Optimum Use of Erosion Control Blankets and Waste Ballast (Rock) Mulch to Aid Grass Establishment on Steep Slopes

Abstract

The focus of this paper is the optimum use of mulch (biodegradable erosion control blankets and waste ballast) on steep slopes (batters) to aid the establishment of grasses for erosion control. Biodegradable blankets are commonly used on steep slopes as mulch to minimize the risk of washout of soil, seeds, and ameliorants during grass establishment to control erosion. However, the blankets can be costly when laid on all sections of the batters. In order to reduce costs, it is suggested to lay the blankets on critical sections such as the outer verge (top) and the bottom. Waste ballast spread on a railway batter provides a degree of permanent protection against erosion, and is useful where fire is a potential hazard. Runoff and soil loss were monitored on experimental plots of a railway embankment batter between December 2000 and May 2001. The cost-effective erosion control strategies on the plots were centerd on control (doing nothing after surface preparation), limited use of erosion control blankets, and variation of waste ballast density on some seeded plots. It was observed that waste ballast and erosion control blankets laid on the outer verge have the potential to control incipient rills by spreading runoff. Erosion control blankets placed at the bottom section of the embankment have the potential to induce deposition of eroded material. Runoff production and soil loss decreases with an increase in the application density of waste ballast, up to a certain level. Waste ballast spread on railway batters enhances grass germination and sustains grass growth.