Prevention of Water Leakage in Tokyo

Transcription

1 Prevention of Water Leakage in Tokyo 2014 Bureau of Waterworks, Tokyo Metropolitan Government

2

3 Prevention of Water Leakage in Tokyo 2014 Bureau of Waterworks, Tokyo Metropolitan Government

4 Contents Page 1 Outline of leakage prevention Present situation Necessity of leakage prevention 2 2 Countermeasure of leakage prevention System of leakage prevention measures Planned replacement of water pipes and improvement of materials for pipes 5 (1) Distribution pipe replacement (aged pipes, 5 early ductile iron pipes, etc.) (2) Integration of service pipes under the 5 private road and replacement with sub mains (3) Reinforcement of seismic resistance of 6 large-diameter service pipes (4) Reinforcement of seismic resistance of service 6 pipes in shelters and other facilities (5) Material improvement work of service pipes Early detection and repair work for water leakage. 8 (1) Planned work 8 a Patrol work(circulating checking) 8 b Leakage volume measurement work. 8 c Leakage investigation and measurement work 9 (2) Mobile work Secure high level of leak prevention technologies 10 (1) Training and Technical Development Center 10 (2) Accreditation of Tokyo waterworks technology 10 experts and super plumbers 2.2 Leakage prevention construction system.11 3 The method of leakage investigation Minimum night flow measurement method 11

5 3.2 Acoustic method Correlation method Time integral type leakage detector Transmission-type leakage detector Other methods.16 4 Problems and the future of leakage prevention 17 5 Annex 19 Table-1 Distribution volume analysis in FY Table-2 Trends in total distribution volume, 21 leakage volume and rate from FY1994 to FY2013 Table-3 Trends in number of each kind of repair works 22 from FY1994 to FY2013. Table-4 Specifications of leakage cases in FY Table-5 Organization of water leakage prevention 24 Table-6 Technology and equipment related to water leakage 25 prevention that were co-developed by the Tokyo Metropolitan Government and private companies.. Table-7 Trends in percentages of ductile cast iron pipes.26 in distribution pipes, stainless steel pipes in service pipes, leakage repair cases, leakage rate from FY1994 to FY2013

6 1 Outline of leakage prevention 1.1 Present situation The rivers flowing in this area, namely Tone, Ara, Tama river systems are the main source of water used in the Tokyo Metropolitan area. We collect raw water from these rivers, process purification at water plants such as sedimentation, filtration and disinfection, convey into underground water pipes with pressure, then supply as tap water to customers. In the process of supplying tap water, some water leaks from the pipes into the ground. leakage of water. This is the Leakage vol. 33million m 3 2.2% Distribution vol. 1,523 million m 3 Fig.1 Annual distribution volume and leakage volume in FY2013 In FY1994 two decades ago the annual water leakage was 175 million m 3 and the leakage rate 9.9%. Water leakage decreased to 33 million m 3 in FY2013. And leakage rate accounted for 2.2% against the annual distribution amount of billion m 3 (Fig.1, Table-1 and 2). Most water leakages occur due to cracks and corrosion caused by aged deterioration of service pipes that are owned by our customers and distribution pipes. The total cases of leakage repair work in FY 2013 recorded around 10,100, and around 97% of which were at service pipes, and the remaining around 3% were at distribution pipes (Table-3 and 4). Mobile work 9,597 cases 95.0% Planned work 503 cases 5.0% Planned work 3,512 m 3 /D 69.8% Mobile work 1,519 m 3 /D 30.2% Fig.2-1 Comparison between Mobile work and Planned work (Cases) Fig.2-2 Breakdown of leakage repair works ( Prevention Volume ) Leakage volume (m3/day) Prevention volume Prevention volume Repetition volume Remained leakage Remained leakage volume volume The second last time The last time Now Recurring years Fig.3 Repetition of leakage - 1 -

