Remediation of Areas Treated with Residual Herbicides

Focus Area

Construction and Maintenance Practices


Environmental Process, Natural Resources






1-2 years

Research Idea Scope

I. Research Problem Statement
For years non-selective, residual herbicides were used to keep the roadsides at the edge of the pavement free of vegetation. These areas, sometime referred to as Zone 1, ranged in width from 2 to 10 feet or more. Due to increased concerns about herbicides in the environment and increased costs, these areas are being significantly narrowed or eliminated. Because of the long term use of residual herbicides it has been difficult to establish desirable vegetation in these areas. This problem may be more difficult in areas with drier climates. Designers and maintenance personnel will be able to use the results of this research to restore abandoned Zone 1 areas with desirable plant communities, reduce long-term maintenance costs, and reduce pesticide use.

II. Research Objective
Determine what types of remediation are necessary to establish native or desirable plant communities in areas where residual herbicides were used. This would include:
Determine if the climate makes a difference in residual herbicide breakdown.
Determining what types of remediation can be used to breakdown or neutralized remaining herbicides in the soil, such as soil amendments, addition of soil microorganisms, cover crops, etc.
Determine what types of plants are best suited to re-colonize these areas.
Determine if plant succession methodologies (adaptive management) can, or should be, used to establish desirable plant communities.

Urgency and Payoff

Invasive weeds cause billions of dollars in losses in the United States alone each year. In addition, Executive Order 13112 directs FHWA and transportation departments to eliminate weeds on public rights-of-way. Roadsides and transportation corridors are one of the primary ways that seeds move around the country. Without residual herbicide, the bare soil on the edge of the shoulder becomes a wonderful seedbed for many invasive species. Determining the best ways to quickly get desirable plant species growing on these bare soils will go far in helping to stop the spread of invasive species. The methods this research may uncover could lead to guidelines that precipitate changes in design manuals, construction methods, and maintenance activities.

Suggested By

TRB Research Needs Conference, AFB40, Landscape and Environmental Design