HomeMy WebLinkAbout010 Appendix I - Geotech Report
GEOTECHNICAL REPORT FOR:
Block 2, Lot 1 of South University
District Phase 3
Bozeman, Montana
February 2022
Project 21-197
Civil Engineering ● Geotechnical Engineering ● Land Surveying ● Construction Services
ALLIED ENGINEERING
32 Discovery Dr.
Bozeman, MT 59718
Ph: (406) 582-0221
www.alliedengineering.com
February 17, 2022
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company
c/o: Ray Brown
802 N. 3rd Avenue, Phoenix, AZ. 85003
rbrown@wentprop.com
RE: Final Geotechnical Report – Block 2, Lot 1 of South University District Phase 3
Bozeman, Montana
Dear Mr. Brown:
Please find enclosed an electronic PDF copy of our geotechnical report for the above-referenced
project.
As per our scope of work, this report presents our geotechnical assessment of the project site
and provides recommendations pertaining to site design and construction, earthwork,
foundation, slabs, walls, fill materials, asphalt driveway, and surface and subsurface drainage.
This report was prepared for use by all associated parties during the planning, design, and
construction phases of this site development project. It is important that all Contractors that are
involved with the site grading, foundation earthwork, underground utility installation, and
driveway construction are provided with copies of the report, so they are informed of the site
conditions and our construction recommendations. If you have any questions regarding this
report, please give us a call. Thank you.
Sincerely,
Allied Engineering Services, Inc.
Erik G. Schnaderbeck, PE
Geotechnical Engineer
Craig R. Madson, PE
Principal Geotechnical Engineer
enc: Final Geotechnical Report
P:\2021\21-197 Block 2, Lot 1 of South University District Phase 3\05 Design\Geotech\Report\21-197 - Block 2, Lot 1 of SUD Ph. 3 - Cover Letter - 02.17.22.docx
TABLE OF CONTENTS
INTRODUCTION ............................................................................................................................... 3
SCOPE OF WORK ............................................................................................................................. 3
GEOLOGY OF THE SITE .................................................................................................................... 3
EXPLORATIONS AND SUBSURFACE CONDITIONS ........................................................................... 4
Subsurface Explorations .............................................................................................................. 4
Subsurface Conditions ................................................................................................................. 4
Groundwater Conditions ............................................................................................................. 5
Laboratory Testing ...................................................................................................................... 6
FOUNDATION, SLAB, AND DRAINAGE RECOMMENDATIONS......................................................... 6
Seismic Design Factors ................................................................................................................ 6
Foundation Design ...................................................................................................................... 6
Foundation Bearing Criteria ........................................................................................................ 7
Lateral Earth Pressures................................................................................................................ 9
Foundation Wall Backfill.............................................................................................................. 9
Subsurface Drainage and Damp-Proofing ................................................................................. 10
Vapor Barrier ............................................................................................................................. 10
Surface Drainage Recommendations ........................................................................................ 10
Exterior Concrete and Garage Slabs .......................................................................................... 11
FOUNDATION-RELATED FILL MATERIAL RECOMMENDATIONS ................................................... 11
Excavated Foundation Soils ....................................................................................................... 11
Structural Fill ............................................................................................................................. 11
Clean Crushed Rock ................................................................................................................... 12
FILL PLACEMENT AND COMPACTION ........................................................................................... 12
PAVEMENT SECTION RECOMMENDATIONS ................................................................................. 12
UNDERGROUND UTILITY RECOMMENDATIONS ........................................................................... 14
Foundation Support of Utility Lines .......................................................................................... 14
Trench Backfill ........................................................................................................................... 14
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 2
COLD/WINTER WEATHER CONSTRUCTION .................................................................................. 14
AESI FUTURE INVOLVEMENT ........................................................................................................ 15
LIMITATIONS ................................................................................................................................. 15
REFERENCES .................................................................................................................................. 16
SUPPLEMENTAL INFORMATION
• List of Tables
o Table 1. Summary of Subsurface Conditions
o Table 2. Compaction Recommendations (Application vs. Percent Compaction)
o Table 3. Pavement Design for Stable Subgrade – Option 1
o Table 4. Pavement Design for Unstable Subgrade – Option 2
• List of Figures
o Figure 1 – Vicinity Map
o Figure 2 – Quadrangle Map
o Figure 3 – Test Pit Location Map
o Figure 4 – Geology Map
o Figure 5 – Foundation Typical – Slab-On-Grade (Option 1)
• List of Appendices
o Appendix A – Test Pit Logs
o Appendix B – Laboratory Testing Results
o Appendix C – Pavement Section Design
o Appendix D – Limitations of Your Geotechnical Report
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 3
INTRODUCTION
This report and attachments provide our geotechnical recommendations for the future
development of Block 2, Lot 1 of South University District Phase 3 on the south side of Bozeman,
Montana. The information contained herein is based on an investigation of the property’s
topographical and subsurface conditions, a review of geologic maps and literature for the project
area, and our experience with similar developments in the area. The purpose of this report is to
provide a description of the site’s soil and groundwater conditions as well as recommendations
for the design and construction of future developments proposed for the property.
The 8.60-acre property is located northeast of the Stucky Road and South 19th Avenue
Intersection. The property is situated in the Southwest ¼ of the Southwest ¼ of Section 13,
Township 2 South, Range 5 East, Principal Meridian Montana, Gallatin County, Montana. See
Figures 1 and 2 for site location maps.
The property is comprised of an undeveloped agricultural field that is relatively flat. The property
is bound to the west by South 19th Avenue, the north by State Street right-of way, the east by
South 17th Avenue right-of way, and the south by Stucky Road (currently under construction).
Site vegetation consists primarily of agricultural crops and grasses. A small stand of trees is
present along the western portion of the site adjacent to South 19th Avenue.
At this time, we understand that the development will be composed of high-density residential
housing with a mixed-use commercial element. We have not been provided with any preliminary
site plans or structure specific details at this time. Please keep us updated on development
planning so we can ensure our recommendations are appropriate and applicable.
SCOPE OF WORK
The Scope of Services for this project included:
• Excavation of six test pits within the proposed development site. Two groundwater
monitors were installed in select test pits for future monitoring. The location of each test
pit is shown in Figure 3.
• Laboratory testing of select samples from the test pits.
• Providing allowable bearing capacity criteria.
• Surface and subsurface drainage recommendations.
• Backfill material and compaction recommendations.
• Asphalt pavement section materials and design thickness.
GEOLOGY OF THE SITE
The geologic map for the area prepared by Lonn and English in 2002 indicates the site is underlain
by older alluvial deposits of braid plains (Qabo) which is described as well-rounded, moderately
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
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to well-sorted, bouldery gravel with interbedded silt. An excerpt of this mapping is provided on
Figure 4. Our test pit findings were consistent with the geologic mapping.
EXPLORATIONS AND SUBSURFACE CONDITIONS
Subsurface Explorations
Subsurface conditions were investigated on November 29, 2021, under the direction of Erik
Schnaderbeck, a professional geotechnical engineer with Allied Engineering Services, Inc. Six test
pit excavations, which are identified as TP-1 through TP-6, were excavated on the property using
a CAT 315 tracked excavator provided by SIME Construction. The test pits were spatially situated
across the property to provide coverage. Two groundwater monitors were installed in select test
pits located at the northeast and southwest portions of the property for future monitoring. It
should be noted that SIME Construction was dewatering along Stucky Road and along South 17th
Avenue for utility installation at the time of our test pit explorations. For this reason,
groundwater levels are anticipated to be much higher than what was observed during the test
pit explorations.
During the explorations, soil and groundwater conditions were characterized, measured, and
logged. The relative densities of the exposed soils were estimated based on the ease or difficulty
of digging, probing of the test pit walls, pocket penetrometer readings, and overall stability of
the completed excavations. Copies of our test pit logs are provided in Appendix A. The logs
provide assorted field information, such as soil depths and descriptions, groundwater conditions,
relative density data, and a sketch of the soil stratigraphy. Please be aware that the detail
provided in the logs cannot be summarized in a paragraph; therefore, it is important to review
the logs in conjunction with this report. Following completion of the fieldwork, the test pit
locations were backfilled and cleaned up to the extent possible. Each was staked with a wooden
lath that identified it accordingly. If any test pits will underlie future site improvements, they
should be completely re-excavated and backfilled in properly compacted lifts to avoid
undesirable settlements.
