California Department of Transportation

Caltrans Compost Specifications

According to California Integrated Waste Management (now known as the Department of Resources Recycling and Recovery or CalRecycle), over 12,000,000 tons of compostable materials were landfilled in California in 2003.  Not only does this practice consume valuable landfill space, this disposal of compostable organics misses out on the contribution compost brings to improving soil structure and fertility, improving infiltration, reducing runoff, promoting healthy vegetation, reducing erosion, and improving water quality.

Compost Application Rates

Compost Depth Cubic Yards/Acre Pounds/Acre Tons/Acre
1/64" 2 1,725 0.9
1/32" 4.3 3,450 1.75
1/2" 68.5 54,800 27
1" 135 108,000 54

1/64" compost is the maximim application rate for single step application of compost via a hydroseed rig.

Average Compost Weight = 800 lbs/cubic yard (1050 lbs/cubic meter).

Pneumatic Blower Truck
A 40 cubic yard blower truck holds roughly 35 cubic yards of compost, and applies this compost at an approximate rate of 35 cubic yards/hour. A single truck should be able to apply a 1" thick compost blanket over a 2-acre site (280 CY total) in a single 8-hour working day. The average truck has a hose that can reach 300 feet - this is the typical limit of reach from the roadway. A rough estimate of cost for labor and materials for this work would run from $5,000 - $8,000 per acre. This price estimate does not include seed.

The video below provides additional information about the pneumatic blower truck.

EC08 Watchyourdirt - Express Blower Interview from BlinkWorks on Vimeo.

United States Composting Council (USCC) Seal of Testing Assurance (STA) Program

US Composting Council (USCC) Seal of Testing Assurance (STA) Program Participants
Caltrans compost suppliers must be participants in the United States Composting Council's (USCC) Seal of Testing Assurance (STA) program. The website linked above provides a current list of STA program participants.

For information on how to become a STA program participant, please visit the US Composting Council Seal of Testing Assurance webpage.


Compost Use for Landscape and Environmental Enhancement Manual
The California Integrated Waste Management Board (now known as the Department of Resources Recycling and Recovery or CalRecycle) Landscape and Environmental Enhancement publication provides objective information regarding compost use in landscape plantings and environmental applications.

California Agencies Partner to Increase Compost Use On Roadsides
BioCycle Magazine, March 2007

Compost Use for Erosion Control
Performance in Construction and Roadway Projects
Erosion Control Magazine, May 2006

Studies in Compost
A Closer Look at an an Economical Erosion Control Alternatve
Erosion Control Magazine, April 2005

Infiltration Through Disturbed Urban Soils and Compost-Amended Soil Effects on Runoff Quality and Quantity
Urban Watershed Management Branch, Water Supply and Water Resources Division, U.S. Environmental Protection Agency
The report examines common problems associated with the impact of land development on soils. Land development dramatically alters the natural soil structure, reduces infiltration and groundwater recharge. These changes have dramatic effects on watershed uses. This project measured these changes, identified significant factors reducing infiltration, and evaluated a potential management strategy to reduce these detrimental effects.

Compost and Tillage for Plant Establishment
Researching Roadside Plots in San Jose
Erosion Control Magazine, April 2007

Snowblowers in Summer?
Caltrans Applies Compost Blankets for Roadside Erosion Control
Caltrans News, February 2006

Caltrans BMP Retrofit Pilot Program


Updated Compost related specification information is now located at the following locations: