The Charleston Peninsula Coastal Flood Risk Management Study is a federal study that is investigating coastal storm impacts on the Charleston peninsula and, in partnership with the City of Charleston and its stakeholders, is exploring effective, economically-viable and environmentally-sound solutions to mitigate risks and build enduring coastal storm resiliency.
This four-year feasibility study began in 2018 and will conclude with submission of a final detailed report to Congress in the summer of 2022. The study is 100 percent federally-funded through the Emergency Supplemental funds appropriated by Congress.
In April 2020, USACE published the draft Feasibility Report and Environmental Assessment (FR/EA). This report outlined initial findings and identified several potential storm risk reduction measures, including a perimeter storm surge wall, pump stations and nonstructural measures. In March 2021, the study transitioned from an Environmental Assessment (EA) to an Environmental Impact Statement (EIS), enabling USACE to do more analysis on project impacts, more clearly define mitigation measures and offer expanded public engagement through additional public meetings and the release of an updated draft report for public review.
Throughout the entire feasibility study, the objective has remained at the forefront: reducing coastal storm surge risks to human health, public safety, emergency access and the economic viability of the Charleston peninsula, while enhancing overall coastal resiliency. Public engagement and a continued close partnership with the study’s non-federal sponsor, the City of Charleston, also remain vital to the study’s success and its development of a potential federal project.
Over the last several months, the study has used public and agency feedback and results from detailed modeling to optimize the tentatively-selected plan. Among some of the plan’s most significant changes since the draft FR/EA are: a decrease in the estimated project cost from $1.75 billion to $1.1 billion, an increased benefit-cost-ratio from 2.2:1 to 10.2:1, the addition of living shorelines, a reduction of wetland impacts, the modeling of impacts to surrounding areas and a refined interior drainage analysis.
This feasibility study is one piece of the City of Charleston’s long-range flooding strategy. In the last several years, the City has initiated several flood reduction strategies, including its Flooding and Sea Level Rise Strategy, continued vulnerability assessments, rehabilitation of Low Battery Wall, the Dutch Dialogues and major drainage projects. This study primarily addresses coastal storm surge and, in conjunction with other flood mitigation efforts, also takes tidal flooding and sea level rise into account in its analysis.