HomeMy WebLinkAboutSoils Report 12.11.2015HEPWORTH-PAWLAK GEOTECHNICAL
December 11, 2015
Richard Sierzant
P.O. Box 322
Snowmass, Colorado 81654
fishpoland @ gmai l.com
Subject:
Dear Richard:
k c1 vnrth-Paw1;i1 Geotechnical, Inc
5020 County Road 154
Gler wcxxl Springs, Colorado 81801
Phone. 970.945-7938
Fax 970.945.8454
email hpgco@hpgeorech.com
OCT 052017
Job No. 115 577A
Update of Previous Subsoil Study Report, Proposed Residence, Lot 57,
Cerise Ranch, 18 Sunflower Loop, Garfield County, Colorado
As requested, Hepworth-Pawlak Geotechnical, Inc. visited the site on December 10, 2015
and is providing this update of the previous subsoil study report for the subject site dated
July 17, 2006, Job No. 106 0466. The services were performed in accordance with our
agreement for professional engineering services to you dated December 9, 2015.
The proposed residence will consist of a one and two story structure with an attached
garage. The main floor of the house and the garage floor will be slab -on -grade. The main
floor will be about 824 square feet and the upper level will be about 250 square feet. The
house will be located in the northeast part of the building envelope, closest to the street.
At the time of our visit to the site, the lot was vacant and vegetated with grass and weeds
with patches of snow cover and appeared similar to the previous site conditions describe
in the 2006 report.
Considering the conditions observed at the site and our understanding of the proposed
construction, the previous subsoil study report can be used for design of the new
residence. An underdrain system is not needed and should not be installed around the
building perimeter. Shallow spread footing foundations placed on the natural clay soils
should be designed for an allowable soil bearing pressure of 1,200 psf as previously
recommended. As an alternative with a low settlement risk, the footing bearing level
could be extended down to the dense gravel soils (with excavation dewatering as needed)
and designed for an allowable bearing pressure of 3,000 psf. Other recommendations
presented in our previous report which are applicable should also be observed.
Parker 303-841-7119 • Colorado Springs 719-633-5562 • Silverthorne 970-468-1989
Richard Sierzant
December 11, 2015
Page 2
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.
If you have any questions or need further assistance, please call our office.
Sincerely,
HEPWORTH — PAWLAK GEOTECHNICAL, INC.
Daniel E. Hardin, P.E.
Rev. by: SLP
DEH/ksw
AD
Attachment: Subsoil Study for Foundation Design, Proposed Residence, Lot 57, Cerise
Ranch, Garfield County, Colorado dated July 17, 2006, Job No. 106 0466.
cc: Pamela Sudmeier pang @ s Lid me is Leon)
Job No, 115 577A
HEPWORTH - PAWLAK GEOTECHNICAL
Hepwarth•Pawlak Geotcchnlcai, Inc.
5020 Counry Road 154
Glenwood Springs, Colorado 31601
Phone: 970-945-7988
Fax: 970-945-6454
email: hpgeo®hpgeoteth,com
SUBSOIL STUDY
FOR FOUNDATION DESIGN
PROPOSED RESIDENCE
LOT 57, CERISE RANCH
GARFIELD COUNTY, COLORADO
JOB NO.. 106 0466
JULY 17, 2006
PREPARED FOR:
KELLY BELANY
P.O. BOX 8884
ASPEN, COLORADO 81612
Parker 303-841-7119 • Colorado Springs 719-633-5562 • Silverrhorne 970-468-1989
TABLE OF CONTENTS
PURPOSE AND SCOPE OF STUDY -1-
PROPOSED CONSTRUCTION - 1 -
SITE CONDITIONS - 2 -
SUBSIDENCE POTENTIAL - 2 -
FIELD EXPLORATION - 3
SUBSURFACE CONDITIONS - 3 -
DESIGN RECOMMENDATIONS - 4 -
FOUNDATIONS -4-
FLOOR SLABS - S -
UNDERDRAIN SYSTEM - 6 -
SURFACE DRAINAGE - 6 -
LIMITATIONS - 7 -
FIGURE 1 - LOCATION OF EXPLORATORY BORINGS
FIGURE 2 - LOGS OF EXPLORATORY BORINGS
FIGURE 3 - LEGEND AND NOTES
FIGURE.4 - SWELL -CONSOLIDATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
PURPOSE AND SCOPE OF STUDY
This report presents the results of a subsoil study for a proposed residence to be located at
Lot 57, Cerise Ranch, 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 May 12, 2006.