7 Leakage is classified into two types by its form; surface leakage flows out on the ground and underground leakage leaks out underground without appearing on the surface. Basically, water leakages occurring above the ground are dealt with by mobile work and those occurring underground by planned work. The Figure 2-1 shows the ratio of mobile work to planned one. There were 9,597 repairs by mobile work and 503 by planned one in the fiscal year Water leakages above the ground are, in principle, repaired within the same day that they are detected. On the other hand, underground water leakage is invisible and thus practically unnoticeable; therefore, in many cases water has been leaking for a long period of time. The breakdown of underground leakage repair works shows that 70% of underground water leakage amount is detected and repaired through planned works. Therefore, unless we identify and repair leakages systematically, valuable water will continue to leak and large accidents may occur. Water pipes are always at risk of developing leakage because, in addition to their aged deterioration, they have been affected by earthquakes, uneven settling of the ground, corrosive soil, traffic loads and various construction works. Although water leakages are repaired as soon as they are found, On the other hand, the new leakage increases gradually in accordance with time. This is referred to as the repetition phenomenon of leakage (Fig. 3). As understanding this repetition phenomenon leads to development of leakage prevention measures, we try to collect as many data as possible. 1.2 Necessity of leakage prevention Tokyo currently possesses water resources that supply a volume of 6.3 million m 3 per day. Some of the resources have problems: e.g. Sagami River from which water is diverted to Tokyo through yearly agreements with Kanagawa Prefecture and Kawasaki City, which may affect the water situation in Kanagawa Prefecture in terms of stability of water intake. Furthermore, in the Tone River system which is Tokyo s main water resource, the degree of safety against drought is low currently, as the amount of water which can be stably supplied from dams and other facilities has been decreased compared to the initial plan due to the rainfall conditions in recent years. In consideration of these circumstances, Tokyo, as the capital of Japan, is required to promote efficient use of water and measures for leakage prevention as ever, while making efforts to secure stable water resources, with an eye to achieving a greater security against drought so that we can ensure stable water supply even at the time of severe drought. On the other hand, water distribution pipes installed within Tokyo totals up to about 27,000 kilometers long as of FY2013, which is equivalent to half the length of the earth s circumference. Water pipes embedded under ground are constantly subject to a danger of leakage, and when leakage occurs, these pipes pose risks of factors like secondary disasters including poor water flow, sagging road, inundation and so on. We, Tokyo Waterworks, have actively taken measures against water leakage as part of our major policies because they enable us to prevent secondary disasters as well as water leakages which are equivalent to the amount of water to be obtained by developing a new water resource

8 Fig.4-1 Scene of water leakage Fig.4-2 corrosion and water leakage of iron pipes - 3 -

9 2 Countermeasure of leakage prevention 2.1 System of leakage prevention measures The leakage control measures that we take in Tokyo are classified as follows. Countermeasure of leakage prevention Planned replacement of water pipes and improvement of materials for pipes Distribution pipe replacement (aged pipes, early ductile iron pipes, etc.) Integration of service pipes under the private road and replacement with sub mains Reinforcement of seismic resistance of large-diameter service pipes Reinforcement of seismic resistance of service pipes in shelters and other facilities Material improvement work of service pipes Early detection and repair work for water leakage Planned work Patrol work Mobile work Leakage volume measurement work Leak investigation and measurement work Secure high technology of water leak prevention Training and Technical Development Center Accreditation of Tokyo waterworks technology experts and super plumbers Fig.5 System of leakage prevention measures - 4 -

10 2.1.1 Planned replacement of water pipes and improvement of materials for pipes Planned replacement and improvement of the quality of pipe materials are important and effective methods to reduce remaining leakage as well as to forestall leakage and prevent so called Reversion Phenomena of water leakage. Followings are the major solutions. (1) Distribution pipe replacement (aged pipes, early ductile iron pipes, etc.) We have been replacing the following distribution pipes: low-strength cast iron pipes without inner lining; aged steel pipes installed many years ago; early ductile iron pipes consisting of a mixture of straight pipes made of ductile cast iron and special fittings made of high-grade cast iron with no inner lining; externally-uncoated pipes installed in areas with highly-corrosive and soft ground such as the eastern part of 23 wards; and pipes without earthquake-resistant joints installed in areas where severe damage is anticipated at the time of disaster. In this regard, we have installed pipes with earthquake-resistant joints in consideration of earthquake disaster countermeasures. In particular, the priority in such replacement works is placed on water supply routes to disaster base hospitals, the Capital s central agencies, shelters and main stations. (Note) Ductile cast iron pipe has increased material strength by the addition of magnesium to the traditional cast iron pipe and making graphite in the structure spherical. Cast iron Fig.6 Ductile cast iron Micrograph of cast iron (2) Integration of service pipes under the private road and replacement with sub mains Beneath private roads are congested with many service pipes, causing water leakage due to aging and corrosions. In this regard, we have been making efforts to prevent water leakages and improve earthquake resistance of service pipes under private roads through the consolidation of the system of those pipes by installing submain pipes and replacing the existing pipes with stainless-steel ones. In the project that started in FY1994, at the beginning, we conducted replacement work on private roads where more than three service pipes were installed. Since FY 2007, the scope work has been expanded to private roads which have more than 15 meters, and from FY 2009 further expanded to the ones which have more than 10 meters. We have also replaced pipes under private roads with three or more water meters since September Also, we are trying to further improve earthquake resistance of service pipes under private roads with two or less water meters installed by replacing PVC pipes with stainless steel pipes. -5-

