HomeMy WebLinkAboutSubsoils Report for Foundation DesignlGn*i'ril**1'ffft:fr'Y$;*'*
An Employcc Owncd Compony
5020 County Road 154
Glenwood Springs, CO 81601
phone: (910)945-1988
fax: (970) 945-8454
ernail : kaglenwood@kumarusa.com
www.kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, and Summit CounS, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED RESIDENCE
LOT 20, FIRST EAGLES POINT, BATTLEMENT MESA
318 EAGLE RIDGE DRIVE
GARFTELD COUNTY, COLORADO
PROJECT NO.22-7-213
JUNE 9,2022
PREPARED FOR:
TRAVIS SLAPE
10 SMOKEY HILL COURT
PARACHUTE, COLORADO 81635
slape.t@tyahoo.com
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY
PROPOSED CONSTRUCTION
SITE CONDITIONS.
FIELD EXPLORATION
SUBSURFACE CONDITIONS ...
FOLINDATION BEARING CONDITIONS .
DESIGN RECOMMENDATIONS
FOUNDATIONS
FLOOR SLABS
LINDERDRAIN SYSTEM .....
SURFACE DRAINAGE.........
LIMITATIONS..
FIGURE 1 - LOCATION OF EXPLORATORY BORING
FIGURE 2 - LOG OF EXPLORATORY BORING
FIGURE 3 - GRADATION TEST RESULTS
TABLE 1 - SUMMARY OF LABORATORY TEST RESULTS
1
1
1
..-2-
,,
2
2
aJ
4
4
-4-
Kumar & Associates, lnc, @ Project No.22-7-213
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed residence to be located on
Lot20, First Eagles Point, Battlement Mesa, 318 Eagle Ridge Drive, Garfield County, Colorado.
The project site is shown on Figure 1. The purpose of the study was to develop
recommendations for the foundation design. The study was conducted in accordance with our
agreement for geotechnical engineering services to you dated March 7 ,2022.
An exploratory boring was drilled to obtain information on the general subsurface conditions.
Samples of the subsoils obtained during the f,reld exploration were tested in the laboratory to
determine their classification and other engineering characteristics. The results of the field
exploration and laboratory testing were analyzed to develop recommendations for foundation
types, depths and allowable pressures for the proposed building foundation. This report
summarizes the data obtained during this study and presents our conclusions, design
recommendations and other geotechnical engineering considerations based on the proposed
construction and the subsurface conditions encountered.
PROPOSED CONSTRUCTION
The residence will be a one-story wood-frame structure over a crawlspace with an attached
llz story slab-on-grade ground floor garage, located on the lot as shown on Figure 1. Grading
for the structure is expected to be relatively minor with cut depths between about 2 to 4 feet.
We assume relatively light foundation loadings, typical of the proposed type of construction.
If building loadings, location or grading plans change significantly frorn those described above,
we should be notified to re-evaluate the recommendations contained in this report.
SITE CONDITIONS
The lot was vacant at the time of our field exploration and the ground surface appeared to have
undergone some minor grading probably associated with the subdivision development. The
terrain is relatively flat with a strong slope down to the northwest. Vegetation consisted of
grasses and weeds. There were scattered cobbles on the ground surface.
FIELD EXPLORATION
The field exploration for the project was conducted on March 9,2022. One exploratory boring
was drilled at the location shown on Figure 1 to evaluate the subsurface conditions. The boring
was advanced with 4-inch diameter continuous flight augers powered by a truck-mounted CME-
45B drill rig. The boring was logged by a representative of Kumar & Associates.
Kumar & Associates, lnc. @ Project No.22-7-213
1
Samples of the subsoils were taken with l%-inch and 2-inch I.D. spoon samplers. The samplers
were driven into the subsoils at various depths with blows from a 14O-pound hammer falling 30
inches. This test is similar to the standard penetration test described by ASTM Method D-1586.
The penetration resistance values are an indication of the relative density or consistency of the
subsoils. Depths at which the samples were taken and the penetration resistance values are
shown on the Log of Exploratory Boring, Figure 2. The samples were refurned to our laboratory
for review by the project engineer and testing.
SUBSURFACE CONDITIONS
A graphic log of the subsurface conditions encountered at the site is shown on Figure 2. The
subsoils encountered consisted of about 6 feet of medium dense, clayey to very clayey silty sand
and gravel with cobbles overlying relatively dense, silty sandy gravel and cobbles with probable
boulders down to the drilled depth of 8% feet. Drilling in the dense coarse granular soils with
auger equipment was difficult due to the cobbles and probable boulders and drilling refusal was
encountered in the deposit.
Laboratory testing performed on samples obtained from the boring included natural moisture
content and gradation analyses. The soils were too rocky to obtain undisturbed samples for
swell-consolidation testing. Results of gradation analyses performed on small diameter drive
samples (minus I%-inch fraction) of the granular subsoils are shown on Figure 3. The laboratory
testing is summarizedrn Table 1.
No free water was encountered in the boring at the time of drilling and the subsoils were slightly
moist.
FOUNDATION BEARING CONDITIONS
The natural granular soils possess moderate bearing capacity and, in general, relatively low
settlement potential. The upper sand and gravel soils may tend to settle some when wetted.
Spread footings bearing on the natural granular soils can be used for foundation support of the
proposed residence with some risk of settlement, primarily if the bearing soils were to become
wetted. Placing the footings entirely on the underlying dense coarse granular soils would
provide a lower risk of settlement.
DESIGN RECOMMENDATIONS
FOI-INDATIONS
Considering the subsurface conditions encountered in the exploratory boring and the nature of
the proposed construction, we recommend the building be founded with spread footings bearing
on the natural granular soils. Precautions should be taken to prevent wetting of the bearing soils.
Kumar & Associates, lnc. @ Project No.22-7-2'13
a-J-
The design and construction criteria presented below should be observed for a spread footing
foundation system.
1) Footings placed on the undisturbed natural granular soils should be designed for
an allowable bearing pressure of 2,000 psf. Based on experience, we expect
settlement of footings designed and constrdcted as discussed in this section will
be about I inch or less. There could be some additional settlement for footings
bearing on the upper sand and gravel soils if the soils were to become wetted.
2) The footings should have a minimum width of 18 inches for continuous walls and
2 feel for isolated pads. - --
3)footings and footings beneath unheated areas should be provided with
adequate soil cover above their bearing elevation for frost protection. Placement
of foundations at least 36 inches below exterior grade is typically used in this
atea.
4)Continuous foundation walls should be well reinforced top and bottom to span
local anomalies such as by assuming an unsupported length of at least 10 feet.
Foundation walls acting as retaining structures should also be designed to resist a
lateral earth pressure coffesponding to an equivalent fluid unit weight of at least
50 pcf for the on-site soils, excluding topsoil and oversized (plus 6 inch) rocks, as
backfill.
Existing fill, topsoil and any loose disturbed soils should be removed and the
footing bearing level extended down to the firm natural granular soils. The
exposed soils in footing area should then be moistened and compacted.
A representative ofthe geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
FLOOR SLABS
The natural granular soils, exclusive of topsoil, are suitable to support lightly loaded slab-on-
grade construction. To reduce the effects of some differential movement, floor slabs should be
separated from all bearing walls and columns with expansion joints which allow unrestrained
vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage
cracking. The requirements for joint spacing and slab reinforcement should be established by the
designer based on experience and the intended slab use. A minimum 4-inch layer of well graded
sand and gravel (aggregate base course) should be placed beneath floor slabs for support and to
facilitate drainage. This material should consist of minus 2-inch aggregate with at least 50%
retained on the No. 4 sieve and less than 2o/o passing the No. 200 sieve.
s)
6)
Kumar & Associates, lnc. o Project No.22-7-2'13
-4-
All lrll materials for support of floor slabs should be compacted to at least 95o/o of maximum
standard Proctor density at a moisture content near optimum. Required fill can consist of the
on-site granular soils devoid of topsoil and oversized (plus 6-inch) rocks.
UNDERDRAIN SYSTEM
A perimeter foundation drain around shallow (less than 3 feet deep) crawlspace areas should not
be needed with adequate compaction of foundation backfill and positive surface drainage is
provided away from foundation walls. We recommend below-grade construction, such as
retaining walls, deeper crawlspace and basement areas, be protected from wetting and
hydrostatic pressure buildup by an underdrain and wall drain system. If the finished floor
elevation of the proposed structure is revised to have a floor level below the surrounding grade,
we should be contacted to provide recommendations for an underdrain system.
SURFACE DRAINAGE
Positive surface drainage is an important aspect of the project to prevent wetting of the bearing
soils below the building. The following drainage precautions should be observed during
construction and maintained at all times after the residence has been completed:
1) Inundation ofthe foundation excavations and underslab areas should be avoided
during construction.
2) Exterior backfill should be adjusted to near optimum moisture and compacted to
at least 95o/o of the maximum standard Proctor density in pavement and slab areas
and to at least 90%o of the maximum standard Proctor density in landscape areas.
3) The ground surface surrounding the exterior of the building should be sloped to
drain away from the foundation in all directions. We recommend a minimum
slope of 6 inches in the first 10 feet in unpaved areas and a minimum slope of
3 inches in the first l0 feet in paved areas.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill.
5) Landscaping which requires regular heavy irrigation, such as sod, and sprinkler
heads should be located at least 5 feet from foundation walls.
LIMITATIONS
This study has been conducted in accordance with generally accepted geotechnical engineering
principles and practices in this area at this time. We make no warranty either express or implied.
The conclusions and recommendations submitted in this report are based upon the data obtained
Kumar & Associates, lnc. o Project No.22-7-2'13
-5-
from the exploratory boring drilled at the location indicated on Figure 1, the proposed type of
construction and our experience in the area. Our services do not include determining the
presence, prevention or possibility of mold or other biological contaminants (MOBC) developing
in the future. If the client is concemed about MOBC, then a professional in this special field of
practice should be consulted. Our findings include extrapolation of the subsurface conditions
identified at the exploratory boring and variations in the subsurface conditions may not become
evident until excavation is performed. If conditions encountered during construction appear
different from those described in this report, we should be notified so that re-evaluation of the
recommendations may be made.
This report has been prepared for the exclusive use by our client for design purposes. We are not
responsible for technical interpretations by others of our information. As the project evolves, we
should provide continued consultation and field services during construction to review and
monitor the implementation of our recommendations, and to verifu that the recommendations
have been appropriately interpreted. Significant design changes may require additional analysis
or modifications to the recommendations presented herein. We recommend on-site observation
of excavations and foundation bearing strata and testing of structural fill by a representative of
the geotechnical engineer.
Respectfully Submitted,
Kunrar' & Associatesn Inc.
David A. Noteboom, Staff Engineer
Reviewed by:
David A. Young, P
DAYlkac
b
o
3 6
(,a
Kumar &,Associates, lnc, 'Project No.22"7-213
EAGLE RIDGE DRIVE
LOT 21
i
10 0 n
APPROXIMATE SCALE-FEET
22-7 -213 Kumar & Associates LOCATION OF EXPLORATORY BORING Fig. 1
E
:
e
BORING 1 LEGEND
0
GRAVEL AND SAND (GC-SC); WITH COBBLES, CLAYEY T0
VERY, CLAYEY, SILTY, MEDIUM DENSE, MOIST TO SLIGHTLY
MOIST, LIGHT BROWN, CALCAREOUS.
GRAVEL AND COBBLES (OC-OV); SANDY, CLAYEY, SILTY,
PROBABLE BOULDERS, DENSE, SLIGHTLY MOIST, MIXED BROWN
AND GRAY, CALCAREOUS.
53/6
F
trJtdtL
I-Fo-tdo
5
20/12
WC=4.9
+4=12
-200=58 i
I
I
DRIVE SAMPLE, 2-INCH I.D, CALIFORNIA LINER SAMPLE,
33/6, 50/3
WC=2.0
+4=44
-200=28
DR|VE SAMpLE, 1 5/8-rNCH t.D. SPLTT SP00N STANDARD
PENETRATION TEST.
10 26712DR|VE SAMPLE BLOW COUNT. INDICATES THAT 20 BLOWS 0F
14o-POUND HAMMER FALLING 30 INCHES WERE REQUIRED
t
TO DRIVE THE SAMPLER 12 INCHES.
PRACTICAL AUGER DRILLING REFUSAL.
NOTES
1 THE EXPLORATORY BORING WAS DRILLED ON MARCH 9, 2022
WITH A 4-INCH DIAMETER CONTINUOUS FLIGHT POWER AUGER.
2. THE LOCATION OF THE EXPLORATORY BORING WAS MEASURED
APPROXIMATELY BY PACING FROM FEATURES SHOWN ON THE
SITE PLAN PROVIDED.
3. THE ELEVATION OF THE EXPLORATORY BORING WAS NOT
MEASURED AND THE LOG OF THE EXPLORATORY BORING IS
PLOTTED TO DEPTH.
4. THE EXPLORATORY BORING LOCATION SHOULD BE CONSIDERED
ACCURATE ONLY TO THE DEGREE IMPLIED BY THE METHOD
USED.
5. THE LINES BETWEEN MATERIALS SHOWN ON THE EXPLORATORY
BORING LOG REPRESENT THE APPROXIMATE BOUNDARIES
BETWEEN MATERIAL TYPES AND THE TRANSITIONS MAY BE
GRADUAL.
6. GROUNDWATER WAS NOT ENCOUNTERED IN THE BORING AT THE
TIME OF DRILLING.
7. LABORATORY TEST RESULTS:
WC = WATER CONTENT (%) (ASTM D 2216);
+4 = PERCENTAGE RETAINED ON NO.4 SIEVE (ISTU O OSI:);
-2OO = PERCENTAGE PASSING NO, 2OO SIEVE (ASTM D 1140).
22-7-213 Kumar & Associates LOG OF EXPLORATORY BORING Fig. 2
E
5N
SIEVE ANALYSISHYDROMETER ANALYSIS
CLEAR SQUARE OPENINGS
ari, t/^' t tlri
TIME READINGS
2,1 HRS 7 HRs atoo
U.S. STANDARO SERIES
450 {40 t30 {16 410 lA
f'
i'l
l
!
1
I
:
I
I
.ii
"i
=e
t00
90
80
?o
60
50
/ao
30
20
to
o
t0
20
30
10
5n
60
70
80
90
=
E
too
.005 .009 1.127
I,125 2,O
DIAMETER OF PARTICLES IN MILLIM
CLAY TO SILT COBBLES
GRAVEL 12 % SAND 50 %
LIQUID LIMIT - PLASTICITY INDEX
SAMPLE OF: Very Cloyey Silty Sond wilh Grovel
SILT AND CLAY 58 %
FROM:Borlngl@4'
6
t00
so
ao
70
60
50
40
30
20
to
0
o
t0
20
50
10
5o
60
70
80
90
100
=
I I rlrt
.o75
I
,o37 152
OFP INM
CLAY TO SILT COBBLES
GRAVEL 44 % SAND
LIQUID LIMIT
SAMPLE OF: Silty Sondy Grovel
28%
PLASTICITY INDEX
SILT AND CLAY 28 %
FROM:Boringl@7'
Th.s6 lesl rosulls opply only lo lho
somplos whlch wers lssled. Th6
losllng roporl sholl nol be reproduc€d,
€xcepl ln full, wllhoul lh€ wrlll6n
qpprovql of Kumqr & Assoclqtos, lnc,
Sleve onolysls losllng ls perfo.med ln
occordqnce wlth ASTM D6913, ASTM 07928,
ASTM C136 ond/or ASTM Dll,{0.
SAND GRAVEL
MEDIUM COARSE FINE COARSEFINE
SIEVE ANALYSISHYDROMETER ANALYSIS
U.S. STANDARD SERIES
450 4aO 43d 4t6 {tO {A 5"6" I
CLEAR SOUARE OPENIilGS
\/a" 3/a" 1 1/2"
TIME READINGS
I /
I
l
I
I
I
I
l
I /I
I
I
r
L
I
:
l
I
rlI tt
GRAVELSAND
FINE MEDIUM COARSE FIN E COARSE
22-7 -213 Kumar & Associates GRADATION TEST RESULTS Fis.3
rcn *iffi fi'f,H:ffin'"nE;
n' *' *
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
No.22-7-2'13
Very Clayey Silty Sand
with Gravel
Silty Sandy Gravel
SOIL TYPE
(osfl
UNCONFINED
COMPRESSIVE
STRENGTH
(olol
PLASTIC
INDEX
ATTERBERG LIMITS
("/"1
LIQUID LIMIT
PERCENT
PASSING NO.
200 stEVE
SAND
(%)
GRADATION
GRAVEL
("/"1
(pcfl
NATURAL
DRY
DENS]TY
(ol
NATURAL
MOISTURE
CONTENT
(ft)
DEPTH
SAMPLE LOCATION
BORING
12
44
4
1
1 58
28
30
28
4.9
2.0