HomeMy WebLinkAbout008 Geotechnical Report
GEOTECHNICAL REPORT FOR:
Commercial Lot 1 of
Sundance Springs Subdivision,
Phase 1B
Bozeman, Montana
September 2019
Project 19‐117
.
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 1
TABLE OF CONTENTS
INTRODUCTION ............................................................................................................................... 3
DESCRIPTION OF THE PROPERTY .................................................................................................... 3
SCOPE OF WORK ............................................................................................................................. 3
PROPOSED IMPROVEMENTS .......................................................................................................... 4
EXPLORATIONS AND SUBSURFACE CONDITIONS ........................................................................... 4
Subsurface Explorations .............................................................................................................. 4
Subsurface Conditions ................................................................................................................. 4
Groundwater Conditions ............................................................................................................. 5
FOUNDATION, SLAB, AND DRAINAGE RECOMMENDATIONS......................................................... 5
Seismic Design Factors ................................................................................................................ 5
Foundation Design – Option One ................................................................................................ 5
Alternative Foundation Support Option ..................................................................................... 6
Interior Concrete Slabs ................................................................................................................ 6
Lateral Earth Pressures ................................................................................................................ 7
Foundation Wall Backfill.............................................................................................................. 7
Subsurface Drainage and Damp‐Proofing ................................................................................... 8
Vapor Barrier Under Interior Concrete Slab ............................................................................... 8
Exterior Concrete Slabs ............................................................................................................... 8
FOUNDATION‐RELATED FILL MATERIAL RECOMMENDATIONS ..................................................... 9
Excavated Foundation Soils ......................................................................................................... 9
Sandy (pitrun) Gravel .................................................................................................................. 9
Crushed (road mix) Gravel .......................................................................................................... 9
Clean Crushed Rock ................................................................................................................... 10
FILL PLACEMENT AND COMPACTION ........................................................................................... 10
ASPHALT PAVEMENT RECOMMENDATIONS ................................................................................ 11
Pavement Section Design .......................................................................................................... 11
Pavement Section Materials, Placement, and Compaction ...................................................... 12
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 2
UNDERGROUND UTILITY RECOMMENDATIONS ........................................................................... 12
Foundation Support of Utility Lines .......................................................................................... 12
Trench Backfill ........................................................................................................................... 13
SURFACE DRAINAGE RECOMMENDATIONS ................................................................................. 13
STORM DRAINAGE PONDS ............................................................................................................ 13
CONSTRUCTION RECOMMENDATIONS ........................................................................................ 13
COLD/WINTER WEATHER CONSTRUCTION .................................................................................. 14
AESI INVOLVEMENT DURING DESIGN AND CONSTRUCTION ....................................................... 14
LIMITATIONS ................................................................................................................................. 14
REFERENCES .................................................................................................................................. 15
SUPPLEMENTAL INFORMATION
o List of Tables
Table 1 – Compaction Recommendations (Application vs. Percent Compaction)
Table 2 – Pavement Section Components and Required Compacted Thickness
o List of Figures
Figure 1 – Vicinity Map
Figure 2 – Quadrangle Map
Figure 3 – Test Pit Location Map
Figure 4 – Geology Map
Figure 5 – Groundwater Map
Figure 6 – Foundation Detail – Option 1 Only
o List of Appendices
Appendix A – Test Pit Logs
Appendix B – Laboratory Testing Results
Appendix C – Groundwater Monitoring Results
Appendix D – Limitations of Your Geotechnical Report
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 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 proposed
development of Commercial Lot 1 in Phase 1B of Sundance Spring Subdivision. The information
contained herein is based on an investigation and analysis of the property’s topographical and
subsurface conditions, a review of geologic maps and literature for the project area, and previous
experience gained during our involvement with other 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 the proposed improvements.
DESCRIPTION OF THE PROPERTY
The 4.9‐acre property is legally described as Commercial Lot 1 of Sundance Springs Subdivision
Phase 1B in the Northeast One‐Quarter of Section 25, Township 2 South, Range 5 East, Principal
Meridian Montana, City of Bozeman, Gallatin County, Montana. See Figures 1 and 2 for the site
location maps.
The vacant property presently slopes slightly to the northeast (ground slopes of under two
percent). Vegetation consists of native grasses as well as significant wetland grasses, plants, and
some trees along the western property boundary (down in a small drainage). No flowing water
was visible in the drainage at the time of our explorations; however, we expect the drainage will
flow at certain times of the year (likely late spring and early summer). Given the topography of
the lot relative to the drainage, we expect elevated groundwater levels at certain times of the
year. A groundwater monitor well was set in the approximate center of the lot to allow
groundwater levels to be measured periodically.
The site lies on alluvial fan deposits of sand and gravel overlain by fine‐grain wind and flood
deposits consisting of silt and clay. While the soils with the highest organic content were found
in the upper 1.5 to 2.0 feet, deeper deposits of dark brown to black silt and clays containing
organics extended to depths of six feet below ground surface (BGS) in several of the pits. At the
time of exploration, groundwater levels were shallow and averaged about 7 feet across the site.
SCOPE OF WORK
Our Scope of Services for this project included:
Excavation of seven test pits within the proposed development site. The location of each
test pit is shown in Figure 3.
Installation of one groundwater monitor well.
Laboratory testing of select samples from the test pits.
Providing allowable bearing capacity criteria.
Surface and subsurface drainage recommendations.
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 4
Backfill material and compaction recommendations.
Asphalt pavement section materials and design thickness.
