EPA-600/1-76-033
October 1976 Environmental Health Effects Research Series
This document has not been
submitted to NTIS, therefore it
should be retained.
RENOVATED WASTEWATER AS A
SUPPLEMENTARY SOURCE FOR
MUNICIPAL WATER SUPPLY:
AN ECONOMIC EVALUATION
Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environ-
mental Protection Agency, have been grouped into five series. These five broad
categories were established to facilitate further development and application
of environmental technology. Elimination of traditional grouping was con-
sciously planned to foster technology transfer and a maximum interface in
related fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
This report has been assigned to the ENVIRONMENTAL HEALTH EFFECTS
RESEARCH series. This series describes projects and studies relating to the
tolerances of man for unhealthful substances or conditions. This work is gener-
ally assessed from a medical viewpoint, including physiological or psycho-
logical studies. In addition to toxicology and other medical specialities, study
areas include biomedical instrumentation and health research techniques uti-
lizing animals—but always with intended application to human health measures.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/1-76-033
October 1976
RENOVATED WASTEWATER AS A
SUPPLEMENTARY SOURCE FOR MUNICIPAL WATER SUPPLY:
AN ECONOMIC EVALUATION
by
Robert M. Clark
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
James I. Gillean
Kyle Adams
ACT Systems, Inc.
Winter Park, Florida 32789
Contract No. 68-03-2071
Project Officer
Robert M. Clark
Municipal Environmental Research Laboratory
Water Supply Research Division
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Office of Research and Development,
U.S. Environmental Protection Agency, and approved for publication. Approval
does not signify that the contents necessarily reflect the views and policies
of the U.S. Environmental Protection Agency, nor does mention of trade names
or commercial products constitute endorsement or recommendation for use.
ii
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem
solution and it involves defining the problem, measuring its impact, and
searching for solutions. The Municipal Environmental Research Laboratory
develops new and improved technology and systems for the prevention, treat-
ment, and management of wastewater and solid and hazardous waste pollutant
discharges from municipal and community sources, for the preservation and
treatment of public drinking water supplies, and to minimize the adverse
economic, social, health, and aesthetic effects of pollution. This publica-
tion is one of the products of that research; a most vital communications
link between the researcher and the user community.
The possibilities associated with wastewater reuse have long held a
fascination for environmental engineers. This report presents an economic
evaluation of renovated wastewater as a supplementary source for water supply.
Detailed costs have been calculated that provide a comparison between
renovated wastewater versus the normal means for providing water resource
availability for two case study water supply utilities.
Francis T. Mayo, Director
Municipal Environmental Research Laboratory
iii
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EXECUTIVE SUMMARY
The possibilities associated with the reuse of treated wastewater for
domestic water supply purposes have long fascinated sanitary engineers.
Wastewater renovation allows for the purification of sewage effluent
through advanced waste treatment, making a high quality water available on
site for municipal use. The apparent potential for domestic use of renovated
wastewater coupled with a growing concern and awareness of problems associ-
ated with water supply, as indicated by the Safe Drinking Water Act of 1974,
have made it imperative that an examination of renovated wastewater as a
supplementary source of water supply be undertaken.
The data and associated analysis contained in this report are presented
in an attempt to make a rational evaluation of the economics of renovated
wastewater as a supplementary source for water supply. In the analysis,
the problems of monitoring and adverse health effects which might be asso-
ciated with the use of renovated wastewater are not considered other than
by assuming the best practicable technology which can be applied with
current knowledge to allow water to be reused.
Water supply economic data were obtained from a comprehensive study
conducted by the Water Supply Research Division of EPA. Cost data for the
technology associated with renovated wastewater were obtained from the
Wastewater Research Division of EPA.
Two utilities were selected as the basis for a detailed evaluation of
the use of renovated wastewater as a supplementary source of water supply.
These utilities, the San Diego Water Utility (San Diego, California) and the
Dallas Water Utility (Dallas, Texas) are located in what might be termed
"water-short" areas.
The analysis assumes that each utility is currently meeting stream
standards with its existing wastewater treatment facilities, and that more
raw water will be needed for potable purposes. Both utilities transport
water from existing reservoirs to water treatment plants. Three possibilities
are considered for obtaining additional water: Scheme I is the expansion of
the current water supply source; Scheme II is the option of obtaining addi-
tional drinking water from wastewater after it has been treated by its
existing wastewater treatment system plus an add-on reservoir renovated
wastewater treatment system, transported to existing reservoirs for dilution
and then transported to the water treatment plant; Scheme III is the option
of obtaining drinking water from wastewater after it has undergone treatment
by its existing pollution control facilities, has been further treated in a
iv
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renovated wastewater treatment plant, and is then transported to the head-
works of the existing water treatment facility bypassing the reservoir. In
San Diego, Scheme I means purchasing additional water from the California
water aqueduct system. All of the costs are in 1973-74 dollars and the unit
cost of water supply is assumed to be the same as in 1973-74.
Results of the analysis are presented in the following table:
Comparative Average Costs for Schemes
I, II, and III
Cost of Function ($/mil gal)
Increase (Decrease)
Over Existing
Utility Scheme Acquisition Treatment Distribution Other Total System %
Dallas Existing 25.17 51.70 119.91
System
I 104.66 51.70 119.91
II 182.35 51.70 119.91
III 242.91 51.70 119.91
141.17 337.95
141.17 417.44
141.17 495.13
141.17 555.69
23.5
46.5
64.4
San Existing
Diego System 279.61 27.47 105.86
I 261.99 27.47 105.86
II 494.53 27.47 105.86
III 547.53 27.47 105.86
102.37 515.31
102.37
102.37
102.37
497.96
730.23
783.23
(3.4)
41.7
52.0
Note: An analysis assuming 75% of the capital costs are paid by Government
construction grants yields similar results although the cost increase
due to schemes II and III are somewhat less than shown in the above
table.
As can be seen from the table, implementation of Scheme I in Dallas
will raise the cost of water supply by over 23 percent. However, both
schemes II and III will raise the total cost of water supply by an even
greater percentage. It is interesting to note that the acquisition costs for
schemes I and II increase respectively by 316 percent and 624 percent, but
the total cost increase for water supply is much less. Similar results
occur in San Diego although more efficient use of existing facilities
actually decreases the cost of water supply under Scheme I as compared with
existing supplies.
In both cases, the use of renovated wastewater as a supplementary
source of water supply raises the cost of water above the levels which would
be incurred by using normal sources. However, these cost increases would not
be prohibitive if a community had no other choice for obtaining additional
water supply sources. They suggest that perhaps renovated wastewater might
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be used for industrial and agricultural uses, thereby lengthening the
availability of protected water sources for potable purposes. This analysis
also makes the costs of renovated wastewater explicit, allowing the utility
manager the opportunity to make a rational decision (where appropriate)
as to whether he wishes to take advantage of the improved control available
in his reuse option or, as in the case with many communities, be subject to
random influences.
vi
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TABLE OF CONTENTS
FOREWORD iii
EXECUTIVE SUMMARY iv
METRIC CONVERSION TABLE xvi
INTRODUCTION 1
Basic Economic Evaluation 2
Results 6
DALLAS WATER UTILITY 9
Cost Evaluation 9
Renovated Wastewater Analysis 14
SAN DIEGO WATER UTILITY 34
Cost Evaluation 34
Renovated Wastewater Analysis 37
FINANCING ALTERNATIVES 56
ATTITUDES TOWARD REUSE 58
SUMMARY AND CONCLUSIONS 59
ACKNOWLEDGEMENTS 61
REFERENCES 62
APPENDIX A
DALLAS WATER UTILITY 63
Water Supply Service Area 63
vn
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Organization 63
Acquisition 67
Purification 69
Transmission and Distribution 70
Cost Analysis 72
Systems Costs 79
APPENDIX B
SAN DIEGO WATER UTILITY 91
Organization 91
Service Area 91
Acquisition 93
Treatment 93
Transmission and Distribution 95
Production of Water 95
Cost Analysis 97
System Costs 97
APPENDIX C
TELEPHONE SURVEY RESULTS FOR REGIONS VI AND IX Ill
viii
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TABLES
Number Page
1 Summary of Utility Costs to Provide Finished
Water (1973-1974 Billed Consumption) 7
2 Summary Statistics for Dallas Water Utility (1974) 10
3 Summary of Operating and Capital Expenditures
for 1965-1974 for Dallas Water Utility 13
4 Scheme I - Reservoir and Transmission Plan for
Dallas 16
5 Costs for Scheme II Renovated Wastewater Treatment
Technology 19
6 Cost Estimate for Scheme II Wastewater Reuse Plan 22
7 Costs for Scheme III Renovated Wastewater
Treatment Technology 23
8 Cost Estimate for Scheme III Wastewater Reuse Plan 25
9 Dallas Water Utility's Yearly Water Requirements
at Five-Year Intervals 28
10 Annual Operating and Capital Costs for Dallas
Water Utility 29
11 Cost per Million Gallons of Billed Consumption
for Dallas Water Utility 30
12 Summary Statistics for San Diego Water Utility (1974) 35
13 Summary of Operating and Capital Expenditures for
1965-1974 for San Diego Water Utility 38
14 Historical Costs for Water Purchased by San Diego
Utility 41
IX
-------
Table
Number page
15 Processes and Costs for Wastewater Renovation
Scheme II in San Diego 43
16 Processes and Costs for Wastewater Renovation
Scheme III in San Diego 44
17 San Diego Water Utility Yearly Requirements at
Five-Year Intervals 47
18 Cost Estimate for Scheme II Wastewater
Reuse Plan 48
19 Cost Estimate for Scheme III Wastewater
Reuse Plan 49
20 Annual Scheme Cost for San Diego Water Utility 50
21 Cost per Million Gallons Billed Consumption
for San Diego Water Utility 54
22 Comparative Average Cost for Dallas with 75%
EPA Financing 57
23 Comparative Average Costs for San Diego with 75%
EPA Financing 57
24 Comparative Average Costs for Schemes I, II,
and III in Dallas 60
25 Comparative Average Costs for Schemes I, II,
and III in San Diego 60
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FIGURES
Number Page
1 Schematic Diagram of Acquisition, Treatment and
Distribution Functions for a Typical Water
Supply System 3
2 Schematic of the Water Supply Options: Direct from
Existing Sources; Recycle Wastewater to Reservoir;
Recycle Wastewater to Water Treatment Plant ... 6
3 Dallas Water Utility vs Revenue-Producing Water
Flow 11
4 Schedule of Development - Dallas Long Range Water
Supply Study 15
5 Available Supply Incorporating Wastewate r Reuse . . 18
6 Time-Investment Diagram for Scheme I (Dallas
Water Utility) 20
7 Time-Investment Diagram for Scheme II (Dallas
Water Utility) 24
8 Time-Investment Diagram for Scheme III (Dallas
Water Utility) 26
9 Total Costs for Dallas Water Supply 31
10 Average Unit Costs for Dallas Water Supply ... 32
11 Cumulative Costs for Dallas Water Utility .... 33
12 Treated vs Revenue-Producing Water Flow for
San Diego Water Utility 36
13 San Diego Long Range Water Supply Study;
Scheme I 39
XI
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Figure
Number
Page
14
15
16
17
18
19
San Diego Long Range Water Supply Study;
Scheme II and III
Time-Investment Diagram for Scheme II ...
Time-Investment Diagram for Scheme III . .
Total Time-Investment Cost Diagrams for
Schemes I, II, and III
Average Unit Cost for Schemes I, II, and III
Cumulative Costs for Schemes I, II, and III ,
42
46
51
52
53
55
APPENDIX
TABLES
Table
Number
A-l
A-2
A-3
A-4
A-5
A-6
A-7
Water Service Areas for Dallas Water Utility
Chemicals Used in Water Treatment - Dallas
Water Utility (1972-73)
Water Supply Operating Cost for Dallas Water
Utility
Unit Operating Costs for Dallas Water Utility in
Dollars per Million Gallons of Revenue-Producing
Water
Operating Costs for the Dallas Water Utility As
a Percent of Total Cost
Labor Cost Analysis for Dallas Water Utility . .
Dallas Water Utility Capital and Operating Costs
Page
66
71
73
74
75
76
77
XII
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Table
Number Page
A-8 Capital and Operating Expenditure Ratios for
Dallas Water Utility 78
A-9 Facilities in Dallas Utility Retail Service Area 82
A-10 Cost Elements for Service Zones 83
A-ll Charge Analysis for Typical Monthly Water
Consumption 87
A-12 Cost for Major Consumers in Dallas Service Area 88
A-13 List of Major Users in Cost Zones for Dallas
Service Area 89
A-14 Major Users and Costs Associated with Delivery
and Purchase of Water 90
B-l Summary Statistics for San Diego Water Utility
Distribution and Storage System 96
B-2 Water Supply Operating Cost for San Diego
Water Utility 98
B-3 Unit Operating Costs for San Diego Water Utility
in Dollars per Million Gallons of Revenue-Producing
Water 99
B-4 Operating Costs for the San Diego Water Utility
As a Percent of Total Cost 100
B-5 Labor Cost Analysis for San Diego Water Utility 101
B-6 San Diego Water Utility Capital and Operating
Costs 102
B-7 Capital and Operating Expenditure for San Diego
Water Utility 103
Kill
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Table
Number Page
B-8 Cost Elements for Service Zones 105
B-9 Charge Analysis for Typical Monthly Water
Consumption 106
B-10 Cost for Major Consumers in San Diego Utility
Service Area 107
B-ll San Diego Water Utility's Top Six Major Users -
Costs and Revenues 108
C-l Telephone Survey Results for Region VI 112
C-2 Telephone Survey Results for Region IX 113
APPENDIX
FIGURES
Figure
Number Page
A-l Dallas Water Utility's Service Area 64
A-2 Organization of Dallas, Texas, Water Utility . . 65
A-3 Proposed and Existing Reservoirs for Dallas ... 68
A-4 Treatment Plants and Pump Stations in Dallas
Utility Service Area 80
A-5 Allocation of Capital and Operating Expenses
to Water System Components for Dallas Water Utility 81
A-6 Cost of Service Over Pathway 1 84
A-7 Map of Cost Zones and Major Users for Dallas Service
Area 86
xiv
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Figure
Number Page
B-l San Diego Water Utility 92
B-2 Reservoir System and Service Area for City of
San Diego 94
B-3 San Diego Water Utility Facilities 104
B-4 San Diego Water Utility - Capital and Operating
Expenses Allocated to Water System Components . . . 109
B-5 San Diego Water Utility Major Users and Cost
Zones 110
xv
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METRIC CONVERSION TABLE
English Units
1 foot
1 mile
1 sq. mi.
1 mil gal
1 $/mil gal
Metric Equivalents
0.305 meters
1.61 kilometers
2.59 sq. kilometers
3.79 thou cu meters
0.26 $/thou cu meters
XVI
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RENOVATED WASTEWATER AS A SUPPLEMENTARY SOURCE
FOR MUNICIPAL WATER SUPPLY: AN ECONOMIC EVALUATION
by
o Of*
Robert M. Clark , James I. Gillean and Kyle Adams
INTRODUCTION
Passage of the Safe Drinking Water Act of 1974 has focused a growing
awareness on problems related to the supply of potable water to the consumer.
This Act establishes primary (health related) drinking water standards, and
secondary (aesthetics related, but not enforceable) guidelines for drinking
water supplies. Throughout the Act, there is a constant emphasis on the
need to consider the economics of water delivery, including the possibility
of using renovated wastewater as a supplementary source for water supply.
Data presented in this report are intended to provide information of a stan-
dardized and comparable nature on the costs of water supply from a selected
set of water supply utilities. These data provide a useful baseline of
information from which many decisions, such as the relative attractiveness
of the cost of renovated wastewater as a water supply source, can be made.
Wastewater renovation allows for the purification of sewage effluent
through advanced waste treatment, making a high quality water available on
site for municipal use. The idea of reusing water is not new, nor is it
unique since it is estimated that over 40 percent of the U. S. population
reuses water that has already been used for some domestic or industrial pur-
poses including power cooling, and it is estimated that 60 percent of the
population reuses water that has been used upstream. In some cases, the
water supply of a city lies downstream from the sewage outfall of another,
or tidal influence returns the flow of a city's effluent to its water supply.
a. Systems Analyst, Water Supply Research Division, Municipal Environmental
Research Laboratory, Office of Research and Development, U. S. Environ-
mental Protection Agency, Cincinnati, Ohio 45268.
b. President, ACT Systems, Inc., Winterpark, Florida.
c. Systems Analyst, ACT Systems, Inc., Winterpark, Florida.
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With increasing waste treatment requirements, the quality of treated
effluent has increased accordingly. There is also a growing awareness on
the part of state governments of the need to provide for more stringent regu-
lation on intrastate streams. As a result, the quality of treated effluent
in many cities will be suitable for nonpotable municipal uses and, with
additional treatment, might be suitable for domestic usage.
Despite its potential attractiveness, there are still many problems
associated with wastewater reuse. For example, many water supply monitoring
techniques are intended to be used on relatively clean waters. It is possible
that wastewater like many surface water supplies may contain constituents of
an exotic nature which may have adverse health effects even after it has been
treated by standard drinking water technology. The current concern over the
formation of trihalomethanes which result from the interaction of chlorine
with organics in drinking water illustrates this problem. Another illustra-
tion is the discovery that known carcinogens, such as carbon tetrachloride,
pass through the water treatment process. All of these unknowns suggest
that the deliberate and planned reuse of wastewater as a supplementary source
for drinking water supplies should be studied more thoroughly.
However, in this report these monitoring and health effects problems
are not considered, other than by specifying the best practicable technology
which can be applied with current knowledge to allow water to be reused.
The purpose of this report is to make standard cost comparisons for renovated
wastewater as a supplement to existing water supplies. The wastewater reuse
costs are compared against the costs of acquiring water from normal sources.
The best known practicable treatment techniques for renovated wastewater are
assumed. Data from two case study areas are presented and specific waste-
water renovation alternatives are analyzed. The results presented in this
report should serve not only to provide specific cost information on two
case studies, but also to provide an example as to how future cost comparisons
for wastewater reuse can be made.
BASIS FOR ECONOMIC EVALUATION
In order to acquire data which can be utilized for standardized cost
comparisons, a basic philosophy for data collection needs to be established.
