Culvert maintenance?

[In.the.Piñons]

I've got six smaller culverts (10-12") and four larger ones (eyeballing them at 3-4ft) on my property.

They are all clear, but I was thinking about putting some galvanized chain through them and anchoring it at both ends with some rebar. The idea being that if it gets jammed up, I can pull a tire through.

Anyone else do this? Seems like it would be a pitta to get a culvert unclogged if you didn't already have the chain there ready to go. What sized chain did you use?

 

[dodge man]

I’m of the school “if ain’t broke don’t fix it”. I probably wouldn’t do that unless you start to see them plugging up.

 

[ponytug]

Unless I knew a lot about how the culvert was installed, and what condition it was currently in, I wouldn't do that. Leaving a chain in is just asking for extra wear and corrosion in my book.

All the best,

Peter

 

[Gee Ray]

I’m a tightwad. I wouldn’t invest that much money into chain just to have it lay around. Instead I would. salvage some old waterline (pipe) that I could drive through a culvert that is plugged and use it to pull the chain through.

More importantly, I would maintain the drainage side of the culvert so that the water can run through and avoid the plugs all together. Might also require some maintenance on the uphill side to eliminate things that might plug up the culvert.

An ounce of prevention is worth a pound of cure.

 

[Thomas]

Neighbor uses old guard rail cable and fasten tire to cable,with good rain he'll pull the tire thru couple times before water freezes.

 

[Too many Kubotas]

Not sure what I'm doing wrong, but while I understand why silt settles in the culverts when I mostly block them (to use the water for irrigation), I don't understand why the silt doesn't wash away once the gates are opened again.

Basically, the mound inside starts about a foot behind the gate, then ends maybe two feet from the end of it.

Any ideas, please?

 

[ponytug]

Not sure what I'm doing wrong, but while I understand why silt settles in the culverts when I mostly block them (to use the water for irrigation), I don't understand why the silt doesn't wash away once the gates are opened again.

Basically, the mound inside starts about a foot behind the gate, then ends maybe two feet from the end of it.

Any ideas, please?

Short answer is water velocity and how the speed greatly affects the amount of sediment that can be carried.

When the water is shallow, and moving quickly, the sediment load varies at somewhere between the velocity to the fourth and sixth power. However, once there is a barrier, e.g. your mound, the water slows down and drops at least some of the sediment it has, so your mound becomes self sustaining.

However, that is a gross oversimplification because a great deal depends on the density of the particles, their cohesiveness, and their friction with the channel bed as well as the water velocity.

Cutting a channel through the mound would increase the water velocity, and remove some (more) sediment.

Lots here if you are curious;

https://web.eng.fiu.edu/arleon/courses/Open_Channel/Lectures/Sediment_Transport.pdf

All the best,

Peter

 

[CalG]

Short answer is water velocity and how the speed greatly affects the amount of sediment that can be carried.

When the water is shallow, and moving quickly, the sediment load varies at somewhere between the velocity to the fourth and sixth power. However, once there is a barrier, e.g. your mound, the water slows down and drops at least some of the sediment it has, so your mound becomes self sustaining.

However, that is a gross oversimplification because a great deal depends on the density of the particles, their cohesiveness, and their friction with the channel bed as well as the water velocity.

Cutting a channel through the mound would increase the water velocity, and remove some (more) sediment.

Lots here if you are curious;

https://web.eng.fiu.edu/arleon/courses/Open_Channel/Lectures/Sediment_Transport.pdf

All the best,

Peter

When setting drain pipe, "Self scouring" is the goal.

1/4 inch per foot? Or something like that. I don't recall at the moment.

 

[dodge man]

If the culvert has enough grade it will be self cleaning but you to look at the ditch also. It doesn’t do any good if the grade is theoretically enough to keep the culvert clean if the ditch is so flat the water won’t flow fast enough downstream from the culvert.

 

[woody]

every so often I will scope out a 6 to 12 inch hole at the inlet, water fills the hole and drops it's sediment and moves on, depends on how much sediment as to how often you have to do it. I may only do it once a year so it's not a big deal

 

[Too many Kubotas]

Cutting a channel through the mound would increase the water velocity, and remove some (more) sediment.

Thanks, Peter. That's one approach I did try...with limited success.

One problem is that being part of a many miles long irrigation ditch, and being at the end of it, not only is the grade minimal but the amount of water and silt varies greatly depending of what people upstream are doing.

Obviously I can't do anything about the grade, or much about the flow. This year has been quite good, but last summer I could tarp off the ditch completely, yet the water only made it 15-20 feet from the ditch. There are other issues I can't do anything about, after the ditch goes onto the neighbor's property, but this culvert thing I should be able to overcome. Somehow.

 

[paulsharvey]

I think we are fighting the fire after is is already burning; instead of avoiding it to begin with. Our first step is to avoid getting sediment in our ditch to begin with. That'd not completely possible, but we can use control measures to greatly reduce it;
silt fence when we clean the ditches,
ditch blocks to control the speed of our discharge, and with that, allow sediment to settle out in easily cleaned areas, and avoid any bear soils;
we want our ditch slopes to have vegetation.