11 < Before the execution > After the execution Housing land 2 3 Housing land 2 3 Public road Public road Sub main Private road Private road 1 1 Sub main Service pipes Sub main Service pipes meter drain Valve (for service pipe) Valve (for sub main) Fig.7 Integration of service pipes under the private road and replacement with sub mains (3) Reinforcement of seismic resistance of large-diameter service pipes To react on aged deterioration on large-diameter service pipes that has more than 75mm bore diameter we have been working on earthquake resistant reinforcement since FY1998 in addition to planned (routine) replacement of distribution pipes and leak repair works of service pipes. Since FY2007, we have expanded the scope of pipes for the systematic enhancement of earthquake resistance to large-diameter service pipes, from branching part of service pipes to (in principle) the first stop cock, which remain unreinforced against earthquake on the routes where replacement of distribution pipes had completed before FY1998. (4) Reinforcement of seismic resistance of service pipes in shelters and other facilities As shelters become temporary living places for many people at the time of earthquake disaster, it is necessary to ensure a stable supply of water. Therefore, in order to secure water supply to the shelters, we have been working on earthquake resistance enhancement on service pipes of facilities designated as shelters, and not only the part between the branching part of service pipes to the first stop cock but also meters are subject for the enhancement work. (5) Material improvement work of service pipes Among the total water leakage repairs (please see the Reference 4 on page 28), about 97% were service pipes owned by our customers. Consequently, in order to reduce water leakages, it is extremely effective to prevent them that occur to service pipes. In Tokyo, we used to use lead for service pipes, which has been a major cause of water leakages due to its low intensity and corrosion-prone characteristics. Therefore, since FY 1980 we have abandoned the use of lead pipes for service pipes to be newly installed under public roads, and adopted stainless steel pipes that have superior strength and corrosion resistance. And then, since FY 1982, as a project of Tokyo Waterworks aiming for water leakage reduction, we have replaced branched lead pipes with stainless ones under the requirement of replacing aged distribution pipes and frequently leaking distribution pipes with ductile pipes - 6 -

12 (from the bifurcation area of pipes to the point one meter inside from the edge of the residential land). Moreover, since FY 1983, we have replaced service pipes branching off from the pipelines, which have already been ductile ones, with stainless pipes because they cause leakages so often, and then, since 1984, service pipes with stainless ones at every opportunity of construction work related to submain pipes. Furthermore, since FY 1985, we have replaced heavily corroded lead pipes with stainless steel ones at the occasions of repairing service pipe leakages. In 1992, the stricter water quality standards for lead were introduced (water quality standard values: 0.05mg/l), together with the long-term target for 2002 (water quality standard values: 0.01mg/l). In this regard, in addition to more actively promoting the use of stainless steel pipes through the installation of long-distance service pipes, we have expanded the scope of material improvement work, and replace to within residential areas water meters since FY Also, since FY 1995 we have entirely banned the use of lead pipes, and since 1998 adopted corrugated stainless steel ones that have excellent workability and earthquake resistance. In 2000, a new plan was formulated to replace lead pipes laid from public and private roads to water meters installed within residential areas, and since then we have carried out the replacement works in turn in accordance with the plan. As a result, we were able to replace lead pipes under public roads almost as planned by FY 2002 and most lead pipes under private roads leading to water meters within housing areas by FY In addition, there are a few lead pipes remaining under private roads and within residential areas. We have checked the remaining lead pipes again at the occasion of Patrol work after 2007 and been trying to replace them. Fig.8 Leakage on lead pipes Public road Private road Residential area Meter Distribution pipe Service pipe The portion exchanges in the Waterworks The portion which a user exchanges User's property Fig.9 Material improvement of service pipe - 7 -