The functional areas of acquisition, treatment or purification, and distri-
bution, shown in Figure 1, are common to all water supply delivery systems
and, therefore, provide a common basis for data collection. Not shown on the
schematic is the management or administrative function which complements the
physical activity of supplying water to the consumer. It is this overall
management function which establishes an institutional mechanism for ensuring
that adequate amounts of safe water are supplied. This institution is most
commonly called a water supply utility.
When analyzing the physical distribution system, it is possible to
utilize the functional areas mentioned above. However, the functional areas
or cost categories must be expanded to collect data which adequately reflect
both the physical supply of and the managerial requirements for a drinking
water supply. These cost categorizations must reflect both operating and
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TREATMENT
PLANT
STORAGE
TANK
ACQUISITION
PURIFICATION
DISTRIBUTION
FIG. 1 SCHEMATIC DIAGRAM OF ACQUISITION, TREATMENT AND
DISTRIBUTION FUNCTIONS FOR A TYPICAL WATER
SUPPLY SYSTEM
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capital costs, since a water supply utility requires major expenditures in
fixed facilities. For purposes of the study described in this report,
cost data were assigned as being related to either operating or capital
expenditures. As nearly as possible, the operating costs which are required
to supply water are assigned to the following functional areas: Acquisition;
Purification; Power and Pumping; Transmission and Distribution (including
storage); and Support Services. The first four categories are closely
related to the physical delivery of water, and the fifth, Support Services,
is related to the overall integrative responsibility of the utility manage-
ment. Operating costs are those costs which are required to operate in each
functional area, including operating labor, maintenance, and materials.
For example, in the purification function, laboratory personnel costs are
included in the purification cost category, but management costs for this
function are included in the Support Services category. Support Services
includes therefore all of the administrative and customer services which are
required to manage the water utility and collect revenues, but they are not
directly related to the physical process of delivering water.
Capital costs are assumed to be depreciation and interest on the
plant-in-service. Depreciation as reported here is based on the historic
cost of the facility divided by its useful life, and not on the costs required
to reproduce the facility. The data reported for depreciation, therefore,
reflect lower costs for older utilities, since the utilities discussed in
this report constructed the majority of their facilities in the 1930s and
40s. Interest costs are the actual rates which the utilities must pay for
their bonds or other money raising mechanisms.
All of the data reported are strictly related to the cost of water supply
and do not include some of the broader aspects of elasticity of demand and
optimal pricing policies for water supply. All costs reported in this
study are based on revenue producing water, pumped by the utilities between
years 1964-1974 (a 10-year period coinciding with the utilities accounting
year).
Using the approach outlined above, utilities in five Standard Metropolitan
Statistical Areas (SMSA) were selected for investigation to determine their
costs to supply water. Results of the overall study will be published
separately. Two of these utilities were chosen as having special signifi-
cance, being located in what has been termed "water short areas." These two
utilities, the Dallas Water Utility (Dallas, Texas), and the San Diego Water
Utility (San Diego, California), were analyzed using the approach outlined
above but, in addition, a detailed evaluation of using renovated wastewater
as a supplementary source of water supply was made. Comparisons for waste-
water reuse focus on the acquisition category mentioned earlier. That is,
it is assumed that a water utility needing more water might acquire additional
water from normal sources, such as reservoir development, or it might reuse
wastewater.
In the renovated wastewater analysis it is assumed that the utility is
currently meeting stream standards with its existing wastewater treatment
facilities and that it wishes to obtain more raw water for potable purposes.
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Therefore, if it wishes to consider renovated wastewater as a supplement
to its existing sources, any additional technology required to reuse waste-
water is considered to be an add-on to the existing waste treatment plant.
Three possibilities (Schemes I, II, and III) were considered for obtaining
additional water in each of the two utilities studied. The first scheme,
(Scheme 1), is to expand the current water supply source, thereby obtaining
water from normal or conventional sources.
Scheme II is the option of obtaining drinking water from wastewater,
after it has been treated in existing pollution control facilities and in an
add-on renovated wastewater treatment system and is then transported to an
existing reservoir (up to 50 percent of water demanded). For example, if the
normal demand for water supply is 100 million gallons p^r day (mgd) and if
80 mil gal of the supplied water eventually reach waste treatment facilities,
then 50 mgd of the 80 mil gal are assumed returned to existing reservoirs.
This assumption has the effect of extending existing supplies so that no
new reservoir capacity is needed. However, at some point (if demand grows
sufficiently), total demand will exceed existing capacity plus 50 percent
of water demanded and additional capacity must be supplied. From the
reservoirs it is directed to existing water treatment facilities. Scheme III
is the option of obtaining drinking water from wastewater, after it has under-
gone existing pollution control treatment, has been further treated in a
renovated wastewater treatment plant, and is then transported to the head-
works of the existing water treatment plants. Figure 2 illustrates these
possibilities.
The basic assumptions underlying the analysis presented in this report
are:
Renovated wastewater is considered as a supplement to existing
water sources
All costs are calculated on a common and standardized basis (as
discussed earlier).
The costs are as they would be assessed to the utility and do not
include social discount rates (etc.).
Capital costs are assumed to consist of an annualized, straight-
line depreciation of plant-in-service and interest costs.
Costs for the wastewater renovation analysis are in 1974 dollars.
Renovated wastewater technology is considered to be an add-on to
existing wastewater treatment plants.
RESULTS
The results of the study conducted are presented in Table 1. However,
only the details of the Dallas and San Diego utilities are described
separately with their associated renovated wastewater analysis. The other
utility cost data are included for comparison purposes only. Appendices A
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SCHEME II
WATER
TREATMENT
SCHEME III
UTILITY
SERVICE AREA
EXISTING
WASTE
TREATMENT
RENNOVATION
PLANT
DISCHARGE TO RIVER
FIG. 2 SCHEMATIC OF THE WATER SUPPLY OPTIONS: DIRECT FROM
EXISTING SOURCES; RECYCLE WASTE WATER TO RESERVOIR;
RECYCLE WASTE WATER TO WATER TREATMENT PLANT
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TABLE I - SUMMARY OF UTILITY COSTS TO PROVIDE FINISHED WATER*
(1973-74 billed consumption)
Utility Bil gal/yr
Kansas City 26.9
Dallas 63.0
San Diego 47.2
New Haven 17 .7
Fairfax 19.2
Simple Avg. as
Percent of
Common Cost
Acquis-
tion
15.28
25.17
279.61
28.97
34.79
17.5
Treat-
ment
81.98
51.70
27.47
15.38
61.54
10.9
Distri-
bution
138.64
119.91
105.86
107.34
128.33
27.4
Support
Services
144.52
83.46
95.64
118.19
88.27
24.2
$/mil gal
Interest Common Exceptional Costs*
Costs Private Dividends
Utility
Taxes
50.32 430.70
57.71 337.95
6.73 515.31
116.70 386.58 196.44 87.86
208.57 521.50
20
* Applies to private utilities only.
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and B contain detailed descriptions of both the Dallas and San Diego water
utilities and Appendix C contains the results of a wastewater reuse survey
conducted in Regions VI and IX, and the results of a survey of all of the
utility major consumers concerning their attitudes toward reuse. Conclu-
sions and recommendations resulting from this analysis are presented in the
last section of the report.
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DALLAS WATER UTILITY
The City of Dallas lies within Dallas County, which is in north central
Texas. The city has a population of 942,462 and the county's population is
1,549,221, based on the 1970 census. Dallas' growth rate of 3.1 percent per
year has many implications for urban services, such as water supply. The
Dallas Water Utility provides water on a retail basis to all classes of cus-
tomers within the city and county of Dallas, as well as to many communities
outside the county (Appendix A describes the Dallas water utility). Table 2
summarizes some important statistics for 1974.
Organizationally, the Dallas Water Utility combines both water supply
and wastewater treatment functions. It is composed of three sections:
Engineering and Planning, Operations, and Business.
Raw water comes from five major reservoirs, and is treated in treatment
plants, geographically located in the northwest, central, and southeastern
sections of the city. They are generally in the low lying areas of the city,
thus requiring that water be pumped up to residences and businesses located
at higher elevations.
Figure 3 illustrates the growth in consumer demand for water fron 1964
through 1974. "Treated" water is the amount of water that was pumped from
the city's three water treatment plants and purchased water. "Revenue
producing" water is the water which was measured as metered consumption and
paid for by wholesale and retail customers.
Cost Evaluation
The physical, organizational, and managerial structure of the Dallas
Water Utility is discussed in detail in Appendix A. It is difficult to
analyze the precise nature of the interaction of the various components of
this system. However, in order to properly understand the nature of the
utility, such an analysis must be attempted. One approach is to subdivide
the utility structure into its various functional components, and to analyze
its unit costs. The second approach is to reaggregate these functional com-
ponents in such a manner that they represent a cost picture of the physical
acquisition, treatment and distribution system. Both of these approaches are
presented. A key factor in this analysis is the choice of the basic units
for establishing unit costs. For purposes of this analysis, the productivity
base is revenue-producing water. The difference between revenue-producing
and treated water is due to leaks and other losses in the system. For pur-
poses of this report, it is assumed that productivity will be measured in
units of "millions of gallons" (mil gal).
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TABLE 2
SUMMARY STATISTICS FOR DALLAS WATER UTILITY (1974)
Population - SMSA 2,729,356
County 1,549,221
Retail Service Area 942,462
Area of Retail Service Area (sq. miles) 301.38
Number of Meters in Recognized Customer Classes
Residential 201,830
Commercial 20,508
Government 1,015
Apartment 5,272
Industrial 129
Suburban Cities 35
Flat Rate (number of accounts none
Percent Metered 100
Purchased Water (treated rail gal) 2,770
Source Water 100% Surface Impoundments
Pipe in System (miles) 3,208
Elevation of Treatment Plants (ft, above mean sea level)
Backman 446
Elm Fork 458
East Side 480
Elevation of Service Area (min-max) (ft) 430 - 875
Revenue-Producing Water (billed consumption in mil gal) 63,030
Treated Water (pumpage from treatment plants + treated
(purchased water in mil gal) 70,656
Maximum Day/Maximum Hour (mil gal per day) 433/665
10
-------
TREATED
WATER
2 35
5 30
25
20
-
REVENUE PRODUCING
WATER
I
1
1 I
I
I
I
I
I
64 65 66 67 68 69 70 71 72 73
YEAR
74
FIG. 3 DALLAS WATER UTILITIES TREATED
VS. REVENUE PRODUCING WATER FLOW
11
-------
As mentioned earlier, operating costs were categorized into the follow-
ing: Acquisition; Purification; Transmission and Distribution; Power and
Pumping; and Support Services. Table 3 summarizes the historic costs in
these areas for the water years 1965 through 1974. During this 10-year
period, the actual accounting system changed three times, making it difficult
to track some of the specific cost items over the period of analysis.
Operating costs were divided by millions of gallons of revenue-producing
water to provide standardized operating unit costs (Table 3) putting them on
a unit production basis.
It can be seen that the total operating cost increased from $5,686,673
to $12,528,040. However, Support Services costs increased at a faster rate,
from $1,355,170 to $4,700,439. On a unit cost basis, the total operating
cost of water supply increased from $144.80/mil gal to $198.76/mil gal, with
the greatest increase occurring in the overhead category. Table 3 also con-
tains the operating costs as a percent of total costs, making it possible to
identify where shifts occurred in the proportion of the total amount of money
committed to a given task.
It can be seen that the unit operating cost did not increase as fast as
total cost over a 10-year period of time. It can also be seen that the cost
per mil gal fluctuates, based on the actual amount of water required in any
given year. Because a given work force can produce a variable amount of
water, if demand is heavier during a year because of an unusual drought, the
water consumption can be higher without a corresponding increase in total
operating cost, causing unit costs to drop. The reverse is also true. If
the water usage is low because of unusual conditions, such as excessive rain,
the water consumption will be reduced without a corresponding reduction in
operating cost. An example occurred in 1973 when water consumption signifi-
cantly decreased, but the unit operating cost increased.
From Table 3, we can also see that the proportion of the total cost
devoted to Support Services increased from 24 percent in 1964-65 to 38 per-
cent in 1973-74. In contrast acquisition, which is primarily associated with
the operation of reservoirs, the cost as a percentage of the total decreased
from 9.2 percent to 5.4 percent. It is expected that the cost of power and
pumping will significantly increase in the future, because of major increases
in the cost of electricity.
To this point, the only costs that have been discussed are operating
expenses. To determine the total cost of producing water, it is necessary
to add expenses associated with capital expenditures. As discussed earlier,
there are several methods for determining the capital costs associated with
a water utility. The method chosen for this effort is to depreciate the net
plant in service, based on original purchase price, on a straight line basis,
over a designated period of time. In addition to depreciation cost associated
with capital investment, the cost of borrowing money to acquire the capital
equipment and facilities must also be considered. The cost of money is con-
sidered to be the actual interest paid by the utility when the money is
borrowed.
12
-------
TABLE 3
SUMMARY OF OPERATING AND CAPITAL EXPENDITURES FOR 1965-1974
FOR DALLAS WATER UTILITY
Item
Support services
million $
% of total
$/mil gal
Acquisition
million $
% of total
$/mil gal
Purification
million $
% of total
$/mil gal
Power and pumping
million $
% of total
$/mil gal
Transmission and
distribution
million $
% of total
$/mil gal
Total operating
costs
million $
$/mil gal
Depreciation
million $
Interest
million $
Total capital
costs
million $
Total operating
and capital costs
million $
1.
23.
34.
.
9.
13.
1.
24.
35.
.
17.
25.
1.
25.
36.
5.
144.
2.
1.
4.
10.
65
355
83
51
524
22
35
377
23
07
999
57
44
431
16
43
687
80
979
918
397
583
66
1.450
24.13
36.82
.538
8.95
13.65
1.449
24.09
36.76
1.003
16.69
25.46
1.572
26.15
39.90
6.012
152.59
3.176
1.951
5.127
11.140
67
1.664
25.61
38.57
.597
9.20
13.85
1.448
22.29
33.57
1.094
16.84
25.36
1.692
26.05
39.24
6.496
150.29
3.339
2.088
5.427
11.924
68
1.873
27.19
41.27
.515
7.48
11,35
1.510
21.92
33.27
1.143
16.59
25,19
1.847
26.81
40.70
6.887
151.78
3.494
2.246
5.740
12.627
69
2.285
29.16
42.76
.495
6.32
9.26
1.759
22.44
32.90
1.336
17.04
24.98
1.963
25.04
36.71
7.838
146.61
3.688
2.196
5.884
13.722
70
2.670
30.86
47.29
.501
5.79
8.87
1.902
21.97
33.67
1.404
16.22
24.86
2.179
25.17
38.57
8.656
153.26
3.815
2.804
5.899
14.555
71
3.492
35.28
61.75
.578
5.83
10.21
2.206
22.27
39.01
1.521
15.36
26,89
2.104
21.24
37.20
9.901
175.06
3.986
2.193
6.179
16,079
72
3.764
34.67
62.02
.533
4.91
8.79
2.307
21.24
38.01
1.781
16.40
29,34
2.473
22.77
40.73
10.859
178.89
4.407
2.509
6.916
17,775
73
4.403
35.53
78.63
.756
6.10
13,50
2.573
20.76
45.95
1.908
15.4-
34.07
2.751
22.20
49,13
12.390
221.28
4.752
3.425
8.176
20,567
74
4.700
37.54
74,57
.688
5.49
10.92
2,788
22.25
44.24
1.806
14.41
28.66
2.545
20.32
40.37
12.528
198.76
5.135
3.638
8.773
21,301
269.46 282.70 276.42 278.30 256.72 257.74 284.31 292.83 367.29 337.94
-------
For the purpose of this report, the total cost of producing water is
considered to be operating expenses, depreciation of capital equipment and
facilities, and interest paid on borrowed money. On this basis, the total
cost in Dallas for producing water increased from approximately 10.5 million
dollars in 1965 to approximately 21.3 million dollars in 1974, an increase of
102 percent in total expenditures. However, during that same time period,
the cost of producing a million gallons of water increased only 38 percent
— from $269.46 to $337.94 (Table 3).
Renovated Wastewater Analysis
Having compiled an adequate historical data base concerning the Dallas
water supply delivery system, it is possible to analyze the potential for the
use of renovated wastewater as a supplementary water supply source. This is
most meaningful when it can be compared against existing plans for water supply
augmentation.
Population growth trends within Dallas County and the trend toward
increasing dependency of the suburban communities around Dallas on the Dallas
Water Utility are estimated to raise the projected average day demand from
291.2 mgd in 1980 to 900.2 mgd in 2050. In order to meet these needs, the
Dallas Water Utility has developed a plan for new reservoirs and transmission
facilities. Six new reservoirs and 15 new transmission facilities will be
needed and brought on line to supply the city's total average day demand by
the year 2050. Current supplies are obtained from the existing Grapevine and
Ray Hubbard reservoirs (see Appendix A).
Figure 4 illustrates the increase in the estimated total average day
demand from 1975 through 2050. The horizontal dotted line which indicates
the limits of the existing supply intersects the average day demand line
(concave dotted line) in 1980. The scheduled resource development is shown
by the dark line (step function).
Table 4 shows in order needed the six reservoirs and 15 transmission
facilities that will be required to meet the needs of the Dallas Water Util-
ity through the year 2050. The table also includes information on the
dependable yield of the reservoirs and the capacity of the transmission facil-
ities, the capital cost per year, the capital recovery period, and the oper-
ating cost per year, all based on January 1973 costs. The reservoir
development scheme is part of a comprehensive project by the Corps of
Engineers, Fort Worth Office. Costs assessed against Dallas represent its
share of the comprehensive development program.
It is the reservoir and transmission facility development scheme
(Scheme 1) against which two renovated wastewater schemes will be evaluated.
Scheme II considers collecting from the wastewater system 50 percent of the
raw water demanded in any year, treating it to acceptable levels, and repump-
ing it into existing reservoirs for water supply. Scheme III assumes that
the same amount of wastewater is used per year as in Scheme II, but that it
is treated to a higher level and pumped directly into the headworks of the
water treatment system. Both of the renovated wastewater schemes (schemes
II and III) will satisfy Dallas' needs up to the year 2005. After that point,
14
-------
IUUU
750
T*
o>
E
Z
Z
5 500
Ul
Q
Q
Z
<
>
_l
Q.
Q.
