What compaction factor

[surveyorjoe]

I am working on a project where I need to provide a quantity for three topsoil piles. I have the raw number calculated at 120,000 cubic yards. These topsoil piles were built with large scrappers and stand 18 feet high. I am trying to find out what, if any, compaction factor would be added to a stockpile of this sort to give a more accurate quantity?

Thank you.

 

[sc]

With earthworks, unless you know the exact details of the soil or machinery masses, number of passes, etc you cannot report on the exact quantity in the pile.

I once worked for a survey firm that did stockpile volumes and waste heap volumes for mining companies. The mining company and their earthmoving contractor both agreed that the as placed volume was sufficient for contract payments. The contractor had allowed for approximate compaction, soil properties, etc in his contract rates.

The best thing to do is report the quantity in terms of volume occupied by the pile (as done), don't get involved in estimating masses or compaction as there are too many unknowns. Also it is worth placing a disclaimer on the volume report that the quantity calculated is not 100% accurate due to limitations in survey and calculations methods.

What is the reason that you wish to refine the volume for?


Regards
sc

 

[VAD]

Hello Surveyorjoe:

Looks like you are working for a contractor. Generally this is always a contractor's claim which the client generally agrees on. Check on your specs for topsoil payment. Try something 5 % or smaller. You may end up with a 50/50 agreement. The client may want top stick to the specs. The other way by ground cross-sections before and after stripping the topsoil is a nightmare which few contractors want to abide with as this prevents them from bailing in the dirt. Win some loose some is the ticket on this one.

Good Luck

 

[reddog99o]

Use 20% and you'll be fine.



R.A. Hassett, P.E.
rah1616@hotmail.com

 

[surveyorjoe]

Thank you guys. I think I will not use any compaction factor and let the Contractor work that out with the Client. Your responses are very much appreciated.

 

[KRSServices]

Surveyorjoe, I think you are making a mistake in not assuming a compaction factor, but let me ask this first.

What is the measurement and payment for the material that has been stockpiled? If it is stockpile measurement then the contractor will happily agree to no compaction factor because he will get paid for dirt that in reality does not exist. If it is based upon pre-grading topo shots and a calculated quantity then he still wins, but has some arguing to do. Depending on the material and moisture content, you could have as much as 10% to 20% fluff, which the owner will pay for if not factored into the equation. If the contract provides language that allows the engineer to utilize compaction factors then it will be a simpiler task. Good luck.

KRS Services

http://www.krs-services.com

 

[SirAl]

I don't know how you could establish a reasonable compaction factor for topsoil. Just too variable. Its difficult enough for clay, even gravel can vary depending upon gradation. Good luck!

 

[sc]

KRS

What I am suggesting is that surveyorjoe, calculates an as is volume without trying to apply corrections for compaction. It is then up to the other parties involved to decide how to apply rates of compaction, etc.

As surveyorjoe is a surveyor and not an earthworks specialist or engineer, I am suggesting that he leave the earthworks/engineering decisions to the other parties involved.

The compaction should be considered in the payments.

regards

sc

 

[KRSServices]

sc,

I agree with you completely, well maybe with one caveat. The raw volume is fine as long as surveyorjoe's numbers are not used as the final quantity survey of the material volume. He could be setting himself up for a little grief if his numbers are final and a dispute arises. Maybe he can contact the project geotech for a qualifier constant to assist in the volume calculation.

You are absolutely correct though, because in the old days before the scales, the surveyor would provide the volume and I would adjust with a compaction factor I felt was appropriate in accordance with good construction experience and practice. The factors were also defined in the contract. I can't recall any disputes with that methodology.

KRS Services

http://www.krs-services.com

 

[surveyorjoe]

Hey thanks for the input guys. I am not sure that I agree that the contractor will be happy without some sort of compaction factor as he is paid on the amount of dirt moved. Obviously there is going to be more dirt in the stockpile than my calcs will show. These big scrapers will compact it some as they pass over it. The contractor is working an agreement with the client (a local city and their engineers) for a compaction factor. I got them what they needed though.

Thank you again for your help.

 

[dicksewerrat]

Maybe you should be paying by the ton. No problems then.

 

[BigH]

Or pay by m3 in place - then it is up to the contractor to worry about his volumes at time of bid.