Keeping grade flat

[Riphil]

Howdy. Great website, glad I found it.

quick intro, small excavation company(just me) with a mini ex and tracked skid, I rent the bigger stuff when I need it.

most of my work is sewer and water line install/repair, some demo, and lots of grading for landscape and flat work contractors. I’m starting to get invited to bid on foundations and occasionally winning them.

2 questions for the guys doing foundations:
What do you consider “in spec” for grade on your holes? .5”, 1/10, 1 inch, 2 inch? Most of my flat work prep needs to be within .25”, which means I get as close as I can with the skid and hand rake the rest. Not super hard if you’ve got good gravel, but time consuming. As a 1 man crew, keeping my foundations on grade means I dig a little bit, hop out of the excavator and shoot grade, mark the spots that are on grade or close with paint, then use those spots as reference as I dig a little more, then repeat the process. Lots of in-and-out and really time consuming. I’m just curious what you guys will allow as far as variance from grade from one side of the hole to the other.

2nd question, what methods are using to achieve your tolerances? I think the best solution is a good ground guy with a rod and a rake(and an eye for grade) but it’s just me for right now. I recently purchased a Spectra CR600 receiver and used the mag mount on my boom for the last one I did. It did speed me up, no more in-and-out if the cab, but I found when I was done there was as much as 5” variance across the hole (it was a big one, 80’x75’. A few hours in the skid cleaned it up) I.e I was close but not close enough. (To be fair, the CR600 states it’s to be used on mini excavators, I had it on a 270) Thinking about stepping up to the LR60 or equivalent, or possibly even looking into a 2d system.

Just wanted to pick your guys’ brains a little bit. What works for you? Any tips or tricks are appreciated

 

[NepeanGC]

'in spec' varies from contractor to contractor I find. For foundations here, I'm rarely off more than 1/2". That said, I dug an addition for a local forming company last year, and the guys were blown away by how flat everything was...apparently the standard that they were used to was +/-2-3"

Get yourself a grade man first and foremost. You're wasting way too much time and $$$ hopping in and out of the machine.

Depending on the job and machine we use a rotary laser, zip level, Trimble surveying GPS, machine control, or any combination of those.

 

[treemuncher]

I use a Bullseye laser receiver when I need to cut grade (only for myself these days - I stay out of dirt work) because it senses true vertical in 2 planes. When the lights are solid, the receiver is plumb and there are also pitch lights that show side-to-side level. Lock your bucket in full dump, stick near straight up-down and set your grade with the receiver. Now, every time you check grade, your machine is in the exact same position as long as the lights are not flashing and hold solid green, your teeth are on grade. No need for a man in the trench or to get out to check grade.

The Bullseye is much larger, brighter and easier to see that the receivers that came with my laser unit. Makes the work faster and more precise. There are also different settings for different levels of tolerances and whether you are running on a blade (dozer) or bucket (hoe).

 

[suladas]

I use a LR60 for digging basements, it's great. I am generally +-1" on a basement, sometimes as close as +-0.5". It's just too time consuming to try and get better then that without someone in the hole, a lot also depends on soil quality. I run it on the most sensitive setting, and there is still like 1/2" variance where it will show grade as good, which is good for a basement but maybe not as precise as you need.

 

[AzIron]

Most concrete guys I dig for look for the bottom side of tone on a receiver and it's good but I do have one or 2 that want within a half inch it takes almost twice as long to dig if there grade man wont shovel

 

[suladas]

Most concrete guys I dig for look for the bottom side of tone on a receiver and it's good but I do have one or 2 that want within a half inch it takes almost twice as long to dig if there grade man wont shovel

There’s a few like that here. Some say they don’t own a shovel because they won’t dig. I’ve come pretty close to throwing a shovel at one with dumb comments like that. I once had one complain I was off by like 4”, I show up and they set off one spot in the garage that was 6” long of trench area that was about 3” high and they refused to dig it. It would have taken under a minute to fix, less time then the phone call to complain. I missed it because I was digging in the dark. IMO on a 2000 sqft basement if there’s 30 minutes hand digging to make it perfect, there’s nothing to bitch about.

