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PUBLIC WORKS AND UTILITIES
39,000 people. In the low-cost housing programme a total of 15 blocks were completed during the year at Cheung Sha Wan and Wong Tai Sin, providing homes for about 13,100 people, while 36 more blocks were in course of construction at these and two other estates. Construction had also started on the first 20-storey building at a site east of the Wong Tai Sin Monastery.
Drainage. Nearly all built-up areas, including the larger towns in the New Territories, have water-borne sewerage systems. How- ever, as large new blocks of flats take the place of very old and much smaller buildings, the flow to the sewers is steadily in- creasing and many of the older sewers are becoming laden beyond their designed capacity. An accelerated programme to replace them with larger mains is vital to cope with this rapid rate of redevelop- ment of the urban areas accompanied with high population density and a special team of engineers is now engaged on this work. The nuisance from seawall sewer outfalls has grown and extensive plans to build intercepting sewers in the place of the many seawall sewer outfalls will soon bring the sewage to selected sites where it will be treated and discharged into deep water through sub- marine outfalls. Pump houses have been installed in many cases to raise the sewage in the intercepting sewers where the fall is not sufficient for gravity flow. Of the five schemes for the Kowloon peninsula, the Yau Ma Tei scheme is in complete operation and the remaining four are in an advanced stage. Work on three of the five schemes on the Island was started and two of these, the Wan Chai and North Point schemes are in partial operation. Construction of intercepting sewers for Tsuen Wan and Kwai Chung is continuing.
Surface water draining down from the hills through built-up areas used to be led to the sea through large open-trained channels, known locally as nullahs. These nullahs were frequently 10 feet wide or more and were normally located in the centre of the road. With the tremendous increase in both vehicular and foot traffic, such obstructions had to be removed, and during the last 10 years many nullahs have been decked or culverted. Extensive systems of culverts have been constructed at the resettlement estates at Wong Tai Sin, Wang Tau Hom, Kwun Tong, Tsz Wan Shan, Jordan Valley, Tai Wo Hau, Chai Wan and Aberdeen, and in