News - City of Greensboro FEMA Flood Analyses Completed
February 2013 –The City of Greensboro Water Resources Department contracted with JEWELL to address several issues in the City’s FEMA Floodplain Maps. The project involved three distinct areas of the City where the FEMA maps need to be updated. JEWELL coordinated with the City of Greensboro Water Resources staff to address concerns and coordinate map update efforts with the North Carolina Floodplain Mapping Program (NCFMP) and FEMA.
Phased construction of a large institutional development is occurring along a reach of an unnamed tributary to South Buffalo Creek 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 to NCFMP in October 2012, adding the unmapped reach and revised the mapping along the entire tributary to reflect updated hydrology and a culvert replacement which was done under a no-rise certification. The LOMR is being reviewed by FEMA/NCFMP and approval is expected following the 90-day period allowed for public comments.
In the second area, along a reach of another unnamed tributary to South Buffalo Creek, 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 roadway crossing and the extensive 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, again involved development that occurred after the streams were modeled and before maps were adopted. The result is that 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. A LOMR-F application was prepared to demonstrate to FEMA that the condominiums are outside the floodplain and property owners should be released from the National Flood Insurance Program mandatory requirement to purchase flood insurance. FEMA approved the LOMR-F in January 2013, certifying 33 lots as being outside the regulated floodplain and not subject to requirements for purchase of flood insurance. On three lots where small portions of the property are on the lower side of a retaining wall, the structures were certified as being above the base flood elevation.