HomeMy WebLinkAboutAppendix C - Lyman Reservoir Predesign Final Report APPENDIX C: LYMAN RESERVOIR PREDESIGN FINAL REPORT
LYMAN RESERVOIR
PREDESIGN REPORT
PREPARED FOR:
CITY OF BOZEMAN
BOZEMAN, MONTANA
PREPARED BY:
2880 TECHNOLOGY BLVD W
BOZEMAN, MONTANA 59718
SEPTEMBER 2026
Contents
CHAPTER 1 INTRODUCTION ...................................................................................................... 1-1
1.1. Background ......................................................................................................................... 1-1
1.2. Reservoir History ................................................................................................................. 1-1
CHAPTER 2 EXISTING FACILITY ................................................................................................ 2-1
2.1. Existing Condition ................................................................................................................ 2-1
2.1.1. 2020 Assessment .......................................................................................................... 2-1
2.1.2. 2026 Assessment .......................................................................................................... 2-1
2.2. Operations ........................................................................................................................... 2-7
CHAPTER 3 ALTERNATIVES ANALYSIS .................................................................................... 3-9
3.1. General Design Parameters ................................................................................................ 3-9
3.2. Alternatives Definition ........................................................................................................ 3-10
3.2.1. Rehabilitation............................................................................................................... 3-10
3.2.2. New Reservoir ............................................................................................................. 3-12
3.3. Alternative Costs ............................................................................................................... 3-14
3.3.1. Capital Cost – Construction ......................................................................................... 3-14
3.3.2. Capital Cost – Non-Construction ................................................................................. 3-15
3.3.3. Life-Cycle Costs .......................................................................................................... 3-15
3.3.4. Estimated Alternative Costs ......................................................................................... 3-18
CHAPTER 4 ALTERNATIVES EVALUATION ............................................................................... 4-1
4.1. Alternatives Evaluation ........................................................................................................ 4-1
4.1.1. Alt 1.1 Rehab Existing Reservoir with New Geomembrane Liner................................... 4-1
4.1.2. Alt 1.2 Rehab Existing Reservoir with Concrete Coating System ................................... 4-2
4.1.3. Alt 2.1 Rehab Existing Reservoir with Geomembrane Liner + New 1 MG Reservoir ...... 4-2
4.1.4. Alt 2.2 Rehab Existing Reservoir with Coating System + New 1 MG Reservoir ............. 4-3
4.1.5. Alt 3 New 5 MG Reservoir at Existing Site ..................................................................... 4-3
4.1.6. Alt 4 New 5 MG Reservoir and Treatment at Upgradient Site ........................................ 4-4
4.1.7. Key Takeaways ............................................................................................................. 4-4
4.1.8. Alternative Rankings ...................................................................................................... 4-5
CHAPTER 5 RECOMMENDATIONS ............................................................................................. 5-1
5.1. Preferred Alternative ............................................................................................................ 5-1
5.2. Proposed Project ................................................................................................................. 5-1
5.2.1. Anticipated Project Scope.............................................................................................. 5-1
5.3. Conclusion ........................................................................................................................... 5-2
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Predesign Report Table of Contents
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List of Figures
Figure 1-1: Existing Reservoir Section ............................................................................................... 1-2
Figure 1-2: Existing Reservoir Plan .................................................................................................... 1-2
Figure 2-1: Storm Drain Inlet .............................................................................................................. 2-2
Figure 2-2: 1911 Concrete ................................................................................................................. 2-3
Figure 2-3: Liner Fold......................................................................................................................... 2-3
Figure 2-4: Reservoir Inlet ................................................................................................................. 2-4
Figure 2-5: Reservoir Outlet ............................................................................................................... 2-4
Figure 2-6 Reservoir Drain ................................................................................................................. 2-4
Figure 2-7: Groundwater Monitoring Levels ....................................................................................... 2-6
Figure 2-8: Average Daily Flow .......................................................................................................... 2-8
List of Tables
Table 2-1: Annual Demand ................................................................................................................ 2-8
Table 3-1: General Design Parameters .............................................................................................. 3-9
Table 3-2: Alternatives Summary ..................................................................................................... 3-10
Table 3-3: Estimated Alternative Costs ............................................................................................ 3-18
Table 4-1: Alternative Rankings ......................................................................................................... 4-5
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Predesign Report Table of Contents
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Appendices
Appendix A: Exhibits
• Figure 1 – Vicinity Map
• Figure 2 – Existing Conditions
• Figure 3 – Existing Reservoir Plan and Sections
• Figure 4 – Existing Hydraulic Profile
• Figure 5 – Borehole Exhibit
• Figure 6 – Alternatives 1.1 and 1.2 Rehab Existing Reservoir
• Figure 7 – Alternative 2.1 and 2.2 – 1 MG Reservoir and Rehab Existing Reservoir
• Figure 8 – Alternative 2.1 and 2.2 Hydraulic Profile
• Figure 9 – Alternative 3 – 5 MG Reservoir at Existing Site
• Figure 10 – Alternative 4 – 5 MG Reservoir at Upgradient Site
• Figure 11 – Concrete Investigation Map
Appendix B: Lyman Structural Assessment Report
Appendix C: 2026 Condition Assessment Photos
Appendix D: Geotechnical Assessment Report
Appendix E: Cost Estimates
Appendix F: Record Documents
• 1901 Water Hardboard
• 1911 Plan
• 1957 Plan and Section
• 2004 Plan and Section
• Existing Septic Permit
Lyman Reservoir Chapter 1
Predesign Report Introduction
Page 1-1
CHAPTER 1 INTRODUCTION
1.1. BACKGROUND
The City of Bozeman has retained Morrison-Maierle to complete predesign phase services for
improvements to the Lyman Reservoir. Originally constructed in 1889, the nominal five-million-gallon
Lyman Reservoir is one of the oldest major infrastructure assets in the City of Bozeman. The existing
geosynthetic liner exhibits significant leakage, necessitating evaluation of rehabilitation and
replacement alternatives.
The purpose of this report is to summarize the current condition of the existing reservoir and provide
an alternative analysis for improvements to the storage facility. The following alternatives were
evaluated:
• Alternative 1: Rehabilitate existing reservoir
Sub-Alternative 1.1: Rehabilitate with new geosynthetic liner
Sub-Alternative 1.2: Rehabilitate with concrete coating system
• Alternative 2: Rehabilitate existing reservoir and construct additional 1 MG reservoir
Sub-Alternative 2.1: Rehabilitate with new geosynthetic liner
Sub-Alternative 2.2: Rehabilitate with concrete coating system
• Alternative 3: Construct new 5 MG reservoir at existing site
• Alternative 4: Construct new 5 MG reservoir and treatment at upgradient site
1.2. RESERVOIR HISTORY
• 1889 – Original construction of open cavity trapezoidal reinforced concrete structure. Records
from 1901 indicate the original reservoir had a footprint of 124’ x 108’.
• 1911 – Reservoir enlarged to current approximate footprint. The bottom of the reservoir is
generally flat with a 0.4% slope towards the outlet pipes at the southwest end of the structure. It
appears that the original reservoir was located in the southwest corner of the 1911 footprint,
however it is unclear what portions of the original reservoir were retained, if any.
• 1957 – The sloped slabs were extended about four feet and four-foot-high walls added to the
perimeter of the structure to increase volume to the current capacity of approximately five
million gallons.
• 1989 – Inlet controls, chlorine building, and an HDPE floating cover were added.
• 2004 – This major improvements project consisted of concrete repairs, installation of a 45-mil
reinforced polypropylene liner with underdrain system, hanging polypropylene baffle walls, and
construction of an enclosed roof system. The roof structure is comprised of precast double-tee
roof beams and precast inverted tee beams supported by concrete columns within the footprint
of the reservoir and cast-in-place concrete walls around the perimeter of the reservoir. The roof
deck consists of foam insulation board and an EPDM membrane. An inlet control building with
a water treatment system and an outlet control building with metering and sampling were also
constructed.
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Predesign Report Introduction
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• 2008 – Improvements were made to the spring intake, chemical feed, and control systems. The
project also included installation of a dechlorination system for leakage water and related
discharge permit.
Figure 1-1 shows a cross-section of the existing reservoir and Figure 1-2 shows a plan view.
Figure 1-2: Existing Reservoir Plan
Figure 1-1: Existing Reservoir Section
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CHAPTER 2 EXISTING FACILITY
2.1. EXISTING CONDITION
The bottom dimensions of the reservoir are about 158’ by 73’ and the top dimensions are about 240’
by 157’. The reservoir is about 28 feet deep. The inside footprint of the building is 250 feet by 160 feet.
The existing liner is at the end of its useful life and has been leaking for many years. The City holds an
MPDES permit and dechlorinates the water collected by the underdrain system to allow discharge.
2.1.1. 2020 Assessment
A condition assessment and evaluation were performed by AE2S in 2020. The assessment, primarily
based on observations of visible components, indicated that the roof structure was in relatively good
condition. Exposed sections of the exterior reservoir building walls showed minor signs of wear, and
some soil subsidence was noted. The undersides of the roof deck and the EPDM roof membrane
appeared to be in good condition, with the roof membrane expected to have a remaining useful life of
20 years. The current condition of the concrete reservoir beneath the polypropylene liner is unknown,
but the evaluation presumed that it is likely in a similar state to when it was last observed in 2004. An
underwater inspection and overall condition assessment was performed by LEC who found the overall
condition of the reservoir to be good and recommended cleaning and inspection every 3 years.
The 2020 condition assessment also evaluated two primary alternatives for addressing the leaking
reservoir: rehabilitating the existing reservoir or constructing a new partially buried prestressed
concrete reservoir. The evaluation found reservoir replacement to be the least cost alternative based
on a 50-year life-cycle cost analysis that assumed a new reservoir would recover all lost revenue
water, but a rehabilitation would only recover half of lost revenue water. Reservoir replacement was
contemplated to occur at the current site or at a higher elevation to match the hydraulic grade line of
the South Pressure Zone pending additional study. A geotechnical investigation and study to
determine the optimal siting of a new reservoir were not performed at the time.
2.1.2. 2026 Assessment
Morrison-Maierle conducted a thorough visual inspection of the Lyman Reservoir site, buildings,
treatment system, and related facilities.
A site visit was conducted with operations staff on October 15, 2025 to review the existing inlet and
outlet control building components. An assessment of the reservoir structure and reservoir building
was conducted over the course of several days between February 20th, 2026 and March 5th, 2026.
The reservoir was drained to allow for visual inspection of the existing reservoir structure, liner, piping
and building. Minimal sediment was present in the bottom of the reservoir. Signs of concentrated leaks
from specific areas were not able to be identified by visual inspection of the liner. It is suspected that
the leakage is likely caused by numerous small leaks that are not readily identified rather than a few
larger leaks. The existing liner also showed signs of surface oxidation making it difficult to repair the
material by heat bonding. Therefore, limited data was collected on the underlying concrete beneath the
liner. Additional photos from the visual inspection can be found in Appendix C.
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Site
The Lyman reservoir site is accessed by a 15-foot-wide private gravel road that is approximately 1 mile
from Story Mill Road. The access road is generally in good condition with no major deficiencies. There
is a chain link security fence around the reservoir structure, however it does not enclose the inlet and
outlet control buildings. Barbed wire fencing and gates prevent unauthorized vehicular access to the
gravel drive down to the outlet control building. There are cameras outside of the buildings to provide
additional security monitoring for the relatively remote site that is periodically occupied by operations
staff.
Roof drains on the east side of the reservoir building pour
onto concrete pads which convey water to storm drain
inlets. Several of the storm drain manhole rims sit higher
than the concrete splash pad, preventing proper drainage.
Roof drains on the west side of the building pour onto
small splash pads and into a swale graded away from the
building. The site generally slopes to the south. Issues
with surface water collecting were not observed.
The floor of the outlet control building is three to five feet
below the adjacent grade, and the door is accessed by a
concrete stairwell with a retaining wall. Snow and water
collects in the bottom of the stairwell making it difficult to
safely access the building at times and has corroded the bottom of the door frame.
Reservoir Liner and Concrete
The 2004 improvements project which included the liner was approved by DEQ under EQ 02-2027 in
April of 2002. The project specifications, construction submittals, and record drawings indicate that the
existing liner is a 45-mil, scrim reinforced polypropylene geomembrane. The specifications call for the
liner to be manufactured by Cooley Engineering Membranes, Inc. or approved equal. The material
submittals indicate that the liner was manufactured by MPC Containment International, LTD. None of
these record documents indicate that the liner was required to have, or was supplied with, NSF 61
certification, however NSF-certified polypropylene geomembranes are widely available.
Northwest Linings and Geotextiles of Kent, WA was contracted to remove portions of the existing
polypropylene liner to allow investigation of the concrete beneath. Twelve specific locations were
chosen for removal of 3’x3’ sections of liner. The selected locations are shown on Figure 11 in
Appendix A.
Prior to removing the test sections, a piece of liner was removed above the high-water line near the top
of the vertical perimeter wall to verify the ability to bond the existing liner material to new liner patching
material. Northwest Linings performed numerous peel tests using varying amounts of heat and
pressure and the results were inconsistent. It was determined that removing liner from below the
normal water line would risk exacerbating leakage rates. Therefore, only one investigative cut was
made to expose the 1911 concrete approximately 4.5 feet below the top of the slope and above the
Figure 2-1: Storm Drain Inlet
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apparent normal operating water elevation. The concrete
exposed appeared to be just below the construction joint
between 1911 construction and 1957 construction as a joint
could be seen and felt when lifting up the liner and peering
inside. The apparent joint was about four feet below the top of
the slope, consistent with the 1957 record drawings. The
existing FabriNet geocomposite was also observed beneath the
liner.
Phenolphthalein testing for alkalinity and rebound hammer
testing to estimate strength were conducted at this single
location. The incision was repaired with a triple layered patch
and an air lance was used to verify adhesion of the top patch.
See the Structural Assessment Report in Appendix B for more
details about the results of these tests.
The surface of the existing liner, particularly below the normal
water level, exhibited a faded gray-blue discoloration that is
consistent with oxidative aging associated with long-term
exposure to chlorinated water. Additional indicators of material
aging were observed, including increased stiffness and loss of
flexibility, apparent shrinkage of the polymer coating resulting in
visible scrim telegraphing, and a reduced apparent thickness
compared to new 45-mil repair material. During repair activities,
the existing liner also did not melt or respond to heat welding in
a manner consistent with new liner material, suggesting
changes in the polymer's physical properties. Although
prolonged exposure to chlorine residuals may contribute to
oxidation and depletion of antioxidants within the polymer, material degradation also occurs naturally
with age. Given these observed conditions and the liner's age of nearly 25 years, the liner appears to
have reached the end of its useful service life.
Tight creases were observed throughout the surface of the liner. The internal scrim reinforcement can
be seen along the edges of the folds and could be a potential source of leakage. Many field welds and
caulk repairs were also observed. Minimal amounts of brown sediment were observed throughout the
reservoir.
The reservoir baffles are made of the same material as the liner and show signs of oxidation, although
their function does not appear to be affected. Because NSF 61 certification could not be verified, the
baffles should be replaced. The baffle hangers were inspected from reservoir floor and entrance and
appear to be in satisfactory condition from a distance. The tie down cables and chains show no
evidence of wear against the liner or baffles. Because the stainless-steel hardware is nearly 25 years
old, replacement should be considered during rehabilitation to help ensure it lasts for the life of the
project. Pictures of baffles and baffle hangers can be found in Appendix C.
Figure 2-2: 1911 Concrete
Figure 2-3: Liner Fold
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Reservoir Piping and Appurtenances
Inlet Piping
There was rust present on the flanges of the existing 16” DI inlet
piping, pipe stands and air relief valve. The concrete thrust block
at the bottom of the inlet pipe was covered with liner material
requiring many field seams. No signs of tuberculation on/in inlet
piping were observed.
Outlet Piping
There was damaged coating present on the 16” DI outlet piping
with some rust and tuberculation present. The flange adapter
transitioning from ductile iron to HDPE is embedded in concrete;
however, the exposed interior surfaces, including the stainless-
steel insert, appear to be in satisfactory condition.
Reservoir and Liner Drains
The existing 8” reservoir drain was partially visible beyond the
liner boot and appeared to be in satisfactory condition.
Numerous field seams and repairs were observed.
The existing 8” liner drain and slot drain were not visible for
inspection as they are located underneath the liner.
Figure 2-4: Reservoir Inlet
Figure 2-5: Reservoir Outlet
Figure 2-6 Reservoir Drain
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Reservoir Building
A visual inspection of the exposed foundation wall, undersides of the precast tri-decks, girders, bearing
hardware, parallel connections, and concrete columns was conducted. The reservoir building is
generally in satisfactory condition with some minor repairs needing attention. See the Structural
Assessment in Appendix B for more details about the condition of the reservoir building.
Treatment and Control Systems
The Inlet Control Building contains a pressure reducing valve that reduces the pressure entering the
building to about 20 psi. The building also contains a flow control valve, metering, liquid hypochlorite
injection (via two 500-gallon storage tanks), liquid fluoridation storage and pumping (via one 500-gallon
storage tank), reservoir inlet chlorine analyzer, reservoir outlet chlorine analyzer (piped from Outlet
Control Building), and a restroom. Downstream of the pressure-reducing valve, the 12-inch inlet pipe
bifurcates into two parallel flow paths that recombine immediately upstream of the flow control valve.
Each parallel flow path has two quills for chlorine injection. The existing radon stripping system is
currently not in use.
The Outlet Control Building is located below the reservoir embankment and consists of a supplemental
disinfection point, fluoride injection, flow and chlorine residual monitoring capabilities, and differential
pressure monitoring of the reservoir.
Leakage water collected by the liner drain passes through a dechlorination system before discharging
to the drainage ditch as authorized by MPDES permit MT0031631. The system doses liquid calcium
thiosulfate through a vault approximately 15 feet upstream of the drain pipe discharge.
The facilities were generally in good working order, however the following improvements were
identified:
Inlet Control Building
• Ventilation improvements are needed in the chemical room to improve exhaust louver function.
• Filling the chlorine and fluoride tanks is cumbersome. It is desired to add hard-piped
connections to the exterior of the building to fill tanks more efficiently and safely.
• If the City were to discontinue use of fluoride in the drinking water system at some point in the
future, the existing fluoride storage tank could be replaced with a third chlorine tank.
• Chlorine analyzer waste is routed to drain with a hose. A more permanent hard-piped solution
is desired.
• Chemical tank level sensors are problematic and are scheduled for replacement by operations
staff.
• The existing generator is inadequate for full electrical loads when heaters are running. The City
is in the process of replacing the generator with a larger unit.
• A means of bypassing the reservoir is desired for emergency use and to facilitate reservoir
maintenance.
Outlet Control Building
• The outlet flow meter is scheduled for replacement in FY 27/28.
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Predesign Report Alternatives Analysis
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• The stairs leading down to the building entrance are difficult to safely access in the winter. It
may be possible to regrade the area south of the building to provide drainage and safer access.
On-Site Wastewater Treatment System
According to GHCCD Permit #12172 issued in 2002, the existing septic system has a capacity of 203
gallons per day which included part-time operator and chlorine discharge analyzer water. The system
includes a 1,000-gallon septic tank and 500-gallon pump chamber which are located just south of the
inlet control building. The system pumps septic effluent to a 540 square foot pressure dosed drainfield
located approximately 220 feet to the northeast. The existing septic permit can be found in Appendix F.
Geotechnical Analysis
A geotechnical investigation was conducted by Allied Engineering Services Inc. The investigation
included drilling seven boreholes, producing soil profiles for each borehole, groundwater monitoring,
and analysis of eight leak scenarios to model slope stability of the existing embankment. See Figure 5
in Appendix A for a map of the borehole locations.
Four boreholes were drilled around the existing reservoir building; two within the embankment on the
southwest end of the reservoir, one along the northwest side, and one along the southeast side. Three
borings were drilled east of the existing reservoir at the potential location of a new reservoir.
Groundwater levels were monitored at each of the seven borehole locations and at an existing
monitoring well located at the northeast end of the reservoir. Boreholes were drilled between
November 10, 2025 and November 18, 2025. Groundwater monitoring started in November of 2025
and continued into the summer of 2026.
Figure 2-7: Groundwater Monitoring Levels
5000
5005
5010
5015
5020
5025
1/1/2026 2/1/2026 3/1/2026 4/1/2026 5/1/2026 6/1/2026
GROUNDWATER MONITORING LEVELS
MW-1 MW-2 MW-3 MW-4
MW-5 MW-6 EX-MW Reservoir Floor
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Predesign Report Alternatives Analysis
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Groundwater levels were measured at varying intervals with an increased frequency when the
reservoir was drained for inspection and initially put back into service as shown in Figure 2-7. When
the reservoir was emptied in late February, water levels in all of the surrounding wells dropped. The
reservoir was refilled in March with the drain valve closed to allow for disinfection of the reservoir. The
water levels increased rapidly in the surrounding wells, creating a mounded groundwater condition.
Monitoring wells 1, 2, and 3, which were drilled to depths of 38.5 to 50 feet were dry until the reservoir
was refilled. Groundwater levels began to drop when the drain valve was opened and rose again in
late April, typical of seasonal runoff. These observations strongly indicate that water leaking through
the liner is likely also leaking through the concrete slabs and influences groundwater levels around the
reservoir and embankment.
The slope stability analysis of the existing embankment fill section yielded acceptable factors of safety
under five different groundwater scenarios. These scenarios range from assuming groundwater levels
are below the reservoir floor in native subgrade soils to assuming water is leaking at the high level of
the reservoir and partially saturating the embankment fill section. Several scenarios with improved
embankment slopes were also analyzed but they did not significantly increase the factors of safety.
See Figure 6 in Appendix D for a summary of the slope stability analysis.
The analysis also provided recommendations for constructing a new reservoir. Due to variable bearing
soils, structural fill and ground improvement is recommended to minimize potential for differential
settlement. Ground improvement could include rammed aggregate piers or vibro stone columns.
The full geotechnical assessment report can be found in Appendix D.
2.2. OPERATIONS
The Lyman Reservoir sets the hydraulic grade line for the Northeast Pressure Zone (HGL 5038) which
is mostly built out but has some potential for minor infill. Water from this zone is transferred to the
South Pressure Zone (HGL 5125) via the Pear Street booster station, which underwent a
comprehensive renovation in 2020, including the replacement of all mechanical equipment, process
piping, valves, and control systems. It can also feed the Northwest Zone, if necessary, through PRV
facilities.
Existing Flow Data
Average daily flow from the Lyman Reservoir between 2020 and 2025 is shown in Figure 2-8 and
annual demand is summarized in Table 2-1. Reservoir inflow from Lyman Creek follows a similar trend
line and generally ranges from 700 gpm to 2,600 gpm. The Pear Street booster station wasn’t used
from late 2020 through late 2021 due to a main break on the discharge header outside of the building.
Otherwise, usage patterns have been relatively consistent in recent years and are largely dependent
on spring production. The general operating strategy is to maximize use of the Lyman spring source by
using the lesser of the maximum flow rate legally allowed by the City’s water rights or what is
physically available. Supply in excess of Northeast Pressure Zone demand is pumped to the South
Pressure zone for use throughout the rest of the system. The Average Daily Demand (ADD) and
Maximum Daily Demand (MDD) during this time period were 1.7 MGD and 3.8 MGD respectively.
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Figure 2-8: Average Daily Flow
Table 2-1: Annual Demand
Year ADD (gal) MDD (gal)
2020 1,854,171 3,787,413
2021 1,288,991 2,232,762
2022 1,569,810 3,624,291
2023 1,724,052 3,732,063
2024 1,865,783 3,757,216
2025 1,964,945 3,792,289
Average
2020-2025 1,711,292 3,487,672
Future Demands
The Lyman source is expected to continue supplying other pressure zones through the Pear Street
booster station. The 2017 Water Facility Plan Update projected Ultimate Build Out (UBO) demands for
the Northeast Pressure Zone of 0.6 MGD ADD and 1.6 MGD MDD. The plan also identified the Lyman
Reservoir site as a potential location for a second five-million-gallon reservoir and a pump station to
serve the North Mountain Zone; together, these facilities would help meet the projected systemwide
storage requirement of 72.3 million gallons.
Evaluating total system demands and siting of future storage is beyond the scope of this pre-design
project, however the potential for an additional reservoir at the site should be considered when
designing improvements to the existing reservoir or modifying the site.
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
3,500,000
4,000,000
1/1/2020 1/1/2021 1/1/2022 1/1/2023 1/1/2024 1/1/2025
Average Daily Flow From Lyman Reservoir
Daily Flow (gpd)
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CHAPTER 3 ALTERNATIVES ANALYSIS
3.1. GENERAL DESIGN PARAMETERS
In addition to information gathered during the condition assessment, the primary design parameters
that were used to develop the scope of each alternative are summarized in Table 3-1. All materials in
contact with potable water must be NSF 61 Certified or otherwise approved by DEQ. This would
include all materials of the underdrain system if recirculation of leakage water is desired to be a viable
option.
