HomeMy WebLinkAbout9_Geotechnical Report_Icon Apartments_09-2017
CLIENT Braxton Apartment Group, LLC
P.O. Box 11890
Bozeman, MT 59719
ENGINEER TD&H Engineering
234 E. Babcock, Suite 3
Bozeman, MT 59715
Engineer: Ahren Hastings, PE
Table of Contents
REPORT OF GEOTECHICAL INVESTIGATION
BRAXTON MULTI-FAMILY HOUSING
BOZEMAN, MONTANA
SEPTEMBER 2017
BOZEMAN, GREAT FALLS, KALISPELL & SHELBY, MT | SPOKANE, WA | LEWISTON, ID | WATFORD CITY, ND | MEDIA, PA
Job No. B17-059
406.586.0277
tdhengineering.com
234 East Babcock Street
Suite 3
Bozeman, MT 59715
Braxton Multi-Family Housing Table of Contents
Braxton Apartment Group, LLC – Bozeman, Montana ii
1.0 EXECUTIVE SUMMARY ................................................................................................................... 1
2.0 INTRODUCTION ................................................................................................................................ 2
2.1 Purpose and Scope.................................................................................................................... 2
2.2 Project Description ..................................................................................................................... 2
3.0 SITE CONDITIONS ............................................................................................................................ 3
3.1 Geology and Physiography ....................................................................................................... 3
3.2 Surface Conditions ..................................................................................................................... 3
3.3 Subsurface Conditions .............................................................................................................. 4
3.3.1 Soils ...................................................................................................................................... 4
3.3.2 Ground Water ..................................................................................................................... 4
4.0 ENGINEERING ANALYSIS .............................................................................................................. 5
4.1 Introduction .................................................................................................................................. 5
4.2 Site Grading and Excavations .................................................................................................. 5
4.3 Shallow Spread Footing Foundations ..................................................................................... 6
4.4 Soil Retaining Structures ........................................................................................................... 6
4.5 Floor Slabs and Exterior Flatwork ............................................................................................ 7
4.6 Pavements ................................................................................................................................... 7
5.0 RECOMMENDATIONS...................................................................................................................... 9
5.1 Site Grading and Excavations .................................................................................................. 9
5.2 Conventional Shallow Foundations ....................................................................................... 10
5.3 Soil Retaining Structures ......................................................................................................... 11
5.4 Floor Slabs and Exterior Flatwork .......................................................................................... 12
5.5 Pavements ................................................................................................................................. 12
5.6 Continuing Services ................................................................................................................. 14
6.0 SUMMARY OF FIELD AND LABORATORY STUDIES .............................................................. 16
6.1 Field Explorations ..................................................................................................................... 16
6.2 Laboratory Testing ................................................................................................................... 16
7.0 LIMITATIONS .................................................................................................................................... 18
Braxton Multi-Family Housing Appendix
Braxton Apartment Group, LLC – Bozeman, Montana iii
APPENDIX
Test Pit Location Map (Figure 1)
Summary of Test Pits and Ground Water Monitoring (Figure 2)
Laboratory Test Reports (Figures 3 through 11)
Soil Classification and Sampling Terminology for Engineering Purposes
Classification of Soils for Engineering Purposes
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GEOTECHNICAL REPORT
BRAXTON MULTI-FAMILY HOUSING
BOZEMAN, MONTANA
1.0 EXECUTIVE SUMMARY
The geotechnical investigation for the proposed apartment complex to be located southwest of the
intersection between Babcock Street and Resort Drive in Bozeman, Montana, encountered surficial
topsoil and lean clay overlying native gravels. The seismic site class is D, and the risk of
seismically-induced liquefaction or soil settlement is considered low and does not warrant additional
evaluation. In our opinion, the site poses no significant geotechnical concerns provided the
recommendations provided in this report and all applicable building code standards are incorporated
into the final design and construction for the project. The site is suitable for the use of conventional
shallow foundations bearing on properly compacted native gravels and designed using a maximum
allowable bearing pressure of 3,000 pounds per square foot (psf). Similar construction is not
anticipated to realize vertical displacements exceeding ¾-inch, provided the recommendations
included in this report are followed.
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2.0 INTRODUCTION
2.1 Purpose and Scope
This report presents the results of our geotechnical study for the proposed apartment complex to be
located southwest of the intersection between Babcock Street and Resort Drive in Bozeman,
Montana. The purpose of the geotechnical study is to determine the general surface and subsurface
conditions at the proposed site and to develop geotechnical engineering recommendations for
support of the proposed structures and design of related facilities. This report describes the field
work and laboratory analyses conducted for this project, the surface and subsurface conditions
encountered, and presents our recommendations for the proposed foundations and related site
development.
Our field work included excavating 53 test pits within the limits of the proposed structures. Samples
were obtained from the test pits and returned to our Great Falls laboratory for testing. Laboratory
testing was performed on selected soil samples to determine engineering properties of the
subsurface materials. The information obtained during our field investigations and laboratory
analyses was used to develop recommendations for the design of the proposed foundation systems.
This study is in accordance with the proposal submitted by Mr. Ahren Hastings, PE of our firm dated
August 4, 2017. Our work was authorized to proceed by Mr. Will Ralph of Braxton Apartment Group,
LLC by his signed acceptance of our proposal.
2.2 Project Description
It is our understanding that the proposed project consists of multiple three-story, wood-framed
apartment buildings with associated pools, club houses, site parking and landscaping. The
structures are proposed to be supported on conventional shallow foundations incorporating interior
slab-on-grade construction. Structural loads were not available at the time of this report, but
assumed loads include wall loads on the order of 3,000 pounds per lineal foot and column loads up
to 100 kips.
Site development will most likely include landscaping, exterior concrete flatwork, and asphalt
pavement for parking lots and roadways. If loadings, locations or conditions are significantly
different from those described above, we should be notified to reevaluate the recommendations
contained in this report.
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3.0 SITE CONDITIONS
3.1 Geology and Physiography
The site is geologically characterized as containing upper tertiary sediment according to the
Montana Bureau of Mines and Geology, Geologic Map of Montana. Generally, the surface is
composed of varying thicknesses of silt and/or clay deposits overlying alluvial fan deposits of well-
graded, gravel with sand. The gravel is predominately rounded to subrounded and contains cobbles
and minor amounts of silt and/or clay. Reportedly, the local alluvial fan deposits extend down to as
much as 165 feet.
