Medical District Drainage Tunnel Extension at Ehrhardt Street


To: All interested Agencies (FEMA), Groups, and Individuals

This is to give notice that the City of Charleston under Part 58 has determined that the following proposed action under South Carolina Office of Resilience Disaster Recovery Division (SCDOR DRD) program (Project # IP-20-1000-01) is located in the 100-Year Floodplain, and the City of Charleston will be identifying and evaluating practicable alternatives to locating the action in the floodplain and the potential impacts on the floodplain from the proposed action, as required by Executive Order 11988, in accordance with HUD regulations at 24 CFR 55.20 Subpart C Procedures for Making Determinations on Floodplain Management and Protection of Wetlands.

The City of Charleston is proposing to perform work on Ehrhardt Street and the intersection of Cannon and President Streets to alleviate frequent flooding issues currently experienced in these locations. The project is located in Charleston, Charleston County, South Carolina, and is identified to be within the 100-year floodplain, specifically flood zone AE. The project is divided between two sites, one at the intersection of Cannon Street and President Street and one along Ehrhardt Street and within the MUSC Institute of Psychiatry courtyard. The City of Charleston is proposing to replace and upgrade the existing stormwater system along Ehrhardt Street adjacent to the existing MUSC Institute of Psychiatry courtyard. The new stormwater system will connect and drain to a vortex stormwater structure connected to a vertical drilled drop shaft (Ehrhardt Street drop shaft) that will be installed in the MUSC Institute of Psychiatry courtyard. A deep underground horizontal tunnel will be excavated from the new vertical shaft at Ehrhardt Street to the existing vertical shaft at Cannon and President Streets. The deep underground horizontal tunnel will connect the two vertical shafts and convey stormwater to the existing series of deep underground tunnels that make up the Spring/Fishburne deep tunnel system.

The purpose of the project is to alleviate frequent flooding issues currently experienced in these areas which would provide benefits such as safety, mobility, and a healthier community. The total acreage between the two sites will disturb approximately 0.8-acres. For the portion of the project site located at the intersection of Cannon Street and President Street, approximately 0.3-acres of disturbance are located within easements on private property and <0.1-acres of disturbance are located within the rights-of-way of Cannon Street and President Street. For the portion of the project to be completed on Ehrhardt Street, approximately 0.2-acres of disturbance are located within easements on private property and 0.3-acres of disturbance are located within the right-of-way of Ehrhardt Street. The portion of the floodplain in the proposed project site consists of asphalt paved roads, concrete sidewalks, gravel parking areas, and a partially grassed and concrete courtyard. Surface water generally flows into the low-lying area of Ehrhardt Street where the proposed stormwater improvements are to be located. Surrounding uses consist of medical businesses and general urban development. The lack of wooded vegetation combined with soil compaction from development, and placement of impervious materials in roadways and sidewalks, has removed the floodplain’s ability to attenuate runoff through infiltration and evapotranspiration, thus limiting floodwater storage for the retention of surface water. The previous development within the proposed project area has removed the floodplain’s recreational, educational, and scenic values. No adverse effects are anticipated on the natural environment or the related natural and beneficial functions and values of the floodplain.

There are three primary purposes for this notice. First, people who may be affected by activities in the floodplain and those who have an interest in the protection of the natural environment should be given an opportunity to express their concerns and provide information about these areas. Commenters are encouraged to offer alternative sites outside of the floodplain, alternative methods to serve the same project purpose, and methods to minimize and mitigate impacts. Second, an adequate public notice program can be an important public educational tool. The dissemination of information and request for public comment about floodplains can facilitate and enhance Federal efforts to reduce the risks and impacts associated with the occupancy and modification of these special areas. Third, as a matter of fairness, when the Federal government determines it will participate in actions taking place in floodplains, it must inform those who may be put at greater or continued risk.

Written comments must be received by the City of Charleston at the following on or before July 1, 2021: City of Charleston, Department of Public Service, 2 George Street, Charleston, South Carolina 29401; (843) 724-3713; Attention: Frank Newham, Senior Engineering Project Manager, (RE: HUD Environmental Review). A full description of the project may also be reviewed from 8:30 AM to 4:30 PM at address same as above. Comments may also be submitted via email at All associated maps, permit applications, and project information are available for review on the City’s website:

Date: June 16, 2021

Alert: Funding Approval

The City of Charleston has signed an agreement with the South Carolina Disaster Recovery Division to receive federal funding for the Medical District drainage improvement project. The funding is part of the Community Development Block Grant Mitigation (CDBG-MIT) funding. The funding allocated under the grant is $9,964,190 with a matching commitment from the city of $4,245,646.

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  1. Project Overview

About the Project

The Charleston Medical District is home to three major medical centers: MUSC, VA, and Roper Hospital. Together, this includes the premier medical university of the region, the region’s only Children’s Hospital, and the Veterans Administration.Ehrhardt 2

The Medical District is increasingly threatened by repetitive flooding. Major storm events hit Charleston multiple times every year affecting access to essential medical care, including emergency vehicle access to the Medical District. When operations are interrupted, it has a dramatic impact on the public health and safety for employees, patients, visitors, and residents of the area. Without intervention, the delivery of healthcare itself is at risk.

The Ehrhardt Project will construct a deep tunnel extension and drop shaft to drain the street level stormwater collection system into the deep tunnel and pump systems of the US-17/Spring-Fishburne Project. The City is currently constructing the US-17/Spring-Fishburne project and is expecting to begin the Medical District Drainage Tunnel Extension at Ehrhardt Street project in early 2022.


To learn more about the project, please check soon for a StoryMap outlining the work that will be done for the Medical District Drainage Tunnel Extension at Ehrhardt Street. Curious as to how deep tunnels work? Check out the US-17/Spring-Fishburne Deep Tunnel Drainage Improvement Project website for more information.

Ehrhardt Quick Facts