California Department of Transportation

Soil Filled Rock Slope Protection (Nonstandard)

Willow Cuttings Photo

What is This Treatment?

This work consists of placing 1/4 ton Rock Slope Protection (RSP) on slopes, placing plants between the rocks, and backfilling with topsoil. The soil backfill provides for the establishment of shallow rooted plants including annuals, perennials, willow cuttings, grasses or plants that provide erosion control.

Note that placing RSP for slope protection is different than placing RSP for riverbank or shoreline protection. For information regarding using RSP to protect river and shorelines, please see Chapter 870 of the Highway Design Manual.

Soil Filled RSP

Soil Filled RSP Training Video

When to Use This Treatment?


  • Maintains slope stability and prevents surface erosion, even where slopes feature subsurface water flows.
  • Rock Slope Protection meets storm water permit requirements for "cover" but vegetation softens the visual impact of rock slopes, provides habitat, and provides additional long-term control of erosion.
  • Plant roots provide additional biotechnical reinforcement of the slope.


  • Costly.
  • May require additional design time for coordination between landscape architects and geotechnical engineers.
  • Requires space for heavy equipment access.
  • Planting of willows or other deep rooted plants requires placement of biodegradable plant tubes (for roots) at the same time as the rocks are being placed
  • Plant installation may be limited to the rainy season or require supplemental irrigation to effectively establish plants

Consider Using With:

This treatment may also include the following work:


  • 2010 Standard Specifications (See Section 72 Slope Protection)

Plans and Details:

  • No Standard Plans or Details are available as Soil Filled RSP is designed on a project-specific basis.

Estimate Information:

  • No estimate information is available.

Updated 08-21-2015