The concrete should contain no stone larger than three-quarter* of an inch in any 

 dimension and the material should be carefully graded so that all voids will be well filled. 

 Good concrete is the cheapest and best waterproofing. It has been demonstrated that a 

 properly proportioned and properly mixed concrete may be made practically waterproof. 

 It is nevertheless advisable to take every precaution possible. The concrete should be 

 thoroughly mixed to a wet consistency and well tamped. Any good waterproofing com- 

 pound which may be obtained in the market should be mixed with the concrete. The in- 

 side of the tank should be plastered- with cement mortar or grouted with neat cement. 



Water- 

 proofing. 





FIGURE 38. 



If a tank is required to be elevated as on a roof or water tower, the walls may be 

 designed with the use of the tables, as given herewith. The floor, however, becomes a 

 Special design and here the services of an engineer should be sought. 



If a tank is to be sunk in the ground, the tables herewith given may be used to aid in 

 the design. The external earth pressure counteracts the internal pressure and serves to five 



Types 

 of Tanks. 



ut 



