Question on back hoe speed

[mx125]

I have a 2320 and have some trench jobs ahead. I may just rent a trencher or hire out the service from a pro . . but wondered if anyone could give me an idea of time etc. if i had my own BH.

I need to dig a trench 12" wide x 3 feet deep . . for over 2200'. I also need to dig out a 30x50 frostwall foundation for a garage. Soft soil. Is currently in crop.

How fast do you think I could dig that trench? Having not used one . . would I scrape/dig and just keep the tractor walking forward?

I'm sure a trencher is faster . . but just wonder.

The other job is a trench for a geothermal heat pump. I've settled on having the pros do that as it's probably 3000' of trench and 6 feet deep . . .but maybe someone will tell me it's not that bad??

 

[sixdogs]

I would hire the job out to somone that does this for a living.
There are several learning curves to using a backhoe that would likely take longer that the job itself and give poor results that could affect the quality of the whole job.
I've been with a backhoe for 15 years--off and on--and I hired out a 1250 ft trench to a guy with a laser-levelled backhoe.
On the time aspectof 3000 ft, it's hard to gauge the enormity of it but I would say a number--3-4-5? of frustrating days.
I'll also add teh odds of getting the foundation depth correct and level are virtually nil which would mean the odds for increased settling would likely be great. You know, cracked walls and such.
Sorry to be such a pessismist but a level trench or foundation is an art form.

 

[mx125]

I see what you mean. I was almost 100% sure I would NOT attempt the 3000ft trench . . . 40% in favour of trying the foundation trench . . . and 60% in favour of the 2200 ft. shallow hydro trench.

It sounds like the foundation trench is probably more sensitive than I thought . . and the hydro prob doesn't justify it.

Out of interest . . .can the machine "walk" while digging behind or are stabilizers a requirement? And how long should I budget in time for a pro to dig my 2200' x 3' trench?

 

[Jimbrown]

Well my thoughts are that back hoes are such handy things to have I would seriously consider trying it my self. It will take longer so it kinda depends on how much time you have. I don't think you understand how to back hoe. You but down the stabilizers bucket and dig for the length of the boom and then pick up the stabilizers and bucket move forward 6 or so feet and repeat. You can push the tractor forward with the hoe each time. As for trenching I rented a nice riding ditch witch and dug a 3ft deep 1400 ft trench in about 5 hours.

 

[mx125]

Well my thoughts are that back hoes are such handy things to have I would seriously consider trying it my self. It will take longer so it kinda depends on how much time you have. I don't think you understand how to back hoe. You but down the stabilizers bucket and dig for the length of the boom and then pick up the stabilizers and bucket move forward 6 or so feet and repeat. You can push the tractor forward with the hoe each time. As for trenching I rented a nice riding ditch witch and dug a 3ft deep 1400 ft trench in about 5 hours.

I've never used a hoe . . so would be starting from scratch. I see . . so there would be a minute of so between each dig. I suppose I didn't understand that the hoe can pull an even depth 6 foot swath . . .so can picture it better. If it takes me 5 mins (??) for each swath . . .and a minute to move the tractor and reset . . it could be 36 hours of work for 2200'. If it's twice that it's almost two weeks work. Maybe it actually goes quicker . . .but it sounds like a trencher . .or a pro in a big hoe makes sense.

 

[kennyd]

What are you you putting in the trench?

If it's water or EL lines then a trencher is the way to go for sure. Not only is it a whole lot faster, there is less damage to the surrounding area.

 

[mx125]

What are you you putting in the trench?

If it's water or EL lines then a trencher is the way to go for sure. Not only is it a whole lot faster, there is less damage to the surrounding area.

Yes . .it is electrical (Hydo hook up) from the road. I'll look into renting or hiring a trencher. i could see it being a LOT cleaner. I saw pics from the Geothermal thread. That was some major disruption!

 

[RobS]

That's one LONG, WIDE trench. Why so wide? If it were narrower, I'd rent a trencher for sure. MUCH faster than a BH. If you really need it that wide, well I just don't know. It would be great practice for your hoe if you have the time...

 

[dirtworksequip]

mx125,it will almost always be faster to use a trencher to do utility runs, IF the soil conditions allow for a trencher to be used. If you encounter rock the trencher isn't going to cut it and you will need a hoe. I would say your lack of experience you could probably do the trenching, but forget about it with a hoe unless you have lots of time. 3000 feet of geothermal runs is WAY more digging than I would want to do with a CUT hoe attachment. Your soil conditions are going to dictate whether a trencher will be able to be used or not.

