The Problem


On August 5, 2005 FEMA issued a revised Digital Flood Insurance Rate Map (DFIRM) and Flood Insurance Study (FIS) for Rock Creek and Clifton Branch (Trib 98) in Frederick County, Maryland. This new map showed that the entire mall area fell directly in the midst of a 100-year floodplain, directly impacting the renovation plans for the newly purchased Frederick Towne Mall by the Frederick Towne Mall Associates, LLC.

The Solution


Massoud Rezakhani Consulting (MRC), LLC in partnership with Exponent, worked closely with the City of Frederick, FEMA, and FEMA’s study contractor AMEC, to obtain the technical data used to develop the floodplain and floodway for these two creeks. Evaluations of the technical data and analyses revealed that the floodplain and floodway boundaries depicted on the preliminary DFIRM were inappropriate and needed revisions to both the floodplain and floodway boundaries.

The proposed FEMA restudy for Rock Creek and Trib 98 were inappropriate to be used to set the floodway in the area of Frederick Towne Mall. On Rock Creek, channel outflows were not separated from channel flows when the water surface elevations of the floodway were established. Also in the Trib 98, overland flows in excess of the pipe capacity were not modeled. Therefore, the floodways shown in both these areas are not based on FEMA guidelines and would not be enforceable for the city.

Our study resulted in a revised hydrologic and hydraulic analysis for Rock Creek and Trib 98. The revised floodplain and floodway boundaries are based on sound engineering practice and meet FEMA guidelines and specifications. The proposed floodway meets the FEMA criteria for development of a floodway as a tool for the City of Frederick to meet the minimum floodplain management criteria and economic needs of the community. This floodway is both adoptable and enforceable by the City of Frederick, Maryland.

As a result of our study, FEMA revised the DFIRM and FIS for the City of Frederick in September 2007. We were able to reclaim the use of 75% of the entire mall area without any flood restrictions. In the end, the floodplain was reduced, but not removed. With that in mind, we able to prepare structural engineering designs to elevate the structure, allowing the developer to continue building.

Based on FEMA’s revised DFIRM and FIS, along with our structural engineering plans for flood mitigation, the developer is now able to go forward with the Frederick Towne Mall renovation project and is in the process of obtaining the necessary community planning feedback and permits. The Frederick Towne Mall renovation project completed in 2008.


  • June 2005, Frederick Towne Mall Associates, LLC purchased the run down Frederick Towne Mall.
  • August 2005, FEMA issued a revised Flood Insurance Study and DFIRM. The entire mall area is now unable to be developed, rendering the investment a complete waste.
  • November 2006, MRC, LLC and Exponent ask FEMA to revise status based on new findings.
  • September 2007, FEMA approves revised DFIRMs.
  • 100% of mall area is now approved for development: 75% was shown not to be in the floodplain, and the remaining 25% was able to be developed using structural elevation techniques.