HomeMy WebLinkAboutSoils Report 06.02.2016LKP
Engineering, Inc.
CIVIIJGEOTECHNICAL
SOIL AND FOUNDATION INVESTIGATION
FOR THE
WHITAKER RESIDENCE
LOT 3, THE RANCH AT COULTER CREEK PUD
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
PROJECT NO. 16-3105
JUNE 2, 2016
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29520
PREPARED FOR:
WHIT WHITAKER
WRW LOGWORKS, LLC
102 DEER VALLEY DRIVE
NEW CASTLE, CO 81647
P.O. Box 724, Eagle, CO 81631 Tel (970) 926-9088
TABLE OF CONTENTS
EXECUTIVE SUMMARY 2
SCOPE OF STUDY 2
SITE DESCRIPTION +++++++ Pi + ++++ •• ++ ... • • ... . I. 2
PROPOSED CONSTRUCTION k+ ++++++ S.+4 +++++ •+. • .".4 " ..... ... . ... . ... 3
FIELD INVESTIGATION 3
SUBSURFACE SOIL AND GROUNDWATER CONDITiON
FOUNDATION RECOMMENDATIONS— . 4P? .4
SLAB CONSTRUCTION + + . e+ +5
UNDERDRAIN SYSTEM +++ ++
SITE GRADING AND DRAINAGE ........... . . _ .. .. .....
LAWN IRRIGATION 7
LIMITATION 8
FIGURES
LOCATION SKETCH DRAWING NO.
SUBSURFACE EXPLORATION LOGS FIGURE NCYs L 2
SWELL/CONSOLIDATION TEST RESULTS FIGURE NO'S 3-4
PERIMETER DRAIN FIGURE NO, 5
LKP Engineering, Inc.
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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
clay to sandy, gravelly clay. See Foundation
Recommendations.
SCOPE OF STUDY
This report presents the results of a subsurface Soil and Foundation Investigation for the
proposed Whitaker Residence to be constructed on Lot 3, 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 3 is a 5.388 -acre lot, on the north side of cattle Creek Ridge Road, opposite Meadow
Circle in the Ranch at Coulter Creek PUD Subdivision, Garfield County, Colorado. The
LKP Engineering, Inc.
topography of the lot is moderate. Drainage is to the east and southeast. Vegetation on the lot
consisted of a grassy meadow. On Lot 2 to the south was an existing residence. Lot 3 was vacant.
To the north and east is Tract E, The Ranch at Coulter Creek Open Space.
PROPOSED CONSTRUCTION
We understand that the proposed residence will consist of a one-story wood frame
construction, on a concrete foundation with a possible walkout basement. Loads are anticipated to
be Tight, 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 May 29, 2016, consisted of consisted of excavating,
logging and sampling two test pits. Excavation of the test pits was done by you prior to our site
visit. The test pits' locations arc 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 uniform. Test Pit No. 1 had about 3
feet of topsoil over two feet of reddish -brown, blocky to sandy clay with some gravel over a thin
layer of rocks in a clayey matrix over two feet of light brown, hard clay. Test Pit No. 2 had about
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two feet of topsoil over about 1.5 feet of reddish -brown, blocky to sandy clay with some gravel
over 4.5 feet of light brown, hard clay. Ground water was not encountered in either test pit. We
sampled the soil in the test borings 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 and swell consolidation, as shown on the Swell/Consolidation Test Results, Figure No.'s 3
and 4.
FOUNDATION RECOMMENDATIONS
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. It is possible that the foundation of the proposed basement will be below the soils
observed in the two test pits
The undersigned engineer must observe the foundation excavation to verifi that the soil
conditions are as anticipated /turn 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
necessat7'.
Continuous foundation walls should be well reinforced, top and bottom, to span an
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.
LKP Engineering, Inc.
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SLAB CONSTRUCTION
The on-site clayey soils, showed moderate to potential for expansion. 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
-34 inch gravel with at least 50°o 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 alternative, 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.
