# Trenching through coral rock



## Southeast Power (Jan 18, 2009)

Due to the scarce nature of this machine, those of you that work in areas with dense rock, what method or machine do you use to cut through that type of material?


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## gpop (May 14, 2018)

If you find a way tell us.
We trench the easy then use a excavator with a rock bucket and another with a jack hammer. Around the lake we have rocks that are 1-3 feet thick but 20' across. We just end up beating the hell out of them till they give.


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## MHElectric (Oct 14, 2011)

How come every single job you guys do is a one-of-a-kind absolute crap show? Thats seriously impressive. 

I'd think that sooner or later you would have a job where it wasn't 2ft from the edge of the pool or digging a ditch across the lava crust on Mars.


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## Cow (Jan 16, 2008)

No coral rock, but we have caliche over here.

Sometimes they use a jackhammer attachment on an excavator depending on how far they are going, other times they use a wheel trencher like you have posted for longer runs.

You can't be the only contractor in your area dealing with the stuff, is there an excavation contractor you can sub, that'll have the equipment to handle it?


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## Southeast Power (Jan 18, 2009)

MHElectric said:


> How come every single job you guys do is a one-of-a-kind absolute crap show? Thats seriously impressive.
> 
> I'd think that sooner or later you would have a job where it wasn't 2ft from the edge of the pool or digging a ditch across the lava crust on Mars.


I really feel like Captain Quinn from the movie Jaws. Everyone turns down the job and they end up with us and have to pay the price. Lol


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## Southeast Power (Jan 18, 2009)

Cow said:


> No coral rock, but we have caliche over here.
> 
> Sometimes they use a jackhammer attachment on an excavator depending on how far they are going, other times they use a wheel trencher like you have posted for longer runs.
> 
> You can't be the only contractor in your area dealing with the stuff, is there an excavation contractor you can sub, that'll have the equipment to handle it?


We have a sub we call for missile bore jobs. Maybe they cut rock too.


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## micromind (Aug 11, 2007)

When I lived in central Oregon, I'm pretty sure that the lava rock around there went all the way to China..........

I would often use the DuPont Bro's. Excavation Company...........dynamite........

I don't know how this would work in coral but in lava, a good-size dozer with a single ripper tooth on the back would cut a trench about 3" wide and a couple of inches deep with each pass.


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## splatz (May 23, 2015)

Southeast Power said:


> I really feel like Captain Quinn from the movie Jaws.


"You're going to need a bigger ditch witch." 

That ditch witch might work or might fail misterably, that's what we see around here, the rocks are way too big and way too hard. 

Around here pretty much everyone with an excavator has a hydraulic hammer and don't leave home without both. One utility company that was a customer of mine built a hydraulic hammer with a shaft like an old fashioned star bit. Your local ditchdiggers probably know how to handle it. 

I wonder if that coral rock crumbles into coral sand, you might get lucky and it goes faster than you expect with the right machine. I don't know if you hit it with a rotary hammer or anything to see just how hard it's going to be.


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## oldsparky52 (Feb 25, 2020)

MHElectric said:


> How come every single job you guys do is a one-of-a-kind absolute crap show?


Because that's where the money is.  

You don't think he wants to wire condos when he has the skills he's shown on this site do you?


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## oldsparky52 (Feb 25, 2020)

I would attempt it with a backhoe (CAT 426?) with a narrow bucket with rock teeth and have a quickie saw with a diamond blade to cut the edges (only after I could not find an excavation contractor to do it).


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## Cow (Jan 16, 2008)

micromind said:


> When I lived in central Oregon, I'm pretty sure that the lava rock around there went all the way to China..........
> 
> I would often use the DuPont Bro's. Excavation Company...........dynamite........
> 
> I don't know how this would work in coral but in lava, a good-size dozer with a single ripper tooth on the back would cut a trench about 3" wide and a couple of inches deep with each pass.


My mom lives in Bend, I'd have to agree with the lava rock to China comment. I'll bet driving ground rods around there isn't a popular grounding method either....


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## Signal1 (Feb 10, 2016)

Southeast Power said:


> I really feel like Captain Quinn from the movie Jaws. Everyone turns down the job and they end up with us and have to pay the price. Lol


*Quint


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## MikeFL (Apr 16, 2016)

What are the dimensions of the trench?
What are you burying?
Concrete cutting specialty contractors are something to consider.


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## MHElectric (Oct 14, 2011)

oldsparky52 said:


> Because that's where the money is.
> 
> You don't think he wants to wire condos when he has the skills he's shown on this site do you?





oldsparky52 said:


> Because that's where the money is.
> 
> You don't think he wants to wire condos when he has the skills he's shown on this site do you?


No doubt. 

I bet he eats a bottle of Tums a day.


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## oldsparky52 (Feb 25, 2020)

MHElectric said:


> No doubt.
> 
> I bet he eats a bottle of Tums a day.


I bet he gets a charge out of doing this kind of work, it gets in your blood. Although 100° days would put me out.


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## Southeast Power (Jan 18, 2009)

My Sunbelt rep said they just put a rock chain on a trencher and that seems to work.
the coral rock isn’t as hard as boulders but, I remember working with my dad as a teenager, they had a job at a state park in Everglades National Park. They had the same kind of rock there. The great trophy on that job was a pick that has the end curled like something out of the Nightmare before Christmas logo.


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## Southeast Power (Jan 18, 2009)

MHElectric said:


> No doubt.
> 
> I bet he eats a bottle of Tums a day.


We/ I spend quite a bit of time planning.
our guys have mad skills.
also, we have good suppliers, we don’t beat them up on pricing, don’t do returns, and we pay our bills.


