The purpose of this study was to determine the relations of permeability to particle size and particle size distribution of sands and gravels. Permeability was determined for homogeneous samples (one grade size of Wentworth classification system) and heterogeneous samples (mixtures of two or more of the homogeneous samples, generally in equal amounts by weight). A constant-head permeameter was used.

The results show that (1) the time for a permeameter sample to reach full saturation is directly proportional to the effective size; (2) the permeability of homogeneous sands is equal to the 1.76th power of the effective size multiplied
by 11,279.

k = 11,279 D₁₀^1.76

The permeability of heterogeneous sands falls fairly close to this equation. A field worker may be able to establish roughly the value of permeability based on approximate mechanical analysis; (3) the permeability of homogeneous sands is proportional to the 1.93rd power of the median diameter multiplied by 9,034.

k = 9,034 Md^1.93

The permeability of heterogeneous sands does not fall close to this equation; (4) the permeability of heterogeneous mixtures of sands and (or) gravels is controlled by the permeability of the finest sand in the mixture; (5) no simple relations of permeability to uniformity coefficient, sorting coefficient, and porosity could be determined.