating partial analyses on each
sample. Due to large stage variation during overflows, samplers had to be located high above
low flow levels. Vacuum was therefore insufficient to fill the sampling bottle, since
considerable portions remained in the sampling tube. Collection of larger samples would
have required a much larger and less maneuverable device. Furthermore, during the winter
months, problems were encountered with samples freezing in the long tubes before reaching
the bottles.
Laboratory Establishment — Sample Analysis
To facilitate transportation of samples for analysis and reduce elapsed time between
sampling and testing, a laboratory within the study area was established. The laboratory was
located, through cooperation of the City of Atlanta, in the Intrenchment Creek wastewater
treatment plant, and was equipped to perform all analyses required by the contract.
Capacity of the laboratory was based upon handling batches of 96 samples at peak load
times.
All testing was done in accordance with Standard Methods for the Examination of Water
and Wastewater, 12th Edition, 1965. To facilitate laboratory work, a brochure was prepared
with simplified, step-by-step descriptions of all procedures for the physical and chemical
examinations to be performed. The laboratory was organized to test for biochemical oxygen
demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), total suspended
solids, volatile suspended solids, settleable solids, conductivity, pH, acidity, alkalinity, total
28
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and orthophosphates, chlorine residual, total residue, and volatile residue. A reasonable
number of tests were conducted on each sample. Bacteriological determinations included
total coliform, fecal coliform, and fecal streptococci.
Continuous Quality Monitoring
Conductivity, temperature, and disolved oxygen were continuously monitored in the field
by means of portable, battery—powered recording equipment. Conductivity recorders were
Beckman Model RQ—1, Beckman Instruments, Inc., Fullerton, California, with automatic
temperature compensation. Charts and clock mechanisms for weekly and 24—hour
recording were used. Some problems were encountered with the recording mechanisms of
these recorders.
For dissolved oxygen and temperature monitoring, Rustrak Model 192 recorders, Rustrak
Instrument Division, Gulton Industries, Inc., were used. Difficulties were found with
operation of oxygen probes when flow velocities were low at locations being monitored.
Once clogged at low flow velocities, the probes failed to clear with an increase in flow. The
recording charts permitted continuous monitoring for approximately one—month periods,
however, the probes generally failed to operate after a very limited amount of time.
Personnel limitations precluded suffuciently frequent attention to these remote recorders.
Data Collecting and Processing
Data from the stage level recorders and laboratory analyses were reduced to tabular form
and punched onto IBM computer cards for subsequent analysis on the University of Florida
IBM 360/65 computer. A computer program was written to interpret all overflow events at
each combined sewer station and present them as outflow hydrographs. Cumulative flows
for each event were also calculated. A similar program was used to present dry and wet
weather flows at other monitoring sites. Samples of the printouts for a few events are
included in Appendix D. Hydrograph similarities between two nearby overflow points can
be noticed during a winter or frontal type storm.
Another program tabulated all chemical analyses for each time increment during overflow
events, and calculated the pollution loading rates for each parameter in 1,000 pounds per
day. This procedure enabled periodic analysis of rainfall, runoff, and water quality data in
order to select overflow events suitable for further detailed study. A sample of chemical
analysis results on a computer printout sheet is included in Appendix D.
29
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SECTION IV
RAINFALL AND RUNOFF
Existing Local Precipitation Records
Good climatological data records are available for the Atlanta area in general. An ESSA
(Environmental Science Services Administration) station is located at the Atlanta airport,
outside the South River basin, but only two—thirds of a mile west of the basin divide.
Hourly precipitation records are available for this station, and were utilized to supplement
data obtained from the rain gages installed at selected points within the study area.
The Atlanta station was established in 1878 at the Kimball House in downtown Atlanta. It
occupied this and several nearby locations until 1954, when the last instruments in use were
removed. The Airport station was established in 1928 and its records became official for the
Atlanta area beginning December 1, 1934.
Mean annual rainfall for the 1879—1969 period of record is 48.46 inches. This figure is not
adjusted for instrument location changes that have occurred during the 90 years. For the
39—year period beginning in 1931, the maximum annual precipitation was 71.45 inches in
1948, and the minimum 31.80 inches in 1954. Long range records indicate that the
minimum monthly mean precipitation occurs in October and the maximum mean in March.
Storms in the area are basically of two different types: winter storms of the frontal type,
generally of long duration resulting in moderate to heavy precipitation; and summer
thunderstorms, generally brief but more intense.
Rainfall Intensity—Duration—Frequency Curves
Rainfall intensity—duration—frequency curves for the area have been developed by the U.S.
Weather Bureau using the method of extreme values, after Gumbel, for the period of record
1903 to 1951. These curves are reproduced in Figure 6. Means and extremes of monthly
precipitation, as well as maximum 24—hour records for a 35—year period (1934—1969), are
shown in Table 1. Monthly totals and greatest 24-hour figures for 1969 are also included in
this table. For storms more frequent than two years it may be assumed that the extreme
value distribution does not fit. A better fit would be obtained with a log—normal
distribution. Such frequencies are of interest to combined sewer overflow problems.
Intensity—duration—frequency curves for storms of less than a two—year frequency were
therefore constructed.
Records from the Atlanta airport (ESSA) station were chosen, to enable subsequent
refinement of the curves if this becomes necessary. The period from July, 1968, to
February, 1970, comprising 20 months of hourly rainfall data, was analyzed. Rainfall during
31
-------
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5 10 15 20 30 40 50 60 2 34568 10 15 20 24
MINUTES HOURS
DURATION
SOURCE: U.S. WEATHFR BUREAU
TECHNICAL PAPER NO. 25
PERIOD OF RECORD: 903 1951
FREQUENCY ANALYS S BY METHOD OF
EXTREME VALUES AFTER GUMBEL CITY OF ATLANTA, GEORGIA
RAINFALL INTENSITY
DURATION-FREQUENCY CURVES
32
Figure 6
-------
TABLE 1
PRECIPITATION IN INCHES
ATLANTA AREA*1)
Month
January
February
March
April
May
June
July
August
September
October
November
December
Year
Normal
Total*2)
4.44
4.51
5.37
4.47
3.16
3.83
4.72
3.60
3.26
2.44
2.96
4.38
47.14
1935 -
Maximum
Monthly
10.82
12.77
11.51
9.86
7.83
7.52
11.26
8.69
7.32
7.53
15.72
9.92
14.72
1969 Period of Record
Minimum
Monthly
1.42
0.99
2.73
1.45
0.32
0.74
1.20
0.88
0.26
T
0.41
1.08
T
Maximum
24 Hours*3)
3.27
5.67
4.82
4.26
5.13
3.14
5.44
5.05
5.46
3.27
4.11
3.85
5.67
Calendar Year 1969
Month
Total
2.85
3.20
4.00
5.70
7.68
1.00
2.64
6.12
3.74
1.53
2.67
3.27
44.40
Greatest in
24 Hours
1.65
0.71
1.53
2.69
4.34
0.43
1.51
1.79
1.89
0.69
1.44
1.11
4.34
Airport Station Records Official for Atlanta Area beginning December 1, 1934.
(2)ciimatological Standard Normals (1931 - 1960).
(•^Maximum 24—hour precipitation on record: 7.36 inches, March 1886.
T = Traces
Source: U.S. Department of Commerce, Environmental Science Services Administration
33
-------
this period was 4.7 percent below normal, based upon 30 years of record (1931 to 1960).
Rainfalls of less than 0.04 inch per hour were excluded, as was one five—year storm that
occurred during the period. The resulting curves for two—week, one—month, six—month,
and one—year storms are shown in Figure 7.
Recorded daily precipitation for the year 1969 is shown graphically in Figure 8 for the
Atlanta airport station and for the study's rain gage network. Location of rain gages can be
seen in figure 9.
Availability of records from the Atlanta Stadium station (No. 52) was lost by the end of
March, 1969. It was not, however, until some later date that this was realized, since this
station was not maintained by project's personnel. To replace the stadium station, the
project rain gage at Station 55 was removed and installed at the City's Fire House No. 5,
adjacent to the stadium, this location being most important for the study's purpose.
Records for the storms of April and May, 1969, lost at the stadium station, could not be
obtained from a recording gage operating then at the Georgia Institute of Technology, since
charts for these months were reportedly misplaced.
Daily recordings were also obtained for the Peachtree-DeKalb airport station located eleven
miles north-northeast of the center of the rain gage network. Fifteen-minute recordings
for selected storms are also available from this station. For the main purposes of this study,
however, records from this station were of little help, due to significant differences in times
of events. Differences in rainfall characteristics between this station and those in the
project's rain gages for given storms confirm the need for a dense rain gage network, as well
as short-interval rainfall intensity measurement, for studies of this kind. Accurate
synchronization of all stations is also essential for adequate correlation of records.
Observed Rainfall Distribution in Study Area
Total precipitation during 1969 was calculated at each of the five ainfall stations in the
study area and results were augmented by records from Atlanta and DeKalb—Peach tree
airports, Robbins Air Force Base and a point near the Fulton County airport. The records
range from a high of 54.30 inches at DeKalb-Peachtree airport eleven miles to the
north-northeast, to a low of 44.40 inches at the Atlanta airport six miles to the
south-southwest of the study area. Stations 51 and 52, which monitor rainfall for the three
areas of greatest importance in this study, averaged 53.54 inches per year. The data are very
limited; however, a possible trend may exist with rainfall decreasing in a southwesterly
direction, reflecting the clima ological influence of the nearby Blue Ridge mountains. The
effect of rainfall distribution is discussed in Section V.
The 118 storms occurring during 1969, as recorded at the Atlanta airport, were categorized
to determine their volume distribution. Fifty-six of these storms yielded 0.10 inch of rain
or less, while the largest storm produced 4.34 inches. The distribution is plotted in Figure
10.
34
-------
1.4
1 .2 •
3 in.
0 1 • U
at
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Station N9 50: Atlanta Airport (ESSA)
si : Stewart - Lakewood
52: Atlanta Stadium (Jan.-March)
Firehouse N9 5 (Alter Aug. 18)
53.- Georgia National Guard
54: Johnson Motor Lines
55: Green Brothers
10 XS
DICCMBK1I
RECORDED TOTAL DAILY PRECIPITATION
CALENDAR YEAR 1969
H-
iQ
c
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M- &?&*
"tV ^ i I (46/89)
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e 54
• 55
ATLANTA AIRPORT (ESSA)
STEWART - LAKEWOOD
ATLANTA STADIUM
(O-FIREHOUSE NO.5)
GEORGIA NATIONAL GUARD
JOHNSON MOTOR LINES
GREEN BROTHERS
•«• SOUTH RIVER BASIN BOUNDARY ,.
(00.00) TOTAL RECORDED RAINFALL, 1969
j: j-if i :T ;!T^^0;vM^
,4 - ^ V ' - V ..,-< 1 1 '•-••>*'•} ' •- :•: -I
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(•Data Augmented from Slat Ion ;5lJ-i Xr-f —--^ L
UPPER SOUTH RIVER
DRAINAGE BASIN
RECORD ING
RAINGAGE NETWORK
37
Figure 9
-------
c.
NOTE
APPROXIMATE
APPROXIMATE
APPROXIMATE
LOCATION
LOCATION
LOCATION
OF
OF
OF
2-WEEK STORM
1 -MONTH STORM
6-MONTH STORM
2
3.
NEGLECTS VARIATIONS IN STORM DURATION
BASED UPON 118 STORMS IN 1969.
BASED UPON DATA FROM ESSA STATION,
ATLANTA AIRPORT
UJ
00,
cc
UJ
CO
cnp
0. 2
0.4 0.6 0.8 1!
TOTAL RAINFALL ( inches)
DISTRIBUTION OF TOTAL RAINFALL WITHIN EACH SEPARATE OVERFLOW EVENT
2.0
-------
Observed Runoff in Study Area
Measured peak flow rates resulting from three storms occurring during the period of study
are shown in Table 2. Recurrence intervals were determined from rainfall records at station
5, Caspian Street, and are therefore approximate for stations 2 and 3, Boulevard and
McDaniel Streets, due to nonuniformity of rainfall distribution.
TABLE 2
Storm
May8, 1969
Nov 12, 1969
June 15, 1969
Recurrence
Interval
5 yrs
2 mos
2 wks
Peak Flow
Boulevard
985
520
320
(cfs) at Monitoring
McDaniel
934
333
187
Station
Caspian
626
270
244
Flows at stations 1, 4, and 6 were recorded with insufficient frequency during storm events
to justify conclusions concerning peak flow rates occurring during runoff events at these
stations.
Peak runoff at Caspian Street for the five—year storm was compared with the value obtained
from the Burkli—Ziegler formula, which is presently used by the City of Atlanta for storm
drainage design for areas over fifty acres. The calculated runoff was 610 cfs, comparing well
with the measured value of 626 cfs. However, conclusions concerning the validity of present
Atlanta design criteria incorporated in this formula should be based upon more data than
were obtained during this study.
Rainfall—Runoff Relationships
Determination of the relationship between rainfall and runoff for each of the subbasins was
obtained by unit hydrograph analysis. The unit hydrograph represents the "system"
response to a sudden pulse of one inch of rainfall over the entire basin. Three major
assumptions of unit hydrograph theory are as follows:
1. Identical storms with identical antecedent conditions
produce identical hydrographs.
2. Time bases of all floods caused by rainfall of equal duration
are the same.
39
-------
3. Assuming areal and time distribution is similar for several
storms, the ordinates of each hydrograph are proportional to
the volume of runoff.
These assumptions define a linear system, for which a unique unit hydrograph may be
obtained for each basin. However urban areas tend to be nonlinear in their response to
rainfall. Runoff flows in channels and sewers at rates which are exponential functions of the
hydraulic radius and slope, as defined for instance by the Manning formula. Variations in
rainfall distribution during different storms will cause changes in basin runoff response.
However, response characteristics may be assumed to be linear over a limited range of inputs
without causing unreasonable errors. It is therefore desirable to find a linear system that will
best fit a nonlinear system over a given range.
A computer program was written to calculate the unit hydrographs, using the procedure
outlined by Eagleson, et al, (1966). Least-squares analysis of the convolution equations
obtained in the unit hydrograph derivation yields those equations giving the best fitting unit
hydrograph. Such an analysis leads to the discrete form of the Weiner-Hopf equation:
0fg(j - 1) = 2 hopt(k) 0ff(j - k)
Where O
j= 1,2, ...m
40
-------
This method guarantees a feasible solution but it will yield slightly more error than if
hydrograph coordinates were allowed to be negative. At present, this is the best way to
apply a linear formulation to nonlinear data. A listing of the computer program written in
Fortran IV is included in Appendix B.
Preliminary calculations with this program indicated that one—hour rainfall and runoff
increments are inadequate for satisfactory hydrograph derivations. Eagleson and Shack
(1966) have shown that for urban areas with runoff concentration times of approximately
20 minutes, one—minute rainfall increments are required for accurate analysis of high
frequency components of the basin response. However, such accuracy was unnecessary for
this study. Fifteen—minute readings proved to be of sufficient frequency to define the
hydrographs for three subbasins. Rainfall contributing to flow at station 2, Boulevard, was
monitored at station 52. Rainfall contributing to flow at station 5, Caspian Street, was
monitored at station 51. Rainfall contributing to flow at station 3, McDaniel Street, was
calculated by a weighted average of rainfall at stations 51 and 52, determined by the
Thiessen method. Therefore, this study focuses upon the three subbasins for which accurate
rainfall—runoff relationships may be defined. Two of these three areas contain combined
sewers.
Storms monitored during the period of study were screened to ensure approximately
uniform areal distribution, synchronization of rainfall and runoff records, single peaks, and
recurrence intervals similar to those considered to be most significant in combined sewer
pollution problems. Generally these were short, relatively intense storms yielding more than
0.5 inch of rain. Unit hydrographs were derived for each selected storm and an average unit
hydrograph for each subbasin was then obtained by determining the average peak and the
average time to the peak and fitting the hydrograph to this point. The alternative, more
complicated methods of nonlinear analysis are considered to be unwarranted for this study.
Resultant hydrographs for area 2, contributing to overflow station 2, are shown in Figure
11, along with the average unit hydrograph. Figures 12 and 13 show the average unit
hydrographs for areas 3 and 5. Each figure includes the value of the peak hydrograph
ordinate, and the time to peak.
Simulation Procedure
The conventional approach to assessment of pollution from combined sewer overflows
entails collection of samples for water quality analysis at equal time intervalo throughout a
number of overflows. Results indicate order—of—magnitude concentrations of various
parameters that are present in the overflows. Simultaneous monitoring of flow rate permits
calculation of total mass discharges of these parameters to the receiving stream.
Although widely used, this approach has a number of disadvantages. Adequate personnel are
required to enable sampling of water quality throughout an overflow of unpredictable
commencement and duration. Automatic sampling at preset time intervals throughout the
41
-------
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35
40
45
50
-------
entire period is difficult due to the limited number of samples that may be taken. Attempts
to utilize the automatic sampler for this purpose invariably yield incomplete coverage of
runoff from long duration storms, or insufficient coverage from short duration storms. In
addition, this approach does not permit assessment of combined sewer pollution from a
wide range of storm frequencies. Conclusions are generally based upon storms occurring
during a short period of study, thereby limiting observation of any significant number of
low frequency storms.
Preliminary analysis of water quality data indicated the existence of a relationship between
pollutant concentrations, flow rate and time for each of the three areas focused upon in this
study. This observation suggested the possibility of a simulation scheme to utilize the water
quality data most efficiently. A brief summary of this new approach follows.
As described previously in this section, rainfall intensity—duration—frequency curves were
developed for the study area for relatively high frequency storms. The curves were utilized
to synthesize a series of rainstorms. For each storm the peak hourly intensity was 2.5 times
the average hourly intensity for the whole storm. In one series the peak occurred at
one—quarter of the duration. In another series the peak occurred at three—quarters of the
duration. For each series the following storms were synthesized:
Storm
Frequency
(weeks)
2
4
26
52
DURATION
1 2
1 2
2
_ 2
(hours)
5
5
5
5
10
10
10
—
—
20
The simulated rainstorms were convolved with unit hydrographs for the three areas to yield
the time variation of runoff from each of the storms. Equations relating pollutant
concentrations to flow rate and time were calculated from the data and were then utilized
to determine concentrations and total pollutant discharges from each of the simulated
storms. Resulting values are accurate within the bounds of confidence implicit in the
calculation of the average unit hydrographs and the pollutant concentration equations. In
general, results are considered to be reasonable average values, about which farily wide
distributions occur.
Advantages of this new approach are significant. It permits utilization of automatic sampling
devices without the requirement for complete coverage of a storm overflow. This decreases
the number of personnel needed. The data collection program is much more simple and
flexible, since discrete data points relating concentration to flow rate are more readily
obtained than complete sequences of points covering an entire period of overflow. In
addition to these advantages, the simulated storms may be varied in order to determine the
45
-------
pollution effect of both high and low frequency storms. The alternative procedure of
waiting for the actual storms and monitoring the overflows is far more time—consuming.
The new approach utilized in this study therefore yields considerably more information
from a given data collection program than the conventional approach. The improved
efficiency requires only that hourly rainfall records be available near the study area, in order
to derive the intensity-duration-frequency curves.
The rainfall records were examined to determine storms of approximately uniform area!
distribution. Runoff coefficients during these storms were calculated for each area and
averaged. Results are shown in Table 3.
TABLE 3
Sub-
basin
1
2
3
4
5
6
Type of
Sewer
Combined
Combined
Combined
Separate
Separate
Separate
No. of
Storms
5
12
12
15
19
19
Average
Runoff
Coefficient
0.31
0.42
0.42
0.33
0.56
0.31
0.39
Standard
Deviation
0.06
0.06
0.09
0.12
0.21
0.19
Some of the storm runoff in areas served by combined sewers is intercepted by the conduits
that normally carry dry weather sewage flow to the wastewater treatment plants. For large
storms this fraction is very small; however for small storms this can amount to a significant
part of the total runoff. Since intercepted storm flows are generally bypassed to the
receiving stream at the treatment plants, their total volumes were added to overflow
volumes prior to calculation of runoff coefficients.
46
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SECTION V
COMBINED SEWER OVERFLOWS
Major Overflows in Study Area
Preliminary work on the project established the existence of three major overflow points
within the study area. All three occur at the ends of combined sewers draining highly
developed and densely populated areas. Their location is shown in Figure 14.
Largest of all is the overflow at Boulevard, based on area and population served, as well as
on volumes discharged. Overflows from the Boulevard and Confederate Avenue combined
sewers are discharged into Intrenchment Creek. The third major overflow, at McDaniel
Street, contributes wet weather flows to the north branch of South River. Table 4
summarizes areas and populations served by these major combined sewer systems down to
the points of overflow.
TABLE 4
Station
Number
1
2
3
Station
Designation
Confederate Ave
Boulevard
McDaniel Street
Acres
Drained
1129.02
2421.45
967.62
Population'*'
in Area
12,250
40,250
12,750
Receiving
Stream
Intrenchment Creek
Intrenchment Creek
North Branch of
South River
4518.09 65,250
*• 'Based on population estimates for census tracts and tract zones, and population distribution studies by
ARMPC (Atlanta Region Metropolitan Planning Commission).
Approximately 2,400 feet downstream of the McDaniel Street overflow, at the Joyland Park
area, a smaller (66—inch diameter) combined sewer also discharges in to the north branch. It
serves a total drainage area of approximately 194 acres. This is not considered a major
overflow, however, since a separate system serves the largest fraction of the drainage area
and sanitary sewage from only a small part of it enters the combined sewer trunk.
Confederate Avenue Overflow
The major combined sewer discharging south of Confederate Avenue is also known as
Stockade Trunk and Lester Street sewer. It consists of a 10' x 10' concrete arch cross
47
-------
^RyVp^ r-^ }|f I^VrHfWwi li&WS ft , _Y !W I
k^^^^^t" Jl>-'^W^=4w;RES'ljlJ'.AR-R{ L^V^'A^^'^ ~^-A l\\s
OTd ',.•• ».^^"^l^^i^ltinii! N^\P^rtf^vT^^^TT;iV''
^^ATl 'CQNFEDERATr^VE. O^RFLO^^^^^^RHtLV^^OUj I/,-, flfA
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^
A 2
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• e •
CONFEDERAT'E*
BOULEVARD
McDANII
CONTRII
t
SOUTH RIVER BASIN BOUNDARY!
LX
*V.
ir
• I ,-" 1 ^o' -! I' f *.»-^ : j J ^ :4>
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r-r
RIVER
BASIN
MAJOR
COMBINED SEWER OVERFLOWS
48
Figure 14
-------
section with an almost flat, V-shaped concrete bottom. Center line elevation of the bottom
slab is approximately 6 inches lower than the sides. Steep longitudinal slopes in this sewer
induce considerable velocities, especially at high flow conditions. Maximum recorded
velocity at this station was 15 feet per second. Slopes vary from section to section. A total
fall of 28.3 feet takes place in the last 4,130 feet of the sewer. The straight section ending at
the overflow point falls 3.0 feet in a length of 630 feet, for a slope of 0.476 percent.
Details of this sewer at the regulator device can be seen in Figures 15 and 16. Separation of
dry weather flows is obtained by means of an opening on the side wall of the sewer, a
depressed area in the bottom in front of the opening, and a small weir or dam across the
sewer just downstream of it. Entrance to the interceptor is protected by a bar screen located
outside and adjacent to the sewer on the east side. The bar screen is installed within an open
pit having concrete bottom and brick walls. The first section of the interceptor, only 31 feet
long, is made of 20—inch diameter vitrified clay pipe. At the first manhole a change to
27—inch diameter concrete pipe takes place. At a second manhole, located only 29 feet
downstream, diameter increases to 30 inches. The interceptor flows south on the east side of
the stream for approximately 2,200 feet, until it meets the Intrenchment Creek interceptor.
Boulevard Overflow
At the location of the regulator device, the Boulevard combined sewer consists of a double
9' x 13' rectangular sewer, built of reinforced concrete. The regulator consists of a
4—foot—wide, semicircular bottom trough extending from side to side of the combined
sewer in a direction perpendicular to the flow, and protected by a full—width bar screen. A
concrete dam or weir is located on the downstream side of the bar screen to intercept dry
weather flows, as can be seen in Figure 17. Crest of this weir is about one foot higher than
the top of the bar screen. Below this point the main sewer has been extended 212 feet to
the point of discharge, where Intrenchment Creek begins.
The interceptor originating at the regulator device is known as the Intrenchment Creek
interceptor. Construction plans for this structure are dated 1913, and call for a 48—inch
vitrified clay pipe beginning at the regulator. This pipe curves rapidly to parallel the creek
on the north side. The interceptor receives large amounts of grit, requiring frequent cleaning
through an adjacent brick structure constructed later. Inspection of the first three manholes
downstream of this structure indicated large grit accumulation such that only three feet of
interceptor depth were available for flow. A reverse bottom slope exists between the brick
structure and the first three manholes. Separate sanitary sewers enter the Intrenchment
Creek interceptor throughout its route. About 2,300 feet downstream of the regulator it
receives the 30—inch diameter Confederate Avenue interceptor.
Photographs in Figure 18 show the present end of the sewer, where the creek originates, and
a flow level recorder installed in a manhole at the interceptor.
Longitudinal slopes vary along the double 9' x 13' section of the combined sewer. A total
fall of 12.5 feet takes place in a distance of 3,780 feet from the invert of the manhole
49
-------
SECTION "A-A
SCALE = 1" = 10'
I — ~^_
v,
_^^- —
V
87(
o
L
PLAN VIEW
SCALE : 1'= 10
6790
•793
BAR SCREEN
8719 879.7
20"VCP. INTERCEPTOR
SECTION "B-B'
SCALE : 1"= 10'
END VIEW
SCALE •• 1" = 10'
184.3
879.4
GENERAL DIMENSIONS
CONFEDERATE AVENUE
COMBINED SEWER
OVERFLOW
50
Figure 15
-------
Overflow
Samp I i ng
Regulator Device
and Bar Screen
at Interceptor
CONFEDERATE AVENUE
COMBINED SEWER
OVERFLOW
Overflow Point and Flow Level Recorder
51
Figure 16
-------
0 \
, i
t
073.0
*"\
^
^1
T
•^ k
;*'
'- 0"
lo
CH
r-<
I
t 1
n ^
INV)
869.3
3
•*•
A
i
TOP 885.0
BRICK
STRUCTURE
(GRIT REMOVAL)
-
J
' 1
i
\
?