 

[paulsharvey]

Generally, we want our ditches and culverts to be sized so that we don't have water at a velocity that causes uncontrolled erosion, leading to the sediment deposits in the pipes. In about 20 threads per year, culverts come up as a topic; we want culverts sized to handle our flood events, not our day to day rain events; we don't want 4/6/8/12" pipes. They are a joke; when talking about culverts, we really should start the conversation at 15", and move upto 18"/24" as necessary; and when we talking about creek crossings, we might need to talk about 30/36/48, or multiple 24s.

Our ditches/swales; we don't really want a true V, as that leads to increase velocity as our ditch flow increases; ideally, we want maybe a 4:1 slope, then a 24" flat or rounded flow line.

I know this is difficult or impossible in some terrains, and soil types,

 

[paulsharvey]

Too Many Kubotas, have you considered adding silt fence upstream of your culverts? You would still need to clean the sediment out captured by the silt fence, but it is captured in an area that far easier to deal with. Also, should help any irrigation pumps, and improve water quality.

 

[oosik]

I have one culvert on my driveway. I know for sure, 100% - there has never been a drop of water flow thru that culvert. It was required by the county when they issued my driveway permit.

Anyhow - about four years ago. Went down off the driveway to have a look thru this culvert. Down on my knees - hunched down.

What a surprise. Looking right into the face of a raccoon. He was about three feet down the culvert. Apparently - this was his home or a quick by-pass from one side of the driveway to the other side.

 

[MAX-24-Dean]

The corrugations on the culvert wall with at least 12 " of fill should create enough resistance (soil friction) be able to hold the culvert inplace to pull a tire through that is not more than the diameter of the culvert itself.
I have one culvert I pull through once a year using this method. I just have to pull the tire through twice to get it clean. It is a very easy pull with the diameter being the same as the culvert.

 

[Too many Kubotas]

Too Many Kubotas, have you considered adding silt fence upstream of your culverts? You would still need to clean the sediment out captured by the silt fence, but it is captured in an area that far easier to deal with. Also, should help any irrigation pumps, and improve water quality.

I'll have to look into what a silt fence is, and how it operates.

No real need to worry about pumps. Have only use a semi-trash pump one time, to get water on an area on the "wrong side" of the ditch.

Of course, I also create my own silt when cleaning the ditch out, generally with a 24" bucket, but lately also with a 16", or even a 12". There are stretches when it can't be straddled with a backhoe, not even a small one.

I need to go check the other culverts a bit more closely next time there's little or no water in the ditch. There's a total of nine culverts along the main ditch, but this particular one is the only one I've seen buildup in.

And I don't even want to know how much there might be in the 80 something foot long one behind the house. There's either something in there, or the inlet is a bit lower than the center of it, which is fully possible.

 

[paulsharvey]

Silt fence is the black woven fabric with attached wooden stakes you see every where on construction projects. It's designed to allow water to flow through, but capture larger sediment (sand, some silt), but it doesn't prevent turbity very well, and clay particles are too small to capture well. It is Not a permanent product, it's suppost to last 12 months or so, but I'm thinking 8-12 ft across the ditch, maybe 20 ft upstream, would work for you.

You would basically install when water levels are low, there is a 'flap' that gets trenched 6" in, and then back filled, with the stakes on the down stream side. Once it gets about 1/3rd covered with sediment, you would demuck it, and basically trash that 10 ft of fence, and install a new piece. There is also heavier duty stuff with a hog wire backing, but that's over kill. There is also yellow, staked turbity barrier, which is beyond what you need, that's to keep turbid water from entering the down stream water (more an environmentally thing than a practical thing).

 

[In.the.Piñons]

Wow, lots of knowledge on this forum, so thanks for all the replies.

The culverts were put in (professionally) about three years ago, before we bought the property, so they are in great shape (at least to my untrained eye). 99.99% of the time there's no water flowing in any of them.

I'm not worried so much about a partial blockage, but we can get flash flooding here in the high desert and I'm concerned about a 100% blocked culvert that gets packed with silty clay soil from a single downpour.

However, I'm not sure how likely this scenario is to unfold. Sounds like I'm over thinking it!

 

[paulsharvey]

Wow, lots of knowledge on this forum, so thanks for all the replies.

The culverts were put in (professionally) about three years ago, before we bought the property, so they are in great shape (at least to my untrained eye). 99.99% of the time there's no water flowing in any of them.

I'm not worried so much about a partial blockage, but we can get flash flooding here in the high desert and I'm concerned about a 100% blocked culvert that gets packed with silty clay soil from a single downpour.

However, I'm not sure how likely this scenario is to unfold. Sounds like I'm over thinking it!

Those type of soils very well might be erosion prone. I think you mentioned a fair bit of rock in your area; you can dry stack maybe 6-8" of rock across your ditches, think mini, loose rock 'dams' or ditch blocks, that will slow the velocity a bit, but also catch heavy sediment, for future clean up, at an easier place than in the pipe.