HomeMy WebLinkAboutCIVIL ENGINEERING DESIGN REPORT 10-06-20
JOB NO. B19-110
MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA
OCTOBER 2020
406.586.0277
tdhengineering.com
234 East Babcock Street
Suite 3
Bozeman, MT 59715
CLIENT ENGINEER
SMA Architects
109 E. Oak St. Suite 2E
Bozeman, MT 59715
TD&H Engineering
234 East Babcock Street, Suite 3
Bozeman, MT 59715
Engineer: Cody Croskey, PE
GIBSON GUITAR DESIGN BUILD
BOZEMAN, MONTANA
BASIS OF DESIGN REPORT
Image from SMA Architects
B19-110 GIBSON GUITAR Page 1 of 4
GIBSON GUITAR DESIGN BUILD
DESIGN REPORT
October 2020
Purpose and Introduction
The purpose of this report is to explain how water, sanitary sewer, storm drainage, and
street improvements will be designed to meet the City of Bozeman requirements and
Montana Public Works Standard Specifications (MPWSS) to provide service to the
expanded Gibson Guitar manufacturing facility located on Orville Way. The report will
provide information on the detailed design of the above-mentioned infrastructure.
The project is located at the intersection of Orville Way and Simmental Way and is
encompassed within Lots 1, 2, & 3 of Tract 4 of the Gardiner-Simmental Plaza
Subdivision. The proposed new Gibson Guitar expansion includes construction of
approximately 25,000 square feet of new building space to improve and expand the
manufacturing operation. To accommodate the new building and operational needs,
new asphalt parking lots, truck loading areas, access drives, sidewalks, and landscaping
are proposed. While the building expansion is proposed on the same lot as the existing
building, the main employee parking lot, truck loading area, and storm drainage
improvements are proposed within multiple lots.
Design Report
Fire Protection
Fire protection will be provided by the City of Bozeman Fire Department. The existing
building has a four-inch fire service line connected to the building and is sprinklered. It is
our understanding this existing fire service will be maintained, and the existing sprinkler
system will be expanded throughout the new building addition. An existing City of
Bozeman fire hydrant is located at the intersection of Orville Way and Simmental Way.
This hydrant is directly adjacent to the Gibson Guitar property and is located to the
southeast of the building. Emergency response access will be through the new east
driveway and parking lot to the existing FDC, and through the west end of Orville Way
which will provide access around the west and north sides of the building and
incorporate a standard hammerhead turnaround with public access easement.
Water & Sewer Services
Water and sewer utilities for the existing building are connected to the City of Bozeman
water and sewer system, and plumbing will be extended internally throughout the new
building addition to serve new bathrooms and fixtures without adding additional external
services. There is currently an active 1” water service and meter servicing the existing
building. However, projected water demands with the proposed addition require the
existing 1” service be abandoned and upsized to a new 1-1/2” water service and meter.
Construction or extensions of new water and sewer mains are not anticipated with this
project.
B19-110 GIBSON GUITAR Page 2 of 4
Water Demand
Because this is an expansion project with continued similar use, the estimated water
demand is based on existing water utility records and projected metrics for the enlarged
facility and increased operations. Water meter records from Jan 2015 – July 2020 show
an average use of 3,067 gal/day at the existing facility. The current peak employment at
the facility is 160 employees, which is anticipated to increase to a maximum 286
employees in the years following the expansion. Assuming all current demand is
attributable to employee domestic use only, the proportional water demand to employee
increase is estimated as follows:
Table 1.
Estimated Annual Domestic Water Demands per Employee
Employees Average Use Daily Use/
Employee
Current Metered Use = 160 3,067 gpd 3.44 ac-ft/yr 19.2 gpd
Projected Use = 286 5,482 gpd 6.14 ac-ft/yr 19.2 gpd
Increased Demand = +126 +2,415 gpd +2.70 ac-ft/yr
Additionally, irrigation supply is expected to be connected to the City water supply with
this project as original water rights for the two existing irrigation wells at the property
were unable to be located through coordination with DNRC. These wells are also not
currently eligible to be permitted for irrigation use without mitigation due the project
location with the Bozeman Solvent Site Controlled Ground Water Area (BSS-CGWA).
Therefore, it is assumed these wells will need to be disconnected until such time as the
BSS-CGWA is absolved or existing water rights for these wells are discovered. Based
on the current project irrigation design and assuming a typical 24-week irrigation season
from mid-May through mid-October, the estimated annual irrigation water demand is as
follows:
Estimated Annual Irrigation Demands:
Irrigated turf area: 30,252 s.f. = 0.69 acres
Turf watering rate (May-Oct): 24 in/yr
Annual turf irrigation volume: 1.38 ac-ft/yr ¶
Individual plant watering rate (24-weeks May-Oct): 1,699 gal/wk
Annual plant irrigation volume: 0.13 ac-ft/yr
Projected Total Irrigation Water Use: 1.5 ac-ft/yr
A payment for cash-in-lieu of water rights (CILWR) is anticipated to be required to offset
the estimated municipal water demand increase for domestic and irrigation use with this
project.
B19-110 GIBSON GUITAR Page 3 of 4
Storm Drainage
The existing project site is partially developed with existing buildings, parking lots, and a
large gravel parking/storage area. The local streets adjacent to the project currently have
roadside ditches and no curb. The proposed site development includes adding additional
impervious areas such as an expanded building footprint and new paved parking and
circulation areas. Reconstruction of existing paved areas and conveyance of new roof
drainage across existing roofs make it difficult to separate pre- vs. post-project runoff
patterns. The site also has minimal stormwater controls in place currently. Therefore, the
project design seeks to capture and infiltrate design storm runoff from all new
improvement areas as well as runoff from most existing improved areas at the site.
The site generally slopes to the northwest but is relatively flat. Existing drainage patterns
will generally be maintained with stormwater collection/retention ponds located to the
north and west of the project areas and overflowing toward the roadside drainage ditch
along N. 19th Avenue. Localized storm drain inlets and pipes are necessary to
accommodate drainage at isolated low points, such as at the base of the loading dock or
the sag curve in Orville Way once curb is added. Roof drain pipes are prosed to collect
and convey roof runoff around the south face of the building where there is limited space
next to the road right-of-way to address storm water. A public drainage easement is
proposed for storm drainage that will be concentrated/conveyed across the multiple lot
boundaries to reach the NW retention pond where there is more space available. Runoff
volume, retention pond sizing, and pipe flow calculations are provided in the attached
appendix.
Groundwater was observed at the site during the geotechnical investigation at depths
ranging from 4.5 to 10.8 feet below the ground surface. Seasonal groundwater
fluctuations from 2008-2019 for the area were obtained for the nearby MBMG
GWAAMON Network monitoring well ID:241692 located at the MDOT rest area 0.40
miles north of the site. Based on this data, groundwater levels are expected to fluctuate
up and down 3.6 feet seasonally on average. An actual groundwater measurement was
taken at the Gibson site on August 4, 2020, which corresponds to the time of year when
groundwater has receded approximately 64% (or 2.3 feet) below its seasonal high on
average. This information combined with the general valley contours in the area were
used to estimate the seasonal high groundwater elevation beneath the proposed
stormwater infiltration ponds. The pond bottoms are currently designed to be 2.4 to 2.8
feet above the estimated seasonal high groundwater elevation at each location. The
GWAAMON monitoring well hydrograph and associated calculations are attached.
Roadway Improvements
This project is adjacent to Orville Way and Simmental Way which were originally
constructed to County roadway standards with shoulders and roadside ditches. A
requirement of the project is to bring the sides of the roadways fronting the property into
conformance with the City of Bozeman local street standards (i.e., curb & gutter,
boulevards, sidewalks, street lighting, and defined roadway width). Typical roadway
sections for Orville Way and Simmental Way showing the widening and standard
improvements along the property are provided in the design drawings (See Sheet C5.1).
A new street light is also proposed at the corner of Orville Way and Simmental Way. The
pavement section design is per the attached Geotechnical Investigation Report prepared
by TD&H Engineering for the project. All roadway work is to be per the Montana Public
B19-110 GIBSON GUITAR Page 4 of 4
Works Standard Specifications (MPWSS), and the latest City of Bozeman Modifications
to the MPWSS and Standards and Specifications Policy.
Simmental Way has the standard 60-foot right-of-way for a local street and the proposed
curb on the Gibson side is located to create the standard 35-foot roadway with respect to
the partially existing curb on the west side of the street. Orville Way only has a 50-foot
right-of-way width, so an alternate 31-foot roadway width is proposed as identified in
Table IV-2 (and note 3) of the City’s design standards and specifications policy. This
narrower width is expected to be adequate for this location as it is not a through street, it
has a posted 10 MPH speed limit, and additional off-street parking is proposed with this
project beyond the minimum required so as not to necessitate a parking lane on the
street in front of the facility.
