WATER POLLUTION CONTROL RESEARCH SERIES 11024 FKM 12/71
Urban Storm Runoff and
Combined Sewer Overflow
Pollution
Sacramento, California
ENVIRONMENTAL PROTECTION AGENCY • RESEARCH AND MONITORING
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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 Water Quality Research 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.
Previously issued reports on the Storm and Combined Sewer Pollution Control
Program:
11023 FDB 09/70
11024 FKJ 10/70
11023 DZF 06/70
11020 FAQ 03/71
11022 EFF 12/70
11022 EFF 01/71
11022 DPP 10/70
11024 EQG 03/71
11020 FAL 03/71
11024 DOC 07/71
11024 DOC 08/71
11024 DOC 09/71
11024 DOC
11040 GKK
11024 DQU
11024 EQE
11024 EJC
10/71
06/70
10/70
06/71
10/70
11024 EJC 01/71
11024 FJE 04/71
11024 FJE 07/71
11023 FDD 07/71
11024 FLY 06/71
11034 FLU 06/71
Chemical Treatment of Combined Sewer Overflows
In-Sewer Fixed Screening of Combined Sewer Overflows
Ultrasonic Filtration of Combined Sewer Overflows
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
Storm Water Management Model, Volume 1 - Final Report
Storm Water Management Model,' Volume II - Verification
and Testing
Storm Water Management Model, Volume III -
User1s Manual
Storm Water Management Model, Volume IV - Program Listing
Environmental Impact of Highway Deicing
Urban Runoff Characteristics
Impregnation of Concrete Pipe
Selected Urban Storm Water Runoff Abstracts, First Quarterly
Issue
Selected Urban Storm Water Runoff Abstracts, Second Quarterly
Issue
Selected Urban Storm Water Runoff Abstracts, Third Quarterly
Issue
Selected Urban Storm Water Runoff Abstracts, July 1970 -
June 1971
Demonstration of Rotary Screening for Combined Sewer
Overflows
Heat Shrinkable Tubing as Sewer Pipe Joints
Hydraulics of Long Vertical Conduits and Associated Cavitation
Continued on inside back cover
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URBAN STORM RUNOFF
AND
COMBINED SEWER OVERFLOW POLLUTION
Sacramento, California
by
Envirogenics Company
A Division of
Aerojet-General Corporation
El Monte, California
for the
ENVIRONMENTAL PROTECTION AGENCY
Program No. 11024 FKM
Contract No. 14-12-197
December 1971
For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402 - Price $1.75
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EPA Review Notice
This report has been reviewed by the Environmental
Protection Agency 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
A general method was developed to assess, primarily from readily avail-
able precipitation and wastewater quality data, the extent of water
pollution occurring from storm water runoff and combined sewer overflows
in an urban area, and is applied to Sacramento, California. Systems
for the control and treatment of these wastewaters are developed and
evaluated.
The least costly system to adequately protect the receiving waters from
storm water runoff and combined sewer overflows would retain the com-
bined sewers for the conveyance of combined sewage during wet-weather
flow conditions. Facilities would also be required for the treatment of
existing separated storm water flows. Total annual cost for this system
was estimated to be $6.99 million. A slightly more costly system ($7.09
million) incorporating complete sewer separation of sanitary sewage and
storm water runoff is recommended to the City of Sacramento. The
similarity in annual costs for the separated sewer and the combined
sewer systems results from the requirement for major enlargement of the
existing combined sewer system to adequately convey anticipated combined
sewage flows. In areas where existing combined sewer capacities would
not be grossly inadequate, the separation of combined storm water runoff
and sanitary sewage flows to achieve receiving water quality objectives
would appear unwarranted, due to the high cost of constructing new
conveyance facilities and the probable requirement to treat separated
storm water runoff, since its quality is not substantially different
from that of sanitary sewage.
This report was submitted in fulfillment of Project Number 11024 FKM,
Contract Number 14-12-197, under the sponsorship of Water Quality
Research, Environmental Protection Agency.
Pursuant to Executive Reorganization Plan No. 3 of 1970, effective
December 2, 1970, and Environmental Protection Agency Orders Nos.
1110.1 and 1110.2, all references to the Federal Water Quality
Administration herein shall be to the Environmental Protection Agency,
Water Quality Research.
iii
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CONTENTS
Section Page
ABSTRACT iii
FIGURES viii
TABLES xiii
I. CONCLUSIONS AND RECOMMENDATIONS 1
Conclusions 1
Recommendations 3
IL INTRODUCTION 7
Program Need 8
Scope and Objectives 9
in. GENERAL APPROACH 11
IV. THE STUDY AREA 15
Physical Features 15
Geography 15
Hydrology 17
Climate 17
City Evolution 20
Early Years 20
Recent Years 20
Government 25
Financial 25
The Combined Sewer Area 25
Relation to City 25
Population 26
Land Use 26
V. THE WASTEWATER SYSTEM 31
Facilities Description 32
Sewerage System Development 34
Collection and Conveyance 37
Treatment 37
Main Sumps 39
v
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CONTENTS (continued)
Section Page
Wastewater and Rainfall Characteristics 39
Wastewater Sampling 42
Precipitation 48
Municipal Sewage 48
Separated Storm Water Runoff 51
Combined Sewage 56
Receiving Water Characteristics 56
VI. SYSTEMS DESIGN 61
Systems Development 61
Candidate Systems Classification 61
Planning Horizon 62
Design Criteria 63
Wastewater Characteristics 63
Conveyance Considerations 70
Storage 73
Treatment 75
Disposal 79
Spacial and Temporal Constraints 80
Programmed Design 82
Sewer Design 82
Wastewater Quality Characteristics 87
Storage Capacities 88
Treatment Process Performance 91
Receiving Water Quality 105
VII. SYSTEMS ANALYSIS 107
Costing 107
Construction and Installation 107
Operations and Maintenance 107
Annual Conversion 108
Collection and Conveyance 108
Description 109
Costs 119
Comparison 119
VI
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CONTENTS (continued)
Section Page
Storage 122
Description 122
Costs 123
Comparison 125
Treatment Process 125
Description 132
Costs 135
Comparison 137
Effluent Disposal 137
Description 137
Costs 139
Trade-Off Optimization 139
VIII. SYSTEMS EVALUATION AND SELECTION 151
Evaluation Criteria 151
System Performance 151
Financing 155
Environmental Factors 156
Systems Evaluation 157
System Performance 157
Systems Cost Effectiveness 166
Financing Opportunities 175
System Selection 177
IX. ACKNOWLEDGMENTS 179
X. REFERENCES 181
XI. APPENDICES 183
vn
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FIGURES
Figure Page
1. Location of Study Area 16
2. Map of the City of Sacramento - 1859 21
3. Sacramento City Boundary - 1969 22
4. Aerial Photo of Central Sacramento - Looking East 24
5. Sacramento Combined Sewer System 27
6. Aerial View of Study Area and Surrounding Region 29
7. Wastewater Treatment Service Areas in City of 33
Sacramento
8. Existing Combined Sewer System 35
9. Existing Separated Storm Water Sewer Systems 38
10. Schematic Plan - Sump No. 2 40
11. Schematic Plan - Sump No. 1 41
12. Location of Wastewater Sampling Stations 43
13. Wet-weather Wastewater Sampling Periods in Re- 46
lation to Observed Rainfall at U.S. Post Office
14. Location of Rain Gages 49
15. Daily Rainfall - U.S. Post Office 50
16. Diurnal Municipal Sewage Characteristics at 52
Station 8
17. Diurnal Characteristics of Sewage from State Water 53
Resources Building
18. Location of Major Industrial Wastewater Discharges 54
19. Relationship Between River Flow and Suspended 59
Solids Concentration at Sacramento
IX
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FIGURES (continued)
Figure Page
20. Relationship Between River Flow and Fecal 60
Coliforms Concentration at Sacramento
21. Design Sanitary Sewage Characteristics 66
22. Relationship between Existing Pipe Diameter and 71
Slope
23. Relationship Between Number of Grinder-Pump Units 74
and Population Density
24. Relationship Between Surface Loading Rate and Con- 77
stituent Removal for Dissolved Air Flotation
25. Locations of Proposed Storage and Treatment 81
Facilities
26. Predicted Storm Water Runoff Quality Distribution, 89
Combined Area, Sump No. 2 - 1992
27. Predicted Combined Sewage Quality Distribution, 90
Combined Area, Sump No. 2 - Year 1992
28. Relationship Between Reservoir Volume and Reservoir 92
Withdrawal Rate for Storm Water Runoff, Com-
bined Area
29. Relationship Between Reservoir Volume and Reser- 93
voir Withdrawal Rate for Combined Sewage,
Combined Area
30. Relationship Between Reservoir Volume and Reser- 94
voir Withdrawal Rate for Storm Water Runoff,
Separated Area
31. Relationship Between Reservoir Volume and Reser- 95
voir Withdrawal Rate for Storm Water Runoff,
Total Area
32. Relationship Between Reservoir Volume and Reser- 96
voir Withdrawal Rate for Combined Sewage,
Total Area
33. Effect of Various Treatments on Storm Water Runoff 97
Total Suspended Solids Content, Combined Area -
Year 1992
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FIGURES (continued)
Figure Page
34. Effect of Various Treatments on Storm Water 98
Runoff BOD content, Combined Area -
Year 1992
35. Effect of Various Treatments on Storm Water 99
Runoff Fecal Coliforms Content, Combined
Area - Year 1992
36. Effect of Various Treatments on Combined Over- 101
flows Total Suspended Solids Content, Com-
bined Area - Year 1992
37. Effect of Various Treatments on Combined Over- 102
flows BOD Content, Combined Area - Year 1992
38. Effect of Various Treatments on Combined Over- 103
flows Fecal Coliform Content, Combined Area -
Year 1992
39. Estimated Background Distribution of Pollutant 106
Concentrations in the Sacramento River -
Year 1992
40. ASCE Combined Sewer Separation Project Typical 112
Piping Layout
41. Individual Grinder-Pump Unit 114
42. Medium Zonal Grinder-Pump Station 115
43. Plan of Large Grinder-Pump Station 116
44. Elevation of Large Grinder-Pump Station 117
45. Plan of Typical Pump Station for Reservoir 127
Withdrawal
46. Section of Typical Pump Station for Reservoir 128
Withdrawal
47. Plan at Grade of Typical Subsurface Pump Station 129
48. Plan Below Grade of Typical Subsurface Pump 130
Station
XI
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FIGURES (continued)
Figure Page
49. Section of Typical Subsurface Pump Station 131
50. Dissolved Air Flotation Unit 133
51. Mechanical Screening Unit 136
52. Chlorination Facility 140
53. BOD Content of Sacramento River Following 159
Combined Sewage Overflow Discharge -
Year 1992
54. Incremental Addition of BOD to Sacramento River 161
by Combined Sewage Overflow Discharge -
Year 1992
55. Suspended Solids Content of Sacramento River 162
Following Combined Sewage Overflow Discharge -
Year 1992
56. Incremental Addition of Suspended Solids to 163
Sacramento River by Combined Sewage Over-
flow Discharge - Year 1992
57. Fecal Coliform Density of Sacramento River 164
Following Combined Sewage Overflow Discharge -
Year 1992
58. Incremental Addition of Fecal Coliforms to 165
Sacramento River by Combined Sewage Over-
flow Discharge - Year 1992
59. BOD Content of Sacramento River Following Storm 167
Water Runoff Discharge - Year 1992
60. Incremental Addition of BOD to Sacramento River 168
by Storm Water Runoff Discharge - Year 1992
61. Suspended Solids Content of Sacramento River 169
Following Storm Water Runoff Discharge -
Year 1992
62. Incremental Addition of Suspended Solids to 170
Sacramento River by Storm Water Runoff Dis-
charge - Year 1992
Xll
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FIGURES (continued)
F igure
63. Fecal Coliform Density of Sacramento River
Following Storm Water Runoff Discharge -
Year 1992
64. Incremental Addition of Fecal Coliforms to 172
Sacramento River by Storm Water Runoff Dis-
charge - Year 1992
Xlll
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TABLES
Table Page
1. Mean Climatological Data for Sacramento, 19
California
2. Sampling Station Field Survey Data 47
3. Separated Storm Water Runoff Quality Charac- 55
teristics - Station 17
4. Combined Sewage Characteristics - Station 8 57
5. Design Runoff Coefficients 67
6. Design Unit Hydrographs 68
7. Design Constants for Determination of Storm Water 69
Runoff Quality
8. Minimum Force Main Velocities 72
9. Design Criteria for Dissolved Air Flotation 75
10. Mechanical Screening Test Data 78
11. Storm Sewer Design Flows 85
12. Combined Sewer Design Flows 86
13. Estimated Flow Capacities of Existing Sewer 87
Systems
14. Predicted Untreated Wastewater Quality Character- 88
istics for Combined Area - Year 1992
(7,038 acres)
15. Predicted Treated Storm Water Runoff Quality 100
Characteristics - Year 1992
16. Predicted Treated Combined Sewage Quality 104
Characteristics - Year 1992
17. Annual Costs of Conveyance Alternatives 120
18. Capacities of Reservoirs 124
19. Annual Costs of Reservoirs 126
xv
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TABLES (continued)
Table Page.
20. Annual Costs of Treatment for Varied Influent 138
Flow Rates
21. Annual Costs of Effluent Chlorination and Disposal 141
22. Combinations of Storage, Treatment, and Disposal 142
Resulting in Minimum Annual Costs
23. Key for Complete Sewer System Costing Combina- 143
tions (Presented in Tables 24 through 30)
24. Annual System Costs, Separated Area 144
25. Annual System Costs, Combined Area, Sump No. 2 145
Vicinity Location
26. Annual System Costs, Combined Area, Sacramento 146
Port Location
27. Annual System Costs, Combined Area, South 147
Sacramento Location
28. Annual System Costs, Study Area, Sump No. 2 148
Vicinity Location
29. Annual System Costs, Study Area, Sacramento 149
Port Location
30. Annual System Costs, Study Area, South 150
Sacramento Location
31. Acceptably Performing Systems for Control of 174
Storm Water Runoff and Combined Sewer
Overflows from Study Area
32. Comparison of Receiving Water Quality Charac- 175
teristics from the Least Costly, Acceptably
Performing Combined and Separated Sewer
Systems - Year 1992
33. Maximum Funding Eligibilities for Combined 176
Sewage and Storm Water Runoff Water Pollu-
tion Abatement Systems
xvi
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Section I
CONCLUSIONS AND RECOMMENDATIONS
This program was directed to the development of a general method for
determining the extent of pollution resulting from storm water runoff
and combined sewer overflows occurring in an urban area, and the
application of this method to the City of Sacramento, California, Where-
as the conclusions and recommendations, which are primarily based on
conditions and factors pertaining to Sacramento, may not be general in
their application to other areas, the methods developed in this program
to assess the extent of pollution from storm water runoff and combined
sewer overflows are believed general in nature,,
CONCLUSIONS
The necessary data are not available in the Study Area or most other areas to determine or
predict distributions of storm water runoff and combined sewage flows and pollutant con-
tents, and distributions of the corresponding receiving water characteristics. Most, if not
all, of the characterization of storm water runoff and combined sewage
that has been performed and reported is totally unsuitable for predicting
in a quantitative manner the temporal distributions of flows and composi-
tions of storm water runoff. The best that these data can provide are
qualitative indications of the magnitudes and range of expected variations
in the characteristics.
Because the development of specialized data acquisition and measure-
ment programs are both time consuming and costly, a method of assess-
ment is needed that can rely upon readily available, ubiquitous historical
data. Long-term records, in contrast to data collected during short-
term programs, provide a greater assurance that extreme values or
occurrences, for which storm, water runoff and combined sewage control
systems must be designed, will be noted and accommodated. A method was
developed in this program that provides a rapid, economical, and accurate assessment of the
extent of pollution resulting from storm water runoff and combined sewage overflows and
the effectiveness of systems in controlling the pollution.
Evaluation of system performance should be based, not on single values
or sets of water quality criteria that are applicable for all occasions at
all times, but on water quality criteria that recognize and reflect natur-
ally occurring and tolerable distributions of water quality and their ex-
pe ctancie s. The procedure developed in this program permits performance assessment on
the basis of three different and important water quality criteria -- maximum value,
cumulative distribution, and excession frequency. The first criterion
establishes an absolute maximum pollutant concentration that cannot
be exceeded at any time. The second criterion establishes an accept-
able distribution of pollutant concentration by specifying the greatest
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frequency of occurrence for a particular concentration value. The
third criterion establishes the maximum acceptable excession frequency
for the occurrence of a particular pollutant concentration.
The computer program developed in this program for performing the preliminary design of
gravity and force main sewer networks, including separate sanitary, separate storm water
runoff, and combined sewage collection and conveyance facilities, provided rapidly and
economically all of the design details necessary for the accurate preparation of cost esti-
mates. Data input to the program consists simply of the flow distribu-
tion networks and the assignment of the following appropriate values
to each junction in the networkr resident and transient populations,
storm runoff coefficient, individual drainage area, ground surface
elevation, and distance to next downstream junction. Output from the
program provides the peak flow, diameter, slope, invert elevation,
and depth below grade for every pipe in the network. With the aid of
this computer program, a number of conveyance alternatives for
several different storm recurrence intervals can be designed and
their costs estimated to permit a comprehensive evaluation based on
many alternatives.
The modified rational runoff method developed in this program provided realistic estimates
of peak storm water runoff flow rates even though the total drainage area to which it was
applied exceeds ten square miles. The method aggregates the individual hydro -
graphs arriving from, upstream contributing sewers to establish the peak
flow and the corresponding time of concentration to be used for the de-
sign of the immediately downstream sewer.
Due to the high cost of constructing new collection and conveyance systems and the poor
quality of storm water runoff, the separation of combined storm water runoff and sanitary
sewage flows to achieve receiving water quality objectives appears unwarranted, except per-
haps in those areas where existing combined sewer capacities are grossly inadequate. The
concentrations of pollutants in separated storm water runoff are sufficiently large, and not
substantially different from those in sanitary sewage, to require some degree of treatment
prior to their discharge to receiving waters under most conditions.
Separation of sanitary sewage and storm water runoff in combined sewer systems by using
a force main for the transport of the sanitary wastes is substantially more expensive than by
employing an additionaJ gravity-flow system. In the portion of the Study Area
underlain with combined sewers, the estimated annual construction,
operation, and maintenance cost of a system embodying a completely
pressurized network extending from each individual service connection
to the terminus outfall is in excess of $15 million. If the small diam-
eter gravity laterals, which contain most of the service connections and
which would be abandoned and unused under the aforementioned force
main system since they are either inadequate or unnecessary for trans-
porting storm water runoff, were utilized to convey sanitary waste-
waters to common grinder-pump stations for injection into the pressur-
ized system, the estimated total annual cost of this force main system
is about $11 million. A further 20-percent reduction in system costs
would result if the dual-pipe system used in this program were re-
placed by a single-pipe network. An equivalent gravity system, how-
ever, costs less than $2 million.
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For those alternative systems containing high-rate treatment processes, such as mechanical
screening and dissolved air flotation, the least costly facility always resulted when the
treatment process was combined with a holding pond whose capacity was matched with
that of the process to provide an optimally sized facility. The holding pond pro-
vides mainly peak flow attenuation, but also some pollutant removal
capability as well. Reduction of instantaneous peak flows results in
both smaller downstream treatment facilities with improved utiliza-
tion factors and lesser instanteneous pollutant loadings and effects on
the receiving waters. Determination of the required capacities of ponds
to contain storm water runoff and combined sewer overflows associated
with specific storm recurrence intervals must be based on temporal
distributions of both inflow and outflow.
The least costly system for the Study Area that will adequately provide for the protection
of the receiving waters from the discharge of storm water runoff and combined sewer over-
flows retains the combined sewers for the conveyance and provides for the treatment of
the combined wastewater. The system would provide for two separate con-
veyance and treatment systems in the Study Area--one in the existing
combined sewer area and the other in the existing separated sewer
area. The Combined Area system is comprised of an augmented exist-
ing combined sewer collection system for the conveyance of sanitary
sewage from the Study Area and storm water runoff from the Combined
Area to a treatment facility with a surface reservoir, a dissolved air
flotation unit, and a chlorination station. In the Separated Area, the
system consists of an augmented existing storm water runoff collection
network and a new storm water interceptor sewer for conveyance of the
storm water runoff to a common treatment facility comprised of a hold-
ing pond, a dissolved air flotation unit, and a chlorination station.
RECOMMENDATIONS
To protect the Sacramento River from the discharge of storm water run-
off and combined sewer overflows from the total combined sewer system
area until the year 1992, it is recommended that the City of Sacramento select a system
which provides for the complete separation of sanitary sewage and storm flows and provides
for two separate storm water conveyance and treatment systems. Storm water runoff
from the existing combined sewer service area would be conveyed in a
new gravity sewer system to a treatment facility containing a holding
pond, a dissolved air flotation (or mechanical screening) unit, and a
chlorination station. A similar facility would treat storm runoff con-
veyed from the existing separated sewer areas in augmented storm sew-
ers. Sanitary sewage from the total area would be conveyed to the pre-
sent sewage treatment plant in the existing combined sewer system. Al-
though this system has a greater total cost than one retaining combined
sewers for combined sewage, it provides a much greater opportunity for
extramural financial support and would cost the local participants annu-
ally about 100 times less if total maximum funding eligibility under ex-
isting laws could be realized.
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In an attempt to reduce further the total cost of acceptable water pollu-
tion abatement systems, it is recommended that an investigation be conducted to de-
termine the merits of providing different retention and treatment subsystems for different
portions of the storm water runoff and combined sewer overflows. Because usually
both the flow rates and pollutant concentrations of storm water runoff
peak during the initial periods of rainfall events and decline rather
rapidly thereafter, the separation and treatment of a portion of the flow
for a fraction of the runoff time could produce substantial reductions in
pollutant loading to receiving waters at relatively low costs. The per-
formance of the recommended investigation would require a detailed
quantitative analysis of temporal wastewater flow and quality distribu-
tions and corresponding receiving water distributions, and could be
accomplished by modifying the procedures developed and reported herein.
During the conduct of this program to develop a method for evaluating
systems for the control of pollution from storm water runoff and com-
bined sewage overflows, it was necessary to determine the short-term
or hourly variations in quality of the storm water runoff that would be
expected to occur in the Study Area. In the absence of a known method,
these storm water compositions were estimated by means of a model
developed specifically in this program which relates pollutant concen-
tration to the time and rate of pollutant accumulation on the ground sur-
face and the rate of storm water runoff. The model is simple and ra-
tionally derived, but only extremely limited data were available to es-
tablish its exact form and values of coefficients. Because the accurate
prediction of instanteneous, or hourly, storm water runoff pollutant
concentrations is required in the quantitative evaluation of storm water
runoff and combined sewer overflow treatment systems, it is recommended
that a study be undertaken to provide the necessary information for the verification or
modification of the storm water quality model format and for the determination of the co-
efficient values.
The w.ater quality requirements criteria for storm water runoff and
combined sewage treatment systems almost always depend upon the
quality and flow characteristics of the receiving waters, which in turn
are totally influenced by upstream conditions and facilities. Whereas
analysis and evaluation of systems within a particular area can be per-
formed and the best system established by the methods presented here-
in, the quantitative effect and inter-relations of conditions outside the
area that may markedly affect the analysis are not evaluated, ft is recom-
mended, therefore, that the procedures developed herein be expanded in application to in-
clude consideration of all wastewater discharges, including storm water runoff from urban
and rural areas, combined sewer overflows, municipal sewages, industrial wastewaters, and
irrigation return waters, to the receiving waters of the drainage basin. The analysis of
an entire drainage basin system would delineate the .extent to which
each discharge contributes to the pollution burden of the receiving wa-
ters under various wastewater management systems. This approach
would assure the best allocation of resources for the protection of the"
waters in the drainage basin.
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The performance of the high-rate treatment processes — dissolved air
flotation and mechanical screening--which provided for the conditions
of this study acceptable systems at least cost was based on limited
laboratory-scale and pilot-plant studies. On the basis of latest avail-
able information which indicates that mechanical screening should be
less costly than and as effective as dissolved air flotation in removing
wastewater pollutants, it is recommended that a program be undertaken to demon-
strate the efficacy of the mechanical screening process described herein to adequately
treat separated storm water runoff and to establish operating parameters and realistic
capital, operating, and maintenance costs.
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Section II
INTRODUCTION
Man's awareness of his environment is growing pronounced and his
concern intense as he becomes more populated, more urbanized, and
more affluent. The need for a safe and potable water supply and the
resulting degradation of that water by its use was most likely recog-
nized far sooner than similar considerations of air and land resource
management, simply because water pollution has manifested itself in
the loss of human life, the loss of fisheries and wildlife resources,
the loss of irrigable crops, the loss of usable water supplies, and the
loss of aesthetic values.
Emphasis was placed initially on the control of sanitary sewage for the
protection of public health and safety. As a result, sanitary wastes
were collected in an underground sewer network, conveyed to some dis-
tant location, and disposed of untreated. Wherever the disposal occur-
red upstream of water supply intakes, natural diminution by dilution
and degradation and subsequent water supply treatment usually com-
bined to afford adequate protection. The runoff from rainfall was car-
ried on the surface or collected and transported in separate storm sew-
ers; or in many cases, the drainage was conveyed in sewers designed
for the simultaneous combined transport of both storm water runoff and
sanitary sewage.
As populations expanded and had greater occasion to come in contact
with their surroundings, the presence of unsightly and malodorous
sludge deposits resulting from the discharge of untreated sewage be-
came unacceptable, and primary sewage treatment was provided. As
the burdens on the assimulative capacity of receiving waters escalated
due to the ever increasing amounts of degradable soluble materials,
the oxygen resources of the receiving waters became overtaxed and
fish and wildlife resources were affected and septic conditions obtained.
This condition was alleviated by the provision of secondary sewage
treatment, but as the demands on the available resources have grown
more critical, emphasis has shifted toward advanced waste treatment
processes for the removal of nutrients and biostimulants to retard eu-
trophication of receiving waters and for the removal of refractory or-
ganic and inorganic substances and toxicants for higher reuse of the
renovated water.
With the accomplishment of more complete control of municipal and in-
dustrial wastewater discharges, other sources of water pollution have
taken on greater significance in their contribution to the overall burden
and are attracting attention and concern. Two such sources originating
within urban areas are combined sewer overflows and separated storm
water runoff.
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Whereas combined sewers may provide adequate capacity to carry
peak storm flows, which are generally several orders of magnitude
greater than the accompanying sanitary flows, sewage treatment faci-
lities do not have the same hydraulic capacity. Therefore during
periods of precipitation, the sewage treatment facility may be unable
to cope with the combined flows so that the excess is diverted from the
treatment plant and discharged directly to a receiving water or water
course. These combined sewer overflows are of particular concern
because they result in the bypass to the environment of untreated sew-
age and present a potential public health hazard.
Both the quantity and quality of separated storm water runoff from an
urban area are highly variable and transient in nature, being dependent
upon meteorological and climatological factors, hydraulic characteris-
tics of the surface and subterranean conduits, and on the nature of the
antecedent period. The pollutants contained in urban storm water run-
off and drainage include street litter, spent foliage, dust and debris
from airborne fallout, eroded soil, animal excreta, fertilizer, insecti-
cides, ice-control chemicals, and many other chemicals and substances.
Also, storm sewers in urban areas often receive cooling waters from
refrigeration systems, wastewater from air pollution control operations,
and sanitary and industrial wastewaters through illegal connections,,
PROGRAM NEED
The need to investigate the storm water runoff and combined sewer pollu-
tion problem and to determine its extent and contribution to the total wa-
ter pollution burden was amplified in 1965 by the U. S. Public Health
Service in a report (Ref. 1) that pointed out the widespread use of com-
bined sewer systems in the United States. A subsequent study (Ref. 2)
conducted by the American Public Works Association for the Federal
Water Pollution Control Administration in 1967 disclosed that there
were 1, 329 municipalities representing 54 million persons in the United
States served totally or partially by combined sewers, and that about
70 million persons were served by separate sanitary sewers. The re-
port further estimates that around 60 to 65 million persons reside in
areas served by separate storm sewers, which were depicted as poten-
tial sources of water pollution. In 1968, another study (Ref. 3) was con-
ducted by the American Public Works Association for the Federal Water
Pollution Control Administration to determine the factors in the urban
environment that contribute to the pollution of urban storm water runoff
and to determine methods of limiting this source of pollution.
This study, presented herein, is directed at the next logical step; name-
ly, the development of a method to assess the extent of the water pollu-
tion resulting from storm water runoff and combined sewer overflow
and the description and cost of suitable facilities to satisfy specified
receiving water quality criteria.
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SCOPE AND OBJECTIVES
To provide adequate and economical solutions to storm water runoff
and combined sewer overflow problems, careful analysis and evaluation
of various alternative systems must be made relative to their total im-
pact on the environment and the community. This program was aimed
at the development of a general method for ascertaining the extent of
pollution occurring as the result of storm water runoff and combined
sewer overflows, and the synthesis, design, costing, and effectiveness
of various alternative water pollution abatement systems. The method
was directly applied to the City of Sacramento, California, which is
characteristic of many older communities in the nation where the ori-
ginal sewer system, usually in the downtown or business district, was
developed on combined sewers. Areas subsequently annexed to the City
were provided with separated storm and sanitary sewers. The study
area thus contains both combined and separated sewers, necessitating
the integration of both systems in terms of their total effect upon the
receiving waters in order to measure the overall effectiveness of any
alternative system.
Seven different conceptual candidate systems were considered for the
City of Sacramento that were believed to encompass, at least in prin-
ciple, most feasible solutions applicable elsewhere in the nation. Two
systems were based on the total separation of sanitary sewage from
storm water flow--one by the construction of either a sanitary or a
storm gravity sewer and the other by the collection and transport of
sanitary wastewater in small diameter force mains. Storage was uti-
lized for two systems, which in combination with other system compo-
nents, provides either surface ponding or near-surface underground
facilities. Two systems employed high-rate treatment processes,
namely mechanical screening and dissolved air flotation. The last sys-
tem was based on the use of large stabilization ponds,
A complete alternative system capable of handling all of the wastewater s-
domestic, commercial, and industrial sewages and storm water drain-
age--generated within the study area, in addition to those transported
through the study area, consists of adequate collection and conveyance,
storage (or no storage), treatment (or no treatment), and disposal com-
ponents. The various combinations of these components, when coupled
with different storm recurrence interval design criteria and the reali-
ties of available storage pond and treatment facility locations, present
an extremely large number of alternative water pollution control systems
for analysis and evaluation.
Although the City of Sacramento was selected in this study, the program
was designed and conducted to provide applicability to sewer systems
throughout the nation with similar characteristics. Specific objectives
of the program were:
To provide sufficient hydrologic, meteorologic, demo-
graphic, geographic, and land-use bases for design of
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alternative systems. Wastewater quantities and qualities
were established by field sampling and analysis.
To develop preliminary designs for each of the alternative
bystems in sufficient detail to assess their ultimate cost.
To estimate costs for the construction, operation, and
maintenance of the alternative systems.
To develop a method for assessing the performance and
effectiveness of candidate water pollution control systems
in meeting specified receiving water quality objectives.
To develop the cost-effectiveness of alternative systems, at
least as pertains to the City of Sacramento.
10
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Section III
GENERAL APPROACH
The management of storm water runoff and combined sewer overflows
so as not to adversely affect the environment is made extremely diffi-
cult due to the highly variable and transient nature of storm water
flows and qualities. This is further complicated when the quantity and
composition of waters receiving these wastewaters are also time vari-
able, albeit to a lesser extent in most cases.
Conveyance system and storage pond hydraulic capacities that are to-
tally adequate and effective at all times cannot be justified economically,
but instead must be designed on the basis of a probability distribution re-
lating capacity with its expected deficiency or inadequacy. Likewise,
the hydraulic capacities of wastewater treatment facilities must be limit-
ed to values that are expected to be exceeded on occasion. Also the
characteristics of the wastewater effluent from these facilities are vari-
able and dependent upon upstream contiguous flow modulation and waste-
water treatment performance characteristics. Finally, the real, quan-
titative effects, both immediate and ultimate, on the receiving waters
can only be described by a frequency distribution.
The "steady-state" techniques usually employed to deal with more order-
ly and less transient sewer systems are grossly inadequate to define,
analyze, and evaluate the reactions of a complete integrated water pollu-
tion control system for storm water runoff and combined sewer over-
flows. This program was directed to the development and application of
general methods that would be much more responsive to the phenomeno-
logical realities of the system and that would permit an assessment
from readily available data of the extent of water pollution resulting from
various systems designed to control storm water runoff and combined
sewer overflows in an urban area.
To provide methods that would have general applicability throughout
most of the nation and that at the same time would assure that no feasi-
ble solution was overlooked in the analysis, a fairly wide range of sys-
tem concepts and options were considered and incorporated into a to-
tally integrated system comprised of a collection and conveyance net-
work, a storage reservoir (or none) with associating pumping facilities,
a treatment process (or none), and a disposal facility.
Hydraulic capacities in the sewerage components without influent flow
regulation were maintained equal. In the cases where a reservoir pro-
vided a means for controlled outflow, the subsequent hydraulic capa-
cities reflected an optimized relationship between the reservoir storage
capacity and the other downstream system components. Pollutant re-
movals in treatment processes were varied to provide differently per-
forming systems for cost effectiveness evaluations.
11
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For conveyance system design, only the peak instantaneous flow ex-
pected to occur during some selected period or recurrence interval is
required. The storm water portion of these flows was estimated using
a modification of the rational runoff method, which lends itself well to
the determination of expected surface runoff quantities from small dis-
crete drainage areas tributary to a single length of sewer Also the
appropriate rainfall intensity-duration-frequency relationships that are
required to convert precipitation into surface runoff have been developed
and are available in most sections of the country. Peak sanitary sewage
flows were estimated using projected populations, per capita wastewater
discharge factors, and a capacity factor; which was a function of total
contributary population. These peak flows were added to the correspond-
ing peak storm water runoff flows to obtain peak combined sewage design
flows.
The determination of storage capacity requirements requires the knowl-
edge of the magnitude and temporal distribution of incoming and out-
going flows. Pond outflow can be controlled to any level and discharge
pattern, but a constant outflow probably best meets associated down-
stream treatment process operating requirements. The determination
of storm water runoff quantities as functions of time at storage reser-
voir locations was accomplished using the unit hydrograph method,
which converts rainfall intensity to runoff flow. Extensive historical re-
cords of hourly precipitation for most locations in the nation are readily
available. The characteristics of the unit hydrograph for particular
drainage basins were determined by field measurement and on the basis
of available information on the relevant characteristics of the drainage
basin. Temporal distribution of sanitary sewage flows was assumed
diurnal in nature and was developed from field measurements and other
existing data. For estimating hourly combined sewage flows, the di-
urnal sanitary sewage function was added synchronously to the storm
water runoff hydrograph.
Flows to treatment and disposal facilities are dependent upon the nature
of contiguous upstream facilities. When a storage pond was provided,
the resulting controlled outflow established the hydraulic capacity re-
quirements of the downstream treatment and disposal facilities. Where
no flow modulation was provided, the peak flow condition, as determined
by the rational method for a given storm recurrence expectancy, estab-
lished the hydraulic capacity requirements.
Preliminary designs were performed on the various system components
for the purpose of estimating construction costs. For the candidate
treatment processes, the preliminary designs were based on target ob-
jectives for wastewater pollutant removals. These removal rates were
then applied to the system performance analysis relating to resulting
receiving water pollutant distribution. All facilities costs together with
associated operational and maintenance costs were converted to an an-
nual basis for the cost comparison of the many alternatives.
12
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To determine the effect of storm water runoff and combined sewer
overflows on receiving waters, a long-term simulated record of storm
water flows and concomitant wastewater constituent compositions were
developed from hourly precipitation records and mixed synchronously
with the corresponding receiving water flows interpolated from his-
torical daily records covering the same period. Concentrations of pol-
lutants in the storm water runoff were estimated on an hourly basis
using a model developed in this program that relates the pollutant con-
centration to the time of pollutant accumulation on the surface of the
drainage area and the amount of storm water runoff from the area0
Background concentrations of pollutants in the receiving waters were
synthesized on an hourly basis from relationships between flow and
quality that were established from available measurements and records.
Overall performance of the totally integrated alternative systems was
ascertained by the simulation of pollutant removals effected in each
system and the subsequent discharge and diminution of the system ef-
fluent in the receiving waters. Finally, for the combination of com-
ponents comprising each complete system, both performance and cost
were compared and evaluated within the framework of acceptable re-
ceiving water standards.
