HomeMy WebLinkAboutSoils Report.pdfHEPWORTH - PAW LAK GEOTECHNICAL
October 27, 2003
D.M. Neuman Construction
Attn: Duane Neuman
P.O. Box 2317
Glenwood Springs, Colorado 81602
Hepworth-Paudak Geotechnical, Inc.
5020 County Road 154
Glenwood Springs, Colorado 81601
Phone: 970-945-7988
Fax: 970-945-8454
email hpgeo@hpgeotech.com
Job No. 103 403
Subject: Observation of Excavation, Proposed Residence, Lot 4, Springridge,
Phase I, Garfield County, Colorado.
Dear Mr. Neuman.
As requested, a representative of Hepworth-Pawlak Geotechnical, Inc. observed the
excavation at the subject site on October 21, 2003 to evaluate the soils exposed for
foundation support. The findings of our observations and recommendations for the
foundation design are presented in this report. We previously conducted a subsoil
study for design of foundations at the site and presented our findings in a report dated
July 18, 2003, Job No. 103 403.
The proposed residence will consist of a single story wood frame structure with an
attached garage. Ground floor will be structural over a crawlspace for the residence
and slab -on -grade in the garage. Spread footings sized for an allowable soil bearing
pressure of 2,000 psf were recommended in our previous report.
At the time of our visit to the site, the foundation excavation had been cut in one level
from 11/2 to 51/2 feet below the adjacent ground surface. The soils exposed in the
bottom of the excavation were variable and consisted of basalt gravel, cobbles and
boulders. in a sandy silt matrix in the southern portion of the excavation and very stiff
sandy clay in the northern portion. Results of swell -consolidation testing performed on
a sample of the clay taken from the site, shown on Fig. 1, indicate the soils have low
compressibility under existing moisture conditions and light loading and a moderate
expansion potential with a swelling pressure of about 7,000 psf. No free water was
encountered in the excavation and the soils were slightly moist to moist.
The soil conditions exposed in the excavation are consistent with those previously
encountered 011 the site and can be used for support of spread footings designed for the
recommended allowable bearing pressure of 2,000 psf. The clay soils exposed in the
excavation are expansive when wetted and there could be some long term post -
construction movement of the foundation if the bearing soils become wet. Assuming an
expansive clay depth of 2 to 4 feet below bearing level, the potential differential heave
could be on the order of 1 inch. Loose and disturbed soils should be removed in the
Parker 303-841-7119 • Colorado Springs 719-633-5562 • Silverthorne 970-468-1989
D.M. Neuman Construction
October 27, 2003
Page 2
footing areas to expose the undisturbed natural soils. Other recommendations presented
in our previous report which are applicable should also be observed.
The recommendations submitted in this letter are based on our observation of the soils
exposed within the foundation excavation and the previous subsurface exploration at the
site. Variations in the subsurface conditions below the excavation could increase the
risk of foundation movement. We should be advised of any variations encountered in
the excavation conditions for possible changes to recommendations contained in this
letter.
If there are any questions or if we may be of further assistance, please let us know.
Sincerely,
HEPWORTH - PAWLAK GEOTECHNICAL, INC.
/G�s' 0! -T
Jor/y Z.�c amson, Jr., P.E
Rev. by: SLP
JZA/ksw
attachment Figure `"°'` Consolidation Test Results
Job #103 403
G ech
Moisture Content = 12.8 percent
Dry Density = 105 pcf
Sample of: Sandy Clay
From: Bottom of Excavation at
Northeast Corner
2
g
0 1
N
c
0
0.
Expansion
upon
wetting
w 0
c
0
OI 1
cn0
1..
1..
I.
0
2
0
3
0.1 1.0 10
APPLIED PRESSURE — ksf
100
103 403HEPWORTH—PAWLAK
GEOTECHNICAL, INC.
SWELL—CONSOLIDATION TEST RESULTS
Figure 1