HomeMy WebLinkAboutSubsoil Study for Foundation Design 05.10.15HEPWORTH
I [,k hni...I In..
i020 C:.amn Road 154
Glrnm'nd Spring-. CnLmiJo I W I
Phone- 9794;-7988
P,,: 90.945.1454
moo, hpc.. �'�Iq�emomdia,in
JOB NO. 116 136A
MAY 10, 2015
PREPARED FOR:
JOEL RUIZ
P.O. BOX 37
ILT, COLORADO 81652
ioel-ruiz@live.com
Parker 303-841-7119 h Colorado I Springs 719-633-5562 • Silverrhome 970-468-1989
SUBSOIL STUDY
FO
t FOUNDATION DESIGN
P
10POSED RESIDENCE
LOT 2',
SUN MEADOWS ESTATES
SC
UTH MEADOW CIRCLE
GARF
ELD COUNTY, COLORADO
JOB NO. 116 136A
MAY 10, 2015
PREPARED FOR:
JOEL RUIZ
P.O. BOX 37
ILT, COLORADO 81652
ioel-ruiz@live.com
Parker 303-841-7119 h Colorado I Springs 719-633-5562 • Silverrhome 970-468-1989
PURPOSE AND SC
OPE OF S'
PROPOSED CONS
FRUCTIOl
SITE CONDITION
................
FIELD EXPLORA
ION..........
SUBSURFACE CO
DITIONS
FOUNDATION BE
RING C(
DESIGN RECOMMENDATIC
FOUNDATIONS
..................
FLOOR SLABS ..................
UNDERDRAINYSTEM...
SURFACE DRA
AGE......
FIGURE I - LOCATION OF E
FIGURE 2 - LOGS F EXPLO
FIGURE 3 - LEGED D AND NI
FIGURES 4 AND 5 - SWELL -1
TABLE 1- SUMMARY OF LA
Job No. 115 112A
OF CONTENTS
ORATORY BORINGS
TORY BORINGS
CION TEST RESULTS
TEST RESULTS
The proposed reside ice will bet o story wood frame construction over a crawlspace and
-
located between the xploratory borings as shown on Figure 1. Ground floor of the
garage will be slab -ca -grade. Grading for the structure is assumed to be relatively minor
-
with cut depths betty en about 3 to 5 feet. We assume relatively light foundation
loadings, typical of t ic proposed type of construction.
If building loadings, ocation or ading plans change significantly from those described
above, we should be otified to r -evaluate the recommendations contained in this report.
PURPOSE
AND SCOPE OF STUDY
-
This report present
the results
f a subsoil study for a proposed residence to be located
on Lot 27, Sun Me
dows Estate;,
South Meadow Circle, Garfield County, Colorado. The
-
project site is show
i on Figure
. The purpose of the study was to develop
recommendations f
r the foundation
design. The study was conducted in accordance
-
with our agreement
for geotecla
ical engineering services to Joel Ruiz dated April 22,
2016. Hepworth -P
wlak Geote
hnical Inc., previously performed a preliminary
-
geotechnical study I
or Sun Meai
low Estates (formerly Manaus View Subdivision) and
presented our findings
in a repoit
dated March 28, 2000, Job No. 100 169.
-
A field exploration
program consisting
of exploratory borings was conducted 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 ors
ell and orb
r engineering characteristics. The results of the field
exploration and labc
ratory testing
were analyzed to develop recommendations for
foundation types, depths
and allowable
pressures for the proposed building foundation.
This report summar'
zes the data
Dbtained during this study and presents our conclusions,
-
design reconimendai
ions and other
geotechnical engineering considerations based on the
proposed constructin
and the subsurface
conditions encountered.
PR
OSED CONSTRUCTION
-
The proposed reside ice will bet o story wood frame construction over a crawlspace and
-
located between the xploratory borings as shown on Figure 1. Ground floor of the
garage will be slab -ca -grade. Grading for the structure is assumed to be relatively minor
-
with cut depths betty en about 3 to 5 feet. We assume relatively light foundation
loadings, typical of t ic proposed type of construction.
