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 Message Boards » » Building a fence in a Floodplain (any engineers?) Page [1]  
mildew
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I have a piece of property with a corner covered by a floodplain (Flood Zone A). There are no structures being built in this floodplain area, but I would like to extend a fence through part of it. It would not be a solid fence - potentially aluminum or vinyl with generous gaps between each slat/post, so if there were any water or minor debris, it would flow through easily.

When going for the permit with the town, I'm told we are not allowed to do anything in the floodplain without an engineer doing a flood survey and documenting impact, quotes have been extremely high for this (some over 10x the value of the section of fence being installed - which would not be worth it by any stretch IMO). The length of fence is only maybe 50ft long in the floodplain area and then connects to fencing around the rest of the property. I can survive without it, but the yard would look much better if I could extend the fence and give more space for the dog(s) to roam around freely.

So, if I were to bypass the permit, other than regular issues with not having a permit for constructing a fence, could there be specific penalties for building in a floodplain? Anyone go through something like this previously? Any one a civil engineer that could offer insight or could knock this ASAP out at a fair price?

I've also thought about filling in and elevating most of the floodplain area then submitting for a FEMA review and removal of the floodplain, but the length of time for approval + $500 just to apply + potential cost of engineer anyway = would probably not be worth it. Only way I would do that is if I have flood insurance required - which is not expected.


tl;dr I want to build a fence in a flooplain area, what kind of trouble could I get into if I do it on my own and/or is anyone here able to help with the engineering survey required?

7/11/2017 3:43:59 PM

NeuseRvrRat
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i just dropped in to say

a permit for a fucking fence? rofl

actually, i bet you could get away with it if you pulled the permit for doing everything outside the flood plain and then came back in a few months and finished it off.

[Edited on July 11, 2017 at 6:25 PM. Reason : dfas]

[Edited on July 11, 2017 at 6:25 PM. Reason : ds]

7/11/2017 6:23:49 PM

eleusis
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so you're afraid to build a fence in floodplain without permitting, but you're OK with putting fill in a floodplain and then alerting a federal agency to the fact that you have done so?

what exactly would you consider a fair price for an engineer to prepare a variance for this fence?

7/11/2017 8:11:45 PM

TerdFerguson
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You'll have to check your jurisdiction's ordinances, but typically what I've seen is you can be charged with a misdemeanor and fined up to like $5k a day you are in violation until corrected.

That being said, most towns or counties aren't going to do that to a homeowner.

Most likely what would happen is, when caught, they would ask you to retroactively do a study showing no rise in flood elevations, or take the fence down, of course you'd be paying for both. If you refused to take the fence down I assume thats when the fines might start for a homeowner. (I've never seen it go that far, so I'm not really sure how it happens).

So will you get caught? I'm not sure. The instances I can think of where we did retroactive studies were during the sale of commercial land (buyer pulled all permits and found no flood permit), and a building inspector caught a dude filling a major floodway so he could park his RV RIGHT next to the river. We have had some other instances but I probably wasn't involved.

Disclaimer: I perform aspects of flood studies for my job, but I do not deal with the actual ordinances often. I've also only dealt with a handfull of flood administrators, and never with any actual enforcement actions, so your results could vary.

The kicker is it sounds like you may be on a small, rural stream (Zone A)? In this case one of the reasons you are getting quoted such high prices is there is no existing model, or its an old school model (like punchcard computer old school). So someone might have to come up with a model from scratch (could even include surveying$$$$).

There is one other possibility if you'd rather not run the "wait until caught route." I believe a floodplain administrator has the ability, in certain circumstances, to waive the need for a full engineering report. If you built something more like a split rail fence with wire as a way to mitigate flood elevation changes that maybe there is a chance the administrator would be understanding?? (The only times I've seen this occur was when soil was actually being removed from way out on the floodplain fringe).

[Edited on July 11, 2017 at 9:09 PM. Reason : I thought Zone A was pretty rare these days, is it Zone AE? Are there flood elevations??]

7/11/2017 9:06:38 PM

whtmike2k
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My parents have a chain link fence that abuts the top of the creek bank in their back yard. It has been there since they bought the house in the 70's. EVERY time the creek floods, at least part of the fence goes down. The debris does not just pass through, as you think it would for your fence.

With recent development in their town runoff volume has become a real issue in the creek. During creek restoration the city basically told them the fence isn't supposed to be there, but that they could keep it. But, the city would not be liable for any damage to the fence.

If you're worried about issues with fencing in the floodplain, you'd better stay the hell away from trying to regrade the damn thing.

7/11/2017 9:42:42 PM

mildew
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Quote :
" you're afraid to build a fence in floodplain without permitting, but you're OK with putting fill in a floodplain and then alerting a federal agency to the fact that you have done so?"


It would all be done at kind of all at once, engineer/survey/fill, then apply for removal of zone. The application even asks how much fill you've done. It's all odd like that.

7/12/2017 12:12:51 AM

mildew
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Quote :
"
what exactly would you consider a fair price for an engineer to prepare a variance for this fence?

"


I would think ~$1k. Already have multiple surveys and plans done, none of the surveyors have the specific engineer needed on staff.

7/12/2017 12:20:24 AM

JT3bucky
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Just build the fence, dont worry about it being flood plain.

Go about your life as normal.

7/12/2017 2:28:04 AM

FroshKiller
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seriously

shape the earth you live on, and to hell with the TAX MAN

7/12/2017 9:10:25 AM

robster
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just bury an electric fence to teach the dogs the boundary. Probably cheaper and just as effective.

