Advice wanted on installing pipe culverts in woods roads

[pharmvet]

About 3 years ago I hired a gentleman with a mulching machine to cut a 15 ft "firebreak" around the perimeter of my property. I have since conducted 3 prescribed burns for wildlife habitat improvement. The perimeter road is crossed by several little draws or creeks. Several cannot be crossed with a tractor and 3 pt shredder and therefore I cannot keep them maintained. I want to use pipe like is pictured below for culverts. Any and all advice welcomed.

Cover with rock, dirt, both? If both, which first?

 

[whistlepig]

Rock is better than earth. Earth is better than sand.

 

[boggen]

you will more likely need to dig some dirt out. what ever dirt you dig out, do NOT re-use. it will most likely be to wet and take a long time to dry out.
you will most likely want a base layer of rock down before the pipe goes in. and then a little more rock if you have it around pipe, then a little dirt, and then a couple inches or more of rock going across the pipe.

errr take last comment back. diameter of pipe divided by 2 i want to say is min height of dirt you want above the culvert pipe? it has been awhile. i don't remember specifics. other words you may end up having to build a small "ramp" going over the culvert pipe. the ramp helps to make sure the water goes into the culvert pipe, but also making sure you have enough compacted dirt above the pipe, so weight of tractor will not cut through the dirt and smash the culvert pipe. other words the more dirt you have over the culvert, the more the dirt will spread the weight out of the tractor as you drive over the culvert.

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from pictures it looks like that piping is for "air ducts" in some building. *shakes head no* that stuff going to rust out quickly!!!

you can goto menards, lowes, home depot. and pick up some single or more likely prefered double wall culvert pipe, 20 foot lengths fairly cheaply. and would most likely be plastic, and last a long time!!! cost of rock i would imagine going to eat up some cash, and having to redo it in a few years due to pipe rusted out...

 

[EddieWalker]

What type of pipes are those?

Keep it simple. Do not dig any deeper then the existing bottom of the ditch except where you have to in order to get it flat. The secret to a pipes strength to support a load is having the dirt compact all the way around the pipe so the weight of what is on top of it is carried around it. I wouldn't use any rock and I would make sure there wasn't any rock in my fill material. Clean dirt is always going to compact the best. When I worked in California installing different types of pipes in the ground, we would fill with clean sand and jet the sand with water to get it to settle. Sand forms a very tight seal around a pipe when a lot of water is added to it!! Then cover with clean dirt and compact the dirt up to the level where the pavement would start.

For you, clean fill is all you need. Soak it with water if you can to get it into the sides and bottoms and build it up so there is at least half as much dirt on it as the diameter of the pipe. More is better.

What you really need to make sure to do is either add a lot of rock or concrete at the inlet and exit of the pipes to stop the water from eroding them. I like to use 40 pound sacks of concrete. I stack them on top of each other and drive lengths of rebar through all of the sacks. Dump some water of all of it and in time it will harden nicely. If I can't find 40 pound sacks, then I'll get the smallest ones I can find.

Eddie

 

[pharmvet]

Thanks guys. This pipe was advertised locally. I'm going to look at it today or tomorrow. It is supposed to be 12" diameter 1/4" wall thickness natural gas pipe.

 

[DHD]

Here is some info on Forest Road Construction that may help.

http://www.nrs.fs.fed.us/fmg/nfmg/docs/mn/roads.pdf

A Landowner's Guide to Building Forest Access Roads - Introduction

 

[jejeosborne]

I had a plastic culvert fail this spring due to over burden being too heavy. It was 9 feet underground. It is important to backfill with gravel and make sure the base under it is stable. If allowed to bend, it will form a weak spot that will allow for a collapse. I will never use plastic again because of the special requirements it has for back filling. Concrete is the way to go and doesn't require such perfect backfill techniques. The plastic would have been fine if the soil were stable and all techniques were followed exactly right.

 

[EddieWalker]

How did it fail?

Eddie

 

[jejeosborne]

How did it fail?

Eddie

I was where my driveway crosses a very deep Creek and installed 7 years ago. It was installed on some areas that were fill dirt which should have been compacted stone, which allowed some settling at a portion of the pipe. Even a slightest amount of settling on plastic is bad because plastic will form a kink which then becomes a weak point. It then collapsed. Plastic must also be supported by its backfill to gain strength. Now that this has happened, I have become educated on the disadvantages of plastic. I would still use it for trails and areas not needing a lot of support but concrete cost the same per foot so why use it at all? Only reason not to use concrete is that it takes heavy equipment or skill to joint up the bell ends.

 

[s219]

Metal or plastic pipes will fail if the culvert cover is not done right. If it is done right, plastic will greatly outlast steel. So it has become the material of choice nowadays.

Concrete is a different ball game, as you need larger equipment to handle and position it compared to steel or plastic. It does have its own structural strength, so it's less vulnerable to poor fill. However, it will fail too under insufficient cover. When houses are built around here, the site crew normally drops a concrete pipe in the ditch and back fills with just enough stone to reach the top of the pipe. Then all the construction traffic pounds on that pipe. After a few months, they all develop cracks or have chunks missing. Even seen a cement truck get stuck when a concrete pipe gave way.

So whatever you use, be sure it's bedded and back filled properly, with the correct amount of cover.

I put my culvert in about three years ago, using plastic pipe with proper prep, backfill, and cover. Basically, did it as a permanent job from day one. It handled all our construction traffic with no issues, and has outlived all the other half-a$& concrete culvert installs on the street. I would not hesitate to use plastic again.