13 2.1.2 Early detection and repair work for water leakage Early detection and repair work on water leakage means the initiative that we detect water leaks and provide repair works on early stage for the underground and ground with planned and mobile works. Distribution pipes are maintained and managed as water facilities by Tokyo Metropolitan Government. On the other hand service pipes are supposed to be maintained and managed by customers. And, in order to make good use of limited water resources, Tokyo Waterworks repairs water leakages in service pipes installed up to water meters within residential areas without charge except in special circumstances. (1) Planned work Planned works refer to the planned research works by block compartmented submain pipe networks at a certain extent (please refer fig 10 on page 12) within municipal Tokyo. One of them is patrol (routine) work that detects water leakage and provides repair works; another is leakage volume measurement work that is intended to understand leakage trend; the other is leakage investigation and measurement work that aims to check up sluice-gate functions against earthquake and investigate water leakage. In 23 wards, we have been working on leakage preventions since FY1913. Leakage survey is conducted by 6 branch offices (14 offices) and the majority of repair works are undertaken by contractors. Also, in the 26 cities/towns of Tama area in which we operate our services, leakage survey is conducted by an administrative organization of Tokyo Waterworks (Tokyo Suido Services Co., Ltd.), and repair works are undertaken by contractors. a Patrol work (Circulating checking) In the patrol works are individual investigation work that determines leakage with acoustic rod (please refer the page 17) attached to meter on every home, acoustic investigation work that is conducted during the night when there is less traffic to identify point of leakage with electric leakage detector from the road surface etc. To determine the blocks to patrol, we take previous work history, leakage occurrence in the previous year, and residual number of lead service pipes into consideration. In addition to that, we consign administrative bodies (Tokyo Suido Services Co., Ltd.) to conduct such individual investigation with time integral type leak detector (please refer the page 19) replacing acoustic rod on some blocks since FY2003. b Leakage volume measurement work To estimate total leakage volume within Tokyo municipal and understand the leakage trend, we conduct leakage volume measurement works. In order to identify the more accurate amount of water leakage in the urban area that is active 24 hours a day, we measure the minimum flow (leakage amount) at night by narrowing down the number of target taps to that is the threshold below which people stop using water during a certain period of night. By estimating leakage volume within a certain block, we are able to make total assumption of leakage volume within municipal Tokyo. Together with leakage investigation and measurement work that has been put into practice since FY2010, we will put such works to improve our leakage prevention plan. For the leakage volume measurement work, we consign administrative bodies (Tokyo Suido Services Co., Ltd.) since FY2005 for some blocks

14 c Leakage investigation and measurement work To minimize water outage during the earthquake disaster and fast react on to recover the facilities, it is important to ensure the water flow from main pipes to submain pipes. To that end, it is essential to ensure the function of exhaust valves of main pipes. On that basis, it is necessary to avoid using quake-damaged pipelines to secure operable water-supply routes as early as possible and then to expand areas to which water can be supplied. This leakage investigation and measurement work is a practical series of works that conduct functional measurement of water valves required to secure water route after securing the safety of exhaust valve on distribution main, assuming the channel where leakage volume are high as damaged points, then recover/expand the service area sequentially. We conduct investigation on the whole water flow area based on the volume of leakage, and then operate repair works on leakage points one by one when found. Such data will also be partially facilitated to leakage volume measurement work. exhaust valve of distribution main distribution main Block water meter passing water route plan 1 Distribution pipe Distribution pipe for shutdown water flow passing water route plan 2 estimated point of damage Unable to flow water on route 1 and 2 due to damages. Ensuring that 通 水 there is no damage on route 3, flow water to passing water area 2. passing water route plan 3 passing water area 1 passing water area 2 Fig.10 Leakage volume investigation and measurement work (2) Mobile work A work for repairing an aboveground leakage found by report of a customer, by patrol of staff or by other means is called mobile work. In 23 wards, staff members and contractors are on call 24 hours a day at 6 branch offices (14 offices). In addition, the administrative organization of Tokyo Waterworks (Tokyo Suido Services Co., Ltd.) and our contractors in the 26 cities/towns of Tama area, in which we operate our services, are ready 24 hours a day

15 2.1.3 Secure high level of leak prevention technologies With background that we need to maintain low rate of water leakage and mass retirement of veteran workers, our important efforts include trainings for transferring techniques, engineering development, and human resource development, for the purpose of efficient and secure measures for water leakage prevention. (1) Training and Technical Development Center At the Training and Technical Development Center established in 2005, Training division and development division work together to ensure the succession of technologies, enhance the capabilities of the staff members and to respond appropriately to diverse needs so that we can continue to provide a steady supply of safe and better-tasting water to customers into the future. Its pipeline experiment facility has facilities for experiments and verification in order to resolve problems mainly concerning pipelines, which are equipped with the environment that is similar to the actual one. These facilities are utilized for trainings for staff of neighboring and overseas waterworks companies as well as those of the Tokyo Metropolitan Government (TMG). In addition, for the list of items of leakage-prevention related equipment that were co-developed by the TMG and private companies, please see Reference 6. Fig.11 Technical training for leakage prevention work (2) Accreditation of Tokyo waterworks technology experts and super plumbers In various fields not limited to leakage prevention, many veteran staff with technology backed up with experience approach to the time of retirement, which is a big issue in terms of succession of technology. Therefore we founded Tokyo Water Workers Technology Experts Program, in which veteran workers provide training junior fellows as leaders, and offer instruction courses on leakage prevention technologies at Training and Technical Development Center. Furthermore we enhance inheritance of leak prevention technologies by visualizing implicit knowledge that has been cultivated/built and uploaded to shared network, enabling browse as-needed basis. In addition, especially excellent plumbers are accredited as super plumbers among the contractors of distribution pipe construction in order to maintain and succession technology, as well as to enhance the level of the entire plumbing technology and motivation

16 2.2 Leakage prevention construction system Bureau of Waterworks Metropolitan Tokyo Government adopt computerized system for tally records of repair work on leakage (cause and detail of actual repair work) and calculate paid amount for such works. Current systems process the followings. 1) Reception of leakage prevention measures. 2) Calculation of construction cost for water leakage repair, material improvements, etc. 3) Summarization of the records of leakage causes and contents of the work done. The data obtained through electronic processing are effectively used for budget-making of the next fiscal year and drawing out long-term plans, selection of planned work blocks, and calculation of leakage volume, etc., contributing largely to the execution of effective preventive measures against leakage. 3 The method of leakage investigation Currently we have mainly two types leakage investigations; based on maintenance status of pipelines and past history of water leakage, select pipelines necessary to be investigated and conduct leakage investigation (minimum night flow measurement method). Another method is to determine the leakage by the sound and identify the location (acoustic method, correlation method, and method using the time integral type leakage detector). 3.1 Minimum night flow measurement method Minimum night flow measurement is a leak investigation method that has been developed by taking the note of midnight idle time (unoccupied hours) of water usage in a certain block. First, gate valves surrounding the block to be investigated are closed and the water from other blocks is shut down. Then the water is sent into the block through minimum flow measuring equipment set in the block water meter and the flow rate is measured. The minimum flow rate measured (The quantity of flow indicated in spite of a situation where nobody is expected to use water) during the vacant period is considered to be the water leakage. For measurement we use high prevision minimum flow meter joint-developed by the Bureau and a private company. Minimum flow meter Flow Flow Block water meter Minimum flow = leakage Recording chart Time Block water meter A C House C Distribution pipe B House B House A Unoccupied hour Outline of section Length of distribution pipe: approx. 3.0km Time Principle of the unoccupied hour theory Fig.12 Theory of minimum night flow measurement method

