550 PROCEEDINGS OF SECTION J. 



The system naturally divides itself into — the drainage of the 

 city — and the disposal of the sewage by a sewage farm. The 

 drainage system technically consists of the main sewer, the street 

 sewers, and the house connections. It must not be forgotten that 

 the leading idea governing the design, is to keep the waters from 

 dwellings and factories separate from the storm water, and to 

 provide suiEcient means of escape for the first only. 



The main sewer runs along the banks of the Torrens for some 

 distance, and is altogether about four miles in length. It is 

 oviform in section, varies in size from forty -two inches by twenty- 

 eight inches, to sixty inches by forty inches, is constructed chiefly 

 of cement, and for about three miles of its course is an open 

 channel. The fall is one in 1000. It is designed to discharge 

 23,000 gallons a minute. 



The street sewers vary in size from forty-two inches to six 

 inches. They consist almost entirely of earthen-glazed pipes, laid 

 at depths of ten feet to fifteen feet. The fall varies, but always 

 sufficient to give a rapid flow. The design is to carry off the 

 sewage of a population of 100,000. Fifty feet apart, ventilating 

 shafts or lamp holes are placed. They rise to the level of the 

 street, and the openings are covered by iron-grids having buckets 

 underneath. (Pis. XXXIV.-XXXVII.? 



The house drains or connections are; chiefly four inches, but may 

 be six inches in diameter. No direct communication exists, as a 

 rule, between any drain and the inside of a dwelling. A water- 

 closet inside a dwelling-house is a rare thing in Adelaide. The 

 refuse-water falls into a trap or receptacle, duly trapped and ven- 

 tilated. All house-drains are ventilated, they all converge to a 

 common drain, which forms the connecting drain with the street 

 sewer. Upon this connecting drain is placed a "disconnector 

 trap," and from its position is more familiarly known as the 

 ''boundary trap," This trap is open towards the house-drains, 

 but closed towards the street sewer ; that is it acts as a ventilator 

 to the house-di-ains, but not towards the street-sewer. 



Just a word on the sewage-farm, or the second main division of 

 the system. It has an area of four hundred and eighty acres, but 

 is found to be too small. It is four miles from the city, and is 

 about one hundred and ten feet below the highest level in the 

 centre of the city, viz.. King William-street. The sewage is passed 

 through two la^'ge self-acting and revolving strainers. The solid part 

 is removed, and the liquid is distributed by irrigation ( n the broad 

 principle over the soil. This is done dui'ing the whole year, but 

 in winter it has to have combined with it the intermittent down- 

 ward filtration method in order to get rid of it effectually. The 

 management shews a profitable return, last year after paying 

 working expenses £1000 stood to credit. 



