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RE: Soils Reports (again)

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If your local jurisdiction has adopted the IRC for houses because the
requirements are considerably less rigorous for one & two family dwellings in
the IRC. 

In Anchorage Alaska they have ground failure susceptibility areas mapped and
clarifications on site investigation requirements were added to the local
amendments of the building codes by the local geotechnical advisory
commission.  

In higher ground failure susceptibility areas a more rigorous determination
of liquefaction potential, slope stability susceptibility and mitigation can
be required.  For a commercial building permit there you always are supposed
to get a site investigation, but for occupancy category I & II structures in
low ground failure susceptibility areas they allow liquefaction potential to
be determined by historic record and for everything else they require an
empirical method to be used. 

A residential subdivision site investigation is required for residential
subdivisions in Anchorage before they can get approved by the planning and
zoning commission and the plat would list if there are questionable soils
that require additional investigations for houses.

The only time that a site specific geotechnical investigation is required for
1 & two family dwellings in Anchorage is when they are in a high ground
failure susceptibility area or the inspector sees something unusual during an
excavation. For the high ground failure area with houses they require the
same site investigation as for commercial buildings.

You can see Anchorage's requirements at www.muni.org/building

-----Original Message-----
From: Dave Adams [mailto:davea(--nospam--at)laneengineers.com] 
Sent: Tuesday, February 05, 2008 9:04 AM
To: seaint(--nospam--at)seaint.org
Subject: Soils Reports (again)

Hello everyone,

Once again, I am trying to determine alternative solutions to the blanket
requirement for soils reports required in SDC D -- not for the purpose of
avoiding the requirement for a report, but to find some reasonable compromise
for smaller or simpler projects founded on known soil conditions.  These
smaller projects include footings for site retaining walls, residential
additions, small prefabricated metal buildings, other light-framed
structures, equipment foundation pads, light poles, small signage, masonry
fences, small sunshades or canopies, swimming pools in non-expansive soil
regions, agricultural buildings, etc.  My fear is the logistics of requiring
a soils report and the timing of contract execution, production of design
documents, and overexcavation requirements, as well as the increased
liability that geotechnical companies will now absorb for such small
projects, where there was not a need for them to experience it in the past
when the engineer could use presumptive bearing values.

My thought is this:  Can the engineer-of-record prepare their own "soils
investigation" based on the use of engineering judgment with what is known
about and around the site in question?  Such information could include data
from file reports of nearby sites, USDA Soil Surveys, knowledge of the
behavior of likely soil classification due to seismic loading, etc. -- is
there a strict requirement for soil borings to be taken and classified at a
laboratory?  I am fully aware of the legalities of stretching the neck out,
but I am simply trying to determine if there are any alternatives available.

If there truly are some really serious problems with finding an alternative
to a site-specific soils report, are you requesting a soils report up front
for the little projects I've summarized above?  Again -- I am fully aware of
the legal issues that may come up, but strictly from the point of view of
rational engineering judgment, does anyone agree that there might be some
alternative means-and-methods for complying with IBC 1802.2.7 (SDC D only)?
Especially for regions where SDS calls for "SDC C", yet SD1 calls for "SDC
D".

Yikes,
Dave K. Adams, P.E., S.E.
LANE ENGINEERS, INC. 
Tulare, CA  93274

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