Report
to/Rapport au :
Planning and Environment Committee
Comité de l'urbanisme et de
l'environnement
and Council / et au Conseil
27 January 2006 / le 27 janvier 2006
Submitted by/Soumis par : R.G. Hewitt, Acting Deputy City Manager /
Directeur municipal adjoint intérimaire,
Public Works and Services / Services et Travaux publics
Contact
Person/Personne ressource : Kenneth J. Brothers, Director/Directeur
Utility Services/Services publics
(613) 580-2424 x22609, ken.brothers@ottawa.ca
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SUBJECT: |
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OBJET : |
REPORT RECOMMENDATION
That the Planning and Environment
Committee and Council receive this report for information.
RECOMMANDATION DU
RAPPORT
Que le Comité de l’urbanisme
et de l’environnement et Conseil prenne
connaissance du présent rapport à titre d’information.
BACKGROUND
The City of Ottawa has been
providing drinking water services to residents of the City for over 125
years. By and large, the demand for
drinking water has grown as has the City and its population. The infrastructure associated with the
provision of this service has also had to grow to match that increase in
demand. This service is now provided
through an extensive network of water purification plants, booster pumping
stations, reservoirs and approximately 2600 kilometres of transmission and
distribution piping.
The graph below describes how that demand for drinking water has grown over the past twenty-five years.
The original development strategy for the water
infrastructure was to expand the system to ensure that adequate capacity was
available to meet customer demand.
Given the current pressure on existing infrastructure and the
availability of operating and capital funds, more effective and efficient use
of municipal infrastructure is necessary.
In 2004, Council approved a water efficiency strategy, recognizing that initiatives intended to temper the increase in customer demand are both necessary and cost-effective. The report Short and Long Term Strategy on Water Efficiency http://ottawa.ca/calendar/ottawa/citycouncil/pec /2005/04-12/ACS2005-PWS-UTL-0006.htm tabled in 2005, outlined the need to address both the demand and the supply-side of the drinking water service provision. Staff will bring forth a report later this year that will provide further recommendations on demand-side initiatives.
The purpose of this report is to outline a Water Loss Control Strategy
that coordinates all efforts related to water loss control and specifically,
initiatives on the supply-side of the demand equation. Combining these supply and demand
initiatives will provide the most effective comprehensive delivery of drinking
water service to our customers. A
listing of some of the initiatives currently in place are shown below.
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Existing
Supply & Demand Management Initiatives |
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Supply-side Management Activities |
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Demand-side Management Activities |
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Production
Distribution
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Education & Incentives
Regulation
Billing
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DISCUSSION
The City's two water purification
plants, Lemieux Island and Britannia produce, on average, approximately 125.9 x
106 m3/year (340 million litres/day) of drinking water to
satisfy the industrial, commercial, institutional and residential demand in the
City of Ottawa.
The City of Ottawa requires that all connections to the water
distribution system be metered. When
annual production figures are compared against annual billed drinking water
consumption figures, there is a gap that varies between 22% and 28% per
year. This gap has historically been
referred to as unaccounted for water (UFW).
While these figures are better than some utilities, by and large they
are higher than most and higher than recommended industry guidelines. However, there is no standard definition for
unaccounted for water in the industry and this figure is inaccurately portrayed
as the leakage in the transmission and distribution systems.
The water industry has been
compiling international best practices on water accountability and leakage
reduction over the past ten years. The
most innovative approach and recognized best practice has been developed by the
International Water Association and the Water Losses Task Force. They have developed a standard method of
water accounting, known as the Standard Water Balance, which is now adopted
internationally with the American Water Works Association, the National
Research Council InfraGuide and the International Water Association. A standard water auditing process, which Ottawa
is currently implementing, will form the basis of a full water accountability
framework to determine the losses, both real (leakage) and apparent losses
(meter inaccuracies, under registration, theft).
The adoption of this standard
balance will provide very useful information in determining the volumes of
water lost in leakage, and apparent losses.
On a go forward basis, the City of Ottawa will be adopting a philosophy
of calculating leakage in real volume terms and assessing the value of water
both at the retail and marginal cost depending upon whether the losses are
leakage or metering inaccuracies.
The Water
Balance
Using a very pragmatic approach, the industry accepted definitions of water use and loss have allowed the program to develop a standard water balance, as shown below.