S 250
o
1 I 1 1 1 1 n 1
CO
3
CM
0 J*
TOTAL WATER to CM ^,'
SUPPLY DEVELOPMENTS m o /
\ o N ^x
CO 0 .^
0 OJ /
— ° s —
e\i I — /^
V X
^ \ -T
0) ^ /
°! ^/ TOTAL AVERAGE
0 jo y"*~DAY DEMAND
co co x
»- *~ /
_ 0 /
- rn4/
r / EXISTING SUPPLY^
/ - V^
— ,/ CLOSS OF _
RETURN FLOW
1 1 1 1 1 1 1
1970 1980 1990 2000 2010 2020 2030 2040 2050
YEAR
FIG. 4 SCHEDULE OF DEVELOPMENT
DALLAS LONG RANGE WATER SUPPLY STUDY
15
-------
TABLE 4
SCHEME I
RESERVOIR AND TRANSMISSION DEVELOPMENT PLAN FOR DALLAS*
Year
of
Need
1980
1985
2003
2008
2016
2022
Supply
(MGD)
60.5
39.5
53.7
60.0
45.0
170.0
Capital Cost
per year
(1000 $)
Capital Cost
Recovery
Period (Years)
Operating Cost
per Year
(1000 $)
3,072
334
1,915
617
1,140
1,356
Facility**
RESERVOIR
Aubrey
Cooper
Sulfer Bluff I
Sulfer Bluff II
Mineola
Tennessee Colony
TRANSMISSION
Lavon to Lewisville
Tawakoni to Lavon
Hubbard to E. Side
Copper to Lavon
Palistine to E. Side
Southeast Terminal
Sulfer Bluff to Cooper
Cooper to Lavon
Mineola to Tawakoni
Lavon to Lewisville
Bristol Intermediate
Tennessee Colony to
Bristol
Bristol to SE Terminal
Tennessee Colony to
Bristol
Bristol to SE Terminal
* Costs in $1,000 at January 1973 price level.
** Map of facilities is contained in Appendix A.
1978
1978
1985
1991
1994
2000
2003
2003
2016
2016
2022
2022
2022
2035
2035
120
100
150
95
102
102
228
212
45
103
170
85
170
85
170
1,057
1,262
200
806
3,540
616
205
1,322
443
1,036
689
2,178
730
2,178
730
50
50
30
30
50
50
30
30
30
30
30
30
30
30
30
30
30
30
30
30
30
573
25
49
7
329
532
676
480
82
395
1,073
20
172
736
189
531
20
643
151
643
151
-------
additional reservoir capacity will be needed and it is assumed that the
reservoir and transmission line development program (Scheme I) will then be
initiated, but at a slower pace than shown in Table 4. Schemes II and III
have the effect of delaying and slowing the development of the reservoir
program (Scheme I) and conserving available resources.
Figure 5 illustrates the effect which 50 percent of raw water demand
wastewater reuse will have on the existing supply. The average day demand is
the same as in Figure 4, but the solid concave line represents the amount of
wastewater returned for use, which can be added to the available supply. By
reusing this water, the existing supply plus the renovated wastewater, as
shown by the dotted line, intersects the average day demand at the year 2005.
At this time, it would be necessary to build additional transmission lines.
This would further extend the effective yield of the present day supply to
the year 2015 when the Aubrey Reservoir will be required. An additional
reservoir will be required in 2037 to meet needs until 2050. This analysis
does not extend beyond 2050. In Scheme II, the treated wastewater is pumped
to the existing Ray Hubbard and Grapevine reservoirs (see map in Appendix A)
and by the year 2050, development of the Aubrey and Cooper reservoirs is
required.
Scheme I: Scheme I, as shown in Table 4, costs over $1,022 billion
through the year 2050, and a time-investment diagram is shown for this scheme
in Figure 6. It was developed by plotting the sum of the annual operating
and capital expense for each facility as it is brought on line. For example,
in 1978, according to Table 4, the transmission facilities from Lavon to
Lewisville and from Tawakoni to Lavon will be brought on line. The annual
operating and capital costs for the facilities together is $4,375,000 until
1980 when the Aubrey reservoir comes into operation at an annual cost of
$3,645,000. When the life of the facility is completed, the annual costs
are set at zero. Schemes II and III are discussed in the following sections
but, before doing so, the term "demand water" must be defined. Demand water,
as discussed earlier, is equivalent to treated water shown in Figure 3. When
costs are computed in this section a correction factor of 0.75 is applied to
make the cost of acquisition computed in schemes I, II, and III compatible
with the costs in the previous section. It is assumed for schemes II and III
that the existing reservoirs are adequate to handle the additional 50 percent
wastewater.
Scheme II: It is assumed that the following unit processes can be added
to the existing waste treatment plants to produce a water which is adequate
for piping back to the reservoirs:
two-stage clarification
mixed media filtration
granular activated carbon (40-min detention time)
It is also assumed that individual 100 mgd plants will be constructed in
schemes II and III. Therefore, every time the amount of wastewater required
to meet demand exceeds the capacity of a 100 mgd plant, a new treatment plant
is assumed to be constructed. To annualize the capital cost, a capital
recovery factor (CRF) of 0.0651 is used for plants' transmission facilities
and two reservoirs which assumes they have a life of 30 years and an interest
17
-------
1000
750
O)
E
- 500
O
Z
UJ
a
o
z
/ /
/ /
250
- /
/
a.
a.
3
CO
I
TOTAL AVERAGE
DAY DEMAND
X'- AVAILABLE SUPPLY
.f INCORPORATING
' WASTEWATER REUSE
50% WASTEWATER
USE-
1970 80
90 2000 10
YEAR
20
30
40
50
FIG. 5 AVAILABLE SUPPLY INCORPORATING
WASTEWATER REUSE
18
-------
TABLE 5
COSTS FOR SCHEME II RENOVATED WASTEWATER TREATMENT TECHNOLOGY
Treatment Process
2-stage lime clarification
Mixed media filtration
Granular activated carbon
(40 min. det. time)
Capital Cost
($ x 106)
9.8
5.2
27.2
Operating and Maintenance Cost
($71000 gal)
0.046
0.018
0.046
19
-------
MILLIONS OF DOLLARS
ro
o
w
o
tO
00
T]
o
m
? s
r-
> H
^ m
> H
S E
30 >
C O
H 3>
= >
30
(/)
m
m
(0
ro
o
o
o
8
ro
o
w
o
o
o
ro
o
01
o
-------
rate of 5 percent. The other four reservoirs are assumed to have 50-year
lives and a CRF = 0.0405 with 3.225% interest. A discussion of the impact of
interest rates used in the analysis is presented later.
Table 5 summarizes the treatment facilities for Scheme II and Table 6
summarizes all of the facilities required and their associated costs. It is
assumed that two transmission pipelines are constructed for returning waste-
water to the Ray Hubbard and Grapevine reservoirs in 1980 (see Appendix A).
By the year 2007, four 100 mgd renovated wastewater treatment plants will be
functioning and by the year 2032, five will be on-line.
Figure 7 represents a time-investment diagram for Scheme II. The bottom
line represents the cost of the renovated wastewater treatment and the top
line is the total cost for Scheme II including transmission facilities. The
cost of additional reservoir capacity required in conjunction with the
renovated wastewater is included in the figure beyond the year 2005.
Scheme III: Scheme III assumes that wastewater is pumped directly into
the headworks of the Dallas water treatment plants. Because of this direct
reuse, a much more reliable treatment train is hypothesized. The treatment
facilities required for such a system are as follows:
two-stage lime clarification
mixed media filtration
granular activated carbon (40 min detention time)
ozonation (40 mg/1, Oo feed rate)
The capital and operating costs for a 100 mgd plant are shown in Table 7.
As with Scheme II, it is assumed that when the need for renovated wastewater,
based on 50 percent of demand water, exceeds the existing capacity, a new
100 mgd plant will be constructed. Table 8 contains the costs and facilities
associated with Scheme III through the year 2050, including development of
the Aubrey and Cooper reservoirs and associated transmission facilities. A
time-investment curve is shown in Figure 8, in which the bottom line repre-
sents the treatment portion of the scheme, and the top line is the total cost,
including transmission to the water treatment plants and additional reservoirs.
Cost Comparison of Schemes: Both of the reuse schemes are based on the
assumption that 50 percent of the demand water is recycled for water supply
use. It must be clearly understood that demand water and consumed water are
two distinct concepts. For Dallas, Figure 4 shows the water demanded but a
factor of 0.75 must be applied to the demand water to yield the amount of
water supplied to the consumer. The wastewater renovation plants are
designed so that they can handle 50 percent of the demand water but costs are
based on $/mil gal of water consumed. For example, if 100 mgd of water is
demanded only 75 mgd are consumed. However, 50 mgd are returned to the reser-
voirs. If the available supply is 50 mgd, then the amount of recycled water
plus available supplies would meet consumption requirements. The cost would
be calculated by adding the total cost for the available supply plus the
total cost for the wastewater renovation system and dividing the sum by 75
mgd (the water consumed). All costs have been calculated on this basis.
21
-------
ro
N3
TABLE 6
COST ESTIMATE FOR SCHEME II WASTEWATER REUSE PLAN*
Facility
SOURCE
Dallas Wastewater
Plants
Aubrey Reservoir
Cooper Reservoir
TRANSMISSION
Wastewater Renovation
Plant to Ray Hubbard
Wastewater Renovation
Year
of
Need
1980
2015
2037
Supply
(mgd)
50% of water
demanded
60.5
39.5
Capital Cost
per Year
($ 1000)
1980
3,072
334
216
1,350
Capital Cost
Recovery
Period
50
50
30
Operating Cost
per Year
($ 1000)
573
25
739
Plant to Grapevine
Tawakoni Pipeline
WASTEWATER PLANT
1
2
3
4
5
1980
2005
1980
1984
1990
2007
2032
216
100
100
100
100
100
100
1,875
1,262
2,745
2,745
2,745
2,745
2,745
30
30
30
30
30
30
30
1.026
480
4,015
4,015
4,015
4,015
4,015
* 1973 Price Level
-------
TABLE 7
COSTS FOR SCHEME III RENOVATED WASTEWATER TREATMENT TECHNOLOGY
Treatment Process
2-stage lime clarification
Mixed media filtration
Granular activated carbon
(40 min. det. time)
Ozonation (40 mg/1
0 feed rate)
Capital Cost Operating and Maintenance Cost
($ x 106) ($71000 gal)
9.8
5.2
27.2
24.5
0.046
0.018
0.046
0.039
23
-------
50
cc
< 40
O
Q
LL 30
2 20
10
1975 1980
,-J
r—i
! TOTAL COST
I
WASTE TREATMENT
COST
1990 2000 2010 2020
YEAR
2030
2040
2050
FIG. 7 TIME-INVESTMENT DIAGRAM FOR SCHEME II
(DALLAS WATER UTILITY)
-------
Facility
SOURCE
TABLE 8
COST ESTIMATE FOR SCHEME III WASTEWATER REUSE PLAN*
Year
of Supply
Need (mgd)
Capital Cost
per Year
($)
Dallas Wastewater
Plants
Aubrey Reservoir
Cooper Reservoir
TRANSMISSION
WW to East Side
WW to Bachman
Bachman to Elm Fork
WW to Bachman
Tawakoni Pipeline
WASTEWATER TREATMENT PLANT
1 (5 - 100 mgd)
2
3
4
5
1980 50% of water
demanded
2015 60.5
2037 39.5
1980 150
1980 150
1980 150
1995 150
2005 150
1980 100
1984 100
1990 100
2007 100
2032 100
3,072
334
984
844
562
844
1,262
4,342
4,342
4,342
4,342
4,342
Capital Cost
Recovery
Period
50
50
30
30
30
30
30^
30
3CC
30.
30
Operating Cost
per Year
($)
573
25
399
342
228
342
480
5440
5440
5440
5440
5440
* 1973 price level
+ CRF = 0.065
-------
50
OC 40
30
o
o
LL
O
0)
z
O 20
10
I TOTAL COST
i
WASTE TREATMENT
COST
1975 1980 1990 2000 2010 2020 2030 2040
YEAR
FIG. 8 TIME-INVESTMENT DIAGRAM FOR SCHEME
(DALLAS WATER UTILITY)
2050
-------
The first line of Table 9 contains the raw water demand for the Dallas
water system from 1980 through 2050. The second line contains the current
available supply, and the third line contains the value for excess of demand
over available supply. It is obvious that after 1980 additional water must
be obtained to make up the deficit in available water. Line four contains the
amount of recycled water based on 50 percent of demand, and line five contains
the total water which is available if recycled water is added to the avail-
able supply.
The demand as reduced to water consumption (consumption = 0.75 demand)
is shown in parentheses. It can be seen, for example, that in 1985, 12,309
mil gal for consumption must be obtained beyond existing supplies. The
amount available for consumption, based on reuse, is 47,222 mil gal.
The annual costs for each scheme are shown in lines 1 through 3 of
Table 10. Total costs, including existing supply, are shown in lines A
through 6. Table 11 contains the unit costs for total supply for each scheme
(lines 1 through 3) and recycled water (lines 4 and 5).
Figure 9 represents a total cost time-investment diagram for each of the
three schemes, and it is obvious that Scheme I is much cheaper than the other
two. Figure 10 shows the average unit costs for each alternative, and
Figure 11 is a cumulative cost curve for each scheme. The total cost for
Scheme I is about $1.13 billion and $1.8 and $2.4 billion for schemes II and
III, respectively.
27
-------
TABLE 9
DALLAS WATER UTILITY'S
YEARLY WATER REQUIREMENTS AT TIVE-YEAR INTERVALS
(mil gal)
1980 1985 1990 1_99J5 2000 2005 2010 2015 2020 2025 2030 2035 2040 2045 2050
Water
Demanded 105,851 125,925 147,824 171,551 189,801 208,049 229,949 244,551 259,151 270,100 284,700 293,825 306 600 317 551 326 676
(Consumed) (79,388) (94,444)(110,868)(128,663)(142,351)(156,037)(172,462)(183,413)(194,363)(202,575)(213,525)(220,369)(229\950)(238|l63)(245io07)
Available
Supply 105,851 109,513 113,149 105,851 105,851 107,675 107,675 109,500 109,500 109,500 111,325 111,325 111,325 113,151 113,151
Excess of
Demand over
Supply ° 16,412 34,675 65,700 83.750 100,374 122,274 135,051 149,651 160,600 172,775 182,500 195,275 204,400 213,525
Water
Recycled 52,925 62,962 73,912 85,776 94,900 104,024 114,974 122,276 129,576 135,050 142,350 146,912 153,300 158,776 163,338
Augmented
Supply 158,776 172,476 187,061 191,626 200,752 211,670 222,650 231,776 239,076 244,550 253,675 258,238 264,625 271 926 276,489
Augmented
Surplus 52,925 46,551 39,237 20,075 10,951 3,621 7,299 12,775 20,075 25,550 31,025 35,542 41,975 46,625 50,187
-------
TABLE 10
Scheme
1980
1985
ANNUAL OPERATING AND CAPITAL COSTS FOR DALLAS WATER UTILITY
(Thousand $)*
1990
1995
2000
2005
2010
2015
2020
2025
2030
2035
Annual
Scheme
Cost
I
II
III
7,120 7,761 7,761 13,575 14,211 18,610
11,750 18,510 25,270 25,270 25,270 27,012
13,141 22,923 32,705 33,891 33,891 35,633
16,915
27,802
38,683
16,715
28,702
37,986
20,383
25,957
33,644
22,336
25,957
32,800
18,648
25,957
32,800
18,574
31,455
41,320
17,957
29,069
37,337
17,957
29,069
37,337
16,478
29,069
37,337
Total
Annual
Supply
Cost
I
II
III
8,278
12,908
14,299
8,919
19,668
24,081
8,919
26,428
33,863
14,733
26,428
35,049
15,369
26,428
35,049
19,768
28,170
36,791
18,073
28,960
39,841
17,873
29,860
39,144
21,541
27,115
34,802
23,494
27,115
33,958
19,806
27,115
33,958
19,732
32,613
42,478
19,015
30,227
38,495
19,115 17,636
30,227 30,227
38,495 38,495
* 1973 price level.
Includes cost of existing supply (1,158,000).
-------
TABLE 11
COST PER MILLION GALLONS OF BILLED CONSUMPTION FOR DALLAS WATER UTILITY*
Scheme
Total Supply I
Cost S/mll gal
Billed
Consumption** III
1980
1985
1990
1995
2000
2005
2010
2015
2020
2025
2030
2035
2040
2045
2050
104.27 94.44 80.45 114.51 107.97 126.69 104.79 97.45 110.83 115.98 92.76 89.54 82.69 80.26 71.98
162.59 208.25 238.37 205.40 185.65 180.53 167.92 162.80 139.51 133.85 126.99 147.99 131.45 126.92 123.37
180.12 254.98 305.44 272.41 246.22 235.78 231.01 213.42 179.05 167.63 159.04 192.76 167.41 161.63 157.12
OJ
o
Recycled
Water
Cost***
II 296.01 391.98 455.86 392.81 335.04 346.22
III 331.06 485.43 589.98 526.81 476.16 456.72
* 1973 price level.
** Equal to the annual supply cost divided by millions of gallons billed consumption.
*** Equal to scheme cost divided by recycled water billed consumption. This cost is not calculated after 2005 because of transmission
facilities and reservoirs which are not related to wastewater transmission or treatment.
-------
50
40
cc
30
U_
O
CO
20
10
1975 1980 1990
2000 2010 2020
YEAR
2030
SCHEME III
SCHEME II
SCHEME I
2040 2050
FIG. 9 TOTAL COSTS FOR DALLAS WATER SUPPLY
-------
(0
o>
U)
ho
900
800
700
600
500
400
300
200
100
SCHEME III
1980 1990 2000 2010 2020 2030 2040 2050
YEAR
FIG. 10 AVERAGE UNIT COSTS FOR DALLAS WATER SUPPLY
-------
2.5
2.0
CO
cc
o
O 1.5
(0
z
0.5
SCHEME III
II
xxx $2,372,638,000
$1,822,667,000
$1,127,161,000
80 90 00 10 20 30 40 50
YEAR
FIG. 11 CUMULATIVE COSTS FOR DALLAS WATER UTILITY
-------
SAN DIEGO WATER UTILITY
The City of San Diego is located in San Diego County which makes up the
entire San Diego SMSA. San Diego's population is 697,027 and the County's
population is 1,357,854, based on the 1970 census. The retail service area
for the water is made up of the City of San Diego with the exception of the
South Bay area and a small number of retail customers within San Diego
County. Table 12 summarizes some important statistics for the utility.
