HomeMy WebLinkAbout022 Geology, Soils, and SlopeJarrett Subdivision
Preliminary Plat Application
Geology, Soils, and Slope
Included in this section is the preliminary geotechnical assessment report performed by Allied
Engineering. The items in bold below are the items outlined in the Bozeman Municipal Code.
The NRCS Soil Report is included in this submittal.
a. Geologic hazards. Identify geologic hazards affecting the proposed subdivision which
could result in property damage or personal injury due to rock falls or slides; landslides,
mud or snow; surface subsidence (i.e., settling or sinking); or seismic activity.
There are no known geologic hazards, areas of instability, or unusual soil, topographic or
geologic conditions present on site. The site topography slopes at a 1.5% in a northeasterly
direction.
b. Protective measures. Explain what measures will be taken to prevent or materially
lessen the danger of future property damage or injury due to any of the hazards referred
to in subsection A.4.a of this section.
As aforementioned, there are no known geologic hazards, areas of instability, or unusual soil,
topographic or geologic conditions present on site. Therefore, no additional protective
measures are proposed to prevent or material lessen the danger of future property damage or
injury due to any of the hazards referred to in subsection A.4.a.
c. Unusual features. Provide a statement describing any unusual soil, topographic or
geologic conditions on the property which limit the capability for building or excavation
using ordinary and reasonable construction techniques. The statement should address
conditions such as shallow bedrock, high water table, unstable or expansive soil
conditions, and slope. On a map, identify any slopes in excess of 15 percent grade.
There are no unusual features on site. There are no unusual soils, topographic or geologic
conditions on the property, which will limit the capability for building or excavation using
ordinary reasonable construction techniques. There is no known of the following on site:
shallow bedrock, high water table, unstable or expansive soil conditions, and slope. These can
be confirmed in the geotechnical report in Section 3.C. of this application. The site topography
slopes at a 1.5% in a northeasterly direction.
d. Soils map. The subdivision must be overlaid on the county soil survey maps obtained
from the Natural Resource and Conservation Service (NRCS). The maps are 1:24,000 in
scale. These maps may be copied without permission. However, enlargement of these
maps could cause misunderstanding of the detail of mapping. Soils were mapped using a
minimum delineation of five acres, and these soils reports were intended to alert
developers to possible problems and the need for a more detailed on-site investigation.
The developer must provide the following soil reports, which can be obtained from the
NRCS:
1. The physical properties and engineering indexes for each soil type;
Jarrett Subdivision
Preliminary Plat Application
2. Soil limitations for building and site development, and water features for each soil
type;
3. Hydric soils report for each soil type. If hydric soils are present, the developer must
provide a wetlands investigation by a certified consultant, using the current Federal
Manual for Identifying and Delineating Jurisdictional Wetlands; and
4. The developer must provide any special design methods planned to overcome the above
limitations.
Included in this section is an NRCS soils map overlaid with the subdivision. This map shows
that the majority of the Allison Subdivision Phase IV contains 350B soils, which is described
in detail in the NRCS soils report included in this section.
e. Cuts and fills. Describe the location and amount of any cut or fill three or more feet in
depth. These cuts and fills should be indicated on a plat overlay or sketch map. Where
cuts or fills are necessary, describe any plans to prevent erosion and to promote
revegetation such as replacement of topsoil and grading.
Proposed road and lot grades will not exceed 3-percent and slope work will not exceed a 4:1
horizontal:vertical ratio. Cuts/fills required during construction will be minor and will be
less than three feet deep. A Storm Water Pollution Prevention Plan (SWPPP) will be
required to be approved before any construction begins. The SWPPP will contain Best
Management Practices (BMPs) that will be required to be implemented during construction
that will manage sediment and minimize erosion during construction. The SWPPP will also
require revegetation.
Preliminary Geotechnical Assessment
Jarrett Subdivision – Bozeman, MT
Project: 22-169
March 2, 2023
Allied Engineering Services, Inc. Page 2
PROJECT UNDERSTANDING
The project will be a “tight” residential subdivision with small lots. Based on a preliminary layout, the
subdivision area will contain a number of local city streets as well as an alleyway area behind the lots
that front S. 11th Avenue as well as Arnold Street. It is our understanding that all lots will contain single-
family homes. We expect that most homes will be underlain by crawl spaces. Due to the deeper ground
-water conditions, it appears that basement foundation configurations will also be an option. The final
recommendation for basements will be based on the groundwater monitoring data that is collected
during the 2023 high water season.
EXPLORATIONS, TESTING, AND SUBSURFACE CONDITIONS
Subsurface Explorations
Our first phase of subsurface explorations was conducted on December 14, 2022. This included the
drilling of three boreholes (BH-1 through BH-3) to a depth of about 15 feet each. The investigation was
overseen by Lee Evans, a professional geotechnical engineer with Allied Engineering. The three borings
were located near the northeast and southeast corners of the site as well as along the west-central side.
The borings were drilled with a sub-contract drill rig provided by O’Keefe Drilling. During the drilling, soil
samples and standard penetration test data was collected at 2.0 to 3.0-foot intervals. See Figure 1 for
the borehole locations.
Soil Conditions
In general, the project site is blanketed by 9 to 12 inches of topsoil and underlain by 6.0 to 8.0 feet of
sandy silt to sandy lean clay. The silt/clay is medium stiff to stiff and increases in moisture with depth.
Beginning at depths of 7.0 to 9.0 feet is the sandy gravel, which extended to the bottom of the 15-foot
deep boreholes.
Provided in Table 1 is a summary of soil conditions observed in BH-1 through BH-3. This terminology
matches the attached borehole logs.
Table 1. Summary of Soil Conditions in BH-1 through BH-3
BH
# BH LOCATION RANDOM
FILL
NATIVE
TOPSOIL
NATIVE
SILT/CLAY
NATIVE
SANDY GRAVEL
1 NE Corner of Site -------- 0.0’ - 0.8’ 0.8’ - 9.0’ 9.0’ - 14.4’
2 West-Central Side of Site -------- 0.0’ - 1.0’ 1.0’ - 7.0’ 7.0’ - 15.5’
3 SE Corner of Site -------- 0.0’ - 0.8’ 0.8’ - 8.0’ 8.0’ - 15.5’
Notes: 1) All soil measurements are depths below existing ground.
Preliminary Geotechnical Assessment
Jarrett Subdivision – Bozeman, MT
Project: 22-169
March 2, 2023
Allied Engineering Services, Inc. Page 3
Groundwater Conditions
In December 2022, the depth to groundwater across the site was approximately 13.5 feet. This depth
was recorded in all three borings.
Provided in Table 2 is a summary of the groundwater depths measured in the 3 boreholes on 12/14/22.
Also included in the table is the groundwater depth relative to the top of the native sandy gravel.
Table 2. Summary of Groundwater Depths in BH-1 through BH-3 (on 12/14/22)
BH
# BH LOCATION GROUNDWATER
DEPTH
GW DEPTH RELATIVE TO TOP
OF NATIVE SANDY GRAVEL
1 NE Corner of Site 13.5’ (+/-) 4.5’ below top of gravel
2 West Central Side of Site 13.5’ (+/-) 6.5’ below top of gravel
3 SE Corner of Site 13.5’ (+/-) 5.5’ below top of gravel
Notes: 1) All groundwater measurements are depths below existing ground. 2) Groundwater levels will rise in the spring due to snow melt, recharge, and spring rains.
SUMMARY OF SITE CONDITIONS
Provided below is a summary of the site conditions:
• No random fill was found in any of the explorations. All soils are native and in-place.
• The entire property is blanketed by 9 to 12 inches of organic topsoil.
• Underlying the topsoil is 6.0 to 8.0 feet of non-organic silt/clay. Depending on location and
depth, the soils are in a medium stiff to stiff condition. None of the soils were found to be soft.
In general, they are slightly moist in the upper half, but become more moist with depth.
• Underlying the silt/clay is sandy gravel with 3” to 6” gravels/cobbles. The gravel depth across
the site ranges from 7.0 to 9.0 feet. The sandy gravel extended to the bottom of the boreholes
at 15 feet.
• In December, the groundwater depth was at about 13.5 feet across the entire project site.
• The water levels will rise in the spring; but will likely not rise by more than 4.0 feet. Thus, the
seasonal high groundwater level is expected to remain at depths below 9.0 feet and not rise
above the top of the native gravel.
Preliminary Geotechnical Assessment
Jarrett Subdivision – Bozeman, MT
Project: 22-169
March 2, 2023
Allied Engineering Services, Inc. Page 4
SUMMARY OF GEOTECHNICAL ISSUES
Based on the borings, the site appears to not have any geotechnical issues. It is underlain by typical,
Bozeman-area soils and no random fill. Standard subdivision infrastructure construction is expected. A
quick discussion on road building and utility installation is provided below. The silt/clay soils are not
suitable for the direct placement of house footings without some foundation improvement in order to
reduce any settlement risks.
• Groundwater Dewatering: Depending on the depth of the water and sewer utilities and the
time of year, some groundwater dewatering may be required during utility installation.
• Stable Subgrade During Road Building: We expect slightly moist to moist soil conditions and
stable subgrade during street and alleyway construction. We do not expect any issues with soft
subgrade. If some areas are overly moist, they may need to be dried out and scarified.
• Trench Backfill: Trench backfill material will mainly consist of silt/clay, which underlies the site
depths of 7.0 to 9.0 feet. We do not expect any issues with backfill compaction due to slightly
moist to moist, soil conditions.
SUMMARY OF RECOMMENDATIONS
Provided below is a summary of the geotechnical recommendations for the project:
• For local streets and alleys, the design pavement section (Option 1) is provided below. This
section requires stable subgrade (dry, hard, and compacted). See the design calculations at the
back of the report.
o 3” Asphalt
o 6” Base Gravel
o 15” Sub-Base Gravel
o 315 lb. Woven Geotextile Fabric
o Stable Subgrade (Dry, Hard, Compacted)
24” Total Section Thickness
• The local street section is designed for a traffic ESAL loading capacity of 150,000 ESALs.
• We have used the 24-inch, local street section for all the streets in the Meadow Creek and Gran
Cielo Subdivisions, which are located to the west/southwest of the site (west of S. 19th Ave).
• For collector streets, the design pavement section (Option 1) is provided on the following page.
This section requires stable subgrade (dry, hard, and compacted). See the design calculations at
the back of the report. Note: This section will most likely not be needed for the project.
Preliminary Geotechnical Assessment
Jarrett Subdivision – Bozeman, MT
Project: 22-169
March 2, 2023
Allied Engineering Services, Inc. Page 5
o 4” Asphalt (Placed in 2 – 2” lifts)
o 6” Base Gravel
o 18” Sub-Base Gravel
o 315 lb. Woven Geotextile Fabric
o Stable Subgrade (Dry, Hard, Compacted)
28” Total Section Thickness
• The collector street section is designed for a traffic ESAL loading capacity of 550,000 ESALs.
• We have used the 28-inch, collector street section on W. Graf Street (to the south of the site)
and S. 11th Avenue (to the east of the site).
• If there will be any underground stormwater detention systems on the project, we recommend
that they be over-excavated down to native gravel and filled back up to system grades with
fabric-covered, over-sized cobbles.
• We expect that most houses will be underlain by crawl space foundations. Due to the deeper
groundwater conditions, crawl spaces are allowable.
• Assuming that seasonal high water in the spring/summer of 2023 remains at depths of 9.0 feet
or deeper, then basement foundations will be allowable as well. Groundwater monitoring data
is required before a final decision will be made on the acceptable use of basements.
• For foundation bearing, we do not recommend bearing the houses directly on the silt/clay.
These soils will be susceptible to some settlement potential. The sandy gravel at 7.0 to 9.0 feet
is the best bearing material; but due to the depth, it will likely be too costly to bear the single-
family homes on (due to deep over-excavation and granular structural fill replacement).
• For crawl space foundations, there are four options for foundation support or improvement.
These include:
o Over-excavation (down to native gravel) and granular structural fill placement (back up
to footing grade).
o Rammed aggregate piers (down to native gravel).
o Helical piers (down to native gravel) and grade beam foundations.
o 2.0 to 3.0 feet of building pad granular structural fill thickness (throughout foundation
footprint area) that is reinforced with 2 to 3 layers of geogrid.
Consolidation testing will be completed to finalize this recommendation.
FIELD LOG OF BORING
PROJECT: Jarrett Subdivision JOB #: 22-169 DATE: 12/14/22 BORING: BH-1 PAGE: 1 of 1
LOCATION: NE Corner of Site ELEV: N/A TOTAL DEPTH: 14.4’ DEPTH TO GW: 13.5’ (+/-)
DRILL TYPE: Truck-Mounted CASING/HAMMER/SAMPLER: 4.25” Hollow Stem Auger w/ 140 lb Hammer
DEPTH (FT)SAMPLE IDN (UNCORR)BLOWS/1.0 FOOTMOISTURECONTENTSAMPLER PENETRATIONGEOLOGYBottom of borehole @ 12.00 m
N/A
6
18
8
N/A
7
6
8
3
100/11”
4”
0.5”
18
11 18”
18”
Start Depth of Sampler: 2.0’
End Depth of Sampler: 3.5’
Blow Counts: 3 / 4 / 3
Start Depth of Sampler: 0.0’
End Depth of Sampler: 1.5’
Blow Counts: 2 / 3 / 3
Start Depth of Sampler: 14.0’
End Depth of Sampler: 14.3’
Blow Counts: 50 for 3”
Start Depth of Sampler: 16.5’
End Depth of Sampler: 16.8’
Blow Counts: 50 for 4”
Start Depth of Sampler: 17.0’
End Depth of Sampler: 17.0’
Blow Counts: 50 for 0.5”
From 0.0’ to 2.0’: Some grinding noise
during drilling (indicating gravels).
From 2.0’ to 5.0’: Smooth and fast
drill action. No gravels.
From 5.0’ to 15.0’: Extensive grinding
noise and very slow drilling rate.
50/4”
50/0.5”
50/5” 81/11”
50 for
101.6 mm
N/A
50 for
127.0 mm
N/A
50 for
50.8 mm
N/A
50 for
25.4 mm
50 for
50.8 mm
30.5%
N/AN/A
N/A
N/A
N/A
N/A
N/A
NES**
N/A
5.6%
7.1%
1.8%
00.0%00.0%
11.7%
22.5%
21.2%
N/A
23.7%
Wet
N/T = Not Tested00.0%
23.5%
5.4%
3.3%
5.4%
2.8%
1.9%
4.8%
6.5%
14.1%
11.8%
2.9%
16.4%
S1-A(1)
@ 0.33’
(SSS**)
S1-A(2)
@ 0.58’
(SSS**)
S1-B
@ 2.0’
(SSS)
S1-A
@ 0.0’
(SSS)
9”
50/3”
50/5”
50/5”
50/5”
7.8%
64
11
91/11”
50/5”
50/5”
50/3”
18”
18”
18”
18”
Start Depth of Sampler: 5.5’
End Depth of Sampler: 7.0’
Blow Counts: 3 / 3 / 5
Start Depth of Shelby Tube: 4.0’
End Depth of Shelby Tube: 5.5’
Start Depth of Sampler: 12.0’
End Depth of Sampler: 12.9’
Blow Counts: 26 / 50 for 5”
Start Depth of Sampler: 14.0’
End Depth of Sampler: 14.4’
Blow Counts: 50 for 5”
S1-C
@ 5.5’
(SSS)
S1
@ 4.0’
(Shelby)
S1-F
@ 12.0’
(SSS)
S1-G
@ 14.0’
(SSS)
18”
Start Depth of Sampler: 9.0’
End Depth of Sampler: 9.4’
Blow Counts: 50 for 5”
Start Depth of Sampler: 7.0’
End Depth of Sampler: 8.5’
Blow Counts: 3 / 5 / 6
S1-D
@ 7.0’
(SSS)
S1-E
@ 9.0’
(SSS)
50/4”
11”
Wet 64 18”
Start Depth of Sampler: 17.0’
End Depth of Sampler: 18.5’
Blow Counts: 12 / 29 / 35
S1-H
@ 17.0’
(SSS)
Wet 50/4”
Start Depth of Sampler: 19.0’
End Depth of Sampler: 19.8’
Blow Counts: 12 / 50 for 4”
10”
S1-I
@ 19.0’
(SSS)
50/5” 11”
Start Depth of Sampler: 29.0’
End Depth of Sampler: 29.9’
Blow Counts: 32 / 50 for 5”
Wet
S8-M
@ 29.0’
(SSS)
84
Start Depth of Sampler: 29.0’
End Depth of Sampler: 30.5’
Blow Counts: 27 / 41 / 43
Wet 18”
S1-K
@ 29.0’
(SSS)
5”
5”
S1-M
@ 34.0’
(SSS)
Wet 50/3”
Start Depth of Sampler: 34.0’
End Depth of Sampler: 34.8’
Blow Counts: 21 / 50 for 3”
9”
S1-M
@ 34.0’
(SSS)
50/3”
50/5” 11”
Start Depth of Sampler: 24.0’
End Depth of Sampler: 24.9’
Blow Counts: 22 / 50 for 5”
Wet
S1-J
@ 24.0’
(SSS)
50/2”
71/11”
Start Depth of Sampler: 26.0’
End Depth of Sampler: 26.2’
Blow Counts: 50 for 2”
Wet
S2B-L
@ 26.0’
(SSS*)
2”
3” Start Depth of Sampler: 12.0’
End Depth of Sampler: 12.3’
Blow Counts: 50 for 4”
50/4”
50/3”
4.7%
S1-J
@ 22.0’
(NSC**)
S1-K
@ 24.5’
(NSC**)
S1-H
@ 16.5’
(SSS*)
S1-I
@ 17.0’
(SSS*)
S9-F(1)
@ 5.94 m
(SSS)
S9-F(2)
@ 5.49 m
to 6.71 m
(SACK)
S9-G(1)
@ 7.47 m
(SSS)
S9-G(2)
@ 7.01 m
to 8.23 m
(SACK)
DRILLER: Bridger O’Keefe, O’Keefe Drilling (Butte, MT) FIELD ENGINEER: Lee Evans, AESI
ALLIEDENGINEERINGSERVICES, INC.
Civil Engineering
Geotechnical Engineering
Land Surveying
32 Discovery Drive
Bozeman, MT 59718
Phone: (406) 582-0221
Fax: (406) 582-5770
1
2
3
4
5
Laboratory test results for CS-9
(Includes: S9-A, S9-B, and S9-C)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 14.0 %
= 52.0 %
= 34.0 %
= 22.0 %
= 18.1 %
= 3.9 %
= CL-ML
Laboratory test results for CS-6/9
(Includes: S6-F, S9-F(2), and S9-I)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 14.2 %
= 46.9 %
= 38.9 %
= 36.0 %
= 17.0 %
= 19.0 %
= CL
Laboratory test results for S9-D(2)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 11.6 %
= 50.1 %
= 38.3 %
= 27.0 %
= 14.0 %
= 13.0 %
= CL
Bottom of borehole @ 14.4’
Very dense to hard; burnt red; weathered siltstone or sandstone BEDROCK;
dry. Drill cuttings are clayey SAND to sandy SILT with abundant bedrock
fragments. Fragments are platey and layered in appearance, but non-friable
and intact. Occasional layers of less dense (more weathered) bedrock were
encountered in lower half of this layer.
Bottom of weathered bedrock layer @ 8.84 m
From 2.74 to 6.10 m (approximate), the
rate of the drilling slowed; however, it
was smooth. Minimal grinding noise
could be heard.
From 1.52 to 2.74 m (approximate),
grinding noises were obvious.
From 6.10 to 8.84 m (approximate), the
rate of the drilling was non-uniform. It
was slow in upper half of layer, but got
noticeably faster in lower half. By bot-
tom of the layer, the drill rate was very
slow.
From 8.84 to 12.00 m (approximate), the
rate of the drilling was very, very slow.
Loud grinding noises were heard; and the
auger bit was jumping excessively.
Ground vibrations were widespread. It
took 1.0 hour to penetrate bottom 1.50 m
of borehole.
{0.0’ - 0.33’}: Asphalt (4.0”)
{0.33’ - 0.58’}: Base Course Gravel (3.0”)
Dense; brown; 1.5”-minus, sandy GRAVEL;
slightly moist. Clean, imported sand and gravel.
{1.17’ - 2.0’}: Sub-Base: Clay, Silt, Sand, Gravel
Brown; clayey SAND w/ gravel to clayey, sandy,
GRAVEL; moist to very moist. Somewhat sticky
and plastic. Predominately sands and gravels, but
significant clay content. “Dirty” sand and gravel.
Note: Could be more silty/clayey in some areas.
Borehole Elevation Datum:
* NGVD #29 (Converted to COB)
8
4
20
16
12
24
28
and 2” O.D. Standard Split Spoon Samplers
OTHER FIELD OR
SAMPLE INFORMATION
Reviewed By: __________
Reviewed By: __________
Valley Center Rd - Bozeman
(See Figs. 1, 2, & 3 for Location)
B-61 Drill Rig
Laboratory Testing of Composite Sample A
(from BH-1, BH-2, BH-3, BH-4, BH-5, BH-6, BH-7, & BH-8)
Percent Silt/Clay:
Percent Sand/Gravel:
Liquid Limit:
Plastic Limit:
Plasticity Index:
Unified Soil Classification:
Maximum Dry Density:
Optimum Moisture:
pH:
Marble pH:
Sulfate:
Conductivity:
= 81 %
= 19 %
= 31 %
= 18 %
= 13 %
= CL
= 111.8 pcf
= 15.8 %
= 0.0 s.u.
= 0.0 s.u.