RETAINING WALLS
Foundation walls retaining earth and retaining structures that are laterally supported should
be designed to resist an equivalent fluid density of 70 pcf for an "at -rest" condition. Laterally
unrestrained structures retaining the on-site earth should be designed to resist an equivalent fluid
density of 50 pcf for the "active" case.
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Passive earth pressure of 240 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 0.35. 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.
If an imported, relatively free draining material is used for backfill, 60 pcf can be uscd for
an "at rest" condition and 40 pcf can be used for the "active" case. Please verify the choice of
backfill material with the undersigned engineer.
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. 5). 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
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
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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 alI 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°0
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 as the preferred method for the soil and foundation investigation
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 Figure No. 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. We are not responsible for technical
interpretation by others of the data presented in this report.
This report has been prepared for the exclusive use of Whit Whitaker, for the specific
application of the Whitaker Residence to be constructed on Lot 3, The Ranch at Coulter Creek
PUD, Cattle Creek Ridge Road, Garfield County, Colorado.
Sincerely,
LKP ENGINEERING, INC.
Luiza Petrovska, PE
1: WP
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LKP Engineering, Inc.
NOTE: THE LOCATION OF THE TEST PITS 1S
APPROXIMATE. IT IS NOT BASED ON A SURVEY
CIVIL/GEOTECHNICAL
Engineering, Inc.
P.D. Box 724, Eagle, CO 81631
tel (970} 926-9088 www.lkpenglneering.cam
LOCATION SKETCH
LOT 3, THE RANCH AT COULTER CREEK PUD
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
PROJECT NO.
16-3105
SCALE
—1"=100'
ORAWtNO NO.
DATE OBSERVED: MAY 29, 2016 Test Pit # 1
ELEVA110N:
DEP1N
FEET
5
Y
M
B
0
L
S
MA
P
L
E
DESCR1P710N OP MATERIAL
AND SAMPLE LOCATION
LABORATORY
TEST RESULTS
REMARKS
5
Topsoil
' //
r,
p
Reddish—brown, blocky to
sandy clay with some gravel
DD= 104.4 pcf
MC= 16.3 X
_
—
___ 10
- 15
,—,
Layer of rocks in clayey matrix
/ /
/ ' f
/4
❑
Light brown, hard clay
DD= 113.4 pcf
MC= 12.3X
Bottom of Test Pit ® 8 feet
No Ground Water
Encountered
LEGEND:
0 — 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
P1 — Plasticity Index
GW — Ground water
LIP ENGINEERING, INC.
SUBSURFACE EXPLORATION LOG
oma:
16-3105
Ma:
1
DATE OBSERVED: MAY 29. 2016 Test Pit # 2
ELEVATION:
DEPTH
FEET
S
Y
M
B
0
L
S
A
M
P
L
E
DESCRIPTION OF MATERIAL
AND SAMPLE LOCA770N
LABORATORY
TEST RESULTS
REMARKS
_
Topsoil
/
,��,
o
Reddish -brown, blocky to
sandy clay with some gravel
DD= 108.9pcf
MC= 79 X p
J J'
�/J
JJJ
/i
/i
El
Light brown, hard clay
00= 111.9 pcf
MC= 123 X
10
Bottom of Test Pit 0 8 feet
No Ground Water
Encountered
—
15
20
LEGEND:
o - 2 -Inch 0.0. 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
PROW Na:
16-3105
„,c;
2
113
a
3
2
0
h —2
_3
— 4
3
2
0
— 1
—2
L.
a.