Organizationally, the water utility is composed of the Systems, Water
Quality, and Services Division. It is responsible for both water and waste-
water functions, but separate accounts are maintained for water and waste-
water revenues and expenses.
There are no permanent streams or natural lakes anywhere in the area,
nor are there any extensive ground water sources. For this reason, San
Diego has developed a system of impounding reservoirs which are divided into
three geographical districts. These reservoirs provide storage for not only
local run-off, but also water which flows down from the north through the two
aqueducts (Appendix B). In 1974, 89.4 percent of the water used by the
utility was imported from the Colorado River. This percentage will drop as
more and more water is imported from the Feather River project in northern
California.
Water is treated by three plants: the Alvarado plant, located at the
Murray Reservoir; the Miramar plant, located at Miramar Reservoir; and the
Otay plant, located at the Otay Reservoir. The plants have a capacity of 66,
40, and 15 mgd, respectively.
Figure 12 depicts the growth in consumer demand for water from 1964
through 1974. As discussed earlier, "treated" water is the amount of water
that was pumped from the city's three water treatment plants. "Revenue-
producing" water is the water which was measured as metered consumption and
paid for by wholesale and retail customers of the water utility.
Cost Evaluation
As with the Dallas water utility, the productivity base for cost and
economic evaluation is revenue-producing water. It can be seen from Fig-
ure 12 that in 1974 the utility produced nearly 47 bil gal of such water.
Table 13 summarizes costs for the major categories of acquisition, treatment,
transmission and distribution, and power and pumping, for the period from
1964 through 1974.
34
-------
TABLE 12
SUMMARY STATISTICS FOR SAN DIEGO WATER UTILITY (1974)
Population
SMSA 1,562,100
County 1,562,100
Retail Service Area 761,916
Area of Retail Service Area (sq. miles) Not available
Number of meters in recognized customer classes
Single family domestic 139,378
Other domestic 24,953
Commercial 6,325
Industrial 234
Combined irrig. & domestic 42
Outside city services 60
Other utilities 5
Fire service 913
Flat rate (number of accounts) 135
Percent metered 100
Purchased water (mil gal/yr) 4,074
Source water 100% surface impoundments
Pipe in system - miles 1,968
Elevation of treatment plants - ft. above mean sea level
Alvarado 536
Otay 521
Miramar 715
Elevation of service area (min/max) ft. 10/1020
Revenue-producing water (billed consumption in mil gal) 47,205
Treated water (flow from treatment plants in mil gal) 52,436
Maximum day/maximum hour - mgd 212.61/N.A.
35
-------
75
70
65
Z 60
o
555
& 50
U.
O 45
Z 40
O
d "
30
25
20
TREATED
WATER
REVENUE PRODUCING
WATER
1964 65 66 67 68 69 1970 71 72 73 74
YEARS
FIG. 12 TREATED VS. REVENUE PRODUCING
WATER FLOW FOR SAN DIEGO
WATER UTILITY
36
-------
Cost categories utilized in this analysis are the same as those defined
for Dallas. In addition, acquisition costs include: payments in lieu of
taxes to the County and Metropolitan Water District of Southern California;
purchase of water from the Metropolitan Water District through the County
Authority; and impounding and transmission expenses.
To establish a base for productivity, the operating costs in Table 13
were divided by the millions of gallons of revenue-producing water to yield
unit costs. The total cost of operation increased from $9,457,496 in 1965 to
$21,228,851 in 1974, but increased only from $311.36/mil gal to $449.71/mil
gal during the same period. The Support Services and the Acquisition func-
tions increased from 17.84 to 20.82 percent, and 55.43 to 60.91 percent of
total cost, respectively.
Since the total cost of producing water includes both operating and
capital expenses, it is important to include both in a cost analysis. There-
fore, Table 13 contains the costs for operations, depreciation of capital
equipment, and interest. As discussed earlier, the depreciation represents
the annual depreciation of the net plant in service in terms of the original
purchase price. Interest is the total interest paid in a given year. All of
the bonds issued for major plant additions have been financed by revenue bonds
since 1952. It can be easily seen from the table that operating expense is
increasing at a much faster rate than is capital cost.
Renovated Wastewater Analysis
In this analysis, the alternative of purchasing all additional water
from the Metropolitan Water District of Southern California versus 50 percent
wastewater reuse (based on water demand) in addition to buying make-up water
from the Water District, is considered. The wastewater reuse schemes are as
follows: purchasing water from the aqueduct is Scheme I; Scheme II is return-
ing treated water to the existing reservoirs; and Scheme III is pumping
renovated wastewater directly into the headworks of the water treatment plants.
Population growth trends within the San Diego service area have been trans-
lated into increased water demand as shown in Figure 13. It is assumed in
Figure 13 that water demand will increase at a rate of 5.0 percent per year
until 1990 and then at a rate of 3.3 percent annually through the year 2000,
which is the termination point of this analysis. Correspondingly, the
average daily demand for treated water will increase from 150 to 450 mgd
between 1974 and 2000. The utility currently plans to meet this demand by
purchasing additional water from the Metropolitan Water District of Southern
California.
In Figure 13 the solid line represents anticipated demand and the
dotted line represents existing supplies of approximately 160 mgd, which will
cross the demand line in 1976. The water purchased from the aqueduct in 1976
plus the local water from streams and rainfall is included in the existing
supply. It is the incremental demand above existing supplies from 1976
through the year 2000 which will be examined in this analysis. First con-
sideration will be given to purchasing additional water from the Metropolitan
Water District of Southern California. All cost calculations are based on
1973-74 dollars.
37
-------
LO
00
TABLE 13
SUMMARY OF OPERATING AND CAPITAL EXPENDITURES FOR 1965-1974
FOR SAN DIEGO WATER UTILITY
Item
Support services
million $
% of total
$/mil gal*
Acquisition
million $
% of total
$/mil gal-
Purification
million $
% of total
$/mil gal*
Transmission and
distribution
million $
% of total
$/mil gal*
Total operating
costs
million $
$/mil gal*
Depreciation
million $
Interest
million $
Total capital
costs
million $
Total operating
and capital costs
million $
$/mil gal*
1965
1.
17.
55.
5.
55.
172.
.
5.
17.
2.
21.
66.
9.
311.
2.
.
3.
12.
417.
697
84
56
242
43
60
533
64
55
024
41
65
457
36
573
665
237
695
96
1966
1.711
18.29
52.69
5.141
54.96
158.33
.520
5.55
16.00
1.982
21.19
61.05
9.354
188.07
2.496
.622
3.118
12.472
384.13
1967
1.974
20.05
60.10
5.373
54.58
163.60
.493
5.00
15.00
2.004
20.36
61.02
9.843
299.72
2.527
.580
3.107
12.950
394.32
1968
2.212
20.28
63.04
5.985
54.36
170.59
.539
4.94
15.36
2.172
19.92
61.92
10,908
310.91
2.676
.539
3.215
14.124
402.55
1969
2.675
19.44
71.66
8.213
59.61
220.01
.641
4.66
17.18
2.230
16.21
59.74
13.759
368.59
2.627
.499
3.126
16.885
452.32
1970
2.767
19.31
69.39
8.641
60.31
216.70
.725
5.06
18.19
2.195
15.32
55.05
14,329
359.33
2.812
.459
3.271
17.700
441.38
1971
3.086
19.37
73.67
9.651
60.56
230.36
.748
4.69
17.84
2.453
15.39
58.53
15,937
380.40
2.532
.422
2.954
18.891
450.94
1972
3,288
16.76
71.30
12.612
65.16
277.29
.806
4.17
17.73
2.648
13.68
58.21
19,354
425.53
2.769
.385
3.154
22.508
494.86
1973
3.861
17.59
88.22
14.423
65.70
329.58
,913
4.16
20.87
2.757
12,56
62.99
21,955
501.66
2.579
.351
2.929
24.834
568.60
1974
4.419
20.82
93.62
12.930
60.91
273.90
1.056
4.97
22.37
2.824
13.30
59.82
21,229
449.71
2.779
.318
3.096
24.325
515.31
-------
500
Q
O
O
z
LLJ
Q
400
300
Q.
Q. 200
100
TOTAL AVERAGE
DAY DEMAND
AVAILABLE SUPPLY
o
rs
o-
o
oo
o
o
o
ex
YEAR
FIG. 13 SAN DIEGO LONG RANGE WATER
SUPPLY STUDY; SCHEME I
39
-------
Table 14 contains historical costs for San Diego's purchased water in
1971-1974 which range from $138.30/mil gal to $172.48. These costs are
expected to increase by $46.03/mil gal. Between 1977-2000, the San Diego
utility will purchase 1 bil gal in addition to its existing annual supply
of 59,202 mil gal (the 1976 demand). This additional water will cost almost
$243 million in 1974 dollars, based on the following assumptions:
A $46.03/mil gal (Northern California water) increase will take
place for water used between 1977-2000;
Equal amounts of water from Colorado will be mixed and will cost
$195.50/mil gal until 1990;
Water will be mixed between 1990-2000 as follows:
30% Colorado ) or $204-70/mil x
70% California)
This purchase of additional water (Scheme I) is compared against two
other schemes, in which it is assumed that 50 percent of the water demand is
met by using renovated wastewater that is either returned to existing reser-
voirs (Scheme II) or returned directly to the headworks of the water treat-
ment plants (Scheme III). The curve in Figure 14 illustrates the impact
which 50 percent wastewater reuse will have on extending the available water
supply. It can be seen that with 50 percent reuse the available supply does
not cross the demand curve until 1990. Prior to that time reuse will actually
create a surplus of water, thus reducing the amount of water that must be
purchased.
Scheme II considers collecting wastewater equivalent to 50 percent of
demand and repumping it into existing reservoirs after treating it to
acceptable levels for water supply use. Scheme III assumes that the waste-
water is treated to a much higher level and is pumped directly into the
headworks of water treatment plant. Both reuse schemes are assumed to
supplement existing waste treatment, which is a 100-mgd nitrifying activated
sludge plant that must meet the following requirements:
BOD - 30 mg/1
Suspended Solids - 30 mg/1
Coliform - 200/100 ml
Reservoirs will provide at least 50 percent dilution and storage time for
some additional purification in Scheme II. Demineralization is required to
reduce total dissolved solids from about 1200 (wastewater) to 800 mg/1
(Colorado River) in both schemes. The waste treatment processes and the
capital and operating costs associated with a 100-mgd plant required to
satisfy the treatment requirements of schemes II and III are shown in tables
15 and 16. The analysis for wastewater renovation assumes that when the
amount of wastewater plus existing supplies does not meet the demand, a new
100-mgd advanced waste treatment plant is built. To annualize the capital
costs of these plants, a capital recovery factor of 0.0651 is used, which
40
-------
TABLE 14
HISTORICAL COSTS FOR WATER PURCHASED BY SAN DIEGO UTILITY
Year mil gal Cost $/mil gal
1971 35,990.5 4,977,608 138.30
1972 47,338.6 7,128,061 150.57
1973 53,834.3 8,773,772 162.97
1974 40,737.8 7,026,638 172.48
41
-------
Q
O 500
400
LU
O
O.
a.
D
300
200
100
TOTAL AVERAGE
DAY DEMAND
AVAILABLE SUPPLY WITH
50% WASTEWATER REUSE!
O
ts
O
co
o>
O
O
O
YEAR
FIG. 14 SAN DIEGO LONG RANGE WATER
SUPPLY STUDY; SCHEMES II AND III
42
-------
TABLE 15
PROCESSES AND COSTS FOR WASTEWATER RENOVATION SCHEME II
IN SAN DIEGO
-, „ Operating &
Capital Cost .. .
, Maintenance
Treatment Process (10 $) ($/l,000 gal)
Two-Stage Lime Clarification 9.8 0.046
Nitrification 8.4 0.009
Mixed Media Filtration 5.2 0.018
Granular Activated Carbon 22.7 0.025
(15-min. detention time)
Reverse Osmosis (42 mgd)
brine disposal cost not included 35.3 0.181
43
-------
TABLE 16
PROCESSES AND COSTS FOR WASTEWATER RENOVATION SCHEME III
IN SAN DIEGO
Capital Cost Operating &
, Maintenance
Treatment Process (10 $) ($/l,000 gal)
Two-Stage Lime Clarification 9.8 0.046
Nitrification 8.4 0.009
Mixed Media Filtration 5.2 0.018
Granular Activated Carbon 27.2 0.046
(40 min. detention time)
Reverse Osmosis (42 mgd) 35.3 0.181
brine disposal not included
44
-------
assumes a facility life of 30 years and an interest rate of 5 percent.
Table 17 contains the demand information for San Diego with the demand
reduced to consumption in parentheses (consumption = 0.992 (demand)).
Tables 18 and 19 summarize the total facility requirements for schemes II
and III.
Figure 15 represents a time-investment diagram for Scheme II in which
the bottom line is the cost of the renovated wastewater treatment system.
The top line includes costs for the total system, including pumping and
transmission facilities. Figure 16 is a time-investment diagram for Scheme
III. The bottom line is the cost for the wastewater treatment facilities
and the top is the cost of all of the facilities required to implement
Scheme III. Figure 17 is a total cost curve for all three alternatives for
the period 1976 through the year 2000.
Comparison of Schemes: Both of the reuse schemes are based on the
assumption that 50 percent of the demand water is recycled water. As
explained earlier, demand and consumption have been defined as two different
concepts.
The annual costs for each scheme are shown in lines 1 through 3 of
Table 20, and line 4 contains the credits resulting from the replacement of
aqueduct by recycled water. Total annual supply costs are given in lines
5 through 8. Table 21 contains the unit costs ($/mil gal) for each scheme.
Figure 17 is the time-investment diagram for the total cost associated with
all three figures. Figure 18 depicts the average unit costs for each scheme
and Figure 19 shows the cumulative cost for each scheme.
45
-------
50
-------
TABLE 17
SAN DIEGO WATER UTILITY YEARLY WATER REQUIREMENTS AT FIVE-YEAR INTERVALS
(mil gal)
1980 1985 1990 1995 2000
Water Demanded
Available Supply
Excess Demand Over
Supply
Water Recycled
Augmented Supply
Reduction in Purchased
Water from Aqueduct 23,149 13,220 592
71,732
(63,268)
59,015
13,717
35,866
94,881
91,591
(80,748)
59,015
32,576
45,796
104,811
116,845
(103,057)
59,015
57,830
58,422
117,437
137,439
(121,221)
59,015
78,424
68,720
127,735
161,663
(142,587)
59,015
102,648
80,832
139,847
-------
TABLE 18
COST ESTIMATE FOR SCHEME II WASTEWATER REUSE PLAN*
00
Facility
SOURCE
(San Diego Point)
Loma WTP
TRANSMISSION
Pt Loma - Otay
Pt Loma - Miramar
WASTEWATER PLANTS
1
2
3
Year
of
Need
1977
1977
1977
1977
1981
1997
Capital Cost
Supply per Year
(mgd) ($ 1000)
50% of water
demanded
120 1,306
120 1,012
100 5,299
100 5,299
100 5,299
Capital Cost
Recovery
Period
30
30
30
30
30
Operating Cost
per Year
($ 1000)
529
410
10,184
10,184
10,184
* 1973 Price Level
-------
TABLE 19
COST ESTIMATE FOR SCHEME III WASTEWATER REUSE PLAN*
Facility
SOURCE
(San Diego Point)
Loma WTP
TRANSMISSION
Pt Loma - Otay
Pt Loma - Miramar
WASTEWATER PLANTS
(3 100 mgd)
Year
of
Need
1977
1977
1977
1977
1981
1997
Capital Cost
Supply per Year
(mgd) ($ 1000)
50% Raw Supply
120 1,306
120 1,012
100 5,592
100 5,592
100 5,592
Capital Cost
Recovery
Period
Operating Cost
per Year
($ 1000)
30
30
30
30
30
529
410
12,410
12,410
12,410
* 1973 Price Level
-------
TABLE 20
ANNUAL SCHEME COST FOR SAN DIEGO WATER UTILITY*
($ 1000)
Scheme 1980 1985 1990 1995 2000
Annual Scheme Cost
Water Purchase Adjust-
ment
o Total Annual Supply
Cost
I
II
III
II &
III
I
II
III
2,487
18,741
21,260
-4,526
19,127
30,855
33,374
6,361
34,224
39,262
-2,589
23,001
48,275
53,313
11,308
32,224
39,260
- 116
27,948
48,748
55,784
16,056
34,224
39,260
+1,987
32,696
52,851
57,887
21,016
49,706
57,264
+4,467
37,656
70,813
78,371
* 1973-74 price level
-------
TOTAL COST
so r
U.
O
30
20
10
I
WASTE
TREATMENT
COST
1975
1980
1985 1990 1995 2000
YEAR
FIG. 16 TIME-INVESTMENT DIAGRAM FOR SCHEME III
-------
SCHEME III
Ul
O
O
u_
o
CO
z
o
501-
40
30
20
10
1975
I
(SCHEME II
SCHEME I
1995
2000
1980 1985 1990
YEAR
FIG. 17 TOTAL TIME-INVESTMENT COST DIAGRAMS
FOR SCHEMES I, II, AND III.