= 0.000 %
= 0.00 mmhos/cm
Laboratory Testing of Composite Sample B
(from BH-1, BH-2, BH-3, BH-4, BH-5, BH-6, BH-7, & BH-8)
pH:
Marble pH:
Sulfate:
Conductivity:
= 0.0 s.u.
= 0.0 s.u.
= 0.000 %
= 0.00 mmhos/cm
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
Groundwater Observation Note:
* The groundwater depth that was measured does not
represent seasonal high conditions. Groundwater is
expected to rise in April, May, and June.
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
** Modified California Sampler
(Dimensions: 3” o.d. and 2.5” i.d.)
DESCRIPTION OF MATERIALS
Important Note:
The beginning and ending depths of the
individual soil layers are approximate.
Bozeman, MT
Drill Action Observations and Notes:
1) From 0.5’ to 1.8’: Loud grinding w/ vibrations.
2) From 1.8’ to 16.0’: Smooth, easy, and fast drill
w/ minimal grinding noise.
3) At 16.0’: Hit gravel - Start of grinding/vibrations.
4) From 16.0’ to 29.9’: Grinding noise and auger
vibrations. Generally pretty slow, but faster and
less grinding in some areas (likely indicating
more sands and/or smaller gravels). Louder and
more vibrations in other areas (likely indicating
larger and/or abundant gravels).
5) Below 23.0’: Slower drill action w/ grinding.
Note: Groundwater monitoring well installed in BH-8
{9.0’ - 14.4’}: Native Sandy Gravel
Dense to very dense; brown; sandy GRAVEL w/
abundant gravels & cobbles; slightly moist to wet.
Notes:
- Start of significant grinding at 9.0’ (+/-).
- Loud grinding and auger vibrations.
- Top of native sandy gravel is at 9.0’ (+/-).
- Pretty “clean” sandy gravel.
- No noticeable silt/clay seams in SSS samples.
- Based on blow counts, dense to very dense soils.
- Blow counts = 10 - 30: Medium dense.
- Blow counts = 30 - 50: Dense.
- Blow counts > 50: Very dense.
- “Target” foundation bearing at 9.0’ and below.
{21.0’ - 25.5’}: Very Weathered Bedrock
Very stiff to dense; brown to orangish brown;
sandy SILT to silty fine SAND to gravelly coarse
SAND; very moist to wet.
Notes:
- Smooth drill action beginning at 21.0’.
- Start of Tertiary bedrock strata (silt/sand).
- Gravelly coarse sand below 24.0’.
{0.8’ - 9.0’}: Native Silt/Clay
Medium stiff to stiff; brown/tan to orangish brown;
sandy SILT to sandy lean CLAY; slightly moist to
moist to very moist (w/ increasing depth).
Notes:
- Smooth and easy drill action entire depth.
- No apparent intermixed gravels (no grinding).
- Some expected gravels in lowermost 6 inches.
- Hit top of native sandy gravel at 9.0’ (+/-).
- Based on start of loud/consistent grinding.
- Based on blow counts, medium stiff to stiff soils.
- Blow counts = 2 - 4: Soft.
- Blow counts = 4 - 8: Medium stiff.
- Blow counts = 8 - 15: Stiff
- Blow counts = 15 - 30: Very stiff.
- Soils are slightly moist to moist to very moist.
- Moisture content generally increases w/ depth.
- Soils in upper 1.0’ were more moist due to snow.
- Soils at 5.5’ and below were very moist (>20%).
- Soils at 5.5’ and below were orangish brown.
- Unsuitable foundation bearing material.
{0.0’ - 0.8’}: Native Topsoil (9”)
Stiff; black to dark brown; organic clayey SILT
w/ roots; slightly moist to moist.
{1.25’ - 5.0’}: Native Silt/Clay
Medium stiff to stiff; brown to tan; sandy SILT
to sandy lean CLAY w/ some small gravels around
3.5’; slightly moist to moist.
Notes:
- Lower 1.0’ (+/-) likely contains some scattered
gravels. This is a transitional zone and does not
constitute clean sandy gravel.
- Unsuitable foundation bearing material.
LSE, 2/7/23
Composite Sample A @ 2.0’ - 10.0’
Note: No lab testing conducted.
= 36.0 %
= 17.0 %
= 19.0 %
= CL
= 000.0 pcf
= 00.0 %
FIELD LOG OF BORING
PROJECT: Jarrett Subdivision JOB #: 22-169 DATE: 12/14/22 BORING: BH-2 PAGE: 1 of 1
LOCATION: West-Central Side of Site ELEV: N/A TOTAL DEPTH: 15.5’ DEPTH TO GW: 13.5’ (+/-)
DRILL TYPE: Truck-Mounted CASING/HAMMER/SAMPLER: 4.25” Hollow Stem Auger w/ 140 lb Hammer
DEPTH (FT)SAMPLE IDN (UNCORR)BLOWS/1.0 FOOTMOISTURECONTENTSAMPLER PENETRATIONGEOLOGYBottom of borehole @ 12.00 m
N/A
6
18
N/A
6
8
3
100/11”
4”
0.5”
18
11 18”
18”
Start Depth of Sampler: 2.0’
End Depth of Sampler: 3.5’
Blow Counts: 6 / 6 / 4
Start Depth of Sampler: 0.0’
End Depth of Sampler: 1.5’
Blow Counts: 3 / 2 / 4
Start Depth of Sampler: 14.0’
End Depth of Sampler: 14.3’
Blow Counts: 50 for 3”
Start Depth of Sampler: 16.5’
End Depth of Sampler: 16.8’
Blow Counts: 50 for 4”
Start Depth of Sampler: 17.0’
End Depth of Sampler: 17.0’
Blow Counts: 50 for 0.5”
From 0.0’ to 2.0’: Some grinding noise
during drilling (indicating gravels).
From 2.0’ to 5.0’: Smooth and fast
drill action. No gravels.
From 5.0’ to 15.0’: Extensive grinding
noise and very slow drilling rate.
50/4”
50/0.5”
50/5” 81/11”
50 for
101.6 mm
N/A
50 for
127.0 mm
N/A
50 for
50.8 mm
N/A
50 for
25.4 mm
50 for
50.8 mm
30.5%
N/AN/A
N/A
N/A
N/A
N/A
N/A
NES**
N/A
5.6%
7.1%
1.8%
00.0%00.0%
12.6%
22.5%
22.2%
N/A
Wet
N/T = Not Tested00.0%
23.5%
5.4%
3.7%
9.1%
5.9%
2.8%
1.9%
4.8%
6.5%
14.1%
11.8%
2.9%
16.4%
S1-A(1)
@ 0.33’
(SSS**)
S1-A(2)
@ 0.58’
(SSS**)
S2-B
@ 2.0’
(SSS)
S2-A
@ 0.0’
(SSS)
9”
50/3”
50/5”
50/5”
7.8%
64
50
74
36
10
91/11”
50/5”
50/5”
50/3”
18”
18”
18”
18”
Start Depth of Sampler: 5.5’
End Depth of Sampler: 7.0’
Blow Counts: 5 / 11 / 25
Start Depth of Shelby Tube: 4.0’
End Depth of Shelby Tube: 5.5’
Start Depth of Sampler: 12.0’
End Depth of Sampler: 12.9’
Blow Counts: 22 / 50 for 5”
Start Depth of Sampler: 14.0’
End Depth of Sampler: 15.5’
Blow Counts: 20 / 41 / 33
S2-C
@ 5.5’
(SSS)
S2
@ 4.0’
(Shelby)
S2-F
@ 12.0’
(SSS)
S2-G
@ 14.0’
(SSS)
18”
11”
Start Depth of Sampler: 9.0’
End Depth of Sampler: 9.9’
Blow Counts: 27 / 50 for 5”
Start Depth of Sampler: 7.0’
End Depth of Sampler: 8.5’
Blow Counts: 12 / 22 / 28
S2-D
@ 7.0’
(SSS)
S2-E
@ 9.0’
(SSS)
50/4”
11”
18”
Wet 64 18”
Start Depth of Sampler: 17.0’
End Depth of Sampler: 18.5’
Blow Counts: 12 / 29 / 35
S1-H
@ 17.0’
(SSS)
Wet 50/4”
Start Depth of Sampler: 19.0’
End Depth of Sampler: 19.8’
Blow Counts: 12 / 50 for 4”
10”
S1-I
@ 19.0’
(SSS)
50/5” 11”
Start Depth of Sampler: 29.0’
End Depth of Sampler: 29.9’
Blow Counts: 32 / 50 for 5”
Wet
S8-M
@ 29.0’
(SSS)
84
Start Depth of Sampler: 29.0’
End Depth of Sampler: 30.5’
Blow Counts: 27 / 41 / 43
Wet 18”
S1-K
@ 29.0’
(SSS)
S1-M
@ 34.0’
(SSS)
Wet 50/3”
Start Depth of Sampler: 34.0’
End Depth of Sampler: 34.8’
Blow Counts: 21 / 50 for 3”
9”
S1-M
@ 34.0’
(SSS)
50/3”
50/5” 11”
Start Depth of Sampler: 24.0’
End Depth of Sampler: 24.9’
Blow Counts: 22 / 50 for 5”
Wet
S1-J
@ 24.0’
(SSS)
50/2”
71/11”
Start Depth of Sampler: 26.0’
End Depth of Sampler: 26.2’
Blow Counts: 50 for 2”
Wet
S2B-L
@ 26.0’
(SSS*)
2”
3” Start Depth of Sampler: 12.0’
End Depth of Sampler: 12.3’
Blow Counts: 50 for 4”
50/4”
50/3”
4.7%
S1-J
@ 22.0’
(NSC**)
S1-K
@ 24.5’
(NSC**)
S1-H
@ 16.5’
(SSS*)
S1-I
@ 17.0’
(SSS*)
S9-F(1)
@ 5.94 m
(SSS)
S9-F(2)
@ 5.49 m
to 6.71 m
(SACK)
S9-G(1)
@ 7.47 m
(SSS)
S9-G(2)
@ 7.01 m
to 8.23 m
(SACK)
DRILLER: Bridger O’Keefe, O’Keefe Drilling (Butte, MT) FIELD ENGINEER: Lee Evans, AESI
ALLIEDENGINEERINGSERVICES, INC.
Civil Engineering
Geotechnical Engineering
Land Surveying
32 Discovery Drive
Bozeman, MT 59718
Phone: (406) 582-0221
Fax: (406) 582-5770
1
2
3
4
5
Laboratory test results for CS-9
(Includes: S9-A, S9-B, and S9-C)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 14.0 %
= 52.0 %
= 34.0 %
= 22.0 %
= 18.1 %
= 3.9 %
= CL-ML
Laboratory test results for CS-6/9
(Includes: S6-F, S9-F(2), and S9-I)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 14.2 %
= 46.9 %
= 38.9 %
= 36.0 %
= 17.0 %
= 19.0 %
= CL
Laboratory test results for S9-D(2)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 11.6 %
= 50.1 %
= 38.3 %
= 27.0 %
= 14.0 %
= 13.0 %
= CL
Bottom of borehole @ 15.5’
Very dense to hard; burnt red; weathered siltstone or sandstone BEDROCK;
dry. Drill cuttings are clayey SAND to sandy SILT with abundant bedrock
fragments. Fragments are platey and layered in appearance, but non-friable
and intact. Occasional layers of less dense (more weathered) bedrock were
encountered in lower half of this layer.
