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23
any new important extensions of trunk mains. The general scheme
of supply was the same as during 1962 but 957 yards of service main
were laid in Paddington during 1963.
SOURCE OF SUPPLY
Hampton Ashford
Chemical Examination Common
Number of samples 52 52
Ammonia nitrogen 0.165 0.22
Albuminoid nitrogen 0.076 0.083
Nitrate nitrogen 3.9 3.9
Chlorides as Chlorine 32 32
Oxygen absorbed from permanganate
(four hours at 27°C.) 1.22 1.26
Turbidity units 0.3 0.2
Colour—Burgess's Tintometer 11 11
Hardness (total) 276 284
Hardness (non-carbonate) 68 66
pH value 7.8 7.9
Phosphate as PO4 1.3 1.3
Silicate as SiO 2 12 12
Sulphate as SO4 60 60
Fluoride as F 0.25 0.25
Magnesium as Mg 5 5
Surface active material as Manoxol 0.08 0.08
Electrical conductivity (micromhos) 560 560
The above figures are given as milligrammes per litre unless
otherwise stated.
Bacteriological Results (after treatment)
Number of samples 1.091 768
Agar plate count per ml. (20—24 hours at
37°C.) 10.6 13.6
Coliform count—per cent. samples negative
in 100 ml 100.0 99.87
E. coli count—per cent. samples
negative in 100 ml. 99.87 99.87
CLEAN AIR ACT, 1956
There were no major "smog" incidents in the year. This is due
no doubt to the absence of appropriate weather conditions, although
the continued decline in the amount of smoke emitted may well
have played an important part, particularly at critical periods.
The decline is due principally to the continued introduction of
Smoke Control areas assisted by the control of new furnaces, the
improvement of existing industrial and commercial heating arrangements
and the reduction in coal-fired locomotives operating from
Paddington Station.
The sulphur dioxide concentration is unchanged. The Clean
Air Act does not offer controls for emissions of this gas, although
indirectly it does make a contribution. In Smoke Control areas the
replacement of coal fires by modern appliances burning smokeless
fuel efficiently means a smaller fuel consumption, which reduces the
SO2 in direct proportion, and if the coal fires are replaced by electric
or gas fires, which emit no SO2, or fires burning light oils, which
emit only minute amounts, the reduction is even greater. Similarly,
improved heating arrangements in commercial and industrial