3000 feet of trench seems like a lot of trench for a geothermal field. I just did one for a new home and we did 6 feet deep 3 feet wide and 4 runs of 125 feet long. They layed the pipe in the slinky configuration and put the mainfold inside the basement wall.(keep that in mind. it allows you to isolate a run if you would ever have a leak.) So, we only had a total of a little over 500 feet of ditch. Thats why I am wondering why the 3000 feet?

Sincerely, Dirt

 

[mx125]

The utility trench, according to the electrical contact giving my quote was for 3 feet deep by about 12 inches wide (over the 2200 foot run).

I know the geothemal trench is really off limits to me . . but the quote seemed to refence about $6K to dig the trench and somehow i remember hearing 500 feet per ton unit (and he spec'd a 6 ton unit). I could be way off in the total trench length. I just thought I'd ask.

In both cases, though . . .I really have no idea what fair quotes would be.

Thanks for the info.

 

[dirtworksequip]

mx125, if your soil conditions will allow you to use a trencher you could probably do the 2200 feet of electric service trench on a weekend. IF THE SOIL CONDITIONS ALLOW. Are you gluing up the conduit and backfilling the trench. If you are you will need some help. The way I would do it with help is glue up the conduit first. You could actually glue it all up if the terrain permits. Lay the conduit off to one side of where you are going to trench. Out of the way of the trencher. Now start trenching. When you have about 100 feet of trench done have a helper start putting the conduit in the trench working towards the trencher. Once that 100 feet of conduit is in the trench you can start backfilling the trench with your tractor. Provided you have either a loader,rear blade or front blade. Keep trenching ,laying conduit and backfilling. With two other friends things should go pretty smoothly.
Let us know how you make out.

As far as the geothermal of "500 feet per ton" that may be 500 feet of pipe per ton and if they slinky the pipe it doesn't take 500 feet of ditch. $6,000 seems high, but I don't know what the rates are for your area.

Sincerely,Dirt

 

[CurlyDave]

I'll also add teh odds of getting the foundation depth correct and level are virtually nil which would mean the odds for increased settling would likely be great. You know, cracked walls and such.

sixdogs:

Why would this be the case?

I have always thought that if the foundation were deep enough (far enough below the frost line), there would be no such thing as too deep, and unless there was a consistent slope in the foundation trench bottom in the same direction on all four sides, and maybe not even then, a minor slope on the bottom would not cause a problem.

Oh, it might require some more concrete, but there is not going to be excess settling if the foundation trench is clean form debris and loose earth.

I usually use a coefficient of friction of 0.4 for the earth-concrete interface, which is conservative. If we ignore any resistance to concrete motion from material on the sides of the trench, there would have to be a consistent slope of 23.6 degrees on the bottom of the trench for the foundation to move. In the actual situation, material on the sides of the foundation will provide even greater resistance to movement.

Essentially, I don't think it is possible for even a blind man to dig a foundation trench which would cause settling or wall cracking. OTOH, a foundation which is under-designed, with either not enough soil bearing area, or not enough depth, will cause cracking & settling.

 

[mx125]

mx125, if your soil conditions will allow you to use a trencher you could probably do the 2200 feet of electric service trench on a weekend. IF THE SOIL CONDITIONS ALLOW. Are you gluing up the conduit and backfilling the trench. If you are you will need some help. The way I would do it with help is glue up the conduit first. You could actually glue it all up if the terrain permits. Lay the conduit off to one side of where you are going to trench. Out of the way of the trencher. Now start trenching. When you have about 100 feet of trench done have a helper start putting the conduit in the trench working towards the trencher. Once that 100 feet of conduit is in the trench you can start backfilling the trench with your tractor. Provided you have either a loader,rear blade or front blade. Keep trenching ,laying conduit and backfilling. With two other friends things should go pretty smoothly.
Let us know how you make out.

As far as the geothermal of "500 feet per ton" that may be 500 feet of pipe per ton and if they slinky the pipe it doesn't take 500 feet of ditch. $6,000 seems high, but I don't know what the rates are for your area.

Sincerely,Dirt

Thanks Dirt. That gives me some great info. I'll take that back to my builder friends and will be better armedin the dicussions.

And Curlydave . . that also gives me a little more confidence. I'll get a price from my foundation excavator . . if it's a meaningful chunk, maybe I'll go it alone on that garage.

Thanks everyone!

 

[dirtworksequip]

mx125, I checked with the owner of the geothermal sytem about the runs I dug. They were 5 feet deep,3 feet wide and 150 feet long. The pipe he used was in 600 foot coils. He used 600 feet per 150 foot of ditch using the slinky method. Also had 4 runs for the 4 ton unit.

Hope that helps.

Sincerely, Dirt

 

[mx125]

mx125, I checked with the owner of the geothermal sytem about the runs I dug. They were 5 feet deep,3 feet wide and 150 feet long. The pipe he used was in 600 foot coils. He used 600 feet per 150 foot of ditch using the slinky method. Also had 4 runs for the 4 ton unit.