7/12/2017 9:56:32 AM

eleusis
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Quote :
"I would think ~$1k. Already have multiple surveys and plans done, none of the surveyors have the specific engineer needed on staff."


A boundary survey of your property is not the same as the type of survey needed for a floodplain variance. Do you have topo data on your property and the adjacent properties surrounding the floodplain?

You're also either severely underestimating what an engineer's time is worth or severely underestimating how much work has to go into this if you think $1k is in the ballpark.

Quote :
"It would all be done at kind of all at once, engineer/survey/fill, then apply for removal of zone. The application even asks how much fill you've done. It's all odd like that."


You need a permit to put fill in a floodplain BEFORE you start any construction.

7/12/2017 11:26:46 AM

NeuseRvrRat
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How close are your neighbors and are they dicks? The only time I hear about folks getting busted for no permit is when neighbors call and report them.

7/12/2017 2:39:49 PM

eleusis
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^True. buildings sometimes get caught during updates to Aerial imagery and county GIS records, but a fence shouldn't be readily visible from aerial imagery.

7/12/2017 7:48:48 PM

mildew
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This is part of an overall new home construction and the fence will be a distant part of enclosing in the pool area, so permits are flying all around for everything and there will be inspectors out and about. No neighbors with any structures on adjacent properties. The closest neighbor wants me to do whatever I would like, no worries.

And yes, I do admittedly severely underestimate the value of the engineers time bc the quotes I have gotten are up to $8k to tell me if I can put a 50ft strip of aluminum fence in the corner of my yard or not. I understand it is not a standard boundary survey, the surveys I have had done do include the flood plain and certain elevation regarding it, but not enough. It's not a knock on the engineer to say I don't want to pay that much, but more of a knock on the bureaucratic process that is overbearing for such a minor item that is not worth that type of spend.


Anyhoozle.... thanks for letting me vent my first world problem and for the input T-Dub.

7/13/2017 10:29:25 AM

dtownral
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its minor for you, its not minor if everyone put up fences or structures that changed the floodplain and increased flooding in other areas


is the area visible? if not i would just put up a chickenwire mesh fence in that part and call it temporary and be done with it.

7/13/2017 11:55:35 AM

eleusis
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I'd consider the chickenwire option embedded into a hedgerow of boxwoods or something similar. Eventually the hedgerow will grow around the chickenwire and hide it from sight, and you shouldn't need a permit for plantings.

7/13/2017 12:48:30 PM

robster
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Yeah, and if there are enough trees in place, then you can use those as free fence posts for support.

7/13/2017 2:19:30 PM

darkone
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Quote :
"...but a fence shouldn't be readily visible from aerial imagery."


It would be easily visible. Have you looked as Google Maps? That's mostly aerial imagery. Commercial satellite imagery these days would have no problem either.

7/13/2017 3:29:36 PM

NeuseRvrRat
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once all the construction and inspections and junk is done, then quietly finish off the section in question

7/13/2017 5:30:30 PM

dtownral
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you can see a fence in aerial imagery but it wouldn't stick out enough for anyone at the city/county to notice and check. you adding a large parking lot or building may get noticed at some point, not a fence.

7/13/2017 5:46:42 PM

wdprice3
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what TerdFerguson said.

The reason such rules exist is because the idiotic notion of "it's my private property, I can do what I want" leads to you impacting other people's property and life. Say it floods, your fence gets damaged and washes downstream and clogs a culvert, causing flooding at the road, making it impassable, emergency services can't get through, and the water gets high enough to flood someone else's house. What you do on your property can and will affect others. Just having the fence in the floodplain cause also cause increases in flood elevations, hence the reason that jurisdictions ask for flood studies. Now, a small 50' long section of fence is likely to have negligible impact. But then it's your fence, your neighbors, and so on and all of a sudden, the fencing starts to have a measurable impact. It may only be tenths of a foot, but many jurisdictions don't want to take on that liability unless proper studies and procedures are followed.

Now, some jurisdictions (in NC, floodplains are mostly handled at the local level) don't care about fences; some do. Some want you to show that the fence is designed to withstand flooding. Some just want evidence of no-rise in flood levels. That requires modeling. While I haven't done this work for a fence, I have for other items and it cost about $40k to model (albeit, these jobs were much more detailed / complex than a fence). And that's with existing FEMA models. If FEMA doesn't have a model and the jurisdiction wants it modeled, you're looking at thousands of dollars. And if you want to fill in the floodplain, then you probably have to do a conditional letter of map revision (to explain and model what you want to do), and once granted you can place fill in the floodplain, and then you have to do a letter of map revision (second round of modeling based on as-builts). Needless to say, it's not worth it for a fence.

[Edited on July 14, 2017 at 12:45 PM. Reason : .]

7/14/2017 12:41:19 PM

TerdFerguson
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Yea, tell us the county and the stream name mildew. We can check the status of the model online, and maybe even see if other fences on the stream are modeled.

7/14/2017 1:35:26 PM

mildew
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Wake. Neil Branch (Basin 24, Stream 8)

[Edited on July 17, 2017 at 10:24 AM. Reason : Zone A]

7/17/2017 10:24:27 AM

wdprice3
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If you're located right at that intersection, your property may be within the model. The model extends about 300' upstream of West Spring.

that's a really odd intersection to model. I'm surprised FEMA even accepted the way it was modeled. Probably part of the reason that didn't do a detailed study of this portion of the stream and left it as Zone A.

[Edited on July 17, 2017 at 12:48 PM. Reason : .]

7/17/2017 12:47:25 PM

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