Hong Kong Water Supply – Plover Cove Part 1 Scheme Development

Tymon Mellor: If Government documents are to be believed, the inspiration for the Plover Cove Scheme came from the Director of Water Supplies, Mr T O Morgan while swimming in the sea at Plover Cove[i]. His idea was to convert the sea inlet into a fresh water reservoir by damming the inlet, pumping out the sea water and impounding fresh water. This approach was novel but not new, but it had previously been considered too risky as it was not understood how secure foundations for the dam could be constructed. It was now possible due to the improved understanding in soil mechanics and the experience gained from the construction of Shek Pik Reservoir and Kai Tak Airport runway. Thus, in July 1958 the Finance Committee approved the appointment of Messrs Binnie Deacon and Gourley in collaboration with Scott and Wilson Kirkpatrick to commence investigation into such a scheme[ii].

Deteriorating Water Supply Situation

In the post war environment, Hong Kong experienced significant population growth, in a turbulent region the territory was seen as a stable location and a stepping stone to other countries. To satisfy the demand for fresh water required for the population and the growing industrial development, the Government constructed new reservoirs and started to develop an integrated distribution system, allowing water to be moved around the territory. Between 1957 and 1963 the Tai Lam Chung Reservoir and Shek Pik Reservoir were completed providing an additional 10 million gallons of new storage capacity. However, this was still insufficient and water shortages continued.

Hong Kong Population

It was recognised in the late 1950s that with the population growth of 5% it would quickly outstrip the planned water supply capacity, and this was further compounded by the unreliability of the summer rains. Not only were additional water sources required, there was also a need to store water over multiple seasons to accommodate variations in seasonal rainfall. With a forecasted population of 3 million by 1960, and assuming a consumption of 20 gallons of water per person per day, it would be necessary to be able to store 23 billion gallons to ensure a stable supply. However, even with the addition of the two new large reservoirs at Tai Lam Chung and Shek Pik, the available storage capacity was only 10.5 billion gallons. A new reservoir was required with a capacity of at least 10 billion gallons, but finding a suitable site within Hong Kong would be the challenge.

Following Mr Morgan‘s bathing revelation, two suitable sea water inlet sites were identified, Plover Cove on the north shore of Tolo Harbour and Hebe Haven south of Sai Kung[iii]. With funding available, in July 1958 Messrs Binnie Deacon and Gourley in collaboration with Scott and Wilson Kirkpatrick and Partners commenced investigation into the two sites. These two companies had experience in designing for the Hong Kong environment, with Binnie’s involvement in all the territory’s reservoirs and Scott’s experience on the Kai Tak Airport runway reclamation works.

Prioritising Plover Cove, in October 1958 approval was given to commence site investigations to support the development of the schemes. By February and April 1959, preliminary reports were submitted for the Plover Cover and Hebe Haven respectively. The reports confirmed that Plover Cover could reliably yield 55 million gallons a day for a capital cost of $348 million along with a further $60 million for upgrades to the water distribution network including service reservoirs and distribution mains.

Reservoir

Height above mean sea level (m)

Capacity

(million gallons)

Yield

(million gallons day)

Plover Cove

7.0

29,000

55

Hebe Haven

3.6

3,900

20

 

Plover Cover Initial Proposal

The Plover Cove scheme required the construction of a 1.9km dam across the sea inlet, with secondary dams between adjacent islands to create the new reservoir. A pump house would be provided adjacent to the dam and twin 1.2m diameter submarine pipeline pass under the Tolo Harbour to connect to a new water treatment works on the hill above Tai Po. From there, the water would continue in twin 1.2m mains to a new storage reservoir by the KCRC railway tunnel portal on the Shatin side of Beacon Hill. A second pumping station would then raise the water through a new tunnel at Lion Rock to discharge into a new 20 million gallon service reservoir on the hills above Kowloon. This new facility would then feed into the existing Kowloon water distribution system. Implementation of this scheme was forecast to take seven to nine years before it would be productive.

Initial Scheme Proposal

In late July 1959 the Government provided $4 million to enable further detailed investigations and to pursue enquiries into the practicality of sea water distillation utilising nuclear power.

Hebe Haven

The report on Hebe Haven identified that the scheme would be similar to Plover Cove but on a smaller scale. The proposal was to construct a 550m long dam across the outer entrance of the inlet where a pumping station would deliver the water to the new industrial area of Kwun Tong through nearly 9km of tunnels. To minimise the impact on agricultural land and the existing villages, it would be necessary to keep the water level as low as possible, but this arrangement would have only a limited yield. If, however the dam could support a water level 3.6m above mean sea level, the reservoir could supply 20 million gallons a day and be completed within five to six years. The water supply would be cheaper to integrate into the existing supply network with the scheme estimated to cost $95 million[iv] which would be significantly cheaper than Plover Cove.

