HomeMy WebLinkAbout025 - Appendix Q.1 - Geo Tech Report
P.O. Box 6217, Bozeman, Montana, 59771 PHONE: (406) 209‐5573 CELL: (406) 221‐7236
PROJECT: 2020 ‐ The Lakes at Valley West (South) Bozeman, Gallatin County
Montana
CLIENT: The Lakes at Valley West Bozeman, LLC
P.O. Box 1113
Suite 179
Bozeman, Montana
59715
PROJECT NO.: 020025CR
DATE: April 10th, 2020
Executive Summary
This report is to serve as record of the subgrade investigation and geotechnical recommendations prepared for the
2020‐Lakes at Valley West. The Client requested the Geotechnical Evaluation in February, 2020 in phone
correspondence for the above‐referenced site. The purpose of the investigation is to evaluate the subsurface soils
and current groundwater conditions, and to determine suitability and characteristics for proposed construction of
the new phase of the Lakes at Valley West subdivision. Castle Rock Geotechnical has prepared ‘Study of Grounds’
(geotechnical) reports for multiple phases of the Lakes at Valley West Subdivision since 2014. This report will utilize
information from the March 2020 field investigation.
The 2020 geotechnical information within will be used in consideration of subgrade improvements, residential
building foundations, finished grading and street and stormwater infrastructure. It is assumed that the majority of
buildings will utilize an earthen supported, concrete foundation with concrete footing wall and slab on grade or crawl
space. The legal description is ‘located in a portion of the Southwest ¼ of the Northeast ¼ of Section 9, Township 2
South, Range 5 East, of the Bozeman, Montana Quadrangle in Gallatin County’. The Property Record Card records
the Primary Owners as Norton Properties LLC and the Subdivision as Norton East Ranch Subdivision Phase III, Plat J‐
564. The site is located on the north side of west Babcock Street between Pond Lily Drive and Water Lily Drive. The
Vicinity and Topographic Map are shown in Figure 1 of the report. The geotechnical evaluation was completed in
general accordance with standard industry practices.
Summary of Subsurface Findings
The majority of ground surface consists of wild native grasses, cattails and willows, though a large part of the
southeast portion of the property has been used for construction activities such as mining of gravels. See Figure 2,
Test Hole Map. No recent aerial photos could be found to show the exact size of the mining activity and depth the
excavated pits, since high groundwater has filled in the burrow pits. The aerial photo, Figure 2 shows the
approximate boundaries of the disturbance due to mining activity but also stockpiled earthen spoils and some
construction debris. This area will require significant resources to remove deleterious materials, soils such as topsoil
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
2
or concrete debris, and unwanted clay and organics from the site. It is believed that the portion of this disturbed
ground can be reclaimed for building lots once the earthen spoils and debris placed upon native grounds is removed.
It is also believed that the burrow pits can be made into lakes that are landscaped and become part of the
subdivision.
The following subgrade summary is primarily for the ‘non‐disturbed’ grounds that were mostly used as Non‐Qualified
Agricultural Land. Depth to stiff alluvial fan type gravels is observed on average 50 inches below top of existing
grade. Depth varies from location to location +10 inches. A thick dark brown topsoil horizon is found from 12 to 24
inches thick USCS symbol (OL). The topsoil is underlain by brown lean clay loam USCS symbol (CL) which is from 10
to 24 inches thick depending on location. The brown lean clay loam is underlain by 5 to 10 inches of brown‐rust ‘lean
clay’ with gravels USCS symbol (GC) or ‘fat’ gray clay USCS Symbol (CL or CH). The gray clay is approximately 6 inches
thick and typically underlain by poorly graded gravels with sand and pebbles USCS symbol (GP). The alluvial gravels
were excavated several feet before groundwater inundated the pit. Groundwater was typically suppressed by the
overlying clay and is estimated to be 36 inches below top of pre‐development grade. Very little gray clay (hydric
soils) was observed and when observed it was in locations where high groundwater exists for prolong periods of time
and where soil mottling is occurring (redox depletion). See hydric soil rating in the NRCS data supplied.
The grounds profiled in the test pit investigation match well with research information from the Montana Bureau of
Mines and Geology and Department of Agricultures, Natural Resources and Conservation Service (NRCS) Data . This
information will be shared in the report and NRCS soil documents are found in the Attachments at the end of the
report.
Summary of Observations & Recommendations for Residential Building Site Lots
Based on the field investigation, and subsurface soil and conditions the following recommendations should be
considered for residential construction. Each building will require a structural pad consisting of 1 inch diameter
washed rock being placed upon approved native alluvial gravels 1 foot above existing groundwater elevations. On
the washed rock 18 inches minimum, 3 inch minus pit run gravels is to be placed so that footing elevation is a
minimum 20 inches above high groundwater.
(Structural fill for any other need on this project can be either on‐site processed, 3 inch minus pit run gravels
containing less than 10% non‐plastic fines and/or imported 3 inch minus pit run gravels.)
Summary of Road Recommendations
Dewatering will be necessary and will have to be continuous during road construction. Top of road grade
(Surface Course) is assumed to be top of predevelopment grade.
All roadways are to be cleared and grubbed, removing organics and roots while stockpiling topsoil.
All native lean clays are to be removed down to native alluvial gravels, the road foundation material.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
3
The native gravels (road foundation material) should be compacted to 95% of the native soil’s maximum dry
density and +3 percent of its optimum moisture content.
A loaded double axel dump truck should drive upon the road foundation after compacted and areas that are
not firm but deflect or fail under the wheel load during these maneuvers should have the soft or yielding
materials removed and replaced with competent structural fill placed and compacted. The road foundation
should be re‐tested until firm.
Once the entire roadway foundation is firm it should be covered with 6 inch minus sub‐grade material
placed in 12 inch lifts up to 19 inches below top of road grade. All road sub‐grade material should be
compacted to 95 percent of the material’s maximum dry density and +3 percent of its optimum moisture
content.
Upon the sub‐grade material 12 inches of 3 inch minus pit run gravels sub‐base material should be placed up
to the base layer. All road sub‐base material should be compacted to 95 percent of the material’s maximum
dry density and +3 percent of its optimum moisture content.
The base course is to consist of 3 inches of ¾ inch diameter crushed aggregate compacted.
The base course is to be covered with 4 inches of hot plant mix surface course.
General
Other utility recommendations are given within the general report. All newly excavated grounds are to be observed
and approved by the Geotechnical Engineer that prepared the Report. The Client inherits all site conditions and work
not observed and approved by the Geotechnical Engineer. Construction observations and records by the
Geotechnical Engineer are required.
Please refer to the attached report for more detailed results of our fieldwork, engineering analyses, and
recommendations. For greater understanding concerning Geotechnical Engineering Reports, please read Important
Information about Your Geotechnical Report found in the Attachments. Castle Rock Geotechnical Engineering is a
member of the Geoprofessional Business Association (GBA). Thank you for using Castle Rock Geotechnical
Engineering. If you have any questions regarding this report, or require our services during the construction phase of
this project, please call Andrew Pilskalns at (406) 539‐8439.
Sincerely,
Andrew Pilskalns, PE
Geotechnical Engineer
Attachment:
Geotechnical Report
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
4
Contents
Executive Summary .......................................................................................................................................................... 1
Summary of Subsurface Findings ................................................................................................................................. 1
Summary of Observations & Recommendations for Residential Building Site Lots ..................................................... 2
Summary of Road Recommendations .......................................................................................................................... 2
General ......................................................................................................................................................................... 3
A. Introduction ................................................................................................................................................................. 6
A.1. Project ................................................................................................................................................................... 6
A.2. Purpose of this Evaluation .................................................................................................................................... 7
A.3. Scope ..................................................................................................................................................................... 7
A.4. Test Hole Investigation (2020) .............................................................................................................................. 7
B. Field Investigation ........................................................................................................................................................ 7
B.1. Logs ....................................................................................................................................................................... 7
B.2. Geologic Conditions ............................................................................................................................................ 10
B.3. Soils ..................................................................................................................................................................... 12
B.3.a. Topsoil .......................................................................................................................................................... 14
B.3.b. Quaternary Gravels ...................................................................................................................................... 15
B.4. Groundwater Observations ................................................................................................................................. 15
B.4.a Groundwater Research .................................................................................................................................. 15
B.5. Laboratory Tests .................................................................................................................................................. 15
C. Analyses and Recommendations ................................................................................................................................ 16
C.1. Proposed Construction ........................................................................................................................................ 16
C.2. Discussion/Foundation Consideration ................................................................................................................ 16
C.3. Site Preparation ................................................................................................................................................... 18
C.3.a. Clearing & Grubbing ..................................................................................................................................... 18
C.3.b. Backfill and Fill Criteria ................................................................................................................................. 19
C.4. Building Foundations ........................................................................................................................................... 19
C.4.a. Depth ............................................................................................................................................................ 19
C.4.b. Footing Sub‐Grade ........................................................................................................................................ 19
C.4.c. Bearing Pressure ........................................................................................................................................... 20
C.4.d. Anticipated Settlement ................................................................................................................................ 20
C.4.e. Reinforcement .............................................................................................................................................. 20
C.4.f. Foundation Wall Backfill ................................................................................................................................ 20
C.4.g. Seismic Design Considerations ..................................................................................................................... 20
C.5. Earth‐Supported Slab & Crawlspace ................................................................................................................... 21
C.5.a. Sub‐Grade ..................................................................................................................................................... 21
C.5.b. Fill ................................................................................................................................................................. 21
C.5.c. Backfill ........................................................................................................................................................... 21
C.5.d. Vapor Retarder and Vertical Water Protection ............................................................................................ 21
C.5.e. Leveling Course and Sub‐Grade Modulus .................................................................................................... 22
C.6. Exterior Slabs ....................................................................................................................................................... 22
C.6.a. Sub‐Grade ..................................................................................................................................................... 22
C.6.d. Bearing Pressure & Lateral Load Resistance ................................................................................................ 24
C.7. Utilities ................................................................................................................................................................ 24
C.7.a. Materials ....................................................................................................................................................... 24
C.7.b. Backfilling and Compaction .......................................................................................................................... 25
C.8. Site Grading and Drainage ................................................................................................................................... 25
C.9. Concrete .............................................................................................................................................................. 25
D. Construction ............................................................................................................................................................... 25
D.1. Excavation ........................................................................................................................................................... 25
D.2. Observations ....................................................................................................................................................... 26
D.3. Moisture Conditioning ........................................................................................................................................ 26
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
5
D.4. Testing ................................................................................................................................................................. 26
D.5. Cold Weather Construction ................................................................................................................................ 26
E. Procedures .................................................................................................................................................................. 27
E.1. Test Hole Excavation ............................................................................................................................................ 27
E.2. Soil Classification ................................................................................................................................................. 27
E.3. Groundwater Observations ................................................................................................................................. 27
F. General Recommendations ........................................................................................................................................ 28
F.1. Basis of Recommendations .................................................................................................................................. 28
F.2. Review of Design ................................................................................................................................................. 28
F.3. Groundwater Fluctuations ................................................................................................................................... 28
F.4. Use of Report ....................................................................................................................................................... 28
F.5. Level of Care ........................................................................................................................................................ 29
Professional Certification ............................................................................................................................................... 29
References ...................................................................................................................................................................... 31
Definitions ...................................................................................................................................................................... 32
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
6
A. Introduction
A.1. Project
The work as we understand it is to perform a geotechnical investigation on the proposed new phase of development
for the Lakes at Valley West Subdivision. This report is to serve as a record of geotechnical information obtained as a
result of research, field observations, and field testing for the above referenced phase of the project. Preliminary
recommendations made within are based upon this information as well as experience with multiple phases of this
development since 2014. The geotechnical information presented within this report is to be used by the Client to
make educated decisions regarding the development of the subdivisions. Recommendations for subgrade
improvements of individual lots are subject to change based on grade and soil conditions observed at the time of
home construction. To determine subgrade improvements per lot site investigations are recommended.
