Zone A, Elevation Certificate

Well, you were wise to avoid them. You can bring your old elevation, which is probably NAD27 up to NAVD88 using NGS's program. Do an Elevation Certificate and submit it to FEMA. They will tell you what you have to do next. It varies by which FEMA rep you get at the time. If you get a letter of approval you're home free. My guess is they will require a new BFE study. If it's just a Creek you can Wade across not to bad. You need to be persistent to get your LOMA. Hope you didn't bid the job.

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You will need to download the FEMA Zone A manual and go from there with assistance from the floodplain administrator. I am currently working on one and the FA would have accepted the lowest lot elevation plus half the contour interval as BFE with a DFE at 2'?ÿ higher. That said, client wanted the lots removed completely and we are processing a LOMA. Overall I would say run away as these can get very time consuming really fast and drive billing up to places clients do not like.

I would say that Terminus-NC's statement about effort and cost is good.?ÿ

The training, effort and liability associated with that is enormous.?ÿ One must fully understand hydraulic profiles, Manning's equations with appropriate n values, or HEC-RAS, and in addition to that the application of the design rainfall event has to be done with accurate peak flows, HEC-HMS or similar, tailwater issues, blockage allowances, types of flow, sensitivity analyses.?ÿ ?ÿThat is for sure a strong civil engineering project in a specialty hydraulics/hydrology field with the worry of perceived error by clients if they experience a flood event that exceeds the design criteria for a 100-year flood.?ÿ Liability might also include mental anguish, disease from flood water, loss of sale.?ÿ And even if you did it perfectly, the cost and worry about defending it could be significant as well. If a lawsuit evolves, it is likely that the plaintiff will hire an expert who is truly experienced in the field and will try to tear what you did apart even if you did it perfectly.

I have looked over the Fema Zone A manual and it doesn't appear to be anything I'm qualified to tackle. It appears to me that what is described in that manual was already done by the firm that platted the subdivision. If the BFE from the plat cannot be used I will probably refer him to a PE.

I have done several elevation certificates in Zone A.?ÿ From large rivers to non existent creek bed.?ÿ You will definitely need a PE that knows what they are doing.?ÿ They will provide you with the limits of your topo, which can be extensive depending on the nature of your project.?ÿ You would complete the topographic survey and send them the data so they can produce the Zone A elevation.?ÿ Provide their info in your submital and certificate and you should be golden. I've never experienced any issues and usually do about 1 of these every 2 years or so.

@rpls#

I had a similar experience. I convinced the County Flood Plain Coordinator to accept the flood study done previously by the firm that did the subdivision. She later submitted it to FEMA who amended the FIRM. My client wanted the Elevation Certificate for a Building Permit from the County. It was an older Flood study that was done on the NAD27 datum. Your Flood Plain Coordinator should have the Flood Study that was done for the Subdivision in the County Records. Your County should accept the BFE that was done in that study.

These things take alot of time. I usually contract them out to a firm that is experienced in doing them. An easy one can be $2000, but I've heard of the studies costing $20,000. I've got one going right now they've been working on for 6 months. It of course has not had a previous study done on the property. There are FEMA employees that are very helpful. If you get in contact with a good one make sure you get his/her name and extension number.

Vast majority of flood plain water surface profile studies are done by consultants under contract with FEMA (or other gov. agencies), and they seem to be protected from liability in that format. An individual consulting engineer doing that for a private entity is not protected by any lawsuit/liability barrier that is afforded to government works and contractors.

The only way I know to do a Zone A BFE is to hire an engineer,,,,at least in the county I do them in.

I've gotten no help from flood managers, or FEMA getting a BFE for a site in Zone A.

And think about it, how would that be possible, without a topo, profiles, cross-sections where would this number come from, and if you got it how could it be anywhere near correct, you may be doing your client harm.

It's boots on the ground time and the data sent to a PE (one who knows how to do it) and they write a report and you submit to FEMA.

The costs range between $3.5k and up, depends on if you are simply getting a BFE or you need to define the flood plain for a site.

Of course I'm at the top of the country so it might be simpler here, drainage areas only get so large.

I may be wrong but I seem to recall about 10 years ago just filling out an elevation cert leaving the BFE empty and sending it into FEMA. After a month or two they mailed it backed completed.

Provide the Flood Plain Manager with enough data to allow him to prepare a Community Determined BFE. Your Community Rating is probably based on him doing that. OR request a LOMA for the upper portion of the Lot from FEMA. If their model has enough data to determine, they will remove the hazard from the upper portion of the lot. If the County fails and FEMA fails, then your client needs to buy a different lot.?ÿ

Problem with Zone A is that no BFE was determined by FEMA.?ÿ I could be wrong, but I don't think FEMA will provide a BFE for Zone A under any normal circumstance.?ÿ Sometimes counties will provide BFE.?ÿ I suggest that if you use a locally determined BFE, in addition to stating that it was determined by the Flood Plain Manager that you get it in writing from the manager, and keep letter in file.

@frank-willis

FEMA has provided BFEs for my Unnumbered A Zone submittals at least a dozen times. I guess it depends on the part of the country.

Requesting a LOMA used to get you a BFE with the result.?ÿ That has not happened for me in the last few years.?ÿ However I have recently applied for LOMAs in Zone A and will get a favorable determination from them but they will leave the BFE blank on the form.

My suspicion is they have models that they use to evaluate the requests and if they fall beyond certain floodprone thresholds they will remove the request from the BFE without going out on a limb by reporting a BFE.

Check out FEMA's "Estimated Base Flood Elevation Viewer:

https://webapps.usgs.gov/infrm/estBFE/

DDSM

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