I have been asked to set a BM for a house in Flood Zone A4. The firm has it at roughly 374.7' (plus freeboard in NYS). An engineering company did an hydraulic analysis and using the profiles came up with a BFE of 374.0'. Per the FIRM the 374' BFE is 1800' away. Using the profiles you could be anywhere from 374-375' BFE. I am about to call the engineer to discuss, but I'm wondering why they would have used the lowest possible option.
I'm leaning towards using the FIRM and error on the side of caution.
Has anyone seen the BFE on the FIRM and the BFE on the profiles that much off?
Thanks
Base flood elevations on panels are based upon the profiles but generally are rounded to the nearest foot. For community compliance and insurance purposes the panel elevations are sufficient. In this case because because the panel is higher I would definitely use it.
If doing a Loma or Lomr profile elevations must be used which are shown to the nearest tenth.
I have see much more than that. When there's a difference, the profile rules. Or so we have been told by FEMA.
When in doubt turn to written policy. The FIS profile should rule.
The FIS profile is usually the "Bible", but I would ask the local floodplain administrator to be sure.