HomeMy WebLinkAboutSubsoil Study for Foundation Design 01.15.18Engineering, Inc.
CIVTUCEOTECHNTCAL
SOIL AND FOUNDATION INVESTIGATION
FOR A
PROPOSED RESIDENCE
LOT 32, SUN MEADOW ESTATES
sourH MEADOW DRTVE, SrLT
GARFIELD COUNTY, COLORADO
PROJECT NO. 17.3229
JANUARY 15,2018
RËCEIVED
FEB 2 6 2ot8
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PREPARED FOR:
ABEL MONTANEZ
1179 Érwr 133 #10
CARBONDALE, CO 81623
P.O. Box 724,Eagle, CO 81631 Tel. (970) 390-0307 www.lkpengineering.com
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TABLE OF CONTENTS
EXECUTIVE SUMMARY .......
SCOPE OF STUDY
SITE DESCRIPTION
PROPOSED CONSTRUCTION......
FIELD INVESTIGATION
SUBSURFACE SOIL AND GROUNDWATER CONDITION
FOUNDATION RECOMMENDATIONS
SLAB CONSTRUCTION
RETAINING WALLS.
LINDERDRAIN SYSTEM
SITE GRADING AND DRAINAGE..
LAWN IRRIGATION
LIMITATION
FIGURES
LOCATION SKETCH
SUBSURFACE EXPLORATION LOGS
SWELL-CONSOLIDATION . .
PERIMETER DRAIN DETAIL.
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.DRAV/ING NO. 1
FIGURE NO's l-2
FIGURD NO's 3-4
.FIGURE NO. 5
LKP Engineering,Inc.
EXECUTIVE SUMMARY
The proposed residence should be supported with
conventionaltype spread footings, designed for an allowable soil
bearing pressure of 1000 psf. They should construct the footings
on the undisturbed silty-sandy clay and/or sandy silt. See
tr'oundation Recommendations.
SCOPE OF STUDY
This report presents the results of a subsurface Soil and Foundation Investigation for a
proposed residence to be constructed on Lot32, Sun Meadow Estates, on South Meadow Drive
Garfield County, Silt, 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 ore
outside ofour scope ofservices.
SITE DESCRIPTION
Lot32, Sun Meadow Estates is2.002 acres (according to the Garf,reld County Assessor's
website) and it is located on South Meadow Drive south from the intersection with Antonelli
Lane, in Silt, Garfield County, Colorado. Site plan or a survey were not available. There was a
culvert crossing South Meadow Drive and discharging into a shallow ditch running in a westerly
direction over the lot. We understand that the proposed building site was planned to be partially
on the lower part (north from the ditch) and partially on the upper part (south from the above-
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described ditch). Vegetation within the proposed building site consisted of grass, bare ground
and some snow. There was another deeper ditch running along the west property line. The ditch
from the culvert (described above) turned to the southwest and connected with the west ditch.
The topography within the selected building arca rppeared moderate with two terraces. Drainage
is to the west and southwest.
PROPOSED CONSTRUCTION
We understand that the proposed residence will be ranch type, wood frame construction
with a basement, on a concrete foundation, with an attached garage. 'We anticipate loads to be
light, typical of residential construction.
If the finalized plans differ significantly from the above understanding, they should
notif,i us to reevaluate the recommendations of this report.
FIELD INVESTIGATION
The field investigation, conducted on January 9,2018, consisted of logging and sampling
two test pits. 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 7 and2. Soil samples
for laboratory soil analysis and observation were taken at selected intervals. We understand that
you dug the test pits with a mini excavator on rubber tracks prior to our site visit.
SUBSURFACE SOIL AND GROUNDWATER CONDITION
The soil profiles encountered in the two test pits were fairly uniform. Test Pit No. I had
very little topsoil over blocþ clay to about 2.5 feet over light brown, silty sand to sandy silt to
the maximum depth explored of 8 feet. Test Pit No. 2 also had very little topsoil over blocþ
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clay to about 2.5 over light brown, silty sand to sandy silt to about 6 feet over reddish-brown,
calcareous, silty clay to the maximum depth explored of 8 feet. Ground water or bedrock was not
encountered in the test pits. We sampled the soil in the test pits at random intervals.
FOUNDATION RECOMMENDATIONS
We recommend that the building site be adjusted to move away from the ditches. The
storm runoff from the culvert can saturate the foundation soils and cause settlement in the future.
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 silty-sandy clay and/or sandy silt, below the topsoil and blocþ clay.
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 ofat least 10 feet.
The proposed foundation should be set at a minimum depth of four feet below the
finished grade or at the minimum depth required by the local building code. Thefoundation
excavation should be observed by the undersigned engineer to verifi that the soil conditions
encountered during construction ore 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 100o/o of the maximum dry density and
within 2percent of the optimum moisture content as determined in a laboratory from a Standard
Proctor test (ASTM D-69S). A structural fill, placed under footings should be tested by a
qualified profes sional.
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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 frll 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
-314 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 controljoints 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 thc on-sitc carth, should be designed to resist an
equivaleut fluid density uf 40 puf fur Lhe "aotive" case.
The above design recommendations assume drained backfill conditions and a horizontal
backfill surface. Surcharge loading due to adjacent structures, weight of temporary stored
construction materials and equipment, inclined backfill and hydrostatic pressure due to
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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 of360 psfcan be used for the lateralpressure 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. 5). The foundation perimeter drain
should consist of a 4-inch diameter, perforated pipe, sloped to a suitable gravity outlet, at a 714
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 polyetþlene moisture barrier glued to the foundation wall.
The drain pipe should be covered with a minimum of 6 inches of -314-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
near the optimum moisture content to at least 95%o of the maximum standard Proctor density
under pavement, sidewalk and patio areas and to at least 90Yo of the maximum standard Proctor
density under landscaped areas. They should use mechanical methods of compaction. Do not
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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.
