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HEPWORTH-PAWLAK GEOTECHNICAL
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PRELIMINARY GEOTECHNICAL STUDY
PROPOSED TCI LANE RANCH SUBDIVISION
HIGHWAY 82 AND EAST OF COUNTY ROAD 100
GARFIELD COUNTY, COLORADO
JOB NO. 106 0920
MARCH 14, 2008
PREPARED FOR:
TCI LANE RANCH, LLC
C/O NOBLE DESIGN STUDIO
ATTN: JON FREDERICKS, ASLA
19351 HIGHWAY 82
CARBONDALE, COLORADO 81623
1- 7 1 1 c1 e Cr iInl ido
TAME OF CONTENTS
PURPOSE AND SCOPE OF- STUDY - 1 -
SITE CONDITIONS 1 -
REGIONAL GEOLOGIC SETTING - 2 _
PROJECT SITE GEOLOGY _ 3 -
RIVER TERRACES AND DEPOSITS - 4 -
EAGLE VALLEY EVAPORITE - 4 -
GEOLOGIC SITE ASSESSMENT - 5 -
RIVER FLOODING - 5 -
SINKHOLES - 5 -
EAR TTTQUAKE CONSIDERATIONS - 6 -
RADIATION POTENTIAL - 7 -
FIELD EXPLORATION - 8 -
SUBSURFACE CONDITIONS - 8 -
PRELIMINARY DESIGN RECOMMENDATIONS - 8 -
FOUNDATIONS - 9 -
BELOW GRADE CONSTRUCTION 9
FLOOR SLABS _ 9 -
SURFACE DRAINAGE - 10 -
PAVEMENT SECTION - 10 -
LIMITATIONS - 10 -
REFERENCES - 12 -
FIGURE 1 - PROJECT SITE LOCATION
FIGURE 2 - GEOLOGICALLY YOUNG FAULTS AND LARGER HISTORIC
EARTHQUAKES
FIGURE 3 - WESTERN COLORADO EVAPORITE REGION
FIGURE 4 - PROJECT AREA GEOLOGY MAP
FIGURE 5 - LOCATION OF EXPLORATORY PITS
FIGURE 6 - LOGS OF EXPLORATORY PITS
FIGURE 7 - LEGEND AND NOTES
FIGURE 8 - SWELL -CONSOLIDATION TEST RESULTS
FIGURES 9, 10, 11 & 12 .. GRADATION TEST RESULTS
TABLE 1- SUMMARY OF LABORATORY TEST RESULTS
PURPOSE AND SCOPE OF STUDY
This report presents the results of a preliminary geotech.nical study for the proposed
residential subdivision at TCI Lane Ranch located north of the Roaring Fork River and
east ofthe Blue Creek Ranch Subdivision, Garfield County, Colorado. The project site is
shown on Figure 1. The purpose of the study was to evaluate the geologic and subsurface
conditions and their potential impact on the project. The study was conducted in
accordance with our proposal for geotechnical engineering services to TCI Lane Ranch,
LLC, dated December 20, 2007. We previously conducted percolation testing for a septic
system design on the property and presented our findings in a report dated October 31,
2006, Job No. 106 0920.
A field exploration program consisting of a reconnaissance and exploratory pits was
conducted to obtain information on the site and 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 project planning and preliminary design. This report summarizes
the data obtained during this study and presents our conclusions and recommendations
based on the proposed development and subsurface conditions encountered.
SITE CONDITIONS
The TCI Lane Ranch covers about 100 acres and is located in the Roaring Fork River
valley about three and one-half miles upstream of Carbondale, see Figure 1. The
property lies to the north ofthe river and is entirely on the nearly level valley floor. The
valley floor has an average slope of about 2 percent down to the west. It is made up of
several river terrace levels that are separated by low escarpments. The escarpments are
typically about 6 to 20 feet high and have slopes of about 50 to 70 percent. The terrace
surfaces lie between about 4 to 46 feet above the river. The Frontage Road for Highway
82 is located along the northern property line. Parts of the southern property line are in
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the Roaring Fork River channel. The Blue Creek Subdivision borders the property on the
west and rural homes and agricultural land are located on the properties to the east. At
the time of this study several houses and ranch buildings were located in the east -central
part of the TCI Lane Ranch. Much of the ranch is irrigated hay fields and pasture which
are located mostly on the higher terrace surfaces. Cottonwood trees, other trees and brush
are typical of the vegetation on the lower terraces. Poorly drained wetlands are also
present on the lower terraces.
PROPOSED DEVELOPMENT
The proposed development at the TCI Lane Ranch will be mostly a residential
subdivision as shown on Figure 4. A plant nursery will be located in the northwestern
part of the property. The lowest terraces along the river will not be developed and
undeveloped ground will remain along Highway 82. Eighty-nine residential lots are
proposed. Other development facilities will include a network of streets, a community
park and other community facilities.
If development plans change significantly from those described, we should be notified to
re-evaluate the recommendations presented in this report.
REGIONAL GEOLOGIC SETTING
The project site is in the Southern Rocky Mountains to the west of the Rio Grande rift and
to the east of the Colorado Plateau, see Figure 2. The site is in the western Colorado
evaporite region and is in the Carbondale collapse center, see Figure 3. The Carbondale
collapse center is the western of two regional evaporite collapse centers in western
Colorado. It is an irregular -shaped, northwest trending region between the White River
uplift and Piceance basin. It covers about 460 square miles. As much as 4,000 feet of
regional subsidence is believed to have occurred during the past 10 million years in the
vicinity of Carbondale as a result of dissolution and flowage of evaporite from beneath
the regions (Kirkham and Others, 2002). The evaporite is mostly in the Eagle Valley
Evaporite with some in the Eagle Valley Formation. The Eagle Valley Evaporite is the
near surface formation rock below the surficial soil deposits at the project site. It crops
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out on the steep valley side to the south ofthe river, see Figure 4. Much of the evaporite
related subsidence in the Carbondale collapse center appears to have occurred within the
past 3 million years which also corresponds to high incision rates along the Roaring Fork,
Colorado and Eagle Rivers (Kunk and Others, 2002). This indicates that long-term
subsidence rates have been very slow, between about 0.5 and 1.6 inches per 100 years. It
is uncertain if regional evaporite subsidence is still occurring or if it is currently inactive.
If still active these regional deformations because of their very slow rates should not have
a significant impact on the propose development at the TCl Lane Ranch.
Geologically young faults related to evaporite tectonics are present in the Carbondale
collapse center but considering the nature of evaporite tectonics, these fault are not
considered capable of generating large earthquakes. The closest geologically young
faults that are .less than about 15,000 years old and considered capable of generating large
earthquakes are located in the Rio Grande rift to the east ofthe project site, see Figure 2.
The northern section ofthe Williams Fork Mountains fault zone Q50 is located about 60
miles to the northeast and the southern section ofthe Sawatch fault zone Q56b is located
about 60 miles to the southeast. At these distances large earthquakes on these two
geologically young fault zones should not produce strong ground shaking at the project
site that is greater than the ground shaking shown on the U. S. Geological Survey 2002
National Seismic Hazards Maps (Frankel and Others, 2002).
PROJECT SITE GEOLOGY
The geology in the project area is shown on Figure 4. This map is based on our field
observations and is a modification of the regional geology map by Kirkham and
Widmann (1997). Near surface formation rock is the middle Pennsylvanian -age, Eagle
Valley Evaporite. This regional rock formation was deposited in the central Colorado
trough during the Ancestral Rocky Mountain orogeny about 300 million years ago. At
the project site the evaporite is covered by a series of Roaring Fork River terraces and
deposits that are associated with cyclic periods of deposition and erosion related to glacial
and interglacial climatic fluctuations during about the past 35 thousand years.
.lob No. 106 (1920
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RIVER TERRACES AND DEPOSITS
Remnants of seven river terrace levels (Qt 1 through Qt7) are present at the project site.
The lower four terraces are probably related to post-Pinedale climatic fluctuations during
the past 15 thousand years. Terrace Qt I lies within 4 feet of the river. Terrace Qt2 lies
about 6 feet above the river, terrace Qt3 lies about 12 feet above the river and terrace Qt4
is about 22 feet above the river. The Qt 1 ten -aces are small river bank terraces and
channel bar deposits. The Qt2 terraces are old abandoned river channels that lie below
the Qt3 terrace surface. The three higher terraces are probably associated with the late
Pleistocene -age, Pinedale glaciations between about 15 and 35 thousand years ago.
Terrace Qt5 lies about 38 feet above the river, terrace Qt6 lies about 40 feet above the
river and terrace Qt 7 lies about 46 feet above the river,
Our exploratory pits show that the alluvial deposits below terrace levels Qt3 through Qt7
are similar. They consist of a thin, less than 1-toot thick to 3-foot thick, topsoil formed in
soil, silty clay over -bank deposits. The over -bank deposits overlie river alluvium that
consists of rounded gravel- to boulder -size rocks in a relatively clean sand matrix. The
river alluvium extended to the bottom of the exploratory pits that were excavated to
depths of around 9 feet. Judging from water well records in the Colorado State
Engineer's data base the river alluvium is probably in the range of40 to 50 feet deep in
the project area.
