California Department of Transportation

Decompact Soil Surface

Decompact Soil Surface

What is This Treatment?

This work involves the loosening of compacted soils. Decompaction is typically performed by two methods:

  • Via bulldozer-drawn winged subsoiller as seen in the top left-hand photo above. The bulldozer drawn winged subsoiler takes advantage of equipment commonly used to decompact soils for agriculture.
  • Via tracked excavator equipped with a subsoiling grapple rake or subsoiling excavator bucket as seen in the right-hand photo above. Unlike bulldozer-drawn tilling, the subsoiling grapple rake raises the soil surface slightly and leaving only a small furrow on the surface. The grapple rake leaves the nutrient-rich surface layer largely intact, while allowing water, microscopic fungus and native plant roots to penetrate more deeply.

When to Use This Treatment:

  • Use on cut and fill slopes 3:1 and flatter. For specific maximum slope gradients, consult your geotechnical engineer.

  • Use in flat areas where soils are highly compacted and require tilling to restore infiltration and water holding capacity.


  • 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 potential for vigorous long term vegetation coverage.


  • Nonstandard specification which requires approval from the Division of Construction.
  • More costly (yet more effective) than surficial treatments such as Erosion Control (Hydroseed).

  • May increase the cost of earthwork activities.

  • Requires site accessibility by earthwork equipment.

  • Not practical for shallow rocky soils.


Plans and Details:

  • There is no Standard Plan for Decompact Soil Surface.

Estimate Information:

  • There is no estimate information available for Decompact Soil Surface.
  • There is no BEEs code for Decompact Soil Surface.


External Links:

Updated: April 14, 2015