how to fill in a mile long trench

I'm putting a water project in on the farm. It's got to be buried 2 ft deep. I'm going to rent a ditcher. One of my rental ditcher options will make the trench four and a half to five inches wid,e the other is six inches wide. How do I fill in the ditch after I've laid the pipe? With a shovel, or a hoe? So I just have to walk the whole mile and then step on top of it after I filled it? The ditch is through tall native grasses like little blue stem. Is this going to be a problem either for the ditcher or for refilling? I'm going to rent a ride on ditcher. Obviously I have no idea what I'm doing so any practical advice is welcome.

The ditcher should have a little blade on the front for pushing the dirt in the ditch for a project that size. Word to the wise: if you are unfamiliar with trenching it is generally a good idea to go the direction where the soil is placed on the uphill side of a slope for easy filling.

Hi Denise;
Most ditching machines have a small blade on them to push in the dirt when your done.
After that then... yup walk along with a square blade shovel and scrape the dirt into a mound and walk on it.
It will still slump in over next winter.

Denise,

Just a thought, maybe mow the path first so the grass doesn’t hang up the refill operation.

With a mile of trench to fill back in, personally might be tempted to beg, buy, borrow or steal a tractor with an angled blade so you can travel along that long mound and scrape it back into the trench.  After it gets scraped back on the trench, maybe run over the pile in the trench to pack it back down—initially it will likely be mounded above the surface of the trench.

Interesting project!

Eric

Be aware narrow trenches are harder to get filled as the dirt tends to bridge.  And they will settle longer.  This is especially true in deeper trenches.  Plan on refilling the trench probably twice in the next decade as it settles.  If you want to avoid that then you need to fill in fairly short lifts and use some sort of compactor to settle the dirt.

Now I will ask are you sure your trench is deep enough  While I am farther north being northern WY my bury depth is a minimum of 4 1/2 feet here with at least 6 under roads and places driven over regularly in winter.  Also places that have open dirt in winter like corrals are another danger zone needing more depth.  Ideally you want your average frost depth plus at least a foot.  Personally here the ideal depth is 6 feet at least under normal and 8 feet crossing roads and bare dirt areas.

Now such a shallow depth is of concern other ways too.  That is about the depth the phone line was plowed in here and someone crossing that long closed trench in muddy weather a decade later somehow got stuck there and spun the tires digging down trying to get out and cut the phone line with a spinning tire.

It is also of concern because any driving across the line causes uneven crushing forces that tend to crack lines longitudinally.  Also shallow means faster acting freeze thaw causing the same thing.

Also if it is the lightest weight water line(100 psi??0 it will tend to develop a cracking problem even buried deep after a decade or 2.  Suggest going to the 2nd or 3rd step up in pressure rate even if you don't need it because of this.

Finally if you are crossing roads suggest burying that part of the line in a heavy wall pipe extending 10 or 15 feet  on either side of the road to act as a conduit.  Also if the pipe breaks there for some reason it doesn't come up under the road.  Trust me a man made spring in the middle of the road never happens at a good time.

C. Letellier, please define narrow. Yes, I'm sure 24-in. is deep enough. The locals only bury 18". I will be using a schedule 40 PVC or PE pipe. The roads I have to cross are 10 ft wide gravel roads, do I really need to go 10 ft out on either side with a casing pipe?

Hi Denise;
It really is a good idea to use a hard pipe under a road.
As was mentioned the compaction over time and the possibility of a freeze being pushed that deep are true.
The reason I think its a good idea is for when you have problems later.  
Being able to replace a line under the road without having to dig it up is a great benefit.
Even if it is your road on private property it is still a hassle and creates a new  pothole to drive over.

I have lines run under a county road. They are all hard pipe covered  to ease changing. They were that way when I bought the place...
And I did need to change a water pipe out in the 40 years I have been here.
Being able to just slide the new pipe in was SO NICE!   Not needing to dig up a county gravel road was even nicer!

Do you need to go 10' out?     I don't think so.  
A few feet past the toe of fill on either side would be how I would do it.

I plan to use pipes if I go under the gravel roads. I'm only using one and a quarter or one and a half inch water pipe, will if 3-in container pipe be good enough? The other people I've asked have suggested using PVC for the container pipe.

I think the 3" will work fine but 4" would be better.
1.5" poly (black) pipe is at least 2"  outside diameter.  After you backfill, over time your hard pipe will slowly get a dirt/mud layer that fills in on the bottom.  
If you have to push/pull  a coupler with hose clamps on then 3" suddenly isn't so large.

Denise, looking at the distance and the pipe size, I assume you will be running a high pressure line.
Is that correct?
If you are going up and down hills you will need to fit in air valves to allow air bubbles to leave the pipe, otherwise they create a restriction.

This is a project that the NRCS is involved in and so they're keeping me out of trouble in terms of knowing whether I need air release valves, drains, and the sizing of the pipe. What I still haven't decided is whether to use polyethylene or PVC. Before the price of PVC went up this week because of the ice disaster in Texas I was planning on using PVC. Now I'm not so sure. I have gophers so I'm pretty sure PVC is the better idea.

thomas rubino wrote:I think the 3" will work fine but 4" would be better.
1.5" poly (black) pipe is at least 2"  outside diameter.  After you backfill, over time your hard pipe will slowly get a dirt/mud layer that fills in on the bottom.  
If you have to push/pull  a coupler with hose clamps on then 3" suddenly isn't so large.

