HomeMy WebLinkAboutGeotechnical Investigation Report 03.18.2022
Draft Geotechnical Investigation Report
Private Hangar Lots A1 and A2
Rifle-Garfield County Airport
Rifle, Colorado
Yeh Project No.: 222-084
March 18, 2022
Prepared for:
Crisak Inc.
ATTN: Scott Moffat
37174 Devon Wick Lane
Purcellville, VA 20132
Prepared by:
Yeh and Associates, Inc.
1525 Blake Avenue
Glenwood Springs, Colorado 81601
Phone: 970-384-1500
Fax: 970-384-1501
Draft Geotechnical Investigation Report
Private Hangar Lots A1 and A2
Rifle-Garfield County Airport
Rifle, Colorado
Yeh Project No.: 222-084
March 18, 2022
Prepared by: Prepared by:
Kevin Dye, P.E. Sylvia White
Project Engineer Senior Geologist
Reviewer: Independent Reviewer:
Scott W. Richards, P.E., P.G. Martin L. Skyrman, P.E.
Senior Project Manager Senior Project Manager
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Table Of Contents
1. PURPOSE AND SCOPE OF STUDY ................................................................................................... 1
2. PROPOSED CONSTRUCTION .......................................................................................................... 2
3. SITE CONDITIONS AND GEOLOGIC SETTING .................................................................................. 3
3.1 SITE CONDITIONS ............................................................................................................................... 3
3.2 GEOLOGIC SETTING ............................................................................................................................ 3
4. SUBSURFACE INVESTIGATION AND CONDITIONS .......................................................................... 4
4.1 FIELD INVESTIGATION ......................................................................................................................... 4
4.2 SUBSURFACE CONDITIONS ................................................................................................................... 6
4.3 LABORATORY TESTING ........................................................................................................................ 6
4.3.1 CLAY ..................................................................................................................................... 6
4.3.2 SAND ..................................................................................................................................... 7
4.4 GROUNDWATER ................................................................................................................................ 7
5. SEISMIC CONSIDERATIONS ........................................................................................................... 7
6. FOUNDATION RECOMMENDATIONS ............................................................................................. 8
6.1 SHALLOW FOUNDATIONS .................................................................................................................... 8
6.2 DEEP FOUNDATIONS ........................................................................................................................ 10
6.2.1 HELICAL PILE FOUNDATION ..................................................................................................... 10
6.3 FLOOR SLAB DESIGN AND CONSTRUCTION ........................................................................................... 11
7. PAVEMENT ................................................................................................................................. 12
8. CORROSIVITY .............................................................................................................................. 12
9. RADON GAS ................................................................................................................................ 12
10. SITE GRADING AND CONSTRUCTION CONSIDERATIONS .............................................................. 12
10.1 SITE AND SUBGRADE PREPARATION .................................................................................................... 13
10.2 UNDERCUTTING AND SUBGRADE STABILIZATION ................................................................................... 13
10.3 EXCAVATION AND TRENCH CONSTRUCTION .......................................................................................... 14
10.4 DEWATERING/SHORING .................................................................................................................... 15
10.5 ENGINEERED AND STRUCTURAL FILL REQUIREMENTS ............................................................................. 15
10.6 COMPACTION REQUIREMENTS ........................................................................................................... 16
10.7 UTILITY TRENCH BACKFILL ................................................................................................................. 17
10.8 CUT AND FILL SLOPES ....................................................................................................................... 17
10.9 DRAINAGE CONSIDERATIONS ............................................................................................................. 18
10.10 CONSTRUCTION IN WET OR COLD WEATHER .............................................................................. 18
11. LIMITATIONS .............................................................................................................................. 18
12. REFERENCES ............................................................................................................................... 20
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List Of Tables
TABLE 1 – SEISMIC PARAMETERS FOR REFERENCE SITE CLASS B ................................................................................ 7
TABLE 2 – SEISMIC DESIGN PARAMETERS FOR PROJECT SITE ..................................................................................... 7
TABLE 3 – IMPORTED STRUCTURAL FILL CRITERIA ................................................................................................. 16
TABLE 4 – COMPACTION REQUIREMENTS ............................................................................................................ 17
List Of Figures
FIGURE 1 ‐ PROJECT AREA LOCATION .................................................................................................................... 1
FIGURE 2. ‐ DRILLING BORING B‐1 LOOKING WEST .................................................................................................. 5
FIGURE 3 – DRILLING BORING B‐3 AT EAST EDGE TAXIWAY B4 LOOKING NORTH .......................................................... 5
List Of Appendices
GEOLOGY MAP .................................................................................................................................... A
BORING LOCATION MAP ...................................................................................................................... B
BORING LOGS AND LEGEND ................................................................................................................. C
LABORATORY TEST RESULTS ................................................................................................................ D
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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1. PURPOSE AND SCOPE OF STUDY
This report presents the results of our geotechnical engineering investigation for the proposed
hangar on Lots A-1 and A-2 at the Rifle Garfield County Airport in Rifle, Colorado. The
investigation was performed in accordance with Yeh and Associates Inc. (Yeh) Proposal No.
222-084, dated February 14, 2022. Our scope of services was authorized by Mr. Scott Moffat, a
Preconstruction Manager with Crisak Inc., on February 16, 2022. The purpose of the work is to
collect subsurface data from the site and prepare foundation, floor slab and general site grading
recommendations for the proposed improvements. The project location is presented in Figure 1.
Figure 1 - Project Area Location
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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Our scope of services included the following:
Drill a minimum of two (2) borings near proposed structure corners
Collect soil samples and perform laboratory testing to include classification, R-value,
swell/collapse potential, unconfined compressive strength and corrosivity
Record standard penetration blow counts to be used in geotechnical analysis and
design
Prepare a report that:
o Summarizes field and laboratory data
o Presents the results of geotechnical engineering analyses
o Provides structure foundation, concrete floor slab and general site grading
recommendations
The geotechnical investigation consisted of geologic reconnaissance and drilling of exploratory
borings to investigate subsurface conditions. Field investigation activities were overseen by a
Yeh engineer. Samples obtained during the field exploration were examined by the project
engineer and laboratory testing of representative samples was performed to evaluate the
engineering characteristics of materials encountered.
Based on our investigation, Yeh completed a geotechnical engineering evaluation for the
proposed improvements. This report summarizes our field investigation, the results of our
analyses, and our conclusions and recommendations based on the proposed construction, site
reconnaissance, subsurface investigation, and results of the laboratory testing. A detailed
pavement evaluation was outside the scope of our services. Yeh should be contacted, as
needed, to provide additional pavement design recommendations under a supplemental scope
of services.
2. PROPOSED CONSTRUCTION
A preliminary site plan provided by the client shows the proposed construction site. . Based on
preliminary plans and email communications with the client, proposed structures include a pre-
engineered metal frame airport hangar with concrete floor slab located east of the terminal
building on Lots A-1 and A-2 along Taxiway B4, the Group II Taxilane. The planned hangar
dimensions are 176 feet by 133 feet and new pavement is expected to connect the hangar to
the Taxilane. Boring locations were chosen based on the information as above.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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3. SITE CONDITIONS AND GEOLOGIC SETTING
3.1 Site Conditions
The Rifle Garfield County Airport, identified by the FAA as RIL, is located at the north end of
Runway Road, less than one mile from its intersection with County Road 352, south of
Interstate 70, and southeast of Rifle, Garfield County, Colorado. The project area includes
unimproved Lots A-1 and A-2 west of Taxiway B4, east of the existing terminal building and
south of Runway 26 as shown on the Figure B-1 Approximate Test Boring Location Map in
Appendix B.