17 Fig.13 Minimum flow meter 3.2 Acoustic method In the acoustic method, the leak sound is detected by an acoustic rod or an electronic leak detector. The metal tip of the acoustic rod is pressed against the water meter, gate valve or fire hydrant. An inspector then presses an ear against a vibration diaphragm set at the other end of the rod, and listens for transmitted sound of the leakage. The acoustic rod can only tell whether the leakage is present in the neighborhood, and it is difficult to detect the position of leakage. Using an electronic leakage detector, a detector (pickup) to convert the leak sound into an electrical signal is placed on the ground, and the sound transmitted through the ground is amplified and heard through headphones. As the detector (pickup) is moved in order, the leak sound is heard most strongly directly above the point of leakage and thus the position of leakage can be detected. Fig.14 Acoustic rod

18 Detector (Pickup) Fig.15 Electronic leakage detector Acoustic rod Electronic leakage detector Fig.16 Acoustic method 3.3 Correlation method In the correlation method, the position of leakage is detected by using a correlation type leakage detector (a combination of correlation analyzer, sensor, amplifier, wireless transmitter, etc.). Firstly we place sensors at two points (where exposed ground surface i.e. gate valve and fire hydrant), then obtain the leakage noise propagation time difference to both sensors with correlation leakage detector. The position of leakage is calculated by the time lag, distance between sensors, and velocity of leaking sound transmitting through the pipe. Correlation method has a benefit that enables investigation regardless of noise of cities and depth of pipes buried,

19 because it directly detects the noise of leakage from the pipelines. The correlation type leakage detector was jointly developed by the Tokyo Metropolitan Government and private industry. Amplifier with radio transmitter Correlation leakage detector Sensor Valve C C A Standard point Leak point B Comparison point La Lb L La = ( L - Tm C ) / 2 Tm C L Leakage noise propagation time difference Noise velocity on the pipe Distance between A and B Fig.17 Theory of the correlation method A B Fig.18 Correlation type leakage detector

20 3.4 Time integral type leakage detector Time integral type leakage detector is the device that identifies the leakage by utilizing the nature that the leakage noise has the continuity. This device measures the noise to be transmitted for a certain period of time (1 second up to 5 seconds) by attaching the sensor to the exposure points of service pipes within individual meter box. It has excellent characteristics such as being largely unaffected by intermittent usage sound of the waterworks or traffic noise transmitted through the ground, and not requiring skill to operate. The time integral type leakage detector was jointly developed by the Tokyo Metropolitan Government and private industry. Automatic leakage detector Meter Leak point Service pipe Sub main Fig.19 Time integral type leakage detector 3.5 Transmission-type leakage detector The transmission-type leakage detector is the equipment used to detect leakage in a pipe. Chemically inert helium gas mixed with water or air is injected into the pipe and the detector is used to detect the helium gas leaked from the pipe and seeped through the ground. This type of method allows to detect very small amount of leakage or leakage in Main pipes such as main distribution pipes buried deep underground since it is not based on the leak sound as it is necessary with the acoustic leakage sound detection method or the correlative leak detection method. The equipment used for the transmission-type leakage detector method was co-developed by the Tokyo Metropolitan Government and private organizations

21 Transmission-type leakage detector He He He Distribution pipe Leak point Fig.20 Transmission-type leakage detector 3.6 Other methods Leakage investigation requires not only the technologies to identify the leakage but also those to detect the position of laid pipes or to test water quality to determine whether leaking water is tap water. Metal pipe detector and Water hammer Generator are used to detect the pipe location. To identify whether such water is tap water, we facilitate easy method such as water temperature gauge, residual chlorine analyzer, ph meter, and conductivity detector, or precise method determining inclusion of trihalomethane

22 Fig.21 Metal pipe locator Fig.22 Water hammer Generator 4 Problems and the future of leakage prevention Water resources are becoming increasingly precious as there is concern over streamflow reduction and increased risk of drought due to considerable snowfall reduction, early start of snowmelt season and increase in the number of dry days resulting from climate change and global warming. Planned dam construction in the Tone River system, which is Tokyo s major water source, is as yet incomplete, which along with rainfall levels in recent years, has led to lower Actual water supply capacity of dams than originally planned and has also contributed to the low level of safety with respect to drought. Still further, the tap water is based on raw water as described above; it is also a resource produced by spending ca. 1% of the electric power consumed within the Tokyo metropolitan area during steps including water treatment and water supply. Leakage prevention measures aim at an effective use of water, and contribute to prevention of global warming from a viewpoint of energy saving and reduction of carbon-dioxide emissions. Additionally they are of paramount importance

