fema LOMA's

In Kansas these days we can contact the Kansas Division of Water Resources ?ÿ(under Dept of Ag.) to obtain a BFA, which is apparently close enough to a BFE, to satisfy FEMA. ?ÿLat/Long or street address for town lots is the primary input plus a little digital outline of the structure or area under investigation. ?ÿPerhaps Utah has a similar system in place.

Utah a bit different than Kansas (been there!).?ÿ Mountains in the middle of a desert.

I probably need to learn how to do these.?ÿ Looking more at the FEMA site it looks like one would need to take cross sections along the channel and run the hydraulics to get the depth (BFE).?ÿ I can't think of it right now but there is government website out there where you can locate a point on a stream and it will figure out the drainage area and give you the max flow for different storm periods.

So Yeah, I could probably do all this but it is going to cost them money for sure.?ÿ You'd also need FEMA to accept your calculations.?ÿ Still not sure I want the liability.

I referred the caller to one of the larger engineering companies.?ÿ I even called them to ask about it.?ÿ Guy told be they do them BUT it's EXPENSIVE.?ÿ Caller already has his foundation (basement) cast before the county shut it down and told him he couldn't have a basement.?ÿ He'll probably pay!

I think I may call a FEMA flood specialist and get more up to speed on exactly what needs to be done.?ÿ How much work does it really take?

I was told that you leave the BFE blank and FEMA will fill this in when reviewiug the LOMA app?ÿ for ZONE A?ÿ no BFE

Ive not heard of FEMA calculating a BFE in a Zone A, unless perhaps a remap is pending. I'm a PE and I usually have the LS shoot the LOMA form info and gather 2-3 stream cross sections in order to compute the BFE with a USGS regression 100yr flow. Then FEMA reviews the whole package for approval or denial.

I hire an engineer, it's expensive but when you may be paying hundreds of dollars a month for flood insurance it's a small price to pay. I've had some very happy clients that can't write the check for the service fast enough.

I've been told FEMA will give you the BFE for a zone A, never can get them to do it however.

If you think about it how can they? Who does the cross-sections?

I know how they get elevations in a zone Ae, I've talked to the people who ran cross-sections for that and I know how the topo info was generated.

Never found anyone who ran cross-sections in a Zone A for FEMA.

You have to have good data to get a good number for a BFE, if it's some rough DEM file being used then that BFE isn't going to be very accurate.

We do a few Zone A LOMA's each year and in Maine we have a Best Available Data website that is run by our Department of Agriculture, Conservation, and Forestry that contains approximate BFE's for most Zone A flood sources.?ÿ

We submit the rough BFE if found, a topo map of the area around structure down to the flood source, and whatever other information we think may be helpful. Even if there is no BFE available we have had them approved just from filling out the LOMA paperwork and providing a detailed topo of the immediate area.

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I've done a number of them in Zone A (old maps unnumbered A Zone) and have used different methods depending on the circumstances. As TickMagnet states above I've submitted the application to FEMA, but determined the BFE from the following methods:

1) Used a contour interpolation from the USGS quad map as FEMA states to use at seminars. Sometimes they say to do it this way and other times they say it isn't reliable.

2) If the FIRM is one with an aerial photo, map the edge of the Flood Fringe 3D and use that elevation as the BFE, submit to FEMA with a letter stating how you determined the BFE, and if they don't agree with it, determine it from their information.

3) Contacted all the local agencies who might have determined a BFE and use it (USACE, Soil Conservation Service, County, State, Dept. of Fisheries, old gauge station reports from USC &G, local Flood Plain Manager).

I do however fill out the BFE elevation and submit supporting documents or reports which I used to determine that BFE. If you haven't read or seen it, a good starting point is to review "Managing Floodplain Development in Approximate Zone A Areas, A Guide to Obtaining and Developing Base (100 year) Flood Elevations", sorry but I don't see the common FEMA publication number on it.

I've determined after doing this kind of work for about 20 years now that FEMA usually has more information which is not public than they are letting us know about. In one case they sent me an aerial photo about 10 miles upstream from where the last cross section was done and it had a great edge of Flood Zone highlighted (contour line) which closely resembled the edge on the FIRM. Of course they determined the BFE to be 0.1' above the elevation I submitted but it made the client's insurance premium more reasonable. Another interesting point about the FEMA contractor doing the work, depending on which contractor is the caseworker, they are more helpful in providing information to assist you.

I have provided the information as outlined in the following link to FEMA, in the on-line LOMA request with great results. ?ÿFEMA computes the BFE and issues the a LOMA.

https://dec.vermont.gov/sites/dec/files/wsm/rivers/docs/rv_azonesurvey.pdf

Check out FEMA's ESTIMATED BFE VIEWER:

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

DDSM

I hope your Clients appreciate what you do for them. 

I also have had mixed experiences with FEMA contractors through the LOMA and eLOMA process.  Trying to get past the clerk to a person with a background in hydrology can be somewhat difficult.  Consistency and decision making is apparently not in the FEMA contractor's playbook.  I have found the Region Directors and PE's to be very helpful but don't like that I have to go to them with stuff they hired the contractor to do.  For all the LOMA's FEMA approves, I believe there are a good many they do not approve that should be.

I have worked on a few of those and in each instance we hire a hydraulic engineer, run the cross sections and send them the data.?ÿ They run their computations and provide the BFE.?ÿ It was worked out great the 3 times I had to go this route.?ÿ Our sites haven't been too difficult to obtain the cross sectional data but I am sure there are many where that could be quite costly.

'Used' to be in Zone A that we showed (on a survey) a structure as either being in or out of the floodplain (as shown on FEMA maps) and if in, that triggered the EC and the LOMA.

Now it appears that if any part of a parcel is in the floodplain, the owner needs an EC and LOMA.?ÿ ?ÿThis is usually based on the Standard Flood Hazard Determination Form (SFHDF) filled in by some far away clerk.

How do you convince the lender/insurance company that the building is not in the floodplain and does not need insurance.?ÿ Is a note on a plat showing building relative to floodplain sufficient??ÿ The lender relies on the SFHDF and fed regs require flood insurance for federally backed mortgages.

If the structure is outside of the flood boundary, a LOMA application can be sent in with an Out As Shown designation and have it approved.?ÿ Only once has one came back because it was so close the SFHA boundary, they wanted an EC to prove the existing ground was above the BFE before issuing the LOMA.?ÿ?ÿ

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Seems like a ridiculous question but I'm trying to figure out why I need to remove a structure from the floodplain (LOMA) that is clearly shown as not being in the floodplain?  Not sure if I should have taken that logic course in college