With the completion of the first phase of the project (TIGER 1), significant improvements have been made to pedestrian safety, vehicular safety, and traffic efficiency along and directly adjacent to the Septima Clark Parkway from Spring Street to Coming Street. While more than 175 stormwater structures and 5,500 linear feet (LF) of pipe ranging from 18-inch diameter to 48-inch diameter have been installed in this same stretch of roadway, significant work still needs to be completed before the drainage problems can be more fully alleviated. Additional phases are planned with project completion estimated for 2023.
Phase 2 (Completed)
Additional work on Spring and Cannon Streets from the western terminus of Phase 1 to:
President Street south of the Crosstown to Cannon Street
President Street north of the Crosstown to Fishburne Street
Fishburne Street from Harmon Field to Ashley Avenue
Ashley Avenue from Fishburne Street to Sumter Street
More than 12,000 LF of new stormwater pipe ranging in size from 15-inch to 54-inch and more than 300 stormwater structures (catch basins, inlets, junction boxes, conflict structures, etc.) were installed. Eight drop shafts with vortex boxes were also constructed during this phase that connects to the deep tunnel system (Phase 3). Crowder Construction Company (Charlotte, NC) began work on 1 June 2015 and completed this phase of the project on 20 December 2017.
Phase 3 (Underway)
This phase will see the construction of 8,232 linear feet of 12-feet diameter tunnel up to 150-feet below the ground surface, two 30-feet diameter working shafts, and two 20-feet diameter exit shafts. The main line tunnel is approximately 1 mile long running east-west under U.S.17 from between the Ashley River bridges to Coming Street. The President St tunnel is approximately half mile north-south running under President Street from Harmon Field to Cannon Street and intersecting the main line tunnel more than 140 feet below the intersection of U.S.17 and President St. Jay Dee Construction, Inc. out of Livonia, MI mobilized in early July 2016 and is expected to complete this phase by July 2020.
Phase 4 (Underway)
Construction of the wet well for the large stormwater pumps and the triple box culvert outfall into the Ashley River. The wetwell will accommodate the large stormwater pumps which will be installed in Phase 5. The outfall consists of triple 8-ft by 10-ft box culverts which will increase the outfall flow area by almost 10 time. With completion of Phase 4 of the project, some drainage improvements will be realized under normal tidal conditions. Conti Enterprises, Inc. out of Edison, NJ began construction for Phase 4 in March 2019 and is estimated to be completed by July 2022.
A new pump station between the Ashley River Bridges with three pumps each capable of pumping 120,000 gallons per minute, three 850 horse power diesel engines to power the pumps (thereby eliminating the need for electricity to run the pumps in the event of a power failure), and one back-up diesel generator to run the electrical and control systems in the event of a power failure. Once Phase 5 is complete and the pump station is online, the Crosstown and surrounding areas should remain passable in all but the very worst storm events. (Due to the topography and layout of the City of Charleston, the pump station will not be able to accommodate tropical storm events with storm surge that inundates the City.) It is estimated that construction for the pump station will begin at the completion of Phase 4 (2022) and be brought online sometime in 2023.