This water balance recognizes
that not all drinking water produced at the water purification plants will be
used by customers. Some examples of
these losses include water leakage from the system, unauthorized consumption,
water meter inaccuracies, water treatment process demands and distribution
system flushing water use.
Staff have been able to use work
from previous Unaccounted for Water and Non-Revenue Water Loss Initiatives to
provide an early estimate of the relative losses in the City's system based
upon this new assessment tool.
According to the IWA's standard terminology, these losses have been
categorized as Unbilled Authorized Consumption, Apparent Losses or Real Losses.
Unbilled Authorized Losses are
those drinking water uses of which the City is aware but for which bills are
not issued. Examples include
operational practices such as watermain flushing, cleaning and
firefighting. This is expected by be a
small component of the overall water supplied to the system.
Apparent Losses are those losses that
occur due to water meter inaccuracies at customer buildings, accounting
procedure errors as well as unauthorized consumption (theft). Accounting procedure errors may occur due to
overlapping billing cycles, data transfer errors, misread meters, inaccurate
meter estimates or computer programming errors. Eliminating these apparent losses will generate additional
revenue at the combined water and wastewater rate and result in more accurate
real water loss calculations.
Real Losses are those water losses that occur in the water distribution system due to leakage, such as watermain leaks, water service line leaks, storage tank leaks and storage tank overflow occurrences. Reducing these losses will reduce direct operating costs, recapture valuable water volume for future growth and regain system hydraulic capacity.
The standard water balance
approach was used with 2004 data and the following volumes of water used and
lost are expressed as a percentage of system input (production) water
volume. Using statistics available for
2004, staff have represented these losses as a total volume of water lost and
the water loss as a percentage of overall system production, as shown below.
It is
important to realize that this assessment is based upon previous work and
relies upon a number of assumptions. As
a major part of this strategy, staff will be working with these estimates to
improve the confidence limits of the numbers in order to arrive at a better
estimate of the relative costs of these losses. However, in the short term, this assessment will allow staff to
determine where resources should be applied in order to address the most
significant lost water volume and revenue enhancing opportunities.
Apparent Losses
Apparent Losses represent a far smaller portion
of the volume of water lost within the system, but they could represent a large
revenue opportunity to the City, depending upon the actual source of those
losses.
The Water Loss Control Strategies initiatives
in this area will be fourfold:
1.
Reduction
of the unauthorized usage of the water (theft). To achieve this, efforts will be directed at monitoring more
closely the use of flusher hydrants used by contractors and the associated
water consumption and billing, finding and reducing unauthorized connections to
the system, reducing the number of open meter by-passes and eliminating
unmetered properties;
2.
Reduction
of the meter under-registration. Small
meters are currently being statistically assessed for accuracy, and a small
meter change-out program, involving the replacement of approximately 175,000
meters over 15 years, is expected to be the subject of a report this year. Improving small meter accuracy will improve
the billing of the actual water used by the customer. Perhaps more importantly though, is the large meter change-out
that involves approximately 7,500 meters and 47% of City billing revenue. Increased efforts will be employed to
increase the change-out frequency of large meters and optimize the meter
selection sizing to improve meter accuracy;
3.
Revision
of the water billing software and associated business processes. A review of the system will be completed to
ensure it calculates and retains information to meet operational and reporting
requirements. Specifically, a review of
the procedures to calculate the annual customer consumption will be undertaken;
4.
Review
of current water billing accounts to see that they closely match other City
databases including the property tax base.
Real Losses
Infrastructure Leakage Index
It is recognized that all Real Losses cannot be
totally eliminated from the distribution system. Even the best-maintained and best-managed system will still have
a threshold leakage level, or lowest level of attainable leakage. Using the terminology of the Water Loss
Control program, this is known as the Unavoidable Annual Real Losses
(UARL). It is calculated using the
specific characteristics of each system calculated on best levels of loss
performance. Based upon the City's
infrastructure, the UARL is calculated as 4.1 x 106 m3/year.
The Current Annual Real Losses (CARL) for the
City are 23.5 x 106 m3/year, as determined through the
water balance calculation above.
