HomeMy WebLinkAboutObservation of Excavation 04.17.2023Open Hole Soils Report
Page 1
April 17, 2023
Mr. Tony Zarlingo
RE: Open Hole Soils Report per Garfield County Permit Requirement
Dear Tony,
The purpose of this report is to provide on-site, open hole confirmation that foundation subsoils
will support the foundation system as designed for the proposed residence to be constructed at:
. PhysicalAddress 0231 County Road, Garfield County, Silt, Colorado.. Legal Description Lot 1 of the Dunsdon Minor Subdivision, Section 3, Township 6,
Range 92.o Building Permit No. 7931
Design: The approved foundation system design is based on:
The bearing soils being clayey sand (sc) having a load bearing capacity of 2,000 pounds
per square foot (psf).
Twelve inch over excavation of foundation soils and replacement with well graded gravel
(gw), bearing capacity of 3,000 psf.
Use of the lower bearing capacity associated with sc soils for design of the foundation
system.
Findings: On 411712023 an open hole soil evaluation on foundation subsoils for the above
referenced site was conducted by me. Soils collected from two test locations, shown on figure
1, were examined using the soil texture by feel method for soil classification, Sampling of soils
from test locations indicate the soils:
. Remain in a ballwhen squeezed.. Form a ribbon between 1 to 2 inches or more. Feel very smooth when wet.. Classify as scl (silty clay loam) or sc.
As a check for the suitability of the foundation subsoils, a flexible analysis was conducted for the
composite sc/gw subsoils. The r value for sc soils is 10-20, for gravel is 20-80. Using the lower
r value for each subgrade classification results in a composite k value of 208 pci (pounds per
cubic inch), when the gravel layer has a thickness of 12 inches. The k value is a soil property
related to how the soil reacts to load. Values of k in the range of 200 pci and upward indicate
good soilsupport.
Recommendations: Based on the open hole site conditions, the following is recommended
o The maximum soil bearing capacity of 2,000 psf is acceptable.. Although there was no unusual moisture or water present, a foundation drain should be
installed as indicated on the approved drawings.o The approved design spread footing foundation system shown on sheet S3, revision 2
should be used.
a
a
a
Open Hole Soils Report
Page 2
Conclusion; The subsoils will provide sufficient support for the approved foundation system
design shown on sheet 53, Foundation Plan, dated 0811612022, revision #2 dated 0112612023,
stamped and signed on 0112612023
Respectfully,
\¿ .Í) &^*/__,e¡J aø*'t-<* A' /,
Terry Bendetti, P.E. No.56930
Enclosures:Figure 1
Soil Texture by Feel- Test Pit 1
Soil Ribbon Photo - Test Pit 1 Soils
Soil Texture by Feel- Test Pit 2
Soil Ribbon Photo - Test Pit 2 Soils
Composite k-Value
tlr lt
$ü 3$
/r"o,16u()EXIST. FlBEROPTlCSPEDESTALExtsr.TELEPH.ONEPEDESTALFigure 1
! t-Jlt *!
Sail Texture by Feel Doesthesoi$ remai* ün a ba$$ whe$\ squ*wr*dl
Ybs
consistenry, lik* moist
putty.
Àdd dry soil
Ves
s the soi*too wet?
Ns
Place ball of *oil ktxeen
a
$ùsùd sû {lS$À $KS tuidr 5. J-r9r9,
Flace soll in palm of hand. Add water drop-wise
and kne¡d the sail into a smooth and plastic
N*
il
Hil
I
Ëß
I
?
ü
Ådd water
ls the so*l too dnyT
Ybs
Na
the soil form a ribbon?
No
Does soilfeel verygritty? yes
Nc
Þoas soll fecl very srnoath? Ye*
Nçr
F,teither gritty ncr snooth? y*s
Forms a weak
ribbon less
than l"before
breaking
:ilu
tormsaT-2"
ribbsn before
breaklng
ng
5A
?"totr
hí5{èdìtir* r{eèttd*S H¡xiro¡r,ü9r$${ìS $rswn, S lsRs.
Soil Ribbon Pnoto - Test Pit I Soils
! ry*H
Soll Texture by Fsel Ðoes th* sst$ rem*$sx $n s h¡$$ when squeeeedl
\i*s $è*
consistency, like moist Ådd water Ådd d ty s**$
Putty.
Place ball of soil between thumb and forefinger,
å*¡rd ç$üSåS*tSGu¡ds tol{Ë1il¡s by frd - 5. !.t9t9,
Place soil in palm of hand. Ádd water drop-wise
and knead the soil into a smooth and plastic
ËN
ls thr s*il too dryï
Ncs
hi'¡
the soiltco wet?
Yes
No
No
the soil form a ribbon?
Does ¡cll fesl very grittyl Yes
N*
Ðtes soil feel veryr srnooth? Yes
${e
Nelthm gritty $or r*loothT Y*s
Forrns a weak
ribbon less
than l"before
breaking
,r[$ ,ww*r
Formsêì*2"
ribbon before
breaking
5A
2'or
lþi$vÀd¡tþn ea.¡ite.d ty I l{¡nis{ììì, À{S$u,*.ly BrêwÂ, R lè\¡3,r::::: = .r- =.,::1 .,,,S S*ttgo*t*n*,S;., ,,= := ..::::_
Soil Ribbon Photo - Test Pit 2 Soils
Soil Resistance Value for sandy clay = R5ç =
Soil Resistance Value for gravel = RGR =
Resilient Modulus for sandy cla! = M¡56 =
Resilient Modulus for gravel = MRsG =
k-Value corresponding to sandy clay M*s6 =
k-Value corresponding to gravel Mnse =
Composite k-Value =
Composite k-Value
3,054
4305
10
20
pct
pci
pci
to
to
to
to
to
to
to
20
80
psi
psi
pci
pci
pci
LO4
605
268
75
704
208
pst
ps¡
4305
33815