Bottom of weathered bedrock layer @ 8.84 m
From 2.74 to 6.10 m (approximate), the
rate of the drilling slowed; however, it
was smooth. Minimal grinding noise
could be heard.
From 1.52 to 2.74 m (approximate),
grinding noises were obvious.
From 6.10 to 8.84 m (approximate), the
rate of the drilling was non-uniform. It
was slow in upper half of layer, but got
noticeably faster in lower half. By bot-
tom of the layer, the drill rate was very
slow.
From 8.84 to 12.00 m (approximate), the
rate of the drilling was very, very slow.
Loud grinding noises were heard; and the
auger bit was jumping excessively.
Ground vibrations were widespread. It
took 1.0 hour to penetrate bottom 1.50 m
of borehole.
{0.0’ - 0.33’}: Asphalt (4.0”)
{0.33’ - 0.58’}: Base Course Gravel (3.0”)
Dense; brown; 1.5”-minus, sandy GRAVEL;
slightly moist. Clean, imported sand and gravel.
{1.17’ - 2.0’}: Sub-Base: Clay, Silt, Sand, Gravel
Brown; clayey SAND w/ gravel to clayey, sandy,
GRAVEL; moist to very moist. Somewhat sticky
and plastic. Predominately sands and gravels, but
significant clay content. “Dirty” sand and gravel.
Note: Could be more silty/clayey in some areas.
Borehole Elevation Datum:
* NGVD #29 (Converted to COB)
8
4
20
16
12
24
28
and 2” O.D. Standard Split Spoon Samplers
OTHER FIELD OR
SAMPLE INFORMATION
Reviewed By: __________
Reviewed By: __________
Valley Center Rd - Bozeman
(See Figs. 1, 2, & 3 for Location)
B-61 Drill Rig
Laboratory Testing of Composite Sample A
(from BH-1, BH-2, BH-3, BH-4, BH-5, BH-6, BH-7, & BH-8)
Percent Silt/Clay:
Percent Sand/Gravel:
Liquid Limit:
Plastic Limit:
Plasticity Index:
Unified Soil Classification:
Maximum Dry Density:
Optimum Moisture:
pH:
Marble pH:
Sulfate:
Conductivity:
= 81 %
= 19 %
= 31 %
= 18 %
= 13 %
= CL
= 111.8 pcf
= 15.8 %
= 0.0 s.u.
= 0.0 s.u.
= 0.000 %
= 0.00 mmhos/cm
Laboratory Testing of Composite Sample B
(from BH-1, BH-2, BH-3, BH-4, BH-5, BH-6, BH-7, & BH-8)
pH:
Marble pH:
Sulfate:
Conductivity:
= 0.0 s.u.
= 0.0 s.u.
= 0.000 %
= 0.00 mmhos/cm
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
Groundwater Observation Note:
* The groundwater depth that was measured does not
represent seasonal high conditions. Groundwater is
expected to rise in April, May, and June.
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
** Modified California Sampler
(Dimensions: 3” o.d. and 2.5” i.d.)
DESCRIPTION OF MATERIALS
Important Note:
The beginning and ending depths of the
individual soil layers are approximate.
Bozeman, MT
Drill Action Observations and Notes:
1) From 0.5’ to 1.8’: Loud grinding w/ vibrations.
2) From 1.8’ to 16.0’: Smooth, easy, and fast drill
w/ minimal grinding noise.
3) At 16.0’: Hit gravel - Start of grinding/vibrations.
4) From 16.0’ to 29.9’: Grinding noise and auger
vibrations. Generally pretty slow, but faster and
less grinding in some areas (likely indicating
more sands and/or smaller gravels). Louder and
more vibrations in other areas (likely indicating
larger and/or abundant gravels).
5) Below 23.0’: Slower drill action w/ grinding.
Note: Groundwater monitoring well installed in BH-8
{7.0’ - 15.5’}: Native Sandy Gravel
Dense to very dense; brown; sandy GRAVEL w/
abundant gravels & cobbles; slightly moist to wet.
Notes:
- Start of significant grinding at 7.0’ (+/-).
- Loud grinding and auger vibrations.
- Top of native sandy gravel is at 7.0’ (+/-).
- Pretty “clean” sandy gravel.
- No noticeable silt/clay seams in SSS samples.
- Based on blow counts, dense to very dense soils.
- Blow counts = 10 - 30: Medium dense.
- Blow counts = 30 - 50: Dense.
- Blow counts > 50: Very dense.
- “Target” foundation bearing at 7.0’ and below.
{21.0’ - 25.5’}: Very Weathered Bedrock
Very stiff to dense; brown to orangish brown;
sandy SILT to silty fine SAND to gravelly coarse
SAND; very moist to wet.
Notes:
- Smooth drill action beginning at 21.0’.
- Start of Tertiary bedrock strata (silt/sand).
- Gravelly coarse sand below 24.0’.
{1.0’ - 7.0’}: Native Silt/Clay
Medium stiff to stiff; brown/tan to orangish brown;
sandy SILT to sandy lean CLAY; slightly moist to
moist to very moist (w/ increasing depth).
Notes:
- Smooth and easy drill action entire depth.
- No apparent intermixed gravels (no grinding).
- Some expected gravels in lowermost 6 inches.
- Hit top of native sandy gravel at 7.0’ (+/-).
- Based on start of loud/consistent grinding.
- Based on blow counts, medium stiff to stiff soils.
- Blow counts = 2 - 4: Soft.
- Blow counts = 4 - 8: Medium stiff.
- Blow counts = 8 - 15: Stiff
- Blow counts = 15 - 30: Very stiff.
- Soils are slightly moist to moist to very moist.
- Moisture content generally increases w/ depth.
- Soils in upper 1.0’ were more moist due to snow.
- Soils at 5.5’ and below were very moist (>20%).
- Soils at 5.5’ and below were orangish brown.
- Unsuitable foundation bearing material.
{0.0’ - 1.0’}: Native Topsoil (12”)
Stiff; black to dark brown; organic clayey SILT
w/ roots; slightly moist to moist.
{1.25’ - 5.0’}: Native Silt/Clay
Medium stiff to stiff; brown to tan; sandy SILT
to sandy lean CLAY w/ some small gravels around
3.5’; slightly moist to moist.
Notes:
- Lower 1.0’ (+/-) likely contains some scattered
gravels. This is a transitional zone and does not
constitute clean sandy gravel.
- Unsuitable foundation bearing material.
LSE, 2/7/23
Composite Sample A @ 2.0’ - 10.0’
Note: No lab testing conducted.
= 36.0 %
= 17.0 %
= 19.0 %
= CL
= 000.0 pcf
= 00.0 %
FIELD LOG OF BORING
PROJECT: Jarrett Subdivision JOB #: 22-169 DATE: 12/14/22 BORING: BH-3 PAGE: 1 of 1
LOCATION: SE Corner of Site ELEV: N/A TOTAL DEPTH: 15.5’ DEPTH TO GW: 13.5’ (+/-)
DRILL TYPE: Truck-Mounted CASING/HAMMER/SAMPLER: 4.25” Hollow Stem Auger w/ 140 lb Hammer
DEPTH (FT)SAMPLE IDN (UNCORR)BLOWS/1.0 FOOTMOISTURECONTENTSAMPLER PENETRATIONGEOLOGYBottom of borehole @ 12.00 m
N/A
6
18
N/A
7
5
8
3
100/11”
4”
0.5”
18
11 18”
18”
Start Depth of Sampler: 2.0’
End Depth of Sampler: 3.5’
Blow Counts: 4 / 4 / 3
Start Depth of Sampler: 0.0’
End Depth of Sampler: 1.5’
Blow Counts: 3 / 2 / 3
Start Depth of Sampler: 14.0’
End Depth of Sampler: 14.3’
Blow Counts: 50 for 3”
Start Depth of Sampler: 16.5’
End Depth of Sampler: 16.8’
Blow Counts: 50 for 4”
Start Depth of Sampler: 17.0’
End Depth of Sampler: 17.0’
Blow Counts: 50 for 0.5”
From 0.0’ to 2.0’: Some grinding noise
during drilling (indicating gravels).
From 2.0’ to 5.0’: Smooth and fast
drill action. No gravels.
From 5.0’ to 15.0’: Extensive grinding
noise and very slow drilling rate.
50/4”
50/0.5”
50/5” 81/11”
50 for
101.6 mm
N/A
50 for
127.0 mm
N/A
50 for
50.8 mm
N/A
50 for
25.4 mm
50 for
50.8 mm
30.5%
N/AN/A
N/A
N/A
N/A
N/A
N/A
NES**
N/A
5.6%
7.1%
1.8%
00.0%00.0%
12.1%
21.7%
23.9%
N/A
22.2%
Wet
N/T = Not Tested00.0%
23.5%
5.4%
3.1%
7.8%
2.8%
1.9%
4.8%
6.5%
14.1%
11.8%
2.9%
16.4%
S1-A(1)
@ 0.33’
(SSS**)
S1-A(2)
@ 0.58’
(SSS**)
S3-B
@ 2.0’
(SSS)
S3-A
@ 0.0’
(SSS)
9”
50/3”
7.8%
64
13
77
93
98
10
91/11”
50/5”
50/5”
50/3”
18”
18”
18”
18”
Start Depth of Sampler: 5.5’
End Depth of Sampler: 7.0’
Blow Counts: 3 / 5 / 5
Start Depth of Shelby Tube: 4.0’
End Depth of Shelby Tube: 5.5’
Start Depth of Sampler: 12.0’
End Depth of Sampler: 13.5’
Blow Counts: 31 / 48 / 45
Start Depth of Sampler: 14.0’
End Depth of Sampler: 15.5’
Blow Counts: 47 / 50 / 48
S3-C
@ 5.5’
(SSS)
S3
@ 4.0’
(Shelby)
S3-F
@ 12.0’
(SSS)
S3-G
@ 14.0’
(SSS)
18”
18”
Start Depth of Sampler: 9.0’
End Depth of Sampler: 10.5’
Blow Counts: 37 / 31 / 46
Start Depth of Sampler: 7.0’
End Depth of Sampler: 8.5’
Blow Counts: 3 / 2 / 11
S3-D
@ 7.0’
(SSS)
S3-E
@ 9.0’
(SSS)
50/4”
18”
18”
Wet 64 18”
Start Depth of Sampler: 17.0’
End Depth of Sampler: 18.5’
Blow Counts: 12 / 29 / 35
S1-H
@ 17.0’
(SSS)
Wet 50/4”
Start Depth of Sampler: 19.0’
End Depth of Sampler: 19.8’
Blow Counts: 12 / 50 for 4”
10”
S1-I
@ 19.0’
(SSS)
50/5” 11”
Start Depth of Sampler: 29.0’
End Depth of Sampler: 29.9’
Blow Counts: 32 / 50 for 5”
Wet
S8-M
@ 29.0’
(SSS)
84
Start Depth of Sampler: 29.0’
End Depth of Sampler: 30.5’
Blow Counts: 27 / 41 / 43
Wet 18”
S1-K
@ 29.0’
(SSS)
S1-M
@ 34.0’
(SSS)
Wet 50/3”
Start Depth of Sampler: 34.0’
End Depth of Sampler: 34.8’
Blow Counts: 21 / 50 for 3”
9”
S1-M
@ 34.0’
(SSS)
50/3”
50/5” 11”
Start Depth of Sampler: 24.0’
End Depth of Sampler: 24.9’
Blow Counts: 22 / 50 for 5”
Wet
S1-J
@ 24.0’
(SSS)
50/2”
71/11”
Start Depth of Sampler: 26.0’
End Depth of Sampler: 26.2’
Blow Counts: 50 for 2”
Wet
S2B-L
@ 26.0’
(SSS*)
2”
3” Start Depth of Sampler: 12.0’
End Depth of Sampler: 12.3’
Blow Counts: 50 for 4”
50/4”
50/3”
4.7%
S1-J
@ 22.0’
(NSC**)
S1-K
@ 24.5’
(NSC**)
S1-H
@ 16.5’
(SSS*)
S1-I
@ 17.0’
(SSS*)
S9-F(1)
@ 5.94 m
(SSS)
S9-F(2)
@ 5.49 m
to 6.71 m
(SACK)
S9-G(1)
@ 7.47 m
(SSS)
S9-G(2)
@ 7.01 m
to 8.23 m
(SACK)
DRILLER: Bridger O’Keefe, O’Keefe Drilling (Butte, MT) FIELD ENGINEER: Lee Evans, AESI
ALLIEDENGINEERINGSERVICES, INC.
