U.S. 17 Spring/Fishburne Drainage Improvement Project
Project Overview
The goal of this project is a significant reduction in the duration, frequency, and severity of flooding caused by moderate to heavy rainstorms along the Septima Clark Parkway and throughout the Spring Street and Fishburne Street drainage basins by Summer 2024.
Quick Facts About The Project
Volume
Once complete, the system will be able to move 360,000 gallons of water per minute from the Charleston peninsula to the Ashley River.
Flow
As a result of the new outfall, the system will initially work under gravity, increasing the flow rate by up to 7 times its existing capabilities by the end of Phase 4. Following the installation of the pumps during Phase 5, the flow rate will be increased up to 10 times.
Outfall
Phase 4 construction includes an outfall comprised of triple 8ft by 10ft box culverts extending 500ft into the Ashley River. The outfall will be below low tide so as to remain hidden from view and was designed to ensure that there would be no erosion.
Drop – Shafts
Eight drop shafts were installed in Phase 2 to convey flow from the surface to the deep tunnel. The intent of these is to spin the water into a vortex as it enters the drop shaft to prevent air from entering the tunnel system.
Wetwell
Phase 4 construction includes a wetwell measuring 137ft long, 55ft in diameter, and 40ft deep.
Local Contractors
75 million dollars of work will be awarded to local businesses.
Tunnel Boring Machine
Phase 3 used two tunnel boring machines to excavate the ground. The larger of the two was 15 ft in diameter and nearly 300 ft long with all of its components.
Tunnels
5400ft of 12ft tunnel, 2950ft of 8ft tunnel (which includes the drop shaft tunnels which connect the drop shafts to the tunnels).
Shafts
Phase 3 construction included four shafts up to 30ft in diameter and 180ft deep.
COntact us
City of Charleston Citizen Services Desk
(843) 724- 7311
Citizenservices@charleston-sc.gov
Robin Kidd – Stormwater Outreach Coordinator
(843) 214- 0146
Kiddr@charleston-sc.gov
