As a densely populated international city, Hong Kong needs not only good urban planning above the ground, but also large-scale and sophisticated underground facilities to maintain safe and effective operation of our city. These underground facilities include pipelines serving various functions, such as conveying potable water and flushing water, stormwater drainage, and sewage treatment and disposal. Moreover, there are also innovative underground works to stabilise our slopes and to increase our land resources through rock cavern and underground space development. While we may not see these underground pipelines or facilities very often in our daily lives, they are just like the blood vessels in our bodies and quietly support the functioning of our city.
Recently, Radio Television Hong Kong (RTHK) produced an eight-episode documentary series entitled "Underground Order" (地下秩序), in which six episodes cover the work and related facilities of the Drainage Services Department (DSD), the Water Supplies Department (WSD) and the Civil Engineering and Development Department (CEDD) under the Development Bureau. I highly recommend this documentary series to all of you as it not only explains technical concepts in layman terms, but also gives us a glimpse of these underground facilities. As a lot is covered in the series, I can only highlight some of the episodes below. I would also like to take this opportunity to express my gratitude to colleagues of our works departments for their professional work and contributions throughout the years.
"Underground Tunnels"
This episode introduces how we optimise underground space to construct facilities such as stormwater storage tanks and drainage tunnels to reduce flooding risks in the urban areas. As we all know, most of the drainage systems in the older districts were constructed decades ago and can barely meet the drainage needs during heavy rainstorms. But it is not easy to carry out enlargement or improvement works under busy streets. Therefore, we have to resort to interception or storage of stormwater as ways to address the issue. Interception is the construction of drainage tunnels on the hillside to intercept stormwater from the upstream hilly areas. Intercepted stormwater is then drained into stilling basins through branch tunnels and then discharged into the sea. Storage refers to the construction of underground storage tanks to store excess stormwater temporarily. Both methods can reduce the flooding risks in the urban areas. This episode contains footage of how floodwater is discharged from the drainage tunnels and stormwater storage tanks, enabling us to see nature’s power. We can imagine how much damage could have been caused by heavy rainstorms to our city without this underground infrastructure.
"Deep Sewerage Treatment Works"
This episode introduces our sewage treatment strategies and the largest sewage infrastructure in Hong Kong – the Harbour Area Treatment Scheme (HATS). It leads us into the deepest underground works project in the territory – the 21-kilometre sewage tunnel, which is part of the works under HATS Stage 2A. We can see workers at work 160 metres (roughly the height of Jardine House) below sea level, including the application of grouting techniques during excavation to prevent the influx of a huge amount of underground water into the tunnel. This is by no means an easy task and I would like to express my sincere thanks to our DSD colleagues for their hard work in completing the works. It is anticipated that the facilities under HATS Stage 2A will be commissioned by the end of this year. By then, the water quality of Victoria Harbour will be further improved.
"Network of Mains"
This episode introduces how the WSD builds the water supply network, repairs and cleans service reservoirs, and monitors water mains on a daily basis to detect and prevent leakage. What has impressed me most was that the filming crew climbed into an underground water main of less than one metre in diameter to film how workers rehabilitate the internal walls of water mains by applying a fibreglass coating to minimise the risk of water leakage. I would like to take this opportunity to pay tribute to our colleagues for all their long hours of hard work inside such cramped and confined spaces just to help us prevent wastage of our precious water resources. My thanks also go to the filming crew of RTHK for giving us a rare opportunity to witness the contributions made by our construction workers for the well-being of Hong Kong.
"Landslide Prevention"
This episode introduces the landslide preventive works carried out by the CEDD and highlights the use of soil nails in such works as well as the Po Shan Drainage Tunnel. The drainage tunnel uses an innovative method to reduce the risk of landslides by monitoring the underground water levels of the natural hillsides around Po Shan Road. The facilities hidden inside the slopes, perhaps not known to the public at large, are playing their part in protecting slope safety in Hong Kong. I would like to express my gratitude to the colleagues of the CEDD for their efforts in ensuring slope safety in Hong Kong.
The above four episodes, which were broadcast last month, can be viewed again at the following website:
http://programme.rthk.hk/rthk/tv/programme.php?name=tv/subsurfacerules
The other two episodes of "Underground Order", to be broadcast on August 27 and September 10, will cover the CEDD’s studies on rock cavern and underground space development as one of the long-term measures to increase land supply. These two episodes will take the audience deep into the Stanley Sewage Treatment Works built inside a rock cavern, and also follow our research team on underground space development during an inspection visit in Guangzhou.
This documentary series is professionally produced, and features beautiful shots and clear illustrations. It is well worth watching.
23 August, 2015
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