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Small Cabin Forum / General Forum / Putting in a culvert
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jrbarnard
Member
# Posted: 11 Jun 2013 06:33
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So.. the road to my place has a wash-out. Here's what I was thinking of doing:

The people that 'maintain' the road have done a horrible job. They added a lot of road base that easily gets washed out and it did, a week after they paid to have it repaired.

So.. I they are buying like an 8-ft piece of 30" culvert and I am bringing the tractor down to dig out the area that has a huge rut through it. Then I am going to bring a dozen bags of quickrete along with me and lay it along and around the 'entrance' to the wash out.


Then I will take a lot of smaller rocks etc and lay that along the length of the culvert and then fill the rest in with roadbase.

Does that sound about right?

It may not hold much better, but when it washes out, it should not leave a 1-ft plus trench...which is what I had to drive over while hauling a polaris crew....not fun.. heh

Russ

creeky
Member
# Posted: 11 Jun 2013 15:27
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8 feet is pretty short for a road culvert? not 12 or 17 or?
and I'd skip the concrete. but someone will have more road building experience than me.

jrbarnard
Member
# Posted: 11 Jun 2013 15:31
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Not sure how long the culvert will be, I am not the one picking that up. I suspect, actually, it would be at least 10 ft long.

I just am not sure how much or whether to add concrete to reinforce the sides.

Russ

VTweekender
Member
# Posted: 11 Jun 2013 15:48
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Concrete used in the manner you describe would be a waste of time and money as it will just crack and crumble, just use rocks.

jrbarnard
Member
# Posted: 11 Jun 2013 15:50
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cool.. will do.

thanks

toyota_mdt_tech
Member
# Posted: 11 Jun 2013 21:07
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Use rocks to protect the ends of the culvert cover. Large rocks and also build breaks in the ditch with large rocks prior to the culvert. This will slow down the water and stop the erosion.

Oilerfan
Member
# Posted: 11 Jun 2013 22:48
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I am a civil engineer and have installed hundreds of culverts...the concrete isn't required. This would only be installed as bedding for structural reasons (large trucks, etc). As others have said all you need to do is protect the ends from erosion with large rocks (rip rap). You should try to make sure the top of rocks are roughly even with the bottom of the culvert if possible.

Did the road previously have a culvert?

Oilerfan
Member
# Posted: 11 Jun 2013 22:50
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Interestingly enough I was onsite today for one of my projects that is experiencing some flooding. The rip rap is doing its job!!!
Access_Rd_Storm_2.jp.jpg
Access_Rd_Storm_2.jp.jpg


jrbarnard
Member
# Posted: 12 Jun 2013 08:49
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Cool beans, thanks for the help.

The info on the culvert we are getting is 30" diameter and 20 feet long, construction grade.

Will take pics of it when we install it.. heh

Russ

creeky
Member
# Posted: 12 Jun 2013 09:33
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oilerfan thx for the pic. my buddy has a culvert that keeps "humping" up. i don't think the culvert is rising up? but it potholes in the road before his culvert, then humps, then potholes... any suggestions for him? is there a minimum depth of gravel to go overtop?

Oilerfan
Member
# Posted: 12 Jun 2013 10:58
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The minimum depth of cover is typically specificied by the local authority. Up in Canada where it is freezing 8 months of the year, normally the culvert needs 1m (3.3ft) of cover over the top of the pipe to avoid frost heaving. In areas where frost isn't an issue structural loading would govern the required depth. If it is light traffic, you likely wouldn't need more than a couple of feet depending on the material backfilled around the pipe. Gravel would be the best. However all this said, the culvert under roadway is likely about 2ft down, backfilled with clay, and topped with 1ft of gravel. It is settling already but i will likely just add some gravel next spring once it is done.

If your buddy's culvert is potholing it might be due to inproper compaction of the material on the sides of the pipe or the bottom of trench or frost heaving.

In a perfect world this is the typical detail for a culvert install...
- excavate to 1ft below culvert including say 1ft on either side of the pipe.
- ensure bottom of trench is compacted. If soft, you can use a geotextile to help strengthen and bridge the softer material.
- at a min install a granular material (gravel,sand,etc) in the trench to the pipe springline (middle of pipe) for a good bedding. It is preferrable to use granular material to 1ft above pipe if possible. Compact material (plate tamper, etc) every half foot to avoid future settlement.
- Once you get pipe bedding and surround done then backfill to the top of the grade with a good backfill material, again a granular material is always best.
- I like to use 1:1 side slopes in the trench excavation to avoid a vertical cut. The 1:1 side slopes helps avoid differential settlement between the excavation and the existing ground.

Hope this helps and isn't too technical.

jrbarnard
Member
# Posted: 12 Jun 2013 11:10
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We have nothing but rock.. lol.. should be plenty good support ;)

R

241comp
Member
# Posted: 12 Jun 2013 14:27
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If you haven't picked it up yet, I would recommend getting the double-walled culvert which will be smooth on the inside and ribbed on the outside. The smooth interior will flow better and will not collect water in the ribs during dry times (which can be a breeding ground for mosquitos). If you are getting single-wall, be sure the ribs are perforated to allow trapped water to drain out.

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