Aerially Deposited Lead (ADL)

Elevated lead concentrations exist in soils along older roadways as a result of aerially deposited lead (ADL) from the historical use of leaded gasoline. Caltrans and the Department of Toxic Substances Control (DTSC) have entered into a Soil Management Agreement for Aerially Deposited Lead-Contaminated Soils (Agreement) effective July 1, 2016, that supersedes the prior ADL Variance. The Agreement applies to soils on the state highway system with elevated lead derived from leaded fuel tailpipe emissions. This Agreement includes a Transition Plan for projects that may continue to manage hazardous waste concentrations of lead under the Variance requirements. These projects are identified in Exhibit C of the Agreement.

• Soil Management Agreement for Aerially Deposited Lead-Contaminated Soils 2016 (PDF)
• Revised Exhibit C: Caltrans Project List (PDF)
• ADL Agreement Fact Sheet (PDF)
• DTSC FAQs (PDF)

Disposal Agreement with Local Transportation Partners:
When State highway projects operating under the ADL Agreement affect local roadways, such as at the terminus of on and off ramps, and soil containing 80 mg/kg to 320 mg/kg lead will be reused on the local roadway, Caltrans will enter into a standard disposal agreement with the local roadway owner.