Clearing Clogged Culvert

Dmace · Mar 1, 2006

( The thing about that sediment trap hole is that you'll need to clean it out with the hoe pretty often. )

Don't think of it as a "hole" since it will mostly be filled with rock and only about 6"- 1' deep depending on the size rock you use. The sediment will somewhat settle in the rocks but flow of water will clear it out. The rocks just act as a restrictor that will only allow some sediment through at a time. This type of drainage setup will not need to be cleaned out. Especially after a heavy rain.

rox · Mar 1, 2006

Thank you for your reply. I will always remember your advice.
I don't have the issue right now, but we have plenty, plenty of concrete drainage pipes thoughout the property. I earned something fomr you, hey thanks! /forums/images/graemlins/cool.gif

LBrown59 · Mar 3, 2006

I like to dig a hole upstream as a place for silt to fall out of the incoming flow before entering the pipe.


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That's what I do on all my culverts

LBrown59 · Mar 3, 2006

( One of my culverts clogged up completely. The culvert is 12" diameter, 1-½ years old, plastic and corregated inside. It's about 30' or 40' long. I don't think the road guy set this one on enough slope to accellerate water flow through it so the dirt has settled and plugged it up. I'd like to re-set it but need to clear it first.

I think it's mostly silt & dirt because I was able to poke a hole through the clog with 20' of pvc pipe. (near the top of the culvert). Then attached a wire and finally a chain to it so I pulled through a small piece of steel with the tractor. Made only a tiny hole. Also don't have ANY water at the culvert to try to flush it out. I thought about getting a fire truck up to the property and use their high pressure hose to squirt the debris out the other end, but don't know yet if they'll do that. So I'm asking here first.
How do you clear it?

Attached is a picture of how much silt and dirt was washed off the new dirt road, clogging the culvert. You can barely see the edge of it in the lower right hand corner of the photo.
)
 The culvert is 12" diameter, 1-½ years old, plastic and corrugated
*the dirt has settled and plugged it up 
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This is also the problem with corrugated steel pipe.
Double wall smooth boar plastic solves that problem.
~~~~~~~~~Several years back I replaced the rusted out 12" corrugated steel driveway culvert.
The state Required I install 15'' Double wall smooth boar plastic culvert.
Told me If it ever plugged up they would use their special machine to clean it out.
That's why they wanted me to use Smooth Bore Plastic because the Machine will tear up the corrugated stuff.

3RRL · Mar 3, 2006

Considering I was able to pull a chain through mine, if it was a smooth bore I could very well have used a 4x4 attached to the chain and pulled the plugged up stuff out. As it was corregated, no chance of that!

That whole day was shot trying to unplug it, and fixing my Blazer /forums/images/graemlins/mad.gif

marks · Mar 4, 2006

I too have had similar situations, and as the others have pointed out proper fall provides the velocity necessary to keep the pipe clear. In your situation rip-rap on the intake side is necessary, regardless whether the pipe is reset or not. Resetting that length of pipe will take some work, hence you may want to try some alternatives prior to taking that step.

Not knowing the configuration and so forth, the idea is to minimize the sediment entering the pipe, and maintaining the velocity. Assuming that you have a long term perspective on the deal, determine the origin of the sediment, then plant ground cover to reduce the erosion, or divert the flow upstream to some other area. (Rosemary is a fantastic for errosion control, drought tolerant, deer resistant, and cheap). I also assume that a 12" culvert is adequate for the flow.

That said let's think about allowing the sediment to pool and settle upstream (in an area that can easily be cleaned) prior to entering the culvert. Much like the baffle in the septic tank allows the solids to settle and the clear water to flow. If a dam could be made with an overflow discharge pipe then we've accomplished this task. A dry-well setup may also be feasible.

For the swale between the discharge pipe and the culvert, consider using a geotextile fabric, aka weed mat. This is great stuff, the water stays on top of fabric, and protects the soil below it. After overlapping the fabric and stapling it down, use a small rock to protect it and it will NOT reduce the velocity of the water. I use 1 1/2" river rock, its large enough that the water won't move it, smooth enough that the water can easily ride on top of it, and easy to work with. You may need larger rock for the sides of the swale.

It's unfortunate that there isn't any water available. What would it take to bring water there, 1000' of garden hose, a temporary basin, ten drums, a water truck, dam it up now and collect the water, portable pumps - I don't know. While compacting a 1/2 mile long trench I used several 1000' rolls of drip tubing, granted the flow wasn't great, however time was on my side and the tubing was later used in the irrigation system.

Assuming that water is brought to the site, I submit the following observations. For each foot of clogged pipe there is .75 cu. ft. of material. A fire engine carries between 500 -1000 gallons, CDF engines are more like 500. A 1" hose flows 40 gpm, 1.75" 100 to 200 gpm. Injecting water on the discharge side will be an extremely muddy affair, and and only so effective. Think about a garden hose stream pointed into the ground, it doesn't take long until the water that's accumulated in the hole, absorbs the energy from the water entering it. For crude horizontal boring I'll strap the nozzle and hose to a pipe or rebar in order for the nozzle to stay in contact with the soil. CDF doesn't have such a contraption, and overall they might be reluctant to subject their equipment to such abuse. The nozzles are expensive, and purchased with tax payers $ - sensitive topic. Another CDF consideration is the travel distance to refill their tank, what if an alarm comes in and their tank is empty?

Approaching the culvert from the intake side is much cleaner, but with it being so clogged any large flow of water will also make a mess. Consequently a slow flow would be in order.

In conclusion, the water availability will determine the approach. If gravity fed, or low psi, then work from the intake side using a long 2x4 or pipe to assist the water. If high pressure water is available then a garden hose attached to a 3/4" copper pipe with a nozzle might be quicker and more effective.

In any event send a PM, I'm interested to know how things turn out.

It appears that CDF provides your fire protection

3RRL · Mar 5, 2006

Thanks Marks,
Very informative post. It will be 3 weeks before I head back up to the property and see a lot of rain between now and then. I hope it hasn't got worse by then. I'm thinking of running water down there to deal with it. I'll need to do that sooner or later anyway.

willfick · Mar 7, 2006

I have a similar problem with the culverts at the end of my driveways. The county's sand wants to always fill them when we get a hard rain. If I dig out enough of a ditch to let the sand flow it ends up in my woods. Or my neighbor's woods. He doesn't want it, either.
I have to have a sump on the downstream side. If I keep it dug out the culverts stay clear but one hard (2 inches in an afternoon) rain and they're plugged. Even then if I get the hole dug out that day there's enough water in the sand to make it flow. Let it go any longer and, well, I'll show you a picture...