HomeMy WebLinkAboutSoils Report 05.31.2018H-P�KUMAR
Geotechnical Engineering 1 Engineering Geology
Materials Testing 1 Environmental
5020 County Road 154
Glenwood Springs, CO 81601
Phone: (970) 945-7988
Fax: (970) 945-8454
Email: hpkglenwood@kumarusa.com
Office Locations: Denver (HQ), Parker, Colorado Springs, Fort Collins, Glenwood Springs, Summit County, Colorado
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED APARTMENT BUILDING
170 MEL RAY ROAD
GLENWOOD SPRINGS, COLORADO
PROJECT NO. 18-7-330
MAY 31, 2018
PREPARED FOR:
EDNA MONTANEZ
170 MEL RAY ROAD
GLENWOOD SPRINGS, COLORADO 81601
(M onta nexed na 330 @ gma i1.cam)
RECEIVED
GARFIELD COUNTY
COMMUNITY DEVELOPMENT
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY 1
PROPOSED CONSTRUCTION 1
SITE CONDITIONS 1
FIELD EXPLORATION 2
SUBSURFACE CONDITIONS 2
FOUNDATION BEARING CONDITIONS 3
DESIGN RECOMMENDATIONS 3
FOUNDATIONS 3
FLOOR SLABS 4
UNDERDRAIN SYSTEM 4
SURFACE DRAINAGE 5
LIMITATIONS 5
FIGURE 1 - LOCATION OF EXPLORATORY BORING
FIGURE 2 - LOG OF EXPLORATORY BORING
FIGURE 3 - SWELL -CONSOLIDATION TEST RESULTS
H-P%KUMAR
Project No. 18-7-330
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed apartment building to be located
at 170 Mel Ray Road, Glenwood Springs, 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 Edna
Montanez dated May 8, 2018.
An exploratory boring was drilled to obtain information on the subsurface conditions. Samples
of the subsoils obtained during the field exploration were tested in the laboratory to determine
their classification, compressibility or swell and other engineering characteristics. The results of
the field exploration and laboratory testing were analyzed to develop reconunendations 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 proposed apartment building will be two story wood frame construction above a crawlspace
and located in the southeast portion of the property. Grading for the structure is assumed to be
relatively minor with cut depths between about 3 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 from those described above,
we should be notified to re-evaluate the recommendations contained in this report.
SITE CONDITIONS
The property is developed with a single story wood frame home, sheds and gravel driveway as
shown on Figure 1. The proposed building site is vegetated with grass and weeds. The ground
surface is relatively flat with a slight slope down to the south.
H-PKUMAR
Project No. 18-7-330
FIELD EXPLORATION
The field exploration for the project was conducted on May 17, 2018. 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 H-P/Kumar.
Samples of the subsoils were taken with 1% inch and 2 inch I.D. spoon samplers. The samplers
were driven into the subsoils at various depths with blows from a 140 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 returned 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 below about 1/ foot of topsoil consist of hard to very stiff sandy silty clay to 12 feet
overlying silty sandy gravel with cobbles and probable small boulders. Drilling in the dense
granular soils with auger equipment was difficult due to the cobbles and probable boulders.
Laboratory testing performed on samples obtained from the boring included natural moisture
content and density. Results of swell -consolidation testing performed on relatively undisturbed
drive samples of sandy clay, presented on Figure 3, indicate low to moderate compressibility
under conditions of loading and wetting. The sample tested from a depth of 21/2 feet showed an
expansion potential when wetted.
No free water was encountered in the boring at the time of drilling and the subsoils were slightly
moist. The boring was backfilled following drilling.
H-PagKUMAR
Project No. 18-7-330
impose a minimum dead load of 800 psf,
FOUNDATION BEARING CONDITIONS
The upper sandy clay soils are hard to very stiff and typically adequate to support lightly loaded
spread footings. There is a risk of potential heave if the bearing soils are wetted. Precautions
should be taken to limit the effects of potential heave to foundations and floor slabs. The
expansiveness of the exposed clay soils should be evaluated at the time of excavation for
possible need to sub -excavate and replace with structural fill.
