Culvert Advice -- Plastic vs. Galvanized ?

[PineRidge]

Plastic, double walled, corrugated, smooth bore pipe was the first thing that we put down in the culvert after we acquired our property 7 years ago. There has been much traffic across it including all the heavy equipment that was brought in to build the pond. Excavators, dozer's, compactors, and an endless procession of trucks. I check the pipe on a yearly basis to be sure that it isn't filling with silt and it looks to be in the same shape as it was 7 years ago. Think I'm getting my moneys worth on that expense.

 

[CurlyDave]

Thanks for all the replies.

I was already leaning toward plastic based on corrosion, the mosquito abatement is another benefit.

Then I called the only two local suppliers & got the bad news.

One is out of stock on plastic culvert, and the other doesn't carry anything larger than 12", and is also out of stock on plastic. Of course no one will order this for me, since I only need one piece. Fortunately the one that does have 24" galvanized is also the lower priced one.

I will try calling the two suppliers in Medford (30 miles) and see what they have tomorrow. An extra hour of driving is worth it to get the better product.

If they don't have plastic, it looks like galvanized is going to be the only choice. Oh well, the country survived on galvanized culvert for a long time & if I get 30 years out of it, it will outlast me...

Another question;

How do I compact the dirt near the culvert? Do I need to rent a compactor (which is not a lot of fun to run) or can I just push down hard with the FEL after dumping each load? I have a Deere 110 TLB which weighs 8000 lb and can easily lift the front end with downpressure from the bucket.

I am thinking that if I get to this while the dirt is still wet from the winter rains, both digging and compacting will be easier.

I seriously doubt that I want to try driving on the dirt to compact it, the gully will be wet, soft and steeply sloped. Softer at the bottom too. Driving parallel to the partially backfilled culvert will be a great recipe for a lay-over. Not only would it be bad for me & the backhoe, but it would probably squash the culvert too.

 

[BB_TX]

Yes, you can do it with your tractor. Do it in stages. Add fill, pack it, add fill, pack it,........ Once you get it filled somewhat above the culvert, then you can run parallel to the culvert just at the edge of it and pack the fill down along the sides of the culvert. Then add more and pack by driving back and forth all over the crossing.
If the slope is steep, you may have to use some fill to build a temporary ramp to get up and down until you get it filled. Then take the ramp out.

 

[SWinTexas05]

If you are going to have 3-5 feet of fill over the pipe you are going to have a very narrow road on top of it, with that amout of fill I would go with at least 30 feet of pipe. I would go with a double walled plastic pipe.

 

[MarkV]

I was thinking the same thing as SWinTexas that 3 to 5’ of fill is going to narrow that road bed by the time it tapers in. Motor homes are kind of wide and if the approach requires a turn you could be too narrow.

MarkV

 

[BB_TX]

From your basic description, it appears you are going to need 30-40 yards or more of fill. Did you get anywhere near that much from your excavation?
And I would agree with the 30' pipe. I would rather have a nice gradual slope on each side rather than a steep one. On second thought, do it like txdon did. /forums/images/graemlins/grin.gif

 

[LBrown59]

Steel pipe would be like going back to Ma Bell and the crank operated wall telephone.

 

[EddieWalker]

Listen to the advice your've recieved and get the plastic culverts.

You need to find the right suppliers. Every area will have a somebody with plastic culverts. They are used too often not to have them. Lowes hase 15 inche ones here, but the plumbing supply house has 24 inch in stock and I can go to the feed store and get 48 inch. You need to check around more.

Five feet of fill above the pipe will give you a road ten feet wide with 12:12 slopes. That's too steep and it will erode on you, not to mention the road is too narrow.

You can get 24 foot long culverts, but it's still not enough.

So now you need to get two 20 foot culverts and join them together. There are sleeves that slide right over the plastic that are real easy to install. The metal ones are a real bear if you stick with the metal culvert.

If you have five feet of fill over a 24 inch culvert, the simple math says you have a 7 foot ravine. How much water does it handle in the worse case storms???

24 inches might not be enough. /forums/images/graemlins/confused.gif

As for getting the fill material compacted, you have several routes. The pros will do it in lifts with a hand operated thumper or the bucket of a backhoe or trackhoe. Most do it yourselfers will just dump the dirt, smooth it out and drive over it. In time this works pretty good, but I wouldn't try paving the road because it will settle a little over the years. Gravel will work after awhile, but I'd hold off on that for awhile too.

I like the ramp idea to get down there close enough to work, then build up the dirt in layers and driving all over it.

Eddie

 

[LarryRB]

smooth bore, double lined corrugated is the way to go... That is all we used on the highway dept... Properly laid down, and with rock headwalls on each end, they hold up tremendous amounts of weight without a thought about it.... If you cannot buy 18", ask your local highway dept. We use to get pipe all the time for the locals,, We would order and buy and the people would go to town hall and pay the invoice to the treasurer, It would then revert back to our highway budget. Not all dept's will do this, however, it is an option you can ask about

 

[Highbeam]

The most important place to compact the material is around the bottom and halfway up the sides. Some will call this the springline. By compacting the soil well halfway up, the rest of the pipe acts as an arch to support the weight. Plus gravity will help compact above the half way point. Set the culvert down on a firm base, dump 6" of fill around the sides and get in there with your feet and maybe a sledge hammer and tamp it down around the bottom of the pipe and upwards. Do this at least half way up but be careful not to push material under the pipe and squirt it up and out of your trench.

With that much cover you shouldn't experience pipe collapse due to weight but you will experience settling if you don't compact the fill around the pipe. Plus if you don't seal the culvert well enough you may get water flowing around the culvert and washing away your backfill.

In the picture I posted the ravine is at least 7' deep. To get a decently wide roadbed you can actually drive down into the ravine meaning the road has a dip. This is beneficial in a few ways. One, you provide an overflow within the same ravine should the culverts plug. Yes it will ruin your road but the water is still in the channel. Two, the roadbed can be wider. And three, you won't have to haul in 40 yards of fill.