Gully Intrusion into Reclaimed Slopes: Long-Term Time-Averaged Calculation Procedure

Abstract

Impoundments constructed to encapsulate waste materials must resist the natural erosive processes to prevent exposure and release of the waste. One erosive process that has been difficult to predict is gully intrusion. This study was conducted to analyze the gully erosion processes and determine their effect on long-term embankment erosion and estimate the potential impacts on waste stabilization. A comprehensive procedure has been presented for estimating the magnitude and location of a potential gully intrusion into a soil covered, waste impoundment. The estimation procedure requires that the user obtain information pertaining to the regional hydrology, site soils, proposed impoundment geometry, and design life. Data from 27 field sites and seven laboratory experiments were analyzed to produce three dimensionless equations allowing the user to estimate the maximum depth of gully incision on a sloped surface or embankment as a function of: total volume of runoff, embankment geometry, and clay content of the soil comprising the embankment. It is noted that while a limited set of field data was available for synthesis into the prediction equations, the procedure presented is a first step into the determination of the magnitude and location of gullying into sloped surfaces.