• 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 or swell 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. proposed residence will be a one story wood frame structure over a crawlspace with
an attached garage. Garage floor will be slab -on -grade. Grading for the structure is
assumed 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 from those described
above, we should be notified to re-evaluate the recommendations contained in this report.
Job No. 106 0466
G iertech
-2 -
SITE CONDITIONS
The site is Located on the west side of Sunflower Loop and vacant of structures.
Vegetation consists of grass and weeds. There is a landscaping berm along the north
property line with Lot 56. The ground surface is relatively flat with a slight slope down to
the southwest. Elevation difference across the building area is about one foot.
SUBSIDENCE POTENTIAL
The Eagle Valley Evaporite underlies the project area and outcrops on the valley sides
north and south of the site. It consists of gray and tan, gypsum and anhydrite with
interbedded siltstone, claystone, and dolomite. The gypsum and anhydrite are. soluble in
fresh water. The siltstone and claystone vary from cemented and hard to non-cemented
but firm. The dolomite is cemented and hard. The bedding structure is convoluted
because of flow deformation in the plastic gypsum and anhydrite. Joints are commonly
present in the siltstone and dolomite. Because of their plasticity, the gypsum and
anhydrite are massive and have no joints. Due to the soluble nature of gypsum and
anhydrite, subsurface voids and sinkholes are sometimes present in areas underlain by the
Eagle Valley Evaporite in western Colorado.
Sinkholes have been mappedin the Cerise Ranch Subdivision. Evidence of sinkholes
were not observed on the subject property or encountered in the borings during our study.
However, the presence of the Eagle Valley Evaporite beneath the project area indicates
that there is a potential for subsurface voids at the project site. It is our opinion that the
potential for subsurface voids below the site is low and similar to other lots in the area.
The site can be developed as proposed with a relatively low risk of future ground
subsidence throughout the service life of the project. If additional evaluation of potential
subsidence at the project site is desired, we should be contacted.
Job No. 106 0466 Gastech
FIELD E32LORATION
The field exploration for the project was conducted on June 16, 2006. Two exploratory
borings were drilled at the locations shown on Figure 1 to evaluate the subsurface
conditions. The borings were advanced with 4 inch diameter continuous flight augers
powered by a truck mounted CME -45B drill rig. The borings.were logged by a
representative of Hepworth-Fawlak Geotechnical, Inc.
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 Logs of Exploratory Borings,
Figure 2. The samples were returned to our laboratory for review by the project engineer
and testing.
SUBSURFACE CONDITIONS
Graphic logs of the subsurface conditions encountered at the site are shown on Figure 2.
The subsoils below about one foot of topsoil consists of sandy silty clay overlying sandy
gravel with cobbless. Drilling in the dense granular soils with auger equipment was
difficult due to the cobbles and boulders and drilling refusal was encountered in the
deposit.
Laboratory testing performed on samples obtained from the borings included natural
moisture content and density. Results of swell -consolidation testing performed on
relatively undisturbed drive samples, presented on Figure 4, indicate low to moderate
compressibility under conditions of light loading and wetting. The laboratory testing is
summarized in Table 1.
Job No. 106 0466
-4 -
Free water was encountered at depths of 6 to 7% feet in the borings at the time of drilling
and when checked 12 days later. Slotted PVC pipe was placed in -the borings to monitor
the groundwater levels. The upper subsoils were riroist to very moist.
DESIGN RECOMMENDATIONS
FOUNDATIONS
Considering the subsurface conditions encountered in the exploratory borings and the
nature of the proposed construction, we recommend the building be founded with spread
footings bearing on the natural soils.
The design and construction criteria presented below should be observed for a spread
footing foundation system.
1) Footings placed on the undisturbed natural clay soils should be designed
for an allowable bearing pressure of 1,200 psf. Footings bearing on the
gravel soils should be designed for an allowable soil bearing pressure of
3,000 psf. Based on experience, we expect settlement of footings designed
and constructed as discussed in this section will be about 1 inch or less.
Potential settlement can be limited by placing all footings of the gravel
subsoils although dewatering the excavation may be necessary for
construction in thy conditions.
2) The footings should have a minimum width of 18 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 least 36 inches below exterior grade is
typically used in this area.
Job No. 106 0466 Ggertech
-5-
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 lateral earth pressure corresponding to an equivalent
fluid unit weight of at least 5.0 pcf.
5) All existing topsoil and any loose or disturbed soils should be removed and
the footing bearing level extended down to relatively undisturbed soils.