The foundation design for each residential building is assumed to consist primarily of a concrete footing wall with a
slab on grade and crawlspace foundation. The Property Record Card records the primary owners as Norton
Properties LLC and the Subdivision as Norton East Ranch Subdivision Phase III, Plat J‐564. Note that only the east
portion of the plated property was studied. The area of interest is located on the north side of West Babcock Street
between Pond Lily Drive and Water Lily Drive as shown in Figure 1, Vicinity and Topographic Map. The legal
description is ‘located in a portion of the Southwest ¼ of the Northeast ¼ of Section 9, Township 2 South, Range 5
East, of the Bozeman, Montana Quadrangle in Gallatin County’. The property is 4800 feet above sea level and
approximately 40 acres in size. Please note the marked location shown in Figure 1 which shows the general
boundary of the project and labels the property as Lakes at Valley West (South) since the project is south of the Lakes
at Valley West existing development. For simplicity, the lot can be best described as being a square shape with the
northwest corner clipped. The west boundary of the lot is termed the Sewer Utility Road.
Figure 1 –Vicinity & Topographic Map
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
7
A.2. Purpose of this Evaluation
The purpose of the geotechnical evaluation is to provide geotechnical information to assist Architects and other
design professionals in preparing plans and specifications for the proposed new building sites.
A.3. Scope
The scope of services was outlined in the proposal. The task list is given below. The authorization to proceed was in
accordance with the verbal agreement with Greg Stratton.
Our scope of services was limited to the following:
Executive Summary
Limited Study of Grounds Investigation with Excavator
Subsurface Soil Conditions
Groundwater Conditions
Test Hole Logs
General Earthwork Recommendations
A.4. Test Hole Investigation (2020)
Test Hole (TH) locations were selected by Andrew Pilskalns, P.E., Geotechnical Engineer with Castle Rock
Geotechnical Engineering. The locations are shown in Figure 2, Test Hole Map. The Test Holes are used to define the
subsurface characteristics of the property located just 2 miles west of Bozeman, Montana. The test holes are used
to determine the 2020 geotechnical recommendations. Additional subsurface information should be gathered at the
time of construction to verify subsurface materials and conditions. Not all subsurface conditions can be seen or
know until a site is unearthed; therefore geotechnical hazards or conditions cannot be ascertained until sites are
completely unearthed. Revisions to the geotechnical recommendations may be made during construction if hidden
subsurface materials or conditions unearthed at the time of construction are observed which have not been
accounted for. The Log of Test Holes is in the Attachments at the end of this report.
B. Field Investigation
B.1. Logs
Twenty three Test Holes, TH‐1 – TH‐23, were excavated on the lot as part of the subsurface investigation. The test
holes were spatially located on the property to give the best understanding of the site. The investigation occurred on
Thursday March 5th, 2020 with Scott Hardy (Sime Construction) operating a Komatsu PC 170 LC steel track excavator
for excavation. The number of Test Holes used in an investigation such as this should be adequate and numerous
enough to gain a fundamental understanding of subsurface conditions, to ascertain general geo‐related risks and be
proportional to the value of the development. Given that each building site is a large investment to every potential
property Owner, each site should have site conditions approved by a licensed professional Geotechnical Engineer
during construction.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
8
The approximate locations of the 23 test holes are shown in Figure 2, the Test Hole Map. The test holes were
excavated to depths of 5 feet to 13 feet below top of existing grade at the time of this investigation. The southwest
portion of the site was used for mining gravels and dumping of spoils and construction debris. Only a few test holes
were completed in the area used for mining and stockpiling of grounds due to uneven, soft surfaces and mounds of
dirt, access to locations and open ponds.
Soils were described and visually classified utilizing the Unified Soils Classification System, (USCS). In general it could
be said that the test holes were similar – a 1 to 2 foot thick topsoil horizon underlain by a 1 to 3 feet thick lean clay
horizon underlain by alluvial gravels with groundwater at or 6 inches above where the alluvial gravels were
encountered. The alluvial gravels are is 3 inches minus material size, round rock and gravels with pebbles and sand.
Figure 2 – Test Hole Map
Along the southeast portion of the site, delineated by the white boundary in Figure 2, in the vicinity of TH‐10 ‐ TH‐12,
and TH‐22 and TH‐23, open pit mining and stockpiling of soils and construction debris has occurred. Recent aerial
images do show the disturbance; however they are not accurate in showing the size of mining activity since they are
several years old. It is our understanding that the pits will be landscaping features transformed into lakes and
properties can be constructed around the perimeter of the lakes. Test Holes 10, 11 and 12 are likely in a subsurface
trough filled with silt and clay. Depth to gravel was not encountered and the materials are alluvial fan deposits.
Depth to gravel was over 10 feet deep in Test Holes 10, 11 and 12. In Test Holes 10 and 11 undocumented fill was
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
9
observed. It is believed that after 2014 soils were starting to be stockpiled in this open pit mining area and that
mining operations were to soon follow.
The alluvial gravels and pebbles found approximately 50 inches below existing grade that underlie the majority of the
site are rounded from mechanical (gravitational and water forces) and weathering. Well log data shows that alluvial
gravel horizons and similar alluvial deposits are from 40 to 100 feet thick. The fines are washed out of some of these
gravel lenses due to what is believed high subsurface groundwater flow over time. Gaps in grading were observed
and fines are estimated to be 10% or less. These soils are primarily in pockets where likely old stream channels
existed. Footing grade is assumed to be 2 feet below existing grade. Castle Rock Geotechnical is not responsible for
determining road surface elevations or finished floor elevations of buildings. All test hole measurements are made
from the existing undisturbed top of ground surface downward prior to construction. The grounds slope downward
approximately 1 to 2 percent to the south west and all streams are trending in this same direction North 30◦West.
The topographic map does show that the ground is relatively flat in slope because the contour units are in 20 feet
intervals. The area mined for gravel extraction appears to have a similar profile as the other grounds observed. By
observations of the cut embankment around the pond, alluvial gravels were observed to be 50 inches below grade.
Fines within the soils matrix make up approximately 20% or less of the soil materials. Cobbles, gravels, and sands
make up the other materials. Clay and silt fines can absorb moisture, decreasing soil shear strength, which can
reduce the overall embankment strength and bearing capacity of the soils. From geologic maps and well logs in the
area it is hypothesized that alluvium and colluvial gravels make up the upper 50 feet of ground and deeper. No clay
deposits other than mentioned were encountered in the upper 12 feet below the ground during the test hole
investigation.
Several grab bag samples of the alluvial soils from Test Hole 1 and 14 at 5 feet below grade (gravel foundation
material) were field analyzed for shrink swell potential and found to be (NP) Non‐Plastic. The lean clays observed
above the alluvial gravels were field tested and found to be from moderately to highly plastic and moist (typically
above their optimum moisture content) making them very soft. Research data from the Department of Natural
Resource and Conservation Services shows that the lean clay has a moderate shrink swell potential. If thick clayey
horizons of soil other than those observed are encountered and logged in the 2020 field investigation additional
testing should be completed to classify the soils and make recommendations based on findings.
Log of Test Holes sheet(s) indicating the depth and identification of the various soil strata and water level
information can be found in the Attachments at the end of this report. It should be noted the depths shown as
boundaries between the strata are only approximate. The actual changes may be transitions and the depths of the
changes vary between test holes. All measurements in the test holes are taken from the top of existing ground at
the time of the March 2020 investigation downward. Figure 2 –Test Hole Map shows the approximate test‐hole
locations within the building footprint.
Geologic origins presented for the stratum recorded on the Log of Test Hole sheet are based on the soil types and
available knowledge of the depositional history of the site. Because of the complex glacial and post‐glacial
depositional environments, geologic origins are frequently difficult to ascertain. The limited geologic evaluation of
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
10
the site is based on research and test hole information to the depth of the ‘limited’ excavation investigation. The
term ‘limited’ geo‐investigation is used because understanding of ground conditions is based on the limited depth of
test holes and research. More comprehensive subsurface information and soil strength can be obtained by drilling
and Standard Penetration Testing (SPT) with depth at the Owners request. See Figure 3, Test Hole Map‐Depth to
Gravels to determine gravel depth at a location in the study area.
Figure 3 – Test Hole Map – Depth to Gravels
B.2. Geologic Conditions
The property topography is described as sloping 1% downhill to the northwest. The most significant topographic
feature for this proposed phase is an Baxter Creek which trends in the north‐west direction cutting through the east
corner of the property. There are also a very large man made ponds centrally located on the east side of the
property that has a longitudinal axis exceeding 500‐ft. The ponds do not appear on the topographic map shown in
Figure 1 or Figure 4.
Montana Bureau of Mines and Geology (MBMG) record the geological formation of the property as Qafo – Alluvial‐
fan deposits, older than Qaf (Pleistocene). An alluvial fan is defined as an outspread, gently sloping mass of
alluvium deposited by a stream, esp. in an arid or semiarid region when a stream issues from a narrow canyon onto a
plain or valley floor. Viewed from above, it has the shape of an open fan, the apex being at the valley mouth (Bates,
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
11
1984). Alluvium is material deposited by a stream or running water. See Figure 4, MBMG, Geologic Map of Project
Area
Figure 4 – MBMG, Geologic Map of Project Area
Definitions are given from Bates and Jackson, (1984) ‘Dictionary of Geologic Terms’ for the following geologic terms:
Alluvium is soil or sediment “deposited by a stream or running water”. Clay is hydrous silicate minerals, essentially
of aluminum. They have a monoclinic layered crystal lattice. The extremely small particle size imparts ability to
absorb water and ions on the particle surface. Most clay minerals belong to the kaolin, smectite, montmorillonite
and illite groups. Colluvium is soils deposited “usually at the foot of a slope, brought there chiefly by gravity”. Till is
Unstratified drift, deposited directly by a glacier without reworking by meltwater and consisting of a mixture of clay,
silt, sand, gravel, and boulders and cobbles ranging widely in size and shape.” Loam is “a rich, permeable soil
composed of a mixture of clay, silt, sand, and organic matter”. A cobble is “a rock fragment between 64 and 256 mm
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
12
(2.5 and 10 in.) in diameter.” A boulder is “a detached rock mass larger than a cobble, having a diameter greater
than 256 mm (10 in.)”.
The main subsurface geologic feature hidden nearby is the normal fault that passes through Four Corners, Montana
which is about 2 miles from the project. The mapping units show that glacial lakes, gravity, water and freeze thaw
cycles strongly influence the Gallatin basin development. Remnants of very old stream terraces may be found in
dissected country far from any present stream. Along many old established streams lie a whole series of alluvial
deposits in terraces—young deposits in the immediate flood plain, up step by step to the very old deposits on the
highest terraces. In some places recent alluvium covers older terraces.
B.3. Soils
The Natural Resources Conservation Service (NRCS) records multiple soil units in the proposed future phase of Lakes
at Valley West Subdivision. The two primary soils as mapped by the NRCS within the area of development are 510B,
Medowcreek loam and 748A, Hyalite‐Beaverton complex. See Figure 5 – NRCS, Soil Map.
