LCQ12: Water mains burstFollowing is a question by the Hon Tony Tse and a written reply by the Secretary for Development, Mr Paul Chan, in the Legislative Council today (January 23):
In recent years, a number of water mains burst incidents occurred in Hong Kong, causing serious disruption to road traffic and inconvenience to the public. The Water Supplies Department (WSD) has indicated that it is tackling the problem with a multi-pronged approach, including proactive burst prevention by leakage detection, replacement and rehabilitation of aged water mains under the Water Mains Replacement and Rehabilitation (R&R) Programme and implementation of water pressure management. In this connection, will the Government inform this Council:
(a) of the respective numbers of reports of water mains bursts involving fresh and flush water pipes in various districts received by WSD in each of the years from 2010 to 2012; of the average and longest time taken by WSD to isolate the burst mains after receiving the reports; of the number of water mains which had already been included in the R&R Programme when they burst, pending replacement or rehabilitation;
(b) of the respective numbers of water mains the replacement and rehabilitation works of which have been completed, are still in progress and are pending since the introduction of the R&R Programme in 2000;
(c) of the key districts in which the water mains will be replaced and rehabilitated under the R&R Programme from now on until 2015, as well as the total length of such water mains;
(d) of the locations of the pipe sections at which WSD has installed GSM noise loggers with wireless data transmission capability for the purpose of stepping up leakage detection on water mains, as well as the findings in summarising and analysing the collected data; whether it has assessed if the measure can achieve the intended results; if it has, of the outcome;
(e) of the specific measures implemented by the authorities to address the problem of water mains bursts and leaks by means of water pressure management, as well as the progress and effectiveness of the implementation of such measures; and
(f) whether the Government will introduce new measures to prevent and deal with water mains bursts and leaks; if it will, of the specific content of the measures, as well as the manpower and costs involved?
The water supply system of Hong Kong is massive and complex. The hilly terrain of Hong Kong makes the water supply pressure relatively high. The high water pressure together with ground movements and external disturbances makes our aged water distribution network prone to bursts. We fully understand that water main bursts would cause inconvenience to the public and affect the traffic. To tackle the problem proactively, the WSD is taking a multi-pronged approach, including identification of burst-prone water mains by leakage detection, implementation of the R&R Programme and implementation of pressure management. These works have reaped positive results, with the number of water mains burst incidents dropping from a peak of about 2 500 in 2000-01 to about 260 in 2012. The WSD has completed about two-thirds of the R&R programme since its launch in 2000 and anticipates to complete the whole R&R programme in 2015. The WSD is planning the way forward for the next phase of the R&R programme after 2015.
My reply to the six parts of the question is as follows:
(a) The WSD received 670, 370 and 259 reports of water mains bursts involving both fresh and salt water pipes in various districts respectively in 2010, 2011 and 2012. Detailed breakdown of the incidents by district is shown in Annex I. The average and longest time taken to isolate the burst mains after receiving the reports were about 1.7 (Note: The average time taken to isolate the burst mains after receiving the reports were 1.6, 2.2 and 1.4 hours respectively in 2010, 2011 and 2012.) and 5.6 hours respectively. The incident in which the longest time was taken to close off the valves occurred at Happy Valley on March 1, 2011. It involved a very complex water supply network and required closing off 22 valves, including the valves of many branch pipes connected to the burst mains, before repair works could commence. The performance pledge of the WSD on the time required after receipt of a main burst report for valve closure to enable repair works to start as well as the average results achieved are set out in Annex II.
With regard to the main burst incidents from 2010 to 2012, about 78% of the burst mains were included in the R&R programme, but the bursts occurred before the works were carried out. The WSD will regularly review the conditions of the water mains that were pending R&R works and, where necessary, will consider to advance the works for those that are at higher risk of bursting.
(b) Since the WSD launched the R&R programme in 2000 to replace and rehabilitate some 3 000 kilometres (km) of aged water mains, works for about 66.5% of the water mains have been completed as at December 31, 2012. About 94% of the water mains have been included in the R&R works contracts already awarded. About 6% are to be included into the remaining R&R works contracts.
(c) The 1 000 km of water mains yet to be completed under the R&R programme are distributed around the territory and more of them are located in the Central and Western district, Wan Chai, the Eastern district, the Yau Tsim Mong district and Kowloon City.
(d) The WSD has installed GSM noise loggers with wireless data transmission capability at the key water mains that are pending R&R works and located at busy roads, such as Connaught Road Central, Lung Cheung Road and Tuen Mun Road. The collected data, after analysis, will help detect leakage and hence prevent water mains burst. In 2012, about 120 leaks in water mains have been identified by detection that enabled repair works to be carried out in a timely manner to prevent water main burst. The measure has achieved satisfactory results.
(e) The WSD has completed pressure management studies in 12 of the 17 major fresh water supply zones in Hong Kong. Studies for the remaining 5 zones are in progress and will be completed by mid-2014. Of the 12 zones that have completed the studies, works for pressure management systems, including construction of underground chambers and installation of pressure reducing valves and flowmeters, are underway in seven zones and detailed design is being carried out in the remaining five zones. As at December 2012, the WSD has completed the pressure management works for about 300 km of fresh water mains in these seven zones, resulting in an estimated annual reduction of water loss of about 5 million cubic meters in fresh water consumption.
(f) Apart from the above-mentioned measures to prevent and handle water main bursts and leakage, the WSD continues to keep abreast of the latest technologies around the world, with a view to further reducing mains bursts and leaks. In 2011, the WSD tested the new "Sahara" and "Smartball" technologies, which involved putting CCTV cameras and acoustic sensors into in-service pressurised water mains, for leakage detection. The technologies have proved to be effective in locating leaks, but the cost is high. As such, the WSD will continue to search for comparable alternatives worldwide in a bid to drive down the cost through competitive tendering as and when such technologies are adopted as regular tools for leakage detection. Moreover, the WSD has procured the new Leak Noise Correlator, AquaScan TM, which can more effectively detect leaks on non-metal pipes and large diameter pipes, to strengthen its leakage detection capability and prevent water mains burst.
In addition to new leakage detection technologies, the WSD commenced the first leakage detection contract adopting performance-based provisions in April 2012 and commenced another contract of similar type in December 2012 to incentivise contractors to take more positive steps and be more accurate in locating leaks. The WSD will continue to explore new technologies and measures to prevent and handle water mains bursts and leaks. While all the current measures are undertaken with the existing manpower and resources, the WSD will review the need to increase manpower and resources from time to time.
Ends/Wednesday, January 23, 2013
Issued at HKT 14:30