Development In a Flood Zone? 3

[Mechanos]

I would like to develop two plots; both plots have 55% of the lands within a flood zone. (A-5: Area inundated by 100 year flooding for which no BFE have been established.)
The County Regional Planner stated that bringing in fill is not permitted. However I would be permitted to shove material around within the flood plan in order to re-establish a grade above the BFE.
I have considered two options that would raise the finish grade. One would be to shorten or slope the shoreline. The other would be to dredge the river bottom along the shoreline and after treatment use the spoils to raise the elevation.
In later talks with County Officials the amount needed to raise the elevation above BFE has gone from 30” to 78”.
The Regional Planner has not been very cooperative in working with me and in answering my questions. Does anyone have any experience with development in a flood zone? Who is the ultimate authority in these matters, who has the final say of what the BFE is?
I really would like to get some advice before I begin any work.

 

[gbam]

First I assume that your County Flood Plain Department will issue permits based on your plan. From that I would say that they have final say in your requirements. You can research the base flood through FEMA and or the county if they have updated FIRM panels. Do your homework first then hire a competent engineer to design your plat & submit to the county.

 

[Maury]

If no BFE has been established, how is the Regional Planner arriving at 78" of fill to raise the property above the BFE. Follow gbam's recommendation a to get the the flood maps. You may have to hire an Engineer to model the river system and establish a BFE if non exists. Then get a copy of the County ordinance regarding development in a flood plain. It's the ordinance that will control what you can and can't do.

 

[LHA]

The S&LD Ordinance will govern development, and the Zoning Ordinance will establish a Floodplain Zone...BUT FEMA has the authority over what the flood elevation is.

You can't dredge for fill without the Army Corp's permission...I would not recommend that approach, buying new dirt will be way cheaper and quicker.

If you are in an A5 FIRM Zone, there has been no Detailed Study done by FEMA. Therefore, to the best of my knowledge, you are free to delineate one. As the others have said, hire a civil engineer (must be licensed, or the delineation will not be binding) and model the reach. Bringing in fill is permitted unless specifically prohibited by an ordinance. The fact that the Planning Commission doesn't want you to is not legally relevant (although keeping them happy is always adviseable).

Beware, doing this delineation could effectively (and legally) "rezone" the area as a Flood District, IF your local ordinance allows for that. This could backfire on you and make your development criteria more strict.

 

[Mechanos]

Thanks for the good and helpful advice.
Since the county is inland, there is no County Flood Plain Department. The Regional Planner is the Flood Plain Administrator. There is only one Major River that runs through the county. The community has not had any serious flooding since the A.C.E. flood prevention project which was completed over 30 years ago. The project included the construction of a floodwall, channel widening, deepening and straightening.
I think because of the prevention measures, the county has not had a need to adopt any Floodplain Zoning or Ordinances. I could be wrong, but I have checked and could not find anything. Also the township that the development is going to take place in has No Zoning, in fact the township has already issued a permit to build.
The Regional Planner has been tight lipped about any requirement for work permits or providing any type of documentation, although he did let me look at a FIRM map once. I don’t know where the 78” figure is coming from, I not even sure where the original figure came from, it just got higher as I talked to other County officials.
All I have gotten is a verbal understanding (would have preferred it in writing) that if I could raise the elevation above the BFE, with out bringing in fill I could build.
Lha, recommended buying new fill dirt. I thought the whole FEMA floodplain management concept was to protect the integrity of the Flood Plains. That’s why I like the idea of relocating material from within the floodplain to a higher elevation of the floodplain (“dredging”), this would not upset the delicate balance of Mother Nature and it would keep the Planner happy. Does anyone know if there is Floodplain mitigation, like there is with Wetlands?
Maybe its because the Planner is a one man office he does not want to create any more work for himself then he already has. I can’t blame him. He must be real busy, because he is a very hard man to get in contact with.
Anyhow, I was hoping for some simple black and white solutions to this issue. I will follow your suggestions and consult with a Civil Engineer and maybe a lawyer as well.
Thanks again!

 

[Mechanos]

Thanks for the good and helpful advice.
Since the county is inland, there is no County Flood Plain Department. The Regional Planner is the Flood Plain Administrator. There is only one Major River that runs through the county. The community has not had any serious flooding since the A.C.E. flood prevention project which was completed over 30 years ago. The project included the construction of a floodwall, channel widening, deepening and straightening.
I think because of the prevention measures, the county has not had a need to adopt any Floodplain Zoning or Ordinances. I could be wrong, but I have checked and could not find anything. Also the township that the development is going to take place in has No Zoning, in fact the township has already issued a permit to build.
The Regional Planner has been tight lipped about any requirement for work permits or providing any type of documentation, although he did let me look at a FIRM map once. I don’t know where the 78” figure is coming from, I not even sure where the original figure came from, it just got higher as I talked to other County officials.
All I have gotten is a verbal understanding (would have preferred it in writing) that if I could raise the elevation above the BFE, with out bringing in fill I could build.
Lha, recommended buying new fill dirt. I thought the whole FEMA floodplain management concept was to protect the integrity of the Flood Plains. That’s why I like the idea of relocating material from within the floodplain to a higher elevation of the floodplain (“dredging”), this would not upset the delicate balance of Nature and it would keep the Planner happy. Does anyone know if there is Floodplain mitigation, like there is with Wetlands?
Anyhow, I was hoping for some simple black and white solutions to this issue. I will follow your suggestions and consult with a Civil Engineer and maybe a lawyer as well.
Thanks again!

 

[cvg]

If you are in a floodplain, there generally is no limitation on importing fill other than those possibly imposed by your planner. However, you will have to provide the engineering analysis to show that your fill will not raise the BFE. the army corps 404 permit protects against placing fill within the floodway or in any "waters of the US".

 

[Bayou]

This may be a little late for you project...
When dealing with communities that have floodplain administrators with written regulations, typically you can fill in the floodplain. The fill doesn't have to be "re-distributed" soil from within the floodplain. However, the net fill within the floodplain (below the BFE) has to be zero.
eg. In my region, onsite soil tends not to be constructable material; therefore, fill is brought in from off-site. However, a floodplain basin is created to mitigate the fill.
Dredging from the stream lends to more problems. If you have available land, a basin would provide a better solution.

As far as slab elevations, some communities state that the finish floor must be at least 12-inches above the BFE (some state 18").

 

[floodbuilder]

We find ourselves in a very similiar situation. This is why I am going through this site.
I had to spend $800 for a surveyor to establish the BFE off a known benchmark 2 miles away.
I am under the assumption that a higher foundation is more cost effective than bringing in fill. Although I do not want the appearance of stilts from the road. The county is making me build 4 ft. above the BFE, making my foundation approximately 10+ ft. I intend to build a retaining wall at the front wall for aesthetics from the road and using fill off my property to backfill that section only. I'm on the New River in North Carolina.
Good Luck!