Note 5 — Chapter V · Different Types of Earth Dams.

The term “uniformity coefficient” is used to designate the ratio of the size of the grain which has 60% of the sample finer than itself to the size which has 10% finer than itself. The method of determining the size of sand grains and their uniformity coefficients, is fully explained in Appendix 3 of Mr. Hazen’s book on “The Filtration of Public Water Supplies.”