Civil Engineering
Geotechnical Engineering
Land Surveying
32 Discovery Drive
Bozeman, MT 59718
Phone: (406) 582-0221
Fax: (406) 582-5770
1
2
3
4
5
Laboratory test results for CS-9
(Includes: S9-A, S9-B, and S9-C)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 14.0 %
= 52.0 %
= 34.0 %
= 22.0 %
= 18.1 %
= 3.9 %
= CL-ML
Laboratory test results for CS-6/9
(Includes: S6-F, S9-F(2), and S9-I)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 14.2 %
= 46.9 %
= 38.9 %
= 36.0 %
= 17.0 %
= 19.0 %
= CL
Laboratory test results for S9-D(2)
* Grain Size Distribution:
Gravel Portion (> #4)
Sand Portion ( #200 < X < #4)
Silt/Clay Portion (< #200)
* Atterberg Limits:
Liquid Limit
Plastic Limit
Plasticity Index
Plasticity Chart Symbol
= 11.6 %
= 50.1 %
= 38.3 %
= 27.0 %
= 14.0 %
= 13.0 %
= CL
Bottom of borehole @ 15.5’
Very dense to hard; burnt red; weathered siltstone or sandstone BEDROCK;
dry. Drill cuttings are clayey SAND to sandy SILT with abundant bedrock
fragments. Fragments are platey and layered in appearance, but non-friable
and intact. Occasional layers of less dense (more weathered) bedrock were
encountered in lower half of this layer.
Bottom of weathered bedrock layer @ 8.84 m
From 2.74 to 6.10 m (approximate), the
rate of the drilling slowed; however, it
was smooth. Minimal grinding noise
could be heard.
From 1.52 to 2.74 m (approximate),
grinding noises were obvious.
From 6.10 to 8.84 m (approximate), the
rate of the drilling was non-uniform. It
was slow in upper half of layer, but got
noticeably faster in lower half. By bot-
tom of the layer, the drill rate was very
slow.
From 8.84 to 12.00 m (approximate), the
rate of the drilling was very, very slow.
Loud grinding noises were heard; and the
auger bit was jumping excessively.
Ground vibrations were widespread. It
took 1.0 hour to penetrate bottom 1.50 m
of borehole.
{0.0’ - 0.33’}: Asphalt (4.0”)
{0.33’ - 0.58’}: Base Course Gravel (3.0”)
Dense; brown; 1.5”-minus, sandy GRAVEL;
slightly moist. Clean, imported sand and gravel.
{1.17’ - 2.0’}: Sub-Base: Clay, Silt, Sand, Gravel
Brown; clayey SAND w/ gravel to clayey, sandy,
GRAVEL; moist to very moist. Somewhat sticky
and plastic. Predominately sands and gravels, but
significant clay content. “Dirty” sand and gravel.
Note: Could be more silty/clayey in some areas.
Borehole Elevation Datum:
* NGVD #29 (Converted to COB)
8
4
20
16
12
24
28
and 2” O.D. Standard Split Spoon Samplers
OTHER FIELD OR
SAMPLE INFORMATION
Reviewed By: __________
Reviewed By: __________
Valley Center Rd - Bozeman
(See Figs. 1, 2, & 3 for Location)
B-61 Drill Rig
Laboratory Testing of Composite Sample A
(from BH-1, BH-2, BH-3, BH-4, BH-5, BH-6, BH-7, & BH-8)
Percent Silt/Clay:
Percent Sand/Gravel:
Liquid Limit:
Plastic Limit:
Plasticity Index:
Unified Soil Classification:
Maximum Dry Density:
Optimum Moisture:
pH:
Marble pH:
Sulfate:
Conductivity:
= 81 %
= 19 %
= 31 %
= 18 %
= 13 %
= CL
= 111.8 pcf
= 15.8 %
= 0.0 s.u.
= 0.0 s.u.
= 0.000 %
= 0.00 mmhos/cm
Laboratory Testing of Composite Sample B
(from BH-1, BH-2, BH-3, BH-4, BH-5, BH-6, BH-7, & BH-8)
pH:
Marble pH:
Sulfate:
Conductivity:
= 0.0 s.u.
= 0.0 s.u.
= 0.000 %
= 0.00 mmhos/cm
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
Groundwater Observation Note:
* The groundwater depth that was measured does not
represent seasonal high conditions. Groundwater is
expected to rise in April, May, and June.
Split Spoon Sampler Information:
* Standard Penetration Test Sampler
(Dimensions: 2” o.d. and 1.375” i.d.)
** Modified California Sampler
(Dimensions: 3” o.d. and 2.5” i.d.)
DESCRIPTION OF MATERIALS
Important Note:
The beginning and ending depths of the
individual soil layers are approximate.
Bozeman, MT
Drill Action Observations and Notes:
1) From 0.5’ to 1.8’: Loud grinding w/ vibrations.
2) From 1.8’ to 16.0’: Smooth, easy, and fast drill
w/ minimal grinding noise.
3) At 16.0’: Hit gravel - Start of grinding/vibrations.
4) From 16.0’ to 29.9’: Grinding noise and auger
vibrations. Generally pretty slow, but faster and
less grinding in some areas (likely indicating
more sands and/or smaller gravels). Louder and
more vibrations in other areas (likely indicating
larger and/or abundant gravels).
5) Below 23.0’: Slower drill action w/ grinding.
Note: Groundwater monitoring well installed in BH-8
{8.0’ - 15.5’}: Native Sandy Gravel
Dense to very dense; brown; sandy GRAVEL w/
abundant gravels & cobbles; slightly moist to wet.
Notes:
- Start of significant grinding at 8.0’ (+/-).
- Loud grinding and auger vibrations.
- Top of native sandy gravel is at 8.0’ (+/-).
- Pretty “clean” sandy gravel.
- No noticeable silt/clay seams in SSS samples.
- Based on blow counts, dense to very dense soils.
- Blow counts = 10 - 30: Medium dense.
- Blow counts = 30 - 50: Dense.
- Blow counts > 50: Very dense.
- “Target” foundation bearing at 8.0’ and below.
{21.0’ - 25.5’}: Very Weathered Bedrock
Very stiff to dense; brown to orangish brown;
sandy SILT to silty fine SAND to gravelly coarse
SAND; very moist to wet.
Notes:
- Smooth drill action beginning at 21.0’.
- Start of Tertiary bedrock strata (silt/sand).
- Gravelly coarse sand below 24.0’.
{0.8’ - 8.0’}: Native Silt/Clay
Medium stiff to stiff; brown/tan to orangish brown;
sandy SILT to sandy lean CLAY; slightly moist to
moist to very moist (w/ increasing depth).
Notes:
- Smooth and easy drill action entire depth.
- No apparent intermixed gravels (no grinding).
- Some expected gravels in lowermost 6 inches.
- Hit top of native sandy gravel at 8.0’ (+/-).
- Based on start of loud/consistent grinding.
- Based on blow counts, medium stiff to stiff soils.
- Blow counts = 2 - 4: Soft.
- Blow counts = 4 - 8: Medium stiff.
- Blow counts = 8 - 15: Stiff
- Blow counts = 15 - 30: Very stiff.
- Soils are slightly moist to moist to very moist.
- Moisture content generally increases w/ depth.
- Soils in upper 1.0’ were more moist due to snow.
- Soils at 5.5’ and below were very moist (>20%).
- Soils at 5.5’ and below were orangish brown.
- Unsuitable foundation bearing material.
{0.0’ - 0.8’}: Native Topsoil (9”)
Stiff; black to dark brown; organic clayey SILT
w/ roots; slightly moist to moist.
{1.25’ - 5.0’}: Native Silt/Clay
Medium stiff to stiff; brown to tan; sandy SILT
to sandy lean CLAY w/ some small gravels around
3.5’; slightly moist to moist.
Notes:
- Lower 1.0’ (+/-) likely contains some scattered
gravels. This is a transitional zone and does not
constitute clean sandy gravel.
- Unsuitable foundation bearing material.
LSE, 2/7/23
Composite Sample A @ 2.0’ - 10.0’
Note: No lab testing conducted.
= 36.0 %
= 17.0 %
= 19.0 %
= CL
= 000.0 pcf
= 00.0 %
PAVEMENT SECTION DESIGN - Local Streets - Option 1
(Note: This unreinforced design is applicable for stable subgrade conditions (ie. dry, hard, compacted).
Project: Jarrett Subdivision - Bozeman, MT
Project Number: 22-169
Date: March 2, 2023
Prepared By: Lee Evans
Important Notes:
1) See following pages for an Explanation of the Design Input Parameters.
2) Sub-base course shall be comprised of import 6"-minus, sandy pitrun gravel.
DESIGN INPUT PARAMETERS
ESALs (total)150,000
Subgrade CBR, (%)2.50
Subgrade Resilient Modulus, MR (psi)3,750
Reliability, R (%)90Standard Normal Deviate, ZR -1.282
Overall Standard Deviation, So 0.45
Initial Serviceability, po 4.2
Terminal Serviceability, pt 2.0
Design Serviceability Loss, (PSI)2.2
5.17609 = left side
Required Structural Number, RSN 3.20 5.1927 = right side
(Manipulate RSN such that the left and right side of equation match.)