Select soil samples were brought back to the laboratory for further testing and classification.
Laboratory testing results are provided in Appendix B.
Subsurface Conditions
Soil conditions were similar in all six test pits. Topsoil consisted of about a foot of dark brown
organic sandy clay and fine roots. Fine roots in all test pits extended to approximately one foot
below the ground surface indicating that deep root penetration is not required by vegetation due
to high groundwater levels. Below the topsoil from depths of 1.0 to 5.0 feet, the test pits
encountered native, medium stiff to soft, light brown, sandy silt/clay that was very moist. It
should be noted that the sandy silt/clay became softer and moister with depth. Underlying the
sandy silt/clay deposits were alluvial deposits of dense sandy gravel with rounded cobbles that
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 5
extended to the bottom of all six test pits to depths of 12 to 13 feet. Please refer to Table 1 for
a summary of soil conditions encountered in all six test pits. All measurements are below existing
grade.
Table 1: Summary of Subsurface Conditions
TEST PIT
IDENTIFICATION
TEST PIT
LOCATION NATIVE TOPSOIL NATIVE SANDY
SILT/CLAY
NATIVE SANDY
GRAVEL
TP-1 NE Corner 0.0’ – 1.0’ 1.0’ – 4.0’
4.0’ – 12.0’
TP-2 NW Corner 0.0’ – 1.0’ 1.0’ – 5.0’ 5.0’ – 12.5’
TP-3 West Side 0.0’ – 1.0’ 1.0’ – 5.0’ 5.0’ – 13.0’
TP-4
East Side 0.0’ – 1.0’ 1.0’ – 4.0’ 4.0’ – 12.5’
TP-5 SE Corner 0.0’ – 1.0’ 1.0’ – 3.5’ 3.5’ – 12.0’
TP-6 SW Corner 0.0’ – 1.0’ 1.0’ – 4.0’ 4.0’ – 12.0’
Target foundation bearing is within the native sandy gravel deposits found at depths of 3.5 to
5.0 feet depending on location. Foundation support recommendations provided later in this
report are based on excavation to these gravels and placement of the footings either on the
native gravels or on granular structural fill placed on the native gravels.
Groundwater Conditions
As discussed earlier, dewatering activities were being conducted during our test pit explorations
for a nearby utility installation. For this reason, we anticipate that groundwater levels observed
in our test pit explorations are not a representative measure of high groundwater at the site. At
the time of the excavations in late fall, soil conditions were generally moist to very moist,
becoming wet with depth with groundwater encountered at depths of 9.0 to 11.0 feet. While
on-site during the test pit explorations, groundwater measurements were also taken in select
dewatering wells and the levels measured appeared to match the conditions found in the test
pits (depths ranging from 9.0 to 12.0 feet below existing ground surface). This leads us to believe
the regional dewatering was impacting the groundwater levels measured in our test pits.
Groundwater levels are typically near the lowest level during late fall and winter conditions.
Groundwater levels are generally highest in the late spring to early summer (following the spring
melt) and can also rise during irrigation season in July, August, and September. Our groundwater
measurements during our test pit explorations do not represent seasonal high conditions since
there were completed in the late-fall and dewatering operations were taking place at the site for
utility installation.
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 6
Mottling within the native sandy gravel deposits was observed in the test pits. Mottling can be a
result of oxidation, attributed to the presence of groundwater. Mottling was observed at depths
of 5.75 to 7.0 feet in all six test pits.
We also reviewed a nearby GWIC well log in the area to help anticipate high groundwater levels
at the site. The nearest well log (GWIC ID: 301071) measured a static water level at 5.0 feet on
April 17, 2019, prior to the seasonal peak during runoff. This well is located at the Grace Bible
Church located just southwest of the property across 19th Avenue. Based on this information,
and other information gathered from nearby sites over the years, we anticipate that seasonal
groundwater levels may rise above 4.0 feet in the area.
Laboratory Testing
Select sack samples were taken in all six test pits for moisture content testing. In addition to sack
samples taken from the explorations, a composite sample was taken of the upper fine-grain
sandy silt/clay soils at 1.5 to 2.5 feet to obtain a standard proctor of soils to be encountered
during utility and site work. The standard proctor results per ASTM D-698 indicated a maximum
dry unit weight of 101.5 pounds per cubic foot (pcf) and an optimum moisture content of 16.5
percent. It should be noted that moisture contents of the upper sandy silt/clay soils varied from
21 to 28 percent (considerably higher than the optimum moisture content). Drying and
reworking of the material may be required to achieve proper compaction. The laboratory results
are provided in Appendix B.
FOUNDATION, SLAB, AND DRAINAGE RECOMMENDATIONS
Seismic Design Factors
Based on our on-site explorations and knowledge of the area’s geology, the project site class is
Site Class D per the 2018 IBC (not Default Site Class D).
Foundation Design
Due to the presence of high groundwater, we recommend that foundations consist of slab-on-
grades with finished floor elevations raised to the extent possible. All foundations should bear
on the native sandy gravels or on structural fill that in turn bears on the native sandy gravels.
We did consider the use of crawlspace foundations at the site, but do not have enough
information currently to provide specific recommendations due to the unknown levels that
groundwater may reach (we anticipate it could rise to 4 feet or less). Future groundwater
monitoring during the spring runoff would be required to determine proper separation between
footing grades and high groundwater. If possible, we recommend maintaining a minimum of two
feet of separation between high groundwater and the bottom of footings (in crawlspace
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
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applications). This would likely place footings at no greater than two feet below the native
ground surface.
Note that providing appropriate separation in crawlspace applications will require additional
structural fill to extend from the target bearing sandy gravels encountered at 3.5 to 5.0 feet
below existing grade up to footing grade. Achieving this separation will also result in higher
finished grades across the site to maintain 4 feet of cover for frost protection, increasing costs
associated with fill. Substantial subsurface drainage measures will also likely need to be
implemented in crawlspace applications given the possibility of water intrusion into the
crawlspace. Clean crushed rock would be recommended to infill the crawlspace up to top of
footings. Given the flatness of the site, perimeter footing drains and sub-drains in the crawlspace
will need to connect to an exterior sump to pump out any water. Based on our experience with
other projects in the City of Bozeman and surrounding area, there are associated challenges with
pumping out groundwater and re-routing the water away from the structures to an acceptable
location that does not impact surrounding structures. If crawlspace foundations are desired,
please let us know so we can be involved with the design process and perform groundwater
monitoring.
Foundation Bearing Criteria
The upper sandy silt/clay found at the site are prone to excessive settlement (over an inch) under
anticipated foundation loads. For this reason, we recommend over-excavating to the native
sandy gravel (found at a depth of 3.5 to 5.0 feet) and bearing footings on this material or
granular structural fill that is founded on the native sandy gravel. For frost protection, exterior
footings should bear at a depth of four feet below the lowest adjacent finished grade.
In a slab on grade application or an elevated crawlspace, two options exist with respect to the
installation of the structural fill (if needed) to extend from the target bearing native sandy gravels
up to the bottom of footings:
1. The first option is to mass-excavate within the footprint of the structures down to the
target bearing native sandy gravels (and extending outward at least 2 feet) and replace
with compacted structural fill (road mix or pit-run gravel). This may be the easiest option
if there are a significant number of interior spread footings that need to be dug out as
well. Please refer to Figure 5 for details.
2. A second option to perhaps save on foundation preparation costs is to leave the non-
organic sandy silt/clay under the interior slab and only dig out the footings individually
down to the native gravels, using compacted structural fill as needed to build back up to
footing elevation. To ensure load transfer occurs in the structural fill, the required width
of the excavation is the width of the footing plus the depth of structural fill measured
from the bottom of footing to the native gravels (essentially a load transfer of 2V:1H). For
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 8
instance, if the width of the footing is 2 feet and the thickness of structural fill extending
from the bottom of footing to native gravels is 2 feet, the width of the excavation would
need to be 4 feet. This assumes the footing is centered on the structural fill.