DESIGN RECOMMENDATIONS
FOUNDATIONS
Considering the subsurface conditions encountered in the exploratory boring and the nature of
the proposed construction, we recommend the apartment building be founded with spread
footings bearing on the natural sandy clay soils.
The design and construction criteria presented below should be observed for a spread footing
foundation system.
1) Footings placed on the undisturbed natural soils should be designed for an
allowable bearing pressure of 2,500 psf. The footings should also be designed to
Based on experience, we expect initial
settlement of footings designed and constructed as discussed in this section will
be about 1 inch or less. There could be some additional movement if the bearing
soils become wetted.
2) The footings should have a minimum width of 16 inches for continuous walls and
2 feet for isolated pads.
3) Exterior footings and footings beneath unheated areas should be provided with
adequate soil cover above their bearing elevation for frost protection. Placement
of foundations at leas 36 inches below exterior grade is typically used in this area.
4) Continuous foundation walls should be reinforced top and bottom to span local
anomalies such as by assuming an unsupported length of at least 12 feet.
Foundation walls acting as retaining structures should also be designed to resist a
H-P*KUMAR
Project No. 18-7-330
lateral earth pressure corresponding to an equivalent fluid unit weight of at least
55 pcf.
5) The topsoil and any loose or disturbed soils should be removed down to the
natural sandy clay soils. The exposed clay soils in footing area should be
evaluated for expansion potential and subexcavated where needed.
6) A representative of the geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
FLOOR SLABS
The upper sandy clay soils possess an expansion potential and there could be slab heave if the
subgrade soils become wetted. To reduce the effects of some differential movement, slabs -on -
grade 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 slip joint should be
provided at the bottom of non -load bearing walls so that potential heave of the slab is not
transmitted to the upper structure. A minimum 4 inch layer of relatively well graded sand and
gravel such as road base should be placed beneath slabs for support. This material should consist
of minus 2 inch aggregate with at least 50% retained on the No. 4 sieve and less than 12%
passing the No. 200 sieve.
All fill materials for support of floor slabs should be compacted to at least 95% of maximum
standard Proctor density at a moisture content near optimum. Required fill should consist of
imported gravel such as road base.
UNDERDRAIN SYSTEM
It is our understanding the proposed finished floor elevation at the lowest level is at or above the
surrounding grade and the crawlspace is relatively shallow, about 3 feet deep. Therefore, a
foundation drain system is not required.
It has been our experience in the area that local perched
groundwater can develop during times of heavy precipitation or seasonal runoff. Frozen ground
H-PKUMAR
Project No. 18-7-330
during spring runoff can create a perched condition. We recommend below -grade construction,
such as retaining walls 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. All earth retaining structures should be properly drained.
SURFACE DRAINAGE
The following drainage precautions should be observed during construction and maintained at all
times after the apartment building has been completed:
1) Inundation of the 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 95% of the maximum standard Proctor density in pavement and slab areas
and to at least 90% 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 12 inches in the first 10 feet in unpaved areas and a minimum slope of 3
inches in the first 10 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 should be located at least 5
feet from foundation walls. Consideration should be given to use of xeriscape to
reduce the potential for wetting of soils below the building caused by irrigation.
LINIITATIONS
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
from the exploratory boring drilled at the location indicated on Figure 1, the proposed type of
H-P%KUMAR
Project No. 18-7-330
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 concerned about MOBC, then a professional in this special field of
practice should be consulted. Our findings include interpolation and 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 verify 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,
Louis E. Eller
Reviewed by:
Steven L. Pawlak, P.E.