Elevations were estimated from Google Earth and ranged between approximately 5,535 and
5,545 feet. The project site was nearly level with grades of less than 2 percent. The Last
Chance Ditch is approximately 0.5 miles north and approximately 150 feet lower than the project
area, with Mamm Creek located approximately 0.5 mile to the east and northeast, and the
Colorado River is approximately 0.9 mile to the north. Vegetation at the site included native and
cultured grasses and no trees or shrubs were observed at the site. The ground was snow-
covered at the time of this investigation.
Public utilities in the area were located and marked after UNCC One Call locates. We were not
notified of private infrastructure near the drill locations and private utility locates were outside of
our scope of services for this investigation.
3.2 Geologic Setting
The project area is situated on a small mesa northeast of Grass Mesa in the southeast area of
the Piceance Basin of western Colorado, a complex of numerous anticlines and synclines and a
major gas production area. The Piceance Basin is located in the Colorado Plateau province and
the topography of the basin is made up of high plateaus, ridges and deep valleys. The
asymmetrical, arc-shaped basin is 100 miles long by 50 miles wide that is oriented northwest-
southeast and is deepest on the east edge. It is bounded structurally on the north by the Uinta
Mountains, on the northeast by the Axial Uplift, on the east by the Grand Hogback/White River
Uplift and the Elk Mountains, on the south by the Uncompahgre Uplift and on the west by the
Douglas Creek Arch/Rangely Dome. Underlying bedrock near the project site, generally dips, or
tilts, at approximately 3 to 8 degrees to the west and northwest. Based on the U.S. Geological
Survey Geologic Map of the Silt quadrangle (Shroba, 2001), bedrock underlying the site, and
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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also exposed surrounding the site, is the varicolored claystone, mudstone, siltstone and weakly
cemented sandstone of the Tertiary age Shire Member of the Wasatch Formation. The
formation contains a weak calcite cement and may be prone to landslides.
Surficial deposits at the site include Quaternary age loess deposits of wind-blown, calcareous
clay, silt and sand overlying sand, pebbles, and cobbles of terrace alluvium. The terrace
alluvium in this area may be mantled by two loess sheets and may contain or be overlain by
Quaternary age Lava Creek B volcanic ash (Shroba, 2001). The loess in the project area is
estimated to be 3 to 24 feet (1 to 8 meters) thick. Artificial/manmade fill and disturbed areas may
be present at the project site. Based on Shroba, 2001 mapping information and our experience
in this area, the loess deposits and potential ash layers may be prone to sheet erosion, gullying,
piping, and hydro-compaction. A Geology Map is presented in Appendix A.
4. SUBSURFACE INVESTIGATION AND CONDITIONS
4.1 Field Investigation
A total of three (3) borings were drilled in the project area. Boring B-1 was drilled in the
northwest quadrant of Lot A-1, boring B-2 was drilled in the southeast quadrant of Lot A-2 and
boring B-3 was drilled through the existing pavement at the west edge of Taxiway B4 along the
east perimeter of the lots. The borings were completed on February 24, 2022 at locations
selected by Yeh based on the estimated structure foundation layout as provided by the client.
Survey of the borings was outside the scope of this investigation. The approximate locations of
the borings are presented on Figure B-1, Approximate Test Boring Location Map, in
Appendix B.
All borings were advanced using a Diedrich D-90 track-mounted drill rig with 4-inch solid,
continuous flight auger. At selected intervals, a modified California sampler with a 2-inch interior
diameter (ID) and 2.5 inch outside diameter (OD), or a standard split spoon sampler with a 1⅜-
inch ID and 2-inch OD were used to record blow counts (SPT) and obtain samples. The sampler
was seated at the bottom of the boring, then advanced by a 140-pound hydraulic automatic, or
“auto,” hammer falling a distance of 30 inches. The number of blows required to drive the
sampler two 6-inch intervals or a fraction thereof, constitutes the N-value. Bulk samples of drill
cuttings were also obtained. Boring logs and legend are presented in Appendix C. See Figures
2 and 3 for boring activity photos.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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Figure 2. - Drilling boring B-1 looking west
Figure 3 – Drilling boring B-3 at east edge Taxiway B4 looking north
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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4.2 Subsurface Conditions
Subsoils encountered in borings B-1 and B-2 at the surface consisted of approximately 6 inches
of topsoil over stiff to hard sandy clay or clay with sand to depths explored of up to 30 feet.
Boring B-1 encountered a dense sand and gravel lens at approximately 5 to 9 feet deep. Boring
B-3 was drilled at the west edge of the Taxiway B-4 and had 4.5 inches of asphalt over 24
inches of base material of gravel and sand with clay over sandy clay. Groundwater was not
encountered in any of the borings. Bedrock was not encountered and drilling to bedrock was not
included in the scope of services. Boring logs and legend are presented in Appendix C and
results of the laboratory testing are presented in Appendix D.
4.3 Laboratory Testing
Representative soil samples were selected for geotechnical and analytical laboratory testing.
Laboratory testing was performed in general accordance with industry standards and local
practice. Tests included the following:
Natural moisture and dry density
Particle-size analysis
Atterberg limits
Swell/collapse potential
Water soluble sulfates
R-value
Results of the laboratory testing are shown on the boring logs in Appendix C and presented in
the Laboratory Summary in Appendix D. Unconfined compressive strength testing was
attempted but samples crumbled upon extrusion from liners due to the percentage of sand and
the low moisture content.
4.3.1 Clay
Laboratory testing was performed on 12 clay samples that had 53 to 80 percent fines (material
passing the No. 200 sieve). Atterberg limit testing on 11 of these samples indicated liquid limits
of 21 to 31 percent, and plasticity indices of 4 to 18 percent. Swell/collapse testing
(ASTM D4546) on four of these samples taken at depths between 3 and 10 feet exhibited
collapse of 1.7 to 3.1 percent upon wetting and an applied pressure of 1,000 pounds per square
foot (psf). Hveem (R-value) testing performed on a bulk sample of clay taken between depths of
0.5 to 5 feet resulted in a value of 14 at exudation pressures of 300 pounds per square inch
(psi).The clay samples classified as CL and CL-ML according to the Unified Soil Classification
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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System (USCS) and as A-4 (0), A-4 (2), and A-6 with group indices of 3, 5, 6, 9 and 10 based
on the American Association of State Highway and Transportation Officials (AASHTO).
4.3.2 Sand
One sand sample tested had 36 percent fines, a liquid limit of 22 percent and a plasticity index
of 8 percent. The sand sample tested classified as SC (USCS) and as A-4 (0) (AASHTO).
