A COMPARATIVE STUDY OF CIRCULAR AND 
RECTANGULAR IMHOFF TANKS^ 
Theodore Sedgwick Johnson 
Introduction.... 339 
Historical sketch of the development of clarification methods 
Data for design 342 
Locality, Granville, Ohio 
Tributary population 
Character of sewage 
Amount of sewage 
Detention period 
Volume of sedimentation chamber 
Volume of sludge chamber 
Design of tanks 347 
Size of sedimentation and sludge chambers 
Stresses in tank walls 
Rectangular tank, description 
Circular tank, description 
Comparisons and conclusions 358 
Cost 
Sheeting 
Placing reinforcement in floor 
Concreting floors 
Forms for walls 
Reinforcement for walls 
Concrete for walls 
Quantities for rectangular tank 
Reinforcement for rectangular tank 
Quantities for circular tank 
Estimate of cost for rectangular tank 
Estimate of cost for circular tank 
Clarification efficiency 
Bibliography 366 
INTRODUCTION 
No other development of sanitary engineering has taken place 
that has aroused so much interest as the Imhoff, two-story sedi- 
mentation tank. Installed first in the Emscher district in Ger- 
^ Thesis presented to Ohio State University for degree of C.E., June, 1913. 
341 