Table 3-1: General Design Parameters
Parameter Description Design Criteria
All Alternatives
Nominal Storage Volume 5 MG, minimum
Maximum Inflow 2,680 gpm
Rehabilitation
Geomembrane Liner Material Options
XR-PW
CSPE
HDPE
Geosynthetic Liner Quality Control
Air Pressure Testing (wedge weld seams)
Vacuum Testing (other seams)
Spark Testing (requires conductive underlayer)
Leak Testing Standard DEQ-2 94.422
New Reservoir
Tank Type AWWA D110 Type III Prestressed Concrete
Circular Tank
Maximum Working Water Depth 30 feet
Burial Partially Buried
Leak Testing Standard AWWA D110
ASTM C1719
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3.2. ALTERNATIVES DEFINITION
Six alternatives were evaluated, including rehabilitation of the existing reservoir using either a
geomembrane liner or concrete coating system, rehabilitation combined with construction of a new 1-
MG reservoir, and complete replacement of the existing reservoir.
• Alternative 1: Rehabilitate existing reservoir
• Sub-Alternative 1.1: Rehabilitate with new geosynthetic liner
• Sub-Alternative 1.2: Rehabilitate with concrete/coating system
• Alternative 2: Rehabilitate existing reservoir and construct additional 1 MG reservoir
• Sub-Alternative 2.1: Rehabilitate with new geosynthetic liner
• Sub-Alternative 2.2: Rehabilitate with concrete coating system
• Alternative 3: Construct new 5 MG reservoir at existing site
• Alternative 4: Construct new 5 MG reservoir and treatment at upgradient site
The major components included in each alternative are summarized in Table 3-2 and further described
below.
Table 3-2: Alternatives Summary
Alternative
Reservoir
Building
Repair
Reservoir
Concrete
Repair
Reservoir
Geomembrane
Liner
Reservoir
Coating
System
1 MG
D110
Tank
5 MG
D110
Tank
Decommission
Existing
Reservoir
New
Treatment
Facility Rehab 1.1
1.1 Combo 2.1
2.2 New Reservoir 3
4
3.2.1. Rehabilitation
Two methods of rehabilitation were explored. Both methods include repairs to the existing reservoir
building and existing reservoir concrete. The existing inlet control building, treatment system, and
outlet control building will continue to be used for all rehabilitation alternatives and the improvements
identified during the assessment will be made. New piping to bypass the existing reservoir will be
included so the source can be used during construction if needed. The geosynthetic liner alternative
includes installation of a liner system that is similar to the existing system except a liner material that is
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more compatible with the water quality of water held within the reservoir would be used. The concrete
coating system alternative includes sealing the reservoir with a spray-applied concrete coating.
Reservoir Building Repair
The reservoir building requires some minor structural repairs including removing rust from and
recoating steel components of the precast tri-decks bearing connection to the exterior walls and full
replacement of the steel components of the tri-decks parallel connections. A comprehensive
description of structural repair recommendations can be found in Appendix B – Lyman Structural
Assessment Report and is summarized as follows:
• Patch exposed aggregate on exterior foundation wall
• Apply new caulking to vertical expansion joints on exterior foundation wall
• Remove rust and recoat steel hardware for all tri-deck bearing connections
• Replace all tri-deck parallel connections
• Replace rusted open web steel roof joists in vestibules
Reservoir Concrete Repair
Once the liner is removed, the existing concrete beneath will be evaluated, spalling, cracking, and
joints will be repaired. Concrete repair is assumed to include the following items:
• Remove and dispose of existing liner and geocomposite
• Evaluate condition of concrete upon liner removal
• Repair all existing joints
• Repair all existing cracks
• Localized repairs of unsound concrete from ½” to 1” deep by removing concrete and patching
with repair mortar
• Replace sections of slabs as needed
Reservoir Geomembrane Liner System Replacement
Several liner materials that are compatible with chlorine at 5 ppm and commonly supplied with NSF 61
certification were evaluated for liner replacement. These materials include XR-PW, CSPE (Hypalon),
and HDPE. HDPE is the least cost material and can be provided with a conductive backing to facilitate
spark testing during construction to identify holes or leaks. However, HDPE has a very high thermal
expansion rate and is more rigid than the other materials which could result in wrinkling and/or
localized stress at fixed column penetrations and corners. XR-PW and CSPE are thermally stable and
highly flexible. Unlike HDPE, panels can be prefabricated in the factory and folded or rolled for
transport to reduce field welds. XR-PW is a thermoplastic alloy with a permanent thermoplastic matrix,
meaning that repairs can be made by heat welding indefinitely. CSPE is a thermoset elastomer which
is easy to weld when new but welding aged or “cured” material is difficult and requires surface grinding
and chemical preparation. CSPE is more costly than XR-PW and has superior resistance to UV and
high chemical concentrations. Spark testing is commonly used in wastewater applications where
identifying and preventing leakage is paramount but less common for potable water applications.
Installing a separate conductive layer below the liner could be considered if spark testing is desired for
identifying leaks to meet a performance specification.
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-12
XR-PW was used as the basis for cost estimating; however, the exact product should be selected
during final design in further consultation with liner manufacturers. The selected liner should be
suitable for continuous exposure to low levels of chlorine (approx. 5 ppm) and fluoride (approx. 1 ppm)
over the design life of the liner and periodic shock chlorination treatments (approx. 100 ppm to 200
ppm for 48 hours every 5 years). The liner system includes the following components:
• XR-PW3 geomembrane liner and new baffle walls/hangers
• Geocomposite layer below liner for liner protection and drainage
• Fabricated boots for drain pipe and outlet pipe
• Fabricated custom shapes for inlet pipe thrust block and drain sump
• Fabricated boots for columns extending above water level
• Batten bars to anchor top of liner
• Piping to bypass existing reservoir
• Liner underdrain will be maintained to prevent hydrostatic pressure from building up behind
liner and to prevent saturation of embankment should the liner leak
Reservoir Coating System
In addition to the reservoir concrete repair items noted above, the entire surface would be prepared for
application of a coating system. It is anticipated that a concrete surface profile (CSP) between 4 and 6
would be required. A high-performance elastomeric urethane coating system (CIM 1061 by C.I.M.
Industries) was used as the basis for cost estimating. This type of coating is NSF 61 certified, VOC
free, flexible, and capable of bridging cracks. Surface preparation, environmental conditions during
installation (namely moisture and humidity), and pipe penetration details are important considerations
for an effective liner system. The exact product, primer, application thickness, etc. should be selected
during final design. The coating system includes the following components:
• Concrete surface preparation (ICRI CSP 4-6)
• Seal pipe and column penetrations
• Install NSF 61 spray-applied concrete coating system
• Piping to bypass either reservoir
3.2.2. New Reservoir
A new reservoir for all applicable alternatives will be designed and constructed in accordance with the
provisions of AWWA D110 Standard for Wire or Strand Wound Circular Prestressed-Concrete Water
Tanks, Type III core wall, ACI 350, ACI 350.3, ASCE 7 and IBC. Additionally, the prestressed concrete
tank will be designed and constructed in accordance with Montana Department of Environmental
Quality Circular 1, Section 7.0.1 through 7.0.17. The new reservoir will have a concrete dome roof,
vent, roof hatch, guardrail interior ladder, exterior ladder with safety cage, roof sleeves, and manway.
The existing septic drainfield will be relocated to maximize separation.
1 MG Concrete Reservoir
Alternatives 2.1 and 2.2 consist of constructing a new one-million-gallon reservoir and rehabilitating the
existing reservoir. The purpose of the new reservoir would be to maintain use of the Lyman Creek
water source while providing some operational and emergency storage during rehabilitation of the
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-13
existing reservoir. This configuration would reduce the burden on the Sourdough WTP if conditions are
found during rehabilitation that extend the construction duration or if the rehabilitation takes place
during peak water use in summer months. These alternatives would also allow for continued use of the
water source when one of the reservoirs is taken out of service for maintenance in the future.
The new reservoir will have a diameter of approximately 80 feet and a total height of 30 feet.
Approximately 15 feet of the tank will be below grade and the outlet of the reservoir will be higher than
the inlet to the existing reservoir to allow treated water to flow through both reservoirs by gravity. The
piping and valves will allow for isolation of either reservoir. Under normal operations, the existing inlet
building flow control valve would be controlled by level in the new reservoir and a new flow control
valve between the two reservoirs would be controlled by level in the existing reservoir. A new one-
million-gallon reservoir includes the following major work items:
• Excavation, backfill, site grading, and final stabilization
• Rerouting of the existing gravel access road around the tank
• Ground improvement and structural fill below tank foundation
• 1 MG D110 tank and appurtenances
• Inlet and outlet piping, isolation valves, and flow control valve
• Overflow and drain piping to existing outlet ditch
• Piping to bypass existing reservoir
• Relocation of existing drainfield
5 MG Concrete Reservoir at Existing Site
Alternative 3 consists of constructing a new five-million-gallon reservoir and decommissioning of the
existing reservoir. The reservoir could be constructed prior to decommissioning the existing reservoir.
The existing inlet control building and treatment system will continue to be used.
The new reservoir will have a diameter of approximately 170 feet and a height of 30 feet. Alternative 3
set the burial depth at approximately 4 feet to minimize excavation excess material hauling costs. The
burial depth of the reservoir should be evaluated during final design to balance the cost of excavation
and removal of excess materials with the visible height of reservoir. A new five-million-gallon reservoir
includes the following major work items:
• Excavation, backfill, site grading, and final stabilization
• Rerouting of the existing gravel access road around the tank
• Ground improvement and structural fill below tank foundation
• 5 MG D110 tank and appurtenances
• Inlet and outlet piping and isolation valves
• Overflow and drain piping to existing outlet ditch
• Relocation of existing drainfield
5 MG Concrete Reservoir at Upgradient Site
Alternatives 4 consists of constructing a new five-million-gallon reservoir at an upgradient site that
matches the hydraulic grade line of the South Pressure Zone (HGL 5125) and decommissioning of the
existing reservoir. The upgradient site is on a parcel owned by the City of Bozeman and is
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-14
approximately one mile north of the existing site. Utilities and an access road to the site do not exist
and will need to be constructed. New inlet and outlet control facilities and a treatment system will also
need to be constructed. This alternative assumes the existing transmission main will convey raw water
from the spring intake to the new site and treated water from the new site to the distribution system,
unless a new pipeline is constructed under a separate project.
The impacts of increased system pressures on the aging transmission and distribution piping
downstream of the reservoir were not evaluated as part of this study. However, Alternative 4 assumes
that PRV No. 2 in the spring supply line would be removed and that additional pressure-reducing
facilities would be required to maintain acceptable pressures within the Northeast Pressure Zone while
delivering the higher hydraulic grade line necessary to serve the South Pressure Zone.
A new five-million-gallon reservoir at the upgradient site includes the following major work items:
• Excavation, backfill, site grading, and final stabilization
• 5,600 feet of new access road and electrical supply
• Inlet/outlet control building and treatment system
• Ground improvement and structural fill below tank foundation (assumed)
• 5 MG D110 tank and appurtenances
• Inlet and outlet piping and valves
• Septic drainfield
• Removal of PRV No. 2 in spring supply pipe
• Additional PRV facilities in Northeast Pressure Zone
3.3. ALTERNATIVE COSTS
The cost-effectiveness of an alternative is determined via life-cycle cost analysis, or monetary present
value analysis. This is often the single most important comparison parameter. This economic
comparison includes estimated project (capital) cost expenditures and annual operation and
maintenance (O&M) costs.
Capital cost estimates are based on prices of comparable work obtained from recent sources. Costs
for contingency and technical services (i.e. engineering and construction administration) were included
as non-construction costs. Engineering was estimated to be 25% of construction costs. For practical
purposes, salvage value at the end of the 50-year evaluation period will be zero although some assets
may have useful life remaining. The final project costs will vary from the estimates presented herein.
Project feasibility, benefit/cost ratios, risk, and funding needs must be carefully reviewed prior to
making specific financial decisions or re-establishing project budgets to help ensure proper project
evaluation and adequate funding.
3.3.1. Capital Cost – Construction
For estimating capital construction costs, prices of comparable work were obtained from several
sources. Budgetary quotes were requested from material suppliers and contractors. Other costs were
based on similar recent projects in the region including recent bid tabulations. Ancillary facilities and
other more detailed project components were not detailed but rather included with other line items or in
the contingency. Costs presented in this PER are in 2026 dollars.
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-15
3.3.2. Capital Cost – Non-Construction
Two general categories are included for non-construction costs: 1) contingency and 2) engineering. A
percentage of the construction cost is utilized to estimate these cost categories.
• Contingency: A project contingency of 20% of the construction cost is estimated at this
planning level, with the exception of the alternatives involving rehabilitation which have a 25%
contingency due to increased uncertainty of the underlying concrete condition.
• Engineering: Engineering costs are contracted services with an engineering consultant.
Engineering services primarily include project design, permitting, advertising/bidding,
construction observation, construction management, project startup, record drawings, operation
and maintenance manuals, warranty inspections, and project closeout. For project budgeting,
25% of the construction cost plus contingency cost above is estimated for engineering services.
3.3.3. Life-Cycle Costs
Annual O&M costs are generally expected to be relatively similar among the evaluated alternatives.
These costs are therefore not included in life-cycle cost estimates but are described below for
reference. The total life-cycle cost for the alternatives will be primarily driven by the timing and
magnitude of major repair and replacement expenditures. An annual inflation rate of 4.2% is assumed
for future costs. Projects that require financing assume a 20-year repayment period at an interest rate
of 2.5%. The following assumptions were used to estimate life-cycle costs for each alternative:
Alternative 1.1
• Initial Project:
o Initial project as described. Project is financed.
• Roof Replacement:
o Reservoir building roof membrane replaced in 20 years. Replacement is paid for upfront
and is not financed.
• Reline Project:
o Geomembrane liner is replaced after 25 years. Liner replacement includes similar
scope items as initial project. Project is financed.
• Maintenance:
o Every 3-5 years. Drain and clean tank and inspect liner for deficiencies. In particular,
inspect pipe penetrations, field fabricated components, and seams. Perform spot
repairs as needed.
o Every 10 years. Drain and clean tank and perform detailed inspection. Perform spot
repairs as needed.
Alternative 1.2
• Initial Project:
o Initial project as described. Project is financed.
• Roof Replacement:
o Reservoir building roof membrane replaced in 20 years. Replacement is paid for upfront
and is not financed.
• Recoating Project:
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-16
o Concrete coating is replaced after 25 years. Coating replacement includes similar scope
items as the initial project. Project is financed.
• Maintenance:
o Every 3-5 years. Drain and clean tank and inspect coating for holidays, cracking,
blistering, etc. In particular, inspect pipe penetrations and corners. Perform spot repairs
as needed.
o Every 10 years. Drain and clean tank and perform detailed inspection. Perform spot
repairs as needed.
Alternative 2.1
• Initial Project:
o Initial project as described. Project is financed.
• Roof Replacement:
o Reservoir building roof membrane replaced in 20 years. Replacement is paid for upfront
and is not financed.
• Reline Project:
o Geomembrane liner in existing reservoir is replaced after 25 years. Coating
replacement includes similar scope items as the current alternative. Project is financed.
• Renewal Project:
o Renewal project on new reservoir to reapply coating, seal joints, and replace
accessories after 25 years. Project is financed.
• Maintenance
o Every 3-5 years. Drain and clean tank and inspect liner for deficiencies. In particular,
inspect pipe penetrations, field fabricated components, and seams. Perform spot
repairs as needed.
o Every 10 years. Drain and clean tank and perform detailed inspection. Perform spot
repairs as needed.
• New concrete tank useful life in excess of 50 years.
Alternative 2.2
• Initial Project:
o Initial project as described. Project is financed.
• Roof Replacement:
o Reservoir building roof membrane replaced in 20 years. Replacement is paid for upfront
and is not financed.
• Recoating Project:
o Concrete coating in existing reservoir is replaced after 25 years. Coating replacement
includes similar scope items as the initial project. Project is financed.
• Renewal Project:
o Renewal project on new reservoir to reapply coating, seal joints, and replace
accessories after 25 years. Project is financed.
• Maintenance
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-17
o Every 3-5 years. Drain and clean tank and inspect coating for holidays, cracking,
blistering, etc. In particular, inspect pipe penetrations and corners. Perform spot repairs
as needed.
o Every 10 years. Drain and clean tank and perform detailed inspection. Perform spot
repairs as needed.
• New concrete tank useful life in excess of 50 years.
Alternative 3
• Initial Project:
o Initial project as described. Project is financed.
• No additional replacement projects.
• Renewal Project:
o Renewal project to reapply coating, seal joints, and replace accessories required after
25 years. Project is financed.
• Maintenance
o Every 3-5 years. Drain and clean tank and inspect. In particular, inspect pipe
penetrations and corners. Perform spot repairs as needed.
o Every 10 years. Drain and clean tank and perform detailed inspection. Perform spot
repairs as needed.
Alternative 4
• Initial Project:
o Initial project as described. Project is financed.
• No additional replacement projects
• Renewal Project:
o Renewal project to reapply coating, seal joints, and replace accessories required after
25 years. Project is financed.
• Maintenance
o Every 3-5 years. Drain and clean tank and inspect. In particular, inspect pipe
penetrations and corners. Perform spot repairs as needed.
o Every 10 years. Drain and clean tank and perform detailed inspection. Perform spot
repairs as needed.
Lyman Reservoir Chapter 3
Predesign Report Alternatives Analysis
Page 3-18
3.3.4. Estimated Alternative Costs
The estimated costs for each alternative are summarized in Table 3-3 which includes capital construction
costs, non-construction costs, and 50-year life-cycle costs. Additional cost estimate details can be found
in Appendix E.
Table 3-3: Estimated Alternative Costs
Alternative Description Construction
Cost (2026)
Non-
Construction
Cost (2026)
Total Project
Cost (2026)
50-Year Life
Cycle Cost
Rehabilitation Only
Alternative 1.1 Rehabilitate with new
geosynthetic liner $3,238,704 $809,676 $4,048,380 $21,118,377
Alternative 1.2
Rehabilitate with
concrete/coating
system
$4,171,504 $1,042,876 $5,214,380 $26,798,359
Rehabilitation with Additional 1 MG Storage
Alternative 2.1 Rehabilitate with new
geosynthetic liner $7,727,340 $1,931,835 $9,659,175 $28,586,508
Alternative 2.2
Rehabilitate with
concrete coating
system
$8,658,890 $2,164,722 $10,823,612 $33,875,449
New 5 MG Storage
Alternative 3 new 5 MG reservoir at
existing site $9,820,165 $2,455,041 $12,275,207 $25,855,315
Alternative 4
new 5 MG reservoir
and treatment at
upgradient site
$14,855,426 $3,713,857 $18,569,283 $33,930,253
Lyman Reservoir Chapter 4
Predesign Report Alternatives Selection
Page 4-1
CHAPTER 4 ALTERNATIVES EVALUATION
Alternatives were assessed based on project cost and non-monetary factors such as schedule,
constructability, operational ease, and future system compatibility. Comparative parameters were
weighed according to importance with input from City operators and engineers. Alternative scores of 1
to 5 were assigned for each ranking criterion for each alternative. Resulting composite scores were
summed for each alternative for an overall score.
The proposed alternatives for Lyman Reservoir Improvements were evaluated based on the following
ranked criteria:
Cost Effectiveness – 5
• Project and life-cycle costs were considered as the most important decision-making tool in the
comparison between alternatives that are exclusive of others.
Schedule – 5
• The reservoir is currently leaking at an excessive rate which could affect the City’s ability to store
adequate water during periods of low spring supply and high demand. A high priority is placed
on how quickly water loss can be resolved.
Constructability/Risk – 4
• The effect that each alternative will have on the City’s ability to operate the Lyman water during
construction is important to consider. Additionally, the rehabilitation options have increased risks
associated with the unknown condition of the existing concrete.
Operational Ease – 3
• Each alternative will have a similar process for treatment and controls, however there will be
additional operational complexities for alternatives that have multiple tanks or are located further
from the existing facility.
Future System Compatibility – 2
• The 2017 Water Facility Plan Update identified the Lyman site as a location for additional future
storage. City does not have imminent plans to increase storage at this site, however the ability
to do so is considered for each alternative.
4.1. ALTERNATIVES EVALUATION
Based on the alternatives analysis and life-cycle cost evaluation, the following summarizes the primary
advantages and disadvantages of each alternative.
4.1.1. Alt 1.1 Rehab Existing Reservoir with New Geomembrane Liner
Advantages
• Lowest initial project cost of all alternatives.
• Lowest 50-year life-cycle cost.
• Retains existing 5 MG storage volume and current operations.
• Utilizes existing treatment facilities and site infrastructure.
• Shorter implementation schedule than constructing a new reservoir.
• Modern liner materials offer improved performance and NSF 61 compliance.
Lyman Reservoir Chapter 4
Predesign Report Alternatives Selection
Page 4-2
• Minimal site disturbance compared to new reservoir construction and maintains existing site
aesthetics.
Disadvantages
• Relies on a 100+ year old concrete reservoir with uncertain underlying condition.
• Concrete condition cannot be fully assessed until project is under construction.
• Potential for unforeseen repair costs and schedule delays during construction.
• Requires another liner replacement at approximately 25 years.
• Continued dependence on a buried liner system with seams, penetrations, and appurtenances.
• Does not add redundancy or additional storage capacity.
• The existing reservoir structure is unique and may require deviation(s) from Circular DEQ-1
during the permitting process.
• Operating the bypass line while the reservoir is out of service could be challenging.
4.1.2. Alt 1.2 Rehab Existing Reservoir with Concrete Coating System
Advantages
• Preserves the existing 5 MG storage volume.
• Utilizes existing treatment facilities and site infrastructure.
• Eliminates dependence on a geomembrane liner system.
• Coating system is NSF 61 certified, flexible, crack-bridging, and VOC-free.
• Minimal site disturbance compared to new reservoir construction and maintains existing site
aesthetics.
Disadvantages
• Higher capital and life-cycle costs than Alternative 1.1.
• Increased dependency on the condition of the existing concrete structure over Alternative 1.1.
• Requires extensive surface preparation (CSP 4-6) and environmental control during
installation.
• Performance dependent on concrete substrate condition and crack repair quality.
• Coating replacement anticipated after approximately 25 years.
• Does not add redundancy or additional storage capacity.
• The existing reservoir structure is unique and may require deviation(s) from Circular DEQ-1
during the permitting process.
• Operating the bypass line while the reservoir is out of service could be challenging.
4.1.3. Alt 2.1 Rehab Existing Reservoir with Geomembrane Liner + New 1 MG
Reservoir
Advantages
• Provides additional one million gallons of operational and emergency storage.
• Reduces dependence on Sourdough WTP during rehabilitation.
• Improves redundancy and operational flexibility.
Lyman Reservoir Chapter 4
Predesign Report Alternatives Selection
Page 4-3
• Maintains source availability when either reservoir is out of service for maintenance.
Disadvantages
• More costly than Alternative 1.1 and 1.2.
• Retains uncertainty and risk associated with rehabilitating the old structure.
• More complex operations with two reservoirs and additional controls.
• Requires future liner replacement in the rehabilitated reservoir.
• Longer construction duration and greater site impacts than Alternative 1.1.
• Construction of the new reservoir likely couldn’t begin until 2028.
• The existing reservoir structure is unique and may require deviation(s) from Circular DEQ-1
during the permitting process.
4.1.4. Alt 2.2 Rehab Existing Reservoir with Coating System + New 1 MG
Reservoir
Advantages
• Provides additional one million gallons of operational and emergency storage.
• Reduces dependence on Sourdough WTP during rehabilitation.
• Improves redundancy and operational flexibility.
• Maintains source availability when either reservoir is out of service for maintenance.
Disadvantages
• Highest capital cost among alternatives that retain the existing reservoir.
• Retains uncertainty and risk associated with rehabilitating the old structure.
• More complex operations with two reservoirs and additional controls.
• Requires future coating replacement cycles.
• Longer construction duration and greater site impacts than Alternative 1.1.
• Construction of the new reservoir likely couldn’t begin until 2028.
• The existing reservoir structure is unique and may require deviation(s) from Circular DEQ-1
during the permitting process.
4.1.5. Alt 3 New 5 MG Reservoir at Existing Site
Advantages
• Eliminates reliance on the old concrete reservoir structure.
• Existing reservoir could be preserved for future rehabilitation or replacement to double storage
at the site.
• Lowest construction risk and uncertainty.
• New AWWA D110 prestressed concrete reservoir with expected useful life exceeding 50 years.
• No future liner replacement project required.
• Maintains existing site, treatment system, and hydraulics.
Lyman Reservoir Chapter 4
Predesign Report Alternatives Selection
Page 4-4
• Reservoir can be constructed before decommissioning the existing facility, reducing operational
impacts.
• High constructability/risk score because it avoids rehabilitation uncertainties.
Disadvantages
• Capital cost greater than Alternative 1.1 and 1.2.
• Requires significant excavation, ground improvement, and site work.
• Visible above-grade structure may present aesthetic concerns depending on final burial depth.
• Does not add redundancy or additional storage capacity.
• Requires decommissioning and potentially preservation of the existing reservoir.
4.1.6. Alt 4 New 5 MG Reservoir and Treatment at Upgradient Site
Advantages
• New reservoir with expected service life exceeding 50 years.
• Provides hydraulic grade line compatible with the South Pressure Zone which could eliminate
the need for the Pear Street booster station.
• Eliminates dependence on the existing reservoir structure.
• High constructability/risk score because it avoids rehabilitation uncertainties.
Cons
• Highest project cost and highest life-cycle cost.
• Requires approximately 5,600 feet of new road and electrical infrastructure.
• Requires entirely new treatment and control facilities.
• Requires additional pressure reducing facilities in the Northeast Pressure Zone.
• Potential impacts on existing transmission and distribution piping were not evaluated.
