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How do you determine how deep topsoil is when estimating stripping topsoil off and installing a gravel base for a 4 inch monolithic garage floor slab or is your estimating based solely on historical experience, rule of thumb, testing, sampling or some other factors?

What is your preferred method of compacting the fill side of a cut and fill?

What depth of fill do you first do compaction? Is this repeated until you are at the needed height?

What is your preferred method of compacting a gravel base for a 4 to 6 inch concrete garage floor?

How deep can topsoil be before it is too soft for walking and riding lawn mowers, etc.

What method do you use to spread gravel level before compacting in preparation of pouring a concrete floor?

What is the best equipment to use for spreading gravel evenly before compacting for concrete pours?

Do you use string lines or a transit to determine the height of gravel?

How far apart do you take measurements of the height of gravel before and after compacting it?

Do you use marker paint on compacted gravel to mark plus and minus inches of gravel needed to level out?

What variance tolerance is acceptable to you for variation of compacted gravel height to be ready for a concrete pour?

Location is northeast in Western NY State.
 

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That's quite a list of questions!

The only sure way to tell how deep the topsoil is is to dig a test hole, be it with a shovel, back hoe or auger. Is the topsoil yours after the fact? Around here, topsoil is more valuable than engineered fill, so selling the leftovers makes up for what you have to spend on fill.

Several questions about compaction. 3 or 4 inch minus bank run at 8" lifts. Rent a walk-behind sheepfoot roller and roll the heck out of it. I would imagine no one is going to pay for a tester? So no real way of telling how tight it's getting. After a couple lifts, find the heaviest truck you can and see if it pumps (moves) while wheel-rolling it.

You can never have topsoil too deep. That being said, deeper than 4 to 6 inches is most likely 'undisturbed native soil' which means that due to time and gravity, it's as tight as it's going to get.

Spreading gravel is hard work. Some places have rock chucker trucks, and they mostly do a nice job. Sometimes the local high school football coach needs a nice workout for his team:whistling Use inch minus, crushed not screened. Bigger the rocks, harder to spread. 4" minimum, more is better in freeze & thaw conditions.

Whether you use a string or a laser makes no difference, but the more you check, the better off you'll be. I don't have my calculator handy, but 1 cubic yard of concrete will do a 9' square 4" deep. Every quarter inch thicker adds a couple wheelbarrows more mud.
 
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diplomat
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What is bank run in your area? For me it's gravel with no fines. Not the right aggregate for a sheepsfoot roller.
 

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diplomat
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How do you determine how deep topsoil is when estimating stripping topsoil off and installing a gravel base for a 4 inch monolithic garage floor slab or is your estimating based solely on historical experience, rule of thumb, testing, sampling or some other factors?
All of the above except rule of thumb.

What is your preferred method of compacting the fill side of a cut and fill?
For cohesive soils, sheepsfoot roller. Granular, vibratory with water. We never build on cohesive fill. Dozer tracks often are all it gets if it'll just be landscaping or a residential driveway.

What depth of fill do you first do compaction? Is this repeated until you are at the needed height?
4-12" depending on soil, equipment, engineer specs, etc. All the way up.

What is your preferred method of compacting a gravel base for a 4 to 6 inch concrete garage floor?
larger reversible walk behind vibratory plate compactor.


What method do you use to spread gravel level before compacting in preparation of pouring a concrete floor? What is the best equipment to use for spreading gravel evenly before compacting for concrete pours?
Dozer or skidsteer, manpower.

Do you use string lines or a transit to determine the height of gravel?
Rotary laser, string

How far apart do you take measurements of the height of gravel before and after compacting it?
3-6'

Do you use marker paint on compacted gravel to mark plus and minus inches of gravel needed to level out?
Yes, or shovel a hole to the right depth/ make a pile tamped flat with shovel to the right height. The guy in the machine can set the edge of his blade to this.
What variance tolerance is acceptable to you for variation of compacted gravel height to be ready for a concrete pour?
+/- 1/2", maybe more minus. Looking for minimum slab thickness mostly.
 

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What is bank run in your area? For me it's gravel with no fines. Not the right aggregate for a sheepsfoot roller.
Different stuff, alright. Mostly dirty rocks:laughing:We have a fairly jumbled up geology around here, and it varies from pit to pit and sometimes within a pit, but overall the most common is 4 to 6" cobble max with a pretty good mix of dirt and fines. It generally tightens right up, with the right amount of moisture.
 

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We rarely use a sheepsfoot roller. You can do pretty much anything that you are talking about with a smooth drum roller. Depends how big the area is, but I would look into small smooth drum. 48-54" vibratory roller would do all your cut to fills and compaction of all your sub grades from dirt to stone. Don't do more than 6-8" of fill with smaller roller, if you are grading for slabs and they are level a laser would be easier than string but either will work. If you have help don't waste the paint, grade checker can just tell operator up/down and how much when grading.
 
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