Site earthwork and construction recommendations.
PROPOSED IMPROVEMENTS
The present plans for Lot 1 were unknown at the time of this report. However, general plans for
the lot appear to consist of one to several commercial buildings. It is assumed the buildings will
be constructed on conventional spread footings with concrete, slab‐on‐grade floors. Further
site improvements will likely include parking/access roads, storm detention facilities, and
underground utilities.
EXPLORATIONS AND SUBSURFACE CONDITIONS
Subsurface Explorations
On‐site soil investigations were conducted by Allied Engineering on August 21, 2019. A total of
seven test pits were dug with a Volvo ECR40D excavator. The approximate location of the test
pits in relation to the site plan are shown on Figure 3 found at the end of this report. The test pit
logs are provided in Appendix A attached.
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. 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.
Select soil samples were brought back to our laboratory for further testing and classification.
Laboratory testing results are provided in Appendix B.
Subsurface Conditions
Similar conditions were encountered in all seven test pits. The upper 6.5 to 10.5 feet consisted
of a combination of organic topsoil and soft to medium stiff deposits of silt and clay. These
materials were underlain by dense, clayey sandy gravel to sandy gravel with cobbles. Foundation
support recommendations provided later in this report are based on excavation to the native
gravels (depths of 6.5 to 10.5 feet).
During the future site work, we recommend the test pits completed as part of our explorations,
that are located within the footprint of the building or under exterior hardscapes, be dug out and
replaced with compacted granular structural fill. Test pits were filled in at the end of explorations
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 5
and only lightly compacted. Therefore, the test pit locations will be subject to undesirable
settlements if left in their current state.
Groundwater Conditions
During our subsurface investigation, groundwater was encountered between depths of 5.5 and
10.0 feet across the site. Groundwater is expected to be near its highest levels in the late spring
to early summer following the run‐off. There may be a second peak in late August/September
during irrigation season. A groundwater monitor well was installed at approximately the center
of the lot to allow periodic monitoring of groundwater levels. A second reading of groundwater
levels was taken on September 24, 2019. We suggest continuing to monitor starting next April.
Groundwater monitoring results to date can be found in Appendix C.
FOUNDATION, SLAB, AND DRAINAGE RECOMMENDATIONS
Seismic Design Factors
This area lies in an area that can be subject to earthquakes. Therefore, buildings will need to be
designed according to the appropriate earthquake loading parameters. A requirement of the
Structural Engineer will be a determination of the site class since this is a basis for the seismic
analysis. Based on our on‐site explorations and knowledge of the geology, the site class for the
project site is Site Class D (as per criteria presented in the 2012 IBC).
Foundation Design – Option One
The fine‐grain silt and clay found at the site are prone to settlements of up to several inches
under typical foundation loads. For this reason, we recommend over‐excavating to the native
clayey sandy gravel and sandy gravel (found at depths of 6.5 to 10.5 feet) and bearing the
footings on this material or granular structural fill that is founded on this material.
We anticipate that the finished floor of the building(s) will likely be at least 1.0 to 2.0 feet above
existing grade. Based on that assumption, we expect that most foundation components will not
be in direct contact with the target bearing material. Assuming a standard, four‐foot tall,
foundation wall and perimeter footings, we expect footing grades may be up to 4.0 to 8.5 feet
above the target material. As a result, foundation over‐excavation (down to native gravels) and
replacement with granular structural fill (up to footing elevations) will be a significant component
of the project. As shown in Figure 6, we suggest the mass removal of all unsuitable soil within
the footprint of the building(s) down to target bearing. The over‐excavation should extend a
minimum of four feet horizontally beyond the edge of all footing (all sides).
Thought was given to limiting the over‐excavation to under the foundation. However, given the
depth to suitable bearing and likely presence of significant interior foundation support elements,
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 6
it seems the most cost‐effective solution is the mass over‐excavation of foundations. However,
we are open to discussion if the Design Team would like to consider the alternative of over‐
excavating individual foundation elements.
Assuming the footings are supported directly on the native gravels or structural fill that extends
to the native gravels, the allowable bearing pressure for all perimeter, interior, and exterior
spread footings is 3,000 pounds per square foot (psf). Allowable bearing pressures from
transient loading (due to wind or seismic forces) may be increased by 50 percent. We estimate
that the above referenced bearing pressure will result in total settlements of less than 1‐inch
with only minor differential settlements. The minimum depth of cover for frost protection of
exterior footings is four feet.
Alternative Foundation Support Option
An alternative foundation support option we have utilized in the last several years when the over‐
excavated depth to suitable bearing is extensive is to support the foundations on rammed
aggregate piers (RAPs). The piers consist of augured holes that extend from the bottom of
foundations down to target bearing depths and are filled back in with vibratory compacted
gravel. Typical spacings for the RAPs is normally every 8 to 10 feet. Foundation elements are
designed to span between the RAPs. The recently completed Heeb’s building (located in
Bozeman, MT at 200 Highland Boulevard) was constructed on RAPs and resulted in significant
cost savings to the project. We would be happy to assist the Design Team if they would like to
explore this option. Given the depth of organic soils found in locations across the site (up to 6
feet in places), it might be advantageous to also consider supporting interior slabs on the RAPs
as well or consider utilizing a framed floor to avoid extensive over‐excavations to remove organic
soils.
We are happy to assist the Design Team if they wish to pursue the use of the rammed aggregate
piers.