APPENDIX A
Storm Water Design Calculations
M
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C
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C
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PARKING
BASIN 4:C = 0.90I = 0.41A = 1.24V = 3,287 CF
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BASIN 2:C = 0.85I = 0.41A = 1.43V = 3,590 CF
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GIBSON GUITAR DESIGN BUILD
BOZEMAN, MT
DRIANAGE BASINS & STORM POND SIZING B
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Engineering
234 E. BABCOCK ST., SUITE 3 • BOZEMAN, MONTANA 59715
406.586.0277 • tdhengineering.com
J:\2019\B19-110 Gibson Guitar Expansion\CADD\CIVIL\DWG\B19-110 BM.dwg, 10/6/2020 7:56:49 PM, DWG To PDF.pc3
TD&H Storm Drain Calculations
Project: Gibson Guitar
Retention Pond Volume Sizing
Rational Formula "C" Values Per MTDEQ 8 "C"
Hardscape Area 0.9
Gravel Area 0.8
Unimproved Area 0.3
Lawn/landscape 0.1
Post-Development Drainage Basins:
Basin #Basin Description Total Area
(SF)
Total Area
(Acres)
Composite
Cave
10 yr - 2hr
i
(in/hr)
Flow
Q10
(cfs)
Runoff
Volume
(cf)
1 North Roof Area and Utility Yard 49,222 1.13 0.88 0.41 0.41 2,935
2 West Truck Loading Existing Gravel Yard 62,324 1.43 0.85 0.41 0.50 3,590
3 Front Entry Roof and East Parking Lot 11,254 0.26 0.90 0.41 0.10 686
4 SW Parking Lot 53,898 1.24 0.90 0.41 0.46 3,287
5 Orville Way 12,953 0.30 0.88 0.41 0.11 772
Total Site Retention Volume =11,272
Retention Pond Sizing:
Retention
Pond Contributing Basins
Design
Volume
(cf)
NW Basins 1, 2, & 5 7,300
East Basin 3 700
SW Basin 4 3,300
Total Design Retention Volume =11,300
TD&H Stormwater CalculationsProject: Gibson Guitar25-yr Pipe Flow Calculations25-Year Flow Calcs:Pipe Capacity Calcs (94% full):Location Basin Size (Acres)Cave CCf Tc (min)25 yri(in/hr)FlowQ25(cfs)Pipe Dia. (d)(ft)Pipe Slope(%)Manning'sn 94% Flow Depth (y)(ft)Theta (Θ)(rad.)Area (A)(ft2)Hydraulic Radius (R)(ft)Qfull(cfs)Vfull(ft/sec)V25(ft/sec)South Bldg Roof Drain 0.29 0.9 0.99 5 3.83 1.10 0.83 0.50%0.013 0.78 5.29 0.53 0.24 1.67 3.14 3.09Orville Inlet + Roof Drain 0.58 0.88 0.97 5 3.83 2.15 1.25 0.50%0.013 1.18 5.29 1.20 0.36 4.93 4.12 3.67Truck Dock Inlets 0.08 0.9 0.99 5 3.83 0.30 1.00 1.00%0.013 0.94 5.29 0.77 0.29 3.84 5.02 2.80Pipe to NW Pond 3.55 1.25 1.00%0.013 1.18 5.29 1.20 0.36 6.97 5.82 5.41Main Entry Bldg Roof Drain 0.08 0.9 0.99 5 3.83 0.30 0.50 1.00%0.013 0.47 5.29 0.19 0.14 0.61 3.16 2.94Pipe to East Pond 0.26 0.9 0.99 5 3.83 0.98 1.00 1.00%0.013 0.94 5.29 0.77 0.29 3.84 5.02 3.89Manning's Eqn:Q = 1.49/n*A*R2/3*S00.5
Rational Method
Cf = 1.1 for 25-yr event
IDF curve equation for 25-yr stormTc = time to concentration in hoursCombined Flows (Above) =
AiCCQf=
64.25 78.0 −=cTi
Groundwater Information Center Well Hydrograph
The following chart represents the current hydrograph for this well. Data reported are static water levels in feet below ground surface. A filter has been applied to the
data to remove all dry and/or non-static measurements.
GWIC Id: 241692
Site Name: GLWQD - MDOT VISITOR CENTER
Location: 01S05E35AADB
Total Depth: 8.9 feet
Number of Measurements: 62691
Period of Record: 5/27/1993 - 7/4/2020 9:40:00 AM
Disclaimer
The preceding materials represent the contents of the GWIC databases at the Montana Bureau of Mines and Geology at the time and date [8/26/2020 2:14:27 PM] of the
retrieval. The information is considered unpublished and is subject to correction and review on a daily basis. The Bureau warrants the accurate transmission of the data
to the original end user at the time and date of the retrieval. Retransmission of the data to other users is discouraged and the Bureau claims no responsibility if the
material is retransmitted. There may be wells in the request area that are not recorded at the Information Center. Water level data downloaded from GWIC are not
filtered and will contain all measurements.
Date
Static Water Level
8
6
4
2
Jan 2008 Jan 2009 Jan 2010 Jan 2011 Jan 2012 Jan 2013 Jan 2014 Jan 2015 Jan 2016 Jan 2017
Page 1 of 1Montana's Groundwater Information Center (GWIC) | SWL Hydrograph
8/26/2020https://mbmggwic.mtech.edu/sqlserver/v11/reports/WellHydrograph.asp?gwicid=241692&
GWIC ID:241692
SITE NAME:GLWQD - MDOT VISITOR CENTER
TOTAL DEPTH:8.9 FEET
YEAR
2008
2008
2008
2009
2009
2009
2010
2010
2010
2011
2011
2011
2012
2012
2012
2013
2013
2013
2014
2014
2014
2015
2015
2015
2016
2016
2016
2017
2017
2017
2018
2018
2018
2019
2019
2019
=3.2 Feet below ground level
=6.8 Feet below ground level
AVERAGE EARLY AUGUST =5.5 Feet below ground level
GIBSON GUTIAR EXPANSION: B19-110
GWIC WELL MONITOR LEVELS
DATE HIGH LOW NEAR AUGUST
4-Aug
2-Jan 6.78
17-Jan 6.65
2-Jun 2.37
2-Feb 6.39
30-Jun 2.9
1-May 2.3
4-Aug
2-May 2.25
11-Aug
2-Aug
4-Oct 6.69
4.65
5.76
4.48
4.98
2-Jan 7.05
15-Jun 4.1
2-Aug 6.59
2-Oct 7.44
29-May 4.78
8-Aug 4.19
3-Aug 5.88
3-Feb 6.72
26-May 4.7
STATIC WATER DEPTH (BELOW GROUND) FEET
3-Aug 5.76
28-Aug 7.02
17-Oct 6.45
3-Jun 5.2
29-Mar 3.86
28-Apr 3.16
3-Aug 5.74
1-Aug 6.33
20-Jan 7.35
6-Aug 5.61
10-Mar 6.7
7-Oct 6.57
7-May 2.36
AVERAGE LOW
AVERAGE HIGH
21-Apr 0.57
3-Aug 5.5
GWIC ID:241692
SITE NAME:GLWQD - MDOT VISITOR CENTER
TOTAL DEPTH:8.9 FEET
GIBSON GUTIAR EXPANSION: B19-110
GWIC WELL MONITOR LEVELS
Monitoring Well Location
Project Site
APPENDIX B
Storm Water Maintenance Plan
JOB NO. B19-110
MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA
AUGUST 2020
406.586.0277
tdhengineering.com
234 East Babcock Street
Suite 3
Bozeman, MT 59715
CLIENT ENGINEER
SMA Architects
109 E. Oak St. Suite 2E
Bozeman, MT 59715
TD&H Engineering
234 East Babcock Street, Suite 3
Bozeman, MT 59715
ON-SITE STORM WATER MAINTENANCE PLAN
GIBSON GUITAR DESIGN BUILD
BOZEMAN, MONTANA
Gibson Guitar Design Build Storm Water Maintenance Plan
B19-110 1
GIBSON GUITAR DESIGN BUILD
STORM WATER MAINTENANCE PLAN
PURPOSE AND INTRODUCTION
This maintenance plan identifies the recommended maintenance procedures necessary for the
proper function of the on-site storm water management system proposed at the Gibson Guitar
facility expansion in Bozeman, Montana.
The maintenance responsibility for the on-site stormwater ponds and storm drain collection
system belongs to the landowner. The landowner may delegate routine inspection and
maintenance responsibilities to the on-site facility operations management team, or may hire a
qualified professional entity or individual to perform certain monitoring and maintenance tasks
as necessary. A log shall be kept for all required inspections and maintenance. These logs shall
be made available to the City of Bozeman Public Works Department for review as requested. A
sample maintenance log is included in the attached Appendix.
STORM WATER MANAGEMENT SYSTEM
The on-site storm water management system includes curb and gutter, curb inlets, area inlets,
drainage chases, downspout collectors, roof drain piping, storm water retention ponds, drainage
ditches, and dry wells. These various components of storm water management infrastructure
are designed to collect, convey, clean, detain, and/or infiltrate storm water runoff that is
generated on the property before it leaves the site or enters local waterways.