4.4 Groundwater
No groundwater was encountered in the borings during drilling. Variation in groundwater levels
will be largely dependent upon the amount of spring snowmelt, duration and intensity of
precipitation, site grading changes, and the surface and subsurface drainage characteristics of
the surrounding area. Perched water tables may be present but were not encountered in the
exploratory borings.
5. SEISMIC CONSIDERATIONS
Results of the field investigation and laboratory test results were used to evaluate the seismic
site classification in accordance with IBC 2015 using Seismic Design Maps Web Services.
Based upon the nature of the subsurface materials we recommend that Site Class D (stiff soil)
be used in the design of the risk category II, III and IV structures for the proposed project
(approximate site coordinates: 39.5237° N, -107.7168° W). The site class was based on the
conditions encountered in our shallow exploratory soil borings and our knowledge of the
subsurface conditions in the site vicinity. The soil characteristics extending beyond the depth of
our borings were assumed for the purposes of providing this site classification. The site seismic
design parameters are presented in Tables 1 and 2. These values are the same for risk
categories II, III and IV.
Table 1 – Seismic Parameters for Reference Site Class B
PGA (0.0 sec) SS (0.2 sec) S1 (1.0 sec)
0.179 g 0.307 g 0.08 g
Table 2 – Seismic Design Parameters for Project Site
Site Class Fa (0.2 sec) Fv (1.0 sec) SDS (0.2 sec) SD1 (1.0 sec)
D 1.554 2.4 0.318 g 0.128 g
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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6. FOUNDATION RECOMMENDATIONS
In general, the site appears suitable for the proposed construction based on geotechnical
conditions encountered in the borings. The hangar can be supported on shallow foundations
such as spread or strip footings bearing on native soils at the recommended depth. An email
received from SGM, project structural engineer, on March 3, 2022 anticipates a maximum
column location load of 150 kips for shallow foundations and pier loads of 250 kips or more for
deep foundations. An increased bearing pressure may be used if shallow foundations are
placed on a properly prepared layer of structural fill as described below. Deep foundations such
as helical piles would also be an appropriate option in the existing soils.
Foundation design and construction should follow the Garfield County requirements and the
2015 International Building code (IBC). Recommendations presented herein should be
confirmed by a representative of Yeh once excavations for foundations are completed and prior
to placement of reinforcing steel and concrete.
6.1 Shallow Foundations
Based on the subsurface exploration and laboratory test results, shallow foundations placed on
undisturbed native soil may be used to support the hangar. A higher bearing pressure can be
achieved, as described below if a thickness of clay soil below the foundation elements is
removed and replaced with imported structural fill in accordance with Section 10.5, Engineered
and Structural Fill Requirements. On-site soil should not be used as structural fill placed
beneath footings due to the high percentage of fine-grained material. Shallow foundations
should be designed in accordance with the following recommendations:
1. Shallow foundations, including strip footings or spread footings, bearing on native soil
can be designed for an allowable bearing pressure of 2,500 psf.
2. An allowable bearing pressure of 4,500 psf can be used if existing clay soils are
removed to a minimum depth of 2 feet below shallow foundations and replaced with
imported structural fill meeting the criteria in Table 3. The fill should extend 2 feet
laterally beyond all footing edges.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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3. The allowable design values are based on a factor of safety of 3.0. A one-third increase
in the allowable bearing pressure may be used for temporary loading conditions
including wind or seismic conditions.
4. For frost heave protection, footings should bear a minimum of 36 inches below lowest
adjacent finished grade. Interior footings not subject to freezing should bear a minimum
of 12 inches below finish floor elevation (FFE).
5. Resistance to sliding may be derived from passive resistance along the vertical face of
the footings, and friction between the bottom of the footings and the bearing soil. An
ultimate passive resistance using an equivalent fluid density of 350 pounds per cubic
foot (pcf) may be used for the design. An ultimate coefficient of friction of 0.4 or 0.6 can
be used for the sliding resistance between the bottom of the footings and native clay or
structural fill, respectively. A factor of safety of 2.0 is recommended to calculate
allowable values. We recommend the upper 2 feet of the soils to be neglected in the
passive resistance unless the adjacent ground surface is paved.
6. Continuous (strip) footings should have a minimum width of 18 inches, and isolated
spread footings should have a minimum width of 24 inches. Minimum edge to edge
distance between adjacent foundations should not be less than the largest footing width.
7. We recommend that all old fill material, debris, organic material including topsoil, and
loose or deleterious material be removed prior to establishing bearing grades.
Footings should be proportioned to reduce differential foundation movement. Proportioning on
the basis of equal total movement is recommended; however, proportioning to relative constant
dead load pressure will also reduce differential movement between adjacent footings. Total
movement is estimated to be on the order of one (1) inch or less. Differential movement is
anticipated to be on the order of ½ to ¾ of the estimated total movement. Footings and
foundations should be reinforced as necessary to reduce the potential for distress caused by
differential foundation movement.
If unstable conditions are present at the time of foundation excavation it may be necessary to
install a geotextile to reinforce the subgrade at the base of the excavation and facilitate
structural fill placement. The geotextile should be selected in accordance with the intended
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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application and should extend a minimum of two (2) feet laterally beyond all footing edges along
with the structural fill.
Lab testing on soil samples resulted in a generally low to moderate collapse potential if soil
becomes saturated. The performance of a shallow foundation system will be highly dependent
upon proper drainage during and following construction. Ponding water, waterline leaks, and
other sources of water near the structure foundation can result in an increase in the predicted
movements including foundation distress and/or observed cracking.
Conversely, during construction the water content in the foundation soils must be maintained
during dry weather to prevent excessive drying, which can also result in a greater amount of
movement than predicted. Even with a properly designed and constructed foundation system,
foundation movements can cause distress to the structure, such as cracks and misalignments of
various components. Footings and foundations should be reinforced as necessary to reduce the
potential for distress caused by differential foundation movement.
Foundation excavations should be observed by Yeh. If the soil conditions encountered differ
significantly from those presented in this report, supplemental recommendations will be
required.
6.2 Deep Foundations
Deep foundations such as helical piles are an option for support of the hangar. The foundation
elements are typically tied together in a rigid cap of reinforced concrete which may be the
foundation footing or a grade beam. Typically, these systems are designed and installed by a
specialty contractor working under a performance specification. Design and construction
recommendations for helical piles are provided below.
6.2.1 Helical Pile Foundation
Some benefits of helical piles include relative ease of installation with no grouting and no cure
time, reduced construction noise compared to drilling and no drill cuttings or wastewater that
require management and disposal. Helical piles may be more cost effective and require less
installation time compared to a deep foundation system requiring drilling and grout or concrete
placement. Helical pile systems should be designed in accordance with the 2015 IBC and meet
the acceptance criteria for helical pile systems and devices. General recommendations for
design and construction of helical piles are presented below.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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1. The structural engineer should determine helical pile locations and load
requirements. This information should be provided to a specialty design/build
contractor to develop drawings for the helical piles. Provided site grades are not
raised by more than three (3) feet, we do not believe down drag would induce
additional loading on the foundation. Foundation design need not account for
downdrag loads when new fill heights are less than three (3) feet.
