HomeMy WebLinkAboutSubsoil Study for Foundation 08.29.16~~ tfr.~~ Engineering, Inc. ~ CIVlUGEOTECHNlCAL
SOIL AND FOUNDATION INVESTIGATION
FORA
PROPOSED RESIDENCE
LOT 19, WESTBANK RANCH PUD #4 RESUBDIVISION
778 HUEBINGER DRIVE
GARFIELD COUNTY, COLORADO
PROJECT NO. 16-3127
AUGUST 29, 2016
PREPARED FOR:
WHIT WHITAKER
102 DEER VALLEY ROAD
NEEW CASTLE, CO 81647
P.O. Box 724, Eagle, CO 81631 Tel (970) 926-9088 www .l kpengineering . om
TABLE OF CONTENTS
EXECUTIVE SUMMARY ............................................................................................................ 2
SCOPE OF STUDY ....................................................................................................................... 2
SITE DESCRIPTION ..................................................................................................................... 2
PROPOSED CONSTRUCTION .................................................................................................... 3
FIELD INVESTIGATION ............................................................................................................. 3
SUB SURF ACE SOIL AND GROUNDWATER CONDITION ................................................... 3
FOUNDATION RECOMMENDATIONS .................................................................................... 4
SLAB CONSTRUCTION .............................................................................................................. 5
RETAINING WALLS .................................................................................................................... 5
UNDERDRAIN SYSTEM ............................................................................................................. 6
SITE GRADING AND DRAINAGE ............................................................................................. 6
LAWN IRRIGATION .................................................................................................................... 7
LIMITATION ................................................................................................................................. 8
FIGURES
LOCATION SKETCH .......................................... DRAWING NO. 1
SUB SURF ACE EXPLORATION LOGS. . . . . . . . . ................. FIGURE NO's 1-2
SWELL-CONSOLIDATION TEST RESULTS ....................... FIGURE NO's 3-5
GRAIN-SIZE DISTRIBUTION ................................... FIGURE NO. 6
PERIMETER DRAIN DETAIL. .................................. FIGURE NO. 7
LKP Engineering, Inc.
EXECUTIVE SUMMARY
The proposed residence should be supported with conventional
type spread footings, designed for an allowable soil bearing
pressure of 1000 psf. They should construct the footings on the
undisturbed brown, silty, clayey sand with angular rock fragments.
See Foundation Recommendations.
SCOPE OF STUDY
2
This report presents the results of a subsurface Soil and Foundation Investigation for a
proposed residence to be constructed on Lot 19, Westbank Ranch PUD Filing No. 4, at 778
Huebinger Drive, Garfield County, Colorado. The purpose of the subsurface soil and foundation
investigation was to determine the engineering characteristics of the foundation soil and to provide
recommendations for the foundation design, grading, and drainage. Geologic hazard studies are
outside of our scope of services.
SITE DESCRIPTION
Lot 19 is 1.61-acres parcel ofland, located on the south side of the road at 778 Huebinger
Drive, southeast from the intersection ofHuebinger Drive and Native Lane. The property is south
of Glenwood Springs in Garfield County, Colorado and is accessed from Colorado State Highway
82, to CR 154 (Old State Hwy 82) to Co Rd 109 to Huebringer to Dolores Circle and again to
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Huebringer. The proposed building site is at about same distance from the road as the two
adjoining properties. Vegetation within the proposed building site consisted of sagebrush and wild
grass. The topography within the selected building area was moderate. Drainage is to the north.
Lot 19 is vacant.
PROPOSED CONSTRUCTION
We have assumed that the proposed residence will consist of two stories, wood frame
construction, on a concrete foundation. We anticipate loads to be light, typical of residential
construction.
If the finalized plans differ significantly from the above understanding, they should notify
us to reevaluate the recommendations of this report.
FIELD INVESTIGATION
The field investigation, conducted on August 26, 2016, logging and sampling two test pits.
