US 17 Spring/Fishburne Drainage Improvements

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

Our team started by conducting hydrologic and hydraulic analysis of the study area. We identified the most efficient means of collecting, conveying, and discharging stormwater runoff. The solution resulted in the construction of a deep conveyance tunnel network, a 360,000 GPM pump station, and an outfall into the Ashley River. This new tunnel drainage system allows for more reliable stormwater service under a range of tidal outfall conditions, including sea level rise and storm surge scenarios.


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