EAGLE VALLEY EVAPORITE
The Eagle Valley Evaporite underlies the Roaring Fork River alluvium in the project area
and as discussed above may extend to depths of 40 to 50 feet below the terrace surfaces.
The Eagle Valley Evaporite is a sequence of evaporite rocks consisting of massive to
laminated gypsum, anhydrite, and halite interbedded with light-colored mudstone, fine-
grained sandstone, thin limestone and dolomite beds and black shale (Kirkham and
Widmann, 1997). The evaporite minerals are relatively soluble in circulating ground
water and subsurface solution voids and related surface sinkholes are locally present in
these rocks throughout the western Colorado evaporite region where the evaporite is near
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the surface, see Figure 3. Sinkholes were not observed at the project site during our field
work but the snow cover at that time may have obscured sinkholes if present.
GEOLOGIC SITE ASSESSMENT
Geologic conditions that could present an unusually high risk to the proposed
development were not identified by this study but there are geologic conditions that
should be considered in the project planning and design. These conditions, their potential
risks and possible mitigations to reduce the risks are discussed below. Geotechnical
engineering design considerations are presented in the Preliminary Design
Recommendations sect ion of this report.
RIVER FLOODING
The low lying terraces along the Roaring Fork River may be subject to periodic flooding
during high river flows. The hydrologic study conducted for the project storm water
management plan design should evaluate the potential for river flooding and possible
methods to protect project facilities from an appropriate design flood on the river.
SINKHOLES
Geologically young sinkholes are present in the western Colorado evaporite region
mostly in areas where the Eagle Valley Formation and Eagle Valley Evaporite are
shallow, see Figure 3. 1n this region a few sinkholes have collapsed at the ground surface
with little or no warning during historic times. This indicates that infrequent sinkhole
formation is still an active geologic process in the region. Evidence of sinkholes was not
observed at the project site during our field reconnaissance or aerial photographs review
but could have been obscured by the snow cover. A field review to look for sinkholes in
the proposed building area should be made after the site is clear of snow cover. Although
geologically active in the region , the likelihood that a sinkhole will development during a
reasonable exposure time at the project area is considered to be low. This inference is
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based on the large extent of sinkhole pronc areas in the region in comparison to the small
number of sinkholes that have developed in historic times.
Because of the complex nature of the evaporite related sinkholes, it will not be possible to
avoid all sinkhole risk at the project site. If conditions indicative of sinkhole related
problems are encountered during site specific soil and foundation studies for the houses
and other movement sensitive faculties, an alternative building site should be considered
or the feasibility of mitigation evaluated. Mitigation measures could include: (1) a rigid
mat foundation, (2) stabilization by grouting, (3) stabilization by excavation and
backfilling, (4) a deep foundation system or (5) structural bridging. Water features
should not he considered close to building sites, unless evaluated on a site specific basis.
The home owners could purchase special insurance to reduce their potential risks.
Prospective owners should be advised of the sinkhole potential, since early detection of
building distress and timely remedial actions are important in reducing the cost of
building repair should an undetected subsurface void start to develop into a sinkhole after
construction.
EARTHQUAKE CONSIDERATIONS
Historic earthquakes within 150 miles of the project site have typically been moderately
strong with magnitudes of M 5.5 and less and maximum Modified Mercalli Intensities of
VI and less, see Figure 2. The largest historic earthquake in the project region occurred in
1882. It was located in the northern Front Range about 115 miles to the northeast of the
project site and had a estimated magnitude of about M 6.2 and a maximum intensity of
VII. Historic ground shaking at the project site associated with the 1882 and the other
larger historic earthquakes in the region does not appear to have exceeded Modified
Mercalli Intensity VI (Kirkham and Rogers, 1985). Modified Mercalli Intensity VI
ground shaking should be expected during a reasonable exposure time for the houses and
other project facilities , but the probability of stronger ground shaking is low. Intensity
VI ground shaking is felt by most people and causes general alarm, but results in
negligible damage to structures of good design and construction.
