Vancouver Waterworks Proactive Leak Detection

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					 Vancouver Waterworks

Proactive Leak Detection
Leak Detection - Topics of Discussion:
   • Introduction
   • Background
   • Why is it Necessary?
   • How is the City Surveyed for Leaks?
   • Leak Detection Equipment
   • Types of Leaks
   • Leak Survey Trial 2009
   • Physical and Financial Damage
   • Conclusion
A Few Facts:
The City of Vancouver Water Utility is classified as a level 3 system
servicing a population of 601,200 residing in an area of 115 km2.
    The water distribution system is comprised of 1,450 km of mainline and a
    total of 94,112 service lines.
    The average age of the piping network is 39 years with mains ranging
    from 950mm (36 in) to 100mm (4 in) in diameter.
    The distribution system represents an estimated worth of $1.5 Billion
    to City Taxpayers.
    On an average day, the Vancouver water system delivers 360 million
    liters of high quality water to its customers.
To support the sustainable use of water, the City of Vancouver has
developed a Water Loss Management Plan which focuses on the
following 5 key areas:

                                  • Failure Repair Speed and Reporting

                                  • Pressure Management

                                  • Infrastructure Renewal

                                  • Metering - Voluntary or Universal

                                     Proactive Leak Detection
                                  • Leak Survey Program or…

     Capilano Lake Reserve
    Why We Do Proactive Leak Detection?

Because a large proportion of leaks go
unnoticed due to:

•   highly permeable ground conditions

•   proximity of sewers or other trenches

•   low volume of flow

                                            Joyce Road at Monmouth 2004
                   Why We Do Proactive Leak Detection?
The Water
Pressure Zones in
the City of
encompass large
areas and
population. Each
zone is fed
through 2 to 3
Pressure Reducing
Stations. As
monitoring late
night flows for
indications of new
leaks is not viable.
   How Do We Survey the Entire City for Leaks ?
• By dividing the city into a grid-like fashion it allows the Proactive Leak
Detection team to efficiently search the city’s water distribution
• The goal of the Proactive Leak Detection program is to cover a third of
the city every year, so that no single leak goes undetected for more than
three years. Experience has shown that searching an area for leaks every
year does NOT provide an adequate cost benefit. However, using the three
year rotation vastly increases the overall cost benefit of the program.
        How Do You Detect A Leak You Can’t See ?
Such leaks are often identifiable through acoustic detection surveys.

These surveys combine the use of:

  • leak noise data loggers programmed to
    listen for and identify leak noises

  • leak noise correlators are used to find the
    specific location of a leak

  • manual instruments such as aqua-phones.

 The Vancouver water system is well suited to acoustical survey techniques, given
 that the piping network is largely constructed of metallic materials (cast iron,
 ductile iron, steel and copper) that transmit leak noise well.
Data loggers are left in place and used to monitor the network over periods of time.

 Data logger with caution plate     Data logger in place            portable patroller

Any leaks identified are indicated by a flashing red light on the unit.
Data can be picked up by:
• plugging loggers into a laptop or
• remotely, by transmitting data to the patroller carried in the service vehicle.
Once leaks are identified, correlation equipment is used to pinpoint the location

   Transmitters (A and B) are placed on either side of the leak sending
   information to the receiver (C), hence arriving at the exact location of the
   leak by comparing signal strengths.
Other equipment used include manual units
such as aqua scopes which assist us in
detecting leaks by amplifying leak noises

Also more simplistic, although effective
equipment can help us pick up the sound of
running water resonating along the metallic
piping. This technique can be applied
manually or by connecting to a receiver in
order to compile data over extended periods of
         What are the Different Types of Leaks ?
Leaks throughout the city can usually be classified into four main categories.

            Service Leaks                          Valve Leaks

             Main Leaks

                                                 Hydrant Leaks
      What is the break down on leaks found ?

So far, as of November 2009, the Proactive Leak Detection program
has found the following:

                                      Number of
                 Type of Leak         Incidents
                    Hydrant              11
              Hydrant Pulldown (PD)      66
                      Main                2
                   Valve Leak            16
                     Service             12
              Property Trouble (PT)      17
How Common are the Different Types of Leaks ?
                    2009 Leak Survey Trial Breakdown
                           P/T                          Leak
                          14%                            9%
 Service Leaks

Valve Leak
        Main Leak                                                  P/D
        or Break                                                  52%
                     Hyd. Req.
• Of the total number of leaks found during Pro Active Leak
Detection, 52% of them were Hydrant Pulldowns making it the
most common type of leak in the city.

• A Hydrant Pulldown occurs when a hydrant is used and is not
properly closed which in turn causes it to leak. To remedy the
situation a crew is required to “pulldown” or tighten the hydrant seal.

•   After the repair is completed the leaking hydrant is documented
and tracked to assess the frequency of leak re-occurrence, and be
factored into the aging hydrant infrastructure renewal strategy.

                                              Joyce Road at Monmouth 2004
Of the 52% of Hydrant Pulldowns it should be noted that all of them were found on
slide gate hydrants not compression hydrants. Although compression hydrant
pulldowns do occur, they are far less common.