If building loadings, ocation or ading plans change significantly from those described
above, we should be otified to r -evaluate the recommendations contained in this report.
Job No. 115
-2 -
SITE CONDITIONS
Lot 27 is located to
he north of
outh Meadow Circle, west of South Meadow Drive with
-
County Road 216 t
the north.
a ground surface in the building area is gently sloping
down to the south.
Vegetation C
Drisisted of grass, weeds, and brush. A natural drainage
located in the weste
m part of the
property and on the order of 10 feet deep was dry at the
time of our field ex
loration.
IELD EXPLORATION
The field exploratio
i for the pro
ject was conducted on April 27, 2016. Two exploratory
borings were drilled
at the locati
ns shown on Figure 1 to evaluate the subsurface
n
conditions. The hot
ings were ad
vanced with 4 -inch diameter continuous flight augers
powered by a truck-
mounted C
-45B drill rig. The borings were logged by a
-
representative of He
pworth-Paw
lak Geotechnical, Inc.
-
Samples of the subs
ils were taken
with a 2 inch I.D. spoon sampler. The sampler was
-
driven into the subsoils
at various
depths with blows from a 140 pound hammer falling 30
inches. This test is
imilar to the
standard penetration test described by ASTM Method
-
D-1586. The peneu
ition resista
cc values we an indication of the relative density or
consistency of the st
bsoils. Depais
at which the samples were taken and the penetration
-
resistance values are
shown on the
Logs of Exploratory Borings, Figure 2. The samples
were returned to our
laboratory f
Dr review by the project engineer and testing.
SUBSURFACE
CONDITIONS
-
Graphic logs of the
ubsurface conditions
encountered at the site me shown on Figure 2.
The subsoils encoun
ered, below
a minor (about Y: foot) depth of topsoil, consisted of
-
stiff to very stiff, vei
y sandy silt
md clay underlain at about 10 feet in Boring 1 by
medium dense, silty
3and with gr
avel and sandy silt layers that extended down to the
-
drilled depth of 31 ft
et.
-
1
Job No. 115
No free water was�ttcountered �tr the borings at the time of drilling and the subsoils were
slightly moist
BEARING CONDITIONS
The soils encountered at the site possess low bearing capacity and are expected to mainly
tend to settle if wett d. Spread I 3otings bearing on the natural soils can be used for
foundation support provided son ie risk of movement and distress is acceptable to the
owner. The risk of movement is primarily from wetting and precautions should be taken
to keep the bearing oil dry. The swell potential encountered in one of the samples tested
is considered an aroaly and c be neglected in the foundation design. However, the
settl-ment/heave po ,tial of the be
soils should be further evaluated at the time of
construction.
Providing several let t of strucmr it fill (reworking of the on-site natural soils) below the
footings or use of a I elical pier t3 pe foundation down to dense soils would reduce the risk
of foundation moven Lent. Provided below are recommendations for footings bearing on
the natural soils. If r!con=cndal ions for bearing on structural fill or for a helical pier
type foundation systc m are desired, we should be contacted.
DESI N RECOMMENDATIONS
FOUNDATIONS
Considering the subs irface condii Vons encountered in the exploratory borings, the nature
of the proposed coast ruction and i he soils typical of this area, we believe the building can
Job No.
-3-
Laboratory testing
erformed o
i samples obtained from the borings included natural
moisture content at
d density, a
id percent finer than sand size gradation analyses. Results
of swell-consolidat
on testing p
rformed on relatively undisturbed drive samples of the
soils, presented on
igures 4 an
15, generally indicate low to moderate compressibility
under conditions of
loading and
wetting. The sample from Boring 1 at 2%x feet showed a
low hydro-compres
ion potenti
1. The sample from Boring 2 at 5 feet showed a low
swell potential who
i wetted unc
er a constant light surcharge. The laboratory testing is
summarized in Tab
a 1.
