Long story: I'm an electrician more than an excavator. Most of our projects there is an excavator already involved so I step back, let them dig the ditch. I dig when nobody else wants to. It's common to encounter ledge. There are solutions. NEC says covering with 2" concrete is acceptable if a proper depth ditch can't be dug. We have a project where it gets complicated, therefore expensive to use other ways. we need about ?100? feet of 12" deep trench through dolomite ledge. I imagined a diamond saw 3' diameter mounted on excavator or CTL. It appears there is no such thing. I've talked with a few professionals, they agree it is a hydraulic hammer job, might take a week. Another wants to blast. I don't think the owner, or neighbors will go for that. Any suggestions? Ditch I need will be 12" deep, at least 6" wide, I'll say 100' long.
Dolomite is some hard ****, it doesn’t shear all that great unless there’s some sort of relief created. In my experience it does hammer decent. We did some 108” piers 20’ deep in dolostone/dolomite. We perforated with 24” down hole hammer in a pattern then used a 108” core barrel with C4 teeth to create the 108” shaft then came back with various augers to fracture the perforated material and remove it. Based on your explanation I would say hammer it. Sometimes it takes what it takes. I have seen blasting used quite accurately. Years ago we’d use det cord to break cores loose. Thing is, to blast you have to drill and a good bit of the time doing that could be used hammering it anyway.
They make rock saws for skids/CTL's and big trenchers. I've seen attachments that fit on larger excavators as well. Now finding one to rent will probably be an issue. Heavy-Duty Rock Saw Cut through asphalt and concrete with greater efficiency with the Heavy-Duty Rock Saw. erskineattachments.com Do you have a Ditch Witch dealer close? The DW dealer is next to my closest Cat branch and I've seen trenchers there with pretty good sized rock saws. Ditch Witch® acquires HydraWheel™ line of rock saws - Ditch Witch Ditch Witch announced today that it has acquired specific assets from River City Manufacturing, Inc., including the HydraWheel design of rock saws. www.ditchwitch.com If you go the hammer route rent a 20-30K excavator with a hammer on it and clean the ditch with your backhoe or mini. I have a hammer for our 305's that is very useful on a lot of things but it's not going to get the production needed on what you are doing.
Primacord......
100' long, 1' deep, 6" wide? Nah hammer it out. Once the pre-blast survey and seismographs are placed on the adjoining properties one can rent a 20K machine with a hammer for $6-7K a week and be done with the job before the "you cracked my house" lawsuits showing up.
July 4th after dark.....no problem-o.....
I'm thinking CM1995 might be the best option I've heard. Blasting isn't going to be a good choice, too many whiney people to appease, likely needs permits on a higher level than excavation. I had envisioned a rock saw on a heavy machine would work. It seems nothing like that exists locally. I've been on the dumb end of a diamond chainsaw hand held, by the end of the first day not much to show for my efforts. With a 14" blade, I might go 5" deep, then jack hammer to clear that first 5". Next day less is accomplished. Third day may or may not accomplish my goal.
There is a used skid steer 12“ planer on CL right now for 2500 that would do that job. Be even better with some water.
Also hammer. Skid steers need great conditions to cut rock. Good traction, smooth. Just get whatever hoe you can rent with a hammer. It may not be as big as you want but just do it. For a foot deep I would just march into it and lay waste plenty deep, then return with a bucket and clean it out. Little bit of bedding to smooth for the conduit as needed. Then pour it in.
I was on a job once where the rock was so hard they had a blaster come in and drill it in a 12" grid pattern to give the hammer some relief and a place for the rock to fracture. It was slow but blasting was not a option in downtown Greenwich CT
In India the answer would be hire a couple of hundred guys with lump hammers and cold chisels..... Seen it done more than once.
I've seen similar in Africa as well.
Dolomite is a Limestone that commands respect as hard as Granite. Acid Resistant, extremely Dense and usually a Really DARK Gray Color. Can be Chipped or shattered yet requires MASSIVE Pressure as in ANFO. JY is Correct, saw the Hammer set up they ended up using on Dolomitic Limestone, Cut multiple holes, break out between the holes. Planers and Carbide bits just Smoke and Spray Sparks as they erode. Several quarries here mine it, one was aptly Nicknamed Hell Hole, by the Nuke, supplied 98% of ALL the rock in the Plant's Concrete. Blast Drillers hated making the Bore Holes for the Charges, drills took a shellacking.
AKA DetCord.
Well there is always Dexpan. Dexpan Up to 30% Off Wholesale Discounts! Dexpan Non-Explosive Expansive Demolition Grout for sale. Easy concrete removal, rock breaking, cracking and splitting. www.dexpan.com
Rutland VT might find 500 men on the sidewalks on any warm day. Most live in run down motels paid for by the State. None want to work.