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 backfill.
LAWN IRRIGATION
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 l0 feet of foundation walls, porches or patio slabs.
Lawn irrigation must be controlled.
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 and general contractor as the preferred method for the soil
and foundation investigation over a soil and foundation investigation with a drill rig. There is no
otlrcr wat'runty either expressed or inrylied.
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 No.1 and on assumptions stated in the report. Soil conditions at other locations may
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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. We are not responsible for
technical interpretation by others ofthe data presented in this report.
This report has been prepared for the exclusive use of Abel Montanez, for the specific
application to the proposed residence on Lot 32, Sun Meadow Estates, South Meadow Drive,
Silt, Garfield County, Colorado.
Sincerely,
LKP ENGINEERING,INC.
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Lu;iza Petrovska, PE
J:\_WP X4-LKPVO I 8\1 8-3229SILT-CLAY-SAND-PITS.DOCX
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NOTE: THE LOCATION OF THE TEST PITS lS
APPROXIMATE. IT IS NOT BASED ON A SURVEY
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Tel (970) 390-0307 www.lkpengineering.com
LKP
LOCATION SKETCH
LOT 32, SUN MEADOW ESTATES
SOUTH MEADOW DRIVE
GARFIELD COUNTY, COLORADO
PROJÈU I NU.:18-3229
SCALÉ:- 1" = 100'
DRAWING NO.:
1
DATE OBSERVED: JANUARY 9, 2018
ELEVATION:
TEST PIT-I
DEPTH
FEET
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DESCRPNON OF MATERIAL
AND SAMPLE LOCATION
LABORATORY
TEST RESULTS
REMARKS
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-15
20
Blocky-silty cloy DD: 1O2.4 ncf
tr
Light brown, to reddish-brown,
sandy Silt to silty Sond
MC: 5.3 %
DD: 95.6 pcf
MC: 3.5 %
Bottom of Test Pit at I feet No Ground woter
encountered
LEGEND:
trI
DD
MC
- 2-inch O.D. Colifornia Liner Somple
- Bulk Sample
- Noturol Dry Density (pcf)
- Notural Moisture Content (7")
- Percent Passing No. 2O0 Sieve
- Liquid Limit
- Plosticity lndex
- Ground woter
-200
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tKP ENGINEERING, INC.SUBSURFACE EXPLORATION LOG
PRO,ECT NO.:18-3229
IñAURE NO,:
DATE OBSERVED: JANUARY 9, 2018
ELEVATION:
TEST PIT_z
DEPTH
FEET
s
Y
M
B
o
L
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A
M
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DESCRIPTION OF MATERIAL
AND SAMPLE LOCANON
LABORATORY
TEST RESULTS
REMARKS
5
-10
-15
20
Blocky-silty cloy
tr
Light brown, to reddish-brown,
sandy Silt to silty Sond DD: 94.5
MC: 4.9
PCf
tr
Light to reddish-brown, silty
Clay, colcareous DD: 101.3 pcf
MC: 7.2 %
Bottom of Test Pit at I feet No Ground woter
encountered
LEGEND:
trI
DD
MC
- 2-inch O.D. California Liner Sample
-200
- Bulk Somple
- Noturol Dry Density (pcf)
- Noturol Moisture Content
- Percent Possing No. 200
- Liquid Limit
- PlastÍcity lndex
- Ground woter
(7")
Sìeve
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tKP ENGINEERTNG, INC.SUBSURFACE EXPTORATION tOG
FKUÈÇ I NU.:t8-3229
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APPLIED PRESSURE - kef
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Somple ofrLíght brown, sandy Sìlt, claycyFrom:Test Pìt No. I of 2.5 feet
Noturol Dry Unìt Weíght
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APPUED PRESSURE - ksf
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Sample of:Lt. brown, sondy Silt
Noturol Dry Unìt lleíght
Natural Moisture Content =
From: Teet Pit No. 1 ot I feet
Pcfpercent
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APPUED PRESSURE - ksf
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Sampla otLÍght brovn, sÍlty sond, fÍno
Noturol Dry Unlt Weight = 94.5
Notural Moìeture Content - 4.9
From: Tcst Plt No, 2 ot 4 fcdt
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APPUED PRESSURE - ksf
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Sample ofrLt. brown, colcoreous
Noturol Dry Unlt Weight
Noturol Molsture Content =
Clay, sandy F¡om: Test Plt Nd 2 at 6 feet,0'1.3 pcf7.2 Percent
LKP EngÍnccrîng, lne Swell - Consolídation Test Results
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AWAY FROM BUILDING
BACKFILL WITH A MINIMUM
OF ONE FOOT OF RELATIVELY
IMPERVIOUS SOIL
FABRTC (MtRAF|
140N OR EOUTVALENT)
NUS 3/4-INCH DIAMETER, COARSE
CLEAN CRUSH ROCK
30 MIL MINIMUM THICKNESS,DIAMETER PERFORATED PIPE SLOPED TO
PLASTIC LINER, GLUED TO A DAYLIGHT LOCATION AWAY FROM ÏHE
FOUNDATION AT 1/4-INCH PER FOOT FOR
FLEXIBLE AND 1/8-INCH MINIMUM FOR RIGID PIPE
FOUNDATION WALL
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Engineering, Inc.
P.O. Box 724, Eosle, CO 81631
Tel (970) 390-0J07 www.lkpengineering.com
LKP
PERIMETER DRAIN
LOT 32, SUN MEADOW ESTATES
SOUTH MEADOW DRIVE
GARFIELD COUNTY, COLORADO
PHo.tLCt NU.: ß4229
scALE: N.T.s.
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flGURE NO;