HomeMy WebLinkAboutSoils Report 08.01.2017Engineering, Inc.
CIVIUGEOTECHNICAL
SOIL AND FOUNDATION INVESTIGATION
FOR THE
RICE RESIDENCE
LOT 4, THE RANCH AT COULTER CREEK PUD
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
PROJECT NO. 17-3155
REVISED AUGSUT 1, 2017
MARCH 15, 2017
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PREPARED FOR:
TOM RICE
180 ALLMOND LANE
ALPHARETTA, GA 30004
P.O. Box 724, Eagle, CO 81631 Tel (970) 390-0307
1
TABLE OF CONTENTS
EXECUTIVE SUMMARY 2
SCOPE OF STUDY 2
SITE DESCRIPTION 2
PROPOSED CONSTRUCTION . 3
FIELD INVESTIGATION 3
SUBSURFACE SOIL AND GROUNDWATER CONDITION 3
FOUNDATION RECOMMENDATIONS 4
SLAB CONSTRUCTION 5
RETAINING WALLS 6
UNDERDRAIN SYSTEM 6
SITE GRADING AND DRAINAGE 7
LAWN IRRIGATION 7
LIMITATION 8
FIGURES
LOCATION SKETCH . DRAWING NO. 1
SUBSURFACE EXPLORATION LOGS .FIGURE NO's 1 - 2
SWELL/CONSOLIDATION TEST RESULTS .. FIGURE NO'S 3 -4
GRAIN SIZE DISTRIBUTION FIGURE NO. 5
PERIMETER DRAIN FIGURE NO. 6
LKP Engineering, Inc.
2
EXECUTIVE SUMMARY
The proposed residence should be supported with
conventional type spread footings, designed for a
maximum allowable soil bearing pressure of 3000
psf and a minimum dead load of 1000 psf. They
should construct the footings on the undisturbed
sandy, clayey to clayey -gravelly soils. See
Foundation Recommendations.
SCOPE OF STUDY
This report presents the results of a subsurface Soil and Foundation Investigation for the
proposed Rice Residence to be constructed on Lot 4, The Ranch at Coulter Creek PUD, Cattle
Creek Ridge Road, 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 4 is a 4.407 -acre lot, on the north side of Cattle Creek Ridge Road, south from the
intersection with Red Canyon Road in the Ranch at Coulter Creek PUD Subdivision, Garfield
County, Colorado. The topography of the lot within the building envelope is moderate. Drainage is
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proposed residence will be two -stories, wood frame constriction with over a crawl space.
3
to the east and southeast. Vegetation on the lot consisted of a grassy meadow. Lot 4 is surrounded
to the north, east and south by the Tract E, The Ranch at Coulter Creek Open Space. On the west
side of the lot is Cattle Creek Ridge Road. Lot 4 was vacant.
PROPOSED CONSTRUCTION
At the time of the soils and foundation investigation, there was no information available
about the proposed residence. The original report is revised to reflect the additional information
about the proposed residence. Based on our telephone conversation and the emailed plans, the
The test
pits had been already excavated by Whit Whitaker, prior to our site visit. Loads are anticipated to
be light, typical of residential construction.
If the finalized plans differ significantly from the above understanding, we should be
notified to reevaluate the recommendations of this report.
FIELD INVESTIGATION
The field investigation, conducted on March 10, 2017, consisted of logging and sampling
two test pits. Excavation of the test pits was done by you prior to our site visit. The test pits'
locations 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. Test Pit No. 1 had
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about 2 feet of topsoil over two feet of reddish to light brown with white streaks, sandy clay to
clayey sand over 1.5 feet of whitish -brown, sandy silt to silty -clayey sand over 2.5 feet of reddish
to light brown, silty to clayey, sandy gravel to the maximum depth explored of 8 feet. Test Pit No.
2 had about 2.5 feet of topsoil over about 2.5 feet of yellowish to whitish -brown, silty to sandy clay
with thin layers of gravel over 3 feet of light brown, silty to sandy clay. The soils in both test pits
had high moisture content ranging from 20 to 24 percent in the clayey soils and about 10 percent in
the gravelly soil at the bottom of test pit number 1. Ground water was not encountered in either test
pit. We sampled the soil in the test pit at random intervals. The soil samples were brought to our
laboratory for observation and analysis. They were tested for natural dry density, natural moisture
content, swell/consolidation, and sieve analysis, as shown on the Swell/Consolidation Test
Results, Figure No.'s 3 and 4, and the Grain -Size Distribution, Figure No. 5.
FOUNDATION RECOMMENDATIONS
The on-site clayey soils showed low potential for expansion. Since the soils had high
moisture content due to exposure to the weather conditions (the test pits were dug the previous
day), it is possible that the potential for expansion will increase after the subgrade has dried up and
moisture content is allowed to increase again. The proposed residence should be supported with
conventional type spread footings or pads and grade beams, designed for a maximum allowable
soil bearing pressure of 3000 psf and a minimum dead load of 1000 psf.
