FIS BFE

Map

I forgot to upload the map...duh.

I like the Earth plugin. Using the measure tool to station the profile from the cross sections makes things a little easier.
https://hazards.fema.gov/femaportal/wps/portal/NFHLWMSkmzdownload

I'd run with 99.5 as that is the highest BFE (interpolated) adjacent to the house. Others might say 101 and declare that interpolation is not allowed. My theory is that it is ultimately up to FEMA to accept or reject the number I insert on the form.

You've got two cross sections in the area. Use the Earth site to inverse the distance between them as best you can see the water body, go the the FIS and check your inverse between the record for how close you are to the FIS, then figure out at what "river mile" the structure is using the same method. FEMA and the insurance underwriters like to see the FIS box checked more for determining the BFE than the FIRM box. It shows you didn't just pull the elevation out of thin air.

Unless I am mistaken, I believe his issue is not how to determine the BFE from the FIS profile, but where on the profile he should be taking it based on the sinuosity of the stream at the house location.

Always perpendicular to the thread of the stream from the upriver building corner (if there is a building, if not just the upstream edge of the property). If there is enough comfort room I usually add some arbitrary number to the BFE (differs in each case how much, usually less that half a foot) that I feel would account for any differences between my determination and FEMAs.

I once did a LOMA for a very large manufacturing facility. The flooding source was a small creek adjacent to the subject building. The BFE fell 15' from one end to the other.

There was a large berm constructed along the creek bank in the 50's or so (don't remember exactly), it was well within long-ago enough to not be considered fill. I spoke with a mapping specialist at length about this project, because in effect it was impossible for the flood waters to crest the berm, but the BFE was well over LAG, FFE, etc.

I asked if I sent a detailed map with the LOMA that showed cross-sectional detail every 50' feet or so if they would analyze the conditions and render a favorable LOMA.

My fee was $3,000 and the client was paying something like $3,000 per month in flood insurance (large multi-million dollar facility). A different mapping specialist reviewed the LOMA than the one I spoke with previously and declared it in the flood plane because "The LAG is lower than the BFE". That's all the explanation that I got.

I always wondered what would happen if I just keep submitting it like it was new, maybe someone with sense would finally be the reviewer.

This one has always bugged me, if anyone has any information that may help I would still like to submit it for them free of charge.

I too have been sold this bill of goods. Natural ground surrounding the LAG higher than the BFE, told by FEMA when I called that I could send a topographic survey showing as such and they would issue a LOMA. That particular client did not want to pursue it, this was 3-4 years ago. Fast forward to last month, called and asked exactly what would be required and was told "Never heard of that, you are mistaken. If the BFE is above the LAG it is in the flood zone." I get different answers to the same questions all the time when calling the MSC.

Yep. The problem is that there are many scenarios that their forms do not address, and the outcome is ruled yes/no based on the forms.

He didn't mention the FIS, that is why I included the information. My usual rule is that if the BFE from the FIS is higher at the upstream end of a crooked stream like this, than the building LAG, or it is apparent flooding will come from the upstream end, that is my BFE. IF it is fairly flat, average it out.

Noting below on the comment about the berm, if it isn't certified and open at each end the flooding could come from anywhere. The last large flood in our area was from the water coming inside the levee from the north about a mile away from the homes on the south end of the levee. Guess someone should have closed the river off at the north end before the high water.

Map

Based on results of surveyed locations I will not use Google and the NFHL for anything other than concept evaluation. I have seen the SFHA boundaries relative to improvements shifted over a hundred feet. I relate my survey data to the DFIRM OR scanned panel using the grid ticks. I measure along the apparent thread and check it against the profile. Then I use the BFE from the profile.

Google is an awesome tool. The NFHL is simply not a good tool where I work yet...