1890-91.] A CONSIDERATION OF SEWERAGE SCHEMES. 145 



thousand tons of sewer sludge to the channel can be as readily accom- 

 plished. 



While it is thus clear that in the case of the metropolis the conveyance 

 of the sludge to the sea is the only available remedy, it by no means 

 follows that under other circumstances, and where local conditions are 

 favorable other systems are undesirable. Each case must be dealt with 

 on its own merits, and according to local requirements. 



I believe it was at one time the intention of the City Engineer to 

 recommend a somewhat similar scheme for the City of Toronto, for a 

 temporary relief, but no doubt the winter season here would interfere 

 with such a scheme. 



Reverting once more to the schedule we learn the average amount of 

 sewage per head daily in these forty towns. It amounts to a trifle less 

 than forty gallons per day. This is of importance, and will be referred 

 to later on, as the size of the sewers should be proportioned to the 

 amount of sewage they are intended to convey. 



Under the head of chemicals used, the prevailing materials are lime 

 and sulphate of alumina or alumino ferric. They are found to produce 

 the best results when used in the proportion of 7 grains of the former to 

 5 of the latter per gallon. The lime is usually applied in the form of 

 milk-of-lime, but better results are produced by using the lime in solution. 

 Great care must be taken to apply just the proper quantity, and have it 

 properly mixed. Machinery more or less complicated is used for this 

 purpose, which it would be quite out of place to attempt to describe in a 

 paper of this nature. 



Under the head of acreage I find that on an average one acre of land 

 is required for about 125 persons where sewage farms are established. 

 Thus for Toronto would be required about 1,600 acres, and of course a 

 corresponding increase would be required as the population increased. 

 But even this is considered a low estimate. In Germany 100, and even 

 as low as 75 persons to the acre is recommended. It is admitted by 

 persons in charge of sewage works that the longer land is used for sewage 

 disposal the more it becomes clogged, and the number per acre requires 

 to be reduced. 



Comparatively full descriptions of the sewage works of a number of 

 towns and cities of England are given in Mr. Crimp's book, among which 

 are the following : Doncaster, Croydon, Bedford, Dewsbury, Merton^ 

 Swan wick, Chiswick, Kingston-on-Thames, Sal ford, Bradford, Sheffield, 

 Barnet, Coventry, Newhaven, Birmingham, and Dortmund, Germany. 

 In order to arrive at an intelligent view of the case, and to be enabled 

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