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RE: code soil values vs. site specific values

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Hi Stan,
I suppose if I were in Texas, I would be doing exactly as you are. However,
here in the land of the UBC we have two choices - design by a geotechnical
report OR design to the worst condition of the Uniform Building Code
(whichever is required by the building official). In residential
construction (in the desert where I live), rarely are geotechnical reports
required unless the site is known to have problems. Even when I lived in Los
Angeles the City of Los Angeles only required that we design by the worst
case expansive soils (a revised section of the UBC provisions that are more
restrictive to Los Angeles City jurisdiction).
I know other areas - such as Southern Utah, that have some real expansive
clay problems and are just starting to mandate soils reports.

Let me preface that the homes I design without geotechical reports are on
flat sites and generally one story slab on grade (no hillside lots or
difficult soil conditions). Being a desert area, the soil condition is
fairly well known and consistent (decomposed granite or compacted sand) -
far more so than in Los Angeles or other areas of California where expansive
clays exist. I also have to deal with having my hands tied. I can not afford
to absorb the cost of the soils reports and have it in my contract that the
owners representative will provide it. In most cases they do not live up to
this part of the contract and I have had to add a disclaimer to my contract
that explains that the worst case conditions will be used in the design
unless a report is obtained to show the conditions are less stringent.

I am not so flippant about this as I may have made it seem but it is not
enforced as stringently as it is in your area.


-----Original Message-----
From: Caldwell, Stan [mailto:scaldwell(--nospam--at)]
Sent: Thursday, April 13, 2000 3:02 PM
To: 'seaint(--nospam--at)'
Subject: RE: code soil values vs. site specific values

It is a good thing that you are practicing in liberal State of California,
and not in the great conservative State of Texas!  The Texas PE Board
clearly views foundation design without a site-specific geotechnical
investigation and report as failing to meet "generally accepted engineering
standards or procedures".  In their January, 1992 Official Newsletter, they
specifically state that they will judge such practice as gross negligence,
incompetence, or misconduct under Board Rule 131.151.  Consequently, at my
firm, we won't design anything (not even a dog house) without a
site-specific geotechnical report with foundation design criteria.  To the
best of my knowledge, this is also the policy of all of the other
"enlightened" firms in Texas.
Stan R. Caldwell, P.E.
Rooting for the Stars in Dallas !!
URL of the Week:
Dennis wish wrote:
In most cases, I have been relying upon the local building departments to
advise what the conditions and near source values are in their community. If
there are more than one type of soil to consider, I go with the most
I have tried with little success to obtain soil studies - mostly the
architects or designers are in too much of a hurry to wait for job specific
information and the building departments have not been enforcing soils
There is one soils company,  locally, who will provide soil profiles and
near source data given a site address. They work from historical records and
will email the information for a fee of $100.00. However, for the homes that
I have done since the code was adopted, I have been able to obtain most of
the values from the building department who have maintained some records
from submittals in the same vicinity (mostly gated and private communities).
I don't have serious expansive clays to deal with in my area as is common
throughout most of Southern California, so the concerns that clays bring are
not as difficult to contend with.