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8
In the Annual Report for 1903, some facts as to the general conditions
of the district were given, in accordance with a suggestion made by the Local
Government Board. As that Report can easily be referred to, it is not
necessary to repeat them here, but two important matters must be mentioned.
During the year the conversion of the method of sewage disposal has been
completed, and the new system has been working for more than half of it.
No alteration has been made in the method of collecting the sewage at the
works, which was briefly described in last year's report. It may, however,
be of interest to add that the engines for compressing air are four in number,
tavo of 50 horse-power each being in constant use, and two, each of 25 horsepower,
being in reserve for emergencies. These engines supply air to the
seven Shone's ejectors used for raising the sewage from the lower level mains.
The total amount of sewage to be dealt with amounts to an average flow
every 24 hours of about a million and a half gallons. There are five tanks
for the bacteriological treatment of this sewage, two being of a capacity of
450,000 gallons, and three of 300,000 gallons each, though the actual capacity
of each tank is diminished by the space taken up by the arched supports for
the roofs, The filtering of the effluent from these tanks is, carried out on
the single contact system by 14 filter beds, each of an average area of about
1000 square yards. At present four of these filters are worked automatically
and the remainder are hand controlled. The material used for filtering is
coke breeze and clinker, and the average depth of it is rather more than
three feet.
The effluent was passed through these filters for the first time about
the middle of May, when 11 were in use, and by the end of March all of
them were working, The final effluent obtained from the filters was fairly
good from the first, and there has been an improvement in it as experience
has been gained. It is far too soon to criticise the new system, to assume
its complete success, or to call attention to faults or defects. Many months
of observation and practical experience will be required before its full benefits
can be obtained, but even in the few months it has been in use prove its
superiority to the old method of chemical precipitation.
The Destructor which was under consideration last year, was finally
decided on and its erection commenced. It is expected that it will be in
use about the end of April, 1905, and that it will be capable of disposing
of at least 30 tons of refuse daily.