13
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Section IV
THE STUDY AREA
The City of Sacramento, California, selected as the locale for the study,
has both combined and separated sanitary and storm sewers which dis-
charge ultimately to either the American River or the Sacramento River,
which bound the study area on two sides. As the Capital of the State of
California, the City is experiencing extensive reconstruction and urban
redevelopment while retaining large unchanging areas devoted to single-
family residences, and thus provides a land-use mix that is believed
typical of many communities in the United States with combined sewer
systems.
PHYSICAL FEATURES
GEOGRAPHY
The City of Sacramento, California is located at the confluence of the
Sacramento and American Rivers in the south-central portion of the
broad and fertile Sacramento Valley, a part of the Great Central Valley,
which lies between the Sierra Nevada Mountains to the east and the
Coast Ranges to the west. San Francisco is approximately 90 miles
to the southwest, and Los Angeles is 400 miles to the southeast. The
location is shown in Figure 1.
The entire City and a large part of the surrounding County of Sacramento
consist of relatively flat topography. Ground elevations within the City
range generally between ten and 40 feet, averaging about 25 feet above
mean sea level. The foothills of the Sierra Nevada Mountains commence
a few miles to the east of the City.
The City of Sacramento lies within the alluvial plain of the Sacramento
Valley, formed partly by river erosion and partly by river deposition.
Adjacent to the rivers and extending inland for varying distances up to
several miles is a belt of recent quarternary alluvium which has been
derived by the present stream systems. The remainder of the City,
as with a large part of the surrounding region, is covered by the Victor
formation, a river flood plain deposit that has been slightly dissected.
The debris making up the deposit varies widely, both vertically and
laterally, and is heterogeneous, coarse, crudely stratified, and large-
ly unweathered.
The soils within the City consist of those extending inland from the riv-
ers developed on flood plains and recent alluvial fans (infrequent over-
flow), and those at slightly higher elevations developed on old alluvial
plains and terraces. A common characteristic of this latter classifi-
cation is a hardpan layer at the surface of the substrata, generally
15
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SAN FRANCISCO
Figure 1. LOCATION OF STUDY AREA
16
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from one to four feet below the surface. This layer is a hard, rock-
like material varying in thickness up to one foot0 The substrata are
cemented and hardened, and practically impervious.
HYDROLOGY
The American River flowing from the east bisects the City, and dis-
charges into the Sacramento River which, meandering in a southerly
direction, bounds the City on the west.
The Sacramento River is by far the largest stream in California, and
is subjected to extensive regulation upstream and on its tributaries.
It has an annual runoff past Sacramento of 16, 000, 000 acre-ft, equiva-
lent to an average flow of 22, 000 cfs. Under the California Water Plan,
construction work now in progress will divert large quantities of north-
ern California water to southern California. A good portion of this
flow will first pass through the reach of the Sacramento River at the
City of Sacramento. While no precise quantity can be predicted now,
it appears that the minimum flow in the Sacramento River will be on the
order of 5, 000 cfs during the months of April and May. Flows during
August and September would be more nearly 10, 000 cfs. In spite of
the relatively large degree of upstream regulation, there will continue
to be large flood flows passing Sacramento, estimated at approximately
50, 000 cfs as an average peak flow,,
The American River is one of the larger streams in California with an
average annual runoff of 2,700,000 acre-ft. It is regulated some 25
miles above Sacramento by Folsom Dam and Reservoir. Additional
reservoir projects located upstream are planned. Under a program
soon to be implemented, most of the American River runoff will be di-
verted for irrigation and other purposes at Nimbus, a few miles to the
east of Sacramento. Under ultimate development at the American Ri-
ver, it is planned that only sufficient water will be released past the
Nimbus Diversion Dam to provide the water supply for Sacramento and
adjacent communities and to preserve the fisheries resource. The mini'
mum quantity to reach the Sacramento River will thus be only 250 cfs
during certain months of the year.
CLIMATE
The Sacramento Valley enjoys a mild climate with an abundance of sun-
shine. Cloudless skies prevail during the summer and during much of
the spring and autumn. Mountains surround the Valley to the west,
north, and east. Because of the shielding influence of the mountains,
heavy rainfall and excessive winds are rare.
Average annual rainfall within the City is close to 17 inches. Practi-
cally all of this rainfall occurs during the period from November
through April, yet rain in measurable amounts occurs only on about
ten days each month during this rainy season.
17
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Summers are hot and dry with average maximum temperatures of about
90°F and occasional extremes as high as 114°F; nights are generally
cool. Most autumn and spring days are cloudless. Winters are of
moderate intensity, although below-freezing temperatures occur occa-
sionally.
Relative humidity ranges from about 60 to 90 percent throughout the day
during the winter months, and about 30 percent during the summer. The
low diurnal reading is generally noted near mid-afternoon.
The extremely low relative humidity that accompanies high temperatures
during the daytime in the summer months should be considered when
comparing temperatures of Sacramento with those of other cities in more
humid regions. Thunderstorms are few in number and usually mild in
character. Snow falls so rarely and in such small amounts that its occur-
rence may be disregarded as a climatic feature. Heavy fog occurs most-
ly in mid-winter, never in summer, and seldom in spring or autumn.
Light and moderate fogs are most frequent, and may come anytime dur-
ing the wet, cold season. The fog is usually the radiational cooling type
and is confined to the early morning hours. An occasional winter fog,
under stagnant atmospheric conditions, may persist for several days.
Table 1 contains a summary of important climatological data for the
area, which have been compiled in Sacramento since 1849.
18
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Table 1
MEAN CLIMATOLOGICAL DATA FOR SACRAMENTO, CALIFORNIA
Month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Yr
.9
Rainfall,
3.2
3.0
2.4
1.4
0.6
0.1
0
0
0.2
0.8
1.4
3.2
16.3
O
•t
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CITY EVOLUTION
EARLY YEARS
Sacramento had its original beginning in 1839 when Captain Sutter built
his fort at what is now 27th and K Streets and established an embar-
cadero on the waterfront of the Sacramento River just below its con-
fluence with the American River. When gold was discovered at Sutter's
Mill in nearby Coloma in 1848, Sacramento became a boom town. By
July of 1849, there were approximately 100 buildings along the water-
front area now called Old Sacramento.
As shown by Figure 2, which presents the map of the City dated
October 1859, the gridiron street pattern which today characterizes
that portion of Sacramento called the Old City was already established.
Also in evidence on the 1859 map were vast areas of the City that were
subjected to periodic flooding from storm overflows of both the
Sacramento and American Rivers.
Because of severe flooding in 1861 and 1862, the street levels near
the waterfront were raised one story in building height in 1864, accom-
plished simply by filling the original ground floor to the second level.
The attempt to protect against the flooding which plagued the City in
the early years is still much in evidence in the architecture of older
homes with the main floor level elevated approximately one story a-
bove the adjacent ground. Even today, very few residences contain
basements. The flood threat has gradually been alleviated by the con-
struction of an extensive levee system along the Rivers. In more re-
cent times, the Rivers themselves have come under increasing control
through numerous water conservation and flood control projects through-
out their upper reaches.
The original boundaries of the City enclosing a 4. 5-square mile area
remained more or less intact until 1911 when a 9. 5-square mile annex-
ation increased the total area to 14 square miles. Starting in 1946, the
City has expanded areawise through many annexations, until today it en-
compasses 94 square miles of territory, some of which is yet undevelop-
ed and devoted to agricultural purposes, as shown in Figure 3.
RECENT YEARS
Characteristic of many other cities at comparable stages of their devel-
opment, the older portion of Sacramento between the riverfront and the
Capital to the east experienced an undesirable change starting in the
late 1920's. The strong relationship between river traffic, railroads,
industry, and business no longer provided a common bond and the area
was abandoned to the forces of neglect and changed land use. With the
business center moving eastward away from the deteriorating core, the
20
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nmnnnninDann'
puuuuuujann
GIJULJUU JL j
Figure 2. MAP OF THE CITY OF SACRAMENTO - 1859
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1 „,="; ,-'I1'" ' if -X-"
--<1
Figure 3. SACRAMENTO CITY BOUNDARY - 1969
22
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blight was gradually infecting a larger and larger area of the City.
Recognizing the need for corrective action, the City Council in 1948
authorized a survey of the deteriorated area, which led subsequently to
an allocation of federal funds and the activation of the Sacramento Re-
development Agency in 1950, pursuant to the provisions of the California
Community Redevelopment Law of 1945, The results achieved through
urban renewal to date are far-reaching. Much of the blighted area with
attendant problems has been cleared. Already in evidence is a well-
planned mix of new commercial facilities, with more to come, as shown
in Figure 4,, As a matter of interest, the historic Old Sacramento or
Embarcadero area long the waterfront will be restored or reconstructed
to capture again the exciting era of the bustling frontier city.
Somewhat concurrently with the work of the Redevelopment Agency, the
State Legislature in 1959 created the Capital Building and Planning Com-
mission to provide for the orderly development of future State buildings
in the City of Sacramento. A master plan has been developed with a
stated purpose to give California a noble and monumental seat of govern-
ment. The comprehensive plan projects requirements for an orderly
growth of facilities to accommodate future State employees., The State
is acquiring land on all sides of the Capital, excluding the commercial
shipping area to the north, in order to meet its future needs. Modern
high-rise office structures are already in evidence and portend the dra-
matic changes yet to come.
Sacramento State College is located along the American River in the
eastern section of the City. The College enrollment in 1969 was close
to 10, 000 students, and is expected to double in the next 12 to 14 years.
Even as late as 1950, the majority of the Sacramento metropolitan area
population resided within the boundary of the City. Since 1950, however,
an explosive population growth has occurred in the area surrounding the
City, primarily to the northeast. The sharp increase in growth rate of
the metropolitan area during the 1950's was caused in part by the ex-
pansion of two major employers, McClellan Air Force Base and Aerojet-
General Corporation. With other industrial companies also selecting
Sacramento for the site of new plants, the area's economy which pre-
viously had been based primarily on government and agriculture now in-
cluded a significant industrial component.
Sacramento is the county seat of Sacramento County. The estimated
population of Sacramento County in 1968 was 670, 000 of which approxi-
mately 275, 000 resided within the City of Sacramento.
The City of Sacramento and the surrounding metropolitan region is expeo
ted to continue as an important and growing commercial and industrial
center. The recent development of the Sacramento-Yolo Port which ac-
commodates oceanic vessels will enhance the area as a desirable loca-
tion for new industry. Along with the benefits to be derived from new
23
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1. Sacramento Redevelopment Area
2. Sacramento Central Business District
3. California State Capitol and Complex
4. Federal Buildings
5. Sacramento River
6. American River
7. Sacramento State College
8. Lake Folsom
9. California State Fair (new site)
Figure 4. AERIAL PHOTO OF CENTRAL SACRAMENTO
LOOKING EAST
24
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industrial development, the economy of Sacramento will continue to be
based strongly on government and agriculture, both of which are ex-
pected to expand in future years.
GOVERNMENT
In 1921, the City adopted a City Charter which provides a 9-member
elected City Council. The members of the City Council are elected
by the city-at-large to 2-year terms. There are no other elected City
officials. By custom, the councilman receiving the most votes in the
biennial election is named Mayor by the Council. The City functions
under a Council-Manager form of government with the City Manager
responsible to the City Council.
FINANCIAL
The 1968 total assessed valuation within the City was $525 million,
down slightly in the past several years because of extensive land clear-
ing for new freeway construction and urban renewal. Historically,
assessed valuation represents about 25 percent of market value. The
1968 City tax rate was $2. 17 per $100. 00 of assessed valuation, which
together with other diversified revenue sources provides funds for
governmental services. Water and sewer utilities operated by the City
charge rates which are adequate both to support operations and provide
capital development funds, including debt service costs for these uti-
lities.
Currently the City budget totals about $35 million which includes those
activities such as the Department of Water and Sewers which functions
on a self-supporting basis. Debt obligations as of August 1968 totalled
$113 million, which reduced to $88 million after subtracting all self-
supporting bonds. The $88 million bonded debt represents about 17
percent of assessed valuation.
THE COMBINED SEWER AREA
RELATION TO CITY
The primary study area of this program is by definition that area covered
by the combined sewer system in Sacramento. However, many aspects
of the combined sewer investigation extend beyond this specific area into
other parts of the City and metropolitan region. The primary study area
is further defined as that part of the overall combined sewer system that
collects and conveys municipal sewage via the combined system to a
common location.
While also a part of the total system, the municipal collection districts
north of the American River which feed into the combined system are
not considered a part of the primary study area. Storm water separa-
tion projects in the upper reaches of the combined sewer system are
25
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considered within the primary study area, since sanitary sewage con-
tinues to be conveyed by the older combined sewers, which downstream
remain truly combined. In this report, the primary study area hence-
forth will be called the Study Area, the separated storm water part of
the Study Area will be called the Separated Area, and the truly com-
bined part of the Study Area will be called the Combined Area.
The Study Area, shown in Figure 5, covers 18. 8 square miles of the ^
older or central portion of the City, commonly referred to as the Main
City Section. For many years the Study Area comprised the entire
City plus what was then considered to be suburban countryside. The
Study Area is, therefore, the locale for most of the activities relating
to city growth and characterization as described previously.
POPULATION
With its general location in the older developed portion of Sacramento,
the Study Area has in recent years experienced, and will continue to ex-
perience, a slower growth rate in residential population than the less-
developed surrounding regions. On the other hand, primarily because
of the impact of State government and Sacramento State College growth,
the work force or employee population within the Study Area is expected
to grow at a much faster rate in the years to come than the correspond-
ing residential population.
Because of the unusually high ratio of employees to residents, it was
deemed advisable to consider the employee population separately. An
employee is considered as one who is either regularly employed in the
Study Area or for other reasons spends approximately eight hours each
day within the Study Area away from home. Thus, a tourist, a shopper,
or a student might contribute to the employee population. The employee
may or may not also be a resident of the Study Area.
From estimates prepared by the City Planning Department, the July 1968
residential population of the Study Area was 111, 395. Based on data col-
lected from several sources, the July 1968 worker population of the Study
Area was estimated at 93, 913. The above populations do not include the
areas to the north of the American River which contribute sanitary sew-
age to the combined sewer system.
LAND USE
The structure of the Study Area from a land-use standpoint is typical of
many other American cities in comparable stages of their evolutionary
development. As the City grew, changing patterns in land use developed
which, for varying reasons, resulted in sub-standard residential housing
near the central core. Fortunately for Sacramento, the impetus of ur-
ban renewal plus the initiation of other long-range planning programs
have served to arrest this undesirable trend in much of the older areas.
26
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SACRAMENTO
HAGGINWOO
Figure 5. SACRAMENTO COMBINED SEWER SYSTEM
27
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The tremendous growth of the Sacramento metropolitan region during
the 1950's has already been mentioned. This surge of population into
surrounding suburbs is, of course, a phenomenon not unique with
Sacramento. As elsewhere in the country, the conversion of open
land to mass housing developments, shopping centers, and other atten-
dant facilities could not help but alter the orientation of commercial
and business activities within the City.
While a few pockets of undeveloped land still exist, the Study Area to-
day may be characterized as essentially built-up. The aerial photograph
covering the entire Study Area and adjacent regions presented in Fig-
ure 6 visually depicts this condition. Future residential growth will
be derived primarily by transition from single-family to multiple-
family housing. Future worker growth will be accommodated by dis-
placing present residential and light commercial areas with construc-
tion of high-rise facilities. The commercial and nongovernmental busi-
ness activity within the Study Area is expected to grow moderately a-
long with the residential population. Likewise, because of available
land constraints, industrial activity within the Study Area will experi-
ence only moderate growth. Total utilization of available land and a
much more intensive land use is projected for the future. Rates of
growth will be increasingly constrained with time as the Study Area
gradually approaches saturation.
28
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'
1. California State Capitol
2. Redevelopment and Central Business District
3. U. S. 40 - Interstate 80
4. Sacramento River
5. Port of Sacramento
6. American River
7. Sacramento Municipal Airport
8. Southern Pacific Railroad
9. Western Pacific Railroad
10. U. S. 50-99
11. Sacramento State College
Figure 6. AERIAL VIEW OF STUDY AREA AND SURROUNDING REGION
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Section V
THE WASTEWATER SYSTEM
There are over 30 organizations within Sacramento County providing
sewerage services, representing for the most part incorporated cities,
county sanitary districts, and local maintenance districts. Approxi-
mately 75 percent of the 670, 000 population of the County in 1968 was
served by these community-type sewer systems. This percentage is
quite high and is attributable to the progressive attitude of the County
Department of Public Works in creating the necessary sewer dis-
tricts to keep pace with the rapid growth.
Individual sewage disposal facilities are required in the areas not
served by community sewer systems. The County Health Department
has cognizance over individual systems that includes approval of plans
before issuance of building permits. County zoning ordinances require
new residential developments to maintain larger minimum lot sizes in
order to quality for approval of individual septic-tank and leaching-
field systems. This requirement favors the development of public sew-
er systems where higher density land use is evolving.
Nearly all of the sewage authorities within the County provide primary
or secondary treatment to waste flows which are discharged typically
either to small streams which flow to the American or Sacramento
Rivers or directly to the Rivers.
Since the Sacramento and American Rivers have huge watersheds ex-
tending above Sacramento County, a considerable amount of sewage is
discharged to these Rivers before reaching Sacramento. The waste
products associated with agricultural activity in the Sacramento Valley
also contribute to the pollution of the Rivers. The effects of these re-
mote discharges at Sacramento are ameliorated due to the dilution pro-
vided and the natural purification processes taking place in the streams.
Nearby, but outside of the County, the West Sacramento Sewer District
operates a sewer system and treatment plant immediately across the
Sacramento River and adjacent to the Study Area. The treatment plant
provides primary treatment.
The City of Roseville, located just to the north of the County boundary,
operates a sewer system with treatment plant that discharges via a
creek which flows to the American River through the north central por-
tion of Sacramento County0 The major thrust of future urban growth
in the area appears to be toward Roseville from Sacramento.
The one other major waste contributor within the general area is the
American Crystal Sugar Company located in Clarksburg on the west
31
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bank of the Sacramento River and south of the City, The sugar pro-
cessing operation is seasonal in nature and the liquid waste receives
treatment by settling tanks and holding ponds with effluent discharging
to the Sacramento River.
FACILITIES DESCRIPTION
The City's overall sewer service area contains a system of storm and
sanitary collection sewers, three major pumping installations, 29 sani-
tary and 67 storm water lift stations, and two treatment plants with
appurtenant outfall facilities. The sewers in the City comprise a sys-
tem approximately 900 miles in length and range in size from 6-in.
sanitary lines to 114-in. combined sewage trunk drains.
Within the City of Sacramento service area, the City Engineer, report-
ing to the City Manager is responsible for the City's municipal water
supply and wastewater systems, which are operated by the Division of
Water and Sewers. The Division has a staff of approximately 230 em-
ployees including engineers, technicians, clerks, and operating and
maintenance personnel.
The City's sewer service area, shown in Figure 7, in 1968 encompassed
58 square miles, with an estimated population of 279, 000. Of this area,
six square miles containing 38,000 persons lies outside the City limits.
The total area of the City is 94 square miles. The portion of Sacramento
not included in the City's sewer service area is provided with sewage
collection and disposal by five different systems, three of which have
their own treatment plants. These systems were installed by County
sanitation districts in areas subsequently annexed by the City. The sys-
tems continue to impose their own tax rates, connection charges, and
service charges and are operated under the control and supervision of
the County Department of Public Works. County Sanitation Districts
Nos. 1 and 2, which have contractual arrangements with the City for
sewage treatment, serve areas both inside and outside the City limits
and account for the only service of this type provided by the City for
nonresidents.
Prior to about 1948, which marked the beginning of an extensive growth
through annexation, the City's sewer service area consisted essentially
of the area covered by the combined sewer system and is the Study Area
of this program. The combined sewage flows by gravity to a common
point, Sump No. 2, near the southwest corner of the Study Area, and is
pumped to the Sacramento Main Treatment Plant located in the south-
west section of the City on a 35-acre site. The Main Treatment Plant,
which accepts sewage from several other service areas, was completed
in 1954 at a cost of $40 4 million with a nominal design capacity of 76
mgd. . This plant, which soon will incorporate secondary treatment,
provides primary treatment before discharging disinfected effluent
through an outfall line to the Sacramento River.
32
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HIVE"
MEADOWVIEW
TREATMENT PLANT
STUDY
LEGEND:
J*"»»o* CITY LIMITS
| I CITY SEWER
' SERVICE AREA
j%%^ COUNTY SANITATION
DISTRICT NO. i
£$$$$•§} COUNTY SANITATION
RVWX3 DISTRICT NO. 2
A SEWAGE TREATMENT
PLANT
Figure 7. WASTEWATER TREATMENT SERVICE AREAS IN
CITY OF SACRAMENTO
-------
The City also owns and operates the Meadowview Treatment Plant lo-
cated near the southern City limits along the Sacramento River. This
2, 6-mgd plant, acquired by the City through annexation, provides pri-
mary treatment and disinfection.
SEWERAGE SYSTEM DEVELOPMENT
Design drawings prepared for construction of segments of the existing
combined sewer system are on file in the Sacramento City Engineer-
ing Department which date back to circa 1880. Some portions of the
system are undoubtedly older. The construction and maintenance of
sewers and storm drains have been a City utility operation -~ince 1878.
In common with many cities throughout the country, the combining of
sanitary wastes and storm water into a single sewer system was adopt-
ed as a basic policy in Sacramento for all sewer system construction
over a time span of many years. The combined sewer system func-
tioned adequately and fulfilled its intended purpose in meeting the mini-
mum needs of the City, particularly during the period when the popula-
tion was only a fraction of that served today and treatment of sewage
prior to river disposal was not considered mandatory.
Because of extensions to the combined sewer system, certain portions
of the larger trunk sewers experienced severe overloading from time
to time, which was relieved by construction of bypass sewers to other
trunk lines. Over a span of several decades, these cross-connections
were added to the system together with various types of diversion weirs.
The combined sewer system reached its maximum areal coverage in
the late 1940's. By that time, the extension outward had in some in-
stances reached the boundary of other sewerage districts and elsewhere
the decision was made not to further burden the system with additional
storm water flows. Also, in keeping with the awareness of the times
on the need for improvement, efforts were undertaken to provide treat-
ment facilities for sanitary sewage. No combined sewers have been
constructed in Sacramento subsequent to 1946.
During the early years of the system, all sewage flowed to a common
pumping station, and thence discharged directly to the Sacramento Ri-
ver. The original pumping station was replaced in 1908 by the existing
Sump No. 1, which is shown on Figure 8. As the City grew to the east
and south, trunk lines were constructed to a new pumping station, the
existing Sump No. 2, built in 1916. Both pumping stations have been
expanded from time to time. Until 1954 when Sacramento completed
its first wastewater treatment facility, all flows were discharged un-
treated directly into the Sacramento River.
In. 1954, a 72-in. force main was placed in operation from Sump No, 2
to the Sacramento Main Treatment Plant. From that time, all flow by-
passes Sump No. 1 except during storms and is pumped via the force
34
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OO
tn
Figure 8. EXISTING COMBINED SEWER SYSTEM
-------
main from Sump No. 2 to the treatment plant. Depending upon the
severity of a particular storm, the combined flows are diverted either
totally or partially to the Sacramento River directly from Sump No. Z,
with Sump No. 1 also utilized as needed for additional flow diversion
directly to the River.
Three separate sanitation districts north of the American River and
outside the City previously discharged sanitary sewage to the combined
sewer system. The area encompassed by two of these districts, North
Sacramento and Hagginwood, has since been annexed by the City and a
single force main now discharges into the upper reaches of the com-
bined sewer system and continues via gravity flow to Sump No. 2.
County Sanitation District No. 2, located partially within the City, also
discharges sanitary flow through a force main under the American Ri-
ver to the combined sewer system in a similar manner.
Experience from system overloading and attendant flooding gave cause
for the City to undertake measures to update the combined sewer sys-
tem and relieve the chronic flooding which persisted in certain areas,
even from storms of moderate intensity. The earlier method of re-
lieving the system at critical points by the construction of cross-con-
nections between main trunks was no longer considered feasible. In
fact, with the passage of time, the rationale used in the selection of
cross-connection routings was no longer in clear evidence in some
instances.
Starting in the early 1960's the City undertook a new approach in the
modernization of the combined sewer system. An improvement pro-
gram was initiated wherein new separated storm sewers were con-
structed in selected areas, with the existing combined sewer system
continuing to be utilized for sanitary flows only. There were several
reasons for selecting the new separate system for storm water runoff
rather than sanitary sewage. First the areas selected were located
conveniently near discharge points to the Rivers. Second, the storm
flows would not, by standards heretofore acceptable, require additional
treatment facilities. Third, the disruption to existing sewer facilities
would be considerably less because residential sewer connections would
not require disconnection and reestablishment. Finally, the basic prob-
lem of relieving the combined sewers during storms would best be serv-
ed with a modern adequately designed storm sewer system.
After completion of two of the separation projects, the residents of
Sacramento in 1964 voted approval for the sale of $15 million in bonds
for continuation of this improvement work. Subsequently, three other
separation projects have been implemented under the bond program. In
addition, one other separation project has recently been completed in
the industrial district along the American River, financed through for-
mation of a local sewer assessment district.
36
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COLLECTION AND CONVEYANCE
The Study Area covers 10,772 acres which is served by the combined
sewer network (see Figure 8). Of this total area, seven separated
storm water sewerage systems cover 2, 881 acres. Also, there are
two parcels of land--308 acres at Sacramento State College and 545
acres along the American River adjacent to the Elvas Freeway--that
presently are not served by any type of storm sewer system. There
remains an area of 7, 038 acres where the system continues to function
as a truly combined sewer system, receiving both sanitary wastes and
storm water drainage.
The portions of the Study Area where the seven separated storm water
systems have been superimposed over the combined sewer system to
form the Separated Area are shown in Figure 9. Typically, each
storm water system drains to a lift station, identified in Figure 9,
from whence the runoff is discharged to one of the Rivers through a
short force main. Treatment of separated storm water is not provided,,
At present, the storm water conveyance system identified by Sump A
in Figure 9 discharges back into the combined sewer system. This was
ignored in this study on the assumption that the separated storm flow
•will eventually be accommodated through adjacent facilities to the south
in County Sanitation District No. 1.
There are no immediate plans in progress for construction of new sep-
arate storm systems within the Study Area. Meanwhile, overloading
of the combined sewer system continues to occur, albeit to a lesser
degree than experienced prior to initiation of the improvement program.
TREATMENT
Except when combined sewer overflows necessitate direct diversion to
the Sacramento River, all sanitary flow from the combined sewer sys-
tem is pumped approximately two miles to the Main Treatment Plant
from Sump No. 2 through a 72-in, force main. The maximum peak dis-
charge to the treatment plant is about 86 mgd0 In addition to the flow
from Sump No. 2, the Main Treatment Plant receives sanitary sewage
from County Sanitation District No. 1. In recent years, it has been the
practice during moderate storms to split the combined flow from Sump
No. 2 between the Main Treatment Plant and the River. For larger
runoffs, all combined flow is bypassed to the Sacramento River.
Planning is currently in progress for construction of biofilter second-
ary sewage treatment facilities at the Main Treatment Plant which would
improve effluent quality in line with higher anticipated receiving water
quality standards. The improvement program will also include increas-
ing primary treatment capacity from a nominal 76 to 95 mgd.
37
-------
OJ
00
EXISTING SUMP
NEW DtSKJN SUMP
STUDY AREA BOUNOitfY
SEPARATED STORM FLOW
Figure 9. EXISTING SEPARATED STORM WATER SEWER SYSTEMS
-------
MAIN SUMPS
Sump No. 2 contains eleven pumps arranged as shown in Figure 10.
Because of the configuration of incoming trunks and the baffling of
sump wells, only Pumps No. 5 through 8 are used for normal sanitary
flows, with Pumps No. 1 through 4 used when flow depth in the well ex-
ceeds 3. 5 feet. Pumps No0 1 through 8 can be utilized either for flows
to the treatment plant or to the River, with flow quantities adjusted by
selection of pump or combination of pumps of varying capacities. Pumps
No. 9 through 11 are used only for diversion of combined flows to the
Sacramento River.
The Sump No. 2 pumps are protected by manually cleaned vertical bar
screens. Screenings are hauled away by truck. No flow metering or
chlorination facilities are provided. All pumps have electrical motor
drives energized from a single transformer station. The pump station
is manually controlled by visually gaging incoming sewage levels and
selecting pumps as required. The necessity for bypassing to the Ri-
ver during a storm is determined by the operator. A continuous 24-
hour watch at the station is required.
At present, all flow normally bypasses Sump No. 1 and flows by gravity
through a 60-in. trunk to Sump No. 2. However, during periods of ex-
cessive rainfall, the inflow is pumped from Sump No. 1 directly into the
Sacramento River through a 60-in. outfall. As shown in Figure 11,
there are six pumps at the station, with a total capacity of 240 mgd.
Three of the pumps are electrical motor driven and three are gas en-
gine driven.
Sump No. 1 is normally unattended. The three electrical motor driven
pumps may be controlled by the operator at Sump No. 2, but an atten-
dant is required at the station to operate the gas engine driven pumps.
The cleaning of bar screens also requires an attendant during periods
of pumping.
WASTEWATER AND RAINFALL CHARACTERISTICS
Information on the characteristics of untreated combined sewage and
separated wastewater runoff during dry weather and wet weather was
obtained through a program of field sampling and laboratory analysis.
Due to the timing of program commencement in relation to the wet-
weather season in Sacramento, and the need to establish certain waste-
water characteristics early in the study, estimated values were used
until such time as they could either be verified or modified.
The locations of sewage sampling and flow measurement recording sta-
tions within the Study Area were selected on the basis of providing the
most representative and meaningful data for the design and evaluation
of the proposed candidate systems for treatment. Every attempt was
made to provide good areal distribution, to provide simultaneous
39
-------
o
LJ LJ LJ LJLJ LJ
M0MIKJAL PUMP CAPAC
Figure 10. SCHEMATIC PLAN - SUMP NO, 2
-------
it-
MO.
-i
EXCEPT WHEN <=>'JMP \
MO.'Z OVERLOADED
•
-------
determination of quantities and compositions of the several discrete
types of wastewater streams produced in or transported through the
area, and to provide adequate information on the hydraulics of the
present combined sewer system.
WASTEWATER SAMPLING
Sixteen sampling and measurement stations were selected to charac-
terize combined sewage flow. Separated storm water runoff was ob-
served at only one sampling station, which required three upstream
measurement stations for proper flow determination. The sampling
station for the separated storm water was situated at the junction of
three storm sewers and provided a composite of the entering storm
flows. Locations of wastewater sampling stations are shown in Figure
12. Stations 1 through 16 were situated on combined sewers and Sta-
tions 17, 17A, 17B, and 17C were located on separated storm sewers.
Station 1 was located approximately 600 feet upstream from Sump No. 2
on the 60-in. sewer line arriving from the vicinity of Sump No. 1.
This sewer line is identified as Trunk D.
Station 2 was located on the 114-in. sewer line, identified as Trunk B,
approximately 2, 500 feet upstream from Sump No. 2. The sewage at
this point is representative of combined flow from a predominantly
residential area. Only single lines with relatively small drainage
areas flow into the 114-in. pipe below the sampling station. All man-
holes on the 114-in. sewer between Sump No. 2 and Station 2 are per-
manently sealed because of the potential surcharge condition of the sew-
er.
Station 3 was located approximately 3, 000 feet upstream from Sump No.
2 on the 108-in. sewer line identified as Trunk C_ One 12-in. and one
18-in. line intercept the sewer between the sump and the sampling
station. This sewer provides the major drainage from the Old City or
gridiron-street-pattern portion of the Study Area. All manholes on the
108-in. sewer between Sump No. 2 and Station 3 are permanently sealed
because of the potential surcharge condition of the sewer.
Station 4 was located on a 60-in0 sewer line serving the southern and
eastern sections of the Old City area, which together with another 60-in.
pipe, is the principal contributor to Sump No0 1. Results from this
station, in conjunction with Station 5, provided information on com-
bined overflows at Sump No. 1.
Station 5 was located on a 60-in. sewer serving the central and western
sections of the Old City area that comprises, with the addition of the
sewer underlying Station 4, almost all the combined sewage flow from
the Old City area that is not transported to Sump No. 2 via the 108-in.
Trunk C sewer.
42
-------
Figure 12. LOCATION OF WASTEWATER SAMPLING STATIONS
-------
Station 6 was chosen to establish realistic sanitary sewage flows and
loading factors for the large transient or nonresidential employee
population that exists in the Old City area. This station was located
on a 24-in. sewer line that receives the 10-in. building connection di-
rectly at the sampling manhole. The building connection serves the
State Resources Building, a large office facility.
Station 7 was placed on a 56-in. sewer line just downstream of a re-
presentative diversionary or relief structure wherein a smaller pipe,
in this case the 56-in. line, intercepts at right angles and has a higher
invert elevation than the larger 108-in. pipe with the entire smaller
pipe section removed in the larger pipe. Thus, during low-flow con-
ditions, all flow from the influent 56-in. line is diverted to the 108-in.
sewer.
Station 8 was located on the 108-in. sewer line flowing from the Old
City area immediately downstream of where it is intercepted by the
56-in0 sewer monitored at Station 7. This station, coupled with
Station 7, provided information on the composition and volume of the
combined sewage.
Station 9 was located on the 84-in. sewer inlet to, and 150 feet up-
stream from, Sump No. 1. The monitoring of this station showed
the flow conditions during dry-weather periods and the flow measure-
ment and characteristics of combined sewage pumped by Sump No. 1
during overflow periods.
Station 10 was located near the terminus of a 36- by 42-in. brick
elliptical combined sewer in the Old City area -where it discharges
into a 42-in0 diameter sewer0
To characterize combined sewage flows generated in the commercial
Old City area, Station 11 was located on a 33-in. sewer line at the
northeast corner of Capitol Park upstream of its later connection
with the large 108-in. collector.
Station 12 was located on a 45-in, sewer line which serves both a re-
latively small combined sewage area in the northeast section of Old
City and a separate sanitary system in the northern part of the Study
Area, in addition to the large exogenous sanitary sewage flow from
County Sanitation District No. 2, situated across the American River
to the North. This line has been observed on occasion to be sur-
charged.
Station 13 was located on a 60-in. inlet to Sump No. 2, approximately
1, 000 feet upstream from the sump. This sewer line is identified as
Trunk A. In conjunction with the other three trunk sewers tributary
to Sump No. 2, (Trunks B, C, and D) the integrated characterization
of the combined sewage produced in the total Study Area was obtained.
44
-------
To characterize the separate sanitary sewage originating in a resi-
dential area within the Study Area, a sampling and measurement point
was located on a 30-in. sewer at Station 14, upstream of any storm
water contributions.
Station 15 was located on a 45-in. combined sewer that also services
the sanitary flow from a residential area provided with a separate
storm water system.
The sanitary sewage from the County Sanitation District No. 2, lo-
cated north of the American River and outside the Study Area, was
characterized at Station 16. Results obtained here on the composi-
tion of the sewage were used to also characterize the other significant
exogenous sanitary flow from the North Sacramento-Hagginwood area,
also outside the Study Area.
Station 17 was located on an 84-in. sewer line approximately 100 feet
upstream from a lift station for the discharge of separated storm wa-
ter runoff to the American River from a predominately residential
area. This 84-in. storm sewer is fed by three separated storm sew-
ers of 36-, 45-, and 48-in. diameter in close proximity to Station 11,
Stations 17A, 17B, and 17C were located, respectively, on these tri-
butary storm drains.
The characterization of the combined sewage and storm water during
six wet-weather episodes was performed by collecting samples and
measuring flows at each of the 19 sampling locations at, as nearly as
practical, the commencement of rainfall, three hours thereafter, and
approximately 12 to 18 hours after the commencement of sampling.
Actual relations between the time of wet-weather wastewater sampling
and the time and intensity of rainfall at the U. S. Weather Bureau rain
gage situated at the U. S. Post Office in Sacramento are presented in
Figure 13. To properly evaluate the variations in quantity and quality
of sanitary sewage, the dry-weather measuring and sampling effort
was conducted over a single continuous 24-hour period. Representa-
tive samples and measurements were taken at 2-hour intervals at 16
sampling stations. The 24-hour period, commencing on a Tuesday,
was one that had been preceded by approximately 20 days with no re-
corded precipitation in the vicinity of the Study Area.
