Road erosion problem

[random]

So I'm trying to figure out the approach to fixing a problem with my road eroding.

I live about a mile off the pavement, with a dirt/gravel road that I maintain as the only access to my property. Last year, I had drainage put it that has helped prevent the big problems it used to have, with thick mud and massive ruts, but there is another problem that's been creeping up for a few years, and it's time to address it.

Part way down, there is a creek that passes under the road. It has a culvert that's been there for years, possibly decades - no idea how long. Most of the time, this is fine, but in heavy rain the road runoff cuts it a bit, and if it gets bad enough, we end up with the creek flowing (rather quickly) OVER the road, which I think is a big contributor to the problem.

So I'm looking for ideas on how to fix this before I don't have a road anymore!

Some pics of the problem - flow is right to left in all pics:

Where it goes under. You can see the erosion at the top where it's starting to cut into the top of the road.

Another view of that spot. The inner part of that crescent is probably a good 3-4 inches more worn that it was when we moved in (6 years ago) and it seems it's been getting faster. During heavy rain, the water runs down over this spot, and when it floods this is the spot that gets hit by the full rush.

Better view underneath where the water enters. I'm pretty sure the primary path is the one on the right, not sure where the one on the left leads, but I'm guessing they probably both go to the pipe, but that something ended up splitting the inflow.

Here's the outflow side. You can see the pipe where it discharges. The USUAL drop is about 2-3 feet when it's at the usual level. You can see at the right side of the pic the corresponding drop where the water crosses when flooded.

I have a couple thoughts on what to do with this but would like input from people who know more about it than I do before settling on an approach.

 

[old and tired]

So you have two pipes going IN but only one pipe OUT... I would figure that one out first.

Are the pipes filled with sediment? I would get those cleaned out with pressure hose (fire department need a "donation" in return for cleaning your pipes?)

Personally, I would extend the Inlet side pipe out farther, widen the road and pack the entrance with large rocks to prevent washouts. Your outlet pipe looks to be long enough, just packing rocks and clay to hold them in place...

I would also, dig a pit in front of the inlet side so you have a place for sediment to settle in vs. having it settle inside the pipe.

 

[RCW]

random - -

I'm little more than a redneck/bar napkin engineer, so my advice isn't worth much. There are some bona fide engineers on OTT.

Looks like heavy rains top your pipes and crosses the road, eroding both upstream and downstream sides?

Is that 2 culvert pipes at 24-36"..hard to tell? What are they made of... concrete, corrugated metal, welded or riveted steel, plastic? Looks like you get some back-up at the space between the 2 pipes?

Existing pipe sizing will be important for an informed repair/replacement.

My first thought is rip both them puppies out in favor of a single tube. Given geometry, the volume of a single tube of a marginally larger-size pipe than 24-36" (guessing) will greatly exceed the volume of the two pipes you have now. It will also eliminate the back-up issue between the two you have now.

Some of the smooth-bore plastic pipes move water more efficiently. Same with a concrete box culvert type design.

i would extend the inlet and outfall another 10'+ if possible. Sounds like you own the road and both sides of it?

Again, my advice plus $2.04 will buy you a medium coffee at my local convenience store......(Medium coffee is $2.04.... )

 

[Lil Foot]

My first thought is rip both them puppies out in favor of a single tube.

My thoughts exactly. Either large round metal culvert, or an oval metal culvert. I used oval on mine, less height but more width. I would also use a longer pipe, extending further out end side, and pack it in with rocks or lots of riprap.

I would also, dig a pit in front of the inlet side so you have a place for sediment to settle in vs. having it settle inside the pipe.

Also a great idea. I dug a pit at the inlet of the county culvert that dumps runoff water onto my land and then under my driveway.

 

[Lil Foot]

Here's a couple pics of the county culvert near full of sediment.

 

[RCW]

Here's a couple pics of the county culvert near full of sediment.

CMP is prone to attract sediment. I've found the smooth-bore CPP to be real slick - doesn't hold the sediment as much.

Your place in AZ is dry 360 days a year, then gets inundated. Not sure either matters in your application..

I know you've fought with it for years, and it looks like you've got it now with the better flow through the pipe that will scour the crud outta there.