2. Since drilling refusal and a consistent, relatively thick cohesionless bearing
stratum were not encountered within the borings, the anticipated depths of helical
pile refusal are difficult to predict. Depending on the pile spacing, target depths
for helical piles may range between 10 to 20 feet below existing grade based on
information from borings B-1 and B-2. These pile lengths are estimates and
actual lengths may exceed these values.
3. Onsite verification testing should be performed in accordance with specialty
contractor recommendations. A representative of the geotechnical engineer, Yeh
and Associates, should observe helical pile installation.
6.3 Floor Slab Design and Construction
Floor slabs for the structure should be supported on a minimum 6-inch layer of imported
structural fill meeting the requirements of Table 3 or Colorado Department of Transportation
(CDOT) Class 6 Aggregate Base Course (ABC) material. Some differential movement of a slab-
on-grade floor system is possible should the subgrade soils become elevated in moisture
content. To reduce potential slab movements, the subgrade soils should be prepared according
to Section 10.1, Site and Subgrade Preparation. For structural design of concrete slabs-on-
grade, a modulus of subgrade reaction of 150 pounds per cubic inch (pci) may be used for
floors supported on 6 inches of non-expansive, gravel or imported structural fill compacted as
described Section 10.6, Compaction Requirements.
Additional floor slab design and construction recommendations are as follows:
1. Positive separations and/or isolation joints should be provided between slabs and all
foundations, columns or utility lines to allow independent movement.
2. Control joints should be provided in slabs to control the location and extent of cracking.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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3. Interior trench backfill placed beneath slabs should be properly placed and compacted.
4. Floor slabs should not be constructed on frozen subgrade.
5. Other design and construction considerations, as outlined in Section 302.1 R-04 of the
ACI Guide for Concrete Floor and Slab Construction are recommended.
7. PAVEMENT
Pavement design was outside our approved scope of services. The new pavement, at the
entrance to the hangar, is anticipated to experience less loading than the existing taxiway which
appears to be in good to excellent condition at the time of this report. We recommend the new
pavement section match the existing Taxiway B4/Group II Taxilane section of 4.5 inches of
asphalt concrete over 2 feet of aggregate base course.
8. CORROSIVITY
The concentrations of water-soluble sulfates measured in two samples obtained from the
exploratory borings at depths of 2.0 to 4.5 feet and from 4.0 to 5.5 feet were 0.045 and 0.072
percent, respectively. Based on these laboratory test results, typical soils in the area present a
Class 0 exposure rating based on a range of less than 0.10 percent as presented in the
American Concrete Institute (ACI) Guide to Durable Concrete and corrosive soils are not
anticipated at the project site. A qualified corrosion engineer should review this data to
determine the appropriate level of corrosion protection.
9. RADON GAS
Radon gas can be found in nearly all rock and soil and can move into buildings or other
enclosed spaces and create a health hazard if radioactive particles are inhaled. Evaluation of
the radon gas potential was not within our authorized scope of service and should be addressed
by others.
10. SITE GRADING AND CONSTRUCTION CONSIDERATIONS
Site preparation and earthwork operations should be performed in accordance with applicable
codes, safety regulations, and other local, state, or federal guidelines. We recommend
earthwork on the project be observed and evaluated by Yeh. The evaluation of earthwork
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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should include observation and testing of engineered fills, subgrade preparation, foundation
bearing materials and other geotechnical conditions exposed during the construction of the
project. We also recommend that Yeh review the project grading plans to ensure they are in
conformance with the recommendations presented herein.
10.1 Site and Subgrade Preparation
Preparation of the site should begin with stripping and removal of remaining topsoil, organic
materials, and construction debris or unsuitable material. The stripped materials should be
removed for offsite disposal in accordance with local laws and regulations or stockpiled. All
exposed surfaces should be free of mounds and depressions, which could prevent uniform
compaction.
Following the above, all exposed areas which will receive fill, support structures, or pavements,
should be scarified to a minimum depth of 8 inches, moisture conditioned, and compacted
according to Section 10.6, Compaction Requirements. Prior to placement of fill or structural
elements, the condition of the exposed subgrade soil should be evaluated by observation of a
proof roll. Proof rolling the subgrade aids in identifying soft or disturbed areas. Unsuitable areas
identified by the proof rolling operation should be undercut and replaced with imported structural
fill. Proof rolling may be accomplished through use of a fully loaded, pneumatic-tire dump truck
or similar equipment providing an equivalent subgrade loading. Proof rolling should be
performed under the observation of the geotechnical engineer using multiple passes in both
directions to ensure complete coverage.
Following proof roll observations, suitable fill should be placed to the design grade as soon as
practical to avoid moisture changes in the underlying soils. All structural fill soils should meet the
requirements of Section 10.5, Engineered and Structural Fill Requirements, in this report and be
placed and compacted in accordance with the criteria presented in Section 10.6, Compaction
Requirements.
10.2 Undercutting and Subgrade Stabilization
Based on the subsurface conditions encountered in the borings, subgrade soils exposed during
construction of the proposed structures will be moisture-sensitive and could become overly soft
and unstable at higher moisture levels. If unstable conditions are encountered or develop during
construction, stability may be improved by scarifying and drying/wetting the subgrade soils.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
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Clays may require 3 to 6 inches of crushed rock/gravel to provide a stable working surface. The
amount of aggregate and type of stabilization required will be a function of the conditions
encountered during construction. Over excavation of wet zones and replacement with structural
fill or crushed rock may be necessary.
If areas are found to be unsuitable for re-work, additional stabilization will be required. If
additional stabilization is required, Yeh should be contacted to evaluate the conditions in the
field, and a suitable stabilization method can be provided. In addition, any soft and/or wet areas
exposed during the excavation may need to be stabilized prior to the placement of new fill to
create a stable, firm construction platform. A typical stabilization method may include utilizing
crushed rock with the combination of geogrid (e.g., Tensar BX1200 or TX160) to create a stable
base. Other stabilization methods may also be appropriate.
10.3 Excavation and Trench Construction
Excavations within the on-site geologic materials will encounter a variety of conditions, including
sand, clay and organic material. Additionally, fill placed during previous grading operations may
be encountered that was not present in our widely spaced borings. We anticipate these
materials will be excavatable with conventional heavy-duty earth moving equipment. The
excavation contractor is responsible for determining the means and method necessary to
accomplish earthwork operations.
All excavations must comply with the applicable local, State, and Federal safety regulations, and
with the excavation standards of the Occupational Safety and Health Administration (OSHA).
Construction site safety, including excavation safety, is the sole responsibility of the Contractor
as part of its overall responsibility for the means, methods, and sequencing of construction
operations. Yeh’s recommendations for excavation support is provided for the Client’s sole use
in planning the project, and in no way do they relieve the Contractor of its responsibility to
construct, support, and maintain safe slopes. Under no circumstances should the following
information be interpreted to mean that Yeh is assuming responsibility for either construction
site safety or the Contractor’s activities.
We believe the overburden soil encountered on this site will classify as a Type A material, using
OSHA criteria. OSHA requires that unsupported cuts be no steeper than 0.75H:1V for Type A
material for unbraced excavations up to 20 feet in height. Flattened slopes may be required if
hazardous ground movement is observed, or the slopes will be exposed for an extended period
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
15
of time. Please note that the Contractor’s OSHA-qualified “competent person” must make the
actual determination of soil type and allowable sloping in the field.