Hebe Haven Reservoir

All Change

In January 1960, a number of new developments occurred that would change the approach for the water supply. The consultant had been exploring the opportunity to integrate the two proposals while the Government had been negotiating the supply of water from the Mainland and other northern sources. The new Sham Chun or Shenzhen Reservoir would supplement the local water supply and could be integrated into the supply scheme.

While new water sources were being explored, the Director of Public Works had prepared a new assessment on the water demand. It indicated that rather than an annual increasing consumption of 6 million gallons a day it was more likely to be 10 million gallons a day, once supply restrictions were removed. On this basis, even with the proposed Plover Cove and Hebe Haven scheme, the Territory would once more be short of water by 1970 and supply restrictions would need to be re-introduced. The scheme needed to be enhanced.

In early 1960, the scheme was refined to raise the combined yield from 75 million gallons a day to 100 million gallons a day through optimisation, integration and expansions. The changes included:

  • Hebe Haven lacked the capacity to store all the water available from the catchment, thus in the wet season this would overflow into the sea. To avoid this waste, it was proposed to send the surplus water through pipe line to Plover Cove;
  • Replace the pumped supply system from Plover Cove with deep tunnels allowing the interception of hillside streams along the route;
  • Rather than sending the water from Hebe Haven direct to Kwun Tong, construct a tunnel to the original Shatin pumping station site, intercepting rivers and streams along the route;
  • Construct a large water treatment plant at the Shatin site for all the water;
  • Provide new balancing reservoirs to assist in water management, one to be constructed below the existing Shing Mun Reservoir and one at Three Fathoms Cove on the south side of the Tolo Channel; and
  • Extend the scheme north of Tai Po to intercept water from the Northern Sources, local rivers, pumped from the Indus and supplied from Shenzhen Reservoir.

Plover Cove Scheme

By adopting a tunnelled solution, it was possible to design the scheme to operate using gravity flow, minimising the need to pump the water. A further refinement allowed the scheme to operate in either direction, thus in the wet season the tunnels would transfer water into Plover Cove and in the dry season, they would extract water from the reservoir.

This new scheme arrangement had a number of strategic advantages:

  • it could be built and commissioned in stages thus allowing early delivery of the new water supplies;
  • the operational elements, such as the Shatin treatment works were scalable minimising initial expenditure;
  • the staged implementation allowed time for development of the design for the high-risk elements such as the dams; and
  • the new Shenzhen water supply was to be delivered to the Tai Lam Reservoir and treated at Tsuen Wan, but this had limited capacity. By diverting the supply to Tai Po Tau it could be incorporated into the new scheme along with the opportunity for further expansion.

Water Demand Supply

The project cost for the new scheme would rise from $541 million for the separate reservoir arrangement to $641 million for the integrated scheme. On the 23th March 1960 the Finance Committee approved expenditure to further develop the integrated scheme and allow early construction of the works to allow 20 million gallons a day of water to be available in 1964 for an estimated cost of $100 million.

With funding in place, work could now commence on the construction of the Stage 1 Works[v]. This would include;

  • Stage 1 of the pumping station at Tai Po Tau;
  • Tunnel from Tai Po Tai to Shing Mun;
  • Lower Shing Mun reservoir;
  • Stage 1 of the Shatin treatment works with capacity for 60 million gallons a day;
  • Lion Rock Tunnel; and
  • Service reservoir in Kowloon.

In November 1960, ten months after the scheme had been proposed, construction works commenced.

Project Office

Images

The University of Hong Kong Digital Repository – 1964

South China Morning Post

Full Report on the Plover Cove & Hebe Haven Water Scheme – 1962

Sources

[i] Plover Cover, Water Supplies Department, PWD, 1978

[ii] Hong Kong Annual Report, 1960

[iii] Hong Kong Annual Report, 1960

[iv] Augmentation of the Water Supply of Hong Kong, G A R Sheppard, 1960

[v] Annual Departmental Reports 1960-61, Director of Public Works

This article was first posted on 1st August 2021.

Related Indhhk articles:

  1. Plover Cove Reservoir – photographs of official opening 1969
  2. Plover Cove Reservoir – 1977 Water Supplies Dept report
  3. Q&A48 T.O.Morgan, Director of Water Supplies – imagined Plover Cove Reservoir while swimming in the area

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