No free water was�ttcountered �tr the borings at the time of drilling and the subsoils were
slightly moist
BEARING CONDITIONS
The soils encountered at the site possess low bearing capacity and are expected to mainly
tend to settle if wett d. Spread I 3otings bearing on the natural soils can be used for
foundation support provided son ie risk of movement and distress is acceptable to the
owner. The risk of movement is primarily from wetting and precautions should be taken
to keep the bearing oil dry. The swell potential encountered in one of the samples tested
is considered an aroaly and c be neglected in the foundation design. However, the
settl-ment/heave po ,tial of the be
soils should be further evaluated at the time of
construction.
Providing several let t of strucmr it fill (reworking of the on-site natural soils) below the
footings or use of a I elical pier t3 pe foundation down to dense soils would reduce the risk
of foundation moven Lent. Provided below are recommendations for footings bearing on
the natural soils. If r!con=cndal ions for bearing on structural fill or for a helical pier
type foundation systc m are desired, we should be contacted.
DESI N RECOMMENDATIONS
FOUNDATIONS
Considering the subs irface condii Vons encountered in the exploratory borings, the nature
of the proposed coast ruction and i he soils typical of this area, we believe the building can
Job No.
FLOOR SLABS
115 112A
-4 -
be founded with sp
-ead footing
bearing on the natural soils with a risk of movement. The
risk of movement A
mainly fro
wetting the bearing soils and precautions should be
taken to keep them
dry.
The design and con
struction cri
eria presented below should be observed for a spread
W footing foundation
ystem.
1) Foo
'ngs placed
on the undisturbed natural soils should be designed for an
allowable
bearing
pressure of 1,500 psf. Based on experience, we expect
inti
settlement
of footings designed and constructed as discussed in this
secti
Do will be at
out I inch or less. There could be additional differential
mov
ment of abc
or V2 to 1 inch if the bearing soils become wetted
depe
iding on the
depth and extent of the wetting.
2) The i
outings sho
Id have a minimum width of 18 inches for continuous
so
walh
and 2 feet f
3r isolated pads.
3) Extei
for footings
and footings beneath unheated areas should be provided
with
idequate soil
cover above their bearing elevation for frost protection.
Placement
of foundations
at least 36 inches below exterior grade is
typic
dly used in
is area.
4) Cont
nuous founc
ation walls should be heavily reinforced top and bottom
to sp
local anomalies
and better withstand the effects of some
diffej
ential movement
such as by assuming an unsupported length of at
least
4 feet. Foundation
walls acting as retaining structures should also
be de
igned tore
'st a lateral earth pressure corresponding to an equivalent
fluid
nit weight
f at least 55 pcf for the on-site soil as backfill.
5) The topsoil
and any
loose or disturbed soils should be removed and the
food
g bearing level
extended down to the undisturbed natural soils. The
subgr
ide should then
be moistened and compacted.
6) A rep
esentative of
the geotechnical engineer should observe all footing
excav
tions prior
concrete placement to evaluate bearing conditions.
FLOOR SLABS
115 112A
-5-
The natural on-site s
Als, excludi
ig topsoil, should be suitable for support of lightly
loaded floor slabs o
-grade. The
re could be slab movement if the subgrade becomes
wetted as discussed
bove. Prov
ding several feet of structural fill below the slabs would
act to reduce the risk
of floor slal
i movement. The settlement/heave potential of the
bearing soils and =
d for structural
fill should be further evaluated at the time of
•
construction.
M To reduce the effect
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 requij
ements for j
Dint spacing and slab reinforcement should be
• established by the dc
signer basec
on experience and the intended slab use. A minimum 4
inch layer of relatively
well grad
d 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 o
i the No. 4 sieve
and less than 12% passing the No. 200 sieve.
•
All fill materials placed
for support
of floor slabs should be compacted to at least 95% of
• maximum standard
Proctor density
at a moisture content new optimum. Required fill can
consist of the onsite
oils devoid
of vegetation and topsoil.