The soils encountered in the proposed excavations may vary significantly across the site. The
preliminary classifications presented above are based solely on the materials encountered in
widely spaced exploratory test borings. The contractor should verify that similar conditions exist
throughout the proposed area of excavation. Note the above classifications presume a dry slope
and that seepage encountered within temporary cut slopes will act to destabilize excavations.
As a safety measure, it is recommended that all vehicles and soil piles be kept to a lateral
distance equal to at least the depth of the excavation from the crest of the slope. The exposed
slope face should be protected against the elements and monitored by the contractor on at least
a daily basis.
10.4 Dewatering/Shoring
Groundwater was not encountered in the borings at the time of drilling. If water is discovered at
the time of construction, appropriate dewatering equipment/systems such as well points, sumps,
and trenches, will be the responsibility of the contractor. In addition, trenching into unstable,
saturated overburden soils will require temporary shoring, where construction of safe slopes is
not feasible. OSHA requirements for excavation in unstable materials should be followed.
10.5 Engineered and Structural Fill Requirements
Based on our laboratory test results, the on-site soils should not be utilized as engineered fill
placed directly beneath structural foundations due to the amount of fines present. On-site soils
may be used as engineered fill to raise grade beneath floor slabs as necessary provided
requirements of Section 6.3 are satisfied. Imported structural fill should consist of non-
expansive, well-graded granular material meeting the criteria presented in Table 3. In addition,
structural fill should be non-corrosive to concrete and metal.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
16
Table 3 – Imported Structural Fill Criteria
Gradation Requirements
Standard Sieve Size Percent Passing
2-inch 100
No. 4 30 to 100
No. 50 10 to 60
No. 200 5 to 20
Plasticity Requirements (Atterberg Limits)
Liquid Limit 35 maximum
Plasticity Index 6 maximum
We recommend that a qualified representative of Yeh visit the site during excavation and during
placement of the structural fill to verify the soils exposed in the excavations are consistent with
those encountered during our subsurface exploration and that proper foundation subgrade
preparation and placement is performed.
All fill placed on this site should be compacted according to the recommendations in Section
10.6, Compaction Requirements, of this report. It is recommended that a sample of any
imported fill material proposed for use on the project be submitted to our office for approval and
testing at least three (3) days prior to stockpiling at the site.
10.6 Compaction Requirements
Fill materials should be placed in horizontal lift thicknesses that are suitable for the compaction
equipment being used but in no case should exceed 8 inches by loose measure. Fill materials
should be moisture conditioned and compacted in accordance with the criteria shown in
Table 4.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
17
Table 4 – Compaction Requirements
Fill Location Material Type Percent
Compaction Moisture Content
Subgrade On-site clay, sand, silt 95 minimum
(ASTM D698) 2 % of optimum
Foundation
Areas,
Paved Areas
Imported Structural Fill 1,
Class 6 ABC
95 minimum
(ASTM D1557) 2 % of optimum
Utility Trench
Backfill
(areas outside
structural and
paved areas)
Imported Structural Fill or on-
site clay, sand, silt
90 minimum
(ASTM D698) 2 % of optimum
1Material meeting the criteria in Section 10.5, Engineered and Structural Fill Requirements
10.7 Utility Trench Backfill
On-site soils may be utilized as backfill material in utility trenches provided the location is not
beneath structures or pavement and the backfill is free of plant matter, organic soil, debris,
trash, other deleterious matter, and rock particles larger than 3-inches. Backfill should be placed
in loose lifts of 8-inches or less and compacted with appropriate trench compaction equipment.
Pipe bedding material should meet the requirements of the pipe manufacturer, project
specifications and/or as recommended by the design civil engineer for the project. Imported
granular fill, as described in Section 10.5, Engineered and Structural Fill Requirements could be
considered for pipe bedding material. We suggest maximum aggregate size for drainage pipe
bedding material should be limited to 1.5 inches for plastic pipe, with 2.0 inches acceptable for
other types. Utility trench backfill should be compacted as recommended in Section 10.6,
Compaction Requirements.
10.8 Cut and Fill Slopes
Permanent cut and fill slopes should be inclined no steeper than 2H:1V. Vegetation should be
established on slopes as soon as possible to reduce the potential for erosion of the surface of
cut/fill slopes.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
18
10.9 Drainage Considerations
Positive drainage should be provided during construction and maintained throughout the life of
the project. Proper design of drainage should include prevention of ponding water on or
immediately adjacent to the hangar structure. We recommend the ground surface surrounding
structures be sloped to drain away from the structures at a minimum and preferably covered
with area paving to minimize water infiltration. Roof run-off should be directed away from
building foundation systems. Surface features that could retain water in areas adjacent to the
structures should be sealed or eliminated. Backfill against any kind of structure and in utility line
trenches should be well compacted and free of construction debris to reduce the possibility of
moisture infiltration and migration. Concentrated runoff should be avoided in areas susceptible
to erosion and slope instability. Slopes and other stripped areas should be protected against
erosion by re-vegetation or other methods.
10.10 Construction in Wet or Cold Weather
Engineered fill, structural fill, or other fill should not be placed on frosted or frozen ground, nor
should frozen material be placed as fill. Frozen ground should be allowed to thaw or be
completely removed prior to placement of fill. A good practice is to temporarily cover the
compacted fill with a “blanket” of loose fill to help prevent the compacted fill from freezing.
Concrete structures should not be constructed on frozen soil. Frozen soil should be completely
removed from beneath the concrete elements, or thawed, scarified and re-compacted. The
amount of time passing between excavation or subgrade preparation and placing concrete
should be minimized during freezing conditions to prevent the prepared soils from freezing.
Blankets, soil cover, or heating as required may be utilized to prevent the subgrade from
freezing.
11. LIMITATIONS
The findings and recommendations presented in this report are based upon data obtained from
borings, field observations, laboratory testing, our understanding of proposed construction, and
other sources of information referenced in this report. It is possible that subsurface conditions
may vary between or beyond the locations explored. The nature and extent of such variations
may not become evident until construction. If during construction conditions appear to be
different from those described herein, Yeh should be advised and provided the opportunity to
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
19
observe and evaluate those conditions and provide additional recommendations, as necessary.
Yeh should also be contacted if the scope of construction changes from that generally described
within this report. The conclusions and recommendations contained in this report shall not be
considered valid unless Yeh reviews all proposed construction changes and either verifies or
modifies the conclusions of this report in writing. Yeh should be contacted to perform general
observations and materials testing services during construction. If another firm is contracted for
these services, this firm will assume responsibility for following recommendations provided
herein.
This report was prepared in a manner consistent with that level of care and skill ordinarily
exercised by other members of our profession practicing in the same locality, under similar
conditions and at the date the services are provided. Yeh makes no other representation,
guarantee, or warranty, express or implied, regarding the services, communication (oral or
written), report, opinion, or instrument of service provided.