They should construct the
footings on the undisturbed sandy, clayey to clayey -gravelly soils. It is possible that the foundation
of the proposed basement will be below the soils observed in the two test pits, in which case
additional testing might be required.
The undersigned engineer must observe the foundation excavation to verify that the soil
conditions are as anticipated from the two test pits. For a deep foundation system alternatives, like
straight shaft piers or micro piles, an additional soils and foundation with a drill rig will be
necessary.
Continuous foundation walls should be well reinforced, top and bottom, to span an
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unsupported length of at least 10 feet. A minimum backfill cover as required by the local building
department should be provided for frost protection of the footing subsoils.
The foundation excavation should be free from excavation spoils, frost, organics and
standing water. Any overexcavation within the proposed foundation should be backfilled, in 8
inches loose, level lifts and compacted to 98% 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). Structural fill, placed under footings, should be tested by a qualified professional.
Another alternative will be to support the proposed foundation with helical piers.
For any additional foundation alternatives, please contact our office.
SLAB CONSTRUCTION
With lightly loaded concrete slabs, the swelling soils might cause structural damage. In
areas, such as a garage, where the possible movement of the slab can be tolerated and is acceptable
by the homeowner, concrete slab on grade can be constructed.
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. The concrete slab -on -grade should be reinforced and control joints scored
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.
As a preferred alternativ
e, to reduce the risk of heaving of the slab -on -grade, a minimum of
three feet of the underlaying swelling soils can be replaced with a non -swelling, structural fill.
The
fill should be placed in thin lifts and compacted to 95 percent of the maximum Standard Proctor
(ASTM D698) dry density and within 2 percent of the optimum moisture content as tested.
In areas, other than the garage a structural floor over crawl space is recommended. The
crawl space must be vented according to the local building code requirements.
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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.
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 0.45. Undisturbed soil or a structural, non -swelling fill compacted to 100
percent of the maximum dry density and within 2 percent of the optimum moisture content shall be
used to resist lateral loads at the sides of the footings.
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 undrained
backfill should be incorporated in the design. Every attempt should be made to prevent the buildup
of hydrostatic pressure behind the retaining wall.
UNDERDRAIN SYSTEM
To reduce the risk of surface water infiltrating the foundation subsoil, installation of a
foundation perimeter drain is recommended (see Figure No. 6). 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. The drain should slope at 1/4 inch per foot if flexible or at 1/8 of an inch if rigid
pipe is used. 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 placed over the moisture
barrier and 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
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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. The top one foot of
the backfill material should consist of a relatively impervious fill. The backfill should be sloping
away from the building.
SITE GRADING AND DRAINAGE
The following recommendations are general in nature. 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 one foot of relatively
impervious fill to reduce the potential of surface water infiltrating the foundation subsoils. Exterior
backfill should be compacted at or 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. Mechanical methods of
compaction should be used. Do not puddle the foundation excavation.
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 adjacent 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 backhoe
was selected by Mr. Whitaker, the general contractor, as the preferred method for the soil and
foundation investigation over a soil and foundation investigation with a drill rig. 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 Figure No. 1 and on assumptions
stated in the report. Soil conditions at other locations and depths 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. We are not responsible for technical interpretation by others of the
data presented in this report. There is no other warranty either expressed or implied.
This report has been prepared for the exclusive use of Tom Rice, for the specific
application of the Rice Residence to be constructed in the area tested on Lot 4, The Ranch at
Coulter Creek PUD, Cattle Creek Ridge Road, Garfield County, Colorado.
Sincerely,
LKP ENGINEERING, INC.
Luiza Petrovska, PE
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NOTE: THE LOCATION OF THE TEST PITS IS
APPROXIMATE. IT IS NOT BASED ON A SURVEY.
CIVIL/GEOTECHNICAL
Engineering, Inc.
P.O. Box 724, Engle, CO81£31
tel (970) 390-0307 www.lkpengirKenng.com
LOCATION SKETCH
LOT 4, THE RANCH AT COULTER CREEK PUD
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
PROJECT NO.:
17-3155
SCALE:
-1"=100'
DRAWING NO.:
1
DATE OBSERVED: MARCH 10, 2017 Test Pit # 1
ELEVATION:
DEPTH
FEET
S
Y
M
8
O
L
S
A
M
P
L
E
DESCRIPTION OF MATERIAL
AND SAMPLE LOCA710N
LABORATORY
7EST RESUL7S
REMARKS
—
—
Topsoil
,
�
p
Reddish -brown, to light
brown, with white streaks,
sandy clay to clayey sand
DD= 91.6 pcf
MC= 24.2 X
3
Whitish -brown, sandy silt to
silty -clayey sand
DD= 723 pcf
MC= 20.3 X
—
—
!.;.
!•• .