UNDERDRAIN SY
TEM
•
It is our understanding
the finished
d floor elevation at ground level will be at or above the
surrounding grade wid
that craw
space grade will be shallow, on the order of 3 feet below
•
existing grade. The
fore, a foundation
drain system is not required provided surface
grading and drainage
is properly
constructed as recommended below. It has been our
•
experience in the ar
a that local
perched groundwater can develop during times of heavy
precipitation or seasonal
rano££
Frozen ground during spring runoff can create a perched
condition. We recut
end belo
-grade construction, such as retaining walls or deep
crawlspace or basen
ent, be protf
cted from wetting and hydrostatic pressure buildup by
•
an underdrain and w
ffl drain sys
em.
•
•
Job No. 115 112A
C-.t'9taC h
5) Land
caping which
-6 -
If the finished floc,
elevation of
the proposed structure has a floor level below the
surrounding grade,
we should I
e contacted to provide recommendations for an underdrain
cause
I by irrigation.
system. All earth
claiming stractures
should be properly drained.
LIMITATIONS
SURFACE DRAD
AGE
This study has been
onducted in
accordance with generally accepted geotechnical
Positive surface dr
'nage is an important
aspect of the project to prevent wetting of the
bearing soils. The
following dr
iinage precautions should be observed during construction
and maintained at all
times Met
the residence has been completed:
1) Inun
Jation of thE
foundation excavations and underslab areas should be
avoi
ed during c
instruction.
2) Exte
ior backfill
hould be adjusted to near optimum moisture and
compacted
to at least
95% of the maximum standard Proctor density in
pave
nent and sla
b areas and to at least 90% of the maximum standard
Proc
or density it
landscape areas.
3) The
ground surfa
a surrounding the exterior of the building should be
slopt
d to drain at
fay from the foundation in all directions. We
teem
end a mil
imum slope of 12 inches in the first 10 feet in unpaved
areas
and a minin
turn 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
5) Land
caping which
requires regular heavy irrigation should be located at
least
10 feet from
foundation walls. Consideration should be given to use
of xei
'scape to reduce
the potential for wetting of soils below the building
cause
I by irrigation.
LIMITATIONS
This study has been
onducted in
accordance with generally accepted geotechnical
engineering principit
s and practices
in this area at this time. We make no warranty either
express or implied.
he conclusi
ns and recommendations submitted in this report are
based upon the data
btained fror
i the exploratory borings drilled at the locations
indicated on Figure 1
the proposed
type of construction and our experience in the area.
115 I12A
se'x�
Steven L. Pawlak P.
y
r $
_ Reviewed by:��
Daniel E. Hardin, P. .
SLP/ksw
cc: Wester, Inc. Stephen Kesler (westu@rof.net
Job No. 115 112A
-7 -
Our services do not
include dete
mining the presence, prevention or possibility of mold or
other biological con
aminants (
OBC) developing in the future. If the client is
concerned about M
BC, then a
rofessional in this special field of practice should be
consulted. Our find
ngs include
interpolation and extrapolation of the subsurface
conditions identifiec
at the expl
ratory borings and variations in the subsurface
conditions may not I
iecome evid
mit until excavation is performed. If conditions
encountered during
onstruction
appear different from those described in this report, we
should be notified so
that re-eval
uation of the recommendations may be made.
This report has been
prepared foi
the exclusive use by our client for design purposes. We
are not responsible
r technical
interpretations by others of our information. As the
project evolves, we
hould provide
continued consultation and field services during
construction to revic
w and monitor
the implementation of our recommendations, and to
verify that the recon
endations
have been appropriately interpreted. Significant design
changes may require
additional analysis
or modifications to the recommendations
presented herein.
recommend
on-site observation of excavations and foundation
bearing strata and to
ting of stru
total fill by a representative of the geotechnical
engineer.
Respectfully Submit
ed,
HEPWORTH - PAV
FLAK GEQMLHNICAL,
INC.
se'x�
Steven L. Pawlak P.
y
r $
_ Reviewed by:��
Daniel E. Hardin, P. .