Danby VT is home of the world's largest underground marble quarry. in the 1980s they wanted to avoid damage to marble by blasting. The overlying ledge is Dolomite. They contracted to have three tunnels each 500 feet deep through the low value rock above the softer marble. It was a ten month contract. At two years the contractor gave up.
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I looked in to a drum cutter for a 1800' water line project. A lot of them are only good up to 30 MPa rock. Dolomite normally ranges 30-60 MPa. Weathered rock can be easier to fracture and the really hard stuff is up around 90 MPa.
I've seen it work. My neighbor as many, had a 7' boulder in his cellar. It took up a lot of space. He felt blasting wasn't an option. I don't remember the cost. Our boulders are extremely hard, probably some variety of granite. He hired someone to drill several holes. It broke it up to pieces he could cary up the stairs.
Not for one project, but if someone were available to cut it....... I pictured a hydraulic saw on an excavator. If there is such a thing, I haven't found it. I have used a cut off chainsaw with diamond blade to trench 6" deep in ledge. That is for short sections, EXTREMELY labor intensive. An air powered hand held hammer is not for old people.
Larger site contractor here has one a 330 or 340 equipped with GPS to grind rock slopes to grade. Don't know how productive it is though. Here's a rock saw for large excavators - #1 Quality Excavator Rock Saw | Quarrying, Mining, Excavation Our excavator rock saw is used in a wide variety of applications including dimensional stone quarries, excavation, mining, and earth moving. Contact us today! rocktools.com
I wonder how much one of those blades costs!
The price is so high that you're speechless?
It's all relative to what the value of the operation is.
I ran one of these. It was used to cut a trench for under-drains along interstate highways. It would cut through asphalt and concrete. Straight trenches only.
Had to be one dusty SOB with that seat hanging so close to the saw.
Well.........this is a reluctant landlord. Rented a building to a fabricator with an obsession for buying big industrial equipment. At this point he has sticker shock. Supply to the building is not going to power the new machines. I believe the Catch 22 of overhead upgrade prices it out of the question. I believe the setback of underground is ledge, maybe 100'. Code calls for it to be covered by 2" concrete. I am not confident. A 3-5/8 OD pipe wants concrete on all sides. I'm describing the required trench as 12" Deep, anything over 8" wide. Buying a $100,000 machine isn't in the math for this job.
Fist bump @tTinkerer I ran a much smaller version of that thing. Much smaller half the wheel size but doing the same job. And yes it was Dusty nasty noisy. I was cutting in a trench drain for about 4,000 ft down I-5.
The contractor I worked for had that dusty SOB on a purchase rental contract. We did many miles of interstate highways putting in under-drains. A laser controlled Vermeer trencher followed me, excavating the trench. It was rigged to drop 4 inch perforated drain tile in.
Depending on the cable diameter an expansion agent maybe a goer and lay the cable in the crack. No silly bugger will dig it up if the rock is that hard. Seen this done when I was working on the optic fibre installation. We came across a lump of pink granite, destroyed a moil in 8hrs on a 30 ton digger. The cable was to be laid at 1.2 metres or 800mm in condute. The phone company drilled a series of holes a filled the with the agent and next day laid the cable without condute at 500mm.
It seems to have boiled down to pushing all the cheap, large, industrial machines to a corner. The man renting the building won't be able to power them. The facility has only Delta 240,120,208. Most of the machines prefer 480 V three phase. Landlord isn't interrested in a $30,000. investment.
Next potential, Convert to 240 Single or multi Phase motors.
I find it hard to believe that if he already has 3 phase of any kind that it can't be used to power his machines. Either rewire them or set a transformer. He can't possibly run them all at once unless he has a crew.
The facility shares 200 amps at 240. Several buildings, several users. Hundreds of feet for voltage loss. Down to 5 buildings supplied with 100 amps in decending order. Tennant has a compressor needs 66 amps three phase at 240. Would be only 33 amps if 480. Big building seasonally houses a few other builders. I explained that I have capability to do much of what he hopes to do. I have 100 amps single phase in my facility. He is broken hearted that his auction bargain equipment won't work. I agree, a 5 HP air compressor will do what he needs. He already has giant welders pushed into a corner, he can't power, bought a chinese 45 amp single phase he thinks is magic.
So far, it's one person year round. He thinks he will one day have a crew. The power on the property is antique. It started as 200 amps three phase, they kept adding more buildings, more machines. This was a big empty nearly unused building they rented out. I did mention his obsession with buying huge industrial machines, why not a big cheap industrial generator for his three times a year he needs to use BIG machines.
Hell I have a 1000a feed at meter for house and shop where was figuring on at least one other structure, just on single phase.