Purchased water savings for Schemes II and III are not
shown
-------
900
800
700
~CO 600
0>
^ 500
400
300
200
100
^^ SCHEME III
SCHEME II
SCHEME I
75
80
95
2000
85 90
YEAR
FIG. 18 AVERAGE UNIT COST FOR SCHEMES I, II, AND III
-------
TABLE 21
COST PER MILLION GALLONS BILLED CONSUMPTION FOR SAN DIEGO WATER UTILITY*
Scheme 1980 1985 1990 1995 2000
Total Supply Cost
Oi
I
II
III
302.32
487.69
527.50
284.85
597.85
660.24
271.19
473.02
541.29
269.72
435.99
477.53
264.09
496.63
549.64
Recycled Water Cost II 592.43 847.67 625.37 564.65 697.20
III 672.06 972.46 761.92 647.74 803.21
* 1973-74 Price Level
-------
01
Ln
-------
FINANCING ALTERNATIVES
Several comments must be made concerning the type of financing associated
with the renovated wastewater systems discussed in the report. In Dallas, the
cost of schemes II and III as compared to Scheme I is the cost which Dallas
will be assessed by the Corps of Engineers for its share in a comprehensive
reservoir development program. Such a program will include recreation, flood
control and navigation, and water supply as only one of several multi-purpose
objectives. A cost analysis was made for a single-purpose water supply use,
and it was determined that the cost per million gallons to Dallas would be
approximately the same no matter which alternative was chosen (piggy-back on
Corps of Engineers project or go it alone). For example, as mentioned
earlier, for four of the six reservoirs in Scheme I a reservoir life was
assumed as 50 years, with an interest rate of 3.225 percent, based on Corps
of Engineers financing. If Dallas had chosen to construct Scheme I itself,
the write-off period for reservoir life might have been closer to 30 years at
an interest rate of approximately 6 percent. The annualized interest cost
over the period of analysis would probably have been equivalent. However,
for convenience and ease of financing, Dallas decided to become part of a
larger comprehensive project. In general, however, single-purpose reservoir
development can be more expensive than the proportionate share of a multi-
purpose development.
Another financing consideration is the possible use of 75 percent
matching U. S. Environmental Protection Agency construction funds to pay the
capital cost of the wastewater renovation plants. Tables 22 and 23 summarize
the costs for schemes I, II, and III with 75 percent matching grants for
capital costs. Obviously, since no construction is required in Scheme I,
these costs would not change but the grant reduces Scheme II in Dallas from
$1,822,667,000 to $1,538,559,000 and Scheme III from $2,372,638,000 to
$1,923,241,000. In San Diego, the cost for Scheme II would be reduced from
$747,173,030 to $568,327,055 and the cost for Scheme III would be reduced
from $860,544,230 to $670,814,230. The unit cost for Scheme I would drop
since the currently available fixed facilities would be used more efficiently.
All of the costs shown in tables 22 and 23 are based on a relationship
between water demanded and revenue-producing water from Dallas of 0.75 and
for San Diego of 0.83.
56
-------
TABLE 22
COMPARATIVE AVERAGE COSTS FOR DALLAS WITH
75% EPA FINANCING
Increase Over
Cost of Function ($/mil gal) Existing System
Scheme
I
II
III
Acquisition
104
138
174
.66
.97
.29
Treatment
51
51
51
.70
.70
.70
Distribution Other
119.
119.
119.
91
91
91
141.47
141.47
141.47
Total %
417
451
487
.44
.75
.07
23.
33.
44.
5
7
1
Note: See Table 24 for comparison of cost without 75% EPA financing.
TABLE 23
COMPARATIVE AVERAGE COSTS FOR SAN DIEGO WITH
75% EPA FINANCING
Increase(Decrease)
Cost of Function ($/mil gal Over Existing
Scheme Acquisition Treatment Distribution Other Total System (%)
I 261.99 27.47 105.86 102.37 497.96 (3.4)
II 410.91 27.47 105.86 102.37 646.91 25.5
III 459.29 27.47 105.86 102.37 694.99 34.9
Note: See Table 25 for comparison of cost without 75% EPA financing
57
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ATTITUDES TOWARD REUSE
Economic costs reflect only a part of the reuse picture. A more
important issue regarding reuse is the attitude of the water utility
managers and consumers toward reusing wastewater. As part of the cost
evaluation performed in this study, a telephone survey was made of selected
utilities in regions VI (Dallas) and IX (San Diego). The results of the
survey are presented in Appendix C. For a group of selected cities a survey
was conducted which identified the physical characteristics of the utilities,
and their current use of wastewater. Questions were asked of the utility
managers regarding their attitudes toward the limited use of wastewater and
the results of these questions are reported in Appendix C.
58
-------
SUMMARY AND CONCLUSIONS
Standardized costs for the Dallas and San Diego water utilities have
been developed. Using these costs, a comparison has been made for each
utility which tests the possibility of using renovated wastewater as a
supplement to water supply sources. Tables 24 and 25 summarize the costs
associated with the current water supply as well as with alternatives I, II,
and III. For both tables line 1 gives the acquisition, treatment, distribu-
tion, and other costs associated with the current water supply system.
Lines 2, 3, and 4 contain the costs associated with schemes I, II, and III.
For Dallas it can be seen that when Scheme I is implemented, it will increase
the total cost for water by only 23.5 percent. If Scheme II were chosen, it
can be seen that although the acquisition cost increases by 624.5 percent,
the total cost differential increases by only 46.5 percent. Similar results
occur in San Diego.
The purpose of this report is to present data from two selected case
study utilities in order to make an economic comparison of renovated waste-
water as a water supply source. Data from the analyses will be specifically
useful to the utilities cited. However, in a broader context, the report
should emphasize the need for uniform and standardized data analysis proce-
dures in making such comparisons. It also makes the cost of using renovated
wastewater explicit. It is obviously not a cheap alternative. On the other
hand, it will allow the utility manager the opportunity to make a rational
decision (where appropriate) as to whether he wishes to control his reuse
option or, as in the case of many communities, be subject to random
influences.
59
-------
TABLE 24
COMPARATIVE AVERAGE COSTS FOR SCHEMES I, II, and III IN DALLAS
Increase(Decrease)
Cost of Function ($/mil gal) Over Existing
Scheme Acquisition Treatment Distribution Other Total System (%)
Existing
System 25.17 51.70 119.91 141.17 337.95
I 104.66 51.70 119.91 141.17 417.44 23.5
II 182.35 51.70 119.91 141.17 495.13 46.5
III 242.91 51.70 119.91 141.17 555.69 64.4
COMPARATIVE AVERAGE COSTS
TABLE 25
FOR SCHEMES I, II, AND III IN
SAN DIEGO
Increase (Deer ease)
Over Existing
Cost of Function ($/mil
Scheme Acquisition
Existing
System 279.61
I 261.99
II 494.53
III 547.53
Treatment
27.47
27.47
27.47
27.47
Distribution
105,86
105.86
105.86
105.86
gal)
Other
102.37
102.37
102.37
102.37
System (%)
Total
515.31
497.96
730.23
783.23
—
(3.4)
41.7
52.0
60
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ACKNOWLEDGMENTS
The authors would like to acknowledge the following individuals for
their assistance in preparing this report: John N. English, Wastewater
Research Division, Municipal Environmental Research Laboratory, and Herbert
R. Pahren, Water Quality Division, Health Effects Research Laboratory,
U. S. Environmental Protection Agency, Cincinnati, Ohio, 45268; Dan Keller,
U. S. Army Corps of Engineers, Cincinnati, Ohio; Henry Grasier, Director,
and Robert Ford, Deputy Director, Dallas Water Utility, Dallas, Texas; and
Ernest Clay, Deputy Director, San Diego Water Utility, San Diego, California.
The study effort was accomplished through EPA contract No. 68-03-2071.
61
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REFERENCES
1. Clark, R. M., "Cost and Pricing Relationships in Water Supply," to be
published in the Journal of the Environmental Engineering Division,
American Society of Civil Engineers.
2. Clark, R. M., and Goddard, H. G., "Pricing for Water Supply: Its
Impact on Systems Management," Environmental Health Effects Research
Series, EPA-1 670/1-74-001, April 1974, National Environmental Research
Center, Office of Research and Development, U. S. Environmental Protec-
tion Agency, Cincinnati, Ohio 45268.
3. Clark, R. M., Stevie, R., and Trygg, G., "The Cost of Municipal Water
Supply: A Case Study," to be published as an EPA report, Water Supply
Research Division, Municipal Environmental Research Laboratory, U. S.
Environmental Protection Agency, Cincinnati, Ohio 45268.
4. Federal Register, "Water Resources Council Water and Related Land
Resources, Establishment of Principles and Standards for Planning,"
Monday, September 10, 1973, Washington, D. C., Vol. 38, No. 174, Part 111.
5. Public Law 92-500, Amendments to the Federal Water Pollution Control
Act, 92nd Congress, Washington, D. C.
6. Public Law 93-523, Safe Drinking Water Act, 93rd Congress, Washington,
D. C. (Dec. 16, 1974).
7. U. S. Army Corps of Engineers, "Phase 1 (Simplified) Plan Formulation
General Design Memorandum, Big Walnut Lake, White River Basin, Big
Walnut Creek, Indiana, Design Memorandum No. 1," prepared by U. S. Army
Engineers District, Louisville Corps of Engineers, October 1974.
62
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APPENDIX A
DALLAS WATER UTILITY
The City of Dallas lies within Dallas County which is in north central
Texas. The city has a population of 942,462. The county's population is
1,549,221. These figures are based on the 1970 census. The Dallas metro-
politan area is growing at the rate of 3.1 percent per year. This growth
rate has many implications for urban services, such as water supply.
Water Supply Service Area
The Dallas Water Utility provides water on a retail basis to all
classes of customers within the City's five service areas (Figure A-l).
Treated water is supplied to 19 cities within Dallas County (locally referred
to as "county towns") and also to the Dallas-Fort Worth Regional Airport.
Some water is also sold to communities outside Dallas County. Service is
provided to each of these cities through one or more master meters and con-
tracts are negotiated individually by the Utility with each "county town"
or water service area. The contracts are from one to 50 years duration with
20 and 30 year contracts being most common. Total consumption for the cus-
tomer cities and the airport in 1974 was 12,438 mil gal, or around 20 per-
cent of the total metered consumption for the utility. Table A-l contains
a listing of the Dallas service area and customer towns.
The population within Dallas County is increasing at a rapid rate, a
trend which is expected to continue. A great deal of emphasis is placed on
meeting the treated water supply needs of the Dallas county towns as they
turn to the Dallas Water Utility for additional water. At the present time,
financing and developing new reservoirs are of primary concern for the
utility.
Organization
Organizationally, the Dallas Water Utility combines both the Water
Supply and Wastewater Treatment functions. The accounting systems for these
two operations are also combined, requiring that at those points where over-
lap in fuction occurs, an estimate be made of the costs which must be
assigned to each operation. The organizational structure depicted in Fig-
ure A-2 is composed of the Engineering and Planning, Operations, and
Business sections.
63
-------
FIG.A-1 DALLAS WATER UTILITIES-SERVICE AREA
64
-------
DIRECTOR
ON
Oi
1
ENGINEERING
& PLANNING
1
WATER
OPERATIONS
RESERVOIRS
PURIFICATION
PUMPING
DISTRIBUTION
OPERATIONS
WASTEWATER
OPERATIONS
COLLECTION
TREATMENT
1
1
BUSINESS
1
SUPPORT
SERVICES
MAINTENANCE
STORES
METER SHOP
CONSTRUCTION
WATER & SEWER
STRUCTURAL
FIG. A-2 ORGANIZATION OF DALLAS, TEXAS WATER UTILITY
-------
TABLE A-l
WATER SERVICE AREAS FOR DALLAS WATER UTILITY
City of Dallas
Service Areas
A North High
B East High
C Central Low
D South High
E Trinity Heights -
Cedardale Intermediate
Customer Cities
Outside Dallas
1 Sunnyvale
2 Balch Springs
3 Kleberg
4 Rylie
5 Seagoville
6 Hutchins
7 Wilmer
8 Lancaster
9 Woodland Hills
10 DeSoto
11 Cedar Hill
12 Duncanville
13 Grand Prairie
14 Irving
15 Regional Airport
16 Coppell
17 Carrollton
18 Farmers Branch
19 Addison
20 Richardson
66
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The Engineering and Planning Section plans all system improvements and
analyzes pumpage, flow, and consumption data to evaluate the adequacy of the
system. It coordinates the development of long range plans with engineering
consultants. The Business Section is responsible for accounting and collect-
ing for the utility, and other elements within the section are responsible
for meter reading and billing.
The Operations Section is made up of four divisions, of which the Water
Operations Division is the largest. All water production and distribution
functions are handled by this division. The Wastewater Operations Division
is responsible for the collection and treatment of wastewater. The Support
Services Division maintains equipment and meters, and is responsible for
storage of spare parts. The Construction Division supervises the installa-
tion of additions to the system.
All three sections handle both wastewater and water supply responsi-
bilities through the division level. The only division which handles only
water supply is the Water Operations Division. Separate costs are maintained
for both water and wastewater activities by the Business Section.
Acquisition
Raw water comes from five major reservoirs and is treated in treatment
plants located in the northwest, central, and southeastern section of the
city. The treatment plants are located generally in the low-lying areas,
thus requiring that water be pumped up to residences and businesses located
at higher elevations. The raw water reservoirs are shown in Figure A-3.
Dallas paid $5.5 million toward the cost of dams to be built at Lewis-
ville on the Elm Fork of the Trinity River, and at Grapevine on Denton Creek.
The remaining construction costs for the dam were paid by the Federal Govern-
ment. In return, the Federal Government reserved 163 bil gal of water in
Garza-Little Elm and Grapevile reservoirs exclusively for Dallas' use.
Lavon Reservoir is operated by the North Texas Municipal Water District
with whom Dallas has a contract under which an average of 10 mgd of treated
water will be furnished to the northeast section of the city at the Casa
View pump station until 1991.
Lake Ray Hubbard on the East Fork of the Trinity River has a capacity
of 181 bil gal. It was built for water supply only and is owned entirely
by Dallas.
Lake Tawakoni is located on the Sabine River, and lies in an entirely
different water shed than Dallas. The reservoir and dam were built by
Dallas and the Corps of Engineers, and turned over to the Sabine River
Authority, in return for 80 percent of the water yield. The lake normally
holds 306 bil gal.
Waters from the Garza-Little Elm and Grapevine reservoirs flow in
natural channels to points near the Backman and Elm Fork treatment plants.
67
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LAKE TAWAKONI
AUBREY
ON
00
GARZA-LITTLE ELM
ROANOKE
GRAPEVINE
LA VON
LAKE RAY HUBBARD
LAKE JUNE
EXISTING RESERVOIRS
PROPOSED RESERVOIRS
MOUNTAIN CREEK
FIG. A-3 PROPOSED AND EXISTING RESERVOIRS
FOR DALLAS WATER UTILITY
-------
At these plants, the raw water is removed from the channel by pumps located
in the treatment facility.
Water from Lake Hubbard is pumped directly to the East Side treatment
plant by a remote pump station which is controlled by the treatment plant.
Water from Lake Tawakoni is pumped 18 miles through a 60-inch pipe line
to a 266 mil gal interim reservoir located on the ridge separating the Sabine
and East Fork water sheds. The water then flows by gravity to the East Side
treatment plant.
Purification
Raw water is treated at Elm Fork, Bachman, and East Side. Each facility
was constructed at a different time in response to increasing demands.
The Elm Fork treatment plant, which is about four miles northwest of
the city, was completed in 1952, and has a capacity of 196 mgd. It is
equipped with activated carbon facilities, in addition to chlorinators, pri-
mary and secondary flocculators, and settling tanks. It also houses a 13.2
mil gal clear well storage facility. On-site pumping facilities include
five 30 mgd at 58 ft. of head low-service pumps, four 30 mgd, and one 15 mgd
at 280 ft. discharge head, high-service pumps, plus additional wash-water
pumps. The high-service pumps put water directly into the distribution
system.
The Bachman purification plant, which is located within the city limits,
was completed in 1930 and has a capacity of 116 mgd. Its design is similar
to that of Elm Fork but it has no secondary flocculators. The plant has four
centrifugal water pumps, 14 high-service pumps, and one wash-water pump.
The clear wells at Bachman have a total capacity of 20 mil gal, and the high-
service pumps put water directly into the distribution system.
The East Side treatment plant, which is about five miles east of the
city limits, was completed in 1964. Its design capacity is 205 mgd, and it
has flocculators, primary clarifiers, secondary settling basins, and filters.
There are no low-service pumps located at the plant, because water flows from
the interim reservoir by gravity.
Chemical Treatment Processes: Seven chemicals are fed into the plants in
proportion to the amount of water treated, but the quality of the raw water
affects the specific amount of each chemical used. The chemicals used,
their purpose, and the order of application are as follows:
1. Activated carbon: used to absorb organic matter and to control
taste and odor.
2. Chlorine: added in the initial phases of treatment to start
the process of killing bacteria, to prevent the growth of algae
in the basins, and to oxidize organic matter.
69
-------
3. Lime: serves as a softening agent, combines with other chemicals
to settle out suspended matter, and adjusts the alkalinity of the
water to make it less corrosive.
4. Ferric Sulfate: the chief clarifying agent; it combines with part
of the lime.
5. Fluosilicic Acid: is the fluoridating agent; it is added at the
end of the first stage of settling; if needed, more ferric sulfate
is added at this point.
6. Sodium Hexametaphosphate: added for scale and corrosion control.
7. Ammonia: is added as a disinfectant along with chlorine; it also
makes the taste of the chlorine less noticeable.
8. Additional chlorine is added.
Of the chemicals used, all of the carbon and ferric sulfate and nearly
all of the lime settle out in the plant as sludge. Most of the pre-chlorine
is consumed, a trace of the lime and the ammonia, post-chlorine, fluoride,
and hexametaphosphate remain in the water going to the consumer. The amounts
of chemicals used in 1972-73 are shown in Table A-2.
Transmission and Distribution
The distribution system consists of approximately 3,208 miles of mains,
composed of from 2- to 90-inch pipe. To direct the flow of water to the
proper areas and to control pressure, 32,000 valves have been installed.
There are eight elevated tanks in the system to provide pressure, together
with 10.5 mil gal of storage for peak demand periods. There is a difference
of about 360 feet in elevation between the areas along the river channel and
the surrounding hills.
The line from the East Side treatment plant is concrete pipe, 90 inches
in diameter, and goes to Lake June Reservoir. A small line goes on to South-
cliff Reservoir (not shown on map).
The Elm Fork plant pumps into a line to serve the city and it also serves
the City of Irving through a 40-in. pipe and Grant Prairie through a 36-in.
line beyond Irving.
The Bachman plant pumps into three 36-in. lines, which fan out over the
central part of the city into the business district and on to South Dallas.
Storage: Within the distribution system, nine ground reservoirs have a total
capacity of 141.87 mil gal. Each reservoir is paired with a high-pressure
pump station to boost water into the distribution system under enough pres-
sure to deliver it to the customer. The eight elevated storage tanks
provide: (1) slack in the system so that the pumps are not pumping against
a closed system and overheading; (2) an additional 10.5 mil gal of storage.