The Infrastructure Leakage Index (ILI) is a new
performance indicator currently being adopted in many countries around the
world. The ILI is defined as the ratio
of Current Annual Real Losses to the Unavoidable Annual Real Losses (UARL). It is a ratio comparing current utility
performance to its own lowest level of leakage performance. As such, it can be used as a performance
indicator between utilities regardless of their size or geographical
location. Based upon available
information, the City’s ILI is 5.8 (23.45/4.05). In other words, the real losses in Ottawa are 5.8 times more than
the lowest technically achievable level of real losses. For comparison purposes, please find listed
below ILI information for a number of international water utilities.
Infrastructure
Leakage Indexes – International Data of 27 Water Utilities
ILI
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ILI |
International Utility Data
Set
This graph depicts the wide range of ILIs and
Ottawa’s results in relation to 27 water utilities from 20 different countries.
While Ottawa’s ILI is within the acceptable range as proposed by the
AWWA (see Appendix A1), it is the position of staff that Ottawa should reduce
its Infrastructure Leakage Index to a value of 4.0 or less over the next three
years. However, a full economic
analysis of the leakage index is required to optimize the investment of water
loss control to the value of the water losses.
The City will acquire the appropriate analytical tools to determine this
economic level of leakage and will bring subsequent reports to Committee and
Council as appropriate.
Real Loss Control
Initiatives
The following graphic describes the City's plan
to address and reduce the volume of real losses from the City's water system.
The City will be focusing on four different
aspects of our service delivery. These
include addressing:
- Active
Leak Control;
- Pressure
Management;
- the
Speed and Quality of Repairs;
- Pipeline
Asset Management.
Our workplan in each of these areas of work is
decribed in some detail below.
Active Leak Control
The City currently investigates a leak on
either a reactive basis (reported leaks) or a proactive leak detection
basis. The proactive program is
intended to locate leaks that do not surface.
Water leaks can be characterized as reported
and unreported breaks. Reported breaks,
those coming to the surface and reported by the public, are immediately
responded to by the Utility Services Water Distribution Section for leak pinpointing
and generally for immediate repair. The
City of Ottawa repairs the vast majority of all reported breaks within a
24-hour timeframe.
Watermain leaks which have not surfaced are
located through the City’s proactive leak detection program. The City employs the latest in leak
detection equipment and has dedicated staff to undertake the preventative
maintenance program. However, the
current program is based upon a five-year cycle to survey the entire 2600
kilometres of City-owned water distribution system. New detection methods are being assessed to determine if they can
accelerate and improve the survey portion of the leak program. Staff project that by increasing resources
to this program and improving the detection process that the cycle survey time
may be reduced to approximately 18 months in duration.
The current proactive leak detection program
involves surveying only City-owned watermains and services. However, there are approximately 500
kilometres of privately-owned watermains servicing major complex sites like the
NRC Montreal Road Campus, the University of Ottawa and Tunney’s Pasture, as
examples. In many of these instances,
water meters are installed at the individual buildings only, and any water
leakage occuring on these private distribution systems prior to the building meter
is unaccounted for water. These losses
contribute to the overall City water systems leakage figures. Staff will be considering two possible
changes to current practices to address this issue. One would involve installing meters at the perimeter of the
property to ensure that the private owner becomes financially responsible for
leaks from their infrastructure. Where
this isn’t possible, an annual leak detection survey and report may be
required. Any identifed leaks would
require prompt repair. In either event,
changes to the water by-law may be required.
District Metered Areas
The City pumps drinking water through the
transmission, reservoir and distribution systems. Within this system are 14 pressure management zones where
booster stations raise the pressure of water to overcome topography changes and
hydraulic losses within the piping system to deliver water at reasonable water
pressure to all customers served by the City's water systems. At each of these pressure zones, drinking
water flow is metered, and recorded.
However, due to the size, capacity and mixed water usage within the
pressure zones, it is not possible to determine when a leak actually occurs
from the information provided. Further
sectorization of the distribution system is required in order to identify areas
of high night-time flow and probable excessive leakage. This further sectorization is called
District Metering and will provide a great benefit in monitoring water delivery
profiles, leakage event occurrences and allow more controlled repair
activities.
District Metered Areas (DMAs) can vary in size,
depending upon demand and service type, but for most areas, optimal DMA size
ranges up to 5,000 services connections.
