XVI. J. DAVIS. 



top liquid flows over a weir situated at and forming the end of 

 the tanks, into an effluent channel which conveys it to filter beds, 

 where it is purified by oxidation and bacterial agencies, and 

 eventually finds its way to the tidal waters as a harmless effluent. 



The solids, on the other hand, are deposited in the tanks as 

 sludge, which is drawn off and reduced to sludge cake by forcing 

 the liquid sludge through filter presses. The cake is then burnt 

 in destructor furnaces. 



Sufficient land was resumed to enable the tanks and other 

 works to be erected (a plan of which is attached hereto). 

 This, with the portion reclaimed for filtration area, amounts to 

 about 13 acres. The reclaimed portion, about eight acres, was 

 filled in with sand to an average depth of about six feet, and 

 formed into eight filter beds. At the southern end of the 

 resumption, and at the outfall end of the main sewer, the 

 treatment works are situated, comfusing the straining chamber, 

 air compressor engine, filter presses, sludge receivers, and lime 

 mixing apparatus. Adjoining the outlet of the sewer and the 

 building are five large open settling tanks, built of concrete with 

 brick lining, of such an aggregate capacity that four will cope 

 with the average daily sewage flow, leaving the fifth as a reserve 

 for an emergency. 



Abutting on the settling tanks, and so placed as to receive 

 the deposited solids from them when required, is a, sludge reservoir, 

 which is a long covered concrete chamber of about 8,100 cubic 

 feet capacity. An open conduit of concrete superposed on the 

 sludge reservoir conveys the sewage to the tanks from the strain- 

 ing chamber in the building. The open effluent channel, also of 

 concrete, conveying the effluent floated off from the tanks, runs 

 round two sides of the latter and then passes along the sides of the 

 filter beds. From this the effluent is distributed through offlet 

 valves, and troughing over each bed as required. Willoughby 

 Falls Creek formerly discharged into the head of the bay, and 

 when this was filled in for the filter beds it was necessary to build 

 a stormwater channel to conduct the stream through the 

 reclamation to the tidal waters. This channel is also available 



