Hong Kong Water Supply – Shing Mun First Section
Tymon Mellor: We take for granted that when we turn a tap on clean water will flow. However, for the majority of Hong Kong’s colonial history, there were water shortages and supply restrictions. This was not a result of poor policy decisions but of changing circumstances, financial limitations and geographical constraints, and unlike other major conurbations, Hong Kong has no major natural water courses and bodies such as rivers and lakes to provide a secure water source.
With a growing population on Hong Kong Island and Kowloon, there was a constantly growing demand for drinking water. The early existing supplies, primarily the Tai Tam reservoirs and Kowloon Reservoir were proving insufficient to meet the population needs. During 1921 and 1922 investigation commenced on locating a new water sources, Aberdeen and the Shing Mun Valley were identified as the best future options.
With the completion of the Tai Tam Tuk scheme in 1917, Hong Kong Island had secured its immediate water supply. However, this would not last and the Public Works Department looked to identify new sources of water and sites for new and larger storage reservoirs. Short term solutions including the development of the Aberdeen Valley and additional reservoirs associated with Kowloon Reservoir were implemented, but the largest opportunity for increasing supply was among the hills around the Shing Mun Valley. During 1921 and 1922 preliminary investigations were undertaken which included detailed surveys of Shing Mun and Gin Drinkers Bay along with installation of rain gauges and the measurement of water flows. Under the direction of Mr R M Henderson, the head of the water department, a detailed proposal was developed comprising multiple reservoirs and the first cross harbour connection.
The Shing Mun Scheme
In April 1924, R M Henderson presented his report on the Shing Mun Valley Waterworks[i], identifying the development of the scheme in five sections or stages, adding an additional 17 million gallons a day to the existing 10 million gallons a day for Hong Kong Island and 3 million gallons a day for Kowloon. Treatment of the water from the new reservoirs would be at a new Kowloon treatment facility before the water was piped to Kowloon and Hong Kong Island to a new service reservoir in the Botanical Gardens.
The Shing Mun Scheme included:
Dam no. 1: Located at the head of the Shing Mun Valley and would be 270m long and 44m high, impounding 900 million gallons.
Dam no. 2: Located in the located close to the current Shing Mun dam, with a length of 134m and a height of 49m impounding 900 million gallons. A third dam, number 2A was identified in a side valley, 76m long and 30m high, impounding 185 million gallons.
Dam nos. 3 and 4: On the southern slopes of Tai Mo Shan, two smaller dams were proposed, numbers 3 and 4 impounding 200 million gallons and 137 million gallons respectively.
Dam no. 5: Located in the site of the current lower Shing Mun reservoir would require a dam of 153m long and height of 30m, impound 400 million gallons.
Dam no. 6: Located up-stream of Tai Wai village, requiring a long dam of 530m and 26m high and impounding 1,700 million gallons. With the dam located at such a low level, a pumping station and rising mains would be required to deliver the water into the supply network.
Dam no.7: The most adventurous of the proposals was to adopt a similar solution to Tai Tam Tuk and dam the Gin Drinkers Bay Valley, allowing the storage of two to three thousand million gallons, the water then being pumped uphill into the distribution system.
The proposed ‘First Section’ of the scheme development was to include a new 3.2km access road to Pineapple Pass, a small intake dam on the Shing Mun River with a conduit and tunnels to a new reception reservoir, filter beds and a service reservoir. It also included a new supply main through Kowloon and across the harbour, feeding new service reservoirs at Garden Road on the Hong Kong Island and a Service Reservoir at Pipers Hill in Kowloon. This work was forecast to provide an additional 3 million gallons a day at a cost of $3,500,000.
The ‘Second Section’ would see an extension of the access road and new dams at dam sites 1, 2 and 2A, along with catchwaters, extension of the filter beds and a second trunk main to Kowloon. This would provide an additional 7 million gallons a day for a cost of $4,750,000 and require the relocation of 855 persons residing within the eight villages within the Shing Mun Valley impacted by the scheme.
The ‘Third Section’ would include additional catchwaters on the southern slopes of Tai Mo Shan with dams 3 and 4 and the third section of the filter beds, adding a further 4 million gallons a day for $2,000,000.
