Swale Design Optimization for Enhanced Application and Pollutant Removal

Swales are the most prevalent stormwater conveyance - and therefore potential treatment device - within North Carolina Department of Transportation's (NCDOT’s) linear right-of-way. To date, swale performance with respect to hydrologic change and pollutant retention has been assumed to be modest; however, initial NCDOT-funded research on hydrologic condition (wetland versus upland) and check dam presence has yielded basic results that lead to some potential design improvements. To date, a comprehensive and systematic research program of post-construction swale performance has yet to be conducted. Because swales are such a common practice, small but defined design improvements could yield substantial improvements in runoff quality and quantity released to receiving waters. The purpose of this proposal is to test multiple design parameters in controlled plots and field settings. Moreover, field testing would occur in two physiographic regions (Piedmont and Coastal Plain). NCSU’s Sediment and Erosion Control Research and Education Facility (SECREF) will be the location of the plot tests. Multiple swale design parameters are planned to be tested in this controlled setting, including: channel slope, vegetation height (or type), end-of-swale treatment and hydraulic loading ratio. NC DOT-directed variables may be added or substituted, if requested. The field tests are located in both the RTP (exact location TBD, but perhaps NC 147 in Southern Durham County) and Wilmington (Shipyard Blvd.). In addition to underlying soil type variation, the field tests will examine bioswale hydraulic loading ratio. NCSU faculty, staff and students will conduct the following tasks as part of this proposal: (1) Design, construction and instrumentation of controlled research plots at SECREF, (2) Design and implementation of the monitoring plan for the two field sites, (3) Data collection, (4) Analysis and reporting of final data, (5) Development of design and management tools, and (6) Delivery of information to NC DOT personnel (& designees) via an end-of-project workshop. Deliverables provided in addition to the workshop include a final report to NCDOT and a companion Microsoft Excel-based design tool to assess the performance of multiple swale design options. By better understanding and predicting swale performance, and its various design configurations, NC DOT will be able to more efficiently manage runoff within its unique linear environment.


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    • Status: Completed
    • Funding: $299428
    • Sponsor Organizations:

      North Carolina Department of Transportation

      Research and Development
      1549 Mail Service Center
      Raleigh, NC  United States  27699-1549
    • Project Managers:

      Kirby, John

    • Performing Organizations:

      North Carolina State University, Raleigh

      College of Agriculture and Life Sciences
      Department of Soil Sciences, Campus Box 7619
      Raleigh, NC  United States  27695-7619
    • Principal Investigators:

      Hunt, III, William

    • Start Date: 20150816
    • Expected Completion Date: 20180815
    • Actual Completion Date: 0

    Subject/Index Terms

    Filing Info

    • Accession Number: 01573242
    • Record Type: Research project
    • Source Agency: North Carolina Department of Transportation
    • Files: RIP, STATEDOT
    • Created Date: Aug 18 2015 2:00PM