Development of Best Management Practices for Turbidity Control During Rainfall Events at Highway Construction Sites Using Polyacrylamide

On Arkansas State Highway and Transportation Department (ASHTD) construction projects, topsoil is gradually washed away by irrigation runoff. Over time, massive quantities of soil can be stripped from fields and carried into runoff water. Federal, state and local water quality regulations prohibit the discharge of turbid water from construction activities into adjacent water bodies and require departments of transportation (DOTs) to use approved Best Management Practices (BMPs). One of the BMPs available the AHTD is considering is the use of Polyacrylamide (PAM), a synthetic water-soluble polymer composed of molecules of acrylamide. PAM binds soil particles together, causing them to settle out and not be carried away in runoff water. This prevents soil loss and can improve water infiltration. PAM is not harmful to the environment, and is proven to degrade safely into harmless organic molecules over the course of several weeks after application. In 2009, the Environmental Protection Agency (EPA) issued a numeric turbidity unit of 280 nephelometric turbidity units (NTU) for stormwater runoff from regulated turbidity of runoff water from highway construction sites to a maximum of 280 nephelometric turbidity units (NTU). Although the EPA has since agreed to propose the withdrawal of the numeric limit, final action on the proposal is not anticipated until February 2014. Even if this action stands, EPA still proposes to impose non-numeric requirements intended to reduce the amount of turbidity leaving construction sites. Without treatment, turbidity levels of these runoff waters can exceed 15,000 NTU due to soil erosion from heavy rainfall events. While addition of polyacrylamide (PAM) to soils at construction sites has proven effective at reducing turbidity of runoff waters, no BMPs have been developed to meet the EPA regulation, including selection of the type of PAM and the application method and rate based on construction site properties (e.g., soil type, slope, rainfall duration and intensity). Research is needed to develop and/or refine BMPs using PAM on AHTD construction projects. Under the expected final permit, there will be no numerical turbidity standard, just a requirement to reduce turbidity to the maximum extent practical.

    Language

    • English

    Project

    • Status: Active
    • Funding: $156193.00
    • Contract Numbers:

      TRC-1403

    • Sponsor Organizations:

      Arkansas State Highway and Transportation Department

      System Information and Research Division, P.O. Box 2261
      Little Rock, AR  United States  72203
    • Project Managers:

      Snow, Melana

    • Performing Organizations:

      University of Arkansas

      Department of Civil Engineering
      4190 Bell Engineering
      Fayetteville, AR  United States  72701
    • Principal Investigators:

      Fairey, Julian

    • Start Date: 20130701
    • Expected Completion Date: 0
    • Actual Completion Date: 20150630
    • Source Data: RiP Project 37425

    Subject/Index Terms

    Filing Info

    • Accession Number: 01542981
    • Record Type: Research project
    • Source Agency: Arkansas State Highway and Transportation Department
    • Contract Numbers: TRC-1403
    • Files: RiP
    • Created Date: Nov 1 2014 1:41AM