Hope that helps.

Sincerely, Dirt

Thanks. That makes more sense. I spoke to a pro excavator today. He said that although he hasn't done any geothermal work, he "assumed" he could excavate a very large rectangle 6 feet deep . . allowing them to run all the piping they'd need . . .and that he could easily dig for $1500. Back fill would be less . . . so unless "trenching" was required he'd see $2500 as a more realistic quote (vs $6-7K quoted by the geothermal installer).

Perhaps the geothermal thermal process requires a more undisturbed soil .. but I'll ask the geo guys.

 

[CurlyDave]

he "assumed" he could excavate a very large rectangle 6 feet deep . . allowing them to run all the piping they'd need

You need to be a little careful here. The idea is to exchange heat with the earth. You would need a rectangle larger than the area of the trenches combined, because there are "edge effects" with the trenches which you would lose with one big rectangle of the same area as the total of the trenches.

While I might be able to muster up enough math to do this calculation, it is not for the faint-hearted.

I would want the hydrothermal factory engineers to make this calculation, not just a local installer.

 

[sixdogs]

My comments regarding getting the foundation hole straight and level means that is is difficult to get the dig even all over the length of run and that some "filling" may be necessary to correct too deep of a dig in one area. If that happens the soil will settle later and odds of a foundation shift are more likely.
I don't dig foundations but have seen a lot dug buy pros who seem to take a lot of care to get it exact and right the first time to avoid the settling.

 

[CurlyDave]

some "filling" may be necessary to correct too deep of a dig in one area.

Unless the slope is way, way off over a substantial run, don't fill with dirt, just use extra concrete.

If I am doing it myself, I also use extra steel. The money I save on the excavation more than pays for a little extra concrete and steel, and I get a stronger, better foundation for less money.

 

[dirtworksequip]

mx125, you need trenched runs and not one huge excavated rectangle. The runs I did were 15 feet between the runs. In other words it was layed out
3 foot trench then 15 feet undisturbed soil between the runs.Then another 3 foot wide trench followed by 15 feet of undisturbed soil. Each 3 foot trench had 15 feet of undisturbed soil between them. The idea of the geothermal system is to affect as much ground area as you can. Hope that helps you see the picture. If you put the piping in one big retangular hole you will be excavating out a lot of extra dirt and not affecting as big of an area.
Wish I had some pics of the system I did and you would get the idea. The $1,500 would be inline with what I did. If I remember right I think the total was $1,750 and that included the time for a machine to backfill. One word of caution is you need rock free dirt to bed the geo pipe in the trenches. We had an over abundance of topsoil, so I roto tilled the topsoil to a powder with my JD 3520 equiped with a JD 660 tiller. Then we used a Cat Track Skidsteer to slowly backfill with the powdered topsoil. Had 3 guys in the trench with shovels backfilling the first couple of inches to make sure no rocks were against the pipe. Once we had a couple of inches over the pipe we backfilled the rest of the trench with the Skidsteer. Its critical to make sure there are NO rocks in contact with the pipe.

Sincerely, Dirt

 

[mx125]

mx125, you need trenched runs and not one huge excavated rectangle. The runs I did were 15 feet between the runs. In other words it was layed out
3 foot trench then 15 feet undisturbed soil between the runs.Then another 3 foot wide trench followed by 15 feet of undisturbed soil. Each 3 foot trench had 15 feet of undisturbed soil between them. The idea of the geothermal system is to affect as much ground area as you can. Hope that helps you see the picture. If you put the piping in one big retangular hole you will be excavating out a lot of extra dirt and not affecting as big of an area.
Wish I had some pics of the system I did and you would get the idea. The $1,500 would be inline with what I did. If I remember right I think the total was $1,750 and that included the time for a machine to backfill. One word of caution is you need rock free dirt to bed the geo pipe in the trenches. We had an over abundance of topsoil, so I roto tilled the topsoil to a powder with my JD 3520 equiped with a JD 660 tiller. Then we used a Cat Track Skidsteer to slowly backfill with the powdered topsoil. Had 3 guys in the trench with shovels backfilling the first couple of inches to make sure no rocks were against the pipe. Once we had a couple of inches over the pipe we backfilled the rest of the trench with the Skidsteer. Its critical to make sure there are NO rocks in contact with the pipe.

Sincerely, Dirt

Thanks Curly and dirtworks. I definitely understand what you mean. And I don't wat to spend $35+K on a system that doesn't work well dur to improper trenching. I'll talk to the geo team. If he has complete specs for the trenching I'll talk to my pro about cost on his end. Thanks again for all the insight.