The exposed soils in footing area should then be moistened and
compacted. .If water seepage is encountered, the footing areas should be
dewatered before concrete placement.
6) A representative of the geotechnical engineer should observe all footing
excavations prior to concrete placement to evaluate bearing conditions.
FLOOR SLABS
The natural on-site 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 colmmrim 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 free -draining gravel should be placed beneath
basement leve] slabs 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 2% 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 can
consist of the on-site granular soils or a suitable imported granular material devoid of
vegetation, topsoil and oversized rock.
Job No. 106 0466
-6-
UNDERDRAIN SYSTEM
Although free water was encountered below the expected crawlspace grade during our
exploration, it has been our experience in the area that local perched groundwater can
develop during times of heavy precipitation or seasonal runoff. Frozen ground during
spring runoff can create a perched condition. We recommend below -grade construction,
such as retaining walls and crawlspace areas, be protected from wetting and hydrostatic
pressure buildup by an underdrain system. A shallow crawlspace (less than 3 feet) should
not require an underdrain provided the exterior backfin is properly compacted and
graded.
If installed, the drains should consist of drainpipe placed in the bottom of the wall -backfill
surrounded above the invert level with free -draining granular material. The drain should
be placed at each level of excavation and at least 1 foot below lowest adjacent finish
grade and sloped at a minimum 1% to a suitable gravity outlet, drywell or sump and
pump. Free -draining granular material used in the underdrain system should contain less
than 2% passing the No. 200 sieve, less than 50% passing the No. 4 sieve and have a
maximum size of 2 inches. The drain gravel backfill should be atJeast 1'/z feet deep.
SURFACE DRAINAGE
The following drainage precautions should beobserved during construction and
maintained at all times after the residence has been completed:
1) Inundation of the foundation excavations and underslab areas. should be
avoided during construction. .
2) Exteriorbac16.11 shouldbe adjusted to near optimum moisture and
compacted to at least 95% of the na.axi_mum standard Proctor density in
pavement and slab areas and to at least 90% of the maximum standard
Proctor density in landscape areas.
Job No. 106 0466 &griech
-7-
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 10 feet in paved areas.
Free -draining wall backfill (if any) should be capped with about 2 feet of
the on-site soils to reduce surface water infiltration.
4) Roof downspouts and drains should discharge well beyond the limits of all
backfill.
LIMITATIONS
This study bas been conducted in accordance with generally accepted geotechnical
engineering principles and practices in this area at this time. We snake no warranty either
express or implied. The conclusions and recommendations submitted in this report are
based upon the data obtained from the exploratory borings drilled at the locations
indicated on Figure 1, the proposed type of construction and our experiencein the area.
Our services do not include determining the presence, prevention or possibility of mold or
other biological contaminants (MOBC) developing in the future. I£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 borings and variations in the subsurface
ti
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.
Job No. 106 0466
Gatech
-8 -
Significant design changes may require addili.onal analysis or modifications to the
recommendations presented herein. We recommend on-site observation of excavations
and foundation bearing Strata and ting of structural fill by a iepresentative of the
geotechnical engineer.
Respectfully Submitted,
HEPWORTH - PAWLAK GEOTECHNICAL, INC.
Louis E. Eller
Reviewed by:
Daniel E Hardin, P.E.
LEE/vad
cc: Enrique Bienkowski (fax only)
Yob No. 106 0466
SUNFLOWER LOOP
HP GEOTECH r
JOB NO. 103 243 1
LOT 56 1
1
If r--, l
1 1 1 • 1 i
11 BORING 11
LOT 58
1 1
II BUILDING 1
1j ENVELOPE 1
1 l
I ■ 11
11 BORING 2
LOT 57
IRRIGATION DITCH
EASEMENT
APPROXIMATE SCALE
1"=100'
106 0466
tionvown+PAw{.mc GIKUMC217,11CAL
LOCATION OF EXPLORATORY BORINGS
Figure 1
0
— 10
15
106 0466
BORING 1
5/12
WC=15,1
Oa -s7
5/12
16/5
12
BORING 2
4/12
WC=a6.o
DD.85
13/4
Note: Explanation of symbols Is shown on Figure 3.
LOGS OF EXPLORATORY BORINGS
5
10
15
li
a.8
Figure 2
LEGEND:
® TOPSOIL; organic sandy silt and clay, moist, dark brown.
CLAY (CL); sandy, silty, soft, moist to vety,moist, brown.
GRAVEL (GC); clayey, sandy, with cobbles and possible small boulders, medium dense to dense, wet, brown,
subangular rocks.