 

[Riphil]

Thanks guys, appreciate the input

Get yourself a grade man first and foremost. You're wasting way too much time and $$$ hopping in and out of the machine.

I agree about wasting time and money. I’m probably still a little ways out from hiring a guy full-time and I doubt I’ll be able to find a part time grade guy worth his salt. I love the idea of leveraging tech and tools to be able to eliminate a guy in the hole. I do have some nephews that are about ready to start doing real work, I may have to invest a little time into getting them trained up until I can get the tech side dialed in.

I use a Bullseye laser receiver when I need to cut grade

I use a LR60 for digging basements,

I had heard of the LR60, had not heard of the Bullseye. Looked it up and it looks like the same unit as the LR60 but in Red. Looks like they’re built by the same manufacturer. I think that’s going to be my next step. The CR600 is great but with no plumb indicator it’s hard to stay as close as I’d like to be. Thanks for sharing your methods with me and I welcome any more

 

[NepeanGC]

Thanks guys, appreciate the input



I agree about wasting time and money. I’m probably still a little ways out from hiring a guy full-time and I doubt I’ll be able to find a part time grade guy worth his salt. I love the idea of leveraging tech and tools to be able to eliminate a guy in the hole. I do have some nephews that are about ready to start doing real work, I may have to invest a little time into getting them trained up until I can get the tech side dialed in.

I've got part time staff I've trained to shoot grade for me. Only takes me a couple hours to get them up to speed usually. I'm not paying them to do layout, only use a laser receiver and can of paint. It's a pretty cushy job tbh, I know I don't have a problem finding people to do it...digging with a hand shovel or finish raking gravel is a whole other story...Hence why we have tiltrotators.

Tech ain't cheap, but my grade control system paid for itself in 3 months of work.

 

[Riphil]

Depending on the job and machine we use a rotary laser, zip level, Trimble surveying GPS, machine control, or any combination of those.

so I just looked up the Zip Level, I had never seen it before. How do you like it? Preference between it and a rotary laser?

 

[NepeanGC]

so I just looked up the Zip Level, I had never seen it before. How do you like it? Preference between it and a rotary laser?

I love our zip level. It's great for stuff when line of sight is impossible, or a grade rod will be a pain. Also nice that you literally just set the box down, pull out the line, and you're ready to go. Much faster than setting up a laser.
The drawback, is of course the hose. If the hose gets damaged it needs to go in for repairs. You also can't have multiple receivers like you could with a laser. I use ours a lot for quoting projects.

 

[Tones]

I've been working with a bloke who insists on grading to the mm. He achieves by using it using a laser plain pulled by a compact JD tractor. We've laid out 600 tons of gravel in 1.5 has with that and a 922CTL

 

[JPSouth]

Flatwork a guy sure likes to see things within 1/4" or so, where there's slope is more important. If the subgrade is too high it causes problems with rebar. We position mats and cages with chairs, don't want wire ties near the surface when finishing. With the screened rock we use here, usually leave the raked grade about 1/4" high, by the time you run two passes with a plate compactor it's pretty close to right.

Foundations, if we're in anything like clay or loam (which isn't often), like to see holes within 1/2" or so but it all depends on how stable the floor is. There's times we've gotta run a trench compactor even if we don't go below the virgin surface. If anything, be a little deep as it's far cheaper to pay for an extra yard of mud rather than spend a bunch of time trying to hand-skin hard soils down to grade. If we're in rock, especially river run (large cobble) shales or limestone, rules change again. Long as the hole is close to grade but on the low side of the green line, things are good. No sense beating the machine to pieces, you're never going to get a pool table anyway.

Things like this happen now and then. Hole was dug for us by a neighbor of the homeowner, he had a bigger machine but evidently was a little light on his QC as the hole was off 16" from the low side, and two sides were anywhere from 2' - 4' out of square. So I brought mine in and leveled/squared the thing up, dug a ramp in which should have been done to start with, silt turned to flour doing it, so we had to haul in screened rock to make something like a stable base for footings and floor..PITA. And expensive as this place wasn't exactly next door to anything. The days we had wind on this job were a real treat.