HomeMy WebLinkAboutPermit Field Test & Inspection Report 1996-5-15
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. OREGON
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To:
Me James Cullen
41707 McKenzie Highway
Springfield, OR 97478
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',GEOTECHNICAL S
. ~ "" ERVICES
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May 15,1996
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Re: Construction Inspection and Fill Certification: 6924 Glacier, Springfield,OR >';
The purpose of this letter is to record that on Between May 3 and May 15, 1996, Oregon
Geotechnical Services staff provided construction inspection at the above mentioned property to
test the compaction of aggregate fill, and to document conditions at the site as observed during
construction, This work was performed by David E. Reich, Certified Engineering Geologist (OR
Lic, # E1227) of Oregon Geotechnical Services, 211 Q Street, Springfield, OR 97477,
This work consisted of visual inspection of the building site and excavation area, and manual
testing and inspection of the subgrade exposed near the footing and slab areas to verify bearing
capacity and assess soil characteristics, Relative density measurements were taken to test
compaction of the aggregate fill.
Sile Condilions
The topography of the site is sloping to the northeast, and the building site consists of three
benches, approximately 3 feet apart, stepping down the slope, All surficial soils and organics
were removed from the building areas prior to placement of crushed rock, The thicknesses of
the till varies from about 4 inches on the south side of the house pad and 2-3 feet on the north
side, The fill consists of a base course of coarse open crushed rock, and the surfacing is
approximately I - I y, feet of'!. minus crushed rock. A pipe was installed in the base of the fill
to provide additional drainage relief for the fill,
The site is underlain by volcanic rocks and soils derived from these materials. The soil exposed
in the subgrade consists of brown sandy silt with abundant rock fragments and boulders. Manual
consistency tests indicate the subb'Tade is firm, The soils at the site are field classified
according to the Unified Soil Classification System (USCS) as an ML, Based on field
observations, a bearing capacity of approximately 1500 PSF can be expected for the remaining
native materials in the footing and slab areas, based on the field classification of observed
materials and manual consistency measurements taken in exposed locations around the
perimeter of the proposed structure, A small pocket of plastic soil (clay) was observed in the
southeast area of the building site, and was removed by overexcavation.
Compaction Testing:
After the top soil at the site was excavated, aggregate was placed and machine compacted in 6
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6924 Glacier Compaction Rpl 5/96
Oreg.on GI.'Otcchnical Scniccs
211 Q Street, Springfield. Oregon 97477 . Phone: (541) 726-6560 FAX: (541) 726-3895
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inch lifts, where applicable, to finished grade, The two building areas were then finished with a
vibratory roller compacter.
Observation of the building sites after placement and compaction of the aggregate fill (';."
minus) showed no signs of rutting in the footing areas from the compaction equipment and
verified that the building area is well compacted. Test indicate that the fill is placed on adequate
strength subgrade, and is suitable for (the proposed) placement of a singly family residence,
Relative density tests were perfonned after placement and compaction of the aggregate fill (>;."
minus) to detennine if the required density and strength had been achieved, and to ensure that
the aggregate was evenly compacted throughout the fill. Testing confinns that the fill is evenly
compacted, and that the density of the fill increases with depth into the fill. Tests indicate that a
relative compaction of approximately 95% (ASTM D 1557) has been achieved in the aggregate
fill. Bearing capacity design values of 1500 PSF can be safely used for the foundation design at
this site,
Recommendations
The native subgrade exposed at the site is suitable for residential construction, it has adequate
bearing capacity and should experience negligible settlement with adequate drainage. Drainage
from downspouts and surface run off should be directed away from the footings in order to avoid
differential settlement of the foundation. Minor settlement should be expected based on the
overall thickness of the fill, however, drainage control and protection of the site from stonn
runoff during construction will help reduce settlement.
Limitations:
This report was prepared for the exclusive use of Jim Cullen and his authorized agents,
Professional services were rendered in accordance with generally accepted geotechnical
services, and using the degree of care and skill ordinarily exercised under similar circumstances
by finns or individuals practicing in similar locations, Analysis, conclusions and
recommendations included in this report relate to conditions at the time the services were
perfonned, Data was accumulated from overall site reconnaissance and limited subsurface
exploration in select locations, In the event that changes in the nature, design or layout of the
project are made, the conclusions and recommendations contained in this report shall not be
considered valid unless the changes are reviewed and verified in writing,
6924 Glacier Compaction Rpl 5/96
Oregon GCQtcchnical Scn.ices
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If you have any comments or questions please give us a call at 726-6560,
Sincerely,
Oregon Geotechnical Services
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