Electrical Trenching

[tractchores]

Electrical Trenching in Rocky soil - 265 feet

I've been working on trenching 265' for an electrical service run to be used for a gate and lights. I thought I'd post some pictures. This is a very time consuming job due to my soil - glacial till. It's heavy clay filled with boulders everywhere, which range in size from basketball size up to as big as a car. The trench has to be at least 30" deep to allow for bedding the service per code. I'm trenching with my B2920 and BH65 with a 16" bucket. The conditions make using a typical trencher impossible due to the large rocks. Quotes for excavation ranged from a few thousand all the way up to $12,500!!!!!

The project is taking a long time, but I am probably done with close to 200 feet now, though it took 7.5 hours of work today to go ~150' due to several large boulders that had to be dealt with.


The trench line, it's going in between a bunch of trees and some surface boulders have to be moved just to start work. Length will be over 265' when done. I used a string and utility flags to mark the path to attempt to keep it as straight as possible.


Partially done section. Soil and small rocks are on the right for easy backfill, larger rocks and boulders are on the left for use later in other projects.


The trench had to be routed around a big rock that was probably too large to move. The width is sufficient to get what I need under the edge of the rock and access is hard at this point so I left it VS trying to excavate it. It is at least 3' x 4 x 4, possibly much larger.


Tractor in one of the easy access sections.


A Problem. A rock that is directly across the trench and is close to 30" deep, 6' long and 30+" wide. The trench is right at it's center and initially it didn't move at all when pulled. Feather and wedges failed on this rock, partially due to it's thickness, but also due to the top breaking off and ruining the drill holes before splitting. Drilling was taking far to long (granite), so I decided to try to move it out of the way into a hole I dug next to it.


I was able to get the rock up on end and then with a lot of chain and effort use the tractor to tip it into the deeper hole. Now 2' stick above the surface, but it's out of the path of the trench.


Rock in it's final resting place. I broke a 4,000 lb come-along trying to get it here and ended up using the bucket to lift and pull to get it to tip into the deeper hole.


A view of more of the trench

 

[sodamo]

Great job.
I did a similar trench, minus the big rock last year with my Kiotii and BH. Quite rewarding - when finished LOL. Put in an extra conduit just in case. I put 2 2 in hers in mine, never want to have to redig. If interested I posted in the Kioti forum, search for Trench should get it.

David Sent from my iPad using TractorByNet

 

[tractchores]

Great job.
I did a similar trench, minus the big rock last year with my Kiotii and BH. Quite rewarding - when finished LOL. Put in an extra conduit just in case. I put 2 2 in hers in mine, never want to have to redig. If interested I posted in the Kioti forum, search for Trench should get it.

David Sent from my iPad using TractorByNet

Thanks i'll check it out! The plan is for a high voltage conduit, low voltage for controls and a spare. Definitely do not want to dig it up again.

 

[tractchores]

Some pictures from today. I was hoping to get it finished today on the theory that when I got close to the driveway the material would be primarily fill material and easier to dig. However early indications are that it's not. I hit the rockiest section yet today and in 5 hours only moved maybe 20 - 30'. I stopped at a boulder that would not move, the others were right at the edge of my capacity to move.

I also had a close call when I started. There was a lot of rain this morning and the ground was soft. I went to back into position to resume digging, which is on a side hill. The tractor slid and the rear wheel spun, unfortunately the lower wheel dug in and the upper wheel was on a big rock. The net result was the tractor sliding to the side and on 3 wheels right on the edge of tipping. I was in this position for a while unable to move because of trees blocking the way. Ultimately i was able to get it stable enough to get off, put the BH uphill to add weight to that side and that gave enough traction to get out of there. I leveled the area with the FEL and BH prior to resuming work so it wouldn't happen again. The soft soil in the woods are definitely tough and I found myself sliding sideways and moving when using the BH or positioning.


Today's progress... not much


The section I dug today, notice the rocks on the side of the trench. To give some perspective the big boulder in the background is the size of a small car (I didn't move that one), the other ones are in general 2' cubes or bigger. All granite and all piled on top of each other.


Stopped after I hit this one, so far I can tell it is at least 3' x 3', depth is unknown, but when pried with the BH it does not wiggle. I'll have to dig around it and see what I can do.

 

[Stimw]

If you are running conduit you might want to go bigger or add another run in case you decide to put in other things. ???

I had some trenching to do and I made a 6" bucket for my Hoe.
Having a Welding/Fabrication Shop really helps.
I just made a pattern of the 18" bucket side and then cut it out with my Plasma Cutter. Then some other fabrication for the rest of it.
The narrow bucket digs better because it doesn't require as much power to dig.
It really works great for things like stump removal.

 

[JerryK]

Backhoes are fun, arn't they..... !!!!!!

 

[tractchores]

If you are running conduit you might want to go bigger or add another run in case you decide to put in other things. ???

I had some trenching to do and I made a 6" bucket for my Hoe.
Having a Welding/Fabrication Shop really helps.
I just made a pattern of the 18" bucket side and then cut it out with my Plasma Cutter. Then some other fabrication for the rest of it.
The narrow bucket digs better because it doesn't require as much power to dig.
It really works great for things like stump removal.

For the conduit I'm running 3 runs, only 2 will be in use and we'll have extra pulls in them all for future things. No way I'm digging this twice.

Very cool bucket. I wish I had one like that. I thought of buying or renting a smaller one for the project, but our clay soil really sticks, so I even have to bang the 16" bucket at times to get it to empty out.

If only they made one of those rock breaking attachments for small backhoes, then I'd be in business.