• Furthest location from current facilities, increasing travel for operators and chemical deliveries
and additional snow removal costs.
• Longest implementation schedule and greatest permitting/site-development effort.
4.1.7. Key Takeaways
• Alternative 1.1 (rehabilitation with new geomembrane liner) provides lowest initial and life-cycle
costs, shorter schedule, and compatibility with future system planning.
• Alternative 3 (new 5 MG reservoir at the existing site) is the strongest long-term solution from a
risk and asset reliability perspective because it removes uncertainty associated with the aging
historic reservoir.
• The Alternative 2 options provide additional redundancy and operational flexibility but at a
significant cost premium while still retaining the risks of rehabilitating the existing reservoir.
• Alternative 4 offers potential hydraulic benefits but is difficult to justify economically unless
there is a larger future system strategy that benefits from relocating storage to a higher
elevation.
Lyman Reservoir Chapter 4
Predesign Report Alternatives Selection
Page 4-5
4.1.8. Alternative Rankings
Table 4-1 summarizes the rankings for each alternative based on the criteria described above.
Table 4-1: Alternative Rankings
Comparison
Parameter
Parameter
Weight Alternative 1.1 Alternative 1.2 Alternative 2.1 Alternative 2.2 Alternative 3 Alternative 4 Cost Effectiveness 5 5 4 3 2 4 2
Schedule 5 5 5 3 3 3 2
Constructability/Risk 4 3 2 4 3 5 5
Operational Ease 3 5 5 4 4 5 4
Future System
Compatibility 2 5 5 4 4 5 5
Weighted Rank
Total: 87 78 66 57 80 62
CHAPTER 5 RECOMMENDATIONS
This chapter presents recommendations for reservoir improvements that consider prioritization of
needs, costs, and feasibility.
5.1. PREFERRED ALTERNATIVE
Alternative 1.1 (rehabilitation with new geomembrane liner) is the preferred alternative. Similar to
Alternative 1.2, this provides the shortest schedule and maximizes the use of existing infrastructure.
However, Alternative 1.1 provides the lowest initial and life-cycle costs and is expected to be more
forgiving with the aged concrete structure than a concrete coating. It also maintains the liner drain
which minimizes saturation of the reservoir embankment and provides an opportunity to identify future
leaks if and when they occur.
5.2. PROPOSED PROJECT
The anticipated scope of Alternative 1.1 is summarized below and shown in Figure 6 in Appendix A.
5.2.1. Anticipated Project Scope
Site
• Install security fence to enclose inlet and outlet control buildings
• Improve drainage along east side of reservoir building
• Return access road and parking area to pre-existing condition following construction
Inlet Control Building
• Chemical room ventilation improvements
• Chemical tank fill pipe improvements
• Chlorine analyzer waste pipe improvements
• Construct reservoir bypass piping
Outlet Control Building
• Building entrance access and drainage improvements
Reservoir Building Repair
• Patch exposed aggregate on exterior foundation wall
• Apply new caulking to vertical expansion joints on exterior foundation wall
• Remove rust and recoat steel hardware for all tri-deck roof bearing connections
• Replace all tri-deck roof parallel connections
• Replace rusted open web steel roof joists in vestibules
Reservoir Concrete Repair
• Remove and dispose of existing liner and geocomposite
• Evaluate condition of concrete upon liner removal
• Repair all existing joints
• Repair all existing cracks
• Perform localized repairs of unsound concrete up ½” to 1” depth by removing concrete at
patching with repair mortar
• Replace sections of slabs with unsound concrete greater than 1” depth
Reservoir Geomembrane Liner System Replacement
• Install new geocomposite layer below liner for liner protection and drainage
• Consider installing conductive layer directly below liner to facilitate spark testing
• Install new geomembrane liner, baffle walls, and hangers
• Install new fabricated boots for drain pipe and outlet pipe
• Install new fabricated custom shapes for inlet pipe thrust block and drain sump
• Install new fabricated boots for columns extending above water level
• Install new batten bars to anchor top of liner
• Implement leakage testing during construction. Consider maintaining existing discharge permit
for a period of time and periodically monitor for leaks.
5.3. CONCLUSION
Alternative 1.1, Rehab Existing Reservoir with New Geomembrane Liner, is the recommended
alternative for the Lyman Reservoir Improvements Project. This alternative provides the lowest initial
project cost and lowest 50-year life-cycle cost while maintaining the existing five-million-gallon storage
volume and maximizing use of the City's existing infrastructure. The alternative can also be
implemented more quickly than construction of a new reservoir and minimizes site disturbance, making
it a practical near-term solution for reducing ongoing water loss from the reservoir.
The primary disadvantage of Alternative 1.1 is the uncertainty associated with the condition of the
underlying concrete structure, which cannot be fully evaluated until the existing liner is removed. As a
result, unforeseen concrete repairs may increase project costs or extend the construction schedule.
Additionally, the rehabilitation alternative retains reliance on a geomembrane liner system. Although
modern liner materials and installation practices are expected to provide improved performance, the
existing liner experienced leakage throughout much of its service life.
Despite these limitations, the significant cost savings relative to new reservoir construction and ability
to implement the project quickly, support rehabilitation as the most cost-effective and practical
alternative at this time. The recommended improvements will extend the useful life of the facility,
reduce leakage, maintain operational flexibility, and preserve the potential for future storage expansion
at the Lyman site if additional capacity is needed.
APPENDIX A
Exhibits
APPENDIX B
2026 Structural Assessment
1
To: Brian Heaston, City of Bozeman
From: Nate Menuez, PE
Date: March 3, 2026
Job No.: 0417.100
RE: Lyman Creek Reservoir Structural Assessment
CC: James Nickelson, PE, Brad Hammerquist, PE
Urgent For Review Please Comment Please Reply For Your Use
This memorandum documents the findings of a structural assessment conducted by Morrison-
Maierle at the Lyman Reservoir on March 2 and 3, 2026. The concrete reservoir, constructed
around 1889, has seen several modifications and improvements over time. All modifications and
improvements have stayed consistent with a structural concrete approach. Morrison-Maierle was
tasked with performing a limited, visual observation of the existing concrete structural elements
of the Reservoir.
The evaluation included the following structural elements and associated conditions:
· Exterior concrete foundation walls above grade.
· Vertical expansion joints and joint sealant/caulking.
· Precast concrete tri-deck roof system (underside visible).
· Precast concrete girders supporting the roof.
· Interior circular concrete columns.
· Steel bearing connections between tri-decks and exterior walls.
· Steel parallel connection hardware associated with tri-decks.
· Existing 6-inch concrete slab-on-grade beneath the liner.
· Steel-framed vestibule structure on the south side of the reservoir.
· Steel roof deck and open-web steel joists within the vestibule.
2
Lyman Creek Reservoir Structural
Assessment
The exterior concrete foundation wall was visible above finish grade level. The exterior concrete
wall condition is satisfactory. There are several areas where minor surface deterioration has
occurred and aggregate has been exposed, requiring patching. In addition, the caulking that was
used in the vertical expansion joints has shrunk and cracked and needs replacement. See Photo
A.
Photo A – Exterior building concrete foundation
3
Lyman Creek Reservoir Structural
Assessment
The bottom of precast concrete tri-decks and precast concrete girders were visible from inside
of the tank. These structural elements are in satisfactory condition. The tops of the tri-decks
were not visible due to the roof membrane. The interior concrete circular columns, supporting
the girders, are also in satisfactory condition.
The steel components of the bearing connection of the precast concrete tri-decks to the exterior
wall are beginning to rust. Efforts will be required to clean existing rust and recoat all steel
hardware. In addition, the steel components of the parallel connections to the tri-decks have
rusted through and a full replacement will be required. See Photos B and C.
Photo B – Precast concrete tri-deck bearing condition
4
Lyman Creek Reservoir Structural
Assessment
Photo C – Precast concrete tri-deck parallel connection
5
Lyman Creek Reservoir Structural
Assessment
There are small steel stud framed vestibules on the north and south sides of the reservoir. The
vestibule roof framing is a steel metal deck supported by steel open web joists. The exposed
area of the open web steel joists have significant rusting, reducing their structural capacity. The
vestibule roof framing will have to be revised. See Photo D
Photo D – Rusted open web steel joists
6
Lyman Creek Reservoir Structural
Assessment
The existing 6” slab on grade was accessed by cutting a small hole in the liner about 4.5 feet
from the top of the sloped slab near the south vestibule. The concrete exposed appeared to be
just below the construction joint between 1911 construction and 1957 construction as a joint
could be seen and felt when lifting up the liner and peering inside. The apparent joint was about
four feet below the top of the slope, consistent with the 1957 record drawings. The original plan
was to cut the liner at multiple locations to obtain additional data on the concrete’s condition;
however, because the existing liner material was difficult to weld successfully, testing was limited
to a single location. Minor cracking, slight deterioration, water staining, and signs of minor
spalling could be seen, but these signs of wear do not appear to warrant major concerns
structurally. The concrete slab on grade appeared to be in surprisingly good condition given its
age.
The alkalinity of the concrete foundation was tested at the exposed location using carbonation
testing with a phenolphthalein solution. In general, concrete is highly alkaline, and the alkalinity
of the concrete reacts with the reinforcing steel to create an oxide film layer that protects the
steel from corrosion. As concrete ages, carbon dioxide reduces the pH of the concrete starting
at the face and working inward toward the reinforcing steel. Once the extent of the reaction
reach the reinforcing steel, the oxide film layer may become compromised, leaving the
reinforcing steel vulnerable to corrosion. The phenolphthalein indicator works by turning
pink/purple when in contact with high pH concrete (pH>10) and showing no color change when
in contact with low pH (<10) concrete. The exposed location was selected for carbonation
testing as the concrete must be scratched/chipped to view the results. The results of the
carbonation testing on the slope slab on grade of the reservoir were positive, by changing to a
pink/purple color, indicating that the concrete has maintained its alkaline state and is
considered to be in acceptable condition. See Photo E.
An additional task was to use a rebound hammer to estimate strength of the existing slab-on-
grade. A rebound hammer (or Schmidt hammer) is a portable, non-destructive testing
instrument used to evaluate the surface hardness and estimate the compressive strength of
hardened concrete. It works by measuring the rebound distance of a spring-driven mass after it
impacts the concrete surface, providing a quick, in-situ assessment of structural uniformity. The
results of the rebound hammer testing indicated the estimated concrete strength to be 3,000 to
3,800 psi. This is an acceptable result for concrete strength of the existing slab.
7
Lyman Creek Reservoir Structural
Assessment
Photo E – Phenolphthalein testing
APPENDIX C
2026 Condition Assessment Photos
Figure 1, Roof Down Spout and Splash Pad
Figure 2, Corroded Concrete Tri-Deck Parallel Connection
Figure 3, Vestibule Open Web Steel Joists
Figure 4, Inlet Pipe and ARV
Figure 5, Inlet Pipe
Figure 6, Exterior Building Foundation Aggregate Exposure
Figure 7, Existing EPDM Roof Membrane
Figure 8, Existing Wall Liner (oxidation appears as white residue)
Figure 9, Existing Wall Liner (oxidation appears as white residue)
Figure 10, Existing Floor Liner (oxidation appears as white residue)
Figure 11, Existing Floor Liner Fold
Figure 12, Test Welding Existing Liner Material
Figure 13, Existing Liner Material Test Weld
Figure 14, Existing Liner Material Enlarged Test Weld
Figure 15, Existing Liner Material Test Extrusion Weld
Figure 16, Existing Liner Material Failed Extrusion Weld
Figure 17, Existing Concrete – 1957 Reservoir Expansion Below Vertical Wall
Figure 18, Column Boot Caulk Failure
Figure 19, Existing Liner Crease with Internal Scrim Exposure
Figure 20, Caulk Repair Failure
Figure 21, Existing Liner Crease with Internal Scrim Exposure
Figure 22, Test Patch Above Normal Waterline
Figure 23, Polypropylene Patch on Tank Floor
Figure 24, Investigative Cut - 1911 Expansion Concrete
Figure 25, Phenolphthalein Test Results
Figure 26, Investigative Cut Location Relative to Existing Bar Work
Figure 27, Northwest Linings Patching Investigative Cut
Figure 28, Investigative Cut Patch
Figure 29, Northwest Linings Air Lancing Patch
Figure 30, Existing Baffles and Hangers
APPENDIX D
Geotechnical Assessment Report
July 30, 2026
James Nickelson
Brad Hammerquist
Morrison Maierle
2880 Technology Blvd. W.
Bozeman, MT 59718
e-mail: jnickelson@m-m.net (Sent via email only)
bhammerquist@m-m.net
Re: AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Dear Mr. Nickelson and Mr. Hammerquist:
This letter with attachments is provided as our AESI pre-design geotechnical assessment report for the
Lyman Reservoir project site, located in the foothills of the Bridger Mountains on the northeast side of
Bozeman, MT. It presents a detailed summary of our work, findings, results, and recommendations.
This report is based our understanding of the project alternatives, review of old plans and reports,
correspondence with Morrison Maierle and City to Bozeman staff, our knowledge of the site geology,
our geotechnical investigation of the project site via seven boreholes, groundwater monitoring of eight
monitoring wells (including one existing well), lab testing of select soil samples, and an extensive slope
stability analysis of the embankment fill section on the downslope side of the existing reservoir (under
eight different scenarios). The three main purposes of our geotechnical work were to measure ground-
water conditions prior to, during, and following the emptying and re-filling of the existing reservoir in
February/March 2026, to evaluate the current stability of the existing reservoir embankment fill section
under static and seismic conditions, and to assess the foundation bearing conditions for a new concrete
tank and provide preliminary geotechnical recommendations for foundation design, foundation support,
and foundation improvement (for cost estimating purposes of this project alternative).
This report serves as a planning document with preliminary foundation-related recommendations for a
new concrete tank, which is being considered at an adjacent on-site location on the east/southeast side
of the existing reservoir. It is important to understand this report does not provide all the necessary
geotechnical recommendations for the future design/construction of a new tank. As part of our work,
we drilled four boreholes in the general area of the proposed, new tank site. Depending on the final
design, location, and depth of a new tank, additional borings may be required. Assuming the new tank
alternative is selected, we recommend that a final geotechnical report be prepared during final design.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 2
PROJECT LOCATION
The Lyman Reservoir site is an existing City of Bozeman water storage facility located within the upland
terrain on the south end of the Bridger Mountain Range. It lies on the lowermost flank of the range and
just upslope of the valley floor. The site location is approximately 0.75-miles north of Bridger Drive/
Bridger Canyon Road and it is accessed via a private roadway that heads east of the intersection of Story
Mill Road and McIlhattan Road for about 1.0-mile (up to the reservoir location).
EXISTING LYMAN FACILITY
The main component at the Lyman facility is a large, rectangular, old concrete reservoir that was built
over a hundred years ago and has been in service ever since. Over the years, some improvements have
been made to the reservoir, including vertical side wall extensions, a new roof, interior column supports
for the new roof, a reinforced polypropylene liner (on the inside of the reservoir), and an interior drain
system between the exterior concrete shell and the liner (that is valved and daylighted to drain). The
purposes of the drain system are to 1) collect any groundwater that gets though the old concrete shell
(from below); and to 2) collect any stored water that gets through the liner (from above). Other existing
infrastructure at the facility includes an operations/treatment building and inlet, outlet, and drain piping
that connects the reservoir. See Figures 1 through 4 for an aerial image of the existing site conditions.
The existing reservoir was constructed in the bottom of a drainage that cuts through the project site.
The reservoir extends to a depth of approximately 30 to 33 feet below existing grades (depending on the
location) and consists of a rectangular floor slab and four, sidewall slabs that have a slope of 1.5H:1V. In
more recent years, vertical concrete wall extensions were added to the top of the reservoir shell around
all four sides. This work was done in conjunction with the addition of the new roof.
Since the reservoir was built within a surface drainage, the downslope (southwest) side of the reservoir
is buttressed by a large embankment fill section (that was placed to “fill the drainage” up to the top of
the reservoir). The embankment fill section extends the full width of the reservoir, is approximately 56
feet wide at the crest, has a 1.57H/1V side slope configuration along its downslope face, and ranges in
height from 21 to 25 feet (depending on location; and based on the topographic survey and borehole
findings). See Figures 5 and 6 for an as-built cross section of the embankment fill section geometry and
the downslope end of the reservoir. As shown on these figures, the bottom of the reservoir extends
about 6.0 feet below the bottom of the embankment fill (where it is 25 feet tall); but extends deeper
where the embankment fill height is closer to 21 to 22 feet.
PROJECT ALTERNATIVES
Per the project RFP for pre-design services, three alternatives are being considered for water storage
improvements at or near the existing Lyman facility. These include:
• Alt. 1: Leave the existing reservoir in service and make any necessary/needed improvements.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 3
• Alt. 2: Construct a new concrete tank in the adjacent area to the east/southeast of the existing
reservoir. Most likely, the new tank will be partially buried to lower the height of the tank; but
there is a possibility that the upslope side may be closer to being fully buried (to further lower
the height of the tank). Based on pre-design planning, there are two tank size alternatives that
are now being considered. The small tank alternative would be 80 feet in diameter; while the
large tank alternative would be 170 feet in diameter. Both tank alternatives will be 30 feet tall
(from floor to roof). It is unknown whether the existing reservoir will remain in service if a new
tank is constructed; and will likely largely depend on what improvements are necessary/needed
(to keep it in service).
• Alt. 3: Construct a new concrete tank at an upgradient site that is located about 0.75-miles
upslope of the existing reservoir. See Figure 11 for a geology map that shows the Alternative 3
site location in relation to the existing Lyman Reservoir facility. Based on discussions during the
RFP process, it is our understanding that Alternative 3 is not being highly considered at this time
since our proposal/cost for a geotechnical investigation of this site was not authorized as part of
the approved scope of work.
SCOPE OF WORK
Provided below is a summary of our scope of work for pre-design geotechnical services:
• Drill boreholes within the embankment fill section (on southwest/downslope side of the existing
reservoir), collect soil samples, and install groundwater monitoring wells. We drilled BH-1 and
BH-2 (and installed MW-1 and MW-2) in this area.
• Drill boreholes on southeast and northwest sides of the existing reservoir, collect soil samples,
and install groundwater monitoring wells. We drilled BH-3 and BH-4 (and installed MW-3 and
MW-4) in these areas. It was not necessary to drill a borehole on the northeast/upslope side of
the reservoir since a monitoring well (Ex. MW) already existed.
• Drill boreholes in the general area of the proposed Alternative 2 tank location (adjacent to and
east/southeast of existing reservoir), collect soil samples, and install groundwater monitoring
wells. We drilled BH-5, BH-6, and BH-7 (and installed MW-5, MW-6, and MW-7) in this area.
• Perform lab testing of select samples (as necessary) to obtain soils information for analysis and
recommendations. We tested the following items: Several samples for soil classification (ie.
natural moisture contents, atterberg limits, and percent passing No. 200 sieve); a sample of the
embankment fill materials to obtain shear strength parameters (for slope stability analysis); and
four samples of soils from the Alternative 2 tank location to determine soil corrosivity potential
(for tank concrete).
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 4
• Perform groundwater monitoring of all monitoring wells before, during, and after the emptying
and re-filling of the existing reservoir (in February/March 2026); and continuing through spring
and early summer (during the spring runoff). From November 19, 2025 to June 17, 2026, we
monitored groundwater levels 25 times. The majority of the monitoring was conducted from
mid-February to mid-March as the reservoir was being emptied, while it was empty, and while it
was being re-filled.
• Conduct an extensive slope stability analysis of the existing embankment fill section (on the
downslope side of the existing reservoir) to determine its factor of safety (FoS) for a future slope
failure under static and seismic conditions. As part of our work, we analyzed eight scenarios.
For Scenarios 1 through 5, we modeled the existing embankment fill geometry (1.57H:1V slope)
under different groundwater conditions. For Scenarios 6 through 8, we modeled flatter, 2H:1V,
2.5H:1V, and 3H:1V slope configurations under the highest/worst-case groundwater condition.
• Evaluate the foundation bearing conditions under the Alternative 2 tank location and provide
preliminary geotechnical recommendations for foundation design, foundation support, ground
improvement (with rammed aggregate piers or vibro stone columns), and subsurface drainage
(around the perimeter sidewalls and under the tank footprint area).
• Prepare a pre-design geotechnical assessment report (for Alternatives 1 and 2) that summarizes
our work, findings, results, and recommendations.
CONTENT OF REPORT
Provided below is an itemized summary of the sections within this report.
• Summary of findings:
o Existing reservoir (Alternative 1).
o New tank site (Alternative 2).
• Summary of recommendations:
o Existing reservoir (Alternative 1).
o New tank site (Alternative 2).
• Detailed summary of report attachments.
• Site geology.
• Site observations:
o Existing reservoir (Alternative 1).
o New tank site (Alternative 2).
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 5
• Subsurface exploration and testing:
o Borehole drilling.
o Monitoring well installation.
o Laboratory testing.
• Soil conditions:
o Embankment fill section (Alternative 1).
o New tank site (Alternative 2).
• Groundwater conditions:
o Existing reservoir (Alternative 1).
o New tank site (Alternative 2).
• Slope stability analysis of existing embankment fill section (Alternative 1).
• Recommendations for existing reservoir and embankment fill section (Alternative 1).
• Preliminary foundation-related recommendations for new tank site (Alternative 2).
SUMMARY OF FINDINGS
Provided below is our summary of findings for the existing reservoir (Alternative 1) and the new tank
site (Alternative 2):
Existing Reservoir (Alternative 1)
• The project site is mapped as a Quaternary-aged, alluvial fan deposit. There are no mapped
landslide deposits nearby or upslope of the site.
• There are no signs of surface movements or deformations around the existing reservoir.
• The downslope face/geometry of the existing embankment fill section is well vegetated; and
uniform and planar. There are no signs of surface movement or instability. Based on this, the
fill section appears to be historically stable.
• The embankment fill section is 21 to 25 feet tall (depending on location); and is comprised of
sandy lean clay w/ scattered pebbles and small gravels. The foundation soils underlying the fill
section consist of native, clay w/ more gravel. There were no weak soil layers identified within
or under the fill section materials.
• Natural, seasonal high groundwater conditions do rise close to and above the bottom of the
reservoir on the northeast and northwest sides (in the Ex. MW and MW-4).
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 6
• It appears that natural, seasonal high groundwater conditions also can rise close to the bottom
of the reservoir on the southwest/downslope side (in MW-1 and MW-2). Since the downslope
side of the reservoir is “dug into” native soils, this high-water level (at the bottom of reservoir) is
about 6.0 feet below the bottom of the embankment fill section materials.
• Based on groundwater monitoring during the emptying and re-filling of the reservoir (when the
liner drain value was closed), it was confirmed that the existing reservoir leaks, including both
the polypropylene liner and old concrete shell. As the reservoir was emptied, the groundwater
levels dropped; and as the reservoir was filled, the water levels rose quickly and substantially.
• During the re-filling process, it was estimated that the amount of leakage was approximately
300 gpm (which was equal to the reservoir inflow rate needed to maintain the reservoir water
level when the liner drain valve was closed).
• During the re-filling process (when the liner drain valve was closed), the groundwater levels rose
quickly/sharply and by large amounts. This was caused by extensive leakage (through the liner
and through the concrete shell) that was artificially “mounding the groundwater table”.
• An extensive slope stability analysis was conducted on the existing embankment fill section
(using topographic survey geometry, borehole soils information, and lab testing data for shear
strength parameters of the embankment fill materials). The existing embankment was modeled
under five different groundwater scenarios, including Scenario 1 – Groundwater Below Bottom
of Reservoir; Scenario 2 – Groundwater At Bottom of Reservoir; Scenario 3 – Groundwater
Above Bottom of Reservoir and At Bottom of Embankment Fill Section; Scenario 4 – Mid-Level
Leak and Partial Saturation of Embankment Fill Section; and Scenario 5 – High-Level Leak and
Partial Saturation of Embankment Fill Section. Under all five scenarios, the static factor of safety
(FoS) was > 1.5; while the seismic FoS for a 500-year earthquake event was >1.1. Both of these
FoS values are considered minimum, accepted design standards. As a result, our slope stability
modeling shows the existing embankment fill section to be stable; and if any surface movement
were to occur, it would be confined to the outer 10 to 15 feet of the embankment fill. As a note,
our FoS values are very similar to the slope stability values contained in the 2000 HKM Technical
Memorandum No. 3 Design Report (summarizing their evaluation of the Lyman Reservoir).
• In addition to the five scenarios above (for the existing 1.57H:1V slope condition), we analyzed
three, possible slope improvement options (for flatter slope configurations). These included:
Option 1 – 2H:1V; Option 2 – 2.5H:1V, and Option 3 – 3H:1V. Each of these options was
modeled (as Scenarios 6, 7, and 8) using the worst-case groundwater conditions (Scenario 5 –
High-Level Leak). The purpose of this evaluation was to see if a flatter slope configuration would
significantly improve the FoS values. What was found was that static FoS increased from 1.582
to 1.686 to 1.823 to 1.960; while seismic FoS increased very little from 1.171 to 1.193 to 1.219
to 1.245. In our opinion, the increase in seismic FoS (which is a more critical design parameter
than static FoS) was non-significant; and does not warrant any future slope improvements.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 7
New Tank Site (Alternative 2)
• Similar to the existing reservoir site location, the new tank location will also be underlain by
Quaternary-aged alluvial fan deposits; and no mapped landslide deposits exist nearby.
• The site terrain consists of a gentle, planar slope with signs of any past surface movements.
