Culvert Issues, help!

[HawkinsHollow]

I have a small stream on my property that I was not able to cross due to it being too steep and deep. I decided to put a culvert in. Fast forword a few years and I think I am regretting my decision. You see this area on my property is along a creek and floods 1-5 times a year. To exacerbate this issue, this culvert is basically at pond level. I think what is happening is as a flood is happening the first step is water is coming through this area with quite a bit of force. By that time the pond level has raised a bit and water cannot and does not flow through the culvert it flows over it, washing away the dirt covering it.

In hindsight I think a crossing would have been better. And that is the direction I think I might take going forward. I was thinking about taking 2 or 3 4" pipes and putting them in the concrete pipe. After that crushing the pipe to make the majority of the crossing and then sloping each side accordingly. The 4"ers will allow the tiny trickle of water that is going thru this area 99% of the time to come thru. Is that a fools errand? Are these pipes just going to clog? I think I already know the answer to this. My other idea was leaving the pipe but armoring the area better with concrete chunks and hoping that holds the dirt in place. How would you proceed?

 

[HawkinsHollow]

Ok, I have another idea. What about leaving the bottom third of the pipe in place. Filling it with the rubble, allowing water to flow through. Then sloping either side appropriately and armoring with concrete chunks.

 

[thclimer]

I think you would be better off removing the culvert and trying to harden the area where it was. Either pouring concrete or with large sone. Something like in the picture below but no where near as elaborate. It would allow the water to flow over it but also a hardened surface that allows you to cross it and if there is a huge flow it doesn't get washed away:

 

[HawkinsHollow]

I think you would be better of removing the culvert and trying to harden the area where it was. Either pouring concrete or with large sone. Something like in the picture below but no where near as elaborate. It would allow the water to flow over it but also a hardened surface that allows you to cross it and if there is a huge flow it doesn't get washed away:

View attachment 3191602

Yep! I think that is the plan. That is what I should have done in the first place. Live and learn!

 

[EddieWalker]

If it was my place, I would keep that culvert in place and build up the entrance to the pipe with sacks of concrete. Just stack them dry so the water cannot get around the pipe, and then hammer some rebar through the sacks to lock them in place.

Then I would do the same thing at the exit side of the pipe. This should hold your material better when the water overflows the pipe.

Instead of using dirt over the pipe, I would get the largest crushed concrete that I could find and build up the road over the culvert with that. Once compacted, the crushed concrete should lock together and allow water to flow over it.

If I was getting really crazy, I might even add a few sacks of Portland Cement to the crushed concrete with some sand and work it into everything to make it even stronger.

 

[newbury]

You need an "emergency overflow".
How important is it to get across the stream? And what is the flooding like?
Do you need to be able to rescue someone on the other side? Or can it wait a few days or weeks?
The soil pictured has a lot of "fines", these settle in slow water. And clog culverts.
And Eddie is spot on. Block the flow, make it go elsewhere
It looks like you have a good culvert. If you can create a shallow ditch a ways off to the side of the culvert that handles the storm overflow it should handle the

5 times a year

major flows. This was a common practice for "farm" ponds when I grew up.
Good luck.
Keep us posted please.

 

[scootr]

Yep! I think that is the plan. That is what I should have done in the first place. Live and learn!

Live and learn beats the hell out both the alternatives this saying suggests

 

[turkish]

I have a small stream on my property that I was not able to cross due to it being too steep and deep. I decided to put a culvert in. Fast forword a few years and I think I am regretting my decision. You see this area on my property is along a creek and floods 1-5 times a year. To exacerbate this issue, this culvert is basically at pond level. I think what is happening is as a flood is happening the first step is water is coming through this area with quite a bit of force. By that time the pond level has raised a bit and water cannot and does not flow through the culvert it flows over it, washing away the dirt covering it.
View attachment 3191564
View attachment 3191565
In hindsight I think a crossing would have been better. And that is the direction I think I might take going forward. I was thinking about taking 2 or 3 4" pipes and putting them in the concrete pipe. After that crushing the pipe to make the majority of the crossing and then sloping each side accordingly. The 4"ers will allow the tiny trickle of water that is going thru this area 99% of the time to come thru. Is that a fools errand? Are these pipes just going to clog? I think I already know the answer to this. My other idea was leaving the pipe but armoring the area better with concrete chunks and hoping that holds the dirt in place. How would you proceed?

