Erosion Control Toolbox: Contour Grading and Slope Rounding
Introduction
Contour grading and slope rounding involves grading with smooth, flowing contours that help integrate highway improvement with the surrounding environment. Concentrated water flows in graded valleys help sustain vegetation in arid regions.
This grading technique reduces erosion and maintains water quality by breaking the slope into smaller tributary areas that disperse runoff. Due to higher moisture content, these focused drainage areas support larger trees and shrubs than the planar slopes produced by rectilinear grading.
Landform Grading/Contour Grading Training Video
Click here to watch a short video about Landform Grading
When to Use This Treatment
- Consider using contour grading and slope rounding whenever permitted by right of way limits
- Typically used on cut slopes 2:1 and 3:1 (H:V) composed of rippable material. For specific maximum slope gradients, consult your geotechnical engineer
Consider Using With
Benefits
- Reduced stormwater runoff volume and velocity
- Improved infiltration rate
- Improved soil water holding capacity within sculpted valleys
- Improved potential for vigorous long term vegetation coverage
- Topographic diversity supports a wider range of plant material
- Reduces irrigation requirements by providing sheltered areas that can support trees and shrubs with higher moisture requirements
- Provides visual compatibility between highway facilities and their surrounding environment
Limitations
- May increase the cost of earthwork activities
- Requires site accessibility by earthwork equipment
Specifications
- Refer to Standard Specifications - Section 19 Earthwork
References
Updated: December 6, 2018