• The alluvial fan materials underlying the new tank site will consist of alternating layers/seams of
silt/clay; silt/clay with interbedded sand/gravel seams; sand/gravel with interbedded silt/clay
seams; and sand/gravel. Based on the depositional history of this type of geologic deposit, the
soil layers are not uniform (across the site) with respect to layer location, layer composition, and
layer thickness. In short, the layered alluvial fan deposit is variable. In some areas, it is more
silt/clay; and in other areas; it is more sand/gravel; and in other areas, it is a “variable mixture”.
• All silt/clay soils are stiff; and all sand/gravel soils are dense. No soft or weak soils were found.
• Natural, seasonal high groundwater conditions appear to be deeper than about 40 feet in the
general area of the new tank site (based on MW-5, MW-6, and MW-7).
SUMMARY OF RECOMMENDATIONS
Provided below is our summary of recommendations for the existing reservoir (Alternative 1) and the
new tank site (Alternative 2):
Existing Reservoir (Alternative 1)
• In the future, whenever the reservoir will be emptied for cleaning or maintenance, this should
be scheduled in the late fall, winter, early spring when the groundwater levels are the lowest.
• Prior to emptying the reservoir, the monitoring wells (on all four sides) should be measured to
confirm that water levels are at, near, or below the bottom of the reservoir.
• To prevent the possibility of groundwater mounding (caused by leakage) under and around the
reservoir (and from rising to the bottom of the embankment fill materials); the liner drain valve
needs to remain open. Even in the event the leaking liner is repaired or replaced (as part of a
future improvement project), the liner drain valve must be in the open position. The FoS values
for slope stability are much higher when groundwater levels are at or below the bottom of the
embankment fill section.
• Due to only minor increases in seismic FoS (as a result of a flatter slope configuration), there is
no reason to consider a future slope flattening improvement project (for a 2H:1V, 2.5H:1V, or
3H:1V condition). The increase in seismic FoS is insignificant and does not justify the expense.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 8
New Tank Site (Alternative 2)
• Foundation soils across the new tank footprint will be variable and non-uniform due to: 1) the
variable layered condition of the sloping alluvial fan deposit; and 2) the change in foundation
depth from the low side to the high side of the new tank site as the tank is cut into the sloping
hillside). As a result of these varying conditions, there is a differential settlement concern (since
foundation soils are not consistent and will range from silt/clay to sand/gravel to a “mixture”).
• To minimize the differential settlement potential, we recommend a concrete mat foundation
underlain by a minimum of 12 inches of compacted structural fill; and at a minimum, ground
improvement elements (ie. rammed aggregate piers or vibro stone columns) under/around the
entire perimeter wall line (of the tank) as well as under any interior columns (for roof support).
Depending on the final design of the tank; and specifically, how much of the tank height will be
set above ground verses buried); additional ground improvement elements may be needed
under the slab area in non-footing areas (to further strengthen the foundation bearing soils if
new loads exceed a certain threshold). The final design of the ground improvement system will
be the responsibility of the pier contractor, which is standard practice and an industry standard.
• All on-site soils are suitable for foundation bearing/tank support with ground improvement; and
with the recommended mat slab and structural fill section (as stated above).
• There is no defined “target” bearing material (due to variable soil conditions across the site).
• The support of the tank does not require a deep foundation system (ie. steel piles).
• Based on lab testing, the on-site soils are not corrosive to standard concrete. Therefore, there is
no reason for the use of Type V cement in the foundation/tank concrete.
• At a minimum, subsurface drainage elements shall include a 6-inch perimeter footing drain that
is bedded in a crushed rock section that extends 2.0 feet (min.) above top of slab and wrapped
in non-woven fabric; and geocomposite drainage panels around the perimeter of the tank. The
main purposes of these drainage provisions are to intercept any groundwater seepage, to keep
the foundation backfill soils as dry as possible; and to provide a drain line in the event that the
sidewall of the tank develops a leak and water builds up along the outside of the tank.
• In addition, it would also be a good idea to consider an underslab drainage system to collect any
water that may leak through cracks that develop in the bottom of the tank. If this system is
added, we recommend underlaying the slab area with 6 inches (min.) of clean crushed rock that
contains a network of 4-inch drain piping, which in turn overlies the recommended 12-inch
(min.) structural fill layer. The main purposes of the underslab drainage system are to prevent
saturation of the foundation soils; and to better alert the City if a leak is occurring. If installed,
the perimeter footing drain elevation shall be lowered to the bottom of the crushed rock layer.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 9
REPORT ATTACHMENTS
There are several attachments to this report. The attachments are a big part of the report and provide
detailed information (maps, exhibits, cross sections, logs, data, and results) that is easy to understand.
They “illustrate” the site conditions, our slope stability analysis (for Alternative 1), and our foundation
recommendations (for Alternative 2). Please refer to the attachments during the review of the report.
A summary/description of the attachments is presented below:
• Figure 1 – Borehole Locations and Depths: This figure uses existing aerial imagery as the base
map; and shows the existing site conditions and the locations and depths of our seven boreholes
(BH-1 through BH-7) that were drilled across the project site on November 10 – 18, 2025.
• Figure 2 – Monitoring Well Locations and Depths: This figure uses existing aerial imagery as the
base map; and shows the existing site conditions and the locations and depths of our seven
monitoring wells (MW-1 through MW-7) that were installed in BH-1 through BH-7. This figure
also shows the location and depth of the existing monitoring well (Ex. MW) that is located on
the upslope/northeast side of the existing reservoir.
• Figure 3 – Summary of Soil Conditions – Project Site Area: This figure uses existing aerial imagery
as the base map; and shows the soil conditions/soil stratigraphy that was found in each of the
seven boreholes (BH-1 through BH-7) that were drilled across the project site. The colors of the
soil conditions (on this figure) match the attached borehole logs. The main purpose of the figure
is to illustrate the variable layered soil conditions across the site with respect to layer location,
layer composition, and layer thickness (and that there is no uniformity across the site).
• Figure 4 – Foundation Conditions – New Tank Site: This figure uses existing aerial imagery as the
base map; and shows the probable foundation bearing conditions under the new tank site based
on our borehole findings in BH-3, BH-5, BH-6, and BH-7. The colors of the soil conditions (on this
figure) match the attached borehole logs. Based on initial design concepts (for a partially buried
tank configuration), the bottom of the tank could be 30 feet (+/-) deep on the upslope side and
23 feet (+/-) deep on the downslope side. However, as we understand it, shallower depth tank
configurations are being considered during the more recent pre-design process to reduce the
amount of foundation excavation. The main purpose of the figure is to illustrate that foundation
bearing conditions are expected to vary across the footprint area of the tank (depending on
location and depth); and they are expected to consist of a combination of layers of silt/clay,
layers of silt/clay with thin, interbedded seams of sand/gravel, layers of sand/gravel with thin,
interbedded seams of silt/clay, and layers of “cleaner” sand and gravel.
• Figure 5 – Existing Embankment Fill Section – Existing Reservoir: This figure shows a detailed
cross section of the existing embankment fill section and the downslope end of the existing
reservoir. It is based on the site topography (from a Morrison Maierle topographic site survey),
the existing elevation of the reservoir floor slab, our understanding of the maximum operating
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 10
height of the reservoir (28.2 feet), and our borehole findings in BH-1 and BH-2 (both of which
were drilled within the embankment fill section). The purposes of the figure are to show 1) the
as-built geometry; 2) that the bottom depth of the reservoir extends below the bottom of the
embankment fill section; 3) the highest “natural” groundwater level that was measured in the
embankment fill section area (in MW-2 on December 18, 2025) prior to emptying the reservoir
(in February 2026); and 4) the highest “mounded” groundwater level that was measured in the
embankment fill section area (in MW-1 on March 12, 2026) during the re-filling of the reservoir
(and measured just a few hours before the liner drain system valve was opened on March 12).
• Figure 6 – Summary of Slope Stability Analyses – Existing Reservoir: This figure uses the Figure 5
cross section (of the existing embankment fill section and downslope end of existing reservoir)
as the base map; and shows and summarizes the eight scenarios that were modeled as part of
the slope stability analysis. For Scenarios 1 through 5, the existing embankment fill section
geometry and its 1.57H:1V slope configuration were analyzed under five different groundwater
conditions. For Scenarios 6 through 8, new and flatter 2H:1V, 2.5H:1V, and 3H:1V slope options
(which are identified as Options 1, 2, and 3) were analyzed using the highest/worst-case ground-
water condition (same as Scenario 5). The purpose of Scenarios 6 through 8 was to evaluate if a
flatter, slope configuration would result in a significant increase (improvement) in the slope
stability factor of safety (FoS) results. Other items included on Figure 6 are detailed information
on the slope stability analysis and a summary of the final results (for static FoS and seismic FoS)
for all eight scenarios.
• Figure 7 – Option 1 – 2H:1V Slope Improvement – Existing Reservoir: This figure is a neat line,
concept diagram that shows existing embankment fill section geometry (with a 1.57H:1V slope)
and the new embankment fill addition that would be required to flatten the existing slope to a
2H:1V configuration (assuming that the new fill section is “hinged at the top” of the existing fill
section). The purposes of this figure are to 1) illustrate the width of new embankment fill (at the
toe of new fill section) and 2) show the estimated volume of new embankment fill (per running
foot of embankment fill length). As shown on the figure, the new width at toe of fill is 11.0 feet;
and the estimated volume of new fill is 4.5 CY per running foot of embankment length.
• Figure 8 – Option 2 – 2.5H:1V Slope Improvement – Existing Reservoir: This figure is a neat line,
concept diagram that shows existing embankment fill section geometry (with a 1.57H:1V slope)
and the new embankment fill addition that would be required to flatten the existing slope to a
2.5H:1V configuration (assuming that the new fill section is “hinged at the top” of the existing fill
section). The purposes of this figure are to 1) illustrate the width of new embankment fill (at the
toe of new fill section) and 2) show the estimated volume of new embankment fill (per running
foot of embankment fill length). As shown on the figure, the new width at toe of fill is 27.0 feet;
and the estimated volume of new fill is 11.0 CY per running foot of embankment length.
• Figure 9 – Option 3 – 3H:1V Slope Improvement – Existing Reservoir: This figure is a neat line,
concept diagram that shows existing embankment fill section geometry (with a 1.57H:1V slope)
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 11
and the new embankment fill addition that would be required to flatten the existing slope to a
3H:1V configuration (assuming that the new fill section is “hinged at the top” of the existing fill
section). The purposes of this figure are to 1) illustrate the width of new embankment fill (at the
toe of new fill section) and 2) show the estimated volume of new embankment fill (per running
foot of embankment fill length). As shown on the figure, the new width at toe of fill is 44.0 feet;
and the estimated volume of new fill is 18.0 CY per running foot of embankment length.
• Figure 10 – Preliminary Foundation Detail – New Concrete Tank: This figure illustrates our
preliminary geotechnical recommendations for the foundation design, foundation support, and
foundation improvement of a new, partially buried, concrete tank that is located to the east/
southeast of the existing reservoir. Our recommendations include a thick mat slab foundation
that is supported on a 12-inch (min.) layer of granular structural fill; and ground improvement
elements (ie. rammed aggregate piers or vibro stone columns) under perimeter wall line loads
and interior column loads. Additional recommendations regarding the length/depth, diameter,
and spacing of the ground improvement elements are provided for cost estimating purposes.
• Figure 11 – Geology Map: This figure is an excerpt of the MBMG geology map for the project
area. It shows that the underlying geology of the existing Lyman Reservoir project site (as well
as a potential upgradient tank location site) consists of Quaternary-aged, alluvial fan deposits.
There are no mapped landslides or debris flows in the areas of the three project alternatives.
• Borehole Logs for BH-1 through BH-7: Detailed borehole logs are provided for the seven bore-
holes (BH-1 through BH-7) that were drilled across the project site. Each log is color-coded to
easily differentiate the variable, layered soil conditions. The color-coded, soil sequence on the
logs matches the borehole soil stratigraphy that is shown on Figures 3 and 4.
• Exhibits 1 through 7 – Monitoring Well As-Builts for MW-1 through MW-7: These exhibits show
the as-constructed condition of the seven monitoring wells (MW-1 through MW-7) that were
installed in BH-1 through BH-7.
• AESI Lab Testing Results: All soil samples were tested for naturel moisture content; while select
samples were tested for atterberg limits and percent passing the No. 200 sieve (in order to aid in
the classification of the on-site soils).
• PTS Lab Testing Results: Select samples were submitted to Pioneer Technical Services for lab
testing. These are the results for soil corrosivity testing (for foundation concrete for new tank)
and for triaxial compression testing (for slope stability analysis of existing embankment section).
• Groundwater Monitoring Data for MW-1 through MW-7 through June 17, 2026: Groundwater
monitoring has been conducted at the site from November 19, 2025 through June 17, 2026 in
the eight on-site monitoring wells (including MW-1 through MW-7 and the Ex. MW). These
forms contain all the groundwater data that has been collected at the site.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 12
• Exhibits A1 through A3 – Slope Stability Analysis for Scenario 1: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 1. Under
this scenario, the existing embankment fill section geometry and 1.57H:1V slope configuration
was modeled under a deep groundwater condition well below the bottom of the embankment
fill section materials (and similar to the “natural” 45.1-foot (+/-) groundwater depth that was
measured in MW-2 on December 18, 2025). The results show a static FoS of 1.829 and a seismic
FoS of 1.395; and that any potential slope movements would be confined to the outer 10 to 15
feet of the embankment fill section.
• Exhibits B1 through B3 – Slope Stability Analysis for Scenario 2: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 2. Under
this scenario, the existing embankment fill section geometry and 1.57H:1V slope configuration
was modeled under an elevated groundwater condition that matches the bottom of the existing
reservoir floor elevation (which is approximately 6.2 feet below the bottom of the embankment
fill section and about 31.2 feet below the top of the embankment fill section). The results show
a static FoS of 1.829 and a seismic FoS of 1.396; and that any potential slope movements would
be confined to the outer 10 to 15 feet of the embankment fill section.
• Exhibits C1 through C3 – Slope Stability Analysis for Scenario 3: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 3. Under
this scenario, the existing embankment fill section geometry and 1.57H:1V slope configuration
was modeled under an elevated groundwater condition that lies at the interface between the
bottom of the embankment fill section materials and the underlying native subgrade soils (and
closely corresponds with the highest “mounded” groundwater level of 26.4 feet (+/-) that was
measured in MW-1 on March 12, 2026 during the re-filling of the reservoir). The results show a
static FoS of 1.705 and a seismic FoS of 1.257; and that any potential slope movements would
be confined to the outer 10 to 15 feet of the embankment fill section.
• Exhibits D1 through D3 – Slope Stability Analysis for Scenario 4: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 4. Under
this scenario, the existing embankment fill section geometry and 1.57H:1V slope configuration
was modeled under an elevated groundwater condition that mimics a “mid-level leak on the
southwest side of the reservoir and a partially saturated embankment fill section condition”.
The results show a static FoS of 1.649 and a seismic FoS of 1.221; and that any potential slope
movements would be confined to the outer 10 to 15 feet of the embankment fill section.
• Exhibits E1 through E3 – Slope Stability Analysis for Scenario 5: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 5. Under
this scenario, the existing embankment fill section geometry and 1.57H:1V slope configuration
was modeled under an elevated groundwater condition that mimics a “high-level leak on the
southwest side of the reservoir and a partially saturated embankment fill section condition”
(which would be worst-case condition). The results show a static FoS of 1.582 and a seismic FoS
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 13
of 1.171; and that any potential slope movements would be confined to the outer 10 to 15 feet
of the embankment fill section.
• Exhibits F1 through F3 – Slope Stability Analysis for Scenario 6: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 6. Under
this scenario, the existing embankment fill section geometry was modeled with a flatter, 2H:1V
slope improvement (Option 1) and the same elevated groundwater condition (as Scenario 5)
that mimics a “high-level leak on the southwest side of the reservoir and a partially saturated
embankment fill section condition” (which would be worst-case condition). The results show a
static FoS of 1.686 and a seismic FoS of 1.193; and that any potential slope movements would
be confined to the outer 10 to 15 feet of the embankment fill section.
• Exhibits G1 through G3 – Slope Stability Analysis for Scenario 7: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 7. Under
this scenario, the existing embankment fill section geometry was modeled with a flatter,
2.5H:1V slope improvement (Option 2) and the same elevated groundwater condition (as
Scenario 5) that mimics a “high-level leak on the southwest side of the reservoir and a partially
saturated embankment fill section condition” (which would be worst-case condition). The
results show a static FoS of 1.823 and a seismic FoS of 1.219; and that any potential slope
movements would be confined to the outer 10 to 15 feet of the embankment fill section.
• Exhibits H1 through H3 – Slope Stability Analysis for Scenario 8: These exhibits show the slope
stability analysis set-up and FoS results for static and seismic conditions for Scenario 8. Under
this scenario, the existing embankment fill section geometry was modeled with a flatter, 3H:1V
slope improvement (Option 3) and the same elevated groundwater condition (as Scenario 5)
that mimics a “high-level leak on the southwest side of the reservoir and a partially saturated
embankment fill section condition” (which would be worst-case condition). The results show a
static FoS of 1.960 and a seismic FoS of 1.245; and that any potential slope movements would
be confined to the outer 10 to 15 feet of the embankment fill section.
SITE GEOLOGY
Per a MBMG geology map for the Bozeman area (see Figure 11), the project site lies in the middle of a
large Quaternary-aged, alluvial fan complex that emanates off the west side of the Bridger Mountains.
According to the map, there are no mapped landslide deposits upslope or downslope of the site.
SITE OBSERVATIONS
Existing Reservoir (Alternative 1)
• The down slope side of the embankment fill section shows no signs of instability or movements
(such as tension cracks or surface slumps). The slope is dry, smooth, planar, and well vegetated.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 14
• The ground surface around the sides of the reservoir is normal-looking with no signs of surface
deformation, cracking, or movement.
New Tank Site (Alternative 2)
• The area for the new tank consists of a gentle and uniform, planar slope that is well vegetated.
All of these are strong evidence of long-term slope stability. None of the site characteristics
suggest any past instability issues.
SUBSURFACE EXPLORATION AND TESTING
Borehole Drilling
On November 10 through 18, 2025, seven boreholes were drilled around the site using a truck-mounted
drill rig provided by O’Keefe Drilling. The boreholes were drilled to depths of 38.5 to 71.5 feet and were
identified as BH-1 through BH-7. During the drilling, standard penetration tests and soil samples were
obtained at 2.5 to 5.0-foot spacing. Two borings (BH-1 and BH-2) were positioned within the existing
embankment fill section on the southwest/down slope side of the existing reservoir. Two borings (BH-3
and BH-4) were located on the southeast and northwest sides of the existing reservoir, respectively. The
final three borings (BH-5, BH-6, and BH-7) were sited in the general area for the new tank, located on
the east/southeast side of the existing reservoir. See Figures 1 through 4 for the approximate borehole
locations. Figure 1 also shows the depths of each boring.
Monitoring Well Installation
Besides observing the soil conditions and collecting SPT data/soil samples, another main purpose of the
borings was to install monitoring wells. Following drilling, each of the boreholes were backfilled with a
2-inch, PVC monitoring well. The wells ranged in depth from 38.5 to 70.0 feet and were termed MW-1
through MW-7 (to match the corresponding BH number). See Figure 2 for the approximate monitoring
well locations and the depths of each of the wells.
All wells were constructed in the same manner. Each consists of long sections of 2-inch well screen (at
the bottom) and approximately 12 feet of 2-inch well casing (at the top), which is encased at the ground
surface in a 5.0-foot long, 6-inch steel protective casing. The well screen is backfilled with silica sand;
while the well casing is backfilled with bentonite pellets. See Exhibits 1 through 7 for well construction
diagrams showing the as-built condition of each of the wells.
Laboratory Testing
• Natural Moisture Contents: All sack samples that were collected during drilling were tested for
natural moisture content. The lab testing data is attached and is also shown on each of the
borehole logs.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 15
• Atterberg Limits: Eight samples of silt/clay soils were tested for Atterberg limits. Four of the
samples were of the embankment fill material (from BH-1 and BH-2); and four of the samples
were of native soils in the new tank site area (from BH-3, BH-5, BH-6, and BH-7). The purposes
of the testing were for soil identification and to confirm that the soils were not fat/expansive
clay. All eight samples yielded similar results; and all classified as low plasticity, lean silt/clay
(CL-ML). The lab testing data is attached.
• Percent Passing No. 200 Sieve: The same eight samples of silt/clay (plus one additional sample)
were also tested for percent passing No. 200 sieve. Similar to above, the purpose of the testing
was for soil identification; but also to determine if certain samples were more of a silt/clay with
seams of sand/gravel or if they instead were more of a sand/gravel with seams of silt/clay. Most
of the samples were > 50% silt/clay; while only two had less than < 50% silt/clay. The lab testing
data is attached.
• Soil Corrosivity Potential for Concrete: Four silt/clay samples in the area of the new tank (from
BH-3, BH-5, BH-6, and BH-7) were submitted to Pioneer Technical Services for soil corrosivity
potential and tested for pH, marble pH, and soluble sulfate. According to Montana Department
of Transportation design standards, Type I-II cement is used when soil sulfate contents are less
than 0.20%; and Type V cement is required when sulfate levels are between 0.20% and 2.0%.
Based on the testing data, which is attached, the four samples had sulfate contents ranging from
0.0001% to 0.0012%. As a result, none of the samples are corrosive to standard concrete; and
there is no reason to use Type V cement for the tank/foundation concrete.
• Triaxial Shear Strength Parameters: In order to obtain shear strength parameters for our slope
stability analysis, three Shelby tube samples of the embankment fill material (from BH-2) were
submitted to Pioneer Technical Services for triaxial testing. The samples yielded total cohesion
and total friction angle values of 3.90 psi and 15.8 degrees; and effective cohesion and effective
friction angle values of 2.59 psi and 28.4 degrees. The lab testing data is attached.
o Note: During drilling of BH-2, we attempted to collect a Shelby tube sample of the
native foundation soils below the bottom of the embankment fill material (sandy lean
clay) for triaxial testing. However, the native clay was too stiff/dense and too gravelly to
push the tube in and get a sample (as the tube buckled during penetration).
SOIL CONDITIONS
Embankment Fill Section (Alternative 1)
• The embankment fill section on the southwest/down slope side of the existing reservoir is 21 to
25 feet tall (depending on the location) and is comprised of medium stiff to stiff, sandy lean clay
with scattered pebbles and small gravels. Based on the lab testing of four samples, the clay soil
classifies as a “CL”; and the percent passing the No. 200 sieve ranges from 55% to 60%.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 16
• The native foundation soils below the embankment fill section consist of stiff to very stiff, sandy
clay with scattered pebbles and occasional seams of sand/gravel. In general, the soils are stiffer
and more gravelly (than the embankment materials).
• See the attached borehole logs for BH-1 and BH-2. The soil stratigraphy on each log is color-
coded (for easier understanding/comparison). This same soils information is shown on Figure 3.
New Tank Site (Alternative 2)
• The new tank site area is underlain by alternating layers of silt/clay, silt/clay with gravel seams,
gravel with silt/clay seams, sand & gravel.
• Based on the relatively closely-spaced boreholes, the soil stratigraphy is not uniform/consistent
from location to location. Depending on the borehole, the layers vary in location, composition,
and thickness. This is pretty typical for an alluvial fan deposit (that is located close to its “source
area”, like this one is).
• Regardless whether the soils are more of a silt/clay or more of a sand/gravel (or some mixture in
between), all the soils in the boreholes were stiff to dense. No soft/weak soil layers were found.
• See the attached borehole logs for BH-3, BH-5, BH-5, and BH-6. The soil stratigraphy on each log
is color-coded (for easier understanding/comparison). This same soils information is shown on
Figures 3 and 4. The big take-way that is illustrated on these two figures is none of the layers
really “align” from borehole to borehole. Each borehole’s layering sequence is different.
GROUNDWATER CONDITIONS
Existing Reservoir (Alternative 1)
• In December, January, and early to mid-February, the groundwater levels on the southwest/
down slope side of the tank within the embankment fill section (in MW-1 and MW-2) were at
depths of > 45 feet; while the water level on the southeast side (in MW-3) was > 50 feet. In
contrast, the water levels on the northeast and northwest sides (in Ex. MW and MW-4) were
much higher at depths of 33 feet and 26 feet, respectively.
• As the reservoir was emptied in late February, water levels in all the surrounding wells dropped.
• When the reservoir was re-filled in early to mid-March, all the water levels in the surrounding
wells shot upwards at a very rapid rate and to a much higher level than they were immediately
before the emptying of the reservoir began. As it turns out, both the polypropylene liner and
old concrete shell have leaks; and the liner drain valve was closed. This resulted in the leakage
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 17
draining through the concrete shell and directly into the ground below and around the reservoir,
which caused an artificially “mounded groundwater condition”. As soon as the liner drain valve
was opened in mid-March, the water levels began to slowly subside.
• Around the middle to latter part of April, water levels rose again as a result of seasonal run-off.
Since the groundwater table was still in a “likely mounded condition”, it is unknown if these high
water levels are “typical” or if they were elevated/influenced by the reservoir leakage in mid-
March. Perhaps the safest assumption is that they are “typical”. If this is the case, water levels
in the embankment fill section (in MW-1 and MW-2), and on the southeast side of the reservoir
(in MW-3), rose to depths of 31 to 32 feet (which is an equal to the bottom of reservoir depth
and about 6.0 feet below the bottom of the embankment fill section on the southwest/down-
slope side of the reservoir). On the northeast side (in Ex. MW), the water level rose to 24 feet;
while on the northwest side (in MW-4), the water level rose to 16 feet.
