Use of Flow Modulated Pressure Management in York Region, Ontario, Canada

Transcription

1 Leakage Conference Proceedings Page 1 Use of Flow Modulated Pressure Management in York Region, Ontario, Canada A M Lalonde Veritec Consulting Inc., Canada alain@veritec.ca Keywords: Pressure Reduction; Flow Modulation; Water Loss Background Information Demand Side Management (DSM) initiatives have quickly been recognized within the water industry as cost-effective alternatives to supply side initiatives for providing a new source of water supply to accommodate new demands and growth. The Regional Municipality of York (York Region), located just North of the City of Toronto in Ontario, Canada (see Figure 1.1) understood the benefits of demand side management initiatives and decided to incorporate DSM into its long-term water supply strategy. Figure 1.1 York Region is the fastest growing municipality in Ontario with average population growth of 5% per year. Population in York Region as at December 2004 was estimated at 889,600 and is expected to grow to 1.28 million by 2026 ( In 1995, the Region of York initiated the long-term water project, which had the goal of establishing a strategy that would ensure a sustainable supply of water until the year The project identified four major components to achieve this goal: 1. New supply agreement with the City of Toronto Completed 1998

2 Leakage Conference Proceedings Page 2 2. New supply source from Lake Simcoe for Georgina Completed New supply connection from the Region of Peel Project Started Demand Side Management Initiatives The strategic plan highlighted above uses a combination of supply side and demand side alternatives to ensure a sustainable supply of potable water to accommodate the substantial system growth. Demand Side Management Initiatives Water For Tomorrow The Region of York Long Term Water Project identified demand side management as a viable cost-effective measure to obtain additional system capacity to accommodate system growth. The Region completed a review of available DSM measures and identified four particular measures that they selected to implement Region wide. These four measures are: 1. Residential and ICI Toilet and Showerhead Retrofit Program 2. ICI Water Audit Program 3. Public & School Education Programs 4. Leakage Reduction Program The DSM project implementation was named the Water For Tomorrow program. It was started in 1998 and will continue until June 2006 ( The entire project goal was to recover a total of 19 MLD, which is enough water to service a population of over 50,000 people. The remainder of the paper will focus on the Leakage Reduction Program and provide details of one particular component dealing with flow modulated pressure management. Leakage Reduction Program The strategy selected by the Region of York in order to address and reduce water leakage within their water distribution systems was to implement District Metered Areas (DMA) and Flow Modulated Pressure Management Areas (FMA). This methodology is relatively new in North America for active leakage control but is also promoted as the most effective method available. The project goal for the leakage reduction program was to achieve a sustained water savings of 5.96 MLD (1.31 MGD). York Region selected the engineering firm of Veritec Consulting Inc. of Mississauga, ON to implement the leakage reduction program at a total projects cost of $2.2 million CDN. At the time, the program was the largest and most aggressive active leakage control program in North America. To enable efficient control of recoverable leakage, the distribution systems that make up York Region were divided into 65 temporary DMAs. These DMAs are being used both to identify and reduce recoverable leakage in the short term and then to monitor and control leakage in an ongoing manner. In addition to the 65 temporary DMAs, 10 dynamically controlled permanent pressure management schemes were introduced to allow unnecessarily high pressures to be efficiently controlled, to reduce background leakage volumes and new leak frequency, while continuing to meet hydraulic and fire fighting requirements.

3 Leakage Conference Proceedings Page 3 In addition to the DMAs and FMAs mentioned above, routine leak pinpointing and repair also plays a major part in the leakage reduction strategy. Temporary DMAs Leakage control, using the DMA approach, is based on the measurement of water usage within isolated areas of the water distribution system to hone in on areas of high leakage, during the initial test and then to monitor the level of leakage in an ongoing manner. Controllable zones are established such that by closing appropriate line valves, these areas can be supplied via a single pipe (preferable and less costly) or by a number of metered inputs (see Figure 1.2). The size of the zone depends on the demand, the demand types and the hydraulic capacity of the main pipes feeding both the zone in question and the neighbouring zones. They can vary in size from 1500 to 3500 connections. A sensitive flow measurement device (in this case an insertion turbine meter) is installed onto the supply pipe and a 7-day demand and pressure profile is recorded using data loggers. These profiles are presented graphically and the average minimum night flow (MNF), which is normally obtained between 12:30 am to 5:30 am, is calculated. (These profiles in conjunction with other strategically placed pressure loggers are also used to identify areas with high potential background leakage, which will then justify permanent pressure management schemes.) Figure 1.2 Recorded Profile vs. Estimated Legitimate Demand Recorded Profile Flowrate Estimated Leakage Estimated Legitimate Demand AM 1:00 AM 2:00 AM 3:00 AM 4:00 AM 5:00 AM Time Figure 1.3

4 Leakage Conference Proceedings Page 4 Once a repeatable MNF has been established, any legitimate usage during the MNF period is determined and subtracted from the MNF. Legitimate night-time usage is determined using proven allowances for residential accounts, or through actual meter readings for larger ICI accounts. Hence, any remaining MNF can be classified as potential system leakage (see Figure 1.3). This methodology helps to prioritize areas of high leakage, and, in addition, quantifies the rate of leakage in each zone to be used in payback calculations, or to justify further investigation. After high leakage areas are identified, the individual leaks are located, pinpointed and repaired. The first step to assessing leak locations is by completing controlled valve closures known as Step Tests. By isolating various sections within the DMA from the district flow meter, it is possible to record any flow reduction associated with the isolated area. A large reduction in flow indicates a high potential for leakage in the section last isolated. Step testing is normally conducted during the night, and the various steps are isolated for only a few minutes to minimize disruption. Step testing can also provide the ability to locate leakage in difficult areas, or on non-metallic mains. Leak Detection & Repair Once a leak has been identified and quantified through step testing, it is then pinpointed using proven sonic and correlation techniques. Leak noise correlators are becoming the method of choice for pinpointing leakage. With recent technological advancements, correlators can now pin-pinpoint leakage on all types of mains including PVC, which has been traditionally difficult due to the high attenuation of leak sound within the pipe walls and the low frequency sounds available. The final step of the process is to mark the leak location, confirm the leakage rate through on site measurements, and repair the leak. Once the areas have been cleaned of recoverable leakage, a baseline flow is determined and the area is monitored on a routine basis to identify when leakage starts to develop again. Once leakage is identified again in justifiable amounts, the whole process starts again. Permanent Pressure Management Areas As mentioned earlier, 10 of the 65 temporary DMAs will become permanent pressure managed areas. The 5 basic steps taken to identify the areas, which will become permanent, are itemized below: Selecting the FMA Location & Boundary The first stages of selecting a sub-sector take place in the office, during the selection of the initial DMAs. The first stage is an inspection of plans to decide on a suitable area, where there is potentially high pressure. The majority of the plans were available on paper and some areas were available in GIS or AutoCAD format. The area should be controllable; in other words it should either be isolated from the general system naturally or by a series of valve closures. Several pressure control valves may be used if hydraulically necessary, or as a safety feature to ensure suitable fire fighting conditions. Demand analysis Demand analysis is undertaken to identify the types of consumers in the potential sector and their specific requirements. During the demand analysis phase, particular care is

5 Leakage Conference Proceedings Page 5 given to potential seasonal changes, and to hydraulic and fire fighting capacity. A very simplified hydraulic model is used to calculate potential head losses under normal and stressed conditions, between the supply point and the critical node. Field measurements Once the paper work phase is completed it is time to go into the field and make some preliminary measurements of pressure and flow. These measurements are used to identify the potential benefit of control and to confirm the simple hydraulic models. The field measurements are processed and entered into a special software model for final analysis of cost to benefit and type of control. Type of control, control limits and dimensioning The type of control is determined by the field conditions measured in the above stage. There are three types of basic controls available: Fixed Outlet, Time Based and Flow Modulated. However as a high priority has been given to maintaining fire fighting requirements, only flow modulated pressure control were used. Final cost to benefit calculations Once all of the determining factors have been identified, the potential cost of the installation(s) is weighed against the potential benefit. Each sector is analyzed using the model prior to field installation. The results from the model include the most efficient type of control and the overall payback for the installation. The Type of Control Selected for this Project Flow Moulated Control This is a relatively new technique, which has proven to be the best type of control for areas with changing conditions, headloss, fire flow requirements and the need for advanced control. This type of control is affected by controlling outlet pressure in relation to demand by connecting the controller to a metered signal output. Modulation of outlet pressure is achieved by altering an opposing force against the pilot spring. The advanced controller has a local data logger and optional remote communications. Control can be completed with a preset profile, of 256 points, which fits the changing relationship of demand and headloss in the sector (see Figure 1.4). Alternately a direct communications link can be made between the controller and the critical point. Obviously the second option involves communications and therefore higher costs, which were not included in this project.