                 The slide gate hydrants generally leaked at the
                 gate seal, with leakage not surfacing, as
                 hydrants are typically installed in crushed rock
                 to enable quick draining.
           How Destructive Can A Leak Be ?
• Actively finding leaks is extremely important as an undetected
leak can cause damage to the surrounding area.

• The severity of the physical damage a leak can cause is
dependant on a number of factors. These factors include leak hole
size, PSI, surrounding ground/infrastructure conditions and the
duration the pipe has been leaking.

•  Of all the factors stated above it is the time period the pipe has
been leaking that is most important. A leak that is the size of a pin
hole that has been leaking undetected for ten years can be just as
wasteful as a bigger hole leaking for a much shorter period of time
(which has a greater chance of being detected anyways) .
• Leaks can cause damage……
         How Destructive Can A Leak Be ?
• Medium damage….
         How Destructive Can A Leak Be ?
• and sometimes even the smallest leak……
          How Destructive Can A Leak Be ?
• can cause Massive undermining that may put individual’s lives at
How Destructive Can A Leak Be ?
              How Costly Can A Leak Be ?

•While the physical damage a leak can cause can be very dramatic
it should not overshadow the financial loss. To get a better idea of
the financial hit a leak can incur, Vancouver Water Works
Operations conducted a controlled leak experiment.

•The experiment involved cutting different leak hole sizes (which
were classified as Minor, Moderate and Major) into various pipes
and hydrants and seeing how much water was actually lost over an
hour period.

•With the amount of gallons lost per hour it is then possible to
estimate a dollar figure (using GVRD rates) on how much a leak can
cost the city over an extended period of time.
                                How Costly Can A Leak Be ?
                Leak Hole                             7.48 US GAL=         $ / m3
                   Size                                   1-cu ft       (GVRD Rate)
 HYDRANT         volume-      Start   Stop    Total     us gals/per      35.3cu ft =      1        24         7         365
(Slide Gate)      cu/ft       cu ft   cu ft   cu ft         hr              1m3          Hour     hours      days       days
   Minor       from closed    27.01   36.86   9.85        73.68             $0.52       $0.15      $3.48    $24.38    $1,271.10
               2-Turns from
 Moderate         closed      1.15    27.01   25.86      193.48             $0.52       $0.38      $9.14    $64.01    $3,337.80

                                                       7.48 US
                Leak Hole                               GAL=             $ / m3
                   Size                                 1-cu ft       (GVRD ate)
                 volume-      Start   Stop    Total   us gals/per      35.3cu ft =               24          7         365
 SERVICE          cu/ft       cu ft   cu ft   cu ft       hr              1m3        1 Hour     hours       days       days
               1/4 inch cut
   Minor          copper      266     331      65        486.2           $0.52       $0.96      $22.98     $160.86   $8,387.76
               1/2 inch cut
 Moderate         copper      423     555     132       987.36           $0.52       $1.94      $46.67     $326.67   $17,033.61
               3/4 inch cut
   Major          copper      555     795     240       1795.2           $0.52       $3.54      $84.85     $593.95   $30,970.20
The third of the city that was proactively searched s yielded the
following results. Cost of the proactive leak detection program for
2009 was approximately $75,000 (leak detection truck with operator
and labourer for 2/3rds of the year).
                                                            2009 Leak Severity





                         0                   10        20            30      40       50           60
                                                        Number of Leaks Found
                             Hydrants                  Water Mains           Valves        Services
So - How long can a leak run undetected and at what cost ?

 From the wear on the pipe and shut off valve at the leak point it is possible
 to assume that the leak has run for many months. For others it is nearly
 impossible to know how long a leak has been running
                  How Costly Can A Leak Be ?
Using the number of leaks found and the corresponding severity
dollar amount for each leak, it is possible to obtain an approximate
cost for the various kinds of leaks found.
                  Total Number      24
     Type           of Leaks      hours     7 days   3 months   6 months   365 days
    Hydrants                     $387.06
 (includes P/D)       77                    $2,709   $35,300    $70,500    $141,000
    Services                     $1,374.5
 (includes PT)        29            7       $9,621   $125,500   $251,000   $502,000

The graph above illustrates potential savings the Proactive Leak
Detection program may have saved the city over a given period of
time. Because the leaks found through the leak detection program
do not show above ground we can assume that many could have
run for 3 to 6 months or longer. The cost of the lost water with an
average of 3 months per leak is $160,000 or $320,000 for 6 months.
              How Costly Can A Leak Be ?

Besides the cost of the lost
water, undetected leaks can also
potentially have liability costs
associated with it as well.

Finding leaks before they cause
hazardous situations (i.e. an
undetectable sinkhole on the
road) can potentially reduce the
number of risk management
claims against the city.

The Proactive Leak Detection program plays a vital role in
maintaining Vancouver’s water distribution system. Through the use
of efficient search methods and proven technology, a leak can be
detected and repaired before further infrastructure and financial
damage is caused. At a cost of $75,000 for the program in 2009, it
is estimated that the City may have saved $160,000 to $320,000 in
the purchase of water alone.

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