The wastewater flows were established at manhole sampling stations
by measuring depth of flow at the station. Whenever this procedure
was not possible due to surcharge conditions, the flows were deter-
mined from the hydraulic grade line, which was ascertained by mea-
suring the depth of flow in the upstream and the downstream manholes.
Relative rim invert elevations were established by field survey for all
manholes, including those upstream and downstream, permitting the
determination of flow depths from the distance between the water sur-
face and the manhole rim. These data are presented in Table 2. The
45
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0.3
0.2
0.2
0.1
0.2
.£ 0.1
v
_i
if o
z
<
cc
STORM NO. 1
10 DEC 68
STORM NO. 2
h- 13 DEC 68
STORM NO. 4
5 FEB 69
0.2
0.1
0.2
0.1
STORM NO. 5
* 23 FEB 69
STORM NO. 6
5 APR 69
1 I I I I I I I I T
SAMPLING PERIODS
O
STORM NO. 3
18 JAN 69
a a
a a
a a
a J
20 2224
"24 2 4 6 8 10 12 14 16 18 20
TIME OF DAY, hr
Figure 13. WET-WEATHER WASTEWATER SAMPLING
PERIODS IN RELATION TO OBSERVED RAINFALL AT
U. S. POST OFFICE
46
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Table 2
SAMPLING STATION FIELD SURVEY DATA
Up-
Up-
Down-
stream stream stream
Sta-
tion
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17A
17B
17CC
Rim
Elev. '
57. 18
50.21
51. 12
50. 00
50. 00
47.59
49.77
50. 00
50. 00
50. 00
50. 00
55.38
50. 00
50. 00
50. 00
50.00
48. 17
48. 39
Invert
Elev.
35. 18
39. 58
36. 34
38. 50
36.60
10 -in. Pipe From
35.84
33.60
35. 10
38. 90
39. 30
34.75
36. 88
43. 40
36.09
40.70
37. 30
29. 17
32.39
Rim
Elev.
63.47
50.39
51.72
53. 14
50.82
State Water
50. 00
50. 00
50. 01
48. 64
49.79
48.78
54.98
50.40
45.99
_
50. 29
47. 39
46. 37
Invert
Elev.
35. 89
39.74
36.65
39. 14
36.72
Resources
36.00
34. 00
36.01
39.34
39.79
35.36
36.91
43.70
36. 24
_
37. 49
29.72
32. 37
Rim
Elev.
_
50.00
50. 13
51.73
51. 73
Building
48.24
48.66
51.03
51.52
50. 80
49.93
55.75
50. 49
47. 27
49.76
48. 94
51. 03
51. 03
Down-
stream
Invert
Elev.
_
39.22
36. 05
38. 15
38. 15
35.49
33.08
34. 61
38. 72
39.10
33. 34
36.50
43. 29
35. 97
39.76
24.24
28. 03
28. 03
Upstream
Slope,
%
0. 064b
0. 0426b
0. 0572b
0. 082b
0. 06 3b
0. 042b
0. 180b
0. 252
0. 105
0. 130
0. 054b
0.272
0. 130
0.043
_
0. 087b
0. 172b
-0. 0067
Down-
stream
Slope,
%
_
0. 0815
0. 0690
0.092
0.066
0.095
0. 180
0. 204b
0. 080b
0.051b
0. 176
0. 112b
0.046
0.0 34b
0.52b
1.03
0. 247
1.62
Upstream
Pipe Dia.
in.
60
114
108
60
60
56
108
84
42
30
45
60
24
45
24
36
45
48
Down-
stream
Pipe Dia.
in.
60
114
108
60
60
56
108
84
42
33
45
60
24
45
24
36
45
48
Full
Flow,
cfs
65. 0
300
305
73. 0
64.0
46.0
520
290
28.0
12. 0
28. 0
85.0
4. 8
22.0
16. 0
19.0
50. 0
All elevations are relative
Slopes used to calculate full pipe flows
Hydraulic gradient slope to be used to calculate flow at station 17C
-------
flow was calculated from these measurements using Manning's equa-
tion, q = 1. 49ar°'6?S°'5/n, where q is How in cfs, a is wetted
cross-sectional area in square feet, r is wetted hydraulic radius in
feet, S is slope of water surface or invert, and n is roughness
coefficient. The roughness coefficient was assumed to be equal to
0. 013, a design value used by the City of Sacramento Engineering
Department.
All samples collected during both dry-weather and wet-weather epi-
sodes were analyzed for total and volatile suspended solids, settle-
able solids, biochemical oxygen demand, chemical oxygen demand,
and fecal coliform concentrations and pH value.
PRECIPITATION
Rainfall in the Study Area was characterized by the U. S. Weather
Bureau at the most representative reporting weather station. The
location of the reporting station changed several times during the
18 years of continuous rainfall record from June 1950 to June 1968
that was applied to the unit hydrograph. For the period from 1 June
1950 through 19 November 1958, it was located at the Post Office at
9th and I Streets in downtown Sacramento. Thereafter it was located
1. 5 miles to the southeast at 23rd and R Streets until 29 September
1964, at which time it was returned to the Post Office at 9th and I
Streets. Beginning with 1 January 1964 and throughout the remainder
of the continuous record used in this program, the municipal airport,
located 4. 5 miles to the south of the Post Office, was the reporting
station. The several rain gage locations and their relation to the
Study Area are shown in Figure 14.
Total daily rainfall recorded at the Post Office during the period of
the sewage characterization program is presented in Figure 15.
MUNICIPAL SEWAGE
The overall flow and composition of municipal sewage converging at
Sump No. 2 could not be ascertained directly. Sump No. 2 is used to
control flow discharge into the Main Treatment Plant, resulting in
rather frequent surcharging of the lower tributary trunk sewers. It
was found that this nonuniform flow condition due to storage occurred
for about 1. 5 to 2 miles upstream from Sump No. 2.
Mean daily flows are quite variable even during dry-weather episodes
due to, among other things, extensive and excessive use of water for
lawn and shrubbery irrigation. The latest available records (Ref. 4)
on the average monthly discharge rates from Sump No. 2 to the Main
Treatment Plant indicate that for the summer months of June 1967 and
July, August, and September 1966 the sewage flows were 43. 5, 40. 3,
57.7, and 54. 5 mgd, respectively. Corresponding monthly rainfalls
48
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Figure 14. LOCATION OF RAIN GAGES
49
-------
2.0r
1 I I I I T
1 I I
i i i i i n i i i i i i i i i r
1968-1969
o
z
<
cc
5 10 15 20 25
NOV
5 10 15 20 25
DEC JAN FEB MAR
Figure 15. DAILY RAINFALL - U.S. POST OFFICE
I I I
10 15 20 25
APR
-------
as recorded at the Municipal Airport were 0. 60, 0. 10, 0. 00, and
0. 07 inches, respectively. Diurnal variations in the dry-weather
sanitary sewage characteristics were established on the basis of
analysis of stations upstream from the influence of Sump No. 2.
Figure 16 shows the observed diurnal variation in dry-weather, flow
and composition at Sampling Station 8, which is considered repre-
sentative of other sampling stations. The major peak occurs approxi-
mately in the middle of the afternoon and a smaller peak occurs sub-
sequently in the middle of the evening. Minimum flow occurs during
early morning hours. The average daily flow at this sampling sta-
tion was approximately 45 mgd; the peak flow was about 140 percent
of average and minimum flow about 50 percent of average.
A similar diurnal variation of dry-weather sewage flow and quality
is shown in Figure 17. The peak flow from this large densely popu-
lated commercial structure occurs at 2:00 p.m. , with the minimum
flow (no flow) occurring at approximately 3:00 a. m. Figure 17 shows
that the greatest volume of flow from this building occurs, as expec-
ted, during normal working hours.
The principal industrial wastes generated in Sacramento from the
standpoint of wastewater volume and strength are from food process-
ing operations. A City ordinance requires preliminary screening
prior to discharge into trunk sewers, but these process wastes com-
prise a major portion of the load at the Main Treatment Plant. The
food process wastes are basically seasonal and occur primarily dur-
ing late summer and autumn. Figure 18 shows the location of the
major industrial wastewater discharges in the Study Area.
Complete dry-weather results characterizing municipal sewage are
presented in Appendix A.
SEPARATED STORM WATER RUNOFF
Water quality characteristics of the storm -water runoff collected from
a separated storm sewer system are presented in Table 3. Reliable
data on corresponding flows could not be ascertained due to difficulties
encountered in measuring the depths at the selected location (Stations
17, 17A, 17B, and 17C).
The magnitudes of the various "wastewater constituents were found to
be variable with respect to both date and time, but certain trends
were indicated.
The concentrations diminished as the wet season progressed and be-
came of more equal value during the course of a single rainfall event.
Also the somewhat higher concentrations of BOD and COD observed
during the last sampling episode in April were no doubt a consequence
of the relatively dry preceding month (see Figure 15).
51
-------
10 12 14
TIME OF DAY, hr
16 18 20 22 24
Figure 16. DIURNAL MUNICIPAL SEWAGE
CHARACTERISTICS AT STATION 8
52
-------
6 8 10 12 14 16 18 20 22 24
Figure 17. DIURNAL CHARACTERISTICS OF SEWAGE FROM
STATE WATER RESOURCES BUILDING
53
-------
Ln
Ptok Month
Avt. Daily
JMi
COMPANY
BERCUT- RICHARDS PACKINB CO.
BORDEH CO.
CALIFORNIA PACKINC COUP. Nl II
DEL MONTE CORP
FOREMOST DAIRIES INC.
LliBY, M'NEIL*. ft LIBBY
NATIONAL ICE CO,
SACRAMENTO BEE
SACRAMENTO COUNTY HOSPITAL
SOUTHERN PACIFIC SHOPS
SUTTER HOSPITAL
Figure 18. LOCATION OF MAJOR INDUSTRIAL WASTEWATER DISCHARGES
-------
Table 3
SEPARATED STORM WATER RUNOFF QUALITY CHARACTERISTICS - STATION 17
Characteristic
Total Suspended
Solids mg /t
Volatile Suspended
Solids, mg/t
Settleable Solids,
mg/f
BOD, mg/t
COD, mg/t
PH
Fecal Coliforms,
org/f
Sampling
Sequence*
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Date
10 Dec 68
54
208
22
54
208
18
52
193
22
52
118
67
110
176
36
6.6
6.6
7.2
e
2. 9 x 10-
7.5 x 10^
1.0 x 10
13 Dec 68
48
211
3
30
211
3
48
187
0
92
117
105
66
46
21
6.8
7.6
7.0
A
2.0 x 10°
2.0 x 10?
4.0 x 10
18 Jan 69
171
43
134
39
23
37
96
31
115
260
194
65
40
38
44
7.2
6.9
7.0
4
5.5 x 10,:
1.3 x 10;
2.4 x 10
5 Feb 69
26
38
35
10
19
17
25
18
19
52
46
86
45
66
28
7.3
7.3
7.5
A
8.0 x 10.
8.0 x 10*
8.0 x 10
23 Feb 69
27
51
46
21
3
22
25
35
38
24
39
39
44
27
45
7.2
7.3
7.6
4
6.6 x 10;
4.0 x lOj.
4.0 x 10
5 Apr 69
25
19
45
25
19
35
14
15
43
283
274
131
77
136
36
6.8
6.9
7.3
6
6.0 x IQ,
2.0 x 10°
4.0 x 10
1 denotes as nearly as practical to start of storm, 2 denotes three hours thereafter, and 3 denotes
12 to 18 hours after the commencement of sampling.
-------
COMBINED SEWAGE
Results of the wet-weather measurement, sampling, and analysis at
Station 8, which is typical of the overall combined sewage from the
Study Area, are presented in Table 4. It is evident that the concen-
trations of wastewater constituents are highly variable and change
quite rapidly as a result of different admixtures of storm water run-
off and sanitary sewage, whose compositions and quantities are ex-
tremely time dependent.
Complete data on the wet-weather monitoring of the combined sewage
system are given in Appendix B.
RECEIVING WATER CHARACTERISTICS
The eventual recipient of all wastewaters from the Study Area is the
Sacramento River, which flows past Sacramento to the San Francisco
Bay system and thence to the Pacific Ocean through the Sacramento-
San Joaquin Delta. The drainage basin upstream of the City of
Sacramento has an area of approximately 24, 000 square miles and
contributes about 65 percent of the flows to the Delta (Ref. 5)0 Major
tributaries are the Feather, Yuba, and American Rivers. The
American River bounds the Study Area on the north before joining the
Sacramento River, which bounds the Area's western extremity.
Many factors affect the flow and quality of the Sacramento River at
Sacramento, including storm water runoff, reservoir water releases
and storage, water diversions for use and exportation, power genera-
tion, and lunar tides. Even though the stream discharges are becom-
ing more extensively regulated by reservoir systems, the flows past
Sacramento are still expected to have great variation in the future,
ranging from perhaps 5, 000 cfs in the spring to in the order of 50, 000
cfs during the winter rainy season.
Water quality objectives have been adopted to protect and preserve
the many beneficial uses of the water of the Sacramento-San Joaquin
Delta, which includes at its northern extremity the Sacramento River
at the City of Sacramento. These beneficial water uses include do-
mestic and municipal, agricultural, and industrial supply; propaga-
tion, sustenance, and harvest of fish, aquatic life, and wildlife; re-
creation; aesthetic enjoyment; and navigation. In addition, the dis-
charge of wastewaters into these receiving waters for waste assimi-
lation, transport, and diminution was considered as a beneficial use
in the formulation of Delta water quality objectives.
Many factors influence or describe receiving water quality, such as
color; odor, floating grease and oils, benthic deposits, bacteria,
trace elements, temperature, pH, radioactivity, turbidity, dissolved
oxygen, nitrogen forms, biocides, total dissolved solids, chlorides,
56
-------
Table 4
COMBINED SEWAGE CHARACTERISTICS - STATION 8
Characteristic
Flow, cfs
Total Suspended
Solids, mg/t
Volatile Suspended
Solids, mg/f
Settleable Solids,
mgA
BOD, mg/t
COD, mg/t
PH
Fecal Coliforms,
org/f
Sampling
Sequence*
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
1
2
3
Date
10 Dec 68
218
188
52
227
47
230
164
26
60
28
0
119
74
197
171
387
234
291
6.9
7. 1
7. 3
A
2.4 x 10?
2. 6 x 10_
6.6 x 10'
13 Dec 68
117
291
62
216
53
30
173
53
30
159
53
28
193
160
328
380
146
431
7.0
6.9
7.2
7
3.0 x 10_
8.6 x 10'
1.2 x 10'
18 Jan 69
_
233
281
502
186
66
311
186
26
488
111
44
241
258
175
513
257
59
7. 1
6.8
7.0
6
5.9 x 10?
1.6 x 10?
8.9 x 10
5 Feb 69
237
223
72
140
110
98
56
82
98
127
106
70
808
132
186
160
176
285
7.2
6.9
7.2
6
2.0 x 10?
1.6 x 10?
7.0 x 10
23 Feb 69
242
150
74
56
151
208
51
112
162
34
142
202
75
73
69
195
191
318
7.5
7.5
7. 1
6
1.2 x 10°
6. 6 x 10?
7.0 x 10
5 Apr 69
88
61
40
242
91
241
242
91
221
233
52
210
306
70
-
191
123
354
7.0
6.6
6.5
6
2.0 x 10?
4. 5 x 10°
1.2 x 10
Ui
1 denotes as nearly as practical to start of storm, 2 denotes three hours thereafter, and 3 denotes 12
to 18 hours after the commencement of sampling.
-------
and toxic materials. Of the wastewater quality characteristics that
constitute or affect these factors, total suspended solids, BOD, and
fecal coliforms were chosen as being adequate for describing and
evaluating a system for the control of storm water runoff and com-
bined sewage overflows, at least within the context and scope of this
program.
The concentrations of these constituents indigenous to the Sacramento
River at Sacramento are dependent on, among other things, stream
flow. Figure 19 presents suspended sediment (solids) concentrations
reported (Ref. 6) for the Sacramento River at Sacramento for the
three water years extending from October 1963 to September 1966,
from which a correlation between suspended solids and stream dis-
charge has been drawn. Suspended solids concentrations reported
for the 1968-69 water year, which were not available for use during
the normal conduct of this program, provide generally lower suspend-
ed sediment loads at flows in excess of 25, 000 cfs than are represent-
ed by Figure 19, and may be indicative of the ever-increasing up-
stream flow regulation of the Rivers. Calculations indicate however
that the use of these more recent data would have negligible effects on
the findings of this study.
BOD concentrations representative of background levels were not
available over most of the range of river flows experienced, but the
limited data that were obtainable indicated values ranging from 1 to
7 mg/1 of BOD for flows between 7, 000 and 10, 000 cfs, with most
values being 1 to 2 mg/1. In an investigation (Ref. 7) by Hydroscience,
Inc0 for the County Department of Public Works on the pollution assi-
milative capacity of the lower Sacramento River, it was stated that
the background values of BOD are likely to increase to 2. 0 mg/1,,
Historical fecal coliform densities were not available for the
Sacramento River, but samples taken from the I-Street Bridge dur-
ing the conduct of this program indicated upon analysis an inverse re-
lation between fecal coliform densities and River flows ranging from
10, 000 to 75, 000 cfs as shown in Figure 20.
58
-------
103
Q.
a
»
O
P
oc
8
102
I I I I/ I
104
105
FLOW.cfs
Figure 19. RELATIONSHIP BETWEEN RIVER FLOW AND
SUSPENDED SOLIDS CONCENTRATION AT SACRAMENTO
59
-------
10
FLOW, K^cfs
Figure 20. RELATIONSHIP BETWEEN RIVER FLOW AND
FECAL COLIFORMS CONCENTRATION AT SACRAMENTO
60
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Section VI
SYSTEMS DESIGN
Development and design of implementable systems for the control of
storm water runoff and combined sewer overflows is complicated by
many diverse and sometimes contradictory factors. Upon determina-
tion of controlling physical conditions relevant to the problem, such
as wastewater quantities and qualities, receiving water quality and
assimilative capacity, and existing sewerage facilities and appurten-
ances, candidate or alternative systems must be conceived and de-
veloped in accordance •with specific design parameters and criteria.
In addition, the systems must be formulated within the constraints of
realistic phasing for the implementation of the systems over a future
time period, of applying reasonable financing methods to this schedule,
and of providing in some cases a suitable organization or agency to
effectively administer the construction, operation, and maintenance
of the systems,,
SYSTEMS DEVELOPMENT
Storm water runoff and combined sewer overflow pollution control sys-
tems were based on pre-selected concepts that demonstrated promise
of meeting expected requirements both because of proven performance
or recent technological advances and on concepts that represented a
wide range of solutions applicable not only to the Sacramento area but
throughout the nation.
CANDIDATE SYSTEMS CLASSIFICATION
Seven basic candidate systems were investigated in this study. These
systems were inter-related in varying degrees since it became neces-
sary to combine parts of several of the candidate systems to achieve a
complete sewer system consisting of wastewater collection, convey-
ance, treatment, and disposal.
The seven basic candidate systems or concepts are identified by name
as Complete Separation, ASCE Force Main, Surface Storage, Under-
ground Storage, Stabilization Pond, Dissolved Air Flotation, and Mech-
anical Screening.
Complete Separation considered total separation of sanitary and storm
flows. This entailed the installation of a new gravity conveyance system
for either sanitary or storm flows with the existing system then utilized
for the other.
61
-------
ASCE Force Main also necessitated total separation of sanitary and
storm flows. The basic concept called for the sanitary flow to be
managed through force mains located within the existing sewers, which
would continue to convey the then separated storm flows. This system
was divided further into two parts in order to explore an alternative
which appeared well suited for application in Sacramento. Total Force
Main was in full accord with the ASCE concept wherein each home was
served by an individual grinder-pump unit. The other system, Hybrid
Gravity-Force Main, considered the use of larger zonal grinder-pump
stations with the sanitary sewage delivered to the station via conven-
tional gravity lines.
Surface Storage and Underground Storage provided means for retaining
peak flows and thereby modulating the burden on pumping and treatment
facilities. The latter system envisioned near-surface storage.
Stabilization Pond also entailed storage, but was considered primarily
as a treatment process in itself rather than as a reservoir for reten-
tion of storm water runoff or combined sewage flows prior to treatment.
Dissolved Air Flotation and Mechanical Screening were two other treat-
ment processes evaluated.
A complete wastewater system can be comprised of many possible com-
binations of candidate systems and other components. The system de-
sign is further complicated due to spatial and temporal constraints im-
posed by a particular study area.
To assist in the systems development, the work was arranged into four
main groupings within which similar characteristics existed. These
four major subsystems were Collection and Conveyance, Storage, Treat-
ment, and Disposal. Each of the candidate systems under investigation
fell under one of the first three classifications above. While the actual
employment of a storage subsystem or a treatment subsystem was con-
sidered as optional, the development of any complete wastewater system
would require consideration of all four major subsystems.
PLANNING HORIZON
All systems investigated in this program were predicated on meeting pro-
jected requirements for 20 years after the start of construction. By es-
tablishing 1972 as the earliest practical year that a selected system
could realistically be started, the 20-year life would extend the planning
horizon to 1992. Then, when system capacity was theoretically reached,
it was assumed that additional capacity could be provided either by par-
allel systems or, more likely, by new methods developed through tech-
nological advances that had occurred during the intervening years.
As a practical matter it was recognized that any selected improvement
program of the magnitude envisioned in this study would be construction
phased over several years. The intent here has been to provide a
62
-------
reasonable basis for defining and costing the alternative systems on an
equal basis.
DESIGN CRITERIA
Design criteria were established on the basis of present practice and
projections of current data to the year 1992. Present data were ac-
quired both through available sources and the conduct of field measure-
ment programs in the Study Area.
WASTEWATER CHARACTERISTICS
Only sanitary sewage flows that would occur in a completely separated
sanitary and storm sewer system were considered in this program.
Whereas present dry-weather sewage flow rates are quite seasonal due
to the collection of extensive lawn irrigation return water and cooling
system discharges in the existing combined sewers, these wastewaters
would not be expected to enter a sewer used exclusively for sanitary
sewage. During wet-weather episodes these extraneous wastewaters
would not be prevalent and the respective quantities of combined sewage
would consist solely of sanitary sewage and storm water runoff.
Sanitary Sewage
Sanitary sewage flows for the Study Area were derived using projected
residential and employee populations, anticipated population distribu-
tion, and per capita wastewater discharge factors. The only exceptions
were several major industrial discharges and the exogenous sanitary
sewage from County Sanitation District No. 2, which is presently fixed
in magnitude by contract and expected to remain so.
The residential population for the Study Area and the North Sacramento-
Hagginwood area was projected to the year 1992 utilizing basic data fur-
nished by the Sacramento City Planning Department. The County Plan-
ning Department and the Sacramento Chamber of Commerce supplied
basic data for the projected employee population within the Study Area
and the North Sacramento-Hagginwood area, excluding State employees
and the student population at Sacramento State College. The latter two
were projected populations from data furnished by the State and the
College, respectively.
Projected 1992 populations for the Study Area and North Sacramento-
Hagginwood area were 201, 500 residents and 176, 200 employees, in-
cluding State personnel and student population at Sacramento State
College, providing a total population of 377,700 for both the Study Area
and the North Sacramento-Hagginwood area.
The projected residential population was distributed over the Study Area
in relation to the future anticipated zoning. This distribution was accorri'
plished by assigning a 1992 residential population to each 1968 census
63
-------
tract and its respective blocks based on an area ratio for each tract.
All future anticipated nonresidential areas were excluded in the dis-
tribution.
The projected employee population was distributed over the Study Area
in accordance with future anticipated commercial and industrial zoning.
Here again, the census tracts and the respective blocks were utilized
for distribution of the 1992 employee population with a greater per-
centage of employee population assigned to the larger blocks in each
tract. State employees were assigned on the basis of individual build-
ing floor area as proposed in the California State Capital Plan. The
proposed building locations have been tentatively fixed so that the in-
dividual block or blocks in each tract were known.
The average per capita sewage flow established for the Study Area (was
85 gpd for residents and 40 gpd for employees. The residential waste
discharge factor of 85 gpd/cap was based on the ultimate average de-
sign flow established in a study (Ref. 8) performed for the City of
Sacramento by Dewante and Stowell, Consulting Engineers, for a resi-
dential and commercial area, North Sacramento-Hagginwood. This
average design flow less the projected employee flow for 1992 provided
the appropriate residential wastewater factor.
The employee waste discharge factor of 40 gpd/cap was established on
the basis of extensive studies associated with the Bay Delta Study (Ref.
9) that indicated 35 gpd/cap as being representative of the general area;
an additional 5 gpd/cap was added for restaurants and other comple-
mentary commercial activities in the Sacramento metropolitan area
that are indiscernable in the large area from which the 35 gpd/cap
derives.
During the 24-hour dry-weather flow monitoring of the State Water Re-
sources Building that contained an employee population of approximate-
ly 3, 500, it was found that the peak flow was 00 323 mgda This provides
a peak waste discharge factor of 92. 5 gpd/cap. Applying the appropri-
ate peak factor, which will be described later in this section, to the
peak flow produced an average employee wastewater discharge factor
of 38. 5 gpd/cap, which compares very favorably with the 40 gpd/cap
used in this study.
The total dry-weather sanitary flow tributary to Sump No. 2 is and will
be generated in the Study Area, North Sacramento-Hagginwood, and
County Sanitation District No, 20
The sewage flow from Sanitation District No. 2 is fixed at 12 mgd by
contract and is not likely to change unless a new agreement is reached
between the City and the District.
Sanitary sewage flow from North Sacramento-Hagginwood was based
on the 1992 projected residential and employee populations and their
respective wastewater discharge factors, in addition to an anticipated
64
-------
peak industrial waste flow of 16 mgd.
The chemical and biological characteristics that were considered of
major importance in regard to the conduct of this study were the total
suspended solids, biochemical oxygen demand (BOD) and fecal coli-
form concentrations. Other important wastewater constituents, such
as oil and grease, floatable materials and debris, and settleable so-
lids, were not considered because of insufficient data on their concen-
tration in the receiving waters and in the storm water runoff. How-
ever, the control of the selected wastewater quality parameters by
the treatment processes employed, i. e. , dissolved air flotation, mech-
anical screening, and retention basins, will certainly effect major re-
movals of these pollutants.
Design sanitary sewage characteristics are shown in Figure 21 which
depicts the anticipated hourly variations in flow rate and total suspended
solids, BOD, and fecal coliform concentrations. These values were
based on the temporal form of the results reported (Ref. 10) by the City
and County of San Francisco for a similar drainage area in that City.
Flow rate results were adjusted to better represent the inflow conditions
expected at Sump No. 2, which is the common conveyance terminus of
the Study Area, and concentration magnitudes were adjusted in propor-
tion to the reported 24-hour averages for the two areas. Subsequent
field sampling and analysis in the Study Area established that in general
the design peak concentrations of BOD and total suspended solids were
about 35 percent lower than the observed and the design minimum con-
centrations were about 45 percent lower. Design peak fecal coliform
concentrations were 130 percent higher, while the design minimum was
200 percent higher. A single diurnal peak concentration of both BOD
and suspended solids was observed to occur at around 3:00 p0 m0 , which
upon adjustment to correspond to the arrival time at Sump 2, would
place it between the two peaks assumed in the design. The observed
fecal coliform concentration maximum, however, occurred around mid-
night instead of noon, as was assumed in the design (cf. Figure 16).
Storm Runoff
Design flow characteristics of storm water runoff from the Study Area
were based either on the application of the unit hydrograph developed
for the Study Area to eighteen continuous years of hourly rainfall re-
cords or the use of a particular modification of the rational method
using rainfall intensity-duration-frequency relations established in a
recent hydrologic investigation (Ref. 11) for Sacramento County by
Nolte Consulting Civil Engineers, Inc.
The rational method was used to determine peak storm water runoff
flows in each of the individual pipes comprising the collection and con-
veyance system. Maximum runoff was computed by the equation
Q = CAI, where Q is flow in cfs, C is runoff coefficient, A is con-
tributing area in acres, and I is rainfall intensity in inches/hour for
65
-------
300 ^
O
<
CC
UJ
O
O
O
9
_i
s
Q
LU
Q
UJ
a
V)
Q
<
a
§
2om
100t
O FLOW
BOD
A SUSPENDED SOLIDS
O FECAL COLIFORMS
1 I I l l i
0 02 04 06 08 10 12 14 16 18 20 22 2'
TIMEOFDAY.hr
Figure 21. DESIGN SANITARY SEWAGE CHARACTERISTICS
66
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a time duration equal to the time of concentration. Several storm re-
currence intervals were considered in this study. For economic rea-
sons, the greatest recurrence interval chosen for this study was ten
years. However to obtain perhaps a more realistic perspective for
the conveyance and treatment design effort, the 5- and 2-year storm
recurrence intervals were considered also.
The runoff coefficient expresses the fraction of rainfall that appears as
runoff after equilibrium conditions in the drainage area have been
reached and is dependent upon the nature of the drainage surface.
They were assigned to the individual tributary areas of the Study
Area on the basis of proposed future zoning established by the
Sacramento City Planning Department. Table 5 presents the runoff
coefficients used in this study, based on the general character of the
tributary area.
Table 5
DESIGN RUNOFF COEFFICIENTS
Description of Area Runoff Coefficient
High-density commercial 0. 80
High-density industrial 00 75
Medium-density commercial and industrial 0. 60
High-density apartments 0. 70
Medium-density apartments 00 60
Low-density apartments 0. 50
Single-family residential 0. 40
Schools 0. 30
Parks and cemeteries 0. 20
For the purposes of storage, treatment, and disposal design and analy-
sis, storm water runoff characteristics were established on a real-
time hourly basis from a continuous 18-year record of hourly rainfall
extending from June 1950 through May 1968, and a storm water runoff
quality model developed in this program. A hydrograph, developed
using the observed runoff record from three more or less isolated
storms, was applied to hourly precipitation data to obtain expected
67
-------
flow distributions. Hydrograph ordinates were least-square values
of storm runoff, determined from pumping records at Sump No. 2,
from a 1-in. , 1-hour rainfall in the Combined Area for the hour of
rainfall and the four succeeding hours. The computed ordinates
were increased by a factor to reflect the higher average Combined
Area runoff coefficient of 0. 534 expected to pertain in the year 1992.
The present average runoff coefficient was found to be 0. 362.
A unit hydrograph for all storm water runoff originating in the Sepa-
rated Area and converging to a common central location was pre-
pared by modifying the unit hydrograph developed for the Combined
Area. Both areas have similar characteristics and provide approxi-
mately the same maximum travel times for flow based on a 2-year
storm design of about 170 minutes, so that the ordinates of the Com-
bined Area unit hydrograph could be adjusted simply by proportion-
ing with the ratios of the respective areas and average runoff coef-
ficients. The area of the Separated Area draining to the common
point would be 3, 632 acres and the average runoff coefficient for this
area was calculated to be 0. 438.
For collection of all storm water runoff produced in the total Study
Area at Sump No. 2, a unit hydrograph was prepared that represented
inflow to Sump No0 2 from the combination of the Combined Area unit
hydrograph and the Separated Area unit hydrograph modified to re-
flect the time of transport from the common collection point to Sump
No. 2. On the basis that the time of concentration would increase by
60 minutes to 230 minutes, the base of the Separated Area unit hydro-
graph was expanded by 35 percent and the ordinate was proportionate-
ly diminished to provide the same total amount of runoff from an equal
amount of rainfall. Table 6 provides the ordinates of the unit hydro-
graphs.
Table 6
DESIGN UNIT HYDROGRAPHS
Average Runoff, cfs
Hours after Rainfall Combined Area Separated Area Total Area
0.5 187 79 230
1.5 1178 499 1337
2-5 1102 467 1471
3-5 825 350 1167
4-5 507 215 785
5. 5 0 0 205
6.5 0 0 114
68
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The content of total suspended solids, BOD, and fecal coliform bac-
teria in storm runoff was determined on the basis of a model which
depicts a constant rate of pollutant deposition on the land surface.
There the pollutant decays or is removed at a constant percentage
rate, i. e. , as a first-order reaction. During dry weather the accu-
mulation of pollutant on the land will therefore approach an asympto-
tic level. In rainy weather, however, the pollutant washes off at a
rate proportional both to the amount accumulated and to the runoff
flow. Heaviest concentrations occur near the beginning of storms
when the land accumulation is greatest. Symbolically, the mass
balance of pollutant on the land surface is AL = P -k L - k LQ,
1 £<
where L is accumulation of pollutant over the Combined Area, AL
is hourly increase (or decrease) in pollutant accumulation, P is
production rate of pollutant, k is decay constant, k is wash-off
constant, and Q is storm water runoff flow. The mass flow of pol-
lutant in the runoff is k~LQ and its concentration, K?L. The model
involves three parameters, P, k., and k_, whose values were
selected in accordance with storm water runoff data taken in
Sacramento and elsewhere (Refs. 3, 10, 12).
used for each of the three critical pollutants.
Table 7 gives the values
Table 7
DESIGN CONSTANTS FOR DETERMINATION OF
STORM WATER RUNOFF QUALITY
Parameter
Production Rate (P),mg/hr; org/hr
Decay Constant (k,), 1/hr
Wash-off Constant (k2), l/(cfs)(hr)
BOD
3x10
6x10
8
Total
Suspended
Solids
6x10
6x10
8
-3
-4 -4
7x10 7x10
Fecal
Coliforms
6x10
4x10
7x10
11
-2
-4
Combined Sewage
Projected combined sewage characteristics were determined by ad-
mixing the sanitary sewage and storm water runoff as ascertained
by the methods described above. Seasonal industrial wastewater
flows from the food processing industry were excluded from the com-
bined sewage because these flows would not be expected to occur si-
multaneously with the large storm flows that occur only in the winter
months in the Sacramento area.
69
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CONVEYANCE CONSIDERATIONS
For the design of the conveyance systems it was assumed that only a
minor infiltration would occur with very little effect on pipe capacity
design. Investigation showed that the groundwater level is well be-
low most of the existing sewer except in very close proximity of the
Sacramento and American Rivers where high groundwater can be en-
countered when River flows are high. With the use of newly available
pipe joints, proper inspection, and maintenance of high construction
standards, it was assumed that infiltration would be negligible for
all new designs.
Standard pipe diameters were used throughout the design, with mini-
mum diameters of eight inches for gravity systems and 1. 5 inches
for force main systems. Minimum acceptable depth of cover over
gravity-flow pipes was three feet.
Hydraulic Criteria
For the gravity systems, frictional head loss was determined from
Mannings formula using a roughness coefficient, n, of 0. 013, which
is the design criterion used by the City.
Sanitary gravity sewers were designed on the basis that depth of flow
would not exceed three-fourths of the pipe diameter and that minimum
slopes were those giving 2. 0 fps velocity at full-flow conditions. No
separated sanitary sewer pipes were permitted to be smaller than any
upstream pipe, and the soffits of the pipes entering and leaving the
manholes or junctions were set at the same elevation.
For the gravity systems for the collection and conveyance of storm wa-
ter runoff and combined sewage, the designs were based on pipes flow-
ing full and at a minimum velocity of 2. 0 fps. At junctions, the invert
of the downstream pipe was never higher than the inverts of any in-
coming pipe. A portion of the downstream pipe was permitted to flow
under pressure to accommodate this condition.
In the sanitary sewage force main design, frictional head loss -was com-
puted using the Hazen-Williams formula and a friction coefficient, C,
equal to 135 for 6-in. and smaller diameter pipes and 115 for larger
pipes. Pipe size was selected to provide the largest standard diameter
that would provide for a minimum scouring velocity at the design flow.
These minimum velocities were determined in an independent study
(Ref. 13) and are presented in Table 8.
Because of insufficient data to determine the exact capacity of each and
every pipe in the existing collection and conveyance systems, it was
assumed that all existing pipes had slopes corresponding to their dia-
meters,, These slopes were ascertained from a rough correlation of
slope versus diameter for the few pipes in the system whose slopes
were known. The relation is shown in Figure 22. The slope for the
70
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0.0040
0.0030
0.0020
3
0.0010
0.0000
1 I
A AVERAGE COMBINED SEWER
O AVERAGE SEPARATED SEWER
ESTIMATED RELATIONSHIP
0 10 20 30 40 50 60 70 80 90 100 110 120 130
DIAMETER, in.
Figure 22. RELATIONSHIP BETWEEN EXISTING
PIPE DIAMETER AND SLOPE
71
-------
entire length of 108-in. pipe was known and constant at 0. 065 per'
cent, and thus was employed instead of the value indicated by the
correlation.
Table 8
MINIMUM FORCE MAIN VELOCITIES
Diameter, Velocity, Diameter, Velocity,
in. fps in. fps.