6 Leakage Conference Proceedings Page 6 Figure 1.4 In general installation costs are higher for dynamic control, however additional savings due to more intelligent control usually make this type of control more desirable (see Figure 1.5). Figure 1.5

7 Leakage Conference Proceedings Page 7 Results to Date The DMA program, comprising of the 65 areas and targeting unreported recoverable leakage, as yielded results of 7.65 MLD (1.68 MGD) of sustained water loss savings exceeding the 5.21 MLD (1.15 MGD) target by 147%. Similarly, the FMA program has also exceeded targets. A short description of one of these areas follows. Two of the FMA schemes operate in the same isolated area within Richmond Hill and are referred to as RH 6-1 & RH 6-2 Richvale Area (see Figure 1.6). The pressure management area is comprised of 45 km (28 miles) of watermain with a total of 4250 connections mostly residential with some small commercial and school sites. Figure 1.6 The area has an average night zone pressure of 56 m (80 psi). The projected pressure scheme highlighted an average reduction of 15 m (22 psi) across the isolated area with a resulting estimated savings of 8% of average annual day demand. The two feed points and control installations are on Shaw Blvd. 200 mm (8 ) PRV with a 75 mm (3 ) PRV low flow by-pass, and on Langstaff Rd. 150 mm (6 ) PRV with a 75 mm (3 ) PRV low flow by-pass. The chambers were constructed using a pre-fabricated rectangular chamber (see Figure 1.7). Figure 1.7

8 Leakage Conference Proceedings Page 8 The results of this area support the expected savings calculations. To date we are implementing an average reduction of 10 m (14 psi) with an average savings of 6.5 % of average annual day demands (see Figure 1.8). The full 15 m (22 psi) reduction will be set for the final year of the program to enhance the water savings. Flowrate (m3/hr) /11/02 30/11/02 York Region - Leakage Reduction Program Demand Profile for Richmond Hill- RH 6-1 & RH 6-2 (South Richvale) 01/12/02 Flow Modulated Control 02/12/02 03/12/02 04/12/02 05/12/02 06/12/02 Date / Time 07/12/02 No Control Total Flow (RH 6-1 & RH 6-2) Inlet Pressure RH 6-2 Outlet Pressure RH 6-2 Inlet Pressure RH 6-1 Outlet Pressure RH /12/02 09/12/02 10/12/02 11/12/02 12/12/ /12/ Pressure (m) 300 York Region - Leakage Reduction Program Demand Profile for Richmond Hill- RH 6-1 & RH 6-2 (South Richvale) 250 Flowrate (m3/hr) Average Daily Demand - No Control = 4579 m3/day Average Daily Demand - FMA Contol = 4277 m3/day Achieved Water Savings = 302 m3/day (0.30 MLD) Average Water Savings = 6.5% of AADD 0:00 2:00 4:00 6:00 8:00 10:00 14:00 16:00 18:00 20:00 22:00 0:00 Time Average Daily Profile - No Control (Dec. 6 to Dec. 13, 02) Average DailyProfile - Flow Modulated Control (Nov. 29 to Dec. 6, 02) Figure 1.8 To date, we have achieved 164% of the total project goal of 0.73 MLD with respect to the flow modulated pressure schemes with only 60% of the sites in full operation. In addition, we would like to stress that no complaints have been recorded in any of the implemented areas. Table 1.1 below illustrates the predicted savings and achieved savings from each of the flow modulated schemes.

9 Leakage Conference Proceedings Page 9 Table 1.1 FMA Area Name Predicted Savings Achieved Savings Richvale RH 6-1 & MLD 0.30 MLD Oak Ridges RH MLD 0.46 MLD Newkirk RH MLD 0.32 MLD Maple VA MLD TBD Wilshire VA 6-1A & 6-1B 0.14 MLD 0.12 MLD South / West Thornhill VA 5-2 & MLD TBD Totals 1.69 MLD 1.20 MLD Acknowledgements The author would like to thank Mr. Michael Brooks of United Utilities Canada Limited and Mrs. Debbie Korolnek, P.Eng. of the Region of York for their support throughout the project to date. Additional thanks go to Mr. Julian Thornton of Thornton International Ltd. whom provided technical details for this paper.