How long to dig a 30'x50'x8' ish deep hole?

[CDN Farm Boy]

I'm looking to dig a hole to bury a bunch of old concrete, dirt/wood/steel debris from an old barn foundation. Trying to decide if it's cheaper to hire it out to a full-size excavator or rent a kx080 and do it myself. I'm plenty skilled as an operator and not looking to factor in my time.

Relative cost from contractor is easy to figure based on how many yds/hr they can dig with their respective machine. The part I'm having trouble with is how long will it take me. The biggest tooth bucket my rental yard has is a 32". Digging is easy clay, no rocks. It doesn't have to be perfect like it would for a foundation, just a hole to put junk in and cover over the next day.

Opinions?

 

[4570Man]

In good easy dirt I could probably do it in two days with my BH 90. Around here you couldn't dig a hole that big.

 

[EddieWalker]

I think the biggest challenge is where are you going to put all that dirt and how are you going to get it from the hole to where it's going to be out of the way? With a full sized excavator, you can probably reach out and down 8 feet from one side to create a ditch ten to 12 feet wide, depending on how big the excavator is and dump the dirt on the other side of the excavator. If you did this down the length of the ditch one way, then went down the other side doing it the other way, you might be able to get a ditch 20 feet wide and 8 feet deep. If it was me, I would go longer rather then trying to go any wider then what you can dig and dump with just the excavator. If you do it that way, and you have a 20 tonne machine or bigger, you should be able to dig the ditch in a day or two. If you are hauling materials with a dump truck, I would expect it to take at least a week. If you want to use a mini excavator, and haul the dirt, it could easily take several weeks. Digging is easy, it's what you do with the dirt that creates all the challenges.

Are you going to rent a dozer to push the dirt back into the hole to cover up what you are burying? I would burn all the timer before burrying it, otherwise, it will just lead to issues down the road as it decomposes. I would also spread the dirt out as thin as I could when filling the hole to get as much of it into the voids as you can. Those void will eventually fill over time and leave you with a mess on the surface. They will also lead to areas of quicksand type mud that you can walk over, maybe drive something light over, but then swallow your up when you go over it with a heavier tractor or truck. Worse stuck of my life was from a situation like this.

 

[Gary Fowler]

I think Eddie nailed it. Given that the amount of surface area needed is available, you could likely do better by digging a much more narrow trench, filling it with debris, then dig another trench as close beside it as you can operate your rig and use the dirt from that hole to backfill the first one. You would of course need more surface area to do that, but it would require only moving the dirt from the first trench to the last one.

You are going to end up with a lot of extra dirt any way you do it.

 

[KubotaToy]

A neighbor who does land clearing for a living, gave me some advice before I started a similar project to help keep what Eddie brings up as the common problems with burying wood or other debris as they decompose. His tips were to spread the debris out as much as possible in as big of a hole as possible, not stack the debris more than 4'-5' deep, make sure you bury it as deep as you can with a minimum of 5' fill over the top and layer the fill dirt either by spreading thin layers of fill with a dozer or excavator. Not sure if any of his advice is any good but I gave it a try.

I had about three acres of 12"-24" tree debris and stumps to bury, I ended up getting a 38 ton excavator and dozer. My first "hole" was a 30' wide trench about 25' deep about 150' long. I put the fill behind the excavator as I was digging the trench. I learned after digging the first one, as Eddie and Gary note, you need a lot of ground to put the the fill. I ended up with digging two similar sized trenches to get all of my tree debris buried, after filling the first one, I just kept digging where I had placed the initial fill and just put the new fill on top of the trench I just filled up. I ended up digging up about an acre of land in all and put about 40 hours on my excavator and about 10 hours on my dozer.

 

[CDN Farm Boy]

In good easy dirt I could probably do it in two days with my BH 90. Around here you couldn't dig a hole that big.

I've got a BH77. Not a chance could this happen with this size of a machine. I don't think a full size backhoe is the right choice either for that matter. If I owned one, I'd make it work but I don't. It's definitely a job for an excavator, the size is the question.

 

[CDN Farm Boy]

I should also clarify a couple things.

I'm not actually burying the framing from the barn. Everything that can be burnt will be or salvaged for other projects. The wood that will be going in the hole is either too rotten to burn or already mixed with too much dirt etc to bother trying to burn. The trouble I have with burning is I'm part of the local FD and well aware of our burn bylaws. Where the debris sits, I don't have room within the regs to burn it. Not even close. Not that I won't burn it, it just won't be as easy as I'd like.

I'd already planned on only a 4-5' layer of the junk and 4-5' of dirt. Layered, packed, poked & prodded to try and avoid as many voids as possible. Size of the hole was already factored for this.

As for the extra dirt, not a problem. With everything is positioned the way it is, where the hole gets dug will be on one side of the junk with the dirt piled on the other side of the machine. That other side of the dirt is a low spot already and needs a couple feet of fill just to get up to level and is a fair bit bigger of surface area than what the hole will be. It's kinda 2 birds with one stone thing. I very rid of the junk in my yard and fill the low spot at the same time. No hauling of dirt necessary. Just grade things out after.

Good point about longer vs wider. I probably would have figured that out quickly once I started but easier planning on that way from the beginning.


So realistically, how long does it take to reach out, dig a bucket full at full reach, rotate 180, dump and return to dig again?

 

[Sprinklerman]

Concrete we either crush for base or pile up and use for erosion problems , steel we save and take to the scrap yard .

 

[KubotaToy]

So realistically, how long does it take to reach out, dig a bucket full at full reach, rotate 180, dump and return to dig again?

Well, I am no dirt professional, just play one on the weekends. I have a good sized excavator and my soil is red clay chert. I spent about 12 hours total digging my first trench, maybe 8 hours on the second one (learning curve). I would say it was about 20 second cycle time for me from scoop to scoop.

 

[fhdesign]

With that size machine you will have a hard time with moving the excavated material out of the way so you can easily get the debris back in the hole, that said I would estimate it should take 4 or 5 days to excavate and backfill. Keep in mind if you hit ground water or it rains hard it could take twice as long.