Geologic Map of Montana, Edition 1.0
Montana Bureau of Mines & Geology (2007)
The appropriate site class, per the 2012 International Building Code (IDBC), for this site is Site Class
D. Seismic ground motion values should be determined using the National Earthquake Hazards
Reduction Program (NEHRP) recommendations using the above site class. The likelihood of
seismically-induced soil liquefaction or settlement it low for this project and does not warrant
additional evaluation.
3.2 Surface Conditions
The proposed project site presently consists of an undeveloped field with native grasses. Based on
background information and site observations, the site general slopes down to the northwest at
approximately 1.5 percent and is considered relatively flat.
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3.3 Subsurface Conditions
3.3.1 Soils
The subsurface soil conditions appear to be very consistent based on our exploratory
excavating and soil sampling. In general, the subsurface soil conditions encountered within
the test pits consist of 0.3 to 1.3 feet of lean clay topsoil overlying lean clay to depths of 1.8
to 3.8 feet below the existing ground surface. The surficial clay is underlain by dense gravel
extending to a depth of at least 10.8 feet, the maximum depth investigated.
The subsurface soils are summarized on the enclosed summary of test pits and ground
water monitoring (Figure 2) and below. The stratification lines shown on the summary
represent approximate boundaries between soil types and the actual in situ transition may
be gradual vertically or discontinuous laterally.
Lean Clay
The lean clay appeared firm to stiff based on observations during excavation of the test pits.
Generally, the upper 0.3 to 1.3 feet was classified as topsoil. The unconfined compression
strength of the lean clay, as measured by a handheld Pocket Penetrometer, was less than
2.0 tons per square foot. This material is considered slightly to highly compressible
depending on water content. A single sample of the material contained 7.1 percent gravel,
11.4 percent sand, and 81.5 percent fines (silt and clay). Twelve samples of the lean clay
were tested and exhibited liquid limits ranging from 35 to 44 percent and a plasticity indices
of ranging from 13 to 25 percent. The natural moisture contents measured varied from 7 to
12 percent and averaged 8 percent.
Poorly-Graded Gravel with Sand
The poorly-graded gravel with sand appeared dense based on observations during
excavation of the test pits. A sample of the material obtained contained 70.7 percent gravel,
28.2 percent sand, and 1.1 percent fines (silt and clay).
3.3.2 Ground Water
Ground water was encountered in 45 of the 53 test pits at depths ranging from 2.5 to 8.5 feet
below the ground surface. Water levels were measured at the time of excavating and are
considered approximate due to disturbances caused by the excavations. Additionally, the
presence of observed ground water may be directly related to the time of the subsurface
investigation. Numerous factors contribute to seasonal ground water occurrences and
fluctuations, and the evaluation of such factors is beyond the scope of this report.
Perforated plastic pipes were installed in Test Pits 1, 4, 17, 23, 30, 37, 48, and 51 for future
ground water monitoring. At the time of this report, no additional ground water data had
been collected from these instruments.
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4.0 ENGINEERING ANALYSIS
4.1 Introduction
The primary geotechnical concern regarding this project is the presence of weak near surface clay
soils and high ground water. The near surface clays have poor strength properties that are further
diminished when wetted. Thus, they are not suitable to support structural loads and it will be
necessary to extend all load bearing foundation elements through the weak clay into the dense
native gravel. Exterior concrete slabs-on-grade and pavements can be constructed on the native
clay provided they are supported by an adequate granular base underlain by a geosynthetic. Due to
the cost and difficulty associated with the repair of interior slabs should undesirable slab movements
occur, the native clays are not considered suitable to support interior slab systems.
4.2 Site Grading and Excavations
The ground surface at the proposed apartment complex site is nearly level and slopes between 1
and 2 percent down toward the northwest. Based on our field work, lean clay overlying gravel with
sand will be encountered in foundation and utility excavations to the depths anticipated. Depending
on the time of year and the moisture conditions at the time of construction, the lean clay may not be
suitable for use as backfill due to the need for considerable moisture conditioning to achieve proper
compaction. Therefore, an excess of this material may be generated during excavation and
imported material may be necessary. If the native clay can be properly moisture conditioned and
compacted at the time of construction, it is considered suitable for use as exterior backfill and
general site grading fill on this project. Testing indicates the average natural moisture content of the
lean clay is approximately 8.1 percent while the optimum moisture is 16.7 percent. The long-term
performance of this material will be directly related to the compactive effort applied during
construction. In-place density testing should be conducted to monitor compliance with the
recommendations provided below.
Dense native gravel will also be encountered in foundation and utility excavations within the depths
anticipated. The dense gravel, exclusive of large cobbles and boulders, will be suitable for most site
grading and trench backfill applications. Due to the amount of cobble sized material present in the
native gravel, it will be necessary to follow good utility bedding practices during construction.
Based on the exploratory test pits, ground water should be anticipated in utility and foundation
excavations. Dewatering will be necessary in order to construct the proposed buildings and utilities.
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4.3 Shallow Spread Footing Foundations
Considering the subsurface conditions encountered and the nature of the proposed construction,
the structures can be supported on conventional shallow foundations bearing on properly
compacted native gravels or structural fill extended down to native gravels. Excess native gravel
removed from portions of the project may be reused elsewhere on site as structural fill provided it is
properly moisture conditioned and compacted during placement. Depending on the site grading for
the development, most conventional frost-depth footings are anticipated to bear upon native gravels;
however, some imported structural fill may be required, especially beneath interior bearing points
which may prefer to utilize a shallower footing depth. The volume of imported structural fill required
for this project and is partially dependent on the finished floor elevations and the amount of excess
gravel removed to reach adequate frost depth.
Based on our experience, the theory of elasticity, and using an allowable bearing pressure of 3,000
pounds per square foot (psf), we estimate the total settlement for footings will be less than ¾-inch
when constructed as recommended in this report and in accordance with all applicable building code
requirements. Differential settlements within individual structures should be on the order of one-half
this magnitude.
The lateral resistance of spread footings is controlled by a combination of sliding resistance between
the footing and the foundation material at the base of the footing and the passive earth pressure
against the side of the footing in the direction of movement. Design parameters are given in the
recommendations section of this report.
4.4 Soil Retaining Structures
Foundation walls on this project are not anticipated to support differential soil heights due to the
proposed use of slab-on-grade construction. However, other site features like the proposed
swimming pools will realize lateral pressures associated with the soil backfill, especially when
emptied for maintenance or during winter months.
The lateral earth pressures are a function of the natural and backfill soil types and acceptable wall
movements, which affect soil strain to mobilize the shear strength of the soil. More soil movement is
required to develop greater internal shear strength and lower the lateral pressure on the wall. To
fully mobilize strength and reduce lateral pressures, soil strain and allowable wall rotation must be
greater for clay soils than for cohesionless, granular soils.
