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- How do I prevent
Special Inspection problems ... ?
- How are structures ...
shrink-swell?
- How much is
a residential geotechnical study... ?
- What is Phase I Environmental Assessment (ESA) ... ?
- What is Special Inspection ... ?
- What is Geotechnical Study and when is required ... ?
- What are high shrink-swell soils
...?... ?
What happens when some of the Special Inspection issues do not get addressed
and how do I prevent this?
Second question first:
Since the Special Inspection site visits happen at various times during the
project, we recommend an initial meeting between the Special Inspector and the
Contractor's Superintendent and appropriate Subcontractors. This meeting can be
used to provide the list of needed inspections to those who are in the best
position to notify the Special Inspector when it is the appropriate time to
perform the inspection or tests. This meeting can also be used to discuss
specifics in the project requirements
Now
the first question:
Life
gets difficult when this happens. Either the item gets inspected (even if it
means removal of what is covering it) or the Project
Structural Engineer has to state in writing that inspection of this item was not
required after all (and most Engineers would prefer not to go against Code
requirements)
We construct footings in high shrink-swell
soils by going deep enough that the footing bottom is below the "zone of significant moisture change"; note that
even with this, you can still have a little change in
moisture and this can result in some movement. Constructing slabs over high
shrink-swell soils are more difficult. Options are either remove and replace the
high shrink-swell soils to an appropriate depth with inert soils, or make sure
the soils stay at a stable moisture content (i.e. only minor fluctuations in
moisture will occur) with tight control of the construction process and proper
post construction drainage
Doing a
geotechnical (shrink-swell) study for a single residence is the most expensive,
with costs in the Central Virginia area typically varying from about $300 to
$600 for most individual houses, and a time period (from notice to proceed until a report is
issued) of about two to three weeks. When performing studies on full
subdivisions (i.e. multiple lots), while the time to do all the lots increases
somewhat, the cost per lot can be reduced to about 1/2 to 1/3 of the cost of an
investigation for a single lot
A Phase I
Environmental Site Assessment is a brief look at the environmental
history (and current conditions) of the property and the surrounding
properties. While the scope of work can vary a little, they generally include a
review of data and violations recorded by the U.S. Environmental Protection
Agency (EPA) and the Virginia Department of Environmental Quality (name may
change depending upon the state you're in), a visit to the site (with
photographs) and surrounding properties by an Environmental Professional who
looks for environmental issues which may be pertinent to this site, discussion
with property owner, neighbors, etc., review of the Chain of Title, etc. At the
end, the report gives a general assessment of environmental risk for this
property. It does not include soil and/or groundwater sampling or testing, as
this is done for a Phase II ESA (if the need for it is identified and authorized)
Special Inspection for
most commercial (not residential) structures consists of a series of
minimum tests and inspections on structural components required by the
applicable Building Code. Many of these tests and inspections are those
typically performed as part of normal construction materials testing services.
Code requires the Project Structural Engineer prepare a "Statement of Special
Inspections" to be submitted with his structural drawings for review by the
County or City. The Statement of Special Inspections is simply a list of the
minimum tests and inspections required by the Building Code and who is to
provide these. Also, whoever applies for the Building Permit needs to list the
various people involved in this process (e.g. Owner, Architect, Structural
Engineer, Geotechnical Engineer, Special Inspector, Contractor, etc.). At the
end of the project, a Final Report has to be submitted by the Special Inspector
and approved by the Project Design Professional confirming that all required testing has been satisfactorily completed before a C.O. is issued. Many Counties/Cities have developed their own Special
Inspection forms
Every county or
municipality has its own set of requirements; from a specified
number of soil borings, laboratory tests and engineering analyses and footing
design, to no study of any kind being required. Some of the counties which have
no requirements make any problems associated with geotechnical issues the
Contractor's responsibility. AGS has done work in a large number of Virginia
counties and municipalities and can help you with more specifics, or you can get
the information directly from the appropriate Building Inspection Department
High shrink-swell
soils are typically "active" clays which significantly shrink as they dry, and
swell as they absorb water. These soils are not unique to any one area, actually
many other areas of the world have soils which shrink and swell much more than
those found in Virginia. The shrink-swell characteristics of a soil are important because
structures constructed improperly over high shrink-swell soils can experience
significant distress if the soils beneath the footings become wetter or drier
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