Erosion Control Toolbox: Imported Soil

Introduction

Imported soil

Photo Showing Use of Imported Topsoil: Imported topsoil is obtained from outside the project limits and is typically used for highway planting projects as opposed to erosion control work.

When to Use This Treatment

Use to provide topsoil as a growth medium on slopes 1.5:1 (H:V) and flatter. To minimize slumping during heavy rain events, the following application rates are suggested where topsoil will not be secured by additional treatments such as cellular confinement or turf reinforcing mat:

  • Slopes 1.5:1 (H:V) - 2" maximum thickness
  • Slopes 2:1 (H:V) - 3" maximum thickness
  • Slopes 3:1 (H:V) - 4" maximum thickness
  • Slopes ≤ 4:1 (H:V) - 6" maximum thickness

Consider using Local Topsoil for erosion control work.

Benefits

  • Reduced stormwater runoff volume and velocity
  • Improved infiltration rate
  • Improved soil water holding capacity
  • Improved soil structure, porosity and texture
  • Improved plant rooting depth
  • Improved soil chemical properties - provides proper pH, carbon, nitrogen, potassium and phosphorus levels
  • Improved soil nutrient levels and nutrient cycling
  • Improved potential for vigorous long term vegetation coverage

Limitations

  • More costly and effective than surficial treatments such as Erosion Control (Hydroseed)
  • Requires temporary storage space within the project limits to stockpile materials
  • Requires site accessibility by earthwork equipment

Technical Information

  • 1” depth = 134 cubic yards/acre
  • 3” depth = 402 cubic yards/acre
  • 6" depth = 804 cubic yards/acre

Standard Specifications

  • Standard Specifications - Section 21 Erosion control
  • Estimate Information

    • Use Bid Item Code 210110 Imported Topsoil for payment by cubic yard
    • Use Bid Item Code 210111 Imported Topsoil for payment by ton

    Updated: January 22, 2019