The lowest lateral earth pressure against walls for a given soil type is the active condition and
develops when wall movements occur. Passive earth pressures are developed when the wall is
forced into the soil, such as at the base of a wall on the side opposite the retained earth side. When
no soil strain is allowed by the wall, this is the "at-rest" condition, which creates pressures having
magnitudes between the passive and active conditions.
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The distribution of the lateral earth pressures on the structure depends on soil type and wall
movements or deflections. In most cases, a triangular pressure distribution is satisfactory for design
and is usually represented as an equivalent fluid unit weight. Design parameters are given in the
recommendations section of this report.
4.5 Floor Slabs and Exterior Flatwork
The natural on-site soils are not suitable for the support of interior slab-on-grade construction due to
the potential for settlements and/or limited heave associated with these materials when wetted.
Therefore, it will be necessary to improve the underslab conditions to improve slab performance.
Based on the weak lean clay subsoils encountered, some slab movement is possible if any amount
of the native clay remains beneath the slab. Due to the limited thickness of lean clay encountered
on site, the complete removal of the weak clay soil down to native gravel and replacement with
compacted structural is considered feasible and is the only method capable of effectively eliminating
the risk of settlement beneath interior slabs.
4.6 Pavements
A pavement section is a layered system designed to distribute concentrated traffic loads to the
subgrade. Performance of the pavement structure is directly related to the physical properties of the
subgrade soils and the magnitude and frequency of traffic loadings. Pavement design procedures
are based on strength properties of the subgrade and pavement materials, along with the design
traffic conditions.
Traffic information was not available at the time of this report. We have assumed that traffic for the
parking lot and adjacent streets will be limited to passenger-type vehicles and occasional delivery
trucks. The anticipated subgrade material is lean clay which is classified as an A-6 soil, in
accordance with the American Association of State Highway and Transportation Officials (AASHTO)
classification. AASHTO considers this soil type to be a fair to poor subgrade. Typical California
Bearing Ratio (CBR) values for this type of soil range are less than 10 percent (According to Figure
14.2 in the Montana Department of Transportation Geotechnical Manual), which was confirmed by a
laboratory CBR test resulting in a CBR of 7.4 percent when compacted to at least 95 percent of the
maximum dry density determined using a standard proctor (ASTM D698). It will be necessary to
recompact the subgrade soils prior to placing fill material associated with the pavement section.
This may require scarification and moisture conditioning of the subgrade to achieve proper
compaction. The fill should be selected, placed, and compacted in accordance with our
recommendations.
A geotextile acting as a separator is recommended between the pavement section gravels and the
prepared clay subgrade. The geotextile will prevent the upward migration of fines and the loss of
aggregate into the subgrade, thereby prolonging the structural integrity and performance of the
pavement section. Proper installation of the geotextile is necessary for the long-term performance
of the pavement. The subgrade must have a suitable moisture content and be rolled to a smooth
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surface prior to placement of the geotextile. Subgrade which is too wet at the time of construction to
facilitate proper compaction and placement of the geotextile, should incorporate a geogrid to provide
added stability. Based on previous experience in the project area, a geogrid may be required
depending on the construction schedule. When required by site conditions, we recommend a
Tensar TX140 geogrid be used for this application. Geogrids are not always interchangeable;
therefore, any substitution requests will require an independent pavement analysis.
In our experience, achieving 95 percent compaction of the subgrade may be difficult depending on
the construction schedule due to elevated moisture contents which occur seasonally. Therefore, a
CBR value of 3.0 percent was used in design and is consistent with typical values and accounts for
the anticipated difficulty compacting the subgrade soils. The pavement sections presented in this
report are based on a CBR value of 3.0 percent, assumed traffic loadings, recommended pavement
section design information presented in the AASHTO Design Manuals, and our past pavement
design experience in the Bozeman area.
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5.0 RECOMMENDATIONS
5.1 Site Grading and Excavations
1. All topsoil and organic material should be removed from the proposed building and
pavement areas and any areas to receive site grading fill. For planning purposes, a
minimum stripping thickness of 12 inches is recommended. Thicker stripping depths
may be warranted to remove all detrimental organics as determined once actual
stripping operations are performed.
2. All fill and backfill should be non-expansive, free of organics and debris and should
be approved by the project geotechnical engineer. The on-site soils, exclusive of
topsoil, are suitable for use as exterior backfill and general site grading fill on this
project. On-site native clays are highly sensitive to varying moisture contents and
can be difficult to achieve recommended compaction densities if optimum moisture
conditions cannot be met. When native gravels are to be utilized as backfill, all
cobbles and boulders larger than 3-inch diameter should be removed or crushed
prior to use. All fill should be placed in uniform lifts not exceeding 8 inches in
thickness for fine-grained soils and not exceeding 12 inches for granular soils. All
materials compacted using hand compaction methods or small walk-behind units
should utilize a maximum lift thickness of 6 inches to ensure adequate compaction
throughout the lift. All fill and backfill shall be compacted to the following
percentages of the maximum dry density determined by a standard proctor test
which is outlined by ASTM D698 or equivalent (e.g. ASTM D4253-D4254).
a) Below Foundations or Spread Footings ...................................... 98%
b) Below Slab-on-Grade Construction ............................................. 95%
c) Exterior Foundation Backfill ......................................................... 95%
d) Below Streets, Parking Lots, or Other Paved Areas ................... 95%
e) General Landscaping or Nonstructural Areas ............................. 92%
f) Utility Trench Backfill, To Within 2 Feet of Surface ...................... 95%
3. Imported structural fill should be non-expansive, free of organics and debris, and
selected per the following gradation requirements:
Screen or Sieve Size Percent Passing by Weight
3-inch 100
1½-inch 80 – 100
¾-inch 60 – 100
No. 4 25 – 60
No. 200 10 maximum
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Native gravel which is screened to remove cobbles and boulders larger than that
specified above should satisfy this gradation requirement for use as structural fill.
4. Develop and maintain site grades which will rapidly drain surface and roof runoff
away from foundation and subgrade soils, both during and after construction. Final
site grading should comply with the project grading plan which is to be developed by
others to comply with the requirements of the applicable building codes.
5. At a minimum, downspouts from roof drains should discharge at least six feet away
from the foundation or beyond the limits of foundation backfill, whichever is greater.
All downspout discharge areas should be properly graded, by others, to drain away
from the structure and prevent ponding.
6. Site utilities should be installed with proper bedding in accordance with pipe
manufacturer’s requirements.