During hours of peak consumption, when it is impossible for booster pumps to
70
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TABLE A-2
CHEMICALS USED IN WATER TREATMENT - DALLAS WATER UTILITY (1972-73)
CHEMICAL Ib/mil gal mg/1
Lime 444 53
Ferric Sulfate 144 17
Carbon 44 5
Chlorine, Pre- 37 4
Chlorine, Post- 17 2
Ammonia 5 1
Sodium Hexametaphosphate 8 1
Fluosilic Acid 19 2
71
-------
deliver enough water to remote areas within the system, water is provided to
these areas by gravity from the elevated tanks.
Cost Analysis
Figure 3 illustrates the growth in consumer demand for water from 1964
through 1974, as discussed earlier. "Treated" water is the amount of water
that was pumped from the city's three water* treatment plants and treated
water purchased from the North Texas Municipal Water District and pumped
from the Casa View pump station. "Revenue-producing" water is the water
which was measured as metered consumption and paid for by wholesale and
retail customers.
Using the standardized cost categories defined earlier, data have been
collected and reported as shown in tables A-3 through A-5. As indicated by
the relative increases in the Support Services category, a major portion of
the operating budget has been expended for labor. Therefore, Table A-6
examines labor costs associated with operations and maintenance activities.
It shows the total payroll expended and the total number of man-hours on
the payroll.
As can be seen in Table A-5, the cost per man-hour increased by 231 per-
cent, while the total payroll hours required to produce a million gallons of
revenue-producing water decreased by 22 percent. This means that the opera-
ting cost for producing water did not increase as rapidly as labor cost per
man-hour. However, at some time in the future, it will no longer be poss-
ible to gain increasing efficiencies with respect to manpower, and the
operational cost will then start increasing at the same rate as the labor
cost.
Table A-7 summarizes the operating, depreciation, and interest expen-
ses for the 10-year period of analysis, and Table A-8 lists capital and
operating expenditure ratios. The purpose of Table A-7 is to provide a
comparison of the expenditures associated with operations and capital. The
operating expenses are those shown as the total of the values in Table A-5,
which are expenses incurred in normal day-to-day operations. The capital
expenses are the total expenses associated with periodic expenditures on
major equipment items and facilities, plus the interest that was charged on
the money that was borrowed for the purpose.
A comparison of the operating expenses and capital expenses as a per-
cent of the total cost shows that more expenses were associated with
operations than capital. Over the 10-year period, this trend continued
primarily because of a continual increase in the cost of items associated
with operations, such as salaries. Capital costs also increased slightly,
but not at the same rate as operating expenses.
Because the Dallas system is relatively old, the capital that is
being depreciated was expended when costs were significantly lower. On the
other hand, the operating expense is in current dollars. This ratio will
change whenever capital investments are made by the utility. For example,
major expenditures are planned for acquiring water by constructing new
72
-------
SUPPORT SERVICES
Administration
Accounting & Collection
Other
Total
ACQUISITION
Total
PUBIFI CATION
Supervision & Labor
Chemicals & Supplies
Other
Total
POWER & PUMPING
Supervision & Labor
Miscellaneous Services
Other
Total
TRANSMISSION & DISTRIBUTION
Supervision & Labor
Maintenance
Miscellaneous Services
Other
Total
TABLE A-3
WATER SUPPLY OPERATING COST FOR DALLAS WATER UTILITY
($)
1965
530,135
822,1*25
2,610
1,355,170
52!+, 1*1*0
556,380
693,1*19
127,316
1,377,115
l*5l+, 231*
U89,789
55,H*8
999,171
89!*, 528
261,572
188, 285
86,392
1,1*30,777
1966
5ta,798
907,782
2,329
1,1*50,909
537,779
577,366
706,ll*l*
165,173
1,1*1*8,683
l*5U,l8l
502,600
!*5,978
1,002,759
975,233
291,502
212,091*
93,1*99
1,572,328
1967
616,1*10
1,01*3,523
l*,05l*
1,663,987
597,257
573,028
729,556
11*5,665
1,1*1*8,21*9
515,622
530,983
1*7,600
1,09!*, 205
1,095,557
299,637
210,1*32
86,752
1,692,378
T968
707, 91*!
1,161,223
3,675
1,872,839
515,11*7
655,615
723,275
130, 781*
1,509,671*
562,015
528,055
52,817
1,11*2,887
l,2te,96o
281*, 162
2ll*,990
I0l*,63l+
1,81*6,71*6
1969
957,709
1,322,772
l*,8il
2,285,292
1*95,129
766,7l*5
838,152
I5l*,l99
1,759,096
636,310
655,995
1*3,31*9
1,335,651*
1,352,503
259,1*26
253,21*1
97,390
1,962,560
1970
1,189,7!*9
l,blk,W)
5,993
2,670,182
501,031
879,388
836,382
185,992
1,901,762
676,597
673,861*
53,81*2
l,l*ol*,303
1,1*66,236
316,959
266,819
128,756
2,178,770
1971
1,320,763
1,552,938
6l8,l*98
3,1*92,199
577,571
1,032,35!*
888,1*1*3
285,14-08
2,206,205
802,553
61*2,11*7
76,131*
1,520,831*
1,368,530
351,91*0
276,539
107,110
2,lolv,ll9
1972
537,166
1,716,325
1,510,872
3, 761*, 363
533,1*81
1,079,892
907,206
319,931
2,307,029
933,639
766,508
81,006
1,781,153
1,608,508
1*13,651*
325,031
125,893
2,1*73,086
1973
677,837
2,099,736
l,62l*,958
U,U02,53l
756,126
1,166,396
1,009,252
397,390
2,573,038
928,523
876,909
102,275
1,907,707
1,787,916
1*11,11*7
1*31,01+3
120,681*
2,750,790
• Tsft—
509,168
1,928,061
2,263,210
l*,700,l*39
688,105
1,21*0,568
1,151,276
396,605
2,788,UU9
81*9,759
892,073
61*, 1*21
1,806,253
1,952,521
1*06,501
5U,308
131,1*61*
2,5W+,79>*
TOTAL
5,686,673 6,012,1*58 6,1*96,076 6,887,293 7,837,731 8,656,01*8 9,900,928 10,859,112 12,390,192 12,528,oUo
-------
TABLE A-4
UNIT OPERATING COSTS .FOR DALLAS WAIEK UTILITY JN.DOLLARS PER MILLION GALLONS. OF JiEVENU£-^ROD_UCING_WAlEE
($/mil gal)
SUPPORT SERVICES
Administration
Accounting & Collection
Other
Total
ACQUISITION
Total
PURIFICATION
Supervision & Labor
Chemicals & Supplies
Other
Total
POWER & PUMPING
Supervision & Labor
Power & Miscellaneous Serv.
Other
Total
TRANSMISSION & DISTRIBUTION
Supervision & Labor
Maintenance
Miscellaneous Services
Other
Total
1965
13-50
20. 9!+
0.07
3^-51
1966
13-72
23 01+
0.06
36.82
1967
11+.29
21+.19
0.09
38.57
1968
15.60
25-59
0.08
1+1.27
1969
17-92
21+.75
0.09
1+2.76
1970
21.07
26.11
0.11
1+7-29
1971
23-35
27-1+6
10.91+
61.75
1972
8.85
28.28
21+.89
62.02
197T
12.11
37-50
29.02
78.63
1Q74
8.08
30.59
35-91
7^.57
13-35
11+.17
17-66
3-2!+
35.07
11-57
12.1+7
1.1+0
25-1+1+
13.65
11+.65
17-92
1+.19
36.76
11-53
12.76
1.17
25.1+6
13.85
13-28
16.91
3-38
33-57
11-95
12-31
1.10
25-36
11-35
H+.1+5
15.91+
2.88
33-27
12.39
11.61+
1.16
25-19
9.26
15.68
2.88
32.90
11.90
12.27
0.81
21+.98
8.87
15-57
H+.81
3-29
33-67
11.98
11-93
0-95
21+.86
10.21
18.25
15-71
5-05
39-01
11+.19
11-35
1-35
26.89
17-79
1^-95
5-27
38.01
15-38
12.63
1-33
29.31+
13-50
20.83
18.01
7.10
^5-95
16.58
15-66
1.83
3l+. 07
22.78
6.66
1+.79
2.20
36.1+3
21+.75
7.1+0
5-38
2.37
39-90
25-1+0
6-95
1+.88
2.01
39-21+
27-39
6.26
It. 71+
2.31
1+0.70
25.30
1+.85
1+.71+
1.82
36.71
25-96
5.61
1+.72
2.28
38.57
21+.20
6.22
1+.89
1.89
37-20
26.50
6.8l
5-35
2.07
1+0.73
31-93
7.31+
7-70
2.16
i+9.13
10.92
19.68
18.27
6.29
1+1+.21+
13-U8
11+.15
1.02
28.66
30.98
6.1+5
0.86
2.09
TOTAL
11+1+.80
152.59 150.29 151.78 11+6.61
153-26
175-06
178.89
221.28
198.76
-------
TABLE A-5
OPERATING COSTS FOR THE DALLAS WATER UTILITY AS A PERCENT OF TOTAL COST
SUPPORT SERVICES
Administration
Accounting & Collection
Other
Total
ACQUISITION
Total
PURIFICATION
Supervision & Labor
Chemicals & Supplies
Other
Total
POWER AND PUMPING
Supervision & Labor
Power & Misc. Services
Other
Total
TRANSMISSION & DISTRIBUTION
Supervision & Labor
Maintenance
Miscellaneous Services
Other
Total
1965
9-32
ik.ke
• 05
23.83
1966
8-99
15-10
.OU
2k. 13
1967
9.1+9
16.06
.06
25.61
1968
10.28
16.86
•05
27.19
1969
12.22
16.88
.06
29.16
1970
13-75
17. ok
.07
30.86
1971
13.31+
15.69
6.25
35-28
1972
1+-95
15.81
13.91
3l+. 67
1973
5-1+7
16.95
13-11
35-53
1974
1+.07
15-39
18.08
37.51+
9.22
8.95 9.20 7-1+8 6.32
5-79
5.83 1+-91 6.10 5-1+9
9.79
12.20
2.21+
21+.23
7-99
8.61
0.97
17.57
15.73
k.6o
3-31
1.52
25.16
9.60
11.71+
2.75
21+.09
7-56
8.36
•77
16.69
16.22
1+.85
3-53
1-55
26.15
8.82
11.23
2.2k
22.29
7 -9k
8.17
• 73
16. 8k
16.87
1+.61
3 -2k
1-33
26.05
9-52
10.50
1.90
21.92
8.16
7.67
•76
16.59
18.05
1+.12
3-12
1.52
26.81
9.78
10.70
1.96
22 .kk
8.12
8.37
.55
17. ok
17.26
3.31
3-23
1. 2k
25. ok
10.16
9-66
2.15
21-97
7.82
7-78
.62
16.22
16. 9k
3.66
3-08
1.U9
25.17
10.U2
8.97
2.88
22.27
8.11
6.1+8
• 77
15.36
13.82
3-55
2.79
1.08
21.21+
9.9*+
8.36
2.91+
21.21+
8.60
7.06
0.71+
16.1+0
U+.81
3-8l
2.99
1.16
22.77
9.Ul
8.1U
3-21
20.76
7-1+9
7.08
0.83
15.1+0
11+ A3
3-32
3-1+8
0.97
22.20
9-90
9-19
3-16
22.25
6.78
7.12
0.51
ll+.l+l
15-59
3-25
0.1+3
1.05
20.32
-------
TABLE A-6
LABOR COST ANALYSIS FOR DALLAS WATER UTILITY
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974
Total Payroll ($)* 2,039,838 2,187,81*1* 3,126,9^0 3,1*68,600 3,936,236 1*,398,157 5,lW,8l7 5,688,610 6,102,292 6,296,936
Total Hours on Payroll ** 1,753,^0 1,759,680 1,72^,320 1,768,000 1,73^,720 1,828,320 2,028,000 2,186,080 2,302,560 2,20^,800
Billed Consumption (mil gal) 39,27>* 39,>*0l* 1*3,135 **5,372 53,^51 56,1*72 56,555 60,698 55,991* 63,030
Total Payroll /mil gal of
Metered Consumption 51-91* 71-51 72.1*9 76.1*5 73-61* 77.88 91.01* 93-39 108.98 99-90
Total Hours /mil gal (hrs/mil gal)
Metered Consumption (bil gal) 1*1*.65 1*1*.66 39-97 38-97 32.1*5 32.38 35-86 38.02 1*1.12 3!*.98
Average Cost/man hour** 1.16 1.2l* 1.8l 1.96 2.2? 2.1*1 2.5!* 2.60 2.65 2.86
* Includes Operations and Maintenance payroll only.
** Includes all water utility man hours.
-------
TABLE A-7
DALLAS WATER UTILITY CAPITAL AND OPERATING COSTS
($)
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974
Operating Expense 5,686,67!+ 6,012,1+57 6,1*96,075 6,887,291 7,837,731 8,656,01+8 9,900,927 10,859,112 12,390,193 12,528,01+0
Depreciation 2,978,901 3,175,888 3,339,206 3,^,015 3,687,875 3,8H+,911 3,985,751 l+,Uo6,95!+ 1+,751,860 5,135,253
Interest 1,917,672 1,951,21+3 2,088,277 2,21+5,807 2,196,370 2,8ol+,l85 2,192,802 2,508,61+7 3,l+2l+,568 3,637,576
Total 10,583,253 11,139,588 11,923,558 12,627,113 13,721,976 H+,555,11*1* 16,079,1+80 17,77l+,713 20,566,621 21,300,869
Total Unit Cost/ 269.U6 282.70 276.1+2 278.30 256.72 257-7>+ 281+.31 292.83 367-29 337-91*
mil gal of
Revenue Producing
Water
-------
TABLE A-8
CAPITAL AND OPERATING EXPENDITURE RATIOS FOR DALLAS WATER UTILITY
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974
Operating Cost ($) 5,686,67!* 6,012,1*57 6,1*96,075 6,887,291 7,837,731 8,656,01*8 9,900,927 10,859,112 12,390,193 12,528,01*0
capital cost ($) 1*,396,573 5,127,131 5,1*27,1*83 5,739,822 5,884,21*5 5,899,096 6,178,553 6,915,601 8,176,1*28 8,772,829
Total ($) 10,583,253 11,139,568 11,923,558 12,627,113 13,721,976 ll*,555,lW* l6,079,>*80 17,77l*,713 20,566,621 21,300,869
Operating Cost
(% of Total)
Capital Cost
(% of Total)
Capital Labor
Cost Ratios
53-73
1*6.27
2.16
53-97
1*6.03
2.3!*
5U.M
1*5-52
1.7k
5>* .51*
1*6.1*6
1.65
57.11
1*2.89
1.1*9
59-1*7
1*0.53
1.3U
61.57
38.1*3
1.20
61.09
38.91
1.22
60. 2l*
39-76
1.31*
58.81
1*1.19
1-39
-------
reservoirs and pipe lines. When this occurs, the ratio of capital expenses
versus operating expenses will change significantly.
Examination of the costs on a functional basis is only part of the total
cost picture. Since the purpose of a water supply utility is to deliver
water to a consumer, it is important to be able to present costs in such a
way that they relate to the water delivered to a demand point within the
utility's distribution system. Therefore, the functional categories, both
operating and capital, should be reaggregated and assigned to physical com-
ponents in the water delivery system.
System Costs
In Figure A-4, the arrows depict the general direction of the water flow
in the retail service area. Rectangles indicate treatment plants and circles
are the pump stations. Although seldom used, Elm Fork and Bachman treatment
plants also contain high pressure pumps for moving the water to the Lake
June pump station, where all the water treated at East Side is pumped into
the distribution system. The elevation of each facility is shown in
Table A-9.
To analyze the impact of the cost of water as it moves through acquis-
ition to treatment to the consumer, it is necessary to identify the capital
and operating cost of each component of the system. Figure A-5 is a
schematic diagram of Figure A-4 and shows the operating and capital cost for
each of the system's major facilities. A linearity assumption is made
which allows costs per million gallons to be added as water moves from one
component of the system to another. For example, the acquisition cost of
water going to the East Side treatment plant (shown as ES in Figure A-4) is
$54.62/mil gal, the cost of treatment is $78.08/mil gal, and the cost of
pumping to Zone A is $20.34/mil gal. Adding these three costs together
yields a cost of $153.04/mil gal for water delivered to Zone A. As water
passes through this zone, a transmission cost of $41.01/mil gal is added.
The schematic diagram which shows the major pathways for water are
designated by 1, 2, or 3. The various cost zones are shown in column 1 of
Table A-10. Therefore, according to this designation, for Zone 3-A the
incremental cost is $153.04/mil gal. These incremental costs are shown in
column 2 of Table A-10. Added to the incremental costs are the distribution
costs, the interest cost, and the support services costs.
Distribution cost is calculated based on the assumption that these are
constant throughout the system. Therefore, the total capital and operating
cost for distribution was divided by the number of gallons of revenue-produc-
ing water in 1973, yielding the figure $67.33/mil gal. The same approach
was taken to calculate interest and support service costs. When these costs
are added together, a total cost per mil gal for water in a given zone
results. For example, the total cost of water delivered in Zone 3 is
$361.55/mil gal. Columns 7 and 8 of Table A-10 contain the metered consum-
tion in mil gal for each zone and its estimated revenue. Total revenue can
be compared with the total cost for 1973-74 as shown in Table A-8. Figure
A-6 is a graph of typical charges ($/mil gal) over a pathway (pathway 1).
79
-------
FIG. A-4 TREATMENT PLANTS AND PUMP STATIONS
IN DALLAS UTILITY SERVICE AREA
80
-------
OO
1
ACQUISITION $13.75
EF
TREATMENT $44.07
PUMPING $21.28
TRANSMISSION $45
.80
2 3
$13.75 $48.08
B ES
$52.47 $64.89
$21.28
$43
.80 $43.80
I
ZONE
PUMPING
TRANSMISSION $43.80
PUMPING
PURCHASED
WATER
$108.68
B
FIG. A-5 ALLOCATION OF CAPITAL AND OPERATING EXPENSES TO
WATER SYSTEM COMPONENTS FOR DALLAS WATER UTILITY
(ALL COST IN DOLLARS PER MILLION GALLONS BILLED CONSUMPTION)
-------
TABLE A-9
FACILITIES IN DALLAS UTILITY RETAIL SERVICE AREA*
Treatment Plants
EF Elm Fork
B Bachman
ES East Side
Elevation Pump Stations
(ft)
458 B
456 CW
480 CC
G
JM
LJ
SC
S
we
CV
WH
Beltwood
Camp Wisdom
Cosa Crest
Greenville
Jim Miller
Lake June
Southcliff
Sunset
Walcrest
Casa View
Walnut Hill
Elevation
(ft)
622
693
620
609
521
504
586
607
627
562
* Above mean sea level.
