Grit Chamber Model Tests for Detroit, Michigan Sewage Treatment Project

In designing the grit chambers for the Sewage Treatment Plant, at Detroit, Mich., in 1936, several problems were solved by means of a small-scale model of the tank and large-scale tests of two existing tanks. The small model was used to observe flow distribution and grease removal, and the large-scale tests revealed the percentage removal of sand of various sieve sizes for any given length of tank. This paper presents actual data on the settling of sand in flowing water, under field conditions, in a form which greatly simplifies the computations involved in grit-chamber design. This is not a theoretical approach to the problem of sedimentation in flowing water, but rather a presentation of data in a practical and usable form heretofore not available to the sanitary engineer.