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sewage flows into the septic tanks, the flow through these
tanks being varied as required by the conditions arising from
time to time. The scum on the septic tanks is held back by
"scum boards." The septic liquid is then taken through
"equalising channels" to the various filters. There are four
"primary" and four "secondary" filters; two of the latter
are rectangular. The sewage is distributed on to the circular
filters by revolving sprays, and on to the rectangular beds by
fixed distributors, designed by the Council's Engineer.
Measures have also been taken by means of special
hydraulic tanks to intercept the solids in suspension both
between the septic tanks and filters, and between the primary
and secondary filters.
6 of the percolating filters are circular, 69 feet in
diameter and 5 feet deep. 2 of the percolating filters are
below ground level, rectangular, 5 feet deep, with open
jointed herring-bone pipes for taking off the effluent and for
ventilation.
The sludge from the tanks is collected in a sludge well,
discharged thence by automatic ejectors (actuated by air
pressure) upon the higher part of the farm, there dried in
small lagoons, and afterwards ploughed into the land.
The whole of the new works have been designed and
carried out by the Council's Engineer and Surveyor, C. J.
Jenkin, M.I.C.E.
The working of the installation is tested by frequent
analyses of the effluent, and during the year 17 samples were
analysed.
Chemically the effluent is a good one: the nitrates are
usually high, and very stable. The amount of solids in suspension
is, however, frequently in excess of the standard laid
down by the Royal Commission, and the Council are considering
the best methods of improving the effluent in this respect.
On account of the rapid development of the district, the
amount of sewage to be dealt with is an ever-increasing one,
and the Council are now completing arrangements for the