Non Revenue Water Reduction Projects for Local Governments of Korea

Transcription

1 Leakage 25 - Conference Proceedings Page 1 Non Revenue Water Reduction Projects for Local Governments of Korea H Woo*, H Ahn**, J Kim***, W Cho****, S Kim*****, S Choi****** * Korea Water Resources Corporation, #462-1 Jeonmin-Dong, Yusung-Gu, Daejon, Korea, paulose@kowaco.or.kr ** Korea Water Resources Corporation, #462-1 Jeonmin-Dong, Yusung-Gu, Daejon, Korea, anwon@kowaco.or.kr *** Korea Water Resources Corporation, #462-1 Jeonmin-Dong, Yusung-Gu, Daejon, Korea, jhkim@kowaco.or.kr **** Yonsei University, #134 Shinchon-Dong, Seodaemun-Gu, Seoul, Korea, woncheol@yonsei.ac.kr ***** Korea Water Resources Corporation, #462-1 Jeonmin-Dong, Yusung-Gu, Daejon, Korea, skim@kowaco.or.kr ****** Korea University, Ahnam-Dong, Sungbuk-Gu, Seoul, Korea, eechoi@korea.ac.kr Keywords: Non Revenue Water Project, Leakage Reduction, Block System Introduction Current Problems and Issues Korea ministry of environment says that national amount of real loss water among the drinking water produced is about 8 million /year by recent published water statistics book (MOE, 24). If the loss could be converted as money, the lost revenue to Government is about $ 5 million per year. Improving accounted for water rate is prevailed recent years in local governments of Korea. The Korean government has promoted the need for: Efficient use of limited water resources by decreasing the volume of leakage, Rehabilitating old pipes and improving the efficiency of water treatment, preventing virus outbreaks by improving detection methods and by adopting improved treatment methods. Case Study Existing Problems for Masan City Over 32 million m3 of water lost per year in Masan through NRW, this is equivalent to $ 16 million per year in lost revenue. NRW has increased over the past 1 years due to deteriorating pipes and high network pressures. Faced with the need to rehabilitate the network to reduce revenue losses, progress has been delayed due to difficulties in fixing a budget. Production requirements at Chilseo WTP have increased due to increasing NRW. As a result, there are plans for expanding the WTP to meet the growing production needs, requiring further financing by Masan City. Municipal Government unlikely to receive any further loans due to their existing financial debt for drinking water. Increased public mistrust of the quality of water supplied due to contaminants in the network. This is compounded by the serious virus outbreaks in Korea that have undermined the public s confidence in the water treatment and supply systems. Water Quality to consumers is not guaranteed. The aging network is showing signs of further deterioration unless major replacement program is undertaken. Customers currently receive a poor water service that is likely to worsen, as problems at the WTP and network increase. High NRW will increase operating costs. NRW could increase from 49% to around 6% in the future. Additional production volumes required as NRW losses would increase.

2 Leakage 25 - Conference Proceedings Page 2 Current Status of Water Supply Operations Masan is a port city with a total area of 33 km2, and is located on the southern coast of Gyeongsangnam-do. With Changwon City situated on its eastern flank, Masan is approximately 5 km west of Pusan, the second city of Korea. With a current population of over 43,, Masan City has seen a slight reduction in the number of people. The average growth rate over the past 1 years has decreased by 1.2%. Although the trend is for a slight decrease in population overall since 199, the local centres of Naeseo-eup, Jindong-myeon, Jinbukmyeon, Jinjeon-myeon and Gusan-myeon have seen an increase in the number of inhabitants. Water Production In 21, a population of 399,272 were served by the water Supply Service, representing a coverage ratio of 93% of the total population. The number of connections was 41,271, comprising 29,564 domestic taps and 11,77 non-domestic connections. Water production to Masan City in 2 was reported at 66,415,154 m3, with accounted-for volumes representing only 51% of the total delivered flow, at 34,1,23 m3. Water abstracted from the Nakdong River is treated at Chilseo Water Treatment Plant. Treated water is then shared between Masan City and other population centers at Haman, Changyeong and Changwon City (through a Bulk Supply Agreement) Table 1. Summary of Statistics for 2 REVENUES FROM WATER Water Supply Income 16,83 VOLUMES SOLD (M Won) Bulk Water Supply Income 4,323 TOTAL 2,46 OPERATING COST FOR Direct Operating Costs 14,668 WATER SUPPLY (M Won) Renewals and Maintenance 5,147 Vehicles, Tools and Furniture 161 Debt Payments 1,573 TOTAL 3,549 Net Loss in M Won (1,143) Production and Sold Volumes Production Volume Sold Water Volume Non Revenue Water 66.4 million 34. million 32.4 million Average Revenue Water % Whole of Korea Kyungnam Province Masan City 73.4% 7.5 % 51.2 %

