Burying plastic culvert pipe

   / Burying plastic culvert pipe #1  

JimR

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How much cover (fill) do you need to put over a 24" diameter buried corrugated OD smooth bore plastic culvert pipe to sustain a 10 ton drive over load for instance? I'm going to install this in a roadside drainage ditch and need to bury it to make my new access road. TIA, Jim R.
 
   / Burying plastic culvert pipe #2  
How deep is the drainage ditch at the end of the new access road? Is the ground level or is it a hill? The reason I ask is if the drainage ditch isn't very deep to install the plastic culvert, you maybe able to did the drainage ditch a little deeper to make room under the access road to increase the amount of fill over the pipe. I'd think 18" or more would do the job without seeing the actual spot. If your going to be running heavy machinery through there often, I'd try to bury the culvert deeper if possible.

Howard
 
   / Burying plastic culvert pipe #3  
There should be tables of coverage required for the specs of the pipe you have. Also you must take into account the type of backfill and compaction capabilities you can acheive.

I know it does not answere you question but an incorrect answere means there may be a failure which I do not think you want.
 
   / Burying plastic culvert pipe
  • Thread Starter
#4  
MX5000 said:
How deep is the drainage ditch at the end of the new access road? Is the ground level or is it a hill? The reason I ask is if the drainage ditch isn't very deep to install the plastic culvert, you maybe able to did the drainage ditch a little deeper to make room under the access road to increase the amount of fill over the pipe. I'd think 18" or more would do the job without seeing the actual spot. If your going to be running heavy machinery through there often, I'd try to bury the culvert deeper if possible.

Howard


Iwill have to take accurate measurements of the slope. I think the high side is 5' and the low side is 2.5'. The low side is also about 4-5 feet from the top of the culvert pipe to the edge of the road. I'll try to measure this tomorrow and take a picture of it. The Higway Dept. chief told me to dig down 6" and drop the pipe into place and just fill it over. I want to pack this in as tight as possible to make the best carrying surface I can for it. I was thinking that small stone around the pipe with crushed gravel mixed in to make it really hard. I bought two sections of pipe from a guy that had no use for them. These 20' pipes cost $416.00 apiece with tax. I paid $300.00 for the pair of them. One is 20', the other is 16' long. I also plan on dropping the short piece into a stream (with proper approval beforehand) so that I can access another section of land we own. No digging will be required as I dug this out 30 years ago to a depth of 4'. The second pipe will be a simple drop it in and fill it over.
 
   / Burying plastic culvert pipe
  • Thread Starter
#5  
Egon said:
There should be tables of coverage required for the specs of the pipe you have. Also you must take into account the type of backfill and compaction capabilities you can acheive.

I know it does not answere you question but an incorrect answere means there may be a failure which I do not think you want.


I wish I had a sheet for these pipes. I'm trying to find one online.
 
   / Burying plastic culvert pipe #6  
Jim,

I did find a table online years ago. Basically it said to put 12 inches over the culvert. That was good for a semi trailer. I tried to get 12 inches of ABC over mine. I'm close but I doubt its that deep. The culvert held up just fine during the house construction. At least one logging truck, dozens and dozens of dump truck loads of ABC and 67 stone was brought in, 7 concrete trucks, as well as bulldozers, backhoes, and an execavator went over that culvert.

I back filled the culvert with ABC which is the name of the road base here in NC. This stuff packs down almost like concrete. That culvert has not moved. The culvert was not placed in a ditch, its in a low area that had to be crossed. So the ABC had to cover and hold in the sides of the culvert. From the road, the drive drops a bit, climbs the culvert, dips again and the climbs a hill. One day I'll have another 15 tons dropped on each side of the culvert to take out the dip.