Storm water systems require proper maintenance to prevent sediment clogging, overgrown
vegetation, erosion of detention ponds, obstruction of inlets, pipes, and structures, and
prolonged standing water. Such issues may result in downstream pollution, unpleasant odors,
unsightly areas, nuisance insects, or algae blooms, and must be mitigated. Scheduled
inspections, times of inspections, locations inspected, maintenance completed, corrective
actions taken, and any modifications or reconstruction performed shall be documented in the
maintenance logs to be readily available upon request. Disposal of accumulated sediment must
be in accordance with all applicable local, state and federal regulations.
Wetlands may be present within the boundaries of retention ponds, drainage ditches and
surrounding areas, and should be considered when planning maintenance activities. Wetland
permitting is generally not required for maintenance of constructed storm water management
features. However, maintenance of locations where pond outlet pipes or pond overflows
discharge to protected water bodies within wetland areas may require wetland or stream bank
permitting. If unsure of the regulatory status of wetland features observed at the site, consult the
local authorities prior to undertaking any activities that may cause disturbance.
Gibson Guitar Design Build Storm Water Maintenance Plan
B19-110 2
STORM WATER MAINTENANCE PROCEDURES
The following maintenance procedures are intended to prolong the life of installed system
components and ensure their continued functionality:
General Storm Water System Maintenance –
1. Parking lot areas and curbs & gutters should be cleared of leaves and other debris once
after primary leaf drop in the fall and once after snow melt in early spring at a minimum.
This will minimize the potential for debris to enter the system which could lead to
premature clogging of structures, reduced storage capacity, and/or blockage of inlets.
2. Inspect the storm drain inlets, manholes, downspout connections, and cleanouts, for
sediment build-up or clogging and flush/clear as needed. Inspect for snow/ice buildup at
least once weekly during winter months and clear the inlet as needed. Do not pile snow
over inlets.
3. Snow storage should be performed in designated areas during winter months and
should not be allowed to be piled in front of or over inlets. Piled snow around or over the
inlets could block early snowmelt run-off from entering the system, possibly causing
overflows and icy conditions.
4. Sanding of the parking lots and truck loading areas should be done sparingly or avoided
completely. Sand or other sediment on the parking lot will likely be washed into
stormwater system components which can lead to buildup and reduced capacity or
blockages over time.
Storm Water Pond Maintenance –
1. Routine Maintenance Activities (every 3 months):
a. Mow vegetation around each stormwater pond regularly throughout the
spring/summer months.
b. Designate a “no-mow” zone at the bottom of the ponds. This area will be trimmed
once a year and protected from regularly scheduled grass mowing. Excessive
mowing causes debris buildup and compaction of the soils in the bottom of the
pond, reducing the pond’s infiltration ability.
c. Remove trash, leaves, plant trimmings, grass clippings, pet waste and other
debris from the pond area.
d. Inspect pond inlets, outlets, and internal dry well grates for any obstructions that
would prevent stormwater from entering or leaving the pond and remove
obstructions as needed.
2. Annual Maintenance Activities (annually):
a. At the end of each fall, cut plants in the “no-mow” zone to a height of six inches
and rake and remove all clippings and leaves.
Gibson Guitar Design Build Storm Water Maintenance Plan
B19-110 3
b. Re-establish vegetation on eroded or barren areas of the pond.
3. Long-Term Maintenance Activities (as observed/required):
a. Survey the pond elevations to determine the amount of sediment buildup, if any,
in the pond.
b. Excavate sediment and re-establish the pond to its initial design volume per the
construction plans if sediment build-up is found to be greater than six inches or if
the pond volume has decreased by more than ten percent.
c. Flush sediment from outlet structures/piping and from the outfall location if build-
up is observed. Remove sediment build-up from outlet structure or dry well
sumps if needed.
APPENDIX
City of Bozeman Stormwater Basin Maintenance Guide
Sample Maintenance & Inspection Log
FIGURE 5
Storm Water Facilities Inspection and Maintenance Log
Facility Name
Begin Date End Date
Date Location Facility Description Inspected
by:
Cause for
Inspection
Exceptions Noted Comments and
Actions Taken
Instructions: Record all inspections and maintenance for all storm water facilities on this form. Use additional log sheets and/or
attach extended comments or documentation as necessary. Save all completed logs in one place and have them readily available for
the City of Bozeman’s review upon request.
Location — Specify the exact location of the facility either by its name, facility ID or physical location.
Inspected by — Note all inspections and maintenance on this form, including the required independent annual inspection.
Cause for inspection — Note if the inspection is routine, pre-rainy-season, post-storm, annual, or in response to a noted
problem or complaint.
Exceptions noted — Note any condition that requires correction or indicates a need for maintenance.
Comments and actions taken — Describe any maintenance performed and need for follow-up.
FIGURE 1FIGURE 1
FIGURE 6
Appendix C
Project Geotechnical Report
MONTANA | WASHINGTON | IDAHO | NORTH DAKOTA | PENNSYLVANIA
JOB NO. B19-110-001 FEBRUARY 2020
REPORT OF GEOTECHNICAL INVESTIGATION
CLIENT ENGINEER
Langlas & Associates
1019 E. Main Street, Suite 101
Bozeman, MT 59715
Craig Nadeau, PE
Craig.nadeau@tdhengineering.com
REPORT OF GEOTECHNICAL INVESTIGATION
PROJECT NAME
PROJECT LOCATION 406.586.027 7
tdhengineering.com
234 E. Babcock, Suite 3
Bozeman, MT 59715
GIBSON GUITAR EXPANSION
BOZEMAN, MONTANA
Gibson Guitar Expansion Table of Contents Bozeman, Montana i
Table of Contents
1.0 EXECUTIVE SUMMARY ......................................................................................................... 1
2.0 INTRODUCTION ..................................................................................................................... 2
2.1 Purpose and Scope .......................................................................................................... 2
2.2 Project Description ........................................................................................................... 2
3.0 SITE CONDITIONS ................................................................................................................. 3
3.1 Geology and Physiography .............................................................................................. 3
3.2 Surface Conditions ........................................................................................................... 3
3.3 Subsurface Conditions ..................................................................................................... 4
3.3.1 Soils ........................................................................................................................... 4
3.3.2 Ground Water ........................................................................................................... 5
4.0 ENGINEERING ANALYSIS .................................................................................................... 6
4.1 Introduction ....................................................................................................................... 6
4.2 Site Grading and Excavations.......................................................................................... 6
4.3 Conventional Shallow Foundations ................................................................................. 6
4.4 Foundation and Retaining Walls ...................................................................................... 7
4.5 Floor Slabs and Exterior Flatwork .................................................................................... 7
4.6 Pavements ....................................................................................................................... 8
5.0 RECOMMENDATIONS ......................................................................................................... 10
5.1 Site Grading and Excavations........................................................................................ 10
5.2 Conventional Shallow Foundations ............................................................................... 11
5.3 Floor Slabs and Exterior Flatwork .................................................................................. 13
5.4 Pavements ..................................................................................................................... 14
5.5 Continuing Services ....................................................................................................... 15
6.0 SUMMARY OF FIELD AND LABORATORY STUDIES ....................................................... 17
6.1 Field Explorations ........................................................................................................... 17
6.2 Laboratory Testing ......................................................................................................... 17
7.0 LIMITATIONS ........................................................................................................................ 19
Gibson Guitar Expansion Appendix Bozeman, Montana ii
APPENDIX
Test Pit Location Map (Figure 1)
Logs of Exploratory Test Pits (Figures 2 through 8)
Laboratory Test Data (Figures 9 through 16)
USGS Design Maps Summary Report
LTTPBind Online PG Asphalt Binder Analysis Summary
Soil Classification and Sampling Terminology for Engineering Purposes
Classification of Soils for Engineering Purposes
Gibson Guitar Expansion Executive Summary Bozeman, Montana Page 1
GEOTECHNICAL REPORT GIBSON GUITAR EXPANSION
BOZEMAN, MONTANA
1.0 EXECUTIVE SUMMARY
The geotechnical investigation for the proposed expansion of the Gibson Acoustic facility located at
1894 Orville Way in Bozeman, Montana, encountered varying thickness of surficial clay overlying
water bearing native poorly-graded gravel with sand. The seismic site class is D, and the risk of
seismically-induced liquefaction or soil settlement is considered low and does not warrant additional
evaluation. The primary geotechnical concern regarding this project is the presence of relatively
soft surficial clays of varying thickness which pose a risk of differential settlement to the planned
expansion. Based on the site conditions encountered, we do not recommend foundations
supported on the native clay soils. Conventional shallow foundations are suitable for this site but
should be placed on properly compacted structural fill extending down to the native gravel stratum.
Based on the site conditions, structural fill thicknesses of up to six feet are anticipated below
conventional frost depth footings. Ground water was also encountered near the top of the native
gravel in all test pits performed. A confined ground water condition may exist on this property; thus,
dewatering of all construction excavations should be anticipated following the removal of the native
clay to facilitate the placement and compaction of the structural fill.
