California Department of Transportation

Imported Topsoil


What is This Treatment?

Imported topsoil is topsoil obtained from outside the project limits. Imported topsoil is typically used for highway planting projects rather than for erosion control work.

Where 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 products 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.
  • Typically used for Highway Planting projects. Consider using Local Topsoil for erosion control work.


  • Reduced stormwater runoff volume and velocity.
  • Improved infiltration rate.

  • Improved soil water holding capacity.

  • Improved soil structural properties - soil structure, porosity, and texture.

  • Improved plant rooting depth.

  • Improved soil chemical properties - providing proper pH, carbon, nitrogen, potassium and phosphorus levels.

  • Improved soil nutrient levels and nutrient cycling.

  • Improved potential for vigorous long term vegetation coverage.


  • More costly (yet more 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 = 140 cubic yards/acre.
  • 3” depth = 420 cubic yards/acre.
  • 6" depth = 840 cubic yards/acre.


Plans and Details:

  • There is no Standard Plan required for Topsoil.

Estimate Information:

Updated 04-15-2014