If it is a larger conduit, you maybe have an easier time running something else in there as well, such as a second pipe from a separate source (potable/non-potable), or to a different destination (barn/field irrigation), so that you aren't without water everywhere due to one leak/repair, or you could shut-down one "zone" seasonally.
Other things you might run (not sure if allowed by code in same conduit?) electric, data/phone, electric fence wire?... If you think *maybe* you might do any of these in the future, another option is running a second conduit alongside in the trench at the same time...(taped shut/capped off) it's relatively inexpensive, and that way you only dig across the road once.

the trencher that I want to rent says it will trench four and a half to five inches wide. It is the less expensive trencher to rent for sure. Will I be able to put a 4-in pipe in that trench?

Well , Poly pipe easily.    Hard schedule 40 pvc?  Not so easy.
Let me ask a question.  I think you said you wanted to use pvc?
If that is so then you must plan on bedding that pipe,  preferably in sand.   Backfilling hard pipe is also partially done with sand.
Black Poly pipe is much more forgiving about being pushed into a hole and  backfilled with what you have.

the NRCS is involved

what does this mean please?
When you speak of PVC pipe, are you talking about the sort of harder plastic used in downpipes etc?
Or pressure water pipe used inside walls?

NRCS is natural resource conservation service, that is the government. I will be using pipe that can be pressurized and pressure fittings.

There is not a perfect magic number for the width the casing pipe needs to extend beyond a road.  I just use 10 feet as the rough number  But remember roads tend to get wider over time.  Also remember the sheer/compaction zone is wider than the road and you want the pipe to pipe interface beyond that because it creates a hard crush/sheer zone you want to protect from.  Personally I look for surface features that are likely to remain in roughly the same place to use as references for finding the pipe later and to minimize future damage.  So say I have a road and then 4 feet to a property line fence.  My casing pipe should go under the road and just under the fence far enough that I don't have to take the fence out to affect a repair there.  That way I can use the fence as my marker for where the end of my casing pipe is buried.  I would still try to bury something nearly vertical that I can trace down to the mouth of my casing pipe.  It can then tuck into the fence.  usually I am looking at  say 6 to 8 feet from the road edge and another 2 feet to get far enough past the fence that I could dig down without wrecking the fence in the future so that is my 10 feet.  if the compaction zone  goes down at a 45 degree angle and and I am 6 to 8 feet down for freeze prevention there again that puts my pipe to pipe interface beyond which is also just under the 10 feet.  So that is the reason for 10 feet.  Crossing a country road there they have a 60 foot right of way would be my other possible criteria.(30 feet out each way from the center line of the current road is the rule here.  And I would try and get my casing pipe beyond that.  Do what looks like will make things the easiest into the future remembering potential change into the future.(like roads getting wider)  That fence is also a nice place to bring your line locate wires up on at least one side of the road.  PS for future reference suggest videoing everything but at least places like road crossings and major bends in the pipe path.

Now someone mentions the casing pipe filling with mud over time.  Very true.  On my to try list is spray foaming between the 2 pipes in say 3 inches with a big blob of it outside the pipe at that location.  Triple goal.  1. keep more of the mud out of the casing pipe hopefully, 2. make finding the end while digging safer and easier as you should hit the foam first with the shovel.  3.  create a cushion to hopefully reduce setting dirt crush problems.  As for size I am going to say the ID of casing pipe should be roughly 25% larger than the OD of the pressure pipe as the minimum.   That much is simply to make pulling the pipe thru the pipe easier.   Within reason bigger is better simply because it leaves more options into the future.  And high schedule PVC is perfectly good enough.  Suggest mimimum of 40 with probably schedule 80 being a better choice.

Also if there is any chance you may want to run a wire of any kind in that right of way the mentioned idea of a capped conduit run in the same trench is a good idea.(likely won't work if you are boring the road instead)

Personally I would go with poly pipe as I have had fewer problems with it thru the years unless there is a major price difference.  Be sure you get the proper stuff to do butt socket fusion so you minimize the number of clamped mechanical joints in the pipe. If you must do clamped mechanical joints in poly be sure you use all stainless or 100% stainless hose clamps for it.  I have replaced a number of buried joints that the clamp simply said stainless.  The problem is the band and the clamp shell are stainless but the worm gear isn't  It eventually rusts away and the clamp/pipe goes to leaking.  So be sure it says all stainless or 100% stainless.

I am using PVC because I have a lot of gophers and I'm hoping that will be more resistant to them than the poly pipe. I bought one in PVC. I bought a 4-in PVC foam-filled pipe for under the roads. I don't know what they use it for or what it looks like but the salesman said it would work for the 1-in poly. The roads have been the same with for 10 years and they're on the property so I bought a 20-ft pipe. The roads are 10 ft wide and they lead to the gas well pads. They get pickup trucks everyday and tankers not too often.  I'm going to run my pipeline parallel to these roads part of the way and I have to decide how far from the road I'm going to put them. It's a 10-ft road and they have a 20-ft right of way so once or twice a year they mow 5 ft off both sides of the road. I was thinking another 5 ft from their edge, so 15 ft from the center line of the road. I'm not going to have permanent fence anytime soon, I'll be using temporary electric fence with step in posts for the livestock and 50 or 100 gallon tanks for the water.