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30
The state of the water of the river is of great concern to the Council and a weekly
examination of it is therefore made at 25 points between Teddington Weir and the
sludge dumping area in the estuary. In addition, the water off the two outfall works is
sampled daily at both high and low tide.
An important factor in determining the pollution load with which the water of a
river will deal satisfactorily is the fresh water flow; in the case of the River Thames,
this is the amount coming over Teddington Weir after the Metropolitan Water Board
has, above that point, abstracted the quantity required for water supply. By Statute, no
abstraction is permitted which will have the effect of reducing the flow over the Weir
to below 170 million gallons per day, although the appropriate Minister can, by Order,
permit the reduction of the flow to as low as 50 million gallons per day. The rainfall in
the summer of 1952 was rather below average and hence the average fresh water flow
over Teddington Weir was also rather below average. It was, indeed, considerably less
than that for 1951, though much greater than that in the dry year 1949. In the summer
months of 1952 the condition of the water of the river became extremely poor and was
bad over a considerable stretch of its course for several weeks, particularly between
London Bridge and Gravesend, with a complete absence of dissolved oxygen and the
development of sulphide (with its characteristic odour).
There are now two Government Committees considering and investigating the
condition of the River Thames; the Thames Survey Committee of the Department of
Scientific and Industrial Research set up at the request of the Port of London Authority
in June, 1949, and the Heated and Other Effluents Committee of the Ministry of Housing
and Local Government set up early in 1951 with wider terms of reference. The Chemistin-Chief
is a member of both these Committees.
Close liaison was maintained with other research work, both in this country and in
the United States, on the problems of sewage treatment and river sanitation.
The laboratories at the two outfall works carried out the chemical analyses necessary
for the control of the various plants during the year. Research work was also done on
several aspects of the sewage treatment problem and particularly in reference to the
de watering of sludge by a new process involving freezing after the addition of chemicals;
the pilot plant for dealing with one ton of sludge came into operation early in the year
and research on the filtration of the material produced proceeded satisfactorily.
The question of trade discharges into sewers was investigated in a number of cases
as to compliance with the appropriate sections of the Public Health (London) Act, 1936.
Attention was also directed to the ventilation of sewers and, in view of certain complaints
of emanations, a joint working group of officers of the Council and of the Metropolitan
Boroughs' Standing Joint Committee was set up to investigate the problem. It was
decided that the increase in trade wastes was an important factor and that it was desirable
to initiate legislation in order to obtain more effective control. The Chemist-in-Chief
was a member of this Working Group.
Safety lamps used in sewers were tested and adjusted periodically and an officer of
the Chemical Branch gave advice and assistance in training men employed on sewerage
work in the use of oxygen breathing apparatus under emergency conditions.
The sewage treatment service is a joint function of the Chief Engineer's and Public
Health Departments and special mention should be made of the cordial relations which
have so greatly helped in maintaining the efficiency of the operations. Weekly conferences
of the Divisional Engineer (Main Drainage) and the Chemist-in-Chief and their senior
officers have been of the utmost value in this respect.
Housing
The work done by the Chemical Branch for this service covered a very wide field.
The largest section was on paints and other decorative finishes, the economic aspect of
which has already been mentioned. The Interdepartmental Paint Committee and SubCommittee
held periodical meetings during the year and progress was made with the
completion of 'approved lists' of brands of paint which must be used on work for the
Council whether by direct labour or by contractors. Lists were compiled for hard-gloss
paint (both interior and exterior), flat oil paint, semi-gloss paint, emulsion paint,