Relatively undisturbed drive sample; 2 -Inch LD. California liner sarnple.
r r
r_.
5/12
0,12
T
—�--7
Drive sample; standard penetration test (SPT),1 3/8 Inch I.D. split spoon sample, ASTM 0-1586.
Drive sample blow count; Indicates that 5 blows of a 140 pound hammer falling 30 inches were
required to drive the California or SPT sampler 12 inches.
Free water level in boring and number of days following drilling measurement was taken.
Practical drilling refusal. Where shown above bottom of log, indicates that multiple attempts were
made to advance the boring.
Indicates slotted PVC pipe installed In boring to depth shown.
NOTES:
1. Exploratory borings were drilled on June 16, 2006 with 4 -Inch diameter continuous flight power auger.
Z Locations of exploratory borings were measured approximately by pacing from features shown on the site plan
provided.
3. Elevations of exploratory borings were not measured and the logs of exploratory borings are drawn to depth.
4. The exploratory boring locations should be considered accurate only to the degree Implied by the method used.
5. The lines between materials shown on the exploratory boring Togs represent the approximate boundaries between
material types and transitions may be gradual.
6. Water level readings shown on the logs were made at the time and under the conditions Indicated. Fluctuations In
water level may occur wfth time.
7. Laboratory Testing Results:
WC Water Content (%)
DD W Dry Density (pcf)
106 0466
HIrPwORTlFPAwurc GotfrkC14arm.
LEGEND AND NOTES
Figure 3
ae
C
N
5g
0
•
1
a
E
8 2
3
Moisture Content = 15.1 percent
Dry Density = 97 pcf
Sample of: Sandy Clay
From: Boring 1-at.3 Feet
Expansion
upon
wetting
0.1
0
1
2
3
4
a
m
to
5
E
U
6
7
8
1.0 10
APPLIED PRESSURE - ksf
100
Moisture Content = 36.0 percent
Dry Density = 85 pcf
Sample of: Sandy Silty Clay
From: Boring 2 at 3 Feet
Compression
upon
wetting
0.1
106 0466
1.0 10
APPLIED PRESSURE - ksf
HEl*wo i, PR►n.711C GeO7eergtl C.Ai
SWELL -CONSOLIDATION TEST RESULTS
100
Figure 4
HEPWORTH-PAWLAK GEOTECHNICAL, INC.
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Job No. 106 0466
• SAMPLE LOCATION
NATURAL
MOISTURE
CONTENT
NO
NATURAL
GRADATION
PERCENT
ATTBERG LIMITS i
FR
UNCONFINED
COMPRESSIVE
STRENGTH
(PSF)
r
SOIL OR
BEDROCK TYPE
BORING
DEPTH
(It)
DRY
DENSI Y(
(acf)
GRAVEL
)
SAND
(%)
PASSING
t O. 200
SIEVE
LIQUID
UM1T
(%)
PLASTIC
INDEX
(%)
1
3
15.1
97
Sandy Clay
2 .
3
36.0
85
Sandy Silty Clay
T
1-
Dave Argo
From: richard sierzant <ceriseranch57@gmail.com>
Sent: Thursday, October 05, 2017 2:47 PM
To: Dave Argo
Subject: Fwd: Update of Previous Report for Lot 57, Cerise Ranch (#115 577A)
Attachments: 115577A (12-11-15) Update signed.pdf
Dave,
Below you'll find the soils report. This report was for the previous design referenced. Spoke with H -P Geo and
they indicated this report will easily accommodate the new design which I've submitted for your approval.
Appreciate your time and consideration. Thanks.
Richard Sierzant
Forwarded message
From: richard sierzant <ceriseranch57@gmail.com>
Date: Wed, May 10, 2017 at 3:43 PM
Subject: Fwd: Update of Previous Report for Lot 57, Cerise Ranch (#115 577A)
To: jeff.holmesexc@gmail.com
Forwarded message
From: Lena Galliher <lenag@hpgeotech.com>
Date: Wed, Feb 10, 2016 at 3:32 PM
Subject: Update of Previous Report for Lot 57, Cerise Ranch (#115 577A)
To: ceriseranch57@gmail.com
grnail.corn
Richard, attached is the report you requested.
Lena Fowlkes
Administrative Assistant
Ienaqah pgeotech.com
HP Geotech, Inc.
5020 County Road 154
Glenwood Springs, CO 81601
(970) 945-7988 - Office
(970) 945-8454 - Fax
1