7. It is the responsibility of the Contractor to provide safe working conditions in
connection with underground excavations. Temporary construction excavations
greater than four feet in depth, which workers will enter, will be governed by OSHA
guidelines given in 29 CFR, Part 1926. For planning purposes, subsoils
encountered in the test pits are considered Type C. The soil conditions on site can
change due to changes in soils moisture or disturbances to the site prior to
construction. The contractor is responsible to provide an OSHA knowledgeable
individual during all excavation activities to regularly assess the soil conditions and
ensure that all necessary safety precautions are implemented and followed.
5.2 Conventional Shallow Foundations
The design and construction criteria below should be observed for a spread footing foundation
system. The construction details should be considered when preparing the project documents.
8. Both interior and exterior footings should bear on properly compacted native gravels
or compacted structural fill extending down to native gravels. Footings may be
designed using a maximum allowable soil bearing pressure of 3,000 psf provided
settlements as outlined in the Engineering Analysis are acceptable. The use of a
one-third increase in the design bearing pressure for consideration of dynamic
loading conditions is permitted for this project.
9. The top 12 inches of gravel subgrade should be compacted to 95% of the maximum
dry density as determined by ASTM D4253-D4254. Soils disturbed below the
planned depths of footing excavations should either be re-compacted or be replaced
with suitable compacted backfill approved by the geotechnical engineer.
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10. Footings shall be sized to satisfy the minimum requirements of the applicable
building codes while not exceeding the maximum allowable bearing pressure
provided in Item 8 above.
11. Exterior footings and footings beneath unheated areas should be placed at least 48
inches below finished exterior grade for frost protection.
12. The bottom of the footing excavations should be free of cobbles and boulders to
avoid stress concentrations acting on the base of the footings. Where cobbles and
boulders are present, a thin leveling course meeting the requirements of Montana
Public Works Standard Specifications (MPWSS) Section 02235 (1.5-inch minus)
should be considered. When used, the thickness of this layer should be at least 6
inches and should be compacted to the requirements of Item 2 above.
13. Lateral loads are resisted by sliding friction between the footing base and the
supporting soil and by lateral pressure against the footings opposing movement. For
design purposes, a friction coefficient of 0.50 is appropriate for footings bearing on
native gravel or imported structural fill. Lateral resistance pressure of 100 and 350
psf per foot of depth are appropriate for backfill comprised of the native clay and
gravel, respectively.
14. A representative of the project geotechnical engineer should be retained to observe
all footing excavations / backfill phases and conduct on-site testing to verify that
proper compaction has been performed.
5.3 Soil Retaining Structures
15. Soil retaining structures which are laterally supported and can be expected to
undergo only a slight amount of deflection should be designed for a lateral earth
pressure computed on the basis of an equivalent fluid unit weight of 60 pcf for
backfill consisting of the native gravel or imported 3-inch minus structural fill. To
utilize this reduced design value, all backfill within a horizontal distance equal to two-
thirds the structure height shall be comprised of compacted granular material. If
native lean clays are to be utilized as backfill, and increased equivalent fluid unit
weight of 90 pcf is appropriate.
16. The allowable bearing pressure and lateral resistance of wall footings can be
determined using the parameters given in Items 8 and 13 above.
17. Backfill placed against the sides of the footings and the base of the walls to resist
lateral loads should be placed and compacted to at least 95% of the maximum dry
density determined by a standard proctor test which is outlined by ASTM D698 or
equivalent (e.g. ASTM D4253-D4254).
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18. Backfill should be selected, placed, and compacted per Items 2 and 3 above. Care
should be taken not to over-compact the backfill since this could cause excessive
lateral pressure on the walls. Only hand-operated compaction equipment should be
used within 5 feet of walls. Native clay is not recommended as backfill due to the
difficulty to compact properly and the reduced strength when wetted. Native gravels,
less particles greater than 3 inches, or imported structural fill (Item 3) are the
preferred backfill material.
5.4 Floor Slabs and Exterior Flatwork
19. For interior slab-on-grade construction, the surficial lean clay should be completely
removed down to the native gravels and replaced with properly compacted structural
fill. Prior to placing the imported granular fill, the upper six inches of the native gravel
subgrade should be compacted per Item 2 above. All subsequent structural fill
material shall be placed and compacted in accordance with our recommendations
(Item 2).
20. Interior concrete floor slabs should be designed using a modulus of vertical
subgrade reaction no greater than 300 pounds per cubic inch (pci) when designed
and constructed as recommended above.
21. Exterior slab-on-grade construction should incorporate a compacted gravel cushion
course comprised of structural fill (Item 3) with a minimum thickness of 12 inches.
Similar construction will be susceptible to vertical movements associated with the
remaining clay soils beneath the slabs. For critical exterior surfaces which cannot
tolerate vertical settlements, the clay soils should be completely removed and
replaced as recommended in Item 19 for interior slabs.
22. Geotechnically, an underslab vapor barrier is recommended for this project due to
the relatively shallow ground water and the potential for seasonal fluctuations. We
recommend the vapor barrier consist of at least a 10-mil product but should be
specified by the architect and/or structural engineer based on interior improvements
and/or moisture and gas control requirements.
5.5 Pavements
23. The following pavement sections or an approved equivalent section should be
selected in accordance with the discussions in the Engineering Analysis.
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STREET SECTION
Section Component Section
Asphaltic Concrete Pavement 3”
1.5-inch minus Crushed Base Course 6”
4-inch minus Subbase 18”
Separation Geotextile† Mirafi 600X
Total 27”
PARKING LOT SECTION
Section Component Section
Asphaltic Concrete Pavement 3”
1.5-inch minus Crushed Base Course 6”
4-inch minus Subbase 12”
Separation Geotextile† Mirafi 600X
Total 21”
† See Item 27
24. Gradations for the crushed base courses shall conform to Section 02235 of the
Montana Public Works Standard Specifications (MPWSS). The gradation for the
subbase shall conform to Section 02234 of the MPWSS or the structural fill
gradation outlined in Item 3 above.
25. Where the existing grades will be raised more than the thickness of the pavement
section, all fill should be placed, compacted and meet the general requirements
given in Item 2 above.
26. The asphaltic cement should be a Performance Graded (PG) binder having a 58-28
grade in accordance with AASHTO MP1.
27. Subgrade should be compacted to 95% of the maximum dry density as determined
by a standard Proctor test (ASTM D698). Depending on the time of year and
moisture conditions of the native clay subgrade, it may be difficult to achieve this
compaction. Provisions should be made to allow for significant moisture conditioning
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efforts of the soil or to replace the Mirifi 600X geotextile with a combination Tensar
TX140 Geogrid over Mirafi 160N.