INV-
867.5
SECTION "C-C
.A. SCREEN
973 °
CONC.WEIR
"B-B"
SCALE r-10'
GENERAL DIMENSIONS
BOULEVARD
COMBINED SEWER
OVERFLOW
52
Figure 17
-------
Overflow Point and Flow Level Recorder
BOULEVARD
COMBINED
SEWER
OVERFLOW
Flow Level Recorder in Manhole
at Interceptor
53
Figure 18
-------
located at Hill Street and the top of the bar screen structure at the regulator device. The
straight section just upstream of the regulator slopes at approximately 0.5 percent for a
length of 1,600 feet. The last section, extending 212 feet below the weir at the regulator,
slopes at 1.04 percent to the present point of discharge at the beginning of Intrenchment
Creek.
McDaniel Street Overflow
The McDaniel Street combined sewer has the smallest drainage area of the three major
overflows studied. At its present end it consists of a 16' x 16' concrete arch culvert running
for 170 feet under and across the tracks of the Atlanta and West Point Railroad. Two
combined sewers join to enter this section at its upstream end. One is an 8' x 8' box culvert
that comes from McDaniel Street, and slopes at 0.68 percent for the last 570 feet; the other
is a 6' x 6' arch sewer entering from the west, and averaging 0.72 percent slope over the last
2,340 feet. Two smaller storm sewers serving the adjacent area also enter the trunk at this
junction.
Dimensional drawings and photographs of the regulator and overflow appear in Figures 19,
20, and 21. The regulator consists of an opening broken through a concrete wall on one
side, and a raised bottom at the discharge end of the culvert. A slightly depressed area in
front of the wall opening facilitates entrance of dry weather flows to the interceptor.
A bar screen protects the interceptor from larger debris in the combined sewage. The
interceptor begins as a 20—inch pipe between the bar screen and an adjacent manhole. At
this point diameter is increased to 24 inches. It continues downstream along the northeast
side of the creek towards the South River treatment plant.
For convenience, overflow discharges from this sewer were measured at the 12' x 12' culvert
at Manford Road, located 250 feet downstream of the overflow point. This causes a slight
increase in tributary drainage area. Flows in the interceptor were also monitored at a
manhole on the center line of Manford Road, next to the culvert. It was not possible to find
additional manholes between this point and the south expressway, to verify invert elevations
for comparative flow estimation.
At the Manford Road manhole, surcharge has been observed to occur in the interceptor at
rather small wet weather flows.
Overflow Characteristics
Overflows at Confederate Avenue, Boulevard and McDaniel Street were monitored for
pollutant concentrations, as discussed in Section III. With a maximum of 24 bottles
available from the automatic sampler, collection intervals were vari d during the study
period. By manually activating the samplers, short intervals of one to five minutes were
54
-------
SECTION "A-A"
24" R.C.P. INTERCEPTOR ,' j J, I
v
917.75
932.50
ELEVATION
GENERAL DIMENSIONS
McDANIEL ST.
COMBINED SEWER
OVERFLOW
Figure 19
-------
Regula tor Dev i ce and
Bar Screen at Interceptor
Over fIow Point
McDANIEL STREET
COMBINED SEWER OVERFIOI
Gaging Station
Culvert Below Ove r f low Point
56
Figure
-------
Open ing on Side WaI I
Serving as Regulator
Samp I ing Dry Weather Flow
McDANIEL STREET
COMBINED SEWER OVERFLOW
Ba r Screen at Interceptor
57
Figure 21
-------
employed to define adequately concentrations near the beginning of overflows of some
storms. Longer intervals of fifteen minutes or more were used to cover the entire duration
of other storms.
Of the many parameters monitored, the most significant in its impact upon the environment
is biochemical oxygen demand (BOD). This parameter is therefore emphasized more
strongly than the others in subsequent discussions.
BOD in combined sewer overflows comes from three primary sources: normal dry weather
flow during the storm, overland storm drainage, and BOD in the system at the beginning of
storm runoff, including settled solids. In the South River Basin, City of Atlanta, the last
component is forced out of the system in front of the storm runoff, causing high initial
BOD's that decay with time as the whole system becomes tributary to the point of
overflow. During the remainder of the overflow, BOD concentrations vary inversely with
flow rate, indicating dilution with sewage flow entering the system. BOD from the storm
drainage component and from areas served by storm sewers varies directly with flow rate.
These relationships are illustrated for two storms in Figures 22 and 23.
The extensive BOD data were analyzed to separate the three primary components. The wide
variations from one storm to the next in recorded BOD concentrations during the dilution
phase of overflows indicate the effects of many factors, including overflow rate, the
duration of preceding dry weather period, the precision of laboratory analyses and sewage
flow rate at the time of overflow. The last factor is very significant since the storm flows
dilute dry weather sewage flows to yield the overflow BOD concentration. Hourly and daily
dry weather sewage flow variations at the interceptors were monitored during the study and
were utilized in conjunction with monthly sewage treatment plant records to obtain
multiplication factors by means of which dry weather sewage flows at any time during the
year could be compared to those occurring during an average hour of the year. With these
multiplication factors, recorded BOD concentrations during overflows were adjusted to
values that would have been obtained during an average hour of the year. This procedure
was followed in order to improve the validity of equations relating BOD to overflow rate,
without specific consideration of the time of year. The equations can be utilized to estimate
BOD concentrations and pollution loads from storms occurring at particular times of the
year by multiplying with the appropriate factor.
All BOD values were screened in order to separate high concentrations occurring at the
beginning of overflows due to scouring of solids. Concentrations due to storm runoff alone,
as determined from data at Station 5, Caspian Street, were subtracted from the data in order
to leave a residual concentration attributable to dilution of influent dry weather flow. A
regression analysis was then performed to determine the relationship between this
concentration and flow rate. The results are shown in Table 5 as follows:
58
-------
Ul
vo
C
h
(D
to
-------
n
(D
10
CO
-------
TABLE 5
Station
Number
1
2
3
Station
Designation
Confederate Ave
Boulevard
McDaniel St
Boulevard: BOD
Number of
Overflows
32
97
97
= 123.90-
F
01.11
24.55
23.44
30.09 log! c
r2
0.034
0.205
0.198
, FLOW
Statistical Significance
None(* )
.995+
.995+
(cfs)
McDaniel St: BOD = 105.73 - 33.12 logj 0 FLOW (cfs)
(1) Destruction of a control weir at Confederate Avenue early in the study limited the relia-
bility of subsequent high flow data at this station.
These equations permit estimation of the BOD component due to sanitary sewage entering
the system during the overflow. Their statistical significance is quite strong, although the
correlation coefficients, r, are not high. The resulting predicted concentrations are good
estimates of average values occurring during the year, although specific storms may yield
wide variations around these averages. Detailed analysis of the data at McDaniel Street
indicated that adjustment of BOD concentrations, as described above, increased the variance
accounted for at that station from 11.1 percent to 19.8 percent. Residual variance may be
attributed to many factors, among which may be included the accuracy of the BOD test,
accuracy of the rating curves at high flow rates, possible sampling bias, and length of the
preceding dry weather period.
The components due to storm runoff and sanitary sewage, both of which are functions of
flow rate, were subtracted from the record to leave a time—dependent residual at the
beginning of each overflow. Insufficient usable data were available to analyze the
relationship rigorously at each station. Consequently readings at all three stations were
combined and linear regressions were fitted visually, as shown in Figure 24. Each line
denotes an approximate trend evident in BOD concentrations in the flow range specified,
the flow rates being shown beside each data point. For flows during the initial phase of less
than 50 cfs, about 75 minutes are required to completely scour the combined sewer system
and to remove all settled solids. By contrast, intense storms yielding initial flows greater
than 200 cfs scour the system in approximately nine minutes. During this time BOD values
are higher than would be possible from dilution of influent sewage alone. Peak
concentrations of approximately 500 mg/1 adjusted BOD occur at the beginning of
overflows. Actual recorded values are higher, reflecting components due to storm runoff and
influent sewage dilution. Concentrations decrease with time until the system is scoured,
after which the latter two components predominate. Relatively high sewer slopes and low
61
-------
62
Figure 24
-------
interceptor capacities are considered to cause these high BOD concentrations during the first
few minutes of overflows. For a given flow rate, the decrease is assumed to be a linear
function of time, although further data would clarify the nature of the relationship, whether
linear or exponential. Table 6 shows the coefficients in the equation for each flow rate,
equations being of the form:
BOD - 500 - At t < B
TABLE 6
Coefficients for Various Flow Ranges — Initial BOD Equation
Flow Range (cfs) A B(Minutes)
0-50
50-100
100-200
200-over
6.67
11.10
16.67
55.60
75
45
30
9
Pollution Load From Overflows
The BOD equations were incorporated into the runoff calculation computer program as a
subroutine, as described previously in Section IV. This enabled estimation of concentrations
and total pollution loads in each time increment of runoff resulting from application of each
of the synthetic storms. Results for areas 2 and 3, Boulevard and McDaniel Streets, are
shown in Figure 25. The relationship between total pounds of BOD and rainfall duration for
storms of stated recurrence intervals indicates clearly the pollution severity of low
frequency storms. However, when each curve is weighted by the number of expected
occurrences per year, the great importance of high frequency storms becomes apparent, as
shown for station 2, Boulevard, in Figure 26. These high frequency curves, especially the
two— and four—week curves, should be considered conservative since they do not account
for the cumulative nature of specific rainfall frequencies. The curves indicate that adequate
treatment of small overflows from minor, frequent storms may significantly reduce the total
annual pollutional load upon the South River.
Comparison of the results from Boulevard and McDaniel Street overflows is shown in Table
7 and is included in Figure 27. Values at each station were adjusted to pounds BOD per acre
per hour of rainfall. Although discussion of these results is deferred until Section X, it may
be observed that the values for each area are quite similar.
63
-------
64
Figure 25
-------
H
Z!
BE
ON
±t±
5 10 15
RAINFALL DURATION (hours)
20
TOTAL ANNUAL BOD VS. RAINFALL DURATION FOR HIGH FREQUENCY STORMS
65 Fl<
igure 26
-------
en
UJ
C
-------
TABLE 7
Frequency
2 weeks
2 weeks
2 weeks
1 month
1 month
1 month
1 month
6 months
6 months
6 months
1 year
1 year
1 year
1 year
Duration
(hours)
1
2
5
1
2
5
10
2
5
10
2
5
10
20
Pounds
Boulevard
2.815
1.668
0.755
3.414
2.648
1.144
0.656
4.620
1.908
1.185
4.993
2.282
1.375
0.792
BOD/acre/hour of rainfall
McDaniel St
2.802
1.606
0.634
3.495
2.030
1.002
0.564
4.138
1.621
1.010
4.495
2.952
1.179
0.654
The figures of Table 7 were obtained from simulation of storms with peaks at one—quarter
of the duration, and are considered to be reasonable estimates of combined sewer pollution
in the study area. To determine the effect of rainfall distribution on the results, the series
was rerun with the peaks at three—quarters of the duration. For both combined sewer areas
the difference in total pounds of BOD was less than four percent, with the early runoff peak
producing consistently higher results. It was concluded that for a given area the time
distribution of rainfall during a typical storm of a given frequency and duration has little
effect on the pollution load from that storm.
Slight irregularities in the smoothness of the curves in Figures 25 and 26 may be attributed
partly to small sample error in the calculation of the rainfall intensity-duration-frequency
curves of Figure 7. A longer record would have increased the definition of the curves,
particularly at the extremes. However, the extra effort involved was not considered to be
justified for the purposes of this investigation, since already well-defined high frequency
storms are of primary interest in combined sewer studies.
Available treatment methods for combined sewer overflows, to be discussed later, include
the storage and subsequent treatment of all, or part of, the runoff. For this reason the time
variation of BOD loading at each overflow point was determined for storms having peaks at
67
-------
one—quarter of the duration. The relationship between cumulative runoff volume and
percent of total BOD load is shown in Figures 28 and 29. The figures may also be
interpreted as percent of overflow BOD stored in reservoirs of given volume for storms of
varying frequency and duration characteristics.
Figure 28 includes combined overflow from stations 1 and 2, Confederate Avenue and
Boulevard. Both discharge into Intrenchment Creek, their point of confluence forming the
site of a possible reservoir. Rainfall and runoff data for the subbasin contributing to the
Confederate Avenue overflow were insufficient to define adequately the pollution
characteristics of that area. Since the two areas are adjacent and land uses are very similar,
total runoff and BOD were assumed to be directly proportional to basin area such that the
combined runoff was 1.4 times the runoff from station 2 alone. During the storm the time
distribution of BOD from stations 1 and 2 is assumed to be identical, although BOD from
station 1 tends to be higher, due to the character of the industrial wastes entering the
system in this area.
Results indicate that a reservoir at the Intrenchment Creek site storing 1.8 million cubic feet
would contain 100 percent of the overflows from storms occurring with frequency greater
than, or equal to, two weeks as well as 60 to 80 percent of BOD from one-month storms.
Increasing the storage to 3.4 million cubic feet allows containment of overflow from all
one—month storms as well as 40 to 50 percent of six—month and one—year storms.
Similarly for the area contributing to station 3, the McDaniel Street overflow, storage of 0.5
million cubic feet will allow containment of 100 percent of the overflow BOD from all
two-week storms as shown in Figure 29. It will also contain 55 to 90 percent of the
overflow from all one—month storms and 25 to 40 percent of overflow BOD from one—year
storms.
The significance of these results becomes apparent after consideration of Figure 10
discussed in Section IV. The approximate location on this graph of a two—week, a
one—month, and a six—month storm was determined by averaging the locations found by
two procedures. In the first procedure the two—week storm was located by finding that
rainfall volume exceeded by 25 storms during the year. In the second procedure it was
located by determining the volume of rainfall from the storm of average duration for the
given frequency.
Consideration of a longer period of record would improve confidence in the location of the
six-month storm in this figure. However, such precision on relatively low frequency storms
was not necessary for this study. Of 118 storms occurring in 1969, approximately 57
percent were of higher frequency than two weeks. It may be concluded that a large
percentage of the total annual BOD from combined sewers is due to storms with frequency
greater than, or equal to, two weeks. Data for 1969 indicated that this is about 57 percent.
While total annual BOD is an important criterion of combined sewer pollution, the shock
loading placed on receiving waters due to a single storm is of greater importance. The
68
-------
9.0-1
8. Q-\
CJ
CVI
6.0H
5. (H
3.
2. 0
i.oH
2-WEEK FREQUENCY
1-MONTH FREQUENCY
6-MONTH FREQUENCY
1-YEAR FREQUENCY
CTQ
e
N)
oo
LONG flURATI ON
SHORT PURA
30 40 50 60 70
PERCENT OF TOTAL BOD RETAINED BY STORAGE
RESERVOIR STORAGE OF BOD FROM BOULEVARD AND CONFEDERATE OVERFLOWS
100
-------
3 0
2.5-
2.0-
1.5-
CD
0°=
a
CO
1.0-
0.5-
2 WEEK FREQUENCY
MONTH FREQUENCY
6 MONTH FREQUENCY
YEAR FREQUENCY
LONG DURATION STORM
SHORT DURATION STORM
TJ
30 40 50 60 70
PERCENT OF TOTAL BOD RETAINED BY STORAGE
RESERVOIR STORAGE OF BOD FROM McDANIEL ST OVERFLOW
too
-------
relationship of this shock loading to storm frequency is discussed in Section XI,
CONDITIONS IN THE STREAM.
Consideration of Figures 7, 10, 27 and rainfall records for 1969 enabled calculation of the
estimated total annual BOD from combined sewer overflows in Atlanta. The estimated total
is 2,100,000 Ibs BOD/year, amounting to 460 Ibs BOD/acre/year. This value may be
compared to results of a study by Engineering-Science (1967) of combined sewer pollution
at Selby Street and Laguna Street in San Francisco. Values reported were 101 and 136 Ibs
BOD/acre/year respectively. Total annual rainfall for these areas is approximately
one—quarter of that for Atlanta.
To this total should be added an additional 920,000 Ibs/year bypassed at the treatment
plants, of which 675,000 Ibs/year are released from the Intrenchment Creek wastewater
treatment plant. Approximately three-quarters of this bypassing is caused by quality
deterioration of intercepted combined flows.
Reservoir storage of overflow from these storms would appear to be a feasible solution.
Offsetting the apparent simplicity of such a solutuion, however, is the bypassing procedure
presently followed by the sewage treatment plants in the study area. As discussed in Section
VII in greater detail, many intercepted storm flows are bypassed to the receiving stream due
to their low quality, particularly at the Intrenchment Creek sewage treatment plant.
Although overflows are caused by rainfalls as low as 0.01 inch, a large percentage of the
runoff from the high frequency storms is intercepted. Since small, frequent storms
constitute the major source of combined sewer pollution, interception and subsequent
bypassing of storm flows constitutes a significant restraint on the effectiveness of overflow
storage and treatment.
Variation of Physical and Chemical Parameters
At Combined Sewer Overflows
Total Suspended Solids (TSS)
Total suspended solids were observed to vary exponentially with flow rate at all three
overflow points. Statistical analysis substantiated the relationship
TSS = A(FLOW)B
and yielded the values for A and B listed in Table 8.
71
-------
TABLE 8
Station
Number
1
2
3
Station
Designation
Confederate Ave
Boulevard
McDaniel St
A
75.62
19.82
48.86
B
0.33075
0.56847
0.78482
r2
0.27
0.44
0.36
No. of
Storms
33
70
64
With peak flows occurring near the beginning of many recorded storms, it was not possible
to determine conclusively the existence of initially high values for total suspended solids at
the beginning of runoff events. Direct observation and some sample analyses indicate that an
initial effect may occur. However, the relationships above were utilized in this study to
predict total suspended solids loads from storms of different frequencies and durations in
the study area.
Results indicate that TSS discharged to the South River from combined sewers increases for
storms of lower frequencies. For any given frequency, TSS increases with decreasing
duration. For a one-year storm of two-hour duration, predicted peak concentrations were
1,000 mg/1 at Boulevard and 4,800 mg/1 at McDaniel Street. Total amounts discharged from
the Boulevard and McDaniel Street overflows are included in Table 9.
TABLE 9
Frequency
2 weeks
2 weeks
2 weeks
1 month
1 month
1 month
1 month
6 months
6 months
6 months
1 year
1 year
1 year
1 year
Duration
(hours)
1
2
5
1
2
5
10
2
5
10
2
5
10
20
Total Pounds
Boulevard
07.61
04.66
01.44
18.89
10.05
03.57
01.33
44.00
10.27
04.54
48.80
13.75
05.91
02.36
TSS/acre/hour of rainfall
McDaniel St
021.93
013.88
003.91
062.50
033.30
011.06
003.82
177.80
036.82
015.85
198.40
051.60
020.83
007.73
72
-------
The consistently larger amounts of TSS at the McDaniel Street overflow, approximately
three times amounts at the Boulevard overflow, are probably due to the lack of sufficient
data at high flow rates incorporated in the regression analysis. Results for Boulevard,
however, lie well within the range of data acquired during the study.
Volatile Suspended Solids (VSS)
The relationship between volatile suspended solids and total suspended solids is shown in
Table 10 for all three combined sewer overflows. Results indicate that VSS is approximately
30—50 percent of TSS during overflow events at these three stations. No further underlying
relationships were apparent in the data.
TABLE 10
Station
Number
1
2
3
Station
Designation
Confederate Ave
Boulevard
McDaniel St
No. of
Samples
53
68
71
Average
(VSS/TSS)
0.43
0.32
0.49
Standard
Deviation
0.16
0.16
0.24
Conductivity
Conductivities during dry weather flow were monitored at the three interceptors. Values
fluctuated during the day, reflecting directly the hourly variation in flow rate. Averages at
Confederate Avenue, Boulevard and McDaniel Street were 500, 450, and 700 micromhos
per centimeter (jumhos/cm) respectively, with fluctuations of less than 200 jumhos/cm.
Variation of conductivities during overflows is similar to the variation of BOD, although the
range of values is slightly dampened. Initially high values decrease with time at a rate
proportional to the flow rate, after which dilution of dry weather flow by the storm flow is
the primary factor. Data were insufficient to determine accurately the initial response of
conductivities during overflows. However, initial values appear to decrease from a maximum
of approximately 500 ^mhos/cm to steady-state values of approximately 100 to 300,
depending upon flow rate. The relationship between conductivity (C) and flow rate for the
Boulevard and McDaniel Street overflows is as follows:
Boulevard
(r=0.75)
McDaniel Street
(r=0.48)
C = 227.18 - 47.14 log! o (Flow)
C = 274.42 - 67.49 log! 0 (Flow)
73
-------
These relationships are statistically significant at the 99.95+ percent level.
pH
Recorded values for pH at all three overflow points do not differ appreciably from neutral
conditions. Confederate Avenue overflows were slightly on the basic side, with pH's ranging
from 7.0 to 10.0. Values at Boulevard ranged from 6.0 to 8.0. At McDaniel Street recorded
values ranged from 6.15 to 9.70, although the majority were between 6.5 and 8.0.
Acidity
Total acidities at the Confederate Avenue, Boulevard and McDaniel Street overflows
averaged 5, 12, and 7 mg/1 CaCO3 respectively. Although the quantity of data was limited at
the latter two monitoring stations, it is apparent that acidities are low. Further data would
be required to determine whether discharge of acidic industrial wastes is insignificant or is
well diluted by storm runoff.
Alkalinity
Alkalinity data at the three overflow points indicate that values at Confederate Avenue are
generally highest. When combined with the slightly basic pH's found at this station, this
implies that alkaline industrial waste discharges contribute to flows at Confederate Avenue,
yielding an average alkalinity of 66 mg/1 in overflows of less than five cfs. Average values of
30 and 34 mg/1 were recorded at Boulevard and McDaniel Streets, respectively, with
coefficients of variation ranging from 0.30 to 0.35 at all three stations.
Phosphate
Ortho phosphate concentrations at all three overflows showed no dependency upon time or
flow rate. Occasional high concentrations suggest intermittent discharge to the sewer system
of industrial wastes containing phosphate. Table 11 shows averages at the three stations, as
well as standard deviations and recorded maximum concentrations.
TABLE 11
Station
Confederate Ave
Boulevard
McDaniel St
No. of
Samples
67
81
99
Average PO4
(mg/1)
6.5
1.7
2.3
Standard
Deviation
5.1
1.3
2.8
Maximum
Concentration
25.6
06.2
12.3
74
-------
Of the three stations, Confederate Avenue yields the highest average and maximum
orthophosphate concentrations. Total phosphates were not determined at the combined
sewer monitoring stations.
Coliforms
Total conforms, fecal coliforms and fecal streptococci were determined during the study at
all monitoring stations except Confederate Avenue. Results at the remaining two combined
sewer overflow points are summarized below in Table 12. Analyses were performed with the
membrane filter technique.
TABLE 12
Geometric Mean (MPN/ml x 102)
Station
Boulevard
McDaniel Street
Number of Samples
21
21
Total
Coliform
1390
660
Fecal
Coliform
5
5
Fecal
Streptococci
11
4
Chemical Oxygen Demand (COD)
Analysis of the data to determine points where COD increased and BOD decreased, thereby
indicating toxic agents in the flow, was hampered by long sampling intervals, lack of
sequential COD/BOD pairs and wide variability in flow rates between consecutive samples.
An arbitrary maximum COD/BOD ratio of 5.0 was therefore selected, above which toxicity
was assumed to be present. Ten pairs of data were rejected by this criterion. A summary of
the remaining data for combined sewer overflows is shown in Table 13.
TABLE 13
COD/BOD Ratio
Station
Number
1
2
3
Station
Designation
Confederate Ave
Boulevard
McDaniel St
No. of
Samples
47
47
73
Avg
COD
442
164
286
297
Average
2.11
1.95
2.15
Standard
Deviation
0.73
1.24
1.20
Average 2.07
75
-------
Dissolved Oxygen (DO)
A small number of samples from the Boulevard and McDaniel Street overflows were tested
for dissolved oxygen. Averages were 7.9 and 9.2 mg/1, respectively. Determination of the
percent of saturation concentration for each sample was not possible. However, the average
saturation concentration in the South River during 1968—1969 was 8.25 mg/1. It appears
probable, therefore, that dissolved oxygen in combined sewer overflows is at saturation
concentration. This indicates that insufficient flow time has elapsed for biochemical
reaction to occur in the combined sewers. After discharge to the receiving stream, the
saturation level of DO is not maintained.
76
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SECTION VI
STORM WATER FLOWS
Sites Selected for Study
Three drainage areas within the upper South River basin were selected for study of storm
water quantity and quality. These areas are slightly different in land use and other
characteristics, but all are served by separate sanitary and storm sewer systems. Location of
the areas and corresponding monitoring sites can be seen in Figure 30.
A summary of general information on the three areas appears in Table 14.
TABLE 14
SITES SELECTED FOR STORM WATER
RUNOFF MONITORING
Station
Number
Station
Designation
Drainage
Area,
Acres
Estimated
Population in
Drainage Area
General
Information
Harlan Drive
954
Caspian Street
Federal Prison
Branch
517
1,498
9,250
3,750
7,250
(+ inmates)
Open stream receiving
runoff from indus-
trial and residential
areas
Stream originating
at storm sewers
Stream draining
reserved land, also
receives urban
runoff
77
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-., \ 5™——$.~ » r-o^:<
,.....,,.;>..,,.=i ,-,. -^.^i.-..^-.,^^ • •
i I iIL^Jft*: 2f(.>
":e^ QV S T ! T u T ! O'N
' '
UPPER SOUTH RIVER
DRAINAGE BASIN
STORM WATER RUNOFF
MONITORING SITES
SOUTH RIVER BASIN BOUNDARY1
Figure 31
-------
Station 4 is located on the south branch of South River. It utilizes an existing U.S.
Geological Survey installation established in October, 1963, as a continuous recording
station for the river's headwaters. The level recorder is installed upstream of the culvert on
Harlan Drive in the City of East Point, Georgia.
