California Department of Transportation
 

Compost Sock

Biodegradable Compost Sock

What is This Treatment?

Compost socks consist of tubular netting filled with compost.

Where to Use This Treatment?

Place on erodible slope faces at regular intervals, and at the slope top, toe, and at grade breaks, aligning compost socks with the slope contours.

Biodegradable socks are available in both 8-inch and 12-inch diameters in both cotton (white) and burlap (beige). Both burlap and cotton 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 the Storm Water Quality Handbook - Project Planning and Design Guide (May 2007).

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 for vigorous long term vegetation coverage.

Limitations:

  • Some Regional Water Quality Boards may require compost socks to be setback from a water body 303d listed for nutrients.
  • 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 being placed at the toe of 2:1 (H:V) slopes.

Specifications

Plans and Details:

Estimate Information:

Updated 04-14-2014