 

[tractchores]

Well I managed to get the latest boulder exposed today after work.

I'm now officially wishing I had a MUCH larger machine and hydraulic thumb! Anyone have any ideas on how to get this one out?

I normally would dig to the side of it and push it in, but this one is right between a paved driveway and a tree, so I have to drag it somewhat. I tried to build a ramp and pull it out, but couldn't even budge it (not enough traction). I can stand it on end with the BH and thumb, but cannot get it out of the hole. I've got a new diamond hole saw coming later this week so may try the feather and wedge method again, though it has yet to work on these rocks.... Progress is at a stand still until I can get past this one.

 

[JerryK]

If it wasn't so rocky, you could just dig deeper and put in down deeper in the ground. I have done that with a big double stump heavily encrusted with wet sand. Dug a sloped trench down beside the stump so I could get the tractor lower, then dug down another nine feet and then slid the big stump down into the pit. Pretty scary, but was lots of fun.... You could also use my old standby stump solution... blow it out with a few pounds plastic explosive.. with the added benefit, that if you use enough.... the rock might not even be on your property when you are done...

 

[hawkeye08]

Can you rent a jackhammer?

 

[BeezFun]

Looks like a good candidate for aerial.

 

[sodamo]

Know someone with a really good winch ? Winch it out of the hole.

David Sent from my iPad using TractorByNet

 

[tractchores]

Can you rent a jackhammer?

Possibly, though it would likely be a long job to try to chip it up. That may be the last resort.

Looks like a good candidate for aerial.

Aerial? What's that?

Know someone with a really good winch ? Winch it out of the hole.
David Sent from my iPad using TractorByNet

Don't know anyone with a winch, I did try the last one with a come-along and broke the come along (4k lb). I haven't tried using pulleys to force multiply, that may be an idea...

Likely I'll have to dig a hole nearby and try to pull it forward beyond the tree and then push to the side in a hole. 'course that'll rely on being lucky about not finding a rock the same size or bigger where I have to dig the hole! I could rent a mini-ex to finish the last 100', but I'm thinking anything I can rent easiy won't be able to lift it either.

 

[BeezFun]

Aerial? What's that?

Aerial means running the cable above ground on poles, like the electric company does. As many trees as you have you almost wouldn't notice it. There's pros and cons to each, aerial is subject to ice and falling trees, but it's easy to get at and fix. Buried isn't vulnerable to much except backhoes and post hole diggers, but it's tough to get at and replace.

 

[tractchores]

Aerial means running the cable above ground on poles, like the electric company does. As many trees as you have you almost wouldn't notice it. There's pros and cons to each, aerial is subject to ice and falling trees, but it's easy to get at and fix. Buried isn't vulnerable to much except backhoes and post hole diggers, but it's tough to get at and replace.

ahh ok thanks! All our utilities are underground because of the large number of trees, it'd be getting taken down constantly. It sure would have been quicker to go that route though!

 

[pinetree10]

I'm surprised you've been able to move rocks that big with a tractor that light. On the bright side, you'll have a bunch of nice rocks for landscaping later. Thanks for the pictures and good luck if you're still working on it.

 

[Grandad4]

Well I managed to get the latest boulder exposed today after work.
View attachment 338082
I'm now officially wishing I had a MUCH larger machine and hydraulic thumb! Anyone have any ideas on how to get this one out?

I normally would dig to the side of it and push it in, but this one is right between a paved driveway and a tree, so I have to drag it somewhat. I tried to build a ramp and pull it out, but couldn't even budge it (not enough traction). I can stand it on end with the BH and thumb, but cannot get it out of the hole. I've got a new diamond hole saw coming later this week so may try the feather and wedge method again, though it has yet to work on these rocks.... Progress is at a stand still until I can get past this one.

Mother nature certainly left you with all kinds of surprises in your ground, didn't she? That's a great job you're doing with your backhoe, though. I wish I had better advice concerning how to deal with that boulder, but don't have much experience since my place doesn't seem to have many big rocks. My only suggestion: when we have a really large stump that can't be lifted, dragged or pushed out of its crater, we'll use either the FEL or the BH to roll it up and out. If you can stand that rock up like you say, maybe you can keep it going so it rolls, making one or more platforms to bring it up to ground level. Of course you'd have to figure out some way to safely keep it from rolling back. Good luck!

 

[schmism]

dexpan and a hammerdrill will take care of those large rock issues

 

[JerryK]

You can try the crib method... If you can get one corner of it up, throw a log or timber under it. Then lift the other end up, repeat. It also helps to fill in around the cribbing you put in the hole with dirt or any other fill you have nearby. That makes it a little safer keeping the cribbing from moving around under the rock. Once you can finally get it up to ground level, then you can try to wrestle it onto a metal skid or sled. Afterwards, dig out all the junk you put under the rock. I did this once with a huge rock that was just showing the top of. Lots of fun... !!!

 

[tractchores]

Good news! I just managed to get it out of the way. I used something similar to the crib method, I dug an area out next to it and then was able tolift sides and slide other rocks etc under it until I could tip it on edge. I was barely able to move it around with the BH and with a lot of flipping about finally got it positioned off to the side out of the path of the trench wedge among a couple of other rocks in the same hole. I'll post some pics tomorrow. Thanks for the support and encouragement, only 100' to go!

By the way - talked to the electrical inspector today. My contractor gave me some bad info, the regulation for this run is that it needs to be down 12" since it's in conduit, 120v and GFCI!!! I think I'll do the final 100' at 18" so I can bed it and still have clearance to meet code, that'll make it MUCH easier.