The river falls approximately 100 feet in a distance of 1.5 miles down to this station. It
receives runoff from industrial and residential areas located mainly within the City of East
Point, although about 12 percent of the drainage area falls within the corporate limits of
Hapeville. The stream at this station is usually clear at dry weather flows, but pollution
probably originating at chemical industries in the area was found to reach the stream
sometimes, producing sudden increases in the conductivity of its waters. Peak discharges
observed during the few years of record have exceeded 800 cubic feet per second (cfs) at
this station. Flows of over 600 cfs were recorded four times during the present study.
Station 5 is located on one of the two streams that form the middle branch of South River.
These two streams merge just above the culvert at Stewart Avenue. The gaging station was
established on the stream entering from the north, on the downstream side of the culvert at
Caspian Street and can be seen in Figure 31. At the present time the headwaters of this
stream consist entirely of the storm sewer system serving the area, and the open stream
originates on the south side of Deckner Avenue at the end of a 6—foot arch brick storm
sewer. A short distance downstream two 42—inch storm sewers contribute additional flows
to the stream from the west side of the area.
The stream runs in the open for 3,400 feet through the Perkerson Park area, and falls 57
feet in this distance before reaching the culvert at Caspian Street, where the gaging and
sampling station was established.
Station 6 is located on Federal Prison branch, a tributary entering South River from the
north approximately 4,700 feet downstream of the Jonesboro Road bridge. The gaging
station was installed downstream of the culvert on South River Industrial Boulevard, as
shown in Figure 31.
This stream was selected mainly because, although its drainage area is still located entirely
within the upper South River basin, land uses in part of it, at least, are rather different than
for the preceding two streams. All of the reservation surrounding the prison, most of it
sloping open land, falls within the drainage area. In contrast, most of the land in the other
areas selected for study is highly developed.
The longest branch of this stream, flowing in a northwest-southeast direction, runs
overland for a distance of 2.5 miles, from the end of the 6' x 6' arch culvert at Sawtell
Avenue, before reaching the gaging station. A total fall of 140 feet takes place in this
distance. Upstream of Sawtell Avenue most of the area is served by a separate sewer system.
Storm sewers from this area end with a 72-inch diameter concrete pipe that discharges into
the culvert at Sawtell Avenue.
79
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Flow Level Recording Station at Caspian Street
Tributary to Middle Branch of South River.
Flow Level Recording Station at South River Industrial Boulevard
Fede ra I Pr i son Branch
80
Figure 31
-------
The drainage area of the Federal Prison branch is long and narrow, as opposed to the other
two areas studied.
A small ponding area exists three—quarters of a mile downstream of Sawtell Avenue. A weir
controls outflow from the pond, producing some flow regulation.
Federal Prison branch receives eventual discharges of raw sanitary sewage, when the
Constitution Road pumping station fails to operate and overflows into the stream.
Deterioration of the stream due to these discharges was noticed at least once during the
study at the sampling station on South River Industrial Boulevard.
Flow Characteristics
Stations 4, 5, and 6 maintain small dry weather flows throughout the year, showing some
seasonal variation. Approximate average annual values of these base flows are shown in
Table 15, along with corresponding values at stations 7 and 8 on the South River at
Jonesboro Road and Bouldercrest Road.
TABLE 15
Station
Number
4
5
6
7
8
Contributory
Area
(square miles)
1.49
0.79
2.34
15.52
41.50
Approximate
Base Flow
(cfs)
3.6
1.8
1.9
2.8
41.0
Cubic Feet per Second
per Square Mile
2.42
2.28
0.81
1.80
0.99
Stations 1, 2 and 3 are excluded from consideration since any base flow is combined with
sewage and intercepted. Flows at station 8 represent the fraction remaining after removal of
sewage treatment plant average annual flows.
Although the source is uncertain, average base flow is 1.66 cubic feet per second per square
mile. Seasonal variation of the base flow implies that ground storage of rainfall occurs,
although this is undoubtedly inhibited by the presence of clay and other impervious
materials throughout the Atlanta area. The base flow may be attributed, therefore, to a
combination of ground storage and flow from springs occurring in the area. Base flow at
Harlan Drive is periodically augmented by industrial wastewater from cleaning operations.
81
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BOD's of the base flow at stations 5 and 6 averaged 17 and 18 mg/1, respectively. Data were
insufficient at station 4. Calculation of BOD's during storm flows was hampered by a lack of
high flow rate observations at station 6. The relationship between BOD concentration and
flow at station 5 was calculated as follows:
BOD = 29.2 + 8.28 log! „ FLOW (cfs)
F = 4.84
r = 0.287
n = 56
The regression equation is statistically valid, although the correlation coefficient is low.
Although this equation was used in all computations, it is believed that further data at high
flow rates would increase the value of the flow coefficient above 8.28.
Pollution Load from Storm Sewer Runoff
The subbasin contributing to station 5, Caspian Street, was selected for detailed study to
determine pollution characteristics of a storm sewer area. Calculation of pollution
concentrations in the runoff resulting from application of the synthetic storms, as described
in Section IV, yielded the values listed in Table 16.
TABLE 16
Frequency
2 weeks
2 weeks
2 weeks
1 month
1 month
1 month
1 month
6 months
6 months
6 months
1 year
1 year
1 year
1 year
Duration
(hours)
1
2
5
1
2
5
10
2
5
10
2
5
10
20
Pounds BOD/acre— hour
of rainfall
1.149
0.770
0.334
2.187
1.320
0.634
0.318
3.664
1.279
0.730
3.940
1.580
0.892
0.465
82
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Comparison of the above results with those listed in Table 7 for combined sewer overflows
is shown in Figure 27, which shows that for storms of two— and four—week frequency,
BOD loads from storm sewers are approximately half those of combined sewers. For less
frequent storms, BOD loads approach three—quarters of those from combined sewers. The
difference is minimized for short, intense storms. The annual average pollution from an acre
served by storm sewers is estimated at 55 percent of that from a similar area served by
combined sewers.
BOD loads from both storm shapes were calculated, confirming the observation of Section
V that the time distribution of rainfall during a storm has little effect on the pollution load
from that storm.
Variation of Physical and Chemical Parameters
In Storm Sewers
Total Suspended Solids (TSS)
Acquisition of TSS data at Harlan Drive, Caspian Street, and the Federal Prison branch was
limited, necessitating determination of weighted average concentrations for dry weather
flow. This average was calculated to be 75 mg/1. Dry weather flow in the storm sewers was
very small.
TSS concentrations during storm runoff at the three stations were combined and an
exponential equation was fitted to the data. The equation
TSS - S.OOCFLOWCcfs))1-225
indicates a sharper response of TSS to flow than for the combined sewer areas, probably due
to the lack of significant base flow. Since this equation does not apply specifically to station
5, Caspian Street, no attempt was made to determine pounds TSS per acre per hour of
rainfall at this station.
Volatile Suspended Solids (VSS)
The relationship between volatile suspended solids and total suspended solids is shown in
Table 17 for all three storm sewer monitoring stations, and may be compared with values
tabulated in Table 10 of Section V. Results indicate that VSS is approximately 20 to 40
percent of TSS during runoff events at these three stations. This is 10 percent less than for
combined sewer overflows.
83
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TABLE 17
Station
Number
4
5
6
Station
Designation
Harlan Drive
Caspian Street
Federal Prison
No. of
Samples
8
38
21
Average
(VSS/TSS)
0.40
0.34
0.21
Standard
Deviation
0.16
0.20
0.14
Conductivity
Conductivities were recorded at station 4, Harlan Drive, for dry weather flow, yielding an
average of 518 jumhos/cm with a standard deviation of 58. The high value is due to discharge
of industrial wastes from Tennessee Corporation, Owens, Illinois, and other industries in the
area. Lower conductivities were recorded at Caspian Street and Federal Prison branch,
averaging 153 and 160 ^mhos/cm, respectively, with low standard deviations. Both averages
were for dry weather and low flows.
pH
The effect of industrial waste discharges upon pH at station 4, Harlan Drive, was apparent
from the 4.6 to 6.3 range recorded during the study. Discharge of oxalic acid by the
Tennessee Corporation may cause these low pH values. Neutral averages were recorded at
Caspian Street and Federal Prison branch.
Acidity
Acidity at Harlan Drive averaged 111 mg/1 CaCO3, whereas values at Caspian and Federal
Prison branch averaged 6 mg/1 CaCO3. When combined with conductivity and pH averages,
the high value at Harlan substantiates conclusions concerning industrial pollution in the
stream.
Alkalinity
Alkalinities at Harlan Drive, Caspian Street, and Federal Prison branch averaged 14, 80, and
43 mg/1, respectively. Occasional high values at Caspian Street reflected in a standard
deviation of 80 mg/1 indicate the possible intermittent discharge of alkaline industrial wastes
in that area.
84
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Phosphate
Average orthophosphate concentrations at the three storm sewer monitoring points are
shown in Table 18. As in combined sewer overflows, standard deviations are high, although
the averages are low. Total phosphates were not performed at these stations.
TABLE 18
Station
Harlan Dr
Caspian St
Federal Prison
Branch
No. of
Samples
16
59
55
Average
PO4
mg/1
0.4
0.3
1.6
Standard
Deviation
0.6
0.3
1.6
Maximum
Concentration
mg/1
1.9
1.6
5.7
Coliforms
After analysis, coliform data proved inadequate to justify conclusions concerning coliform
concentrations at storm sewer monitoring stations.
Chemical Oxygen Demand (COD)
COD/BOD ratios in all three storm sewers were higher than in combined sewer overflows. It
was not possible to detect toxicity in the data, so all observations were included in the
analysis, which is summarized in Table 19. The majority of observations were at dry weather
or low flows.
TABLE 19
COD/BOD Ratio
Station
Harlan Dr
Caspian St
Federal Prison
Branch
Average
No. of
Samples
13
38
27
Average
COD
28
84
67
60
Average
4.00
4.20
2.60
3.60
Standard
Deviation
1.8
2.9
1.5
85
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Dissolved Oxygen (DO)
Averages of the values recorded at Harlan Drive, Caspian Street, and Federal Prison branch
were 6.6, 9.0, and 5.6 mg/1, respectively. The samples from which these averages were
obtained were small, thereby limiting reliability of conclusions concerning dissolved oxygen
at storm sewer monitoring stations. However, these values are generally less than the annual
average saturation concentration of 8.25 mg/1.
Comparison of Pollution Indices
for Storm and Combined Sewer Areas
Table 20 summarizes physical, chemical and bacteriological analyses of storm flows from
areas served by separate and combined sewers.
TABLE 20
Water
Quality
Parameter
COD/BOD Ratio
VSS/TSS Ratio
Conductivity
Omhos/cm)
PH
Acidity
(mg/lCaC03)
Alkalinity
(mg/lCaC03)
Orthophosphate
(mg/1)
Dissolved Oxygen
(mg/1)
Total Coliform
(MPN/mlx 10*)
Fecal Coliform
(MPN/mlx 102)
Fecal Streptococci
AVERAGE CONCENTRATION
Combined Sewer
1 2
2.11 1.95
0.43 0.32
500 450
8.5 7.0
5 12
66 30
6.5 1.7
7.9
1,390
5
11
Area
3
2.15
0.49
700
7.2
7
34
2.3
9.2
660
5
4
Storm Sewer Area
4
4.00
0.40
518
5.4
111
14
0.4
6.6
—
—
5
4.20
0.34
153
7.0
6
80
0.3
9.0
—
—
2
6
2.60
0.21
160
7.0
6
43
1.6
5.6
—
—
(MPN/mlx 102)
86
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SECTION VII
WASTEWATER TREATMENT PLANTS
Normal Operation
The City of Atlanta owns and operates two wastewater treatment plants within the South
River basin. The South River plant is made up of two adjacent treatment facilities operating
in parallel, one employing trickling filters and the other diffused air for secondary
treatment. Intrenchment Creek plant, owned also by the City, is a high rate trickling
filtration facility. Both plants receive sewage contributions from areas served by combined
sewers, as well as from areas having separate storm and sanitary systems. Normal operation
of these plants is based on treatment of dry weather flows only. Wet weather flows are
generally bypassed to prevent overloading of the units and difficulties with the large
amounts of grit that would otherwise reach the digesters.
The fraction of combined sewer flows diverted to the treatment plants at interception
points is augmented by additional sewage from separate systems before reaching its
destination. Substantial increases in flow along the interceptor lines occur during storms.
However, the primary cause of bypassing at the treatment plants is not the flow increase,
but the poor quality.
The intercepted combined flows contain grease, grit and mud. Bypassing of all flows in the
intercepted lines is necessary in order to prevent the grit from reaching the digesters. Grit
enters the system from a number of sources, primary among which is the bypassing
procedure utilized to separate mud from water treatment plant influent. This practice has
recently been curtailed. Other sources include application of light gravel to highways during
infrequent snowfalls, and construction activity within the City.
Due to the additional sewage flow carried by the interceptors, bypassing of intercepted
flows at the wastewater treatment plants is more significant than discharge of the same
flows at the interception points. Understanding of the fundamental difference between the
two is important for understanding the remainder of the report.
The Intrenchment Creek treatment plant receives its inflow from two primary trunk sewers.
One of these, the Intrenchment Creek interceptor, serves 46% of the area. It carries flow
from the Boulevard and Confederate Avenue interceptors augmented by sewage from an
additional 20% of the area served by the treatment plant. As shown in Figure 32, this
interceptor is bypassed very frequently, averaging 52 hours per month during 1969.
Condition of the waste was the reason for almost every bypass event. Simultaneous
bypassing of flows from both the Intrenchment Creek interceptor and the Sugar Creek
trunk sewer occurred an average of eight hours per month during 1969. The Sugar Creek
trunk sewer does not carry flows from combined sewer areas.
87
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TOTAL HOURS WHEN WASTEWATER TREATMENT PLANTS WERE BYPASSED
oo
oo
C
K
JJJBM
1969 JANUARY FEBRUARY
•KPT EMBER
TOTAL BYPASS HOUR* IN MONTH
REASON FOR BYPASSING:
I \ CONDITION Of WASTE
|J (Or«fli*,Siorm Water A Mud,
Industrial Watt*}
;l ^MECHANICAL A OTHER
OCTOBER NOVCMBCH DECEMBER 1969
BYPASSING RECORD
ATLANTA'S WASTEWATER TREATMENT PLANTS
WITHIN UPPER SOUTH RIVER BASIN
to
K>
-------
Bypassing at the South River wastewater treatment plant occurs less frequently, as shown in
Figure 32. The sewer carrying intercepted flow receives additional sewage from a large
fraction of the area served by the treatment plant. Therefore, the impact of each bypass
event is more severe, due to the higher fraction of sewage in the influent.
South River Wastewater Treatment Plant
The South River plant is located on the north side and almost within the flood plain of the
river, just downstream of Jonesboro Road (State Road 54). As stated before, it actually
consists of two adjacent plants operating in parallel, the older one utilizing standard rate
trickling filters for secondary treatment, and the more recent one employing a modified
activated sludge process. Sludge treatment for both plants is provided by a single group of
units.
An aerial view of the plant can be seen in Figure 33, while flow diagrams of the existing
treatment facilities appear in Figure 34.
The South River plant receives for treatment all sanitary sewage from most of the upper
south River drainage basin upstream of the Jonesboro Road (State Road 54) bridge, plus a
few smaller additional areas. A large part of the potential contributory area is completely
sewered at the present time, and altogether encompasses 26.09 square miles, with an
estimated population of 99,750. Additional areas contributing sewage include most of the
Federal Prison branch basin, a tributary entering the South River downstream of the plant.
Sanitary sewage from part of this area flows by gravity into the South River plant, while
part is pumped at the Constitution Road pumping station into the gravity system.
Most of the contributory area is served by a separate sewer system, combined sewers being
confined to approximately 2.07 square miles at the northwest end of the basin. This figure
is equivalent to only 7.9 percent of the total contributory area. Part of the sewers carrying
sanitary waste into the South River plant originate in areas within the cities of East Point
and Hapeville to the west, as well as in Clayton County to the south. Potential contributory
areas also extend into DeKalb County southeast of the plant.
The trickling filter plant is designed to treat an average flow of 6.0 mgd, while the modified
activated sludge plant has a design capacity of 12.0 mgd. Combined capacity of both is 18.0
mgd. An operating summary of these treatment facilities appears in Appendix C. Based on
these figures, for the twelve—month interval December, 1968 through November, 1969,
average daily flows entering both plants were 15.41 mgd, influent BOD's averaging 232
mg/1. Effluent BOD's averaged 40 mg/1 for this period and BOD discharged daily into the
stream was approximately 5,740 pounds.
From operating figures it appears that these two plants function at a rather high efficiency
and that bypassing is not frequent. However, total pollutional loads in the effluent are high,
annual mass discharge representing a large fraction of the total pollution entering the
stream.
89
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South Rivei Wastewater Treatment Plant
City of At lanta
•n
n
OJ
-------
FLOW DIAGRAM
PLANT "A" MODIFIED AERATION
FLOW DIAGRAM
PLANT "B" TRICKLING FILTRATION
FILTl* MNLDNM
FRGH PLANT "A'
FLOW DIAGRAM SLUDGE TREATMENT FACILITIES
FLOW DIAGRAMS
SOUTH RIVER
WASTEWATER
TREATMENT PLANT
CITY OF ATLANTA
91
Figure 34
-------
Average daily flows from the plant are as much as 10 times larger than the base flow in the
stream at the point of discharge. On the other hand, during large floods the stream may
carry as much as 100 times the average flow discharged by the plant.
Intrenchment Creek Wastewater Treatment Plant
This plant is located on a site adjacent to the creek just upstream of the Key Road bridge, in
DeKalb County. The location is approximately 2.1 miles downstream of the city limits,
measured along the stream, and 1.5 miles above the point where Intrenchment Creek enters
South River.
The plant presently receives sanitary sewage from an area of approximately 20.15 square
miles, with an estimated population of 115,750. About 37.8 percent of this area, on the east
side of the basin, is located in DeKalb County and outside Atlanta's city limits. Part of the
upper Sugar Creek basin is included in the contributory area, sewage reaching the plant
through the Sugar Creek trunk that cuts through the ridge separating this basin from the
adjacent Intrenchment Creek.
On the northwest, the area contributing sanitary sewage to the Intrenchment Creek plant is
served by combined sewer systems, including the Boulevard (Lloyd Street) and Confederate
Avenue (Stockade) trunks. These two systems encompass a majority of the combined sewers
within the South River basin. Altogether, they serve approximately 5.30 square miles,
representing 26.2 percent of the total area served by Intrenchment Creek plant.
The plant has a design capacity of 20.0 mgd and provides secondary treatment by means of
high rate trickling filters. Figure 35 is an aerial view of the plant, and Figure 36 is a flow
diagram. An operatingsummary for this plant during the interval December, 1968, through
November, 1969, appears in Appendix C. From available figures, average daily flows
entering the plant during this period were 13.29 mgd, with an average influent BOD of 368
mg/1. Effluent BOD's averaged 62.8 mg/1, and pollutional loads discharged into the stream
represent 8,800 pounds of BOD per day. The plant operates at a rather high efficiency for
the type of process employed. However, effluent BOD is very high, and need of bypassing is
rather frequent, mainly due to quality of the sewage in the Intrenchment Creek interceptor.
The combined sewer systems cover 56.6 percent of the area served by this interceptor. Need
for bypassing sewage from Sugar Creek trunk is not frequent, and storm water is reported to
reach this trunk only during very heavy rains.
Intrenchment Creek, which receives the effluent and bypasses from this plant, originates at
the two major combined sewer overflow points within the basin. Drainage area down to the
plant is only 9.9 square miles, average daily effluent volumes from the plant exceeding dry
weather flows on the creek at this point.
At the confluence point, dry weather flows in both Intrenchment Creek and South River
consist chiefly of wastewater treatment plant effluents. Control Station No. 8 of the study
92
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Intrenchment Croek Wastewater Treatment Plant
City o\ Atlanta
c
>-t
n
-------
SUGAR CREEK TRUNK
FLOW D I AGRAM
INTRENCHMENT CREEK
WASTEWATER TREATMENT PLANT
CITY OF ATLANTA
94
Figure 36
-------
is located 1.1 miles below this point, at the Bouldercrest Road bridge. At this station
conditions in the river are most critical. Dry weather flow records at Bouldercrest clearly
reflect hourly flow variations in plant effluents.
Other Treatment Facilities
A few more wastewater treatment plants contribute additional pollution to South River
between Bouldercrest and the Klondike Road bridge. DeKalb County owns and operates
two secondary treatment plants within the basin. The Shoal Creek plant, located upstream
of the 1-285 bridge at this stream, is a standard rate trickling filter facility with a design
capacity of 2.0 mgd. Flows averaged 2.62 mgd during 1969, with an estimated BOD
discharge of 962 pounds per day to the stream. The Snapfinger Creek plant, located on the
north side of South River just below the Flakes Mill Road bridge, is a high rate trickling
filter facility with a design capacity of 3.0 mgd. It is presently being enlarged to a capacity
of 6.0 mgd. Average flows received during 1969 were 2.49 mgd, with estimated daily
discharge of 1,095 pounds BOD to the South River. A summary of operating data for these
two plants is included in Appendix C. Within the Snapfinger Creek basin is a waste
treatment lagoon serving part of Stone Mountain. Effluent enters Barbashela Creek, a
tributary within the basin.
Long range plans for the Metropolitan Atlanta area consider future abandonment of Shoal
Creek and other existing treatment plants upstream, and gravity conveyance of wastes from
all the upper basin and the Stone Mountain area into the present Snapfinger Creek plant
location, for treatment at a larger, more efficient facility.
The Panola industrial area, located within the Pole Bridge Creek basin, is presently served by
an extended aeration plant just north of Rock Springs Road. Pole Bridge Creek enters South
River from the north about a mile upstream of Klondike Road. Conley Creek, a tributary
entering from the south, receives at its headwaters effluent from the reatment facility at
the Atlanta Army Depot. From available records for the interval October, 1968, to
September, 1969, average daily flows at this plant were 0.305 mgd, while BOD's averaged
220 mg/1 in the influent and 8.5 mg/1 in the effluent.
Also within the upper basin, in Clayton County, is the Rock Cut Road System, presently
utilizing an aerated lagoon for treatment of wastes. At least four more smaller treatment
facilities are known to exist in DeKalb County, on the south side of the basin, upstream of
Snapfinger Creek plant location.
Pollution Load From Wastewater Treatment Plants
The average daily pollution load upon the South River from the Intrenchment Creek and
South River wastewater treatment plants is 14,540 pounds BOD. Bypassing procedures at
each of the plants, although intermittent, add an average of 2,520 pounds per day or 17
percent of the treated effluent pollution load. However, bypassing does not occur on a daily
95
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basis, so the effect upon the South River is far more pronounced when it does occur, as
discussed in Section X.
Bypassing of flows from both the Intrenchment Creek interceptor and the Sugar Creek
trunk adds approximately 1,850 pounds BOD per day to the 8,800 discharged as treated
effluent at the Intrenchment Creek wastewater treatment plant, amounting to an increase of
21 percent. Bypassed flows from both sections of the South River wastewater treament
plant add 670 pounds BOD per day to the 5,740 discharged as treated effluent, yielding an
increase of 12 percent.
As an intrastate stream, the South River does not fall under federal water quality standards.
State standards have been established however. The content of these standards and the
reduction in pollution load required to attain them is discussed in Section XI,
CONDITIONS IN THE STREAM.
96
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SECTION VIH
OTHER SOURCES OF POLLUTION
Overflows from Temporarily
Inoperative Pumping Stations
Topographic conditions in the upper South River basin are such that sanitary flows from
practically all areas within its boundaries can reach the treatment plants by gravity.
However, two pumping stations exist and are operated within the basin. One of them,
known as Constitution Road pumping station, receives sewage from a drainage area of about
408 acres within the basin of the Federal Prison branch. The Constitution Road pumping
station discharges through an 8-inch force main into the 21-inch Federal Prison outfall
that flows into South River plant.
The second pumping station is located at Jonesboro Road within the site of the South River
treatment plant itself. Purpose of this station is to lift part of the sewage that arrives at the
plant from the south and southwest at a lower elevation, to the higher elevation of the
42—inch South River sewer entering from the northwest. Sewage requiring pumping arrives
through the Bromack Drive, Hapeville, and Jonesboro Road (south) outfalls.
When the Constitution Road pumping station becomes inoperative, bypassed raw sewage is
discharged into Federal Prison branch at a point about 3,500 feet upstream of its confluence
with South River.
No records were kept by the City on times when bypassing of this pumping station occurred
during 1969. The pumping station at Jonesboro Road experienced mechanical trouble from
January 13 to March 7, 1969, causing a partial bypassing of flows arriving at the plant. It
operated uninterruptedly for the rest of the year.
Pollution From Industrial and Other Sources
A large number of industries are found within the upper South River basin, many of them
along the ridges that establish the boundary, where most railroad tracks are located. Some
of these industries contribute untreated wastes to the system, while others provide
preliminary treatment of some kind before discharging them. It is the policy of the Atlanta
Metropolitan Sewer System that all industrial wastes be accepted into the sewers and
provided with further treatment after suitable pretreatment by industry.
A complete survey of the industrial waste situation within the basin is not feasible for this
study, due to the number and variety of industries involved, and complexity and variability
of some industrial processes. As a sample, a list for the McDaniel Street subbasin is included
in Appendix D. Information was obtained by field survey. Illegal discharges of wastes that
would have required pretreatment probably occur from time to time. It would be practically
impossible to find and assess many of these sources of pollution.
97
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Conductivity recordings as well as sampling and observation at some of the study stations
have shown eventual discharges of pollutants of unknown origin reaching the streams.
Identification of specific pollutants in the sewage and of possible sources has not been made
since it was not justified for the purpose of the study.
In a field survey of the headwaters of the south branch of the river it was concluded that
during heavy rains, overflow from certain holding ponds for pretreatment of industrial
wastes could possibly reach the stream. To ascertain conditions like these, specific
inspections would be required during storms.
Toxicity studies carried out on a number of samples taken at selected locations have
confirmed presence of toxic waste in variable concentrations. Variability of conditions is
such, however, that no quantitative statement can be made in connection with industrial
waste discharges.
