Greensboro FEMA Flood Studies
Clients: City of Greensboro, NC and Davis-Martin-Powell
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Services provided in this project:
The City of Greensboro Water Resources Department contracted with JEWELL as a subcontractor to Davis-Martin-Powell to address several issues in the City’s FEMA Floodplain Maps, involving three distinct areas of the City. JEWELL coordinated the work with the North Carolina Floodplain Mapping Program (NCFMP) and FEMA to ensure compatibility with ongoing map updates.
The first area involved phased construction of a large institutional development occurring along a reach of South Buffalo Creek Tributary 4 that was not studied or mapped in the 2007 FEMA update because it was outside of the City limits at the time. JEWELL updated the hydrology for the watershed to reflect development which has occurred in the 10 years since the effective model was developed. A LOMR application was prepared and submitted, updating the hydrology and adding flood elevation/boundary data for the unmapped reach, and accounting for a culvert replacement which was constructed under a no-rise certification. The LOMR revisions became effective in October 2013.
In the second area along a reach of South Buffalo Creek Tributary 11, an apartment complex and a new street crossing had been constructed after the hydraulic models were developed for the 2007 update, but before the maps were adopted. The street crossing and the topographical changes have significantly impacted flood conditions. JEWELL updated the watershed hydrology and the cross-section geometry for this reach and the information was forwarded to NCFMP to be incorporated into their map maintenance updates, which were already in progress.
The third area, in the Horse Pen Creek watershed, also involved development that occurred after the streams were modeled and before maps were adopted. A large number of condominiums were built on fill, well above the base flood elevations, but are mapped within the floodplain, which was delineated on older topography. Two LOMR-F applications were submitted to FEMA and approved in January 2013, documenting that the condominiums are outside the floodplain and property owners should be released from the mandatory National Flood Insurance Program requirement to purchase flood insurance.