FEMA Zone A (thread162-108813) 1

[bencraddock]

I have a similar situation as the above-referenced thread (a FEMA Zone A floodplain shows up on a stormwater swale through a farmer's field with a relatively small upstream drainage area). We want to develop the property and simply pipe the flow through it. Does anyone know why FEMA would include a stormwater swale in a floodplain? There are no tailwater issues as far as I know.

Would there be an easier, more "common sense" way to get the floodplain revised given the situation other than the usual LOMR process??? Even if I do a detailed analysis and show what the 100 year flows and BFE would be in the swale, I would argue that it would not belong on a FEMA FIRM map since it's only a stormwater swale. Any thoughts?

 

[bencraddock]

Just to follow up... I was told by FEMA's consultant (Michael Baker Assoc.) that anything with a drainage area less than 1 square mile did not belong in a FEMA flood zone. So I was told to submit an MT-2 form with a site map that delineates the drainage area showing it to be less than a square mile - no hydrology or hydraulic calcs are required. This sounds too good to be true but I'll write again when I get more news.

An interesting side note, the County (who in this case is the designated community official) did not want to sign off on the concurrence form, but FEMA said that I could submit the forms anyway. Since there is no floodway involved, the County's concurrence probably won't be necessary.

 

[queque]

Have you checked with FEMA to validate the 1 sq. mi. limitation on Flood Studies?
Where is the reference?

 

[bencraddock]

I have not been able to verify with FEMA. I did send in the application and am awaiting a response.

In doing some other research I noticed that the CFR Section 701.5 "Office of Surface Mining Reclamation and Enforcement, Department of the Interior" defines an intermittent stream as one that drains a watershed of at least one square mile. I know this is not directly related to FEMA but perhaps FEMA has a similar view that any watercourse that drains less than one square mile would not even be classified as an intermittent stream and should not be studied by FEMA. We'll see...