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Brush Layering

Brush Layerng

What is This Treatment?

Brush layering work includes harvesting green cuttings from existing alder, cottonwood or willow stands and embedding these cuttings in horizontal layers perpendicular to the slope face.

When to Use This Treatment?

  • Best used on fill slopes. This treatment is used to provide erosion protection, increase vegetative cover, and enhance habitat.
  • To use Brush Layering in a stream or channel below the 100-year base flood elevation (as determined by the Engineer) contact the Civil (Hydraulics) Engineer in responsible charge of the stream/channel.

Consider Using With:

Benefits:

  • Provides immediate slope reinforcement from unrooted brush cuttings. As roots develop, slope stability and shear resistance improve.
  • Creates slope breaks that shorten slope length and reduce runoff velocities.
  • Creates vegetative filters for debris.
  • Increases infiltration rates on dry sites.
  • Acts as a horizontal drain on wet sites.
  • Provides for vegetation establishment, cover, and natural recruitment.

Limitations:

  • Nonstandard practice - requires design and approval by a Civil (Geotechnical) Engineer based on site calculations.
  • Requires accessible, local stand of alders, cottonwoods or willows from which to harvest cuttings.
  • Not recommended for rocky slopes, slopes with extremely low soil moisture through the dry season, slopes with no equipment access, or slopes with concentrated flow (i.e., culvert outfall).

Technical Design Tips:

  • Consult your geotechnical and hydraulic engineers for maximum slope angle recommendations.

  • Installation typically proceeds from bottom to top. Fill slope installation is simple, cuttings are placed between successive soil layers.

  • Installation on cut slopes requires digging a ditch or building a bench. As with fills, work proceeds from bottom to top. Excavation for the upper layer is used for filling-in and covering the lower brush layer.

  • May require weeding and supplemental irrigation during the establishment period.

Specification:

Details:

Estimate Information:

Guidance:

  • Caltrans Erosion Control New Technology Report, Brush Layering, June 2003

External Links: