COMMUNITY SANITATION 



421 



After carefully studying the problem, Cleveland built 

 a new intake tunnel extending five miles into the lake. 

 As soon as it was opened the doctors noticed a change 

 for the better in the typhoid situation, and in a short 

 time the water was considered by all as comparatively safe. 

 It is quite common for cities to pour their sewage into 

 near-by waters. New York City pours its sewage into the 



FIG. 372. A Sewage Disposal Plant. 

 The Imhoff tanks, Columbus, Ohio. 



harbor, Chicago into the Illinois River through the 

 Chicago Drainage canal, Cleveland into Lake Erie. 

 In many inland cities the problem of sewage disposal 

 has been solved by the installation of sewage disposal 

 plants. They have proved so satisfactory that their use 

 undoubtedly will be greatly extended. Such plants 

 purify the sewage by oxidation and by the aid of friendly 