With Option 2, lightly loaded interior slabs would be supported by the native non-organic
fine-grained soils and a section of structural fill. We recommend against supporting any
portion of interior slabs on organic soils since these soils will be prone to settlement
depending on the degree of organics present. Organic soils should be completely
removed and the non-organic fine-grained subgrade proof-rolled to a dense, unyielding
condition. Please recognize that the upper sandy silt/clay soils were very moist and may
be soft upon excavation. Drying and scarifying of the surface may be needed to compact
the subgrade to an unyielding condition. On top of the prepared subgrade, we
recommend placing a woven geotextile fabric (Mirafi 600X or approved equivalent),
followed by 18 inches of structural fill and 6 inches of crushed drainage rock directly under
the slab. If the entirety of the building footprint will be excavated to the native gravels
and replaced with granular structural fill, fabric reinforcement is not required.
Our experience is that there is often a balance between leaving some of the fine-grain soils under
the slabs and individually digging the spread footings and perimeter footings down to the native
gravels versus the ability to utilize larger construction equipment and excavating everything
down to the gravel. In the case of the latter, more gravel is used; however, the work can proceed
much faster with the use of the larger equipment. We suggest consulting with a foundation
excavation contractor to determine which option will be the most cost effective for this
development.
In the event groundwater is encountered at the bottom of the excavation, clean crushed rock
may be placed to raise the bottom of the excavation above the groundwater before switching to
more traditional structural fill (pit-run or crushed sandy gravel). Providing separation from
groundwater using the non-moisture-sensitive clean crushed rock will avoid the saturation of the
structural fill and subsequent difficulty with compaction. Clean crushed rock should be placed in
lifts not exceeding 12 inches loose and vibratory compacted. Clean crushed rock should be
covered with a nonwoven geotextile fabric such as a Mirafi 180N or equal prior to structural fill
placement to prevent the migration of fines into the crushed rock. Structural fill shall be placed
in lifts and compacted to 98 percent of its Standard Proctor Density based on ASTM D-698.
Further details on lift thickness and compaction requirements are provided later in this report.
Prior to pouring footings or placing structural fill (if used), the native subgrade should be proof-
rolled to an unyielding condition. Any soft or overly moist areas should be removed and replaced
with lifts of structural fill compacted to a dense, unyielding condition. A leveling course of crushed
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rock or road mix may be used if there are excessive large rocks in the subgrade that would create
an uneven bearing surface.
An appropriate bearing capacity for design assuming conventional spread and continuous
footings is 3,000 pounds per square foot (psf). Total settlements are estimated to be under 0.75
inches with minimal differential settlements. Allowable bearing pressures during earthquakes
may be increased by 50 percent.
Lateral Earth Pressures
All foundation walls that will be fixed at the top prior to the placement of backfill should be
designed for an “at rest” equivalent fluid pressure of 60 pounds per cubic foot (pcf). In contrast,
cantilevered retaining walls may be designed for a lower, “active” equivalent fluid pressure of 45
pcf, provided either some slight outward rotation of the wall is acceptable upon backfilling, or
the wall is constructed in such a way that accommodates the expected rotation. The “at rest”
and “active” design values are only applicable for walls that will have backfill slopes of less than
ten percent and will not be externally loaded by surface pressures applied above and/or behind
the wall. These lateral earth pressures also assume proper subsurface drainage provisions
(footing drains) are installed to prevent the development of hydrostatic pressures.
Lateral forces from wind, earthquakes, and earth pressures on the opposite side of the structure
will be resisted by passive earth pressure against the buried portion of the foundation wall and
by friction at the bottom of the footing. Passive earth pressures in compacted backfill should be
assumed to have an equivalent fluid pressure of 280 pcf; while a coefficient of friction of 0.4
should be used between cast-in-place concrete and the native gravels or granular structural fill.
Actual footing loads (not factored or allowable loads) should be used for calculating frictional
resistance to sliding along the base of the footing. Please be aware that the friction coefficient
has no built-in factor of safety; therefore, an appropriate safety factor should be selected and
used in all subsequent calculations for each load case.
The lateral earth pressures summarized above are for static conditions and should be factored
for seismic conditions.
Foundation Wall Backfill
Exterior wall backfill can consist of any excavated foundation soil, other than topsoil, provided it
is not overly moist, highly plastic, or too rocky in composition. The native soils may require drying
to re-use as backfill. All select backfill materials should be placed in multiple lifts and properly
compacted to 95 percent of their Standard Proctor density. Foundation walls intended to be
braced should not be backfilled until the bracing (such as floor joists) is in place to prevent
unintended rotation/deflection of the wall. To prevent damaging foundation walls during the
backfilling process, only hand-operated compaction equipment is recommended within three
feet of walls that are not buried on both sides. To minimize the potential for future settlement
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
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problems, the level of care (with respect to the selection of dry backfill materials and the
compactive effort that is used) should be increased significantly in those areas that will receive
concrete/asphalt surfacing or that will support a retaining wall. Finally, the re-use of topsoil as
backfill should be limited to the uppermost four to six inches in landscaped areas.
Subsurface Drainage and Damp-Proofing
If a crawlspace is used, we recommend installing a footing drain around the perimeter of the
foundation consisting of a 4-inch perforated pipe encased in clean, crushed rock and burrito-
wrapped in a nonwoven drainage fabric. The drains should be daylighted downslope, or if
daylighting is impractical given the flatness of the site, we suggest taking the drains to an exterior
sump with a pump. As discussed earlier, it may be difficult to find a suitable area to pump the
water given the flatness of the site.
In addition, a network of perforated 4-inch subdrain pipe should be placed within the free-
draining crushed rock infill in the crawlspace. The subdrain pipe should likewise be taken to a
sump with a pump (or daylighted if possible). The network of pipe in the crawlspace should be
covered with the free-draining clean crushed rock placed to the top of footing and covered with
a vapor barrier as described below. A rat slab could be constructed on top of the vapor barrier
and crushed rock if desired.
Perimeter footing drains for slab-on-grade foundations are not necessary unless the exterior
grade will extend above the top of slab (which is normally not likely).
Buried foundation walls should be damp-proofed with an acceptable commercial product as per
the requirements of the International Building Code (IBC 2018).
Vapor Barrier
To control moisture vapor, we recommend installing a heavy-duty vapor barrier under interior
slabs or over the top of crawlspace subgrades. We recommend a vapor barrier with a water vapor
transmission rate of 0.006 or lower as established by ASTM E 96, such as a Stego 15-mil Vapor
Barrier. The vapor barrier should be installed as per the manufacturer recommendations and
ASTM E 1643, ensuring it is properly attached to footings/walls and sealed at the seams.
Surface Drainage Recommendations
No water should be allowed to accumulate against or flow along any exposed foundation walls.
Concrete or asphalt surfacing that abuts the foundation should be designed with a minimum
grade of 2 percent away from the structure, and adjacent landscaped areas should have a slope
of at least 5 percent within 10 feet of the wall (see the IBC building codes). Do not route water
to subsurface footing and foundation drains. To further reduce the potential for moisture
infiltration along foundation walls, backfill materials should be well-compacted. The upper 4 to 6
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
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inches of backfill should consist of low permeability topsoil. Except for the locations that will be
surfaced by concrete or asphalt, finished grades next to foundation walls should be set no less
than 6 inches below the top of the sill plate.
Exterior Concrete and Garage Slabs
Depending on site grading, lightly loaded exterior concrete slabs can either be supported on a
minimum of 6 inches of clean crushed rock overlying 6 inches of granular structural fill that bears
on non-organic, native soils or on embankment fill material that is placed above the stripped
subgrade surface to raise design elevations. Traffic loaded exterior slabs should be underlain by
a minimum of 6 inches of clean crushed rock and 12 inches of granular structural fill with a woven
geotextile fabric (315 lb. woven fabric or approved equivalent) placed over compacted and
unyielding subgrade.
Thickening the crushed rock layer to greater than six inches will improve the drainage capacity
under the slab as well as provide additional separation from the underlying soils. Consequently,
the frost heave potential of the slab should be reduced. We suggest that critical exterior slab
areas which cannot undergo any heaving be underlain by additional crushed rock and two inches
or more of below grade insulation extending outward two feet from the edge of the slab to limit
frost penetration. Prior to placing any embankment fill or structural fill, both of which must be
adequately compacted, the subgrade surface should be proof-rolled to confirm its stability. If
soft or wet areas are identified, they should be over-excavated and replaced with compacted
structural fill.