Within a DMA, overnight flow monitoring is conducted to determine actual
drinking water flow. If night-time flow
is determined to be too high, a proactive leak detection survey is conducted to
locate, pinpoint and repair the unreported leak as quickly as possible during
regular work hours.
DMAs can be either permament or temporary,
depending upon the nature of the distribution system and the flows within.
Pressure Management
The amount of leakage from any distribution
system is directly related to the water pressure in the distribution
system. If it is possible to reduce the
operating pressure in the distribution system, with little or no appreciable
change in service level, leakage from the system can be reduced. This pressure management approach can be
applied at many scales depending upon residual pressure. However, most often it is included as part
of a permanent DMA installation. Pressure management can be applied as a
permanent reduction, a short term reduction or automated into a time of
day/night-time type of pressure reduction.
Staff will be assessing pressure management area opportunities to reduce
system leakage flow rates, stabilize and reduce system pressures which can
reduce the occurence of watermain and service lateral leaks.
Speed and Quality of Repair
Speed and quality of repair are centered around
the reduction of the leakage run time.
The volume of water lost in any leak is calculated by the flow rate of
leak x leakage run time. The volume of
lost water can be reduced by shortening the leakage run time by the speed of
the leak identification and repair process.
In this context, speed of repairs refers to the operational
responsiveness to a leak event. The
operational awareness of leak occurrence will be improved with better district
metering and active leak control. As a
result of both of these initiatives, staff will be deployed more quickly to
carry out watermain repairs. The result
of these improved operational practices will be to reduce leakage run times and
thereby reduce the total volume of water lost from the distribution
system.
Pipeline Asset Management
This is a continuous, long term strategy
looking at pipe replacement and rehabilitation, materials of construction,
construction standards and inspection.
Funds are annually budgeted to replace and rehabilitate aging piping
with prioritization and selection currently based upon pipe age and watermain
break history. In future, it is
expected that the Active Leak Detection program will identify areas of high
leakage and this condition will be added to the Rehabilitation program project
prioritization process. The City
currently has a progressive system replacement capital program in place.
ENVIRONMENTAL IMPLICATIONS
The City’s Environmental Strategy identifies as one of its goals to
"manage material, human and natural resources as efficiently and
effectively as possible." By
reducing water loss, the City can take best advantage of the existing
infrastructure and resources at hand.
Any effort aimed at reducing the amount of water lost between the
production of drinking water and its end use, has positive environmental
impacts. These impacts range from reduced energy used to transmit water,
reduced chemical consumption to producing less water and possibly, less water
collected for wastewater treatment. All
of these are important environmental consequences that help the City progress
towards its commitment as expressed in the Environmental Strategy.
PUBLIC CONSULTATION
The City's Water Loss Control program was presented to the
Environmental Advisory Committee at its meeting of January 12, 2006. The Environmental Advisory Committee is
expected to advise PEC of their perspective on the program in the near future.
FINANCIAL IMPLICATIONS
The City has approved as part of
the 2006 capital budget spending of $343,000.
This spending level is projected to continue for ten years in the same
amount. This funding will be directed
to constructing the initial pilot DMAs and associated infrastructure, extension
of the SCADA system for DMA monitoring purposes and the replacement and upgrade
of some of the leak detection equipment.
Reduction in apparent losses is
expected to generate additional revenue for the City. It is difficult to predict the value of these revenues as the
nature and type of apparent loss is unknown.
To address real water losses from
the drinking water transmission and distribution systems, the program
recommends an expanded proactive leak detection program. For 2006, this increased operating budget
requirement will be accomplished through reallocation of existing
resources. This will allow staff to
better determine any future operating budget requirements based upon working
experience. In future budget years, it
is expected that the expanded program will be maintained and that additional
funds will be requested at that time.
An increased proactive leak
detection program is expected to identify an increased number of watermain
leaks requiring repairs. The funds
required to complete these repairs will be taken from the existing Water Rehabilitation
Program.
SUPPORTING DOCUMENTATION
Appendix A1: AWWA Water Loss Committee Guidelines (2003)
Appendix A2: World Bank Institute Classification (2005)
DISPOSITION
Drinking Water Services
Division will implement the Water Loss Control Strategy in 2006. Staff will prepare an Annual Report to
Committee in 2007.
Appendix A1
Appendix
A2