The excavation of the test pits had been done prior to our site visit. The approximate locations of
the test pits are shown on Drawing No. 1. We show the soil profile of the test pits on the
Subsurface Exploration Logs, Figure No's 1 and 2. Soil samples for laboratory soil analysis and
observation were taken at selected intervals.
SUBSURFACE SOIL AND GROUNDWATER CONDITION
The soil profiles encountered in the two test pits were fairly uniform, consisting about a 1.5
of topsoil over 5.5 and 4.5 feet of slopewash material, consisting of brown, silty, clayey sand with
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angular rock fragments of gravel to cobble size with occasional boulders over silty clay to clayey
silt to the maximum depths explored of 8 and 7 feet respectively. Ground water was not
encountered in either test pit.
We sampled the soil in the test pits at random intervals. The soil samples were tested in our
laboratory for swell-consolidation, natural dry density, natural moisture content, and grain-size
distribution. The test results are shown on Figure No's 3 through 6.
FOUNDATION RECOMMENDATIONS
The proposed residence should be supported with conventional type spread footings,
designed for a maximum allowable soil bearing pressure o 1000 psf. he footings should be
constructed on the undisturbed brown, silty, clayey sand with angular rock fragments, below the
topsoil and organics.
We recommend a minimum width of 16 inches for the continuous footings and 2 feet for
the isolated footing pads. Continuous foundation walls should be reinforced top and bottom to
span an unsupported length of at least 10 feet.
We recommend a minimum of 48 inches of backfill cover for frost protection of the
footing subsoils. The foundation excavation should be observed by the undersigned engineer to
verify that the soil conditions encountered during construction are as anticipated in this report.
The foundation excavation should be free from excavation spoils, frost, organics and standing
water. We recommend proof-rolling of the foundation excavation. Soft spots detected during the
proof-rolling, should be removed by overexcavation. Any overexcavation within the proposed
foundation should be backfilled, in 8 inches loose level lifts and compacted to 100% of the
maximum dry density and within 2 percent of the optimum moisture content as determined in a
laboratory from a Standard Proctor test (ASTM D-698). A structural fill, placed under footings
should be tested by a qualified professional.
LKP Engineering, Inc.
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SLAB CONSTRUCTION
The natural on-site soils, exclusive of topsoil and organics, are suitable to support lightly
loaded slab-on-grade construction. The subgrade for the slab-on-grade construction should be
proof compacted to detect and remove soft spots. They should backfill overexcavated soft spots
and other underslab fill with the on-site soil, free from topsoil and organics, or other suitable
material, compacted to a minimum of 95 percent of the maximum standard Proctor density
(ASTM D-698). Suitable material should be free from topsoil, organics and rock fragments greater
than 3 inches.
The concrete slab should be constructed over a 4-inch layer of clean gravel consisting of
-3/4 inch gravel with at least 50% retained on the No. 4 sieve and less than 3 percent passing the
No. 200 sieve.
They should reinforce the concrete slab-on-grade and score control joints according to the
American Concrete Institute requirements and per the recommendations of the designer to reduce
damage due to shrinkage. The concrete slab should be separated from the foundation walls and
columns with expansion joints to allow for independent movement without causing damage.
RETAINING WALLS
Foundation walls retaining earth and retaining structures that are laterally supported
should be designed to resist an equivalent fluid density of 60 pcf for an "at-rest" condition.
Laterally unrestrained structures, retaining the on-site earth, should be designed to resist an
equivalent fluid density of 40 pcf for the "active" case.
The above design recommendations assume drained backfill conditions and a horizontal
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backfill surface. Surcharge loading due to adjacent structures , weight of temporary stored
construction materials and equipment, inclined backfill and hydrostatic pressure due to undrained
backfill should be incorporated in the design. They should try to prevent the buildup of hydrostatic
pressure behind the retaining wall.
Passive earth pressure of 360 psf can be used for the lateral pressure against the sides of the
footings. Resistance to sliding at the bottom of the footings can be calculated based on a
coefficient of friction of 0.5. Undisturbed soil or a structural fill compacted to 100 percent of the
maximum dry density and within 2 percent of the optimum moisture content will be used to resist
lateral loads at the sides of the footings.