FOUNDATION-RELATED FILL MATERIAL RECOMMENDATIONS
Excavated Foundation Soils
All topsoil should be stripped and stockpiled for re-use during site reclamation. On-site soils
suitable for re-use as site fill or backfill should be separated from wet, rocky, or otherwise
unsuitable soils during excavation. The suitability of the non-organic excavated soils will depend
on their rockiness, plasticity, natural moisture content, and ability to be re-compacted. The driest
soils containing an even mixture of soil matrix and smaller rock fragments should be selected for
use as compacted fill, while the wettest and rockiest soils should either be hauled off-site or used
for general site grading in non-critical locations. Depending on the time of year, some of the
native soil that is excavated may be wet of optimum and will require drying prior to re-use. This
may necessitate the import of easily compacted fill material if work is conducted during the wet
or winter season when drying is not an option.
Structural Fill
If needed, import granular structural fill for the project should consist of organic-free, well-
graded 4-inch-minus sandy (pit-run) gravel or 1.5-inch-minus crushed road mix gravel. The
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
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Page 12
gravels shall meet the material and gradation specifications as presented in the Montana Public
Works Standard Specifications (MPWSS) for sub-base course and base course gravel.
Clean Crushed Rock
The primary uses for clean crushed rock include placement under concrete slabs and behind
foundation and retaining walls for drainage-related purposes. It may also be used to bring the
subgrade up above the groundwater level in below foundation applications. Crushed rock shall
consist of a clean assortment of angular fragments with 100 percent passing a one-inch screen
and less than 1 percent (by weight) finer than the No. 100 sieve. Over 50 percent of the rock
particles must have fractured faces.
FILL PLACEMENT AND COMPACTION
All fill materials should be placed in uniform, horizontal lifts and compacted to an unyielding
condition. The “loose” thickness of each layer of fill prior to compaction should not exceed 10
inches for self-propelled rollers, 6 inches for remote-controlled trench rollers, and 4 inches for
plate compactors. The moisture content of any fill material to be compacted should be within 2
percent of its optimum value. Table 1 below provides our compaction recommendations for
general site applications. These recommendations apply to all fill materials and are presented as
a percentage of the maximum dry density of the material being placed as defined by ASTM D-
698. A common misconception is that washed or screened crushed rock does not require
compaction. However, this material does require compaction with a vibratory plate or smooth
drum roller.
Table 2. Compaction Recommendations (Application vs. Percent Compaction)
APPLICATION % COMPACTION
Granular Structural Fill Under Footings and Interior Slabs: 98
Embankment Fill Under Exterior Slabs: 95
Backfill Behind Foundation: 95
Clean Crushed Rock Under Slabs: N/A (Vibration Required)
Sub-base and Base Course Materials for Asphalt Pavement: 95
PAVEMENT SECTION RECOMMENDATIONS
Due to the anticipated soft subgrade conditions across the site and intended uses for roads, we
have recommended separate pavement sections for local streets and parking areas assuming
stable and moderately unstable subgrade conditions. See Appendix C for design calculations.
For local roads including side streets, accesses, parking areas, and driveways, we assumed a
design ESAL of 150,000 and a 20-year design life. We have not been provided with any
preliminary site plans and layouts at this time, so if our assumptions to do not apply please let us
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 13
know so appropriate recommendations can be provided. Table 3 presents the minimum
pavement section for local streets assuming stable subgrade conditions (i.e., the upper 8 inches
of native soil can be compacted to 95-percent of ASTM D-698, no rutting or deflecting, dry
subgrade, etc).
Table 3. Pavement Section 1 – Local Streets/Parking Areas – 150,000 ESALs – Stable Subgrade
MATERIAL COMPACTED THICKNESS (IN)
Asphalt 3
Base Course Gravel 6
Sub-Base Course Gravel 15
315 lb. Woven Geotextile Fabric (Mirafi 600X) Yes
Stable Subgrade Soils (less Topsoil) Compacted to 95%
TOTAL SECTION DESIGN THICKNESS 24
Please recognize that the section above is only applicable to stable subgrade conditions (no
rutting, deflecting, etc). Given the subgrade was very moist (wet of optimum) and became
softer with depth, it should be anticipated that the subgrade will likely need to be dried,
scarified, and re-worked to achieve adequate compaction to a stable condition prior to placing
fabric and sub-base gravel.
Should widespread moderately unstable subgrade conditions (minor rutting and deflecting, very
moist subgrade, etc.) occur across the site, an additional pavement section has been provided.
Table 4 presents an alternative section for local roads and parking areas if stable subgrade
conditions cannot be achieved during road construction prior to placing fabric and sub-base. We
suggest incorporating a bid item within the contract documents in the event unstable subgrade
conditions are encountered. The option for moderately unstable subgrade listed in Table 4
includes 6 additional inches of sub-base gravel and the utilization of a stronger subgrade
stabilization fabric comprised of a combination of geogrid and a non-woven geotextile fabric
placed over subgrade.
Table 4. Pavement Section 2 – Local Streets/Parking Areas – 150,000 ESALs – Unstable
MATERIAL COMPACTED THICKNESS (IN)
Asphalt 3
Base Course Gravel 6
Sub-Base Course Gravel 21
Tensar TX-190L Geogrid Reinforcement Yes
8-ounce non-woven geotextile fabric (Mirafi 180N) Yes
Moderately Unstable Subgrade (Less Topsoil) Compacted to Extent Possible
TOTAL SECTION DESIGN THICKNESS 30
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221
Page 14
We should be retained during construction of roadways/parking areas to evaluate the severity of
any unstable conditions encountered and the use of higher strength fabrics or increasing the sub-
base section. In the event highly unstable subgrade conditions (severe rutting and deflecting)
are encountered we recommend adding 6 to 12 inches of additional sub-base gravel to the
pavement section listed in Table 4.
The sub-base and base course materials that comprise the granular parts of the pavement section
shall consist of 6-inch minus uncrushed sandy (pitrun) gravel and 1-1/2-inch minus crushed (road
mix) gravel, respectively. Both gravel courses shall meet the material and gradation specifications
presented in MPWSS, Sections 02234 and 02235. Under normal circumstances, the gravel
products should be placed in lifts not exceeding 12 inches in thickness (depending on the size of
the compactor) and compacted to at least 95 percent of the maximum dry density as defined in
ASTM D-698. However, if the subgrade soils are found to be overly moist, soft, or unstable, the
initial lift thickness of the sub-base gravel should be thickened to prevent damaging and tearing
the geotextile fabric with construction equipment and bridge unstable subgrade.
UNDERGROUND UTILITY RECOMMENDATIONS
Foundation Support of Utility Lines
Exterior utility lines (water, sewer, and dry utilities) can be adequately supported by the native
gravels. Should utility lines be supported by the upper fine-grained soils that were very moist and
soft, Type 2 bedding may be required by the Engineer to support the lines. We recommend a bid
item be included on the bid form in case Type 2 bedding is deemed necessary. We suggest proper
bedding of all utilities following the specifications found in the Montana Public Works Standard
Specifications.
Trench Backfill
Trench backfill can consist of any native material (except materials containing significant
organics) that is not overly wet. Due to the very moist and soft upper fine-grained soils, we
recommend that a bid item be included in the bid form should import material be needed for
trench backfill. We recommend that trench backfill be compacted to a minimum of 95 percent
of ASTM D-698 under pavement/slab areas and 92 percent in landscaped areas.
COLD/WINTER WEATHER CONSTRUCTION
If foundation construction will occur during the cold/winter weather season, the Contractor shall
take all necessary precautions to prevent the earthwork from freezing and/or from being
contaminated with snow. Exposed subgrade and fill materials (under footings, slabs, and walls)
should be adequately covered with concrete insulation blankets to prevent frost penetration and
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221 Page 15
to protect them from snow. All soils that are used for fill under or around foundation components
should be relatively dry, free of intermixed snow and frozen clods, and must not be placed when
it is snowing. Fill materials or foundations should not be placed over frozen soils, which may be
in a “frost-heaved condition,” or over layers of snow. When earthwork will proceed during the
non-optimal times of the year, we recommend that it be performed expeditiously to minimize
the time that the foundation excavation is open and exposed to the elements.
AESI FUTURE INVOLVEMENT
We suggest that we be retained during the design to ensure that the recommendations provided
herein are followed. We further recommend that we be allowed to view the construction
excavation to verify that the appropriate target bearing materials have been reached.
