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RE: Frozen soil = disturbed earth?

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I would advocate that previously frozen soil is not disturbed soil in the classic definition.  If you go back in time far enough, all soil was frozen.  It occurred just after the dinosaurs. 
You just can not or should not place soil on frozen soil.  There are dilemmas out there like placing concrete foundations and then the structure is left for the winter with the intent of back filling and enclosing the structure in the spring.  The foundations were not placed on frozen soil, but the soil was frozen after they were placed.  In that case call a geotech. 

Regards, Harold Sprague


Date: Fri, 20 Mar 2009 06:25:37 -0700
From: wilsonengineers(--nospam--at)
Subject: Frozen soil = disturbed earth?
To: seaint(--nospam--at)

Is previously frozen soil considered disturbed earth?  Perhaps there isn't a definitive answer to this question, but in general terms, if there is evidence that the soil has frozen and heaved, is it thereafter unusable for placement of a footing?
The easy CYA engineering answer is to require a soils engineer, do testing, compaction, etc.  But sometimes the easy answer is not the right answer.
For example, one numbskull called me this winter with cracks in his foundation wall.  Sure enough, he placed new concrete walls and footings in December, left them exposed and then we had sub-zero temps for about two months straight.  Come February, the walls had several cracks.  No wonder.  But after the frost subsided, the cracks closed and didn't look like much of anything.  Is there an argument that the foundation is okay (notwithstanding analysis of the cracks) because it returned to its original condition?  Soils in our area are typically sandy gravel with decent bearing capacity.
Jim Wilson, PE
Stroudsburg, PA

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