Two factors balanced each other in planning further exploitation of the colony’s water resources. More reservoirs of the type already in use would displace more farmland than Hong Kong could afford to lose. But the introduction of grouting, the foundation technique successfully employed at Shek Pik, made it possible to consider reservoir sites which would have seemed ridiculously unsuitable a few years earlier. And these sites, it appeared, could be developed without invading farm areas.
In the late 1950s, engineers of the Public Works Department and two consulting firms directed their search for more water toward the thinly settled scrub country of the eastern New Territories. This part of the colony consists of two peninsulas with the irregular outline of an ink-blot, separated by the broad, ten-mile-long Tolo Channel. Both peninsulas are chopped into by dozens of deep bays, coves and inlets bordered by high, rocky hills. Hundreds of inshore fishermen ply the surrounding waters, but most of the region is too barren and mountainous for farming.
Survey engineers made two recommendations which startled laymen: (1) Build a 6,600-foot-long dam across the entrance of Plover Cove, a four-square-mile inlet from Tolo Channel, and cut it off from the sea. (2) Build a similar but much shorter dam to seal off Hebe Haven, an inlet about one-fourth as large as Plover Cove. When the dams were finished all that would be necessary would be to pump the seawater out of the inlets and let the rains fill them with fresh water. The two reservoirs would be enough to double the storage capacity of the colony’s water-supply system.
These basic recommendations in further discussions evolved into an integrated scheme of tremendous size and complexity, covering the entire eastern half of the New Territories. It included a series of service reservoirs and pumping stations along a main pipeline extending from the Red China border to Kowloon. These would be linked to Plover Cove and Hebe Haven by another system of tunnels. Virtually all the surface rains in the eastern end of the New Territories would be fed through catchwaters into the two main reservoirs. Since Hebe Haven might collect more summer rain than it could hold, the excess water could be conveyed by tunnel to Plover Cove, with its much larger capacity. Even the water brought by pipeline from Red China would be fed into the integrated system. Three balancing reservoirs, to maintain a controlled and even flow of water, and two large new filtration plants, to purify the water before it made the last stage of its journey to urban consumers, were to become part of the system.
Many of the connecting pipelines were to be designed to convey water in either direction, making the utmost use of storage capacity. By these refinements of the original recommendations, the capacity of the integrated scheme would be raised to 100 million gallons a day when it came into full use.
The first stage of the gigantic new system had made remarkable progress by the early part of 1962. The Lion Rock Tunnel had already been begun by cutting through the side of a mountain to connect the filtration plant at Sha Tin with a pair of service reservoirs in Kowloon. The tunnel, 32 feet in diameter, will carry three pipelines, each four feet in diameter, and a two-lane, 24-foot-wide auto road three-fourths of a mile through Lion Rock Mountain. Excavation work on the Lion Rock Reservoirs, with a total capacity of 41 million gallons, had almost been completed. At the other end of the tunnel, at the Sha Tin filtration plant and pumping station, a hillside site as extensive as four football fields had been excavated and the spoil was being used to fill a shallow inlet. Construction of ten miles of tunnels and the 10-foot-high Lower Shing Mun Dam were well advanced.
Meanwhile, engineers were probing the soil structure at the entrance of Plover Cove. Working from barges in 35 feet of water, they bored down through 35 feet of soft clay, reaching to almost twice that depth before they found impermeable clay and rock to form the foundation for their earth-fill dam. When complete, the dam will extend 35 feet above the water and 70 feet below it, with grouting to provide a watertight foundation. The main section of the dam will cross the cove’s wide entrance. Two shorter sections will close off side entrances to the cove.
The first stage of this integrated scheme will be rounded out in 1964. Both Hebe Haven and Plover Cove should be ready by 1970, though any completion dates beyond 1964 are likely to be elastic. At each stage, improvements are introduced and existing goals altered.
In addition to these broad-scale developments, the colony has taken immediate measures to conserve the present supply of fresh water by making it possible to use salt water for such purposes as flushing and fire-fighting. Since 1958, salt-water mains have been installed in four densely populated sections of Kowloon and two on Hong Kong Island. Fluoridation of the entire water supply began in March, 1961.