UNDERDRAIN SYSTEM
To reduce the risk of surface water infiltrating the foundation subsoil, we recommend
installation of a foundation perimeter drain (see Figure No. 7). The foundation perimeter drain
should consist of a 4-inch diameter, perforated pipe, sloped to a suitable gravity outlet, or to a
sump pump location, at a 1/4 inch per foot for flexible or at a 1/8 of an inch for rigid pipe. The
bottom of the trench adjacent to the footing should be lined with a polyethylene moisture barrier
glued to the foundation wall. The drain pipe should be covered with a minimum of 6 inches of
-3/4-inch free-draining granular material. Geotextile (Mirafi 140N or equivalent) should be used
to cover the free-draining gravel to prevent siltation and clogging of the drain. The backfill above
the drain should be granular material to within 2 feet of the ground surface to prevent a buildup of
hydrostatic pressure.
SITE GRADING AND DRAINAGE
The following recommendations are general. Exterior backfill should be compacted at or
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near the optimum moisture content to at least 95% of the maximum standard Proctor density under
pavement, sidewalk and patio areas and to at least 90% of the maximum standard Proctor density
under landscaped areas. They should use mechanical methods of compaction. Do not puddle the
foundation excavation.
The site surrounding the building structure should slope away from the building in all
directions. A minimum of 12 inches in the first 10 feet is recommended in unpaved areas, and
three inches in the first 10 feet in paved areas. The top of the granular foundation backfill should
be covered with a minimum of 1 foot of relatively impervious fill to reduce the potential of surface
water infiltrating the foundation subsoils.
Permanent, unretained cut and fill slopes should be graded at two horizontal to one vertical
or flatter with slope heights not exceeding 20 feet. Slopes exceeding 20 feet should have benching
incorporated. To protect the newly created slopes, erosion control methods should be used. Also,
drainage of the site above the slopes and the retaining walls should be controlled to prevent slope
instability.
Surface water naturally draining toward the proposed building site should be diverted
around and away from it by means of drainage swales or other approved methods. The roof drains
and downspouts should extend and discharge beyond the limits of the baclifill.
LAWN IRRIGATION
The clayey, silty matrix in the onsite soils is moisture sensitive, with a high potential for
hydro-consolidation. It is not recommended to introduce excess water to the foundation soils by
installing sprinkler systems next to the building. The installation of the sprinkler heads should
insure that the spray from the heads will not fall within 10 feet of foundation walls, porches or
patio slabs. Lawn irrigation must be controlled.
LKP Engineering, Inc.
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LIMITATION
This report has been prepared according to locally accepted Professional Geotechnical
Engineering standards for similar methods of testing and soil conditions at this time. The type of
soil testing was selected by the owner over a soil and foundation investigation with a drill rig.
There is no other warranty either expressed or implied.
The findings and recommendations of this report are based on field exploration, laboratory
testing of samples obtained at the specific locations shown on the Location Sketch, Drawing N o.1
and on assumptions stated in the report. Soil conditions at other locations may vary, which may
not become evident until the foundation excavation is completed. If soil or water conditions seem
different from those described in this report we should be contacted immediately to reevaluate the
recommendations of this report.
This report has been prepared for the exclusive use of Whit Whitaker, for the specific
application to the proposed residence Lot 19, Westbank Ranch PUD Filing No. 4, at 778
Huebinger Drive, Garfield County, Colorado.
Sincerely, ~... ~ .,
LKP ENGINEERING, INC.
Luiza Petrovska, PE
J:\_ WP X4-LKP\_2016\15-3127SLTSND-GRPITS.DOCX
LKP Engineering, Inc .
NOTE: THE LOCATION OF THE TEST PITS IS
APPROXIMATE. IT IS NOT BASED ON A SURVEY.
CIVIL/GEOTECHNICAL
Engineering, Inc.