Suitability ratings for these soils will be discussed. Suitability ratings such as dwellings with basements and without
basements, risk of corrosion to both concrete and steel, and water features reports for Soil unit 510B, Medowcreek
loam and 748A, Hyalite‐Beaverton complex are in the Attachments.
The soils mapped by the NRCS in this 2020 Phase study of the subdivision show that the Medowcreek loam has a
high risk for corrosion to steel. Therefore, buried metal is to be either stainless steel, epoxy coated, encased in
polyethylene wrap or have cathodic protection. The soil units have a moderate risk of corrosion to concrete.
Sulphate resistant concrete should be used. 748A, Hyalite‐Beaverton complex have a low risk to corrosion to
concrete and steel. The other soil units shown on the map are in areas designated as Wet Lands and have a high risk
to corrosion to metal as well.
The parent material of the soil units mapped in the future Lakes at Valley West, 2020 study are loamy alluvium or
alluvium associated with stream terraces or alluvial fans. Alluvium is soils deposited by water and loam is a soil
mixture comprised of clay, silt and sand with organic matter. This information is congruent with field findings.
Linear extensibility is a measurement of a soil’s shrink‐swell potential and is considered low if the linear extensibility
is less than 3 percent, moderate for 3 to 6 percent, high if 6 to 9 percent, and very high if more than 9 percent. If
linear extensibility is more than 3, shrinking and swelling can cause damage to buildings, roads, and other structures.
For the soil units mapped in the vicinity of this 2020 Phase study, the linear extensibility varies from 0.00 up to 5.9.
The soils within the 748A, Hyalite‐Beaverton complex are found to have some moderately expansive soils. It is
recommended that all clay soils be removed because they have been found to be overly moist and soft. For the
most part the soils are considered to have a low to moderate shrink swell potential and should not be used as
engineered fill and only approved backfill. It would not be prudent to construct slabs or other slab elements over the
top of the Hyalite Beaverton complex soils. Our analysis and understanding of the subsurface materials and
conditions are only to the depth of observations made.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
13
The Plasticity Index for the gravels that underlies the lean clays (loam) is NP, Non‐Plastic. The gravelly soils are
classified as very extremely gravelly sand, USCS symbol GP. Additional testing may be completed at the time of
construction as deemed necessary by the Geotechnical Engineer that prepared this report.
Figure 5 – NRCS – Soil Map
Most Type I, II and IV Concrete are sulphate resistant. Sulphate resistant concrete is recommended. The risk of
corrosion pertains to the potential soil‐induced electrochemical or chemical action that corrodes or weakens
concrete or uncoated steel. For dwellings with and without basements, the NRCS rates the suitability of the soil as
“somewhat limited” due to large stones, and ‘depth to saturated zone’. To avoid all issues associated with soft loam
soils and lean clay soils the recommendation is to remove them from the building footprint and to construct a solid
building pad out of structural fill where finished footing elevation is above high groundwater and water elevations
that may flood the crawl space. Basically, the higher the footing elevation is, the lower the risk of moisture issues to
the crawl‐space of the structure.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
14
For the proposed building on this site, it is recommended that steel structural elements in the soils be protected with
coatings or have some other cathodic protection. The information from the NRCS correlates well with information
for the field investigation. All of the soil’s physical and engineering properties listed above can be found in the
Attachments at the end of this report.
Castle Rock Geotechnical cannot assume responsibility for the effects of sensitive soils on the building beyond the
depth of the “limited” study area and width of the building footprint. The report is based on best information derived
from typical geotechnical methods used and project budget constraints. If a more detailed bore study is desired,
please contact our office for preparing a bore study.
B.3.a. Topsoil
In the majority of test holes with exception of TH‐10, ‐ 12, the first material encountered was very dark loam, topsoil
with organics, Unified Soil Classification System (USCS) Symbol (OL‐ML) and or (ML‐CL). This was underlain by native
lean clay loam with clay and silt binder. Standard Penetration Test (SPT) blows per foot “N” was estimated based on
experience and difficulty of excavation. The SPT “N” blow count was estimated to be 2 or less with a clay soil
consistency of “ very soft ” for the upper 50 inches of ground and “N” value of 10‐30 with a sand soil relative density
of “medium” for depths greater than 50 inches below grade within the alluvial gravels. The topsoil can be used only
as backfill for landscaping due to high organic content. Table 1 correlates standard penetration test results to Soil
Consistency, Undrained Shear Strength and Saturated Unit Weight of the soil.
Table 1 – Soil Consistence based on SPT
Soil Consistency
Description
SPT "N" Blow
count
Undrained Shear
Strength "c" ‐ lb/ft2
Saturated Unit
Weight (pcf)
Very Soft 0 ‐ 2 < 250 < 100 ‐ 110
Soft 3 ‐ 4 250 ‐ 500 100 ‐ 120
Firm 5 ‐ 8 500 ‐ 1,000 110 ‐ 125
Stiff 9 ‐ 16 1,000 ‐ 2,000 115 ‐ 130
Very Stiff 16 ‐ 32 2,000 ‐ 4,000 120 ‐ 140
Hard > 32 > 4,000 > 130
The optimum unit weight of the alluvial gravel soils with oversize correction is estimated to be 135 pcf at a moisture
content of 7.0%, which correlates well with the soil consistency description. It is recommended that all topsoil be
removed and stockpiled for later use. It is estimated that as much as the upper 24 inches will need to be excavated
to remove all topsoil. However, shallower areas may exist. Under no circumstances is construction of subgrade
improvements to occur upon topsoil or organic laden soils or soft clay. All organics from tree roots are to be
“grubbed out” by excavation and removed from the building footprint. This construction process of removing
topsoil, organics and roots is called clearing and grubbing. The soils profile in TH‐10 through TH‐12 was 4 feet to 6
feet of spoils overlying 2 feet of dark loam underlain by 4 to 5 feet of brown‐gray clay loam underlain by gravelly clay.
These three test holes were from 10 to 13 feet deep.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
15
B.3.b. Quaternary Gravels
The topsoil, approximately 24 inches thick, is underlain by native clay soils that are underlain by alluvial gravels with
either sand, clay or a silty‐clay binder. These soils have a USCS symbol of GP, GM, GC, and often contain a large
number of cobbles. No horizons of clean sand were observed with depth.
Excavation into these gravels was found to be difficult, which indicates they are very tightly packed. The gravels are
within groundwater and can easily be disturbed; therefore excavation near the alluvial gravels is to occur carefully or
when groundwater is drawn down several feet below the top of the gravel’s horizon.
This stratum was given an estimated SPT “N” blow count of 10‐30 for a soil relative density of “medium”. The stiff
gravels were encountered in the upper 7 feet of grounds and are assumed to continue down 40 feet or more.
Groundwater was encountered near 36 to 50 inches below grade in all the test holes except TH‐10, TH‐11 and TH‐12
where groundwater was observed as deep as 10 feet below grade. Weeping of the embankments was observed in
these three test holes near 55 inches below grade, indicating entrapped near surface moisture in the clay horizon.
Field findings correlates well with information researched from the NRCS.
B.4. Groundwater Observations
Groundwater was observed in all the test holes approximately 6 inches above where the native gravels were
encountered. Groundwater in TH‐10 – TH‐12 was significantly deeper due to spoils placed upon the ground. This
report is not a detailed groundwater study completed over a period of time but rather, a quick evaluation based on
research.
B.4.a Groundwater Research
Groundwater information was obtained from the Bureau of Mines and Geology, Groundwater Information Center,
(GWIC) web mapper. Groundwater in this report is defined as that part of the subsurface water that is in the zone of
saturation, including underground streams. It may also be interpreted as all subsurface water as distinct from
surface water. The definitions are taken from Bates and Jackson, (1984) ‘Dictionary of Geologic Terms’. A well log
located near the project site recorded static groundwater levels ranging 40 feet below ground surface. Stratigraphy
of well logs within the same geologic unit was researched to better understand where subsurface soil units begin and
end. The log of GWIC Well Id: 103496, located south of the project lot, shows topsoil underlain by 86 feet of
clay bound gravels and chipped rock underlain by 59 feet of shale underlain by sandstone and shale rock sequences
down to 400 feet below well casing. Depth of alluvial gravels will vary. The stratigraphy of the well logs described is
congruent with MBMG’s description of alluvial deposited geologic units and observations made onsite. The well logs
described can be found in the Attachments at the end of this report.
B.5. Laboratory Tests
Laboratory testing of the soils was not deemed necessary due to ‘in situ’ soil conditions, knowledge of the soils from
previous projects in the vicinity, and the similarities of soils observed in the test holes. The optimum moisture
content for the poorly graded native gravels is assumed to be 7.0 percent. It is recommended that all spoils used as
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
16
backfill be placed at +3 percent moisture content. The desired dry density of the backfill is 95 percent of its
maximum dry density. It is recommended that all imported processed 3 inch minus pit run gravels be compacted to
approximately 135 pcf. Additional testing may be requested by the Client if they would like to determine the use of
either native soils or stockpiled spoils that exist on the property.
C. Analyses and Recommendations
C.1. Proposed Construction
It is assumed that the proposed residential building(s) will be both single and two‐story structures with an earth
supported concrete footing, stem wall with crawl‐space foundation and garage with concrete slab on grade. Castle
Rock Geotechnical does not determine finished floor elevations. The finished grounds around the outside of the
building should have positive drainage. Positive drainage is defined as grounds sloped 5% for the first 10 feet on all
sides of the building to prevent flooding of the foundation as prescribed in the 2018 International Building Code.
Exceptions are areas that have impermeable surfaces such as concrete pads and paved drives, etc. These surfaces
can be sloped 2% positive drainage away from the building. No water is to be allowed to pond within the first 15
feet of the building. All backfill is to be free of boulders and consist of 3 inch minus native gravels. No gravels
greater than 3 inches in size are to be placed around the building as backfill. The native materials are alluvial fan
deposits and have slow to high permeability rates so care must be taken to remove all oversized rock.
The assumed loading is as follows: (1) wall loads will be 1 to 2.5 kips per linear foot, (2) interior column loads will be
between 30 and 40 kips and exterior column loads will be between 20 and 40 kips, and (3) distributed floor loads will
be 150 psf. If the proposed loads exceed these values, finished grades differ by more than 1 foot from the assumed
value, or if there are changes to the design, our office is to be informed. Additional analyses and recommendations
may be necessary. These assumptions are based on groundwater not being within 24 inches of the bottom of
footing.
C.2. Discussion/Foundation Consideration
Based on the field investigation, and subsurface soil and conditions the following recommendations should be
considered. Structural fill will be 1 inch diameter washed gravels and 3 inch minus pit run gravels. The structural fill
is to be properly placed on approved alluvial gravels as recommended. Each building will require this structural pad
with finished footing elevation above high groundwater. (Structural fill for any other need on this project can be
either on‐site processed, 3 inch minus pit run gravels containing less than 10% non‐plastic fines and/or imported 3
inch minus pit run gravels.)
The building footprint should be cleared and grubbed with all deleterious materials, organics and topsoil
being removed. Topsoil should be salvaged, removing large rocks and high density organics and used as
landscaping backfill. Topsoil, should be used as landscaping fill only on the exterior of the building once
primary backfill has been completed. The topsoil horizon is of very high quality and will make for excellent
landscaping backfill.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
17
Based on our findings and experience it is recommended that within a building’s footprint the site be
excavated down to native alluvial (non‐plastic) gravels. Groundwater may or may not exist during site
development depending upon time of the year or diversion practices.