The native clay soils are relatively soft and exhibit elevated moisture contents which are likely
above typical optimum values for compaction of the clay. Thus, any reuse of the native clay for
backfill or site grading applications should anticipate the need for moisture conditioning of the
material prior to reuse. Furthermore, elevated moisture can significantly weaken these clay soils
impeding access to construction equipment and subgrade strengths for pavement systems. Thus,
increased gravel thicknesses and the incorporation of separation geotextiles beneath parking lots
and access roads should be expected.
Gibson Guitar Expansion Introduction Bozeman, Montana Page 2
2.0 INTRODUCTION
2.1 Purpose and Scope
This report presents the results of our geotechnical study for the proposed expansion to the Gibson
Acoustic facility located at 1894 Orville Way in Bozeman, Montana. The purpose of the geotechnical
study is to determine the general surface and subsurface conditions at the proposed site and to
develop geotechnical engineering recommendations for support of the proposed structure and
design of related facilities. This report describes the field work and laboratory analyses conducted
for this project, the surface and subsurface conditions encountered, and presents our
recommendations for the proposed foundations and related site development.
Our field work included excavating seven test pits across the proposed site. Samples were obtained
from the test pits and returned to our Great Falls laboratory for testing. Laboratory testing was
performed on selected soil samples to determine engineering properties of the subsurface
materials. The information obtained during our field investigations and laboratory analyses was
used to develop recommendations for the design of the proposed foundation systems.
2.2 Project Description
It is our understanding that the proposed project consists of a 21,500 square foot addition to the
existing structure. The addition is planned to utilize either precast concrete or steel frame
construction with conventional shallow foundation systems with interior slab-on-grade construction
matching the finished floor elevation of the current building. Structural loads had not been provided
at the time of this report. However, for the purpose of our analysis, we have assumed that wall
loads will be less than 4,000 pounds per lineal foot and column loads, if any, will be less than 100
kips.
Site development will most likely include landscaping, exterior concrete flatwork, and asphalt
pavement for parking lots and access roads. If the assumed design values presented above vary
from the actual project parameters, the recommendations presented in this report should be
reevaluated.
Gibson Guitar Expansion Site Conditions Bozeman, Montana Page 3
3.0 SITE CONDITIONS
3.1 Geology and Physiography
The site is geologically characterized as upper tertiary sediment or sedimentary rock (Tsu). This
formation is comprised of conglomerate, tuffaceous sandstone and siltstone, marlstone, and
equivalent sediment and ash beds. These materials are generally overlain by varying thicknesses
gravel (Qgr). These gravels are comprised of variable deposits ranging in size from pebble to
boulder sized rock including sand, silt, and clay.
Geologic Map of Montana, Edition 1.0
Montana Bureau of Mines & Geology
Based on the subsurface conditions encountered, the site falls under seismic Site Class D. The
appropriate 2015 International Building Code (IBC) seismic design parameters for the site include
site coefficients of 1.224 and 1.98 for Fa and Fv, respectively. The recommended design spectral
response accelerations at short periods (SDs) and at 1-second period (SD1) are 0.588g and 0.277g,
respectively. These values represent two-thirds of the mapped response accelerations following
correction for the appropriate site classification and assume the proposed construction to fall into
risk category II. The likelihood of seismically-induced soil liquefaction or settlement for this project
is low and does not warrant additional evaluation.
3.2 Surface Conditions
The proposed project site is located at 1894 Orville Way in Bozeman, Montana. The site is at the
location of the current Gibson Acoustics facility which consists of an existing structure estimated to
be approximately 21,000 square feet in plan and a large asphalt parking lot. Two smaller support
structures and a gravel surfaced yard are located to the west of the parking lot. Based on
PROJECT LOCATION
Gibson Guitar Expansion Site Conditions Bozeman, Montana Page 4
background information and site observations, the site is considered relatively flat with limited grade
change across the property.
3.3 Subsurface Conditions
3.3.1 Soils
The subsurface soil conditions appear to be relatively consistent with respect to the
depositional layering of the site; however, the thickness of the stratum varies some across
the property. All seven test pits encountered surficial topsoil underlain by native lean clay
and native poorly-graded gravel with sand. The lean clay varied from 3.6 to 10.4 feet in
thickness and generally increased in thickness towards the east side of the property. The
lean clay is underlain in all test pits by native gravels which extend to depths of at least 10.8
feet, the maximum depth investigated for this project.
The subsurface soils are described in detail on the enclosed test pit logs and are
summarized below. The stratification lines shown on the logs represent approximate
boundaries between soil types and the actual in situ transition may be gradual vertically or
discontinuous laterally.
TOPSOIL
Topsoil consisting of organic rich lean clay were encountered in all seven borings and
ranged in thickness from 0.5 to 1.8 feet. The topsoil is considered firm based on the ease of
excavation and may have had some frost within this zone at the time of our investigation.
LEAN CLAY
Native lean clay was encountered directly below the upper topsoil horizon in all test pits and
extends to depths of 3.6 to 10.4 feet. The lean clay is considered firm to soft with increasing
moisture at depth based on the ease of excavation and observations of our field engineer.
Pocket penetrometer tests performed within several test pits at varying depths indicated an
unconfined compressive strength of less than 0.5 tons per square foot, which is supportive
of a soft soil consistency. Samples of the material contained between 0 and 6 percent
gravel, between 9 and 10 percent sand, and between 85 and 91 percent fines (clay and silt).
The lean clay samples also exhibited liquid limits of 34 to 38 percent and plasticity indices of
14 to 19 percent. The natural moisture contents varied from 21 to 32 percent and averaged
27 percent.
A bulk sample of the lean clay material was tested and exhibited a maximum dry density of
107.0 pounds per cubic foot (pcf) when compacted at its optimum moisture content of 18.2
percent. This test was performed using the standard proctor method outlined in ASTM
D698. A California Bearing Ratio (CBR) test was then performed on the same sample to
evaluate its strength when utilized as a subgrade beneath a pavement system. This test
Gibson Guitar Expansion Site Conditions Bozeman, Montana Page 5
which was performed in accordance with ASTM D1883 resulted in a CBR value of 2.0
percent when compacted to at least 95 percent of the maximum dry density outlined above.
POORLY-GRADED GRAVEL WITH SAND
Native gravels, visually classified as poorly-graded gravel with sand, were encountered
below the native clay in all seven borings at depths of 3.6 to 10.4 feet and extend to depths
of at least 10.8 feet, the maximum depth investigated. The gravel is considered relatively
dense based on observations of our field engineer during excavation. A single natural
moisture content of 7.0 percent was measured for this stratum.
3.3.2 Ground Water
Ground water was encountered within all seven test pits performed for this project at depths
ranging from 4.5 to 10.8 feet below the ground surface. At all seven test pit locations, the
ground water was encountered in close proximity to the transitions between the lean clay
and native gravel strata. This indicates that a confined ground water condition may exist
seasonally in which the native clay resists rises in the ground water table and creates a
temporary pressurized ground water table. We anticipate seasonal fluctuations in the
ground water table to occur and expect dewatering to be required during construction to
facilitate the removal of the native clay and replacement with properly compacted structural
fill. However, numerous factors contribute to seasonal ground water fluctuations, and the
evaluation of the magnitude or presence of seasonal ground water fluctuations is beyond
our scope of work for this project.
Gibson Guitar Expansion Engineering Analysis Bozeman, Montana Page 6
4.0 ENGINEERING ANALYSIS
4.1 Introduction
The primary geotechnical concern regarding this project is the presence of soft, compressible clay
soils at and below the anticipated bearing elevation for foundations associated with the addition.
The clay thickness is also highly variable across the property which increases the risk of differential
behavior and is the primary source of building distress related to foundation movement. The soft
clay is also expected to be encountered at moisture contents which are well beyond the compaction
range for the material. This will impact the strength of the clay in pavement applications and any
planned reuse of this material should anticipate the need for moisture conditioning prior to
compaction.
4.2 Site Grading and Excavations
The ground surface at the proposed site is considered relatively flat; thus, significant cut or fill
thickness for site development are not anticipated for this project. Based on our field work, topsoil,
lean clay, and native water-bearing gravels will be encountered in foundation and utility excavations
to the depths anticipated. Based on the test pits, ground water should be expected in all foundation
and utility excavations extending below a depth of four feet and dewatering systems should be
provided by the contractor to temporarily lower the water table and facilitate the proper placement
and compaction of structural fill below foundation elements.
4.3 Conventional Shallow Foundations
Considering the subsurface conditions encountered and the nature of the proposed construction,
the addition can be supported on conventional shallow foundations bearing on properly compacted
structural fill extending down to native gravels. Based on the test pits performed, structural fill
thickness are anticipated to range from 0 to 6 feet beneath conventional frost depth foundation
elements. The thickness of structural fill should increase from west to east across the project limits.