The ‘Fourth Section’ would require a new access road from Tai Wai to the new low level dams 5 and 6, catchwaters, pumping station, rising mains and a third trunk main to Kowloon. This scheme would provide an additional 6 million gallons a day for a cost of $6,500,000.
The final ‘Fifth Section’, would be the Gin Drinkers Bay reservoir. However, this was considered very doubtful due to the poor ground conditions identified at the dam sites.
Excluding Gin Drinkers Bay, the cost of the full scheme came to $17 million, well beyond the finances of the Colony, and an alternative funding arrangement would be required. In July 1923 the proposal for a staged implementation of the Shing Mun Scheme was endorsed by the Executive Council and forwarded to the Secretary of State for the Colonies for approval[ii].
Shing Mun First Section
Following a review of the scope of the First Section, it was decided to proceed in stages, with the initial portion to be completed by June 1926[iii]. The scope would include;
- Access Road from Tsuen Wan to Pineapple Pass;
- Intake Dam across the Shing Mun River and Temporary Conduit in Shing Mun Valley;
- North Conduit in Shing Mun Valley;
- North Tunnel under Smugglers Ridge, South Tunnel under Golden Hill and South Conduit connecting them; and
- Reception Reservoir in Lower Shek Lai Pui valley.
With these works in place, the water supply for Kowloon would be secured and if supply on the Hong Kong Island was still a problem it would be possible to complete the cross harbour pipe line to supplement the supply. An initial funding of $2 million was identified for the initial portion of the works.
Back in London, the general election of December 1923 resulted in a hung parliament with Labour replacing the previous Conservative administration. The Labour administration would stay in power for just over 12 months before the Conservative party was once more returned to govern. During the short administration, J H Thomas was appointed the Secretary of State for the Colonies and he was not confident in the Shing Mun Scheme proposal. In April 1924 he requested further justification for the scheme, to which the Governor R E Stubbs responded[iv] with a detailed report noting that problems with water shortage and the “considerable anxiety” among the local residents. The Governor admitted the cost was expensive but noted that “the expense is unavoidable and, as the cost of labour and materials is continuously increasing, it will only be increased by delay in beginning the works”.
The Colonial Office was nervous with the proposal, as a file note recorded[v];
“It does not seem wise to adopt so large a scheme without the best technical advice and the Waterworks engineer who is advising appears to be an engineer in the services of the Colonial Government at a salary of £620-700. In view of the urgency the Secretary of State may be unwilling to refuse leave to proceed with the first section. This does not seem to involve large dams such as some of the later sections require, but it would seem desirable to have a competent opinion on the scheme as a whole, for which purpose a consulting engineer would have to be sent out from this country at least as far as we know, there is no one there with sufficient local knowledge to advise”.
Given the urgency of the situation and the low risk nature of the works, approval to proceed with First Section was received in May 1924 allowing works to proceed, with the addition of:
- Filtration plant and covered service reservoir;
- 600mm truck main through Kowloon;
- Covered service reservoir at Pipers Hill with a capacity of 1.5 million gallons;
- 600mm cross harbour main; and
- 5 million gallon service reservoir in the Botanical Gardens.
In addition to the Shing Mun works, the Colonial Government had approved funding for the Shek Lei Pui reservoir in 1923 and the Kowloon Bywash Reservoir in 1929.
Construction of a new road into the Shing Mun Valley was authorised in late 1922 on the basis of providing access for the necessary survey work[vi]. Work commenced in 1923 with the award of the works to Messrs Chun Sing for $98,288. Progress was slow and by the end of the 1924 only the excavation had been completed. By the end of 1925 the works on the 3km road were substantially complete with over 4,900m3 of rock removed and 43,000m3 of soft material excavated for the 4.8m wide carriageway.
Temporary Intake and Conduit
A temporary intake dam and associated conduit were constructed to collect water from the Shing Mun River for delivery to Kowloon using the new distribution system. The works were temporary in nature as they would be abandoned with the completion of the main Shing Mun dam.
