LOMRs and Stream Relocation: Lessons Learned and Troubleshooting Tips
Mary Beth Berkes, PE
GAI Consultants, Inc
Pittsburgh, PA
Obtaining a Letter of Map Revision (LOMR) from the Federal Emergency Management Agency has a reputation for slowing down projects and adding significant costs. As such, the goal of developers and hydraulic engineers is often to design projects that will allow for a no-rise condition, thereby avoiding the LOMR process. However, there are situations when stream restoration projects may require a LOMR based on the nature of the work. For example, revisions to mapping that has become dated due to channel migration could be required to support construction a stable stream re-alignment. Another example could be completing a project where re-establishing floodway connectivity would provide flood mitigation, hazard recovery, and resilience to flood prone areas allowing potential development in previous floodways or fringe areas. Accordingly, the goal of this presentation is to demonstrate techniques that could make the hydraulic modeling process and agency coordination required to support LOMR efforts more efficient.
This presentation will highlight lessons learned from the LOMR process, specifically demonstrating how hydraulic modeling for stream restoration projects to obtain a LOMR could differ from hydraulic modeling to support restoration design only. Tools within the USACE HEC-RAS software program will be presented, giving special attention to the hurdles that may be specifically encountered on stream restoration projects, such as accurately overlaying cross sections when the pre- and post-construction stream reaches follow different alignments, troubleshooting negative surcharges when adding encroachments, and effectively mapping results. The goal will be to present relatable concepts and common challenges encountered during hydraulic modeling and mapping of floodways for stream restoration and relocation projects. The hope will be that the presented information can make the LOMR process less daunting for hydraulics engineers and designers so that floodway maps can be updated in an effective manner allowing for timely construction of projects that mitigate flooding and support hazard recovery.
About Mary Beth Berkes, PE
Ms. Berkes is GAI’s Engineering Lead for Stream and Wetland Mitigation Design, and she also manages a team of experienced and junior staff focused on water resources engineering. She has over 16 years of design experience, specializing in hydrologic and hydraulic analysis and modeling, inundation studies and investigations, geomorphic surveys and field assessments, natural channel design, and stream restoration and bank stabilization for protection of utilities, property, and resources. Her experience also includes coastal and ocean engineering, dam design and hydraulic analysis, and design of hydraulic structures.
Ms. Berkes is a licensed PE in seven states. She has completed the Rosgen Level I through IV courses and her training resume also includes formal courses relating to multi-dimensional hydraulic modeling for stream restoration, advanced HEC-RAS modeling and scour analysis, and hydrologic and hydraulic permitting and procedures. She received her MS in Civil Engineering with a Concentration in Coastal and Ocean Engineering from Oregon State University, and a BS in Civil Engineering from the University of Pittsburgh