P.O. Box 724, Eagle, CO 81631
tel (970) 926-9088 www.lkpengineerlng.com
LOCATION SKETCH
LOT 19, WESTBANK RANCH PUD FILING #4
778 HUEBINGER DRIVE
GLENWOOD SPRINGS
GARFIELD COUNTY, COLORADO
PROJECT NO.: 16-3127
SCALE: -1" = 80'
DRAWING NO .:
DATE OBSERVED: AUGUST 26, 2016
ELEVATION:
Test Pit I 1
DEPTH
FEET
-5
s s
y A
M M
B p
0 L
L £
. • . ..
~··
.. [J
..
; .•
D£SCRIPT10N OF MATERIAL
AND SAMPLE LOCA TlON
Topsoil
Slopewash material consisting
of brown, silty, clayey sand
with angular rock fragments
of gravel to cobble size with
an occasional boulder
:.;;, n Brown, silty clay
Bottom of Test Pit 0 8 feet
-10
-HS
-20
LEGEND:
D -2-lnch O.D. California Liner Sample
• -Bulk Sample
DD -Natural Dry Density (pcf)
MC -Natural Moisture Content (Jt)
-200 -P#N'Cent Passing No. 200 Sieve
LL -Liquid Limit
Pl -Plasticity Index
GW -Ground water
LABORATORY
TEST RESULTS
DD• 89.6 pcf
MC• 6.3 1'
IDD= O:>.J per
MC• 9.7 JC
No Ground Water
Encountered
LICP ENGINEERING, INC. SUBSURFACE EXPLORATION LOG
REMARKS
16-3127
1
DA lE OBSERVED: AUGUST 26, 2016
ELEVATION:
Test Pit I 2
s s
y A
DEPTH U U
FEET B P
0 L
L £
-ll
-, .. ,.
" -. •. .. • -~-
...; .. '
-5
·"'· , --= I!!!!!!!!!!!!!! n -
-
-10
-115
-20
LEGEND:
DESCRIPTION OF UA TERIAL
AND SAUPL£ LOCATION
Topsoil
Slopewash material consisting
of brown, silty, clayey sand
with angular rock fragments
of gravel to cobble size with
an occasional boulder
Light brown, silt, clayey, sandy
Bottom of Test Pit 0 7 feet
CJ -2-lnch O.D. Cal/fornla Liner Sample
• -Bulk Sample
DD -Natural Dry Density (pcf)
UC -Natural Moisture Content (1')
-200 -Percent Passing No. 200 Sieve
U -Liquid Limit
Pl -Plasticity Index
GW -Ground water
LABORATORY
TEST R£SUL TS
uc-1.61'
-200•9.41'
uu-aJ.J per
U~ R.'i !t
No Ground Water
Encountered
LKP ENGINEERING, INC. SUBSURFACE EXPLORATION LOG
REMARKS
16-3127
2
2
1
0
ADDmONAL SETTLEMENT UPON I ADDITION OF WA TCR UNDER
CONSTANT PRESSURE OF 1000 PSF
-1 I
-2
-3
-4
s -5 ~
&
\
\
' ~
-6
" -7
.~
~ -8
g,
~ -9
-10
\
\
\
'
I
\
' -11
-12
-13
\
\
I
-14
-15 0.1 1.0 10 100
APPUED PRESSURE -ksf
Sample of : Light brown, silty, claysy sand from: Test Pit No. 1 0 4 feet
Natural Dry Unit Weight -89.6 pcf
Natural Moisture Content -6.3 percent
MOtEr:r NO.:
LKP Engineering, Inc. Swell -Consolidation Test Results
16-3127
""1UlfE NO.: 3
2
1
0 A00/110NAL S£TT1..£ME'NT UPON
CONSTANT PRESSURE OF 1000 PSF
/ ADD/TlON OF WA TCR UNDER
-1 II
-2
-3 ""' ,
-4 \
\
i -5
fj
!
