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RE: peat- Thor

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Hi Andrew

Peat is peat, same stuff here as in New Zealand.  Below our organic level at
about 2ft it turns into extremely weak clays (MC through the roof) and not
even excavating and engineered mat seems to work.  I mentioned clay because
I was finding only moduli for weak clays.  Since then I have found peat
values from .005 N/mm^3 (18.4lb/in^3) to .015 N/mm^3 (55.3lb/in^3).  For my
exercise, which is temporary support of building while we build new
foundations, I'm using the average value to design the strip ftg for the
support cribbing.

As for the final foundation, even a raft slab is iffy so we have decided to
go screw piles but I have to investigate the buckling of those piles ...
bearing at about 100ft ...


-----Original Message-----
From: Andrew Kester [mailto:akester74(--nospam--at)] 
Sent: Thursday, December 09, 2010 5:13 AM
To: seaint(--nospam--at)
Subject: re: peat- Thor

Is peat in BC more stable? You also mentioned clay? I know we are on
opposite corners of the continent and our geology is very different,
but I deal with problematic soils every day and those are two of the
worse (expansive clay and peat/organics).

Had a job where a 20 year old house built about 25 feet off a man-made
canal had apparent settlement damage. A floor elevation survey
indicated a 5 inch slope towards a corner of the house where a boring
indicated a large depth of organic/peat soil. Standard slab-on-grade
with monolithic edge footings, "luckily" its mostly wood frame with
siding so the exterior damage is limited.

Just curious about your project since here those soils are either
over-excavated and then clean sandy fill is brought in, OR you go to

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