incurred in cleaning them out. A number of old nullahs constructed with granite setts were re-inverted and the falls improved. Considerable quantities of the sand which collected in some of the nullahs were removed by the Government Sand Monopoly but in many cases pollution was so severe that the sand proved to be useless for building purposes. The degree of pollution of nullah sand depends largely on the incidence of rainfall and varies considerably from year to year.
77. A bridge was constructed over Tonkin Street nullah to enable Shun Ning Road to be formed to take traffic and thus relieve Castle Peak Road. Bridges were also constructed over Waterloo Road Nullah at three places. Work has commenced on the diversion of Sung Wong Toi Nullah to join the main Kai Tak Nullah.
78. Repairs were carried out to the reinforced concrete of the Wongneichong Nullah by guniting and over 6,000 square feet of surface was treated.
79. A short length of open nullah in Portland Street was inverted, thus removing a big obstruction to traffic and providing a relief route for Nathan Road.
80. A scheme was prepared and partly completed for the conveyance of stormwater through the reclamation at Causeway Bay and works of a similar nature were carried out for the North Point Reclamation.
Sewerage
81. Minor nuisances from foul sewers occurred with greater frequency during the year due, in part, to rebuilding in certain areas of the Central district and the consequent increase in the local density of population. The situation was aggravated both by the severe water supply restrictions which