LEE/ksw
4.
cc: Kurtz & Associates - Bnan ' tirtz (,kurtzenginccr@yahoo.com)
H-PagKUMAR
Project No. 18-7-330
z
11
-`i
we MAILBOX
m"
L_6 IAY•I-I46
wsuswIAw
(55.51
LOT 3
(BASIS OF BEARRIGS)
SB8'33'30"E 141.41'
m�ip."asuaF""w: uF ,
STONE
PLANTER
SINGLE STORY
FRAME HOUSE
170 MELRAY
ROAD
I' + BUILDING
to .o ■ra
Ivt;
m,La+ Hurt � ils
1:1) --FOUND NO
1 5 REBAR
15 0 15 30
APPROXIMATE SCALE—FEET
x s'
NB813'30"W 141.41'
LOT 1
LOT 2
BLOCK 2
14.141± S,F
•
BORING 1
01'51'44'W 100.00'
ALF
W i
£`
BUILDING
lC N1164 --
1
45I GO WO
18-7-330
H -P- KUMAR
LOCATION OF EXPLORATORY BORING
Fig. 1
1-
LJ
x
1-
a
LJ
0
5
10
15
20
25
18-7-330
BORING 1
51/12
WC=12.0
DD=119
54/12
19/12
WC=14.0
DD=106
39/12
50/3
H-P�KUMAR
LEGEND
0'
TOPSOIL; ORGANIC SANDY SILT AND CLAY, FIRM, SLIGHTLY MOIST, DARK
BROWN.
CLAY (CL); SANDY, HARD TO VERY STIFF, MOIST, BROWN.
GRAVEL (GP -GM); WITH COBBLES, POSSIBLE BOULDERS, SANDY, SILTY,
DENSE, SLIGHTLY MOIST, BROWN.
�i DRIVE SAMPLE, 2 -INCH I.D. CALIFORNIA LINER SAMPLE.
DRIVE SAMPLE, 1 3/8 -INCH I.D. SPLIT SPOON STANDARD PENETRATION
TEST.
51/12 DRIVE SA/4PLE BLOW COUNT. INDICATES THAT 51 BLOWS OF A
140 -POUND HAMMER FALLING 30 INCHES WERE REQUIRED TO DRIVE
THE SAMPLER 12 INCHES.
—s DEPTH AT WHICH BORING CAVED.
NOTES
1. THE EXPLORATORY BORING WAS DRILLED ON MAY 17, 2018 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);
DD = DRY DENSITY (pcf) (ASTM D 2216).
LOG OF EXPLORATORY BORING
Fig. 2
CONSOLIDATION - SWELL
CONSOLIDATION - SWELL
2
1
0
— 2
— 3
1
0
— 1
—2
— 3
1.0 APPLIED PRESSURE — KSF
10
100
I
I
I I
I
—
SAMPLE OF: Sandy Clay
FROM: Boring 1 0 2.5'
- .
...
T
- -
WC = 12.0 %, DD = 119 pcf
�_
_
NO MOVEMENT UPON
WETTING
�
'
l
_..
I
I I
I
—
1
EXPANSION UNDER CONSTANT
PRESSURE UPON WETTING
——...
f
—Y—.I
I
II
`
evor* M
irint mate apply ethe
dol lolled. The testIng repeel
.hrdI not be .pn)donod,act* In
IA .11lnut Ire ef10ea ppp.p.vl of
omo and HWCWH. Mt. Seed
C,dnoli Infmq performed In
oo rdmrce with ASTM 0-4516.
10 APPLIED PRESSURE — KSF 10 in
II
1.0 APPLIED PRESSURE — KSF
10
100
18-7-330
H-P-KUMAR
SWELL -CONSOLIDATION TEST RESULTS
Fig. 3
—
SAMPLE OF: Sandy Clay
FROM: Boring 1 0 10'
WC = 14.0 %, DD = 106 pcf
- .
...
T
- -
�_
.-.
NO MOVEMENT UPON
WETTING
�
'
l
_..
—
——...
f
—Y—.I
I
II
`
evor* M
irint mate apply ethe
dol lolled. The testIng repeel
.hrdI not be .pn)donod,act* In
IA .11lnut Ire ef10ea ppp.p.vl of
omo and HWCWH. Mt. Seed
C,dnoli Infmq performed In
oo rdmrce with ASTM 0-4516.
10 APPLIED PRESSURE — KSF 10 in
18-7-330
H-P-KUMAR
SWELL -CONSOLIDATION TEST RESULTS
Fig. 3