The scope of services for this project did not include, specifically or by implication, any
environmental or biological (e.g., mold, fungi, and bacteria) assessment of the site or
identification or prevention of pollutants, or conditions or biological conditions. If the owner is
concerned about the potential for such contamination, conditions or pollution, other studies
should be undertaken and a professional in that field should be consulted.
This report may be used only by the Client and the registered design professional in responsible
charge and only for the purposes stated for this specific engagement within a reasonable time
from its issuance, but in no event later than five (5) years from the date of the report.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
20
12. REFERENCES
American Concrete Institute (ACI) 201.2R-08, 2008, Guide to Durable Concrete.
American Concrete Institute (ACI) 302.1R-04, 2004, Guide for Concrete Floor and Slab
Construction.
Colorado Department of Transportation (CDOT), 2021, Standard Specifications for Road and
Bridge Construction.
ICC Acceptance Criteria for Helical Pile Systems and Devices, Compliance date December 1,
2013.
International Code Council. International Building Code. Falls Church, Va. :International Code
Council, 2015.
Shroba, R.R., and Scott, R.B., 2001, Geologic map of the Silt quadrangle, Garfield County,
Colorado: U.S. Geological Survey, Miscellaneous Field Studies Map MF-2331, Version
1.0, scale 1:24,000.
Structural Engineers Association of California, US Seismic Design Maps Web Service,
https://seismicmaps.org/, accessed on March 9, 2022.
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
APPENDICES
GEOLOGY MAP ........................................................................................................................ A
BORING LOCATION MAP .......................................................................................................... B
BORING LOGS AND LEGEND ..................................................................................................... C
LABORATORY TEST RESULTS .................................................................................................... D
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
Appendix A
GEOLOGY MAP
NorthBase map from Shroba, R. and Scott, R., 2001, Geologic map of the Silt quadrangle, Garfield County, ColoradoAlluviium and colluvium Artificial fill Sheetwash deposits over loessOlder terrace alluviumLoessGeologic Map - Approximate Project Location Rifle Garfield County Airport Hangar Lot A-1 Rifle, Garfield County, ColoradoDrawn by: SAWSHEET NUMBER:A-1Yeh and Associates Project No. 222-084Checked by: KD/SWRDate: 3/1/2022File Name: Rifle-Garfield County Airport HangarScale: Not to scaleYeh and Associates, Inc. Geotechnical - Geological - Construction ServicesQloQacApproximateProject AreaafQsw/QloQtoQacafQto
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
Appendix B
BORING LOCATION MAP
B-1
Approximate Test Boring
Location Map
PROJECT NUMBER:
SCALE: 1"=200'
PROJECT:
FIGURE
DRAWN BY:
CHECKED BY:
DATE:
DATE:
DESIGNED FOR:
Geotechnical-Geological-Construction Services
Yeh and Associates, Inc.B-1
SAW
KD/SWR
0 100'200'400'
NOTES:
1. Base map from Google Earth.
2. Boring locations determined in field based on
preliminary construction plan and accessibility
3. Approximate lot boundary based on preliminary information from client.
Indicates approximate location
of test borings
LEGEND
03/07/2022
03/07/2022
Rifle-Garfield County Airport Hangar
Lots A-1 and A-2
Garfield County, ColoradoCrisak Inc.
222-084
Approximate Boundary
Lots A1 and A2
N Taxiway B4/Taxilane Group IIB-1
B-2
B-3
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
Appendix C
BORING LOGS AND LEGEND
Project Number:222-084
Sample Types
Legend for Symbols Used on Borehole Logs
Project:
3. The Modified California sampler used to obtain samples is a 2.5-inch OD, 2.0-inch ID (1.95-inch ID with liners), split-barrel sampler with internal
liners, as per ASTM D3550. Sampler is driven with a 140-pound hammer, dropped 30 inches per blow.
2. "Penetration Resistance" on the Boring Logs refers to the uncorrected N value for SPT samples only, as per ASTM D1586. For samples obtained
with a Modified California (MC) sampler, drive depth is 12 inches, and "Penetration Resistance" refers to the sum of all blows. Where blow counts
were > 50 for the 3rd increment (SPT) or 2nd increment (MC), "Penetration Resistance" combines the last and 2nd-to-last blows and lengths; for
other increments with > 50 blows, the blows for the last increment are reported.
Lab Test Standards
1. Visual classifications are in general accordance with ASTM D2488, "Standard Practice for Description and Identification of Soils (Visual-Manual
Procedures)".
Modified California
Sampler
(2.5 inch OD, 2.0
inch ID)
Standard
Penetration Test
(ASTM D1586)
Drilling Methods
Moisture Content ASTM D2216
Dry Density ASTM D7263
Sand/Fines Content ASTM D421, ASTM C136,
ASTM D1140
Atterberg Limits ASTM D4318
AASHTO Class. AASHTO M145,
ASTM D3282
USCS Class. ASTM D2487
(Fines = % Passing #200 Sieve
Sand = % Passing #4 Sieve, but not passing
#200 Sieve)
pH Soil pH (AASHTO T289-91)
S Water-Soluble Sulfate Content (AASHTO T290-91,
ASTM D4327)
Chl Water-Soluble Chloride Content (AASHTO T291-91,
ASTM D4327)
S/C Swell/Collapse (ASTM D4546)
UCCS Unconfined Compressive Strength
(Soil - ASTM D2166, Rock - ASTM D7012)
R-Value Resistance R-Value (ASTM D2844)
DS (C) Direct Shear cohesion (ASTM D3080)
DS (phi) Direct Shear friction angle (ASTM D3080)
Re Electrical Resistivity (AASHTO T288-91)
PtL Point Load Strength Index (ASTM D5731)
Lithology Symbols
Asphalt
(see Boring Logs for complete descriptions)
Other Lab Test Abbreviations
Notes
SOLID-STEM
AUGER (4" OD)
Rifle-Garfield County Airport Hangar
Lots A1 and A2
FILL - Base material Topsoil CLAY (CL)
CLAY, sandy
(CL, CL-ML)SAND, claye (SC)
S=0.045%
S/C=-3.1%
5.0 ft - Noisier
drilling between 5
and 6 feet.
S/C=-1.7%
58.0
53.0
36.0
70.0
54.0
80.0
24
21
22
26
24
8
4
8
11
10
A-4 (2)
CL
A-4 (0)
CL-ML
A-4 (0)
SC
A-6 (3)
CL
A-4 (5)
CL
4.9
4.9
5.3
6.6
8.0
11.9
88.0
106.0
0.0 - 0.5 ft. (topsoil).
0.5 - 5.0 ft. Sandy CLAY to Silty,
sandy CLAY, tan, low plasticity, dry
to damp, stiff, calcareous, with
organics.
5.0 - 9.0 ft. Clayey SAND with gravel,
tan, low plasticity, dry to damp, dense.
9.0 - 10.0 ft. CLAY with sand.
10.0 - 27.0 ft. Sandy CLAY, tan, low
plasticity, dry to damp, stiff to very stiff,
calcareous, with organics, oxidized
zones.
27.0 - 30.0 ft. CLAY with sand,
red-brown, low plasticity, dry to damp,
stiff.
Bottom of Hole at 30.0 ft.
