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  6. Erosion Control Toolbox: Compost Sock

Erosion Control Toolbox: Compost Sock

Introduction

Compost sock

Compost socks consist of tubular biodegradable mesh filled with compost.

Where to Use This Treatment

Place on erodible slope faces at regular intervals at grade breaks and at the top and toe of slope. Align compost socks with the slope contours. Biodegradable socks are available in both 8-inch and 12-inch diameters in cotton, jute, sisal, burlap, wood-based yarn, or coir. Biodegradable compost socks will likely function up to 12 months, depending on climate and weather conditions. 8-inch diameter socks work well on slopes up to 2:1 (H:V). 12-inch diameter compost socks are too heavy for the middle of 2:1 slopes, however they work well at the toe. Compost socks are typically spaced as follows:

  • 10 feet apart for slopes steeper than 2:1 (horizontal:vertical)
  • 15 feet apart for slopes from 2:1 to 4:1 (horizontal:vertical)
  • 20 feet apart for slopes from 4:1 to 10:1 (horizontal:vertical)
  • 50 feet apart for slopes flatter than 10:1 (horizontal:vertical)

For additional guidance, contact your District Stormwater Coordinator and refer to the Storm Water Quality Handbook - Project Planning and Design Guide.

Benefits

  • Reduces slope length
  • Reduces stormwater runoff volume and velocity
  • Intercepts runoff and releases it as sheet flow
  • Reduces the amount of sediment in runoff
  • Sock can be slit and removed at the end of the project leaving the compost in place to improve soil quality and provide sustainable vegetation coverage

Limitations

  • Some Regional Water Quality Boards may require compost socks to be set back from a water body per Clean Water Act Section 303(d)
  • Sock must uniformly contact ground surface for maximum effectiveness
  • Difficult to install securely on steep or rocky slopes
  • 12-inch diameter compost socks are limited to placement at the toe of 2:1 (H:V) slopes

Standard Plans and Specifications

  • Caltrans Standard Specifications - Section 21 Erosion Control
  • Use Standard Special Provision 21-1.02Q: Natural fibers are preferred, do not use polypropylene mesh where wildlife may become entrapped
  • Standard Plans for Landscape and Erosion Control
  • Plans Preparation Manual for Erosion Control Examples

Estimate Information

Updated: February 7, 2019