Best way to remove 3’ of bed rock to burry septic tank?

[4570Man]

The top foot is pretty soft and I can probably scratch it out with the backhoe after that it seems to be harder but I haven’t started digging the hole yet. Everything I’ve stated about the rock was concluded by digging the footer which I hit the rock in a few places.

 

[L47TLBwannabe]

The guy across the road split a huge boulder with that expanding stuff last fall. It was sticking out of the ground and was a hazard. The stuff worked to split the stone, I dug on each side of it and pulled the stone apart putting each section below grade.

Most of the afordable blasting around here was by a guy that showed up with an old pickup truck and his dog. He had the stuff, maybe a small auger, tamper, blasting machine and that's about it. If that couldn't do your blasting job, you were probably looking at a serious contract with a construction company.

Yeah this was no boulder this was solid bed rock hardest stuff in the country..... But for this job he could try scratching it with new teeth and if he's got it a ripper I did that in Calgary many years ago breaking up shale and sandstone but a hammer on a 4-8 tonne excavator should be more than sufficient.

 

[Industrial Toys]

Reminds me about the split rock. Got promised a dinner for my troubles, I have yet to see.:confused3:

 

[bdog]

I wish I was closer. We could try and blow it up. It would be a fun experiment as I don’t normally do that type of thing but I do have a rock drill and explosives license.

 

[Oldpath05]

I google (rock hammer) I have my doubts...........
https://www.homedepot.com/p/Estwing...j3IT_Hnllb3HAF83_WBoC3HcQAvD_BwE&gclsrc=aw.ds

 

[Cataclysm]

An excavator with a hammer will work well for you. No need to get too fancy.

My 18,000 pound CAT backhoe digs sandstone pretty well with dragon claws (rock teeth). I have started out sitting on solid sandstone and dug an aerobic tank hole 8'Wx6'Dx14'L. Many times the last 3 or 4 feet are sandstone around here. Makes short work of it.

With limestone we use a 11,800lb Kubota U45 excavator with a hammer. It eats right through hard limestone.

 

[Cataclysm]

Double post.

 

[arkydog]

Back at about eight years ago, I had to jackhammer 2 feet deep by 6 feet by 10 feet with the pneumatic hammer. Backhoe operator was removing chips while two of us we're doing the Hammering taking turns. I had just had carpal tunnel surgery and in a cast on my right wrist, I'm left-handed, and I learn how to move the hammer by bouncing it to the next chisel area.

Only took two with three of us hammering including backhoe operator. he couldn't do it the second day because his hands swelled so bad he couldn't get his gloves on. It worked and only cost me About four or 500 more for the septic. they forgot to dig a test hole for the tank location.

Biggest thing was the backhoe operator being a extremely good because he could remove the chips by putting the bucket right next to our pants and never touching us. He was good

 

[4570Man]

I dug the hole today and got it deeper than expected. It’s about 48” deep. Another foot would be good but it’d probably close enough to just mound some dirt over. I still haven’t decided the final solution.

 

[Tompet]

Re: Best way to remove 3 of bed rock to burry septic tank?

I would get a quote and possibly hire it done. You would want to clear the rock deeper than just the minimum to lay a bed of sand in order to set the tank level. Rather than setting the tank on jagged rock creating voids and high pressure points on the tank bottom.

A small excavator with a hydraulic hammer would make short work of it.

For sandstone...Oldoak hammered out the plan.

 

[4570Man]

Re: Best way to remove 3 of bed rock to burry septic tank?

For sandstone...Oldoak hammered out the plan.

I dug out the top layer of rock pretty easily. The rock below that is white and a lot harder.

 

[Cord]

Re: Best way to remove 3 of bed rock to burry septic tank?

Here is our tank that got planted in rock. This was limestone and it took me a full weekend with a mini excavator and breaker. This rock is certainly harder than sandstone. The biggest problem that I had was getting the bit to bit into the rock. It was made for flat surfaces and would slide off the slopes sides. Turning the breaker horizontally worked on the back wall, but created an oblong hole. This was only an ejector tank which would be only 1/8 the size of a holding tank. For the holding tank I hired a contractor and he used a 18,000lb hoe to rip the rock. Amazing the power difference in machines.

For your install, I'd start with a ripping shank on the excavator and see if it can penetrate the rock. If it can, proceed with that method. If the rock is too hard, then you'll either need a bigger machine or you'll need a breaker. Breakers work by creating cracks in the material so this means it needs room to displace the rock. If you are able to rip a groove around the perimeter or core a row of holes, it'll really speed up the breaking process. I doubt Dexpan will be needed, but it could make the breaking or ripping process go faster.

The top layer of rock is often the softest with harder rock to be found a couple of feet down.

 

[4570Man]

I have my doubts about a ripper doing any good. I did most of the digging with my 36” bucket and then switched to my 18” bucket with rock teeth. I wasn’t able do anything more with the narrower bucket.

 

[4570Man]

I’ve got a little mini excavator pecking away at it. I’m sure glad I didn’t use the handheld jackhammer approach. That would have really sucked.

 

[4570Man]

 

[Alan W.]

I see your putting the ballast to it. Have seen a lot of the plastic tanks float out because they were empty.
Busting rock sucks. Should go smoother from here on .

 

[jhasafety1]

You didn't say how high house is above grade. I think I would put septic tank at bedrock and build the raised bed as mentioned and do the leech field as normal. The only consideration is would you have fall to the raised tank or require a lift?