California Department of Transportation
 

Duff

DUff Illustration

What is This Treatment?

Duff consist of vegetation removed from the project site that is chipped, stockpiled, and then reapplied to disturbed soil areas after completion of earthwork. Duff does NOT include topsoil - other than any topsoil attached to the roots of plants removed by clearing and grubbing operations. Use Local Topsoil to specify the removal, stockpiling and replacement of the organic topsoil layer.

Where to Use This Treatment:

  • Typically applied on slopes 1.5:1 (H:V) and flatter. The following application rates are suggested:
    • 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.

Benefits:

  • Improved protection from raindrop splash erosion.

  • Reduced stormwater runoff volume and velocity.

  • Improved infiltration rate.

  • Conserves soil moisture.
  • Improved soil biology - activity by bacteria, mycorrhizal fungi, nematodes, protozoa, microarthropod and earthworms.

  • Improved soil nutrient levels and nutrient cycling.

  • Improved potential for vigorous long term native vegetation coverage.

Limitations:

  • More costly (yet more effective) than surficial treatments such as Erosion Control (Hydroseed).

  • May increase the cost of earthwork activities.

  • May requires temporary storage space within the project limits to stockpile materials.

  • Requires removal of noxious weed species prior to harvesting of materials from the project site.

  • Requires site accessibility by earthwork equipment.

How to Specify This Treatment on a Project

  • Identify duff collection and placement areas on the plans using callouts, bubbles or tables on quantity plan sheets.

  • Exclude known areas of noxious or invasive weed species from duff collection.

  • Temporary cover of duff stockpiles is likely not required by stormwater regulations as duff stockpiles are primarily chipped plant material, basically a mulch material, and mulch does not require temporary cover.

  • If temporary cover of duff stockpiles is required, the best approach is to simply use Caltrans standard temporary erosion control products and specifications.

Specifications:

Consider Using With:

To effectively treat sites with compacted, nutrient depleted, or poorly draining soils, consider combining this treatment with:

Plans and Details:

Example of how to specify the use of Duff on the project plans:

Incorporate Materials

Estimate Information:

Guidance:

External Links:

  • David Steinfield, Scott Riley, Kim Wilkinson, Thomas D. Landis, Lee Riley, et al. 2007. "Roadside Revegetation, An Integrated Approach to Establishing Native Plants" Accessed 2009-07-16
  • Updated 04-15-2014