City of Crisfield Drainage System Assessment
(Click above to download the report)
The drainage assessment was used to inform the existing FEMA and MDE grant for stormwater pumps and tide gates as well as the 2024 FEMA Southern Crisfield Flood Mitigation application.
This report was prepared by BayLand Consultants & Designers (BayLand) using Federal funds under award number NA19NOS419016 from NOAA, U.S. Department of Commerce. The statements, findings, conclusions, and recommendations are those of the author(s) and do not necessarily reflect the views of NOAA or the U.S. Department of Commerce.
4 BayLand Consultants & Designers, Inc.
City of Crisfield Drainage System Assessment
EXECUTIVE SUMMARY
The City of Crisfield (the City) is located in Somerset County on the eastern shore of Maryland along the Chesapeake Bay. The overall low elevations of the City and deficiencies of the drainage system result in frequent flooding of multiple areas within City limits. This assessment examines fifteen of the highest priority areas for flooding. Flooding in these areas is evaluated based on general topography, proximity to the flooding source, and the presence and effectiveness of the drainage system components. Flooding from both rainfall events and tidal sources, also referred to as ‘nuisance flooding’, are examined for each high priority area for both current conditions and with future sea level rise. Nuisance flooding extents utilizes a ‘bathtub’ approach by overlaying anticipated flood elevations on top of current topography. Flooding due to deficiencies in the drainage system are examined by using the EPA developed Storm Water Management Model (SWMM). NOAA Atlas 14 precipitation estimates are used to develop storm input parameters paired with tailwater conditions experienced today and with 2030 and 2050 sea level rise. The model was run with varying amounts of sedimentation occurring within the existing drainage systems to demonstrate the impacts on the capacity of the storm drain systems. Model outputs are used to determine the duration of flooding at each high priority area.
This assessment provides a vulnerability rating by examining the exposure, sensitivity, and adaptive capacity of each high priority area. This vulnerability rating, along with the size, economic impacts, location of City-owned assets and critical infrastructure are used to create a prioritization table of the areas for addressing flooding impacts.
Mitigation alternatives for addressing the deficiencies in the drainage system and remediation of tidal flooding are developed for the high priority areas. Each alternative provides a description and planning level cost estimate for implementation and on-going maintenance. A preferred alternative is presented for each high priority area. The prioritization table and the preferred alternatives were merged to create an implementation plan to address flooding. A planning level time frame is also presented for implementation of the preferred mitigation solution.