Construction of the small dam and conduit were awarded to Mr Ng Wah for $64,101 in 1925 and by the end of the year, the works were substantially complete. The temporary dam had a length of 35m and maximum height of 10m and fed the temporary 1,840m long conduit with the capacity to transfer up to 10 million gallons a day into the new permanent North Conduit.
The conduit followed the contours around the hills with a short sections of reinforced concrete box over streams and small depressions.
Construction of the North Conduit was also awarded to Mr Ng Wah in February 1925 for a value of $70,801. The works covered the construction of the permanent conduit from the temporary conduit, at the location of the future dam location to the new north tunnel, a length of 880m with a capacity of 12 million gallons a day. Good progress was made and the works were complete by the end of 1925.
North Tunnel, South Conduit and South Tunnel
Construction of the North Tunnel and South Tunnel along with the connecting South Conduit were awarded to the British firm of Sir W G Armstrong Whitworth & Co in December 1924 for $1,052,344[vii]. The company employed a large European staff, modern plant and modern construction methods.
To overcome the remoteness of the construction site, two cableways were erected for the delivery of materials, one from the Castle Peak Road serving the South Conduit, the other from the Tai Po Road to serve the south end of the south tunnel. Excavation of the tunnel used explosives to blast the granite rock.
Work on the North Tunnel commenced in April 1925 from the south portal and in December 1925 from the north portal. Excavation of the tunnel was predominantly through competent granite but intrusions of shale, soft clay and running sands were encountered. These delayed progress and required the installation of a 300mm thick concrete arched roof. The tunnel was 620m long excavated in a horse-shoe shaped cross-section, 2.1m wide at the bottom and 2.2m high.
The tunnel broke through on the 9th August, 1926 after 16 months driving at a point 45m from the north portal. Completion of the tunnel invert lining and portal structures were finished in December 1926.
The South Conduit, 610m long connected the North Tunnel to the South Tunnel. Work commenced in early 1925 and was completed in early 1926. A two-span reinforced concrete bridge was constructed to carry the conduit across a major stream.
Construction of the South Tunnel commenced at the north end in February 1925 and at the south end two months later. Good quality granite was encountered throughout the length of the 1,420m tunnel. Breakthrough was achieved on the 4th July 1926 after 19 months of tunnelling, with all work completed by the end of the year.
Kowloon Reception (Shing Mun Reception)
A contract for the construction of the 33.15 million gallon reservoir was awarded to Messrs Trollope & Colls (Far East) Ltd in December 1924. The works include the construction of a draw-off dam with a valve house and an overflow dam with overflow channel.
Construction of the reservoir achieved good progress in the first year but by 1926 labour troubles delayed the progress of the works. Hong Kong had suffered boycotts and strikes since the summer of 1925 as a result of an incident in Shanghai when Sikh police under British command opened fire on a crowd of Chinese demonstrators. The mainland strike committee encouraged Chinese to leave the Colony and the population to go on strike. The Hong Kong Government implemented emergency measures, replacing striking workers and removing pro-strike material[viii]. However, by the summer of 1926 the disruption abated and by the end of the year the works were complete on the 33.2million gallon reservoir. The concrete draw-off dam was 69m long with a maximum height of 14.6m. The overflow dam was 26.5m long with a maximum height of 5m to the overflow.
With the completion of the reservoir, tunnel and conduit, the Shing Mun River was diverted through the new tunnel on the 24th December 1926 and supplied water to the existing Kowloon filter beds.
Filtration Plant & Service Reservoir
In late 1925, a contract was let to Paterson Engineering Company in England for the supply and installation of eight rapid gravity filters along with chemical dosing equipment. The facility was the first part of a two-part installation, providing an initial 5 million gallons a day with the capacity to double the capacity with the second stage of installation.
Construction of the buildings commenced in June 1927 following the arrival of building details from the supplier and were only partially complete when the equipment arrived from England in late 1927. The buildings were completed by May 1928 allowing installation and testing of the equipment to be completed by the end of 1928. The facility was brought into service on the 10th June 1929 supplying the new Piper’s Hill service reservoir with approximately 1 million gallons of treated water a day[ix].