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## MHElectric (Oct 14, 2011)

Southeast Power said:


> We/ I spend quite a bit of time planning.
> our guys have mad skills.
> also, we have good suppliers, we don’t beat them up on pricing, don’t do returns, and we pay our bills.


Don't think I'm coming off like a hater, you definitely look like you have your stuff together.

I just don't like tons of stress personally. 

A few of these jobs here and there are extremely profitable and challenging/rewarding. However....non-stop nightmares back to back to back get old quick. At least for me. It's like I'm stuck in an 80's horror flick.


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## Southeast Power (Jan 18, 2009)

MikeFL said:


> What are the dimensions of the trench?
> What are you burying?
> Concrete cutting specialty contractors are something to consider.


I reached out to our underground bore sub. They flat out refused any job with coral rock. He did say if we had success with a certain type of machine, they would send us all of the work we could handle.
that rock cutting wheel machine I saw on EBay was $14,000. Sunbelt rents theirs for $1,000 per day. It might be better to just buy it if the job was any decent size.


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## oldsparky52 (Feb 25, 2020)

Southeast Power said:


> It might be better to just buy it if the job was any decent size.


Careful, you might wind up with a whole new line of work.


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## gpop (May 14, 2018)

Southeast Power said:


> My Sunbelt rep said they just put a rock chain on a trencher and that seems to work.


True but it beats the heck out of the operator and will shake the trencher until something rattles loose.


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## micromind (Aug 11, 2007)

Cow said:


> My mom lives in Bend, I'd have to agree with the lava rock to China comment. I'll bet driving ground rods around there isn't a popular grounding method either....


I lived in Bend from 1974 to 1991......

The inspectors would let us lay ground rods horizontally in the ditch; otherwise it'd be nearly impossible to drive them in some places. 

It's funny though, the landfill out on Knott road is very likely over 100' deep. Just dirt, no rocks.


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## Wirenuting (Sep 12, 2010)

Only way I’ve ever seen was hitting it with a ship.... Then again it end so well....
View attachment 151551


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## macmikeman (Jan 23, 2007)

Cow said:


> No coral rock, but we have caliche over here.
> 
> Sometimes they use a jackhammer attachment on an excavator depending on how far they are going, other times they use a wheel trencher like you have posted for longer runs.
> 
> You can't be the only contractor in your area dealing with the stuff, is there an excavation contractor you can sub, that'll have the equipment to handle it?



We got's lava. Blue Rock is extreme hard very old lava, impossible to drill thru. We use a backhoe with the jackhammer attachment , but we call it a hop toe. I had to dig out my footings and sewer line ditch using one of those . Took 4 days of hammering to get it all done.


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## LARMGUY (Aug 22, 2010)

How come everyone is trenching? A directional boring machine is easy and cheap.

Well so much for not reading the entire thread.





__





StackPath






www.constructionequipment.com





You might want to call Vermeer and Ditch Witch for advice.


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## Cow (Jan 16, 2008)

LARMGUY said:


> How come everyone is trenching? *A directional boring machine is easy and cheap.*


I've never heard that before. What do you think it costs to bore versus using open trench?


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## LARMGUY (Aug 22, 2010)

Dunno. I've never trenched. We always used directional. Especially on this one job where they had fiber everywhere and no one absolutely no one knew where it was.


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## Southeast Power (Jan 18, 2009)

We decided to use a backhoe with a 12” we took a 3 ton Kubota mini excavator with a 24” bucket out to the site.
We were able to scratch down 6” with just about 3 passes. I think a heavier marking with a smaller. Bucket will get us where we need to be in a day.


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## oldsparky52 (Feb 25, 2020)

Southeast Power said:


> We decided to use a backhoe with a 12” we took a 3 ton Kubota mini excavator with a 24” bucket out to the site.
> We were able to scratch down 6” with just about 3 passes. I think a heavier marking with a smaller. Bucket will get us where we need to be in a day.


Get the rock teeth if they are available.


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## Cow (Jan 16, 2008)

Southeast Power said:


> We decided to use a backhoe with a 12” we took a 3 ton Kubota mini excavator with a 24” bucket out to the site.
> We were able to scratch down 6” with just about 3 passes. I think a heavier marking with a smaller. Bucket will get us where we need to be in a day.


We have several different buckets for our mini, 12" and 18" toothed buckets being a couple of them. On our machine, when using the 12", I have to watch my depth because it rubs the bucket pins against the side of the ditch if you go much deeper then the bucket. The 18" doesn't have that problem. I'm not sure if that's how all mini's are or just our 35G. Just something to lookout for, in dirt not much of a problem, in harder coral rock might be an issue??

I'm glad to hear the mini will get it done though, that sounds a lot simpler and more straightforward than the other options.


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## Southeast Power (Jan 18, 2009)

We ended up with a backhoe and a 12" regular bucket.
We scratched our way through it.
The good news is we have some nice fill for our slab base.


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## oldsparky52 (Feb 25, 2020)

oldsparky52 said:


> I would attempt it with a backhoe (CAT 426?) with a narrow bucket with rock teeth and have a quickie saw with a diamond blade to cut the edges (only after I could not find an excavation contractor to do it).





Southeast Power said:


> We ended up with a backhoe and a 12" regular bucket.
> We scratched our way through it.
> The good news is we have some nice fill for our slab base.




Thanks for sharing this. Curious, were rock teeth available or did you decide to just not worry about it?


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## Nemikon (Nov 7, 2021)

I used to use a ground cutter (trencher), now I do trench work with a backhoe loader


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