1.5 0.61 24 2.45
2 0.71 27 2.59
2.5 0.78 30 2.74
3 0. 86 33 2. 87
4 1.00 36 3.00
6 1.22 39 3.13
8 1. 42 42 3. 24
10 1.58 45 3. 35
12 1.72 48 3.46
14 1.86 51 3.56
16 2.00 54 3.67
18 2. 12 57 3. 78
21 2.29 60 3_ 89
Materials Selection
In order to compare alternative conveyance systems on as equal a
basis as possible, the material selected for new systems was the
same as those materials currently in use in Sacramento. No attempt
was made to evaluate or compare these materials with others. There-
fore, for example, since Amerplate is not presently in use in
Sacramento, it was not specified or costed in new sanitary lines. Like-
wise, since corrugated metal pipe is not now in use, it was not speci-
field for new storm sewer applications.
The materials selected for separated storm water runoff and combined
sewage systems were nonreinforced concrete pipe in the 8- and 10-in.
diameter sizes and reinforced concrete pipe in 12-in. and larger sizes,
The pipe joints were tongue and groove except when pipe was laid in
groundwater, in which case the joints were rubber gasket.
The sanitary sewage collection system material selected was vitrified
clay pipe in standard sizes up to and including 42-in. diameter pipe
with plasticized polyvinyl chloride or polyurethane elastomer joints.
72
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The larger sizes, 48-in. diameter and larger, were constructed of
reinforced concrete with tongue and groove joints except in ground wa-
ter where joints were rubber gasket.
The reinforced concrete pipe material strength was expressed in D-
load factors which vary with type of installation, depth of trench, size,
and live loads imposed. The D-load is the load on the pipe per lineal
foot per foot of internal diameter. The computations were based on
an ideal trench section wherein the trench width at the top of pipe would
not exceed the outside diameter of the pipe plus 16 inches of working
space.
The material strength of nonreinforced concrete pipe and vitrified clay
pipe is based on a 3-edge bearing support. Both types of pipe were
utilized at their "extra strength" classification for ideal trench condi-
tions within their limits of depth. At shallower depths a concrete cradle
was provided to increase the load factor as trench width and applied
loads increased.
The material selected for force mains was polyvinyl chloride for the
small sizes of 1. 5- through 6-in. diameters., Their strength designa-
tion was Class 125. The pipe joints were "Ring-Tite" with 0-ring
seals. Larger force mains through 36-in. diameter were epoxy-lined
asbestos cement pipe, Class 1000 Force mains greater than 42-in.
diameter were reinforced concrete pipe with rubber gasket joints.
Grinder-Pump Requirements
For the ASCE Force Main systems, the grinder-pump requirements
were estimated on the basis of population density. Specifically, the
number and size of grinder-pump units needed to service each major
category of land use--single-family residential, multiple-family resi-
dential, low-density commercial, and high-density commercial--in the
Study Area were established. Representative populations and areas
used in these determinations were selected from the sewer system in-
put design data. The derived relationship used in the design and costing
of the grinder-pump components is presented in Figure 23.
STORAGE
Volumetric storage requirements for the containment of storm water
runoff and wet-weather combined sewer flows were selected to match
the conveyance system with regard to storm recurrence interval. Thus,
a reservoir comprising a portion of a system provided with a conveyance
subsystem designed for a 5-year storm would overflow or exceed its
capacity with the same recurrence expectancy, that is once every five
years.
Storage reservoir capacities were determined utilizing several con-
stant withdrawal rates and hourly inflow characteristics computed
73
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-J
\u
a.
v>
cc
111
O
z
DC
O
u.
O
DC
UJ
m
Z
D
11
10
POPULATION DENSITY*
Oto20
20 to 200
200 to 400
400 or MORE
RESIDENTIAL AND EMPLOYEE
GRINDERS PER ACRE
0.3 X DENSITY
6.4 - 0.02 X DENSITY
3.6 - 0.006 X DENSITY
1.2
h
i I i I i
A:
I i I i I ill I i I i
200
400
600 800 1000 1200
POPULATION PER ACRE
1400
1600
1800
Figure 23. RELATIONSHIP BETWEEN NUMBER OF GRINDER-PUMP UNITS
AND POPULATION DENSITY
-------
from 18 years of hourly precipitation data and the unit hydrographs for
the Sacramento area.
When sizing storage facilities for combined sewage, all dry-weather flow
was bypassed directly to the existing municipal sewage treatment plant
for processing and disposal. If any storm drainage was contained in the
combined sewage, the entire flow was accepted by the pond, regardless
of the extent of unused capacity available at the sewage treatment plant.
TREATMENT
To match the approximate performance capability of the mechanical
screening process, the requirement for removal of suspended solids
was set at 30 percent for both mechanical screening and the dissolved
air flotation process. In addition, a second requirement for 60-per-
cent removal of suspended solids was specified for dissolved air flota-
tion only.
Dissolved Air Flotation
Pertinent design criteria established for the dissolved air flotation pro-
cess effecting 30- and 60-percent removals of total suspended solids
are presented in Table 9.
Table 9
DESIGN CRITERIA FOR DISSOLVED AIR FLOTATION
Design Value
Parameter 30% Removal 60% Removal
Unit Capacity, mgd 40 40
Suspended Solids Removal, % 30 60
BOD Removal, % 21 42
Surface Loading Rate, gpd/(sq ft) 13,000 3,000
Weir Loading Rate, gpd/ft 125,000 125,000
Recirculation Rate, % 20 20
Dissolved Air Tank Detention Time, sec 60 60
Air Injection Rate, cfm at 65 psig 30 90
75
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It was assumed that 30 percent of the total BOD contained in the storm
water runoff and the combined sewage was dissolved and not removed
by the dissolved air flotation treatment process. Also negligible fecal
coliform bacteria removals were anticipated using this process,
Two sources of information were employed in the application of dis-
solved air flotation to the Sacramento study. The Rhodes Corporation,
Oklahoma City, had performed testing on a pilot plant installation in
Fort Smith, Arkansas, that also provided solids removal upstream by
cyclone centrifugation, but only partial results were available. There-
fore, design criteria were based largely on the laboratory study (Ref.
10) conducted by Engineering-Science, Inc. , Arcadia, California pre-
paratory to the design and construction of a dissolved air flotation in-
stallation on a combined sewer bypass in San Francisco. Data from
this study were used to develop a relation between total suspended
solids removal and surface loading rate, which is shown in Figure 24.
BOD removal is also shown and was based on the assumption that 70
percent of the total BOD is in the suspended form and removed with
the suspended solids.
Mechanical Screening
The mechanical screening unit employed in this study has been under
development for several years by the manufacturer, SWECO, Inc.
A test program is presently underway at the Hyperion Sewage Treat-
ment Plant, Los Angeles, to determine the relationship between mesh
size, flow split between treated effluent and concentrate blowdown, and
pollutant reductions. These data are summarized in Table 10 which re-
flects both early data and also the latest available experience.
Based on the earlier results, the mechanical screening process was
assumed to effect 30-percent removals of suspended solids and 21-per-
cent reductions in BOD since it was assumed that 70 percent of the to-
tal BOD content was associated with the total suspended solids0 Negli-
gible reductions in fecal coliform density were expected through treat-
ment of the storm water runoff and combined sewage with mechanical
screening devices. At the design hydraulic loading or throughput rate
at 56 gpm/(sq ft), 20 percent of the influent flow was needed for con-
centrate blowdown.
Stabilization Pond
Stabilization ponds, and smaller storage reservoirs, were expected to
remove total suspended solids and the associated suspended BOD by
sedimentation, dissolved BOD by providing time for its reduction, and
fecal coliforms by permitting die-off. Total suspended solids removals
were assumed to vary linearly with pond volume from no reduction at
zero volume to a maximum of 70-percent removal at full capacity.
Since the insoluble fraction of BOD was taken as 70 percent, the maxi-
mum removal by sedimentation would be 49 percent. The remaining
76
-------
c
7
i 10*
3 *
uj 8
u
"• 7
W 6
5
SUSPENDED SOLIDS
(After Ref. 10)
10
20
30
40
50
60
70
80
90
100
CONSTITUENT REMOVAL, %
Figure 24. RELATIONSHIP BETWEEN SURFACE
LOADING RATE AND CONSTITUENT REMOVAL
FOR DISSOLVED AIR FLOTATION
77
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Table 10
MECHANICAL SCREENING TEST DATAC
00
Screen Characteristics
Loading Treated
Average Reductions, %
Mesh
signation
80MG
105TBC
165TBC
230TBC
Opening,
in.
0. 0070
0. 0065
0. 0042
0. 0029
Wire
Diameter,
in0
0. 0055
0. 0030
0. 0019
0. 0014
Open
Area,
%
31. 4
46. 9
47. 1
46. 0
JA.O.LC; , '-'
gpm/(sqft)
56
56
56
76
56
67
.Cj-Liiuejii.
Recovery ,
80
80
80
88
80
82
Suspended
Solids
25. 7
32. 0
36. 3
31.7
46. 2
36. 2
BOE
30. 0
19. 0
18. 3
12. 0
14. 0
22, 7
Determined on raw sanitary sewage at Hyperion Treatment Plant, Los Angeles, California
by SWECO, Inc0
Based on treated effluent flow
-------
BOD, both suspended and dissolved, would be reduced at a rate of 1. 0
percent each hour. A 4. 0-percent hourly die-off was applied to reduce
the stored fecal coliform densities.
Major reductions in fecal coliform content of the storm water runoff
and combined sewage to acceptable discharge levels were expected by
chlorination and retention to provide adequate contact time. At least
15-minute contact was provided between the wastewater and chlorine
prior to discharge to the receiving waters, except for the systems
where no storage pond was provided. In this case, only 10-minute con-
tact was provided for the peak flow condition.
DISPOSAL
Only the disposal of wastewaters produced from storm drainage, either
as separated storm water runoff or as combined sewage, was consider-
ed in this study,, When analyzing combined sewer systems, it was as-
sumed that capacity, which would be highly variable and time dependent,
in the conventional sewage treatment facilities was not available. An
exception was the acceptance on occasion of solids concentrate from
the mechanical screening treatment process by either the existing or
expanded sewage treatment plant.
The effects of wastewater discharges to the Sacramento River from the
existing or future municipal sewage treatment plants were outside the
scope of this program and were not included in the analysis. Obviously
in evaluating downstream water quality and the total effects thereon, all
discharges from the total watershed area must be considered. For this
study, the quantity and composition of all storm water runoff as com-
bined sewer overflows from the Combined Area portion of the Study
Area were determined and the effects on the receiving waters immediate-
ly upon assimilation of these wastewaters subsequent to various means
of containment and treatment were evaluated. The consequences of the
already separated storm water discharges from the Separated Area
were not included in the analysis; the pollutant loadings from these drain-
age areas were presumably already integrated into and contributary to
the background levels used for analysis since their discharge was up-
stream of the background datum location.
For design purposes, three water quality parameters were assumed to
adequately describe the performance of storm water runoff and com-
bined sewage overflow water pollution control systems — total suspended
solids, BOD, and fecal coliforms concentrations. Indigenous background
levels in the Sacramento River were assumed to be a function only of Ri-
ver flow, or in the case of BOD, a constant of 2. 0 mg/1. Because the
relation between River flow and BOD was unknown, this constant value
was selected as being representative and reasonably conservative. Re-
lations between River flow and suspended solids and fecal coliforms con-
centrations are shown, respectively, in Figures 19 and 20 presented
elsewhere in this report.
79
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SPACIAL AND TEMPORAL CONSTRAINTS
To fully describe any one complete wastewater system applied to a
given area, it became necessary to specify potential locations for
storage and treatment facilities. Although a detailed investigation of
potential sites was not undertaken, six locations were selected, from
which four were utilized in costing out the alternative systems.
While not explored in this program, a promising potential was avail-
able for multiple land usage in combining a reservoir with other types
of overhead facilities. This concept could be compared to the grow-
ing practice of utilizing air space over railroad and freeway rights-
of-way for the construction of buildings. Such a project might be in-
corporated into urban renewal and implemented through an existing
or new redevelopment agency.
The six sites are identified by name and location in Figure 25. It is
recognized that one or more of the sites selected for costing of the
various alternative systems may not be ideally suited for the planned
usage. The intent has been to develop and compare the effectiveness
of the candidate systems on as equal a basis as possible within the
framework of a complete sewer system,, The available options at any
given location were kept open to the maximum extent feasible.
American River Park holding pond would be located adjacent to the
Elvas Freeway and would provide a common collection point for the
presently separated storm sewer systems within the Study Area. It
is understood, however, that this land has been reserved by the City
for a sanitary landfill site.
Sump No. 2 holding pond, a below-surface reservoir, would be con-
structed to the north of the existing Sump No. 2. The area is present-
ly single-family residential, which would have to be cleared. The de-
velopment of a landscaped surface park over the reservoir is suggested.
Sacramento Port holding pond would be located on land that is undevel-
oped and presently devoted to agricultural purposes to the west of Sump
No, 2 across the Sacramento River. While located near Sump No, 2,
this location in adjacent Yolo County is handicapped because of the cost
of installing conduits under the River, which is a navigable deep-chan-
nel waterway.
South Sacramento holding pond would be situated on presently undevel-
oped land to the south of the City, about eight miles from Sump No. 2,
and is considered promising. This location is adjacent to the existing
Central County Sanitation District treatment facilities. While the pre-
sent capacity of the County plant is limited, it is understood that it will
eventually be enlarged to serve an area within which extensive growth
forecast. This southern area is relatively low in elevation and with-
a natural flood plain so that the construction of reservoirs may prove
80
i
in
-------
_
~~1 SACRAMENT
PORT
Figure 25, LOCATIONS OF PROPOSED STORAGE AND
TREATMENT FACILITIES
-------
difficult.
Old State Fairgrounds holding pond would be located on the former site
of the California State Fair which is unused and for sale. From an
availability standpoint, a portion of this land for a reservoir location
has appeal.
William Curtis Park holding pond would be situated on open land that
belongs to the Western Pacific Railroad. Availability of this land is
unknown however. An area between the railroad land and William
Curtis Park to the east is considered a good candidate for an under-
ground reservoir with enlarged park facilities, perhaps under the
auspices of urban renewal.
PROGRAMMED DESIGN
Extensive use was made of a digital computer in three different aspects
of the study. The first was design of the various sewer pipe networks--
separate sanitary sewers, separate storm sewers, combined sewers,
and a pressure sanitary system. Secondly, the storage requirements
necessary for containment of the various quantities of flow associated
with different, selected storm recurrence intervals were determined.
In the third application, various proposed treatment schemes were
simulated and the resulting effect on receiving water quality summari-
zed statistically,
SEWER DESIGN
The pipe network was laid out by hand to correspond basically with the
existing system. Each manhole was given an identification number.
One data card was prepared for each manhole and contained the follow-
ing individual information: its manhole index, index of the next manhole
downstream and of any manholes immediately upstream, the tributary
residential and employee populations, tributary acreage, average sur-
face runoff coefficient, ground surface elevation, diameter and length
of the existing pipe leaving the manhole, and its slope and invert ele-
vation if known,, Also given was the amount of any sewage flows pumped
to the manhole from outside its immediate tributary area.
Sanitary Sewers
With the data for the entire network in the computer, the design was
carried out one pipe at a time, working downstream. A search routine
operated in such a way that a pipe could be selected for design only
after all tributary pipes had already been designed. Tributary popula-
tions were multiplied by per capita flows to give average daily flows.
Both total population and average daily flow were accumulated down-
stream. Design flow for any pipe was obtained by multiplying the accu-
mulated average flow by a peak factor, which was a function of the total
82
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tributary population according to the relation,
Peak Factor = 37' 2 + ,
14. 3 + VP
where P is the tributary population in 1,000's. "Exogenous" flow
was also accumulated downstream and was added to the pipe design
flow after application of the peak factor to the average endogenous flow.
With the design flow computed, the smallest possible pipe was selected
and laid on the basis of hydraulic criteria presented previously. After
completing design of all pipes, the depths and invert elevations of pipes
were computed.
As a result of the computer design, total sanitary sewage design flow
for the year 1992 to Sump No. 2 was estimated to be 115 cfs.
Storm Sewers
The basic pipe network and manhole numbering used in the sanitary sew-
er design was also the starting point for the storm and combined sewers.
Design was carried out in the same order also, using a search proce-
dure which assured that no pipe would be considered until after all pipes
upstream had first been computed.
Flows were calculated by a particular modification of the rational me-
thos. A uniform inlet time of 15 minutes was assumed. The intensity-
-0 59
duration curves (Ref. 11) had the relation I = K t , where I is
rainfall intensity in in. /hr, tc is time of concentration in minutes and
K had the values of 4. 90, 7. 50, and 8. 96 for the several storm re-
currence intervals considered of 2, 5, and 10 years, respectively. The
time of concentration and the product of runoff coefficient and area were
both accumulated downstream, so that at the moment of designing the
pipe below a given manhole, these two figures were available for each
tributary sewer entering the manhole. The time of concentration at
the lower end of any pipe was obtained from that at the upper end by
adding a travel time equal to the length of run divided by velocity as
computed from the design flow, slope, and diameter using the Manning
formula.
It was assumed that the hydrograph at the lower end of any sewer had
the form shown in the sketch on the following page. The flow was
assumed to rise linearly from zero to a peak at the time of concentra-
tion. The peak flow was the cumulative tributary "CA" value (runoff
coefficient times area) multiplied by rainfall intensity corresponding to
the time of concentration, t . Thereafter the flow decreased in accord-
ance with the intensity-duration curve. When several such hydrographs
representing the branches arriving at a junction were added together,
the resultant hydrograph had a series of cusp-shaped peaks occurring at
the respective times of concentration for the branches. The tallest of
such peaks and the corresponding time of concentration were taken as
83
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the design values for the sewer leaving,,
Flow
Q = CAKt
-0.59
Time
Time of
Cone entr ation,
tc
With design flow determined, the pipe was laid at the minimum slope
consistent with the previously specified criteria. After completing
design of all pipes in the above manner, a second upstream-to-down-
stream scan was made through the system, and the upstream inverts
of all pipes were lowered (if necessary) so as to lie no higher than
the inverts of their tributaries. The downstream ends of adjusted
pipes were also lowered, if necessary, to maintain minimum-velocity
slope.
Storm water runoff design flows to each sump in the Study Area are
presented in Table 11.
Combined Sewers
Gravity systems for the collection of combined storm and sanitary sew-
age were designed using the same method and criteria as described a-
bove for the storm sewers. Sanitary flows, computed previously and
retained on magnetic tape, were merely added to the storm flows. The
pipe design, and hence times of concentration, wiire computed using
the combined flows.
Design flows in each of the four trunks at Sump No. 2 and the total for
the combined sewer system at the three storm recurrence intervals
are presented in Table 12.
Sewer Augmentation
*
A design was performed to determine the sewer construction necessary
to provide sufficient capacity in the existing system for all design flows,
which were taken as those previously computed for a new complete
84
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Table 11
STORM SEWER DESIGN FLOWS
Sump
No,
ioa
3ia
52a
99a
ioia
llia
Aa
Pb
sb
2AC
2BC
2CC
2DC
2
Area,
acres
514
815
155
535
347
414
102
445
308
439
3, 250
1,398
1,949
7, 038
Average Run-
off Coefficient
0. 409
0.471
0. 692
0. 449
0. 397
00 750
0. 462
0. 200
0. 303
0. 404
0. 455
0. 601
0. 652
0. 534
Peak Flow, cfs
2-yr Storm 5-yr Storm 10-yr Stori
98.2
151
66.4
110
57. 8
134
26, 8
8.0
72. 1
69. 3
350
221
323
890
152
231
104
171
88. 8
206
41.6
73.5
111
107
544
345
501
1, 380
182
277
125
205
106
247
50. 0
87. 8
134
128
655
423
601
1,670
3.
Existing separated areas
Proposed areas to be separated
c
Major trunks tributary to Sump No. 2
sanitary, storm, and combined sewer system. They were compared
with the capacity of the existing pipe at its assumed slope (cf. Figure
22) flowing full0 Where additional capacity was required a supplementary
pipe was laid at the same slope as the existing pipe, and its diameter was
85
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Table 12
COMBINED SEWER DESIGN FLOWS
Peak Flow, cfs
Sump 2-yr Storm 5-yr Storm 10-yr Storm
2A* 74.2 114 137
2B* 333 496 587
2C* 257 362 422
2D* 339 512 610
2 892 1,300 1,540
;'<
'Major trunks tributary to Sump No. 2
chosen as the smallest standard size that would carry the excess flow
without becoming pressurized.
Estimated flow capacities at sumps in the existing sewer systems are
presented in Table 13.
Sanitary Force Main System
The force main concept involved collecting sanitary sewage at neigh-
borhood or household stations for grinding and pumping into a network
of relatively small-diameter, shallow-laid force mains. The same
basic pipe layout was assumed as for the several gravity systems and
design flows at any point were identical to those used in the separate
gravity sanitary system. Negligible benefits would have derived in the
Study Area from a different network, although in other areas that are
less developed and that possess more irregular terrain, a force-main
layout not constrained by gravity-flow requirements could provide bene-
fits not evident in this study.
One half of the design flow was assigned to each of two parallel force
mains, which should be necessary to assure continued operation during
maintenance of the pipes at low-flow periods. Thus both parallel pipes
are fully utilized at peak-flow condition. Pipe size was selected as the
largest standard diameter, 1. 5 inches or greater, that would provide
a scouring velocity at the design flow (see Table 8).
After determination of pipe sizes, the head losses and pressure head
throughout the system were computed, working upstream from the lower
86
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end. A scanning procedure was selected that provided for head compu-
tations only on pipes lying immediately upstream from another pipe
whose head loss had already been established. Head at the upstream
end of a pipe was obtained by adding the head loss to the downstream
head and subtracting the difference in ground surface elevations.
Table 13
ESTIMATED FLOW CAPACITIES OF
EXISTING SEWER SYSTEMS
Sump Estimated Flow, cfs
10 97.5
31 73.9
52 58. 2
99 127
101 106
111 86.8
A 26. 2
2A* 58. 2
2B* 281
2C* 318
2D* 58. 2
2 716
*
Major trunks to Sump No. 2
WASTEWATER QUALITY CHARACTERISTICS
To estimate the effect that the alternative systems for the control of
storm water runoff and combined sewage overflows would have on the
receiving water quality, a computer simulation of the wastewater gen-
eration and treatment system was developed. The model provided
for calculation of storm water runoff flow and combined sewage flow
during the occurrence of storm runoff, and of concentrations of pollu-
tants in the sewage. Input data were hourly rainfall values over a con-
tinuous 18-year period of record for Sacramento, which were convert-
ed to flow and composition in accordance with criteria and techniques
discussed earlier in this section.
87
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Statistical information was extracted from each simulation and in-
cluded, for each of the three pollutants, the cumulative frequency
distribution of concentrations and the frequency at which particular
concentration levels were exceeded.
The predicted wastewater quality distributions of total suspended
solids, BOD, and fecal coliforms concentrations for storm water run-
off and combined sewage from the Combined Area (excluding storm
water runoff from the Separated Area) in the year 1992 are shown in
Figures 26 and 27. Characteristics of sanitary sewage, which were
estimated to vary diurnally only, are presented elsewhere (see Figure
21). For convenience, expected mean and maximum concentrations
of the three pollutants in untreated discharges are presented in Ta-
ble 14.
Table 14
PREDICTED UNTREATED WASTEWATER QUALITY
CHARACTERISTICS FOR COMBINED AREA - Year 1992
(7, 038 acres)
Pollutant
Total Suspended Solids, mg/1
Mean
Maximum
BOD, mg/1
Mean
Maximum
Fecal Coliforms, org/1
Mean
Maximum
Sanitary
Sewage
159
258
208
364
6. 8x10
2. 3x10
7
Wastewater
Storm Water
Runoff
250
693
125
348
6. 3x10^
1. 0x10^
Combined
Sewage
184
595
170
364
1x10
3x10
7
STORAGE CAPACITIES
To determine reservoir capacities that would be compatible with con-
veyance system capacities, which were dependent upon the storm re-
currence interval selected for design, a computer simulation was
developed. Hourly inflow to the pond was derived from the contin-
uous 10-year hourly rainfall record using the appropriate unit hydro-
graph for the drainage area under consideration. For pre-selected
constant withdrawal raies, the recurrence interval for the overflow
or spillage Irom any given reservoir volume was estimated Addi-
tional information provided by the simulation was the total duration of
-------
0.01
99.9
TO 1 25 10 20 30 40 50 60 70
PERCENTAGE LESS THAN GIVEN VALUE
Figure 26. PREDICTED STORM WATER RUNOFF QUALITY DISTRIBUTION,
COMBINED AREA, SUMP NO. 2 - YEAR 1992
160
140
— 120
100
MEAN VALUES
TOTAL SUSPENDED SOLIDS, mg/l 250
BOD, mg/S[ 125
FECAL COLIFORM, ora/^ 6.34 x 104
FECAL COLIFORMS
TOTAL SUSPENDED SOLIDS
?
o
n
99.99
-------
O
UJ
O
o
o
Q
Q
01
O
Z
LU
I
800
700
6OO
500
400
300
MEAN VALUES
Total Suspended Solids, mg/|"
BOD, mg/C
Fecal Coliforrm,
<
O 200
O
Z
Q
8 100
TOTAL SUSPENDED SOLIDS
400
— 350
300
250
200
— 150 Q
— 100
50
"001
10 20 30 40 50 60 70 80
PERCENTAGE LESS THAN GIVEN VALUE
90
95
98 99
99.9
99.99
Figure 27. PREDICTED COMBINED SEWAGE QUALITY DISTRIBUTION,
COMBINED AREA, SUMP NO. 2 - YEAR 1992
-------
overflow.
The calculated relations between storage reservoir volume and re-
servoir withdrawal rate for storm water runoff and combined sewage
flows from the Combined Area draining to Sump No. 2, for storm
water runoff from the Separated Area draining to American River
Park, and storm water runoff and combined sewage flows from the
Total Area draining to Sump No. 2 are shown in Figures 28 through
32, respectively. It was assumed that the hydrograph for the Total
Area drainage at Sump No. 2 would be applicable wherever the hold-
ing pond might be located downstream of this point since no addition-
al flow would be introduced.
TREATMENT PROCESS PERFORMANCE
Effluent concentration distributions of the three pollutants from
various sewage storage and treatment process combinations were
estimated through system simulation.
The effects of treating storm water runoff from the Combined Area
are shown in Figures 33, 34, and 35, which present distributions of
total suspended solids, BOD, and fecal coliforms concentrations,
respectively. The volumes noted refer to storage pond capacity and
the removal percentages to total suspended solids reductions in that
portion of the flow received by the treatment process. Storage pond
overflows were not subjected to treatment.
Predicted mean and maximum concentrations corresponding to the
distributions are given in Table 15. These results indicate that
large holding ponds would reduce markedly the average effluent pol-
lutant concentration without appreciable change (in this case zero)
in the maximum expected value. Processes that are capable of a
fixed percentage removal of from 30 to 60 percent on the other hand
would effect moderate reductions in average effluent pollutant con-
centrations and sizeable decreases in maximum predicted concen-
trations.
Distributions of the three pollutant concentrations in the effluent
from various storage and treatment combinations processing com-
bined sewage overflows from the Combined Area are shown in Fig-
ures 36, 37, and 38; and the corresponding expected mean and maxi-
mum concentrations are given in Table 16. Sanitary sewage flows
that occur during periods when storm runoff is nonexistant would not
contribute to this wastewater quality distribution and thus were ex-
cluded from the computation.
In contrast to the storm water runoff distributions, the singular in-
fluence of a large holding pond on the attenuation of mean pollutant
concentration in comparison to the combined effects of small or
moderate storage facilities and fixed removal treatment processes
91
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103
o
102
10
10-YEAR RECURRENCE
EXPECTANCY
5-YEAR RECURRENCE
EXPECTANCY
2-YEAR RECURRENCE
EXPECTANCY
10'
102
WITHDRAWAL RATE,
103
Figure 28. RELATIONSHIP BETWEEN RESERVOIR VOLUME
AND RESERVOIR WITHDRAWAL RATE FOR
STORM WATER RUNOFF, COMBINED AREA
92
-------
5
10-YEAR RECURRENCE
EXPECTANCY
5-YEAR RECURRENCE
EXPECTANCY
2-YEAR RECURRENCE
EXPECTANCY
10
102
WITHDRAWAL RATE, mgd
Figure 29. RELATIONSHIP BETWEEN RESERVOIR
VOLUME AND RESERVOIR WITHDRAWAL RATE FOR
COMBINED SEWAGE, COMBINED AREA
93
-------
103
10
5-YEAR RECURRENCE
EXPECTANCY
10-YEAR RECURRENCE
EXPECTANCY
2-YEAR RECURRENCE
EXPECTANCY
To3
10' 102
WITHDRAWAL RATE,
Figure 30. RELATIONSHIP BETWEEN RESERVOIR
VOLUME AND RESERVOIR WITHDRAWAL RATE FOR
STORM WATER RUNOFF, SEPARATED AREA
94
-------
104
103
D
5
102
10'
10-YEAR RECURRENCE
EXPECTANCY
5-YEAR RECURRENCE
EXPECTANCY
2-YEAR RECURRENCE
EXPECTANCY
I I
I
I
102
WITHDRAWAL RATE, mgd
103
Figure 31. RELATIONSHIP BETWEEN RESERVOIR VOLUME
AND RESERVOIR WITHDRAWAL RATE FOR
FOR STORM WATER RUNOFF, TOTAL AREA
95
-------
104
103
3E
D
-I
O
10
10-YEAR RECURRENCE
EXPECTANCY
5-YEAR RECURRENCE
EXPECTANCY
2-YEAR RECURRENCE
EXPECTANCY
I
I
I
I
I
I I I I I
101 102 10J
WITHDRAWAL RATE, mgd
Figure 32. RELATIONSHIP BETWEEN RESERVOIR VOLUME AND
RESERVOIR WITHDRAWAL RATE FOR COMBINED SEWAGE,
TOTAL AREA
96
-------
800
0.01
10 20 30 40 50 60 70 80
PERCENTAGE LESS THAN GIVEN VALUE
Figure 33. EFFECT OF VARIOUS TREATMENTS ON STORM WATER RUNOFF
TOTAL SUSPENDED SOLIDS CONTENT, COMBINED AREA - YEAR 1992
-------
400
-X)
oo
280 acre-ft, 30% REMOVAL
0 acre ft, 30% REMOVAL
0.01
20 30 40 50 60 70 80 90
PERCENTAGE LESS THAN GIVEN VALUE
95 98 99
99.9
99.99
Figure 34. EFFECT OF VARIOUS TREATMENTS ON STORM WATER RUNOFF
BOD CONTENT, COMBINED AREA - YEAR 1992
-------
200
vO
I
0.01
90
95
98 99
99.9
99.99
PERCENTAGE LESS THAN GIVEN VALUE
Figure 35. EFFECT OF VARIOUS TREATMENTS ON STORM WATER RUNOFF
FECAL COLIFORMS CONTENT, COMBINED AREA - YEAR 1992
-------
Table 15
PREDICTED TREATED STORM WATER RUNOFF QUALITY CHARACTERISTICS
YEAR 1992
o
o
Treatment
Combination
3, 700 acre-ft Pond
0% Removal
0 acre-ft Pond
30% Removal
280 acre-ft Pond
30% Removal
625 acre-ft Pond
30% Removal
0 acre-ft Pond
60% Removal
None
Total Suspended
Solids, mg/1
Meaji
58. 1
197
175
168
145
250
Max
693
553
483
483
399
693
BOD,
mg/1
Mean
10. 1
98. 6
98.7
94. 3
72.5
125
Ma
348
276
276
276
204
348
Fecal Coliforms,
org/1
Mean
3. 3x10'
6. 3x10
6. 3x10
5. 8x10
6, 3x10
Max
1. 0x10"
1. 0x10'
1. 0x10'
1. 0x10'
1. 0x10'
6. 3xl04 1. OxlO5
-------
800
700
600 —
500 —
I
<
cc
Ul
u
O 300-
200 —
100 —
0.01
400 —
0.1
1
10
90 96
98 99
99.9
20 30 40 50 60 70
PERCENTAGE LESS THAN GIVEN VALUE
Figure 360 EFFECT OF VARIOUS TREATMENTS ON COMBINED OVERFLOWS
TOTAL SUSPENDED SOLIDS CONTENT, COMBINED AREA - YEAR 1992
99.99
-------
400
0.01
20 30 40 50 60 70 80 90
PERCENTAGE LESS THAN GIVEN VALUE
Figure 37.
EFFECT OF VARIOUS TREATMENTS ON COMBINED OVERFLOWS
BOD CONTENT, COMBINED AREA - YEAR 1992
-------
400
350 —
300 —
250 —
1
O
Oo
200
150 —
100 —
"0.01
0.1
10 20 30 40 50 60 70 80
PERCENTAGE LESS THAN GIVEN VALUE
90 95 98 99
99.9
99.99
Figure 38. EFFECT OF VARIOUS TREATMENTS ON COMBINED OVERFLOWS
FECAL COLIFORM CONTENT, COMBINED AREA - YEAR 1992
-------
Table 16
PREDICTED TREATED COMBINED SEWAGE QUALITY CHARACTERISTICS
YEAR 1992
^
Treatment
Combination
8, 400 acre-ft Pond
0% Removal
0 acre-ft Pond
30% Removal
0 acre-ft Pond
60% Removal
445 acre-ft Pond
60% Removal
1, 000 acre-ft Pond
60% Removal
None
Total Suspended
Solids, nag/1
Mean
59. 8
145
106
73. 1
65. 2
184
Max
385
483
357
245
245
595
BOD,
mg/1
Mean
15. 2
135
98.9
95.8
62. 8
170
Max
276
292
2.2
212
212
364
Fecal Coliforms,
org/1
Mean
2. 6xl0
4. IxlO
4. IxlO
3. 8xl0
1.2xlO
4. IxlO
Max
1. IxlO1
2. 3x10
2. 3x10
2. 3x10
20 2x10
2. 3x10
8
8
8
-------
would be less. Large ponds in this case would however effect a re-
duction in maximum expected pollutant concentrations.
RECEIVING WATER QUALITY
It was not feasible to make use of a synthetic procedure to estimate
the Sacramento River's natural pollution load. The processes govern-
ing introduction and removal of pollutants in the River are not subject
to ready quantification. Instead, empirical correlations between Ri-
ver flow and pollutant concentration were developed from, existing
data. These relations are presented in an earlier subsection.
Hourly River flows were obtained by straight-line interpolation be-
tween the bracketing daily values. Concentrations of total suspended
solids, BOD, and fecal coliforms were then computed as 3-point in-
terpolations in tables expressing the aforementioned correlations.
The estimated distributions of the three pollutant concentrations in
the Sacramento River for 1992 prior to wastewater discharges from
the Combined Area are presented in Figure 39.
105
-------
16
14
ir
Z 12
LU
O
O
O
CO
§ 10
O
D
Z
LU
Q.
CO
CO
_l
<
O
Q
Z
Q
§
-,40
MEAN VALUES
Total Suspended Solids, mg/f
BOD, mg/f
Fecal Coliforms, org/f
132
2
1.0 x 107
FECAL
COLIFORMS
BOD,mg/H
30
20
CO
TOTAL SUSPENDED
SOLIDS, 102mg/^
10
0
0.01
20 30 40 50 60 70 80 90
PERCENTAGE LESS THAN GIVEN VALUE
0.1
10
95
98 99
99.99
Figure 39. ESTIMATED BACKGROUND DISTRIBUTION OF POLLUTANT
CONCENTRATIONS IN THE SACRAMENTO RIVER - YEAR 1992
-------
Section VII
SYSTEMS ANALYSIS
Detailed descriptions and costs of the various components comprising
the system for abatement of water pollution from storm water runoff
and combined sewer overflows were prepared to permit a thorough and
careful analysis and comparison of all alternatives. Although specially
related to the situation in the City of Sacramento, the discussion should
be construed to have general application elsewhere.
COSTING
To provide a common basis for comparing costs of the alternative sys-
tems, total annual costs for construction, installation, operation, and
maintenance of each alternative were estimated.
CONSTRUCTION AND INSTALLATION
Sewer line construction cost estimating was pursued in more detail than
other costing aspects of overall sewage system construction for several
reasons. First, the sewer lines represented a substantial percentage
of total costs. Secondly, since separation of flows was basic to several
of the alternatives, the careful development of estimated costs was war-
ranted in order to properly compare and evaluate all of the alternatives.
A general purpose computer program was developed for estimating the
construction costs of complete sewer systems within the Study Area.