During 1928, a design was prepared for the Shek Lai Pui Service Reservoir, located immediately adjacent to the filtration plant. Construction of the 10.6 million gallon covered reservoir was awarded on the 14th September, 1928 to the Hong Kong Excavation Pile Driving and Construction Company for $253,433. By the end of 1928 excavation of the eastern half of the structure had commenced allowing a start on the reservoir structure in June 1929 and the roof in November, 1929. As work proceeded it was found to be economical to enlarge the structure to provide an enhanced capacity of 11.4 million gallons.
The reservoir had a dividing wall allowing the eastern cell to be completed first by the end of April 1930 and commissioned into service in July 1930 following the completion of the inlet and outlet control valve houses. Progress on the western half was good until more extensive rock than anticipated was encountered, delaying the completion and commissioning until the end of the year.
The reservoir was fed from the rapid gravity filter plant and supplied the 600mm Kowloon distribution main. Provision was made for two future trunk mains connections.
A new 600mm distribution main was installed from the Shek Lai Pui Service Reservoir to a number of distribution points in Kowloon and to the harbour pipeline to Hong Kong Island. A contract was let in 1925 to Messrs Stewart & Lloyds in England for the supply of the steel pipe and Messrs Glenfield and Kennedy Ltd for the valves and fittings. By the end of 1926 all the off-shore procured equipment was in the Colony, allowing installation to commence in May, 1927. The installation of the trunk main commenced between Cheung Sha Wan and the service reservoir, being ready for testing by May 1928. Work then commenced on the next section to the junction of Nathan and Prince Edward Road. Work was suspended in August 1928 due to widening works of Castle Peak Road blocking the route, and permission was granted to continue installation by the end of October, 1928. This section was finally completed in May 1929 including the remaining section of pipe line, passing under the Kowloon Canton Railway station which was completed to the sea wall to join the cross harbour pipe.
The new pipe line to the Piper’s Hill Service Reservoir was bought into service on the 10th June, 1929 with the completion of the new reservoir. The remaining pipeline through Kowloon was commissioned on the 31st March 1930 in conjunction with the new cross harbour pipeline. The total length of pipe laid through Kowloon was 7,325m.
Towards the end of 1929, work commenced on the distribution main on Hong Kong Island with the installation of the 600mm main from Queen’s Pier connecting to an existing 380mm main at the corner of Wardley Street. This would later be extended to the new Gardens Service Reservoir, once complete.
Pipers Hill Service Reservoir
The Pipers Hill Service reservoir was a covered structure with a capacity of 1.5 million gallons. It was fed from both the new Shek Lai Pui Service Reservoir and from Kowloon Filters. The reservoir was required to provide additional storage for Kowloon and the Lai Chi Kok Water Boat supplies. The reservoir was located on a spur above Cheung Sha Wan.
A contract for the construction of the reservoir was let in September 1924 to the Mr Ng Wah and good progress was made with the excavation completed by the end of 1924. The reservoir was completed and brought into use by the end of 1925.
Cross Harbour Pipe Line
The provision of a cross harbour pipe line to supplement the Hong Kong Island supply had been considered on many occasions but had been rejected due to costs. In Osbert Chadwick’s follow-up report of 1902[x] he identified the opportunity of a harbour pipe, “it will be difficult, though by no means impossible. It will, however, certainly be costly”.
For the Shing Mun Scheme to support the Hong Kong Island water supply, a detailed understanding of the harbour was required to develop the design. Thus, in May 1923 a tender was issued for the “Tender for Borings and Prickings in Hongkong Harbour”. The site investigation resulted in 15 bore holes and 56 samples from the sea bed on an alignment between Nathan Road and Jackson Road[xi]. The results of the survey were sent to Mr William Fairly[xii], a Consulting Engineer to the Crown Agents for the Colonies based in London, specialising in water supply. In 1925 he prepared a design for the laying of two 450mm cast iron mains across the harbour. To avoid the risk of ships anchors fouling the pipes, the mains were to be buried in a trench in the seabed. Tenders were called for the installation works, but with an ongoing trade embargo and social problems in Hong Kong, the works were suspended due to the lack of funds in the Colony.