23 in that they are a key to avoidance of secondary disasters like sagging road resulting from leakage. As for these measures against water leakage, 13 cities (including Tokyo, the host city, Seoul, Los Angels and New York) agreed to make efforts to promote such measures and provide technical information at the C40 Tokyo Conference on Climate Change held in October So, the importance of those measures has now been recognized in the world. Amid growing expectations for Japan s technologies in order to tackle the global water problems, Tokyo Metropolitan Government (TMG) has made a commitment to international cooperation under the Tokyo Waterworks Management Plan 2013 as adopted in February 2013, by means of utilizing high-quality water engineering and operational know-how, in addition to our preceding efforts such as acceptance of oversea trainees and oversea dispatch of our staff. The rate of water leakage in Tokyo is 2.2% as of FY 2013, which indicates the outcome of the efforts that have been taken by the Bureau for water leakage prevention as a major policy issue. This rate in Tokyo stands at an exceptionally high level, even in comparison with those in other cities of the same scale. In this respect, TMG s efforts received acclaim at the 2012 International Water Association (IWA) Project Innovation Awards (PIA) in that our leakage prevention measures were significantly conducive to enhance operational efficiency in energy saving as well as efficient use of valuable water resources. Consequently, we received East Asia Awards (July 2012) and Global Honour Awards (September 2012). We will continue to actively promote its technologies and know-how both at home and abroad, and pass them on to the next generation. We will also keep the current low-leakage rate by utilizing all of our accumulated technologies

24 5 Annex

25 Table-1 Distribution volume analysis in FY2013 Unaccount for 15million m 3 (1.0%) Leakage 33million m 3 (2.2%) Deduced consumption by settlement 2million m 3 (0.1%) Account for 1,473million m 3 (96.7%) Water Volume (m 3 /year) Component Rate (%) Distribution total 1,523,491, Effective 1,488,111, Account for 1,472,779, Charged 1,469,114, Supplied to Tama 3,628, Others 36, Unaccount for 15,332, Unmeasured 12,938, Waterworks use 1,207, Others 1,186, Ineffective 35,379, Leakage 33,186, Deduced consumption by settlement 2,192,

26 Table-2 Trends in total distribution, leakage volume and rate from FY1993 to FY2013 (10 6 m 3 ) (%) 2, ,800 1,600 1,400 1,200 1, H7 ('95) H9 ('97) H11 ('99) H13 ('01) H15 ('03) H17 ('05) H19 ('07) H21 ('09) H23 ('11) H25 ('13) Distribution vol. Leakage vol. Leakage rate Distribution vol. Leakage vol. Leakage rate Distribution vol. Leakage vol. Leakage rate H6('94) H7('95) H8('96) H9('97) H10('98) H11('99) H12('00) H13('01) H14('02) H15('03) 10 6 m 3 1,746 1,727 1,697 1,689 1,672 1,671 1,678 1,656 1,639 1, m % H16('04) H17('05) H18('06) H19('07) H20('08) H21('09) H22('10) H23('11) H24('12) H25('13) 10 6 m 3 1,625 1,616 1,606 1,607 1,582 1,568 1,569 1,537 1,523 1, m %

27 Table-3 Trends in number of each kind of repair works from FY1994 to FY ,000 (Cases) 50,000 40,000 30,000 20,000 10,000 0 H7 ('95) H9 ('97) H11 ('99) H13 ('01) H15 ('03) H17 ('05) H19 ('07) H21 ('09) H23 ('11) H25 ('13) Planned work Mobile work Total Planned work Mobile work Total Planned work Mobile work Total H6('94) H7('95) H8('96) H9('97) H10('98) H11('99) H12('00) H13('01) H14('02) H15('03) cases 10,505 10,979 9,177 8,028 6,964 6,627 5,073 4,199 3,450 3,516 cases 37,542 35,965 33,757 31,345 30,575 28,476 27,569 23,135 18,996 24,186 cases 48,047 46,944 42,934 39,373 37,539 35,103 32,642 27,334 22,446 27,702 H16('04) H17('05) H18('06) H19('07) H20('08) H21('09) H22('10) H23('11) H24('12) H25('13) cases 2,592 1,908 1,287 1,097 1, cases 22,987 19,361 16,460 15,173 14,083 13,046 13,777 12,090 10,476 9,597 cases 25,579 21,269 17,747 16,270 15,109 13,894 14,578 12,774 11,018 10,

