For an international metropolis like Hong Kong, a stable water supply forms an indispensable part of its infrastructure. However, given the territory’s scarce land resources, we had to bury most of our water mains under roads or pavements when developing the water supply network. With the rapid increase in development density and traffic flow in various districts, burst water mains on busy roads due to an ageing water supply network will inevitably cause great inconvenience to road users and the public.
A salt water main on Ma Tau Wai Road burst twice at two different sections on September 11 and October 2 this year. In both incidents, colleagues of the Water Supplies Department (WSD) worked hard to complete emergency repair works within the day and reopened the affected areas to traffic as soon as possible. We sincerely apologise to all those affected for the serious traffic congestion and the inconvenience caused during the burst water mains. The two incidents drew public attention due to their close proximity to the Shatin to Central Link (SCL) worksite of the Mass Transit Railway Corporation (MTRC). However, preliminary findings show that the two incidents were mainly caused by the ageing of the water main.
There have not been any bursts in these sections of the water main on Ma Tau Wai Road in recent years, though it has been in use for more than 30 years. Taking its age into account, our WSD colleagues assessed the possible impact of a burst water main on traffic before large-scale traffic diversion was implemented by the MTRC on Ma Tau Wai Road for the SCL works last year, and took the following measures to minimise potential risks.
Firstly, water mains were diverted. Before the SCL works started, the MTRC was commissioned to lay down new water mains on Sheung Heung Road and Kowloon City Road to replace the ones on Ma Tau Wai Road. These works are now in progress. Secondly, monitoring points were set up on Ma Tau Wai Road and in its vicinity to monitor any subsidence and vibration of the water mains near the SCL worksite. Thirdly, the water mains are regularly checked for leakage. Fourth, water pressure in the area between Ma Tau Chung Road and Ma Tau Wai Road has been reduced without affecting the water supply, and finally a contingency plan in the event of burst water mains was drawn up to facilitate the completion of any repair works as soon as possible. The contingency plan proved to be effective in the two recent water main bursts on Ma Tau Wai Road.
To minimise the potential risks of burst water mains in the Ma Tau Wai area affected by traffic diversion, we need to complete the water main diversion works as soon as possible. However, when laying down new water mains, we also have to address the needs of the road users and local residents, and co-ordinate with other concurrent projects in the area. Before the works started we undertook preparation work and co-ordinated with the parties concerned, including applying to the relevant departments for approval for traffic diversion arrangements and for construction noise permits if the works need to be carried out at night due to busy traffic during the day. Since the rules set up by various departments have to be strictly complied with during construction works, and all kinds of difficulties may arise as the works are carried out in crowded underground areas with complicated facilities, it may take a long time to complete the works. According to current estimates, the works will be completed by November this year, and the potential risks of burst water mains in the area affected by traffic diversion will be mitigated.
In fact, the Ma Tau Wai Road burst water main incidents mentioned above are typical examples that demonstrate the WSD’s efforts to reduce the risk of burst water mains and their effects, as well as the challenges facing the department. In 2000, the department implemented a 15-year large-scale Water Mains Replacement and Rehabilitation (R&R) Programme to replace or rehabilitate about 3,000 kilometres of aged water mains in phases to improve the condition of the water supply network. So far, we have completed works on a total of 2,200 km of water mains, with the number of burst water mains dropping substantially from 2,479 in 2000-01 to 267 in 2012-13.
Although the number of burst water mains continues to drop year by year, it is increasingly challenging for us to manage the water supply network. It is particularly challenging to enhance the ageing network in the vicinity of busy roads and in areas with large-scale infrastructure projects under construction. Nonetheless, our colleagues in the WSD will keep the progress of the R&R Programme under review during its implementation to ensure early completion of the works. The whole programme is expected to be completed in stages by 2015.
The WSD will reduce the water pressure in extensive areas in various districts covered by the water supply network, and will check for leakage and monitor the water mains on major roads regularly to reduce the risk of burst mains.
Over the years, WSD staff have endeavoured to reduce the impact of burst water mains on the public. We hope the community will understand that the implementation of large-scale water mains enhancement works will inevitably cause inconvenience.. With the completion of the works, however, we believe that the risk of burst water mains will be further reduced and the water supply become more stable, such that we can all live in a better and more comfortable environment.
27 October, 2013
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