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US 17 Spring/Fishburne Drainage Improvements

The Septima P. Clark Parkway (US 17) is a critical transportation corridor across the Charleston peninsula that experiences chronic flooding during heavy rainfall events. The City of Charleston enlisted Davis & Floyd to recommend and design improvements to alleviate repetitive, damaging flooding conditions and increase highway accessibility, traffic efficiency, and vehicular/pedestrian safety.


Our team conducted hyrologic and hydraulic analysis of the study area and identified the most efficient means of collecting, conveying, and discharging stormwater runoff for alleviating frequent and damaging flooding within the study area. The project team provided an improved drainage system reliable for a range of tidal outfall conditions, including sea level rise and storm surge scenarios. Vortex structures were developed and modeled for controlling air entrapment atop vertical drop shafts carrying flow from conventional collection systems into a deep conveyance tunnel network, a 360,000 GPM pump station, and an outfall into the Ashley River.

Services Provided

  • Stormwater
  • Hydraulic Design & Modeling
  • Roadway Design
  • Permitting
  • Traffic Control
  • CEI
  • Environmental
  • SUE
  • Public Engagement
  • Structural Engineering
  • Salt Marsh Mitigation