Work continued to find a more cost effective solution. In 1926 Mr Fairley wrote to Mr R M Henderson suggesting that if anchorage could be prohibited over the pipe line, it would be possible to lay two smaller pipes of 225mm diameter directly on the sea bed and save possibly half the cost of the original project[xiii]. He noted, “I do not suggest it is a better scheme, but the difference in cost would be so much that it might allow the works to proceed which could not be put in hand owing to the financial position”.
Mr R M Henderson, adopted the Mr Fairley’s suggestion but revised the design to a single 311mm diameter pipe and by 1929 a new proposal was submitted to the Colonial Office in London for endorsement. As the Colonial Office adviser, Mr Fairley, reviewed and endorsed the proposal, noting that given the low risk of damage to the pipeline from shipping and the pipeline having a life of only ten years the proposal would be acceptable.[xiv] An earlier proposal to partially protect the pipe within a trench had been rejected due to the lack of suitable construction plant. To minimise the impact of possible damage, ball and socket joints were proposed ensuring in the event of a dragging anchor the main would break at the joint and avoid damage to the pipes, allowing repair to be made within a few weeks.
In addition to the design of the crossing pipe, concern was raised into the geological nature of the harbour. At the time there was no geological maps for Hong Kong. The Colonial Office had an agreement with the Department of Geology of the University of British Columbia to map the territory but the work was not yet complete. Four geologists undertook field work between 1923 and 1927 in preparation of the map and the associated report[xv]. Among the geologists was R W Brock who became the Government’s advisor on matters relating to geology and minerals.
In early 1929 Mr Brock[xvi] provided guidance on the harbour geology along with a geological cross section. He recommended additional bore holes along the alignment of the pipe line and between the original holes to see if there was any possibility of any unknown channels. He also suggested sinking a shaft on Kellett Island and drilling horizontal bore holes across the harbour to confirm the extent of the rock.
In January 1929 the Colonial Government decided to proceed with the harbour pipe line and send Mr R M Henderson, now the Assistant Director of Public Works to London to finalise the scheme with Mr Fairley. In May 1929 the Colonial Office endorsed the scheme and in June, 1929 a contract was signed with Messrs Stewarts & Lloyds for the supply of the steel pipes and fittings. Mr Henderson and the first consignment of pipes arrived in the Colony in September 1929.
A pipe assembly yard was established along the Praya East, opposite Arsenal Street and fabrication works commenced on the 13 October, 1929. Preparation works had commenced in the harbour, with a detailed survey. This identified the sea bed which generally consisted of hard sand with occasional small boulders. The final 240m at the Kowloon end and 120m at the Hong Kong Island side consisted of mud. This was dredged to a depth of 1.2m and replaced with rubble mound to provide a suitable foundation for the pipeline.
The Netherlands Harbour Works Co Hong Kong was contracted to install the single 311mm diameter pipe. Following the arrival of the ball and socket joints, the first section of the pipe was placed on the 17th December, 1929 in the centre of the harbour and proceeded for the following 57 days with the last section completed on the 17th February, 1930. The underwater pipe connections were undertaken using northern Chinese divers under the supervision of a Government diver, Mr Petroff[xvii].
To secure the pipe, 300mm square concrete piles were driven either side of the pipe to prevent lateral movement in water less than 10.5m deep. In deeper water, 17t precast concrete anchor blocks were sited on each side.
With the completion of the harbour pipe, the connections to the existing mains were completed on the 23rd February, 1930 followed by testing ready for the Governor to officially open the line on the 31st March, 1930.
Gardens Service Reservoir
The final part of the Shing Mun First Stage required the construction of a service reservoir in Hong Kong Botanical Gardens known as Gardens Service Reservoir. The reservoir was to be fed with water from Shing Mun, through the new harbour pipe.
