Clearing culverts

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6 years 8 months ago #535343 by Hawkspur
Clearing culverts was created by Hawkspur
Has anyone used a waterblaster or fire hose pump to clear partially blocked culverts?

We have some culverts that are partially blocked with sand and stones, some of which are cobble sized so up to around 150mm.
The culverts are large enough to crawl through when clear, but have only about 100-200mm clear at the moment.

We are debating the approach to use. Suggestions have included:
- digging with various hand tools - works for mud and silt, but not easily with cobbles, and is a lot of work, and needs the water level to drop to summer levels to give access without a snorkel being needed!
- waterblasting - great for moving silt and gravel, but needs a clean water supply, might not shift cobbles
- fire hose pump - might move heavier stuff, but needs a lot more water, but might cope with dirtier water

One issue is the water available on site is currently very silty.
We can bring in a bit of clean water but not more than about 1500L easily

We would be hiring the pump/waterblaster so don't want to choose the wrong tool

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6 years 8 months ago #535344 by Ruth
Replied by Ruth on topic Clearing culverts
I'd try dragging a brick or something through, which would bring with it a lot of the blocking debris. How long are the culverts? Tie a long bit of string/strong cord to a float, send it through, tie chain or whatever else you might tie to the brick through next, then drag the brick. You might end up with a stuck brick but you'd be not too far worse off than now. It sounds like fun to me!

We have culverts which are filling with silt but if you clear the larger debris, the silt clears as water flows through - and if you block the lower end a bit for a while, you can create more flow to carry it out.

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6 years 8 months ago #535352 by LongRidge
Replied by LongRidge on topic Clearing culverts
I have had some success with a long length of steel water pipe, about 50 mm diameter. Push the pipe up from the downhill side and move it around. After some of the rubbish has been removed by water flow, block the inlet with a removable blockage and stir up the silt and rubbish with not much water flowing. Then remove the pipe and remove the inlet blockage so the water rushes through.
Then use the pipe as a probe/prodder on the inlet side.

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6 years 8 months ago #535409 by Hawkspur
Replied by Hawkspur on topic Clearing culverts
Thanks for that. We have tried digging. It helps with the silt and smaller stuff, but just at the moment you need to stand right in the water to reach so that approach can wait till the water level is lower and the temperatures are higher.

We had to make a tool to reach in because there isn't a straight line access at either end and the culvert is longer than the length of tool you can get in. We made a digging tool with lengths of handle that thread on to extend it, but there's not enough leverage to shift the larger stuff, which is why we were considering water with more power assistance.

I think a brick would just bounce off the rocks in there, because the tool isn't budging them. I thought waterblasting might loosen things up by stirring up the silt wedging things in but maybe not.

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6 years 8 months ago #535410 by tonic
Replied by tonic on topic Clearing culverts
We had a culvert filled with willow roots and mud so that only the top 1/5 or so was allowing water through. This caused a swamp to form on the upstream side. My husband made a tool, like an oversized metal rake and placed it on the up stream side. Then sent a rope through the culvert and tied it to the tractor, which was several meters away and not in a straight line. We dragged it through a number of times and each time pulled out more roots until it was clear. It was fiddly but very satisfying when a decent clump was ripped out and the water really started to flow.

Maybe something similar would pull the rocks through?

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6 years 8 months ago #535417 by Hawkspur
Replied by Hawkspur on topic Clearing culverts
There is no straight line of travel in line with the culvert. It is at the bottom of a tight little valley and the stream either side of the culvert goes around great big rocks, trees, and steep banks with inconvenient bends.
The only motorised vehicle route is across the culvert. So, unfortunately pulling things though, (other than by hand, or through a complicated pulley arrangement), isn't an option for this blockage.
With some scrub and tree clearing work a trail bike would possibly get a short straight line, but even a quad would require a lot of earthworks.

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6 years 8 months ago #535421 by Rokker
Replied by Rokker on topic Clearing culverts
I'm starting to think you might be better off just getting a digger in and lifting the pipe, then you can clean it out and re-lay it. Might cost you a hundred bucks or so for the digger but could be a whole lot less effort and time.

Do NOT cross this paddock! ... Unless you can do it in 9 seconds, 'cos the bull can do it in 10!

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6 years 8 months ago #535427 by Hawkspur
Replied by Hawkspur on topic Clearing culverts
The pipe is actually two, big, steel pipes, concreted in. I hope that we don't have to resort to removing them!

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6 years 8 months ago #535430 by Bamboo
Replied by Bamboo on topic Clearing culverts
A little bit left field but have you thought about compressed air? You would need to hire a commercial air compressor, not one you would use for airtools. Because you don't have a straight line the hose is flexible and will go around the bends in your pipe, air will shift all the issues you have mud, silt and the loosen up anything holding the larger cobbles. The level of water that you already have in there should help to clear it all once you loosen it as well. Any of the bigger stuff you could wait for summer and water levels to drop and get in there and drag them out. Just a thought.Cheers

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6 years 8 months ago #535441 by Hawkspur
Replied by Hawkspur on topic Clearing culverts
I hadn't thought of that. Thanks for the suggestion.

Yes, It will all be easier once the water level drops. The problem is that if we get heavy rain, because there is little free space in the culvert, water runs over the top and is scouring out the track surface, and we are still without a 4WD so have been stuck unable to go anywhere a couple of times.
Fingers crossed to find a replacement vehicle soon.

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6 years 8 months ago #535461 by Muz1
Replied by Muz1 on topic Clearing culverts
www.ipmofnh.com/2011/03/06/how-to-build-...spade-for-around-50/

Googled airspades and found these that might help.

Might be fun with mud and stones.

Everything Must be Somewhere

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6 years 8 months ago #535466 by Hawkspur
Replied by Hawkspur on topic Clearing culverts
Interesting.

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