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The houses and other facilities subject to earthquake damage should be designed to
withstand moderately strong ground shaking with little or no damage and not to collapse
under stronger ground shaking. For firm rock sites with shear wave velocities of 2,500
fps in the upper 100 feet, the U. S. Geological Survey 2002 National Seismic Hazard
Maps indicate that a peak ground acceleration of0.06g has a 10% exceedence probability
for a 50 year exposure time and a peak ground acceleration of 0.23g has a 2% exceedence
probability for a 50 year exposure time at the project site (Frankel and Others, 2002).
This corresponds to a statistical recurrence time of about 500 years and 2,500 years,
respectively. The soil profiles at the building sites should be considered as Class C, firm
rock sites as described in the 2006 International Building Code unless site specific shear
wave velocity studies show otherwise.
RADIATION POTENTIAL
Regional studies by the Colorado Geological Survey indicate that the closest radioactive
mineral occurrences to the project site are greater that twenty miles from the site
(Nelson -Moore and Others, 1978). Radioactive mineral occunrences are present in the
Aspen-Lenado mining district to the southeast and on the southwest flank of the White
River uplift to the northwest. :Regional studies by the U. S. Geological Survey (Dubiel,
1993) for the U. S. Environmental Protection Agency (EPA) indicate that the project site
is in a moderate radon gas potential zone. The 1993 EPA regional radon study considered
data from (1) indoor radon surveys, (2) aerial radioactivity surveys, (3) the general
geology, (4) soil permeability estimates, and (5) regional architectural practices. It is not
possible to accurately assess future radon concentrations in buildings before they arc
constructed. Accurate tests of radon concentrations can only be made when the buildings
have been completed. Because of this, new buildings in moderate to high radon areas are
often designed with provisions for ventilation ofthe lower enclosed areas should post
construction testing show unacceptable radon concentrations.
Job No. 106 0920
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FIELD F,XPLORATION
The field exploration for the project was conducted on January 10 and 15, 2008. Twelve
exploratory pits were excavated at the locations shown on Figure 5 to evaluate the
subsurface conditions. The pits were dug with a trackhoe and were logged by a
representative of Hepworth-Pawlak Geotechnical, Inc. Samples of the subsoils were
taken with relatively undisturbed and disturbed sampling methods. Depths at which the
samples were taken are shown on the Logs of Exploratory Pits, Figure 6. 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 6.
The subsoils consist of about 'A to 3 feet of organic topsoil overlying 2 feet of silty sand
in Pit 1 and relatively dense, silty sandy gravel containing cobbles and boulders in the
remaining pits. Pit 3 contained a lens of slightly gravelly sand from 4 to 5'/2 feet.
Laboratory testing performed on samples obtained from the pits included natural moisture
content and density and gradation analyses. Results of swell -consolidation testing
performed on a relatively undisturbed sample, presented on Figure 8, indicate moderate
compressibility under conditions of loading and wetting. Results of gradation analyses
performed on large disturbed samples (minus 3 to 5 inch fraction) of the natural coarse
granular soils are shown on Figures 9 through 12. The laboratory testing is summarized
in Table 1.
No free water was encountered in the pits at the time of excavation and the subsoils were
slightly moist.
PRELIMINARY DESIGN RECOMMENDATIONS
The conclusions and recommendations presented below are based on the proposed
development, subsurface conditions encountered in the exploratory pit, and our
experience in the area. The recommendations are suitable for planning and preliminary
design but site specific studies should be conducted for individual lot development.
Job No. 106 0920
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FOUNDATIONS
Bearing conditions will vary depending on the specific location of the building on the
property. Based on the nature of the proposed construction, spread footings bearing on
the natural granular soils should be suitable at the building sites. We expect the footings
can be sized for an allowable bearing pressure in the range of 1,500 psf to 3,000 psf.
Compressible silty sands encountered in building areas may need to be removed or the
footings designed accordingly as part of the site specific lot study. Nested boulders and
loose matrix soils may need treatment such as enlarging footings or placing compacted
structural fill. Foundation walls should be designed to span local anomalies and to resist
lateral earth loadings when acting as retaining structures. The footings should have a
minimum depth of 36 inches for frost protection.
BELOW GRADE CONSTRUCTION
Free water was encountered in some of the exploratory pits and it has been our experience
in the area that the water level can rise and local perched groundwater can develop during
times of seasonal runoff and heavy irrigation. In general, all below grade areas should be
protected from wetting and hydrostatic pressure buildup by use of an underdrain system.
We recommend that slab -on -grade floors be placed near to above existing grade and
crawlspaces be kept shallow. Basement leve.ls may not be feasible in the lower lying
areas with a shallow groundwater level. Potential groundwater impacts on proposed
development should be evaluated as part of the site specific building study.