• Over the two months (from the latter part of April to the latter part of June), water levels in all
wells were slowly dropping. In most locations, the June 17 water level (which was the last day
monitoring occurred) was between 4.5 feet and 6.6 feet above the water level on December 18.
New Tank Site (Alternative 2)
• In December, January, and early to mid-February, the groundwater levels in the new tank area
(in MW-5 and MW-6) were at a depth of 49 to 50 feet.
• In these same two wells, the highest water levels that were recorded this spring (on May 13)
were at 41 to 42 feet. After this date, the water level in both wells began to drop.
SLOPE STABILITY ANALYSIS
Existing Embankment Fill Section (Alternative 1)
As part of our geotechnical assessment, an extensive slope stability analysis was performed on the
existing embankment fill section (on the southwest/down slope side of the reservoir). For the model
setup, we used existing site/slope geometry (1.57H:1V) from the M-M topographic survey, the soil
stratigraphy/conditions from BH-1 and BH-2, and the shear strength parameters from our lab testing.
For the groundwater conditions, we modeled five scenarios. Each scenario, which is listed below, was
analyzed for static conditions and seismic conditions (ie. for a 500-year earthquake event).
• Scenario 1: Groundwater Well Below Bottom of Reservoir.
• Scenario 2: Groundwater At Bottom of Reservoir (and Below Embankment Fill Section).
• Scenario 3: Groundwater Above Bottom of Reservoir (At Bottom of Embankment Fill Section).
• Scenario 4: Mid-Level Leak and Partially Saturated, Embankment Fill Section Condition.
• Scenario 5: High-Level Leak and Partially Saturated, Embankment Fill Section Condition.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 18
Flattened Embankment Fill Section (Alternative 1)
In addition to the five scenarios listed above (for existing conditions), we also modeled three scenarios
for a flattened, down slope configuration. The purpose of the effort was to see if a flatter slope (than
the existing 1.57V:1H slope) would cause a significant increase in the slope stability factor of safety (FoS)
values. Three slope improvement options were considered: Option 1 – 2H:1V; Option 2 – 2.5H:1V; and
Option 3 – 3H:1V. These are illustrated on Figures 7, 8, and 9. Each of these three options was modeled
(as Scenarios 6 through 8) using the same soil conditions (as Scenarios 1 through 5); but only the worst-
case groundwater condition (same as Scenario 5). Each scenario, which is listed below, was analyzed for
static conditions and seismic conditions (ie. for a 500-year earthquake event).
• Scenario 6: Option 1 – 2H:1V; High-Level Leak and Partially Saturated Embankment Fill Section.
• Scenario 7: Option 2 – 2.5H:1V; High-Level Leak and Partially Saturated Embankment Fill Sec.
• Scenario 8: Option 3 – 3H:1V; High-Level Leak and Partially Saturated Embankment Fill Section.
Analysis Results
See Figure 6 for a summary of the slope stability analysis and results for Scenarios 1 through 8 (which
were analyzed using Slope W software). For each of the eight scenarios, three exhibits are provided
showing the model setup, the slope stability results (for static condition), and the slope stability results
(for seismic condition). These exhibits are named Exhibit A1-A3 (for Scenario 1), Exhibit B1-B3 (for
Scenario 2), Exhibit C1-C3 (for Scenario 3), Exhibit D1-D3 (for Scenario 4), Exhibit E1-E3 (for Scenario 5),
Exhibit F1-F3 (for Scenario 6), Exhibit G1-G3 (for Scenario 7), and Exhibit H1-H3 (for Scenario 8). For all
seismic analyses, a horizontal seismic coefficient of 0.15 was used (for a 500-year earthquake event).
Provided below are the static FoS and seismic FoS results for Scenarios 1 through 8:
• Scenario 1: 1.829 (static) 1.395 (seismic)
• Scenario 2: 1.829 (static) 1.396 (seismic)
• Scenario 3: 1.705 (static) 1.257 (seismic)
• Scenario 4: 1.649 (static) 1.221 (seismic)
• Scenario 5: 1.582 (static) 1.171 (seismic)
• Scenario 6: 1.686 (static) 1.193 (seismic)
• Scenario 7: 1.823 (static) 1.219 (seismic)
• Scenario 8: 1.960 (static) 1.245 (seismic)
Analysis Criteria
• Per accepted design standards, FoS of 1.5 (or higher) is considered stable for static conditions.
• Per accepted design standards, FoS of 1.1 (or higher) is considered stable for seismic conditions.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 19
Analysis Conclusions
• For Scenarios 1 through 5, the FoS values for static conditions all exceeded > 1.5; and the FoS
values for seismic conditions all exceeded > 1.1. Therefore, even for the worst-case ground-
water condition (Scenario 5), the stability of the existing embankment fill section still meets the
accepted design criteria and is considered stable. The Scenario 5 groundwater conditions are
highly unlikely; and any seepage emanating from the embankment slope would be noticeable.
• The FoS results that we obtained for Scenario 5 are very similar to the results that HKM shows in
their 2000 Technical Memorandum No. 3 Design Report for the same worst-case groundwater
condition, which simulates a high-level leak on the down slope side of the reservoir.
• Based on the slope stability models, any slope instability that were to occur (under all five of the
scenarios) could cause slope movements/deformation within the outer 10 to 15 feet of the 56-
foot wide embankment fill section. This “limited width of slope impact” along the outer crest of
the embankment would not comprise the structural integrity of the reservoir.
• Based on the FoS results, no additional modification or improvement is necessary to the existing
embankment fill section.
• For Scenarios 6 through 8 (ie. slope improvement options), the static FoS increased from 1.582
(for Scenario 5) to 1.686 (for Scenario 6) to 1.823 (for Scenario 7) to 1.960 (for Scenario 8); while
seismic FoS increased to a far lesser extent from 1.171 (for Scenario 5) to 1.193 (for Scenario 6)
to 1.219 (for Scenario 7) to 1.245 (for Scenario 8).
• Since the seismic FoS is the most critical parameter and the increase is negligible (for the three
slope flattening options); there is not enough benefit to warrant undertaking a future slope
improvement project.
• In our opinion, there is no need to flatten the slope since the existing embankment fill section
meets the accepted design standards; and the “small gain” in seismic FoS for a re-graded slope
configuration (of 2H:1V, 2.5H:1V, or 3H:1V) is not significant (as it is less than 0.022 to 0.074).
RECOMMENDATIONS – EXISTING RESERVOIR AND EMBANKMENT FILL SECTION
Future Reservoir Emptying for Cleaning and Maintenance
Knowing that groundwater levels can rise above the bottom of the reservoir floor on the northwest and
northeast sides (in MW-4 and Ex. MW), emptying of the reservoir for future cleaning and maintenance
work should be scheduled in the late fall, winter, or early spring when groundwater is the lowest. Prior
to emptying the reservoir, the monitoring wells (around all four sides) should be checked to confirm that
water levels are near or below the bottom of the reservoir.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 20
Liner Drain Valve
The liner drain valve needs to remain open at all times (to prevent leakage from causing an artificially
“mounded groundwater condition” under and around the reservoir; and to prevent elevated ground-
water conditions from rising up into the embankment fill section). Even if the liner gets repaired (as part
of a future improvement project), the liner drain valve is a critical safety measure that must be open.
Slope Improvement
Based on the FoS results, no slope improvement (slope flattening) is needed or warranted on the down
slope side of the existing embankment fill section.
PRELIMINARY FOUNDATION RECOMMENDATIONS – NEW TANK SITE
Foundation Detail
Please refer to Figure 10 for a preliminary foundation detail for the new concrete tank. This detail shows
the recommended foundation configuration, foundation earthwork, ground improvement, subsurface
drainage, and foundation wall backfill. Final recommendations will be provided in a final report.
Foundation Design and Support
The native soil stratigraphy under the tank location is suitable for foundation/slab support. Given the
expected variability of the soil conditions across the tank footprint (at slab grade and at depth below the
slab), there is no defined “target” bearing material (for mass over-excavation/replacement). In addition,
the site conditions do not warrant the use of a deep, foundation system (steel piles).
The biggest issue at the site is not soils bearing capacity (as all the foundation soils will be stiff to dense);
but instead, it is the potential for differential settlement due to variable foundation bearing conditions
(which will range from silt/clay -to- silt/clay w/ gravel -to- gravel w/ silt/clay -to- sand/gravel, depending
on the location). To reduce the settlement risk, we recommend the tank be supported on a concrete
mat slab foundation that in turn bears on 12 inches (min.) of structural fill. We foresee the mat slab
thickness could be in the 12 to 14-inch range; but the final design thickness will be determined by the
Structural Engineer.
To further minimize settlement across the tank footprint (and especially under the wall and column
loads), we also recommend the installation of ground improvement elements (ie. rammed aggregate
piers or vibro stone columns) under the perimeter wall line loads and under any interior columns loads
(for roof support), at the very least. Depending on the depth of the tank relative to existing grades and
the new “water-weight” loads that will be exerted on the sub-slab soils, there is a possibility that some
additional ground improvement elements will be required under the slab area of the tank as well. This
will not be known until the tank is in the design process and new foundation loads are determined.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 21
Ground Improvement
Ground improvement shall consist of either rammed aggregate piers or vibro stone columns. Both of
these elements are similar in “look and function”; but they differ in how they are installed. Rammed
aggregate piers are installed in “augered holes”, rammed with a vibrating hammer, and require that the
soil formation materials do not cave/collapse during installation; while vibro stone columns are used for
deeper installations and can be used when soil conditions are prone to caving (as the stone column is
built by feeding gravel material through the drill stem and compacting it with a down-hole vibrator).
Give the stiff to dense soil conditions; coupled with the fact that much of the soil stratigraphy is silt/clay
or silt/clay with gravel seams, we do not expect an issue with caving of the “augered holes”. Therefore,
we foresee that rammed aggregate piers can be used and will be the cheaper option (due to the smaller
and less specialized, installation equipment that is required).
For estimating purposes, we recommend assuming 20-foot deep, rammed aggregate piers (which is the
maximum depth for pier installation); and a center-to center pier spacing of 6.0 to 7.0 feet. Depending
on the pier design, the piers will likely be 24 to 30 inches in diameter. The design of the pier system will
be the responsibility of the pier contractor, which is standard industry practice.
Excavation Slopes
Per OSHA guidelines, the on-site soil stratigraphy should be generally classified as a Type C soil (cohesive
silt/clay soil w/ areas of sand/gravel). This will require a minimum excavation sidewall slope of 1.5H:1V,
which is applicable for excavation depths of 20 feet or less.
If the site conditions will allow, it may be better to assume (and quantify for cost estimating purposes) a
little flatter excavation of 1.75H:1V, or even 2H:1V, for increased worker safety in deeper excavations.
Concrete Corrosivity Potential
Based on the testing of four silt/clay samples from the new tank site, the on-site soils are non-corrosive
to standard concrete. There is no need to use Type V cement in the foundation/tank concrete.
Subsurface Drainage
At a minimum, we recommend a 6-inch perimeter footing drain (at bottom of mat slab grade) that is
bedded in clean crushed rock up a height of 2.0 feet (min.) above the top of the mat slab and wrapped
in 8 oz. non-woven geotextile fabric; and the installation of geocomposite drainage panels around the
perimeter of the tank. The three purposes of this subsurface drainage system are to 1) intercept any
groundwater seepage; 2) keep the foundation backfill soils as dry as possible; and 3) in the event of a
crack in the tank wall that causes the tank to leak, this will allow for the collection and rapid drainage of
the leakage water. Note: This perimeter system will not be very effective for a “leaking floor scenario”.
AESI Pre-Design Geotechnical Assessment Report
Lyman Reservoir – Bozeman, MT
Project: 25-084
July 30, 2026
Page 22
Underslab Drainage Collection System
This recommendation is not shown on the preliminary foundation detail (Figure 10); but it would be a
good idea to consider an additional underslab drainage system (for collection of any leakage that may
drain through the floor as a result of a crack). We foresee this system consisting of a 6-inch (min.) layer
of crushed rock under the slab with a network of 4-inch drain piping. If a crushed rock layer is installed,
it should be placed above the recommended 12-inch (min.) layer of structural fill; and the elevation of
the recommended perimeter footing drain shall be lowered to match the bottom of the crushed rock
layer. This will allow the 4-inch underslab drain piping to be hydraulically connected to the perimeter
footing drain. The tank supplier/contractor will likely have valuable input on whether the inclusion of an
underslab drain system is standard practice (for their concrete tank product).
In our opinion, this system would serve two purposes. First, it would help prevent the saturation of the
foundation soils in the event of a floor leak; and second, it would better alert the City if a floor leak was
occurring and if repairs were needed.
FINAL GEOTECHNICAL REPORT
As stated at the on-set of this pre-design, geotechnical assessment report, it is not a final geotechnical
report and only contains preliminary foundation-related recommendations for the planning and cost
estimating phase for a new concrete tank (Alternative 2). Depending on the location, depth, and design
of the tank, additional geotechnical investigation (boreholes) may be necessary; some of the preliminary
recommendations may need to be modified; and additional recommendations may need to be included.
During the design process, we recommend that a final geotechnical report be prepared.
LIMITATIONS
This assessment-level report provides our geotechnical findings and recommendations for Alternative 1
(Existing Reservoir) and Alternative 2 (New Concrete Tank) at the Lyman Reservoir project site.
As stated above, the recommendations for the new tank alternative should be considered as preliminary
and should only be used for planning and cost estimating. Final geotechnical recommendations for the
design and construction of the tank will be issued in a final geotechnical report.
Our findings and recommendations are based on our understanding of the project alternatives, our
geotechnical investigation of the site’s soil and groundwater conditions, groundwater monitoring data,
an extensive slope stability analysis of the existing embankment fill section; and previous experience
that was gained/learned on other water tank projects and other rammed aggregate pier projects.
All individuals associated with this project should consult this report during the planning and pre-design
phases of the site improvements. It should be made available to other parties for information on factual
data only and not as a warranty of subsurface conditions such as those interpreted herein.
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FIGURELYMAN RESERVOIR
BOREHOLE LOCATIONS AND DEPTHS
BOZEMAN, MONTANA
1
LYMAN RESERVOIR
NOTES:
1) DRILLED 7 BOREHOLES BETWEEN NOVEMBER 10AND NOVEMBER 18, 2025.
2) DEPTH OF BOREHOLES RANGES FROM 38.5' TO 71.5'.
3) BOREHOLE LOCATIONS SHOWN ARE APPROXIMATE.
4) SEE ATTACHED BOREHOLE LOGS.
5) INSTALLED 7 MONITORING WELLS ACROSS THE SITE(SEE FIGURE 2).
N
BASE MAP:
MICROSOFT BING AERIAL IMAGERY
BH-1
38.5'
BH-2
51.5'
BH-3
51.5'
BH-4
40.3'
BH-5
71.5'
BH-6
70.9'
BH-7
70.2'
LEGEND
BOREHOLE DEPTH
(IN FEET)
BH-#
XX.X'
BOREHOLE LOCATION
(BH-1 THROUGH BH-7)
EXISTING RESERVOIR
POSSIBLE NEW
TANK LOCATION
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FIGURELYMAN RESERVOIR
MONITOR WELL LOCATIONS AND DEPTHS
BOZEMAN, MONTANA
2
LYMAN RESERVOIRN
BASE MAP:
MICROSOFT BING AERIAL IMAGERY
LEGEND
MONITORING WELL DEPTH
(IN FEET)
MW-#
XX.X'
MONITORING WELL LOCATION
(MW-1 THROUGH MW-7)
MW-1
38.5'
MW-2
50.0'
MW-3
50.0'
MW-4
40.0'
MW-5
70.0'
MW-6
70.0'
MW-7
70.0'
EX. MW
41.0'
NOTES:
1) AESI INSTALLED 7 MONITORING WELLS ACROSS THE SITEBETWEEN NOVEMBER 10 AND NOVEMBER 18, 2025.
2) EX. MW WAS INSTALLED BY OTHERS IN 2000.
3) DEPTH OF MONITORING WELLS RANGES FROM 38.5' TO 70.0'.
4) MONITORING WELL LOCATIONS SHOWN ARE APPROXIMATE.
5) SEE ATTACHED MONITORING WELL EXHIBITS.
EXISTING RESERVOIR
POSSIBLE NEW
TANK LOCATION
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FIGURELYMAN RESERVOIR
SUMMARY OF SOIL CONDITIONS
BOZEMAN, MONTANA
3
LYMAN RESERVOIR
NOTES:
1) SEE ATTACHED BOREHOLE LOGS FOR MOREDETAILED SOIL DESCRIPTIONS.
2) THE SITE GEOLOGY CONSISTS OF A LAYERED,
QUATERNARY ALLUVIAL FAN COMPLEX COMPRISED
OF ALTERNATING LAYERS OF SILT/CLAY, SILT/CLAY
WITH GRAVEL SEAMS, GRAVEL WITH SILT/CLAYSEAMS, AND SAND AND GRAVEL.
3) THE PURPOSE OF FIGURE 3 IS TO ILLUSTRATE THEVARIABLE LAYERED SOIL CONDITIONS ACROSS THESITE WITH RESPECT TO LAYER LOCATION, LAYERCOMPOSITION, AND LAYER THICKNESS.
N
BASE MAP:
MICROSOFT BING AERIAL IMAGERY
LEGEND
BOREHOLE DEPTH
(IN FEET)
BH-#
XX.X'
BOREHOLE LOCATION
(BH-1 THROUGH BH-7)
BH-1
38.5'
BH-2
51.5'
BH-3
51.5'
BH-4
40.3'
BH-5
71.5'
BH-6
70.9'
BH-7
70.2'
EXISTING RESERVOIR
POSSIBLE NEW
TANK LOCATION
COLOR KEY
TOPSOIL
CLAY (EMBANKMENT FILL)
SILT/CLAY
SILT/CLAY WITH GRAVEL SEAMS
GRAVEL WITH SILT/CLAY SEAMS
SAND & GRAVEL
0.0'1.0'
9.0'
19.0'
32.0'
45.0'
64.0'
70.2'
0.0'1.0'
15.0'
21.0'
24.0'
41.0'
63.0'
70.9'
47.5'
0.0'1.0'
15.0'
20.0'
27.5'
40.0'
61.0'
71.5'
46.0'
10.0'
31.0'
42.0'
50.0'
55.0'
0.0'1.5'
20.0'
30.0'
45.0'
40.0'
51.5'
0.0'1.5'
25.0'
34.0'
38.5'
0.0'1.5'
25.0'
38.0'
51.5'
0.0'0.5'
25.0'
40.0'40.3'
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FIGURELYMAN RESERVOIR
FOUNDATION CONDITIONS - NEW TANK SITE
BOZEMAN, MONTANA
4
LYMAN RESERVOIR
NOTES:
1) AS WE UNDERSTAND IT, IF THE SELECTED IMPROVEMENTALTERNATIVE IS A NEW TANK, IT WILL BE LOCATED TO THE EASTOF THE EXISTING RESERVOIR IN THE GENERAL AREA BETWEEN
BH-3, BH-5, BH-6, AND BH-7.
2) AS WE UNDERSTAND IT, THE NEW TANK ALTERNATIVE WOULD
CONSIST OF A 170' (±) DIAMETER, 30' (±) TALL, CONCRETE
STRUCTURE THAT WOULD BE CLOSE TO FULLY BURIED ON THEUPSLOPE SIDE AND PARTIALLY BURIED ON THE DOWNSLOPE SIDE.
3) BASED ON PRELIMINARY DESIGN CONCEPTS, THE BOTTOM OFTHE TANK COULD BE 30' (±) DEEP ON THE UPSLOPE SIDE AND23' (±) DEEP ON THE DOWNSLOPE SIDE.
N
BASE MAP:
MICROSOFT BING AERIAL IMAGERY
LEGEND
BOREHOLE DEPTH
(IN FEET)
BH-#
XX.X'
BOREHOLE LOCATION
(BH-1 THROUGH BH-7)
BH-1
38.5'
BH-2
51.5'
BH-3
51.5'
BH-4
40.3'
BH-5
71.5'
BH-6
70.9'
BH-7
70.2'
EXISTING RESERVOIR
POSSIBLE NEW
TANK LOCATION
COLOR KEY
TOPSOIL
CLAY (EMBANKMENT FILL)
SILT/CLAY
SILT/CLAY WITH GRAVEL SEAMS
GRAVEL WITH SILT/CLAY SEAMS
SAND & GRAVEL
0.0'1.0'
9.0'
19.0'
32.0'
45.0'
64.0'
70.2'
0.0'1.0'
15.0'
21.0'
24.0'
41.0'
63.0'
70.9'
47.5'
0.0'1.0'
15.0'
20.0'
27.5'
40.0'
61.0'
71.5'
46.0'
10.0'
31.0'
42.0'
50.0'
55.0'
0.0'1.5'
20.0'
30.0'
45.0'
40.0'
51.5'
PROBABLE FOUNDATION BEARING CONDITIONS UNDER NEW TANK SITE
BH-3: SOILS FROM 25' TO 45' CONSIST OF SILT/CLAY AND GRAVEL WITH SILT/CLAY SEAMS.
BH-5: SOILS FROM 30' TO 50' CONSIST OF SILT/CLAY WITH GRAVEL SEAMS AND THINNER LAYERS OF SILT/CLAY AND SAND/GRAVEL.
BH-6: SOILS FROM 23' TO 43' CONSIST OF SILT/CLAY WITH GRAVEL SEAMS AND THINNER LAYERS SILT/CLAY AND SAND/GRAVEL.
BH-7: SOILS FROM 25' TO 45' CONSIST OF SILT/CLAY WITH GRAVEL SEAMS AND SAND/GRAVEL.
PURPOSE OF FIGURE 4:
TO SHOW THE PROBABLE FOUNDATION BEARING CONDITIONSAT FOOTING/SLAB GRADE AND WITHIN ABOUT 20' (±) BELOW THEBOTTOM OF THE NEW TANK. THE DEPTH RANGES THAT ARESHOWN ASSUME A BOTTOM OF TANK DEPTH OF 23' AT BH-6,25' AT BH-3, 25' AT BH-7, AND 30' AT BH-5.
25.0'
45.0'
PROBABLEFOUNDATIONBEARINGCONDITIONS
25.0'
45.0'
PROBABLEFOUNDATIONBEARINGCONDITIONS 23.0'
43.0'
PROBABLE
FOUNDATION
BEARINGCONDITIONS
30.0'
50.0'
PROBABLEFOUNDATIONBEARINGCONDITIONS
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FIGURELYMAN RESERVOIR
EXISTING EMBANKMENT FILL SECTION
BOZEMAN, MONTANA
5
LYMAN RESERVOIR
NOTES:
1) FIGURE 5 SHOWS THE EXISTING GEOMETRY OF THE RESERVOIR ANDDOWNSLOPE EMBANKMENT FILL SECTION.
2) THIS CROSS SECTION IS THE BASIS FOR OUR SLOPE STABILITY MODELAND ANALYSIS.
3) WITHIN THE SLOPE STABILITY MODEL, SOIL STRENGTH PARAMETERS
WERE ASSIGNED TO THE EMBANKMENT FILL MATERIAL AND UNDERLYING
NATIVE SUBGRADE SOILS.
4) SEVERAL SLOPE STABILITY ANALYSES WERE PERFORMED FOR DIFFERINGGROUNDWATER SCENARIOS WITHIN AND BELOW THE EMBANKMENT FILLMATERIAL.
5) ON 3/12/26, WE MEASURED A GROUNDWATER DEPTH OF 26.4' IN BH-1. THISIS THE HIGHEST GROUNDWATER LEVEL THAT WAS MEASURED IN BH-1AND BH-2, BOTH OF WHICH ARE LOCATED WITHIN THE EMBANKMENT FILLSECTION AREA ON THE DOWNSLOPE SIDE OF THE EXISTING RESERVOIR.THE 26.4' GROUNDWATER DEPTH IS APPROXIMATELY 1.4' BELOW THEBOTTOM OF THE EMBANKMENT FILL/NATIVE SUBGRADE SOIL INTERFACE.
N
EXISTING
RESERVOIR
EXISTING
EMBANKMENT
FILL SECTION
NATIVESUBGRADESOILS
NOTE:
DEPENDING ON LOCATION, THEEMBANKMENT FILL HEIGHT RANGESFROM ± 21.0' TO ± 25.0'. FOR THEPURPOSE OF OUR SLOPE STABILITYANALYSIS, WE MODELED A ± 25.0'FILL HEIGHT.
NOTE:
DURING RE-FILLING OF THE RESERVOIR IN EARLY MARCH
2026, GROUNDWATER LEVELS ROSE SIGNIFICANTLY
UNDER/AROUND THE RESERVOIR AS A RESULT OF A LEAK INTHE INTERIOR LINER AND THE CONCRETE RESERVOIR SHELL.PRIOR TO OPENING THE LINER DRAIN VALVE ON 3/12/26, THEHIGHEST MEASURED "MOUNDED" GROUNDWATER LEVEL INMW-1 WAS AT ± 26.4'. MW-1 IS LOCATED WITHIN THE EXISTINGEMBANKMENT FILL SECTION ON THE DOWNSLOPE SIDE OFTHE RESERVOIR.