Based on our experience, the theory of elasticity, and using an allowable bearing pressure of 5,000
psf, we estimate the total settlement for footings constructed as described above will be less than
¾-inch. Differential settlements within the limits of the planned addition should be on the order of
one-half this magnitude.
The lateral resistance of spread footings is controlled by a combination of sliding resistance
between the footing and the foundation material at the base of the footing and the passive earth
pressure against the side of the footing in the direction of movement. Design parameters are given
in the recommendations section of this report.
New footings for additions which are placed adjacent to the existing building foundation will increase
the stress on the subgrade beneath the existing footing and depending on the soil type which
Gibson Guitar Expansion Engineering Analysis Bozeman, Montana Page 7
supports these footings can induce additional settlements beneath the existing structure. If similar
over-excavation and replacement methods were utilized on the original building construction, the
potential for additional settlements associated with the addition will be minor; however, if native
clays were left in place beneath the existing structure, this can have significant impacts to the
original building both in long-term performance and constructability of the planned addition. At this
time, we have no information regarding how the original foundation system was supported; thus, it
is prudent to assume worst-case scenarios in which the structure is founded on the soft
compressible clay soils. To help reduce the potential for constructability issues and future
settlements of existing structure, new spread footings placed adjacent to the existing structure
should be separated from the existing footings by a lateral distance of at least six feet. This will
help to prevent potential undermining of the existing foundation during the removal and replacement
of the clay soils by maintaining a maximum construction slope of 1:1 (horizontal to vertical) near
existing foundation elements and provide separation between foundations so that new foundation
loads are not applied to subgrade beneath the existing structure. The structure would need to
utilize cantilevered elements within this separation zone. This separation may not be warranted if
additional investigation is performed or construction documents are available which indicate that the
clay soils were removed from beneath the existing structure. The need for separation will be
controlled by the limits of the original structural fill and the potential for undermining the existing
foundations during the construction of the planned addition.
4.4 Foundation and Retaining Walls
Foundation walls and other soil retaining structures which will retain differential soil heights are not
anticipated for this project based on the intended use of interior slab-on-grade construction and the
relative flat conditions on site. If similar soil retaining structures are needed as part of the final
design or if the planned foundation system is changed in include either crawlspace or basement
features, we should be contacted to provide suitable design recommendations for these structures.
4.5 Floor Slabs and Exterior Flatwork
The natural on-site soils, exclusive of topsoil, are suitable to support conventional exterior concrete
flatwork. A leveling course of granular fill directly beneath the slab is recommended to provide a
structural cushion, a capillary-break from the subgrade, and a drainage medium. Construction
typically utilizes four to six inches of compacted granular fill beneath exterior flatwork; however, the
requirements may vary locally. Similar construction is considered typical for exterior flatwork and
has not been evaluated for expected performance or potential settlement risks.
The natural on-site soils are also suitable to support interior floor slabs but warrant the use of an
increased structural gravel layer beneath the concrete to account for the high clay moistures and
the anticipated difficulties with compaction of the subgrade layer. All interior slab systems should
utilize at least 18 inches of compacted structural fill which is separated from the prepared subgrade
by a geotextile fabric.
Gibson Guitar Expansion Engineering Analysis Bozeman, Montana Page 8
4.6 Pavements
A pavement section is a layered system designed to distribute concentrated traffic loads to the
subgrade. Performance of the pavement structure is directly related to the physical properties of the
subgrade soils and the magnitude and frequency of traffic loadings. Pavement design procedures
are based on strength properties of the subgrade and pavement materials, along with the design
traffic conditions. Traffic information was not available at the time of this report. We have assumed
that traffic for the parking lots will be primarily limited to passenger-type vehicles; however, some
routes will be utilized for heavier truck traffic and warrant a stronger pavement system. We have
provided two pavements sections as part of this report for use in general parking lot and heavy truck
routes within the site development.
The pavements sections provided below consider the anticipated traffic for the development after
completion of construction only and have not considered construction traffic as part of their intended
use. Thus, if areas are to be utilized by the contractor for access of concrete trucks, delivery
vehicles, or other large construction equipment they should be evaluated further based on the size
and number of vehicles anticipated in order to adjust the pavement section accordingly. Use of the
pavement sections provided without modification to account for construction traffic will reduce the
overall life expectancy of the asphalt or lead to unstable subgrades which require repair prior to
paving.
The potential worst-case subgrade material is the soft lean clay soils, which are classified as an A-7
soil in accordance with the American Association of State Highway and Transportation Officials
(AASHTO) classification. AASHTO considers this soil type to be a poor subgrade material due to
its inferior drainage properties and loss of strength at elevated moistures. Laboratory testing
measured a California Bearing Ratio (CBR) value for the lean clay of two percent assuming the
subgrade could be compacted to at least 95 percent of the maximum dry density for the material.
However, in-situ moisture contents indicate that moisture contents at a two-foot depth range from
21 to 32 percent and average 25.5 percent. These values are 3 to 14 percent above the optimum
moisture content for this material; thus, compaction to the levels required for this CBR value are
unlikely. For this reason, the pavement sections provided in this report have utilized a CBR value of
only one percent to account for the low density expected at the subgrade elevation for this project.
During construction, the subgrade should be cleared of all loose soil and construction debris and
rolled smooth prior to the installation of a separation geotextile and the gravel materials associated
with the pavement system. Excessive compaction, especially using vibratory methods, could
induce subgrade pumping and instability and should be avoided.
A geotextile acting as a separator is recommended between the pavement section gravels and the
prepared clay subgrade. The geotextile will prevent the upward migration of fines and the loss of
aggregate into the subgrade, thereby prolonging the structural integrity and performance of the
pavement section.
Gibson Guitar Expansion Engineering Analysis Bozeman, Montana Page 9
The pavement section presented in this report is based on an assumed CBR value of one percent,
assumed traffic loadings, recommended pavement section design information presented in the
Asphalt Institute and AASHTO Design Manuals, and our past pavement design experience in
Bozeman.
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 10
5.0 RECOMMENDATIONS
5.1 Site Grading and Excavations
1. All topsoil and organic material, asphalt, concrete and related construction debris
should be removed from the proposed addition and pavement areas and any areas
to receive site grading fill. For planning purposes, stripping thicknesses of up to two
feet may be required to remove detrimental organics; however, thicker stripping
depths are anticipated to remove existing asphalt and other site features within the
planned addition.
2. All fill and backfill should be non-expansive, free of organics and debris and should
be approved by the project geotechnical engineer. The on-site soils, exclusive of
topsoil, may be utilized as backfill and general site grading fill on this project.
However, native clay exhibit moisture contents which are elevated beyond typical
compaction levels and moisture conditioning should be expected prior to use. This
often requires the material to be spread out over a relatively large area and worked
to facilitate drying to suitable moisture levels.
All fill should be placed in uniform lifts not exceeding 8 inches in thickness for fine-
grained soils and not exceeding 12 inches for granular soils. All materials
compacted using hand compaction methods or small walk-behind units should
utilize a maximum lift thickness of 6 inches to ensure adequate compaction
throughout the lift. All fill and backfill shall be moisture conditioned to near the
optimum moisture content and compacted to the following percentages of the
maximum dry density determined by a standard proctor test which is outlined by
ASTM D698 or equivalent (e.g. ASTM D4253-D4254).
a) Structural Fill Below Foundations ................................................ 98%
b) Structural Fill Below Interior Slabs .............................................. 95%
c) Foundation Wall Backfill (Interior / Exterior) ......................... 95 / 92%
d) Gravel Courses Below Streets & Parking Lots ........................... 95%
e) General Landscaping or Nonstructural Areas ............................. 90%
For your consideration, verification of compaction requires laboratory proctor tests to
be performed on a representative sample of the soil prior to construction. These
tests can require up to one week to complete (depending on laboratory backlog) and
this should be considered when coordinating the construction schedule to ensure
that delays in construction or additional testing expense is not required due to
laboratory processing times or rush processing fees.
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 11
3. Imported structural fill should be non-expansive, free of organics and debris, and
conform to the material requirements outlined in Section 02235 of the Montana
Public Works Standard Specifications (MPWSS). All gradations outlined in this
standard are acceptable for use on this project; however, conventional proctor
methods (outlined in ASTM D698) shall not be used for any materials containing
less than 70 percent passing the ¾-inch sieve. Conventional proctor methods are
not suitable for these types of materials, and the field compaction value must be
determined using a relative density test outlined in ASTM D4253-4254.
Alternative structural fill materials containing rocks larger than those permitted by
MPWSS Section 02235 may be considered provided they are approved by the
geotechnical engineer prior to use and the field compaction value is determined
using the appropriate method to be specified by the geotechnical engineer.
However, materials containing rocks larger than 3-inch diameter will not be
considered acceptable for structural fill applications.
4. Develop and maintain site grades which will rapidly drain surface and roof runoff
away from foundation and subgrade soils; both during and after construction. The
final site grading shall conform to the grading plan, prepared by others to satisfy the
minimum requirements of the applicable building codes.