All lean clay soils can be used as backfill next to the building once the concrete has properly cured and
sufficiently strong. The native lean clay soils used as backfill should be free of gray clay ( if any is
encountered) and placed at its optimum moisture content + 3 percent and compacted to 95 percent of its
maximum dry density.
If possible all native alluvial gravels within the building footprint should be compacted and approved by the
geotechnical engineer. If groundwater is present it can be temporarily pumped and controlled so that
ground improvements can be constructed. Groundwater should be pumped 6 inches below where the
native alluvial gravels are encountered. If groundwater is present the native alluvial gravel should not be
compacted unless groundwater is lowered 2 feet below where the native alluvial gravels are first
encountered. Dewater should be continuous during the construction of ground improvements or contact
the GeoEngineer for alternate recommendations.
Based on current groundwater elevation it is recommended that for individual building footprints washed
gravel be placed in the building footprint in 12 inch lifts, vibratory plate compacted 1 foot above
groundwater.
Once placed the washed rock is to be covered with 18 inches of 3‐inch minus non‐plastic pit run gravels
containing less than 10% non‐plastic fines. Engineered fill and Structural fill are interchangeable within the
report and defined as 1 inch diameter washed rock or imported 3‐inch minus non‐plastic pit run gravels
containing less than 10% non‐plastic fines.
Footing grade should be a minimum 20 inches above high groundwater.
Minimum footing depth and width recommended for single level residential buildings are 8 x 16 inches, with
a net allowable bearing pressure of 2,000 lbs/ft². See Figure 6, Typical Crawl Space Foundation
Minimum footing depth and width recommended for two level structures proposed are 8 x 18 inches, with a
net allowable bearing pressure of 2,500 lbs/ft².
The total anticipated settlement is less than 1‐inch.
Typical concrete footing, stem‐walls, slabs foundations, crawl‐space is recommended.
Full basement homes require additional geotechnical considerations. Contact the Geotechnical Engineer for
further consultation.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
18
The foundation footing and slab are to bear upon a raft of structural fill and imported processed washed
gravels.
It is recommended that all foundation stem walls be insulated. Rigid foam reflective insulation that does
not absorb moisture should be used on the interior of the crawlspace or framed basement. Rigid score
board, XPS foam insulation or Architectural‐board that does not absorb water (or equivalent) should be
used. All rigid insulation used on the exterior should be protected with metal flashing to a depth of 6 inches
into the ground and should be reflective coated. It is the Contractor’s responsibility to ensure that exterior
insulation does not interfere with waterproofing membrane adhesive and materials.
Spread footings for 1‐story buildings should bear minimum 3‐feet below finished grade for frost protection,
as required by the Montana State Code. Based on typical construction methods the combination of
concrete foundation footing and wall height is typically 42 inches.
Based on groundwater elevations, no footing drains can be installed since there is no place to discharge
individual drain system. Ensuring the footing grade is above high groundwater and having a waterproof
interior polyethylene barrier installed in the crawl space will ensure moisture protection of the underside of
the structure.
To achieve proper grading around the building after the exterior walls have been backfilled, native soils can
be placed, moisture conditioned, and compacted. It must be remembered that all backfill placed next to
the walls has to be processed native 3 inch minus gravels or imported 3 inch minus gravels.
Based on the results of the soil test holes, it is our opinion the native gravel soils found from 38 inches to 55 below
grade are stiff and can receive structural fill as designed within. Once the building pad is constructed to the
engineer’s specification the structural fill is suitable for spread footing foundations or isolated column loads.
Surface flooding during excavation work is to be avoided with diversion ditches as needed. No water is to be allowed
to pond or pool within a building site during construction. Dewatering may be necessary for each residential
construction project.
C.3. Site Preparation
C.3.a. Clearing & Grubbing
It is recommended that the topsoil horizon be removed from the excavation footprint. The excavation footprint is
defined as the area of the building and the first 3 feet horizontally around the perimeter of the structure. Topsoil
from the excavation may be recovered and used as non‐structural fill and landscaping as approved by the
geotechnical engineer. All trees with roots are to be grubbed out of the building footprint. No footings should be
constructed upon roots.
All construction excavation and associated worker safety are the responsibility of the Contractor in accordance with
current Occupational Safety and Health Administration (OSHA) regulations.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
19
Based on the predominant soil types encountered during the field investigation, construction activities are to adhere
to Type C, non‐cohesive strength soil conditions, in accordance with OSHA regulations, 1:1 embankment (See Section
F of OSHA Regulations for slopes of wet soils). Beneath footings and structural columns, sub‐excavation is to extend
down to native gravels and be replaced with compacted structural backfill.
All critical exterior slabs will require frost protection such as polystyrene foam insulation to reduce the effects of
frost heave. Isolated critical non‐heated exterior slabs are to be constructed upon structural fill with insulation under
the entire slab and extend 5 inches from the slab on all sides. A vapor barrier is recommended under all interior
slabs or some other form of water block.
C.3.b. Backfill and Fill Criteria
One inch diameter washed rock will be used as structural fill under the footings and slab. One‐quarter inch crushed
rock can be used as a leveling course under slabs. This is also termed as structural fill material under slabs.
Approved soils processed to remove all rock greater than 3 inch can be used as an engineered fill for non‐structural
elements such as road fill, site grading fill and other projects elements such as based material for sidewalk, parking
lots and site grading material. All such fill is to be 3 inch minus material, free of debris, organics, and large cobbles
and boulders. Architectural landscaping does not require the large rock to be removed. Boulders are defined as rock
10 inches in diameter and larger. All backfill against the building is to consist of 3‐inch minus native gravel,
processed.
Non‐structural backfill will be defined as native spoils processed as 3 inch minus pit run gravels containing less than
10 percent non‐plastic fines. All non‐structural fill is to be compacted to 95 percent of the soils maximum dry density
as determined by ASTM D‐698 (Standard Proctor) and moisture conditioned to +3 percent of the soils optimum
moisture content. Washed rock is to be placed in maximum 12 inch lifts and vibratory plate compacted and moisture
treated to reduce dust.
C.4. Building Foundations
C.4.a. Depth
It is recommended footings bear a minimum of 4 feet below exterior grades for frost protection or utilize some type
of water proof, reflective insulation for frost protection as required by 2018 International Building Code (2018 IBC).
Interior footings in heated buildings may be placed immediately beneath the slabs, provided they bear on sub‐grade
soils as described below.
C.4.b. Footing Sub‐Grade
It is recommended spread footings bear on smooth, level compacted 3 inch minus pit run gravels. All grounds prior
to placing structural fil are to be level and smooth with all voids filled. Disturbed native pit run soils will be re‐
compacted prior to placing structural fill.
It is recommended all existing soil be removed from beneath proposed footings and slabs and an oversized zone
extending 3 feet (horizontal) beyond the outer edge of footings vertically down to native gravels. Deep excavations
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
20
will have to be benched according to OSHA regulations as given within. Sub‐excavation will extend down to native
pit run soils with structural fill placed up to the desired footing grade after the newly excavated ground is compacted,
level and smooth. All roots and organic debris are to be grubbed out from the building footprint.
The Geo‐Engineer is to approve the grounds prior to placing materials. Upon the engineer’s approval the ground can
be covered with structural fill. Structural fill is defined as 1 inch diameter washed rock to be placed in 12 inches
compacted thickness. It is recommended that all washed rock be compacted in two directions twice with a vibratory
plate compactor. Compaction of structural fill should not destroy existing work. Once compacted 3 inch minus pit
run gravels can be moisture treated and placed up to footing grade in 12 inch lifts and compacted to specification.
All newly excavated surfaces and placed fill are to be approved by the engineering firm that has prescribed the
recommendations and those not approved in writing by the Geotechnical Engineering firm that has prepared the
recommendations are inherited by the Owner and Contractor.
C.4.c. Bearing Pressure
It is our opinion two story structures with footings placed on structural fill as described above may be designed for a
net allowable bearing pressure up to 2,500 lbs/ft2. (Net allowable bearing pressure is defined as that bearing
pressure in excess of the final minimum overburden pressure.) See Figure 6, Typical Crawlspace Detail.
C.4.d. Anticipated Settlement
It is anticipated that total settlement of foundations designed and placed as recommended above will be less than 1
inch under the assumed loads.
C.4.e. Reinforcement
Sufficient reinforcing steel should be placed in the foundation walls to span isolated zones where foundation support
could be lost due to localized settlement, heave of the soils, or installation of subsurface utilities. This will also
reduce the widths of cracks created by shrinkage of the concrete and local settlement and heave of the soils. The
amount of reinforcing should be determined by the project structural engineer. Sulphate resistant concrete is
typically standard practice.
C.4.f. Foundation Wall Backfill
The native pit run soils are to be approved by the engineer prior to placement of non‐structural fill. The on‐site clay
loam, (not topsoil) may be used as backfill if properly conditioned and compacted to 95% of the soils optimum dry
density and + 3 percent of the soils optimum moisture content. For garage slabs it is recommended that imported
structural fill be placed once all clays are removed. The levels of the exterior and interior backfills should not differ
by more than 10 inches during placement or the walls should be braced, otherwise the foundation walls may be
displaced or crack. Backfill is to be placed when walls are adequately strong and properly cured.
C.4.g. Seismic Design Considerations
Based on the results of our subsurface investigation and review of available geologic information, it is anticipated
that the upper 100‐foot profile is comprised of sedimentary deposits of clays, silts, sands, soft bedrock of gravels and
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
21
shale horizons. Therefore, it is recommended to use Site Class "E" (firm soil profile) as defined by the 2018
International Building Code for design.
The intermountain seismic belt is a zone with major ground shaking potential. The Bozeman area and surrounding
mountains is part of this seismic zone. Seismic activity is possible in the Greater Rocky Mountain Region, which
stretches from Canada to Utah with Montana in the middle. Montana is subject to significant seismic activity, and
the study site is located in the Intermountain Seismic Belt (ISB). Two of the largest recorded earthquakes in the
Northern Rocky Mountains occurred in the Centennial Seismic Belt, a part of the ISB. These were the August 18th,
1959 Hebgan Lake, Montana, earthquake (M ‐ 7.5), and the October 28th, 1983 Borah Peak, Idaho, earthquake (M ‐
7.3).
Based on the interactive fault map provided by the Earthquake Hazards Program website offered by the USGS,
Quaternary Age faults are not located within 15 miles of the project.
C.5. Earth‐Supported Slab & Crawlspace
C.5.a. Sub‐Grade
It is recommended that all existing topsoil be removed. Good load bearing gravels are present below the topsoil and
clay loam. Therefore, it is estimated that approximately 3 feet or more of structural fill will be needed to achieve the
desired footing grade above high groundwater and additional fill, 4 feet to bring up the ground to slab grade. If
structural fill is needed, it is recommended to consist of 1 inch diameter washed rock or imported 3 inch minus pit
run gravels containing less than 10% non‐plastic fines.
C.5.b. Fill
It is estimated that a minimum 2 to 3 feet of structural fill will be required and placed on native alluvial gravels to
bring up the ground to footing grade. However, if additional structural fill is needed for some other use it should be
imported 3 inch minus pit run gravels or fill approved by the Engineer. It is recommended that 3 inch minus
structural fill materials be moistened to a moisture content of +3% of optimum, then compacted to a minimum of 97
percent of its standard Proctor maximum dry density. If 1 inch minus rock is used moisture conditioning is not
required; however vibratory plate compaction is required with rock lifts no greater than 12 inches in thickness. All
washed rock should be plate compacted. A minimum of 4 inches of ½ inch diameter frost free gravels (leveling or
choker course) is required under all slabs.