NOTE:
PRIOR TO EMPTYING AND RE-FILLING THERESERVOIR IN FEBRUARY AND MARCH 2026, THEHIGHEST MEASURED "NATURAL" GROUNDWATERLEVEL IN MW-2 WAS AT ± 45.1' ON 12/18/25. MW-2 ISLOCATED WITHIN THE EXISTING EMBANKMENT FILLSECTION ON THE DOWNSLOPE SIDE OF THE
RESERVOIR.
BOREHOLES AND MONITORING WELLS:
1) TWO BOREHOLES WERE DRILLED WITHIN THE EXISTING EMBANKMENTFILL SECTION. THESE INCLUDED BH-1 AND BH-2. SEE FIGURE 1 FOR THEBOREHOLE LOCATIONS.
2) BH-1 WAS 38.5' DEEP AND BH-2 WAS 51.5' DEEP.
3) MONITORING WELLS WERE INSTALLED IN EACH OF THE BOREHOLES AND
ARE IDENTIFIED AS MW-1 AND MW-2. SEE FIGURE 2 FOR THE MONITORING
WELL LOCATIONS.
4) MW-1 IS 38.5' DEEP AND MW-2 IS 50.0' DEEP.
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FIGURELYMAN RESERVOIR
SUMMARY OF SLOPE STABILITY ANALYSES
BOZEMAN, MONTANA
6
LYMAN RESERVOIR
NOTES:
1) FIGURE 6 SHOWS EIGHT SLOPE STABILITY SCENARIOS THAT WERE MODELED AND EVALUATED.
2) PER ACCEPTED DESIGN STANDARDS, A FACTOR OF SAFETY OF 1.5 (OR HIGHER) IS CONSIDERED STABLE FOR STATIC CONDITIONS.
3) PER ACCEPTED DESIGN STANDARDS, A FACTOR OF SAFETY OF 1.1 (OR HIGHER) IS CONSIDERED STABLE FOR SEISMIC CONDITIONS.
4) FOR SCENARIOS 1-5, THE EXISTING 1.57H:1V EMBANKMENT FILL SLOPE GEOMETRY IS MODELED.
5) FOR SCENARIOS 6-8, NEW 2H:1V, 2.5H:1V, AND 3H:1V EMBANKMENT FILL SLOPE GEOMETRIES ARE MODELED.
6) THE VARIABLE FOR ALL EIGHT SCENARIOS IS THE GROUNDWATER LOCATION (i.e., THE PIEZOMETRIC SURFACE).
7) FOR THE SEISMIC ANALYSES, WE USED A HORIZONTAL SEISMIC COEFFICIENT OF 0.15, WHICH CORRESPONDS TO A 500-YEAREARTHQUAKE EVENT IN BOZEMAN.
8) SEE THE TABLE IN THE BOTTOM LEFT CORNER OF THIS FIGURE FOR A SUMMARY OF OUR SLOPE STABILITY RESULTS (FOR STATICAND SEISMIC CONDITIONS) FOR ALL EIGHT SCENARIOS.
9) FOR THE DETAILED SLOPE STABILITY ANALYSIS OF EACH OF THE EIGHT SCENARIOS, SEE THE ATTACHED SLOPE STABILITY
EXHIBITS A-H.
10) SEE FIGURES 7-9 FOR CROSS SECTIONS SHOWING THE GEOMETRY, DIMENSIONS, AND MATERIAL QUANTITIES FOR SCENARIOS 6-8
(OPTIONS 1, 2, AND 3 FOR NEW 2H:1V, 2.5H:1V, AND 3H:1V SLOPE GEOMETRY).
N
PURPOSE OF SCENARIOS 6-8:
TO EVALUATE IF FLATTENING THE EMBANKMENT FILLSLOPE SIGNIFICANTLY IMPROVES THE FACTOR OFSAFETY. THE WORST CASE GROUNDWATERCONDITION (HIGH-LEVEL LEAK) WAS MODELED.
EXISTING
RESERVOIR
EXISTING
EMBANKMENT
FILL SECTION
NATIVESUBGRADESOILS
SUMMARY OF MODELED SLOPE STABILITY SCENARIOS:
SCENARIO 1: DRY - GROUNDWATER WELL BELOW BOTTOM OF RESERVOIR.
(EXISTING 1.57H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 2: GROUNDWATER AT BOTTOM OF RESERVOIR IN NATIVE SUBGRADE SOILS.(EXISTING 1.57H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 3: GROUNDWATER ABOVE BOTTOM OF RESERVOIR AT INTERFACE OF NATIVE SUBGRADE SOILS AND EMBANKMENT FILL SECTION.(EXISTING 1.57H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 4: MID-LEVEL LEAK ON SW SIDE OF RESERVOIR AND PARTIALLY SATURATED EMBANKMENT FILL SECTION.(EXISTING 1.57H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 5: HIGH-LEVEL LEAK ON SW SIDE OF RESERVOIR AND PARTIALLY SATURATED EMBANKMENT FILL SECTION.
(EXISTING 1.57H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 6: HIGH-LEVEL LEAK ON SW SIDE OF RESERVOIR AND PARTIALLY SATURATED EMBANKMENT FILL SECTION.
(OPTION 1 - NEW 2H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 7: HIGH-LEVEL LEAK ON SW SIDE OF RESERVOIR AND PARTIALLY SATURATED EMBANKMENT FILL SECTION.(OPTION 2 - NEW 2.5H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SCENARIO 8: HIGH-LEVEL LEAK ON SW SIDE OF RESERVOIR AND PARTIALLY SATURATED EMBANKMENT FILL SECTION.(OPTION 3 - NEW 3H:1V EMBANKMENT FILL SLOPE GEOMETRY)
SUMMARY OF RESULTS (EFFECTIVE STRESS)
SCENARIO STATIC FS SEISMIC FS
1 1.829 1.395
2 1.829 1.396
3 1.705 1.257
4 1.649 1.221
5 1.582 1.171
6 1.686 1.193
7 1.823 1.219
8 1.960 1.245
NOTE:
DEPENDING ON LOCATION, THEEMBANKMENT FILL HEIGHT RANGESFROM ± 21.0' TO ± 25.0'. FOR THE
PURPOSE OF OUR SLOPE STABILITY
ANALYSIS, WE MODELED A ± 25.0'
FILL HEIGHT.
NOTES:
1) THE FACTOR OF SAFETY (FS) RESULTS FOR SCENARIOS 1 - 8ARE BASED ON EFFECTIVE STRESS SOIL PARAMETERS.
2) WE ALSO ANALYZED AND DOUBLE CHECKED SCENARIOS 1 - 8USING TOTAL STRESS SOIL PARAMETERS.
3) BASED ON THE ANALYSIS, THE FACTOR OF SAFETY (FS) RESULTSFOR THE TOTAL STRESS SOIL PARAMETERS WERE FOUND TO BEAPPROXIMATELY THE SAME AND/OR A LITTLE HIGHER.
4) FOR THIS REASON, WE ARE REPORTING THE LOWER AND MORE
CONSERVATIVE FACTOR OF SAFETY (FS) RESULTS FOR
EFFECTIVE STRESS SOIL PARAMETERS.
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FIGURELYMAN RESERVOIR
OPTION 1 - 2H:1V SLOPE IMPROVEMENT
BOZEMAN, MONTANA
7
LYMAN RESERVOIRN
NOTES:
1) FIGURE 7 SHOWS OPTION 1 FOR SLOPE IMPROVEMENT, WHICH CONSISTS OF FLATTENING THE EXISTING 1.57H:1V SLOPE TO A NEW 2H:1V SLOPE CONFIGURATION FOR INCREASED SLOPE STABILITY.
2) THE PURPOSE OF THIS FIGURE IS TO SHOW THE APPROXIMATE TOE WIDTH AND MATERIAL QUANTITY OF THE SLOPE FLATTENING WORK.
3) THIS FIGURE IS FOR CONCEPTUAL PURPOSES ONLY AND SHOWS A NEAT LINE AREA OF NEW EMBANKMENT FILL.
4) THIS FIGURE DOES NOT SHOW PROPER EXCAVATION AND BENCHING AT BOTTOM OF NEW EMBANKMENT FILL AND ALONG SIDE SLOPE OF EXISTING EMBANKMENT FILL.
NATIVESUBGRADE SOILS
EXISTINGRESERVOIR
EXISTINGEMBANKMENTFILL SECTION
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FIGURELYMAN RESERVOIR
OPTION 2 - 2.5H:1V SLOPE IMPROVEMENT
BOZEMAN, MONTANA
8
LYMAN RESERVOIRN
NOTES:
1) FIGURE 8 SHOWS OPTION 2 FOR SLOPE IMPROVEMENT, WHICH CONSISTS OF FLATTENING THE EXISTING 1.57H:1V SLOPE TO A NEW 2.5H:1V SLOPE CONFIGURATION FOR INCREASED SLOPE STABILITY.
2) THE PURPOSE OF THIS FIGURE IS TO SHOW THE APPROXIMATE TOE WIDTH AND MATERIAL QUANTITY OF THE SLOPE FLATTENING WORK.
3) THIS FIGURE IS FOR CONCEPTUAL PURPOSES ONLY AND SHOWS A NEAT LINE AREA OF NEW EMBANKMENT FILL.
4) THIS FIGURE DOES NOT SHOW PROPER EXCAVATION AND BENCHING AT BOTTOM OF NEW EMBANKMENT FILL AND ALONG SIDE SLOPE OF EXISTING EMBANKMENT FILL.
NATIVESUBGRADE SOILS
EXISTING
RESERVOIR
EXISTING
EMBANKMENT
FILL SECTION
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FIGURELYMAN RESERVOIR
OPTION 3 - 3H:1V SLOPE IMPROVEMENT
BOZEMAN, MONTANA
9
LYMAN RESERVOIR
NOTES:
1) FIGURE 9 SHOWS OPTION 3 FOR SLOPE IMPROVEMENT, WHICH CONSISTS OF FLATTENING THE EXISTING 1.57H:1V SLOPE TO A NEW 3H:1V SLOPE CONFIGURATION FOR INCREASED SLOPE STABILITY.
2) THE PURPOSE OF THIS FIGURE IS TO SHOW THE APPROXIMATE TOE WIDTH AND MATERIAL QUANTITY OF THE SLOPE FLATTENING WORK.
3) THIS FIGURE IS FOR CONCEPTUAL PURPOSES ONLY AND SHOWS A NEAT LINE AREA OF NEW EMBANKMENT FILL.
4) THIS FIGURE DOES NOT SHOW PROPER EXCAVATION AND BENCHING AT BOTTOM OF NEW EMBANKMENT FILL AND ALONG SIDE SLOPE OF EXISTING EMBANKMENT FILL.
N
NATIVESUBGRADE SOILS
EXISTINGRESERVOIR
EXISTINGEMBANKMENTFILL SECTION
Figure 10
25-084 March 2026
Lyman Reservoir
Preliminary Foundation Detail - New Concrete Tank
Bozeman, Montana
Civil Engineering
Geotechnical Engineering
Land Surveying
32 Discovery Drive
Bozeman, MT 59718
Phone: (406) 582-0221
Fax: (406) 582-5770
Finished Grade To Slope Away @ 5% (min.) Within 10’ Of Wall. Upper 4” - 6” Of Backfill Should Consist Of Low Permeable Topsoil.
Reviewed By: __________________
LSE, 3/25/26
Native Silt/Clay Soils(Suitable Bearing Material)
Embankment Site Fill(On-Site Excavated Soils)
No Scale (Parts Of This Exhibit Have Been Exaggerated For Clarity)
Geotechnical Notes: 1) Figure 10 Provides Our Preliminary Foundation Recommendations For A New Partially Buried, Concrete Tank. To Minimize Differential Settlement Potential Due To Varying Foundation Bearing Soil Conditions, The Recommendations Include A Concrete Mat Slab Foundation Underlain By A Minimum Of 12 Inches Of Structural Fill And Ground Improvement Elements Under Perimeter Wall Line Loads And Interior Column Point Loads.
Legend
Low Permeable Topsoil
Granular Structural Fill (*)Vib. Compact To 97% (min.).1” Minus CleanCrushed Rock
Ground Improvement(Rammed Aggregate Pier Or Vibro Stone Column)
Exterior Wall Backfill(On-Site Excavated Soils)
Native Sand/Gravel Soils (Suitable Bearing Material) Native Topsoil
Concrete Mat Slab
Existing Ground
Perimeter Wall of Concrete Tank (typ.)
Interior Column ForRoof Support (typ.)
Finished Floor Elev. (Tank Floor)
Downslope SideOf Tank (typ.)
Upslope SideOf Tank (typ.)
Based On Groundwater Monitoring, Groundwater Levels Are Anticipated To Be At Least 50’ Deep (Below Ex. Grades)During Most Of The Year.
Geocomposite Drainage PanelsAround PerimeterOf Tank (typ.)
(*) Granular Structural Fill Can Consist Of 3”-Minus Sandy (Pitrun) Gravel Or 1.5”-Minus Crushed (Roadmix) Gravel
8 oz. Non-WovenFabric (typ.)
2’ (min.)
6” FtgDrain
Silt/Clay Subgrade Soils(Re-Compacted To DenseAnd Unyielding Condition).
Ground Improvement Under Perimeter Wall Line Loads (typ.)
Strip Topsoil PriorTo Placing Site Fill.
Based On Boreholes,Alternating Layers Of Silt/Clay Soils And Sand/Gravel Soils To A Depth Of At Least 70’.
The Ground Improvement System (Ie. Diameter, Depth, & Spacing) Shall Be Designed For A Foundation Bearing Pressure Of 4,000 psf.
For Cost Estimating Purposes, We Recommend Assuming Rammed Aggregate Piers Or Vibro Stone Columns Will Have A Maximum Length Of 20’, Will Have A Diameter Of 24” To 30”, Will Be Installed At A Spacing Of 7.0’ On-Center, And Will Be Constructed Using 1.5”-Minus Crushed Roadmix Gravel.
Ground Improvement Under Interior Column Point Loads (typ.)
Sand/Gravel Subgrade Soils(Re-Compacted To DenseAnd Unyielding Condition).
Summary Of Soil Conditions:
1) The Soils Conditions Across The New Tank Site Consist Of Alternating Layers Of Silt/Clay Soils And Sand/Gravel Soils. The Soils Range From Silt/Clay To Silt/Clay w/ Gravel Seams To Gravel w/ Silt/Clay Seams To Sand & Gravel.
2) The Soil Layers Are Not Uniform And Continuous Across The Site. Depending On The Location, They Vary In Composition, Depth, And Thickness.
3) In Some Areas, Tank Subgrade And Foundation Bearing Soils Will Be Silt/Clay; While In Other Areas, They Will Be Gravelly.
Concrete Mat Slab Foundation (Assumed Thickness Is 12” To 14”)
12” (min.) Structural Fill Layer Under Concrete Mat Slab (typ.)
FIGURECivil Engineering
Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
GEOLOGY MAP
BOZEMAN, MONTANA
11
N
LEGEND
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
LOG OF BH-1
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/12/2025 PAGE: 1 of 1
LOCATION: Bozeman, MT ELEVATION: 5039.77' DEPTH: 38.5' GW: Dry
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-1
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
{0.0'-1.5'}: Topsoil (Embankment Fill)Medium stiff; dark brown to black; organic
sandy CLAY with roots; slightly moist.
{1.5'-25.0'}: Clay (Embankment Fill)Stiff to soft; brown to black to greenish gray;sandy LEAN CLAY with scattered pebblesand small gravels; moist to very moist.
·Soft from ~10' to ~17'.
·Occasional pockets of sand/gravel.
·Percent Passing #200 on S1-B = 55.8%.·Atterberg on S1-B: Lean Clay (CL).·Percent Passing #200 on S1-F = 59.4%.
·Atterberg on S1-F: Lean Clay (CL).
{25.0'-34.0'}: Clay with Gravel (Native)Stiff; brown; sandy CLAY with occasional
seams of sand/gravel; moist to very moist.·The SSS from 29.5' to 31.0' wasnoticeably moister and clayier than theSSS from 24.5' to 26.0'.
{34.0'-38.5'}: Sand & Gravel (Native)Dense; orangey tan; silty SAND with gravel;moist.
·Auger refusal at 38.5'.
S1-A0.0' - 1.5'4/3/3(6)11.9%General Notes:1. BH-1 was located on the east sideof the existing embankment.2. We hit refusal on a randomcobble at about 4.0' so we had tomove over ± 5' and restart.3. MW-1 was installed to a depth of38.5'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.2. Drill rig was a B60X Mobile Rig.3. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Grinding in upper ± 4'.2. Smooth drilling from 4.5' to 15'.3. Smooth/fast drilling from 10' to15'.4. Chattering between 15' and 20'.5. Gravelly (grinding) around 20'.6. Smooth/tight drilling withchattering from 20' to 25'.7. Fast/smooth drilling (limitedchatter) with some tight zonesfrom 25' to 30'.8. Multiple layers of small gravels(chattering) from 30' to 35'.9. Bigger gravels (grinding) from 35'to 40'.10. Auger refusal at 38.5'.11. No groundwater encountered atthe bottom of hole (dry at 38.5'below EG).
End of Boring at 38.5'
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S1-B4.5' - 6.0'5/5/7(12)12.8%
S1-C9.5' - 11.5'
ShelbyTube
S1-D11.5' - 13.0'3/1/3(4)25.1%
S1-E14.5' - 16.5'ShelbyTube
S1-F16.5' - 18.0'3/5/8(13)21.1%
S1-G19.5' - 21.0'10/6/19(25)19.9%
S1-H24.5' - 26.0'4/4/6(10)15.2%
S1-I29.5' - 31.0'4/4/6(10)24.9%
S1-J34.5' - 36.0'15/16/22(38)9.4%
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/11/2025 PAGE: 1 of 2
LOCATION: Bozeman, MT ELEVATION: 5040.34' DEPTH: 51.5' GW: 48.2'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-2
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
S2-A0.0' - 1.5'7/9/8(17)16.6%General Notes:1. BH-2 was located on the west sideof the existing embankment.2. MW-2 was installed to a depth of50.25'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.3. Drill rig was a B60X Mobile Rig.4. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. The soil from approximately 10'to 20' consists of black, organicclay (buried topsoil?).2. Smooth/fast drilling in the upper± 25'.3. No additional driving pressurehad to be applied when pushingthe Shelby Tube from 15' to 17'.4. Hit a rock when pushing theShelby Tube from 25' to 26.25'(the tube collapsed).5. Chattering around 38' to 40'.6. Some grinding around 45'.7. Slower drilling below 45'.8. Groundwater encountered at 48.2'below EG.
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Water Resource EngineeringGeotechnical EngineeringCivil Engineering
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32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S2-B5.0' - 6.5'5/4/3(7)15.7%
S2-D15.0' - 17.0'
ShelbyTube
S2-E20.0' - 21.5'2/3/4(7)23.2%
S2-F25.0' - 26.3'ShelbyTube
S2-G26.3' - 27.8'7/10/11(21)10.7%
S2-I35.0' - 36.5'3/3/13(16)21.7%
S2-C10.0' - 11.5'2/3/7(10)23.6%
S2-H30.0' - 31.5'3/5/4(9)16.5%
{0.0'-1.5'}: Topsoil (Embankment Fill)Very stiff; dark brown to black; organic
sandy CLAY with roots; slightly moist.
{1.5'-25.0'}: Clay (Embankment Fill)Stiff to soft; brown to black to greenish gray;sandy LEAN CLAY with scattered pebblesand small gravels; moist to very moist.
·Soil turns black between 5' and 10' and
turns greenish gray around 15'.·Soft from ~12' to ~17'.·Occasional seams of sand/gravel.·Percent Passing #200 on S2-C = 59.0%.
·Atterberg on S2-C: Lean Clay (CL).
·Percent Passing #200 on S2-E = 55.6%.
·Atterberg on S2-E: Lean Clay (CL).
{25.0'-38.0'}: Clay with Gravel (Native)Stiff to very stiff; brown; sandy CLAY withoccasional zones of scattered pebbles andoccasional seams of sand/gravel; moist.
LOG OF BH-2
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
40.0
45.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/11/2025 PAGE: 2 of 2
LOCATION: Bozeman, MT ELEVATION: 5040.34' DEPTH: 51.5' GW: 48.2'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-2
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
S2-J40.0' - 41.5'8/11/12(23)15.9%
General Notes:1. BH-2 was located on the west sideof the existing embankment.3. MW-2 was installed to a depth of50.25'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.4. Drill rig was a B60X Mobile Rig.5. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. The soil from approximately 10'to 20' consists of black, organicclay (buried topsoil?).2. Smooth/fast drilling in the upper± 25'.3. No additional driving pressurehad to be applied when pushingthe Shelby Tube from 15' to 17'.4. Hit a rock when pushing theShelby Tube from 25' to 26.25'(the tube collapsed).5. Chattering around 38' to 40'.6. Some grinding around 45'.7. Slower drilling below 45'.8. Groundwater encountered at 48.2'below EG.End of Boring at 51.5'
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Water Resource EngineeringGeotechnical EngineeringCivil Engineering
Land Surveying
32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S2-K45.0' - 46.5'14/11/15(26)9.2%
S2-L50.0' - 51.5'19/37/32(69)11.7%
{25.0'-38.0'}: Clay with Gravel (Native)Stiff to very stiff; brown; sandy CLAY with
occasional zones of scattered pebbles andoccasional seams of sand/gravel; moist.
{38.0'-51.5'}: Sand & Gravel (Native)Medium dense to very dense; brown toorangey brown; clayey SAND with gravel toclayey sandy GRAVEL; slightly moist towet.
·Groundwater encountered at 48.2'.
LOG OF BH-2
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/11/2025 PAGE: 1 of 2
LOCATION: Bozeman, MT ELEVATION: 5048.04' DEPTH: 51.5' GW: Dry
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-3
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
{0.0'-1.5'}: TopsoilMedium stiff; dark brown; organic sandy
CLAY with roots; slightly moist.
{1.5'-20.0'}: Sand & Gravel with ClayMedium dense to dense; brown to orangeybrown; clayey SAND to clayey sandyGRAVEL with seams of clay; slightly moistto moist.
{20.0'-30.0'}: Clay
Stiff to very stiff; brown to gray with orangemottles; sandy CLAY; moist.
{30.0'-40.0'}: Sand & Gravel with ClayMedium dense to dense; brown to gray;clayey SAND to clayey sandy GRAVELwith seams of clay; slightly moist to moist.
S3-A0.0' - 1.5'4/3/3(6)15.5%General Notes:1. BH-3 was located on the east sideof the existing reservoir.2. BH-3 was started on 11/10/2025and finished on 11/11/2025(stopped for the day at 25').3. BH-3 generally had more sandand gravel than BH-4 (located onthe west side of the existingreservoir).4. MW-3 was installed to a depth of50.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.5. Drill rig was a B60X Mobile Rig.6. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Generally smooth/fast drillingwith limited chatter in the upper± 22'.2. Some scattered small gravels inthe tailings pile around 15'.3. Some grinding around 22'.4. Slower drilling around 24'.5. Chattering around 35'.6. Smooth/fast drilling at ± 40'(noticeably moister clay in theSSS from 40.0' to 41.5').7. Slower drilling with some zones ofchatter below 45'.8. No groundwater encountered atthe bottom of hole (dry at 51.5'below EG).
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Water Resource EngineeringGeotechnical EngineeringCivil Engineering
Land Surveying
32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S3-B5.0' - 6.5'8/10/13(23)9.2%
S3-D15.0' - 16.5'
S3-E20.0' - 21.5'4/5/13(18)23.1%
S3-F25.0' - 26.5'3/6/6(12)31.8%
S3-H35.0' - 36.5'18/29/18(47)7.9%
S3-C10.0' - 11.5'5/8/8(16)14.9%
S3-G30.0' - 31.5'21/15/13(28)12.9%
19/19/14(33)9.2%
LOG OF BH-3
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
40.0
45.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/11/2025 PAGE: 2 of 2
LOCATION: Bozeman, MT ELEVATION: 5048.04' DEPTH: 51.5' GW: Dry
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-3
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
{30.0'-40.0'}: Sand & Gravel with ClayMedium dense to dense; brown to gray;
clayey SAND to clayey sandy GRAVELwith seams of clay; slightly moist to moist.
{40.0'-45.0'}: ClayVery stiff; brown; sandy CLAY; moist.
{45.0'-51.5'}: Sand & Gravel with ClayDense to very dense; brown to gray; clayeySAND to clayey sandy GRAVEL with seams
of clay; slightly moist to moist.
S3-I40.0' - 41.5'7/8/10(18)22.6%
General Notes:1. BH-3 was located on the east sideof the existing reservoir.2. BH-3 was started on 11/10/2025and finished on 11/11/2025(stopped for the day at 25').3. BH-3 generally had more sandand gravel than BH-4 (located onthe west side of the existingreservoir).4. MW-3 was installed to a depth of50.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.5. Drill rig was a B60X Mobile Rig.6. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Generally smooth/fast drillingwith limited chatter in the upper± 22'.2. Some scattered small gravels inthe tailings pile around 15'.3. Some grinding around 22'.4. Slower drilling around 24'.5. Chattering around 35'.6. Smooth/fast drilling at ± 40'(noticeably moister clay in theSSS from 40.0' to 41.5').7. Slower drilling with some zones ofchatter below 45'.8. No groundwater encountered atthe bottom of hole (dry at 51.5'below EG).