FLOOR SLABS
Slab -on -grade construction should be feasible for bearing on the natural granular soils
below the topsoil. There could be some post construction slab settlement at sites with
compressible silts and sands. To reduce the effects of some differential movement, floor
slabs should be separated from all bearing walls and columns with expansion joints.
Floor slab control joints should be used to reduce damage due to shrinkage cracking. A
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minimum 4 inch thick layer of flee draining gravel should underlie building slabs to
break capillary water rise and facilitate drainage.
SURFACE DRAINAGE
The grading plan for the subdivision should consider runoff through the project and at
individual sites. Water should not be allowed to pond next to buildings. To limit
infiltration into the bearing soils next to buildings, exterior backfill should be well
compacted and have a positive slope away from the building for a distance of at least 10
feet, Roof downspouts and drains should discharge well beyond the limits of all backfill
and landscape irrigation should be restricted.
PAVEMENT SECTION
The near surface soils encountered in the exploratory pits below the topsoil typically
consisted of silty sandy gravel. The pavement section for the site access roads can be
taken as 3 inches of asphalt pavement on 8 inches of Class 6 aggregate base course for
preliminary design purposes. The subgrade should be evaluated for pavement support at
the time of construction, Subexcavation of the topsoil and fine-grained soils and
replacement with coarse granular subbase material may be needed to achieve a stable
subgrade in some areas.
LIMITATIONS
This study has been conducted according to 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 field reconnaissance, review of published geologic reports, the
exploratory pits located as shown on Figure .S and to the depths shown on Figure 6, the
proposed type of construction and our experience in the area. Our consulting services do
not include determining the presence, prevention or possibility of mold or other biological
contaminants (MO.BC) 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
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include interpolation and extrapolation of the subsurface conditions identified and the
exploratory pits 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 planning and
preliminary design purposes. We are not responsible for technical interpretations by
others of our information. As the project evolves, we should provide continued
consultation, conduct additional evaluations and review and monitor the implementation
of our recommendations. 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,
HEPWORTH - PAWLAK GEOTECHNLCAL, INC.
Scott W. Richards, E.I.
Reviewed by:
Steven L. Pawlak, P.E.
SWR/vad
Job No. 106 0920 Gagtedi
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REFERENCES
Dubiel, R. F., 1993, Preliminary Geologic Radon. Potential Assessment of Colorado in
Geologic Radon Potential EPA Region 8, Colorado, Montana, North Dakota,
South Dakota, Utah and Wyoming: U. S. Geological Survey Open File Report 93-
292-H.
Frankel, A. D. and Others, 2002, Documentation fbr the 2002 Update of the National
Seismic Hazard Maps: U. S. Geological Survey Open File Report 02-420.
Kirkham, R. M. and Rogers, W. P., 1985, Colorado Earthquake Data and Interpretations
1867 to 1985: Colorado Geological Survey Bulletin 46.
Kirkham, R. M. and Widmann, B. L., 1997, Geology Map of the Carbondale Quadrangle,
Garfield County, Colorado: Colorado Geological Survey Open File 97-3.
Kirkham, R. M. and Scott, R. B., 2002, Introduction to Late Cenozoic Evaporite
Lectonism and Volcanism in West -Central, Colorado, in Kirkham R. M., Scott, R.
Job No. 106 0920
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ICI Lane Ranch Project
Site Location
0
106 0920
Intermountain
Seismic Balt
Middle
Intermountain
t811 Seismic Belt
Rangely
Della]
Plateao
Cortez
T.
1
Explanation:
Post -Glacial Faults:
Fault younger than about 15,000 years.
Larger Historic Earthquakes:
Earthquakes with maximum intensity greater than VI
or magnitude greater than M 5,0 from 1867 to
present.
Nuclear Explosion:
Large underground nuclear explosion for natural gas
reservoir enhancement.
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1944
VI
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VI
Laramie Mtn.
1eb4
M 5.5
VI
Walden
L7
Vail
11
Eagle
, Project
Site Aspen
Cimarron Ridge Gunnison
1955
M 6.5
Durango 0
1866
VIIS'%
Lake CI
1955
VI
Pegosa Springs
a
N. Fran
1082
M 5.2
VII
Golden
Ci59a
009b
• Pr.
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Historic Seismic Zones:
Areas with historically high seismic activity.