3 Leakage 25 - Conference Proceedings Page 3 Table 2. Source: Statistical Annual Report of Masan City in 2 (Masan City, 2). Summary of Water Supply Data for Masan City 2 Total Population 434,49 Serviced Population 398,5 Rate (%) 92 Domestic Taps 29,33 Taps for Business Service 4,954 Commercial Taps 6,542 Taps for the 1 st Bath 83 Taps for the 2 nd Bath 3 Total 4,885 58,8 12,188 18, Total ( /day) 89,737 Domestic Use ( /day) Business Use ( /day) Commercially Use ( /day) Type 1 Public Baths ( /day) Type 2 Public Baths ( /day) Distribution Network Masan City records of the existing pipeline length are not fully complete. However, our field study revealed the following breakdown of the existing pipeline. From table 3 to 5 detailed network status is shown. Table 3. Pipe Detail By Diameter Diameter (mm) < TOTAL LENGTH Length (m) 442, ,327 47,84 136, ,972 55,327 29,21 12,927 3, , , ,937 45,614 Table 4. Pipe Detail By Material Pipe Material Length (m) CIP DCIP GP PE Others TOTAL 28, ,318 73, ,12 65, ,324

4 Leakage 25 - Conference Proceedings Page 4 Table 5. Pipe Detail By Age (Source: Masan City for intake pipes and transmission pipes) Length of Pipe in m Location Diameter Age < 1 years Age years Age > 2 years TOTAL LENGTH Intake 18 mm Transmission Pipes mm 2,5 2,5-41, Distribution Pipes 75-1 mm 125,477 23,812 35, ,551 Service Pipes mm 366, ,68 47,9 627,773 TOTAL 512, ,92 82,271 1,34,189 (5%) (42%) (8%) (1%) Despite the efforts of Masan City to replace pipes and meters, NRW remains very high. The effectiveness of the replacement programme is questionable. Only one leak is detected per day by a small team equipped with limited equipment. The high pressure in the distribution network contributes to the high level of NRW. Key equipment such as pumps and valves do not receive adequate preventative maintenance. Hydraulic simulations of the network indicate that significant inefficiencies exist at Heowon, Kuam, Jungli and Samgei Pumping Stations. Lack of Drawings and customer records prevents effective planning to be made. Poor design of the network has resulted in many pipes being laid in accordance with an inefficient layout or with insufficient diameter. Planned shut-downs of the network during an emergency incident following a pipe burst. As the leakage rate is high (39% of existing production volumes are reported as leakage), it can only be assumed that mains shut-downs for repairing bursts is a common problem. Certainly, the lack of existing or accessible gate valves in the network results in the inability to localise the interruption to a small area that would only affect a smaller number of customers. As a result, a very large proportion of the total number of customers are affected by a leak or burst in another part of the network. On-going Projects The Masan City on-going projects can be divided into: Replacement of old pipes and Repair of Pipe Bursts, Replacement of Meters, Construction of new works Pipe Replacement: The replacement program by Masan City concentrates on replacing the small diameter pipes (<1 mm), which can be illustrated by the average cost of the works. The pipe materials generally replaced are : Polyethylene (PE) pipes laid before 1995; Galvanised Pipes (GP). However, Masan City s program of replacement is not focused on one or two specific locations, but is spread throughout the whole city. Consequently, all the good work undertaken is not put to best effect. It would be more effective to reduce the leakage in specific zones rather than by replacing several small sections along a pipe that is very poor in quality throughout its total length. Burst Repairs: The total number of detectable leaks per year is estimated to exceed 1,7. Currently Masan City are reported to repair approximately 36 leaks per year (1 per day). However, as can be seen on the following table, Reported Leaks only represent

