01576�MY''�Y klai �ir
Olson Walker A!` ci ates Architects
April 11, 1980
page 2
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Nateria1 Approx. Average Depths Approx. Range
Description below Existing Grade of thickness'
(ft) .(ft)
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top soil 0 - 0.5 0.5;
organic, loose, sand 0.5 - 2.0 1.5.
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*medium dense sand 2 - 7 5
*dense till with wet sand seams 7 - depths of not estab1ished
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penetration.
* bearing strata to support footings
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The following, which may influence design and construction was also''
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obtained during field investigation at the -subject site..
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a) The topsoil was'very soft. A back,hoe could easily move around
on the site at the time of field exploration. No peat bog is
encountered at the site.
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b) Perched groundwater was noted at sand and till layer. Some
test pits were caved in during the pit excavation. Groundwater
was observed at the contact zones between sand and till layer.
c) Construction in the summer period will be desirable to reduce'
adverse groundwater effects..
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5.. DIRECT SHEAR TESTS
Direct shear tests were conducted on representative samples of the
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undisturbed soils retrieved by Shelby tubes. The peak and residual
shear strength of the samples were obtained by the following methods.
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Each sample was sheared in a shear box to obtain peak shear stress
values. After peak shear stress is obtained, the shear box returned
to its original position, and a second shear test was conducted for
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the same sample. The maximum stress value obtained from the second
test is referred to as the residual strength of the soil.
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