SLP/ksw
cc: Wester, Inc. Stephen Kesler (westu@rof.net
Job No. 115 112A
APPROXIMATE SCALE
1"=50'
COUNTY 60AD 216
/ C BORING 1
(HP GEOTECH
\ JOB NO. 100169
LOT 25 I v v 3/28/2000)
OT 27
i
/ BENS
BORING 2
/ / I
/ / I
BORING 1
SOUTH MEADOW CIRCLE
0
O
0
D
0
O
116136A I u_I ILOCATION OF EXPLORATORY BORINGS I Figure 1
BORING 1
BORING 2
2
14/12
WC -6,5
=5.6
DD -109
97
-200=44
2
14/12
-4.4
WC=4.6
108
DD=103
`46
-200=50
17/12
4.5
132
112
M
5
10
15
20
25
30
35
Note: Ixplanation o symbols is shown on Figure 3.
ech LOGS OF EXPLORATORY BORINGS Figure 2
b
LEGEND:
ration test (SI
®
TOPSOIL; organic sandy silt
ind clay, f
required to drive the Californi
sampler 12
NOTES:
SILT AND CLAY (ML -CL); sar
dy to very
2. The exploratory boring locations wE
plasticity.
provided.
3. The exploratory boring elevations w
re not meas
4. The exploratory boring locations should
be consi
SAND (SM); silty to very silty,
catered
n the explon
material types and transitions may it
layers.
6, No free water was encountered in t
e borings at t
_
7. Laboratory Testing Results:
stiff to very stiff, slightly moist, light brown to brown, low
to gravelly, medium dense, slightly moist, brown, some sandy silt
Relatively undisturbed drives mple; 2 -inch II.D. California liner sample.
13/8 inch I.D. split spoon sample, ASTM -1586,
vs of a 140 pound hammer falling 30 inches were
6 with a 4 -inch diameter continuous flight power auger.
xoximately by pacing from features shown on the site plan
J and the log of exploratory borings are drawn to depth.
ed accurate only to the degree implied by the method used.
ry boring logs represent the approximate boundaries between
time of drilling. Fluctuation in water level may occur with time
116 136A I uc I LEGEND AND NOTES I Figure
■ Drive sample; standard penel
ration test (SI
39/12 Drive sample blow count; indi
mtes that 39
required to drive the Californi
sampler 12
NOTES:
1. The exploratory borings were drillec
on April 27,
2. The exploratory boring locations wE
re measured
provided.
3. The exploratory boring elevations w
re not meas
4. The exploratory boring locations should
be consi
5. The lines between materials shown
n the explon
material types and transitions may it
a gradual.
6, No free water was encountered in t
e borings at t
_
7. Laboratory Testing Results:
WC = Water Content (%)
DD = Dry Density (pcf)
_
-200 = Percent passing No. 200 si
13/8 inch I.D. split spoon sample, ASTM -1586,
vs of a 140 pound hammer falling 30 inches were
6 with a 4 -inch diameter continuous flight power auger.
xoximately by pacing from features shown on the site plan
J and the log of exploratory borings are drawn to depth.
ed accurate only to the degree implied by the method used.
ry boring logs represent the approximate boundaries between
time of drilling. Fluctuation in water level may occur with time
116 136A I uc I LEGEND AND NOTES I Figure
Moisture Content = 5.6 percent
Dry Density = 97 pcf
Sample of: Sandy Silt
0 From: Boring 1 at 2y Feet
2
Compression
4 upon
wetting
6
c
0
N
m g
E
E
o
U
10
12
14
0.1 1.0 10
APEU PRESSURE -ksf 100
116136A [
TION TEST RESULTS I Figure 4
A LIED PRESSURE -ksf 10 100
116136A ~
.ak s� o SWELL -CONSOLIDATION TEST RESULTS Figure 5
Moisture
Content
= 4.6
percent
Dry
Density
=
103
Oct
Sample
of:
Very
Sandy Silty
Clay
From:
Boring
2 at 5 Feet
fEppan;lon
A LIED PRESSURE -ksf 10 100
116136A ~
.ak s� o SWELL -CONSOLIDATION TEST RESULTS Figure 5
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