Inputs to the costing program were received directly from the outputs
of the sewer design programs simulating the various conveyance alter-
natives. These costs were developed for each sewer line and for each
main trunk system.
For the force main concepts, the sewer line costs also include the
grinder-pump costs for transfer of sewage into the force main. Sizing
the number of grinder-pump units were derived from the computer pro-
grams using the relation shown in Figure 23 of the preceding section.
Construction costs of reservoirs or storage ponds varied with size and
location. Curves were developed to relate cost and size over a wide
range of capacities for both near-surface underground and surface
reservoirs.
Some of the treatment processes under consideration had very little
in the way of historical precedent for development of construction costs.
In these cases, the cost backup was derived by subdividing the process-
es into parts for component costing. Every attempt was made to cost
107
-------
the alternative systems on a common basis.
OPERATIONS AND MAINTENANCE
In addition to the estimation of all capital costs for construction and
installation, annual operational and maintenance costs were developed
for each capital cost item. Wherever applicable, curves were de-
veloped to relate annual operational and maintenance costs to system
capacity so as to cover a range of sizes where optimizing trade-off
opportunities became available.
ANNUAL CONVERSION
All facilities construction costs were developed from a mid-1969 base
for the Sacramento area. On all developed costs, a 15-percent upward
adjustment was applied to account for miscellaneous items not covered
in the initial preliminary design work. The mid-1969 costs were then
converted to mid-1972 costs using an 8-percent annual escalation fac-
tor. While the 8-percent annual escalation was higher than the long-
term historical experience of from four to five percent, it was lower
than the 1968 annual increase of about 10 percent. Mid-1972 was se-
lected as the target start date for new construction on the basis that
this is the earliest practical start date subsequent to the necessary
planning and engineering work. An allowance of 15 percent of con-
struction cost was also applied to cover all planning, engineering de-
sign, administrative, and construction management services.
The costs of all new facilities were converted to a mid-1972 annual
basis by amortizing over the life expectancy of each installation, using
a 5-percent interest rate. The general guidelines established for life
expectancy were perpetual life for land requirements, 40 years for sew-
age conveyance systems and large reservoirs, 20 years for pumping
plants and treatment facilities, and ten years for selected equipment
within pumping plants and treatment facilities.
The 15-percent contingency allowance and the 8-percent annual esca-
lation adjustment were also applied to the annual operational and main-
tenance costs in the same manner as applied to new facilities construc-
tion costs to reach the mid-1972 construction start date. Annual esca-
lation beyond mid-1972 for the cost of new construction, equipment re-
placement, and operation and maintenance was estimated at five percent.
COLLECTION AND CONVEYANCE
Two of the candidate systems entail separation of sanitary sewage and
storm water runoff, thus requiring either a new storm or a new sani-
tary system while the existing combined system would be used to con-
vey, respectively, the sanitary sewage or the storm water runoff.
There are, in addition, other collection and conveyance options to be
investigated. The boundary location between gravity separated system
108
-------
and force main system must be specified when considering the hybrid
force main concept, Regardless of candidate system, the existing
system augmentation requirements to meet a given overall criteria.
level must be considered. As a result, seven different collection and
conveyance subsystems were analyzed.
DESCRIPTION
Gravity Separation
Three alternatives were investigated relative to complete gravity sep-
aration of sanitary and storm water flows. All three alternatives are
primarily concerned with the separation requirements in the Combined
Area portion of the Study Area. Each alternative subsystem contains,
in addition to the basic features described below, the necessary aug-
mentations of existing facilities to provide a complete, comparable
subsystem.
New Gravity Storm Sewers (Augmented Existing System for Sanitary)
For the Combined Area, a new storm sewer installation was designed
with the existing sewer system utilized for sanitary sewage only. As
expected, the existing combined system was found to be more than
adequate for projected sanitary sewage peak flows, with few minor
exceptions, and thus requires very limited augmentation.
New Gravity Sanitary Sewers (Augmented Existing System for Storm)
For the Combined Area, a new sanitary sewer installation was designed
with the existing sewer system utilized for storm water runoff only.
The existing system was found to be undersized for almost its entire
length, even for a storm of 2-year recurrence expectancy, and would
require augmentation to provide adequate hydraulic capacity.
Augmentation of Existing Combined Sewers
For the Combined Area, the existing combined system was augmented
by superimposing a new-design parallel system as required to assure
that combined flow criteria, requirements would be met at all points
along the combined sewer length. This augmented combined system
then provided a basis for evaluating the relative merits of separated
versus combined flows.
ASCE Force Main Separation
The ASCE System of separation of sanitary wastewaters from storm
water runoff envisions construction of individual dwelling, commercial,
or industrial grinder-pump units discharging into a pressure-line sys-
tem developed to convey the sanitary wastes to a treatment location.
The many facets of the program ranging from consideration of individual
109
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home sewage flow variations to control and pumping techniques have
been explored in detail by the ASCE (Ref. 13).
In essence, the ASCE concept proposes that each individual dwelling and
building have a combination storage, grinder, and pumping facility.
Where possible, the grinder-pump station would be located within the
basement and the small plastic discharge piping to the common pres-
sure line in the street would be laid within the existing service con-
nection. There are variations in the street force mains proposed but,
in principal, they are shallow lines laid in trenches in the parkway
areas which proceed to a common collection point.
One of the ASCE schemes proposes the use of pressure lines within
sections of existing gravity sections wherever sewers of sufficient
size are available. Throughout these gravity sections, the pressure
lines would be suspended from the pipe soffit on hangers, with special
manholes constructed to accommodate the essential valving. Controls
would be provided to maintain a positive pressure within the system to
prevent alternate filling and draining of lines. The installation of the
smaller diameter force mains would increase the capacity of the ex-
isting combined sewage system for use as a separate storm drainage
system, thus accomplishing the separation concept.
A modification to the ASCE concept was derived in this program to eli-
minate most of the individual household grinder-pump units and sub-
stitute a larger zonal grinder-pump station. The merits of this scheme
are economics and the potential maintenance advantage inherent with a
single large station for an area rather than many small individual units.
It should be noted that many existing small 8-, 10-, and 12-in. diam-
eter sewers which have sufficient capacity for sanitary flows but not
for storm runoff, requiring replacement in any separated storm sewer
application, would be utilized in this approach to convey sanitary sew-
age to the zonal grinder-pump units.
Another factor that suggests the use of zonal grinder-pump stations
is the existence of separated sanitary systems which discharge into
combined sewers at the terminus of their particular development. It
is only logical to maintain the segregated sanitary and storm waters in
the upper reaches by constructing a grinder-pump station at the ter-
minus of the existing separated sanitary sewers and pumping the efflu-
ent at this point into the new pressurized system.
Several force main layouts were suggested in the ASCE program, vary-
ing in costs and degree of flexibility. In general, the systems may be
classified as dual or single piping configurations. Only the dual-line
layout was considered in this investigation. The dual system consists
of a pressure line on each side of the street to which the individual
household or building unit may be connected. Each single pipe is sized
to convey the peak flow from one side of the street only, representing
one half of the total flow that would be generated on the street and trans-
ported in a single, common gravity sewer. A typical piping layout is
110
-------
shown in Figure 40. Valving and valve manholes are'provide'd at each
intersection to allow isolation of one side of theVstreet for cleaning and
maintenance. By manipulation of valves, flows may be passed around
any isolated section. Should one section be shutdown for cleaning, the
line on the other side of the street would transport all of the flow. This
temporary increase in head loss should, however, be of little concern
since the additional frictional losses within a block reach are minor
when compared to the entire system. The merits of scheduling routine
cleaning coincident with off-peak usage are obvious.
A corollary to this method is the use of large-size sewers to provide a
passage for the pressure lines rather than trenching along'the curb
lines. Where the large sewers are available, the pressure lines are
suspended from the soffit within the gravity sewer. The method of in-
serting and suspending the force mains within the larger gravity sewers
does not appear to be an easy task, however. Relatively short pipe
lengths of ten feet appear to be the most practical for ease of insertion
and handling, since the manhole structure would require modification to
accommodate the valving, and excavation could be opened adjacent to the
manhole to allow for insertion of the short lengths. A sewer dolly, con-
structed to carry and position the pipe, could transport materials from
the access manhole a considerable distance before another access man-
hole would be required. Construction could only be accomplished during
minimum flows.
One intriguing possibility for construction of the in-sewer force main
would be the use of formed sections of pipe that fit the soffit of the
larger gravity sewer, thus providing a mating shape to the sewer cross-
section. The pipe shapes would vary widely to accommodate the required
flow and to fit the range of envelope gravity sewer pipe sizes. A cir-
cular pipe section could be reformed to almost any desired shape and
section. Protective coatings inside and outside would be required to
protect the steel from the corrosive atmosphere associated with sewage.
A formed rubber gasketed joint at 10-ft intervals would be advisable
with pipe supports provided by spaced toggle bolts and angles. Trans-
ition sections from arch to round would be required at the valve stations.
Several options were available to store, grind, and pump building and
dwelling wastes into the community pressure system. Consideration
included ability to pump against a pressure head of about 35 psig. Among
the schemes that have been used with some degree of success in past ex-
periments were a storage tank feeding a commercial garbage grinder
unit with a separate pump to provide the necessary system head, and a
storage tank with a combination grinder-pump unit. The first type of
unit has the disadvantages of higher first cost and greater spacial re-
quirements. The combination grinder-pump unit offers lower initial
first cost, is compact, and is currently under intense development.
The Water Management Laboratory of the General Electric Company
has put forth considerable effort toward developing a device capable of
meeting this need. Environment One Corporation is producing a similar
111
-------
IN)
CLEAN OUT FITTING (TYP1
SHUT OFF VALVE (TYP)
DETAIL I
GROUND SURFACE
PLAN VIEW
-EXISTING SEWER
Figure 40. ASCE COMBINED SEWER SEPARATION PROJECT TYPICAL PIPING LAYOUT
-------
appliance for a demonstration grant project with the New York State De-
partment of Health. The Railway Sanitation Research Project has also
conducted extensive testing with use of commercial grinders in railcar
toilets with a degree of success. Baker Filtration also is experiment-
ing with a combination unit capable of both grinding and pumping at a
reasonable cost.
As a comparative figure, it was estimated that a separate grinder and
pump would cost approximately twice that of an integrated unit. For
this reason, coupled with the present efforts being made to commer-
cially develop and market integrated units, the combination grinder-
pump was selected for application to this study.
The household unit power requirements would be in the neighborhood
of 1. 5 hp while the larger capacity units suitable for apartment build-
ings would require a 5-hp motor. A 30- to 50-gal storage reservoir
is adequate for domestic units and piping is simple. Capacities and
heads can be readily varied. Estimated cost of the domestic unit falls
in the range of $300 to $500 for the grinder-pump alone, increasing
to over $2, 000 for a complete operating installation. Figure 41 shows
a layout of a typical home installation. The pump discharge line of
polyethylene or polybutylene should be equipped with a shutoff valve
and check valve. The check may be a normally closed solenoid valve
that opens when the grinder-pump starter is energized. This type of
check is virtually fool-proof and is essential to avoid backflow and
flooding of individual units. The polyethylene or polybutylene dis-
charge tubing has proven successful for snaking through existing house
laterals by either pulling or pushing. The fittings for the line should
be of the "no-hub" variety to avoid projections within the line.
The concept of zonal pump stations to reduce the number of individual
household units results in grinding and pumping installations of a size
where a wide range of equipment is available. Comminution equip-
ment with grinding capacities ranging from 0. 03 to 20 mgd have been
proven in operation for many years with most satisfactory results.
The range of sizes for nonclog pumps is almost infinite.
The type of station chosen for the zonal pump stations is the common
wet pit-dry pit installation with the grinder, bypass channel and rack,
and wet well on one side of the bulkhead. Vertical pedestal mounted
pumps and electrical switchgear are located in the dry pit side of the
station. Consideration may be given to installation of flow meters at
each station. A magnetic flow meter installed in the discharge piping
would be suitable for maintaining flow records. The pump station con-
figuration is purposely long and narrow to allow installation between
curb and property line in many instances. A typical installation of
this type is depicted in Figure 42. The larger pump stations, as shown
in Figures 43 and 44, where two or more grinders and a bypass chan-
nel are required, precluded the use of a narrow structure.
113
-------
A
MAkl HOLE COV
P L A NJ
n
CUT HUE-
r1-^
•cr- .-'—L
: :•»?
^^
SI' f 'W^g^
LlFTlUC,
li"4> C3ALV. STL. PIPE-J
£XI6T
LATERAL
PLU 6 VALVE/
•o
^
-a
o -
> c'
•5 it*
LlUE
PoLYETHYLEME PIPE.
-PLUG VALVE
-SOLEKJOID
VALVE
E- C T I O M A-A
Figure 41. INDIVIDUAL GRiNDER-PUMP UNIT
114
-------
Y~
\
.COV6RED OPEWIUfii POB
1 1
1 1
1 I
J-J.
..
"-'
_
^
-x
^
-
-
"^
^
-
•"
^
'-*-*? ' - -
^-*L
COMMlMUTOR
ACCESS j
CHAIU OPEZATfrD
6ATE VALV
PUMI" ACCESS
eDPEUlklGS
COVfrRED VtUT
COVERED VSWT.
ROD F PL AM
i
COMMIklUTOR
&LEVATIOKJ
UOTE:
TYPICAL. AlZRAKIGEiMtlJT OP %MALL TO
MEDIUM SITE StWEK PUMt* STATIONS FOR
FOIICt-MAIW APPLICATIOkl.
lAOO TO 320O CPM CAP.
F LOOK PLAU
Figure 42. MEDIUM ZONAL GRINDER-PUMP STATION
-------
(TYP 4. PLAC£6>)
IKILET PIPE
AlK FbLOWErR
(EXHAUST TO
-GATE
•AlK INLET
CATMOS)
WET WELL
CHECkl VALVE
AIR IMLET
(AT MO 6)
VERTICAL PUMP
(TYPICAL. *>
NOTE
TYPICAL ARRMvlGEMESIT OF LARGE
SIZE SEWER PUMP STATIONS FOR.
PORCE -MAIN APPLICATION. I-Z.OOO
GPM CAR
Figure 43. PLAN OF LARGE GRINDER-PUMP STATION
-------
AlE EXHAUST
AIE INLET
Figure 44. ELEVATION OF LARGE GRINDER-PUMP STATION
-------
To avoid a large wet well and the usual odor nuisance, variable speed
pumps were used in all stations. The variable speed equipment matches
the incoming flow and eliminates the surges associated with intermittent
pump operation. All pump stations were considered to be below sur-
face installations with separate hatches for the wet well and dry well.
Four alternatives were investigated relative to the ASCE force main
concept. As with the first three gravity conveyance alternatives, the
force main alternatives are primarily concerned with the Combined
Area portion of the Study Area. Thus, no attempt was made to adapt
the force main concept to the parts of the Study Area where separa-
tion of flows already exists. The so-called hybrid force main concepts
utilize a combination of gravity flow and pressurized flow with zonal-
type grinder-pump units rather than units located at every individual
service connection.
Total Force Main
For the Combined Area, a total force main concept was applied, where-
in every service connection without exception within the area would be
served with a grinder-pump unit so that sanitary flows would be handled
entirely via pressure lines. In the Separated Area, the sanitary sew-
age would flow in the existing gravity sanitary sewers to the pressure
system boundary where grinder-pump units would be located to inject
it into the pressurized system.
Hybrid Force Main (New Gravity Storm Sewers Area)
For the new gravity storm sewer system previously described, it was
assumed that storm runoff would travel on the surface for about one
block before catch basins or inlets would intercept the flow and dis-
charge to the sewer. In superimposing that alternative system on the
existing combined network, there remains many laterals of one-block
length not required for storm flows and, therefore, available for sani-
tary use. But in applying the Total Force Main concept, these exist-
ing laterals would be unused. A logical force main scheme would en-
tail making use of these existing laterals for sanitary gravity flow to
zonal grinder-pump units. This Hybrid Force Main alternative em-
bodies this approach wherein the new sanitary force main would be
installed only where the new gravity storm sewers would be placed.
All force mains in this system would be placed in trenches.
Hybrid Force Main (Pipe-in-Pipe/New Gravity Sanitary Sewers Up-
stream)
A basic feature of the ASCE Force Main concept is the utilization of
existing combined sewers as a conduit or pipe gallery for the installa-
tion of the new smaller sanitary pressure lines so that storm and sani-
tary flows become separated. Based on the design criteria adopted for
118
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this study, the existing combined system was found to be undersized
for storm flows along almost its entire length. As a result, the pipe-
in-pipe concept has little advantage, since major storm water convey-
ance system augmentation was indicated to provide adequate hydraulic
capacity and no excess capacity within the pipe is available for place-
ment of even a small pressure conduit.
This alternative considered use of the force main only within a 48-in.
diameter or larger gravity conduit. Since the existing combined
system was already undersized, this force main system alternative
was superimposed on the new gravity storm sewer system downstream
of the locations specifying a 48-in0 or larger diameter pipe for the con-
veyance of separated storm water runoff.
This hybrid system requires the installation of a new gravity sewer
system for separation of flows upstream from the first downstream
48-in. pipe. For this alternative, a new upstream gravity sanitary
sewer system was selected and the existing sewer was utilized and
augmented for separated storm flows.
Hybrid Force Main (Pipe-in-Pipe/New Gravity Storm Sewers Upstream)
This alternative is identical to that immediately preceding with the ex-
ception that a new gravity storm system was installed upstream with
the existing upstream combined sewer utilized and augmented where
necessary for separated sanitary flows.
COSTS
Table 17 summarizes the costs for each of the seven conveyance alter-
natives for the Study Area, including the augmentation requirements for
storm water runoff conveyance in the Separated Area. All seven alter-
native subsystems provide the same hydraulic capacity by a combina-
tion of new facilities, existing facilities, and augmentations of existing
facilities. The capital costs have been converted to an annual basis and
annual operational and maintenance costs have been included. Since all
seven alternatives involve new or augmented facilities for handling
storm flows, the costs were computed for 2-, 5-, and 10-year storm
recurrence expectancies,, For the four force main concepts, the costs
include the grinder-pump requirements associated with each of the
alternatives.
COMPARISON
All seven conveyance alternatives were designed to meet the same speci-
fied criteria, including augmentation of the existing sewer system where
found necessary to comply. Therefore, all seven alternatives may be
said to provide equal performance characteristics.
119
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Alternative No. 1 provides a new-design storm sewer system and Al-
ternative No. 2 provides a new-design sanitary sewer system, with
the same complete separation of flows occurring in both cases. Alter-
native No. 2 was eliminated from further consideration, since it is
more costly than Alternative No. 1. Also, complete separation via the
installation of a new-design storm sewer system follows the pattern al-
ready well established within the Study Area for relief of the existing
combined sewer system. Approximately one-third of the Study Area
is served by separated storm sewers with the older combined sewers
being utilized for sanitary sewage.
Table 17
ANNUAL COSTS OF CONVEYANCE ALTERNATIVES
(millions of dollars)
Storm Recurrence Expectancy
General System Description 2-yr 5-yr 10-yr
1. New Gravity Storm Sewers 2. 68 3. 68 4. 16
(Augmented Existing
System for Sanitary)
2. New Gravity Sanitary Sewers 3. 35 4. 12 4. 48
(Augmented Existing
System for Storm)
3. Augmentation of Existing 20 16 3. 10 30 48
Combined Sewers
4, Total Force Main 18.74 19.52 19.87
5. Hybrid Force Main 13.78 14. 56 14.91
(New Gravity Storm
Sewers Area)
6. Hybrid Force Main 5. 33 6. 51 6. 94
(Pipe-in-Pipe/New
Gravity Sanitary
Sewers Upstream)
7. Hybrid Force Main 4. 70 5. 92 6. 35
(Pip e - in - Pip e /New
Gravity Storm Sewers
Upstream
120
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Alternative No. 3 proposes continuing the combination of sanitary and
storm flows with the existing system augmented to meet the specified
criteria. Although less costly than Alternative No. 1, a direct com-
parison between the two systems is not possible since subsequent
treatment requirements are not identical. Therefore, both alterna-
tives were considered within the framework of overall sewerage sys-
tems evaluation.
Alternatives No. 4 through 7 require a new-design sanitary force main
system resulting in complete separation of flows in all four cases.
Alternatives No. 4 and 5 propose large-scale force main installations
over virtually the entire existing truly combined portion of the Study
Area. Of the two systems, Alternative No. 5 is more economical,
primarily because of more efficient utilization of the existing com-
bined sewer system. Therefore, Alternative No. 4 was eliminated
from further consideration.
Alternatives No. 6 and 7 propose new force mains only where a storm
sewer of 48-in. diameter or larger is available for placement of the
pressure lines within. Using a new-design storm sewer system as the
basis, a relatively small portion of the combined sewer system area
meets the 48-in. diameter requirement. As a result, these two alter-
natives are far less costly than the large-scale force main systems and
they approach the still lower cost gravity systems. Of the two, Alter-
native No. 7 is less costly; therefore, Alternative No. 6 was eliminated
from further consideration.
In defense of the force main concept, a more detailed investigation than
was performed in this study would probably show numerous ways to re-
duce system costs. For example, elimination of dual lines and elimin-
ation of the grinder requirement where flows exceed an established
minimum would provide significant savings over those developed in
this study. It is estimated, for example, that about a 20-percent re-
duction in annual cost could result if a single-line force main system
were used. However, except where unusual conditions prevail, it
appears doubtful that a force main system could be justified on the basis
of cost alone in competition with a more conventional gravity sewer sys-
tem.
The conveyance system cost associated with any overall sewer system
that is predicated on separation of flows would be independent of the re-
mainder of the total system costs. On this basis, all force main sys-
tems could be eliminated, since separated gravity flow systems are
less expensive. However, Alternatives No. 5 and 7 were maintained in
the analysis and considered as representative force main concepts in
the development of overall sewage system costs.
121
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STORAGE
Th- -- 01 the candidate systems, including stabilization ponds which are
primarily a treatment process, are considered here under the storage
category. Since a complete sewer system does not necessarily require
storage, this system component may be considered as optional. Thus
four alternatives were investigated, of which one of the four was the
complete absence of storage facilities.
Regardless of the storage alternative under consideration for contain-
ment of combined sewage, the reservoirs were sized to accommodate
only the combined flow volume occurring during periods of storm run-
off. At all other times, the sanitary flow would bypass the reservoir
and would be processed through the conventional treatment facilities.
DESCRIPTION
A storage facility provides a means for modulating peak flows, thus re-
ducing downstream capacity requirements for conveyance, treatment,
and disposal and providing for more efficient utilization of downstream
equipment and facilities. These obvious advantages must be weighed
against the cost of the reservoir installation.
Suitable locations for reservoirs are frequently difficult to find. Usu-
ally the area involved is already developed, resulting in high land costs
and strong objections from vested interests to the construction of this
type of facility. Thus, regardless of potential advantages, it may be-
come necessary to provide sewer system improvements without benefit
of storage.
Underground Storage
This concept evolved from the development work carried out in Chicago
on underground storage of combined sewage. The Chicago program pro-
posed to utilize modern tunnel excavation techniques to provide new
main sewers and interceptors as well as mined storage. The stored
waters could then be released at a reduced rate to treatment facilities.
The costs of the long-range program are to be defrayed in part by power
generation through pumped storage between underground and surface
reservoirs and by sale of mined aggregate.
The subsurface conditions in the Sacramento area do not favor the deep
tunnel approach. Consequently, the concept was modified to consider
only relatively shallow or near-surface underground storage provided
through open-type excavation rather than by tunneling.
Underground reservoirs are best justified in already developed areas.
A location just north of Sump No. 2 was selected for application of this
122
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concept (see Figure 25). This prospective site is presently single-
family residential. Extensive relocation would be required, with the
resulting open area over the reservoir available for development of
recreational areas, public parks, or other applications.
A reinforced concrete structure is proposed with the top of sufficient
strength to withstand earth cover and light-weight vehicular loads. A
dividing wall would provide two separated water-tight compartments
to assist in operation and maintenance activities. Access provisions
for periodic cleanout would be provided.
Surface Storage
Assuming the availability of flat open land, a surface reservoir pro-
vides the least costly storage facility. Cut-and-fill construction is
envisioned with the fill material utilized for peripheral dike construc-
tion. A dike dividing the reservoir into two parts is proposed to assist
in operation and maintenance activities. An asphaltic pavement sur-
facing would be used to restrict outflow from and inflow to the reser-
voir due to groundwater seepage.
For the Sacramento area, three locations were selected for applica-
tion of the surface reservoir concept. The American River Park lo-
cation would provide storage for already separated storm flows only.
Either the Sacramento Port location or the South Sacramento location
would provide storage for several combinations of storm flow alone
and combined flow from either the Combined Area or the total Study
Area.
Stabilization Pond
The preceding description of surface storage facilities applies equally
to stabilization ponds. Considered primarily as a treatment process,
the stabilization ponds were accordingly sized to a large capacity. The
storage reservoirs, on the other hand, primarily would serve as peak
flow modulators where capacity is balanced against an optimum out-
flow rate.
Both the Sacramento Port and the South Sacramento locations were used
for application of the stabilization pond concept. The combined flow
pond was sized on the basis of a rough estimate of available acreage.
The capacity of the stabilization pond for treatment of separated storm
water runoff was determined on the basis of the same pond withdrawal
rate that was used for combined flow.
COSTS
Costs were developed for a range of reservoir sizes and depths which,
in turn, were related to a given reservoir outflow or withdrawal rate.
Table 18 presents reservoir capacities for the selected locations and
123
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Table 18
CAPACITIES OF RESERVOIRS
(millions of gallons)
ro
Location
American River Park
Surface Reservoir
Sump 2 Vicinity
Underground
Reservoir
Surface Reservoir
South Sacramento
Surface Reservoir
With-
drawal
Rate
mgd
1 0
20
40
80
160
231*
320
352*
422*
40
80
160
320
575*
577*
640
842*
892*
993*
1077*
10
40
80
160
320
640
10
40
80
160
320
640
yr btorm Recurrence
Storm
Flow
Combined
Flow
Separated Area
176
117
73
39
12
0
0
_
-
Combined Area
305
190
104
42
0
0
0
-
-
-
-
619
352
153
57
-
-
0
-
-
-
Combined Area
847
305
190
104
42
0
1857
619
352
153
57
0
Combined Area
847
305
190
104
42
0
1857
619
352
153
57
0
Storm
Flow
Combined
Flow
Study Area
528
365
205
96
-
-
20
-
-
-
1108
505
290
121
-
-
28
-
-
-
-
Study Area
-
528
365
205
96
20
-
1108
505
290
121
28
Study Area
_
528
365
205
96
20
_
1108
505
290
121
28
y torm Recurrence
Storm
Flow
Combined
Flow
Separated Area
264
176
108
55
21
-
0
0
-
Combined Area
457
306
156
68
-
9
-
0
-
863
489
215
90
-
-
15
0
-
-
-
Combined Area
120C-
457
306
156
68
9
2737
863
489
215
90
15
Combined Area
1205
457
306
156
68
9
2737
863
489
215
90
15
Storm
Flow
Combined
Flow
Study Area
766
547
293
147
-
-
47
-
-
-
-
1564
717
430
150
-
-
62
-
-
-
-
Study Area
-
766
547
293
147
47
-
1564
717
430
150
62
Study Area
_
766
547
293
147
47
_
1564
717
430
150
62
-yr orm
Storm
Flow
Combined
Flow
Separated Area
325
222
130
64
30
-
1
-
0
Combined Area
588
392
193
91
-
-
13
-
-
-
0
1010
570
257
117
-
-
20
-
-
0
-
Combined Area
1401
588
392
193
91
13
3128
1010
570
257
117
20
Combined Area
1401
588
392
193
91
13
3128
1010
570
257
117
20
Storm
Flow
Combined
Flow
Study Area
912
684
342
183
-
-
68
-
-
-
-
1857
896
554
218
-
-
93
-
-
-
-
Study Area
_
912
684
342
183
68
_
1857
896
554
218
93
Study Area
_
912
684
342
183
68
1857
896
554
218
93
Flow (No Reservoir)
-------
2-, 5-, and 10-year storm recurrence expectancies. Corresponding
annual costs, including operation and maintenance, are summarized
in Table 19.
To simplify the assembly of major subsystem components into complete
sewer systems, the reservoir costs also include the associated pump-
ing and connecting piping costs. Underground reservoirs were assumed
to have gravity inflow and pumped withdrawal. A typical pumping sta-
tion for reservoir withdrawal is shown in Figures 45 and 46. Surface
reservoirs were assumed to have pumped inflow and gravity outflow.
Depicted in Figures 47, 48, and 49 is a typical below-grade pumping
station which may be utilized in a variety of applications including the
filling of reservoirs. Connecting piping is from the termination of
the conveyance systems at Sump No. 2 to the reservoir. Where al-
ready separated storm flows from the American River Park location
are transported to Sump No. 2 and beyond, the cost of this piping was
also borne by the associated reservoir. The special case at Sump No.
2 where outflow rate equals incoming peak flow, requiring a zero reser-
voir capacity, was also included to account for these same pumping and
piping requirements under the alternative or no reservoir. Utilization
of either the Sacramento Port or the South Sacramento site with no re-
servoir was not considered.
COMPARISON
From the standpoint of providing storage, all of the reservoir alterna-
tives may be considered as giving equal performance characteristics
for the given criteria. The optimum reservoir size for any specific
situation with regard to either subsequent treatment process or to
physical location is related to the reservoir outflow rate. This is dis-
cussed subsequently under Trade-Off Optimization. While not explored
in this study, the problem of objectionable anaerobic conditions devel-
oping -where stored flows are impounded for an extended period must
also be considered in relation to reservoir size and outflow rate.
Underground reservoirs are far more costly to construct than surface
reservoirs. This higher cost must be balanced against the advantages
of the underground system in comparing the two alternatives,, An ob-
vious advantage of the underground installation is that it may be visu-
ally hidden so that objections stemming from appearance are reduced.
Objectionable odors are also better controlled within an enclosed
structure.
TREATMENT PROCESS
Two of the candidate systems, dissolved air flotation and mechanical
screening, are considered here. For convenience, wastewater con-
stituent reductions effected by reservoirs or stabilization ponds and
chlorination have not been considered under this heading.
125
-------
N)
Table 19
ANNUAL COSTS OF RESERVOIRS
(millions of dollars)
Location
American R.ver
Surface Reservoir
Underground
S cramento Port
Surface Reservoir
With -
mgd
10
20
•10
80
160
231*
320
352*
422*
40
80
160
320
575*
640
577*
842*
892*
993*
1077*
10
40
80
160
320
640
10
40
80
160
320
MO
V e
Storm
Flow
Combined
Flow
Separated Area
1. 01
\. 03
.93
.87
. 80
.77
-
-
-
Combined Area
2. 82
1.93
i. 25
.80
.39
-
-
-
-
-
4.87
3. 12
1.63
.93
-
.54
.39
-
-
-
-
Combined Area
1.41
1. 18
.93
.77
.65
. 55
2.35
1.73
,.25
.87
.68
.55
Combined Area
2.33
2. 10
1. 86
1.72
2. 57
1.48
3.27
2.66
2.17
1.79
1.60
1.48
Storm
Flow
Combined
now
Study Area
5.71
4.26
3. 11
2.36
-
-
-
-
-
-
-
9.41
5.35
3.81
2. 56
-
-
-
-
•
-
Study Area
-
2.80
2.50
2.19
1.95
1.82
Stud
-
3.82
3.51
3.21
2.97
2.83
-
3.95
2.80
2.38
2.07
1.88
Area
-
5.18
4.03
3.61
3.30
3. 11
yr orm ecurrence
Storm
Flow
Combined
Flow
1.64
l. 55
1.42
j.29
1.23
-
1.17
1.16
-
Combined Area
3.98
2.77
1.72
1.06
-
.67
-
-
. 57
-
-
6.65
4. 10
2.12
1.23
-
.73
-
. 54
-
-
-
Combined Area
2.03
i.76
1.46
i.l5
.99
.87
3.34
2.47
1.79
1.24
1.00
.85
Combined Area
3.31
3. 04
2.70
2.43
2.27
Z. 15
4.62
3.75
3.07
2.53
2.28
2. 13
Storm
Flow
Combined
Flow
Study Area
7.52
6.08
4.28
3.25
-
2.60
-
-
-
-
12.74
7.19
5.31
3.28
-
2.74
-
-
-
-
-
Study Area
-
3.96
3. 54
3.05
2.80
2.61
-
5.43
3.88
3.39
2.84
2.65
Study Area
-
5.42
5.01
4.52
4.26
4.07
-
7.05
5.50
5.01
4.46
4. 28
Storm
Flow
Combined
Flow
Separated Aron
1.96
1.84
..68
1. 55
1.47
1.42
1.39
Combined Area
4.98
3.56
2.02
1.28
.73
-
-
-
.68
9.20
4.63
2.47
1.48
-
.82
-
-
-
.62
-
Combined Area
2.35
2.09
1.76
1.34
1.16
1.01
3.89
2.87
2.01
i.41
1.15
.96
Combined Area
3.82
3.56
3.23
2. 82
2.63
2.48
5.28
4.25
3.40
2.79
2.53
2.34
Storm
Flow
Combined
Flow
Study Area
8.73
7.23
4.96
3.85
-
3.09
-
-
-
-
-
14.87
8.77
6.51
4.11
-
3.31
.
-
-
-
-
Study Area
-
4.64
4.22
3. 55
3.25
3.03
-
6.41
4.64
4.06
3.47
3.15
Study Area
-
6.38
5.95
5.29
4.98
4.77
-
8.57
6.83
6.23
5.64
5.31
*Peak Flow (No Reservoir)
-------
.^ LIME WHEW
15 FULL
K&S8&J I 'I
_r___) I J-.
P L A KJ V I Er W
Figure 45. PLAN OF TYPICAL PUMP STATION FOR RESERVOIR WITHDRAWAL
-------
IX)
00
WATER L3.VE.'-
FLAP <5ATE TYPICAL
ALL PUMPS
MAIM PUMP
SUMMES PL
-------
xD
Figure 47. PLAN AT GRADE OF TYPICAL SUBSURFACE PUMP STATION
-------
PL<»W IW
MAIW fUMPi
ftAPFLfr
SUMMER FL<7N PUMP
SUMP
Figure 48. PLAN BELOW GRADE OF TYPICAL SUBSURFACE PUMP STATION
-------
FL/CW PUMP
Figure 49. SECTION OF TYPICAL SUBSURFACE PUMP STATION
-------
The treatment alternatives consider only the processing of either com-
bined flows or already separated storm flows. In all instances where
only sanitary sewage would be present in the sewer, the flow would be
diverted to the conventional treatment facilities and is not further con-
sidered,,
DESCRIPTION
No Treatment
Within the framework of this study, the no-treatment alternative con-
siders only the absence of either dissolved air flotation or mechanical
screening as candidate system treatment processes. The option re-
mains of utilizing a pond, either individually or in conjunction with
conventional treatment, with the resulting improvement in waste dis-
charge characteristics.
In the cases predicated on separation of flows, it -was presumed that
all sanitary sewage will be accommodated by existing or enlarged con-
ventional treatment facilities. For separated storm water runoff or
for combined flows it was presumed that the minimum acceptable treat-
ment under any circumstances will include chlorination, even though
this has not been classified as a candidate system.
Dissolved Air Flotation
To provide a common basis for comparison of dissolved air flotation
with other alternative treatment processes, a unit output capacity of
40 mgd was established. Total system requirements were met with
modules of this basic unit. Two dissolved air flotation preliminary
designs were prepared, one for the condition of 30-percent removal of
suspended solids and the other for 60-percent removal,,
A conceptual plan of a 40-mgd unit for 30-percent suspended solids re-
moval is shown in Figure 50. Ideally, a reservoir preceding the treat-
ment process would provide a controlled inflow. A minimum water
level within the basin would be attained prior to starting the treatment
facility. If this minimum level were not attained before runoff has sub-
sided and trunk line capacity became available, the impounded water
would be pumped back to the trunk line at a rate not to exceed existing
treatment plant capacity. If the water level continued to rise, the treat-
ment facility would be started and flows processed until the basin has
been emptied.
Plant start-up may be completely automated from the time the process
comes on the line until it is shut down. Assuming controlled inflow,
approximately 2, 6 hours would be required to fill the tanks and for the
operation to function fully. On a level signal, the skimmers and collec-
tors would be started along with the effluent recirculation pumps and air
compressor. During the initial phase of operation, prechlorination may
be desirable to minimize odors.
