NOTES ON THE PURIFICATION OF SEWAGE. XIII. 



ordinary domestic sewage, consists of a considerable proportion of 

 trade refuse from breweries, boiling down establishments, etc. 

 After arriving on the northern bank of Cook's River, where all 

 the heavier solids are screened out, it passes under the river 

 by means of an inverted syphon, and is then delivered on to the 

 farm by means of an open carrier. This carrier has various out- 

 lets along the route by means of which it is distributed on to 

 irrigation beds and nitration tanks. 



The heavier solids screened out of the sewage at the screening 

 house have up to the present been grabbed out of the wells and 

 conveyed over a temporary bridge spanning the river on to the 

 farm, and there ploughed into the land, the ultimate result being 

 eminently satisfactory as far as the disposal of sludge is concerned, 

 but the cost of handling to say nothing of the objectionable nature 

 of the work leaves ample room for improvement. As a step in 

 that direction, it is intended to tap the sludge wells and force it 

 across the river by means of a line of cast iron ball and socket 

 submarine pipes, using compressed air for that purpose. This 

 pipe will deliver into a reservoir tank from which it will be taken 

 by carts and distributed on to the beds where required. 



The total area of land over which the sewage from the Southern 

 outfall is distributed amounts to 71 acres, of which 13 J acres are 

 under cultivation, and 57^ acres are used as filter tanks. The 

 whole area is underdrained with the exception of three tanks 

 comprising 25 acres, which are at present being dealt with. Some 

 of these drains are constructed of 6 inch diameter glazed stone- 

 ware pipes, jointed with mortar, consisting of one of cement to 

 five of sand thus rendering it quite porous. Others are constructed 

 of unglazed earthenware pipes well scored on the outer skin with 

 the idea of rendering them more porous, and jointed with cement 

 in a similar manner to the above. The drains are laid at an 

 average depth of about 4 feet, and discharge into Cook's River 

 and Botany Bay. 



As time went on the natural increase of flow proved itself too 

 much for this area to deal with, the rate of filtration being too 



