Page:Twentieth Century Impressions of Hongkong, Shanghai, and other Treaty Ports of China.djvu/138

130 period, in addition to performing the purpose for which they were constructed, these channels were turned to account as a means of getting rid of the sullage water from the houses. This state of affairs could evidently not be permitted to go on indefinitely, as the channels were obviously unsuitable for the conveyance of foul liquids, especially during the dry season of the year, when the absence of rainfall caused the nullahs to be practically dry. Consequently, in 1888 an extensive scheme was prepared for the construction of what is now known as the "separate system." This consisted of the laying of stoneware pipes of comparatively small diameter for the reception of foul water, though, of course, rain-water cannot be entirely excluded from them. The work, which extended throughout the whole area of the city, was completed about the year 1895. The sewage is discharged into the waters of the harbour at various points along the city front, generally into deep water, where it is dispersed by the tidal currents, which are of considerable strength. With the continued progress of buildings upwards on the higher levels of the city, the regulation of the various streams was a matter of necessity, to enable the sites which were cut in the hillsides to be properly laid out, and roads giving access to them to be formed, and many channels were constructed with these objects. More recently, however, the importance of training the streams as a preventative of malaria has been recognised, and during the past six years very extensive works have been carried out for this purpose alone. Waterworks.—Prior to the year 1860, the city of Victoria was entirely dependent for its supply of water on wells sunk in the compounds throughout the city and on the streams flowing down the slopes of the range of hills at the base of which the city is situated. These sources, besides being of a precarious nature, very soon proved inadequate, and in the year already mentioned steps were taken to supplement them by intercepting the waters of a stream on the opposite, or southern, side of the range and bringing them into the city in cast-iron pipes. The works, as carried out, comprised a small dam in the Pokfolum Valley impounding 2,000,000 gallons, a cast-iron main 10 inches in diameter and 3¼ miles in length, two tanks or service reservoirs above the city of a combined capacity of fully 1,000,000 gallons, and a number of fountains and fire-cocks. They were completed in 1863, but were speedily found insufficient to meet requirements, and in 1866 the construction of a dam in the Pokfolum Valley with a capacity of 66,000,000 gallons was undertaken. This was completed in 1871.

With the growth of the city which, perforce, continued upwards owing to the flat area at the base of the hills being soon covered, a difficulty arose in supplying water to the buildings on the higher levels. To overcome this, a conduit was constructed from the outlet of the Pokfolum reservoir contouring the hills at a height of about 500 feet above sea-level and terminating at a point above the central part of the city. It was 3⅓ miles long and had a discharging capacity of nearly 1,750,000 gallons per day. The original cast-iron main which was thus superseded was taken up on completion of the work, which occurred in 1877.

The growth of the population and the increasing demand for water for industrial purposes soon rendered it necessary to augment the supply, and in 1883 the Tytam scheme was undertaken. The works comprised under it were, relatively to the Pokfolum works, of great magnitude. They included a storage reservoir with a capacity of 312,000,000 gallons, a tunnel and aqueduct, 1·38 and 2·93 miles in length respectively, for conveying the water to the city, a series of filter-beds and a service reservoir capable of containing nearly 5,750,000 gallons. The cost of these works amounted to $1,257,500, and they were completed in 1889.

To place the Pokfolum supply on an equal footing with that derived from Tytam, filter-beds and a service reservoir (capacity 941,000 gallons) were next constructed, and attention was then turned to the question of distributing the greatly augmented supply throughout the city. For this purpose fully 20 miles of cast-iron mains, varying from 14 inches to 3 inches in diameter, were laid during the years 1890–92; a system of hydrants being provided at the same time for fire-extinction purposes. Owing to the great variation in the levels of the city, which extended from sea-level to about 500 feet above it, the distribution system was divided into three zones, the excess pressure of the supply for the lowest zone being utilized for pumping water to the highest zone, whilst the middle zone was supplied direct from the service reservoirs. About the same time as the distribution works just described were being carried out, a scheme for extending the supply of water to the Hill District, which ranges from about 900 to 1,800 feet above sea-level, was undertaken. The scheme included the provision of a pumping engine, a rising main of heavy wrought-iron piping, nearly a mile in length, 5⅓ miles of distributing mains, and a series of tanks for controlling the pressure and ensuring uniformity of supply. On the completion of the distributing system in the city the wells were closed, as they were all more or less contaminated or liable to contamination.