M Local, surface wave or body wave magnitude
VI Modified Mercalli Intensity
References:
Widmann and Others (1998)
U. S. Geological Survey Earthquake Catalogs
% Pori
•I Cplllne
f Loveland
!Rocky Min. Anion
i 196121u 19117
VI to VII
M 3.2 10 M 5.3
Denver
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Rock
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Pueblo
0
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0 50 m1.
i J
Scale: 1 In, = 50 ml.
TCI Lane Ranch Project
Geologically Young Faults and Larger Historic Earthquakes
Figure 2
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0
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ea
L2
0
m
m
0
0
70
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0
Shallow Evaporate in Eagle
Valley Formation and Eagle
Valley Evaporite.
Explanation:
* Project
Site
References:
Tweto and Others (1978)
Kirkham and Scott (2002)
Basis
Carbondale
Collapse
Center
(460 sq. mi.)
M7,1,1
Eagle
Collapse
Center
(960 sq. mi.)
m
0
0
Explanation:
Man -Placed Fill
af
Qt1 1
Qt2
Qt3 J
Qt4
Qf
First Post -Glacial Terrace
Second Post,Glaclal Tel
Third Post -Glacial Terrace
Fourth Post Glacial Terrace
Alluvial Fans
_ Qt7 Qf
af
Qt5 - 7
P1
P€nedale Qutwash Terraces:
5 - lowest, 6 - intermediate, 7- highest
Colluvium over Eagle Valley Evaporite
Contact:
Approximate boundary of map units.
■ Exploratory Pits:
Approximate locations.
0 400 ft,
Scale: 1 in. = 400 ft.
Contour Intorval: 10ft. and 40 it,
March 2009
Modified from Kirkham and Widmann (1997)
106 0920
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HEPWORTN-PAWLAK OEOTECHNICAL
TCI Lane Ranch Development
Project Area Geology Map
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APPROXIMATE SCALE
1" = 300'
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NURSERY PARCEL
roximate location of
previous percolation test
10/30/2006
PIT 1 •
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LOCATION OF EXPLORATORY PITS
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4=15
-200=2
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Note Explanation of symbols is shown on Figure 3.
1 06 0920
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11-1
HEPWORTHPAWLAK GEOTECHNICAL
LOGS OF EXPLORATORY PITS
Depth - Feet
LL
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0
Figure 6
LEGEND:
TOPSOIL; organic silty clay, soft, moist, dark brown.
SAND (SM-SP ); silty, trace gravels, loose, slightly moist, brown.
GRAVEL AND COBBLES (GM -GP); with boulders, clean sand, dense to very dense, slightly moist, light
brown to brown, subrounded rock.
SI 2' Diameter hand driven liner sample.
Disturbed bulk sample,
Free water in pit at time of excavating.
NOTES;
1. Exploratory pits were excavated on January 15, 2008 with a track excavator.
2. Locations of exploratory pits were measured approximately by pacing from features shown on the site plan
provided.
3. Elevations of exploratory pits were not measured and the logs of exploratory pits are drawn to depth,