Later,
Dan
 
   / Burying plastic culvert pipe #7  
Is the ditch county property ? Check with your county road dept. Here the county will install a concrete pipe for drive access free . They will install an additional 100' free if you buy the pipe
 
   / Burying plastic culvert pipe
  • Thread Starter
#8  
dmccarty said:
Jim,

I did find a table online years ago. Basically it said to put 12 inches over the culvert. That was good for a semi trailer. I tried to get 12 inches of ABC over mine. I'm close but I doubt its that deep. The culvert held up just fine during the house construction. At least one logging truck, dozens and dozens of dump truck loads of ABC and 67 stone was brought in, 7 concrete trucks, as well as bulldozers, backhoes, and an execavator went over that culvert.

I back filled the culvert with ABC which is the name of the road base here in NC. This stuff packs down almost like concrete. That culvert has not moved. The culvert was not placed in a ditch, its in a low area that had to be crossed. So the ABC had to cover and hold in the sides of the culvert. From the road, the drive drops a bit, climbs the culvert, dips again and the climbs a hill. One day I'll have another 15 tons dropped on each side of the culvert to take out the dip.

Later,
Dan


Hi Dan,

That is what I needed to know. I was hoping a foot of good fil would be enough. I think I will end up with about 16 inches over the pipe.

As for the county doing it, not in my town. The budget is too tight. I have to foot the bill for the pipe, installation and fill. I can do all the work myself. At least the ditch is already there. If I need to dig it out 6" that shouldn't be too hard to do. I do need to wait till next summers dry season to install the pipe to eliminate any soil runoff. It is actually the drainage ditch on the side of a road that I need to bridge. I had a railroad tie bridge over it for 20+ years. I removed it this spring as it was starting to rot away and had ants in the creosoted beams.

I did find a spec sheet on Advanced Drainage Systems website. It recommends 6-12" of initial backfill using class I, II, or III material and a foot of final backfill (no type mentioned) over the pipe.

I just found this on ADS's website

ADS N-12 pipes are designed to carry H-25 live loads (40,000 lbs. Axle – legal load) with 12 inches of
cover. This assumes a well compacted embedment and includes the subbase material for installations
under pavement. For 60" N-12 the minimum cover for H-25 loads is 2'-0".
 
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   / Burying plastic culvert pipe #9  
JimR said:
Hi Dan,

That is what I needed to know. I was hoping a foot of good fil would be enough. I think I will end up with about 16 inches over the pipe.

As for the county doing it, not in my town. The budget is too tight. I have to foot the bill for the pipe, installation and fill. I can do all the work myself. At least the ditch is already there. If I need to dig it out 6" that shouldn't be too hard to do. I do need to wait till next summers dry season to install the pipe to eliminate any soil runoff. It is actually the drainage ditch on the side of a road that I need to bridge. I had a railroad tie bridge over it for 20+ years. I removed it this spring as it was starting to rot away and had ants in the creosoted beams.

I did find a spec sheet on Advanced Drainage Systems website. It recommends 6-12" of initial backfill using class I, II, or III material and a foot of final backfill (no type mentioned) over the pipe.

I just found this on ADS's website

ADS N-12 pipes are designed to carry H-25 live loads (40,000 lbs. Axle – legal load) with 12 inches of
cover. This assumes a well compacted embedment and includes the subbase material for installations
under pavement. For 60" N-12 the minimum cover for H-25 loads is 2'-0".

Look at those ADS tables and in particular, the diagrams. The critical fill is about half way up the pipe. After that, the quality of the fill material becomes a little less important.
 
   / Burying plastic culvert pipe #10  
A two foot cover over the pipe would be assuming the angle of repose of the covering material is 45 degrees which should be pretty close. At that point the covering material bridges and the weight transfered to the pipe is transfered down at a angle of 45 degrees thus greatly reducing any force on the pipe.:)

Compaction from the base of the culvert to the top of the road will really help distribute the load and lock the pipe in place.:D

Is it possible to build up the road to give more coverage?

One site that may help. Be patient and keep reading. There will be a few pictures and some tables. Ignore the calculations unless you are conversant with them.

http://http://drainage.plasticpipe.org/pdfs/tr-38.pdf
 
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