Interior Concrete Slabs
Several options exist to support interior concrete slabs. Provided the entirety of the foundation
footprint is over‐excavated to native gravels, the interior concrete slab will be supported by
several feet of structural fill, which is more than adequate.
If the foundation elements are excavated on an individual basis, some fine‐grain soil will be left
under interior slabs. In that case, we suggest a minimum section of 18 inches of granular
structural fill consisting of 12 inches of granular structural fill and 6 inches of compacted crushed
rock overlying a woven geotextile fabric if needed. All organics should be stripped from beneath
the slab. Note that in places, this may result in over‐excavations of up to six feet in areas where
significant organics are present. If soft spots are encountered in the subgrade, these areas should
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 7
be stripped out and replaced with structural fill. Any fill required to bring the subgrade up to the
bottom of the structural fill should be compacted in lifts as specified in a later section.
Also note there may be areas of random fill present (see the log for TP‐7). Random fill can be
subject to unpredictable settlements and should be completely removed from within the interior
of the building(s).
Assuming RAPs are used to support the slab, the deep deposits of organics may be left in‐place
provided the slab is designed to span between the RAPs.
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. If there will be significant surface loads within 10 feet of the wall, we should be consulted
to provide appropriate lateral earth pressures for design. These lateral earth pressures also
assume proper subsurface drainage provisions 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 250 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
Wall backfill can consist of any non‐overly moist, on‐site excavated soil, other than soil containing
organics. All backfill materials must be placed and compacted in accordance with the
embankment fill recommendations as provided later in the report. To avoid damaging
foundation walls during backfilling, only hand‐operated compaction equipment is recommended
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 8
within three feet of walls that are not buried on both sides. The re‐use of topsoil as backfill should
be limited to the uppermost six to eight inches within landscape areas. Please recognize that
the native materials will likely need to be dried prior to reuse as backfill.
Subsurface Drainage and Damp‐Proofing
Assuming the foundation system will consist of a slab‐on‐grade (placed one to two feet above
native grades) with frost walls and footings, a footing drain is not necessary. However, footing
drains should be placed at the base of retaining walls or footings supporting structural floors to
prevent hydrostatic pressures from developing. Footing drains in that case should consist of 4‐
inch perforated PE pipe bedded in crushed drainage rock, completely wrapped in a non‐woven
drainage fabric and daylighted to a downslope location or to a sump with a pump (depending on
elevations).
Buried foundation walls should be damp‐proofed with an acceptable commercial product as per
the requirements of the International Building Code (IBC 2012).
Vapor Barrier Under Interior Concrete Slab
We recommend the addition of a Stego 15‐mil vapor barrier directly under interior concrete slabs
which will be covered with non‐pervious floor coverings. The purpose of the vapor barrier is to
limit rising water vapor which can accumulate under non‐pervious flooring materials and affect
the flooring adhesives. We recommend that the vapor barrier be placed directly on top of the
crushed rock in conjunction with the use of proper concrete mixes that will limit the possibility
of curling at the edges. Burying the vapor barrier under a blotter course of crushed rock is done
to avoid curling of the slab, but it also adds the risk of trapping moisture between the vapor
barrier and the bottom of the slab. For this reason, we recommend placing the vapor barrier on
top of the crushed rock and directly under the slab.
Exterior Concrete Slabs
Depending on site grading, exterior concrete slabs can either be supported 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 six
inches of clean crushed rock and 15 inches of granular structural fill. Thickening the crushed
rock layer 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,
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 9
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 suitable, compacted structural fill.
FOUNDATION‐RELATED FILL MATERIAL RECOMMENDATIONS
Provided below are recommendations for the foundation‐related fill materials that may be used
during construction. These include on‐site excavated soils, sandy (pitrun) gravel, crushed (road
mix) gravel, and clean crushed rock. Placement and compaction criteria follow the specifications
for these materials.
Excavated Foundation Soils
A variety of soils will be excavated during foundation earthwork including topsoil, silt, clay, and
potentially some gravel with cobbles. All topsoil and organic materials should be stripped and
stockpiled for re‐use during site reclamation. We also recommend that on site soils suitable for
re‐use as embankment fill be separated from wet, rocky, or otherwise unsuitable soils during
excavation. The suitability of the non‐organic excavated soils will depend on their rocky
condition, 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.
Sandy (pitrun) Gravel
Sandy (pitrun) gravel is a granular structural fill alternative for placement under and/or behind
footings, slabs, and walls. This material shall be a non‐plastic, well‐graded, mixture of clean sand
and gravel with 100 percent of its fragments passing a four‐inch screen and less than 10 percent
of its particles (by weight) finer than the No. 200 sieve. In addition to these material and
gradation recommendations, it should meet all other applicable specifications as presented in
Section 02234 of the Montana Public Works Standard Specifications (MPWSS) for uncrushed,
sub‐base course gravel.
Crushed (road mix) Gravel
Crushed (road mix) gravel is another granular structural fill alternative for placement under
and/or behind footings, slabs, and walls. This material shall be a non‐plastic, well‐graded,
mixture of clean sand and gravel that is processed (crushed) such that 100 percent of its
fragments pass a 1‐1/2‐inch screen and less than 10 percent of its particles (by weight) are finer
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 10
than the No. 200 sieve. It should also meet all other specifications as presented in Section 02235
of the MPWSS for crushed, 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.
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. This aggregate
product needs to be manufactured by a crushing process and over 50 percent of its particles must
have fractured faces. It is not acceptable to use rock that contains abundant rounded particles
for foundation‐related applications.
