Fly ash erodibility

Gary A. Lehrsch; Dale E. Baker

ABSTRACT:

In the northeastern United States, fly ash is removed from stack gases and commonly trucked to landfills for disposal. The cover soil and especially the underlying fly ash of these landfills are susceptible to erosion by water. Fly ash erodibility was estimated by collecting sediment eroded by natural rainfall in the field from standard erosion plots (1.8 m wide and 22.1 m long on a 9% slope of exposed fly ash). The universal soil loss equation (USLE) was used with direct measurements on-site to obtain estimates of the erodibility factor, K, for fly ash. These estimates were then compared to an estimate obtained using a soil erodibility nomograph. The K factors measured in the field ranged from 0.11 to 0.13 Mg ha h (ha MJ mm)⁻¹ and averaged 0.122 Mg ha h (ha MJ mm)⁻¹ A K factor of 0.122 Mg ha h (ha MJ mm)⁻¹ was recommended for erosion control. With this K factor and the USLE, the surface topography of vegetated fly ash disposal areas was designed to limit soil loss to a tolerance level of 4.5 Mg (ha y)⁻¹. Using the design K factor, erosion from vegetated demonstration plots, 73 m long on a 15% slope, was controlled.

Footnotes

Gary A. Lehrsch, formerly a graduate student in the Department of Agronomy, Pennsylvania State University, is now a soil scientist with the Soil and Water Management Research Unit, Agricultural Research Service, U.S. Department of Agriculture, Kimberly, Idaho 83341. Dale E. Baker is a professor of soil chemistry in the Department of Agronomy, Pennsylvania State University, University Park, 16802. Authorized for publication as Journal Series Paper No. 7636 of the Pennsylvania Agricultural Experiment Station, University Park. The authors thank the Pennsylvania Electric Company for providing financial support for the study and K. C. McGregor and R. L. Cunningham for reviewing the manuscript. Trade names are included for the benefit of the reader and do not imply endorsement of or preference for the product by Pennsylvania State University or the U.S. Department of Agriculture.
Copyright 1989 by the Soil and Water Conservation Society

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