 

[skeets]

random I dont kow where you are, but if you are in an area that has shown gold,,, check out the riffles in the pipes if theres any gold inthe them it might just pay for the whole thing,
But really I would start down stream and start cleaning out the out flow first and work your way up. At least get her open till you can get in with equipment and rip it out and like the man said 36 inch pipe and make an inlet with rock to direct water INTO the pipe,, just my 2 cents

 

[Lil Foot]

CMP is prone to attract sediment. I've found the smooth-bore CPP to be real slick - doesn't hold the sediment as much.

Your place in AZ is dry 360 days a year, then gets inundated. Not sure either matters in your application..

I know you've fought with it for years, and it looks like you've got it now with the better flow through the pipe that will scour the crud outta there.

The culvert plugged up because the phone company trenched through it and laid two cables in it, creating a "snare" that caught rocks & stuff until it plugged. Once I got them to clear the cable, it washed clear in about 18 months. Of course, all that sediment went into my water course & had to be cleared, but it's all good now.

 

[mikester]

Here's a couple pics of the county culvert near full of sediment.
View attachment 51668 View attachment 51669

Those are the spring overtime specials for the county workers. Why fix drainage problems in the summer when you can get double overtime trying to get enough flow to clear the flooding on the roads with the steam torpedos.

 

[D2Cat]

random I dont kow where you are, but if you are in an area that has shown gold,,, check out the riffles in the pipes if theres any gold inthe them it might just pay for the whole thing,
But really I would start down stream and start cleaning out the out flow first and work your way up. At least get her open till you can get in with equipment and rip it out and like the man said 36 inch pipe and make an inlet with rock to direct water INTO the pipe,, just my 2 cents

Skeets, just a bit of information. If you put your mouse on the moniker of a poster you will see some information which often has the posters home location.

 

[Lil Foot]

Those are the spring overtime specials for the county workers. Why fix drainage problems in the summer when you can get double overtime trying to get enough flow to clear the flooding on the roads with the steam torpedos.

The city of Flagstaff is in the same county as my place in the high country, (Coconino) and the county has (2) decommissioned fire trucks there they use for blasting culverts clean- but they won't drive them the 75mi to our area, so we have to rely on monsoon rains. (or NONsoon rains in this years case)

 

[random]

Far as I can see, there is one pipe, maybe about 18" (maybe 24? I haven't measured, probably should). It appears to be clear of sediment for the most part at least, I'll check more on the inlet side.

It looks to me like the inlet side has two openings because something is blocking it partly.

I am VERY reluctant to dig it up, because it usually works ok, and it's my only way in or out, so if I screw it up I'm in a hell of a bind. There are two types of erosion - one is runoff from the road onto the upstream side, the other is when the creek starts to flood that ends up running over the road. Erosion on the downstream side isn't that bad and I have a LOT of extra room before it starts hitting the road, it's the upstream side I'm most concerned about.

My thought was to extend the inlet side, maybe try to open it up some first, and build things up on that side with some rock and maybe something like decomposed asphalt that will lock things in. But still considering options.

Maybe a full replacement is the right approach, but if I do that I may just hire someone with more experience instead of doing it myself.

Doubt there would be any gold - pipe appears to be smooth.

Thanks for the replies. A lot to consider here.

 

[PoTreeBoy]

1. Figure out what you've got. Clean out inlet with backhoe, shovel, hoe, etc. Is there one pipe or 2? I see pipe on outlet, but I don't see pipe on inlet, just dirt. If there's only one pipe, where does that other hole go?
2. Assuming pipe(s) come out to or past edge of the road, you could stack 4x6's on edge on top of the pipe, parallel to the road. Go up maybe one above the elevation of the road to form a curb. Drill and run rebar or equal through to hold in place. This would form a retaining wall at the road.
3. Similarly, use 4x's on each side of the culvert, starting at or slightly below the bottom of the pipe(s), to form a wing wall to hold the ditch banks back. Flare (angle) them out from the pipe end and make them progressively shorter to make a gradual entrance. You can also get culvert flares like this:



If the pipe doesn't come out to the road, you'll need to extend it. Make sure you keep the joint smooth so it doesn't catch debris. Ideally, the pipe would stick out far enough to allow about a 2-1/2hor:1vert slope so the dirt would stay in place. Then you could just cut the pipe off at an angle. But the flare still flows better.

 

[skeets]

Skeets, just a bit of information. If you put your mouse on the moniker of a poster you will see some information which often has the posters home location.

Ahhhhh soooooooo