C.5.c. Backfill
It is recommended that backfill in footings and mechanical trenches is moistened to moisture content +3% of
optimum and compacted to a minimum of 95 percent of its standard Proctor maximum dry density. All backfill is
assumed to be native, 3 inch minus alluvial sandy gravels with some silt and clay that is properly moisture
conditioned and screened.
C.5.d. Vapor Retarder and Vertical Water Protection
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
22
It is recommended a vapor retarder/barrier (polyethylene) be placed directly upon the crawl space floor or under the
concrete slab. (Some coverings, coatings, or situations may require a vapor barrier, i.e., a membrane with a
permeance less than 0.01 perm.). Under slab (horizontal) water tight seam sealed 6 mil thickness polyethylene
barrier is to be used; which is continuous and permanently attached 12 inches above the interior foundation footing
onto the concrete wall. Manufacturer’s equivalents or equals products may be substituted. The Contractor should
be responsible for installing a water tight moisture barrier in the crawl space of residential building and under slabs
so that moisture does not adversely affect any wood or other construction material of the building.
The 6 mil vapor retarder/barrier is to be seam sealed water tight and it can be placed over the entire crawl space and
mechanically or chemically welded (bonded) to the foundation crawlspace walls complying with all safety for human
occupancy requirements. A continuous water tight vapor barrier is recommended under all slabs. See Figure 6. If a
more robust water block is used directly under a slab or blindside water proofing is used in basements etc., the 6 mil
polyethylene barrier is not required.
C.5.e. Leveling Course and Sub‐Grade Modulus
It is recommended that a leveling course beneath the floor slabs, preferably consisting of ½‐inch crushed, frost free
base course, be provided. (Actual selection of the leveling course should be determined by the architect/civil
engineer). Assuming a minimum of 4 inches of crushed base leveling course is provided, it is our opinion a modulus
of sub‐grade reaction, k, of 350 pounds per square inch per inch of deflection (pci) may be used to design the floor.
C.6. Exterior Slabs
C.6.a. Sub‐Grade
Non‐critical exterior slabs may be supported on existing native gravel fill after all topsoil, organics and soft clay have
been removed. The Contractor assumes all risk and liability if clay is not removed under slabs. Non‐critical slabs
require structural fill and a final 3‐inches of ¾‐inch diameter washed rock for leveling. Critical exterior slabs, such as
those at entrances, require some additional sub‐grade frost preparation as described previously and as below. Non‐
critical slabs built upon native clay soils are subject to freeze thaw and shrink‐swell affects and will have very poor
performance over time and likely fail quickly.
C.6.b. Backfill and Fill
Critical slabs require placement of structural fill followed by 4‐inches of ½‐inch diameter washed rock. Backfill and fill
beneath proposed exterior slabs and their oversize zones should be placed in lifts and at moisture content +3% of
optimum. It is recommended that all fill and backfill beneath exterior slabs be compacted to a minimum of 95
percent of its standard Proctor maximum dry density.
C.6.c. Frost Protection of Critical Slabs
Heaving of foundation elements and slabs during the winter are a hazard and a nuisance especially where doors
open outward and at other critical grade areas. If the foundation is constructed to have a crawl space or footings,
wall, and slab, it is recommended that the interior walls are insulated with R‐12 or greater water protected XPS
polystyrene. Basically any insulation that gets wet loses its ability to insulate and can become a very costly problem
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
23
to remove and replace. Other issues may arise such as mold that can cause health issues. Insulation used in the
basement or crawlspace should be projected from getting wet.
Figure 6 – Typical Crawl Space Foundation
For critical slab frost protection the following methods can be applied. Excavate the footprint of the slab and 4 feet
beyond the slab. If a slab abuts a building it cannot be in direct contact because this would cause cold bridging.
Vertical water proof insulation will have to separate the slab from the foundation wall. Ten inches of vertical
excavation below the slab is required. The base is compacted and made level and smooth with a minimum 2% slope
for positive drainage as prescribed by the 2018 International Building Code (2108 IBC).
The water proof insulation can be placed directly onto the ground lying flat and smooth and extend 36 inches past
the slab. The insulation is to be covered with 4 inches of ½ inch diameter washed rock. The washed rock and
insulation will reduce frost penetration into the underlying sub‐grade, utilize the heat of the ground and thereby
reduce heave. The leveling course of pea gravel (frost free gravel) is generally required to seat the insulation panels.
A minimum of 5 inches of crushed road base material should be placed over the panels to protect them during
construction. The slab can be placed directly on the ½ inch minus gravel. Native topsoil can be placed over the
remainder of the pea gravel and compacted with a hand tapper.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
24
C.6.d. Bearing Pressure & Lateral Load Resistance
It is our opinion footings placed as described above may be designed for an allowable bearing pressure up to 2,000
lbs/ft2 for footing dimension of 8 inches thick x 16 inches wide for single level homes. The allowable bearing
pressure is 2,500 lbs/ft2 for footing dimension of 8 inches thick x 18 inches wide for two level homes. All footings
must be a minimum 18 inches away from HIGH groundwater levels.
Lateral Load Resistance:
Footing drains cannot be installed as prescribed to reduce hydrostatic pressure on structures since there
is no place to drain them and in periods of flooding the drain may bring water quicker to undesirable
areas. It is assumed that the structure(s) will have a crawl space type foundation. To prevent water
issues it is recommended that the building be elevated above high groundwater and flooding. All
foundation walls are assumed to be fixed at the top. Both the passive and frictional resistance of the
foundation can be assumed to act concurrently. The Structural Engineer may neglect the weight of the
foundation and backfill when determining dead loads. When calculating resistance to vertical dead
loads the coefficient of friction of the aggregate upon which the foundation is constructed is 0.40 and a
passive equivalent fluid pressure of 500 pcf. For short‐period loading from wind or seismic loads
allowable bearing pressures may be increased by one‐quarter.
Lateral Earth Pressures coefficients for Processed native 3 inch minus structural fill & 1” diam. washed
rock:
(1) The active, Ka ‐ 0.31 and an equivalent fluid pressure is 35 pcf.
(2) The passive, Kp – 3.20 and an equivalent fluid pressure of 500 pcf.
(3) At rest, Ko ‐ .41 and an equivalent fluid pressure of 55 pcf. (Non‐sloped condition)
Lateral Earth pressures coefficients for Imported 3 inch minus structural fill will be the same as given
for the processed native soils.
C.7. Utilities
C.7.a. Materials
The potential for sulfate attack is low or negligible and conventional Type II cement may be used according to Table
1904.3 of the 2018 IBC. The soils located on site are rated as having a moderate potential to corrode. It is
recommended that crushed gravel road base with a maximum particle size of 3/4 inch or ½ inch be used as bedding
material. On‐site soils from the trench excavations can be used as backfill above the bedding if properly conditioned
and placed at 95% of the soils maximum dry density as determined by ASTM D 698.
Utility depths are assumed to be less than 10 feet. The embankment profile consists of non‐plastic granular
materials which will require OSHA trenching, and bracing requirements for Type C apply. In addition, native soils are
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
25
not suitable for direct bedding and pipe support. Below 10 feet, rocky soils may be present that may require sub‐
excavation and replacement with Montana Public Works Standards and Specifications, MPWSS, Type II bedding.
C.7.b. Backfilling and Compaction
It is recommended that bedding material be thoroughly compacted around the pipes. It is recommended that trench
backfill above the bedding be compacted to a minimum of 95 percent beneath proposed footings, slabs, and
pavements. Backfilling around and above utilities should meet the requirements of MPWSS.
C.8. Site Grading and Drainage
It is recommended that the site be graded to provide positive run‐off away from the proposed building. It is
recommended that landscaped areas have a slope of at least 5 percent for the first 15 feet away from the building,
then 2 percent to carry run‐off away. To maintain this slope, it is essential that backfill against the foundation walls
be adequately compacted. If it is not adequately compacted and stiff, the exterior foundation wall backfill will likely
consolidate, settle or experience subsidence and water may pond and soak into the soil, causing settlement and
future water issues. All finished grades are to be covered with a minimum 1 foot thick lift of low permeable topsoil
that will prevent the easy absorption of water into the grounds around the building. Landscape features such as
barriers with washed rock that will entrap surface water are not to be placed around the building drip irrigation and
plants shrubs and trees are not recommended within 5 feet of the building unless in completed isolated growing
units where root penetration will not damage the soils or foundation supporting the building. No permeable
landscaped surfaces are to be within 10 feet of the building.
C.9. Concrete
It is recommended that cement meeting the requirements of ASTM C 150 Type II be used to provide moderate
resistance to sulfate attack. It is recommended specifying 5 to 7 percent entrained air for exposed concrete to
provide resistance to freeze‐thaw deterioration. It is recommended a water‐cement ratio of 0.50 or less be used for
exposed concrete and a water‐cement ratio of 0.45 or less for concrete exposed to deicers.
D. Construction
D.1. Excavation
It is our opinion the soils encountered during our field investigation can be excavated with a steel track‐excavator.
The test holes indicate medium firm gravel deposits near 50 inches below grade. See Figure 3, Test Hole Log ‐ Depth
to Gravels, to determine depth of gravels in th vicinity of a particular location in the new Phase. Soils in the footing
excavation will be Type C soils under Department of Labor Occupational Safety and Health Administration (OSHA)
guidelines. Existing fill will be Type B. All earthwork and construction should be performed in accordance with OSHA
guidelines.
Dewatering during infra‐structure construction will be necessary. For residential home construction it may or may
not be required depending on several factors at the time of construction. The geotechnical engineer should be
consulted for each site on how to proceed with residential construction dewatering. It is recommended that flow‐on
the site during excavation not be allowed. Road ditches, spoil piles, and diversion ditches are to be in place to
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
26
prevent stormwater flow onto the site. A construction dewatering permit may not be required during residential
construction if proper construction methods are adhered to. Montana Law requires a Storm Water Pollution
Prevention Plan for infrastructure development.
Castle Rock Geotechnical is a SWPPP Administrator and our office can be contacted to assist in providing a Storm
Water Pollution Prevention Plan if needed. The pollution prevention plan implements measures such as constructing
accesses from 3 inch minus pit run gravels to prevent soil debris, fines from going onto public roadways and washing
into road storm water gutters and natural bodies of water and rivers.
D.2. Observations
All newly excavated ground and subgrade improvements are to be observed and approved by the Geotechnical
Engineer who prepared the report and recommendations, prior to footing construction. All grounds and conditions
and subgrade improvements not observed and approved by the Geotechnical Engineer in writing will be inherited by
the Owner. Castle Rock Geotechnical is not responsible for unapproved work. The removal of topsoil and any
undesirable material from beneath proposed building footprints is also to be verified by the engineer.
D.3. Moisture Conditioning
On site native soils that will be excavated and reused as backfill appeared to be well above the soil’s optimum
moisture content. It is anticipated that it will be necessary to dry them out or during hot months, moisture condition
these soils to achieve the desired optimum moisture content.
It is anticipated that imported fill and backfill materials will be below the soil’s optimum moisture content and
additional moisture will be necessary to achieve the desired moisture content near or slightly above optimum. All
native or imported soils used as backfill are to be tested for moisture content and density when installed.