FILL PLACEMENT AND COMPACTION
All fill materials should be placed in uniform, horizontal lifts and compacted to an unyielding
condition. This includes clean crushed rock, which can be compacted and/or consolidated by
vibratory means. The maximum “loose lift thickness” for all fill materials (prior to compaction)
should be limited to about 12 inches for large self‐propelled rollers, 8 inches for remote‐
controlled, dual drum rollers, and 6 inches for walk‐behind plate or jumping jack compactors.
The moisture content of any material to be compacted should be within approximately two
percent (+/‐) of its optimum value for maximum compaction.
Special attention must be given to the proper compaction of structural fill materials along the
edges and in the corners of the foundation excavation. These areas often cannot be adequately
accessed and compacted with large equipment. In those cases, either small compactors must
be used, or the limits of the excavation must be increased such that compaction of the entire
minimum structural fill width can be achieved with the larger equipment.
Table 1 details our compaction recommendations for foundation‐related applications. These
recommendations are presented as a percentage of the maximum dry density of the fill material
is defined in ASTM D‐698.
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 11
Table 1. 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 and Retaining Walls: 95
Clean Crushed Rock Under Slabs and Behind Walls: N/A (Vibration Required)
Sub‐base and Base Course Materials for Asphalt Pavement: 95
ASPHALT PAVEMENT RECOMMENDATIONS
Pavement Section Design
Table 2 presents our recommended pavement section for the parking lot and road
improvements. This section is designed for a 20‐year service life and is based on the site’s shallow
subsurface conditions, the traffic loading associated with commercial development, laboratory
testing of the native soils (CBR Test performed by Pioneer Techical), and our previous experience.
If there is slight rutting during subgrade preparation, a woven‐geotextile can be added to
enhance subgrade strength as shown in Table 2 below.
Table 2. Pavement Section Components and Required Compacted Thickness
COMPONENT COMPACTED THICKNESS (IN)
Asphalt Concrete: 3
Base Course ‐ Crushed (road mix) Gravel: 6
Sub‐Base Course ‐ Uncrushed Sandy (pitrun): 15
Woven Geotextile (Mirafi RS280i): As Needed
Stable Subgrade Soils (Less Topsoil): Compacted to 95%
TOTAL SECTION THICKNESS: 24
Important Note: Our design pavement section is suitable provided the subgrade soils are dry,
stable, and can be compacted to 95 percent of ASTM D‐698 prior to the placement of sub‐base
gravel. If widespread unstable subgrade conditions are an issue (i.e., significant deep rutting of
over an inch), either the overly moist soils will need to be scarified and dried OR the sub‐base
component of the pavement section will have to be thickened to bridge the inferior soils.
Depending on the level of severity of the soft subgrade conditions, additional sub‐base gravel
thickness could range from 6 to 12 inches. A woven stabilizer fabric (Mirafi RS280i) may also be
used to reinforced soft subgrade conditions if needed.
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 12
We suggest a bid item within the contract documents for import structural fill and woven
stabilizer fabric to be used if widespread unstable conditions are encountered.
Pavement Section Materials, Placement, and Compaction
The sub‐base and base course materials that comprise the granular parts of the pavement section
shall consist of 4‐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 as presented in the MPWSS, Sections 02234 and 02235. Under normal
circumstances, these gravel products shall be placed in loose lifts not exceeding 12 inches in
thickness and compacted to at least 95 percent of the maximum dry density as defined in ASTM
D‐698. However, wherever subgrade soils are overly soft, and a woven geotextile fabric is used,
we recommend that a full, 15 to 24‐inch section of sub‐base course gravel be placed and
compacted in one single lift to prevent damaging and tearing the fabric with the construction
equipment.
Prior to the placement of the pavement section components (see Table 2 above), all organic
topsoil should be stripped and the excavated subgrade surface re‐compacted. If subgrade
elevations need to be raised, any on‐site excavated soil, other than topsoil, can be used for
embankment fill provided its moisture content is near optimum for compaction and it can be
compacted to an unyielding condition. Following the re‐compaction of the subgrade surface, it
should be proof‐rolled with a heavy piece of construction equipment, such as a loaded dump
truck, to determine its stability. If any isolated soft spots are observed, they can be sub‐
excavated and replaced with suitable compacted fill on an individual basis. However, if it is found
that widespread, unstable conditions exist (ie. the subgrade surface is overly soft, prone to
rutting or pumping, and cannot be compacted to 95 percent of ASTM D‐698) the subgrade soils
will either need to be dried via scarification, the sub‐base gravel component of the section
increased, and/or woven fabric be added as described above. The use of geogrid is also an option
if wide spread subgrade pumping is apparent.
UNDERGROUND UTILITY RECOMMENDATIONS
Foundation Support of Utility Lines
Utility lines (water, sewer, and dry utilities) will likely be supported on a combination of fine‐grain
and gravel soils. These materials will provide suitable support for the utility lines. We suggest
proper bedding of these utilities following the specifications found in the Montana Public Works
Standard Specifications.
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 13
Trench Backfill
Trench backfill can consist of any native material (except materials containing significant
organics) that is not overly wet. 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.
SURFACE DRAINAGE RECOMMENDATIONS
Final site grading must establish and promote positive surface water drainage away from the
foundation footprint in all directions. Water should not be allowed to accumulate against or flow
along any exposed foundation wall. Concrete or asphalt surfacing that abut the foundation
should be designed with a minimum grade of two percent; while adjacent landscaped areas
should have a slope of at least five percent within ten feet of the wall. To further reduce the
potential for moisture infiltration along foundation walls, backfill materials should be well
compacted, and in landscaped areas, capped by four to six inches of low permeability topsoil.