—3
— 4
EXPANSION
UPON
ADDITION
UNDER
PRESSURE
CONSTANT
OF
OF WATER
1000 PSF
t
0.1 1.0 10 100
APPLIED PRESSURE — ksf
Sample of Light brown clay From: Test Pit No. 1 at 8feet
Natural Dry Unit Weight = 113.4 pcf
Natural Moisture Con ten t = 12.3 percent
2.7X swell 0 6ksf Swell Pressure
0.1 1.0 10 100
APPLIED PRESSURE — ksf
Sample of Brown, sandy clay with some gravel From: Test Pit No. 1 at — 5feet
Natural Dry Unit Weight = 104.4 pcf
Natural Moisture Content = 16.3 percent
0.4X swell 0 2ksf Swell Pressure
EXPANSION
UPON
ADDITION
UNDER
PRESSURE
CONSTANT
OF
OF WATER
1000 PSF
0.1 1.0 10 100
APPLIED PRESSURE — ksf
Sample of Light brown clay From: Test Pit No. 1 at 8feet
Natural Dry Unit Weight = 113.4 pcf
Natural Moisture Con ten t = 12.3 percent
2.7X swell 0 6ksf Swell Pressure
LKP Engineering, Inc.
Swell — Consolidation Test Results
PROJECT Hn:
15-3105
FIGURE MCA:
3
3
2
0
0
13 —2
g.
cj 3
a
—4
3
2
0
S.
—2
V —3
—4
LKP Engineering, Inc.
Swell — Consolidation Test Results
Peascr Ma
15-3105
4
ADDITION
EXPAt,SION
OF
UPON
WATER
UNDER
PRESSURE
CONSTANT
F 1000
PSF�\
10
Test
swell 0 1.8ksf
Pit No.2
Swell
at
Pressure
N
3.5feet
100
0.1
10
Reddish—brown,
Unit Weight =
Content =
APPLIED PRESSURE
—
gravel
ksf
Sample of.
Natural Dry
Natural Moisture
sandy clay with some
108.9 pcf
19 percent
From:
0.2Z
LKP Engineering, Inc.
Swell — Consolidation Test Results
Peascr Ma
15-3105
4
ADDITION
EXPAt,SION
OF
UPON
WATER
UNDER
PRESSURE
CONSTANT
F 1000
PSF�\
0.1 10 10 100
APPLIED PRESSURE — ksf
Sample of. Light brown clay From: Test Pit No. 2 at 8feet
Natural Dry Unit Weight = 111.9 pcf
Natural Moisture Content a 72.3 percent
1.6X swell 0 5ksf Swell Pressure
LKP Engineering, Inc.
Swell — Consolidation Test Results
Peascr Ma
15-3105
4
•
► D
► D•
•
D
• v'
V
► � 9
▪ 'KC
D O
► D
ZZ
• '►O
'
•
• ►
D •
• 1,
LOPE AWAY FROM BUILDING
COVER BACKFILL WITH A MINIMUM
OF ONE FOOT OF RELATIVELY
IMPERVIOUS SOIL
FOOTING
GRANULAR FILL
//\\ INUS 314 -INCH DIAMETER, COARSE,
CLEAN CRUSH ROCK
ILTER FABRIC (MIRAFI
140N OR EQUIVALENT)
30 MIL MINIMUM THICKNESS,
PLASTIC LINER, GLUED TO TH
FOUNDATION WALL
-INCH DIAMETER PERFORATED PIPE SLOPED TO A
DAYLIGHT LOCATION AWAY FROM THE FOUNDATION
AT 1!4 -INCH PER FOOT FOR FLEXIBLE AND 1I8 -INCH
MINIMUM FOR RIGID PIPE OR TO A SUMP PUMP
CIVIL/GEOTECHNICAL
Engineering, Inc.
P.O. Bax 724 Eepte, CO 61671
Tel.(970) 926-9088
PERIMETER DRAIN
LOT 3, THE RANCH AT COULTER CREEK PUD
CATTLE CREEK RIDGE ROAD
GARFIELD COUNTY, COLORADO
FRO ECT Na . 16-3105
SCALD N.T,S.
FJCVRC NO.
5