Asphalt Concrete Layer Coefficient, a1 0.41
Base Course Layer Structural Coefficient, a2 0.14
Base Course Layer Drainage Coefficient, m2 0.90
Sub-Base Course Layer Structural Coefficient, a3 0.09
Sub-Base Course Layer Drainage Coefficient, m3 0.90
DESIGN PAVEMENT SECTION
Asphalt Concrete Thickness, D1 (in)3.0
Granular Base Course Thickness, D2 (in)6.0
Granular Sub-Base Course Thickness, D3 (in)15.0
Calculated Structural Number, CSN 3.20
(Manipulate layer thicknesses such that CSN matches or exceeds RSN.)
DESIGN EQUATION
Pavement Section Design: Page 1 of 1
PAVEMENT SECTION DESIGN - Collector Streets - Option 1
(Note: This unreiniforced design is applicable for stable subgrade conditions (ie. dry, hard, compacted).
Project: Jarrett Subdivison - Bozeman, MT
Project Number: 22-169
Date: March 2, 2023
Prepared By: Lee Evans
Important Notes:
1) See following pages for an Explanation of the Design Input Parameters.
2) Sub-base course shall be comprised of import 6"-minus, sandy pitrun gravel.
DESIGN INPUT PARAMETERS
ESALs (total)550,000
Subgrade CBR, (%)2.50
Subgrade Resilient Modulus, MR (psi)3,750
Reliability, R (%)90Standard Normal Deviate, ZR -1.282
Overall Standard Deviation, So 0.45
Initial Serviceability, po 4.2
Terminal Serviceability, pt 2.0
Design Serviceability Loss, (PSI)2.2
5.74036 = left side
Required Structural Number, RSN 3.85 5.7367 = right side
(Manipulate RSN such that the left and right side of equation match.)
Asphalt Concrete Layer Coefficient, a1 0.41
Base Course Layer Structural Coefficient, a2 0.14
Base Course Layer Drainage Coefficient, m2 0.90
Sub-Base Course Layer Structural Coefficient, a3 0.09
Sub-Base Course Layer Drainage Coefficient, m3 0.90
DESIGN PAVEMENT SECTION
Asphalt Concrete Thickness, D1 (in)4.0
Granular Base Course Thickness, D2 (in)6.0
Granular Sub-Base Course Thickness, D3 (in)18.0
Calculated Structural Number, CSN 3.85
(Manipulate layer thicknesses such that CSN matches or exceeds RSN.)
DESIGN EQUATION
Pavement Section Design: Page 1 of 1
Explanation of Design Input Parameters: Page 1 of 3
PAVEMENT SECTION DESIGN – Local and Collector Streets
(EXPLANATION OF DESIGN INPUT PARAMETERS)
Design Life (yr): 20
ESALs (total) – Local Streets: 150,000
ESALs (total) – Collector Streets: 550,000
Soaked Subgrade CBR, (%): 2.5
Subgrade Resilient Modulus, MR (psi): 3,750
Reliability, R (%): 90
Standard Normal Deviate, ZR: -1.282
Overall Standard Deviation, So: 0.45
Initial Serviceability, po: 4.2
Terminal Serviceability, pt: 2.0
Design Serviceability Loss, (PSI) 2.2
Asphalt Concrete Layer Coefficient, a1: 0.41
Base Course Layer Structural Coefficient, a2: 0.14
Base Course Layer Drainage Coefficient, m2: 0.90
Sub-Base Course Layer Structural Coefficient, a3: 0.09
Sub-Base Course Layer Drainage Coefficient, m3: 0.90
Design Life: A design life of 20 years is typical for new asphalt projects in Bozeman,
including city streets and alleys as well as private facilities.
ESALs (total) – Local Streets: According to Table 18.12 in Reference 1, the estimated
design Equivalent 18,000-lb Single Axle Load (ESAL) value for roadways subjected to
light vehicle and medium truck traffic ranges from 10,000 to 1,000,000. Light vehicles
are classified as Class 1, 2, and 3 and have equivalent ESAL values of 0.001 to 0.007 per
trip; while heavier trucks range from Class 4 to 9 and have equivalent ESAL values of
0.257 to 1.462 per trip. We believe that a conservative estimate for ESAL loading on
local streets in the City of Bozeman is 150,000. We have designed several other local
street projects using this design value. For this project, the local street pavement
section design we are recommending is good for 150,000 ESALs.
ESALs (total) – Collector Streets: According to Table 18.12 in Reference 1, the estimated
design Equivalent 18,000-lb Single Axle Load (ESAL) value for roadways subjected to
light vehicle and medium truck traffic ranges from 10,000 to 1,000,000. Light vehicles
are classified as Class 1, 2, and 3 and have equivalent ESAL values of 0.001 to 0.007 per
trip; while heavier trucks range from Class 4 to 9 and have equivalent ESAL values of
Explanation of Design Input Parameters: Page 2 of 3
0.257 to 1.462 per trip. We believe that a conservative estimate for ESAL loading on
collector streets in the City of Bozeman is 500,000. We have designed several other
collector street projects using this design value. For this project, the collector street
pavement section design we are recommending is good for 550,000 ESALs.
Soaked Subgrade CBR: The project site is underlain by sandy silt to sandy lean clay soils
that extend down to depths of 7.0 to 9.0 feet, depending on location. For this reason,
we have designed the new asphalt pavement section improvements based on “fine-
grained, subgrade support conditions”. Over the past years, we have conducted CBR
tests on several samples of the Bozeman-area silt/clay soils. Typically, soaked CBRs for
these soils ranged from 2.0 to 3.0%. Based on these test results, we selected a design
soaked CBR value of 2.5%.
Subgrade Resilient Modulus: For fine-grained soils with a CBR of 10.0 or less, an
accepted correlation between CBR and resilient modulus is MR = 1500 x CBR. Based on
this equation, the design resilient modulus value shall be 3,750 psi.
Reliability: According to Table 2.2 in Reference 2, the recommended reliability level for
local streets in urban settings ranges from 50 to 80 percent, while reliability levels for
collector and principal arterial streets are recommended to be 80 to 95 percent and 80
to 99 percent, respectively. To provide for a greater factor of safety, we chose a design
reliability level of 90 percent for all streets, regardless of functional classification.
Standard Normal Deviate: According to Table 4.1 in Reference 2, a 90 percent reliability
value corresponds to a standard normal deviate of –1.282.
Overall Standard Deviation: According to Sections 2.1.3 and 4.3 in Reference 2, a
design value of 0.45 is recommended for flexible pavements.
Initial Serviceability: According to Section 2.2.1 in Reference 2, a design value of 4.2 is
recommended for flexible pavements.
Terminal Serviceability: According to Section 2.2.1 in Reference 2, a design value of 2.0
is suggested for roads that will be subjected to small traffic volumes; while a value of 2.5
or higher should be used when designing major highways. We selected a terminal
serviceability of 2.0.
Design Serviceability Loss: This is the difference between the initial and terminal
serviceability. Therefore, the design value shall be 2.2.
Asphalt Concrete Layer Coefficient: According to the table with the revised surfacing
structural coefficients in Reference 4, a design value of 0.41 is recommended for all
asphalt plant mix grades. This value replaces the 0.33 asphalt coefficient that was
provided in Table 3-2 of Reference 3.
Explanation of Design Input Parameters: Page 3 of 3
Base Course Layer Structural Coefficient: According to the table with the revised
surfacing structural coefficients in Reference 4, a design value of 0.14 is recommended
for new 1.5”-minus, crushed base course gravel. This value replaces the 0.12 crushed
gravel coefficient that was provided in Table 3-2 of Reference 3.
Base Course Layer Drainage Coefficient: According to Table 2.4 in Reference 2, a
coefficient of 0.80 to 1.00 should be used when fair to good drainage is anticipated
within the pavement structure. We assume good drainage for this project (ie. 1.00);
however, in order to be more conservative, a value of 0.90 was selected for the design.
Sub-Base Course Layer Structural Coefficient: We assume that imported, 6”-minus,
uncrushed sandy (pitrun) gravel will be placed for the sub-base section of the roads.
This is the standard product used in the Bozeman area for sub-base. According to
pavement design charts for gravelly soils, we estimated that 6”-minus pitrun will have a
CBR of between 15.0 and 20.0%, which correlates to a structural coefficient of 0.09.
Sub-Base Course Layer Drainage Coefficient: The drainage coefficients for sub-base
and base course layers are typically the same; therefore, we selected a value of 0.90 for
the design. See the base course layer drainage coefficient section for an explanation.
Reference List
1) Traffic and Highway Engineering; Nicholas J. Garber and Lester A. Hoel; 1988.
2) Design of Pavement Structures; AASHTO; 1993.
3) Pavement Design Manual; Montana Department of Transportation; 1991.
4) Pavement Design Memo; Montana Department of Transportation; May 11, 2006.
5) Geotechnical Manual; Montana Department of Transportation; July 2008.
LIMITATIONS OF YOUR GEOTECHNICAL REPORT
GEOTECHNICAL REPORTS ARE PROJECT AND CLIENT SPECIFIC
Geotechnical investigations, analyses, and recommendations are project and client specific. Each project
and each client have individual criterion for risk, purpose, and cost of evaluation that are considered in the
development of scope of geotechnical investigations, analyses and recommendations. For example, slight
changes to building types or use may alter the applicability of a particular foundation type, as can a
particular client’s aversion or acceptance of risk. Also, additional risk is often created by scope-of-
service limitations imposed by the client and a report prepared for a particular client (say a construction
contractor) may not be applicable or adequate for another client (say an architect, owner, or developer for
example), and vice-versa. No one should apply a geotechnical report for any purpose other than that
originally contemplated without first conferring with the consulting geotechnical engineer. Geotechnical
reports should be made available to contractors and professionals for information on factual data only and
not as a warranty of subsurface conditions, such as those interpreted in the exploration logs and discussed
in the report.
GEOTECHNICAL CONDITIONS CAN CHANGE
Geotechnical conditions may be affected as a result of natural processes or human activity. Geotechnical
reports are based on conditions that existed at the time of subsurface exploration. Construction operations
such as cuts, fills, or drains in the vicinity of the site and natural events such as floods, earthquakes, or
groundwater fluctuations may affect subsurface conditions and, thus, the continuing adequacy of a
geotechnical report.
GEOTECHNICAL ENGINEERING IS NOT AN EXACT SCIENCE
The site exploration and sampling process interprets subsurface conditions using drill action, soil
sampling, resistance to excavation, and other subjective observations at discrete points on the surface and
in the subsurface. The data is then interpreted by the engineer, who applies professional judgment to
render an opinion about over-all subsurface conditions. Actual conditions in areas not sampled or
observed may differ from those predicted in your report. Retaining your consultant to advise you during
the design process, review plans and specifications, and then to observe subsurface construction
operations can minimize the risks associated with the uncertainties associated with such interpretations.