•
Reddish to light brown, clayey
sandy gravel
MC=10.3%
-200=38X
—
10
Bottom of Test Pit ® 8 feet
No Ground Water
Encountered
15
20
LEGEND:
O — 2 -inch O.D. California Liner Sample
• - Bulk Sample
DD - Natural Dry Density (pcf)
MC - Natural Moisture Content (X)
-200 - Percent Passing No. 200 Sieve
LL - Liquid Limit
PI - Plasticity Index
GW - Ground water
LKP ENGINEERING, INC.
SUBSURFACE EXPLORATION LOG
PROJECT Na:
17-3155
i Raw Nn:
1
DATE OBSERVED: MARCH 10, 2017 Test Pit O 2
ELEVATION:
DEPTH
FEET
S
Y
M
8
O
L
S
A
M
P
L
E
DESCRIPTION OF MATERIAL
AND SAMPLE LOCATION
1 LABORATORY
TEST RESULTS
REMARKS
5
Topsoil
�!
,
o
Yellowish to whitish brown,
silty to sandy clay with thin
layers of gravel
DD== 21. i f
—
10
/�
Light brown, silty to sandy
clay
DD= 102.7 pcf
MC= 21.9 X
Bottom of Test Pit 0 8 feet
No Ground Water
Encountered
15
— 20
LEGEND:
0 - 2—inch O.D. Califomia Liner Sample
• — Bulk Sample
DD — Natural Dry Density (pcf)
MC — Natural Moisture Content (X)
—200 — Percent Passing No. 200 Sieve
LL — Liquid Limit
PI — Plasticity Index
GW — Ground water
LKP ENGINEERING, INC.
SUBSURFACE EXPLORATION LOG
PROACT Na:
17-3155
RawNa 2
.g
C
O
W
2
1
0
- 2
k
W
k
- 5
2
1
0
- 2
- 3
- 4
- 5
LICP Engineering, Inc.
Swell — Consolidation Test Results
rear 1110.:
77-3155
'FIGURE na:3
y
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\
.
0.1 1 0 10 100
APPLIED PRESSURE - ksf
Sample: Clayey sand to sandy clay From: Test Pit 1 at 3.8 feet
Natural Dry Unit Weight = 91.6 pcf
Natural Moisture Content = 24.2 percent
LICP Engineering, Inc.
Swell — Consolidation Test Results
rear 1110.:
77-3155
'FIGURE na:3
0.1 1 0 10 100
APPLIED PRESSURE - ksf
Sample ofWhitish, Sandy Silt From: Test Pit 1 at 5 feet
Naturol Dry Unit Weight = 72.3 pcf
Natural Moisture Content = 20.3 percent
LICP Engineering, Inc.
Swell — Consolidation Test Results
rear 1110.:
77-3155
'FIGURE na:3
3u, '6upeeu1 u3 d)l7
Swell — Consolidation Test Results
Compression R Expansion
W
N
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Sample of: Lt. Brown, sandy, Silt and Clay. From: Test Pit 2 at 8 feet
Natural Dry Unit Weight = 102.7 pcf
Natural Moisture Content = 21.9 percent
0.7X SWELL AT 2.7 KSF
O
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O
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74
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U
Compression R Expansion
#
0.1 1.0 10 100
APPLIED PRESSURE — ksf
Sample of: Yellowsh—whitish, sandy cloy From: Test Pit 2 at 4 feet
Natural Dry Unit Weight = 98.7 pcf
Natural Moisture Content = 21.7 percent
1
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90
80
70
2
0 60
50
0
ter 40
9
30
20
10
0 500
U.S. STANDARD SIEVE OPENING IN INCHES
U.S STANDARD SIEVE NUMBERS
FROM: Test Pit No. 1 at 8 feet
B 4 3 2 1a 1 iN ref it 3 4 6 810 1416 20 3040 50 70 100 140 200
HYDROMETER
r
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•
100 50
10
5
1
0.5
01
0 05
0.005
0
10
20
30
40
50
60
70
80
90
100
0.001
Cobbles
Gravel
Sand
Silt or Clay
coarse
fine
coarse
medium
fine
Moisture Content: 10.3X
Gravel: 32X
Sand: 30X
Description: brown, silty to clayey, sandy Gravel
Fines 38X
Wpm Al Jesj000 auealed
LOPE AWAY FROM BUILDING
OVER BACKFILL WITH A MINIMUM
OF ONE FOOT OF RELATIVELY
IMPERVIOUS SOIL
VQo
0 0 \/
a
•��❑ !NUS 3/4 -INCH DIAMETER, COARSE,
CLEAN CRUSH ROCK
FILTER FABRIC (MIRAFI
140N OR EQUIVALENT)
30 MIL MINIMUM THICKNESS,
PLASTIC LINER, GLUED TO TH
FOUNDATION WALL
CIVIL/GEOTECHNICAL
Engineering, Inc.
P.O. Box 724 Eagle, CO 81631
Tel.(970) 390-0307
-INCH 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 4, THE RANCH AT COULTER CREEK PUD
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
PRO✓EC7 NO.:
17-3155
SCALE:
N.T.S.
FIGURE NO.:
6