Designing and Evaluating Infiltration Swales for Retaining and Infiltrating Roadway Stormwater Runoff

Details

• Creators:
  Austin, Parker J. ; Florez, Diego A. Ramirez ; Ji, Yuting ; Perez, Michael A. ; Fang, Xing ; Donald, Wesley N.
• Corporate Creators:
  Auburn University. Highway Research Center
• Corporate Contributors:
  Alabama. Department of Transportation
• Subject/TRT Terms:
  Data Collection Design Drainage Structures Green Infrastructure Hydrology Infiltration Infrastructure Moisture Content Performance Evaluations Roads Runoff Soil Deposits Stormwater Swales

  More +
• Publication/ Report Number:
  931-072
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States
• Corporate Publisher:
  Auburn University. Highway Research Center
• Abstract:
  The Alabama Department of Transportation (ALDOT) employs infiltration swales, linear vegetated channels with engineered soil media, as a green infrastructure stormwater control measure along roadsides to reduce runoff discharge. This study evaluated the performance of infiltration swales and their media through laboratory experiments, field testing, and hydrologic modeling. Laboratory testing using 6-in. columns and falling-/constant-head tests guided material performance characterization. Two 40-ft long swales (ALDOT and modified infiltration swale) were constructed at the Auburn University - Stormwater Research Facility to compare infiltration behavior under varying rainfall frequencies, soil moisture conditions, underdrain settings, and seasonal differences. Moisture sensors tracked water movement within the swales, and surface storage and settlement were monitored. Results showed the ALDOT infiltration swale performed adequately and met infiltration goals. The modified infiltration swale, which included an amended topsoil and optimized media matrix, provided higher infiltration rates. The ALDOT swale averaged an infiltration rate of 1.6ft/d and a drawdown time of 12.25 hrs, while the modified swale achieved 5.2 ft/d and 5.06 hrs, respectively. Drier soils, longer inter-event dry periods, and warmer months resulted in higher infiltration rates in both designs. Moisture data indicated that infiltrated water reached the bottom of the modified swale in 0.13 hours compared to 1.8 hours for the ALDOT swale. Hydrologic modeling demonstrated that both swales reduce discharge, with the modified design providing the largest reductions under design storms and long-term rainfall. Assessment of surface profile elevations found no indication of settling in either swale.
• Format:
  PDF
• Funding:
  931-072
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:984acbe9d69f995d225bc03935d6a6e1084a8832d1ea5d5cf89a3b059527675748106e2ea82229060c891006aeb53750cd35e68fd0ea03f1f0ae07cd6401b05f
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/88488/dot_88488_DS1.pdf
• File Type:
  [PDF - 16.02 MB ]