Pollution from Sanitary Landfills
Fifteen landfills are found within the upper South River basin, but only one is presently
active. Location of these landfills appears in Figure 37. It can be noticed that most of them
are adjacent to streams.
The active landfill, located adjacent to the Confederate Avenue combined sewer overflow,
has been extended south on the west side of the sewer and along the open concrete canal
recently built at the overflow point. Natural ground at this location is composed mainly of
impervious clays and slopes gently in the direction of Intrenchment Creek. Both conditions
facilitate pollution from material in the landfill reaching the stream with storm runoff.
An assessment of pollution from this source has not been successful; however, it has been
observed that during heavy rains, surface runoff from the area carries clay and other finely
suspended materials into the stream. It might be expected that leachates from landfills
should also reach the stream under these conditions, contributing increased pollution loads
to the overflows. Stronger liquors from deeper fills have been found by other investigators
to contain amounts of BOD in the 2,000 to 4,000 mg/1 range. However, volume and
strength are highly dependent upon fill constituents, soil percolation, landfill construction,
and many other factors. At dry weather conditions, no seepage or flows from the landfill
have been observed to reach the canal or the creek. A significant amount of rainfall can be
expected to be absorbed by landfill materials before any leaching occurs.
Decrease of the quality of overflows due to contributions from this source is not easily
estimated. Grab sampling procedures are unsafe, due to the very high flow velocities in the
canal adjacent to the landfill and due to the lack of a suitable sampling point along the
banks of the canal. The latter constraint also limits use of an automatic sampling device.
Furthermore, observation of storm flows at the land fill site indicated that dilution of small
leachate volumes in these large flows would yield changes in water quality of so small a
magnitude that a separate, detailed study would be required to detect them. Personnel,
98
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SCALE
1"= 6000'
INACTIVE SANITARY LANDFILL
ACTIVE SANITARY LANDFILL f
V
UPPER SOUTH RIVER
DRAINAGE BASIN
LOCATION OF SANITAR
LANDFILLS
•••• SOUTH RIVER BASIN BOUNOAR
Figure 37
-------
equipment and financial contraints contributed to the necessity for omitting this separate
study, thereby permitting effort to remain focused on the primary goal of this report — an
assessment of combined sewer pollution.
Pesticides and Other Chemicals
Presence of chemicals, possibly pesticides, has been suspected at times by odor of water at
certain points in the stream. However, adequate determinations have not been performed,
since the laboratory was not set up for this type of analysis. It was not physically or
financially feasible to have pesticide determinations performed elsewhere within a
reasonable distance.
Contributions from Vacant Lots,
Agricultural Lands, Air Pollution
The percentage of vacant lands is practically zero in the north sections of the basin where
combined sewers exist, but becomes significant to the south, where development is still
taking place. Contributions from these sources must be assessed as a whole from conditions
at various stations on the stream for different flow regimes.
Downstream of Intrenchment Creek wastewater treatment plant, and adjacent to the
stream, is located the Atlanta Prison Farm.
Pollution from cattle, feed lots, agricultural uses, and other sources on this farm might add
to that reaching the stream, but conditions in this section are normally so critical that
isolation of individual pollution sources is extremely difficult.
It is known that rain scavenges air pollution. In a highly industrialized area, as is the case in
all of the upper South River basin, significant contributions can be expected to originate at
this source. Air pollution will add pollutants to storm water runoff and combined sewer
overflows. Assessment of this source in presence of many others is also an almost impossible
task.
Due to the difficulty of isolating pollution from such sources to determine the significance
of each, this study has included all such effects in the determination of equations for quality
of storm runoff and combined sewer overflows.
100
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SECTION IX
EFFECT OF ZONING AND LAND USES
ON POLLUTION LOADS
Zoning Regulations
Zoning regulations of the City of Atlanta establish twenty different zoning districts. District
uses and regulations appear on maps covering the corporate area to the scale of 1 inch equals
1,200 feet. These maps were utilized in the preliminary assessment of differences in land use
between drainage areas or subbasins that could be monitored for detailed study.
For simplicity in selection and correlation with pollution data, the City's zoning districts
were grouped into four general types for preliminary work. These types included low and
high density residential, industrial, and commercial districts. Each drainage subbasin selected
for pollution load monitoring was subdivided into the four general zoning types, and areas
within each type were calculated.
Land Uses
Zoning districts include built up and undeveloped areas indiscriminately. Thence, actual
land uses, and not zoning districts, had to be correlated with pollution data for a realistic
approach. A detailed determination of land uses within each selected subbasin was
undertaken when drainage maps became available. In this work aerial photomaps were
utilized and land uses were established block by block, obtaining additional information in
the field as required. These photomaps have the same scale (1 inch equals 200 feet) as the
study's drainage maps, and it was possible to overlay detailed land uses on the same maps
where drainage boundaries were carefully established.
Areas under each of six general land use classifications were determined on these maps. It is
not practical to include these maps in the report, since large scale reductions would be
required and a large number of sheets is involved.
A sample of the typical land use determination performed, taken from Sheet P-16 within
McDaniel drainage area, can be seen in Appendix D.
Within the study area is located the Atlanta Model Neighborhood which is being developed
under the Demonstration Cities and Metropolitan Development Act of 1966. The Model
Neighborhood area occupies 3,130 acres, nearly all of which is served by the combined
sewer system. For the purpose of the investigation, however, present land uses were
obtained for correlation with pollution data, independent of future plans for parts of the
study area.
101
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Figures 38 through 41 are simplified maps of each of the smaller drainage areas studied in
detail, in an attempt to correlate pollution loads to land uses. Drainage boundaries and land
uses have been shown on each area to permit easy visual comparison.
For land use determinations in other drainage areas outside the city limits of Atlanta, recent
aerial phc -i-aphs and information from Atlanta Region Metropolitan Planning Commission
(ARMPQ were utilized.
In general, all of the area within the upper South River basin is highly industrialized.
Although differences in land uses do exist between selected subbasins, they are not highly
significant, and percentages of land for industrial uses are similar in all. These conditions
hinder possible conclusions concerning effect of land uses on quantity and quality of runoff,
as found in the analysis of pollution data.
Calculated percentages of land uses within each drainage subbasin studied in detail are
grouped in Table 21 below. Figures for subbasins 1, 2, 3, and 5, entirely within the area
mapped for the study, are based on the detailed determination described before.
Calculations for areas 4 and 6 had to be based on less accurate maps and uncontrolled aerial
photographs. Low density land use was considered to apply to all single family dwellings
and duplexes, whereas high density land use included all apartments. For both uses, the
number of persons per dwelling varied widely.
102
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TABLE 21
UPPER SOUTH RIVER DRAINAGE BASIN
LAND USES WITHIN SUBBASINS
(Percent)
Subbasin Designation and Number
Land Use
Commercial
Low density
residential
High density
residential
Industrial
Undeveloped —
open
Interstate
ROW
Total
Confederate Boulevard McDaniel
01* 02* 03*
4.50 8.11 1.80
54.72 51.77 56.50
13.03 12.37 4.58
25.35 19.27 35.64
2.13 1.48
2.40 6.35
100.00 100.00 100.00
Federal
Harlan Caspian Prison
04 05* 06
8.00 2.49 5.12
47.70 60.59 34.92
9.20 — 0.58
24.70 28.45 20.41
10.40 8.47 36.52
— — —
100.00 100.00 100.00
* Figures based on study's drainage mapping, aerial photomaps, and field verification.
103
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KEY TO LAND USES
• • DRAINAGE AREA BOUNDARY
////// LOW DENSITY RESIDENTIAL
I I UN II UN COMMERCIAL
SOUTH RIVER BASIN BOUNDARY
1 X JX. Z INDUSTRIAL
UNDE V FIO P
UNDEVELOPED
HIGH DENSITY RESIDENTIAL
jyrJ^k:
GRAPHIC SCALE
Zfi
1500 O
1500ft.
DRAINAGE AREA N0.1
CONFEDERATE AVENUE
COMBINED SEWER OVERFLOW
104
Figure 38;
-------
• • • • SOUTH RIVER BASIN BOUNDARY
DRAINAGE AREA BOUNDARY
////// IOW DENSITY RESIDENTIAL
HIGH DENSITY RESIDENTIAL &'<¥;'&??%
v _ s-i^ar
GRAPHIC SCALE
o
*'f^ ?liii^'^3^«p4|g1:
2OOO
105
DRAINAGE AREA NO.2
BOULEVARD
COMBINED SEWER OVERFLOW
Figure 39
-------
KEY TO LAND USES
• • • DRAINAGE AREA BOUNDARY
///// LOW DENSITY RESIDENTIAL
JIJ I.I Ml III COMMERCIAL
INDUSTRIAL
UNDEVELOPED
HIGH DENSITY RESIDENTIAL
III
>
• • • • SOUTH RIVER BASIN BOUNDARY
'*wS- ^ Y^'/iAv' '/ ^ >• ^?:j£3rf *x\ *.V% •' if','''' '"" T u«jfKit»i«Wi'*i>.«it.i.*t»^J.lv; .-MY^MH ,--~. .jw
•o&^^v;?i!eyw?..;^^^^asir^"^;i b a r—,r—,.—i;-wrH!
* j-
^Gaging Station " ",; 'A'*
\ ! ntn!
-------
KEY TO LAND USES
DRAINAGE AREA BOUNDARY
////// LOW DENSITY RESIDENTIAL
LI MM IJJIII COMMERCIAL
\ X X /> INDUSTRIAL
UNDEVELOPED
HIGH DENSITY RESIDENTIAL
• • • • SOUTH RIVER BASIN BOUNDARY
GRAPHIC SCALE
Z3SP
IOOO O
107
DRAINAGE AREA NO.5
CASPIAN ST.
MIDDLE BRANCH SOUTH RIVER
Figure 4]
-------
Effect of Land Uses Upon Quality and
Quantity of Dry Weather Flows
Dry weather flow characteristics at each of the six stations were monitored during the
period of study. The results of the BOD analyses are presented in Table 22.
TABLE 22
BOD - Dry Weather Flow
Station
11
21
31
4
5
6
Confederate Avenue
Boulevard
McDaniel Street
Harlan Drive
Caspian Street
Federal Prison Branch
Mean
462
194
161
14
17
18
Standard Deviation
169
78
71
4
12
12
The high BOD's associated with the Confederate Avenue interceptor reflect the extent of
industrial activity in that area. Although industrial land use, at 25 percent of the subbasin
area, was not substantially different than in the other two combined sewer areas, the waste
BOD's are significantly higher due to the types of industries concentrated in the subbasin.
Overflows at Confederate Avenue have been observed to change color due to introduction
of textile dyes to the waste collection system. Such dyes often have high BOD's and yield
deleterious effects upon receiving waters.
Dry weather flows at stations 11, 21, and 31, the Confederate Avenue, Boulevard and
McDaniel Street interceptors, averaged 5, 12, and 6 cfs, respectively. No correlation was
evident between land use and dry weather flow quantity, either when expressed as gallons
per capita per day or as cfs per acre.
As described previously, land uses for all six areas were not substantially different, thereby
hindering correlation of dry weather flow characteristics and land use. Analysis of the data
from a limited number of subbasins suggests that such a correlation may be unrealistic for
combined sewer areas receiving industrial waste. For storm sewer areas it may be feasible;
however, data obtained from this study was insufficient to establish any definite
relationship due to the similarity of land uses for each of the three storm sewer areas. This
point will be discussed further in the next paragraph.
108
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Effect of Land Uses Upon Quality and
Quantity of Storm Runoff
Storm runoff at all six subbasins was monitored during the period of study; however, as
discussed in Section IV, areas 2, 3, and 5 were selected for detailed analysis. Since dilution
of influent industrial and domestic waste constitutes the primary source of BOD in
combined sewer overflows, it is reasonable to expect that quality of storm runoff should
reflect dry weather flow conditions. This was found to be true for all three combined sewer
flows, although the high BOD's associated with overflows at station 1 were of limited
statistical significance due to the lack of data at high flow rates.
Runoff coefficients for areas 2 and 3 were identical at 0.42 while for area 5 the coefficient
was 0.56. All three were higher than the 0.39 average of all six subbasins. The similarity of
land uses and the limited number of subbasins precluded correlation of land uses with
runoff quantities from storm events.
A statistical analysis was performed to determine those variables contributing significantly
to a relationship between land use and pollution load. Initially, variables under
consideration consisted of the six land use classifications included in Table 10—1. It was
later determined that replacement of high and low density residential classifications by a
single population density variable improved the correlation. A linear relationship was
assumed since the limited data did not warrant more refined analysis. Pollution loads
expressed as pounds BOD per acre per hour of rainfall were obtained from Tables 7 and 16.
The storm sewer area contributing to station 5 was assumed to be a combined sewer area
with zero tributary population.
For all but three of the 14 synthetic storms, population density was the significant variable,
while all others were rejected. For the remaining three, undeveloped land was selected. The
relationship would be substantially improved by inclusion of pollution load data from
additional subbasins, especially from those with widely varying land uses. Table 23 presents
the results of the analysis from which an equation may be derived for any chosen storm, of
the form:
Y - a + bXt + cX2
where Y = pollution load (pounds BOD/acre/hour of rainfall)
Xj = population density (persons/acre)
X2 = undeveloped land (%)
109
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TABLE 23
Storm
Frequency
2 weeks
2 weeks
2 weeks
1 month
1 month
1 month
1 month
6 month
6 month
6 month
1 year
1 year
1 year
1 year
Rainfall Duration
(hours)
1
2
5
1
2
5
10
2
5
10
2
5
10
20
a
3.250
0.785
0.330
3.796
1.278
0.629
0.315
3.629
1.260
0.720
3.905
2.923
0.880
0.456
b
0.057
0.025
0.073
0.030
0.020
0.052
0.034
0.026
0.057
0.027
0.018
c
-0.247
-0.190
-0.162
Average 0.038 -0.200
This table presents a base upon which considerable subsequent work may be developed, as
discussed in the next paragraph. Certain hypotheses may be developed from these results
and previous observations. For combined sewer areas, land use may not be the appropriate
primary variable upon which to base pollution load estimates. For all but initial scouring
flows and high flow rates, pollution characteristics depend primarily upon dilution of
domestic and industrial waste entering the system. The strength of this waste determines the
BOD concentration in the overflow. The pertinent parameter for correlation would
therefore be the population equivalent of the domestic and industrial waste, which would
entail a detailed analysis of industrial waste discharges within each combined area. Storm
sewer areas and combined sewer areas at high flow rates yield BOD concentrations that may
well depend upon land use more than upon population; however, further data will be
required to determine the nature of the relationship.
Recommendations for Further Study of
Land Use Effects
With very little additional field work, high frequency response characteristics of three
additional subbasins in the study area may be determined, thereby permitting inclusion of
already available data in the correlation of land use and pollution load. Doubling the sample
size will increase significantly the statistical validity of conclusions concerning such a
correlation. It would also permit determination of the form of equation most accurately
describing the relationship between pollution load, storm frequency and rainfall duration
110
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With this equation, it may be possible to standardize the results of studies across the United
States, to remove all rainfall dependent properties prior to correlation with land use effects.
Ill
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SECTION X
COMPARATIVE ASSESSMENT OF POLLUTION SOURCES
Assessment of Pollution Sources
During Dry Weather Flow
Effluent from the Intrenchment Creek and South River wastewater treatment plants
constitutes the major source of pollution during dry weather flow. With average daily
discharges of 8,800 and 5,740 pounds of BOD, respectively, these sources contribute a
significant fraction of the total annual pollution load upon South River from the study area.
the impact upon the stream may be judged from the resultant average dissolved oxygen
profile for 1968-69, shown in Figure 42. This information was compiled by the Georgia
State Water Quality Control Board (1970) and was based upon data obtained by that
organization and the City of Atlanta. The average critical point is reached near Panthersville
Road, about two miles below Bouldercrest, with a dissolved oxygen deficit of 4.35 mg/1.
The proximity of the critical point to the headwaters area reflects a number of pertinent
factors, most significant among which is the relatively large fraction of dry weather stream
flow attributable to sewage treatment plant effluent. Approximately 75 percent of the flow
at Bouldercrest originates at the wastewater treatment plants during dry weather periods.
The resulting low flow rates yield low velocity and high reaeration rates. Furthermore, the
deoxygenation rates of 0.20 for trickling filter effluents and 0.08 for activated sludge
effluents assumed for this study, tend to yield rapid utilization of dissolved oxygen.
The minimum dissolved oxygen level in South River during 1968—1969 averages 1.9 mg/1 as
compared with the 3.9 mg/1 average level. The minimum also occurred near Panthersville
Road.
Other pollution sources are of minor importance. BOD's associated with the small dry
weather flows from storm sewered areas have little impact upon the stream when compared
with effluent from the treatment plants. Intermittent bypassing of raw sewage from the
pumping station at Constitution Road, which has been observed during the study, may
significantly affect water quality; however, no data are available to judge the extent of
impact.
Assessment of Pollution From Storm and Combined Sewer Areas
A comparison of BOD loads from storm and combined sewer areas is shown in Figure 27,
Section V. These curves indicate that annual average BOD loads from storm sewer areas are
approximately 55 percent of those from combined sewer areas.
It must be noted that these pollution loads are based upon average flows in the combined
sewers. A storm occurring during the peak annual flow that might be expected on an
113
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R « I N F * L L
«T SUME D IN
HE «0*« I ERS
» RE » ONLY —
DISTANCE (feet x 103)
I 0
<=>
co
cc
cj
30
= 40
50
c/o
60
80
90
I 00
J_
2 -
4 -
SATURATION D . 0 . CONCEN TR AT I ON = 8.25 r.g
6 -
NOTE:
DRY WEATHER FLOW--
OBSERVED D 0. PROFILE
A. ALL WWTP FLOW TREATED; STORM DRAINAGE K, = 0. 05
B. ALL WWTP FLOW BY-PASSED; STORM DRAINAGE K, = 0.05
C. ALL WWTP FLOW TREATED; STORM DRAINAGE K = 0. 1 0
THEORETICAL D.O. PROFILES
FOR TWO-WEEK STORM
Tl
f
•"1
THEORETICAL ANNUAL AVERAGE DISSOLVED OXYGEN PROFILES IN SOUTH RIVER FOR TWO-WEEK STORM
to
-------
afternoon in May, would yield BOD concentrations and pollution loads 56 percent higher
than the average, whereas a similar storm occurring before dawn on a Sunday in February
would yield only 56 percent of the average pollution load. Therefore ratios between
pollution from storm and combined sewer areas actually depend upon the exact time of
year.
Assessment of the Impact Upon the South River
of Pollution Loads from Storm Runoff
Calculation of the theoretical dissolved oxygen profiles of Figure 42 revealed the relative
importance of the various sources of pollution during runoff events. The profiles should be
interpreted only with full understanding of the assumptions used in their derivation. In
order to assess the impact of runoff from the study area upon the South River, it was
assumed that the storm occurred uniformly over the headwaters only, down to the
confluence of Intrenchment Creek and South River. Lateral inflow to the river below this
point was assumed equal to that expected under dry weather conditions. The storm applied
to the study area was a two—week storm of two—hour duration, with a peak at one—quarter
of the duration. Treatment of intercepted flow was assumed for two of the profiles, while in
the third it was assumed that all treatment plant flow was bypassed.
Deoxygenation rates were obtained from a study by Schroepfer et al., (1960) of the
Mississippi River near St. Paul, Minnesota, as listed in Table 24.
TABLE 24
Waste Description Range of KI (20°) Average
Untreated Sewage 0.40 - 2.61 1.0 (4,8,12 hours)
Activated Sludge Effluent 0.03 - 0.13 0.08
Trickling Filter Effluent
High Rate 0.18-0.22 0.20
Standard Rate 0.18-0.24 0.21
Unpolluted River Flow 0.00 - 0.15 0.06
115
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Generally accepted values of Kt for untreated sewage of approximately 0.25 represent rates
based upon 1, 3, and 5-day BOD's, whereas Schroepfer et al., showed that initial rates for
time periods less than 12 hours are much higher. For storm runoff from urban areas,
deoxygenation rates were assumed to range from 0.05 to 0.10 although this estimate
requires verification. The sensitivity of the dissolved oxygen profile to variations within this
range is included in Figure 42. All temperatures were assumed to be 24° C, the average
occurring during 1968-1969. Velocities of three fps were assumed along the whole river, in
order to maintain the observed lag time of 9—12 hours between commencement of rainfall
and arrival of the flood wave at Klondike.
The river was divided into five reaches, in each of which steady, uniform flow was assumed
to occur, at flow and pollution rates equal to the average occurring during the duration of
runoff within the tributary area. A far more sophisticated flood routing computer program,
requiring detailed information from the entire South River basin, will be desirable for future
studies in order to assess the exact impact of pollution sources and abatement alternatives
upon the South River under dynamic conditions.
The approximation to the actual hydraulic response of the river, as utilized in this study, is
considered to be sufficient for assessing the relative impact of various sources of pollution
upon the water quality of the South River.
Average reaeration rates in the South River were calculated for each of the five reaches,
utilizing hydraulic properties and equations determined by Wallace and Reheis (1969). Data
was augmented by information obtained in this study. Although the equations were derived
for dry weather flow conditions, they are considered to represent storm flow conditions
more accurately than any alternative procedure, other than measurement under such
conditions.
Combined sewer overflows at Confederate Avenue and Boulevard increase the ultimate BOD
of the upper end of Intrenchment Creek by 14 to 52 percent above the level to be expected
from storm runoff alone. The range reflects the sensitivity to variation of K! for storm
runoff from 0.05 to 0.10 respectively. However the maintenance of any stream standard of
water quality in the South River will require consideration of biochemical oxygen demand
during periods of time less than one day. Due to the high initial deoxygenation rates
associated with untreated sewage, the ultimate BOD is less significant a gage of pollution
impact than a short term BOD that reflects these high rates. The only such measure
commonly available is the 5-day, 20° C BOD, which is increased at the upper end of
Intrenchment Creek by 130 percent above the level to be expected from storm runoff alone.
The analysis suggests, therefore, that the impact of combined sewer overflows upon the
receiving stream may be due to both the increase in volume of biodegradable matter
discharged and the increase in the average deoxygenation rate above the level for storm
runoff alone.
Flow entering Intrenchment Creek from the Confederate Avenue and Boulevard overflows is
diluted by lateral inflow until reaching the Intrenchment Creek wastewater treatment plant.
Overflows at the McDaniel Street interceptor increase the 5-day, 20° C BOD by
116
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approximately 130 percent, although the impact is rapidly dissipated by dilution from
lateral inflow. By the time flow reaches the South River wastewater treatment plant, the
increase in 5-day, 20° C BOD due to combined sewer overflow is only 7 percent.
Another effect of combined sewer overflows upon a receiving stream has been reported by
Engineering Science, Inc. (1967) in a study of combined sewer pollution in San Francisco.
They observed that combined sewer overflows have a considerable impact on the bacterial
quality of receiving waters. However, coliform MPN's were estimated to decrease by 90
percent within approximately 12 hours, slightly greater than the travel time to Klondike.
The relative impact of combined sewer overflows and storm runoff for other than
two-week, two-hour storms may be estimated from Figure 26. The impact for lower
frequency storms decreases; however, such storms are of lesser significance in combined
sewer studies.
Wastewater treatment plant effluents during runoff events, including treatment of
intercepted flows, have little impact upon the South River, in contrast to their significant
influence during dry weather flows. Calculations indicated that treated effluent at the
Intrenchment Creek wastewater treatment plant may decrease the average ultimate BOD at
that point.
Bypassing of all flows, including intercepted combined sewer flows, has a severe impact
upon the South River. As described in Section VII, this procedure is common during periods
of storm runoff. It is also more severe in its pollution impact than discharge of the same
combined sewer flow at the interception points, because additional sewage enters the
interceptor lines before bypassing at the treatment plants. Bypassing therefore adds
considerable volumes of untreated waste to the flows from combined sewer areas.
The high rate of deoxygenation for untreated waste during the first 12 hours causes an
increase of approximately 33 percent in the average deoxygenation rate along the entire
South River to Klondike. Although bypassed flow rates at the South River wastewater
treatment plant tend to be lower, the impact upon the stream is greater due to the high
percentage of sanitary waste in these flows. Under these limited conditions, the increase in
deoxygenation rate would cause the South River to become anaerobic at a point
approximately 8 miles upstream of Klondike.
It is emphasized that these conclusions are theoretical and apply only under the conditions
outlined at the beginning of this section. It is unlikely that all wastewater treatment plant
flows would be bypassed for a storm of this size. A normal storm of this frequency would
cover not only the headwaters, but probably all, or a large part of, the South River basin,
thereby causing considerable dilution of BOD concentrations. The added inflow would also
increase stream velocity, tending to move the dissolved oxygen profile downstream. The
profiles of Figure 42 may therefore be considered conservative in their representation of
normal stream conditions during a storm.
117
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The only difference in the calculations of curves A and C of this figure is the variation in the
assumed value of Kt for storm drainage. Both of these curves assume treatment of all waste
and intercepted combined flows. Application of the higher value of Kt to the case where all
treatment plant flows are bypassed, would cause South River to become anaerobic further
upstream of the point shown on curve B.
Valid assessment of the relative impact of individual pollution sources upon the South River
may be obtained from the calculations despite uncertainty as to the exact value of some
variables. However, accurate prediction of dissolved oxygen levels in the South River
subsequent to treatment modifications will require a more detailed analysis of the physical
and hydrologic characteristics of the South River basin than was required for this study.