5 Leakage 25 - Conference Proceedings Page 5 1% of total volume of leakage, and is clearly a major factor in Masan City s difficulty in reducing the leakage volumes. Hence, the NRW has remained very high over recent years. Replacement of Customer Meters: Masan City s ongoing program for replacing meters every eight years for connections up to 5mm in diameter, and every six years for larger connections, is bound by statutory law. In effect, approximately 5, meters of the 41, existing metered connections should be replaced annually. However, there consistently remains over 3,5 customer complaints per year regarding problems with meters (leaking valves, meter trouble), which perhaps are not addressed in this meter replacement program. Construction of new works: Based on our discussions with Masan City, there is only one new ongoing project concerning the abandonment of Heowon Pumping station, which will be replaced with a new booster station. Leakage The two flow meters that monitor the flows to West Masan and East Masan are regularly checked for accuracy, and indicate the degree of leakage. Average Leakage for 21 =71,588 /day. Account Number Table 6. Results of Meter Under-Registration for 11 Large Consumers Dates of Study Study Duration Volume (m3) Meter Error (% consumption) meter (days) start end Vivendi meter /1/21 1:42 18/1/21 1:9 1.98day 15 mm 1,351 1, % /1/21 16:9 25/1/21 16:2 1.1day 1 mm % /1/2 14:44 19/1/2 14:11.98day 15 mm % /1/21 12:17 22/1/21 1: day 1 mm 1,715 1, % /1/21 15:16 22/1/21 14: day 1 mm 1,748 1,61-8.6% /1/21 11:58 23/1/21 13:42 1.7day 1 mm % /1/21 12:41 23/1/21 14:3 1.6day 1 mm % /1/21 15:14 23/1/21 16:36 1.6day 8 mm % /1/21 15:45 24/1/21 1:28.78day 1 mm % /1/21 14:55 24/1/21 15:18 1.2day 1 mm % /1/21 17:9 25/1/21 9:53 1.7day 1 mm % 7,877 7, % Dia of Excessive length of tertiary network. 78% of total network length is up to 1mm in size. These smaller pipes are exposed to the highest incidence of bursts. Current network layout comprises a high proportion of manifold-type connections fed off a central feeder pipe. In other comparable cities, this ratio is around 65%, which means that there is an excess of 13% (13 km). Most leakages occur in: Poor quality PE laid before 1995, Galvanised GP pipes, 47 km of pipes bad PE has been laid before 1995, primarily for tertiary network. (39 km with diameter less than 65mm). Masan City undertaking a strategy to replace the low quality PE pipe. In parallel the GP network length has drastically decreased during recent years. However, the old CIP pipes and PFP need to be replaced as well.

6 Leakage 25 - Conference Proceedings Page 6 Evolution of PE Tertiary network Length of PE tertiary network (m) 6, 4, 2, Years Evolution of GP Pipes Network Length od GP Pipes (m) 4, 3, 2, 1, Years Hydraulic Simulation The hydraulic model comprises a database and analysis software. EPANET software has been used for its good track record, its practicality and its simplicity. These elements have been digitalized and comprised: 783 nodes, 942 trunks, 37 Pumps, 2 valves and 15 tanks / reservoirs. Validate the mathematic model over a period of 1.5 months; Measurements: Measurement along the network using equipment: pressure gauges with loggers installed on 32 hydrants and 16 PRV s; level gauges were installed on 5 reservoirs portable ultrasonic flow meter were installed on 11 big connections with portable chlorimeter; Pressure measurements on the network; Reservoir level measurement; Customer flow measurement; Network Flow measurements (through the Scada); Residual chlorine measured at key points in the network; Calibration: Adjustment of model parameters to obtain best possible correlation with the data measurements taken in the field. Actual consumption has been based on customer files, while the field measurement revealed the demand patterns for the city, as well as the consumption pattern for the big customers. The network losses have been calculated per billing zone, and then split per pipe length. The calibration work yielded the following conclusions: Confirmation that PRV s are not operational; coastal areas of network are influenced by Jasan reservoir; Many valves are closed or partially closed, creating high head losses during the peak hours; the location of these valves is not well known, since Masan City has no updated data for valve status; detailed measurement of the pressure will solve this problem; Some areas present a pressure hole, which could also be explained following a detailed pressure study. Utilisation of Model as a Management Tool: Carry out various simulations for planning the strategy for reducing NRW; Optimized network operation: pressure management, new districts and sectors for leakage control, pumping strategy, reservoir storage. Sizing of new pipes: Analysis of the water quality : residual chlorine, Pipe velocity. Strategic Planning of the following scenarios: Response to crisis situations: Chilseo WTP shutdown, transmission line bursts; Development plan: network extensions in some areas (Gusan, Naeseo, Jinjeon, Jinbuk, Dongjeon); Charts 1 is showing examples of pressure calibration

7 Leakage 25 - Conference Proceedings Page 7 P9 / Node Calibration P25 / Node 26 - Calibration m 3 m Measure Model 15 Measure Model 5 :: 2:: 4:: 6:: 8:: 1:: 12:: 14:: 16:: 18:: 2:: 22:: :: :: 2:: 4:: 6:: 8:: 1:: 12:: 14:: 16:: 18:: 2:: 22:: :: Fig 1. P9/P25 Pressure Calibration Chart 2 is showing example of Demand Patterns for Large Consumers (Most large consumers use water for only 4 hours per day on average, creating sudden pressure decrease in network). BC No3 Account No : flow from 1/18/2 14h to1/19/2 14h volum e by m eter = 48 m 3 volum e by flow m eter = 533 m 3 e x isting m e te r m e a n w e ighte d e rror -11% 1 Flow (m3/h) /1 12: 18/1 18: 19/1 : 19/1 6: 19/1 12: 19/1 18: Tim e Fig 2. Demand Pattern Existing Network Pressure The following pressure map of the existing network indicates the following: Networks in the coastal areas have very high pressures up to 7 bar (7m). The networks in the coastal areas comprise mainly old pipes which are laid in an aggressive environment, and are therefore subjected to severe corrosion. The high pressures in these zones can only increase the leakage in these zones. 5% of the network operates with pressures exceeding 4.5 bar (45m). The city is composed of different pressure zones: Kuam area network, served by Kuam reservoir. Northern part of the city, served by Heosung reservoir. Western part located at the highest elevations, served by Jasan reservoir. Eastern and Southern parts of the city, served by Heosung reservoir, although with some influence by Jasan reservoir.