132
-------
IN'-ST
EFF LU&UT
C0LLEC7I0W
TAMK
TAWK
•SCUM
Ctf LLECTI0W
TAWK
-^ I U C t I I B L.I T —' -^
AFFLUENT RECIRCULATI0U
PUMP
INPLUEKIT
" CHAWNBU .-. ^
-__' t - ' ' I "."I. ' ' ' *---..' '.. ' 'T ' ' ' '
P L A KJ
1JJPLUEMT CHANMJL
\^^y^' * ^ ' f»:9ffim -f j»..-i«fj
Figure 50. DISSOLVED AIR FLOTATION UNIT
-------
Incoming wastewater would be distributed via a channel into each tank.
Within the tank, the flow would be diverted downward and across the
dissolved air header wherein effluent saturated with oxygen is to be in-
troduced. The air-saturated effluent would carry floatables to the sur-
face and dense particulates would settle to the bottom. The floatables
on the tank water surface and the settled matter on the bottom would be
transported to a rotating skimmer and a helical sludge collector, re-
spectively, by traveling chain collectors. The floatables would travel
to a common pit for return to the trunk sewer together with the sludge
withdrawn from the tank hoppers. Each hopper and pit would be pumped
individually through air-actuated valves rotationally sequenced by means
of a timer.
Plant effluent would pass upward beyond a baffle into a quiescent area
and flow over weirs into the effluent channel. The re circulation pumps
would return 20 percent of the flow to the tanks at a pressure of 65 psig.
Compressed air at 30 cfm would be injected into the pipeline prior to a
dissolved air tank with a retention period of one minute. From the dis-
solved air tank, the saturated effluent would be fed to the slotted tank
headers through a distribution main.
At the termination of operation, the plant effluent may be recirculated
to wash down the storage reservoir and pump station. Final dewater-
ing of the plant may be accomplished by using the sludge and recircula-
tion pumps.
Mechanical Screening
The SWECO mechanical screening unit applied here has been termed
the Wastewater Concentrator and was designed primarily for the re-
moval of substantial portions of both floatable and settleable solids,
but it also has the capability of removing from 32 to 36 percent of the
suspended solids and achieving BOD reductions of from 12 to 23 per-
cent. The flow split between treated effluent and concentrate used in
this program was approximately 80:20, although very recent data
from the manufacturer would indicate that similar removals of solids
can be effected at a split of 88:12.
The unit consists of a cylindrical screen rotating about a vertical axis.
The feedwater enters through a central inlet pipe and flows horizon-
tally outward to the revolving screen over a distribution dome. The
cylindrical screen revolves at between 50 to 60 rpm and passes approx-
imately 80 to 88 percent of the flow out of the unit as effluent. The re-
maining 12 to 20 percent drops down the inside of the screen and is dis>
charged separately from the unit as concentrate.
Each separator unit employs an inside-outside hot water spray clean-
ing system operated by cycle timers. Best performance reportedly
occurs with 4. 5-minute on and 0. 5-minute off cycles. During the on
cycle, the outside hot water spray system operates. At the end of
134
-------
4. 5 minutes, the feed flow is interrupted and the back-spray system
then operates for 30 seconds.
Each separator unit is powered by a 5-hp, 220/440-v, 3-phase motor.
The screens consist of a series of segmented, easily replaceable
panels which, in the case of the 8-ft diameter unit envisioned for the
40-mgd module, would contain approximately 24 panel screens. Peri-
odic inspection and replacement of screens would be required.
For the Sacramento application, fourteen 8-ft diameter separators
were combined within a common effluent basin shown in Figure 51.
The 14-unit module would give a net effluent outflow rate of 40 mgd,
requiring an influent rate of 50 mgd with the 80:20 flow split.
In the 40-mgd module the system would be activated by liquid-level
controls, which would turn on the hot water system, the influent pumps,
and the module control system. The module control system would en-
ergize the screen drive motors and activate the air-operated butterfly
valves to the individual units in a sequential order. Timers would acti-
vate the solenoid valves in the spray lines inside and outside the cylin-
drical screen. Shutdown operations would follow a similar pattern in
reverse.
In considering overall study area requirements, the 20-percent volume
of concentrate produced by the separator represents a significant vol-
ume still requiring treatment and disposal. Since this concentrate flow
will frequently exceed the off-peak capacity of the treatment plant, the
screening process was considered feasible only in combination with an
upstream reservoir with provisions made for recycling of the concen-
trate back through the reservoir. Thus the net 80-percent effluent flow
rate would be maintained continually and the concentrate treatment
accomplished through controlled input to the treatment plant as off-peak
capacity became available. As discussed later under Trade-Off Opti-
mization, the inclusion of the reservoir in combination with the screen-
ing process did not impose an undue burden on the subsystem, since a
cost savings was also achieved.
During the preparation of this report, the manufacturer submitted new
data showing significantly improved performance for the screening
units. The improved performance was derived from a flow split ratio
of 88 parts effluent to 12 parts concentrate rather than the previously
reported 80:20, and from a greater input flow through the standard
5-ft diameter model than previously considered feasible. For the 40-
mgd module, sixteen 5-ft diameter separator units are indicated rather
than the previously considered fourteen 8-ft diameter separator units.
COSTS
Dissolved air flotation treatment costs were developed for systems
capable of suspended solids reductions of 30 and 60 percent. Mechani-
cal screening treatment costs were developed for a system effecting
135
-------
tFFLUtNT SUMP
WASTE WAT6IZ C<7M CE|JT[IAT
-------
30-percent removal of suspended solids.
Multiples of the basic 40-mgd modules were applied as required to meet
total flow requirements as specified either by peak conditions or reser-
voir withdrawal rates. The total annual costs are summarized in Table
20 for the several locations under consideration. An annual operation
and maintenance cost allowance is included. There are no associated
pumping or connecting piping costs lumped with treatment costs that re-
main a requirement independently of the treatment process. Therefore,
as shown in Table 20, the alternative of no treatment produced a zero
cost value.
The costs presented in Table 20 for the mechanical screening process
do not reflect the most recent performance data, which were received
too late for processing. It is estimated that the incorporation of this
improved performance data would effect a cost reduction of about 25
percent below the values presented. Therefore, for 30-percent re-
movals, the mechanical screening process should prove less costly
than dissolved air flotation.
COMPARISON
Comparison of 30- and 60-percent removals for the dissolved air flota-
tion process becomes a matter of relating resultant effluent quality to
cost, which -will be considered later.
For 30-percent removals, a comparison between dissolved air flotation
and mechanical screening is difficult because of the general lack of
quantitative data. For both alternatives, additional testing under field
operating conditions would be desirable before proceeding with the de-
sign and construction of a full-scale system. While not reflected in
Table 20, the mechanical screening process would be selected on the
basis of cost alone if the improved performance data were considered.
EFFLUENT DISPOSAL
Effluent disposal has been included as a major subsystem classification
in order that each of the candidate systems may be evaluated within the
framework of a complete sewer system. Effluent disposal requirements
were varied only to the extent necessary to satisfy the complete sewer
system criteria, as the other alternatives were manipulated. According-
ly, effluent disposal was not in itself considered as an alternative.
DESCRIPTION
Chlorination was established as a mandatory requirement prior to efflu-
ent disposal, regardless of any preceding treatment process that may
be specified. Depending on the location of treatment facilities, a con-
tact chamber of sufficient capacity was provided such that total elapsed
time prior to river discharge is a minimum of 15 minutes subsequent to
137
-------
Table 20
ANNUAL COSTS OF TREATMENT FOR VARIED INFLUENT FLOW RATES
(millions of dollars)
U>
00
Location
American River Park
Surface Reservoir
Sump 2 Vicinity
Underground
Reservoir
Sacramento Port
Surface Reservoir
South Sacramento
Surface Reservoir
Influent
Rale.
mgd
10
20
40
80
160
231»
320
352»
422*
40
SO
160
320
575*
640
842*
892*
993*
1077»
40
80
160
320
640
40
80
160
320
640
Air Flotation
30% Suspended Solids Removal
Storm
Flow
Combined
Flow
Separated Area
.09
. 16
. 29
. 53
. 54
i.09
.79
.93
Combined Area
. 11
.21
.38
.71
1.22
1.29
-
1.82
-
2.16
Combi
.12
.28
.50
.93
1.70
. 12
.21
.39
.73
-
1.33
1.73
-
2.00
-
led Area
.13
.29
.52
.96
1.74
Combined Area
.15
.27
.49
.93
1.70
.16
.28
.51
.96
1.74
Storm
Flow
Combined
Flow
Study Area
.12
.22
.40
.75
-
1.38
-
-
-
-
.13
.23
.42
.79
-
1.45
-
-
-
-
Study Area
.13
.30
. 53
.98
1.78
.14
.32
.56
1.03
1.86
Study Area
.16
.29
.52
.98
1.78
.17
.31
.55
1.03
1.86
Air Flotation
60% Suspended Solids Removal
Storm
Flow
Combined
Flow
Separated Area
-
.15
.27
. 50
.92
1.08
1.83
1.57
1.85
Combined Area
.21
.41
.75
1.41
2.45
2.55
-
3.64
-
4.32
.22
.42
.77
1.45
-
2.63
3.46
-
4.01
-
Combined Area
.22
.47
.86
1.62
2.97
.23
.49
.90
1.68
3.05
Combined Area
.25
.46
.85
1.62
2.97
.26
.48
.89
1.68
3.05
Storm
Flow
Combined
Flow
Study Area
.23
.43
.79
1.49
-
2.73
-
-
-
-
.25
.45
.83
1.57
-
2.87
-
-
-
-
Study Area
.24
,51
.92
1.72
3.13
.26
. 55
.98
1.82
3.29
Study Area
.27
.50
.91
1.71
3.13
.29
.54
.97
1.81
3.29
Mechanical Screening
30% Suspended Solids Removal
Storm
Flow
Combined
Flow
Separated Area
-
. 12
.21
.39
.69
-
1. 26
-
-
Combined Area
.14
.26
.48
.89
-
1.65
-
-
-
-
.14
.27
.49
.91
-
1.70
-
-
-
-
Combined Area
.21
.39
.68
1.23
2.23
.22
.39
.69
1.25
2.27
Combined Area
.19
.36
.66
1.20
2.20
.20
.36
.67
1.22
2.24
Storm
Flow
Combined
Flow
Study Area
.15
.28
.51
.94
-
1.76
-
-
-
-
.15
.29
.53
.98
-
1.85
-
-
-
-
Study Area
.22
.40
.70
1.27
2.32
.23
.41
.72
1.31
2.42
Study Area .
.20
.37
.68
1.24
2.29
.21
.38
.70
1.28
2.39
* Peak Flow (No Reservoir)
-------
chlorination. A typical chlorination facility is shown in Figure 52.
Where peak flows without benefit of storage are to be handled, the
15-minute elapsed time was reduced to ten minutes for the peak flow
condition. In those cases where storage without subsequent treat-
ment was specified, the reservoir itself would function as the contact '
chamber. The outfall sewer line requirements and associated lift sta-
tion requirements are also included under the effluent disposal category.
COSTS
The annual costs, including operation and maintenance costs, relating
to effluent disposal are summarized in Table 210
TRADE-OFF OPTIMIZATION
Wherever storage was included as a part of a complete sewer system,
the specified withdrawal rate effected not only reservoir size but also
downstream treatment and effluent disposal sizing requirements. Func-
tioning as a peak-flow modulator, the reservoir size and cost increases
as the withdrawal rate is reduced, while downstream the facilities ca-
pacity requirements and costs decrease.
Ignoring resultant effluent wastewater quality variations, an optimum
(least cost) arrangement of capacities was established for all alterna-
tives within the major subsystem classifications of storage, treatment,
and effluent disposal. The resulting reservoir sizes, withdrawal rates,
and combined storage-treatment-disposal minimum costs are summari-
zed in Table 22.
A tabular listing of alternatives by major subsystems is given in Table
23, which includes an identification letter and number for keying into
Tables 24 through 30, which present the summary costs of the com-
plete sewer systems for the Study Area.
139
-------
CONTACT
\-O B I MATOI2
£ H LiPft IKl ATOrl
-ftAFFLES
5E-CTIOKJ A-A
Figure 52. CHLORINATION FACILITY
-------
Table 21
ANNUAL COSTS OF EFFLUENT CHLORINATION AND DISPOSAL
Location
American River Park
Separated Area
Surface Reservoir
Sump 2 Vicinity
Combined Area
Underground
Reservoir
Sacramento Port
Combined Area
Surface Reservoir
South Sacramento
Combined Area
Surface Reservoir
*
No reservoir
Storm
Recurrence
Expectancy,
years
-
-
-
-
-
2
5
10
-
-
-
-
2
5
10
2
5
10
-
_
-
_
-
_
_
_
_
_
_
Peak Peak
Storm Combined
Flow, Flow,
mgd mgd
-
-
-
-
-
231*
352*
422*
-
-
-
-
-
577*
892*
1077*
575*
842*
993*
-
_
-
-
-
_
.
-
_
_
-
_
Reservoir
Withdrawal
Rate,
mgd
20
40
80
160
320
-
-
-
40
80
160
320
640
-
-
-
-
-
-
10
40
80
16'0
320
640
10
40
80
160
320
640
Annual
Cost,
million !
0.03
0. 04
0.05
0. 07
0. 10
0. 07
0. 09
0. 10
0.04
0. 05
0.07
0. 22
0.48
0.35
0.48
0. 55
0. 38
0.51
0.58
0.03
0.04
0.06
0.08
0. 11
0. 16
0.09
0. 14
0. 06
0. 31
0.52
0. 90
141
-------
Table 22
COMBINATIONS OF STORAGE, TREATMENT, AND DISPOSAL
RESULTING IN MINIMUM ANNUAL COSTS
1
Location
American
River Park
Surface
Sump 2
Under-
ground
Reservoir
Sacramento
Port
Surface
Reservoir
South
Surface
Re8ervoir
Treatment
Percent Removal
Suspended Solids
Air Flotation, 30%
Mech. Screens. 30%
Air Flotation, 30%
Air Flotation, 60%
Mech. Screens, 30%
Air Flotation, 30%
Air Flotation, 60%
Air Flotation, 60%
Mech. Screens, 30%
2-yr Storm Recurrence
Flow
•s x
$2
•«
U "
•3 §
C — •
-------
Table 23
KEY FOR COMPLETE SEWER SYSTEM
COSTING COMBINATIONS
(Presented in Tables 24 through 30)
A - SEPARATED AREA
1. Treatment at Individual Sumps
2. Treatment at American River Park
3. Storm Flow to Sump No. 2
B - CONVEYANCE SYSTEM
1. New Gravity Storm Sewers (Alternate 1)
2. Augmentation of Existing Combined Sewers
Pipe-in-Pipe/New Gravity Storm Sewers Upstream
(Alternate 3)
3. Hybrid Force Main (Alternate 7)
4. Hybrid Force Main - New Gravity Storm Sewers
(Alternate 5)
5. Existing Storm System Augmented
C - STORAGE
1. Underground - Storm Runoff
2. Underground - Combined Sewage
3. No Reservoir
4. Surface - Storm Runoff
5. Surface - Combined Sewage
6. Stabilization Pond - Storm Runoff
7. Stabilization Pond - Combined Sewage
D - TREATMENT AND DISPOSAL
1. Air Flotation - 30% Suspended Solids Removal
2. Air Flotation - 60% Suspended Solids Removal
3. Mechanical Screening - 30% Suspended Solids Removal
4, No Treatment (Except Chlorination)
5» Conventional Sewage Treatment (40 mgd)
143
-------
Table 24
ANNUAL SYSTEM COSTS, SEPARATED AREA"
(millions 'of dollars)
Storm Recurrence
BCD 2-yr 5-yr 10-yr
1
2
2
2
2
2
2
5
5
5
5
5
5
5
3
4
3
4
3
6
3
4
1
1
2
2
4
4
0. 65
1.43
1. 68
1. 51
2. 22
1. 50
1. 14
0.96
2. 10
2. 53
2. 21
3. 31
2. 23
1.74
1.07
2. 39
2.93
2. 50
3. 86
2. 60
2, 01
Reference Table 23 Key
144
-------
Table 25
ANNUAL SYSTEM COSTS, COMBINED AREA
SUMP NO. 2 VICINITY LOCATION*
(millions of dollars)
Storm Recurrence
B
1
1
1
1
1
1
2
2
2
2
2
3
3
3
3
3
3
4
4
4
4
4
4
2
C
1
1
1
3
3
3
2
2
2
3
3
1
1
1
3
3
3
1
1
1
3
3
3
3
D
1
2
3
4
1
2
1
2
3
1
2
1
2
3
4
1
2
1
2
3
4
1
2
4
2-yr
4. 03
4. 48
4. 18
2. 78
4. 34
5. 57
3.71
4. 24
3. 87
3. 86
5.09
6. 05
6. 51
6. 20
4. 80
6. 36
7.59
15. 14
15.59
15. 29
13.89
15.45
16.67
2.29
5-yr
5. 21
5.74
5. 39
3. 73
6.06
7. 88
4. 81
5. 44
5. 00
5. 39
6. 61
7. 45
7. 98
7. 62
5.97
8. 30
10. 12
16.09
16. 62
16. 27
14.61
16.94
19.76
3. 18
10-yr
5. 88
6.43
6, 04
4. 28
7. 03
9. 19
5. 40
6. 07
5.60
6. 16
8. 17
8.06
8. 62
8. 23
6.47
9.22
11. 38
16.63
17. 18
16.79
15. 03
17.78
19.94
3. 62
'f
Reference Table 23 Key
145
-------
Table 26
ANNUAL SYSTEM COSTS, COMBINED AREA
SACRAMENTO PORT LOCATION*
(millions of dollars)
Storm Recurrence
A B
1
1
1
1
2
2
2
2
3
3
3
3
4
4
4
4
1
2
3
4
'-Reference Table 23 Key
146
c
4
4
4
6
5
5
5
7
4
4
4
6
4
4
4
6
4
5
4
4
D
1
2
3
4
1
2
3
4
1
2
3
4
1
2
3
4
5
5
5
5
2-yr
30 67
3. 84
3.77
3. 85
3. 33
3. 64
3. 48
4. 26
5. 69
5. 86
5.79
5. 87
14.77
14.94
14. 87
14. 95
4. 07
4. 10
6.09
15. 17
5-yr
4.94
5. 22
5.09
5.29
4. 45
4. 84
4. 64
6. 01
7. 18
7.45
7. 33
7. 52
15.82
16. 10
15.97
16. 17
5. 65
5.78
7. 89
16. 53
10-y:
5. 58
5.94
5.76
6.06
4.96
5. 34
5. 15
6.92
7.77
8. 13
7.95
8. 24
16. 33
16. 69
16. 51
16. 81
6.46
6. 56
8. 65
17. 21
-------
Table 27
ANNUAL SYSTEM COSTS, COMBINED AREA
SOUTH SACRAMENTO LOCATION*
(millions of dollars)
Storm Recurrence
D 2-yr 5-yr 10-yr
1
1
1
1
1
2
2
2
2
2
3
3
3
3
3
4
4
4
4
4
4
4
4
6
4
5
5
5
7
5
4
4
4
6
4
4
4
4
6
4
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
1
2
3
4
5
4.70
4. 88
4.78
4. 80
4.89
4.45
4.73
4. 57
5. 22
4.93
6. 72
6.90
6. 80
6. 83
6.91
15. 80
15.98
15. 88
15.91
15.99
6. 37
6. 58
6.46
6.60
6. 83
5.95
6.27
6.09
7. 33
6.96
8. 60
8. 82
8.70
8. 84
9.07
17. 25
17. 46
17. 34
17.48
17. 71
7.28
7.57
7. 40
7. 56
7. 83
6. 58
6.91
6.71
8. 34
7. 84
9.46
9.76
9.59
9.75
10. 02
18.03
18. 32
18. 15
18. 31
18. 58
"Reference Table 23 Key
147
-------
Table 28
ANNUAL SYSTEM COSTS, STUDY AREA
SUMP NO. 2 VICINITY LOCATION*
(millions of dollars)
Storm Recurrence
3 1
3 1
3 1
3 2
3 2
3 2
3 3
3 3
3 3
3 4
3 4
3 4
'Reference Table 23 Key
c
1
1
1
2
2
2
1
1
1
1
1
1
D
1
2
3
1
2
3
1
2
3
1
2
3
2-yr
6. 00
6. 54
6. 16
5. 68
6. 38
5. 88
8. 02
8. 56
8. 18
17. 10
17. 65
17. 27
5-yr
7. 87
8. 61
8. 10
7. 33
8.09
7. 55
10. 11
10. 84
10. 34
18. 75
19.49
18.98
10-yr
8, 97
9.67
9. 18
8. 50
9. 30
8. 73
11. 16
11. 85
11. 37
19. 72
20. 42
19.93
148
-------
Table 29
ANNUAL SYSTEM COSTS, STUDY AREA
SACRAMENTO PORT LOCATION*
(millions of dollars)
Storm Recurrence
A
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
B
1
1
1
2
2
2
3
3
3
4
4
4
1
2
3
4
C
4
4
4
5
5
5
4
4
4
4
4
4
4
5
4
4
D
1
2
3
1
2
3
1
2
3
1
2
3
5
5
5
5
2-yr
5.48
5.75
5. 62
.5. 14
5.47
5. 30
7. 50
7.76
7.64
16. 58
16.85
16.72
4. 62
5.25
6.64
15.72
5-yr
7. 32
7.71
7.51
6.97
7.48
7. 22
9.56
9.95
9.75
18. 20
18.59
18. 39
6. 32
7.21
7.56
17.20
10-yr
8. 20
8.69
8. 50
8.00
8.53
8. 25
10.49
10. 87
10.68
19.05
19.44
19.25
7. 19
8. 28
9.38
17.94
^Reference Table 23 Key
149
-------
Table 30
ANNUAL SYSTEM COSTS, STUDY AREA
SOUTH SACRAMENTO LOCATION*
(millions of dollars)
Storm Recurrence
A B CD 2-yr 5-yr 10-yr
3 1 4 1 6. 67 8.93 10.29
3 1 4 2 6.89 9.35 10.65
3 1 4 3 6. 76 9. 17 10. 44
3 1 4 5 5. 54 7. 68 8. 83
3 2 5 1 6.57 8.92 10.50
3 2 5 2 6.88 9.27 10.92
3 2 5 3 6.60 9.09 10.68
3 2 5 5 6.38 8.74 10.35
33 41 8.69 11.26 12.47
3 3 4 2 8.91 11.59 12.84
3 3 4 3 8.79 11.40 12.62
33 45 7,56 9.92 11.02
3 4 4 1 17.77 19.91 21.04
3 4 4 2 17.99 20.23 21/40
3 4 4 3 17. 87 20. 05 21. 19
3 4 4 5 16.64 18.56 19.58
•jf
'Reference Table 23 Key
150
-------
Section VIII
SYSTEMS EVALUATION AND SELECTION
The evaluation of systems for the control of water pollution from storm
water runoff and combined sewer overflows for the purpose of present-
ing one or more systems for selection depends upon several inter-re-
lated factors. The major considerations are system performance, sys-
tem cost, and other system effects on the environment in regard to
meeting acceptable and specified standards or criteria. Actual selec-
tion of the system must be made by the administrators responsible for
their implementation, financing, and operation and will depend upon
many complex political, social, and economic considerations that are
beyond the usual rigorous definition, quantification, and analysis. Thus
the best that technology can do is present the costs, performance, and
effects of alternative public works systems in a display that will aid the
administrator in his selection.
EVALUATION CRITERIA
The adequacy of any alternative system must be measured against cri-
teria that have been established to allow the attainment of public goals
and objectives. The criteria must be realistic in magnitude and form
to permit implementation and operation within a community's con-
straints of economics, responsibilities, and attitudes.
SYSTEM PERFORMANCE
The systems considered in this program should be capable of perform-
ing two major functions designed to eliminate or significantly reduce
detrimental effects on the environment and to decrease any impairment
to public well-being and enjoyment.
The first is the management of storm water runoff and combined sewer
overflow quantities so as to reduce the occurrence of or eliminate un-
controlled discharges from treatment facilities to the receiving waters.
In this program, all alternative systems were designed to provide the
same adequate hydraulic capacity for three storm recurrence expec-
tancies. Thus, all alternative systems designed for a particular storm
recurrence interval perform comparably and require no evaluation with
regard to their hydraulic performance.
The second performance function has to do with the effect of the alterna-
tive system on the quality of the environment. Whereas the hydraulic
aspects are local in impact, the system's performance in regard to wa-
ter quality must be judged from the viewpoint of not only local but re-
gional and national considerations of the total water resource manage-
ment system. The method developed in this program assesses the
151
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extent of the pollution in the immediate vicinity occurring as the re-
sult of alternative storm water runoff and combined sewage control
systems. While no attempt has been made to extend the approach to
consider the spatial and temporal changes resulting downstream from
the installation and operation of the various alternatives, this ex-
pansion in the methodology could be accomplished. However, those
considerations depend quite heavily upon the type of receiving water
system, i. e. , river, lake, embayment, estuary, or ocean.
Hydraulic Considerations
Most structures for the containment of naturally occurring waters are
designed on the basis of the average occurrence or expectancy of sin-
gle events, which have associated with them a particular expected mag-
nitude. Thus hydraulic works are sized to handle at least the quanti-
ties of water associated with storms that are lesser in magnitude than
the design storm of a particular recurrence interval. Large structures,
such as dams and reservoirs built for controlling floods are designed
to withstand and contain severe storms that occur on the average once
every 50 or 100 years because their inadequacy could result in major
destruction of life and property. Structures for controlling lesser quan-
tities of storm runoff are sized for correspondingly lesser storm in-
tensities and duration, which occur more frequently; flood control chan-
nels are adequate to contain the runoff from storms that recur once
every 25 or 50 years. Buried conduit or sewer systems on the other
hand are usually designed to carry adequately only the runoff from
storms that can be expected to occur on the average once every five
to ten years. The relatively frequent inadequacy of these systems can
be justified on the grounds that during the deficient periods little if any
loss of life or property occurs, that the system is usually conservative
in design and capable of somewhat greater capacity during periods of
surcharging and minor flooding of overlying surfaces, and that the in-
conveniences caused are tolerable and acceptable to the public.
In this analysis, conveyance systems and their hydraulically related
appurtenances were designed to have adequate capacity for all expected
storms that recur only once every two years, once every five years, and
once every ten years. The three recurrence intervals were chosen for
several reasons. First, it was not known a priori what storm interval
best represented the existing conveyance system, "although recent separa-
tion projects were based reportedly on 10-year recurrence intervals.
The correct recurrence expectancy was important for establishing re-
quirements in supplementing the existing system to bring it to the arbi-
trarily selected design capacity. Secondly, since all three could be
readily and rapidly accommodated in the design procedure, it would per-
mit a comparison of costs between the various systems for the three re-
turn intervals.
All further discussion herein is based on systems designed to perform
adequately without surcharging for storms of severity less than one
152
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that would be expected to occur on the average once every five years.
It is believed that systems designed to this storm recurrence interval
for the conditions in the Sacramento Study Area are adequate and real-
istic, based primarily on the apparent public acceptance of a system
which by the design standards and procedures employed in this pro-
gram will not be completely adequate for a storm of 2-year recurrence.
Water Quality Aspects
The performance of facilities in achieving acceptable water quality con-
trol objectives can be established on the basis of requirements applied
either to the waste discharge quality or to the receiving water quality
following discharge of the wastes and their immediate assimilation. In
many cases and certainly for the pollutants considered pertinent to this
program, requirements placed directly on wastewater discharges must
be based on a careful determination and evaluation of the assimilative
capacity of receiving waters and the effects on overall water quality. Be-
cause the natural quality of the receiving waters for the storm water run-
off and combined sewer overflows from the Study Area were quite varia-
ble over a rather large range and were flow dependent, it was imperative
in this program to consider the extent to which the various alternative
systems affected the receiving water quality following the admixing of
the wastewater discharges, particularly since some of the wastewater
pollutant characteristics were somewhat similar in magnitude and the
quantities of discharge were usually quite small compared to those of
the receiving waters.
Due to the variations in wastewater and receiving water quality and quan-
tity, it is not possible to establish realistic single values or sets of wa-
ter quality criteria that will suffice for all occasions at all times. In-
stead, a distribution of wastewater and receiving water qualities exists
that represents, on the average, both naturally occurring and humanly
controlled systems, and the specified criteria should reflect these dis-
tributions and the associated expectancies. Three water quality crite-
rion parameters are suggested to completely determine the ability of
alternative systems to perform adequately in meeting water quality ob-
jectives. A system, to be acceptable, must meet all three criteria.
The first water quality criterion parameter establishes an absolute maxi-
mum concentration of pullutant that cannot be exceeded at any time. This
parameter will prevent the occurrence of acute lethal dosages of pollu-
tants for the protection of the public health and the fisheries resource
and other single, but catostrophic, occurrences. The second parameter
establishes an acceptable distribution of pollutant concentrations by speci-
fying a frequency of occurrence of a particular value. That is to say that
a specified value can be exceeded only a certain small percentage of the
total time. This parameter recognizes the presence of periods in which
the receiving waters are below acceptable quality which does not consti-
tute long-term degradation but only tolerable transient conditions. All
uses of the receiving waters dependent upon pollutant concentration-
153
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time relations such as chronic animal toxicity are accommodated by
this criterion parameter. In those downstream water uses however
that require a change or stoppage of procedure during those periods
when pollutant concentrations are excessive, such as could occur for
water supply operations, the total duration of the occurrence of ex-
cessive concentration is probably of less concern than the number of
times that the value is exceeded and extraordinary operational proce-
dures initiated. This is similar to the determination of hydraulic
capacities based on recurrence interval of a particular storm and the
associated runoff volumes, where the number of flooding episodes or
the meer existance of flooding is of more importance than the total
duration of flooding. Whereas a cumulative frequency distribution
parameter indicates the total time over which any particular value is
exceeded, e. g. , 12 hours annually, it does not indicate whether this
value will be exceeded once for a total of 12 hours each year or on 12
separate occasions each of 1-hour duration. The third water quality
criterion parameter accounts for this by establishing the acceptable
number of occurrences or expectancy for any particular concentra-
tion to be exceeded.
Therefore it is proposed that these criterion parameters, all of which
must be satisfied, can adequately and completely describe the required
performance of a water quality control facility. These will be termed
maximum value criterion, cumulative distribution criterion, and ex-
cession frequency criterion.
As will be discussed subsequently, if the pertinent water quality charac-
teristics of the receiving water are unacceptably or undesirably high as
the result of uncontrolled surface runoff or upstream discharges of in-
adequately treated wastewaters and the relative mixing volume of re-
ceiving water quite great, the evaluation of alternative systems is ex-
tremely difficult since the discharge of a highly treated wastewater has
no measurable effect different from the discharge of the same influent
wastewater untreated. Since this situation occurs in this program with
regard to suspended solids and fecal coliforms the performance of the
alternative systems in controlling these pollutants will be judged differ-
ently from that used for BOD, which was based on simulated discharge
to the receiving water of anticipated indigenous quality. *
The system performance for controlling the discharge of suspended
solids was based on the incremental addition of suspended solids to the
receiving waters by considering that the receiving waters contained no
suspended solids or impurities prior to discharge of the treated waste-
waters. In this way the contribution of various alternative systems to
the total receiving water burden could better be assessed.
*
In effect, the same holds true for BOD, since a constant low-level value,
derived from expected likely future levels, was assumed to obtain at all
times.
154
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Fecal coliforms are not included in subsequent discussions, since chlo-
rination facilities capable of virtually total disinfection were provided
in all alternative systems, including the no treatment configuration.
FINANCING
A variety of methods and sources exist for financing the planning, de-
sign, construction, and operation of systems for the control of pollu-
tion from storm water runoff and combined sewer overflows. Finan-
cing sources may be categorized into two major types--capital con-
struction, and operation and maintenance. In general, sources of
funds that might be used wholly or partly by an agency for financing the
design and construction of sewerage facilities include general obliga-
tion bonds, revenue bonds, special assessments, general tax revenues,
Federal subsidies, private capital, state funds, and county funds. For
operation and maintenance funding, ad valorem taxes, connection char-
ges, participation fees, and service charges are commonly used me-
thods for obtaining needed revenues.
The availability and application of these funds however is often depen-
dent upon the exact nature and type of sewerage facilities, particularly
with regard to Federal participation. To take full advantage of all po-
tential funds therefore requires careful consideration of system ob-
jectives and features.
The Federal Water Pollution Control Act PL 84-660 as amended 33
USC 466 et seq. Clean Water Restoration Act of 1966, PL 89-753 is
available for accelerating local wastewater treatment works construc-
tion. Grants can be made to any state, municipality, or other munici-
pal or interstate agency for the construction of wastewater treatment
and disposal systems, including collection of interceptor sewer flows.
Several funding arrangements are available and include a 40-percent
grant if the state also contributes at least 30 percent, a 50-percent
grant if the state also contributes 25 percent and the system performs
in conformance with enforceable water quality standards, and a 60-per-
cent grant if the project conforms with a comprehensive metropolitan
plan.
For those facilities not eligible for assistance under Federal Water Pol-
lution Control Act, PL 84-660 as amended, direct grants are available
to public agencies for financing up to 50 percent of the construction of
storm water runoff and combined sewage collection systems under the
Housing and Urban Development Act of 1965, PL 89-117, 79 STAT 490,
42 USC 3102 (Supp 1, 1965). The remaining 50 percent, when secured
through general obligation or revenue bonds, can be financed by a loan
received under the Public Works and Economic Development Act of
1965, PL 86-136, 79 STAT 552 that may run for as long as 40 years at
an interest rate determined by Government borrowing costs. Should
funding under HUD Act of 1965 be denied and the jurisdiction is designa-
ted as a redevelopment area, application under the Public Works and
155
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Economic Development Act can be amended to request a 50 percent
grant and a Federal loan for the remainder.
Separate storm water runoff sewers can be financed up to 100 percent
under the Watershed Protection and Flood Prevention Act PL 83-566,
PL 89-337, PL 89-4, Section 417, PL 87-703, STAT 608, 609 16 USC
1004, 1005 (Supp V), which provides technical and financial assistance
to state and local agencies in planning, designing, and constructing
watershed improvement works. If these facilities are located in re-
development areas, they can also be funded up to 50 percent under
Public Works and Economic Development Act of 1965, PL 89-156,
STAT 552.
Additional sources of Federal subsidy are available for storage facili-
ties when coupled with land conservation or open-space programs. The
Housing Act of 1961, PL 87-70, 75 STAT 183, 42 USC 1500-1500e (1964)
as amended, 42 USC 1500e (Supp 1, 1965) as amended, 42 USC 1500-
1500d, provides for 50-percent matching grants to public agencies for
acquiring, developing, and preserving open-space land. Grants may be
increased up to 90 percent for projects that demonstrate improved me-
thods of preserving urban open space. Financial assistance is available
to states and their political subdivisions for all types of outdoor recrea-
tional areas and facilities, such as multi-purpose metropolitan parks,
fishing grounds, and boating areas, through the Land and Water Conser-
vation Fund Act of 1965, PL 88-578, 78 STAT 879, 16 USC 460D, 460L-
11 (1964), 23 USC 120 (1964).
Due to the particular provisions and availability of all the foregoing fund-
ing sources, the most economical system overall may not necessarily be
the one of least cost to the local community nor one that can be afforded
locally because of smaller extramural funding assistance. Thus careful
analysis must be made of alternative system costs and the communities
ability or desire to locally finance it.
ENVIRONMENTAL FACTORS
Of growing concern to the populace is the condition of their surrounding
environment and the modification that man has made or can effect.
Therefore in attempts to improve and enhance his environs, he is aware
of other effects, both deleterious and beneficial, that the construction
and operation of other environment-improving facilities might have asso-
ciated with them. An improvement in one condition can be undesirable
if a degradation of another type occurs. Also, aesthetic values associa-
ted with major facilities should be considered and evaluated. Nuisances
and inconvenience, however temporary, connected with specific alterna-
tives must be taken into account. Although the environmental effects of
alternative systems can be described, their absolute and relative im-
portance requires a value judgment that is biased by one's vantage point.
156
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Other factors requiring evaluation for alternative systems include bene-
fits derived by the additional use of the facility for recreational pur-
poses. An example might be the employment of a storm water runoff
storage facility, filled wholly or partly with storm water runoff, for
boating and picnicing.
For the alternative systems considered in this program, it was deter-
mined that, except in a cursory way, the differences that did exist in
the alternatives with regard to their effect on the environment were
small relative to other evaluation criteria and could be dismissed from
further analysis. Much of each system is underground and except for
the period of their placement, would present no irretrievable or per-
haps even no measurable effects on the surrounding community. Re-
creational use of certain portions of alternative systems would be lim-
ited and hence of questionable value, due to the availability of adjacent
waterways and other nearby recreational activities.