Work started in 1929 with site investigation, confirming that little rock would be encountered in the excavation for the reservoir. A contract for the construction of the reservoir was awarded on the 15th September, 1931 to Messrs Yee Lee & Co for a sum of $189,500. Good progress was made with the excavation and construction of the 4.9 million gallon reservoir and the new facility was commissioned on the 4th May, 1933. During construction, settlement was experienced on the main walls of the northwest corner of the structure requiring the wall to be underpinned and the ground strengthened with grouting. This would later become a major problem for the reservoir with excessive leakage, reducing capacity and requiring reconstruction of the structure immediately after the war[xviii].
First Section Completion
With the completion of the Gardens Service Reservoir, the whole of the First Section of the Shing Mun scheme was complete. Construction commenced in 1923 and was completed within ten years for a total cost of $4.1 million (Mexican silver dollars).
|Element||Cost (Mexican Silver Dollars)|
|Resumptions (see next article)||428,850|
|Water Filter Plant||206,390|
|Kowloon Pipe Line||465,704|
|Piper’s Hill Service Reservoir||136,699|
|Temporary Intake and Conduit||73,269|
|Harbour Pipe Line||299,972|
|Tunnels and South Conduit||1,073,644|
|Shek Lei Pui Service Reservoir||300,449|
|Gardens Service Reservoir||240,303|
|Hong Kong Island Pipe Line||22,489|
|Kowloon Byewash Reservoir||518,623|
With the completion of the First Section of the Shing Mun Scheme, the demand for water was out-stripping supply and implementation of the Second Section was required. This would pose new problems and challenges to Hong Kong’s engineers.
[i] Report on the Shing Mun Valley Waterworks Scheme, R M Henderson, 8 April 1924
[ii] Public Works Report 1923
[iii] Shing Mun Valley Waterworks Scheme, Harold T Creasy Director of Public Works, 15 April, 1924
[iv] Letter R E Stubbs to J H Thomas dated 16th April 1924
[v] CO129/484 File Note 28th May 1924
[vi] Legislative Council, 12th October, 1922
[vii] Report On The Construction Of The First Section Of The Shing Mun Valley Water Works Scheme, W Woodward, 26th April, 1935
[viii] Unions and students in Hong Kong and Canton strike-boycott against British imperial rule, 1925-1926, https://nvdatabase.swarthmore.edu/content/unions-and-students-hong-kong-and-canton-strike-boycott-against-british-imperial-rule-1925-1
[ix] Public Work Report 1929
[x] Preliminary Report On The Sanitary Condition Of Hongkong, Osbert Chadwick, 10th April 1902.
[xi] Public Work Report 1924
[xii] 1922 Who’s Who In Engineering, https://www.gracesguide.co.uk/1922_Who’s_Who_In_Engineering:_Name_F
[xiii] Hong Kong Harbour Crossing, William Fairley, 4th August 1926 CO 129/513
[xiv] Hong Kong Harbour Crossing, William Fairley, 17th May 1929 CO 129/513
[xv] Report on the Geological Survey of Hong Kong, P M Allen & E A Stephens, 1971
[xvi] Letter, R W Brock, 24th January 1929
[xvii] Report On The Construction Of The First Section Of The Shing Mun Valley Water Works Scheme, W Woodward, 26th April, 1935
[xviii] The Hong Kong Waterworks, Leonard Jackson, 1952
This article was first posted on 28th March 2020.
Related Indhhk articles:
- Hong Kong Water Supply – The Tai Tam Tuk Scheme First Section
- Hong Kong Water Supply – The Tai Tam Tuk Scheme – Second Section
- Hong Kong Water Supply – The Politics of Water Supply and Rider Main Districts (1890-1903)
- Hong Kong Water Supply – Kowloon Reservoir
- Hong Kong Water Supply – Tai Tam Upper Dam (formally Tytam Reservoir)
- Hong Kong Water Supply – Kowloon Peninsula
- Hong Kong Water Supply – Pok Fu Lam Reservoir
- Hong Kong Water Supply – Mint Dam and Other Early Structures
- Hong Kong Water Supply – The Aberdeen Reservoirs Scheme
- Hong Kong Water Supply – Shek Lei Pui and Kowloon Byewash Reservoir
- The Hongkong Engineering & Construction Company Ltd 1922-1993
Our Index contains many other articles about Hong Kong reservoirs.