LIMITATIONS
This report provides our geotechnical-related recommendations for Block 2, Lot 1 of the South
University District Phase 3 located in Bozeman, Montana. Please be advised that this report is
only applicable for the above-referenced project and shall not be used for other nearby projects.
The recommendations presented herein are primarily based on observation and evaluation of
the site’s surface and subsurface conditions, along with review and interpretation of geologic
maps, and previous engineering experience within the project area. If during earthwork
construction, soil and groundwater conditions are found to be inconsistent with those described
in the report, we should be advised immediately so the situation can be analyzed, and
recommendations can be modified as needed.
All individuals associated with this project should consult this report during the planning, design,
and construction of the site improvements. It should be made available to other parties for
information on factual data only and not as a warranty of actual subsurface conditions such as
those interpreted herein.
We appreciate the opportunity to provide our geotechnical services. If you have any questions,
please call.
Allied Engineering Services, Inc.
Erik G. Schnaderbeck, PE
Geotechnical Engineer
Craig R. Madson, PE
Principal Geotechnical Engineer
CV QOZP Stucky Bozeman, LLC, a Delaware limited liability company Geotech Rpt– Blk 2, Lot 1 of S.U.D Phase 3
February 17, 2022 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582-0221 Page 16
REFERENCES
1.International Code Council, 2018. “2018 International Building Code”.
2.Montana Contractors’ Association, April 2010. “Montana Public Works Standard
Specifications”, Sixth Edition.
3.Lonn, J. and English, A (2002). “Preliminary Geologic Map of the Eastern Part of the Gallatin
Valley Montana”, MBMG Open-File Report 457.
qa/qc: JGE
P:\2021\21-197 Block 2, Lot 1 of South University District Phase 3\05 Design\Geotech\Report\21-197 - Block 2, Lot 1 of SUD Ph.
3 - Geotech Report - 02.17.22.docx
LIST OF FIGURES
FFiigguurree 11 –– VViicciinniittyy MMaapp
FFiigguurree 22 –– QQuuaaddrraannggllee MMaapp
FFiigguurree 33 –– TTeesstt PPiitt LLooccaattiioonn MMaapp
FFiigguurree 44 –– GGeeoollooggyy MMaapp
FFiigguurree 55 –– FFoouunnddaattiioonn TTyyppiiccaall––SSllaabb--OOnn--GGrraaddee ((OOppttiioonn 11))
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
BLOCK 2, LOT 1 OF S. UNIVERSITY DIST.
VICINITY MAP
BOZEMAN, MONTANA
1
N
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
BLOCK 2, LOT 1 OF S. UNIVERSITY DIST.
QUADRANGLE MAP
BOZEMAN, MONTANA
2
N
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
BLOCK 2, LOT 1 OF S. UNIVERSITY DIST.
TEST PIT LOCATION MAP
BOZEMAN, MONTANA
3
TP#
TP-1
MW#N
MW-1
TP-2
TP-6
MW-2
TP-4
TP-3
TP-5
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
BLOCK 2, LOT 1 OF S. UNIVERSITY DIST.
GEOLOGY MAP
BOZEMAN, MONTANA
4
N
Figure 521-197Jan 2022Block 2, Lot 1 of South University District Phase 3Foundation Typical - Slab-On-Grade (Option 1)Bozeman, MontanaLegendFoundation Backfilland Embankment FillNative Sandy Gravel(”Target” Bearing Material)ConcreteNative TopsoilLow Permeable TopsoilNot To ScaleCivil EngineeringGeotechnical EngineeringLand Surveying32 Discovery DriveBozeman, MT 59718Phone: (406) 582-0221Fax: (406) 582-5770Native Fine-Grained Soil(Sandy Silt/Clay)Granular Structural FillClean Crushed RockGroundwaterFinished Floor Elevation15 mil Polyethylene Vapor Barrier (typ.)ExistingGroundReviewed By:EGS/CRM Jan. 20226” (min.) Clean Crushed Rock Under SlabMass Over-Excavate Entire Foundation Footprint And Place Granular StructuralFill From Excavated Gravel Surface Up To Perimeter And Interior Footing Grades.Perimeter FootingInterior FootingImportant Note: Increase The Level Of Care For Wall BackfillAnd Compaction In Areas That Will Receive Concrete Slabs.Finished Landscape GradeTo Slope Away @ 5% (min.).Upper 4” - 6” Of FoundationBackfill Should Consist OfLow Permeable Topsoil.2’ (min.)6” (min.)Raise FF Above Existing Grades As HighAs Site Grading Will Allow.Depth Of Cover ForFrost Protection4’ (min.)Width Of MassOver-ExcavationExcavated Gravel Surface Should Be “Clean” Sandy Gravel. Re-Compact To An Unyielding Condition Prior To Placement Of Structural Fill.3.5’ to 5’ (approx.)Depth To“Target” GravelAll Fill Materials Shall Be Placed And Compacted InAccordance With The Specifications In The Report.All Footings Must Bear Directly On Native Gravel Or OnStructural Fill That In Turn Is Supported On Native Gravel.Foundation Walls to be Damp-Proofed. No Footing Drain IsRequired Unless Exterior Grade Will Extend Above Top of Slab
LIST OF APPENDICES
AAppppeennddiixx AA –– TTeesstt PPiitt LLooggss
AAppppeennddiixx BB –– LLaabboorraattoorryy TTeessttiinngg RReessuullttss
AAppppeennddiixx CC –– PPaavveemmeenntt SSeeccttiioonn DDeessiiggnn
AAppppeennddiixx DD –– LLiimmiittaattiioonnss ooff YYoouurr GGeeootteecchhnniiccaall RReeppoorrtt
APPENDIX A
TTeesstt PPiitt LLooggss
{0.0' - 1.0'}: Native Topsoil:Medium stiff; dark brown to black; organicsandy SILT/CLAY with fine roots; very moist.·Fine roots extend to 12".{1.0' - 4.0'}: Fine-Grained Deposit:Medium stiff to soft; light brown; sandySILT/CLAY; very moist.·Pocket Penetrometer = 1.0 tsf. at 1.5'.·Pocket Penetrometer = 0.5 tsf. at 2.0'.·Pocket Penetrometer = 0.5 tsf. at 3.0'.·Becoming softer with depth.·Significant moisture increase below 2.0'.{4.0' - 12.0'}: Alluvium:Dense; dark brown with some orange mottling;sandy GRAVEL with 8"-minus rounded cobbles;moist to wet.·Target bearing at 4.0' .·Mottling observed below 6.0'.·Groundwater encountered at 9.0'·Wet material beginning at 7.0'.Notes:1.Onsite dewatering system in use for utilityinstallation (groundwater anticipated to behigher).2.4" PVC piezometer installed in test pit(MW-1).12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA21-19712.0'9.0'Test Pit Designation: TP-1 (NE Corner) Location:Surface Elevation: Backhoe Type: CAT 315C Job Number:Total Depth: Backhoe Operator: Scott w/SIME Project: Block 2, Lot 1 of South University Dist. Ph. 3Groundwater: Logged By: EGS (AESI) Date: November 29, 2021S1-A@2.0'45.65808, -111.06069(See Map)Target Bearing at 4.0'25.8%3691215GW at 9.0'15129631323S1-B@3.0'25.7%S1-C@8.0'5.9%
