Stipping Topsoil and placing Topsoil loss factor
Stipping Topsoil and placing Topsoil loss factor
(OP)
We have a site that has required the contractor to strip and stockpile the top foot of soil after clearing and grubbing has been completed. This topsoil was to be saved for re-use as topsoil after subgrading operations were completed. After subgrading was completed the contractor placed the topsoil from the stockpile into the landscaped area at the same depth of 1 foot with a required compaction of between 85% and 90%. The area of stripping vs the area of placing topsoil is the same. However there was a need to import a significant amount of topsoil. (like half of the stockpile) within the same amount of area. I have heard of shrinkage from bank volume to compacted place yards but not that high. The soil type is a clay loam. Does anyone have shrinkage factors for this type of situation. I have gone through almost 30 pages of interesting threads regarding shrinkage and cut and fill calcs but they don't speicifically deal with soley topsoil and the fact the compaction requirements of topsoil placement is less. We figured about 20% shrinkage which seems to be reasonable. Thank You DHF





RE: Stipping Topsoil and placing Topsoil loss factor
Regarding shrinkage, I can vaguely remember about 15%.
I am not sure if I have provided you with the answers you need. What I know that this item has always given problems and answers are not easy unless one has monitored the site during the operations.
Regards
RE: Stipping Topsoil and placing Topsoil loss factor
1. The topsoil thickness was specified for both stripping and placing at 12".
2. We paid for topsoil stripping as part of the lump sum item for earthwork and we can determine the area from where it was stripped because that was specified as well.
3. I don't think we did survey the areas after it was strippped.
Thank you for responding. Lets see what others have to say about the shrinkage. Oh by the way the compaction requirement on the placed topsoil is 85% max and not between 85 and 80 as I stated before.
RE: Stipping Topsoil and placing Topsoil loss factor
Advice: during any soil investigation - that a few hand dug holes be dug to get a better idea of actual thickness of topsoil rather than "measure" the thickness in the spoon. I learned this from someone that had been once burned and decided I'd rather not be.
RE: Stipping Topsoil and placing Topsoil loss factor
If no moitoring of the topsoil stripping was done,
then you can not be sure that 12" of soil was striped.
Shrinkage (in my opinion) does not enter into the equation
since the topsoil should not be be densly compacted.
Also, I cannot picture a site where all of the stripped
soil (@12") would be respread (@12") unless the site had
no buildings or parking areas.
My thoughts are that much less than 12" were stripped
RE: Stipping Topsoil and placing Topsoil loss factor
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Hope that works - I hadn't written it down before downloading but got the url off my Download Accelerator. If not try to find me.
RE: Stipping Topsoil and placing Topsoil loss factor
RE: Stipping Topsoil and placing Topsoil loss factor
Regardless of the depth of topsoil prior to construction, we only require that 6" be replaced. This often leaves us with upwards of 10,000 cubic yards of topsoil to remove from a 30 acre site. It could be that we specify only 6" of topsoil replacement because we want to ensure that our building pads are adequately compacted.
RE: Stipping Topsoil and placing Topsoil loss factor
To compact to 90% (I assume modifed) for 12 inches seems to be a waste of good material. If in its natural state it is at 70% (and it depends a great deal on site specific conditions), to go to 90% is a 28% increase. the other factor that has not been considerered is loss. When ever you move material to a stockpile and back, there is loss. Typically I use a factor of 10 to 15%. Therefore you have say 30% shrinkage and 15% loss gives you 45%.
The question is so you are 6" low with the topsoil, do you really need to import more, or by a little judicious regrading, can you utilize the material on site? The six inches is ok for grass, so I would see if you really needed the add'l topsoil
RE: Stipping Topsoil and placing Topsoil loss factor