COLOSSAL WORK IN BALTIMORE 



367 



SHEATHING OE A DEEP TRENCH 



sanitary sewerage system throughout the 

 streets and alleys of the entire city, carry- 

 ing connections to each individual house. 

 This public work is being handled on a 

 very broad scale, and is being pushed to 

 completion in a most rapid and business- 

 like manner. 



The city expects to spend about 

 $20,000,000 in disposing of the storm- 

 water drainage and carrying the sewage 

 to great disposal plants, in which the 

 sewage will be brought to a state of puri- 

 fication equal to drinking water before 

 discharging it into the Chesapeake Bay. 

 In carrying out this great project, some 

 of the sewers are of such size as to re- 

 mind you of the ones in Paris. 



In order not to have to purify the 

 storm-water that falls, two systems, one 



for storm-water and *one for sanitary" 

 sewage, are being constructed, amount- 

 ing in all to about 1,100 miles in length. 

 This is some cases causes two large sew- 

 ers of the different systems to come to- 

 gether on the same level, necessitating: 

 the siphoning of one beneath the other. 

 The photograph on page 366 shows one 

 of the largest siphons in the world, con- 

 structed along such unique lines as to 

 have caused wide comment in the engi- 

 neering world. 



The great trouble with siphons is 

 brought about by having to make the 

 siphon large enough to take care of a 

 heavy cloud-burst and still be operative 

 during the summer flow, when there is a 

 mere trickle, causing deposits to accumu- 

 late in the siphon. In this case a battery 



