FEMA just released the proposed FIRM Maps in December of 2019 for Florida and Palm Beach County. CLICK HERE to read my post on the new maps. This got me thinking though. In terms of elevations using the same base line just how much have the flood zones changed?
For this example I am going to look at the community of Frenchmans Harbor in Juno Beach at the base of the Donald Ross bridge. So, let’s go to the the FEMA Map center and look up my listing at 13958 Chester Bay Lane.
The current (as of Jan 2020) flood zone map does NOT show this property as being in the Special Flood Hazard Area Zone AE. However the zone AE is in the area and the Base Flood Elevation is given there as +4′ by the 1988 NAVD datum.
From the survey accompanying the boat lift permit, the elevation at the top of the sea wall is 7.3’ (1929) and the Finished Floor Elevation of the house is at 9.22’ (1929). Converting these to the 1988 datum we have the top of sea wall is at 7.3’-1.54’ = 5.76’ (1988) and the FF El. = 9.22’-1.54’ = 7.68’ (1988).
So we see that the current base flood elevation (4′) is BELOW the top of the sea wall at 5.76′. But what was the Base Flood Elevation before the last map change was adopted in October of 2017?
Frenchmans Harbor is in unincorporated Palm Beach County. The first FIRM Maps for Palm Beach County were effective as of 02/01/1979. Prior to the most recent (curent) map the last revision was effective on 10/15/1982. This map gave the Base Floor Elevation of Zone A, which was in the SFHA, as 6′ by the 1929 NGVD datum. A BFE of 6′ by the 1929 datum is 4.46′ by the 1988 NAVD datum.
So, from 1982 to 2017 the Base Flood Elevation was 4.46′. Then, in 2017 it was changed to 4′, so it went down in real terms. Now they want to raise the Base Flood Elevation by 3′ from a BFE=4′ to a BFE = 7′.
The proposed flood map is for the BFE = 7’ for 13958 Chester Bay BUT the AE zone does not touch the property. It does show the shaded zone X as being in the back yard. I looked at the old survey for the property and the FF El is 9.22′ by the 1929 datum and thus is FF El. = 7.68’ (1988 NAVD). With the finished floor elevation (FF El. = 7.68’) being above the BFE of 7′ it should not be rated as being in a SFHA.