End of Boring at 51.5'
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S3-J45.0' - 46.5'20/34/40(74)7.5%
S3-K50.0' - 51.5'14/17/18(35)13.6%
LOG OF BH-3
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/10/2025 PAGE: 1 of 2
LOCATION: Bozeman, MT ELEVATION: 5037.85' DEPTH: 40.3' GW: 27.0'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-4
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
S4-A0.0' - 1.5'3/3/3(6)18.7%General Notes:1. BH-4 was located adjacent to thedrainage on the west side of theexisting reservoir.2. BH-4 was generally the wettestand clayiest borehole.3. MW-4 was installed to a depth of39.2'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stickup height = ± 2'.4. Drill rig was a B60X Mobile Rig.5. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Generally smooth/fast drillingwith limited chatter zones from 0to 40' (bottom of hole).2. Drilling action was fairlyconsistent.3. Gravelly zone at 40' (SPT refusal).4. Groundwater was encountered at27.5' below EG at the time ofdrilling. Groundwater wasmeasured at 27.0' below EG thefollowing day.
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Water Resource EngineeringGeotechnical EngineeringCivil Engineering
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32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S4-B5.0' - 6.5'4/4/5(9)15.7%
S4-D15.0' - 16.5'
S4-E20.0' - 21.5'4/5/14(19)12.4%
S4-F25.0' - 26.5'5/14/19(33)27.6%
S4-H35.0' - 36.5'11/8/10(18)23.3%
S4-C10.0' - 11.5'3/3/3(6)19.9%
S4-G30.0' - 31.5'4/5/10(15)35.7%
8/11/7(18)21.0%
{0.0'-0.5'}: TopsoilMedium stiff; dark brown; organic sandy
CLAY with roots; slightly moist.
{0.5'-25.0'}: Clay with GravelMedium stiff to very stiff; brown to lightorangey tan to gray; sandy CLAY withoccasional seams of sand/gravel; moist.
{25.0'-40.0'}: ClayVery stiff to hard; brown; sandy CLAY;
moist to wet.·Groundwater measured at 27.0'.·Some sandy seams but no gravel seams.
LOG OF BH-4
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
40.0
45.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/10/2025 PAGE: 2 of 2
LOCATION: Bozeman, MT ELEVATION: 5037.85' DEPTH: 40.3' GW: 27.0'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-4
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
{25.0'-40.0'}: ClayVery stiff to hard; brown; sandy CLAY;
moist to wet.·Groundwater measured at 27.0'.·Some sandy seams but no gravel seams.
{40.0'-40.3'}: GravelHard; brown to light orangey tan; clayeysandy GRAVEL; wet.
·SSS refusal at 40.3'.
S4-I40.0' - 40.3'50for3.5"(Refusal)
25.2%
General Notes:1. BH-4 was located adjacent to thedrainage on the west side of theexisting reservoir.2. BH-4 was generally the wettestand clayiest borehole.3. MW-4 was installed to a depth of39.2'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.4. Drill rig was a B60X Mobile Rig.5. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Generally smooth/fast drillingwith limited chatter zones from 0to 40' (bottom of hole).2. Drilling action was fairlyconsistent.3. Gravelly zone at 40' (SPT refusal).4. Groundwater was encountered at27.5' below EG during drilling.Groundwater was measured at27.0' below EG the following day.
End of Boring at 40.3'
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LOG OF BH-4
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/13/2025 PAGE: 1 of 2
LOCATION: Bozeman, MT ELEVATION: 5058.65' DEPTH: 71.5' GW: 50.3'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-5
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
S5-A0.0' - 1.5'2/2/4(6)24.2%General Notes:1. BH-5 was located on the northside of the proposed new tank.2. MW-5 was installed to a depth of70.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.3. Drill rig was a B60X Mobile Rig.4. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Chattering and some grindingbetween 0 and 10'.2. The tailings pile between 0 and 10'consists of tan, slightly moist, siltySAND with scattered 1.5"-minussub-rounded gravels.3. Easy, smooth, fast drillingbetween 10' and 15' (no grinding).4. Smooth/tight drilling between 15'and 20' (tailings are moist, brown,clayey SAND).5. Fast/smooth drilling from 20' to25'.6. 400 to 500 psi down pressureapplied at 34' (tight drilling).7. 400 to 500 psi down pressure withchattering/vibrations from 35' to37'.8. 300 psi down pressure and fairlyslow with chattering from 40' to42.5'.9. 400 psi (±) down pressure from42.5' to 45'. Smooth/fast from42.5' to 43'. Smooth/tight withsmall gravels from 43' to 45'.10. Smooth/tight drilling from 45' to47.5'.11. Chattering at 49' to 50' (350 psi).12. Tailings from 40' to 50' consist ofbrown, moist, clayey SAND withscattered 1"-minus sub-angular toangular gravels.13. Fast/smooth drilling (200 psidown pressure) from 50' to 55'.14. Chattering/grinding from 56.5' to59' (small gravels).15. Smooth drilling with minorchatter from 60' to 62.5'.16. Smooth/fast drilling (200 psi downpressure) from 62.5' to 65'.17. Smooth/fast drilling with 500 psidown pressure from 65' to 70'.18. Groundwater was encountered atapproximately 55' below EG.
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Water Resource EngineeringGeotechnical EngineeringCivil Engineering
Land Surveying
32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S5-B5.0' - 6.5'13/22/20(42)5.8%
S5-D15.0' - 16.5'
S5-E20.0' - 21.5'5/9/15(24)20.4%
S5-F25.0' - 26.5'7/9/12(21)15.9%
S5-H30.0' - 31.5'9/11/15(26)14.8%
S5-C10.0' - 11.5'6/4/10(14)12.9%
S5-G27.5' - 29.0'4/6/6(12)24.4%
13/14/10(24)7.1%
S5-I32.5' - 34.0'29/23/16(39)14.0%
S5-J35.0' - 36.5'17/10/13(23)14.4%
{0.0'-1.0'}: TopsoilMedium stiff; dark brown; organic sandy
CLAY with roots; slightly moist.
{1.0'-10.0'}: Sand & GravelDense; tan; silty SAND with 1.5"-minusgravels; slightly moist.
{10.0'-15.0'}: SiltStiff; grayish brown; sandy SILT; slightlymoist.
{15.0'-20.0'}: Silt with Gravel
Very stiff; grayish brown; sandy SILT withscattered gravels; slightly moist.
{20.0'-27.5'}: Clay with GravelVery stiff; brown; sandy CLAY withstringers of sand/gravel; moist.
{27.5'-31.0'}: ClayStiff; brown; sandy CLAY; moist.
{31.0'-40.0'}: Clay with GravelVery stiff to hard; brown to light brown;sandy SILT/CLAY with stringers ofsand/gravel; moist.
LOG OF BH-5
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
40.0
45.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/13/2025 PAGE: 2 of 2
LOCATION: Bozeman, MT ELEVATION: 5058.65' DEPTH: 71.5' GW: 50.3'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-5
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
General Notes:1. BH-5 was located on the northside of the proposed new tank.2. MW-5 was installed to a depth of70.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.3. Drill rig was a B60X Mobile Rig.4. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Chattering and some grindingbetween 0 and 10'.2. The tailing pile between 0 and 10'consists of tan, slightly moist, siltySAND with scattered 1.5"-minussub-rounded gravels.3. Easy, smooth, fast drillingbetween 10' and 15' (no grinding).4. Smooth/tight drilling between 15'and 20' (tailings are moist, brown,clayey SAND).5. Fast/smooth drilling from 20' to25'.6. 400 to 500 psi down pressureapplied at 34' (tight drilling).7. 400 to 500 psi down pressure withchattering/vibrations from 35' to37'.8. 300 psi down pressure and fairlyslow with chattering from 40' to42.5'.9. 400 psi (±) down pressure from42.5' to 45'. Smooth/fast from42.5' to 43'. Smooth/tight withsmall gravels from 43' to 45'.10. Smooth/tight drilling from 45' to47.5'.11. Chattering at 49' to 50' (350 psi).12. Tailings from 40' to 50' consist ofbrown, moist, clayey SAND withscattered 1"-minus sub-angular toangular gravels.13. Fast/smooth drilling (200 psidown pressure) from 50' to 55'.14. Chattering/grinding from 56.5' to59' (small gravels).15. Smooth drilling with minorchatter from 60' to 62.5'.16. Smooth/fast drilling (200 psi downpressure) from 62.5' to 65'.17. Smooth/fast drilling with 500 psidown pressure from 65' to 70'.18. Groundwater was encountered atapproximately 55' below EG.
End of Boring at 71.5'
50.0
55.0
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60.0
65.0
70.0
S5-K37.5' - 39.0'9/13/27(40)14.2%
S5-M42.5' - 44.0'9/7/32(39)21.8%
S5-L40.0' - 41.5'22/37/41(78)8.0%
S5-N45.0' - 46.5'17/16/10(26)16.9%
S5-O47.5' - 49.0'5/7/8(15)21.9%
S5-Q52.5' - 54.0'14/11/17(28)17.4%
S5-P50.0' - 51.5'21/16/20(36)18.3%
S5-R55.0' - 56.5'14/15/17(32)20.7%
S5-S57.5' - 59.0'30/35/19(54)13.7%
S5-U62.5' - 64.0'7/8/19(27)27.7%
S5-T60.0' - 61.5'4/8/15(23)38.6%
S5-V65.0' - 66.5'6/10/15(25)30.2%
S5-W70.0' - 71.5'4/4/7(11)37.7%
{31.0'-40.0'}: Clay with GravelVery stiff to hard; brown to light brown;
sandy SILT/CLAY with stringers ofsand/gravel; moist.
{40.0'-42.0'}: Sand & GravelVery dense to medium dense; brown to lightbrown; silty sandy GRAVEL; moist.
{42.0'-46.0'}: Clay with GravelVery stiff to hard; brown to light brown;
sandy CLAY with stringers of sand/gravel;moist.
{46.0'-50.0'}: ClayStiff; brown; sandy CLAY; slightly moist tomoist.
{50.0'-55.0'}: Clay with GravelVery stiff to hard; orangey brown to brown;sandy CLAY with stringers of sand/gravel;moist.
{55.0'-61.0'}: Sand & GravelDense to very dense; brown; clayey SAND toclayey sandy GRAVEL; wet.
{61.0'-71.5'}: ClayVery stiff to stiff; brown; sandy CLAY; verymoist.
·Occasional thin seams of clayey SAND(no gravels).
LOG OF BH-5
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/17/2025 PAGE: 1 of 2
LOCATION: Bozeman, MT ELEVATION: 5054.58' DEPTH: 70.9' GW: 49.0'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE/LSE BORING: BH-6
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
S6-A0.0' - 1.5'3/3/5(8)23.0%General Notes:1. BH-6 was located on the southside of the proposed new tank.2. BH-6 was started on Friday11/14/2025 and completed onMonday 11/17/2025 (stopped forthe day at 30').3. MW-6 was installed to a depth of70.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.4. Drill rig was a B60X Mobile Rig.5. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Easy/fast drilling from 0 to 15'.2. Grinding/slow drilling (300 psi)from 15' to 21'.3. Smooth, easy, fast drilling (nochattering) from 21' to 23'.4. Smooth, slower, and tight with nochattering at 25' (500 psi).5. Slow/tight from 26' to 30'.6. Slow/tight with infrequent chatter(400 psi) from 30' to 32.5'.7. Slow/tight with very little chatter(250 psi) from 32.5' to 35'.8. Smooth from 35' to 35.5' (250 psi).9. Chattering (small gravels) from35.5' to 38.5' (250 - 300 psi).10. Smooth/fast drilling from 38.5' to41' (250 - 300 psi).11. Loud grinding (very gravelly)from 41' to 42.5' (300 psi).12. Lots of chatter (gravelly) from42.5' to 45' (250 - 300 psi).13. Fast/vibrations (very gravelly)from 45' to 47.5'.14. Very stiff/slow/smooth drillingfrom 47.5' to 50' (250 psi).15. Lots of chattering (small gravels)from 50' to 52.5'.16. Smooth/fast drilling with nochatter from 52.5' to 57.5'.17. Smooth/fast drilling with minorchatter from 57.5' to 60'.18. Smooth/tight/slow from 60' to 63'.19. Chattering/vibrations (gravelly)from 63' to 65'.20. Very slow/lots of vibrations/loudgrinding (big gravels) from 65' to69' with chattering (smallergravels) from 69' to 70'.21. Groundwater was encountered at± 50' below EG during drillingand was measured at 49.0' belowEG the following day.
15.0
20.0
25.0
30.0
35.0
Water Resource EngineeringGeotechnical EngineeringCivil Engineering
Land Surveying
32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S6-B5.0' - 6.5'4/4/4(8)16.4%
S6-D15.0' - 16.25'
S6-E20.0' - 21.5'9/14/16(30)12.8%
S6-G25.0' - 26.5'14/10/11(21)14.6%
S6-I30.0' - 31.5'16/17/22(39)9.8%
S6-C10.0' - 11.5'4/7/10(17)14.8%
S6-H27.5' - 29.0'12/14/9(23)17.3%
18/23/50 for 3"6.5%
S6-J32.5' - 34.0'6/9/20(29)18.8%
S6-K35.0' - 36.5'23/30/16(46)18.3%
(Refusal)
S6-F22.5' - 24.0'8/10/8(18)16.1%
{0.0'-1.0'}: TopsoilMedium stiff; dark brown; organic sandy
CLAY with roots; moist.
{1.0'-15.0'}: ClayMedium stiff to stiff; brown; sandy CLAY;moist to slightly moist.
{15.0'-21.0'}: Sand & GravelVery dense; brown to light brown; siltysandy GRAVEL; slightly moist.
{21.0'-24.0'}: Clay
Very stiff; brown; sandy CLAY; moist.
{24.0'-41.0'}: Clay with GravelVery stiff to stiff; brown to light brown;sandy CLAY with stringers of sand/gravel;moist to very moist.
LOG OF BH-6
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
40.0
45.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/17/2025 PAGE: 2 of 2
LOCATION: Bozeman, MT ELEVATION: 5054.58' DEPTH: 70.9' GW: 49.0'
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE/LSE BORING: BH-6
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
General Notes:1. BH-6 was located on the southside of the proposed new tank.2. BH-6 was started on Friday11/14/2025 and completed onMonday 11/17/2025 (stopped forthe day at 30').3. MW-6 was installed to a depth of70.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.4. Drill rig was a B60X Mobile Rig.5. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Easy/fast drilling from 0 to 15'.2. Grinding/slow drilling (300 psi)from 15' to 21'.3. Smooth, easy, fast drilling (nochattering) from 21' to 23'.4. Smooth, slower, and tight with nochattering at 25' (500 psi).5. Slow/tight from 26' to 30'.6. Slow/tight with infrequent chatter(400 psi) from 30' to 32.5'.7. Slow/tight with very little chatter(250 psi) from 32.5' to 35'.8. Smooth from 35' to 35.5' (250 psi).9. Chattering (small gravels) from35.5' to 38.5' (250 - 300 psi).10. Smooth/fast drilling from 38.5' to41' (250 - 300 psi).11. Loud grinding (very gravelly)from 41' to 42.5' (300 psi).12. Lots of chatter (gravelly) from42.5' to 45' (250 - 300 psi).13. Fast/vibrations (very gravelly)from 45' to 47.5'.14. Very stiff/slow/smooth drillingfrom 47.5' to 50' (250 psi).15. Lots of chattering (small gravels)from 50' to 52.5'.16. Smooth/fast drilling with nochatter from 52.5' to 57.5'.17. Smooth/fast drilling with minorchatter from 57.5' to 60'.18. Smooth/tight/slow from 60' to 63'.19. Chattering/vibrations (gravelly)from 63' to 65'.20. Very slow/lots of vibrations/loudgrinding (big gravels) from 65' to69' with chattering (smallergravels) from 69' to 70'.21. Groundwater was encountered at± 50' below EG during drillingand was measured at 49.0' belowEG the following day.End of Boring at 70.9'
50.0
55.0
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32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
60.0
65.0
70.0
S6-L37.5' - 39.0'17/5/4(9)19.7%
S6-N42.5' - 43.25'10.5%
S6-M40.0' - 41.5'2/17/26(43)10.5%
S6-O45.0' - 46.5'21/28/26(54)7.5%
S6-P47.5' - 49.0'11/14/11(25)18.9%
S6-R52.5' - 54.0'6/9/8(17)33.6%
S6-Q50.0' - 51.5'7/8/11(19)27.0%
S6-S55.0' - 56.5'6/6/10(16)25.3%
S6-T57.5' - 59.0'8/7/10(17)26.9%
S6-U60.0' - 61.5'4/6/10(16)31.2%
S6-V65.0' - 66.3'12.3%
S6-W70.0' - 70.9'17.8%
27/50 for 3"(Refusal)
28/49/50 for 4"(Refusal)
15/50 for 5"(Refusal)
{24.0'-41.0'}: Clay with GravelVery stiff to stiff; brown to light brown;
sandy CLAY with stringers of sand/gravel;moist to very moist.
{41.0'-47.5'}: Sand & GravelDense to very dense; brown; silty sandyGRAVEL; moist.
{47.5'-63.0'}: ClayVery stiff; brown to blue-ish gray; sandy
SILT/CLAY; moist to wet.
{63.0'-70.9'}: Sand & GravelVery dense; brown; silty sandyGRAVEL; wet.
LOG OF BH-6
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
5.0
10.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/18/2025 PAGE: 1 of 2
LOCATION: Bozeman, MT ELEVATION: 5060.55' DEPTH: 70.2' GW: Dry
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-7
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
S7-A0.0' - 1.5'3/4/5(9)22.7%General Notes:1. BH-7 was located east of theproposed new tank.2. MW-7 was installed to a depth of70.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.3. Drill rig was a B60X Mobile Rig.4. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Small gravels/chattering startingaround 8.5' or 9'.2. Grinding/slower drilling from 10'to 18.5' (1"-minus gravels).3. Smooth, stiff, tight drilling withno chattering (no gravels) from18.5' to 22'.4. Some grinding (gravels) from 22'to 24'.5. Generally applied 200 to 300 psidown pressure drilling the upper25'.6. Smooth, tight, slow-ish drillingwith no grinding from 25' to 27.5'(500 psi).7. Alternating between smoothdrilling and chattering from 27.5'to 32.5' (200 - 250 psi).8. Chattering (1.5-minus sandygravel) but fairly fast drillingfrom 32.5' to 40' (250 - 300 psi).9. Tailings got lighter in color (tanvs dark brown) and more gravellyat 39' (1.5"-minus silty sandyGRAVEL).10. Hard (grinding/slow drilling)from 40' to 42.5' (400 psi).11. Really hard (loud grinding) at41.5'.12. Fairly slow drilling from 42.5' to45' (500 psi).13. Softer again from 45' to 48'(smooth/fast drilling).14. Smooth/tight drilling from 48' to52.5' (300 - 400 psi).15. Fast/easy/smooth drilling from 55'to 57.5'.16. Smooth/tight drilling from 60' to64'.17. Gravelly again at 64' (grinding).18. Drill rig bucking at 65' (grinding).19. Smooth seam with no grindingfrom about 69' to 70'.20. Hard/grinding at ±70' (refusal).21. No groundwater encountered atbottom of hole (dry at 70.2' belowEG).
15.0
20.0
25.0
30.0
35.0
Water Resource EngineeringGeotechnical EngineeringCivil Engineering
Land Surveying
32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
S7-B5.0' - 6.5'3/4/4(8)
S7-D15.0' - 16.5'
S7-E20.0' - 21.5'6/10/16(26)12.2%
S7-F25.0' - 26.5'9/18/25(43)9.4%
S7-H30.0' - 31.5'16/10/9(19)15.2%
S7-C10.0' - 11.5'7/9/7(16)11.4%
S7-G27.5' - 29.0'15/23/33(56)9.4%
17/22/24(46)6.7%
S7-I32.5' - 34.0'28/43/40(83)4.1%
S7-J35.0' - 36.5'9/40/47(87)11.1%
{0.0'-1.0'}: TopsoilStiff; dark brown; organic sandy CLAY with
roots; moist.
{1.0'-9.0'}: Silt & ClayMedium stiff; brown to light brown; sandySILT/CLAY; moist.
{9.0'-19.0'}: Gravel with ClayMedium dense to dense; brown; silty sandyGRAVEL with occasional clay seams; moist.
{19.0'-32.0'}: Clay with Gravel
Very stiff to hard; brown; sandy CLAY withstringers of sand/gravel; moist.
{32.0'-45.0'}: Sand & GravelVery dense; brown to light brown to orangeybrown to purple-ish brown; silty sandyGRAVEL; slightly moist to moist.
LOG OF BH-7
DEPTH (FT)GEOLOGYLOGDESCRIPTIONOF MATERIALS
SAMPLESN(UNCOR)BLOWS/FTMOISTURECONTENTOTHER FIELD ORSAMPLEINFORMATION
40.0
45.0
PROJECT: Lyman Reservoir JOB #: 25-084 DATE: 11/18/2025 PAGE: 2 of 2
LOCATION: Bozeman, MT ELEVATION: 5060.55' DEPTH: 70.2' GW: Dry
DRILL TYPE: Hollow Stem Auger FIELD ENGINEER: JGE BORING: BH-7
DRILLER: Andrew (O'Keefe) CASING/HAMMER/SAMPLER: 8.75"OD/4"ID/140-lb hammer/2"OD SSS
General Notes:1. BH-7 was located east of theproposed new tank.2. MW-7 was installed to a depth of70.0'. The entire well is screenedaside from the upper 10 feet of thesoil profile. Stick up height = ± 2'.3. Drill rig was a B60X Mobile Rig.4. The beginning and end depths ofall soil layers are approximate.
Drilling Action Notes:1. Small gravels/chattering startingaround 8.5' or 9'.2. Grinding/slower drilling from 10'to 18.5' (1"-minus gravels).3. Smooth, stiff, tight drilling withno chattering (no gravels) from18.5' to 22'.4. Some grinding (gravels) from 22'to 24'.5. Generally applied 200 to 300 psidown pressure drilling the upper25'.6. Smooth, tight, slow-ish drillingwith no grinding from 25' to 27.5'(500 psi).7. Alternating between smoothdrilling and chattering from 27.5'to 32.5' (200 - 250 psi).8. Chattering (1.5-minus sandygravel) but fairly fast drillingfrom 32.5' to 40' (250 - 300 psi).9. Tailings got lighter in color (tanvs dark brown) and more gravellyat 39' (1.5"-minus silty sandyGRAVEL).10. Hard (grinding/slow drilling)from 40' to 42.5' (400 psi).11. Really hard (loud grinding) at41.5'.12. Fairly slow drilling from 42.5' to45' (500 psi).13. Softer again from 45' to 48'(smooth/fast drilling).14. Smooth/tight drilling from 48' to52.5' (300 - 400 psi).15. Fast/easy/smooth drilling from 55'to 57.5'.16. Smooth/tight drilling from 60' to64'.17. Gravelly again at 64' (grinding).18. Drill rig bucking at 65' (grinding).19. Smooth seam with no grindingfrom about 69' to 70'.20. Hard/grinding at ±70' (refusal).21. No groundwater encountered atbottom of hole (dry at 70.2' belowEG).
End of Boring at 70.2'
50.0
55.0
Water Resource EngineeringGeotechnical EngineeringCivil Engineering
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32 Discovery DriveBozeman, MT 59718Phone (406) 582-0221Fax (406) 582-5770www.alliedengineering.com
60.0
65.0
70.0
S7-K37.5' - 39.0'28/46/50(96)5.1%
S7-M42.5' - 44.0'6.1%
S7-L40.0' - 40.5'50 for 6"(Refusal)3.9%
S7-N45.0' - 46.5'15/15/14(29)7.6%
S7-O47.5' - 49.0'8/7/9(16)27.2%
S7-Q52.5' - 54.0'6/10/12(22)20.6%
S7-P50.0' - 51.5'10/10/11(21)26.2%
S7-R55.0' - 56.5'6/10/11(21)31.2%
S7-S57.5' - 59.0'4/5/6(11)32.6%
S7-T60.0' - 61.5'5/7/10(17)29.8%
S7-U65.0' - 66.5'11.6%
S7-V70.0' - 70.2'12.5%
19/30/40(70)
16/22/27(49)
50 for 2"(Refusal)
{32.0'-45.0'}: Sand & GravelVery dense; brown to light brown to orangey
brown to purple-ish brown; silty sandyGRAVEL; slightly moist to moist.
{45.0'-64.0'}: ClayStiff to very stiff; brown; sandy CLAY;moist to very moist.
{64.0'-70.2'}: Sand & GravelDense to very dense; brown; silty sandy
GRAVEL; moist.
