11.80 Fluoridation of supplies, started in 1971 to reduce dental decay in children, continued. The average level achieved during the year was 0.8 p.p.m. fluoride against a nominal target of 1.0 p.p.m.
11.81 The standard of bacteriological quality aimed at throughout the distribution system is absence of coliform organisms in 100 millilitres of sample. All 2,817 samples taken regularly from service reservoirs conformed to this standard as did all 2,085 random samples taken from taps connected directly to water mains. Of 1,167 samples from taps fed via private storage tanks 97.9% were free from coliform organisms.
Plover Cove
11.82 Regular chemical, limnological and biological surveys continued in Plover Cove Reservoir where summer inflows reduced the salinity from 260 p.p.m. (NaCl) in May to 150 p.p.m. by November, the total of all dissolved salts being then 220 p.p.m. The general quality of the stored water remained good but an unusual earthy-musty taste and odour persisted for about 3 weeks during November when dosing of powdered activated carbon before filtration was necessary at Sha Tin treatment works, to maintain palatability. There was no further fish stocking but a research student from Hong Kong University began a study of the naturally occurring species of Tilapia which is thought likely to assume the functions of biological control hitherto performed by the stocked species of carp.
CONSULTANTS LIAISON UNIT
Senior Engineer:
N. T. WHITWORTH, B.Sc.Tech., C.Eng., M.I.C.E., M.I.Mun.E., M.I.W.E.
Y. AU-YOUNG, B.Sc. (C.E.), C.Eng., M.I.C.E., M.I.W.E., M.A.S.C.E.
General
11.83 The unit is responsible for liaising with the Consulting Engineers engaged on water supply schemes, other than desalting. Expenditure during the year amounted to over $228 million.
High Island Water Scheme
11.84 Work continued on the High Island scheme contracts substantially on programme. The major contract for the construction of the main dams and ancillary works for the 60,000 million gallons
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