Except for locations that will be surfaced by concrete or asphalt, finished grades (next to
foundation walls), should be set no less than six inches below the top of the interior concrete
slab.
STORM DRAINAGE PONDS
We do not suggest the use of retention ponds. Rather, all stormwater ponds (detention ponds)
should have a controlled outlet.
CONSTRUCTION RECOMMENDATIONS
Please recognize the soil conditions at the site include the potential for elevated groundwater
levels, areas of significant organic soils, and fine‐grain non‐organic soils that are sensitive to
moisture. We suggest careful construction planning and sequencing to complete foundation
preparation in the most expedient manner possible. If work is completed when groundwater
levels are highest, site‐wide groundwater de‐watering may be required. If the work is completed
in the late fall and winter, there is a possibility that significant de‐watering costs may be avoided.
We are happy to work with the Design Team and the Contractor regarding appropriate
construction measures to successfully develop the site.
As discussed earlier in the report, we suggest working with an earthwork contractor early in the
design process to determine the cost savings or expense associated with:
1. Removal of all organic soil and non‐organic fine‐grain soil down to the native gravels
inside the footprint of the building(s) or;
Bill Anderson Commercial Lot 1, Sundance Springs Geotech
September 25, 2019 Bozeman, Montana
Allied Engineering Services, Inc. ● 32 Discovery Drive. Bozeman, Montana 59718 ● Ph: (406) 582‐0221 Page 14
2. Excavating individual footings down to the native gravels and leaving non‐organic fine‐
grain soils under the slab, which we feel will not be the most cost‐effective but are open
to discussion, or;
3. The use of RAPs to support foundation and slab elements.
COLD/WINTER WEATHER CONSTRUCTION
If foundation construction will occur during the cold/winter weather season, the Contractor
should 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 covered with concrete insulation blankets to prevent frost penetration and 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. No fill materials (or footings) should be placed over frozen soils, which may be in a
“frost‐heaved condition”, or on layers of snow.
AESI INVOLVEMENT DURING DESIGN AND CONSTRUCTION
We recommend that AESI be retained during the design of the improvements to assure our
recommendations as discussed in this report are implemented. We further recommend that AESI
be retained during the construction to verify adequate bearing has been achieved and to observe
road/parking lot subgrade conditions.
LIMITATIONS
This report provides our geotechnical‐related recommendations for the proposed construction
on Lot 1 of Sundance Springs Subdivision in Bozeman, Montana. Please be advised that this
report is only applicable for the above‐referenced property and shall not be used for other nearby
project sites.
The recommendations presented herein are primarily based on our observation and evaluation
of the site’s surface and subsurface conditions, along with our 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 that we can analyze the situation and modify
our recommendations if 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.
LIST OF FIGURES
FFiigguurree 11 –– VViicciinniittyy MMaapp
FFiigguurree 22 –– QQuuaaddrraannggllee MMaapp
FFiigguurree 33 –– TTeesstt PPiitt LLooccaattiioonn MMaapp
FFiigguurree 44 –– GGeeoollooggyy MMaapp
FFiigguurree 55 –– GGrroouunnddwwaatteerr MMaapp
FFiigguurree 66 –– FFoouunnddaattiioonn DDeettaaiill –– OOppttiioonn 11 OOnnllyy
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
COMM LOT 1, SUNDANCE SPRINGS
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
COMM LOT 1, SUNDANCE SPRINGS
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
COMM LOT 1, SUNDANCE SPRINGS
TEST PIT LOCATION MAP
BOZEMAN, MONTANA
3
N
TP#
TP-1
TP-2
TP-3
TP-5 TP-6
MW-1
TP-4
TP-7
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
COMM LOT 1, SUNDANCE SPRINGS
GEOLOGY MAP
BOZEMAN, MONTANA
4
N
FIGURECivil Engineering
Geotechnical Engineering
Land Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718
PHONE (406) 582-0221 . FAX (406) 582-5770
www.alliedengineering.com
COMM LOT 1, SUNDANCE SPRINGS
GROUNDWATER MAP
BOZEMAN, MONTANA
5
N
Figure 619-117Sept 2019Commercial Lot 1 - Sundance SpringsFoundation Detail - Option 1 OnlyBozeman, MontanaLegendFoundation Backfilland Embankment FillNative Alluvial Gravels(”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(Lean Clay to Sandy Lean Clayto Organic Soils)Granular Structural FillClean Crushed RockGroundwaterFinished Floor Elevation15 mil Polyethylene Vapor Barrier (typ.)ExistingGroundReviewed By: C. Madson Sept. 20196” (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 6” - 8” Of FoundationBackfill Should Consist OfLow Permeable Topsoil.4’ (min.)6” (min.)Depth Of Cover ForFrost Protection4’ (min.)Width Of MassOver-Excavation6.5’ to 9.0’ (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.
