Water and Wastewater Terms Beginning U

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uniformity coefficient (UC)

A measure of the degree of uniformity in a granular material such as filter media. The measure is the ratio of the diameter of a grain (particle) of a size that is barely too large to pass through a sieve that allows 60 percent of the material (by weight) to pass through to the diameter of a grain (particle) of a size that is barely too large to pass through a sieve that allows 10 percent of the material (by weight) to pass through.

uniformity coefficient = (particle diameter_60%) / (particle diameter_10%)