5. It is the responsibility of the Contractor to provide safe working conditions in
connection with underground excavations. Temporary construction excavations
greater than four feet in depth, which workers will enter, will be governed by OSHA
guidelines given in 29 CFR, Part 1926. For planning purposes, subsoils
encountered in the test pits are considered Type C for the native clay and gravel
strata due to the anticipated low strength of the clay material. The soil conditions on
site can change due to changes in soils moisture or disturbances to the site prior to
construction. Thus, the contractor is responsible to provide an OSHA
knowledgeable individual during all excavation activities to regularly assess the soil
conditions and ensure that all necessary safety precautions are implemented and
followed.
5.2 Conventional Shallow Foundations
The design and construction criteria below should be observed for a conventional shallow
foundation system. The construction details should be considered when preparing the project
documents.
6. Both interior and exterior footings should bear on properly compacted structural fill
extending down to native gravels. Structural fill thickness are anticipated to range
from 0 to 6 feet and increase from west to east across the site. All structural fill shall
be placed and compacted as outlined in Item 2 above. The contractor should
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 12
anticipate the need for dewatering at the time of construction to facilitate the proper
placement and compaction of the structural fill beneath footing elements. The limits
of the structural fill shall extend at least 24 inches beyond the outer face of the
footing in all directions.
Footings which are designed and constructed as described above, should be
designed for a maximum allowable soil bearing pressure of 5,000 psf provided
settlements as outlined in the Engineering Analysis are acceptable.
7. To reduce structural distress caused by slab movements, all interior load-bearing
walls and columns should be supported on separate spread footings constructed as
described in Item 6 above. Conventional slab-on-grade construction consisting of
interior walls bearing directly on the slab or thickened portions of the slab is not
recommended for this project unless the clay is to be removed and replace within
the entire footprint of the planned addition.
8. Soils disturbed below the planned depths of footing excavations should be re-
compacted to the requirements of Item 2 above.
9. Footings shall be sized to satisfy the minimum requirements of the applicable
building codes while not exceeding the maximum allowable bearing pressure
provided in Item 6 above.
10. Exterior footings and footings beneath unheated areas should be placed at least 48
inches below finished exterior grade for frost protection.
11. Lateral loads are resisted by sliding friction between the footing base and the
supporting soil and by lateral pressure against the footings opposing movement.
For design purposes, a friction coefficient of 0.45 and a lateral resistance pressure
of 200 psf per foot of depth are appropriate for footings bearing on properly
compacted structural fill and backfilled with compacted native soils.
12. When native soil may be supported by clay soils, new footings placed adjacent to
the existing structure should be separated from the existing footings by a distance of
at least six feet to reduce the potential for undermining existing footing elements
during the removal of the native clay and to limit new foundation stresses beneath
existing foundation elements. This distance is measured between the nearest
exterior face of two footing elements. If additional investigation or as-built
information can confirm that the native clay was removed and replaced, this
requirement may not be warranted depending on the limits of the original structural
fill placed.
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 13
13. A representative of the project geotechnical engineer should be retained to observe
all footing excavations and backfill phases prior to the placement of concrete
formwork to verify that all clay soils have been removed and that compaction of the
subsequent structural fill conforms to these recommendations.
14. Only hand-operated compaction equipment should be used within 5 feet of
foundation walls. Foundation backfill should be placed in lifts of equal thickness
which alternative from interior to exterior of the foundation wall.
15. Exterior footing drains are not required for this project based on the intended use of
slab-on-grade construction assuming the interior finished floor elevation will be
higher than the final exterior grade adjacent to the building at all locations. If interior
slabs will lie below exterior grade or if a crawlspace of basement configuration is
considered, we should be consulted to provide additional recommendations and
details pertaining to suitable foundation drain systems.
5.3 Floor Slabs and Exterior Flatwork
16. For normally loaded, exterior concrete flatwork, a typical cushion course consisting
of free-draining, crushed gravel should be placed beneath the concrete and
compacted to the requirements of Item 2b above. Cushion course thicknesses
generally range from four to six inches but may vary based on local requirements.
Conventional construction, as has been described, is not intended to mitigate
potential settlement concerns associated with the soft clay subsurface conditions
encountered. In most cases, the cost to repair and/or replace exterior flatwork when
excessive movements occur is far more economical than efforts to mitigate these
movements. However, if no acceptable risk of movements for exterior flatwork is
acceptable for this project, additional improvements beneath exterior flatwork should
be considered.
17. For normally loaded, interior slab-on-grade construction, a minimum 18-inch cushion
course consisting of free-draining, crushed gravel should be placed beneath the slab
and compacted to the requirements of Item 2b above. Prior to gravel installation,
the clay subgrade should be cleared of all loose soil and debris, static rolled, and a
separation geotextile consisting of a Mirafi 600X, or equivalent, installed in
accordance with all manufacturer recommendations.
18. Cushion course materials utilized beneath slab-on-grade applications should
conform to the requirements outlined in Section 02235 of the Montana Public Works
Standard Specifications (MPWSS). All gradations outlined in this specification are
acceptable based on local availability and contractor preference.
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 14
19. Interior floor slabs should be designed using a modulus of vertical subgrade reaction
no greater than 100 pci when designed and constructed as recommended above.
20. Geotechnically, an underslab vapor barrier is recommended for this project due to
the high soil moisture within the native clay and potential for ground water
fluctuations which have not been evaluated for the site. This is especially important
in any portions of the addition to receive moisture sensitive flooring materials. The
type and grade of vapor barrier shall be specified by the structural engineer or
architect.
5.4 Pavements
21. The following pavement section or an approved equivalent section should be
selected in accordance with the discussions in the Engineering Analysis.
Pavement Component
Component Thickness
General Parking
Section
Heavy Truck
Route Section
Asphalt Pavement 3” 4”
Crushed Base Course 9” 6”
Crushed Subbase Course 12” 18”
Total 24” 28”
* The pavement sections provided have not considered construction traffic during in their development. Modification to these
sections may be warranted and need additional evaluation if the contractor intends to utilize areas for construction vehicle
access during or after the completion of asphalt paving.
22. Final pavement thicknesses exceeding 3 inches shall be constructed in two uniform
lifts.
23. Gradations for the crushed base courses shall conform to Section 02235 of the
Montana Public Works Standard Specifications (MPWSS). All gradations outlined in
this specification are acceptable for this application based on the local availability
and contractor preference. The gradation for the subbase shall conform to Section
02234 of the MPWSS.
24. If existing grades will be raised more than the thickness of the pavement section at
any location, all fill should be placed, compacted and meet the general requirements
given in Item 2 above.
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 15
25. A geotextile is recommended between the pavement section and the prepared
subgrade to prevent the migration of fines upward into the gravel and the loss of
aggregate into the subgrade. A Mirafi 600X or equivalent geotextile is appropriate.
26. Based on the local climate, asphaltic cement should be a Performance Graded (PG)
binder having the following minimum high and low temperature values based on the
desired pavement reliability.
Reliability Min. High Temp Rating Min. Low Temp Rating Ideal Oil Grade
50% 33.8 -30.6 PG 52-34
98% 37.5 -39.5 PG 52-40
In our experience, neither of the ideal oil grades outlined above are locally available
for use. Thus, these materials would require the import of a specialized product and
custom mid design which is likely not practical for this project. Most local
construction utilizes a PG 58-28 product which is a standard asphalt binder
discussed in MPWSS specifications. We recommend the use of this material for the
asphalt pavements for this project as it will provide the highest level of performance
obtainable using readily available products.
5.5 Continuing Services
Three additional elements of geotechnical engineering service are important to the successful
completion of this project.
27. Consultation between the geotechnical engineer and the design professionals
during the design phases is highly recommended. This is important to ensure that
the intentions of our recommendations are incorporated into the design, and that
any changes in the design concept consider the geotechnical limitations dictated by
the on-site subsurface soil and ground water conditions.
28. Observation, monitoring, and testing during construction is required to document the
successful completion of all earthwork and foundation phases. A geotechnical
engineer from our firm should be retained to observe the excavation, earthwork, and
foundation phases of the work to determine that subsurface conditions are
compatible with those used in the analysis and design.