28. To ensure the long-term performance of the pavement systems, all surficial lean clay
may be removed and replaced with properly compacted granular materials. The
sections provided above are considered the minimum recommended section for
support upon the native clays. Where additional excavation is planned to remove
the surficial clay and improve pavement performance, the subbase course should be
increased accordingly to replace this zone. Native gravels may be used for this
application as well provided all materials larger than 3-inches are removed prior to
compaction. This complete removal and replacement of the native clay is
recommended for any pavement areas to be utilized during construction for
construction traffic.
29. Final pavement thicknesses exceeding three inches shall be constructed in two
uniform lifts.
5.6 Continuing Services
Three additional elements of geotechnical engineering service are important to the successful
completion of this project.
30. Consultation between the geotechnical engineer and the design professionals during
the design phases is highly recommended. This is important to ensure that the
intentions of our recommendations are incorporated into the design, and that any
changes in the design concept consider the geotechnical limitations dictated by the
on-site subsurface soil and ground water conditions.
31. Observation, monitoring, and testing during construction is required to document the
successful completion of all earthwork and foundation phases. A geotechnical
engineer from our firm should be retained to observe the excavation, earthwork, and
foundation phases of the work to determine that subsurface conditions are
compatible with those used in the analysis and design.
32. During site grading, placement of all fill and backfill should be observed and tested to
confirm that the specified density has been achieved. We recommend that the
Owner maintain control of the construction quality control by retaining the services of
a construction materials testing laboratory. We are available to provide construction
inspection services as well as materials testing of compacted soils and the
placement of Portland cement concrete and asphalt. In the absence of project
specific testing frequencies, TD&H recommends the following minimum testing
frequencies by used:
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Braxton Apartment Group, LLC – Bozeman, Montana Page 15
Compaction Testing
Beneath Column Footings 1 Test per Footing per Lift
Beneath Wall Footings 1 Test per 25 LF of Wall per Lift
Beneath Slabs 1 Test per 400 SF per Lift
Foundation Backfill 1 Test per 50 LF of Wall per Lift
Parking Lot & Access Roads 1 Test per 600 SF per Lift
LF = Lineal Feet SF = Square Feet
Concrete Testing
Structural Concrete† 1 Test per 50 CY per Day
Non-Structural Concrete 1 Test per Day
† Structural concrete includes all footings, stem walls, slabs, and other load bearing
elements
CY = Cubic Yards
Braxton Multi-Family Housing Summary of Field & Laboratory Studies
Braxton Apartment Group, LLC – Bozeman, Montana Page 16
6.0 SUMMARY OF FIELD AND LABORATORY STUDIES
6.1 Field Explorations
The field exploration program was conducted on August 15, 2017. A total of 53 test pits were
excavated to depths ranging from 2.5 to 10.8 feet at the locations shown on Figure 1 to observe
subsurface soil and ground water conditions. The tests pits were excavated using a rubber-tired
backhoe. The subsurface exploration and sampling methods used are indicated on the attached
test pit logs. The test pits were logged by Mr. Ahren Hastings, PE of TD&H Engineering.
Samples of the subsurface materials were obtained from spoils removed during excavation. The
corresponding depths were measured from the ground surface using a steel tape measure. The
depths and elevations of the water levels measured and the date of measurement are shown on
Figure 2.
Measurements to determine the presence and depth of ground water were made in the test pits
using a measuring tape shortly after excavation. Perforated plastic casing was installed in Test
Pits 1, 4, 17, 23, 30, 37, 48, and 51 to allow for future monitoring of water levels. The depths or
elevations of the water levels measured, if encountered, and the date of measurement are
shown on Figure 2.
6.2 Laboratory Testing
Samples obtained during the field exploration were returned to our materials laboratory where they
were observed and visually classified in general accordance with ASTM D2487, which is based on
the Unified Soil Classification System. Representative samples were selected for testing to
determine the engineering and physical properties of the soils in general accordance with ASTM or
other approved procedures.
Tests Conducted: To determine:
Natural Moisture Content Representative moisture content of soil at the time of
sampling.
Grain-Size Distribution Particle size distribution of soil constituents describing the
percentages of clay/silt, sand and gravel.
Atterberg Limits A method of describing the effect of varying water content on
the consistency and behavior of fine-grained soils.
Moisture-Density Relationship A relationship describing the effect of varying moisture
content and the resulting dry unit weight at a given
compactive effort. Provides the optimum moisture content
and the maximum dry unit weight. Also called a Proctor Curve
or Relative Density Curve.
Braxton Multi-Family Housing Summary of Field & Laboratory Studies
Braxton Apartment Group, LLC – Bozeman, Montana Page 17
UU Shear Strength (Field) The undrained, unconfined shear strength (su) of cohesive
soils as determined in the field by either a pocket
penetrometer or a hand torvane.
California Bearing Ratio The measure of a subgrade’s or granular base’s ability to
resist deformation due to penetration during a saturated
condition. Used to assist in pavement thickness designs.
The laboratory testing program for this project consisted of 22 moisture-visual analyses, two sieve
(grain-size distribution) analysis, and 12 Atterberg Limits analyses. The results of the water content
analyses are presented Figures 3 and 4. The grain-size distribution curve and Atterberg limits are
presented on Figures 5 through 8. In addition, one California Bearing Ratio (CBR) test, two
moisture-density tests were performed. The results of these tests are presented on Figures 9
through 11.
Braxton Multi-Family Housing Limitations
Braxton Apartment Group, LLC – Bozeman, Montana Page 18
7.0 LIMITATIONS
This report has been prepared in accordance with generally accepted geotechnical engineering
practices in this area for use by the client for design purposes. The findings, analyses, and
recommendations contained in this report reflect our professional opinion regarding potential
impacts the subsurface conditions may have on the proposed project and are based on site
conditions encountered. Our analysis assumes that the results of the exploratory test pits are
representative of the subsurface conditions throughout the site, that is, that the subsurface
conditions everywhere are not significantly different from those disclosed by the subsurface study.
Unanticipated soil conditions are commonly encountered and cannot be fully determined by a limited
number of soil test pits and laboratory analyses. Such unexpected conditions frequently require that
some additional expenditures be made to obtain a properly constructed project. Therefore, some
contingency fund is recommended to accommodate such potential extra costs.