82
-------
00
U)
TABLE A-10
COST ELEMENTS FOR SERVICE ZONES
Cost
Zone
1 A
B
C
2 A
B
3 A
B
C
3 D
Incremental
Cost
($/mil gal)
70.90
132.25
193.60
104.66
166.01
153.04
214.39
275.74
129.96
Distribution
Cost
($/mil gal)
67.33
67.33
67.33
67.33
67.33
67.33
67.33
67.33
67.33
Interest
Cost
($/mil gal)
57.72
57.72
57.72
57.72
57.72
57.72
57.72
57.72
57.72
Overhead
Cost
($/mil gal)
83.46
83.46
83.46
83.46
83.46
83.46
83.46
83.46
83.46
Total
Cost
($/mil gal)
279.41
340.76
402.11
313.17
374.52
361.55
422.90
484.25
333.88
337.96
Metered
Consumption
(mil gal)
16,766
16,323
223
872
854
4,212
5,936
87
557
63,030
Revenue
($)
4,684,588.06
5,562,225.48
89,670.53
2,465,274.24
2,566,960.08
1,522,848.60
2,933,234.40
623,299.75
853,731.16
21,301,762.30
-------
CD
-P-
300.00
200.00
D)
E
100.00
EAST FORK
WALCREST
COSA CREST
FIG. A-6 COST OF SERVICE OVER PATHWAY 1
-------
Once these calculations have been made, and various cost zones have been
established, costs for a given set of consumers versus charges can be exam-
ined. Table A-ll summarizes the cost per million gallons for typical monthly
water consumption rates, by meter size, as charged by the City of Dallas.
Table A-12 contains water costs for the 10 largest customers served by
the Dallas Utility. The table shows high and low month of water use, the
number of units (hundred cubic feet) used during that time, and the amount
billed for the service. If a customer also utilized sewage services, the
utility bill includes sewage service charges, and it was therefore necessary
to calculate the portion of the bill that was allocated directly to water,
which is contained in the column, "Allocated to Water."
By converting the units used to mil gal, and dividing that into the money
charged for the water, it is possible to examine the amount that the customers
were actually paying per mil gal to the utility for their water, as shown in
the last column.
Comparing each user's location with the cost allocation table makes it
possible to identify the actual allocated cost associated with delivering
water to a specific consumer. Figure A-7, which is a map of the cost and the
major users, shows that the majority of users are located among the central
low area of the distribution system and, therefore, are served directly from
the treatment facilities. Some users, such as two of the Texas Instrument
plants (1 & 3), are located a considerable distance from the treatment plants
and require significant transportation of the water. Table A-13 contains a
match-up of cost zones and customers. Table A-14 contains the costs which
are associated with water delivery by cost zone and the amount of money paid
by the customer.
85
-------
FIG. A-7 MAP OF COST ZONES AND MAJOR USERS
FOR DALLAS SERVICE AREA.
86
-------
TABLE A-ll
CHARGE ANALYSIS FOR TYPICAL MONTHLY WATER CONSUMPTION
Gallons
Class Meter Size Consumed Billed $/mil gal
Residential 5/8" 10,000 6.12 $612.00
Commercial 4" 1,000,000 509.54 509.54
Industrial - 25,000,000 5,316.00 212.64
(Outside city limits rates multiplied by 1.5)
87
-------
TABLE A-12
COST FOR MAJOR CONSUMERS IN DALLAS SERVICE AREA
oo
00
Major Users
Texas Instruments
Procter & Gamble
Standard Brands
Texas Instruments
Texas Instruments
Clevepak Corp.
Stokely Van Camp
Morton Foods
Diamond Shamrock
Dr. Pepper Co.
(high and
high
low
high
low
high
low
high
low
high
low
high
low
high
low
high
low
high
low
high
low
Month
low use)
9
1
9
10
8
4
8
2
11
1
9
11
8
11
9
1
7
10
9
3
Units Used
(cubic feet)
138,402
104,364
36,770
25,342
27,350
19,120
28,530
12,490
16,511
9,990
39,910
15,124
18,444
13,358
9,966
4,748
6,906
3,948
10,890
7,297
Total Cost
($)
$45,028.25
33,999.94
7,717.08
5,385.77
9,047.40
9,164.16
6,036.12
2,763.96
5,535.56
3,422.76
5,068
6,161.86
4,513.99
3,414.98
1,724.35
1,624.82
1,021.39
3,714.36
3,631.00
Allocated
to Water
($)
18,487.62
13,932.94
7,717.08
5,385.77
3,627.54
3,675.77
6,036.12
2,763.96
2,177.15
1,304.57
1,984.13
2,435.82
1,755.25
3,150.98
603.12
1,624.82
1,021.39
1,425.00
1,390.57
$/mil gi
178.56
178.44
280.54
284.09
177.30
257.05
282.80
295.80
291.45
43.69
143.77
243.82
175.70
422.38
169.89
314.52
373.88
174.91
254.68
-------
TABLE A-13
LIST OF MAJOR USERS IN COST ZONES FOR DALLAS SERVICE AREA
Identification
Number
1
2
3
4
5
6
7
8
9
10
Major Users*
Texas Instruments
Procter & Gamble
Standard Brands
Texas Instruments
Texas Instruments
Clevepak Corp.
Stokely Van Camp
Morton Foods
Diamond Shamrock
Dr. Pepper Co.
Supply
Area
IB
3A
2A
2A
IB
3A
2B
2A
3A
2B
* See Figure A-6
89
-------
TABLE A-14
MAJOR USERS AND COSTS ASSOCIATED WITH DELIVERY AND PURCHASE OF WATER
Major Users
Texas Instruments
Procter & Gamble
Standard Brands
Texas Instruments
Texas Instruments
Clevepak Corp.
Stokely Van Camp
Morton Foods
Diamond Shamrock
Dr. Pepper Co.
Cost of Water
for High and Low
Use Month (for 1973)
($/mil gal)
178.56
178.44
280.54
284.09
177.30
257.05
282.80
295.80
291.45
43.69
143.77
243.82
175.70
422.38
169.89
314.52
373.88
174.91
254.68
Estimated
Delivery Cost
($/mil gal)
340.76
361.55
313.17
313.17
340.76
361.55
374.52
313.17
361.55
374.52
90
-------
APPENDIX B
SAN DIEGO WATER UTILITY
The City of San Diego is located in San Diego County, which comprises
the San Diego SMSA. The retail service area for the water utility is made
up of the City of San Diego except for the South Bay area and for a small
number of retail customers within San Diego County. Raw water is purchased
from the Metropolitan Water District of Southern California by the San Diego
County Water Authority. Its price covers operating costs of the County
Water Authority and the Metropolitan Water District. The Water Utility makes
in-lieu-of tax payments to the Metropolitan Water District and the San Diego
County Authority to cover the capital cost of the aqueducts.
Organization
In San Diego the water utility is organized as follows (Figure B-l):
Systems; Water Quality; and Services divisions. Included in the Service
Division's functions are design engineering, customer service, and adminis-
trative support. The Systems Division is responsible for installation and
maintenance of hydrants, manholes, valves, and mains, and is also responsi-
ble for hydraulic control, emergency services, systems engineering, utility
plant checking, maps and records, meters, services and laterals, sewer main
cleaning, and hydrology. The Water Quality Division is responsible for
water supply, water treatment, wastewater collection and treatment, and the
operation of the laboratory.
The water and wastewater functions of the San Diego Water Utility are
combined organizationally at the division level, although separate accounts
are maintained for water and sewer revenues and expenses. All bonds are
clearly defined as to whether or not they are water or sewer bonds.
Service Area
The San Diego Water Utility Department provides water service on a
retail basis to all classes of customers within the San Diego city limits.
It also supplies treated water to the California-American Water Company,
the City of Del Mar, California, and to miscellaneous users outside the city.
The California-American Water Company in turn supplies retail customers
within the city's South Bay area.
In 1974, the city sold 3,025.6 mil gal to the California-American Water
91
-------
ADMINISTRATION
UTILITIES SERVICES
DIVISION
DESIGN ENGINEERING
CUSTOMER SERVICE
CHOLLAS ADMINISTRATION
UTILITIES SYSTEMS
DIVISION
HYDRANT, MANHOLE,
VALVE MAIN
HYDRAULIC CONTROL
AND EMERGENCY
SERVICES
SYSTEMS ENGINEERING
UTILITIES PLANT
CHECKING
MAPS AND RECORDS
METERS
SERVICES AND LATERALS
SEWER MAIN CLEANING
HYDROLOGY
WATER QUALITY
DIVISION
LABORATORY
WATER SUPPLY
WATER TREATMENT
WASTE WATER
FIG. B-1 SAN DIEGO WATER UTILITY
-------
Company, 306.8 mil gal to Del Mar, and 64.2 mil gal to miscellaneous users
outside the city. That same year, the San Diego Water Utility delivered
49,039.8 mil gal to the City of San Diego, making the total water consumption,
including the South Bay area, 50,073.9 mil gal during fiscal year 1974.
Figure B-2 shows the water utility service area.
Acquisition
There are no permanent streams or natural lakes anywhere in the San
Diego area, nor are there any extensive ground water sources. For this
reason, San Diego has developed a system of impounding reservoirs (Figure B-2)
divided into three geographical districts. Each series of water sheds or
drainage basins extends from the summit of the mountains to the lowest dam.
Parallel to the Mexican border is the Cottonwood-Otay District which includes
Morena and Barrett reservoirs on the Cottonwood River, and the Dulgura Conduit
and Upper and Lower Otay reservoirs on the Otay River.
To the north of the Cottonwood-Otay District lies the San Diego River
which is the largest river system in the County in terms of runoff. This
watershed contains Cuyomaca Reservoir, owned by the Helix Irrigation Dis-
trict, and El Capital and San Vicente reservoirs, owned by the City of San
Diego. The San Dieguito River District is north of the Helix Irrigation
District, which includes Sutherland and Hodges reservoirs.
These reservoirs provide storage for local run-off and for imported
water which flows down from the north through the two San Diego aqueducts.
In 1974, 89.4 percent of the water used by the San Diego Water Utility was
imported from the Colorado River. This percentage will drop as water is
imported from the Feather River project (Northern California).
Treatment
Raw water treatment is accomplished by three treatment plants: the
Alvarado plant, located at the Murray Reservoir; the Miramar plant, located
at Miramar Reservoir; and the Otay plant located at the Otay Reservoir. The
plants have a combined capacity of 66, 40, and 15 mil gal per day,
respectively.
The Alvardo treatment plant filters water which originates in the San
Diego River system, including water originating from the El Capital, San
Vicente, and Murray reservoirs, and Colorado River water stored in the
San Vicente and El Capitan reservoirs. Water from the second San Diego
aqueduct can also be processed at this plant.
The Miramar plant serves the northern section of the city and filters
water that has been transported from the Colorado River through the facil-
ities of the Metropolitan Water District of Southern California and the
San Diego County Water Authority. Miramar Reservoir serves as a supple-
mental source of supply, or in the event of an aqueduct failure.
The Otay plant serves the South Bay area of the city and treats water
from the Cottonwood-Otay system and from the second San Diego aqueduct.
93
-------
AQUEDUCT
QUEDUCT
-------
Water from Morena and Barrett reservoirs is transferred to Otay when avail-
able, and treated after being pumped from Otay Reservoir.
The Alvarado, Miramar, and Otay treatment plants have capacities of
66, 40, and 15 mgd, respectively, and are similar in design with separate
mixing and settling basins with rapid sand filters. The Otay treatment
plant combines the steps of mixing, coagulation, and sedimentation all in one
single basin and has pressure filters.
Transmission and Distribution
The Utility's three treatment plants are located between 521 and 715
feet above sea level; however, most of the Utility's customers are located
below these elevations, and are therefore supplied by gravity from the treat-
ment plants. Pressure reducing valves are required on trunk mains.
Tne highest point in the distribution area ia 1,020 feet above sea
level. Since these higher elevations are scattered throughout the distribu-
tion area, they are supplied through small pumping plants. Most of these
areas are also equipped with elevated storage tanks or standpipes for the
purpose of leveling out demand. There are currently 145 pressure reducing
stations, 33 pumping stations, and 23 elevated storage tanks, and 74 pressure
zones in the San Diego system.
The distribution storage reservoirs are built at strategic locations
in the system, allowing the filtration plants to be operated at a fairly
constant rate. During periods of peak demand, the water flows back out of
the reservoirs and augments the filtration plants. The system now has 20
covered storage reservoirs, with a total capacity of 159.37 mil gal.
The standpipes and elevated storage tanks within the San Diego system
serve a dual purpose: they level out the demand on the pumping plants, and
they maintain adequate delivery pressures within the higher elevations of
the distribution area. At present, there are 10 standpipes, with a total
storage capacity of 13.28 mil gal and 11 tanks with a total capacity of
3.05 mil gal within the San Diego system. Table B-l is a summary sheet for
the facilities which make up the storage system.
Production of Water
Figure 12 illustrates the steady growth in the production of water
which has taken place from 1963 through 1973. "Treated" water is the amount
of water treated in the city's three plants. "Billed" water is the revenue-
producing water which was measured as metered consumption. As discussed
earlier, the cost analysis for each utility has been based on revenue-produc-
ing water. Unit costs have been calculated by dividing cost for a given
functional area by the amount of revenue-producing water which has been sup-
plied. It can be seen from Figure 12 that slightly over 30,000 mil gal of
revenue-producing water (billed consumption) were supplied in 1964 and over
47,000 mil gal were produced in 1974.
95
-------
TABLE B-l
SUMMARY STATISTICS FOR SAN DIEGO WATER UTILITY DISTRIBUTION
AND STORAGE SYSTEM
Reservoirs (covered)
Alvarado
Bayview
Brown Field
Del Cerro
Earl Thomas
La Jolla CC Hts
La Jolla Exchange
La Jolla View
Mirairiar Reg
Pacific Beach
Point Loma
Pomerado Park
Penasquitos
Rancho Bernardo
San Carlos
San Ysidro
Soledad
South San Diego
Torry Pines
University Hts.
Capacity
mil gal
20.2
10.0
1.0
1.5
35.0
0.5
.99
.72
20.0
2.4
10.06
5.2
5.0
10.1
5.0
1.2
1.5
15.0
2.8
11.2
Standpipes
Camp Callan
Catalina
Chesterton
College Ranch
Emerald Hills
Encanto
Kearney Mesa
Lomita Village
Paradise Hills
Redwood Village
Tanks
Alvarado Wash
Brown Field
Climax
College Hts.
College Ranch
La Jolla CC
Miramar Wash
Paradise Hills #2
Point Loma Sewage
San Carlos
University Hts.
Capacity
mil gal
2.0
1.5
0.99
1.5
1.5
0.75
1.52
0.77
0.75
2.0
0.792
0.002
0.50
0.003
0.50
.003
.050
.002
1.200
96
-------
Cost Analysis
Tables B-2 through B-4 contain the costs for treatment, acquisition,
transmission and distribution, power and pumpting, and support services.
The "other" category in support services includes: expenses of other city
departments applicable to the water utility, contributions to the retirement
fund, compensation insurance, other insurance and damage claims, uncollect-
able accounts, engineering, taxes, and general expenses.
Table B-5 contains an analysis of labor costs for San Diego and shows
that although the unit cost of water based on labor input is rising, the
productivity in terms of manhours per mil gal of water consumed is decreas-
ing. Table B-6 shows total operating and capital cost expenditures and
Table B-7 contains the percent of operating and capital cost based as a
function of total cost.
System Costs
As with Dallas, the cost of each functional component of San Diego's
water utility can be reaggregated, and allocated against the physical
components of the water delivery system. The arrows in Figure B-3 show the
water from the treatment plants through booster pumping stations, through
pressure regulators to the 74 service areas across the city.
Operation and depreciation costs for each system component are shown
in Figure B-4. The total delivery costs of water to a specific point within
the distribution area are given in Table B-8.
Table B-9 establishes the cost per mil gal based on meter size and
typical consumption rates on a monthly basis. Most domestic, commercial,
and industrial customers are billed bi-monthly, although 5,000 customers
are billed monthly. The charge analysis in Table B-9 illustrates the price
that typical residential, commercial, and industrial customers pay for water
on a dollars per mil gal basis.
Table B-10 shows the six major customers of the San Diego Water Utility,
together with their high and low water use, the number of units (hundreds
of cubic feet) used during that time, and the amount of money they are billed
for the service. These same users shown on Figure B-5 (map of San Diego
service area) are all located on the shores of San Diego Bay, with the
exception of the Torry Pines Golf Course. The cost zones established for the
San Diego utility are also shown in Figure B-5. Table B-ll compares the costs
associated with delivery of water to the consumer versus the costs actually
paid.