29. During site grading, placement of all fill and backfill should be observed and tested
to confirm that the specified density has been achieved. We recommend that the
Owner maintain control of the construction quality control by retaining the services of
an experienced construction materials testing laboratory. We are available to
provide construction inspection services as well as materials testing of compacted
Gibson Guitar Expansion Recommendations Bozeman, Montana Page 16
soils and the placement of Portland cement concrete and asphalt. In the absence of
project specific testing frequencies, TD&H recommends the following minimum
testing frequencies be used:
Compaction Testing
Structural Fill Beneath Footings 1 Test per Column Footing per Lift
1 Test per 50 LF of Wall Footing per Lift
Structural Fill Beneath Interior Slabs 1 Test per 1,500 SF per Lift
Foundation Backfill 1 Test per 50 LF of Wall per Lift
Parking Lot & Access Roads 1 Test per 2,500 SF per Lift
LF = Lineal Feet SF = Square Feet
Gibson Guitar Expansion Summary of Field & Laboratory Studies Bozeman, Montana Page 17
6.0 SUMMARY OF FIELD AND LABORATORY STUDIES
6.1 Field Explorations
The field exploration program was conducted on January 8, 2020. A total of seven test pits were
excavated to depths ranging from 5.9 to 10.8 feet at the approximate locations shown on Figure 1 to
observe subsurface soil and ground water conditions. The tests pits were excavated by Earth
Surgeons Excavation, LLC using a Komatsu 88 mini-excavator. The subsurface exploration and
sampling methods used are indicated on the attached test pit logs. The test pits were logged by Mr.
Ahren Hastings, PE of TD&H Engineering. The location of the borings were estimated by Mr.
Hastings based on their relative proximity to existing surface features visible on an aerial image of
the property.
Composite grab samples from the test pits were collected at distinct changes in the subsurface
stratigraphy and at regularly spaced intervals within each test pit. Samples were collected from
excavation spoils after removal from the test pit. A log of each test pit, which include soil
descriptions and sample depths, are presented on the Figures 2 through 8.
Measurements to determine the depth of ground water in the test pits were made using a steel tape
measure shortly after the completion of excavating. The depths or elevations of the water levels
measured, if encountered, and the date of measurement are shown on the test pit logs.
6.2 Laboratory Testing
Samples obtained during the field exploration were returned to our materials laboratory where they
were observed and visually classified in general accordance with ASTM D2487, which is based on
the Unified Soil Classification System. Representative samples were selected for testing to
determine the engineering and physical properties of the soils in general accordance with ASTM or
other approved procedures.
Tests Conducted: To determine:
Natural Moisture Content Representative moisture content of soil at the time of sampling.
Grain-Size Distribution Particle size distribution of soil constituents describing the percentages of clay/silt, sand and gravel.
Atterberg Limits A method of describing the effect of varying water content on the consistency and behavior of fine-grained soils.
UU Shear Strength (Field) The undrained, unconfined shear strength (su) of cohesive soils as determined in the field by either a pocket
penetrometer or a hand torvane.
Gibson Guitar Expansion Summary of Field & Laboratory Studies Bozeman, Montana Page 18
Moisture-Density Relationship A relationship describing the effect of varying moisture content and the resulting dry unit weight at a given
compactive effort. Provides the optimum moisture content and the maximum dry unit weight. Also called a Proctor Curve.
California Bearing Ratio The measure of a subgrade’s or granular base’s ability to resist deformation due to penetration during a saturated
condition. Used to assist in pavement thickness designs.
The laboratory testing program for this project consisted of 11 moisture-visual analyses, 3 sieve
(grain-size distribution) analyses, and 3 Atterberg Limits analyses. The results of the water content
analyses are presented on the test pit logs, Figures 2 through 8. The grain-size distribution curves
and Atterberg limits are presented on Figures 9 through 14. In addition, one proctor (moisture-
density) test and one California Bearing Ratio (CBR) test were performed. The CBR and moisture
density relationships are shown on Figures 15 through 16. The results are shown on the test pit logs
at the depths the samples were tested.
Gibson Guitar Expansion Limitations Bozeman, Montana Page 19
7.0 LIMITATIONS
This report has been prepared in accordance with generally accepted geotechnical engineering
practices in this area for use by the client for design purposes. The findings, analyses, and
recommendations contained in this report reflect our professional opinion regarding potential
impacts the subsurface conditions may have on the proposed project and are based on site
conditions encountered. Our analysis assumes that the results of the exploratory test pits are
representative of the subsurface conditions throughout the site, that is, that the subsurface
conditions everywhere are not significantly different from those disclosed by the subsurface study.
Unanticipated soil conditions are commonly encountered and cannot be fully determined by a
limited number of soil test pits and laboratory analyses. Such unexpected conditions frequently
require that some additional expenditures be made to obtain a properly constructed project.
Therefore, some contingency fund is recommended to accommodate such potential extra costs.
The recommendations contained within this report are based on the subsurface conditions
observed in the test pits and are subject to change pending observation of the actual subsurface
conditions encountered during construction. TD&H cannot assume responsibility or liability for the
recommendations provided if we are not provided the opportunity to perform limited construction
inspection and confirm the engineering assumptions made during our analysis. A representative of
TD&H should be retained to observe all construction activities associated with subgrade
preparation, foundations, and other geotechnical aspects of the project to ensure the conditions
encountered are consistent with our assumptions. Unforeseen conditions or undisclosed changes
to the project parameters or site conditions may warrant modification to the project
recommendations.
Long delays between the geotechnical investigation and the start of construction increase the
potential for changes to the site and subsurface conditions which could impact the applicability of
the recommendations provided. If site conditions have changed because of natural causes or
construction operations at or adjacent to the site, TD&H should be retained to review the contents of
this report to determine the applicability of the conclusions and recommendations provide
considering the time lapse or changed conditions.
Misinterpretation of the geotechnical information by other design team members is possible and can
result in costly issues during construction and with the final product. Our engineers are available to
assist in reviewing the portions of the plans and specifications which pertain to earthwork and
foundations to assess their consistency with our recommendations and to suggest necessary
modifications as warranted. This additional service is not included in our current scope of work and
would be performed for additional fees when requested. TD&H should be involved throughout the
construction process to observe construction, particularly the placement and compaction of all fill,
preparation of all foundations, and all other geotechnical aspects. Retaining the geotechnical
engineer who prepared your geotechnical report to provide construction observation is the most
effective method of managing the risks associated with unanticipated conditions.
Gibson Guitar Expansion Limitations Bozeman, Montana Page 20
This report was prepared for the exclusive use of the owner and architect and/or engineer in the
design of the subject facility. It should be made available to prospective contractors and/or the
contractor for information on factual data only and not as a warranty of subsurface conditions such
as those interpreted from the test pit logs and presented in discussions of subsurface conditions
included in this report.
Prepared by: Reviewed by: Craig Nadeau PE Ahren Hastings PE Geotechnical Manager Geotechnical Engineer TD&H ENGINEERING TD&H ENGINEE RING
J:\2019\B19-110 Gibson Guitar Expansion\GEOTECH\REPORTS\Gibson Guitar Expansion.doc
GIBSON GUITAR EXPANSION BOZEMAN, MONTANA TEST PIT LOCATION MAP FIGURE 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
- See Figures 15 and 16 for proctor and CBR results.
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
1.8
10.0
10.6
G
G
LEGEND LOG OF TEST PIT TP-1Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.2
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
qu = 0.5 tsf
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
1.1
10.4
10.8
G
G
LEGEND LOG OF TEST PIT TP-2Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.3
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
qu = 0.5 tsf
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
1.0
6.1
8.0
G
G
LEGEND LOG OF TEST PIT TP-3Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.4
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
qu = 0.5 tsf
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
1.8
4.6
7.5
G
G
LEGEND LOG OF TEST PIT TP-4Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.5
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
qu = 0.5 tsf
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
0.5
3.6
7.8
G
G
LEGEND LOG OF TEST PIT TP-5Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.6
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
qu = 0.5 tsf
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
0.6
4.2
6.1
G
G
LEGEND LOG OF TEST PIT TP-6Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.7
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
0
1.5
3
4.5
6
7.5
9
10.5
TOPSOIL: Lean CLAY, appears firm, dark brown, slightly
moist, organics
Lean CLAY, appears firm to soft, brown to light brown,
slightly moist to moist, increasing moisture with depth
Poorly-Graded GRAVEL with Sand, relatively dense, brown,
red, and gray, moist to wet
Bottom of Test Pit
0.5
4.9
5.9
LEGEND LOG OF TEST PIT TP-7Atterberg Limits
Field Moisture content Gibson Guitar Expansion
Bozeman, MontanaGroundwater Level
Grab/composite sample
Logged by:Ahren Hastings, PE
Excavated by:Earth Surgeons
Komatsu 88GNP = Granular and Nonplastic
Note: The stratification lines represent approximate
boundaries between soil types. Actual boundaries
may be gradual or transitional.
January 8, 2020 B19-110-001
Figure No.8
Sheet
GR
A
P
H
I
C
LO
G
SOIL DESCRIPTION
SURFACE:Native Grasses
SURFACE ELEVATION:Not Measured
DE
P
T
H
(
F
T
)
GR
O
U
N
D
WA
T
E
R
SA
M
P
L
E
DE
P
T
H
(
F
T
)
MOISTURE CONTENT
0 10 20 30 40 50
= MOISTURE CONTENT
1 of 1
Tested By: WJC/TF Checked By:
1-27-2020
9
(no specification provided)
PL=LL=PI=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
USCS=AASHTO=
*
Lean CLAY
3/8"
#4
#10
#20
#40
#60
#80
#100
#200
100.0
99.9
99.7
99.3
98.6
97.8
96.9
96.1
90.8
CL
Report No. A-20734-206
Langlas & Associates
Gibson Guitar Expansion
Bozeman, Montana
B19-110-001
Material Description
Atterberg Limits
Coefficients
Classification
Remarks
Location: TP-1
Sample Number: A-20734 Depth: 4.0 ft Date:
Client:
Project:
Project No:Figure
SIEVE PERCENT SPEC.*PASS?
