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 Vancouver encompass large areas and population. Each zone is fed through 2 to 3 Pressure Reducing Stations. As currently configured, 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 system. • 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 Aqua-Phone 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 time. 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 Leak 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 Hydrant P/T Leak 14% 9% Service Leaks 10% Valve Leak 13% Hydrant Main Leak P/D or Break 52% Hyd. Req. 2% Maintenance 0% • 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 risk!!! 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 1/2-Turn 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 through Minor copper 266 331 65 486.2 $0.52 $0.96 $22.98 $160.86 $8,387.76 1/2 inch cut through Moderate copper 423 555 132 987.36 $0.52 $1.94 $46.67 $326.67 $17,033.61 3/4 inch cut through 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 8 12 Minor 56 9 Severity 4 Moderate 2 18 7 Major 3 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. CONCLUSION 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. Questions?