4. The exploratory pit locations and elevations should be considered accurate only to the degree implied by the method
used.
5. The lines between materials shown on the exploratory pit logs 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 with time.
7. Laboratory Testing Results:
WC = Water Content (%)
DD = Dry Density (pcf)
+4 = Percent retained on the No. 4 sieve
-200 = Percent passing No. 200 sieve
106 0920
H
Hepworth-Powlok
Geot chnicai
LEGEND AND NOTES
Figure 7
Compression
2
3
4
5
6
7
8
9
Moisture Content = 8.9 percent
Ury Density 96 pcf
Sample of; Silty Sand
From: Pill at 2 Y Feet
-t]
Compression
-upon
wetting
O.1
106 0920
1,0
Hepworth— Pawl ok Geotechn[cal
10 100
APPLIED PRESSURE - ksf
SWELL -CONSOLIDATION TEST RF,SIJI TS 1 Figure 8
"CENT RETAINER
• RCENT RETAIN s
HYDROMETER ANALYSIS SfEVF ANALYSIS j
TIME READINGS U.S. STANDARD SERIES I CLEAR SQUARE OPENINGS
45 MIN. 15h1MIN. 60MIN19MIN.A MIN. 1 MIN. #200 #100 #50 #30 #16 #B #4 3/8" 3/4" 1 1/2" 3" 5"6" 8'
0 100
10
20
30
40
50
60
70
80
90
100
1
i_
1
i
t
001
.002
005 009 019 ,037 074 .150 300 600 1.18 2 36
DIAMETER OF PARTICLES IN MILLIMETERS
CLAY TO SILT
FIN£
SAND
i.1EUiUM [COAo$E
4.75
9.5 125 19,0
SINE
37.5 762 152 203
127
GRAVV,
1 CUAI:SE
GRAVEL 66 % SAND 32 % SILT AND CLAY 2
LIQUID LIMIT % PLASTICITY INDEX %
SAMPLE OF: Sandy Gravel FROM: Pit 2 at 8 to 8 Y Feet
COBBLES
s0
BO
C3
70
co
UJ
60 eL
1-"-
50 Z
W
U
40
W
0
ao
20
10
L� HYDROME tR ANALYSIS SIEVE ANALYSIS I
� TIME READINGS U,S, STANDARD SERIES I CLEAR SQUARE OPENINGS {[
24 MIN. '15 MIN. 60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 #4 3/8" 3/4" 1 1/2" 3" 5°6" 8'
100
10
20
30
40
50
60
70
80
90
-T
r
r
•
1`-
100
001 .002
.005 .009 019 .037 .074 .150 .300 .600 1.18 2.36 4 75 9.512.519 0 37.5
CLAY 70 SILT
DIAMETER OF PARTICLES IN MILLIMETERS
GRAVEL 15 %
LIQUID LIMIT %
SAMPLE OF: Sandy Gravel
106 0920
1—i
Hepworih--Pawlok Geot chnlcol
SAND
EIF]E I ME.UIIRA 1 MAME
rim
CN OEL
COAFlSr
90
80
C3
70
60 0_
50 W
C7
40 W
0_
30
20
10
0
76.2 121y52 203
SAND 83 % SILT AND CLAY 2
PLASTICITY INDEX %
FROM: Pit 3 at 5 to 5 Y Feet
GRADATION TEST RESULTS
COBBLES
Figure 9
'ER EN RETA
NAMIXBMINTIVEXI
10
30
40
50
60
70
80
90
100
HYDROMETER ANALYSIS SIEVE ANALYS!^a
TIME READINGS U.S. STANDARD SERIFS I CLEAR SQUARE OPENINGS
451R. 7MIN. 15MMIN. 6OMINIOMIN.4 MIN. 1 MIN, #200 #140 #50 #30 #16 #8 #4 3/8" 3/4" 1 1/2" 3" 5"6" 8"
10
20
30
40
50
60
70
80
90
100
001 .052 .005 .009 .019 .037 .074 .150 .300 .600 1.10 2,30 4.75 9,5 125 19.0 37.5 702 152 203
127
'J
CLAY 70 SILT
DIAMETER OF PARTICLES IN MILLIMETERS
Ste+
FINE 1 bbE:OIUM J COARSE FINE
1
CART*"
MARNE
GRAVEL 69 % SAND 29 % SII T AND CLAY 2
LIQUID LIMIT % PLASTICITY INDEX %
SAMPLE OF: Sandy Gravel FROM: Pit 4 at 8 Y to 9 Feet
HYDROMETER ANALYSIS I SIEVE ANALYSIS
24 SIR. 7 HR TIME READINGS j U.S. STANDARD SERIES 1 CLEAR SQUARE OPENINGS
45 IN. 15 MIN. 60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 #4 3/8" 3/4" 1 1/2" 3" 5"6" 8"
0 100
90
20
./ ._ _
80
COBBLES
110
70
60
40
30
20
10
- o
11
}
1
t
•
.001 .002 .005 .009 .019 ,037 074 .150 .300 .600 1.18 2.36