28 Table-4 Specifications of leakage cases in FY By Uses Mains 21Cases 0.2% Submains 305Cases 3.0% Service pipes 9,774Cases 96.8% 2 By Causes ( Mains ) Joint 8Cases 38.1% Corrosion 3Cases 14.3% Packing of valves 10Cases 47.6% Water pipes consisting of the mains with a bore diameter of 400 mm or larger that were installed to distribute water from service and booster-pump stations to water supply areas. ( Submains ) Others 80Cases 26.2% packing of valves 83Cases 27.2% Water pipes with a bore diameter of 350 mm or less that branch off from distribution mains and directly connect to Hydrants 40Cases 13.1% Joint 29Cases 9.5% Corrosion 53Cases 17.4% Crack 20Cases 6.6% service pipes (50, 75, 100, 150, 200, 250, 300 and 350 mm). ( Service Pipes ) Packing of meters 1,798Cases 18.4% Packing of valves etc 2,051Cases 21.0% Others 809Cases 8.3% Corrosion 1,787Cases 18.3% Joint 2,146Cases 21.9% Crack 1,183Cases 12.1% Water pipes that branch off from small distribution pipes and connect to household taps

29 Table-5 Organization of water leakage Director Water Supply Div. Water Supply Sect. Management Subsect. Leakage Prevention Subsect. Research Subsect. Emergency Water Service Squad Branches(6) Water Supply Sect.(7) Management Subsect.(7) Leakage Prevention Subsect.(7) Leak Prevention Suboffice.(7) Construction Coordinantion Charge.(7) Tama Water Works Center Training and Technical Development Center Number of persons working in the Waterworks is 3,920(at April 2014). 308 persons of them are engaged in leakage prevention of the 23 wards

30 Table-6 Technology and equipment related to water leakage prevention that were co-developed by the Tokyo Metropolitan Government and private companies. Freezing method This method suspends water by freezing up the water inside the pipe with liquid air in repairs. Electronic leakage detector This instrument can pick up the leakage noise electrically on ground surface. Portable minimum flow meter This flow meter is used at the minimum night flow measurement. Correlation type leakage detector This instrument locates the leakage by processing leakage noise picked up at two point on pipe. Underground radar This radar radiates electro-magnetic wave to ground so as to search the underground condition. Time integral type leakage detector Making use of the continuity of leakage noise, this instrument is able to check whether the leakage exists or not. Transmission-type leakage detector It is a device to locate the place of water leakage by detecting the helium gas injected into the water pipe and then discharged through the leakage spot to the soil

31 Table-7 Trends in percentages of ductile cast iron pipes in distribution pipes, stainless steel pipes in service pipes,leakage repair cases,leakage rate from FY1994 to FY ~1 0 ) i s c a se p a ir re e a k a g e L s le in sta g e e n ta e rc EP e s p ip n iro c a st u c tile d o f g e e n ta e rc P ) e s(% p ip H7 ('95) H9 ('97) H11 ('99) H13 ('01) H15 ('03) H17 ('05) H19 ('07) H21 ('09) ) % H23 ('11) H25 ('13) ) (% te ra e a k a g e L Percentage of ductile cast iron pipes Percentage of stainless steel pipes Leakage repair cases Leakage rate Percentage of ductile cast iron pipes H6 ('94) H7 ('95) H8 ('96) H9 ('97) H10 ('98) H11 ('99) H12 ('00) H13 ('01) H14 ('02) H15 ('03) % H16 ('04) H17 ('05) H18 ('06) H19 ('07) H20 ('08) H21 ('09) H22 ('10) H23 ('11) H24 ('12) H25 ('13) Percentage of stainless steel pipes % Leakage repair cases 48,047 46,944 42,934 39,373 37,539 35,103 32,642 27,334 22,446 27,702 25,579 21,269 17,747 16,270 15,109 13,894 14,578 12,774 11,018 10,100 Leakage rate %

32