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

[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?