Sewage Farm Competition, 187!). 
55 
volume of sewage to be dealt with at the site of the outfall 
works is about 12,000,000 gallons pei" day in dry weather. One- 
fourth, or 3,000,000 gallons per day only, are applied to the land, 
on to which it flows by direct gravitation ; the remaining three- 
fourths, after chemical treatment, are passed into the water- 
courses of the district. At 6 P.M. on the 4th of June last, 10^ 
inches in depth of sewage was flowing over a gauge-dam, 4 feet 
wide, on to the sewage farm, this being at the rate of 6,305,400 
gallons in 24 hours. Again, at 3.30 P.M. on the 11th of 
August, 10 inches in depth of sewage was flowing over the same 
<lam on to the sewage farm, being at the rate of 5,860,400 gallons 
in 24 hours. 
With reference to the preparation of the sewage prior to its 
application to the land, it should be stated that one portion of 
the land, 30 acres in extent, receives the sewage without any 
treatment ; 20 acres receive the sewage after it has had lime 
added to it, but before precipitation in the tanks ; and the 
remaining portion receives the sewage after subsidence has 
taken place in the tanks. It is the clarified effluent from the 
tanks which is used for irrigation. The manager considers 
that, of the two sewaged areas, the one receiving crude sewage 
and the other limed sewage, the one in which the sewage 
has had lime mixed with it answers the best. The mode of 
treatment of the sewage is as follows : — At about a quarter of a 
mile distant from the site of the outfall into a series of tanks, 
lime is added to the sewage as it flows through the sewers. 
This lime is procured from Dudley, in Staffordshire, and is 
ground in water, in an arrangement similar to that of a mortar- 
mill, and the slaked lime flows from the mill direct into the 
sewer. About 14 tons of lime are every day added to the 
sewage as it flows down the outfall sewers. The subsidence- 
works at the outfall of the sewers consist of 19 tanks, or 3 
large roughing-tanks, into which the sewage first flows, which 
average 390 feet in length, 90 feet wide and 5 feet 6 inches deep 
(one of these roughing-tanks having not yet been used) ; and 
there are 16 smaller tanks, each 150 feet long, 50 feet wide 
and 8 feet deep. Each of the large roughing-tanks now in 
use is at present worked for about a fortnight, after which 
period the sewage is diverted into the other while the deposit 
is removed from the former ; but it is intended, as soon as 
the third roughing-tank is brought into operation, to empty 
these tanks weekly, and so relieve the work which has to 
be done by the smaller subsidence-tanks. The flow of the 
sewage is so regulated that each of the secondary subsidence- 
tanks receives about -fgth part of the sewage, and in them 
subsidence takes place. At each end of these subsidence- 