{0.0' - 1.0'}: Native Topsoil:Medium stiff; dark brown to black; organicsandy SILT/CLAY with fine roots; very moist.·Fine roots extend to 12".{1.0' - 5.0'}: Fine-Grained Deposit:Medium stiff to soft; light brown; sandySILT/CLAY; very moist.·Pocket Penetrometer = 1.0 tsf. at 2.0'.·Pocket Penetrometer = 0.5 tsf. at 3.0'.·Pocket Penetrometer = 0.5 tsf. at 4.0'.·Becoming softer with depth.·Significant moisture increase below 2.0'.{5.0' - 12.5'}: Alluvium:Dense; dark brown with some orange mottling;sandy GRAVEL with 6"-minus rounded cobbles;moist to wet.·Target bearing at 5.0' .·Mottling observed below 7.0'.·Groundwater encountered at 9.5'·Wet material beginning at 9.0'.Notes:1.Onsite dewatering system in use for utilityinstallation (groundwater anticipated to behigher).12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA21-19712.5'9.5'Test Pit Designation: TP-2 (NW Corner) Location:Surface Elevation: Backhoe Type: CAT 315C Job Number:Total Depth: Backhoe Operator: Scott w/SIME Project: Block 2, Lot 1 of South University Dist. Ph. 3Groundwater: Logged By: EGS (AESI) Date: November 29, 2021S2-A@2.0'45.65809, -111.06197(See Map)Target Bearing at 5.0'22.4%3691215GW at 9.5'15129631323S2-B@4.0'28.3%S2-C@6.0'3.9%
{0.0' - 1.0'}: Native Topsoil:Medium stiff; dark brown to black; organicsandy SILT/CLAY with fine roots; very moist.·Fine roots extend to 12".{1.0' - 5.0'}: Fine-Grained Deposit:Medium stiff to soft; light brown; sandySILT/CLAY; very moist.·Pocket Penetrometer = 1.0 tsf. at 1.5'.·Pocket Penetrometer = 0.75 tsf. at 2.0'.·Pocket Penetrometer = 0.5 tsf. at 3.0'.·Pocket Penetrometer = 0.5 tsf. at 4.0'.·Becoming softer with depth.·Significant moisture increase below 2.0'.{5.0' - 13.0'}: Alluvium:Dense; dark brown with some orange mottling;sandy GRAVEL with 8"-minus rounded cobbles;moist to wet.·Target bearing at 5.0' .·Mottling observed below 7.0'.·Groundwater encountered at 9.5'·Wet material beginning at 8.5'.Notes:1.Onsite dewatering system in use for utilityinstallation (groundwater anticipated to behigher).12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA21-19713.0'9.5'Test Pit Designation: TP-3 (West Side) Location:Surface Elevation: Backhoe Type: CAT 315C Job Number:Total Depth: Backhoe Operator: Scott w/SIME Project: Block 2, Lot 1 of South University Dist. Ph. 3Groundwater: Logged By: EGS (AESI) Date: November 29, 2021S3-A@2.0'45.65756, -111.06197(See Map)Target Bearing at 5.0'24.1%3691215GW at 9.5'15129631323S3-B@4.0'28.1%S3-C@6.0'3.9%
{0.0' - 1.0'}: Native Topsoil:Medium stiff; dark brown to black; organicsandy SILT/CLAY with fine roots; very moist.·Fine roots extend to 12".{1.0' - 4.0'}: Fine-Grained Deposit:Medium stiff to soft; light brown; sandySILT/CLAY; very moist.·Pocket Penetrometer = 1.0 tsf. at 1.5'.·Pocket Penetrometer = 0.5 tsf. at 2.0'.·Pocket Penetrometer = 0.5 tsf. at 3.0'.·Becoming softer with depth.·Significant moisture increase below 2.0'.{4.0' - 12.5'}: Alluvium:Dense; dark brown with some orange mottling;sandy GRAVEL with 8"-minus rounded cobbles;moist to wet.·Target bearing at 4.0' .·Mottling observed below 6.0'.·Groundwater encountered at 9.0'·Wet material beginning at 7.5'.Notes:1.Onsite dewatering system in use for utilityinstallation (groundwater anticipated to behigher).12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA21-19712.5'9.0'Test Pit Designation: TP-4 (East Side) Location:Surface Elevation: Backhoe Type: CAT 315C Job Number:Total Depth: Backhoe Operator: Scott w/SIME Project: Block 2, Lot 1 of South University Dist. Ph. 3Groundwater: Logged By: EGS (AESI) Date: November 29, 2021S4-A@2.0'45.65749, -111.06073(See Map)Target Bearing at 4.0'24.3%3691215GW at 9.0'15129631323S4-B@3.5'21.9%S4-C@8.0'4.6%
{0.0' - 1.0'}: Native Topsoil:Medium stiff; dark brown to black; organicsandy SILT/CLAY with fine roots; very moist.·Fine roots extend to 12".{1.0' - 3.5'}: Fine-Grained Deposit:Medium stiff to soft; light brown; sandySILT/CLAY; very moist.·Pocket Penetrometer = 1.0 tsf. at 1.5'.·Pocket Penetrometer = 0.5 tsf. at 2.0'.·Pocket Penetrometer = 0.5 tsf. at 3.0'.·Becoming softer with depth.·Significant moisture increase below 2.0'.{3.5' - 12.0'}: Alluvium:Dense; dark brown with some orange mottling;sandy GRAVEL with 8"-minus rounded cobbles;moist to wet.·Target bearing at 3.5' .·Mottling observed below 6.0'.·Groundwater encountered at 11.0'·Wet material beginning at 10.0'.Notes:1.Onsite dewatering system in use for utilityinstallation (groundwater anticipated to behigher).2.Measure down in nearest dewatering wellindicated groundwater was ~11.0' belowexisting grade.12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA21-19712.0'11.0'Test Pit Designation: TP-5 (SE Corner) Location:Surface Elevation: Backhoe Type: CAT 315C Job Number:Total Depth: Backhoe Operator: Scott w/SIME Project: Block 2, Lot 1 of South University Dist. Ph. 3Groundwater: Logged By: EGS (AESI) Date: November 29, 2021S5-A@2.0'45.65703, -111.06076(See Map)Target Bearing at 3.5'26.1%3691215GW at 11.0'15129631323S5-B@3.0'22.3%S5-C@6.0'4.3%
{0.0' - 1.0'}: Native Topsoil:Medium stiff; dark brown to black; organicsandy SILT/CLAY with fine roots; very moist.·Fine roots extend to 12".{1.0' - 4.0'}: Fine-Grained Deposit:Medium stiff to soft; light brown; sandySILT/CLAY; very moist.·Pocket Penetrometer = 1.0 tsf. at 1.5'.·Pocket Penetrometer = 0.75 tsf. at 2.0'.·Pocket Penetrometer = 0.5 tsf. at 3.0'.·Becoming softer with depth.·Significant moisture increase below 2.0'.{4.0' - 12.0'}: Alluvium:Dense; dark brown with some orange mottling;sandy GRAVEL with 8"-minus rounded cobbles;moist to wet.·Target bearing at 4.0' .·Mottling observed below 5.75'.·Groundwater encountered at 10.0'·Wet material beginning at 8.5'.Notes:1.Onsite dewatering system in use for utilityinstallation (groundwater anticipated to behigher).2.4" PVC piezometer installed in test pit(MW-2).12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA21-19712.0'10.0'Test Pit Designation: TP-6 (SW Corner) Location:Surface Elevation: Backhoe Type: CAT 315C Job Number:Total Depth: Backhoe Operator: Scott w/SIME Project: Block 2, Lot 1 of South University Dist. Ph. 3Groundwater: Logged By: EGS (AESI) Date: November 29, 2021S6-A@2.0'45.65697, -111.06191(See Map)Target Bearing at 4.0'23.1%3691215GW at 10.0'15129631323S6-B@3.5'23.7%S6-C@8.0'6.5%
APPENDIX B
LLaabboorraattoorryy TTeessttiinngg RReessuullttss
MOISTURE CONTENT DETERMINATION (ASTM D-2216)
Project: Block 2, Lot 1 of South University District Phase 3Project Number: 21-197
Sample Identification: Varies
Soil Classification: Varies
Date Sampled: November 29, 2021
Date Tested: November 30, 2021
Tested By: HRT
Sample Identification:S1-A S1-B S1-C S2-A S2-B S2-C
Exploration Location:TP-1 TP-1 TP-1 TP-2 TP-2 TP-2
Sample Depth (ft):2.0 3.0 8.0 2.0 4.0 6.0
Container Number:LL G H QQ KK UU
Weight of Container:31.08 31.56 31.57 31.19 31.20 30.98
Container + Wet Soil:154.82 199.07 229.68 137.53 151.71 225.81
Container + Dry Soil:129.45 164.80 218.62 118.07 125.12 218.41
Weight of Water:25.37 34.27 11.06 19.46 26.59 7.40
Weight of Dry Soil:98.37 133.24 187.05 86.88 93.92 187.43
Moisture Content:25.8%25.7%5.9%22.4%28.3%3.9%
Sample Identification:S3-A S3-B S3-C S4-A S4-B S4-C
Exploration Location:TP-3 TP-3 TP-3 TP-4 TP-4 TP-4