LIST OF APPENDICES
AAppppeennddiixx AA –– TTeesstt PPiitt LLooggss
AAppppeennddiixx BB –– LLaabboorraattoorryy TTeessttiinngg RReessuullttss
AAppppeennddiixx CC –– GGrroouunnddwwaatteerr MMoonniittoorriinngg RReessuullttss
AAppppeennddiixx DD –– LLiimmiittaattiioonnss ooff YYoouurr GGeeootteecchhnniiccaall RReeppoorrtt
APPENDIX A
TTeesstt PPiitt LLooggss
S1-D@9.5'DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-11711.75'6.5'Test Pit Designation: TP-1 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Kevin (Townsend) Project: Comm Lot 1Groundwater: Logged By: SAL/ECN (AESI) Date: August 21, 2019S1-C@6.5'3S1-A@2.0'Opposite Peace Pipe Drive;45.63616, -111.04653420.4%S1-B@4.0'Target Bearing at 6.5'{0.0' - 2.0'}: Native Topsoil:Soft to medium stiff; dark brown to black; clayeySILT with organics and roots; slightly moist tovery moist.·Thick roots to 4"; scattered roots to 1.0'.·Very moist at 2.0'.{2.0' - 4.0'}: Flood Deposit:Medium stiff; dark brown to black; lean CLAYwith abundant organics; very moist.{4.0' - 6.5'}: Loess Deposit:Soft to medium stiff; tan to light brown; silty leanCLAY with sand; very moist.{6.5' - 10.0'}: Alluvial Deposit:Medium dense; grey to bluish grey with orangemottles; clayey sandy GRAVEL with cobbles;very moist to wet.·Primarily 1"-minus gravel with scattered3"-minus gravel and 12"-minus cobbles.·Tough digging.·Collapsing sidewalls.{10.0' - 11.75'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVELwith abundant cobbles and boulders up to 14"in diameter; wet.·Small pockets of grey clay like previouslayer.·Tough digging.1227.8%20.2%30.1%55413GWT at 6.5'246810108642Atterberg Limits:S1-B @ 4.0 ftLL = 38.6PL = 24.1PI = 14.5USCS Classification:CL (Lean Clay)2
DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-1179.5'8.0'Test Pit Designation: TP-2 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Kevin (Townsend) Project: Comm Lot 1Groundwater: Logged By: SAL/ECN (AESI) Date: August 21, 20193S2-A@3.0'East boundary of lot;45.63567, -111.04620423.7%S2-B@7.0'Target Bearing at 7.5'{0.0' - 1.5'}: Native Topsoil:Soft to medium stiff; dark brown to black; clayeySILT with organics and thick roots; slightly moistto very moist.{1.5' - 3.0'}: Flood Deposit:Soft to medium stiff; light brown to greyishbrown; clayey SILT with organics and roots;slightly moist.{3.0' - 7.5'}: Loess Deposit:Soft to medium stiff; tan to light brown; siltySILT with clay; slightly moist to very moist.·Pinholes present throughout.·Very crumbly.{7.5' - 9.0'}: Alluvial Deposit:Medium dense; grey to bluish grey with orangemottles; clayey sandy GRAVEL with cobbles;very moist to wet.·Primarily 1"-minus gravel with scattered3"-minus gravel and 12"-minus cobbles.·Tough digging.·Collapsing sidewalls.{9.0' - 9.5'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVEL withabundant cobbles and boulders up to 14" indiameter; wet.·Small pockets of grey clay like previouslayer.1229.3%554312GWT at 8.0'246810108642
{0.0' - 1.5'}: Native Topsoil:Soft to medium stiff; very dark brown to black;clayey SILT with organics and roots; slightlymoist to very moist.{1.5' - 3.0'}: Flood Deposit:Soft to medium stiff; dark brown to black; leanCLAY with abundant organics; very moist.{3.0' - 7.3'}: Loess Deposit:Soft to medium stiff; tan to light brown; silty leanCLAY with sand; very moist to wet.·Collapsing sidewalls from 5.0'.{7.3' - 8.0'}: Alluvial Deposit:Medium dense; grey to bluish grey with orangemottles; clayey sandy GRAVEL with cobbles;very moist to wet.·Tough digging.·Collapsing sidewalls.{8.0' - 8.5'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVEL withabundant cobbles and boulders up to 14" indiameter; wet.12DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-1178.5'5.5'Test Pit Designation: TP-3 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Brian (Townsend) Project: Comm Lot 1Groundwater: Logged By: ECN (AESI) Date: August 21, 20193S3-A@5.0'Southeast corner of lot;45.63529, -111.04646Target Bearing at 7.3'431.1%1345GWT at 5.5'24681010864252
DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-11710.5'5.5'Test Pit Designation: TP-4 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Brian (Townsend) Project: Comm Lot 1Groundwater: Logged By: ECN (AESI) Date: August 21, 20193S4-A@4.5'Southwest corner of lot;45.63524, -111.04744425.3%S4-B@7.0'Target Bearing at 6.5'{0.0' - 2.0'}: Native Topsoil:Soft to medium stiff; dark brown to black; clayeySILT with organics and roots; slightly moist.·Thick roots to 4"; scattered roots to 1.0'.{2.0' - 4.0'}: Flood Deposit:Soft to medium stiff; dark brown to black; leanCLAY with abundant organics; very moist.{4.0' - 6.5'}: Loess Deposit:Soft to medium stiff; tan to light brown; silty leanCLAY; slightly moist to wet.·Slight 1"-minus gravel with depth.{6.5' - 10.0'}: Alluvial Deposit:Medium dense; grey to bluish grey with orangemottles; clayey sandy GRAVEL with cobbles;very moist to wet.·Primarily 1"-minus gravel with scattered3"-minus gravel and 12"-minus cobbles.·More gravel and sand with depth.·Hard, rocky digging.·Collapsing sidewalls.{10.0' - 10.5'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVEL withabundant cobbles and boulders up to 14" indiameter; wet.·Small pockets of grey clay like previouslayer.1226.3%5GWT at 5.5'54132468101086422
DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-11712.0'7.5'Test Pit Designation: TP-5 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Brian (Townsend) Project: Comm Lot 1Groundwater: Logged By: ECN (AESI) Date: August 21, 20193S5-A@7.0'West side of lot by large tree;445.63566, -111.04739430.0%S5-B@10.0'Target Bearing at 10.5'{0.0' - 2.0'}: Native Topsoil:Soft to medium stiff; dark brown to black; clayeySILT with organics and roots; slightly moist tomoist.·Thick roots to 4"; scattered roots to 1.0'.·Scattered gravel and cobbles.{2.0' - 6.0'}: Flood Deposit:Soft to medium stiff; dark brown to black; leanCLAY with organics; very moist.{6.0' - 9.5'}: Loess Deposit:Soft to medium stiff; tan to light brown; silty leanCLAY; slightly moist to wet.{9.5' - 10.5'}: Alluvial Deposit:Soft; rusty brown to orange; silty SAND; wet.{10.5' - 11.5'}: Alluvial Deposit:Medium dense; grey to bluish grey with orangemottles; clayey sandy GRAVEL with cobbles;very moist to wet.·Primarily 1"-minus gravel with scattered3"-minus gravel and 12"-minus cobbles.·More gravel and sand with depth.·Tough Digging.{11.5' - 12.0'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVEL withabundant cobbles and boulders up to 14" indiameter; wet.·Small pockets of grey clay like previouslayer.1225.5%5GWT at 7.5'45613246810108642Atterberg Limits:S5-A @ 7.0 ftLL = 37.8PL = 22.8PI = 14.9USCS Classification:CL (Lean Clay)62
DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-11710.5'6.5'Test Pit Designation: TP-6 / MW-1 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Brian (Townsend) Project: Comm Lot 1Groundwater: Logged By: ECN (AESI) Date: August 21, 20193S6-A@7.5'Approx. center of lot;45.63569, -111.046834624.5%{0.0' - 1.5'}: Native Topsoil:Soft to medium stiff; dark brown to black; clayeySILT with organics and roots; slightly moist.{1.5' - 3.5'}: Flood Deposit:Soft to medium stiff; dark brown to black; leanCLAY with abundant organics; very moist.{3.5' - 5.5'}: Loess Deposit:Soft to medium stiff; tan to light brown; silty leanCLAY; slightly moist to wet.·Veins of coarse sand at 5.0'.{5.5' - 6.5'}: Alluvial Deposit:Medium dense; light brown; silty clayey SAND;very moist to wet.{6.5' - 8.0'}: Clay:Very stiff; ochre yellow to bluish light grey;CLAY; wet.·Collapsing sidewalls.{8.0' - 10.0'}: Alluvial Deposit:Medium dense; grey to bluish grey with orangemottles; clayey sandy GRAVEL with cobbles;very moist to wet.·Tough digging.·Collapsing sidewalls.{10.0' - 10.5'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVEL withabundant cobbles and boulders up to 14" indiameter.125GWT at 6.5'Target Bearing at 8.0'45571324681010864272
DEPTH (FT)
SAMPLES
% WATER
CONTENTDESCRIPTION OF MATERIALSHorizontal Distance in FeetCivil EngineeringGeotechnical EngineeringLand Surveying32 DISCOVERY DRIVEBOZEMAN, MT 59718PHONE (406) 582-0221FAX (406) 582-5770www.alliedengineering.comNA19-11711.0'10.0'Test Pit Designation: TP-7 Location:Surface Elevation: Backhoe Type: Volvo ECR40D Job Number:Total Depth: Backhoe Operator: Brian (Townsend) Project: Comm Lot 1Groundwater: Logged By: ECN (AESI) Date: August 21, 20193S7-A@8.0'Northwest corner of lot alongLittle Horse Drive;45.63635, -111.04694419.9%{0.0' - 3.0'}: Random Fill:Medium stiff to stiff; dark brown with light tanveins and streaks; clayey SILT with organicsand roots; dry to slightly moist.·12"-minus boulders at 1.5'.{3.0' - 4.5'}: Native Topsoil:Soft to medium stiff; dark brown to black; clayeySILT with organics; slightly moist.{4.5' - 7.5'}: Loess Deposit:Soft to medium stiff; tan to light brown; silty leanCLAY; slightly moist.{7.5' - 9.0'}: Clayey Silt:Stiff; bluish grey to greyish brown; clayey SILTwith cobbles; slightly moist.{9.0' - 11.0'}: Alluvial Deposit:Very dense; brown to grey; sandy GRAVEL withabundant 6"-minus cobbles.·Tough digging.·Collapsing sidewalls.·Less sand with depth.125GWT at 10.0'Target Bearing at 9.0'34512246810108642