The recommendations contained within this report are based on the subsurface conditions observed
in the test pits and are subject to change pending observation of the actual subsurface conditions
encountered during construction. TD&H cannot assume responsibility or liability for the
recommendations provided if we are not provided the opportunity to perform limited construction
inspection and confirm the engineering assumptions made during our analysis. A representative of
TD&H should be retained to observe all construction activities associated with subgrade
preparation, foundations, and other geotechnical aspects of the project to ensure the conditions
encountered are consistent with our assumptions. Unforeseen conditions or undisclosed changes
to the project parameters or site conditions may warrant modification to the project
recommendations.
Long delays between the geotechnical investigation and the start of construction increase the
potential for changes to the site and subsurface conditions which could impact the applicability of
the recommendations provided. If site conditions have changed because of natural causes or
construction operations at or adjacent to the site, TD&H should be retained to review the contents of
this report to determine the applicability of the conclusions and recommendations provide
considering the time lapse or changed conditions.
Misinterpretation of the geotechnical information by other design team members is possible and can
result in costly issues during construction and with the final product. We strongly advise that TD&H
be retained to review those portions of the plans and specifications which pertain to earthwork and
foundations to determine if they are consistent with our recommendations and to suggest necessary
modifications as warranted. In addition, TD&H should be involved throughout the construction
process to observe construction, particularly the placement and compaction of all fill, preparation of
all foundations, and all other geotechnical aspects. Retaining the geotechnical engineer who
prepared your geotechnical report to provide construction observation is the most effective method
of managing the risks associated with unanticipated conditions.
This report was prepared for the exclusive use of the owner and architect and/or engineer in the
design of the subject facility. It should be made available to prospective contractors and/or the
contractor for information on factual data only and not as a warranty of subsurface conditions such
as those interpreted from the test pit logs and presented in discussions of subsurface conditions
included in this report.
Prepared by: Reviewed by:
Ahren Hastings, PE Craig Nadeau, PE
Geotechnical Engineer Geotechnical Engineer
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FIGURE 4
Tested By: BL/KR WJC/KR Checked By:
Lean CLAY with Sand
Well-Graded GRAVEL with Sand
Report No. A-16456/16463-206
Report No. A-16451/16468-206
inches number
size size
0.0 7.1 11.4 81.5 CL 41 21 20
0.0 70.7 28.2 1.1 GW
3"
2"
1.5"
1"
3/4"
1/2"
3/8"
100.0
98.2
96.9
96.3
95.1
94.4
100.0
87.9
76.5
62.4
52.8
43.8
38.9
#4
#10
#20
#40
#60
#80
#100
#200
92.9
91.0
89.6
88.2
86.8
85.6
84.8
81.5
29.3
20.6
12.0
5.7
3.3
2.3
1.9
1.1
23.7114
5.0218
0.7014
1.52
33.80
Location: TP-22 & TP-33 Composite Depth: 1.0 - 2.0 ft Sample Number: A-16456/16463
Location: TP-13/TP-44 Depth: 4.0 - 5.0 ft Sample Number: A-16451/16468
Bozeman Apartment Group, LLC
Braxton Bozeman Multi-Family Housing
Bozeman, Montana
B17-059
PL PI +3" % GRAVEL % SAND % SILT % CLAY USCS LL
SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description
GRAIN SIZE REMARKS:
D60
D30
D10
COEFFICIENTS
Cc
Cu
Client:
Project:
Project No.: Figure
PE
R
C
E
N
T
F
I
N
E
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.0001 0.001 0.01 0.1 110 100
6
i
n
.
3
i
n
.
2
i
n
.
1½
i
n
.
1
i
n
.
¾
i
n
.
½
i
n
.
3/
8
i
n
.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Particle Size Distribution Report
5
Tested By: JS/KR JS JS JS JS Checked By:
Lean CLAY 35 21 14 CL
Lean CLAY 43 21 22 CL
Lean CLAY 39 22 17 CL
Lean CLAY 38 21 17 CL
Lean CLAY 44 19 25 CL
B17-059 Bozeman Apartment Group, LLC
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Client: Remarks:
Project:
Figure
Location: TP-3 Depth: 2.0 ft Sample Number: A-16445
Location: TP-9 Depth: 2.0 ft Sample Number: A-16447
Location: TP-13 Depth: 2.0 ft Sample Number: A-16449
Location: TP-17 Depth: 2.0 ft Sample Number: A-16452
Location: TP-22 Depth: 1.0 ft Sample Number: A-16454
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
0
10
20
30
40
50
60
LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML
C L o r O L
C H o r O H
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
47
LIQUID AND PLASTIC LIMITS TEST REPORT
Report No. A-16445-207
Report No. A-16447-207
Report No. A-16449-207
Report No. A-16452-207
Report No. A-16454-207
Braxton Bozeman Multi-Family Housing
Bozeman, Montana
6
Tested By: JS JS JS JS WJC Checked By:
Lean CLAY with Sand 41 21 20 88.2 81.5 CL
Lean CLAY 37 21 16 CL
Lean CLAY 36 22 14 CL
Lean CLAY 37 20 17 CL
Lean CLAY 39 23 16 CL
B17-059 Bozeman Apartment Group, LLC
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Client: Remarks:
Project:
Figure
Loc.: TP-22 & TP-33 Composite Sample No.: A-16456/16463
Location: TP-25 Depth: 2.0 ft Sample Number: A-16457
Location: TP-31 Depth: 2.0 ft Sample Number: A-16459
Location: TP-33 Depth: 1.0 ft Sample Number: A-16461
Location: TP-36 Depth: 2.0 ft Sample Number: A-16464
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
0
10
20
30
40
50
60
LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML
C L o r O L
C H o r O H
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
47
LIQUID AND PLASTIC LIMITS TEST REPORT
Report No. A-16456/16463-207
Report No. A-16457-207
Report No. A-16459-207
Report No. A-16461-207
Report No. A-16464-207
Braxton Bozeman Multi-Family Housing
Bozeman, Montana
7
Tested By: JS WJC Checked By:
Lean CLAY 37 21 16 CL
Lean CLAY 35 22 13 CL
B17-059 Bozeman Apartment Group, LLC
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No. Client: Remarks:
Project:
Figure
Location: TP-44 Depth: 2.0 ft Sample Number: A-16466
Location: TP-46 Depth: 2.0 ft Sample Number: A-16469
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
0
10
20
30
40
50
60
LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML
C L o r O L
C H o r O H
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
47
LIQUID AND PLASTIC LIMITS TEST REPORT
Report No. A-16466-207
Report No. A-16469-207 Braxton Bozeman Multi-Family Housing
Bozeman, Montana
8
BEARING RATIO TEST REPORT
ASTM D 1883-07
Project No: B17-059
Project: Braxton Bozeman Multi-Family Housing Bozeman, Montana
Location: TP-22 & TP-33 Composite
Sample Number: A-16456/16463 Depth: 1.0 - 2.0 ft
Date:
Lean CLAY with Sand
Test Description/Remarks:
ASTM D698 with 6" mold. 96-hr
soak prior to test. Represents
uncorrected proctor material.