SIZE FINER PERCENT (X=NO)
PE
R
C
E
N
T
F
I
N
E
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.00010.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 0.1 0.2 1.1 7.8 90.8
6
i
n
.
3
i
n
.
2
i
n
.
1½
i
n
.
1
i
n
.
¾ i
n
.
½ i
n
.
3/
8
i
n
.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Particle Size Distribution Report
Tested By: WJC/TF Checked By:
1-27-2020
10
(no specification provided)
PL=LL=PI=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
USCS=AASHTO=
*
Lean CLAY
1.5"
1"
3/4"
1/2"
3/8"
#4
#10
#20
#40
#60
#80
#100
#200
100.0
99.9
99.2
98.9
98.6
98.3
97.8
97.4
96.5
95.4
94.2
93.2
89.1
20 38 18
0.0867
CL A-6(16)
Report No. A-20735-206
Langlas & Associates
Gibson Guitar Expansion
Bozeman, Montana
B19-110-001
Material Description
Atterberg Limits
Coefficients
Classification
Remarks
Location: TP-1
Sample Number: A-20735 Depth: 6.0 - 7.0 ft Date:
Client:
Project:
Project No:Figure
SIEVE PERCENT SPEC.*PASS?
SIZE FINER PERCENT (X=NO)
PE
R
C
E
N
T
F
I
N
E
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.00010.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.8 0.9 0.5 1.3 7.4 89.1
6
i
n
.
3
i
n
.
2
i
n
.
1½
i
n
.
1
i
n
.
¾ i
n
.
½ i
n
.
3/
8
i
n
.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Particle Size Distribution Report
Tested By: TF/WJC Checked By:
1-27-2020
11
(no specification provided)
PL=LL=PI=
D90=D85=D60=
D50=D30=D15=
D10=Cu=Cc=
USCS=AASHTO=
*
Lean CLAY
3/4"
1/2"
3/8"
#4
#10
#20
#40
#60
#80
#100
#200
100.0
98.2
97.6
94.5
92.3
91.1
90.3
89.8
89.2
88.6
85.2
0.3201
CL
Report No. A-20738-206
Langlas & Associates
Gibson Guitar Expansion
Bozeman, Montana
B19-110-001
Material Description
Atterberg Limits
Coefficients
Classification
Remarks
Location: TP-3
Sample Number: A-20738 Depth: 2.0 ft Date:
Client:
Project:
Project No:Figure
SIEVE PERCENT SPEC.*PASS?
SIZE FINER PERCENT (X=NO)
PE
R
C
E
N
T
F
I
N
E
R
0
10
20
30
40
50
60
70
80
90
100
GRAIN SIZE - mm.
0.00010.0010.010.1110100
% +3"Coarse
% Gravel
Fine Coarse Medium
% Sand
Fine Silt
% Fines
Clay
0.0 0.0 5.5 2.2 2.0 5.1 85.2
6
i
n
.
3
i
n
.
2
i
n
.
1½
i
n
.
1
i
n
.
¾ i
n
.
½ i
n
.
3/
8
i
n
.
#4 #1
0
#2
0
#3
0
#4
0
#6
0
#1
0
0
#1
4
0
#2
0
0
Particle Size Distribution Report
Tested By: BC Checked By:
LIQUID AND PLASTIC LIMITS TEST REPORT
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
0
10
20
30
40
50
60
LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML
C L o r O L
C H o r O H
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
47
WA
T
E
R
C
O
N
T
E
N
T
36
36.4
36.8
37.2
37.6
38
38.4
38.8
39.2
39.6
40
NUMBER OF BLOWS
5 6 7 8 9 10 20 25 30 40
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No.Client:Remarks:
Project:
Location: TP-1
Sample Number: A-20735 Depth: 6.0 - 7.0 ft
Figure
Lean CLAY 38 20 18 96.5 89.1 CL
B19-110-Langlas & Associates
12
Report No. A-20735-207
Date: 1-27-2020Gibson Guitar Expansion
Bozeman, Montana
Tested By: BC Checked By:
LIQUID AND PLASTIC LIMITS TEST REPORT
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
0
10
20
30
40
50
60
LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML
C L o r O L
C H o r O H
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
47
WA
T
E
R
C
O
N
T
E
N
T
33.5
33.7
33.9
34.1
34.3
34.5
34.7
34.9
35.1
35.3
35.5
NUMBER OF BLOWS
5 6 7 8 9 10 20 25 30 40
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No.Client:Remarks:
Project:
Location: TP-4
Sample Number: A-20741 Depth: 4.0 ft
Figure
Lean CLAY 34 20 14 CL
B19-110-Langlas & Associates
13
Report No. A-20741-207
Date: 1-27-2020Gibson Guitar Expansion
Bozeman, Montana
Tested By: BC Checked By:
LIQUID AND PLASTIC LIMITS TEST REPORT
PL
A
S
T
I
C
I
T
Y
I
N
D
E
X
0
10
20
30
40
50
60
LIQUID LIMIT
0 10 20 30 40 50 60 70 80 90 100 110
CL-ML
C L o r O L
C H o r O H
ML or OL MH or OH
Dashed line indicates the approximate
upper limit boundary for natural soils
47
WA
T
E
R
C
O
N
T
E
N
T
36.4
36.8
37.2
37.6
38
38.4
38.8
39.2
39.6
40
40.4
NUMBER OF BLOWS
5 6 7 8 9 10 20 25 30 40
MATERIAL DESCRIPTION LL PL PI %<#40 %<#200 USCS
Project No.Client:Remarks:
Project:
Location: TP-6
Sample Number: A-20744 Depth: 2.0 ft
Figure
Lean CLAY 38 19 19 CL
B19-110-Langlas & Associates
14
Report No. A-20744-207
Date: 1-27-2020Gibson Guitar Expansion
Bozeman, Montana
Tested By: TF Checked By:
Moisture-Density Test Report
Dr
y
d
e
n
s
i
t
y
,
p
c
f
90
95
100
105
110
115
Water content, %
11 13 15 17 19 21 23
18.2%, 107.0 pcf
ZAV for
Sp.G. =
2.65
Test specification:ASTM D 698-12 Method A Standard
6.0 - 7.0 ft CL A-6(16)2.65 38 18 1.7 89.1
Lean CLAY
B19-110-Langlas & Associates
Report No. A-20735-204
Date: 1-17-2020
15
Elev/Classification Nat.Sp.G. LL PI % > % <
Depth USCS AASHTO Moist.#4 No.200
TEST RESULTS MATERIAL DESCRIPTION
Project No.Client:Remarks:
Project:
Location: TP-1 Sample Number: A-20735
Figure
Maximum dry density = 107.0 pcf
Optimum moisture = 18.2 %
Gibson Guitar Expansion
Bozeman, Montana
BEARING RATIO TEST REPORT
ASTM D 1883-07
Project No: B19-110-001
Project: Gibson Guitar Expansion Bozeman, Montana
Location: TP-1
Sample Number: A-20735 Depth: 6.0 - 7.0 ft
Date: 1-27-2020
Lean CLAY
Test Description/Remarks:
ASTM D698 with 6-inch Mold
168 hour soak prior to testing
Report No. A-20735-210
Date: 2-10-2020
Figure 16
107.0 18.2 38 18CL
Material Description USCS
Max.
Dens.
(pcf)
Optimum
Moisture
(%)
LL PI
Molded
Density
(pcf)
Percent of
Max. Dens.
Moisture
(%)
Soaked
Density
(pcf)
Percent of
Max. Dens.
Moisture
(%)
CBR (%)
0.10 in. 0.20 in.
Linearity
Correction
(in.)
Surcharge
(lbs.)
Max.
Swell
(%)
1 101.2 94.6 18.0 101.1 94.5 20.7 1.8 2.3 0.026 10 0.1
2 106.8 99.8 17.9 106.8 99.8 18.3 4.7 4.7 0.000 10 0
3
Pe
n
e
t
r
a
t
i
o
n
R
e
s
i
s
t
a
n
c
e
(
p
s
i
)
0
40
80
120
160
200
Penetration Depth (in.)
0 0.1 0.2 0.3 0.4 0.5
Sw
e
l
l
(
%
)
0
0.1
0.2
0.3
0.4
0.5
Elapsed Time (hrs)
0 24 48 72 96 120 144 168
CB
R
(
%
)
0
1.5
3
4.5
6
Molded Density (pcf)
99 101 103 105 107 109
10 blows
56 blows
CBR at 95% Max. Density = 2.0%
for 0.10 in. Penetration