Present sources of storm pollution, in order of decreasing annual pollution load, are as
follows:
Ibs BOD/year
1. Storm drainage from urban areas tributary to
Bouldercrest Road (22,042 acres). 5,577,000
2. Combined sewer overflows at Confederate Avenue
and Boulevard (3,550 acres). 1,633,000
3. Bypassing of flows from the Intrenchment Creek
interceptor. 506,000
4. Combined sewer overflow at McDaniel Street (968
acres). 445,000
5. Intrenchment Creek wastewater treatment plant
effluent. 185,000
6. Bypassing of flows from South River wastewater
treatment plant. 183,000
7. South River wastewater treatment plant effluent. 146,000
Although important, annual pollution load is less significant than impact of individual
storms upon the South River. Consideration of bypassing frequency, impact of overflows
and bypassed flows upon average deoxygenation rates, bacterial effects and pollution
loading rates, suggests that priorities among the seven pollution sources be shifted. In order
of decreasing impact, the following arrangement appears reasonable:
118
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Ibs BOD/year
1. Bypassing of flows from the Intrenchment Creek
interceptor. 506,000
2. Combined sewer overflows at Confederate Avenue
and Boulevard (3,550 acres). 1,633,000
3. Bypassing of flows from South River wastewater
treatment plant. 183,000
4. Combined sewer overflow at McDaniel Street (968
acres). 445,000
5. Storm drainage from urban areas tributary to
Bouldercrest Road (22,042 acres). 5,577,000
6. Intrenchment Creek wastewater treatment plant
effluent. 185,000
7. South River Wastewater treatment plant effluent. 146,000
119
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SECTION XI
CONDITIONS IN THE STREAM
General
A discussion of conditions in the South River, its branches and tributaries at or near the
headwaters, involves preliminary establishment of a point along the stream below which
there is a possibility that actual conditions could be compared to some quality standard.
As discussed early in the report, the basin's headwaters lie within sewer systems, and
extension of these systems in a downstream direction can be expected to occur with growth
of the area. From a practical point of view, a few upstream sections of the stream system
have to be considered as open storm sewers requiring encasement rather than polluted
streams needing protection or treatment.
For these reasons a study of conditions along the stream must start at the Jonesboro Road
bridge, a short distance above the outfall of the South River wastewater treatment plant. At
this point, the stream has a definite base line flow and shows fairly good quality conditions
during dry weather.
Dry Weather Flow Conditions
Dry weather flow conditions along the river, below the Jonesboro Road bridge, have been
monitored for the past two years by the State Water Quality Control Board (SWQCB), as
discussed before. These studies covered a total of seven stations distributed over forty—four
miles of river length. An oxygen sag curve for part of this length is included in Figure 42.
For the present study, monitoring stations were established at the Jonesboro Road,
Bouldercrest Road and Klondike Road bridges. These stations are shown in Figures 43 and
44. Although the length of time over which conditions in the river were monitored is shorter
than the SWQCB period of record, results obtained at dry weather flow conditions were in
fairly good agreement with values in their studies. Dissolved oxygen concentrations at dry
weather flow conditions for the sewer stations monitored by SWQCB are included in Figure
42. Values are arithmetic averages of available results for each station.
Stream Survey Observations
Field inspection of conditions at the river's headwaters, as well as at some of the small
tributary streams, revealed that during dry weather streams showing some base flow were
rather clean. No flow was observed at first sections of streams originating at combined sewer
overflows, such as the north branch near 1—75 or Intrenchment Creek near Boulevard.
121
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Gaging and Sampling Station
SOUTH RIVER
AT
KLONDIKE ROAD
F I ow LeveI Recorder
122
Figure 43
-------
Flow Level Recording Stat ion
South River at Jonesboro Road
Flow Level Recording Station
South River at Bouldercrest Road
123
Figure 44
-------
At Lakewood Avenue, the north branch had some base flow, was rather clean and had no
odor. Measured conductivities were in the range of those found at water sources for the
area, approximately 200 /imhos/cm.
The middle branch, near Caspian Street showed temperatures of 85° F during hot summer
days. The stream generally was moving slowly, had no odor, low conductivity and showed
some growth on the bottom.
The south branch was surveyed several times. Conductivities were usually high to very high
at this stream. Some possible industrial sources were also inspected. Lagoons at Tennessee
Corporation had conductivities exceeding 1,000 jumhos/cm. Values as high as 2,000 - 3,000
were observed where wastes from Allied Chemicals entered the stream.
Intrenchment Creek was observed to have some flow, no odor and clean appearance, with
low condictivities, at Custer Avenue. Downstream of the wastewater treatment plant, at
Constitution Road, its waters were dark reddish in color, had foul odor and rather high
conductivities, with very low amounts of dissolved oxygen. Soapsuds were also observed
frequently.
Poole Creek, entering South River from the south upstream of Forest Park Road, generally
had a clean, free running appearance at dry weather conditions.
The main stream of South River was generally found to be clean at the Jonesboro Road
bridge, upstream of the South River wastewater treatment plant outfall. Dissolved oxygen
was found to be always above 6 mg/1 at dry weather conditions, and no odors were noticed.
At Bouldercrest, continuous discharges of effluent from both treatment plants accounted
for low dissolved oxygen values at dry weather flow conditions. Recorded conductivities
were always high. Water was observed to maintain high color and turbidity. Flow consisted
mainly of plant effluent, with BOD's usually in the 20—30 mg/1 range, as a result of
effluent dilution with base flow in the stream.
Storm Flow Conditions
Faster flow velocities and slower average deoxygenation rates for storm water were expected
to move the critical point of the dissolved oxygen sag curve to a point further downstream
from the dry weather critical point near Panthersville Road. Heavy pollution loads from
urban storm runoff and bypassing procedures are diluted by lateral inflow along the South
River, thereby offsetting the impact upon water quality.
Observations at the Klondike Road monitoring station indicated that flow at this point
becomes anaerobic under certain conditions. Difficulty was encountered in continuous
monitoring of DO and conductivity since the low velocities of dry weather flows caused the
probes to clog. However, the existing data indicate that a two-week storm uniformly
distributed over the South River basin will cause anaerobic conditions in the stream at
124
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Klondike Road for a brief period of time. A larger storm of one—year frequency may be
expected to lower DO levels to approximately one mg/1, reflecting the higher velocity and
dilution in the stream. Extended duration, low intensity rainfall causes DO at Klondike to
vary around three mg/1.
Valid conclusions based upon the limited data are difficult. However, it appears that the
large amount of pollution from very low frequency storms is rapidly flushed from the South
River basin, exerting its major impact upon water quality below Klondike Road, where
dilution from lateral inflow becomes significant. Higher frequency storms scour the same
initial organic load from the combined sewers, but receive less dilution along the river.
Velocities are lower and average deoxygenation rates are higher, causing greater impact upon
the stream within the South River basin. Finally, very minor rainfalls, which constitute the
majority of rainfall events in the Atlanta area, cause sufficient overflow to scour the
combined sewers while adding little dilution along the river. Impact from these rainfall
events is the greatest and most frequent. It is also the easiest to prevent, due to the relatively
low volumes of overflow. Further verification of the observations would entail monitoring
of water quality down to Jackson Lake.
Stream Uses and Water Quality Standards
Conclusions concerning alternative pollution abatement schemes should take into
consideration not only the relative importance of various sources of pollution, but also the
present and future uses of the stream and costs required to maintain the water quality
standards associated with those uses.
As an intrastate stream, the South River falls under jurisdiction of the State Water Quality
Control Board, which requires secondary treatment of all municipal wastes. At present the
upper stream reaches are used solely for the transport of wastewater treatment plant
effluent, which constitutes a significant fraction of the dry weather stream flow. In previous
years expanding development of the study area has caused conversion of sections of the
headwater channels to closed culverts. The trend is expected to continue in the future.
Future increases in pollution loading, during both wet and dry weather, will further deplete
oxygen resources of the South River. Adequate planning on a regional scale should be
implemented to ensure optimal future use of the stream by the Atlanta area and
downstream communities. Such planning would pinpoint future competition for the stream
resource for recreation, water supply, waste disposal and other potential uses, enabling
establishment of standards of water quality. The far-reaching impact of pollution from high
frequency storms occurring in the Atlanta area emphasizes the need for such a regional plan.
The Federal government has recommended maintenance of the water quality level in the
South River above Snapping Shoals sufficient to support fishing. In view of the intrastate
nature of the stream, the recommendation is not binding. However a point should be
determined above which waste assimilation is the declared purpose of the stream. Waste
treatment should be implemented to maintain whatever water quality standards are
125
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necessary to support the declared stream use below that point. Such a procedure would
establish a logical framework upon which optimal expansion of waste treatment facilities
may be based.
The procedures would require development of a model of the hydrology and water quality
of the South River. The various studies that have been performed on the river and the
detailed information concerning pollution characteristics of the Atlanta area determined in
this study, should simplify development of such a model. The model would be used to assess
the impact of changes in area development and waste treatment practices upon the water
quality. Required reduction of pollution loads would depend upon the choice of river use
below the reach utilized for waste transport. Table 25, compiled by McKee and Wolf
(1963), presents a typical analysis of water quality requirements to meet various stream use
objectives.
126
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WATER QUALITY OBJECTIVES AND MINIMUM TREATMENT REQUIREMENTS
Wafer Quality Objectives, Applicable to Receiving Waters, for Salt and Freih Surface Waters and Underground Waters
Water qua!tty>
wator usos
y
A. WATER SUPPLY.
DRINKING, CULIN-
ARY A FOOD PRO-
CESSING
Without treatment other
than simple disinfection
and removal of naturally
present impurities
B. WATER SUPPLY,
DRINKING, CULI-
NARY A FOOD PRO-
CESSING
With treatment equal to
coagulation, sedimenta-
tion, filtration, disinfec-
tion and any additional
treatment necessary for
removing naturally
present impurities
C. BATHING, SWIM-
MING AND
RECREATION
Note: When waters are
used for recreational
purposes Much as fishing
A boatine. exclusive of
bathing A swimming,
I—1 the number "1000" may
1>O be substituted for "240"
*-J in statement of coliforra
objective
D. GROWTH &
PROPAGATION OF
FISH, SHELLFISH &
OTHER AQUATIC
LIFE
E. AGRICULTURAL
AND INDUSTRIAL
WATER SUPPLY
Without treatment ex-
cept for the removal of
natural impurities to
meet special quality re-
quirements, other than
those classified under
"A" above.
Note: For agricultural
water supply, salinity
and Eodium hazards are
determined by electrical
conductivity (EC X 10")
and sodium adsorption
ratio (SAR). Waters
hiph in both salinity and
H sodium are generally un-
suitable for irrigation
Si- purposes. (See "rlassifi-
H— > cation and use of irriga-
tjon waters", circular
No. P69, U.S. Depart
^ ment of Agriculture,
<-" November, 1955)
Organising of the
coliform group
Most probable number
coliform bacterial con-
tent of a representative
number of samples
should average less
than 50 per 100 ml.
in any month
M.P.N. coliform bac-
terial content when as-
sociated with domestic
sewage of a represen-
tative number of sam-
ples should average
less than 2000 per 100
ml. and should not ex-
ceed this number in
more than 20 per cent
of samples examined
in any month
Coliform bacterial con-
tent of a representative
number of samples
should average less
than 240 per 100 ml.
and should not exceed
this number in more
than 20 per cent of
samples examined when
associated with domes-
tic sewage (sec note
under "C" at left)
Coliform bacterial con-
tent of a representative
nuuibcr of samples
should not have a
median concentration
greater than 70 per
100 ml. in waters used
for the growth A prop-
agation of shellfish
Floating, suspended
& sottlcable solids
& sludge deposits
None attributable to
sewage, industrial
wastes or other wastes
or which, after reason-
able dilution A mixture
with receiving waters,
interfere with the best
use of these waters for
the purpose indicated
Same as for use "A"
above
Same as for use "A"
above
Same as for use "A"
above
Same as for use "A"
above
Taste- or odor-
producing
substances
None attributable to
sewage, industrial
wastes, or other wastes
None attributable to
sewage, industrial
wastes, or other wastes
which, after reasonable
dilution A mixture,
will increase the thresh-
old odor number
above eight (8)
None attributable to
sewage, industrial
wastes, or other wastes
which, after reasonable
dilution A mixture,
will interfere with the
best use of these waters
for the purpose indi-
cated
None attributable to
sewage, industrial
wastes, or other wastes
which will interfere
with the marketability
or propagation of rec-
reational or commercial
fish, shellfish, or other
edible aquatic forms
None attributable to
sewage, industrial
wastes, or other wastes
which will adversely
affect the marketability
of agricultural or in-
dustrial produce
Dissolved
oxygon
Greater than five
(5) parts per mil-
lion except for
underground
waters
Greater than five
(5) parts per mil-
lion except for
underground
waters
Greater than five
(5) parts per mil-
lion
Greater than six
(6) parts per
mjllion
Greater than three
(3) parts per
mil linn
PH
Hydrogen ion con-
centration ex-
pressed as pll
should be main-
tained between
6.5 and 8.5
Same as for use
"A" above
Same as for Use
"A" above
Same as for use
"A" above
Hydrogen ion con-
centration ex-
pressed as pH
should be main-
tained between
6.0 A 9.5
Toxic, colored, or
othor deleterious
substances
None alone or in
combination with
other sLiljstanccs or
wastes in sufficient
amounts or of such
nature as to make
receiving water un-
safe or unsuitable
for use indicated
(U.S.P.H.S. Stds.)
Same as for use "A"
above
Same as for Use "A"
above
None alone or in
combination with
other substances or
wastes to sufficient
amount or of such
character as to make
receiving waters un-
safe or unsuitable
for use indicated
Same as for use "A"
above
Phenolic
compounds
Less than five (5)
parts per billion
Less than five (5)
parts per billion
Less than 25 parts
per billion or none
in sufficient
amounts such as to
impart a residual
taste to recrea-
tional or commer-
cial fish, shellfish,
or other aquatic
forms
Same as for use
"C" above
None in sufficient
quantity as to
make receiving
water unsuitable
for use indicated
OH
None
None alone
or in com-
bination
with other
substances
or wastes as
to make
receiving
water unfit
or unsafe for
the use
indicated
Same as for
use "B"
above
Same as for
use "B"
above
Same as for
use "B"
above
High temperature
wastes
Not in sufficient quan-
tities alone or in com-
bination with other
wastes to interfere
with the use indicated
Same as for use "A"
above
Same as for use "A"
above
None in sufficient
quantity as to be in-
jurious to or interfere
with the normal propa-
gation of fish, shellfish,
or other aquatic life
Same as for use "A"
above
Minimum treatment
requirements for
domestic sewage
Sedimentation and
effective disinfection
Sedimentation and
effective disinfection
Sedimentation and
effective disinfection
Sedimentation for all
uses under this group
but disinfection re-
quired in addition only
if discharged into
waters used for the
growth A propagation
of shellfish, either com-
mercial or recreational
Sedimentation and
effective disinfection
«O
<3
>
F<
i—i
1-3
Ki
O
-------
SECTION XII
POLLUTION ABATEMENT APPROACHES
Alternate Solutions As Applied To
Principal Pollution Load Sources
Assessment of pollution load sources demonstrates that at dry weather flow conditions,
treatment plant effluents and bypasses are the most important sources of pollution load
upon the stream. During storms, however, the largest fraction of the load comes from
overflows and bypassed flows. Both conditions are covered by alternate abatement
approaches to be discussed in the following paragraphs.
Wastewater Treatment Plants
Two different aspects must be considered in reducing pollution from wastewater treatment
plants during dry weather: elimination of the need for bypassing under certain flow
conditions, and general improvement of effluent quality during normal plant operation.
Modifications to Eliminate Bypassing
As discussed earlier, bypassing at existing treatment facilities is presently required when
either quality of quantity of influent, or both exceeds the capabilities of the plant.
At the Intrenchment Creek wastewater treatment plant, where bypassing is more frequent,
grease, grit and mud reach the plant at times in amounts that would upset the treatment
units if allowed to flow through the plant. Separation of these pollutants ahead of the plant
may be the only way to reduce the need for bypassing during dry weather.
Large amounts of grease reaching the treatment facilities at times, can be traced to industrial
operations within the basin. Smaller amounts may originate from illegal dumping of used
lubricating oils and other sources.
The City of Atlanta has established Standards of Acceptability of industrial trade waste for
admission into city sewers. Regulations established to delineate these standards, if strictly
enforced, should suffice to control the discharge into the sewer system of materials known
to interfere with plant operation.
Construction of grease separators ahead of treatment facilities should be considered, in
order to reduce the need for bypassing during dry weather.
The presence of large amounts of grit in the influent is a problem common to most existing
treatment faciliites in the Atlanta area. Source of this grit has been described at the
129
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beginning of Section VII. Part enters the interceptors during storms through regulator
devices at combined sewer overflows. Although reduction at the source is the preferred
solution whenever feasible, the need for separation and removal of grit at the overflow
points has long been recognized. A structure has been designed for this purpose at the
Deering Road overflow, located within the Peachtree Creek basin on the north side of the
City. Similar structures at the three major overflow points within the South River basin
would undoubtedly reduce amounts of grit reaching the plants and consequent need for
bypassing. A less expensive alternative to this solution is discussed later. It should be noted
that the presence of suspended and colloidal material in storm flows is primarily due to the
abundance of clays in the Atlanta area.
Modifications to Improve Effluent Quality
Operating performance under normal conditions at the treatment plants has been discussed
in Section VII. Both are performing efficiently for the types of processes involved, yielding
average removal of 83 percent of influent BOD. However, the impact of the treated
effluents upon the dissolved oxygen level of the receiving stream is significant. The water
quality may be expected to deteriorate further as wastewater flows increase in future years.
Any decision to improve effluent quality would have two beneficial effects. Quality of dry
weather flows in the South River would be improved, possibly permitting uses for this
stream other than treated effluent disposal. If bypassing is eliminated or reduced, improved
effluent quality during storms will ameliorate conditions in the receiving stream due to
storm runoff as well as combined sewer overflows, should the latter remain untreated.
Such benefits should be weighed against the cost of converting existing facilities to aeration
plants, which would permit BOD removal efficiencies up to approximately 95 percent. The
resulting pollution load of the effluent would be less than half of the existing load and
would cause a concomitant rise in water quality.
Studies concerning treatment plant modifications to alleviate pollution during dry weather
flow should be undertaken in the near future.
Combined Sewer Overflows
Several alternatives may be considered for alleviating pollution of the South River by
combined sewer overflows and bypassing of intercepted combined flows at the wastewater
treatment plants. The feasibility, benefits and economics of each are considered in the
following paragraphs.
Separation of Systems
Elimination of combined sewer overflows could be accomplished through complete
separation of the sanitary and storm sewer systems within combined sewer areas. Two
different aspects are involved in this separation, the within-the-right-of-way aspect or
130
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sewer system separation, and the within-the-buildings aspect, involving plumbing and
connection modifications.
The first aspect, modification of the sewer system for separate conveyance of sanitary
sewage and storm runoff, could be accomplished more easily in this area through
construction of a new separate sanitary system and reconnection of house services to this
system, leaving the existing combined sewers for storm runoff use exclusively. Since
plumbing arrangements of most existing buildings combine storm and sanitary discharges
into the house service, within-the-building plumbing modifications would also be required.
Disregarding momentarily considerations of difficulties to be found in actual, successful,
system separation and of the amount of pollution in storm water runoff from urban areas, a
cost estimation for separation has been made. It must be emphasized that in the South River
area, two circumstances would favor separation, as compared to other areas of Atlanta or of
most other cities with combined sewers in the Nation. First, areas served by combined
sewers within the basin are located at the headwaters, and do not receive contributions of
sanitary sewage from separate systems upstream. Consequently, sewers required for
separation of sanitary flows can be sized exclusively for the needs of the adjacent areas to be
served, and not to accomodate separate flows entering from other areas upstream.
The second favorable condition is that most of the combined sewer system lies in the Model
Neighborhood area, where redevelopment is scheduled, facilitating reconnection of buildings
to a new separate system.
For comparative cost estimating purposes a system of separate sanitary sewers capable of
serving the area was developed on a set of the project's drainage maps for the combined
sewer areas. Separate sanitary sewers were extended to the points where the existing
interceptors presently begin, and were assumed to be connected to them.
Current estimating prices for new construction in the Atlanta area were utilized in
calculations. These prices apply to peripheral areas, and were multiplied by a factor of 1.6
to allow for increased construction difficulties within the existing combined sewer area,
with heavy traffic, tall buildings, narrow streets and an interfering, extremely complex,
existing utility system in the densely developed area. Additional difficulties, such as the
need to maintain uninterrupted service while reconnecting buildings and interference of
existing gravity lines with new ones to be laid on grade, are very difficult to assess.
Temporary pumping of sewage would be required at entire groups of buildings to permit
reconnection.
In addition to within-the-right-of—way construction costs, plumbing modifications
would be requried at many buildings. Internal plumbing conversions have been estimated to
cost from $1,000 to $1,400 per dwelling unit on recent studies at other cities. A figure of
$1,800 per dwelling unit is reasonable for an estimate of the cost of modification within
private property in Atlanta. A summary of estimated costs follows for each combined sewer
subbasin. A cost breakdown is included in Appendix A.
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Separation of the sanitary and storm sewer systems would eliminate overflows from
combined sewer areas, however, pollution resulting from runoff from storm sewered areas
would remain. As shown in Section VI, such pollution is significant, ranging from one—half
to three—quarters of the pollution from combined sewers. A weighted average of 55 percent
appears reasonable as an estimate of this ratio. Therefore separation would reduce total
annual BOD from existing combined sewer overflows from 460 Ib/acre to 253 Ib/acre at an
estimated cost of S7,859/acre. Separation would also alleviate the need for bypassing
intercepted combined flows at treatment plants, thereby further reducing pollution load
upon the South River by about 690,000 Ibs BOD/year. Amortization of costs over a
25-year period at 6.5 percent yields a cost-benefit ratio, expressed as dollars/lb BOD
removed, of $1.82.
SUMMARY
Area No. 1 , Confederate Avenue
Area No. 2, Boulevard
Area No. 3, McDaniel Street
Area No. 3A, Joyland Park
Total Costs
Within the
Right-of-Way
$ 3,706,750
13,977,840
4,435,260
275,420
$22,395,270
Within Private
Property
$ 2,268,000
9,360,000
2,970,000
36,000
$14,634,000
Total
Cost
$ 5,974,750
23,337,840
7,405,260
311,420
$37,029,270
Average Cost
Per Acre $ 4,753 $ 3,106 $ 7,859
Regulator Modification
As pointed out in Section V, interception and subsequent bypassing of significant fractions
of the runoff from the small, high frequency storms, constitutes a major constraint on the
effectiveness of overflow storage as a pollution abatement alternative. This practice also
constitutes the primary source of pollution during storm flows due to the release of
untreated sewage tributary to the interceptor. A most effective and feasible means of
alleviating this problem would entail modification of the regulators to preclude introduction
of all combined flows to the interceptors. In this way overflows could be contained in
storage reservoirs for subsequent treatment, prior to discharge to the receiving stream.
Furthermore, the need for bypassing raw sewage and poor quality intercepted combined
132
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flows at the treatment plants would be eliminated. Grit and grease removal facilities at the
treatment plants would not be as necessary for successful operation, since detention in the
reservoirs would separate much of this material.
Several feasible alternatives exist for modifying the three regulators in the study area. The
least effective, yet easiest approach would be to limit the volume of intercepted flow by
decreasing the size of the regulators so that only peak dry weather flows would be accepted.
Greater fractions of the small combined flows that constitute the major part of the
combined sewer pollution problem, would be contained in the storage reservoirs.
Intercepted combined flows would not be as great at the treatment plants, thereby
decreasing the necessity for bypassing. A certain amount of grit and grease would still be
carried with the intercepted flow, however, storage and treatment facilities for these
materials at the treatment plant would not need to be as extensive as would be required for
present intercepted flows.
A second alternative would entail installation of semi—automatic, rack and pinion
drop—gates at the regulator walls, activated by remote control and telemetering equipment.
Such a device would be activated at the outset of rainfall in the area, averting interception
of all storm flow. The gate would be raised after runoff cessation, permitting interception of
normal sewage flows. Approximate cost of a reliable system of this type is estimated to be
$40,000 for all three regulators.
Fully automatic devices, activated by rain gages and flow monitoring equipment in each
area, could be installed at an estimated cost of $50,000. This approach would obviate
human error in operation of the regulators.
Of these three alternative modifications to existing regulators, the third would be most
effective. The fraction of bypassing events at the treatment plants caused by intercepted
combined flows is approximately three—quarters. Based upon this estimate, installation of
automatic regulators would prevent bypassing of 506,000 Ibs BOD/year at Intrenchment
Creek and 183,000 Ibs BOD/year at South River wastewater treatment plant. With an
estimated total expenditure of $50,000, the amortized cost—benefit ratio for modification
of the two regulators contributing to the Intrenchment Creek interceptor would be
$0.0057/lb BOD removed. The amortized cost—benefit ratio for installation of an automatic
regulator at the McDaniel Street overflow would be $0.0074/lb BOD removed.
It is emphasized that only a small percentage of the flow in treatment plant bypasses
originates at the combined sewer regulators, although this percentage is sufficient to cause
the bypasses in most cases. Therefore prevention of bypasses by automatic closing of the
regulators during storm flows will not increase significantly the amount of pollution already
existing in combined sewer overflows. Maximum intercepted storm flows at Confederate
Avenue and Boulevard are approximately 14 and 7 cfs respectively, whereas overflows may
reach several hundred cfs.
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In-System Storage
A study of possible in—system storage in the South River basin is discouraging. Slopes of the
order of 0.5 percent to 1 percent in the large combined sewers of the area introduce definite
volume limitations. Furthermore, age, condition and construction materials of many sewer
sections weigh against extended use of in—system storage.
Off—System Storage
Storage at or near the overflow points offers a definite and economical possibility in the
study area. Maximum possible storage areas utilizing undeveloped low land adjacent to the
stream beds are shown in Figures 45 and 47. Figure 46 shows the area covered by
containment of water to elevation 934 feet, whereas Figure 48 shows the area to 878 feet.
Curves on Figures 45 and 47 are storage volumes at different surface elevations in both
areas, based on present topography. One of these low areas, at the McDaniel overflow, could
store overflow volumes corresponding to 100 percent of the BOD from a one-year storm
by utilizing all land up to elevation 931 feet.
Storage would facilitate treatment of overflows, and subsequent disposal at a reduced rate
of flow. Due to the larger flow volumes, smaller percentages of overflow BOD can be stored
at existing undeveloped land at the Confederate Avenue and Boulevard overflows. Sanitary
land fills developed in the past in the low areas adjacent to the stream have set limitations to
available storage volumes. However, storage of 100 percent of the BOD from all six—month
storms is still possible within present flood plains up to elevation 879 feet.