APPENDIX B
LLaabboorraattoorryy TTeessttiinngg RReessuullttss
MOISTURE CONTENT DETERMINATION (ASTM D-2216)Project: Comm Lot 1Project Number: 19-117Sample Identification: VariesSoil Classification: VariesDate Sampled: 8/21/2019Date Tested: 8/23/2019Tested By: ECN Sample Identification: S1-A S1-B S1-C S1-DS2-A S2-BS3-A Exploration Location: TP-1 TP-1 TP-1 TP-1TP-2 TP-2TP-3 Sample Depth (ft): 2.0 4.0 6.5 9.53.0 7.05.0 Container Number: A B C DE HP Weight of Container: 32.00 31.60 31.70 31.7031.60 31.6049.30 Container + Wet Soil: 108.10 106.90 113.90 115.10123.40 119.50172.90 Container + Dry Soil: 95.20 90.50 100.10 95.80105.80 99.60143.60 Weight of Water: 12.90 16.40 13.80 19.3017.60 19.9029.30 Weight of Dry Soil: 63.20 58.90 68.40 64.1074.20 68.0094.30 Moisture Content: 20.4% 27.8% 20.2% 30.1%23.7% 29.3%31.1% Sample Identification: S4-A S4-BS5-A S5-BS6-AS7-A Exploration Location: TP-4 TP-4TP-5 TP-5TP-6TP-7 Sample Depth (ft): 4.5 7.07.0 10.07.58.0 Container Number: L DDKK OORRTT Weight of Container: 31.7 30.8031.20 31.0031.2030.90 Container + Wet Soil: 90.20 94.7093.60 110.70100.20124.40 Container + Dry Soil: 78.40 81.4079.20 94.5086.60108.90 Weight of Water: 11.80 13.3014.40 16.2013.6015.50 Weight of Dry Soil: 46.70 50.6048.00 63.5055.4078.00 Moisture Content: 25.3% 26.3%30.0% 25.5%24.5%19.9% Reviewed By:32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770Moisture Content Determinations
ATTERBERG LIMITS DETERMINATION (ASTM D‐4318)Project: Comm Lot 1Project Number: 19‐117Sample Identification: S1‐B @ 4.0 ftSoil Classification: lean CLAYDate Sampled: 8/21/2019Date Tested: 9/3/2019Tested By: MJSTest ResultsPlastic Limit: 24.1Liquid Limit: 38.6Plasticity Index: 14.5Reviewed By:_________________A‐LineCLML or OLCHMH or OHCL‐MLML01020304050600 102030405060708090100Plasticity IndexLiquid LimitPLASTICITY CHART32 Discovery DriveBozeman, MT 59718Phone (406) 582‐0221Fax (406) 582‐5770
ATTERBERG LIMITS DETERMINATION (ASTM D‐4318)Project: Comm Lot 1Project Number: 19‐117Sample Identification: S‐5A Soil Classification: lean CLAYDate Sampled: 8/21/2019Date Tested: 9/3/2019Tested By: MJS Test ResultsPlastic Limit: 22.8Liquid Limit: 37.8Plasticity Index: 14.9Reviewed By:_________________A‐LineCLML or OLCHMH or OHCL‐MLML01020304050600 102030405060708090100Plasticity IndexLiquid LimitPLASTICITY CHART32 Discovery DriveBozeman, MT 59718Phone (406) 582‐0221Fax (406) 582‐5770
STANDARD PROCTOR COMPACTION TEST (ASTM D-698)
Project: Comm Lot 1
Project Number: 19-117
Sample Identification: Bucket Composite
Soil Classification: Clayey Silty Sand
Date Sampled: 8/21/2019
Date Tested: 8/27/2019
Tested By: MJS
Note: No Oversize Correction Applied
Natural Moisture Content: 25.9 %
Optimum Moisture Content: 19.0 %
Maximum Dry Unit Weight: 94.0 pcf
Reviewed By:
Summary of Lab Test Data
70
75
80
85
90
95
100
105
110
115
0% 5% 10% 15% 20% 25% 30% 35% 40%Dry Unit Weight (pcf)Moisture Content
PROCTOR COMPACTION CURVE
Compaction CurveZ.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
CALIFORNIA BEARING RATIO TEST
ASTM D 1883 / AASHTO T 193
PROJECT DATE:9/18/2019
SAMPLE DESCRIPTION
USCS Classification:Boring Number:Composite
Depth:N/A
MOISTURE-DENSITY RELATIONSHIP
Procedure:ASTM D 698
Maximum Dry Density:94.0 lb/ft3
Optimum Moisture:19.0 %
Dry Density at Molding:90 lb/ft3
Relative Compaction:95.9 %
Moisture Content at Molding:19.0 %
SWELL TEST
Soaking Period:96 hrs Surcharge Weight:10 lbs
Surcharge Weight:10 lbs Surcharge Pressure:50.9 psf
Surcharge Pressure 50.9 psf CBR @ 0.1" penetration:6
Average Moisture Content After Soaking:27.2 %CBR @ 0.2" penetration:5
Swell, % of Initial Height of Specimen:1.1 %
CALIFORNIA BEARING RATIO TEST
SAMPLE LOCATION
Comm Lot 1 19-117
Allied Engineering
Bozeman, MT
Clayey Silty Sand
G19698
0
10
20
30
40
50
60
70
80
90
0 0.1 0.2 0.3 0.4 0.5 0.6Stress (pounds per square inch)Penetration (inches)
APPENDIX C
GGrroouunnddwwaatteerr MMoonniittoorriinngg RReessuullttss
Groundwater Monitoring Data: Summary of Wells
NOTES:
1) Highest water measurement to date in well:
8/21/2019 12:15 PM
9/24/2019 8:00 AM
6.5
4.69
Project:Commercial Lot 1 - Sundance Springs
Project Number:19-117
Location:TP-6 (Refer to Test Pit Location Map)
Date Installed:8/21/2019
Installed By:AESI
Date Time GW Depth Below Ground Surface (ft)
MW-1
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
Groundwater Monitoring Data: Page 1 of 1
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.