building a earthen bridge

[bx24]

For what it is worth, I would do this in your situation:

1- Make it only as high as is needed to clear the size pipes you use while at the same time making it a straight enough horizontal path so that you intended trailer etc won't hang up. The idea would be to make it usable while giving the moving water the ability to flow easily over the entire structure during heavy flooding

2- I would backfill the pipes with some sort of sharp stone (as opposed to smooth stone that won't bind on its neighbors)

3- I would cover the backfill (especially on the sides) with either geo matt or some sort of landscape fabric to hold things in place

4- Cover the sides with a significant amount of rip rap style rocks

5- Cover the top with your choice of gravel

What ever you decide, post some pics!

 

[patrick_g]

For what it is worth, I would do this in your situation:

1- Make it only as high as is needed to clear the size pipes you use while at the same time making it a straight enough horizontal path so that you intended trailer etc won't hang up. The idea would be to make it usable while giving the moving water the ability to flow easily over the entire structure during heavy flooding

2- I would backfill the pipes with some sort of sharp stone (as opposed to smooth stone that won't bind on its neighbors)

3- I would cover the backfill (especially on the sides) with either geo matt or some sort of landscape fabric to hold things in place

4- Cover the sides with a significant amount of rip rap style rocks

5- Cover the top with your choice of gravel

What ever you decide, post some pics!

If the above method is selected then consideration of how to protect the downstream side of the bridge is needed. The turbulent flow on the back side is extremely eroding and it is unlikely that geotextile will be sufficient in a significant overflow event. Also there will be no gravel on the roadbed after a significant overflow event and the surface will be eroded. Blacktop or similar would survive better.

It would be nice if there were a budget for some concrete work.

Pat

 

[Egon]

Do you have any idea of the rate of maximum water flow as this is the place to start from.

You may be better off by eliminating the culvert and going with a wet crossing that allows your equipment to clear under normal conditions. The actual crossing should have some piles with concrete facing and top with a well designed backside incorporating a hydraulic jump to eliminate washing out the backside. The upstream side could be protected by some of the numerous Vermont boulders.

Making a stream crossing should be simple but trust me, we can complicate it imensley!

 

[ore540]

a suggestion
Try the forest service website
out here they are always involved in maintaining roads thru the national forests and keeping them up for logging and general access.
it will take some wading thru their sites but the info is there
Don

I don't know the requirements for Virginia but there's been a big push out here in Oregon to revise the way culverts are being installed. They've found that a lot of culverts were blocking salmon, steelhead and resident fish from using the spawning beds in small streams. There's a replacement program going on and it's pretty cool to see the fish moving through the suburban, urban and neighborhood streams.

The Oregon Road/Stream Crossing Restoration Guide has some pretty handy but government-ese information. The whole guide is here and an appendix -- with more human language -- with guidlines and laws for things like how high above waterline the exit should be is at http://www.4sos.org/wssupport/ws_rest/OregonRestGuide/AppendixA.pdf

 

[JoeL4330]

Check out NCDFR - Access Road Construction: Design Guidelines

all aspects of buildin' your road incl. culverts

 

[patrick_g]

Joe, Thanks for the link. Great info!

Pat

 

[czechsonofagun]

Why not use concrete pipe with 36" opening? Than the dirt does not have to be so high.

That's one of the differences, in Europe they use concrete pipes all the time.

 

[gabby]

I've had my share of washed out culvert pipes. We've had at least three "100-year" rain events in the past 20 years. The amount of runoff was incredible. Trash and debris will obstruct culvert pipes every time and then they overflow and wash out the fill, and that's if the beavers don't obstruct it first.

I have a feeling there is no economical amount of culvert pipe that will withstand a flood in your situation.

You might have to just dump a bunch of rock in the creek bed and ford it.

 

[Kendrick]

the biggest question will be are trees going down that creek during a flood? even smaller trees will plug any culvert you got in a jiffy. where I used to live there was a creek that started ankle deep it had 2 20'? square openings and a 4 lane road over the top. I have seen a mess of trees left behind on the upstreem side and the watter roaring over the top of that road. that creek often dries up in summer.