Pond Boss Forums GENERAL QUESTIONS Property Projects & Construction Building a small bridge in flood plain?

I want to build a bridge over a creek, it is about 40'-0" from edge to edge. Most of the year the creek is below the surrounding banks. But once maybe twice a year (depends on how much rain or snow melt) it does flood the surrounding areas but goes down within 2 days. I would like to make it 5' wide to drive an ATV across.

Is there any way to do this without having the bridge float away when the water floods the area?

thanks!

I had a 16' bridge of mine float away (made it out of 6x6's) when the 2" deep creek flooded. Freak of nature... anyway, in order to hopefully help this from never happening again, I fastened thick rebar to the side of it. I got some metal brackets to hold the rebar in place. Then I drove the rebar 4' into the ground. I don't know if it will work, but I sure hope so.

Can you build the bridge above the high water mark when it floods?

If not, I doubt that it will stay put as moving water has a lot of power to move stuff even when well anchored.

Sounds like what my dad did to bridge at his old pond. Steel t-posts driven almost all the way into the ground with steel cables anchoring the telephone poles that made up the base of the bridge, it still washed out and into the pond after heavy rains.

Luckily for me, mine doesn't have far to wash to. I'll just use a comealong to put it back in place. Fingers crossed it never happens again.

Took a derecho to raise the creek that high... my luck says it'll happen another two times while I live here.

Yea no place around to cross, further down stream two creeks merge and this is why it backs up and floods some times. I was thinking of building the bridge then putting 55 gallon barrels under it and put two steel cables and tie off to a tree, so this way when it floods the bridge will be on top of the water and anchored to two trees, but not sure if this would work or not.

How high do you think the water rises(or would lift the bridge)?

Do you need to drive across this when it's flooded?


My initial thoughts are you need certain points that keep the bridge up above water surface. If the wood deck is floating at water surface, you will get a tremendous amount of push from the water flow (and break your tie downs) and it will hang up all the debris floating down creek.

The barrels would work as long as it holds the deck higher than water level when flooded. But keep in mind, when the water recedes the barrels will rest upon the ground. I think they would get crushed when driving on them in dry conditions. You could possibly design some supports that the bridge would set back down on as the water receded and the barrels would then hang from the deck, then it might all work.

The water get pretty high in that area, I would not be driving on it when its flooded as there would be no way to get to it when it is flooded. I am just going to draw it up and attach it may be easier to under stand.

With semi-truck trailers at 53' in length, I'd bet you can purchase I-Beams long enough to span it. They won't float away.....

It'd just take some heavy equipment to get them in place tho!

Maybe elevate the bridge a few feet above ground level so the flood waters could flow under it. A ramp on each side connecting the bridge to ground level.

What I have seen done is letting the bridge float, but anchor only at one end so it can swing out of the main flow. Winch back into position when waters recede.