11
10
48
38
22
25
16
22
14
5-6
7-9-1
13-35
11-22-16
8-14
3-12-13
4-12
6-11-11
6-8
3.0
3.0
22.0
0.0
9.0
0.0
39.0
44.0
42.0
30.0
37.0
20.0
Boring Began: 2/24/2022
Boring Completed: 2/24/2022
Drilling Method(s): Solid-Stem Auger (4" OD)
Driller: HRL Compliance Solutions
Drill Rig: D-90
Hammer: Automatic (hydraulic), ER: %
Logged By: K. Dye
Final By: S. White
Total Depth: 30.0 ft
Ground Elevation:
Coordinates:
Location: NW corner area of lot
Weather Notes: Clear, 20F
Inclination from Horiz.: Vertical
Night Work:
-
-
-
-
-
-
Symbol
Depth
Date
Groundwater Levels:Not Observed
Elevation(feet)PAGE
1 of 1
Sample Type/DepthProject Number:222-084 Boring No.:B-1
Project
Name:
Field Notes
and
Other Lab
Tests
Drilling MethodDepth(feet)5
10
15
20
25
30
Rifle-Garfield County Airport Hangar
Lots A1 and A2
Atterberg
Limits
Fines Content(%)LiquidLimitPlasticityIndexAASHTO
& USCS
Classifi-
cations
02 BORING LOG 2021 - SPT NON-CDOT STYLE 222-084 RIFLE AIRPORT HANGAR.GPJ 2021 YEH COLORADO TEMPLATE.GDT 2021 YEH COLORADO LIBRARY - EDITING IN PROGRESS (2).GLB 3/9/22MoistureContent (%)Dry Density(pcf)Material Description
PenetrationResistanceSoil Samples
LithologyBlows
per
6 in Gravel Content(%)Sand Content(%)
R-Value=14
S/C=-2%
S=0.072%
S/C=-2%
80.0
66.0
67.0
76.0
57.0
68.0
75.0
31
27
27
28
29
30
26
15
11
12
16
15
18
11
A-6 (10)
CL
A-6 (5)
CL
A-6 (5)
CL
A-6 (9)
CL
A-6 (5)
CL
A-6 (9)
CL
A-6 (6)
CL
4.8
5.5
4.9
6.3
7.4
4.9
9.5
95.0
106.0
112.0
0.0 - 0.5 ft. (topsoil).
0.5 - 9.0 ft. Sandy CLAY, tan, low to
medium plasticity, dry to damp, very
stiff, calcareous.
9.0 - 14.0 ft. CLAY with sand, tan,
medium plasticity, dry to damp, very
stiff, calcareous.
14.0 - 23.0 ft. Sandy CLAY, tan,
medium plasticity, dry to damp, hard,
calcareous, with oxidized zones.
23.0 - 25.5 ft. CLAY with sand,
red-brown, low plasticity, dry to damp,
stiff.
Bottom of Hole at 25.5 ft.
30
16
19
15
31
13
11-19
7-7-9
5-14
6-6-9
14-17
1-3-10
0.0
2.0
3.0
0.0
1.0
2.0
3.0
20.0
32.0
30.0
24.0
42.0
30.0
22.0
Boring Began: 2/24/2022
Boring Completed: 2/24/2022
Drilling Method(s): Solid-Stem Auger (4" OD)
Driller: HRL Compliance Solutions
Drill Rig: D-90
Hammer: Automatic (hydraulic), ER: %
Logged By: K. Dye
Final By: S. White
Total Depth: 25.5 ft
Ground Elevation:
Coordinates:
Location: SE corner area of lot
Weather Notes: Clear, 30F
Inclination from Horiz.: Vertical
Night Work:
-
-
-
-
-
-
Symbol
Depth
Date
Groundwater Levels:Not Observed
Elevation(feet)PAGE
1 of 1
Sample Type/DepthProject Number:222-084 Boring No.:B-2
Project
Name:
Field Notes
and
Other Lab
Tests
Drilling MethodDepth(feet)5
10
15
20
25
Rifle-Garfield County Airport Hangar
Lots A1 and A2
Atterberg
Limits
Fines Content(%)LiquidLimitPlasticityIndexAASHTO
& USCS
Classifi-
cations
02 BORING LOG 2021 - SPT NON-CDOT STYLE 222-084 RIFLE AIRPORT HANGAR.GPJ 2021 YEH COLORADO TEMPLATE.GDT 2021 YEH COLORADO LIBRARY - EDITING IN PROGRESS (2).GLB 3/9/22MoistureContent (%)Dry Density(pcf)Material Description
PenetrationResistanceSoil Samples
LithologyBlows
per
6 in Gravel Content(%)Sand Content(%)
0.0 - 0.4 ft. 4.5 inches, (asphalt).
0.4 - 2.5 ft. 24 inches, (Base).
2.5 - 3.0 ft. Sandy CLAY, tan, dry to damp.
Bottom of Hole at 3.0 ft.
Boring Began: 2/24/2022
Boring Completed: 2/24/2022
Drilling Method(s): Solid-Stem Auger (4" OD)
Driller: HRL Compliance Solutions
Drill Rig: D-90
Hammer: Automatic (hydraulic), ER: %
Logged By: K. Dye
Final By: S. White
Total Depth: 3.0 ft
Ground Elevation:
Coordinates:
Location: Pavement at east edge of lot
Weather Notes:
Inclination from Horiz.: Vertical
Night Work:
-
-
-
-
-
-
Symbol
Depth
Date
Groundwater Levels:Not Observed
Elevation(feet)PAGE
1 of 1
Sample Type/DepthProject Number:222-084 Boring No.:B-3
Project
Name:
Field Notes
and
Other Lab
Tests
Drilling MethodDepth(feet)Rifle-Garfield County Airport Hangar
Lots A1 and A2
Atterberg
Limits
Fines Content(%)LiquidLimitPlasticityIndexAASHTO
& USCS
Classifi-
cations
02 BORING LOG 2021 - SPT NON-CDOT STYLE 222-084 RIFLE AIRPORT HANGAR.GPJ 2021 YEH COLORADO TEMPLATE.GDT 2021 YEH COLORADO LIBRARY - EDITING IN PROGRESS (2).GLB 3/9/22MoistureContent (%)Dry Density(pcf)Material Description
PenetrationResistanceSoil Samples
LithologyBlows
per
6 in
Private Hangar Lots A1 and A2 Yeh Project No. 222-084
Rifle Garfield County Airport, Rifle, Colorado
Appendix D
LABORATORY TEST RESULTS