Development of treatment alternatives for stored overflow from combined sewers requires a
decision concerning the size of the "design storm" to be handled by the system.
Many published studies of combined sewer pollution abatement schemes have designed
storage and treatment facilities sufficient to handle storms of low frequency. Typical design
storm recurrence intervals are 10 and 15 years. While consistent with present drainage
practice, this assumption is unnecessarily conservative for alleviation of pollution from
combined sewers. Results of this study indicate that two—week and higher frequency storms
yield 57 percent of the total annual BOD discharged to the South River from combined
sewers. Whenever feasible, provision for storage and treatment of all flows from these small
storms will also enable storage and treatment of significant fractions of flows from larger
storms, thereby permitting treatment of at least three-quarters of the total annual BOD. It
will also alleviate the considerable shock impact of overflows from the individual
high-frequency storms. The storm of two-week average recurrence interval is therefore
recommended as a reasonable "design storm" upon which to base plans for alleviation of the
effects of pollution from combined sewer overflows.
Storage required at the Confederate Avenue and Boulevard overflows will be 1.8 million
cubic feet, which from Figure 48 entails submergence of 10.7 acres of land up to elevation
873 feet. Required storage at the McDaniel Street reservoir would be 0.5 million cubic feet,
134
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OFF-SYSTEM STORAGE
915
910
i " r
McDANIEL STREET
COMBINED SEWER OVERFLOW
1000
2000
3000
4000
5000
1000 CUBIC FEET
-------
-------
iN-SYStEM STORAGE
OFF-SYSTEM STORAGE
1000
BOULEVARD AND CONFEDERATE AVENUE
COMBINED SEWER OVERFLOW
1 1 1 1 1 1 1 1 1 1 1 1 I 1
1 '
2000
3000 4000
1000 CUBIC FEET
5000
6000
7000
8000
-------
-------
necessitating submergence of 2.9 acres up to elevation 923 feet. These elevations are based
upon existing topography, whereas it would be necessary to improve the ground prior to
utilization as a reservoir.
A primary advantage of overflow storage is the modulation of peak flow rates. In general,
the larger reservoir yields the greater modulation. The number and total capacity of
treatment units need only meet the modulated peak flow rate. For those storms entirely
contained in the reservoir, as is the case for the "design storm," a major constraint on
treatment capacity is the desirability of rapidly providing storage for subsequent overflows.
Furthermore, rapid emptying of the reservoir will prevent problems that may occur due to
depletion of oxygen resources. Whatever the detention time, a certain amount of solids will
settle, both organic and inorganic. Due to the organic nature of part of the solids, and the
open reservoir employed for storage, solids should be removed from the reservoir.
Successful removal of solids has been reported at similar installation in Chippewa Falls,
Wisconsin (Banister, 1969), utilizing a street sweeper. Removal by automatic mechanical
equipment would be desirable, however, the irregular shapes and large surface areas of the
reservoirs would require non-standard equipment at considerable expense.
Construction costs for the reservoir and dam at the Confederate Avenue and Boulevard
overflow sites on Intrenchment Creek are estimated at $600,000. This figure includes land
at $15,000/acre. Combined sewer overflows are assumed to fill the reservoir and overtop the
dam under conditions exceeding design capacities. Costs exclude handling and treatment
expenses, which are considered subsequently. A similar construction estimate for the
McDaniel Street overflow storage site is $125,000. A dam at this site is unnecessary since
the downstream end of the reservoir abuts against a considerable volume of fill underlying
Interstate 85 (South Expressway). An overflow weir and existing culvert may be used to
drain the reservoir after a storm.
Once the combined sewer overflows are stored, a number of alternatives are available for
treatment and release to the receiving streams. The feasibility, economics and benefits of
each are considered in the following paragraphs.
Alternate A
The first approach comprises storage and solids removal in the reservoir followed by
physical treatment of the overflows and release. The two-week design storm of five-hour
duration may be expected to yield 13.1 million gallons of combined sewer overflow to the
Intrenchment Creek reservoir and 3.6 million gallons to the McDaniel Street reservoir.
Lesser volumes would be expected from shorter duration storms, as shown in Figures 28 and
29.
In order to obtain full benefit of the reservoirs, they should be emptied as soon as possible
after cessation of runoff. The requisite high treatment capacities increase costs significantly.
However, the higher capacities also permit treatment of greater fractions of overflows from
139
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larger storms, and reduce the need for aerating stored overflows. Table 26 presents the
percentage of 1969 overflow volume that would have been treated in the Intrenchment
Creek reservoir if designed to contain a two-week storm. Options A, B and C represent 2—,
5- and 10-hour durations from cessation of overflows to reservoir emptying, assuming
treatment begins at commencement of overflows.
TABLE 26
Storm
Recurrence
Interval
2 week
4 week
6 month
Percent Overflow Volume Treated
Duration
(hours)
1
2
5
1
2
5
10
2
5
10
Option
100
100
100
100
100
100
100
33
42
42
A Option B
100
100
100
100
97
100
100
31
38
37
Option C
100
100
100
100
90
100
100
30
35
38
Required Treatment Capacity (mgd)
35
26
19
Option A enables treatment of about 88 percent of the total annual overflow volume
passing through the reservoir. Options B and C will enable treatment of a slightly lower
percentage, due to the infrequent occurrence of storms separated by time intervals too short
to permit complete draining of the reservoir. An estimate of 80 percent treatment with
Option C appears reasonable.
Overflows are initially saturated with dissolved oxygen. Unless they are released at a
reasonable level of DO, impact upon the receiving stream of the treated overflows will be
deleterious due to the decrease in streamflow after the storm. Under average conditions it is
estimated that the stored volume may become anaerobic within several hours of overflow
cessation. However further lab work is required to confirm this estimate, including
determination of the deoxygenation rate constant. In order to maintain effluent from the
reservoir at a DO of at least five mg/1, prechlorination or aeration will probably be necessary
for Option C. Option B may require similar facilites, but these should be unnecessary for
Option A.
140
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Aunough further tests are required to confirm the estimate, prechlorination would entail
application of an estimated 30 mg/1 to the reservoir influent. Preliminary investigation of
this approach indicated that due to the high flow rates encountered, prechlorination would
be infeasible. The large drainage areas tributary to the reservoirs cause high flow rates from
even small storms. Diffused and mechanical surface aeration are also considered infeasible,
due to the high velocities that may occur and the low transfer efficiencies encountered at
high DO levels. However, introduction of oxygen to the effluent conduit in either diffused
or dissolved form should enable maintenance of high DO levels. The partial pressure driving
force will be maximized by introduction of oxygen at this point and flow rates will be
steady and relatively low. A downstream monitor would enable automatic adjustment of
oxygen feed rate to meet the required DO level. Further lab studies and detailed
information concerning the oxygenation process will enable assessment of the optimal
procedure and expected annual operating cost.
Treatment of combined sewer overflows is best accomplished by physical rather than
biological means, due to the short detention times generally possible. Development of
reliable cost estimates for large scale facilities is hampered by the lack of such facilities to
date. Two basic processes are considered: screening and flotation. However, several
variations reported in the literature indicate that a major factor in costs and efficiencies of
these processes is the screen mesh size.
Microstraining of overflows has been proposed as an economically competitive alternate to
separation of combined sewers (Keilbaugh, Glover and Yatsuk, 1969). Utilizing a screen
mesh of 23 microns, preceded by a heavy solids trap and bar screen, this process achieved
removal of suspended solids averaging 80 to 90 percent, and volatile solids averaging 70
percent. However, BOD removal is unpredictable. It is possible that the large surface area of
small particles leaving the microstrainer enhances bacterial action. Such an effect would
increase efficiency of effluent chlorination. If chlorination is not implemented, however, the
shock impact of the treated flows upon the South River might be substantial. Based upon an
11 —acre study area without overflow storage, costs of microstraining and chlorination were
estimated at $10,500 to $12,800 per acre served. Expansion of these costs to an area of
3,400 acres is of little value, however rough estimates of this process suggest that it may be
implemented for 40 to 50 percent of separation costs.
Fine screening of overflows with a 105 micron, rotary, vibratory screen has been reported to
remove 99 percent of floatable and settleable solids, 34 percent of total suspended solids,
and 27 percent of COD (Cornell, Rowland, Hayes and Merryfield, 1970). BOD reduction
was not calculated. Estimated cost of a 25 mgd screening facility is $538,000. Annual
operation and maintenance costs are estimated at $18,500. Total annual cost, including debt
service, is $59,500, based upon a design life of 25 years with amortization at 6.5 percent.
Mason (1969) studied the possibility of combining screening and dissolved air flotation.
Using a 297 micron rotary screen preceded by a 1/2 inch barrack and excluding flotation,
this process achieved a 22 percent BOD reduction, 28 percent COD reduction, 27 percent
suspended solids reduction and 26 percent volatile suspended solids reduction. Addition of
141
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flotation with chemical flocculation increased removal efficiencies for BOD and COD to 51
and 53 percent, respectively. TSS and VSS removals averaged 68 and 65 percent. Capital
costs were estimated at $5,000 to $8,000/mgd for plants exceeding 50 mgd. Operating costs
should approximate 4.5 cents/1,000 gallons.
The same combination of processes was studied by Rhodes Technology Corporation (1970)
utilizing a 32—mesh gyratory screen followed by a series of hydrocyclones. Alum and a
polyelectrolyte were added to the influent of the flotation tank. Results indicated that this
process will remove 84 percent of the suspended solids passing the screen, and 42 percent of
the BOD. At capacities greater than 8 mgd, operating and maintenance costs increase
substantially such that whenever land is available, primary clarification is less expensive. In
this application the land is not available; moreover, the reservoir will act as a primary
clarifier to some extent. Total annual cost of treatment for options A, B and C with this
approach, assuming 25 year bonds at 6.5 percent, is estimated at $75,000, $57,000 and
$42,000, respectively, at Intrenchment Creek. Similar estimates for the McDaniel reservoir
would be $26,000, $20,000 and $16,000. All estimates exclude oxygenation costs, which
cannot be determined at this time.
Certain factors are pertinent to any treatment processes at the reservoir sites. Detention
time in the reservoirs will induce settling of solids, although settling tests on composite
samples of combined sewer overflows are necessary to determine percent removal of solids
and BOD. It is estimated that 20 percent BOD removal and 60 percent solids removal may
be possible within the reservoirs due to settling. Solids removed by treatment at
Intrenchment Creek may be discharged to an interceptor along the north bank of the
reservoir site. Similarly solids removed by the McDaniel treatment unit may be discharged to
an existing sewer at the site.
Consideration of the four treatment alternatives is complicated by the lack of comparability
of cost information. However, for a 25 mgd facility, the cost of microstraining would be
very high and BOD removal unpredictable. Fine screening alone would achieve 27 percent
COD reduction for a total annual cost of $59,500. Coarse screening and dissolved air
flotation would achieve 42 percent BOD reduction for a total annual cost of $55,000. It
must be emphasized that these costs are rough estimates only, and are not strictly
comparable. However, they indicate the approximate efficiency and cost of existing
treatment alternatives for combined sewer overflows. Consequently the last approach is
selected for subsequent benefit—cost calculations.
The total cost of alternative A is shown in Table 27 for the three reservoir detention times.
It is apparent from the Table that the least costly option, the 10—hour detention time, has
the most favorable cost-benefit ratio. It may therefore be concluded that storage of
combined sewer overflows in a reservoir with capacity to contain all two-week storms,
followed by screening, dissolved air flotation and chlorination at a capacity designed to
empty the reservoir within 10 hours of overflow cessation, will enable removal of
approximately 53 percent of treated overflow BOD and 87 percent of suspended solids, at a
cost of about $0.17/lb BOD.
142
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TABLE 27
Reservoir Site
Intrenchment Creek Reservoir
Capital Cost ($)
Amortized Annual Cost ($)
Cleanup Annual Cost ($)
Treatment Annual Cost ($)
Chlorination Annual Cost ($)
Total Annual Cost ($)
(excluding oxygenation)
Annual Flow Treated (%)
BOD Removal Efficiency (%)
BOD Removal (Ibs/year)
Cost-Benefit Ratio ($/lb BOD)
McDaniel Street Reservoir
Capital Cost ($)
Amortized Annual Cost ($)
Cleanup Annual Cost ($)
Treatment Annual Cost ($)
Chlorination Annual Cost
Total Annual Cost ($)
(excluding oxygenation)
Annual Flow Treated (%)
BOD Removal Efficiency (%)
BOD Removal (Ibs/year)
Cost-Benefit Ratio ($/lb BOD)
Detention Time After Cessation of Overflow (hours)
2
600,000
49,000
2,000
75,000
29,000
155,000
88
53
762,000
0.20
125,000
10,000
1,000
26,000
10,000
47,000
88
53
208,000
0.22
5
600,000
49,000
2,000
57,000
29,000
137,000
85
53
736,000
0.19
125,000
10,000
1,000
20,000
10,000
41,000
85
53
201,000
0.20
10
600,000
49,000
2,000
42,000
28,000
121,000
80
53
692,000
0.17
125,000
10,000
1,000
16,000
9,000
36,000
80
53
189,000
0.19
NOTE: Amortization over 25 years at 6.5 percent
143
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Alternate B
A possible alternative to treatment of stored overflows at the reservoir sites is treatment at
the existing treatment plants. Retention of overflows in the reservoirs for a few hours will
permit grit and some solids to settle. Release of flow to the existing sewer lines can be
remotely controlled according to sewage flows at the treatment plants. Peak hydraulic
capacities of the plants can be utilized at night when sewage flows are low, and at times
during the day when flows are less than peak ratings.
Design capacities at the Intrenchment Creek and South River wastewater treatment plants
are 20 and 18 mgd respectively. At these rates BOD removal is about 83 percent at both
plants. Hydraulic overloading will cause BOD removal efficiency to drop, such that flows at
250 percent of design capacity may yield approximately 50 percent BOD removal.
Additional clarification units would permit higher treatment of overflows at these flow
rates.
With the Intrenchment Creek wastewater treatment plant operating at design capacity on
dry weather sewage flow, a surcharge of combined sewer overflow yielding a steady
hydraulic rate through the plant of 47 mgd would permit emptying of the Intrenchment
Creek reservoir in 12 hours. During this period it is estimated that BOD removal within the
plant would average 50 percent. Expansion of facilities would permit higher BOD removal at
this flow rate. Additional studies would enable determination of whether the 12—hour
detention time might be extended, permitting lower hydraulic loading rates.
When design capacity of the South River wastewater treatment plant is reached, a surcharge
of storm overflow yielding a steady flow rate of 25 mgd will permit emptying of the
McDaniel Street reservoir in 12 hours. BOD removal efficiency would fall to about 73
percent.
Although this approach would enable treatment of combined sewer overflows, it will reduce
the treatment efficiency for sewage entering the plants during the 12 hours of peak flows. It
is estimated that net BOD reduction at the Intrenchment Creek reservoir and wastewater
treatment plant will be -423,000 Ibs/year, indicating that the loss in treatment efficiency
offsets any advantage gained by treating the overflow. The net BOD reduction at the South
River treatment plant is 48,000 Ibs/year.
This approach is therefore unrealistic for treatment of flows from Intrenchment Creek
reservoir. Application to flows from the McDaniel Street reservoir would yield a
cost-benefit ratio of approximately $0.23/lb BOD.
Alternate C
BOD reduction due to storage, settling of solids and chlorination constitutes an additional
pollution abatement alternative. As mentioned previously, further tests are necessary to
144
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determine settling and BOD removal characteristics; however, 20 percent BOD removal is a
reasonable estimate. Release of stored overflows to the receiving stream may necessitate
oxygenation of the effluent to maintain high DO levels. Although it is probable that
decreased detention times will reduce the need for oxygenation at the expense of a
reduction in BOD removal, the nature of the trade-off cannot be determined at this time.
Implementation of this approach at the Intrenchment Creek reservoir site should enable a
reduction of BOD in all flows passing through the reservoir, since even flows overtopping
the dam will deposit some solids while progressing through the reservoir. However BOD
reduction under such unsteady conditions will probably not exceed 10 percent. Since 57
percent of the total annual BOD from combined sewer overflows may be contained in a
reservoir designed to store a two-week storm, it may be assumed that the remaining 43
percent will receive 10 percent BOD removal. Consequently at this site, an estimated
256,000 Ibs BOD/year may be removed. The resulting cost-benefit ratio, excluding costs of
oxygenation, is $0.31/lb BOD.
The McDaniel Street reservoir, operated in the same fashion, would remove an estimated
70,000 Ibs BOD/year. Excluding oxygenation costs, the cost—benefit ratio would be
$0.29/lb BOD removed.
Evaluation of Alternative Pollution Abatement Schemes
Although other approaches to the abatement of pollution from combined sewers have been
discussed in the literature, those discussed previously in this section are considered most
applicable to circumstances in the City of Atlanta. The various alternatives are listed in
Table 28 along with their cost—benefit ratios and percentage removal of total annual BOD
from combined sewer overflows and intercepted flows. The latter quantity is estimated at
2,767,000 pounds.
The table reveals the desirability of regulator modification, which will reduce total annual
BOD released to the South River due to combined sewers by 25 percent at a total estimated
capital cost of $50,000. Storage and treatment of overflows at both reservoir sites by
screening, dissolved air flotation and chlorination will increase to 57 percent the removal of
total annual BOD attributable to combined sewers, at an annual cost of $165,000. However,
53 percent may be removed for $140,000/year by omitting treatment of overflows stored at
the McDaniel Street reservoir. The cost-benefit ratio of the latter approach is only slightly
higher than that of the former.
145
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TABLE 28
Alternative Cost-Benefit Ratio BOD Removed
(S/lb BOD) (Percent)
Regulator Modification (1C) 0.0057 18
Regulator Modification (M) 0.0074 7
Treatment Alt. A (1C) 0.17 25
Treatment Alt. A (M) 0.19 7
Treatment Alt. B (ICTP) —
Treatment Alt. B (SRTP) 0.23 2
Treatment Alt. C (1C) 0.31 9
Treatment Alt. C (M) 0.29 3
Sewer Separation 1.82 60
NOTE: 1C — Intrenchment Creek Reservoir
ICTP — Intrenchment Creek Wastewater Treatment Plant
M - McDaniel Street Reservoir
SRTP - South River Wastewater Treatment Plant
It is emphasized that the costs and efficiencies utilized in this section involve a significant
amount of engineering judgment, necessitated by the uniqueness of the proposed solutions
as well as the lack of detailed information available in the literature. However, reasonable
estimates of costs and efficiencies of alternate schemes have been made. Based upon these
estimates, the optimal solution includes modification of regulators at the overflow points,
construction of two reservoirs to store overflows from combined sewers, and treatment of
the stored volumes with screening and dissolved air flotation. At an estimated total annual
cost of $165,000, this solution will remove 57 percent of the annual BOD released to the
South River due to combined sewer overflows and intercepted flows. It will also alleviate
the considerable shock impact of flows from small, high frequency storms.
146
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Abatement of Pollution From Storm-Sewered Areas
Consideration was given to ways of reducing the pollution load due to storm runoff in areas
served by separate sewers. Compared to that from combined sewer areas, the pollution
averages approximately 55 percent of the total annual BOD/acre. However, the relatively
large acreage served by storm sewers yields considerably greater annual BOD. A rough
estimate is that total annual BOD from combined sewer areas constitutes 30 to 40 percent
of the total annual BOD from that part of the City of Atlanta contained in the study area
and tributary to station 8 at Bouldercrest Road.
The study area is characterized by a general lack of suitable storage sites for the large flow
volumes yielded by even small storms. Without storage, treatment must be geared to handle
these volumes at very high flow rates. Preliminary investigations of treatment alternatives
for combined sewer overflows under such conditions revealed the present infeasibility of
this approach. The high costs of treatment, the low efficiencies of BOD removal and the
relatively low waste strength combined to indicate that treatment of storm runoff is not
feasible in the study area at this time.
147
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SECTION XIII
KEY PERSONNEL
Dr. Manuel R. Vilaret
Mr. Robert E. Rader
Mr. R. David G. Pyne
Black, Crow and Eidsness, Inc.
Post Office Drawer 1647
Gainesville, Florida 32601
Black, Crow and Eidsness, Inc.
1261 Spring Street, Northwest
Atlanta, Georgia 30309
Black, Crow and Eidsness, Inc.
Post Office Drawer 1647
Gainesville, Florida 32601
Mr. Asa B. Foster
Environmental Protection Agency
Water Quality Office
1421 Peachtree Street, Northeast
Suite 300
Atlanta, Georgia 30309
Mr. William Rosenkrantz
Mr. Frank Condon
Environmental Protection Agency
Water Quality Office
Storm Water and Combined Sewers
R & D Grants Section
Stop 327
Washington, D. C. 20242
Environmental Protection Agency
Water Quality Office
Storm Water and Combined Sewers
R & D Grants Section
Stop 327
Washington, D. C. 20242
149
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SECTION XIV
ACKNOWLEDGEMENTS
Grateful appreciation is due the City of Atlanta Department of Public Works, Water
Pollution Control Division, and the Georgia State Water Quality Control Board for their
assistance during this study.
151
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SECTION XV
REFERENCES
1. Banister, A.W., "Storage and Treatment of Combined Sewage as An Alternate to
Separation," Presented at Seminar on Storm and Combined Sewer
Overflows, Edison, N. J. (November 1969).
2. Bendat, J.S. and Piersol, A. G., Measurement and Analysis of Random Data, John
Wiley & Sons, Inc., New York (1966).
3. Burgess and Niple, Limited, "A Study of Stream Pollution From Combined Sewer
Overflows and Feasibility of Alternate Plans for Pollution Abatement in
Bucyrus, Ohio," Report to Federal Water Quality Administration (November
1969).
4. Caster, A.D. and Stein, W.J., "Pollution From Combined Sewers, Cincinnati, Ohio,"
Presented at ASCE National Water Resources Engineering Meeting, Memphis,
Tennessee (January 1970).
5. Cornell, Rowland, Hayes, and Merryfield, "Rotary, Vibratory Fine Screening of
Combined Sewer Overflows," Report to Federal Water Quality
Administration (March 1970).
6. Eagleson, P.S., Mejia, R. and March, F., "Computation of Optimum Realizable Unit
Hydrographs," Water Resources Research, 2, No. 4 (1966).
7. Engineering Science, Inc., "Characterization and Treatment of Combined Sewer
Overflows," Report to Federal Water Quality Administration (November
1967).
8. Evans, L.S., Geldreich, R.S., Weibel, S.R. and Robeck, G.G. "Treatment of Urban
Stormwater Runoff," Journal, Water Pollution Control Federation, 40, 5
(1968).
9. Fair, G.M., Geyer, J.C. and Okun, D.A., Water and Wastewater Engineering, Vol. 1,
John Wiley & Sons, Inc., New York (1966).
10. Guarino, C.F. Radziul, J.V. and Greene, W.L., "Combined Sewer Considerations by
Philadelphia," Journal, Sanitary Engineering Division ASCE, Vol. 96, SA—1
(February 1970).
153
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11. Keilbaugh, W.A., Glover, G.E. and Yatsuk, P.M., "Microstraining - With Ozonation
or Chlorination — of Combined Sewer Overflows," Presented at Seminar on
Storm and Combined Sewer Overflows, Edison, N.J. (November 1969).
12. Mason, D.G., "The Use of Screening/Dissolved Air Flotation for Treating Combined
Sewer Overflow," Presented at Seminar on Storm and Combined Sewer
Overflows, Edison, N.J. (November 1969).
13. McKee, J.E. and Wolf, H.W., Editors, "Water Quality Criteria," California State
Water Quality Control Board Publication No. 3-A (1963).
14. Rhodes Technology Corporation, "Dissolved Air Treatment of Combined Sewer
Overflows," Report Presented to Federal Water Quality Administration
(January 1970).
15. Schroepfer, G.J., Robins, M.L. and Susag, R.H., "A Reappraisal of Deoxygenation
Rates of Raw Sewage, Effluents, and Receiving Waters," Journal, Water
Pollution Control Federation, 32, 11, 1212 (November 1960).
16. U.S. Army Corps of Engineers, "Flood Plain Information — Metropolitan Atlanta,
Georgia — Headwaters South River," Report to Atlanta Region Metropolitan
Planning Commission (May 1967).
17. U.S. Army Corps of Engineers, "Flood Plain Information — DeKalb County, Georgia
- Intrenchment, Sugar, Doolittle and Doless Creeks," Report to DeKalb
County (April 1968).
18. Wallace, J.R. and Reheis, H.F., "Hydraulic Properties of the South and Flint Rivers
in the Vicinity of Atlanta, Georgia," Report to the Federal Water Quality
Administration (February 1969).
19. , Standard Methods for the Examination of Water and
Wastewater, 12th Edition, American Public Health Association, Inc., New
York (1965).
154
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SECTION XVI
APPENDICES
-------
APPENDIX A
COST ESTIMATE - SYSTEM SEPARATION
(Based on construction of separate
sanitary sewers and reconnection)
AREA NO. 1 - CONFEDERATE AVENUE
A. Within the Public Right-of-Way Cost
Item
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
Description
8" Pipe
10" Pipe
12" Pipe
15" Pipe
18" Pipe
24" Pipe
30" Pipe
Earth Excavation
Solid Rock Excavation
Semi— decomposed Rock
Manholes
Pavement Replaced
Reconnect Services
Railroad and Highway
Crossings
Estimated
Quantity
33,050
1,800
1,700
2,100
2,200
3,750
4,350
115,780
11,580
23,160
320
42,000
1,260
(8)
Unit
l.f.
l.f.
IS.
l.f.
l.f.
l.f.
l.f.
c.y.
c.y.
c.y.
each
sq. yd.
each
Unit
Price
$ 4.00
5.00
6.00
7.00
9.00
13.00
17.00
4.00
16.00
10.00
500.00
10.00
100.00
Amount
$ 132,200.00
9,000.00
10,200.00
14,700.00
19,800.00
48,750.00
73,950.00
463,120.00
185,280.00
231,600.00
160,000.00
420,000.00
126,000.00
36,000.00
Add 60% for work in highly developed areas
with interfering utilities and uninterrupted
service requirement
Estimated Construction Cost
Engineering contingencies, etc. (20%)
Cost within the right—of—way
$1,930,600.00
1,158,360.00
3,088.960.00
617,790.00
$3,706,750.00
155
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1.