D.4. Testing
Density tests of fills and backfills placed beneath footings, slabs, and pavement should be completed however not
required if proper equipment is implemented and compacting as prescribed within. It is recommended that density
testing be conducted on the compacted pavement, sub‐base, sub‐grade, and gravel base courses. All density tests
are to be completed with certified Troxler 3411‐B nuclear gauges with 8‐inch rod or equivalent. It is recommended
that slump, temperature, air content, and strength tests on Portland cement concrete be performed. Samples of
proposed backfill and fill materials should be submitted to our testing laboratory at least 5 days prior to placement
on the site for evaluation and determination of their optimum moisture contents and maximum dry densities. All
backfill placed that is not properly compacted is inherited by the Contractor.
It is recommended that density testing of the asphaltic concrete pavement be performed (cores and nuclear density
gauge). The maximum density of the asphaltic concrete mix should be determined by ASTM D 2041 (Rice). It is also
recommended that Marshall tests of the asphalt mix be performed to evaluate strength and air voids.
D.5. Cold Weather Construction
If site grading and construction is anticipated during cold weather, it is recommended that good winter construction
practices be observed. All snow and ice is to be removed from cut and fill areas prior to additional grading. No fill
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
27
should be placed on soils that are frozen or contain frozen material. No frozen soils are to be used as fill. The
Contractor should be prepared to protect the site from freezing and/or flooding.
Concrete delivered to the site should meet the temperature requirements of ASTM C 94. The concrete should meet
all specifications strengths as prescribed or set forth by the Structural Engineer such as slump, water content, and air
entrapment and for any additional additives that may be required. Concrete is not to be placed on frozen soils or
soils that contain frozen material. Concrete is to be protected from freezing until the specified strength is attained.
Frost should not be permitted to penetrate below footings bearing on frost‐susceptible soil since such freezing could
heave and crack the footings and/or foundation walls. All concrete should have a minimum (2) cylinder samples for
every 150 cubic yards of concrete placed (more may be required by the Structural Engineer) with concrete sampled
by a trained professional adhering to the following ASTM requirements for Concrete Test Cylinders. Please
reference:
ASTM C 31, Standard Practice for Making and Curing Concrete Test Specimens in the Field
ASTM C 39, Standard Test Method For Compressive Strength of Cylindrical Concrete Specimens
ASTM C 172, Standard Practice for Sampling Freshly Mixed Concrete
ASTM C 617, Standard Practice for Capping Cylindrical Concrete Specimens.
Concrete cylinders can be tested at 28 days for compressive strength to determine it meets the requirement of the
specified strength for the job.
E. Procedures
E.1. Test Hole Excavation
The investigation occurred on Thursday March 5th, 2020 with Scott Hardy (Sime Construction) operating a Komatsu
PC 170 LC steel track excavator for excavation. Observations of the embankment profiles were conducted in
accordance with standard geotechnical engineering practices. Excavation proved to be without incident once the
test hole locations were located by the Engineer. Additional excavated bore holes may be necessary during
construction as deemed necessary by the Client or the Geotechnical Engineer.
E.2. Soil Classification
Andy Pilskalns, P.E. visually and manually classified the soils encountered in the test holes in accordance with ASTM D
2488, “Standard Practice for Description and Identification of Soils (Visual‐Manual Procedures).” A summary of the
ASTM classification system is attached.
E.3. Groundwater Observations
Several of the test holes were left open for over one hour after excavation. This allowed ample time for any existing
groundwater to enter and stabilize. Groundwater did appear to rise 2 inches higher than what was noticed at the
time the hole was excavated. Based on research of existing wells in the vicinity of the project site, static
groundwater is found from 3 to just over 4 feet below existing grade. If excavation occurs during spring runoff
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
28
groundwater could rise a foot, this scenario is highly probable. The test holes were backfilled after final observations
were made.
F. General Recommendations
F.1. Basis of Recommendations
The analyses and recommendations submitted in this report are based upon observations obtained from the
excavation of test holes performed at the locations shown in Figure 2.
Often, variations occur between these test holes, the nature and extent of which do not become evident until
additional exploration or construction is conducted. A reevaluation of the recommendations in this report should be
made after performing on‐site observations during construction to note the characteristics of any variations. The
variations may result in additional foundation costs, and it is suggested a contingency be provided for this purpose.
Please contact our office to perform observations during the construction phase of this project. This will allow
correlation of the soil conditions encountered during construction to the test hole logs, and will provide continuity of
professional responsibility.
F.2. Review of Design
This report is based on the design of the proposed structure as related to us for preparation of this report. Please
contact our office to review the geotechnical aspects of the designs and specifications.
With the review, our office will evaluate whether any changes in design have affected the validity of the
recommendations, and whether our recommendations have been correctly interpreted and implemented in the
design and specifications.
F.3. Groundwater Fluctuations
Water level observations were made in the test holes at the time of the field investigation, stated on the report. The
period of observation was relatively short, and fluctuation in the groundwater level may occur due to rainfall,
flooding, irrigation, spring thaw, drainage, and other seasonal and annual factors not evident at the time the
observations were made. Design drawings and specifications and construction planning should recognize the
possibility of fluctuations and surface flooding. The geologic unit is defined as ‘Alluvial Fan Deposits.’ These
deposits may consist of covered hidden ancient stream beds where water can quickly flow through during spring
runoff. The building foundation will act as a dam if constructed unbeknownst near an old channel. Erring on the side
of caution would be best practice, which is building above high groundwater.
F.4. Use of Report
This report is for the exclusive use of The Lakes at Valley West Bozeman, LLC, and Castle Rock Geotechnical
Engineering, to use for designing the proposed structure and preparing construction documents. In the absence of
our written approval, we make no representation and assume no responsibility to other parties regarding this report.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
29
The data, analyses, and recommendations may not be appropriate for other structures or purposes. It is
recommended that parties contemplating other structures or purposes contact us. Castle Rock Geotechnical
Engineering cannot assume responsibility or liability for any of the recommendations within, subgrade conditions,
materials used, and construction work, or performance of materials that are not observed, tested, and recorded by
the Engineer that prepared this report.
F.5. Level of Care
Services performed by Castle Rock Geotechnical Engineering for this project have been conducted with that level of
care and skill ordinarily exercised by members of the profession currently practicing in this area under similar budget
and time restraints. The successful completion of the geotechnical engineering of this project is dependent on
continued professional geotechnical services to ensure the proper interpretation and intentions of the
recommendations herein and to observe the construction phases of the design (earthwork, foundation, site grading).
Castle Rock Geotechnical Engineering Inc. is not responsible for quality of “Others” work or interpretation of the
recommendations; furthermore no warranty, expressed or implied, is made. Castle Rock Geotechnical is a member
of the Geoprofessional Business Association (GBA). To better understand how geotechnical reports are to be
interpreted please read Important Information about Your Geotechnical Report found in the Attachments provided
by GBA.
Professional Certification
I hereby certify this report was prepared by me and that I am a duly licensed Professional Engineer under the laws of
the State of Montana.
Andrew Pilskalns, PE
Geotechnical Engineer
CASTLE ROCK GEOTECHNICAL ENGINEERING INC.
9 Cedar Lake Drive
Butte, Montana
59701
CONTACT INFORMATION
C: (406) 539‐8439
O: (406) 209‐5573
andy@castlerockerc.com
elise@castlerockerc.com
Licensed – Montana, Utah, Colorado, Idaho, Wyoming, Hawaii, Nevada
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
30
ATTACHMENTS
References
Definitions
USCS Soil Classification Chart
Property Card
Log of Test Holes
NRCS Soil Data
Important Information about Your Geotechnical Engineering Repot
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
31
References
Bates, R.L., and Jackson, J.A. 1984. Dictionary of Geological Terms. American Geological Institute. Anchor Books,
New York, 571 p.
Google Earth 6.2.9200.0. (July 19, 2014) (November 20, 2011) (August 10, 2009) (July 21, 2005) (August 11, 1995).
Big Sky, Montana. 45.267311˚, ‐111.284837˚, Eye alt 9907 ft. Borders and labels; roads; 3D buildings. <
http://www.google.com/earth/index.html>. Accessed February 22, 2016.
Susan M. Vuke, Jeffery D. Lonn, Richard B. Berg, and Christopher J Schmidt V.S, 2014, Geologic Map of Bozeman 30’ x
60’ Quadrangles Southwestern Montana, Montana Bureau of Mines and Geology Open‐File Report 648, Scale
1:24,000.
Lindeburg, M.R., 1999, Civil Engineering Reference Manual for the PE Exam, Seventh Edition: Professional
Publications, Inc., Belmont, 35‐19 p.
Montana Bureau of Mines and Geology, Montana Groundwater Information Center Webpage. Available online
at http://mbmggwic.mtech.edu/. Accessed March 18, 2019.
Soil Survey Staff, Natural Resources Conservation Service, United States Department of Agriculture. Web Soil Survey.
Available online at http://websoilsurvey.nrcs.usda.gov/. Accessed April 03, 2020.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
32
Definitions
To assist the reader in understanding site conditions at a point in time, several definitions have been prepared. The
terms include pre‐development, development, and post‐development grades. Other important terms and
definitions are listed below.
Unified Soil Classification System (USCS): USCS is a soil classification system used in engineering and geology to
describe the texture and grain size of soils.
Soil: a sediment or other accumulation of mineral particles produced by the physical or chemical disintegration of
rock, plus the air, water, organic matter, and other substances that may be included. Soils are a foundation material
upon which structures bear.
Alluvium (Holocene)—Light gray to light brown gravel, sand, silt, and clay deposited in stream and river channels, on
their floodplains, and on low terraces as much as about 6 m (20 ft) above modern streams and rivers. Moderately
sorted to well sorted. Larger clasts subangular to well rounded. Composition varies, but includes clasts of Archean
metamorphic rocks, Precambrian orthoquartzite, Paleozoic limestone and quartzite, vein quartz, and volcanic rocks.
Clasts of some small streams originating in Tertiary uplands are dominantly granule size and smaller, and may include
rip‐up clasts.
Pre‐development grade: The topography of the property as observed during this investigation, prior to installation of
infrastructure or commencement of additional earthwork activities. The attached soil test logs (test pit) are
reflective of the pre‐development grade.
Development grade: The topography of the property after installation of infrastructure and general earthwork
activities.
Post‐Development grade: The grades of the ground after homes are constructed and backfilled on a property.
Overburden/Spoils: Soils that are disturbed by construction activities; including soils that have been placed upon
undisturbed ground surfaces. Examples for this site are soils consisting of dark brown silt loam with organics, dark
brown sandy gravels, mottled silt, clay loam, and non‐plastic sandy gravels.
Topsoil: Native soil material consisting of dark brown silt loam with a high amount of organics; usually undisturbed
ground’s first soil horizon. Topsoil remnants have been observed under spoils across the property.
Lot subgrade improvements: Geotechnical recommendations given regarding the development of each residential lot
for the benefit of the Builder.
Road subgrade improvements: Geotechnical recommendations given regarding the development of subdivision road.
Structural Fill: Soil upon which structural elements such as footings, sonotubes, slabs, etc. may be constructed upon.
Two different types of material may be used as structural fill: imported 3‐inch minus (well graded) pit run gravels
with less than 10% non‐plastic fines as described in Table 3 of this report, or 1 inch diameter washed rock. Other
types of gravels and sand mixtures, USCS soil classification symbol – GP or GW may be used as approved structural fill
if approved by the GeoEngineer upon request.