97
-------
TABLE B-2
WATER SUPPLY OPERATING COST FOR SAN DIEGO WATER UTILITY
C§)
00
SUPPORT SERVICES
Administration
Accounting & Collection
Other
Total
ACQUISITION
In Lieu of Taxes &
Payments
Purchase of Water
Impounding & Transmission
Other
Total
PURIFICATION
Total Purification
DISTRIBUTION
Mains
Services
Meters
Pumping
Reservoirs & Tanks
Other
Total
TOTAL
1965
367,863
370,697
918,376
1,697,296
1,728,586
2,883,918
491,060
138,905
5,242,469
533,115
735,688
263,070
530, 141
137,201
58,052
300,484
2,024,161
1966
325,079
426,691
959,086
1,710,856
1,876,458
2,609,532
481,999
172,797
5,140,786
519,532
722,331
296,901
451,292
150,444
91,288
270,109
1,982,365
1967
384,750
511,013
1,077,771
1,973,534
1,810,262
2,940,944
387,537
234,227
5,372,970
492,548
780,076
254,223
403,633
161,308
93,937
311,037
2,004,214
1968
418,357
515,851
1,277,882
2,212,090
1,860,094
3,578,306
416,087
130,223
5,984,710
539,065
823,365
S42,644
535,480
154,143
95,440
321,369
2,172,441
1969
463,869
700,219
1,510,889
2,674,977
3,248,161
4,468,675
496,109
8,212,945
641,455
839,388
303,581
496,301
156,045
87,062
347,408
2,229,985
1970
207,538
729,688
2,150,856
2,766,983
3,723,339
4,361,873
556,099
8,641,311
725,262
831,956
246,315
410, 4oo
176,233
85,205
445,171
2,195,280
1971
224,967
710,393
2,321,519
3,086,216
4,119,568
4,996,429
535,124
9,651,121
747,559
750,927
284,585
486,078
182,055
81,787
667,106
2,452,538
1972
229,958
736,689
2,730,463
3,288,166
4,851,837
7,164,875
595,165
12,611,877
806,348
845,835
307,020
582,627
230,279
96,143
585,974
2,647,878
1973
238,638
891,761
2,730,463
3,860,862
5,063,372
8,793,815
566,243
14,423,428
913,471
872,818
341,075
608,068
247,521
104,865
582,682
2,757,029
1974
251,425
1,016,043
3,151,995
4,419,463
5,335,690
7,026,638
567,396
12,929,724
1,055,868
829,755
347,245
671,878
286,130
100,143
588,645
2,823,796
9,457,496 9,353,539 9,843,266 10,908,306 13,759,362 14,328,836 15,937,434 19,354,269 21,954,790 21,228,851
-------
TABLE B-3
UNIT OPERATING COSTS FOR SAN DIEGO WATER UTILITY IN DOLLARS PER MILLIONS GALLONS OF REVENUE-PRODUCING WATER
($/mil gal)
SUPPORT SERVICES
Administration
Accounting & Collection
Other
Total
ACQUISITION
In Lieu of Taxes & Payments
Purchase of Water
Impounding & Transmission
Other
Total
PURIFICATION
Total
DISTRIBUTION
Mains
Services
Meters
Punping
Reservoirs & Tanks
Other
Total
1965
12.11
12.20
30.25
55.56
56.91
9^-95
16.17
l*-57
172.60
1966
10.01
13 -I1*
29- 51*
52.69
57-79
80.37
1U.85
5-32
158-33
1967
11.72
15-56
32.82
60.10
55.12
89-55
11.80
7.13
163.60
1968
11.92
1M-.70
36.1*2
63. ok
53-02
101.99
11.86
3-71
170.59
1969
12. U3
18.76
1*0.1*7
71-66
87.01
119-71
13-29
220.01
1970
5.20
18.30
1*5.89
69-39
93-36
109.39
13-95
216-70
1971
5-37
16.96
51.31*
73-67
98.33
119.26
12.77
230.36
1972
5.06
16.20
50. ok
71.30
106.67
157-53
13-09
277.29
1973
5A5
20.38
62.39
88.22
115.70
200. 9^
12.91*
329.58
1974
5-33
21.52
66.77
93.62
113.03
11*8.85
12.02
273-90
17-55
16.00
15.00
15-36
17.18
18.19
17.8!+
17-73
20.87
2l*.22
8.66
17-1*5
1*.52
1-91
9.89
66.65
22.25
9.ll*
13.90
1*.63
2.81
8.32
61.05
23-75
7.7k
12.29
l*.91
2.86
9-1*7
61.02
23-!*7
6.92
15.26
1*.39
2.72
9-16
61-92
22.1*9
8.13
13-30
»*. 18
2.33
9-31
59-71*
20.86
6.18
10.29
l*.l*2
2.11*
11.16
55-05
17.92
6.79
11.60
l*-35
1-95
15-92
58-53
18.60
6.75
12.81
5.06
2.11
12.88
58.21
19- 91*
7-79
13-89
5.66
2.1*0
13.31
62.99
22.37
17.58
7.36
ll*.23
6.06
2.12
12A7
59-82
TOTAL
311-36
188.07
299-72
310-91
368.59
359-33
380.1*0
!*25-53
501.66
1*1*9.71
-------
TABLE B-4
OPERATING COSTS FOR THE SAN DIEGO WATER UTILITY AS A PERCENT OF TOTAL COST
o
o
SUPPORT SERVICES
Administration
Accounting & Collection
Other
Total
ACQUISITION
In Lieu of Tax Pints.
Purchase of Water
Impounding & Transmission
Other
Total
PURIFICATION
Total
DISTRIBUTION
Mains
Services
Meters
Pump ing
Reservoirs & Tanks
Other
Total
1965
3.89
3.92
9.72
17.84
18.28
30.50
5.19
1.47
55.43
1966
3.47
4.56
10.25
18.29
20.06
27.90
5.15
1.85
54.96
1967
3.91
5.19
10.95
20.05
18.39
29.88
3.94
2.38
54.58
1968
3.83
4.73
11.71
20.28
17.05
32.80
3.81
1.19
54.36
1969
3.37
5.09
10.98
19.44
23.61
32.48
3.61
-
59.61
1970
1
5
12
19
25
30
3
60
.45
.09
.77
.31
.98
.44
.88
-
.31
.1.971
1.41
4.46
13.50
19.37
25.85
31.34
3.36
-
60.56
1972
1.19
3.81
11.76
16.76
25.07
37.02
3.08
-
65.16
1973
1.
4.
12.
17.
23.
40.
2.
-
65.
09
06
44
59
06
06
58
70
1974
1.19
4.79
14.85
20.82
25.13
33.10
2.67
-
60.91
5.64 5.55 5.00 4.94 4.66 5.06 4.69 4.17 4.16 4.97
7.78 7.72 7.92 7.55 6.10 5.81 4.71 4.37 3.97
3.91
2.78
5.60
1.45
0.61
3.18
6.64
4.83
1.61
0.98
2.89
2.58
4.10
1.64
0.95
3.16
2.23
4.91
1.41
0.87
2.95
2.21
3.61
1.13
0.63
5.53
1.72
2.86
1.23
0.60
3.11
1.78
3.05
1.14
0.51
4.19
1.59
3.01
1.19
0.50
3.03
1.55
2.77
1.13
0.48
2.65
1.64
3.16
1.35
0.48
2.77
21.41 21.19 20.36 19.92 16.21 15.32 15.39 13.68 12.56 13.30
-------
TABLE B-5
LABOR COST ANALYSIS FOR SAN DIEGO WATER UTILITY
1965 1966 _^J96L 1968__ 1969 1970 1971 1972 1£73 197A
Total Payroll ($)* 2,553,52U 2,525,1*56 2,657,682 2,9^5,2^3 3,715,028 3,868,786 U,303,107 5,225,653 6,010,371 6,323,38U
Total Hours on Payroll ** 8ln,?8l.3 867,973-0* 8^,95^-9* 821,936.7 1,050,737-8 l,cA5,Ul6.0 1,01*6,527 .U 1,057,132-7 1,051,336-9 1,0^5,5^1.0
Billed consumption (mil gal) 30,373 32,U68 32,8U2 35,086 37,330 39,87"* Ul,89U 1+5,U&U ^3,76^ U?,205
Total Payroll/ mil gal of
Metered Consunption ($/mil gal) 87.07 77.78 80-92 83-9U 99-52 97-03 102.71 11U.89 137-3^ 133-96
Total Hours/ mil gal of
Metered Consumption (hr/mil gal)27.71 26.73 19-95 23A3 28.15 26.22 2U.98 23-2U 2^.02 22.15
Average Cost/man hour 3.03 2.91 3-15 3-58 3-5U 3-70 U.ll U-9U 5-72 6.05
($/man hour)
* Includes Operation and Maintenance payroll only.
** Includes all water utility man hours.
-------
TABLE B-6
SAN DIEGO WATER UTILITY CAPITAL AND OPERATING COSTS
($)
1965 1966 1967 1* 2,526,851 2,676,098 2,627,H*5 2,811,573 2,532,092 2,768,889 2,578,850 2,778,632
Interest 66k,68k 621,896 580,202 539,381 1*96,7^7 ^59,19^ ^21,966 385,2(A 350,6Jt5 317,516
Total 12,69^,8U9 12,1*71,789 12,950,319 1^,123,785 16,885,251* 17,599,603 I8,891,»f92 22,508,362 2l*,88fc,285 2U,32U,999
Total Unit Cost/
Mil Gal of 1*17.96 381*.13 39U.32 1*02.55 1*52-32 1*1*1.38 1*50.91* 1*9U.86 568.60 515-31
Revenue Producing
Water
-------
TABLE B-7
CAPITAL AND OPERATING EXPENDITURE RATIOS FOR SAN DIEGO WATER UTILITY
1965 1966 1967 1968 1969 1970 1971 1972 1973 1974
Operating Cost ($) 9,^57,^96 9,353,539 9,81*3,266 10,908,306 13,759,362 ll*,328,836 15,937,^ 19,35^,269 21,95^,790 21,228,851
Capital cost ($) 3,237,353 3,118,250 3,107,053 3,215,1*79 3,^25,892 3,270,767 2,95M58 3,15^,093 2,929,1*95 3,096,11*8
Total ($) 12,69l*,8l*9 12,1*71,789 12,950,319 lU,123,785 16,885,25!* 17,599,603 18,891,1*92 22,508,362 2l*,83l*,285 2l*,32l*,999
Operating Cost
d of Total) 7!*.50 75-00 76.01 77-23 8l.l*9 8l.l*2 81*.36 85.99 88.23 87.27
Capital Cost
(% of Total) 25-50 25-00 23.99 22.77 18.51 18.58 15.61* ll*.01 11.77 12.73
Capital-Labor 1,27 1.23 1,17 1,09 0.84 0.85 0.69 0.60 0.49 0.49
Cost Ratio
-------
FIG. B-3 SAN DIEGO WATER UTILITY FACILITIES
104
-------
TABLE B-8
COST ELEMENTS FOR SERVICE ZONES
Pathway
No.
1
2
3
Incremental
Cost
($/mil gal)
322.68
292.56
300.64
Distribution Interest Overhead Total Metered Revenue
Cost Cost Cost Cost Consumption
($/mil gal) ($/mil gal) ($/mil gal) ($ /mil gal) (mil gal) ($)
105.91 6.73 95.67 530.99 17,013 9,033,732.87
105.91 6.73 95.67 500.87 24,802 12,422,577.74
105.91 6.73 95.67 508.95 5,377 2,736,624.15
TOTAL
47,192
24,192,934.76
-------
TABLE B-9
CHARGE ANALYSIS FOR TYPICAL MONTHLY WATER CONSUMPTION
Class
Residential
Commercial
Industrial
Meter Size
5/8"
4"
10"
Gallons
Consumed
10,000
1,000,000
25,000,000
Billed
$ 3.91
490.32
10,158.05
$/mil gal
$391.00
490.32
406.32
106
-------
TABLE B-10
COST FOR MAJOR CONSUMERS IN SAN DIEGO UTILITY SERVICE AREA
Major Users
Kelco Co.
Navy Training
USMC
Convair
Solar Aircraft
Torrey Pines
High
Low
High
Low
High
Low
High
Low
High
Low
High
Low
Month
Aug.
Dec.
Dec.
Jan.
Sept.
Aug.
June
Dec.
June
July
July
Jan.
Units Used
(cu ft)
21,774
9,961
33,478
6,650
62,134
24,538
9,485
4,447
20,350
9,128
15,441
1,621
Total Cost
($)
6,583
3,134
10,376
2,542
18,743
7,765
2,995
1,524
6,167
2,890
4,959
923
$/mil gal
404.36
420.67
414.37
511.46
403.36
423.16
422.42
459.03
405.19
423.75
429.35
762.80
-------
TABLE B-ll
SAN DIEGO WATER UTILITY'S TOP SIX MAJOR USERS - COSTS AND REVENUES
Major Users
Kelco Co.
Navy Training
USMC
Convair
Solar Aircraft
Torrey Pines
Revenue
Collected
($/mil gal)
404.36
420.67
414.37
511.46
403.36
423.16
422.42
459.03
405.19
423.75
429.35
762.80
Supply Cost
to Deliver Water
($/mil gal)
508.95
500.86
508.95
500.87
500.87
530.99
108
-------
o
AQUEDUCT
AND
RESERVOIRS
TREATMENT
DISTRIBUTION
$288.85
1
MIRAMAR
$33.83
1
$273.27
I
ALVARADO
$19.29
I
$255.45
I
OTAY
$45.19
I
105.91
FIG. B-4 SAN DIEGO WATER UTILITY CAPITAL & OPERATING EXPENSES
ALLOCATED TO WATER SYSTEM COMPONENTS ($/mil gal)
-------
MAJOR USER
1 TORRY PINES
GOLF COURSE
2 SOLAR
3 CONVAIR
4 NTC
5 USMC
6 KELCO
FIG. B-5 SAN DIEGO WATER UTILITY MAJOR
USERS AND COST ZONES
no
-------
APPENDIX C
TELEPHONE SURVEY RESULTS FOR REGIONS VI AND IX
Table C-l contains the results of a series of telephone inquiries
conducted among major water utilities in Region VI. Table C-2 contains the
results of a similar survey conducted in Region IX.
Ill
-------
TABLE C-l
TELEPHONE SURVEY RESULTS FOR REGION VI
City
Albuquerque
Baton Rouge
*Beaumont
*Corpus Christ!
*Dallas
El Paso
Fort Worth
Houston
New Orleans
Oklahoma City
San Antonio
Shreveport
Tulsa
Source
Ground
Ground
Surface &
Ground
Surface
Surface
Surface &
Ground
Surface
Ground &
Surface
Surface
Surface
Ground
Surface
Surface
Source
Quality
Excellent
Good
Good
Good
Very Good
Good
Good
Very Good
Good
Good
Very Good
Very Good
Excellent
Source
Water
Storage
Yes
Yes
No
Yes
Yes
No
Yes
Yes
No
Yes
Yes
Yes
Yes
1962 PHS
Yes
Yes
Yes
Yes
Yes
Yes
(Surface
only)
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Quantity
mgd
60
33
16
77
194
38
68
80
(surface
only)
125
50
100
30
65
No. of
Meters
80,000
70,000
43,000
56,000
230,000
150,000
(population
of service
area)
115,000
303,000
593,000
(population
of service
area)
125,000
158,033
59,360
120,000
Waste
Water
Use
No
No
No
Yes
No
No
No
No
No
No
No
No
No
Reuse Attitude
Feasibility
Personal in Area
Indifferent
Good No
Good No
Good
Good Yes
Indifferent
Good Yes
Good
Indifferent
Good
Good
Good Yes
Bad
Dual
System
Operation
No
No
Yes
No
No
No
Ho
No
No
No
No
No
No
* Recommended preselection visits.
-------
TABLE C-2
TELEPHONE SURVEY RESULTS FOR REGION IX
City
Anaheim
Bakersfield
Fresno
Les Vegas
Los Angeles
Oxnard
*Phoenix
Sacramento
Salinas
*San Diego
Riverside
San Francisco
San Jose
Santa Barbara
Santa Rosa
Tucson
Vallejo
Source
Ground &
Surface
Ground
Ground &
Surface
Ground &
Surface
Ground &
Surface
Ground &
Surface
Ground &
Surface
Ground &
Surface
Ground
Surface
Ground
Surface
Ground &
Surface
Ground &
Surface
Ground
Ground
Surface
Source
Quality
Good
Very Good
Very Good
Hard
Excellent
Good
Good
Excellent
Excellent
Good
Moderately hard
Good
Good
Good
Excellent
Good
Excellent
Source
Water
Storage
Yes
Yes
No
No
Yes
Yes
No
No
Yes
Yes
No
Yes
No
Yes
Yes
Yes
Yes
1962 PHS
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Quantity
mgd
48
85
59
83
611
14
171
60
8
142
39
250
160
15
23
60
20
No. of
Meters
42,000
40,000
12,000
60,000
614,000
18,675
210,000
90,000
13,000
170,000
40,000
1.7 mil
(pop. of
ser.area)
160,000
15,000
22,000
105,000
24,000
Waste
Hater
Use
Yes**
No
No
Yes
No
No
Yes
No
No
Yes
No**
No
No
No
No
No**
No
Reuse Attitude
Personal
Good
Indifferent
Good
Bad
Good
Good
Good
Bad
Indifferent
Good
Indifferent
Indifferent
Indifferent
Good
Bad
Indifferent
Bad
Feasibility
in Area
Yes
Yes
Yes
Yes
Yes
Yes
No
No
Yes
Dual
System
Operation
No
No
No
No
No
No
Yes
No
No
Yes
No
No
No
No
No
No
No
^Recommended preselection visits
**Wastewater used for ground water recharge only.
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/1-76-033
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
RENOVATED WASTEWATER AS A SUPPLEMENTARY SOURCE FOR
MUNICIPAL WATER SUPPLY: AN ECONOMIC EVALUATION
5. REPORT DATE
October 1976 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Robert M. Clark,* James I. Gillean,** and Kyle Adams**
9. PERFORMING ORGANIZATION NAME AND ADDRESS
*Municipal Environmental Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
10. PROGRAM ELEMENT NO.
1CC614
11. CONTRACTflEJBXJffit NO.
68-03-2071
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
EPA-ORD
15. SUPPLEMENTARY NOTES
Systems, Inc., Winter Park, Florida 32789
16. ABSTRACT
The possibilities associated with the reuse of treated wastewater for domestic water
supply purposes have long fascinated sanitary engineers. Wastewater renovation
allows for the purification of sewage effluent through advanced waste treatment,
making a high quality water available on site for municipal use. The apparent
potential for domestic use of renovated wastewater, coupled with a growing concern
and awareness of problems associated with water supply, as indicated by the Safe
Drinking Water Act of 1974, have made it imperative that an examination of renovated
wastewater as a supplementary source of water supply be undertaken.
The report presents an analysis of the cost of renovated wastewater as a supple-
mentary source of water supply. Two water supply utilities provide the basis for
a case study evaluation of the cost of renovated wastewater reuse.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
Economic Analysis, Economics, Financing,
Research, Systems Engineering, Water
Supply, Waste Disposal
13B
18. DISTRIBUTION STATEMENT
Release unlimited
19. SECURITY CLASS (This Report)
UNCLASSIFIED
21. NO. OF PAGES
130
20. SECURITY CLASS (This page)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
114
S GOVERNMENT PRINTING OFFICE: 1976-757-056/5426 Region No. 5-11
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