Report No. A-16456/16463-210
Figure
107.3 18.0 41 20 CL
Material Description USCS
Max.
Dens.
(pcf)
Optimum
Moisture
(%)
LL PI
Molded
Density
(pcf)
Percent of
Max. Dens.
Moisture
(%)
Soaked
Density
(pcf)
Percent of
Max. Dens.
Moisture
(%)
CBR (%)
0.10 in. 0.20 in.
Linearity
Correction
(in.)
Surcharge
(lbs.)
Max.
Swell
(%)
1 89.2 83.1 17.8 88.1 82.1 27.9 2.0 1.8 0.000 10 1.2
2 98.4 91.7 17.8 97.4 90.8 23.8 5.8 5.0 0.000 10 1
3 105.6 98.4 17.7 104.7 97.6 20.5 9.2 9.2 0.000 10 0.9
Pe
n
e
t
r
a
t
i
o
n
R
e
s
i
s
t
a
n
c
e
(
p
s
i
)
0
70
140
210
280
350
Penetration Depth (in.)
0 0.1 0.2 0.3 0.4 0.5
Sw
e
l
l
(
%
)
0
0.4
0.8
1.2
1.6
2
Elapsed Time (hrs)
0 24 48 72 96
CB
R
(
%
)
0
3
6
9
12
Molded Density (pcf)
85 90 95 100 105 110
10 blows
25 blows
56 blows
CBR at 95% Max. Density = 7.4%
for 0.10 in. Penetration
9
Technician:
Test Procedure
2.80
0.0
1.1
Peter Klevberg, P.E.
Laboratory Manager
Relative Density, (ASTM D-4253, ASTM D-4254)
% Retained on 3"
Project: Braxton Bozeman Multi-Family Housing
Group, LLC
Date Sample Received: 8/21/2017
Attn:
Address:
Sample Source: TP-13 & TP-44 (4.0 - 5.0 ft)
REPORT OF RELATIVE DENSITY
1800 River Drive North
Great Falls, Montana 59401
Mr. Will Ralph
Report Date: 8/25/2017
Telephone: (406) 761-3010 Fax: (406) 727-2872
Bozeman, MT 59719 Sample Number: A-15451/16468 Composite
PO Box 11890 Project Number: B17-059-001
Client: Bozeman Apartment Report Number: A-16451/16468-209
Thomas, Dean & Hoskins, Inc.
CRN
Pessimum Moisture = 3.2 % Passing No. 200
Well-Graded GRAVEL with Sand
9.2
Specific Gravity
Unified Classification
Optimum Moisture =
Minimum Dry Density =
136.0
116.5
Maximum Dry Density =
115.0
120.0
125.0
130.0
135.0
140.0
0.0 2.0 4.0 6.0 8.0 10.0 12.0
Dr
y
D
e
n
s
i
t
y
(
p
c
f
)
Water Content (%)
115
120
125
130
135
140
0 10 20 30 40 50 60 70 80 90 100
lb
s
.
/
c
u
.
f
t
.
Percent Relative Density
ZAV Curve
FIGURE 10
Tested By: BL Checked By:
Moisture-Density Test Report
Dr
y
d
e
n
s
i
t
y
,
p
c
f
92
97
102
107
112
117
Water content, %
- Rock Corrected - Uncorrected
8 13 18 23 28 33 38
16.7%, 110.1 pcf
18.0%, 107.3 pcf
ZAV for
Sp.G. =
2.65
Test specification:
ASTM D4718-15 Oversize Corr. Applied to Each Test Point
ASTM D 698-12 Method A Standard
1.0 - 2.0 ft CL A-7-6(16) 2.65 41 20 7.1 81.5
Lean CLAY with Sand
B17-059 Bozeman Apartment Group, LLC
Report No. A-16456/16463-204
Elev/ Classification Nat. Sp.G. LL PI % > % <
Depth USCS AASHTO Moist. #4 No.200
ROCK CORRECTED TEST RESULTS UNCORRECTED MATERIAL DESCRIPTION
Project No. Client: Remarks:
Project:
Location: TP-22 & TP-33 Composite Sample Number: A-16456/16463
Figure
107.3 pcf Maximum dry density = 110.1 pcf
18.0 % Optimum moisture = 16.7 %
Braxton Bozeman Multi-Family Housing
Bozeman, Montana
11
Great Falls, Kalispell, Bozeman, Montana
Spokane, Washington, Lewiston, Idaho
THOMAS, DEAN & HOSKINSEngineering Consultants SOIL CLASSIFICATION AND
SAMPLING TERMINOLOGY
FOR ENGINEERING PURPOSES
12" 3" 3/4" No.4 No.10 No.40 No.200 <No.200
SILTS & CLAYSBOULDERSCOBBLESGRAVELSSANDS
PARTICLE SIZE RANGE
(Distinguished By
Atterberg Limits)FineCoarse FineMediumCoarse
Sieve Openings (Inches)Standard Sieve Sizes
CL - Lean CLAY
ML - SILT
OL - Organic SILT/CLAY
CH - Fat CLAY
MH - Elastic SILT
OH - Organic SILT/CLAY
SW - Well-graded SAND
SP - Poorly-graded SAND
SM - Silty SAND
SC - Clayey SAND
GW - Well-graded GRAVEL
GP - Poorly-graded GRAVEL
GM - Silty GRAVEL
GC - Clayey GRAVEL
* Based on Sampler-Hammer Ratio of 8.929 E-06 ft/lbf and 4.185 E-05 ft^2/lbf for
granular and cohesive soils, respectively (Terzaghi)
STANDARD PENETRATION TEST (ASTM D1586)
RELATIVE DENSITY*RELATIVE CONSISTENCY*
Granular, Noncohesive
(Gravels, Sands, & Silts)Fine-Grained, Cohesive
(Clays)
Very Loose
Loose
Medium Dense
Dense
Very Dense
Very Soft
Soft
Firm
Stiff
Very Stiff
Hard
0-2
3-4
5-8
9-15
15-30
+30
0-4
5-10
11-30
31-50
+50
Standard
Penetration Test
(blows/foot)
Standard
Penetration Test
(blows/foot)
PLASTICITY CHART
0 10 16 20 30 40 50 60 70 80 90 100 110
60
50
40
30
20
107
4
C L o r O L
C H o r O H
ML or OL
MH or OH
CL-ML
"U - L I N E "
"A - L I N E "
LIQUID LIMIT (LL)
P L A S T I C I T Y I N D E X (P I )
For classification of fine-grained soils and thefine-grained fraction of coarse-grained soils.