-6 \
" -7 \
1
~
~ I -s
~
0 -9
-10
-11
-12
-13
-14
-15 0.1 1.0 10 100
APPUED PRESSURE -ksf
Sample of: Light brown, sllty clay from: Test Pit No. 1 O 8 feet
Natural Dry Unit Weight -85.3 pcf
Natural Moisture Content -9.7 percent
flffOtB:T' Na.:
LKP Engineering. Inc. Swell -Consolidation Test Results 16-3127
RtUfE Na.: 4
2
1
0 ------""""
-1 ADDITIONAL S£TTZ.£MENT UPON
-2
I ADDITION OF WA 1E"R UNDER
CONSTANT PRESSURE OF 1000 PSF
I v
-.J
-4
& -5 Oi
6
!
-6
" -7
j
~ -8
Q.
~ -9
-10
\
\
\
' \
\
\
-11
-12 ~
\
-13
-14
1\
1 •
-1~ 0.1 1.0 10 100
APPLJED PRESSURE -ksf
Sample of: Light brown. snt, slightly clayey and sandy from: Test Pit No. 2 0 7 feet
Natural Dry Unit Weight -83 . .J pcf
Natural Moisture Content = 8.5 percent
flROtB:r No.:
LKP Engineering. Inc. Swell -Consolidation Test Results 16-3127
l'ltUfE No.: 5
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FROM: Test Pit No. 2 at 3.5 feet
U.S. STANDARD SIE1£ OPENING IN INOIES U.S. STANDARD SE\£' MJMBERS
100 B 4 3 2 ,.. r .. ..-,... 3 4 1 B ro '" " 20 '°"° 60 10 100 '"° 200
I II
90 \
1
80 ~
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0 500 100 50 10 5 1 0.5 0.1 0.05 0.005
Grovel
fine
Sand Cobbles Slit or aay coarse I fine medium
Grovel: 35. 6% Sand: 55% Fines 9.4%
Moisture Content: 1.5% Description: SOty. gravelly sand
0
10
20
30
40
50
60
70
80
90
100
0.001
f -& ~
~
i
IQ-
:::t--
.. : ' ...
: \l • : ;,
l> '·
LOPE AWAY FROM BUILDING
.' b [> ...
I "" : ~
l> : .• ... •. .. ·1==~~-~
OVER BACKFILL WITH A MINIMUM
OF ONE FOOT OF RELATIVELY
IMPERVIOUS SOIL
·. f ~~~~~~~~~~~~~~~~~~~~;;:;~~ •• ·.-• ·_.. l> • •
. • A •'.
~-".!': .. ; •
. . .-~:
•• •' -....J
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f::::: ~
:;;:::: . ,: c.'.:~.-~-:~-;.-GRANULAR FILL ...... ,·.~··--·.-,..-·'
: .. ti.·
It " ·"'· . . ... . ·. • · . .•. · · c:::;,ci · · · ·O" · · · · c:::;,. -~-~.· ' FOO TING -.·-.·. -·_ ·. ·.° (::).'·:-~: · · .(:) -~' -.08p -.-.·._9 .··._._.··v
IL TER FABRIC (MIRAFI
140N OR EQUIVALENT)
.'• •, '•<"':-" :'\.' ~_...~~.,;ft-;,-,'""'""'"""""'"'f! ~' . =· . :;.. . . _"0?("1
30 MIL MINIMUM THICKNESS,
PLASTIC LINER, GLUED TO T H
FOUNDATION WALL
CIVIL/GEOTECHNICAL
Engineering,
P.O. Box 724 Eagle, CO 81631
Tel.(970) 926-9088
~'\7,, 7' INUS 3/4-INCH DIAMETER, COARSE,
CLEAN CRUSH ROCK
Inc.
INC H DIAMETER PERFORATED PIPE SLOPED TO A
DAYLIGHT LOCATION AWAY FROM THE FOUNDATION
AT 1/4-INCH PER FOOT FOR FLEXIBLE AND 1/8-INCH
MINIMUM FOR RIGID PIPE OR TO A SUMP PUMP
PERIMETER DRAIN
LOT 19, WESTBANK RANCH PUD FILING #4
778 HUEBINGER DRIVE
GLENWOOD SPRINGS
GARFIELD COUNTY, COLORADO
PROJEC r NO.:
16-3125
SCALE:: N.T.S.
FIGURE NO.:
7