specs

Geotechnical Investigation South River Place, Gasser Drive, Napa 29 December 2010
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an 18-inch thick layer of 6-inch minus crushed rock overlain by Mirafi 600x (or approved
equivalent) geotextile followed by engineered fill placement. The requirement for stabilization
and the method may be modified in the field by the Soil Engineer at the time of grading.
In all other areas (non-building or parking lots), the upper 3 feet (minimum) of the subgrade
should consist of engineered fill. Where over-excavation is required (north half of the site), the
area should be excavated to a depth of 2 feet, the bottom 12 inches scarified and compacted inplace
and the area replaced as engineered fill. The south half of the site will require more than 3
feet of fill to achieve the design grades and therefore does not require over-excavation.
Prior to site grading, the existing stockpile which covers a portion of the site must be removed.
After removal of the existing stockpile, the surface of the areas to be graded will require stripping to
remove vegetation and/or other deleterious materials. It is estimated that stripping depths of about 1
to 2 inches may be necessary; however, the actual depth of stripping should be determined in the
field by the Soil Engineer. Stripped material from the site may not be used as engineered fill but
may be stockpiled and used later for landscaping purposes. Any existing undesirable items which
do not meet the requirements of engineered fill (wood, concrete, buried pipes, septic tanks, etc…)
should be excavated and removed from the site.
As part of the Transitional Housing project currently under construction north of the site, Hartle
Court (new) is being extended to connect to the western end of the road. Hartle Court (old) will
then be abandoned. As part of the South River Place project, the abandoned road will be
demolished. The road improvements (including curb/gutter/sidewalk) and any utilities which will
not remain in service must be demolished and removed from the site. The exception is that the
aggregate base, asphalt concrete and portland cement concrete may be crushed and used on the site
as general fill.
After stripping and over-excavation of the existing firm/loose fills, and prior to any additional fill
placement, the upper 12 inches should be scarified, moisture conditioned as necessary and
compacted to a minimum degree of relative compaction of 90% at 2 or more percent above
optimum moisture content as determined by ASTM D1557 Laboratory Test Procedure. Mitigation
of wet/unstable soils is discussed above. After processing and compacting the upper 12 inches (or
stabilization), the site may be brought to the desired finished grades by placing engineered fill in
lifts of 8 inches in uncompacted thickness and compacting to a minimum relative compaction of
90% at 2 or more percent over optimum in accordance with the aforementioned test procedure.
All fill material should be approved by the Soil Engineer. The material should be a soil or soilrock
mixture which is free from excessive organic matter or other deleterious substances. The
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KC ENGINEERING COMPANY Project No. VV3200 Page 17 of 123