Small pipe or several smaller pipes is a fool’s errand. If you want a culvert, you need a much bigger one. I’d get a larger culvert, sized according to the actual acreage and vegetation upstream, or try to maintain a low water crossing.

 

[dodge man]

It’s pretty simple, like @turkish said the pipe isn’t big enough. Either a bigger pipe or build a wet crossing.

 

[paulsharvey]

So, it looks to me, the invert of the pipe is a bit high, but it is what it is. You need to make a head wall, metered end, u-wall, or similar end treatment on the pipe. It can absolutely be as Eddie said, dry stacked quikcrete bags, vertically, at the end of the pipe sides. To stack vertical, if needed, you can drive rebar stakes to allow you to stake them better. Go atleast two or three bags on either side of the pipe, tightly fitted to the pipe, and keep stacking until your atleast 12" above the pipe. I would mortar the "annular space" (the gap between the bags and the pipe).

 

[paulsharvey]

The 2 or 3 4" pipes is a bad idea, dont do it.

Im assuming the RCP you have in place is 15 or 18" round RCP. Thats like 20x the capacity of a few 4" pipes.

 

[paulsharvey]

Once you add the bag headwall; you need to add addional fill on both sides. It looks like even 5 ft away, your approaches are maybe half way up the pipe. Ideally, the pipe invert sits at the flow line of the creek, then atleast 12" of coverage over the top of the pipe. Headwalls up to the driving surface, extending atleast 18" min on both sides of the pipe.

It looks like a swampy area right now; but if you have a situation where the water raises 24" in an hour, we really need to start thinking 36"+ on the pipe. Swampy areas generally dont get that flash flood type water movement, but I dont know your area

 

[paulsharvey]

On pipe sizing... So, if set at the flow line, in normal weather, you want no more than about 1/4 of the pipe diameter flowing water; that gives you about a good bit of added surge capacity for storm events. If the pipe routinely flows at 50% diameter or more, you have nothing left for storm events/surge.

 

[paulsharvey]

So, I went back and looked at the pictures a bit closer; but correct me if wrong.

So, the upstream end does have a cast in place headwall, the pipe is in the center of a stream, but the 30 or so feet left/right is flood plain of the creek? With that, the goal, im guessing with the pipe elevation is to have a year long pond across the flood plain, up stream of the pipe, and the pipe is meant as a control structure. Looking at the weeds/grass that appear pushed over, during heavy rain events, the entire flood plain is flowing.

So; if that is right, we mostly need to focus on 2 things. #1 is a Whole lot more fill: compacted and then the slopes stabalized with grass. #2 the pipe is serving as a bleed down, but we need a true over flow.

So, typically, you would have a small bleed down orifice, and then a much larger overflow. I would build the entire bankment up, probably 24-30", with well packed material; and pick one area, about 12 ft long, off set from the pipe, and leave it about 12" lower then the general embankment. That serves as the true over flow. It will need armored; with rip rap, soil cement bags, crushed ruble, geo rid, fabriform or similar, because that water, when it reaches over flow point, will have velocity.

 

[RayIN]

Present culvert is undersized IMO. A larger diameter will allow it to be lowered to allow water flow while maintaining the height of the banks.
That said, a drive-through will be better, if made correctly.

 

[HawkinsHollow]

There is a cast in place headwall on the upstream side of the pipe it could probably be wider. At high water it is going around it. Yes, there should be more fill over the pipe, but fill is hard to get to this location. This whole areas is under 2 or 3 feet of water when the creek overtops the banks. I think as it is getting to that point this somewhat dry creek becomes an overflow and moves quite a bit of water. This is when the damage is happening. I am chalking it up as a failed attempt and will be making a crossing there when I have time. Plan on using the rubble from the pipe to armor the crossing.