Equation of "A"-line
Horizontal at PI = 4 to LL = 25.5,
then PI = 0.73 (LL-20)
Equation of "U"-line
Vertical at LL = 16 to PI = 7,
then PI = 0.9 (LL-8)
Great Falls, Kalispell, Bozeman, Montana
Spokane, Washington, Lewiston, Idaho
THOMAS, DEAN & HOSKINSEngineering Consultants ASTM D2487
CLASSIFICATION OF SOILS
FOR ENGINEERING PURPOSES
Flow Chart For Classifying Coarse-Grained Soils (More Than 50 % Retained On The No. 200 Sieve)
Flow Chart For Classifying Fine-Grained Soils ( 50 % Or More Passes The No. 200 Sieve)
<5% fines
5-12% fines
>12% fines
<5% fines
5-12% fines
>12% fines
Well-graded GRAVELWell-graded GRAVEL with sandPoorly-graded GRAVELPoorly-graded GRAVEL with sand
Well-graded GRAVEL with silt
Well-graded GRAVEL with silt and sandWell-graded GRAVEL with clay (or silty clay)Well-graded GRAVEL with clay and sand (or silty clay and sand)
Poorly-graded GRAVEL with silt
Poorly-graded GRAVEL with silt and sand
Poorly-graded GRAVEL with clay (or silty clay)Poorly-graded GRAVEL with clay and sand (or silty clay and sand)
Silty GRAVELSilty GRAVEL with sandClayey GRAVELClayey GRAVEL with sandSilty, clayey GRAVEL
Silty, clayey GRAVEL with sand
Well-graded SAND
Well-graded SAND with gravel
Poorly-graded SANDPoorly-graded SAND with gravel
Well-graded SAND with silt
Well-graded SAND with silt and gravel
Well-graded SAND with clay (or silty clay)Well-graded SAND with clay and gravel (or silty clay and gravel)
Poorly-graded SAND with siltPoorly-graded SAND with silt and gravelPoorly-graded SAND with clay (or silty clay)
Poorly-graded SAND with clay and gravel
(or silty clay and gravel)
Silty SANDSilty SAND with gravelClayey SAND
Clayey SAND with gravel
Silty, clayey SAND
Silty, clayey SAND with gravel
<15% sand>15% sand
<15% sand
>15% sand
<15% sand>15% sand
<15% sand
>15% sand
<15% sand>15% sand<15% sand>15% sand
<15% sand>15% sand<15% sand>15% sand<15% sand
>15% sand
<15% gravel
>15% gravel
<15% gravel>15% gravel
<15% gravel>15% gravel<15% gravel>15% gravel
<15% gravel
>15% gravel<15% gravel>15% gravel
<15% gravel
>15% gravel<15% gravel>15% gravel<15% gravel>15% gravel
Lean CLAYLean CLAY with sandLean CLAY with gravelSandy lean CLAY
Sandy lean CLAY with gravel
Gravelly lean CLAY
Gravelly lean CLAY with sand
Silty CLAY
Silty CLAY with sand
Silty CLAY with gravel
Sandy silty CLAYSandy silty CLAY with gravelGravelly silty CLAYGravelly silty CLAY with sand
SILT
SILT with sandSILT with gravelSandy SILTSandy SILT with gravel
Gravelly SILT
Gravelly SILT with sand
Fat CLAYFat CLAY with sand
Fat CLAY with gravel
Sandy fat CLAYSandy fat CLAY with gravelGravelly fat CLAYGravelly fat CLAY with sand
Elastic SILT
Elastic SILT with sand
Elastic SILT with gravelSandy elastic SILTSandy elastic SILT with gravelGravelly elastic SILT
Gravelly elastic SILT with sand
%sand > %gravel
%sand < %gravel
<15% gravel>15% gravel<15% sand>15% sand
%sand > %gravel
%sand < %gravel<15% gravel>15% gravel<15% sand
>15% sand
%sand > %gravel%sand < %gravel
<15% gravel>15% gravel<15% sand>15% sand
%sand > %gravel%sand < %gravel<15% gravel>15% gravel<15% sand
>15% sand
%sand > %gravel
%sand < %gravel
<15% gravel>15% gravel<15% sand>15% sand
fines=ML or MH
fines=CL or CH (or CL-ML)
fines=ML or MH
fines=CL or CH (or CL-ML)
fines=ML or MH
fines=CL or CH
fines=CL-ML
fines=ML or MH
fines=CL or CH
(or CL-ML)
fines=ML or MH
fines=CL or CH
(or CL-ML)
fines= ML or MH
fines=CL or CH
fines=CL-ML
<30% plus No. 200
>30% plus No. 200
<30% plus No. 200
>30% plus No. 200
<30% plus No. 200
>30% plus No. 200
<30% plus No. 200
>30% plus No.200
<30% plus No. 200
>30% plus No. 200
Cu>4 and 1<Cc<3
Cu<4 and/or 1>Cc>3
Cu>4 and 1<Cc<3
Cu<4 and/or 1>Cc>3
Cu>6 and 1<Cc<3
Cu<6 and/or 1>Cc>3
Cu>6 and 1<Cc<3
Cu<6 and/or 1>Cc>3
CL
CL-ML
ML
CH
MH
PI>7 and plotson or above"A" - line
4<PI<7 andplots on or above"A" - line
PI<4 or plotsbelow "A" - line
PI plots on orabove "A" - line
PI plots below"A" - line
GRAVEL%gravel >
%sand
SAND%sand >%gravel
LL>50(inorganic)
LL<50(inorganic)
GW
GP
GW-GM
GW-GC
GP-GM
GP-GC
GM
GC
GC-GM
SW
SP
SW-SM
SW-SC
SP-SM
SP-SC
SM
SC
SC-SM
<15% plus No. 20015-29% plus No. 200
%sand > %gravel
%sand < %gravel
<15% plus No. 200
15-29% plus No. 200
%sand > %gravel
%sand < %gravel
<15% plus No. 200
15-29% plus No. 200
%sand > %gravel
%sand < %gravel
<15% plus No. 20015-29% plus No. 200
%sand > %gravel
%sand < %gravel
<15% plus No. 20015-29% plus No. 200
%sand > %gravel
%sand < %gravel