The conclusions described in your geotechnical report are preliminary because they must be based on the
assumption that conditions revealed through selective exploration and sampling are indicative of actual
Allied Engineering Services, Inc. Page 2
conditions throughout a site. A more complete view of subsurface conditions is often revealed during
earthwork; therefore, you should retain your consultant to observe earthwork to confirm conditions and/or
to provide revised recommendations if necessary. Allied Engineering cannot assume responsibility or
liability for the adequacy of the report’s recommendations if another party is retained to observe
construction.
EXPLORATIONS LOGS SHOULD NOT BE SEPARATED FROM THE REPORT Final explorations logs developed by the consultant are based upon interpretation of field logs (assembled
by site personnel), field test results, and laboratory and/or office evaluation of field samples and data.
Only final exploration logs and data are customarily included in geotechnical reports. These final logs
should not be redrawn for inclusion in Architectural or other design drawings, because drafters may
commit errors or omissions in the transfer process.
To reduce the likelihood of exploration log misinterpretation, contractors should be given ready access to
the complete geotechnical report and should be advised of its limitations and purpose. While a contractor
may gain important knowledge from a report prepared for another party, the contractor should discuss the
report with Allied Engineering and perform the additional or alternative work believed necessary to
obtain the data specifically appropriate for construction cost estimating purposes.
OWNERSHIP OF RISK AND STANDARD OF CARE
Because geotechnical engineering is much less exact than other design disciplines, there is more risk
associated with geotechnical parameters than with most other design issues. Given the hidden and
variable character of natural soils and geologic hazards, this risk is impossible to eliminate with any
amount of study and exploration. Appropriate geotechnical exploration, analysis, and recommendations
can identify and lesson these risks. However, assuming an appropriate geotechnical evaluation, the
remaining risk of unknown soil conditions and other geo-hazards typically belongs to the owner of a
project unless specifically transferred to another party such as a contractor, insurance company, or
engineer. The geotechnical engineer’s duty is to provide professional services in accordance with their
stated scope and consistent with the standard of practice at the present time and in the subject geographic
area. It is not to provide insurance against geo-hazards or unanticipated soil conditions.
The conclusions and recommendations expressed in this report are opinions based our professional
judgment and the project parameters as relayed by the client. The conclusions and recommendations
assume that site conditions are not substantially different than those exposed by the explorations. If
during construction, subsurface conditions different from those encountered in the explorations are
observed or appear to be present, Allied Engineering should be advised at once such that we may review
those conditions and reconsider our recommendations where necessary.
RETENTION OF SOIL SAMPLES
Allied Engineering will typically retain soil samples for one month after issuing the geotechnical report.
If you would like to hold the samples for a longer period of time, you should make specific arrangements
to have the samples held longer or arrange to take charge of the samples yourself.
United States
Department of
Agriculture
A product of the National
Cooperative Soil Survey,
a joint effort of the United
States Department of
Agriculture and other
Federal agencies, State
agencies including the
Agricultural Experiment
Stations, and local
participants
Custom Soil Resource
Report for
Gallatin County
Area, MontanaNatural
Resources
Conservation
Service
January 17, 2023
Preface
Soil surveys contain information that affects land use planning in survey areas.
They highlight soil limitations that affect various land uses and provide information
about the properties of the soils in the survey areas. Soil surveys are designed for
many different users, including farmers, ranchers, foresters, agronomists, urban
planners, community officials, engineers, developers, builders, and home buyers.
Also, conservationists, teachers, students, and specialists in recreation, waste
disposal, and pollution control can use the surveys to help them understand,
protect, or enhance the environment.
Various land use regulations of Federal, State, and local governments may impose
special restrictions on land use or land treatment. Soil surveys identify soil
properties that are used in making various land use or land treatment decisions.
The information is intended to help the land users identify and reduce the effects of
soil limitations on various land uses. The landowner or user is responsible for
identifying and complying with existing laws and regulations.
Although soil survey information can be used for general farm, local, and wider area
planning, onsite investigation is needed to supplement this information in some
cases. Examples include soil quality assessments (http://www.nrcs.usda.gov/wps/
portal/nrcs/main/soils/health/) and certain conservation and engineering
applications. For more detailed information, contact your local USDA Service Center
(https://offices.sc.egov.usda.gov/locator/app?agency=nrcs) or your NRCS State Soil
Scientist (http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/contactus/?
cid=nrcs142p2_053951).
Great differences in soil properties can occur within short distances. Some soils are
seasonally wet or subject to flooding. Some are too unstable to be used as a
foundation for buildings or roads. Clayey or wet soils are poorly suited to use as
septic tank absorption fields. A high water table makes a soil poorly suited to
basements or underground installations.
The National Cooperative Soil Survey is a joint effort of the United States
Department of Agriculture and other Federal agencies, State agencies including the
Agricultural Experiment Stations, and local agencies. The Natural Resources
Conservation Service (NRCS) has leadership for the Federal part of the National
Cooperative Soil Survey.
Information about soils is updated periodically. Updated information is available
through the NRCS Web Soil Survey, the site for official soil survey information.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its
programs and activities on the basis of race, color, national origin, age, disability,
and where applicable, sex, marital status, familial status, parental status, religion,
sexual orientation, genetic information, political beliefs, reprisal, or because all or a
part of an individual's income is derived from any public assistance program. (Not
all prohibited bases apply to all programs.) Persons with disabilities who require
2
alternative means for communication of program information (Braille, large print,
audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice
and TDD). To file a complaint of discrimination, write to USDA, Director, Office of
Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or
call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity
provider and employer.
3
Contents
Preface....................................................................................................................2
How Soil Surveys Are Made..................................................................................5
Soil Map..................................................................................................................8
Soil Map (Jarrett Soil Map)...................................................................................9
Legend................................................................................................................10
Map Unit Legend (Jarrett Soil Map)....................................................................11
Map Unit Descriptions (Jarrett Soil Map)............................................................11
Gallatin County Area, Montana.......................................................................13
350B—Blackmore silt loam, 0 to 4 percent slopes......................................13
References............................................................................................................15
4
How Soil Surveys Are Made
Soil surveys are made to provide information about the soils and miscellaneous
areas in a specific area. They include a description of the soils and miscellaneous
areas and their location on the landscape and tables that show soil properties and
limitations affecting various uses. Soil scientists observed the steepness, length,
and shape of the slopes; the general pattern of drainage; the kinds of crops and
native plants; and the kinds of bedrock. They observed and described many soil
profiles. A soil profile is the sequence of natural layers, or horizons, in a soil. The
profile extends from the surface down into the unconsolidated material in which the
soil formed or from the surface down to bedrock. The unconsolidated material is
devoid of roots and other living organisms and has not been changed by other
biological activity.
Currently, soils are mapped according to the boundaries of major land resource
areas (MLRAs). MLRAs are geographically associated land resource units that
share common characteristics related to physiography, geology, climate, water
resources, soils, biological resources, and land uses (USDA, 2006). Soil survey
areas typically consist of parts of one or more MLRA.
The soils and miscellaneous areas in a survey area occur in an orderly pattern that
is related to the geology, landforms, relief, climate, and natural vegetation of the
area. Each kind of soil and miscellaneous area is associated with a particular kind
of landform or with a segment of the landform. By observing the soils and
miscellaneous areas in the survey area and relating their position to specific
segments of the landform, a soil scientist develops a concept, or model, of how they
were formed. Thus, during mapping, this model enables the soil scientist to predict
with a considerable degree of accuracy the kind of soil or miscellaneous area at a
specific location on the landscape.
Commonly, individual soils on the landscape merge into one another as their
characteristics gradually change. To construct an accurate soil map, however, soil
scientists must determine the boundaries between the soils. They can observe only
a limited number of soil profiles. Nevertheless, these observations, supplemented
by an understanding of the soil-vegetation-landscape relationship, are sufficient to
verify predictions of the kinds of soil in an area and to determine the boundaries.
Soil scientists recorded the characteristics of the soil profiles that they studied. They
noted soil color, texture, size and shape of soil aggregates, kind and amount of rock
fragments, distribution of plant roots, reaction, and other features that enable them
to identify soils. After describing the soils in the survey area and determining their
properties, the soil scientists assigned the soils to taxonomic classes (units).
Taxonomic classes are concepts. Each taxonomic class has a set of soil
characteristics with precisely defined limits. The classes are used as a basis for
comparison to classify soils systematically. Soil taxonomy, the system of taxonomic
classification used in the United States, is based mainly on the kind and character
of soil properties and the arrangement of horizons within the profile. After the soil
5
scientists classified and named the soils in the survey area, they compared the
individual soils with similar soils in the same taxonomic class in other areas so that
they could confirm data and assemble additional data based on experience and
research.
The objective of soil mapping is not to delineate pure map unit components; the
objective is to separate the landscape into landforms or landform segments that
have similar use and management requirements. Each map unit is defined by a
unique combination of soil components and/or miscellaneous areas in predictable
proportions. Some components may be highly contrasting to the other components
of the map unit. The presence of minor components in a map unit in no way
diminishes the usefulness or accuracy of the data. The delineation of such
landforms and landform segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, onsite
investigation is needed to define and locate the soils and miscellaneous areas.
Soil scientists make many field observations in the process of producing a soil map.
The frequency of observation is dependent upon several factors, including scale of
mapping, intensity of mapping, design of map units, complexity of the landscape,
and experience of the soil scientist. Observations are made to test and refine the
soil-landscape model and predictions and to verify the classification of the soils at
specific locations. Once the soil-landscape model is refined, a significantly smaller
number of measurements of individual soil properties are made and recorded.
These measurements may include field measurements, such as those for color,
depth to bedrock, and texture, and laboratory measurements, such as those for
content of sand, silt, clay, salt, and other components. Properties of each soil
typically vary from one point to another across the landscape.
Observations for map unit components are aggregated to develop ranges of
characteristics for the components. The aggregated values are presented. Direct
measurements do not exist for every property presented for every map unit
component. Values for some properties are estimated from combinations of other
properties.
While a soil survey is in progress, samples of some of the soils in the area generally
are collected for laboratory analyses and for engineering tests. Soil scientists
interpret the data from these analyses and tests as well as the field-observed
characteristics and the soil properties to determine the expected behavior of the
soils under different uses. Interpretations for all of the soils are field tested through
observation of the soils in different uses and under different levels of management.
Some interpretations are modified to fit local conditions, and some new
interpretations are developed to meet local needs. Data are assembled from other
sources, such as research information, production records, and field experience of
specialists. For example, data on crop yields under defined levels of management
are assembled from farm records and from field or plot experiments on the same
kinds of soil.
Predictions about soil behavior are based not only on soil properties but also on
such variables as climate and biological activity. Soil conditions are predictable over
long periods of time, but they are not predictable from year to year. For example,
soil scientists can predict with a fairly high degree of accuracy that a given soil will
have a high water table within certain depths in most years, but they cannot predict
that a high water table will always be at a specific level in the soil on a specific date.