Road Fill: Soils used to build the road section upon which may include:
3‐inch minus (well graded) pit run gravels with less than 10% non‐plastic fines See Table 3 Report.
1½ minus, 94‐100 passing 1” sieve, 45‐80 passing ½”sieve, 25‐60 passing No.4 sieve, 25‐55, passing No.10 sieve.
¾ inch minus, 40‐70% passing No. 4 sieve, 2‐10%, 25‐55% passing No. 10 Sieve & 2‐10% passing No. 200 sieve.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
33
Asphaltic Concrete Aggregate – MT Public Works Specification
Sieve Size ‐ Type B grading Requirements
Sieve Size % Passing
¾” 100
½” 80‐100
3/8” 70‐90
No.4 45‐65
No. 10 32‐45
No. 40 15‐25
No. 200 4‐10
Building Footprint: The entire heated area of the foundation and three feet beyond (horizontally) including garage
and covered porches.
Road Footprint: width and length of subbase and aggregate footprint (extend a minimum one foot horizontally
beyond curb and gutter) for city rural and collector roads as defined by MPW road sections.
Soil Pumping: Movement of soils under load due to excess pore water pressure in the soils.
Excavation footprint: The building foundation footprint plus an additional 3‐feet horizontal around the perimeter.
(sometimes interchangeable with Building Footprint)
Settlement: is the result of consolidation of soils.
Subsidence: is the sudden sinking of soils or gradual downward settlement with little or no horizontal movement.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
34
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
35
Log of Test Holes – Page 1
Test Hole 1
USDA Classification Horizon Thickness Groundwater Depth
OL, ML –Topsoil 1’‐6” ‐
CL – Brown Lean Clay Loam*3’‐0” 4’0”
GP –Gravel w/Sand unknown
* Portable static cone penetration tests record the native lean clay loam soils to be soft, 1/8 tonx/sqft.
Test Hole 2
USDA Classification Horizon Thickness Groundwater Depth
OL, ML – Topsoil 2’‐0” ‐
CL – Brown Lean Clay Loam 1’‐3” 3’‐0”
GP –Gravel w/Sand unknown
Test Hole 3
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 1’‐10” no
ML – Silt Loam* 1’‐3” 2’‐10”
GC –Gravels w/Sand‐Clay 1‐6”
GP –Gravels w/Sand‐Clay Unknown **
* Portable static cone penetration tests record the native silt loam soils to be stiff, 1/6 tonx/sqft
** Total depth 5‐’5”.
Test Hole 4
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 1’‐10” no
ML – Silt Loam* 1’‐10” no
GC – Gravel with Clay 0’‐6” 3’‐8”
GP – Sandy Gravels unknown
Test Hole 5
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐0” no
ML – Silt Loam* 2’‐0” 3’‐0”
GP – Sandy Gravels Unknown **
* Portable static cone penetration tests record the native silt loam soils to be stiff, 0 tonx/sqft
** Total depth 5’‐0”
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
36
Log of Test Holes – Page 2
Test Hole 6
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 1’‐10” no
GP – Very Gravelly 0’‐8” 1’‐10”
GW – Well Graded Gravels unknown
Test Hole 7
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 1’‐8” ‐
CL – Brown Clay Loam 2’‐3” 3’‐10”
GW – Well Graded Gravels unknown
Test Hole 8
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐0” ‐
CL – Brown Clay Loam 1’‐6” 3’‐0”
GW – Well Graded Gravels Unknown *
* Total Depth 4’‐0”
Test Hole 9
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 0’‐10” ‐
CL – Brown Clay Loam 2’‐0” ‐
GW – Well Graded Gravels unknown 3’‐4”
Test Hole 10 *
USDA Classification Horizon Thickness Groundwater Depth
CL, ML, CH, OL, GC ‐ SPOILS 5’‐0” Weeping at 48”
OL, ML‐ Topsoil 1’‐6”
CL‐ Brown Clay Loam 6’‐6” **
*NOTE: Top of Ground of TH‐10 is 7’‐0” in elevation than TH‐9.
** Limited Reach of Excavator, Total Depth 12’‐4”
Test Hole 11
USDA Classification Horizon Thickness Groundwater Depth
CL, ML, CH, OL, GC ‐ SPOILS 7’‐0” ‐
CL, CH – Brown Gray Clay 3’‐0” 10’‐0”
CH‐GC Grey Clay w/Gravel 2’‐6” *
* Limited Reach with Excavator, Total Depth, 12‐6”
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
37
Log of Test Holes – Page 3
Test Hole 12
USDA Classification Horizon Thickness Groundwater Depth
CL, ML, CH, OL, GC – SPOILS* 11’‐0” ‐
CL – Grey Clay Unknown ** ‐
*Very soft soils– Embankment collapse at 4’ below grade due to high hydrostatic pressure in soils.
**Limited Reach of Excavator, Total Depth 12’‐6”
Test Hole 13 *
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐0” ‐
CL – Brown Clay Loam 0’‐10” ‐
GW – Well Graded Gravels Unknown ** 3’‐8”
* This Test Hole is 200’ north of TH‐9
** Total Depth is 5’‐0”
Test Hole 14
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 1’‐0” ‐
CL –Rust Brown Clay Loam 1’‐2” ‐
GW – Well Graded Gravels unknown 3’‐0”
Test Hole 15
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐0” ‐
CL –Rust Brown Clay Loam 2’‐3” ‐
GW – Well Graded Gravels unknown 4’‐11”
Test Hole 16
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐0” ‐
CL –Rust Brown Clay Loam 2’‐2” 3’‐9”
GW – Well Graded Gravels* unknown
*Very Stiff Gravels
Test Hole 17
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 1’‐7” ‐
CL –Rust Brown Clay Loam 2’‐1” 3’‐4”
GW – Well Graded Gravels* Unknown *
Total Depth 4’‐6”
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
38
Log of Test Holes – Page 3
Test Hole 18
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐6” ‐
CL –Rust Brown Clay Loam 1’‐11” * 5’‐0”
GW – Well Graded Gravels* Unknown **
Penetration Resistance 0 tonx/sqft
Total Depth 4’‐6”
Test Hole 19
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐0” ‐
CL –Rust Brown Clay Loam 2’‐4” 4’‐4”
GW – Well Graded Gravels* Unknown
Test Hole 20
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐2” ‐
CL –Rust Brown Clay Loam 2’‐8” 4’‐0”
GW – Well Graded Gravels* Unknown
Test Hole 21
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐1” ‐
CL –Rust Brown Clay Loam 2’‐11” 5’‐0”
GW – Well Graded Gravels* Unknown
Test Hole 22
USDA Classification Horizon Thickness Groundwater Depth
OL, ML‐ Topsoil 2’‐2” ‐
CL –Rust Brown Clay Loam 2’‐8” 4’‐10”
GW – Well Graded Gravels* Unknown
Test Hole 23
USDA Classification Horizon Thickness Groundwater Depth
GP‐ Road Mix 1’‐0” ‐
OL, ML‐ Topsoil 2’‐0” ‐
CL –Rust Brown Clay Loam 2’‐0” ‐
GW – Well Graded Gravels* Unknown *
Total Depth – 6’‐6”
Property Record Card
Summary
Primary Information
Property Category:RP Subcategory:Non-Qualified Ag
Geocode:06-0798-09-1-01-13-0000 Assessment Code:00RGG67328
Primary Owner:PropertyAddress:
NORTON PROPERTIES LLC
63026 NE LOWER MEADOW DR #200 COS Parcel:
BEND, OR 97701-5877
NOTE: See the Owner tab for all owner information
Certificate of Survey:
Subdivision:NORTON EAST RANCH SUB PH 3A
Legal Description:
NORTON EAST RANCH SUB PH 3A, S09, T02 S, R05 E, Lot R1, ACRES 79.3085, PLAT J-564
Last Modified:7/11/2019 1:28:25 PM
General Property Information
Neighborhood:206.010.B Property Type:VAC_U - Vacant Land - Urban
Living Units:1 Levy District:06-035008-7C 08
Zoning:Ownership %:100
Linked Property:
Linked Property Link Type
06-0798-09-1-01-14-0000 8 - Split View
Exemptions:
No exemptions exist for this property
Condo Ownership:
General:0 Limited:0
Property Factors
Topography:Fronting:
Utilities:Parking Type:
Access:Parking Quantity:
Location:Parking Proximity:
Land Summary
Land Type Acres Value
Grazing 0.000 00.00
Fallow 0.000 00.00
Irrigated 0.000 00.00
Continuous Crop 0.000 00.00
Wild Hay 0.000 00.00
Farmsite 0.000 00.00
ROW 0.000 00.00
NonQual Land 79.309 4,085.00
Total Ag Land 79.309 4,085.00
Total Forest Land 0.000 00.00
Total Market Land 0.000 00.00
Deed Information:
Deed Date Book Page Recorded Date Document Number Document Type
Owners
Party #1
Default Information:NORTON PROPERTIES LLC
63026 NE LOWER MEADOW DR #200
Ownership %:100
Primary Owner:"Yes"
Interest Type:Conversion
Last Modified:3/22/2016 7:42:49 AM
Other Names Other Addresses
Name Type
Appraisals
Appraisal History
Tax Year Land Value Building Value Total Value Method
2019 4085 0 4085 COST
2018 38832 0 38832 COST
Market Land
Market Land Info
No market land info exists for this parcel
Dwellings
Existing Dwellings
No dwellings exist for this parcel
Other Buildings/Improvements
Outbuilding/Yard Improvements
No other buildings or yard improvements exist for this parcel
Commercial
Existing Commercial Buildings
No commercial buildings exist for this parcel
Ag/Forest Land
Ag/Forest Land Item #1
Acre Type:NQ - Non Qualified Ag Land Irrigation Type:
Class Code:1701 Timber Zone:
Productivity
Quantity:0 Commodity:
Units:Non Qual
Valuation
Acres:79.309 Per Acre Value:51.51
Value:4085
Soil Taxonomy Classification—Gallatin County Area, Montana
(Soil Taxonomy, - Lakes 2020)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 1 of 550583005058390505848050585705058660505875050588405058300505839050584805058570505866050587505058840490820490910491000491090491180491270491360491450491540491630491720
490820 490910 491000 491090 491180 491270 491360 491450 491540 491630 491720
45° 40' 59'' N 111° 7' 4'' W45° 40' 59'' N111° 6' 22'' W45° 40' 40'' N
111° 7' 4'' W45° 40' 40'' N
111° 6' 22'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,170 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
Fine-loamy over sandy or
sandy-skeletal, mixed,
superactive, calcareous,
frigid Typic Endoaquolls
Fine-loamy over sandy or
sandy-skeletal, mixed,
superactive, frigid
Fluvaquentic Haplustolls
Fine-loamy, mixed,
superactive, frigid
Cumulic Haplustolls
Fine-loamy, mixed,
superactive, frigid Typic
Argiustolls
Not rated or not available
Soil Rating Lines
Fine-loamy over sandy or
sandy-skeletal, mixed,
superactive, calcareous,
frigid Typic Endoaquolls
Fine-loamy over sandy or
sandy-skeletal, mixed,
superactive, frigid
Fluvaquentic Haplustolls
Fine-loamy, mixed,
superactive, frigid
Cumulic Haplustolls
Fine-loamy, mixed,
superactive, frigid Typic
Argiustolls
Not rated or not available
Soil Rating Points
Fine-loamy over sandy or
sandy-skeletal, mixed,
superactive, calcareous,
frigid Typic Endoaquolls
Fine-loamy over sandy or
sandy-skeletal, mixed,
superactive, frigid
Fluvaquentic Haplustolls
Fine-loamy, mixed,
superactive, frigid
Cumulic Haplustolls
Fine-loamy, mixed,
superactive, frigid Typic
Argiustolls
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data
as of the version date(s) listed below.