Sample Depth (ft):2.0 4.0 6.0 2.0 3.5 8.0
Container Number:B DD A E RR NN
Weight of Container:31.55 30.86 31.97 31.69 31.28 30.86
Container + Wet Soil:165.73 184.99 216.40 160.76 160.42 216.17
Container + Dry Soil:139.68 151.17 209.41 135.49 137.22 207.94
Weight of Water:26.05 33.82 6.99 25.27 23.20 8.23
Weight of Dry Soil:108.13 120.31 177.44 103.80 105.94 177.08
Moisture Content:24.1%28.1%3.9%24.3%21.9%4.6%
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221Fax (406) 582-5770
MOISTURE CONTENT DETERMINATION (ASTM D-2216)
Project: Block 2, Lot 1 of South University District Phase 3Project Number: 21-197
Sample Identification: Varies
Soil Classification: Varies
Date Sampled: November 29, 2021
Date Tested: November 30, 2021
Tested By: HRT
Sample Identification:S5-A S5-B S5-C S6-A S6-B S6-C
Exploration Location:TP-5 TP-5 TP-5 TP-6 TP-6 TP-6
Sample Depth (ft):2.0 3.0 6.0 2.0 3.5 8.0
Container Number:K OO MM F C J
Weight of Container:31.74 31.09 31.08 31.71 31.78 31.66
Container + Wet Soil:168.33 165.75 202.15 166.66 182.06 200.10
Container + Dry Soil:140.05 141.17 195.10 141.33 153.27 189.87
Weight of Water:28.28 24.58 7.05 25.33 28.79 10.23
Weight of Dry Soil:108.31 110.08 164.02 109.62 121.49 158.21
Moisture Content:26.1%22.3%4.3%23.1%23.7%6.5%
Sample Identification:
Exploration Location:
Sample Depth (ft):
Container Number:
Weight of Container:
Container + Wet Soil:
Container + Dry Soil:
Weight of Water:
Weight of Dry Soil:
Moisture Content:
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221Fax (406) 582-5770
STANDARD PROCTOR COMPACTION TEST (ASTM D-698)
Project: Block 2, Lot 1 of South Univeristy Dist. Ph. 3
Project Number: 21-197
Sample Identification: Composite (1.5 ft - 2.5 ft)
Soil Classification: Native Sandy Silt/Clay
Date Sampled: 11/29/2021
Date Tested: 12/10/2021
Tested By: JGE
Note: No Oversize Correction Applied
Natural Moisture Content: 23.3 %
Optimum Moisture Content: 16.5 %
Maximum Dry Unit Weight: 101.5 pcf
Reviewed By:
Summary of Lab Test Data
82
84
86
88
90
92
94
96
98
100
102
104
106
108
110
0% 5% 10% 15% 20% 25% 30%Dry Unit Weight (pcf)Moisture Content
PROCTOR COMPACTION CURVE
Compaction Curve
Z.A.V. for S.G.=2.50
Z.A.V. for S.G.=2.65
Z.A.V. for S.G.=2.80
Poly. (Compaction Curve)
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
Note: Native Sandy Silt/Clay Material is
Wetter Than Optimum Moisture. (Drying
of Material May Be Needed to Achieve
Adequate Compaction)
APPENDIX C
PPaavveemmeenntt SSeeccttiioonn DDeessiiggnn
PAVEMENT SECTION DESIGN 1 - Local Streets/Parking Areas
(Note: The Option 1 design is applicable for stable subgrade conditions (ie. dry, hard, compacted).
Project: Blk 2, Lot 1 of S.University Dist., Ph. 3
Project Number: 21-197
Date: December 30, 2021
Prepared By: Erik Schnaderbeck
Important Notes:
1) See following pages for an Explanation of the Design Input Parameters.
2) Sub-base course shall be comprised of import 6"-minus, sandy pitrun gravel.
3) Subgrade to be covered with 315 lb. woven geotextile fabric
4) Design assumes that subgrade is stable (no rutting, deflecting, or yielding)
DESIGN INPUT PARAMETERS
ESALs (total)150,000
Subgrade CBR, (%)2.50
Subgrade Resilient Modulus, MR (psi)3,750
Reliability, R (%)90
Standard Normal Deviate, ZR -1.282
Overall Standard Deviation, So 0.45
Initial Serviceability, po 4.2
Terminal Serviceability, pt 2.0
Design Serviceability Loss, (PSI)2.2
5.17609 = left side
Required Structural Number, RSN 3.18 5.1746 = right side
(Manipulate RSN such that the left and right side of equation match.)
Asphalt Concrete Layer Coefficient, a1 0.41
Base Course Layer Structural Coefficient, a2 0.14
Base Course Layer Drainage Coefficient, m2 0.90
Sub-Base Course Layer Structural Coefficient, a3 0.09
Sub-Base Course Layer Drainage Coefficient, m3 0.90
DESIGN PAVEMENT SECTION
Asphalt Concrete Thickness, D1 (in)3.0
Granular Base Course Thickness, D2 (in)6.0
Granular Sub-Base Course Thickness, D3 (in)15.0
Calculated Structural Number, CSN 3.20
(Manipulate layer thicknesses such that CSN matches or exceeds RSN.)
DESIGN EQUATION
Pavement Section Design: Page 1 of 1
PAVEMENT SECTION DESIGN 2 - Local Streets/Parking Areas
(Note: The Option 2 design is applicable for unstable subgrade conditions (ie. minor rutting/deflecting).
Project: Blk 2, Lot 1 of S.University Dist., Ph. 3
Project Number: 21-197
Date: December 30, 2021
Prepared By: Erik Schnaderbeck
Important Notes:
1) See following pages for an Explanation of the Design Input Parameters.
2) Sub-base course shall be comprised of import 6"-minus, sandy pitrun gravel.
3) Subgrade to be covered with 8-ounce non-woven fabric and Tensar TX-190L Triaxial Geogrid.
4) Design assumes that subgrade is unstable (minor rutting/deflecting)
DESIGN INPUT PARAMETERS
ESALs (total)150,000
Subgrade CBR, (%)2.00
Subgrade Resilient Modulus, MR (psi)3,000
Reliability, R (%)90Standard Normal Deviate, ZR -1.282
Overall Standard Deviation, So 0.45
Initial Serviceability, po 4.2
Terminal Serviceability, pt 2.0
Design Serviceability Loss, (PSI)2.2
5.17609 = left side
Required Structural Number, RSN 3.44 5.1782 = right side
(Manipulate RSN such that the left and right side of equation match.)
Asphalt Concrete Layer Coefficient, a1 0.41
Base Course Layer Structural Coefficient, a2 0.14
Base Course Layer Drainage Coefficient, m2 0.90
Sub-Base Course Layer Structural Coefficient, a3 0.09
Sub-Base Course Layer Drainage Coefficient, m3 0.90
DESIGN PAVEMENT SECTION
Asphalt Concrete Thickness, D1 (in)3.0
Granular Base Course Thickness, D2 (in)6.0
Granular Sub-Base Course Thickness, D3 (in)21.0
Calculated Structural Number, CSN 3.69
(Manipulate layer thicknesses such that CSN matches or exceeds RSN.)
DESIGN EQUATION
Pavement Section Design: Page 1 of 1
Explanation of Design Input Parameters: Page 1 of 3
PAVEMENT SECTION DESIGN
(EXPLANATION OF DESIGN INPUT PARAMETERS)
Design Life (yr): 20
ESALs (total): 150,000
Subgrade CBR, (%): 2.0 or 2.5
Subgrade Resilient Modulus, MR (psi): 3,000 or 3,750
Reliability, R (%): 90
Standard Normal Deviate, ZR: -1.282
Overall Standard Deviation, So: 0.45
Initial Serviceability, po: 4.2
Terminal Serviceability, pt: 2.0
Design Serviceability Loss, (PSI) 2.2
Asphalt Concrete Layer Coefficient, a1: 0.41
Base Course Layer Structural Coefficient, a2: 0.14
Base Course Layer Drainage Coefficient, m2: 0.90
Sub-Base Course Layer Structural Coefficient, a3: 0.09
Sub-Base Course Layer Drainage Coefficient, m3: 0.90
Design Life: A design life of 20 years is typical for new asphalt projects.
ESALs (total): According to Table 18.12 in Reference 1, the estimated design Equivalent
18,000-lb Single Axle Load (ESAL) value for roadways subjected to light vehicle and
medium truck traffic ranges from 10,000 to 1,000,000. We have used assumed an ESAL
value of 150,000 for local streets.