B. Within Private Property Cost
Modification of building,
plumbing and service
connections
Total Cost of Separation,
Cost per acre. Area No. 1
1,260
Area No. 1
each
$1,800.00
A. Within the public right-of-way
AREA
B. Within private property
Total cost per acre
NO. 2 - BOULEVARD
$2,268,000.00
$5,974,750.00
$ 3,283.00
$ 2,009.00
$ 5,292.00
A. Within the Public Right-of-Way Cost
Item
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
Description
8" Pipe
10" Pipe
12" Pipe
15" Pipe
18" Pipe
24" Pipe
30" Pipe
36" Pipe
42" Pipe
48" Pipe
Earth Excavation
Rock Excavation
Semi— decomposed
Rock
Manholes
Pavement replaced
Reconnect services
Estimated
Quantity
136,100
11,475
12,100
6,475
5,175
6,725
3,350
2,250
3,325
2,400
468,475
46,850
93,700
1,300
126,250
5,200
Unit
l.f.
l.f.
l.f.
l.f.
l.f.
l.f.
l.f.
l.f.
l.f.
l.f.
c.y.
c.y.
c.y.
each
sq. yd.
each
Unit
Price
$ 4.00
5.00
6.00
7.00
9.00
13.00
17.00
22.00
27.00
33.00
4.00
16.00
10.00
500.00
10.00
100.00
Amount
$ 544,400.00
57,375.00
72,600.00
45,325.00
46,575.00
87,425.00
56.950.00
49,500.00
89,775.00
79,200.00
1,873,900.00
749,600.00
937,000.00
650,000.00
1,262,500.00
520,000.00
156
-------
Estimated Unit
Item Description Quantity Unit Price
1 7. Railroad and Highway
crossings (23) L.S.
Add 60% for work in highly developed areas,
interfering utilities and uninterrupted service
requirement
Estimated Construction Cost
Engineering contingencies, etc. (20%)
Cost, within the right-of-way
B. Within Private Property Cost
1 . Modification of building,
plumbing and service
connections 5,200 each $1,800.00
Total Cost of Separation, Area No. 2
Cost per acre. Area No. 2
A. Within the public right— of— way
B. Within private property
Total cost per acre
AREA NO. 3 - MCDANIEL STREET
A. Within the Public Right-of-Way Cost
Estimated Unit
Item Description Quantity Unit Price
1. 8" Pipe 42,550 l.f. $ 4.00
2. 10" Pipe 3,800 l.f. 5.00
3. 12" Pipe 3,250 l.f. 6.00
4. 15" Pipe 2,300 l.f. 7.00
5. 18" Pipe 2,475 l.f. 9.00
Amount
$ 158,000.00
$7,280,125.00
4,368,075.00
11,648,200.00
2,329,640.00
$13,977,840.00
$9,360,000.00
23,337,840.00
5,773.00
3,865.00
$ 9,638.00
Amount
$ 170,200.00
19,000.00
19,500.00
16,100.00
22,275.00
157
-------
Estimated Unit
Item Description Quantity Unit Price
6. 21" Pipe 1,700 l.f. 10.50
7. 24" Pipe 1,925 l.f. 13.00
8. Earth Excavation 141,520 c.y. 4.00
9. Rock Excavation 9,900 c.y. 16.00
10. Semi— decomposed
Rock 24,060 c.y. 10.00
11. Manholes 380 each 500.00
12. Pavement replaced 52,000 sq. yd. 10.00
13. Reconnect service 1,650 each 100.00
1 4. Railroad and Highway
Crossings (45) L.S.
Add 60% for work in highly developed areas,
with interfering utilities and uninterrupted
service requirements
Estimated Construction Cost
Engineering contingencies, etc. (20%)
Cost within the right-of-way
B. Within Private Property Cost
1 . Modification of building,
plumbing, and service
connections 1,650 each $1,800.00
Total cost of separation, Area No. 3
Cost per acre, Area No. 3
A. Within the public right— of— way
B. Within private property
Total cost per acre
Amount
17,850.00
25,025.00
566,080.00
158,400.00
240,600.00
190,000.00
520,000.00
165,000.00
180,000.00
$ 2,310,030.00
1 ,386,020.00
3,696,050.00
739,210.00
$ 4,435,260.00
$ 2,970,000.00
$ 7,405,260.00
$ 4,584.00
3,069.00
$ 7,653.00
158
-------
AREA NO. 3A - JOYLAND PARK AREA (Smaller combined sewer area
located east of 1-75 at University Avenue Exit)
A. Within the Public Right-of-Way Cost
Estimated Unit
Item Description Quantity Unit Price
1- 8" Pipe 2,825 l.f. $ 4.00
2. 10" Pipe 1,750 l.f. 5.00
3. Earth Excavation 10,675 c.y. 4.00
4. Solid Rock Excavation 1,075 c.y. 16.00
5. Semi— decomposed
Rock 2,150 c.y. 10.00
6. Manholes 22 each 500.00
7. Pavement Replaced 1,100 sq. yd. 10.00
8. Reconnect Service 20 each 100.00
9. Railroad and Highway
Crossings (3) L.S.
Add 60% for work conditions interfering
utilities and uninterrupted service
requirement
Estimated Construction Cost
Engineering contingencies, etc. (20%)
Cost within the right— of —way
B. Within Private Property Cost
1. Modification of building,
plumbing, and service
connections 20 each $1,800.00
Total cost of separation, Area No. 3A
Cost per acre. Area No. 3A
A. Within the public right-of-way
B. Within private property
Total cost per acre
Amount
$ 11,300.00
8,750.00
42,700.00
17,200.00
21,500.00
11,000.00
11,000.00
2,000.00
18,000.00
$ 143,450.00
$ 86,070.00
229,520.00
45,900.00
$ 275,420.00
$ 36,000.00
$ 311,420.00
$ 1 ,420.00
185.00
$ 1,605.00
159
-------
SUMMARY
Area No. 1 , Confederate Avenue
Area No. 2, Boulevard
Area No. 3, McDaniel Street
Area No. 3A, Joyland Park
Total Costs
Within the
right-of-way
$ 3,706,750
13,977,840
4,435,260
275,420
$22,395,270
Within Private
Property
$ 2,268,000
9,360,000
2,970,000
36,000
$14,634,000
Total
Cost
$ 5,974,750
23,337,840
7,405,260
311,420
$37,029,270
Average cost/acre
$ 4,753
$ 3,106
$ 7,859
160
-------
APPENDIX B
UNIT HYDROGRAPH
PROGRAM PACKAGE
This program computes the unit hydrograph using the Wiener-Hopf equations and the MPS
linear programming routine on the IBM 360. At the present time this is the best way of
applying a linear formulation to nonlinear data. Due to the nonlinear characteristics of
urban watersheds, different unit hydrographs will be obtained for different storms in the
same drainage basin. There is no valid way of averaging them.
Following is a summary of the input required for HYDRO:
Format
a. the storm identification number 16
b. length of the rainfall record, N 13
c. length of the runoff record, M 13
d. rainfall record ( F(I), 1=1,. . .N) 20F4.2
e. runoff record ( G(I), 1=1,. . .M) 10F8.2
HYDRO receives as input only one storm record at a time. The last card in the data deck
must be the storm number 000000, in I 6 format, or a blank card. Data is inserted at the
end of stage A, after the card //GO.SYSIN DD *.
Time increments are of arbitrary length, but must be the same for both rainfall and runoff.
Both records must start at the same time, even though runoff readings may initially be zero.
Array dimensions should be checked to ensure adequate machine storage allocation.
In stage A the program calculates the autocorrelation function, PHIFF, and the
cross—correlation function, PHIFG, and stores the output in the computer data cell in a
format suitable for input to stage B, the MPS linear programming routine. Immediately after
execution of stage A, control cards for stage B are read in, followed by the data stored in
the data cell. The unit hydrograph coordinates are contained in the output of stage B.
Pertinent results are listed under the heading "SECTION 2 - COLUMNS." For instance,
HI01 and HI02 are the labels attached to the first and second unit hydrograph coordinates.
The values of these coordinates are shown under the column "ACTIVITY." In all but the
161
-------
simplest storms, some coordinates will have zero value. This is a direct result of the method
of analysis, which attempts to constrain unit hydrograph coordinates to be nonnegative.
Reference: Eagleson, P.S., Mejia, R., and March, F., "Computation of Optimum Realizable
Unit Hydrographs." Water Resources Research, 2, No. 4, 1966 (pp. 755-764)
162
-------
FORT RAN
0001
0002
0003
000 4
0 005
0006
0007
0008
o oo v
0010
0011
0012
IV G LEVEL
C
C
1
2
3
5
10
15
1, MOO 3 MAIN DATE = 70OB4 O<9/48/03 PAGr OT01
PROGRAM TO CALCULATE UNIT HYOROGRAPH USING WIENER HOPF EQUATIONS
AND N"PS LINhAR PROGRAMMING ROUTINE ON IBM 3faO
COMMON F(45),G( 80) , PHIFF (45) .PHITGOO )
DIMENSION A( 120,30) ,MS( 120)
REAC( 5. 2 )NSTOUM
FQRMATC 16 )
I F(N STORM) 120 ,120,3
REALM £,5)N,M
FCHMAT< I 3.SX.I3)
READ< 5. 10 X F( I ) .1 =1 ,N)
FOKMAT< 20F4.2 )
REAC(5.15XG(I).I=1,M)
FORMAT( I OF6.2 )
LL=2*M-N-M
001 J L^=l» + 1
0 01 4 LH = «-N«- 1
0015
0016
0017
0018
001 9
0020
0 02 1
0022
0 023
0024
0025
0 026
0 C27
0 028
D 029
0 030
0 03 1
0 032
0033
0 034
D 035
0 036
0037
0038
O 039
0040
004 1
0 042
0 043
0 04 4
0 045
0046
0047
0 048
0 049
0 050
0 Oj 1
0052
4
34
35
36
300
59
60
64
65
66
67
70
71
75
76
DO 4 K=1,LL
DO 4 J=1,M
A (K , J )=0.0
CALL AUTO(N)
CALL CWOSS(M,N)
DO 36 K=1,LR
DO 2t J=1.M
LN=J-K
LNN=I AUS(LN)-H
IF(LNN-N)35.35,34
A ( K, J ) = 0.0
GO TO 36
A (K ,J )=PHIFF( LNN)
CON T INUft
WRI TE (6, 3 00 )N STORM
FCRMAT( 1H1 . I 6)
WR ITE{ 9. 55)
FORMAT( 18Hr>IAME DATA)
WR ITE(9,60)
FORMA T( "ROWS • )
DC C£ 1=1, M
WRITEC9, 64) MS(I )
FORMAT( IX , «E • ,2X, • J« ,13)
CONT INUE
WR ITE(9,66)
FCRVAT( 1 X, -N • ,2X. 'Z •)
FCRrtATt "COLUMNS' 1
J J=l
DO 60 K=1,LL
00 75 J=1.M
IF(K-M-l-N-l) 70,70,76
WRITt<9.71)MS(K),MS(J).A(K.J)
FORfAT(4X,'Ht,I3.6X,«J<.I3, T26 ,F9 .4 )
CONT INUt
GO TO 80
WRI TE(9. 77)MS(K)
-------
FO&THAN iv G LEVEL t. KCD 2
MAIN
DATfc = 70084
09/48/0J
PA 3 i 0012
0033
00b4
77
FOHMAT(4X.«H'.13.6X,«Z'.T2''.M.O')
N ELACK=K+100
O Poll
0 ObO
WR I TE< 9i85 )NSLAC K. MS( JJ)
65 FCRMAT(4X.'H*.I3.6X.'J'.13.T29.'1.0')
JJ=JJ+l
JK> C UNT I t\UF
WH I Th(Sl.yO)
90 FORMAT('RHS•)
0 Oo 1
0 Oo2
0 0<>3
0 Oo4
OOb 5
0 Oo o
DC ^£ J= 1 ,M
WRI 1t(9.?2)MS(J) ,PH1FG
00/3
0 074_
6 ci r^T
0 076
120
GC TO 1
CONTINUE
"STUP
END
-------
FORTRAN IV G LtVEL 1. MOD 3
AUTO
DATE = 7008*
09/48/03
PAGE 0001
000 1
0 002
0003
0 CJ4
0 00 5
0 OJ 6
0 007
0008
0009
0010
0011
0012
0013
0014
SLdMCoTINE AUTO(N)
CCWWQN F(4i)'.G(aO)tPHIFF(45) ,PHllFG(30)
L AG = 0
00 JO J=1,N
S LM = 0.0
DO 25 1= 1 .N
I I=I-LAG
IF( I I )2S, 25, 24
24 SLM = SUM-fF( I )*F( I I )
25 CONTINUE
PI- IFF( J ) = SUM
30 L AG=LAG+1
HE TLRN
I'ND
FORTRAN IV G LEVaL li NCD 3
CROSS
DATE = 700»4
09/48/03
PAGE 0001
000 1
0 002
0 003
0 00 4
SUDRCUTINE CROSS(M.N)
CCVWON F( 45) tG( 80) .PHIFF (45) .PHIFGOO)
L C=C
OO 5C J= 1 (
0 005
OOJ6
0 00 7
ocoa
0 00 9
0010
0011
001 2
0 01 J
0 Cl 4
0 01 5
45
46
47
50
TOTAL=0. C
OC 47 1= 1 ,M
LS=I-LC
IF( LS )47,47,45
1F(LS-N )46t46.47
TCTAL=TOTAU+F(LS)*G( I >
CONT INUE
PhIFG(J )=TOTAL
LC=LC+1
l< liTOHN
END
-------
EXECUTOR,
MPS/360 V2-M6
"AciL
11
iECTION 2 - COLUMNS
NUMBER .COLUMN.
AT
...ACTIVITY INPUT COST.
.LUKF.H LIMIT. ..UPPER LIMIT,
.RCOUCFO C 3 ST .
1 4
15
16
1 7
i a
1 9
20
2 1
22
23
24
25
26
27
28
29
30
J 1
32
J 3
J4
J5
36
37
H 10 1
M102
H103
H104
H 105
H 106
H 137
H 108
H 109
HI 1 0
Hill
HI 1 2
H 1 3
H 1 4
H 1 5
HI 6
HI 7
H 1 1 8
H 1 1 9
H 120
H12 1
H122
H123
H 124
as
as
OS
BS
BS
BS
US
BS
as
BS
as
BS
LL
LL
LL
LL
LL
LL
LL
LL
LL
LL
LL
LL
20.00000
216. 00000
56.00000
20. 00000
I 1 .40000
a. aoooo
6.30000
6. 00000
5.20000
4.40000
4. 20000
4.00000
,
•
*
•
*
•
^
• •
• .
, m
•
•
I .00000
1.00000
1 .00000
1 .00003
1.00000
1.00000
1.00000
1 .00000
1 .00000
1 .00000
1.00000
1 . 00000
NONE
NONF
NONF
NONE
NONE
NO-JE
NONE
NONE
NONE
NONE
NONt
NONt
NDNE
N3-JE
NONE
NONE
NONE
NDNF
NONF
NONE
NONF.
.
%
•
•
•
t
i . c^ooo
1 . OOii DO
1 . CO "30
1.00000
1 .C OHOO
i . o o o r> o
i . o o n o o
1 .C't'lOO
i . r< TOO
1 . C C O O "
1 .or noo
-------
SUMMARY OF DATA FROM OPERATING REPORTS FOR
SOUTH RIVER - OLD PLANT (TRICKLING FILTER) - ATLANTA, GEORGIA
Adjusted Influent, MGD
Treated Influent, MGD
Bypass Volume, MGD
Bypass Hours in Month
TSS, Avg Influent, ppm
TSS, Avg, Ibs
TSS, Avg Plant Effluent, ppm
TSS, Avg Removed Daily, Ibs
TSS, Avg Removed Daily, Percent
TSS, Avg to Stream, Daily, Ibs.
BOD, Avg Daily Influent, ppm
BOD, Avg Daily Influent, Ibs
BOD, Avg Plant Effluent, ppm
BOD, Avg Removed Daily, Ibs
BOD, Avg Removed Daily, Percent
BOD, Avg to Stream Daily, Ibs
Average Screenings, cf/day
Average Screenings, cf/MG
Average Grit Removed, cf/day
Average Grit Removed, cf/MG
Grit Organics
1968
December
3.90
3.60
.30
60.75
424.00
12,730.17
60.00
10,928.73
85.80
2,862.28
335.00
10,058.04
43.00
8,767.00
87.10
2,129.21
31.00
8.61
61.00
16.94
31.00
1969
January
4.50
4.30
.20
33.25
350.00
12,551.70
80.00
9,682.74
77.10
3,452.76
211.00
7,566.88
55.00
5,594.47
73.90
2,324.35
33.00
7.67
63.00
14.65
—
February
3.90
3.80
.10
18.25
196.00
6,211.63
53.00
4,531.95
72.90
1,843.14
206.00
6,528.55
32.00
5,514.40
84.40
1,185.95
38.50
10.13
71.40
18.78
—
March
4.40
4.30
.10
19.50
184.00
6,598.60
80.00
3,729.64
56.50
3,022.41
281.00
10,077.22
40.00
8,642.74
85.70
1,668.83
30.00
6.97
55.00
12.79
—
April
4.80
4.60
.20
24.00
208.00
7,979.71
65.00
5,486.05
68.70
2,840.60
175.00
6,713.70
31.00
5,524.41
82.20
1,481.19
28.00
6.08
63.00
13.69
—
May
5.90
5.10
.80
98.00
194.00
8,251.59
84.00
4,678.73
56.70
4,867.22
160.00
6,805.44
34.00
5,359.28
78.70
2,513.68
32.00
6.27
52.00
10.19
—
June
4.90
4.70
.20
26.50
257.00
10,073.88
27.00
9,015.53
89.40
1,487.02
305.00
11,955.39
31.00
10,740.25
89.80
1,723.88
27.00
5.74
61.00
12.97
—
July
5.10
4.90
.20
34.00
232.00
9,480.91
60.00
7,028.95
74.10
2,838.93
225.00
9,194.85
34.00
7,805.40
84.80
1,764.75
24.00
4.89
60.00
12.24
—
August
5.30
5.20
.10
11.75
250.00
10,842.00
53.00
8,543.49
78.70
2,507.01
208.00
9,020.54
34.00
7,546.02
83.60
1,647.99
29.00
5.57
74.00
14.23
—
September
4.80
4.70
.10
13.75
257.00
10,073.88
62.00
7,643.60
75.80
2,644.61
261.00
10,230.67
37.00
8,780.34
85.80
1,668.00
7.00
1.48
10.00
2.12
—
October
5.10
5.00
.10
30.00
295.00
12,301.50
65.00
9,591.00
77.90
2,956.53
177.00
7,380.90
44.00
5,546.10
75.10
1,982.41
8.00
1.60
20.00
4.00
—
November
3.80
3.80
.00
9.00
232.00
7,352.54
57.00
5,546.09
75.40
1,806.45
301.00
9,539.29
58.00
7,701.15
80.70
1,838.14
11.00
2.89
12.00
3.15
—
-------
SUMMARY OF DATA FROM OPERATING REPORTS FOR
SOUTH RIVER - NEW PLANT (AERATION) - ATLANTA, GEORGIA
oo
Adjusted Influent, MGD
Treated Influent, MGD
Bypass Volume, MGD
Bypass Hours in Month
TSS, Avg Influent, ppm
TSS, Avg, Ibs
TSS, Avg Plant Effluent, ppm
TSS, Avg Removed Daily, Ibs
TSS, Avg Removed Daily, Percent
TSS, Avg To Stream Daily, Ibs
BOD, Avg Daily Influent, ppm
BOD, Avg Daily Influent, Ibs
BOD, Avg Plant Effluent, ppm
BOD, Avg Removed Daily, Ibs
BOD, Avg Removed Daily, Percent
BOD, Avg to Stream Daily, Ibs
Average Screenings, cf/day
Average Screenings, cf/MG
Average Grit Removed, cf/day
Average Grit Removed, cf/MG
Grit Organics
1968
December
10.30
10.10
.20
10.25
416.00
35,041.34
70.00
29,144.96
83.10
6,590.26
299.00
25,185.96
57.00
20,384.62
80.90
5,300.07
31.00
3.06
61.00
6.03
31.00
1969
January
8.90
8.90
—
1.00
350.00
25,979.10
83.00
19,818.34
76.20
6,160.76
211.00
15,661.68
38.00
12,841.09
81.90
2,820.59
33.00
3.70
63.00
7.07
—
February
7.80
7.50
.30
18.25
196.00
12,259.80
67.00
8,068.95
65.80
4,681.24
206.00
12,885.30
57.00
9,319.95
72.30
4,080.76
38.50
5.13
71.40
9.52
—
March
9.40
9.00
.40
19.50
184.00
13,811.04
66.00
8,857.08
64.10
5,567.78
282.00
21,166.92
43.00
17,939.34
84.70
4,168.63
30.00
3.33
55.00
6.11
—
April
12.00
11.70
.30
24.00
208.00
20,296.22
49.00
15,514.89
76.40
5,301.74
175.00
17,076.15
35.00
13,660.92
80.00
3,853.08
28.00
2.39
63.00
5.38
—
May
14.10
13.10
1.00
34.50
194.00
21,195.27
77.00
12,782.71
60.30
10,030.52
160.00
17,480.64
40.00
13,110,48
75.00
5,704.56
32.00
2.44
52.00
3.96
—
June
10.90
10.80
.10
5.00
257.00
23,148.50
66.00
17,203.74
74.30
6,159.09
305.00
27,471.96
36.00
24,229.36
88.10
3,496.97
27.00
2.50
61.00
5.64
—
July
11.10
10.90
.20
10.75
232.00
21,090.19
76.00
14,181.33
67.20
7,295.83
225.00
20,453.85
34.00
17,363.04
84.80
3,466.11
24.00
2.20
60.00
5.50
—
August
12.40
12.10
.30
11.75
250.00
25,228.50
56.00
19,577.31
77.50
6,276.69
208.00
20,990.11
30.00
17,962.69
85.50
3,547.83
29.00
2.39
74.00
8.11
—
September
9.80
9.70
.10
4.75
257.00
20,790.78
54.00
16,422.28
78.90
4,582.83
261.00
21,114.37
22.00
19,334.61
91.50
1,997.40
15.00
1.54
34.00
3.50
—
October
10.80
10.70
.10
3.00
295.00
26,325.21
70.00
20,078.55
76.20
6,492.69
177.00
15,795.12
35.00
12,671.79
80.20
3,270.94
18.00
1.68
44.00
4.11
—
November
11.20
11.00
.20
9.00
232.00
21,283.68
82.00
13,761.00
64.60
7,909.65
301 .00
27,613.74
52.00
22,843.26
82.70
5,272.54
19.00
1.72
32.00
2.90
—
-------
SUMMARY OF DATA FROM OPERATING REPORTS FOR
INTRENCHMENT CREEK WASTEWATER TREATMENT PLANT, SOUTH RIVER BASIN - ATLANTA, GEORGIA
\D
Adjusted Influent, MGD
Treated Influent, MGD
Bypass Volume, MGD
Bypass Hours in Month
TSS, Avg Influent, ppm
TSS, Avg, Ibs
TSS, Avg Plant Effluent, ppm
TSS, Avg Removed Daily, Ibs
TSS, Avg Removed Daily, Percent
TSS, Avg to Stream Daily, Ibs
BOD, Avg Daily Influent, ppm
BOD, Avg Daily Influent, Ibs
BOD, Avg Plant Effluent, ppm
BOD, Avg Removed Daily, Ibs
BOD, Avg Removed Daily, Percent
BOD, Avg to Stream Daily, Ibs
Average Screenings, cf/day
Average Screenings, cf/MG
Average Grit Removed, cf/day
Average Grit Removed, cf/MG
Grit Organics
1968
December
13.30
12.60
.70
63.00
266.00
27,952.34
61.00
21,542.21
77.00
7,963.03
352.00
36,989.56
52.00
31,525.19
85.20
7,519.34
27.90
2.21
67.90
5.38
33.00
1969
January
13.50
12.80
.70
42.40
167.00
17,827.58
73.00
10,034.68
56.20
8,767.84
350.00
37,363.20
78.00
29,036.54
77.70
10,369.96
18.20
1.42
74.47
5.81
18.00
February
14.20
13.30
.90
64.50
195.00
21,629.79
72.00
13,643.40
63.00
9,450.06
388.00
43,037.73
109.00
30,947.23
71.90
15,002.82
27.96
2.10
65.57
4.93
30.00
March
13.70
12.90
.80
62.50
207.00
22,270.30
96.00
11,942.04
53.60
11,709.36
379.00
40,775.09
113.00
28,617.87
70.10
14,685.90
23.52
1.82
52.69
4.08
18.90
April
14.40
13.60
.80
72.50
287.00
32,552.68
89.00
22,457.94
68.90
12,009.60
346.00
39,244.70
91.00
28,923.11
73.60
12,630.10
31.05
2.28
76.50
5.62
26.00
May
14.70
13.90
.80
74.50
209.00
24,228.53
54.00
17,968.52
74.10
7,654.45
386.00
44,747.43
52.00
38,719.27
86.50
8,603.55
34.84
2.50
108.44
7.80
3.33
June
13.80
13.40
.40
30.00
215.00
24,027.54
53.00
18,104.47
75.30
6,640.31
382.00
42,690.79
39.00
38,332.30
89.70
5,632.84
18.90
1.41
67.50
5.03
26.50
July
12.90
12.30
.60
47.50
308.00
31,595.25
47.00
26,773.89
84.70
6,362.59
343.00
35,185.62
30.00
32,108.16
91.20
4,793.83
15.68
1.27
78.82
6.40
16.00
August
13.00
12.50
.50
46.00
207.00
21,579.75
53.00
16,054.50
74.30
6,388.44
343.00
35,757.75
44.00
31,170.75
87.10
6,017.31
21.77
1.74
91.89
7.35
7.00
September
12.40
11.80
.60
35.50
354.00
34,837.84
66.00
28,342.64
81.30
8,266.61
374.00
36,806.08
36.00
33,263.24
90.30
7,516.03
17.10
1.44
89.10
7.55
17.00
October
11.60
11.30
.30
25.00
321.00
30,251.68
70.00
23,654.74
78.10
7,400.08
387.00
36,471.65
47.00
32,042.27
87.80
5,397.65
10.88
.96
88.40
7.82
14.00
November
12.10
11.70
.40
26.00
205.00
20,003.49
47.00
15,417.32
77.00
5,270.05
384.00
37,469.95
63.00
31,322.53
83.50
7,428.44
9.90
.84
77.85
6.65
27.00
-------
SUMMARY OF OPERATING DATA
SNAPFINGER CREEK WPC PLANT - SOUTH RIVER BASIN,
DEKALB COUNTY, GEORGIA
Average Flow, MGD
Bypass hours in month
TSS Avg Influent, ppm
TSS Avg Effluent, ppm
TSS Removed Daily, %
TSS to Stream Daily, Ibs*
0 BOD, Avg Influent, ppm
BOD, Avg Effluent, ppm
BOD, Removed Daily, %
BOD to Stream Daily, Ibs*
1969
January
2.33
34
119
44
63
1,130
141
76
46
1,880
February
2.61
20
122
42
66
963
174
51
71
1,094
March
2.66
18
64
32
50
727
124
45
64
1,042
April
2.52
60
76
29
62
692
132
33
75
865
May
2.76
52
70
20
71
540
73
18
75
502
June
2.54
0
98
21
79
450
97
27
72
572
July
1.79
4
108
21
81
320
50
47
6
700
August September
2.09
8
132
39
70
697
123
35
72
627
1.97
30
192
130
32
2,172
46
28
39
472
October November December
2.53
78
71
31
56
1,409
99
42
58
1.963
2.52
144
82
22
73
714
86
29
66
1,850
3.59
168
96
21
78
1,134
107
37
65
1,579
* Adjusted according to bypass hours in a month
-------
SUMMARY OF OPERATING DATA
SHOAL CREEK WASTEWATER TREATMENT PLANT
SOUTH RIVER BASIN, DEKALB COUNTY, GEORGIA
1969
January February
Average Flow, MGD
Bypass hours in month
TSS Avg Influent, ppm
TSS Avg Effluent, ppm
TSS Removed Daily, %
TSS to Stream Daily, Ibs*
BOD Avg Influent, ppm
BOD Avg Effluent, ppm
BOD Removed Daily, %
BOD to Stream Daily, Ibs*
2.86
16
132
25
81
630
182
101
45
2,362
3.20
120
80
24
70
905
217
43
80
1,974
March
2.76
0
83
26
69
598
192
36
81
828
April
2.79
48
95
13
86
437
173
30
83
919
May
2.49
40
119
30
75
723
137
28
80
703
June
2.87
0
125
13
90
311
140
34
76
814
July
2.74
28
123
21
83
567
52
15
71
374
August September October November December
2.77
24
125
19
85
518
129
19
85
521
2.84
0
191
60
69
1,420
113
20
82
473
2.64
0
183
14
92
308
130
29
78
638
2.64
14
63
13
79
844
127
39
69
897
2.76
0
45
22
51
506
186
45
76
1,035
* Adjusted according to bypass hours in month
-------
S'XT'ELIP
COVERT
SOUTH RIVER BASIN-CITY OF ATLANTA
COMBINED AND STORM SEWER MAPPING
SAMPLE OF FIELD SURVEY
INFORMATION PLOTTED ON
REPRODUCIBLE CONTOUR MAPS
IS'Xe'BLlPTICAL
SCALE: 1 INCH = 200 FEET
-------
SAMPLE - LAND USE SURVEY
173 Drainage Area No. 3, McDaniel St.
-------
lOO-i
SAMPLE RATING CURVE
GAGING STATION NO. 5
CASPIAN STREET
10-
0»
o
O
i -
Note: Points on curve represent measured
stage - discharge relationships.