DIAMETER OF PARTICLES IN MILLIMETERS
CLAY TO SILT
GRAVEL 73 %
LIQUID LIMIT %
SAMPLE OF: Sandy Gravel
106 0920
H
I.12warth--Pawlak Geotarhnleal
FI 1 IdEG1L1,1 J GGMIOE
70
60
50
40
30
20
10
0
4.75 9.512.519.0 37.5 76.2 121752 203
CORUI.ES
SAND 25 SILT AND CLAY 2 4%0
PLASTICITY INDEX %
FROM: Pit 6 at 8 1/ to 9 Feet
seArwi
FMiE COARSE
,g ra n- Tc i iew
� �u�u�ea.��u`
ligaNWI ' II I
GRADATION TEST RESULTS J
Figure 10
37:T ► : i
HYDROMETER ANALYSIS 1 SIEVE ANALYSIS
TIME READINGS U.S. STANDARD SERIES I CLEAR SQUARE OPENINGS
raF� 7 HR 1
5 MiN. 15 MIN. 60MIN19MIN.4 MIN 1 MIN. #200 #100 #50 #30 #16 #8 #4 3/B" 3/4' 12" 3" 5" 6" 8'
/
0 _ 100
10
20
30
40
50
60
70
80
90
100
001 002 .000 .009 019 037 .074 .150 .300 800 1,18 2.30
DIAMETER OF PARTICLES IN MILLIMETERS
CLAY TO SILT
GRAVEL 61 %
LIQUID LIMIT %
SAMPLE OF: Sandy Gravel
WIR
F1I I asEatum CoAREz
4.75
9.5 12.5 19.0
37,5 76.2 152 203
127
COARSE
COBBLES
SAND 36 % SILT AND CLAY 3 %
PLASTICITY INDEX %
FROM: Pit 8 at 7 Y to 84 Feet
so
00
70
s0
50
40
30
20
10
HYDROMETER ANALYSIS 1 SIEVE ANALYSIS 1
����� TIME READINGS I U.S. STANDARD SERIES I CLEAR SQUARE OPENINGS 1
45 NA .. 15 MIN. 60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8 44 3/8" 3/4" 1 1/2" 3" 5"6" 8'
0 100
10
20
30
40
50
60
70
B0
90
100
.001 .002
r
1-
i
M
.005 .009 .019 .037 .074 .150 .300 .600 1.18 2.36
DIAMETER OF PARTICLES IN MILLIMETERS
CI AY TO SILT
GRAVEL 54 %
LIQUID LIMIT %
SAMPLE OF: Sandy Gravel with Cobble
106 0920
H
Hepworth—Paw[ak Geoterrntea1
EWE
maim I CONIEE
90
80
70
60
50
40
30
20
10
0
4.75 9.512 519.0 37,5 76.2 12152 203
GRAVEL
FINE j CQ.1RBE
SAND 41 % SILT AND CLAY 5
PLASTICITY INDEX %
FROM: Pit 10 at 6 to 7 Feet
GRADATION TEST RESULTS
COBBLES
Figure 11
» Ni3MI11•0211 1E0
HYDROMETER ANALYSIS
TIME READINGS U.S. STANDARD SERIES
24IIn. 7 HR
0 45 MIN. 15 MIN.60MIN19MIN.4 MIN. 1 MIN. #200 #100 #50 #30 #16 #8
10
20
30
40
50
60
70
80
90
100
.001 .002 .005 .009 .019 .037 074 .150 .300 .600 1.18 2.36 4.75 9.5 19,0 37.5 76.2 152 203
12.5 127
SIEVE ANALYSIS
CLEAR SQUARE OPENINGS
#4 3/8" 3/4" 11/2" 3" 5'6"
1
1
1
DIAMETER OF PARTICLES IN MILLIMETERS
CLAY TO SILT
GRAVEL 68 %
LIQUID LIMIT %
SAMPLE OF: Sandy Gravel
106 0920
He wurUi-Puwrnk natoehn1caI
SAND
FIN r pa DIMS 1COARSE
SAND 31 %
FILE I COARSE
PLASTICITY INDEX
COBBLES
SILT AND CLAY 1 %
FROM: Pit 12 at 7 y to 8 Peet
GRADATION TEST RESULTS
100
90
80
70
60
50
40
30
20
10
0
Figure 12
HEPWORTH-PAWLAK GEOTECHNICAL, INC.
TABLE 1
SUMMARY OF LABORATORY TEST RESULTS
Job No. 106 0920
SAMPLE LOCATION
NATURAL
MOISTUR
E
CONTEN
T
- (%)
NATURAL
DRY
DENSITY
(KO
GRADATION
PERCENT
PASSING
NO. 200
SIEVE
ATTERBERG LIMITS
UNCONFINED
COMPRESSIVE
STRENGTH
(PSF)
SOIL OR
BEDROCK TYPE
PIT
DEPTH
(ft)
GRAVEL
(%)
SAND
(%}
LIQUID
LIMIT
(%)
PLASTIC
INDEX
(%)
1
2'/2
8.9
96
41
Silty sand
2
8 - 81/2
66
32
2
Sandy gravel
3
5 - 51/2
2.7
15
83
2
Gravelly sand
4
81/2 - 9
69
29
2
Sandy gravel
6
81/2 - 9
73
25
2
Sandy gravel
8
7'/2 - 81/2
61
36
3
Sandy gravel
10
6 1/2 - 7
54
41
5
Sandy gravel
12
71/2 - 8
68
31
1
Sandy gravel