Project No:%psfB-12.0 to 4.5Bulk-mixed samples4.9 3 39 58 24 16 8 0.045 A-4 (2) CL CLAY, sandy3.0 MC 4.9 88 3 44 53 21 17 4 -3.1 1,000 A-4 (0) CL-ML CLAY, sandy, silty6.0 to 8.0Bulk-mixed samples5.3 22 42 36 22 14 8 A-4 (0) SC SAND, clayey with gravel9.0 MC 6.6 106 0 30 70 -1.7 1,000 CLAY, with sand14.0 SPT 8.0 9 37 54 26 15 11 A-6 (3) CL CLAY, sandy29.0 MC 11.9 0 20 80 24 14 10 A-4 (5) CL CLAY with sandWater Soluble Sulfate (%)Fines < #200 (%)AtterbergLL PL PIGradationGravel > #4 (%)Sand (%)Sample LocationMoisture Content (%)Dry Density (pcf)Test BoringDepth (ft)Sample TypeUSCS Material DescriptionYEH & ASSOCIATES, INC.Summary of Laboratory Test Results222-084 Project Name: Rifle-Garfield County Airport Hangar Lots A1 and A2AASHTOR-ValueSwell (+)-Consolidation (-)MC-Indicates Modified California samplerSPT-Indicates standard split spoon samplerBulk-Indicates auger cuttings or mixed MC and SPT samplesPage 1 of 2
Project No:%psfWater Soluble Sulfate (%)Fines < #200 (%)AtterbergLL PL PIGradationGravel > #4 (%)Sand (%)Sample LocationMoisture Content (%)Dry Density (pcf)Test BoringDepth (ft)Sample TypeUSCS Material DescriptionYEH & ASSOCIATES, INC.Summary of Laboratory Test Results222-084 Project Name: Rifle-Garfield County Airport Hangar Lots A1 and A2AASHTOR-ValueSwell (+)-Consolidation (-)B-20.5 to 5Bulk 4.8 0 20 80 31 16 15 14 A-6 (10) CL CLAY with sand 1.0 MC 5.2 95 2 32 66 27 16 11 -2.0 1,000 A-6 (5) CL CLAY, sandy4.0 SPT 4.9 3 30 67 27 15 12 0.072 A-6 (5) CL CLAY, sandy9.0 MC 6.3 106 0 24 76 28 12 16 -2.0 1,000 A-6 (9) CL CLAY with sand14.0 SPT 7.4 1 42 57 29 14 15 A-6 (5) CL CLAY, sandy19.0 MC 4.9 112 2 30 68 30 12 18 A-6 (9) CL CLAY, sandy24.0 SPT 9.5 3 22 75 26 15 11 A-6 (6) CL CLAY with sandMC-Indicates Modified California samplerSPT-Indicates standard split spoon samplerBulk-Indicates auger cuttings or mixed MC and SPT samplesPage 2 of 2
Applied Normal Pressure, ksf
Applied Normal Pressure, ksf
1 3.0
2 9.0
Job No:
SW/KD
222-084 Project Name:Rifle-Garfield County Airport Hangar Lots A1 and A2 Figure No. D-1YEH & ASSOCIATES, INC.
B-1 106 6.6 -1.7 CLAY, with sand Checked By:
Soil Description
SWELL /
CONSOLIDATION
GRAPH
B-1 88 4.9 -3.1
CLAY, sandy, silty
(CL-ML)Drawn By: LVK
Swell(+) /
Consolidation(-)
(%)
Graph
Number
Boring
Number
Depth
(ft)
Natural Dry
Density
(pcf)
Moisture
Content
(%)
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
0.1 1 10Consolidation(-)/Swell(+), %Graph 2
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
0.1 1 10Consolidation(-)/Swell(+), %WATER ADDED
Graph 1
WATER ADDED
Applied Normal Pressure, ksf
Applied Normal Pressure, ksf
1 1.0
2 9.0
Job No:
Graph
Number
Boring
Number
Depth
(ft)
Natural Dry
Density
(pcf)
Moisture
Content
(%)
Soil Description
SWELL /
CONSOLIDATION
GRAPH
B-2 97 5.2 -2.0 CLAY, sandy (CL)Drawn By: LVK
Swell(+) /
Consolidation(-)
(%)
SW/KD
222-084 Project Name:Rifle-Garfield County Airport Hangar Lots A1 and A2 Figure No. D-2YEH & ASSOCIATES, INC.
B-2 106 6.3 -2.0 CLAY with sand (CL)Checked By:
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
0.1 1 10Consolidation(-)/Swell(+), %Graph 2
-6.0
-5.0
-4.0
-3.0
-2.0
-1.0
0.0
1.0
2.0
0.1 1 10Consolidation(-)/Swell(+), %WATER ADDED
Graph 1
WATER ADDED
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
4 20 406 601.5 8 14 501/2
LL %Fines
%Silt
B-1
B-1
B-1
B-1
B-1
B-1
A-4 (2)
A-4 (0)
A-4 (0)
A-6 (3)
A-4 (5)
CL
CL-ML
SC
CL
CL
39.0
44.0
42.0
30.0
37.0
20.0
3/4 3/8 16 30
PERCENT FINER BY WEIGHT1
SIEVE ANALYSIS
200
24
21
22
26
24
16
17
14
15
14
6 140310
HYDROMETER
BOREHOLE DEPTH
(ft)
AASHTO
Classification
USCS
Classification
PL PI %Gravel %Sand
%Clay
8
4
8
11
10
3.0
3.0
22.0
0.0
9.0
0.0
58.0
53.0
36.0
70.0
54.0
80.0
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
3 10024
COBBLES GRAVEL SAND SILT OR CLAY
GRAIN SIZE IN MILLIMETERS
2.0
3.0
6.0
9.0
14.0
29.0
Project No.222-084
Yeh Lab:
Date:03-09-2022 Rifle-Garfield County Airport Hangar
Lots A1 and A2Report By:
Checked By:04 GRAIN SIZE YEH 10 SAMPLES 222-084 RIFLE AIRPORT HANGAR.GPJ 2021 YEH COLORADO TEMPLATE.GDT 2021 YEH COLORADO LIBRARY.GLB 3/9/22Figure
D-3
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
4 20 406 601.5 8 14 501/2
LL %Fines
%Silt
B-2
B-2
B-2
B-2
B-2
B-2
B-2
A-6 (10)
A-6 (5)
A-6 (5)
A-6 (9)
A-6 (5)
A-6 (9)
A-6 (6)
CL
CL
CL
CL
CL
CL
CL
20.0
32.0
30.0
24.0
42.0
30.0
22.0
3/4 3/8 16 30
PERCENT FINER BY WEIGHT1
SIEVE ANALYSIS
200
31
27
27
28
29
30
26
16
16
15
12
14
12
15
6 140310
HYDROMETER
BOREHOLE DEPTH
(ft)
AASHTO
Classification
USCS
Classification
PL PI %Gravel %Sand
%Clay
15
11
12
16
15
18
11
0.0
2.0
3.0
0.0
1.0
2.0
3.0
80.0
66.0
67.0
76.0
57.0
68.0
75.0
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
3 10024
COBBLES GRAVEL SAND SILT OR CLAY
GRAIN SIZE IN MILLIMETERS
0.5
1.0
4.0
9.0
14.0
19.0
24.0
Project No.222-084
Yeh Lab:
Date:03-09-2022 Rifle-Garfield County Airport Hangar
Lots A1 and A2Report By:
Checked By:04 GRAIN SIZE YEH 10 SAMPLES 222-084 RIFLE AIRPORT HANGAR.GPJ 2021 YEH COLORADO TEMPLATE.GDT 2021 YEH COLORADO LIBRARY.GLB 3/9/22Figure
D-4