After soil scientists located and identified the significant natural bodies of soil in the
survey area, they drew the boundaries of these bodies on aerial photographs and
Custom Soil Resource Report
6
identified each as a specific map unit. Aerial photographs show trees, buildings,
fields, roads, and rivers, all of which help in locating boundaries accurately.
Custom Soil Resource Report
7
Soil Map
The soil map section includes the soil map for the defined area of interest, a list of
soil map units on the map and extent of each map unit, and cartographic symbols
displayed on the map. Also presented are various metadata about data used to
produce the map, and a description of each soil map unit.
8
9
Custom Soil Resource Report
Soil Map (Jarrett Soil Map)505509050551405055190505524050552905055340505539050554405055490505509050551405055190505524050552905055340505539050554405055490495670 495720 495770 495820 495870 495920
495670 495720 495770 495820 495870 495920
45° 39' 10'' N 111° 3' 21'' W45° 39' 10'' N111° 3' 7'' W45° 38' 57'' N
111° 3' 21'' W45° 38' 57'' N
111° 3' 7'' WN
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 12N WGS84
0 50 100 200 300
Feet
0 25 50 100 150
Meters
Map Scale: 1:1,980 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Map Unit Polygons
Soil Map Unit Lines
Soil Map Unit Points
Special Point Features
Blowout
Borrow Pit
Clay Spot
Closed Depression
Gravel Pit
Gravelly Spot
Landfill
Lava Flow
Marsh or swamp
Mine or Quarry
Miscellaneous Water
Perennial Water
Rock Outcrop
Saline Spot
Sandy Spot
Severely Eroded Spot
Sinkhole
Slide or Slip
Sodic Spot
Spoil Area
Stony Spot
Very Stony Spot
Wet Spot
Other
Special Line Features
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 26, Aug 30, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 3, 2009—Sep 1,
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.
Custom Soil Resource Report
10
Map Unit Legend (Jarrett Soil Map)
Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI
350B Blackmore silt loam, 0 to 4
percent slopes
17.4 100.0%
Totals for Area of Interest 17.4 100.0%
Map Unit Descriptions (Jarrett Soil Map)
The map units delineated on the detailed soil maps in a soil survey represent the
soils or miscellaneous areas in the survey area. The map unit descriptions, along
with the maps, can be used to determine the composition and properties of a unit.
A map unit delineation on a soil map represents an area dominated by one or more
major kinds of soil or miscellaneous areas. A map unit is identified and named
according to the taxonomic classification of the dominant soils. Within a taxonomic
class there are precisely defined limits for the properties of the soils. On the
landscape, however, the soils are natural phenomena, and they have the
characteristic variability of all natural phenomena. Thus, the range of some
observed properties may extend beyond the limits defined for a taxonomic class.
Areas of soils of a single taxonomic class rarely, if ever, can be mapped without
including areas of other taxonomic classes. Consequently, every map unit is made
up of the soils or miscellaneous areas for which it is named and some minor
components that belong to taxonomic classes other than those of the major soils.
Most minor soils have properties similar to those of the dominant soil or soils in the
map unit, and thus they do not affect use and management. These are called
noncontrasting, or similar, components. They may or may not be mentioned in a
particular map unit description. Other minor components, however, have properties
and behavioral characteristics divergent enough to affect use or to require different
management. These are called contrasting, or dissimilar, components. They
generally are in small areas and could not be mapped separately because of the
scale used. Some small areas of strongly contrasting soils or miscellaneous areas
are identified by a special symbol on the maps. If included in the database for a
given area, the contrasting minor components are identified in the map unit
descriptions along with some characteristics of each. A few areas of minor
components may not have been observed, and consequently they are not
mentioned in the descriptions, especially where the pattern was so complex that it
was impractical to make enough observations to identify all the soils and
miscellaneous areas on the landscape.
The presence of minor components in a map unit in no way diminishes the
usefulness or accuracy of the data. The objective of mapping is not to delineate
pure taxonomic classes but rather to separate the landscape into landforms or
landform segments that have similar use and management requirements. The
delineation of such segments on the map provides sufficient information for the
development of resource plans. If intensive use of small areas is planned, however,
onsite investigation is needed to define and locate the soils and miscellaneous
areas.
Custom Soil Resource Report
11
An identifying symbol precedes the map unit name in the map unit descriptions.
Each description includes general facts about the unit and gives important soil
properties and qualities.
Soils that have profiles that are almost alike make up a soil series. Except for
differences in texture of the surface layer, all the soils of a series have major
horizons that are similar in composition, thickness, and arrangement.
Soils of one series can differ in texture of the surface layer, slope, stoniness,
salinity, degree of erosion, and other characteristics that affect their use. On the
basis of such differences, a soil series is divided into soil phases. Most of the areas
shown on the detailed soil maps are phases of soil series. The name of a soil phase
commonly indicates a feature that affects use or management. For example, Alpha
silt loam, 0 to 2 percent slopes, is a phase of the Alpha series.
Some map units are made up of two or more major soils or miscellaneous areas.
These map units are complexes, associations, or undifferentiated groups.
A complex consists of two or more soils or miscellaneous areas in such an intricate
pattern or in such small areas that they cannot be shown separately on the maps.
The pattern and proportion of the soils or miscellaneous areas are somewhat similar
in all areas. Alpha-Beta complex, 0 to 6 percent slopes, is an example.
An association is made up of two or more geographically associated soils or
miscellaneous areas that are shown as one unit on the maps. Because of present
or anticipated uses of the map units in the survey area, it was not considered
practical or necessary to map the soils or miscellaneous areas separately. The
pattern and relative proportion of the soils or miscellaneous areas are somewhat
similar. Alpha-Beta association, 0 to 2 percent slopes, is an example.
An undifferentiated group is made up of two or more soils or miscellaneous areas
that could be mapped individually but are mapped as one unit because similar
interpretations can be made for use and management. The pattern and proportion
of the soils or miscellaneous areas in a mapped area are not uniform. An area can
be made up of only one of the major soils or miscellaneous areas, or it can be made
up of all of them. Alpha and Beta soils, 0 to 2 percent slopes, is an example.
Some surveys include miscellaneous areas. Such areas have little or no soil
material and support little or no vegetation. Rock outcrop is an example.
Custom Soil Resource Report
12
Gallatin County Area, Montana
350B—Blackmore silt loam, 0 to 4 percent slopes
Map Unit Setting
National map unit symbol: 56q7
Elevation: 4,850 to 5,550 feet
Mean annual precipitation: 18 to 22 inches
Mean annual air temperature: 37 to 43 degrees F
Frost-free period: 80 to 95 days
Farmland classification: All areas are prime farmland
Map Unit Composition
Blackmore and similar soils:90 percent
Minor components:10 percent
Estimates are based on observations, descriptions, and transects of the mapunit.
Description of Blackmore
Setting
Landform:Stream terraces
Down-slope shape:Linear
Across-slope shape:Linear
Parent material:Calcareous loess
Typical profile
A - 0 to 10 inches: silt loam
Bt - 10 to 27 inches: silty clay loam
Bk1 - 27 to 42 inches: silt loam
Bk2 - 42 to 60 inches: silt loam
Properties and qualities
Slope:0 to 4 percent
Depth to restrictive feature:More than 80 inches
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 content:30 percent
Available water supply, 0 to 60 inches: High (about 11.4 inches)
Interpretive groups
Land capability classification (irrigated): 4e
Land capability classification (nonirrigated): 4e
Hydrologic Soil Group: C
Ecological site: R043BP818MT - Upland Grassland Group
Hydric soil rating: No
Minor Components
Bowery
Percent of map unit:5 percent
Landform:Stream terraces, alluvial fans
Down-slope shape:Linear
Custom Soil Resource Report
13
Across-slope shape:Linear
Ecological site:R044BB032MT - Loamy (Lo) LRU 01 Subset B
Hydric soil rating: No
Blackmore
Percent of map unit:3 percent
Landform:Stream terraces
Down-slope shape:Linear
Across-slope shape:Linear
Ecological site:R043BP820MT - Upland Shrubland Group
Hydric soil rating: No
Brodyk
Percent of map unit:2 percent
Landform:Stream terraces
Down-slope shape:Linear
Across-slope shape:Linear
Ecological site:R044BB030MT - Limy (Ly) LRU 01 Subset B
Hydric soil rating: No
Custom Soil Resource Report
14
References
American Association of State Highway and Transportation Officials (AASHTO).
2004. Standard specifications for transportation materials and methods of sampling
and testing. 24th edition.
American Society for Testing and Materials (ASTM). 2005. Standard classification of
soils for engineering purposes. ASTM Standard D2487-00.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of
wetlands and deep-water habitats of the United States. U.S. Fish and Wildlife
Service FWS/OBS-79/31.
Federal Register. July 13, 1994. Changes in hydric soils of the United States.
Federal Register. September 18, 2002. Hydric soils of the United States.
Hurt, G.W., and L.M. Vasilas, editors. Version 6.0, 2006. Field indicators of hydric
soils in the United States.
National Research Council. 1995. Wetlands: Characteristics and boundaries.
Soil Survey Division Staff. 1993. Soil survey manual. Soil Conservation Service.
U.S. Department of Agriculture Handbook 18. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/national/soils/?cid=nrcs142p2_054262
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. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053577
Soil Survey Staff. 2010. Keys to soil taxonomy. 11th edition. U.S. Department of
Agriculture, Natural Resources Conservation Service. http://
www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?cid=nrcs142p2_053580
Tiner, R.W., Jr. 1985. Wetlands of Delaware. U.S. Fish and Wildlife Service and
Delaware Department of Natural Resources and Environmental Control, Wetlands
Section.
United States Army Corps of Engineers, Environmental Laboratory. 1987. Corps of
Engineers wetlands delineation manual. Waterways Experiment Station Technical
Report Y-87-1.
United States Department of Agriculture, Natural Resources Conservation Service.
National forestry manual. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/
home/?cid=nrcs142p2_053374
United States Department of Agriculture, Natural Resources Conservation Service.
National range and pasture handbook. http://www.nrcs.usda.gov/wps/portal/nrcs/
detail/national/landuse/rangepasture/?cid=stelprdb1043084
15
United States Department of Agriculture, Natural Resources Conservation Service.
National soil survey handbook, title 430-VI. http://www.nrcs.usda.gov/wps/portal/
nrcs/detail/soils/scientists/?cid=nrcs142p2_054242
United States Department of Agriculture, Natural Resources Conservation Service.
2006. Land resource regions and major land resource areas of the United States,
the Caribbean, and the Pacific Basin. U.S. Department of Agriculture Handbook
296. http://www.nrcs.usda.gov/wps/portal/nrcs/detail/national/soils/?
cid=nrcs142p2_053624
United States Department of Agriculture, Soil Conservation Service. 1961. Land
capability classification. U.S. Department of Agriculture Handbook 210. http://
www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/nrcs142p2_052290.pdf
Custom Soil Resource Report
16