# What size excavator ??



## rino1494 (Jan 31, 2006)

I am bidding the site work for a new credit union. It is 50' x 127' with a 14' basement. I need to dig 13' to the bottom, plus I need to over excavate another 7' more because the soil underneath is unsuitable. I then need to import and compact modified to bring it up to grade. Soil engineer wants a overdig of 5' past the footers. Therefore, I will be digging 62' x 139'. All material has to be hauled off site. 

The site previously held a nursing center that was demo'ed and backfilled with fly ash. Therefore, I will have to slope the banks for safety. I was orignally thinking about renting a 300 size hoe, but I am second guessing myself and I am leaning towards a 400 size. 

I priced out a 1 month rental on a Cat 330 and it was $9,500. I can get a Volvo 330 for $8,700 and it is brand spanking new. I haven't priced out a 345 or EC460 yet.

What do you guys think ?? I know mobilization will be alot more for the 400 size hoe.


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## PipeGuy (Oct 8, 2004)

rino1494 said:


> I need to dig 13' to the bottom, plus I need to over excavate another 7' more because the soil underneath is unsuitable. I then need to import and compact modified to bring it up to grade. Soil engineer wants a overdig of 5' past the footers. All material has to be hauled off site. What do you guys think ?? I know mobilization will be alot more for the 400 size hoe.


I always lean towards the light end - not the heavy. I'd rather work a little harder than have so much iron that it winds up being in the way. I think a 330 size hoe with a trenching arrangement (not mass excavating) is what I'd do it with. You can comfortably handle a 2-1/2 yard bucket (60") and it has plenty of reach for loading trucks. I'd try to keep the working depth at something less than 17'. You can dig deeper but the working envelope gets pretty small at that point.

Your observation about hauling cost is right on the money. I think a 400 is overkill given the size of the job.

Cat, Hitachi, Volvo...you can hardly go wrong. Ease of operation is probably the biggest factor on a short term rental.


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## tgeb (Feb 9, 2006)

I can't add to that, other than to agree that working harder instead of bigger would probably be the way to go.


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## WC&T (Feb 22, 2010)

I agree with Pipe, for a 8k-9k cy ex. a 300 sized machine will work just fine. Keeping the trucks flowing in and out of the site smoothly is going to be more of a concern than the difference between a 300 & 400 sized hoe. Just don't forget to calculate the extra time in your hoes production time with digging that deep. If you are taking material straight from the ground and placing it into a truck the deeper you get the slower the rotation will be since it has to bring the bucket from -20' to +10 from ground level to dig and load the truck. Your rotation times be twice as long by the time you hit total depth.


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## S.R.E. (Apr 8, 2010)

You might want to consider two excavators. A 300 size to load trucks and a 200 size to feed material to the 300 size. Try to get a 300 size excavator without a thumb on it so you can reach farther with more in the bucket. Stack up the trucks and get r done. :thumbsup:


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## rino1494 (Jan 31, 2006)

Thanks for confirming my initial thoughts. Since I have to slope the banks back, I am thinking about taking 5' off the top and start my slope on that first cut, that way when I come back to take the bottom 15' out I can sit the machine level. I do not wanna make the first cut too deep, then you have trouble with the trucks backing in and pulling out. I found a dump site real close. It is only 2 miles away, but the job is in the middle of town and it took 12 min to get there in a pick up.


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## ConstSvcs (Nov 22, 2007)

Forget the deep cut and structural fill...........we'll install helicals for you!

A few pile caps and you're on to footings.........perfect for problematic load bearing soils :thumbup:

http://www.youtube.com/watch?v=5StJtqtez8g


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