SYSTEMS EVALUATION
The expected effects on receiving water quality of storm water runoff
and combined sewage discharges from a selected number of alternative
systems that embrace in performance capability all systems considered
in this program have been determined. Performance of the various sys-
tems was based on only discharges from the Combined Area to the
Sacramento River at the downstream periphery of the Study Area, be-
cause the storm water runoff from the Separated Area was already re-
presented in the Sacramento River quality used to establish background
receiving water characteristics and because the pollution resulting from
these storm water runoff discharges could be determined from evalua-
tion of separated storm water runoff discharges from the Combined
Area. Costs of alternative systems however represent total systems
for the control of storm water runoff and combined sewage overflows
derived from both the Combined Area and the Separated Area.
SYSTEM PERFORMANCE
Twelve systems for the treatment of combined sewage and storm water
runoff, incorporating no treatment facilities (except chlorination) and
combinations of different holding pond capacities and treatment process-
es, were simulated and the consequent receiving water quality distri-
butions determined.
Rejection Criteria
On the basis of specified minimum receiving water quality criteria, it
may be necessary to reject from further consideration several of the
systems, thereby reducing the magnitude and complexity of the systems
evaluation.
157
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For the purposes of this program, values that are likely to be repre-
sentative of requirements imposed on the Sacramento River at the
planning horizon by the appropriate regulatory agency were selected _
for the three water quality criterion parameters--maximum value cri-
terion, cumulative distribution criterion, and excession frequency cri-
terion.
Values selected for the minimum BOD requirements were a maximum
value of 11 mg/1, a cumulative distribution of greater than 6 mg/1 less
than 12 hr/yr, and an excession frequency of greater than 6 mg/1 not
more than twice each year. The maximum value criterion was selec-
ted on the basis that 11 mg/1 represents roughly the dissolved oxygen
saturation content of the Sacramento River which would be totally de-
pleted of oxygen at BOD concentrations of 11 mg/1 neglecting the reac-
tion occurring downstream and the compensating under saturation ex-
isting upstream from the point of wastewater discharge. Similarly- a
BOD content of 6 mg/1 could, if the receiving water upstream is of rea-
sonably good quality, hence near oxygen saturation, reduce the dissolved
oxygen levels to about 5 mg/1, which is usually satisfactory for the pro-
tection of a fisheries and wildlife resource. Concentrations of BOD in
excess of 6 mg/1 could further deplete the dissolved oxygen, but this
condition is tolerable if it persists for only a short percentage of the to-
tal time, such as less than 12 hours out of each year, and if it seldom
recurs, such as no more than two times a year on the average.
For the minimum total suspended solids requirements, values were set
at 50 mg/1 for the maximum value, greater than 10 mg/1 less than 12
hr/yr for the cumulative distribution, and greater than 10 mg/1 not
more than twice a year for the excession frequency.
No minimum requirements were selected for the fecal coliform densi-
ties in the receiving water since it was assumed that all systems, in-
cluding no treatment would provide chlorination facilities to adequately
disinfect the wastewater discharges.
Combined Sewage
The cumulative distributions and excession frequencies of BOD concen-
trations occurring in the Sacramento River immediately after complete
admixing of combined sewage and receiving water for six alternative
systems are shown in Figure 53. Based on the selected performance
criteria, Alternate A, which provides no holding pond or treatment
process, fails all three tests of maximum value, cumulative distribu-
tion, and excession frequency. Alternates B and C, which are systems
with no holding ponds and treatment processes capable of removing 30
and 60 percent of the total suspended solids, respectively, are unaccept-
able because they exceed both the maximum value criterion and the ex-
cession frequency criterion. Moreover, Alternate B, which consists of
a 445 acre-ft holding basin upstream of a 60-percent removal process,
does not meet the cumulative distribution criterion. Alternative D fails
158
-------
Ul
I I
0.01
LEGEND
A No pond, no treatment
B No pond. 30% treatment
C No pond, 60% treatment
445 acre-ft pond, 60% treatment
1,000 acre-ft pond, 60% treatment
8,400 acre-ft pond, no treatment
DURATION, hr/yr
24 12 63
O1 1 2 6 10 20 30 40 SO 60 70 80 90 96 98 99 99i9
NUMBER OF ANNUAL EVENTS PERCENTAGE LESS THAN GIVEN VALUE
Figure 53. BOD CONTENT OF SACRAMENTO RIVER FOLLOWING
COMBINED SEWAGE OVERFLOW DISCHARGE - YEAR 1992
99.99
-------
only the excession frequency test, but thus is also an unacceptable sys-
tem. Of the six alternatives simulated, only Alternatives E and F are
acceptable for providing adequate BOD reductions in the combined sew-
age overflows. These systems contain, respectively, a 1,000 acre-ft
holding pond followed with a process removing 60 percent of the total
suspended solids, or 42 percent of the BOD, and an 8,400 acre-ft stabi-
lization pond with no downstream treatment provided.
Figure 54 presents the incremental BOD concentration cumulative dis-
tributions and excession frequencies that would result in the Sacramento
River from the discharge of the combined sewage overflow after various
treatments. These distributions and expectancies are essentially the
same as those including the natural background if the ordinate value is
shifted 2 mg/1, which is the assumed constant background level in the
River0
The results of the discharge to the Sacramento River of combined sew-
age overflows subjected to treatment by the six alternative systems with
respect to suspended solids concentrations are shown in Figure 55. For
all practical purposes, none of the alternative systems ranging from no
treatment to extremely large holding ponds have any influence on the re-
ceiving water suspended solids concentrations due to the relatively small
flows of combined sewage that contain for the most part suspended solids
concentrations no greater and in some cases less than that of the River.
Therefore to assess the relative performance of the various alternative
systems, cumulative distributions and excession frequencies of suspend-
ed solids concentrations were established for discharge of the treated
combined sewage overflows to the Sacramento River if it were totally
devoid of suspended solids. These results, presented in Figure 56, re-
veal that of the six systems considered, only Alternatives A and B, which
provide for no ponds and either no or 30-percent removal of suspended
solids, are unacceptable since they exceed the excession frequency cri-
terion of 10 mg/1 occurring not more than twice each year.
Although the fecal coliform densities resulting from discharge of the
combined sewage into the Sacramento River are not considered in the
evaluation of systems performance as explained earlier, the density cu-
mulative distributions and excession frequencies were established for
discharge from four alternative systems consisting only of retention
ponds ranging in size from 0 to 8,400 acre-ft. Figure 57 indicates that
none of these treatment systems has a measurable effect on natural
Sacramento River fecal coliform concentrations. From. Figure 58,
which presents the relative performance of the various alternative sys-
tems (containing no disinfection facilities), it is seen that only the use
of an exceptionally large stabilization pond will produce substantial re-
ductions in fecal coliform populations.
160
-------
16
14
12 —
10
o
g 8
cc
u
I \
\\
Unacceptable Zone
I I I I
DURATION, hr/yr
24 12 6 3
LEGEND
A No pond, no treatment
B No pond, 30% treatment
C No pond, 60% treatment
D 445 acre-ft pond, 60% treatment
E 1,000 acre-ft pond, 60% treatment
F 8,400 acre-ft pond, no treatment
I
J L
i
Unacceptable Zone
10
20
30 40 50 60 70
80
90 95 98 99 99^9 99M
PERCENTAGE LESS THAN GIVEN VALUE
'0.01 0.1 1 2 E
NUMBER OF ANNUAL EVENTS
Figure 54, INCREMENTAL ADDITION OF BOD TO SACRAMENTO RIVER BY
COMBINED SEWAGE OVERFLOW DISCHARGE - YEAR 1992
-------
1600
1400
LEGEND
No pond, no treatment
No pond, 30% treatment
No pond, 60% treatment
445 acre-ft pond, 60% treatment
1,000 acre-ft pond, 60% treatment
8,400 acre-ft pond, no treatment
DURATION.hr/yr
24 12 6 3 1
RIVER BACKGROUND
A,B, C, D, E, F
I
0.01 0.1 1 2
NUMBER OF ANNUAL EVENTS
10
20 30 40 50 60 70
80 90 95 98 99 99.9 99.99
PERCENTAGE LESS THAN GIVEN VALUE
Figure 55. SUSPENDED SOLIDS CONTENT OF SACRAMENTO RIVER FOLLOWING
COMBINED SEWAGE OVERFLOW DISCHARGE - YEAR 1992
-------
40
35 —
1 T
I T
I I I I
DURATION hr/yr
24 12 6 3 1
UJ
0.01
LEGEND
No pond, no treatment
No pond, 30% treatment
No pond, 60% treatment
445 acre-ft pond, 60% treatment
1,000 acre-ft pond, 60% treatment
8,400 acre-ft pond, no treatment
0.1 125
NUMBER OF ANNUAL EVENTS
10
20 30 40
90 95
PERCENTAGE LESS THAN GIVEN VALUE
99.9
99.99
Figure 56. INCREMENTAL ADDITION OF SUSPENDED SOLIDS TO SACRAMENTO
RIVER BY COMBINED SEWAGE OVERFLOW DISCHARGE - YEAR 1992
-------
o
to
o
UJ
Q
DURAT|ON.hr/vr
24 12 6 3 1
A No pond, no treatment
B 445 acre-ft pond, no treatment
C 1,000 acre-ft pond, no treatment
8,400 acre-ft pond, no treatment
RIVER BACKGROUND
0.01
IT! 12 5 10 20 30 45 55 60 70 80 90 95~
NUMBER OF ANNUAL EVENTS PERCENTAGE LESS THAN GIVEN VALUE
Figure 57. FECAL COLIFORM DENSITY OF SACRAMENTO RIVER FOLLOWING
COMBINED SEWAGE OVERFLOW DISCHARGE - YEAR 1992
9999
-------
(Jl
>
0.01
LEGEND
No pond, no treatment
445 acre-ft, no treatment
1,000 acre-ft pond, no treatment
8,400 acre-ft pond, no treatment
0.1 125 10
NUMBER OF ANNUAL EVENTS
20 30 40 50 60 70
80 90 95 98 99 99.9
PERCENTAGE LESS THAN GIVEN VALUE
99.99
Figure 58. INCREMENTAL ADDITION OF FECAL COLIFORMS TO SACRAMENTO
RIVER BY COMBINED SEWAGE OVERFLOW DISCHARGE - YEAR 1992
-------
Storm Water Runoff
The effects on the BOD content of Sacramento River of the storm wa-
ter discharges from the Combined Area that are subjected to varying
degrees of treatment are shown in Figure 59. Only Alternatives E
and F, consisting of a 625 acre-ft retention pond with a facility to re-
move 30 percent of the suspended solids and a 3,700 acre-ft stabiliza-
tion pond with no further treatment, respectively, are acceptable sys-
tems according to the selected performance criteria for BOD. Where-
as all six alternative systems considered have acceptable BOD concen-
tration cumulative distributions, three alternatives are rejected on the
basis of both excession frequency and maximum value while a fourth
alternative is unacceptable as a result only of failing the maximum
value criterion.
Distributions of the incremental addition of BOD to the receiving waters
from the six alternative systems are presented in Figure 60.
The cumulative distributions and excession frequencies of suspended
solids in the Sacramento River subsequent to storm water discharge is
shown in Figure 61. No differences in performance of the six alterna-
tive systems for removal of suspended solids are noted upon discharge
of storm water runoff to the Sacramento River, due to the high indige-
nous suspended solids concentration and relative flow of receiving wa-
ters. The relative performance of the various systems in reducing
suspended solids content of the receiving waters, however, are presen-
ted in Figure 62. Only Alternate A, which consists of no system, is un-
acceptable, and then only because of its excessive excession frequency.
Fecal coliform densities that would occur in the Sacramento River as
a result of the discharge of storm water runoff that is not disinfected
by chlorination but is subjected to retention in ponds ranging in size
from 0 to 3,700 acre-ft are shown in Figure 63. No measurable differ-
ences are noted because the flows and bacterial contents of the storm
water runoff are markedly lower than those that are extant in the re-
ceiving waters. The relative performance of the several systems con-
sidered in reducing fecal coliform populations are depicted in Figure 64.
SYSTEMS COST EFFECTIVENESS
The complete system for the abatement of combined sewer overflows
and storm water runoff in the Study Area must include facilities for the
treatment of the separated storm water from the Separated Area and
treatment of either the combined sewage or separated storm water run-
off from the Combined Area. Separated sanitary sewage or dry-weather
flow in combined sewers in the Combined Area would be processed in
the existing Main Treatment Plant and thus are excluded from the sys-
tems under consideration. Two methods of handling the storm water
runoff from the Separated Area were explored--discharge directly to
166
-------
1 I
LEGEND
No pond, no treatment
No pond, 30% treatment
No pond, 60% treatment
280 acre-ft pond, 30% treatment
S2S acre-ft pond, 30% treatment
3,700 acre-ft pond, no treatment
1 I
DURATION, hr/yr
I I
24 12
6 3
1
Unacceptable Zone
I I I
I
I
I
I I
0.01
10
20
30 40 SO 60 70
80
90
95
99
99.9
0.1 125
NUMBER OF ANNUAL EVENTS PERCENTAGE LESS THAN GIVEN VALUE
Figure 59. BOD CONTENT OF SACRAMENTO RIVER FOLLOWING
STORM WATER RUNOFF DISCHARGE - YEAR 1992
99.99
-------
00
0.01
LEGEND
No pond, no treatment
No pond, 30% treatment
No pond, 60% treatment
280 acre-ft pond, 30% treatment
625 acre-ft pond, 30% treatment
3,700 acre-ft pond, no treatment
0.1 125
NUMBER OF ANNUAL EVENTS
10
20
30
40 50 60
70 80 90 95 98 99 991T
PERCENTAGE LESS THAN GIVEN VALUE
T59T99
Figure 60. INCREMENTAL ADDITION OF BOD TO SACRAMENTO RIVER BY
STORM WATER RUNOFF DISCHARGE - YEAR 1992
-------
1600
I III
DURATION, hr/yr
A No pond, no treatment
B No pond, 30% treatment
C No pond, 60% treatment
D 280 acre-ft pond, 30% treatment
E 625 acre-ft pond, 30% treatment
F 3,700 acre-ft pond, no treatment
0.01
0.1 1 2 5 10 20 30 40 50 60 70 80 90 95 99 99.9 §9799
NUMBER OF ANNUAL EVENTS PERCENTAGE LESS THAN GIVEN VALUE
Figure 61. SUSPENDED SOLIDS CONTENT OF SACRAMENTO RIVER FOLLOWING
STORM WATER RUNOFF DISCHARGE - YEAR 1992
-------
1 I
-J
o
g
t-
u
8
I I I
DURATION, hr/yr
24 12 6 3 1
LEGEND
No pond, no treatment
No pond, 30% treatment
No pond, 60% treatment
280 acre-ft pond, 30% treatment
625 acre-ft pond, 30% treatment
3,700 acre-ft pond, no treatment
Unacceptable Zone
0.01 0.1 1 2
NUMBER OF ANNUAL EVENTS
10
20
~3040 BO 60 70 80
90 95 98 99 99.9
PERCENTAGE LESS THAN GIVEN VALUE
99.99
Figure 62. INCREMENTAL ADDITION OF SUSPENDED SOLIDS TO SACRAMENTO
RIVER BY STORM WATER RUNOFF DISCHARGE - YEAR 1992
-------
1 I I
A
B
C
D
LEGEND
No pond, no treatment
280 acre-ft pond, no treatment
625 acre-ft pond, no treatment
3,700 acre-ft pound, no treatment
0.01
0.1 1 2
NUMBER OF ANNUAL EVENTS
10
20 30 40 50 60 70
80
90 95 98 99 99.9
PERCENTAGE LESS THAN GIVEN VALUE
Figure 63, FECAL COLIFORM DENSITY OF SACRAMENTO RIVER FOLLOWING
STORM WATER RUNOFF DISCHARGE - YEAR 1992
-------
-J
ro
0.01
DURATION, hr/yr
24 12 6 3
LEGEND
A No pond, no treatment
B 280 acre-ft pond, no treatment
C 626 acre-ft pond, no treatment
D 3,700 acre-ft pond, no treatment
0.1 125
NUMBER OF ANNUAL EVENTS
90 95 98 99 9ST9991)9
PERCENTAGE LESS THAN GIVEN VALUE
Figure 64. INCREMENTAL ADDITION OF FECAL COLIFORMS TO SACRAMENTO
RIVER BY STORM WATER RUNOFF DISCHARGE - YEAR 1992
-------
the receiving waters from either individual or collective facilities and
discharge to the Combined Area system prior to treatment of all waste-
waters from the Study Area in a single facility.
Applying to the Separated Area and Total Area the results of the per-
formance simulation for the discharge of treated storm water runoff
and combined sewer overflows to the Sacramento River from the Com-
bined Area, a number of acceptably performing systems are available
for evaluation. The general features and the total annual cost of these
systems designed for a 5-year storm recurrence interval are presented
in Table 31.
If the conveyance system remains combined, the minimum annual cost
of $60 94 million is provided by the system comprised of separate col-
lection and treatment in the Separated Area and in the Combined Area.
For the Separated Area, the system consists of an augmented storm
water conveyance network, a 275 acre-ft surface holding pond, an air
flotation unit capable of 30-percent suspended solids reduction, and a
chlorination facility. The separated storm water runoff treatment fa-
cility for the Separated Area is located at the American River Park. In
the Combined Area, the existing combined sewer network is augmented
to deliver wet-weather combined sewage to the Sacramento Port loca-
tion across the Sacramento River, where treatment and disposal faci-
lities consist of an 890 acre-ft holding basin, an air flotation unit ca-
pable of removing 60 percent of the suspended solids, and a chlorina-
tion facility.
The minimum annual cost associated with a system that provides for
complete separation of sanitary sewage and storm water runoff is
$7. 04 million, and it too consists of separate treatment facilities in
the Separated Area and the Combined Area. This system is the same
in the Separated Area as previously described for the system employing
combined sewers and consists in the Combined Area of a new storm wa-
ter conveyance network, a 570 acre-ft surface reservoir, an air flota-
tion facility to remove 30 percent of the suspended solids, and a chlori-
nation station with the treatment facilities located across the River at
the Sacramento Port location.
It should be noted that a substantial portion of the total annual costs
for the acceptably performing systems utilizing combined sewers re-
sult from the enlargement or augmentation of the existing sewers to
provide adequate hydraulic capacity in the conveyance lines. For the
system utilizing combined sewers, for example, augmentation of the
existing conveyance system would cost $3. 10 million, or nearly one
half of the total system cost. The system embodying complete separa-
tion of sanitary and storm water flows requires, however, an annual
expenditure of $0. 52 million for enlargement of the existing sewers,
whereas the remaining portion of the $3. 68 million for total conveyance
provisions is necessary for new separated storm water sewer construc-
tion, operation, and maintenance in the Combined Area.
173
-------
Table 31
ACCEPTABLY PERFORMING SYSTEMS FOR CONTROL OF
STORM WATER RUNOFF AND COMBINED SEWER OVERFLOWS
FROM STUDY AREA
Sewer
Type
Combined
Separated
Service
Area
Combined
Separated
Study
Combined
Separated
Study
#
Facilities Description
890 acre-ft pond, 60% air flotation, Sacramento Port
950 acre-ft pond, 60% air flotation, South Sacramento
2, 600 acre-ft pond, sewage treatment plant, Sacramento Port
2,600 acre-ft pond, sewage treatment plant. South Sacramento
8, 400 acre-ft stabilization pond, Sacramento Port
8,400 acre-ft stabilization pond, South Sacramento
280 acre-ft pond, 30% air flotation, American River Park
420 acre-ft pond, 60% air flotation, American River Park
810 acre-ft stabilization pond, American River Park
1,500 acre-ft pond, 60% air flotation, Sacramento Port
1,900 acre-ft pond, 60% air flotation, South Sacramento
4, 800 acre-ft pond, sewage treatment plant, Sacramento Port
4, 800 acre-ft pond, sewage treatment plant. South Sacramento
570 acre-ft pond, 30% air flotation, Sacramento Port
770 acre-ft pond, 30% air flotation, South Sacramento
640 acre-ft pond, 30% mechanical screens, Sacramento Port
940 acre-ft pond, 30% mechanical screens, South Sacramento
940 acre-ft pond, 60% air flotation, Sacramento Port
1,200 acre-ft pond, 60% air flotation. South Sacramento
1,400 acre-ft pond, sewage treatment plant, Sacramento Port
1,400 acre-ft pond, sewage treatment plant, South Sacramento
3,700 acre-ft stabilization pond, Sacramento Port
3,700 acre-ft stabilization pond. South Sacramento
280 acre-ft pond, 30% air flotation, American River Park
420 acre-ft pond, 60% air flotation, American River Park
810 acre-ft stabilization pond, American River Park
800 acre-ft pond, 30% air flotation, Sacramento Port
1,000 acre-ft pond, 30% air flotation, South Sacramento
900 acre-ft pond, 30% mechanical screens, Sacramento Port
1,000 acre-ft pond, 30% mechanical screens, South Sacramento
1,000 acre-ft pond, 60% air flotation, Sacramento Port
1,200 acre-ft pond, 60% air flotation, South Sacramento
2, 300 acre-ft pond, sewage treatment plant, Sacramento Port
2, 300 acre-ft pond, sewage treatment plant, South Sacramento
Annual Cost,
million dollar s
Sub-
system
4.84
6.27
5.78
6.96
6. 01
7. 33
2. 10
2. 21
2. 23
4.94
6. 37
5.09
6.46
5. 22
6. 58
5.65
6. 83
5. 29
6.60
2. 10
2.21
2. 23
System
7.48
9. 27
7.21
8.74
7. 32
8.93
7. 51
9.17
7.71
9. 35
6. 32
7.68
All ponds are surface ponds.
174
-------
Not only does the combined system provide a less costly system than
the totally separated system but it also produces less overall degrada-
tion of the receiving waters, albeit small. The water quality of the
Sacramento River resulting from the discharge of treated wet weather
combined sewage from the Combined Area, which represents the ma-
jor portion of the total wastewater discharge from the Study Area, by
the least costly water pollution abatement system is shown in Table
32, which also presents similar data for the totally separated system.
Table 32
COMPARISON OF RECEIVING WATER QUALITY CHARACTERISTICS
FROM THE LEAST COSTLY ACCEPTABLY PERFORMING
COMBINED AND .SEPARATED SEWER SYSTEMS
Year 1992
Receiving
Water Quality
Parameter
Average Value
Maximum Value
Value exceeded less
than 12 hr/yr
Value exceeded
only twice annually
Combined Sewer
System
BOD, Suspended
mg/1 Solids, *
mg/1
Separated Sewer
System
2, 15
7. 05
4.5
4.8
0. 045
5.70
2.6
3. 1
BOD;
mg/1
2. 12
7.95
4.4
5.4
Suspended
Solids, *
mg/1
0.046
10.5
4.3
6.1
Incremental addition
FINANCING OPPORTUNITIES
The availability of financing sources and methods differs for the con-
struction of the combined sewer system and the separated sewer sys-
tem, as shown in Table 33. The values listed in Table 33 indicate the
maximum funding eligibility under existing laws, and not necessarily
the amounts that would actually become available. Also, the actual
funds approved by the Federal Government or State determine the
amount of local matching funds required, and amy influence the choice
of local funding methods.
175
-------
Table 33
MAXIMUM FUNDING ELIGIBILITIES FOR COMBINED SEWAGE
AND STORM WATER RUNOFF WATER POLLUTION
ABATEMENT SYSTEMS
System
Combined Sewer
Conveyance Subsystem
Augment Storm Sewers
Augment Combined Sewers
Storage Subsystem
Separated Storm Water
Combined Sewage
Treatment Subsystem
Separated Storm Water
Combined Sewage
Disposal Subsystem
Separated Storm Water
Combined Sewage
Totals
Separated Sewer
Conveyance Subsystem
New Storm Sewers
Augment Storm Sewers
Augment Sanitary Sewers
Storage Subsystem
Separated Area
Combined Area
Treatment Subsystem
Separated Area
Combined Area
Disposal Subsystem
Separated Area
Combined Area
Totals
Funding Source
and Method*
1
2
3
4
5
6
3
7
5
6
3
7
5
6
3
1
1
2
3
4
4
7
7
7
7
Funding Eligibility,
%
Federal
100
50
100
60
100
60
100
60
100
100
50
100
100
100
100
100
100
State
25
25
25
Local
50
15
15
15
50
Construction Cost
Contribution,
million dollars
Federal
8.02
21. 88
17. 37
5.73
1. 24
3. 00
0. 30
0. 38
57.92
53. 31
8. 02
0. 24
17. 37
8.75
1. 24
3.01
0. 30
0. 67
92.91
State
2. 39
1. 25
0. 16
3.80
0.00
Local
21. 88
1. 43
0.75
0. 10
24. 16
0. 24
0. 24
1 WP&FP Act PL83-566, PL89-337, PL89-4, PL87-703
2 HUD Act 1965 PL89-117
3 General Obligation and/or Revenue Bonds
4 WP8.FP Act PL83-566
5 FWPC Act PL84-660
6 Senate Bill 647
7 WPfcFP Act PL83-566, PL89-337, PL89-4
176
-------
SYSTEM SELECTION
The final selection of the system, 'which within the constraints best
satisfies all requirements imposed upon the performance, cost,
acceptance, implementation, operation, and maintenance of facilities
for the abatement of water pollution from storm water runoff and com-
bined sewer overflows in the Sacramento area, can be performed only
after a much, greater local involvement and commitment than was re-
quired and provided in this program. On the basis of the information
and evaluations developed and presented herein, however, a system
can be recommended for selection by the City of Sacramento,,
Although the least costly, acceptably performing system is character-
ized by the retention and augmentation of existing combined sewers in
the Combined Area, a system which provides for the complete separa-
tion of sanitary sewage and storm water runoff is only slightly more ex-
pensive but presents a much greater opportunity for extramural fund-
ing support from the Federal Government. Under maximum subsidy,
the financial commitment by the local community would be only about
0. 25 percent, or $240, 000, of the total construction cost of $93. 15
million for this system. Minimum local financial participation in the
less costly combined sewer system would be about 28 percent of the
total construction cost of $85. 88 million, or $24. 16 million. On an
annualized basis, the separated sewer system is only 1. 4 percent
more costly than the combined sewer system.
The recommended system, therefore, that will protect the receiving
waters from the discharge of storm water runoff and combined sewer
overflows from the Study Area involves the complete separation of sani-
tary sewage and storm flows and provides for separate conveyance and
treatment systems in the Combined Area and the Separated Area. The
Combined Area system would be comprised of a new gravity sewer sys-
tem for the collection and conveyance of storm water runoff from the
Combined Area to a treatment facility at the Sacramento Port location.
This treatment facility would consist of a 570 acre-ft surface reservoir,
a dissolved air flotation unit capable of reducing total suspended solids
by 30 percent and total BOD by 21 percent, and a chlorination station.
Sanitary sewage from the Study Area would be collected and conveyed
to the existing sewage treatment plant by an augmented existing com-
bined sewer system.
In the Separated Area, the system would consist of an augmented exist-
ing storm water runoff collection network and a new interceptor sewer
for conveyance of the storm water runoff to a common treatment faci-
lity located at American River Park. Treatment facilities there would
consist of a 280 acre-ft surface holding pond, a dissolved air flotation
unit for removal of 30 percent of the total suspended solids and 21 per-
cent of the total BOD, and a chlorination station.
177
-------
Section IX
ACKNOWLEDGMENTS
This program was performed by the Envirogenics Company, a Divi-
sion of Aerojet-General Corporation, El Monte, California, under
the direction of Messrs. J. C. Merrell, Jr. , Project Officer,
W. A. Rosenkranz, G. A. Kirkpatrick, and D. R. Wright of the
Federal Water Quality Administration. Envirogenics Company per-
sonnel participating in the program were Dr. D. L. Feuerstein, Pro-
gram Manager, Mr. R. W. King, Mr. A. Grimm, Mr. F. M. Russel,
Mr. G. A. Purrington, Mr. E. J. Curtin, Mr. B. Putt, Mrs. G. M.
Hill, and Mrs. M. D. Robinson. Technical consultation was provided
by Dr. A. L. Gram and Mr. D. F. Phillips of Molina Engineering Con-
sultants, Inc. , Pasadena, California.
The collection of storm water runoff and combined sewage samples in
the Study Area was conducted by PMT Associates, Sacramento, Cali-
fornia and the analyses of wastewater samples were performed by
Morse Laboratories, Sacramento, California.
The conduct of the program would have been extremely difficult without
the full cooperation and helpful assistance provided by the City of Sacra-
mento. While many persons contributed to the study the following are
deserving of special acknowledgment: Mr. E. A. Fairbairn, City
Manager (retired); Mr. R. L. Rathfon, City Manager; Mr. J. C.
Jennings, City Engineer; Mr. R. H0 Parker, Assistant City Engineer;
Mr. R. W. Jones, Manager, Division of Water and Sewers; Mr. H. G.
Behrens, Assistant Manager, Director of Water and Sewers, Mr. J0 A.
Avena, Planning Director and Mr. G. E. Vincent, Principal Planner.
A number of agencies in Sacramento furnished data and information
used in the study. They include the City Redevelopment Agency, the
County Department of Public Works, the County Planning Department,
the Capital Building and Planning Commission, and the City-County
Chamber of Commerce.
Appreciation is expressed to Messrs. P. H. Mook and E. D. Kania of
SWECO, Inc. , for preliminary information provided on mechanical
screening processes.
179
-------
Section X
REFERENCES
I, "A Preliminary Appraisal of the Pollution Effects of Storm
Water and Overflows from Combined Sewer Systems. "
USPHS (1965).
20 "Problems of Combined Sewer Facilities and Overflows. "
FWPCA, WP-20-11 (1967).
30 "Water Pollution Aspects of Urban Runoff." FWPCA, WP-20-
15 (1969).
4. "Operating Data 1966-67, Division of Water and Sewers." City
of Sacramento, California.
5, "Water Quality Control Policy for Sacramento-San Joaquin
Delta," California State Water Resources Control
Board (1967).
6. "Water Quality Records in California. " US Geological Survey
(1964, 1965, and 1966).
7. "Pollution Assimilation Capacity of the Lower Sacramento
River. " Hydroscience, Inc. (April 1964).
8. "Expansion of Wastewater Treatment Facilities for the City
of Sacramento. " Dewante and Stowell, Sanitary and
Civil Engineers (October 1966).
9. "San Francisco Bay Delta Water Quality Control Program. "
Kaiser Engineers, et al. (March 1969).
10. "Characterization and Treatment of Combined Sewer Over-
flows. " Engineering-Science, Inc. (November 1967).
11. "County-wide Hydrologic Investigation, Sacramento County,
California.. " George A. Nolte Consulting Civil
Engineers, Inc. (July 1961).
12. Weibel, S, R, , R. J. Anderson, and R. L0 Woodward.
"Urban Land Runoff as a Factor in Stream Pollution. "
J. Water Poll., Control Fed. 36, 7 (July 1964).
130 Combined Sewer Separation Using Pressure Sewers, "FWPCA,
ORD-4 (October 1969).
181
-------
Section XI
APPENDICES
Appendix Page
A0 Dry-weather Combined Flow Characteristics 184
B. Wet-weather Combined Flow Characteristics 188
183
-------
Appendix A
DRY-WEATHER COMBINED FLOW CHARACTERISTICS
£
2
£
0
•"
3
-M
&
g
H
Run No. 1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 May 69
0912
0905
0900
0958
0950
1008
0945
0940
0940
0955
1005
1015
0925
0900
0850
0910
*j
_£-
«
Q
?
o
E
§
13
to
E
..
•Jo
g
a
S
g,
£
^
o
E
•o
4}
T3
C "*"
»~^x
IB
to -
0)
o "~*
H to
4. 95
1.28
3.58
1. 60
2.05
0. 10
0.25
2.02
1.80
0.82
0. 70
1. 35
3.4
0.35
0.36
0.75
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
68.6
11. 6
98.0
16.5
2.30
0. 19
0. 2
58.8
41.8
4. 2
1.4
8.0
69.6
0. 3
0.4
4.9
46
66
314
86
178
101
275
148
137
88
20. 5
370
24
206
260
167
•a
1
V
p, ^
w
3
49
200
59
41
81
122
108
46
50
2. 0
301
18
154
72
147
00
E
o>
-o
O
CO
5
ri
V
"to
to
00
g
Q"
o
00
g
tf
o
0
6
23
270
86
18
30
263
98
77
41
0
50
20
133
233
167
57
80
113
180
209
250
195
168
27
132
53
83
121
176
188
25
196
137
200
328
279
186
510
225
10
200
69
510
127
426
456
622
tfi
cu
7.9
7.4
7.4
7.5
7.8
7.5
8.2
7.7
7. 7
7. 3
7.5
7.4
7.6
7.4
7.8
7.6
o
g
O
3
"o
u
0) h
h 0
1.6 x 10?
4. 2 x 10°
2. 1 x 10,
2. 0 x 10,
1.8 x 10,
1. 1 x 10,
2. 9 x 10,
4.0 x 10°
1.4x10°
9. 0 x 10?
2.2x10°
6. 0 x 10°
1.4 x 10,
2.0 x 10,
2. 9 x 10 '
7.5 x 10*
Run No. 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 May 69
1106
1135
1131
1217
1203
1212
1130
1125
1149
1135
1145
1150
1120
1105
1055
1110
6. 80
2.83
6. 08
2.65
2.85
0. 15
0. 25
2.07
2. 10
0 77
0.75
1.40
5.25
0.40
0. 41
0. 85
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
66. 2
57.4
238.0
41.0
40.4
0.28
0. 2
61.5
56.5
3. 0
1.8
8.4
70. 0
0.4
0.6
6. 1
30
50
190
52
50
75
109
192
58
111
25
424
32
143
177
50
21
45
187
32
6
58
56
119
12
39
14
348
12
92
100
0
21
56
176
42
32
53
87
172
51
80
25
393
30
142
167
2
56
124
153
110
160
150
128
180
15
250
43
180
64
260
98
200
157
211
132
235
216
294
216
446
29
216
78
661
118
333
421
573
7.5
7. 5
7.5
7.6
7. 7
7.6
7.7
7.4
7. 9
7. 2
7.8
7. 3
7.5
7.9
7.5
7.2
1.8 x 10]
4.0 x 10,
3. 0 x 10!
9. 0 x 10?
2.7 x 10?
7.0 x 10°
1. 1 x 10,
6. 0 x 10°
2.0 x 10,
2. 0 x 10,
1.8x10?
7.0 x 10°
1. 6 x 10,
8.0 x 10°
2. 0 x 10?
2. 0 x 10
Run No. 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 May 69
1301
1333
1329
1457
1351
1407
1330
1325
1344
1335
1345
1350
1314
1305
1255
1315
8. 10
3.68
6.88
3. 20
3.60
0.23
0.25
2.57
3.05
0.72
0. 80
1.35
6. 30
0. 30
0. 36
0. 85
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
72.8
90.0
278.0
55.0
56.7
0.5
0.2
94.5
113.7
2.6
2. 1
8. 0
79.5
0.2
0.4
6. 1
3,338
137
190
72
177
194
202
198
65
57
54
248
72
72
56
407
2, 536
0
167
51
114
177
119
146
25
47
34
176
19
47
48
338
3, 066
135
180
63
171
76
179
186
65
57
17
219
71
67
6
390
82
167
160
154
139
88
177
300
45
150
76
425
81
174
185
800
1, 648
135
200
152
200
431
274
426
5
78
152
730
93
230
200
588
6.6
7. 7
7.0
9.0
8.0
7.6
7. 3
7.6
7.6
7. 6
7.7
7. 5
7.8
7.5
7.6
7.5
1. 6 x 10
2. 9 x 10,
1. 4 x 10,
1. 2 x 10,
1. 0 x 10,
7.0 x 10°
1. 5 x 10,
2.3 x 10'
3. 0 x 10°
2. 5 x 10,
1.0 x 10,
1. 6 x 10,
1.7 x 10,
1.5 x 10,
1.4 x 10,
2. 1 x 10'
184
-------
Appendix A (continued)
DRY-WEATHER COMBINED FLOW CHARACTERISTICS
M
JD
B
2
B
o
•r«
3
to
0)
A
Q
Q)
1
H
a
i
Q
|
S
.3
3
.2
t-t
<0
ID
1
s)
.S-
ft
m
u
|
b.
