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10
The working of the tanks and original filters have been
altered and improved, and three Contact Beds have been
constructed under the supervision of Mr. E. J. Reynolds,
Assoc. M. Inst. C.E., further additions are contemplated as
mentioned below.
The method of treatment is as follows:—
The sewage, which enters the works by gravitation, is
first passed through a revolving screen, after which a
solution of Buxton lime equal to 4 grains per gallon is
added, and the whole is thoroughly mixed, It then receives
aluminoferrie to the extent of one grain per gallon, and is
again well mixed by passing through a salmon ladder, and
in this condition flows into settling tanks, of which there
are four, each having a capacity of 70,000 gallons. These
tanks are divided by concrete walls, on which is an open
channel divided by sluice doors, so that either one, two,
three, or four tanks can be worked at a time and alternately
as required. The overflow from the tanks first passes out
of the tanks into an open channel, then on to first Contact
Beds and through the filter or second Bacteria Beds into an
effluent chamber, and thence into the brook referred to above.
A Wrought Iron fence has been fixed along the Southeast
and East side of the Sewage Works, from Alexandra
Road to the G.N. Railway Co's land on the North. This
fence also enclosed 7¼ acres added to the Works in 1906.
A large quantity of oak fencing replaced by iron fencing
has been utilised for fencing in proposed additional and
present allotments land from the Sewage Works. The
Council have had under consideration during the past year,
the construction of additional Sewage Filters and another
Settling Tank. Plans and estimates have been prepared,
and application has been made to the Local Government
Board for sanction to borrow the necessary money to construct
two filter beds and one additional settling tank.
Trough distributors have been fixed in order to distribute
the sewage more uniformly over the whole area of
the storm water filters. This has resulted in a marked
improvement in the working of the beds.
The rainfall during the whole of 1907 was very heavy
and continuous, there being no opportunity to rest the beds.