Certain HMA-funded structure mitigation projects must meet the minimum standards of FEMA’s partial implementation of the Federal Flood Risk Management Standards:
- All structure elevation, mitigation reconstruction, and dry floodproofing projects; and
- All projects where HMA funds are used for new construction, substantial improvement, or to address substantial damage to structures.[116]
The identification of the flood hazard must be based on the best available data.[117] This information may be found in Flood Insurance Rate Maps (FIRMs),[118] Flood Insurance Studies or non-FEMA sources as described below:
- If the FIRM is up to date and available and FEMA determines that the best flood hazard information is the FIRM, then applicants must use the 1% and 0.2% annual chance floodplains on that map.
- If FEMA has provided advisory flood hazard information because the effective FIRM is out of date, FEMA will designate the advisory information to be used if the advisory information is at least as restrictive as the effective information. If assistance is provided post-disaster (such as HMGP), FEMA will communicate the availability of floodplain maps or advisory flood hazard information to be used.
The design standards differ depending on whether the action is critical or non-critical and whether the structure is in a 1%t or 0.2% annual chance floodplain based on the best available data.[119] If a state, local, tribal, territorial government or federal agency has adopted a higher standard applicable to the specific project, FEMA will require the higher standard.[120]
For non-critical actions in a 1%annual chance floodplain:
- Applicants must elevate or floodproof structures to the 0.2% annual chance flood elevation or an additional 2 feet above the Base Flood Elevation, whichever is lower.[121] [122]
- For those areas where the 0.2% annual chance flood elevation has not been established, applicants must elevate or floodproof structures an additional 2 feet above the Base Flood Elevation.
For critical actions in the 1% annual chance floodplain:
- Applicants must elevate or floodproof structures to the 0.2% annual chance flood elevation or an additional 3 feet above the Base Flood Elevation, whichever is higher.
- For those areas where the 0.2% annual chance flood elevation has not been established, applicants must elevate or floodproof structures an additional 3 feet above the Base Flood Elevation.
For critical actions in the 0.2% annual chance floodplain:
- Applicants must elevate or floodproof structures to the 0.2%annual chance flood elevation or an additional 3 feet above the Base Flood Elevation, whichever is higher.
This policy does not affect non-critical actions involving structures that are within the 0.2% annual chance floodplain, but outside the 1% annual chance floodplain.