8 Leakage 25 - Conference Proceedings Page 8 Pressure Management Methodology for Pressure Management: The most important task in reducing leaks is to reduce the network pressures. Current peak pressures at night time indicate that 5% of the network has pressures over 5 bars. The highest pressures (between 6 and 8 bars) are found in with the oldest networks. Hence they have the highest incidence of leaks. Pressure increases the fatigue on existing mains. Reducing the pressure will benefit the overall condition of pipes. As the pressure will become more stabilized at lower values following pressure management, the structural integrity of pipes is maintained, and the pipe failures reduce. Creation of reduced pressure zones; The network will be drastically reorganized to generally achieve: maximum night pressure of 3.5 bars (75% of all cases); a minimum daily pressure of 1.5 bars Creation of New Pressure Zones Six (6) Pressure Zones based on the ground elevation (in metres): 25, 2 4, 35 55, 55 75, 75 9, 5 7 (Kuam); Six (6) Pressure zones derived from the following source storage reservoirs: Hoesung reservoir with PRV, Hoesung reservoir with PRV, Hoesung reservoir, Jasan reservoir with PRV, Jasan reservoir, Kuam reservoir Creation of New Districts within the New Pressure Zones: The network will be divided into 1 new Districts. The size of Districts sizes has been calculated and simulated by the hydraulic model. Each District will be equipped with a pressure gauge that regulates the PRVs. For security, each District will be supplied through at least two (2) active inlet points + one (1) as stand-by. Each District will contain around 4, connections on average and around 1 km of network (35 km of distribution pipes and 65 km of tertiary network). Expected Improvements following the Pressure Management Plan. 1% Pressure Frequency in Masan City (Billing Zones 1 to 26) 9% 8% 4.1 bar 6.6 bar % of points less than 7% 6% 5% 4% 3% 3. bar 5.1 bar Pressure Management Current Situation 2% 1% % Pressure (Bar)

9 Leakage 25 - Conference Proceedings Page 9 The following improvements to the network pressures are expected: 5 % of the nodes have a pressure less than 3 bars (for 5.1 bars today), 8 % of the nodes have a pressure less than 4.1 bars (for 6.6 bars today), Pressures are greater than 4 bars in the transmission line (under Heosung Reservoir) Other Projects In Korea, KOWACO serves as the multiregional water service provider and 167 local governments function as individual local water service providers. Facility expansion has increased the water supply penetration rate to 9%. However, local waterworks suffer from annual leakage losses of up to 8 million because local water service providers lack the scale of economy due to their small-scale waterworks, resulting in accumulative fiscal deficits and backward technologies, showing low operational efficiency. KOWACO efficiently operates local waterworks to supply clean tap water by resolving the problems of local water services with expertise and technologies accumulated through extensive management experience with multi-regional waterworks and piping to supply and drain new cities. KOWACO links local waterworks with multiregional waterworks run by the corporation, reduces costs by integrating intraregional water service facilities, increases flow capacity by modernizing facilities and manages inspection for 254 water quality items. KOWACO succeeded in consolidating the business of operations and management of local waterworks in Nonsan in 24, providing the benefit of a reduction in the tariff by KRW 67 per and increasing flow capacity. Signing basic agreements with 17 local governments including the Jonju Municipal Government, KOWACO is always prepared to engage in business diagnosis or actual operations. KOWACO vigorously seeks out this type of business to provide evenly balanced water services for the entire nation and to defend the Korean water market against foreign multinational companies. To achieve this goal, KOWACO has redesigned its organizational system by adding five new regional water service headquaters to the two existing ones. KOWACO makes every effort to exert more control over the water market by becoming a leading player in the local water service market on the basis of its advanced technologies and operational know-how. References Alan C. Twort et al. (2) Water Supply. AWWA (25) Water Quality in the Distribution System. Ministry of Environment (24) Water Supply Statistics Book. Julian Thornton (22) Water Loss Control Manual. Paul F. Boulos, et al. (24) Comprehensive Water Distribution Systems Analysis Handbook for Engineers and Planners. Haestad Method (23) Advanced Water Distribution Modeling And Management.