O.I
O.I
to
IOO
IOOO
10,000
Discharge - c f s
-------
APPENDIX
SUBBASIN NO. 3
McDaniel Street Combined Sewer Area
Survey of Possible Sources of Industrial or Trade
Waste Discharges (Grouped by Sheet Numbers,
Aerial Map)
Sheet P - 16
1. Electric Storage Battery Company "EXIDE"
2. Great Dane Trailers, Inc., Southeastern Leasing
3. Pollack Paper Company (a)
4. Armour and Company
5. Southern Paint Products Manufacturers
6. Link - Belt
7. Cotton Waste Railway Supply & Manufacturers Co.
8. Reliable Truck Repair (Typical)
9. Johnson Manufacturing
10. Service Stations (Typical)
11. Coin Laundries and Dry Cleaners (Typical)
Sheet P- 17
12. Refrigeration Sales & Service (Typical)
13. Tire Recapping (Typical)
14. Palmour Coffee Company
15. Steam Specialty Company
16. Produce Market (Typical)
17. Auto Junk Yard
18. Auto Electric Exchange
19. Wise Potato Chips
20. Seed Company (Typical)
21. Globe Products Company (b)
22. Harry Alter Company
23. McQuay -Norris Manufacturing
24. Reading Tube Corporation
25. Southeastern Industries
26. Metals Company
27. General Electric
28. Southeastern Warehouse
29. Hudson Manufacturing Company
30. Lancaster Products Company
31. Pfllsbury
32. R. C. Can Company
33. Joslyn Manufacturing
34. Precisionaire
35. Newell Manufacturing
36. Dixie Industrial Finishing Co. (Electroplating)
37. Electric Company (Typical)
38. Merita Bakery (d)
39. Ruralist Press
40. Henson Bakery Supplies
41. Cullen Adams (Upholstry)
42. Brown Metal Works
43. Engraving Company
44. Carpenter Steel Company
45. Atlantic Ice Company
175
-------
46. Berkeley Pump
47. Envelope Manufacturer
48. Abrams Fixture Corporation
Sheet P- 18
49. Fruehauf Trailers
50. Harris Rim & Wheel Inc. Service
51. Printing Company
52. Kingston Printing
5 3. McDaniel Mattress Company
54. Auto Truck FJectric Company
55. Gas Company
Sheet Q - 16
56. Atlanta Intercel
57. Ryder Truck Lines
58. Ford Truck Service
59. Baggett Transportation Company
60. Foy Brick Company
61. Miller Lumber Company
62. Southern Lead Burning Company
63. Dell Industries
Sheet Q- 17
64. Central Neon
65. London Iron & Metal Company
66. Metal Stamping
67. W.C. Caye, Construction Equipment
68. Southern Railway
69. Famous Foods (Processor)
70. Tractor and Machinery Company
71. G. E. Warehouse
72. Building Material Supply
73. Valiant Steel
74. Wadsworth Electric Manufacturing Company
75. Superior Bumper Products
76. Spinks Scale Company
77. New Dixie Trucking Company
78. Peter Pan Baking Company
79. Sugar & Spice Bakery
80. Lundsford Wilson Company
81. White House Food Products
82. National Fruit Product Company
83. Food Distributors
84. Industrial Chemical Manufacturers
85. American Associated Companies
86. Dry Ice Company (e)
87. J & B Smith Company (Reconditioning Steel Drums)
88. Wholesale Florists
89. Kimbro Warehouse
90. Gary Chapman Co. (Electrical & Electronic Products)
91. Gordy Tire Co mpany
92. Woffard Cabinet Company
93. Commercial Solvents Corporation
94. Southern Sales and Warehouse Company
95. Johnson-Fluker Company
96. Industrial Equipment Company
97. Speed Check Company
98. Industrial Door, Inc.
99. Quality Used Tire Company
Sheet Q - 18
100. Southern Mills
101. Swift & Company Oleomargarine Refinery
102. Metals, Inc.
103. Barrel-Town
104. International Harvester
105. Dixie Rubber Company
106. Select Foods
107. Leaseway of Georgia, Inc.
108. Atlanta Betting-Republic Rubber
176
-------
109. Atlas Supply Company
110. American Excelsor Corporation
111, General Lithographing
112. William Bishop, Electrical Manufacturing Agent
113. Alterman Brothers
114. Thomas Paint Manufacturing Company
115. Joana - Western Mills
116. John Underwood Company
117. Rubber Printing Plates
118. Fred K. H. Levy Company (Inks)
119. Bumper Service of Atlanta
120. New Method Laundry
Notes:
(a) Solvents, BOD 832, pH 11.1
(b) Solvents
(c) pH 3.5, can also be high
(d) BOD 1112, Suspended Solids 206
(e) Low pH
177
-------
STATICS 2 STARTING 136/ 3 0
00
STA.
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
DAY hR HN
136/ 3 C
I 1 /. / •) 1C
1 3O / 3 ID
1 •> /, / -i •an
L j u / j 3\j
136/ 3 45
1 ^ f, / it ft
I j a / ** U
136/ A 15
136/ A 30
136/ 4 45
136/ 5 0
136/ 5 15
136/ 5 30
136/ 5 45
136/ 6 0
136/ 6 15
136/ 6 30
136/ 6 45
1 7 f. / 7 n
L 3 o / i U
1 36 / 7 15
1 36 / 7 30
1 1 A / T /. ^
1 JO / f *l 3
1 3 6 / 8 0
136/ 8 15
i i A / n in
L JO / O JU
1367 B *i 5
136/ 9 0
136/ 9 15
136/ 9 30
136/ 9 45
136/1C 0
136/10 15
136/10 30
136/1C 45
136/11 C
136/11 15
136/11 30
136/11 45
136/12 C
136/12 15
136/12 30
136/12 45
136/13 0
136/13 15
136/13 30
136/13 45
136/14 0
136/14 15
136/14 30
136/14 45
136/15 0
136/15 15
CAGE
C.38
It* it
• H *t
' ~*fi
.. . J U
1.00
15 c
• £ J
C .60
C.38
C.38
C.38
C.38
0.38
C.38
C.38
C.38
C.38
1.25
2n 7
• u *
2.36
2f\ i
*u**
17 3
• I £
1C ft
• J U
.30
• 64
* 5
• ** £.
.16
.08
.08
1.10
0.98
C.82
C.£5
0.95
1.14
C.75
0.52
C.38
C.38
0.38
C.38
0.38
C.38
C.38
C.38
C.38
C.38
C.81
C.96
0.69
0.43
C.38
FLOW
O.C
fl 7 r P
O f • b \s
it ^ ft n
O J » ^ U
25. CC
e e p p
J O . U t-
2.5C
c.c
O.C
c.c
O.C
0.0
O.C
c.c
0.0
O.C
55. OC
226* 3C
281.80
2 20 . 6C
t.jc f\ r r
IT U , t L
S 7 . OC
63. CC
11 f\ f f\
JU . L 0
8 3 • C C
42.50
33. CO
33. CC
35. 5C
24. CC
U.CC
4.CC
21. CC
41. CC
7.50
0.83
C.O
C.C
O.C
O.C
C.C
O.C
0.0
C.C
O.C
0.0
10. 5C
22. CC
5.2C
0.05
O.C
FLO GRAPH 5CO TC!AL CF
C.
«••••• IC665C.
••• 14625C.
•••••• ip??sr
• ••••• L C £ £ J \* *
2C8125.
2CS25C.
2CS25C.
2C925C.
2C925C.
2C925C.
2C925C.
2C923C.
2C925C.
2C925C.
•••••• 2?40CC.
••«••• 1165229.
•••• 14C44C4.
••• 143B379.
••• 1448079.
«••• 14989C4.
•• 1525679.
• 1541429.
1548179.
•• 15^9429.
•••• 1587329.
• 16C9154.
16129C2.
1613275.
1613275.
1613275.
1613275.
1613275.
1613275.
1613275.
1613275.
1613275.
1613275.
• 161UCCC.
•• 1632625.
• U44864.
1647226.
164724E.
-------
STATICN 3 STARTING 136/ 2 45
STA. DAY HR
GAGE
FLCk
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
1367 2
1367 3
136/ 3
136/ 3
136/ 3
136/ 4
136/ 4
136/ 4
136/ 4
136/ 5
136/ 5
136/ 5
136/ 5
136/ 6
1367 6
1367 6
136/ 6
136/ 1
1367 1
136/ 7
136/ 7
136/ a
136/ 8
136/ 8
136/ 8
136/ 9
1367 9
1367 9
136/ 9
136/10
136/10
136/10
136/10
136/11
136/11
136/11
136/11
136/12
136/12
136/12
136/12
136/13
136/13
136/13
136/13
136/14
136/14
136/14
136/14
136/15
136/15
136/15
136/15
136/16
136/16
136/16
136/16
136/17
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
C
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
0
15
30
45
C
C
1
C
0
0
c
c
c
c
c
0
c
c
c
0
1
1
1
1
1
1
1
1
1
1
c
0
0
c
c
c
c
c
c
c
c
c
0
c
c
c
0
0
c
c
c
c
c
c
c
c
c
c
c
c
c
1
0
.31
.13
.90
.64
.51
.44
.41
.38
.37
.36
.35
.34
.33
.33
.34
.20
.38
.76
.61
.30
.02
.20
.50
.20
.00
.88
.87
.90
.90
.80
.76
.70
.85
.60
.65
.55
.50
.49
.48
.47
.46
.45
.44
.43
.42
.41
.40
.39
.38
.37
.36
.35
.34
.34
.33
.90
.16
.86
0
32
14
3
0
0
0
0
0
0
0
0
0
0
0
39
62
124
96
52
23
39
80
39
21
13
12
14
14
8
7
4
11
8
3
1
0
0
0
0
c
c
0
0
c
0
0
c
0
0
0
0
0
0
0
14
35
12
.C
.cc
.50
.00
.90
.24
.08
.01
.C
.c
.c
.0
.0
.0
.c
.00
.2C
.80
.80
.00
.00
-CO
.CO
.CO
.CO
.5C
.70
.50
.50
.80
.CO
.70
.4C
.80
.30
.35
.77
.65
.58
.46
.38
.30
.24
.19
.14
.08
.04
.C2
.Cl
.0
.0
.C
.C
.0
.C
.5C
.CO
.10
GRAPH
============
««*»«<
« * *
250
TOTAL CF
C.
1440C.
35325.
432CC.
44955.
45468.
45612.
45652.
15657.
45657.
45657.
45657.
45657.
45657.
45657.
632C7.
1C8747.
192897.
2S2617.
359577.
393327.
421??7.
474777.
528327.
555327.
570852.
582642.
594882.
6C7932.
61B416.
625526.
630791.
638036.
647126.
652571.
65-4664.
65561E.
656256.
65681C.
65727S.
657656.
657962.
658205.
658398.
658547.
658645.
658699.
658726.
65874C.
658744.
658744.
658744.
658744.
658744.
658744.
66.5269.
6-87544.
708739.
-------
Analyses of Water Quality
Results of water quality analyses were punched on computer cards, and a program was
written to collate and print updated records at intervals throughout the study. A sample of
the output is included on the following page. Symbols at the top of each column of data are
as follows:
Symbols
BOD
COD
DO
SST
ssv
SSB
COND
PH
ACID
ALK
PHOS
CHL
REST
RESV
COLI
FCOL
FSTR
GAHT
Description
Biochemical Oxygen Demand (5— day, 20° C)
Chemical Oxygen Demand
Dissolved Oxygen
(Axide Modification of lodometric Method)
Total Suspended Solids
Volatile Suspended Solids
Settleable Suspended Solids
Conductivity (Industrial Instruments Type RC
Conductivity Bridge)
pH
(Electrometric Method)
Acidity - as CaCO3
(Indicator Method)
Alkalinity - as CaCO3
Orthophosphate
(SnCl2 Method)
Chlorine Demand
Total Residue
Volatile Residue
Total Coliform (Membrane Filter)
Fecal Coliform (Membrane Filter)
Fecal Streptococcus (Membrane Filter)
Gage Height
Unit
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
jumhos/cm
mg/1
mg/1
mg/1
mg/1
mg/1
mg/1
MPN/lOOml
MPN/lOOml
MPN/lOOml
feet
180
-------
The first line of each pair of lines on the computer printout lists the sample location, date,
time and method, and the values obtained for each water quality test. Missing tests are
denoted by (-0.0). For instance, the first line of data shown was obtained at station 8
(South River at Bouldercrest Road) on day 87 (of the calendar year 1969), at hour 1012,
and by method 0 (automatic sampler). The second line presents loads of some of the
parameters in 1,000 Ibs/day total bacterial counts, and flow rate corresponding to the stated
gage height, in this case 87.80 cfs.
181
-------
BIBLIOGRAPHIC:
Black, Crow & Eidsness, Inc., Studies of Storm and Combined
Sewer Pollution, Final Report FWQA Contract No. 14-12-458,
January, 1971.
ABSTRACT:
Six urban drainage basins within the City of Atlanta, Georgia, served
by combined and separate sewers, are studied to determine the
major pollution sources during storm events. Rainfall frequency
analysis and simulation techniques are utilized to obtain design
criteria for alternative pollution abatement schemes.
High frequency storms are shown to cause the worst impact and
most of the pollution from combined sewer areas. Annual BOD
from these areas is 2,078,000 pounds, or 460 Ibs/acre, of which 57
percent is due to storms of two-week or higher frequency.
Bypassing of wastewater treatment plant flows during storms adds
690,000 pounds BOD/year. Runoff from storm-sewered areas, at
253 Ibs/acre, adds 5,577,000 pounds/year. Overflows and bypassed
flows have severe impact upon the South River, due to their high
deoxygenation rates and coliform concentrations.
Annual BOD reduction from combined sewer areas of 57 percent
ACCESSION NO.
KEY WORDS:
Storm Overflow
Combined Sewer Overflow
Simulation
Frequency Analysis
Treatment Costs
Economic Analysis
Land Use Indicators
Unit Hydrographs
BIBLIOGRAPHIC:
Black, Crow & Eidsness, Inc., Studies of Storm and Combined
Sewer Pollution, Final Report FWQA Contract No. 14-12-458,
January, 1971.
ABSTRACT:
Six urban drainage basins within the City of Atlanta, Georgia, served
by combined and separate sewers, are studied to determine the
major pollution sources during storm events. Rainfall frequency
analysis and simulation techniques are utilized to obtain design
criteria for alternative pollution abatement schemes.
High frequency storms are shown to cause the worst impact and
most of the pollution from combined sewer areas. Annual BOD
from these areas is 2,078,000 pounds, or 460 Ibs/acre, of which 57
percent is due to storms of two-week or higher frequency.
Bypassing of wastewater treatment plant flows during storms adds
690,000 pounds BOD/year. Runoff from storm-sewered areas, at
253 Ibs/acre, adds 5,577,000 pounds/year. Overflows and bypassed
flows have severe impact upon the South River, due to their high
deoxygenation rates and coliform concentrations.
Annual BOD reduction from combined sewer areas of 57 percent
ACCESSION NO.
KEY WORDS:
Storm Overflow
Combined Sewer Overflow
Simulation
Frequency Analysis
Treatment Costs
Economic Analysis
Land Use Indicators
Unit Hydrographs
BIBLIOGRAPHIC:
Black, Crow & Eidsness, Inc., Studies of Storm and Combined
Sewer Pollution, Final Report FWQA Contract No. 14-12-458,
January, 1971.
ABSTRACT:
Six urban drainage basins within the City of Atlanta, Georgia, served
by combined and separate sewers, are studied to determine the
major pollution sources during storm events. Rainfall frequency
analysis and simulation techniques are utilized to obtain design
criteria for alternative pollution abatement schemes.
High frequency storms are shown to cause the worst impact and
most of the pollution from combined sewer areas. Annual BOD
from these areas is 2,078,000 pounds, or 460 Ibs/acre, of which 57
percent is due to storms of two-week or higher frequency.
Bypassing of wastewater treatment plant flows during storms adds
690,000 pounds BOD/year. Runoff from storm-sewered areas, at
253 Ibs/acre, adds 5,577,000 pounds/year. Overflows and bypassed
flows have severe impact upon the South River, due to their high
deoxygenation rates and coliform concentrations.
Annual BOD reduction from combined sewer areas of 57 percent
ACCESSION NO.
KEYWORDS:
Storm Overflow
Combined Sewer Overflow
Simulation
Frequency Analysis
Treatment Costs
Economic Analysis
Land Use Indicators
Unit Hydrographs
-------
may be achieved for a total annual cost of $165,000, by modifying
the three regulators and treating 80 percent of the overflows, in
conjunction with storage sufficient to contain a two-week storm.
Alternate, less favorable solutions include storage and treatment at
existing treatment plants, and storage with release to receiving
streams after chlorination. Separation of combined sewers would
achieve 60 percent BOD removal for 53,030,000/year.
This report is submitted in fulfillment of Contract 14-12-458
between the Environmental Protection Agency and Black, Crow &
Eidsness, Inc.
may be achieved for a total annual cost of $165,000, by modifying
the three regulators and treating 80 percent of the overflows, in
conjunction with storage sufficient to contain a two-week storm.
Alternate, less favorable solutions include storage and treatment at
existing treatment plants, and storage with release to receiving
streams after chlorination. Separation of combined sewers would
achieve 60 percent BOD removal for $3,030,000/year.
This report is submitted in fulfillment of Contract 14-12-458
between the Environmental Protection Agency and Black, Crow &
Eidsness, Inc.
may be achieved for a total annual cost of $165,000, by modifying
the three regulators and treating 80 percent of the overflows, in
conjunction with storage sufficient to contain a two-week storm.
Alternate, less favorable solutions include storage and treatment at
existing treatment plants, and storage with release to receiving
streams after chlorination. Separation of combined sewers would
achieve 60 percent BOD removal for $3,030,000/year.
This report is submitted in fulfillment of Contract 14-12-458
between the Environmental Protection Agency and Black, Crow &
Eidsness, Inc.
-------
Accession Number
Subject Field &. Group
05-B
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
BLACK, CROW & EIDSNESS, INC., CONSULTING ENGINEERS
Gainesville, Florida
Title
Storm and Combined Sewer Pollution Sources and Abatement — Atlanta, Georgia
10
Authors)
Vilaret, Dr. Manuel R.
Pyne, R. David G.
16
Project Designation
11024 ELB 04-71
21
Note
22
Citation
23
Descriptors (Starred First)
*Overflow, * Storm Runoff, *Wastewater Treatment, * Rainfall—Runoff Relationships,
Water Quality, Storage Capacity, Treatment Methods, Treatment Costs, Cost—Benefit Analysis,
Simulation, Frequency Analysis, Land—Use Indicators, Pollutants
25
Identifiers (Starred First)
*Combined Sewers, Quantity of Overflow, Quality of Overflow.
27
Abstract
Six urban drainage basins within the City of Atlanta, Georgia, served by combined and
separate sewers, are studied to determine the major pollution sources during storm events.
Rainfall frequency analysis and simulation techniques are utilized to obtain design criteria
for alternative pollution abatement schemes.
High frequency storms are shown to cause the worst impact and most of the pollution from
combined sewer areas. Annual BOD from these areas is 2,078,000 pounds, or 460 Ibs/acre,
of which 57 percent is due to storms of two—week or higher frequency. Bypassing of
wastewater treatment plant flows during storms adds 690,000 pounds BOD/year. Runoff
from storm—sewered areas, at 253 Ibs/acre, adds 5,577,000 pounds/year. Overflows and
bypassed flows have severe impact upon the South River, due to their high deoxygenation
rates and coliform concentrations.
Annual BOD reduction from combined sewer areas of 57 percent may be achieved for a
total annual cost of $165,000, by modifying the three regulators and treating 80 percent of
the overflows, in conjunction with storage sufficient to contain a two—week storm.
Alternate, less favorable solutions include storage and treatment at existing treatment
plants, and storage with release to receiving streams after chlorination. Separation of
combined sewers would achieve 60 percent BOD removal for $3,030,000/year.
Abstractor
R David G.Pvne
Inxtitution
Black, Crow & Eidsness, Inc.
WR-.102 (REV. JULY 19691
WRSIC
SEND TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 20240
* OPO: 1969-359-339
-------
Continued from inside front cover....
11022 08/67
11023 09/67
11020 12/67
11023 05/68
11031 08/68
11030 DNS 01/69
11020 DIH 06/69
11020 DBS 06/69
11020 06/69
11020 EXV 07/69
11020 DIG 08/69
11023 DPI 08/69
11020 DGZ 10/69
11020 EKO 10/69
11020 10/69
11024 FKN 11/69
11020
11000
DWF 12/69
01/70
11020 FKI 01/70
11024
11023
DOK 02/70
FDD 03/70
11024 DMS 05/70
11023
11024
EVO 06/70
06/70
Phase I - Feasibility of a Periodic Flushing System for
Combined Sewer Cleaning
Demonstrate Feasibility of the Use of Ultrasonic Filtration
in Treating the Overflows from Combined and/or Storm Sewers
Problems of Combined Sewer Facilities and Overflows, 1967
(WP-20-11)
Feasibility of a Stabilization-Retention Basin in Lake Erie
at Cleveland, Ohio
The Beneficial Use of Storm Water
Water Pollution Aspects of Urban Runoff, (WP-20-15)
Improved Sealants for Infiltration Control, (WP-20-18)
Selected Urban Storm Water Runoff Abstracts, (WP-20-21)
Sewer Infiltration Reduction by Zone Pumping, (DAST-9)
Strainer/Filter Treatment of Combined Sewer Overflows,
(WP-20-16)
Polymers for Sewer Flow Control, (WP-20-22)
Rapid-Flow Filter for Sewer Overflows
Design of a Combined Sewer Fluidic Regulator, (DAST-13)
Combined Sewer Separation Using Pressure Sewers, (ORD-4)
Crazed Resin Filtration of Combined Sewer Overflows, (DAST-4)
Stream Pollution and Abatement from Combined Sewer Overflows •
Bucyrus, Ohio, (DAST-32)
Control of Pollution by Underwater Storage
Storm and Combined Sewer Demonstration Projects -
January 1970
Dissolved Air Flotation Treatment of Combined Sewer
Overflows, (WP-20-17)
Proposed Combined Sewer Control by Electrode Potential
Rotary Vibratory Fine Screening of Combined Sewer Overflows,
(DAST-5)
Engineering Investigation of Sewer Overflow Problem -
Roanoke, Virginia
Micros training and Disinfection of Combined Sewer Overflows
Combined Sewer Overflow Abatement Technology
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