Soil Survey Area: Gallatin County Area, Montana
Survey Area Data: Version 23, Sep 16, 2019
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Sep 10, 2012—Nov
12, 2016
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Soil Taxonomy Classification—Gallatin County Area, Montana
(Soil Taxonomy, - Lakes 2020)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 2 of 5
Soil Taxonomy Classification
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
448A Hyalite-Beaverton
complex, moderately
wet, 0 to 2 percent
slopes
Fine-loamy, mixed,
superactive, frigid
Typic Argiustolls
2.5 4.2%
509B Enbar loam, 0 to 4
percent slopes
Fine-loamy, mixed,
superactive, frigid
Cumulic Haplustolls
2.2 3.7%
510B Meadowcreek loam, 0 to
4 percent slopes
Fine-loamy over sandy
or sandy-skeletal,
mixed, superactive,
frigid Fluvaquentic
Haplustolls
18.8 31.8%
537A Lamoose silt loam, 0 to
2 percent slopes
Fine-loamy over sandy
or sandy-skeletal,
mixed, superactive,
calcareous, frigid
Typic Endoaquolls
8.9 15.0%
748A Hyalite-Beaverton
complex, 0 to 4
percent slopes
Fine-loamy, mixed,
superactive, frigid
Typic Argiustolls
26.8 45.2%
Totals for Area of Interest 59.2 100.0%
Soil Taxonomy Classification—Gallatin County Area, Montana Soil Taxonomy, - Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 3 of 5
Description
This rating presents the taxonomic classification based on Soil Taxonomy.
The system of soil classification used by the National Cooperative Soil Survey
has six categories (Soil Survey Staff, 1999 and 2003). Beginning with the
broadest, these categories are the order, suborder, great group, subgroup, family,
and series. Classification is based on soil properties observed in the field or
inferred from those observations or from laboratory measurements. This table
shows the classification of the soils in the survey area. The categories are
defined in the following paragraphs.
ORDER. Twelve soil orders are recognized. The differences among orders reflect
the dominant soil-forming processes and the degree of soil formation. Each order
is identified by a word ending in sol. An example is Alfisols.
SUBORDER. Each order is divided into suborders primarily on the basis of
properties that influence soil genesis and are important to plant growth or
properties that reflect the most important variables within the orders. The last
syllable in the name of a suborder indicates the order. An example is Udalfs (Ud,
meaning humid, plus alfs, from Alfisols).
GREAT GROUP. Each suborder is divided into great groups on the basis of close
similarities in kind, arrangement, and degree of development of pedogenic
horizons; soil moisture and temperature regimes; type of saturation; and base
status. Each great group is identified by the name of a suborder and by a prefix
that indicates a property of the soil. An example is Hapludalfs (Hapl, meaning
minimal horizonation, plus udalfs, the suborder of the Alfisols that has a udic
moisture regime).
SUBGROUP. Each great group has a typic subgroup. Other subgroups are
intergrades or extragrades. The typic subgroup is the central concept of the great
group; it is not necessarily the most extensive. Intergrades are transitions to
other orders, suborders, or great groups. Extragrades have some properties that
are not representative of the great group but do not indicate transitions to any
other taxonomic class. Each subgroup is identified by one or more adjectives
preceding the name of the great group. The adjective Typic identifies the
subgroup that typifies the great group. An example is Typic Hapludalfs.
FAMILY. Families are established within a subgroup on the basis of physical and
chemical properties and other characteristics that affect management. Generally,
the properties are those of horizons below plow depth where there is much
biological activity. Among the properties and characteristics considered are
particle-size class, mineralogy class, cation-exchange activity class, soil
temperature regime, soil depth, and reaction class. A family name consists of the
name of a subgroup preceded by terms that indicate soil properties. An example
is fine-loamy, mixed, active, mesic Typic Hapludalfs.
SERIES. The series consists of soils within a family that have horizons similar in
color, texture, structure, reaction, consistence, mineral and chemical
composition, and arrangement in the profile.
Soil Taxonomy Classification—Gallatin County Area, Montana Soil Taxonomy, - Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 4 of 5
References:
Soil Survey Staff. 1999. Soil taxonomy: A basic system of soil classification for
making and interpreting soil surveys. 2nd edition. Natural Resources
Conservation Service. U.S. Department of Agriculture Handbook 436.
Soil Survey Staff. 2006. Keys to soil taxonomy. 10th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. (The soils in a given
survey area may have been classified according to earlier editions of this
publication.)
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Lower
Soil Taxonomy Classification—Gallatin County Area, Montana Soil Taxonomy, - Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 5 of 5
Gallatin County Area, Montana
510B—Meadowcreek loam, 0 to 4 percent slopes
Map Unit Setting
National map unit symbol: 56vt
Elevation: 4,200 to 5,950 feet
Mean annual precipitation: 12 to 18 inches
Mean annual air temperature: 39 to 45 degrees F
Frost-free period: 90 to 110 days
Farmland classification: Prime farmland if irrigated
Map Unit Composition
Meadowcreek and similar soils: 85 percent
Minor components: 15 percent
Estimates are based on observations, descriptions, and transects of
the mapunit.
Description of Meadowcreek
Setting
Landform: Stream terraces
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Alluvium
Typical profile
A - 0 to 11 inches: loam
Bg - 11 to 25 inches: silt loam
2C - 25 to 60 inches: very gravelly sand
Properties and qualities
Slope: 0 to 4 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Somewhat poorly drained
Capacity of the most limiting layer to transmit water (Ksat):
Moderately high to high (0.57 to 1.98 in/hr)
Depth to water table: About 24 to 42 inches
Frequency of flooding: None
Frequency of ponding: None
Salinity, maximum in profile: Nonsaline to slightly saline (0.0 to 4.0
mmhos/cm)
Available water storage in profile: Low (about 5.1 inches)
Interpretive groups
Land capability classification (irrigated): 2e
Land capability classification (nonirrigated): 3e
Hydrologic Soil Group: C
Ecological site: Subirrigated (Sb) 15-19" p.z. (R044XS359MT),
Subirrigated Grassland (R044BP815MT)
Hydric soil rating: No
Map Unit Description: Meadowcreek loam, 0 to 4 percent slopes---Gallatin County Area,
Montana
Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 1 of 2
Minor Components
Blossberg
Percent of map unit: 10 percent
Landform: Terraces
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Wet Meadow (WM) 15-19" p.z. (R044XS365MT)
Hydric soil rating: Yes
Beaverton
Percent of map unit: 5 percent
Landform: Stream terraces, alluvial fans
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Shallow to Gravel (SwGr) 15-19" p.z.
(R044XS354MT)
Hydric soil rating: No
Data Source Information
Soil Survey Area: Gallatin County Area, Montana
Survey Area Data: Version 23, Sep 16, 2019
Map Unit Description: Meadowcreek loam, 0 to 4 percent slopes---Gallatin County Area,
Montana
Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 2 of 2
Gallatin County Area, Montana
748A—Hyalite-Beaverton complex, 0 to 4 percent slopes
Map Unit Setting
National map unit symbol: 570v
Elevation: 4,350 to 6,150 feet
Mean annual precipitation: 15 to 19 inches
Mean annual air temperature: 39 to 45 degrees F
Frost-free period: 90 to 110 days
Farmland classification: Farmland of local importance
Map Unit Composition
Hyalite and similar soils: 70 percent
Beaverton and similar soils: 20 percent
Minor components: 10 percent
Estimates are based on observations, descriptions, and transects of
the mapunit.
Description of Hyalite
Setting
Landform: Alluvial fans, stream terraces
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Loamy alluvium
Typical profile
A - 0 to 5 inches: loam
Bt1 - 5 to 9 inches: clay loam
Bt2 - 9 to 17 inches: silty clay loam
2Bt3 - 17 to 26 inches: very cobbly sandy clay loam
3C - 26 to 60 inches: very cobbly loamy sand
Properties and qualities
Slope: 0 to 4 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Capacity of the most limiting layer to transmit water (Ksat):
Moderately high (0.20 to 0.57 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 5 percent
Available water storage in profile: Low (about 4.4 inches)
Interpretive groups
Land capability classification (irrigated): 3e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: C
Ecological site: Shallow to Gravel (SwGr) 15-19" p.z.
(R044XS354MT), Upland Grassland (R044BP818MT)
Map Unit Description: Hyalite-Beaverton complex, 0 to 4 percent slopes---Gallatin County
Area, Montana
Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 1 of 3
Hydric soil rating: No
Description of Beaverton
Setting
Landform: Alluvial fans, stream terraces
Down-slope shape: Linear
Across-slope shape: Linear
Parent material: Alluvium
Typical profile
A - 0 to 5 inches: cobbly loam
Bt - 5 to 21 inches: very gravelly clay loam
Bk - 21 to 25 inches: very cobbly coarse sandy loam
2Bk - 25 to 60 inches: extremely cobbly loamy coarse sand
Properties and qualities
Slope: 0 to 4 percent
Depth to restrictive feature: More than 80 inches
Natural drainage class: Well drained
Capacity of the most limiting layer to transmit water (Ksat):
Moderately high to high (0.57 to 1.98 in/hr)
Depth to water table: More than 80 inches
Frequency of flooding: None
Frequency of ponding: None
Calcium carbonate, maximum in profile: 15 percent
Salinity, maximum in profile: Nonsaline to very slightly saline (0.0
to 2.0 mmhos/cm)
Available water storage in profile: Low (about 3.7 inches)
Interpretive groups
Land capability classification (irrigated): 4s
Land capability classification (nonirrigated): 6s
Hydrologic Soil Group: B
Ecological site: Shallow to Gravel (SwGr) 15-19" p.z.
(R044XS354MT), Upland Grassland (R044BP818MT)
Hydric soil rating: No
Minor Components
Turner
Percent of map unit: 5 percent
Landform: Stream terraces
Down-slope shape: Linear
Across-slope shape: Linear
Ecological site: Silty (Si) 15-19" p.z. (R044XS355MT)
Hydric soil rating: No
Hyalite
Percent of map unit: 5 percent
Landform: Alluvial fans, stream terraces
Down-slope shape: Linear
Across-slope shape: Linear
Map Unit Description: Hyalite-Beaverton complex, 0 to 4 percent slopes---Gallatin County
Area, Montana
Lakes 2020
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 2 of 3
Hydric Rating by Map Unit—Gallatin County Area, Montana
(Hydric Rating, - Lakes 2020)
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
4/9/2020
Page 1 of 550583005058390505848050585705058660505875050588405058300505839050584805058570505866050587505058840490820490910491000491090491180491270491360491450491540491630491720
490820 490910 491000 491090 491180 491270 491360 491450 491540 491630 491720
45° 40' 59'' N 111° 7' 4'' W45° 40' 59'' N111° 6' 22'' W45° 40' 40'' N
111° 7' 4'' W45° 40' 40'' N
111° 6' 22'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,170 if printed on A landscape (11" x 8.5") sheet.
Soil Map may not be valid at this scale.
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
39
2020 ‐ Lakes At Valley West SOG, Bozeman, MT April 10th, 2020 ‐ Project: 020025CR
P.O. Box 6217, Bozeman, Montana, 59771 C: (406) 209‐5573 O: (406) 221‐7236
40