Subgrade CBR: The soaked subgrade CBR was estimated to be 2.5, which is generally
applicable to sandy silts/clays in stable subgrade. A CBR value of 2.0 was assumed for
unstable subgrade.
Subgrade Resilient Modulus: For fine-grained soils with a CBR of 10.0 or less, an
accepted correlation between CBR and resilient modulus is MR = 1500 x CBR. Based on
this equation, the design resilient modulus value shall be 3,750 psi for stable subgrade
and 3,000 psi for unstable subgrade.
Reliability: According to Table 2.2 in Reference 2, the recommended reliability level for
local streets (low volume) in urban settings ranges from 50 to 80 percent; while
collector streets (high volume) should be designed with a level of reliability between 80
and 95 percent. We chose an elevated design reliability level of 90 percent.
Explanation of Design Input Parameters: Page 2 of 3
Standard Normal Deviate: According to Table 4.1 in Reference 2, a 90 percent reliability
value corresponds to a standard normal deviate of –1.282.
Overall Standard Deviation: According to Sections 2.1.3 and 4.3 in Reference 2, a
design value of 0.45 is recommended for flexible pavements.
Initial Serviceability: According to Section 2.2.1 in Reference 2, a design value of 4.2 is
recommended for flexible pavements.
Terminal Serviceability: According to Section 2.2.1 in Reference 2, a design value of 2.0
is suggested for roads that will be subjected to small traffic volumes; while a value of 2.5
or higher should be used when designing major highways. We selected a terminal
serviceability of 2.0.
Design Serviceability Loss: This is the difference between the initial and terminal
serviceability. Therefore, the design value shall be 2.2.
Asphalt Concrete Layer Coefficient: According to the table with the revised surfacing
structural coefficients in Reference 4, a design value of 0.41 is recommended for all
asphalt plant mix grades. This value replaces the 0.33 asphalt coefficient that was
provided in Table 3-2 of Reference 3.
Base Course Layer Structural Coefficient: According to the table with the revised
surfacing structural coefficients in Reference 4, a design value of 0.14 is recommended
for new 1.5”-minus, crushed base course gravel. This value replaces the 0.12 crushed
gravel coefficient that was provided in Table 3-2 of Reference 3.
Base Course Layer Drainage Coefficient: According to Table 2.4 in Reference 2, a
coefficient of 0.80 to 1.00 should be used when fair to good drainage is anticipated
within the pavement structure. We assume good drainage for this project with a
corresponding drainage coefficient of 0.90 for design.
Sub-Base Course Layer Structural Coefficient: For Pavement Section Design, we are
assuming that imported, uncrushed sandy (pitrun) gravel will be placed for the sub-base
section of the roadway. This is the standard product used in the Bozeman area for sub-
base. According to pavement design charts for gravelly soils, we estimated that pitrun
will have a CBR of between 15.0 and 20.0%, which correlates to a structural coefficient
of 0.09.
Sub-Base Course Layer Drainage Coefficient: The drainage coefficients for sub-base
and base course layers are typically the same; therefore, we selected a value of 0.90 for
the design. See the base course layer drainage coefficient section for an explanation.
Explanation of Design Input Parameters: Page 3 of 3
Reference List
1) Traffic and Highway Engineering; Nicholas J. Garber and Lester A. Hoel; 1988.
2) Design of Pavement Structures; AASHTO; 1993.
3) Pavement Design Manual; Montana Department of Transportation; 1991.
4) Pavement Design Memo; Montana Department of Transportation; May 11, 2006.
5) Geotechnical Manual; Montana Department of Transportation; July 2008.
APPENDIX D
LLiimmiittaattiioonnss ooff YYoouurr GGeeootteecchhnniiccaall RReeppoorrtt
LIMITATIONS OF YOUR GEOTECHNICAL REPORT
GEOTECHNICAL REPORTS ARE PROJECT AND CLIENT SPECIFIC
Geotechnical investigations, analyses, and recommendations are project and client specific. Each project
and each client have individual criterion for risk, purpose, and cost of evaluation that are considered in
the development of scope of geotechnical investigations, analyses and recommendations. For example,
slight changes to building types or use may alter the applicability of a particular foundation type, as can a
particular client’s aversion or acceptance of risk. Also, additional risk is often created by scope‐of service
limitations imposed by the client and a report prepared for a particular client (say a construction
contractor) may not be applicable or adequate for another client (say an architect, owner, or developer
for example), and vice‐versa. No one should apply a geotechnical report for any purpose other than that
originally contemplated without first conferring with the consulting geotechnical engineer. Geotechnical
reports should be made available to contractors and professionals for information on factual data only
and not as a warranty of subsurface conditions, such as those interpreted in the exploration logs and
discussed in the report.
GEOTECHNICAL CONDITIONS CAN CHANGE
Geotechnical conditions may be affected as a result of natural processes or human activity. Geotechnical
reports are based on conditions that existed at the time of subsurface exploration. Construction
operations such as cuts, fills, or drains in the vicinity of the site and natural events such as floods,
earthquakes, or groundwater fluctuations may affect subsurface conditions and, thus, the continuing
adequacy of a geotechnical report.
GEOTECHNICAL ENGINEERING IS NOT AN EXACT SCIENCE
The site exploration and sampling process interprets subsurface conditions using drill action, soil sampling,
resistance to excavation, and other subjective observations at discrete points on the surface and in the
subsurface. The data is then interpreted by the engineer, who applies professional judgment to render
an opinion about over‐all subsurface conditions. Actual conditions in areas not sampled or observed may
differ from those predicted in your report. Retaining your consultant to advise you during the design
process, review plans and specifications, and then to observe subsurface construction operations can
minimize the risks associated with the uncertainties associated with such interpretations. The conclusions
described in your geotechnical report are preliminary because they must be based on the assumption that
conditions revealed through selective exploration and sampling are indicative of actual
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 2
conditions throughout a site. A more complete view of subsurface conditions is often revealed during
earthwork; therefore, you should retain your consultant to observe earthwork to confirm conditions
and/or to provide revised recommendations if necessary. Allied Engineering cannot assume responsibility
or liability for the adequacy of the report’s recommendations if another party is retained to observe
construction.
EXPLORATIONS LOGS SHOULD NOT BE SEPARATED FROM THE REPORT
Final explorations logs developed by the consultant are based upon interpretation of field logs (assembled
by site personnel), field test results, and laboratory and/or office evaluation of field samples and data.
Only final exploration logs and data are customarily included in geotechnical reports. These final logs
should not be redrawn for inclusion in Architectural or other design drawings, because drafters may
commit errors or omissions in the transfer process.
To reduce the likelihood of exploration log misinterpretation, contractors should be given ready access to
the complete geotechnical report and should be advised of its limitations and purpose. While a contractor
may gain important knowledge from a report prepared for another party, the contractor should discuss
the report with Allied Engineering and perform the additional or alternative work believed necessary to
obtain the data specifically appropriate for construction cost estimating purposes.
OWNERSHIP OF RISK AND STANDARD OF CARE
Because geotechnical engineering is much less exact than other design disciplines, there is more risk
associated with geotechnical parameters than with most other design issues. Given the hidden and
variable character of natural soils and geologic hazards, this risk is impossible to eliminate with any
amount of study and exploration. Appropriate geotechnical exploration, analysis, and recommendations
can identify and reduce these risks. However, assuming an appropriate geotechnical evaluation, the
remaining risk of unknown soil conditions and other geo‐hazards typically belongs to the owner of a
project unless specifically transferred to another party such as a contractor, insurance company, or
engineer. The geotechnical engineer’s duty is to provide professional services in accordance with their
stated scope and consistent with the standard of practice at the present time and in the subject geographic
area. It is not to provide insurance against geo‐hazards or unanticipated soil conditions.
The conclusions and recommendations expressed in this report are opinions based our professional
judgment and the project parameters as relayed by the client. The conclusions and recommendations
assume that site conditions are not substantially different than those exposed by the explorations. If
during construction, subsurface conditions different from those encountered in the explorations are
observed or appear to be present, Allied Engineering should be advised at once such that we may review
those conditions and reconsider our recommendations where necessary.
RETENTION OF SOIL SAMPLES
Allied Engineering will typically retain soil samples for one month after issuing the geotechnical report. If
you would like to hold the samples for a longer period of time, you should make specific arrangements to
have the samples held longer or arrange to take charge of the samples yourself.