•a
o
§ -5
p, OO
w -
f_4 0)
0 'o'
E-i w
•a
4)
C
«
Run No. 4
I
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 May 69
1458
1523
1519
1551
1547
1535
1525
1520
1535
1530
1545
1550
1513
1500
1450
1510
8.20
3.78
7.03
3.40
3.81
0.20
0.40
2.62
3.20
0.72
0.80
i: 30
6.50
0.40
0. 36
0.90
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
68.4
99. 0
285.0
59.7
60.5
0.42
0.4
97.8
124.0
2.6
2. 1
7.2
64.4
0.4
0.4
6.8
9,274
22
150
8
35
31
136
420
55
28
44
271
322
89
140
365
0
14
133
0
12
8
109
378
32
9
28
230
309
80
105
239
00
S
tn o
9, 065
22
135
6
3
31
129
307
17
5
30
235
315
43
41
327
186
153
178
113
203
205
280
550
34
216
74
375
68
175
300
138
2, 704
235
299
157
191
382
309
578
34
83
74
696
88
274
358
583
6.8
7.5
7.5
7.3
7. 2
7.7
7.4
7.3
7.5
7.4
7.8
7.4
7. 5
7.3
7.5
7.4
1.6 x 10®
2. 3 x 10,
2.4 x 10,
1.6 x 10,
1.4 x 10,
1.3 x 10,
1. 6 x 10,
9.0 x 10?
1.6 x 10,
2. 0 x lo!
3.0 x 10^
4. 0 x 10°
1.8 x 10,
1.4 x 10,
5.0 x 10?
6.8 x 10
Run No. 5
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 May 69
1700
J726
1721
1754
1751
1740
1725
1720
1740
1735
1745
1755
1715
1700
1655
1710
8. 15
3. 73
6.90
3.35
3.75
0. 20
0.35
2.57
2.95
0. 67
0.80
1.30
6.40
0. 35
0.41
0. 80
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
66.2
97.0
278.0
58.8
59.5
0.42
0.3
74.5
106.5
2.3
2. 1
7.2
78.5
0.3
0.6
5.5
142
631
51
124
107
60
83
122
17
32
1
209
53
166
37
327
119
185
0
118
107
60
63
97
11
14
0
174
42
77
23
182
81
617
17
107
48
21
83
122
14
13
1
152
41
166
15
259
38
185
189
54
170
209
190
128
34
125
64
150
193
194
195
168
201
382
1, 132
397
456
764
255
417
59
132
34
505
137
402
211
627
7.4
7.2
7.5
7.5
7.7
9. 1
7.4
7.5
7.8
8. 0
7.5
7.5
7.5
7.6
7.6
7. 5
1.4x10?
2.8 x 10,
1.3 x 10,
7.0 x 10,
1.0 x 10,
1.5x10'
6.0 x 10,
1, 1 x 10'
2.0 x 10,
1.0 x 10!
2.3x10°
9. 0 x 10,
1.8 x 10,
1. 6 x 10,
1.4 x 10,
2.0 x 10
Run No. 6
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 May 69
1901
1921
1918
1947
1942
1940
1925
1930
1933
1930
1945
1950
1912
1900
1855
J9IO
8.05
3. 68
6.88
3.20
3.55
0. 05
0. 25
2.47
3.00
0. 67
0.80
1.30
6.30
0.35
0. 36
0.85
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
66.3
90.0
278.0
55.0
55.8
0.07
0.2
69.0
111.0
2.3
2. 1
7.2
80.5
0.4
0.4
6. 1
969
56
271
71
8
193
86
199
27
156
4
144
100
126
69
179
815
16
260
59
0
0
0
143
17
0
4
110
54
109
60
46
890
49
267
15
8
168
66
195
15
35
1
100
100
57
72
148
380
64
198
90
105
171
216
118
178
151
45
181
122
165
209
225
672
122
98
181
157
397
240
265
34
142
25
220
118
172
294
397
7.2
7. 2
7. 3
7.4
7.4
7.6
7.4
7.4
7.5
7.5
7.4
7.4
7.3
7.5
7. 5
7.4
1.4 x 107
4.0xl06
9. 0 x 10?
8.0 x 10°
1.7x10;
4. 9 x 10,
1.0 x 10,
1. 0 x lO.f
2.5x10°
4. 0 x 10°
4.4x10=
3.0 x 10,
4.0 x 10!
7. 0 x 10°
1. 6 x 10,
1. 6 x 10
185
-------
Appendix A (continued)
DRY-WEATHER COMBINED FLOW CHARACTERISTICS
h
E
3
z
c
o
*J
to
2
a
Q
o
E
•o
•a
c °~
en" £
CD
33
E-i to
-o
•o
Si
E"
CO
'o
m
V
V
-^
to
-^
bo
g
Q"
O
n
•^
bo
g
Q
O
O
ffi
P.
_
(0
g
H
O
"^
G
O to
h o
Run No. 7
1
2
3
4
5
6
7
8
9
10
1 )
12
13
14
15
16
14 May 69
2100
2130
2125
2159
2155
2143
2132
2127
2142
2120
2150
2155
2115
2055
2045
2105
8. 00
3. 53
6. 78
3. 10
3. 40
0. 02
0. 31
2. 57
2.40
0.72
0. 85
1. 45
6. 30
0. 45
0.51
0. 95
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
70. 6
87. 5
274. 0
52.5
52.6
0.03
0.3
94. 5
73.4
2. 6
2.3
8. 9
80.5
0.5
0.9
7. 5
49
612
64
134
527
41
93
51
68
35
16
186
98
206
89
119
0
604
0
5
404
0
55
0
18
14
0
175
41
149
5
36
25
572
43
118
506
18
88
41
67
72
6
35
75
190
80
57
193
295
169
626
158
74
105
178
46
135
28
310
200
750
209
311
172
284
169
338
421
142
235
309
14
221
34
480
113
1,882
225
451
7.4
7. 5
7. 3
7. 9
7.8
7. 5
7.4
7.2
7.5
7.4
7.2
7. 1
7.4
7.0
7.4
7.2
1.0 x 101
6.0 x 10?
8. 0 x 10,
1.4 x 10,
1.2xl06
5.7 x 10°
1.4x10^
2.0 x 10°
7.5 x 10,
2.4 x 10'
4. 4 x 10,
1. 6 x 10,
1. 2 x 10,
1.5 x 10,
2.0 x 10'
3.0 A 10
Run No. 8
,
2
3
4
5
6
7
K
9
10
11
12
13
14
15
14 May 69
2300
2330
2326
2358
2354
2328
2323
2318
2344
2309
7.80
3. 33
0. 58
2. 90
3. 20
0. 04
0 29
2. 46
2 70
0 74
; 2335 i 0. 76
1 2343 1.37
23'9 6 10
16
Run
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
No. 9
15 May 69
,^250
2145
2300
0100
0121
0117
0155
0150
0133
0123
0118
0138
0110
0140
0146
0113
0050
0045
0059
0. 48
0. 46
0 95
7. 40
2.93
6. 18
2. 10
2. 70
0. 03
0. 31
2. 17
8. 10
0. 63
0. 78
1. 27
5. 60
0.42
0. 43
0. 82
60
114
108
60
60
10
56
103
84
42
30
45
60
24
45
24
70. 6
78.5
269.0
47. 5
48.5
0. 06
0 2
86. 8
93. 0
2.8
1. 90
8. 0
70 2
0. 6
0.7
7. 5
52
93
50
91
152
147
117
66
111
80
53
142
352
50
97
161
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
70 6
62.0
244. 0
27. 5
37. 1
0 045
0. 3
66.8
56.5
2. 0
1.96
7.0
73.5
0. 5
0. 2
5. 8
210
109
529
95
40
144
18
146
110
71
36
174
81
37
108
66
20
67
38
57
131
45
53
61
56
38
22
123
134
49
51
719
169
61
499
36
31
101
0
90
21
32
8
24
81
20
39
64
52
81
40
60
83
39
109
61
105
74
47
121
352
43
81
139
140
133
196
163
38
150
70
215
26
700
33
61
75
163
203
225
188
86
481
82
25
135
14
47
96
66
36
159
81
31
94
63
186
146
250
130
73
22
51
200
40
53
214
205
78
123
185
226
75
216
176
75
400
428
66
230
28
56
19
38
66
66
169
235
207
113
197
85
56
24
14
141
28
28
9
165
66
47
47
183
7. 4
7. 3
7. 0
7. 0
7. 2
7.2
7. 2
7. 0
7. 4
7. 2
7. 3
6. 6
7. 2
7. 2
7. 1
6.8
7. 1
6.7
6.9
7. 1
7. 0
7. 2
7.4
6. 7
7.2
7. 3
7. 1
7. 0
7.2
7. 1
7. 2
6. 6
4.0 x 10
6. 0 x 10,
6.0 x 10,
4. 0 x 10,
3.0 x 10,
1. 4 x 10,
4. 0 ^ 10'
1. 0 x 10°
1. 6 x 10,
8. 0 x 10,
5. 0 x 10,
4. 0 x 10,
4. 0 x 10-,
1. 6 x 10,
2. 0 x 10'
1.9x10
4. 0 x 10^
4. 0 x 10,
4. 0 ^ 10,
6. 5 x 10,
1. 6 x 10,
1. 0 x 10'
8.0 x 10,
1.6 x 10,
1.4 x 10,
1.2 x 10(
9. 2 x 10,
4.0 x 10,
3.9 x 10,
2. 0 x 10,
1.0 x 10'
1. 6 x 10°
186
-------
Appendix A (continued)
DRY-WEATHER COMBINED FLOW CHARACTERISTICS
H
0)
|
2
8
3
S5
0)
13
Q
1
£
*J
jj
CU
Q
fa
e
o
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5
£
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a
3
g.
£
at
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cn
00
e
CO
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.a
a
65. 0
9.0
136.5
9.4
18. 1
0. 05
0.2
35.3
15.4
1.8
1.4
4.5
75.5
0.4
0. 6
3. 9
33, 256
132
83
28
90
23
123
104
235
34
53
200
207
182
55
21
Run No. 12
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
15 May 69
0654
0706
0704
0730
0726
0733
0723
0720
0717
0712
0742
0750
0700
0655
0645
0730
4.5
0. 73
3.28
1. 30
1.80
0. 08
0. 35
1. 63
1. 00
0.75
0.79
1.05
2.7
0. 43
0. 43
0.68
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
70.2
3.6
84. 6
11.0
18. 1
0. 12
0.3
37.3
12.7
2.9
2.0
4.8
49. 2
0.4
0.2
3.3
53
73
457
309
195
123
190
46
79
48
80
116
108
231
8
40
28, 684
87
60
25
36
0
74
0
20
21
18
170
134
77
28
20
32, 346
119
76
27
86
23
112
100
2x2
24
15
190
169
176
50
9
1300
130
110
165
57
50
66
210
22
203
78
135
68
155
124
169
21
41
350
159
63
81
187
40
21
36
30
66
41
136
8
37
52
65
419
253
187
106
65
0
56
42
20
101
105
211
4
25
83
168
168
180
130
211
168
185
30
170
35
105
73
78
54
32
4, 080
99
150
132
94
38
28
127
28
28
19
191
132
47
24
122
47
68
437
310
94
179
113
118
19
132
28
94
56
89
47
66
5.6
6. 9
7. 0
6.8
7.2
7.2
7.3
7. 0
7.2
7. 1
7. 1
7. 0
7.0
7.2
7. 2
7.2
3.0 x 10
3.0 x 10,
2.0 x 10,
5.0 x 10,
3. 2 x 10,
2.0 x 10,
1.3 x 10,
2.6x10^
1.4 x 10°
5.6 x 10?
3. 1 x 10^
4. 2 x 10,
8. 0 x 10,
4. 0 x 10,
1. 5 x 10,
6. 0 x 10
7. 2
7.2
6. 5
7.0
7. 1
7.2
7.4
7. 2
7.6
6.9
7.4
7. 0
7.3
7. 5
7.5
7.2
6.0 x lol
8.0 x 10,
1.7 x 10,
4.0 x 10,
3.4 x 10,
1. 6 x 10'
1.6 x 106
4.5 x 10^
6.4 x 10,
2. 7 x I0l
2. 6 x 10?
2.0 x 10,
6. 0 x 10,
1.4 x 10,
4. 0 x 10,
1. 0 x 10
187
-------
Appendix B
WET-WEATHER COMBINED FLOW CHARACTERISTICS
A
z
B
O
rt
to
"rt
Q
CJ
£
H
Run No. 1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
10 Dec 68
1103
1130
1 130
1115
1151
1150
1205
1055
1139
1057
1114
1118
1200
1129
1145
«
jf
g.
Q
o
E
c
o
rt
e
u
Q
a
£
5. 4
4. 48
3. 3
3. 9
0. 6
1. 75
3. 97
4. 5
0. 8
1. 5
3. 1
0.4
0.4
0. 7
60
108
60
60
10
56
108
84
42
30
45
60
24
45
24
0}
"•H
U
>
O
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ra -
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•3 i^
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1
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£
CO
O
CO
JD
a
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?
65. 0
153. 0
57. 6
62. 2
2.2
13.4
218. 0
217. 0
2. 05
9.4
61.0
0. 4
0. 6
4.3
2,764
288
484
99
296
227
584
317
81
104
27,490
84
53
208
2, 503
202
344
99
186
164
164
196
58
91
19, 988
84
4
208
2, 719
261
361
94
148
28
404
294
81
95
27, 490
26
0
70
171
161
133
121
145
74
134
119
127
195
3650
120
113
293
00
£
tf
o
o
3, 360
506
364
300
460
387
152
316
654
866
35, 000
229
224
641
£
P<
6. 1
6.7
8. 25
6. 85
6.8
6. 9
7. 2
6.4
7. 05
6. 65
5. 6
6.85
6.55
6.9
_
£
M
O
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U
u """"
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[*4 O
2. 0 x 10
8. 0 x 10?
2. 6 x 10°
2.4 x 10
6
2.4 x 10?
2. 4 x 10?
4. 4 x 10?
2.5x10°
5.4 x 10?
3.7 x 10°
1.3 x 10?
2. 0 x 10?
2. 0 x 10?
9. 0 x 10
Run No. 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
10 Dec 68
1445
1524
1500
1445
1525
1515
1530
1430
1515
1423
1435
1505
1530
1442
1500
7.5
5. 48
5. 0
5.8
0. 2
1. 75
3. 67
6.4
1. 5
1. 3
2. 5
5.0
0. 6
1. 1
0. 9
60
108
60
60
10
56
108
84
42
30
45
60
24
45
24
44. 0
200.0
73. 0
92.0
0.4
13.4
188.0
814. 0
10. 5
4.9
22. 0
85. 0
0.9
4.7
6.8
1, 087
354
44
115
197
47
282
270
45
136
5, 022
2, 280
350
1, 379
832
226
35
38
144
26
93
132
28
136
1, 926
720
247
1, 300
783
315
44
95
144
0
197
242
35
53
4, 749
1,768
315
500
140
119
97
110
105
197
74
130
84
142
274
130
62
245
1, 100
200
134
139
134
234
174
168
100
259
4, 140
105
165
695
6. 6
7. 3
7.45
6. 85
7. 10
7. 05
8. 95
6.75
6.95
7. 05
6. 15
10. 1
6. 65
6. 6
1. 6 x 107
3.0 x lo|?
4. 4 x 10°
9. 0 x 10
/•
2. 1 x 10?
2.6 x 10?
2.0 x 10°
2.4 x 10°
2.5 x 10?
2.4 x 10°
6.5 x 10°
1. 0 x 10
2. 1 x 10^
1.4 x 10
Run No. 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
11 Dec 68
0855
0915
1025
1015
0926
1035
1045
0955
0915
0845
0857
0907
0840
0908
0910
4. 2
3. 28
1 . 1
1 8
0 1
0 03
7. 87
2. k
1. 7
0. 7
1. 3
2. 6
0. 4
0. 3
0
60
108
60
60
10
56
108
84
42
30
45
60
24
45
24
67. 0
84. 5
7. 9
18. 1
0 2
0 02
51. 6
85.7
6. 1
1. 6
7.3
47. 2
0.4
0. 3
0
200
28
160
62
2, 176
230
54
88
1, 257
2, 207
169
22
12
200
28
160
62
790
60
54
88
665
298
169
22
6
200
22
116
52
2, 165
119
43
63
1, 250
1, 924
21
22
5
158
137
185
161
240
171
119
168
125
152
165
223
103
174
238
127
470
228
337
291
56
227
63
278
844
405
232
167
7. 7
7. 35
9. 65
8.45
8. 35
7. 3
7. 38
7. 4
7. 65
7. 2
6. 9
7. 65
8.8
7.25
5.0 x 10°
7.5 ^ 10^
1. 4 x lo'
1 2 x 10°
3. 0 x 10^
6. 6 x 10.
9.5 x 10,
9. 0 x. lo'
4. 0 x 10?
1. 5 x 10b
2. 1 x 10°
2.4 ^ 10b
6.0 x 105
1. 0 x 105
-------
Appendix B (continued)
WET-WEATHER COMBINED FLOW CHARACTERISTICS
M
Q)
a
g
1
g
o
• r4
to
V
d
Q
I
f-1
*
1
q
>
1
S
B
o
3
0)
.S
m
g*
0)
T)
• r-t
'o
w
u
m
4>
a
to
«,
bo
g
q-
o
n
*v
M
g
O
O
£
P.
I
o
3
o
rt-s
fa o
Run No. 1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
13 Dec 68
1900
1935
2010
2000
1952
1947
1942
20Z5
1932
19Q4
1916
1920
1930
1945
1910
6.6
1.28
3.3
3.7
0.0167
0.55
Z. 87
5.0
1.5
0.9
1.25
4.70
0. 60
0.81
0.90
60
108
60
60
10
56
108
84
42
30
45
60
24
45
24
50.5
126.5
56.5
58.6
>0
133.0
117.0
252
10.5
2.6
6.65
93.2
0.95
2.53
6.80
164
4,485
1,804
592
103
216
806
48
35
86
2,822
590
61
106
164
4,264
1,268
506
73
173
328
40
35
83
2,603
590
61
106
164
4,397
1,550
592
63
159
714
48
25
86
2,416
590
37
106
190
5950
765
175
195
193
125
143
108
238
1983
175
150
185
284
3,800
9,540
370
330
380
240
248
140
380
5, 610
440
294
367
7. 1
6.9
6.0
7.0
7.0
6.95
7.4
6.5
7. 1
7.0
6.0
6.8
6.8
7.0
1.0 x 107
1.0 x 10®
3.7 x 10,
4. 9 x 10
2.0 x 10,
3. 0 x 10,
2.0 x 10,
4. 8 x 10'
7.0x10?
1.7 x 10*
8. 0 x 10°
1. 0 x 10,
1.5 x 10?
1.6 x 106
Run No, 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
13 Dec 68
2155
2220
2245
2300
2243
2232
2229
2310
2217
2158
2209
2210
2220
2228
2200
7.0
6. 18
5. 9
6.6
0. 0167
2. 95
4.77
7.5
2. 3
1. 10
2.35
4. 70
1. 00
1.41
1.00
60
108
60
60
10
56
108
84
42
30
45
60
24
45
24
50. 5
245
71.0
65.0
>0
32.2
291
320. 0
22. 0
3.70
20.2
93.2
2.43
7.55
8. 18
249
152
1,502
169
79
53
466
138
126
282
1, 666
28
16
265
123
130
550
109
79
53
75
31
30
235
18
16
265
220
135
1, 063
169
67
53
388
123
125
107
1, 310
28
15
186
177
210
3008
135
138
160
2ZO
150
130
215
239.8
103
110
335
276
180
2,410
164
124
146
196
94
96
320
2, 500
42
58
559
7. 0
7. 0
6. 6
7. 0
7.2
6.9
7.2
7.4
7.3
7. 1
6.6
7.0
7.0
6.9
2.0 x. 10
Z.OxlO*
5. 2 x 10!
8.0 x 10
1.8 x 101
8. 6 x 10
f
3. 0 x 10,
2. 6 x 10,
2. 2 x 10'
1.3x10°
7.6x10*
3. 0 x 10?
4.0 x 10
Run No. 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
14 Dec 68
0910
0930
0950
0955
1049
1042
0932
1005
0923
0905
0915
0925
0927
0936
0915
5.5
4. 18
1.40
2.80
0. 016
0. 35
2. 17
2. 70
0. 70
0. 60
1.35
3.70
0.40
0. 31
0.80
60
108
60
60
10
56
108
84
42
30
45
60
24
45
24
66.4
131.0
12. 6
39.3
>0
0.51
61.5
92.3
2.5
1. 2
7.8
78.0
0.43
0.35
5.5
95
153
105
150
94
30
344
208
4
319
433
41
139
53
46
153
105
150
94
30
63
71
4
208
256
35
40
46
79
141
105
150
83
28
325
178
0
306
47
137
53
191
204
218
279
195
328
184
188
150
174
393
135
125
150
55
216
266
242
151
431
74
168
28
158
1, 140
240
120
325
7. 7
7. 2
7.4
8.0
7.5
7. 2
7.5
7.5
7.7
7.4
7. 1
7.8
7.8
7. 3
1. 2 x 10
1. 0 x 10,
2.4 x 10'
1. 1 x 10*
6. 0 x 10
A
6.0 x 10,
1. 2 x 10',
4.0 x 10g
1. 3 x 10*
2.2*10'
5. 2 x. 10,
1.2 x 10,
1. 0 x 10,
4. 4 x 10,
6. 0 x 10
189
-------
Appendix B (continued)
WET-WEATHER COMBINED FLOW CHARACTERISTICS
4>
J3
a
2
g
o
+J
w
4J
5
Run No. 1
1
2
3
4
5
7
8
g
10
1 1
12
13
14
is
16
18 Jan 69
«
g
H
1600
1632
1628
7645
1705
1645
1634
1629
1720
1620
1556
161 1
1620
1648
1657
1670
a
£
o.
9
Q
?
o
c
o
*-J
a
5.8
5.53
6.48
5.3
6.4
3.55
4. 77
6. 9
3.07
1. 6
3. 35
3.7
1.20
2. 61
1. 0
a
.
o
V
g
$
o
•2*
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
CD
jj~
o
E
"8
"S •>•
£* p
w -
•3-0
*J ^3
H w>
•a
o
"a
B1^!
3 bO
to g
K
5 2
O *"*
>w
E
1
'o
in
4)
3
14
3
i
CO
66.6
186.0
250.0
74.5
138.0
>0
41.0
291.0
303.0
30.0
6.8
29.8
78.0
2.4
18.7
8.2
419
182
424
159
118
270
502
441
373
159
940
244
129
98
1, 137
88
61
306
65
28
178
311
66
288
83
698
123
44
22
803
380
165
419
91
108
204
480
84
364
114
867
235
110
82
1, 005
^1
no
a
o
M
275
192
178
202
164
335
241
474
723
200
497
383
142
150
682
-S?
00
Q"
O
O
144
163
114
169
101
479
513
127
87
50
836
139
86
37
1.566
E
a.
6.80
6.65
7. 10
6. 90
7.05
6.60
7.05
7.7
6.6
7.20
6.55
6. 70
6.95
7.80
7.00
.
§
1
o
U
si
« H
h o
- - ' "L
2.3 x 10?
2. 0 x 10?
4.0 x 10?
1.5 x 10?
1/8 x 10
6
7.5 x 10?
5.9 x 10?
2.7x10°
6. 0 x 10j
3. 0 x 10?
2. 6 x 10,
3. 0 x 10?
1.7 x 10°
7. 2 x 10,
1.8 x 10
Run No. 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
18 Jan 69
1905
1938
1933
1950
2000
1945
1936
1932
2010
1923
1906
1914
1925
1940
2000
1918
4.9
4. 13
5. 58
4.4
4.9
0
2.05
4. 12
6.6
1.57
0.8
2.95
3. 0
0.61
0.90
1.47
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
69.5
117.0
210. 0
78.6
70.0
0
17.8
233.0
310.0
11.9
2. 1
26.8
58.3
1.0
2.8
14.5
262
144
386
308
72
241
186
121
53
401
396
1, 057
73
33
191
70
41
137
0
35
162
186
23
28
54
250
587
42
19
119
206
110
371
241
61
206
111
100
34
375
346
893
70
28
138
332
112
367
307
109
230
258
422
186
260
784
2055
175
150
220
133
66
192
245
68
287
257
43
53
123
476
1, 310
71
41
298
6.40
6.55
7.40
6.30
6.95
6.35
6.75
6.50
6.65
6. 90
6.85
6.35
6.55
6. 50
6.65
3.6 x 10?
2. 8 x 10?
2.5x10°
7.4x10°
3.6 x 10
A
5.3x10°
1.6 x 10?
1.6 x 10?
4. 0 x 10?
2. 8 x 10?
5. 6 x 10?
7.0 x 10?
2.4 x 10°
4.0 x 10?
4. 8 x 10
Run No. 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
19 Jan 69
0845
0910
0907
0923
0930
0918
0910
0906
0938
0859
0840
0852
0900
0918
0928
0952
6.5
5.63
6.08
3.6
4. 1
0. 1
2. 15
4. 67
4.8
1. 27
1. 0
3.25
3.7
0.80
1. 09
1. 57
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
74.5
219.0
237. 0
66.7
56.8
0. 14
19.3
281. 0
235.0
8.0
3. 1
29.2
78.0
1.6
4. 1
15.6
227
77
80
106
70
34
82
66
865
59
72
2,096
203
64
42
52
42
33
26
34
35
30
37
26
48
26
22
2,056
0
28
8
35
143
64
56
102
64
22
78
44
660
59
59
2. 078
174
40
36
38
348
144
198
168
185
176
260
175
190
139
205
148
377
127
197
160
65
39
37
72
62
82
73
59
46
27
39
110
55
51
48
72
6.55
6.75
6.50
7. 60
6.60
6.75
6.95
7. 00
6. 20
6.55
6. 90
6.30
6.65
7.05
7. 00
6.95
9. 6 x 10^
5. 1 x 10?
4.0 x 10?
1.1 x 10°
1.6* 10,
4. 9 x 10?
5.9 x 10;?
8. 9 x 10?
5.9 x 10°
4.0 x 10°
2.0 x 10*
1.4x10?
1,7 x 10?
2. 6 x 10?
1.2x10°
1. 4 x 10
190
-------
Appendix B (continued)
WET-WEATHER COMBINED FLOW CHARACTERISTICS
h
<0
J3
3
a
0
1
to
CO
bo
E
CO
T)
"o
W
a
2
0)
w
».
00
E
cr
0
n
~-
00
E
3
u
E
o.
to
O
S-l
o
U
«"?
h 5
179
88
211
139
64
66
109
140
341
86
126
592
834
35
27
344
60
22
144
65
30
7
29
56
62
15
15
349
455
35
27
279
152
88
180
119
64
57
95
127
252
82
125
558
817
26
27
324
157
92
95
68
61
166
54
808
206
77
169
350
276
100
71
278
119
99
142
159
65
144
240
160
111
73
62
686
1, 230
91
39
500
7. 3
7.2
7.4
6.9
7.0
7.8
7.3
7.2
7. 1
7.5
7.6
7. 1
6.8
6.8
7. 5
6.9
2. 9 x 10?
3.8 x 10?
5.3 x 10?
5.6 x 10°
1.6 x 10°
1.6 x 10,
2. 3 x 10°
1. 9 x 10°
3.0 x 10?
1.4 x 10?
8.8 x 10,
1.2 x I Of,
3.2 x 10'
1.4 x 10,
2.5 x 10°
1.5 x 10
Ron No. 2
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
5 Feb 69
6 Feb 69
5 Feb 69
6 Feb 69
5 Feb 69
2317
2345
2340
2355
0005
0001
2350
2346
0015
2336
2323
2331
2335
2345
2353
2333
6. 10
4.43
5.38
4. 60
4.80
0. 04
1.95
4. 07
6. 30
1.07
0.50
2.45
3.50
0.53
0.84
1.30
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
61.40
132.00
201.00
80.00
70.00
0.07
16.00
223.00
308. 00
5.80
0.82
21.30
72.70
0.75
2.45
12. 33
105
107
82
109
76
31
54
110
90
31
361
562
36
16
2,460
25
51
39
39
58
6
27
82
26
0
185
276
23
15
18
83
103
74
103
36
22
52
106
0
31
334
523
35
10
2,404
131
41
89
69
57
51
62
132
140
46
336
353
35
45
200
122
52
420
94
64
93
48
176
57
34
500
705
45
48
363
Ron No. 3
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
6 Feb 69
1430
1500
1455
1515
1528
1511
1458
1450
1533
1442
1429
1436
1440
1500
1508
1453
6.70
2.23
4.78
2.40
2. 90
0.21
0. 15
2. 27
3.80
0. 77
0. 50
1.55
4.40
0.35
0.52
1.27
60
114
108
60
60
10
56
100
84
42
30
45
60
24
45
24
70.50
36. 10
164.00
34.80
41. 60
0.42
0. 09
72. 00
165. 00
3. 02
0.81
10. 00
91.50
0.32
0. 94
11. 92
253
127
127
137
107
38
182
98
191
61
225
17
660
142
74
608
63
113
110
71
66
37
129
98
39
50
193
11
430
95
47
572
181
113
104
118
96
9
136
70
45
54
211
0
602
142
72
571
51
69
100
115
98
100
116
186
176
88
82
174
117
103
92
258
126
203
266
247
174
116
299
285
41
139
156
283
581
461
125
686
7. 35
7.2
6.75
7.6
7. 0
7.5
7. 0
6.9
7.6
7.4
7.4
6.9
6.9
7.6
7.2
1.1x10*
1. 7 x 10?
1.2x10°
3.4 x 10?
1. 9 x 10°
1. 6 x 10,
6.0 x 10°
1.6 x 10°
5.7x10=
1.7 * 10
7
2. 0 x 10,
4. 6 x 10?
1.6x10°
3.0 x 10°
8.0 x 10
6.9
6.9
7. 1
7. 7
7. 3
7.4
7.4
7.2
7.6
7.6
7. 5
7. 3
7. 1
7.4
7.6
7.4
6. 0 x 107
1.7 x 10'
1. 6 x 10'
1.8x10;
8.4 x 10°
2.3x10^
6. 6 x 10°
7. 0 x 10?
5.4 x 10°
2. 6 x 10'
2.0xl06
2. 8 x 10°
1.3 x 10'
2.5x10^
3.4 x 10°
2.6 x 10°
191
-------
Appendix B (continued)
WET-WEATHER COMBINED FLOW CHARACTERISTICS
Number
c
o
+U
3
CO
Run
1
2
3
4
5
6
7
8
9
10
1 1
12
13
14
15
16
•M
a
No. 1
23 Feb 69
«
E
H
0225
0300
0255
0315
0328
0247
0241
0235
0340
0227
0209
0219
0245
0255
0305
0245
£
a
Q
o
£
c
o
*J
3
CO
6. 60
4. 73
7. 58
8. 40
8. 30
0
2. 65
4. 27
2. 47
1. 10
1. 75
5. 70
0. 90
2. 43
0 65
a
o
o
.2
Q
P.
£
60
114
108
60
60
10
56
108
84
42
30
45
60
24
45
24
ID
U
-
o
E
•o
V
if
3s
en -
0)
"a -o
™ d
Hen
•a
V
•o
£.-,
CD -~-
3 M
f-s"
J -£
>cn
54. 3
149.5
304.0
82. 0
103. 0
0
27. 2
242.0
24. 0
3.7
12.4
87. 0
2.0
16.8
3.7
215.7
135. 0
34.5
106. 0
218. 0
67.0
56. 0
146. 0
72. 1
308. 5
113. 8
39.3
114. 0
82. 5
71.4
55. 0
19. 0
63.0
150. 0
49.0
51. 0
65.8
21. 0
128. 5
52. 3
9.3
28. 0
25.0
00
6
-------
Appendix B (continued)
WET-WEATHER COMBINED FLOW CHARACTERISTICS
i-t
to
|
2
§
3
tn
2000
234
74
1850
455
200
84
920
300
252
70
402
262
85
626
2000
223
80
281
309
91
141
1,507
172
77
191
82
50
136
636
15,799
36
36
291
6.7
6.6
6.6
6.8
6.9
6.7
7.0
7.3
6.5
6.9
6.6
5.3
7. 1
6.8
6.7
118
73
751
899
265
100
123
59
191
50
476
2, 724
45
45
636
6.0
6.9
6.2
5. 1
6.7
7:0
6.6
7.0
6.9
6.7
6.7
5.5
6.8
6.9
6.4
1.8 x 10,
3. 0 x 10?
3.8 x 10°
1.0 x 10,
5. 0 x 10
2.4x10°
2.0 x 10°
1.0 x 10,
6.0 x 10°
3.2x10°
9.0 x 10°
8. 0 x 10,
1.8x10°
1.1x10°
1.4 x 10
1.2x10?
2. 6 x 10'
1.4 x 10'
2. 2 x 10,
4. 0 A. 10
f.
4.0 x 10?
4.5 x 10?
4.0 x 10?
4.8 x 10°
4.0 x 10?
3.0 x 10°
4. 0 x 10!
6.0 x 10°
3. 6 x 10°
1.7 x 10
66.0
36. 0
193.5
16.6
22.0
0
0. 1
40.0
123.0
2. 2
0.8
7.8
93. 0
0.4
0. 5
9.9
130
90
168
111
70
123
241
223
52
24
382
62
142
24
661
97
88
165
94
70
90
221
47
48
24
382
48
113
16
648
115
77
135
103
53
107
210
223
32
12
362
0
130
24
637
192
340
80
80
73
75
267
326
75
82
346
347
84
68
104
91
259
177
204
186
354
45
127
14
632
113
113
64
863
6.4
7. 1
6.6
6.4
6.7
6.7
6.5
7.0
6.6
7.0
6.7
6.0
6.0
7.0
7.0
8. 0 x 107
1. 0 x 10'
2. 4 x 10'
2.4 x 10'
8. 0 x 10
,
2.0 x 10,
1.2x10;
5.2 x 10°
3. 0 x 10!
2. 6 x 10,
1. 0 x 10,
4.2 x 10,
9. 8 x 10'
9.6 x 10°
4.0 x 10°
193
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1
Accession Number
w
5
2
Subject Field & Group
05 F
SELECTED WATER RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
Organization
Envirogenics Company, a Division of Aerojet-General Corporation
El Monte, California
Title
Urban Storm Runoff and Combined Sewer Overflow Pollution
10
Authors)
Feuerstein, D. L.
King, R. W.
Grimm, A.
16
21
Project Designation
FWQA Program 11024 FKM Contract #14-12-197
Note
22
Citation
Water Pollution Control Research Series 11024 FKM 12/71
23
Descriptors (Starred First)
Combined sewers, combined sewage, water pollution control, wastewater
treatment systems, waste assimilative capacity, surface runoff.
25
Identifiers (Starred First)
27
Abstract
A general method was developed to assess, primarily from readily available
precipitation and wastewater quality data, the extent of water pollution occurring
from storm water runoff and combined sewer overflows in an urban area, and is applied
to Sacramento, California. Systems for the control and treatment of these wastewaters
are developed and evaluated. The least costly system to adequately protect the
receiving waters from storm water runoff and combined sewer overflows would retain the
combined sewers for the conveyance of combined sewage during wet-weather flow
conditions. Facilities would also be required for the treatment of existing separated
storm water flows. Total annual cost for this system was estimated to be $6.99 million.
A slightly more costly system ($7.09 million) incorporating complete sewer separation
of sanitary sewage and storm water runoff is recommended to the City of Sacramento.
The similarity in annual costs for the separated sewer and the combined sewer systems
results from the requirement for major enlargement of the existing combined sewer
system to adequately convey anticipated combined sewage flows. In areas where
existing combined sewer capacities would not be grossly inadequate, the separation of
combined storm water runoff and sanitary sewage flows to achieve receiving water
quality objectives would appear unwarranted, due to the high cost of constructing new
conveyance facilities and the probable requirement to treat separated storm water
runoff, since its quality is not substantially different from that of sanitary sewage.
Abstractor
D. L. Feuerstein
Institution
Aerojet-General Corporation
WR:102 (REV JULY 1969)
WRSI C
SEND, WITH COPY OF DOCUMENT. TO: WATER RESOURCES SCIENTIFIC INFORMATION CENTER
U.S. DEPARTMENT OF THE INTERIOR
WASHINGTON. D. C. 20240
* GPO: 1970-389-930
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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 DWF 12/69
11000 01/70
11020 FKI 01/70
11024 DDK 02/70
11023 FDD 03/70
11024 DMS 05/70
11023 EVO 06/70
11024 06/70
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
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
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.
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