LOG OF BH-7
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Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-1 WELL CONSTRUCTION
BOZEMAN, MONTANA
1
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-1
LOCATION INSTALLED: BH-1
DATE INSTALLED: 11/13/2025
INSTALLED BY: O'KEEFE DRILLING
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Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-2 WELL CONSTRUCTION
BOZEMAN, MONTANA
2
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-2
LOCATION INSTALLED: BH-2
DATE INSTALLED: 11/12/2025
INSTALLED BY: O'KEEFE DRILLING
EXHIBITCivil Engineering
Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-3 WELL CONSTRUCTION
BOZEMAN, MONTANA
3
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-3
LOCATION INSTALLED: BH-3
DATE INSTALLED: 11/11/2025
INSTALLED BY: O'KEEFE DRILLING
EXHIBITCivil Engineering
Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-4 WELL CONSTRUCTION
BOZEMAN, MONTANA
4
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-4
LOCATION INSTALLED: BH-4
DATE INSTALLED: 11/10/2025
INSTALLED BY: O'KEEFE DRILLING
EXHIBITCivil Engineering
Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-5 WELL CONSTRUCTION
BOZEMAN, MONTANA
5
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-5
LOCATION INSTALLED: BH-5
DATE INSTALLED: 11/14/2025
INSTALLED BY: O'KEEFE DRILLING
EXHIBITCivil Engineering
Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-6 WELL CONSTRUCTION
BOZEMAN, MONTANA
6
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-6
LOCATION INSTALLED: BH-6
DATE INSTALLED: 11/18/2025
INSTALLED BY: O'KEEFE DRILLING
EXHIBITCivil Engineering
Geotechnical EngineeringLand Surveying
32 DISCOVERY DRIVE . BOZEMAN, MT 59718PHONE (406) 582-0221 . FAX (406) 582-5770www.alliedengineering.com
LYMAN RESERVOIR
MW-7 WELL CONSTRUCTION
BOZEMAN, MONTANA
7
PROJECT NAME: LYMAN RESERVOIRPROJECT NUMBER: 25-084MONITORING WELL: MW-7
LOCATION INSTALLED: BH-7
DATE INSTALLED: 11/19/2025
INSTALLED BY: O'KEEFE DRILLING
MOISTURE CONTENT DETERMINATION (ASTM D2216)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 11/19/2025
Tested By: JGE
Sample Identification: S1‐A S1 ‐B S1 ‐D S1 ‐F S1 ‐G S1 ‐H S1 ‐I S1 ‐J
Exploration Location: BH‐1 BH ‐1 BH ‐1 BH ‐1 BH ‐1 BH ‐1 BH ‐1 BH ‐1
Sample Depth (ft): 0.0 ‐ 1.5 4.5 ‐ 6.0 11.5 ‐ 13.0 16.5 ‐ 18.0 19.5 ‐ 21.0 24.5 ‐ 26.0 29.5 ‐ 31.0 34.5 ‐ 36.0
Container Number: E D JJ KK I F UU K
Weight of Container: 31.62 31.74 30.89 31.18 31.76 31.68 30.96 31.71
Container + Wet Soil: 143.10 132.04 157.14 148.90 150.50 214.84 191.47 183.91
Container + Dry Soil: 131.27 120.63 131.78 128.42 130.80 190.71 159.48 170.89
Weight of Water: 11.83 11.41 25.36 20.48 19.70 24.13 31.99 13.02
Weight of Dry Soil: 99.65 88.89 100.89 97.24 99.04 159.03 128.52 139.18
Moisture Content: 11.9% 12.8% 25.1% 21.1% 19.9% 15.2% 24.9% 9.4%
Sample Identification: S2‐A S2 ‐B S2 ‐C S2 ‐E S2 ‐G S2 ‐H S2 ‐I S2 ‐J S2 ‐K S2 ‐L
Exploration Location: BH‐2 BH ‐2 BH ‐2 BH ‐2 BH ‐2 BH ‐2 BH ‐2 BH ‐2 BH ‐2 BH ‐2
Sample Depth (ft): 0.0 ‐ 1.5 5.0 ‐ 6.5 10.0 ‐ 11.5 20.0 ‐ 21.5 26.25 ‐ 27.75 30.0 ‐ 31.5 35.0 ‐ 36.5 40.0 ‐ 41.5 45.0 ‐ 46.5 50.0 ‐ 51.5
Container Number: RR A B J C OO QQ H G 2
Weight of Container: 31.23 31.95 31.54 31.63 31.73 31.07 31.18 31.56 31.53 30.51
Container + Wet Soil: 125.60 192.60 160.21 143.55 180.47 131.59 131.67 143.59 180.21 264.61
Container + Dry Soil: 112.16 170.79 135.66 122.48 166.09 117.37 113.73 128.25 167.72 240.02
Weight of Water: 13.44 21.81 24.55 21.07 14.38 14.22 17.94 15.34 12.49 24.59
Weight of Dry Soil: 80.93 138.84 104.12 90.85 134.36 86.30 82.55 96.69 136.19 209.51
Moisture Content: 16.6% 15.7% 23.6% 23.2% 10.7% 16.5% 21.7% 15.9% 9.2% 11.7%
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
MOISTURE CONTENT DETERMINATION (ASTM D2216)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 11/20/2025
Tested By: JGE
Sample Identification: S3‐A S3 ‐B S3 ‐C S3 ‐D S3 ‐E S3 ‐F S3 ‐G S3 ‐H S3 ‐I S3 ‐J
Exploration Location: BH‐3 BH ‐3 BH ‐3 BH ‐3 BH ‐3 BH ‐3 BH ‐3 BH ‐3 BH ‐3 BH ‐3
Sample Depth (ft): 0.0 ‐ 1.5 5.0 ‐ 6.5 10.0 ‐ 11.5 15.0 ‐ 16.5 20.0 ‐ 21.5 25.0 ‐ 26.5 30.0 ‐ 31.5 35.0 ‐ 36.5 40.0 ‐ 41.5 45.0 ‐ 46.5
Container Number: 1 3 4 5 6 7 EE Y O BB
Weight of Container: 30.37 30.56 30.17 30.39 30.54 30.28 48.81 50.84 48.87 48.30
Container + Wet Soil: 160.50 246.71 251.12 310.61 228.05 220.57 351.56 293.50 281.11 327.67
Container + Dry Soil: 143.02 228.53 222.40 287.09 191.00 174.68 317.04 275.66 238.31 308.18
Weight of Water: 17.48 18.18 28.72 23.52 37.05 45.89 34.52 17.84 42.80 19.49
Weight of Dry Soil: 112.65 197.97 192.23 256.70 160.46 144.40 268.23 224.82 189.44 259.88
Moisture Content: 15.5% 9.2% 14.9% 9.2% 23.1% 31.8% 12.9% 7.9% 22.6% 7.5%
Sample Identification: S3‐K S4 ‐A S4 ‐B S4 ‐C S4 ‐D S4 ‐E S4 ‐F S4 ‐G S4 ‐H
Exploration Location: BH‐3 BH ‐4 BH ‐4 BH ‐4 BH ‐4 BH ‐4 BH ‐4 BH ‐4 B H ‐4
Sample Depth (ft): 50.0 ‐ 51.5 0.0 ‐ 1.5 5.0 ‐ 6.5 10.0 ‐ 11.5 15.0 ‐ 16.5 20.0 ‐ 21.5 25.0 ‐ 26.5 30.0 ‐ 31.5 35.0 ‐ 36.5
Container Number: T P M DD GG S W R ZZ
Weight of Container: 51.47 49.11 50.52 48.50 48.18 50.37 50.38 50.51 49.37
Container + Wet Soil: 381.97 275.81 270.48 328.90 304.30 294.47 264.69 290.36 365.96
Container + Dry Soil: 342.34 240.15 240.61 282.45 259.80 267.58 218.33 227.28 306.12
Weight of Water: 39.63 35.66 29.87 46.45 44.50 26.89 46.36 63.08 59.84
Weight of Dry Soil: 290.87 191.04 190.09 233.95 211.62 217.21 167.95 176.77 256.75
Moisture Content: 13.6% 18.7% 15.7% 19.9% 21.0% 12.4% 27.6% 35.7% 23.3%
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
MOISTURE CONTENT DETERMINATION (ASTM D2216)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 11/20/2025 & 11/25/2025
Tested By: JGE
Sample Identification: S4‐I S5 ‐A S5 ‐B S5 ‐C S5 ‐D S5 ‐E S5 ‐F S5 ‐G S5 ‐H
Exploration Location: BH‐4 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5
Sample Depth (ft): 40.0 ‐ 40.3 0.0 ‐ 1.5 5.0 ‐ 6.5 10.0 ‐ 11.5 15.0 ‐ 16.5 20.0 ‐ 21.5 25.0 ‐ 26.5 27.5 ‐ 29.0 30.0 ‐ 31.5
Container Number: L H A QQ OO KK RR B JJ
Weight of Container: 31.68 31.56 31.96 31.18 31.06 31.18 31.23 31.54 30.89
Container + Wet Soil: 188.63 129.21 203.87 205.45 218.67 143.43 193.06 171.59 198.15
Container + Dry Soil: 157.07 110.19 194.50 185.50 206.18 124.38 170.86 144.11 176.61
Weight of Water: 31.56 19.02 9.37 19.95 12.49 19.05 22.20 27.48 21.54
Weight of Dry Soil: 125.39 78.63 162.54 154.32 175.12 93.20 139.63 112.57 145.72
Moisture Content: 25.2% 24.2% 5.8% 12.9% 7.1% 20.4% 15.9% 24.4% 14.8%
Sample Identification: S5‐I S5 ‐J S5 ‐K S5 ‐L S5 ‐M S5 ‐N S5 ‐O S5 ‐P S5 ‐Q S5‐R
Exploration Location: BH‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5
Sample Depth (ft): 32.5 ‐ 34.0 35.0 ‐ 36.5 37.5 ‐ 39.0 40.0 ‐ 41.5 42.5 ‐ 44.0 45.0 ‐ 46.5 47.5 ‐ 49.0 50.0 ‐ 51.5 52.5 ‐ 54.0 55.0 ‐ 56.5
Container Number: D I G F E J UU C K 2
Weight of Container: 31.72 31.76 31.53 31.70 31.63 31.63 30.96 31.73 31.71 30.52
Container + Wet Soil: 205.78 215.81 226.81 195.29 201.30 192.65 183.05 192.77 209.34 328.48
Container + Dry Soil: 184.42 192.70 202.54 183.19 170.88 169.39 155.74 167.83 182.99 277.42
Weight of Water: 21.36 23.11 24.27 12.10 30.42 23.26 27.31 24.94 26.35 51.06
Weight of Dry Soil: 152.70 160.94 171.01 151.49 139.25 137.76 124.78 136.10 151.28 246.90
Moisture Content: 14.0% 14.4% 14.2% 8.0% 21.8% 16.9% 21.9% 18.3% 17.4% 20.7%
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
MOISTURE CONTENT DETERMINATION (ASTM D2216)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 11/25/2025 & 12/2/2025
Tested By: JGE
Sample Identification: S5‐S S5 ‐T S5‐U S5 ‐V S5 ‐W S6 ‐A S6 ‐B S6 ‐C S6 ‐D
Exploration Location: BH‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐5 BH ‐6 BH ‐6 BH ‐6 BH ‐6
Sample Depth (ft): 57.5 ‐ 59.0 60.0 ‐ 61.5 62.5 ‐ 64.0 65.0 ‐ 66.5 70.0 ‐ 71.5 0.0 ‐ 1.5 5.0 ‐ 6.5 10.0 ‐ 11.5 15.0 ‐ 16.5
Container Number: 1 3 4 5 L J OO KK Q Q
Weight of Container: 30.37 30.55 30.18 30.38 31.67 31.62 31.06 31.18 31.18
Container + Wet Soil: 312.92 222.62 256.79 250.53 150.55 139.67 84.42 197.54 184.80
Container + Dry Soil: 278.94 169.17 207.64 199.53 118.01 119.43 76.91 176.03 175.38
Weight of Water: 33.98 53.45 49.15 51.00 32.54 20.24 7.51 21.51 9.42
Weight of Dry Soil: 248.57 138.62 177.46 169.15 86.34 87.81 45.85 144.85 144.20
Moisture Content: 13.7% 38.6% 27.7% 30.2% 37.7% 23.0% 16.4% 14.8% 6.5%
Sample Identification: S6‐E S6 ‐F S6 ‐G S6 ‐H S6 ‐I S6 ‐J S6 ‐K S6 ‐L S6 ‐M S6 ‐N
Exploration Location: BH‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6
Sample Depth (ft): 20.0 ‐ 21.5 22.5 ‐ 24.0 25.0 ‐ 26.5 27.5 ‐ 29.0 30.0 ‐ 31.5 32.5 ‐ 34.0 35.0 ‐ 36.5 37.5 ‐ 39.0 40.0 ‐ 41.5 42.5 ‐ 44.0
Container Number: D RR G UU JJ A B H C L
Weight of Container: 31.73 31.23 31.53 30.97 30.89 31.94 31.55 31.55 31.73 31.68
Container + Wet Soil: 214.02 210.95 177.87 192.38 214.75 165.89 163.16 197.74 222.34 196.55
Container + Dry Soil: 193.37 186.04 159.28 168.62 198.38 144.69 142.80 170.40 204.21 180.95
Weight of Water: 20.65 24.91 18.59 23.76 16.37 21.20 20.36 27.34 18.13 15.60
Weight of Dry Soil: 161.64 154.81 127.75 137.65 167.49 112.75 111.25 138.85 172.48 149.27
Moisture Content: 12.8% 16.1% 14.6% 17.3% 9.8% 18.8% 18.3% 19.7% 10.5% 10.5%
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
MOISTURE CONTENT DETERMINATION (ASTM D2216)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 12/2/2025 & 12/3/2025
Tested By: JGE
Sample Identification: S6‐O S6 ‐P S6 ‐Q S6‐R S6 ‐S S6 ‐T S6‐U S6 ‐V S6 ‐W
Exploration Location: BH‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6 BH ‐6
Sample Depth (ft): 45.0 ‐ 46.5 47.5 ‐ 49.0 50.0 ‐ 51.5 52.5 ‐ 54.0 55.0 ‐ 56.5 57.5 ‐ 59.0 60.0 ‐ 61.5 65.0 ‐ 66.4 70.0 ‐ 70.9
Container Number: I K E F 5 1 6 4 3
Weight of Container: 31.77 31.71 31.62 31.68 30.39 30.36 30.52 30.18 30.55
Container + Wet Soil: 189.02 205.76 201.76 187.04 272.59 258.68 250.41 311.75 288.54
Container + Dry Soil: 178.07 178.11 165.54 148.01 223.75 210.26 198.07 280.86 249.48
Weight of Water: 10.95 27.65 36.22 39.03 48.84 48.42 52.34 30.89 39.06
Weight of Dry Soil: 146.30 146.40 133.92 116.33 193.36 179.90 167.55 250.68 218.93
Moisture Content: 7.5% 18.9% 27.0% 33.6% 25.3% 26.9% 31.2% 12.3% 17.8%
Sample Identification: S7‐A S7 ‐B S 7 ‐C S7 ‐D S7 ‐E S7 ‐F S7 ‐G S7 ‐H S7 ‐I S7 ‐J
Exploration Location: BH‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7
Sample Depth (ft): 0.0 ‐ 1.5 5.0 ‐ 6.5 10.0 ‐ 11.5 15.0 ‐ 16.5 20.0 ‐ 21.5 25.0 ‐ 26.5 27.5 ‐ 29.0 30.0 ‐ 31.5 32.5 ‐ 34.0 35.0 ‐ 36.5
Container Number: J N/A C 2 OO RR A QQ K JJ
Weight of Container: 31.62 N/A 31.73 30.52 31.06 31.24 31.95 31.18 31.72 30.89
Container + Wet Soil: 157.55 N/A 196.73 169.36 197.72 199.61 217.57 185.71 218.15 224.47
Container + Dry Soil: 134.22 N/A 179.88 160.61 179.59 185.15 201.66 165.33 210.81 205.17
Weight of Water: 23.33 N/A 16.85 8.75 18.13 14.46 15.91 20.38 7.34 19.30
Weight of Dry Soil: 102.60 N/A 148.15 130.09 148.53 153.91 169.71 134.15 179.09 174.28
Moisture Content: 22.7% N/A 11.4% 6.7% 12.2% 9.4% 9.4% 15.2% 4.1% 11.1%
No Sample Left
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
MOISTURE CONTENT DETERMINATION (ASTM D2216)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 12/3/2025
Tested By: JGE
Sample Identification: S7‐K S7 ‐L S7 ‐M S7 ‐N S7 ‐O S7 ‐P S7 ‐Q S7‐R S7 ‐S S7 ‐T
Exploration Location: BH‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7 BH ‐7
Sample Depth (ft): 37.5 ‐ 39.0 40.0 ‐ 40.5 42.5 ‐ 44.0 45.0 ‐ 46.5 47.5 ‐ 49.0 50.0 ‐ 51.5 52.5 ‐ 54.0 55.0 ‐ 56.5 57.5 ‐ 59.0 60.0 ‐ 61.5
Container Number: E F D L UU KK G I H B
Weight of Container: 31.62 31.69 31.73 31.68 30.97 31.19 31.54 31.76 31.56 31.54
Container + Wet Soil: 222.07 193.04 208.37 97.74 202.34 156.56 170.37 224.59 194.87 187.66
Container + Dry Soil: 212.91 186.96 198.18 93.10 165.71 130.55 146.63 178.68 154.75 151.79
Weight of Water: 9.16 6.08 10.19 4.64 36.63 26.01 23.74 45.91 40.12 35.87
Weight of Dry Soil: 181.29 155.27 166.45 61.42 134.74 99.36 115.09 146.92 123.19 120.25
Moisture Content: 5.1% 3.9% 6.1% 7.6% 27.2% 26.2% 20.6% 31.2% 32.6% 29.8%
Sample Identification: S7‐U S7 ‐V
Exploration Location: BH‐7 BH ‐7
Sample Depth (ft): 65.0 ‐ 66.5 70.0 ‐ 70.2
Container Number: 3 4
Weight of Container: 30.55 30.16
Container + Wet Soil: 327.43 146.30
Container + Dry Soil: 296.54 133.41
Weight of Water: 30.89 12.89
Weight of Dry Soil: 265.99 103.25
Moisture Content: 11.6% 12.5%
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25-084
Sample Identification: S1-B from 4.5' to 6.0'
Soil Classification: Lean Clay (CL)
Date Sampled: 11/12/2025
Date Tested: 12/3/2025
Tested By: JGE
Test Results
Plastic Limit:20.4
Liquid Limit:31.7
Plasticity Index:11.3
Reviewed By:_________________
A-Line
CL
ML or OL
CH
MH or OH
CL-ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: S1‐F from 16.5’ to 18.0’
Soil Classification: Lean Clay (CL)
Date Sampled: 11/12/2025
Date Tested: 12/9/2025
Tested By: JGE
Test Results
Plastic Limit: 21.4
Liquid Limit: 35.8
Plasticity Index: 14.4
Reviewed By:_________________
A‐Line
CL
ML or OL
CH
MH or OH
CL‐ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: S2‐C from 10.0’ to 11.5’
Soil Classification: Lean Clay (CL)
Date Sampled: 11/11/2025
Date Tested: 12/4/2025
Tested By: JGE
Test Results
Plastic Limit: 21.7
Liquid Limit: 37.7
Plasticity Index: 16.0
Reviewed By:_________________
A‐Line
CL
ML or OL
CH
MH or OH
CL‐ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25-084
Sample Identification: S2-E from 20.0' to 21.5'
Soil Classification: Lean Clay (CL)
Date Sampled: 11/11/2025
Date Tested: 12/3/2025
Tested By: JGE
Test Results
Plastic Limit:21.5
Liquid Limit:39.1
Plasticity Index:17.6
Reviewed By:_________________
A-Line
CL
ML or OL
CH
MH or OH
CL-ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: S3‐F from 25.0’ to 26.5’
Soil Classification: Lean Clay (CL)
Date Sampled: 11/10/2025
Date Tested: 12/8/2025
Tested By: JGE
Test Results
Plastic Limit: 21.1
Liquid Limit: 41.4
Plasticity Index: 20.3
Reviewed By:_________________
A‐Line
CL
ML or OL
CH
MH or OH
CL‐ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25-084
Sample Identification: S5-G from 27.5' to 29.0'
Soil Classification: Lean Clay (CL)
Date Sampled: 11/13/2025
Date Tested: 12/15/2025
Tested By: JGE
Test Results
Plastic Limit:24.2
Liquid Limit:38.8
Plasticity Index:14.6
Reviewed By:_________________
A-Line
CL
ML or OL
CH
MH or OH
CL-ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25-084
Sample Identification: S6-G from 25.0' to 26.5'
Soil Classification: Lean Clay (CL)
Date Sampled: 11/14/2025
Date Tested: 12/15/2025
Tested By: JGE
Test Results
Plastic Limit:22.1
Liquid Limit:34.1
Plasticity Index:12.0
Reviewed By:_________________
A-Line
CL
ML or OL
CH
MH or OH
CL-ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
ATTERBERG LIMITS DETERMINATION (ASTM D4318)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: S7‐E from 20.0’ to 21.5’
Soil Classification: Lean Silt/Clay (CL‐ML)
Date Sampled: 11/18/2025
Date Tested: 12/16/2025
Tested By: JGE
Test Results
Plastic Limit: 17.6
Liquid Limit: 24.5
Plasticity Index: 6.9
Reviewed By:_________________
A‐Line
CL
ML or OL
CH
MH or OH
CL‐ML
ML
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 Plasticity IndexLiquid Limit
PLASTICITY CHART
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
PERCENT PASSING #200 SIEVE (ASTM D1140)
Project: Lyman Reservoir
Project Number: 25‐084
Sample Identification: See Below
Soil Classification: Varies
Date Sampled: 11/10/2025 ‐ 11/18/2025
Date Tested: 12/1/2025 ‐ 12/15/2025
Tested By: JGE
Sample Identification: S1‐B S1 ‐F S2 ‐C S2 ‐E S3 ‐F S5 ‐G S5 ‐O S6 ‐G S7 ‐E
Borehole Identification: BH‐1 BH ‐1 BH ‐2 BH ‐2 BH ‐3 BH ‐5 BH ‐5 BH ‐6 BH ‐7
Sample Depth (ft): 4.5 ‐ 6.0 16.5 ‐ 18.0 10.0 ‐ 11.5 20.0 ‐ 21.5 25.0 ‐ 26.5 27.5 ‐ 29.0 47.5 ‐ 49.0 25.0 ‐ 26.5 20.0 ‐ 21.5
Container Number: J C Z C B B UU G OO
Weight of Container (g): 499.3 486.4 498.1 485.9 347.0 31.54 30.96 31.53 31.06
Container + Wet Soil (g): 1052.4 N/A 1057.3 1112.5 565.8 171.59 183.05 177.87 197.72
Container + Dry Soil (g): 1021.2 1065.0 1053.8 1058.1 521.5 144.11 155.74 159.28 179.59
Weight of #200 Sieve (g): 986.4 986.4 976.3 996.8 976.1 986.5 976.5 986.5 976.5
Sieve Number: 2 2 ZZ 3 ZZ 2 ZZ 2 ZZ
Sieve + Dry Soil After Wash (g): 1216.9 1221.2 1204.3 1250.8 995 1032.9 1015.7 1072.5 1056.0
Weight of Water (g): 31.20 N/A 3.50 54.40 44.30 27.48 27.31 18.59 18.13
Weight of Dry Soil (g): 521.90 578.60 555.70 572.20 174.50 112.57 124.78 127.75 148.53
Water Content: 6.0% N/A 0.6% 9.5% 25.4% 24.4% 21.9% 14.6% 12.2%
Dry Soil After Wash (g): 230.50 234.80 228.00 254.00 18.90 46.40 39.20 86.00 79.50
Soil Weight Passing #200 Sieve (g):291.40 343.80 327.70 318.20 155.60 66.17 85.58 41.75 69.03
% Passing #200 Sieve: 55.8% 59.4% 59.0% 55.6% 89.2% 58.8% 68.6% 32.7% 46.5%
*Moisture contents on this sheet are not representative. Please refer to the moisture contents shown on the borehole logs.
Reviewed By:
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582‐0221
Fax (406) 582‐5770
January 21, 2026
Mr. Lee Evans
Allied Engineering
32 Discovery Drive
Bozeman, MT 59718
RE: GT Allied Engineering - Lyman Residence PO#25-084
Dear Mr. Evans,
On November 25, 2025, and December 18, 2025, three samples from the Lyman Reservoir 25-084
project were delivered to our Bozeman geotechnical testing laboratory in Bozeman. The samples were
identified as “BH-2A-C (15’-17’)”, “BH-2A-B (10’-12’)”, and “BH-2A-A (5’-7’)”, and were assigned
Laboratory identification Nos. G25363, G25364, and G25395, respectively
On December 2, 2025, four samples from the Lyman Reservoir 25-084 project were delivered to our
Bozeman geotechnical testing laboratory in Bozeman. And transported to our Helena location. The
samples were identified and assigned laboratory identification Nos. as seen in Table 1.
The testing was performed in general accordance with the following Standards:
• Consolidated Undrained Triaxial Compression Test for Cohesive Soils with PWP (ASTM D4767);
• pH and Marble of Soils (AASHTO T289, MT 232-04);
• Water-Soluble Sulfate in Soil (EPA 300.0).
The corrosivity testing results are presented in Table 1.
Table 1 – Corrosivity Testing Results
Lab ID Sample ID pH (s.u.) Marble pH (s.u.) Soluble Sulfate (%)
32535 BH-3 S3-E 7.8 8.0 0.0012
32536 BH-5 S5-C 7.8 8.1 0.0003
32537 BH-6 S6-B 7.7 8.0 0.0001
32538 BH-7 S7-B 7.7 7.8 0.0003
*pH and soluble sulfate testing were performed by Energy Labs of Helena.
The results for the Triaxial testing results are attached.
Thank you for using Pioneer Technical Services, Inc. for your geotechnical and materials testing
requirements. Please contact us if you have any questions or need any additional information regarding
this report.
Sincerely,
Travis Sammons
Project Scientist
Tested By: RJ / TS Checked By: JRR
TRIAXIAL SHEAR TEST REPORT
Pioneer Technical Services, Inc.
106 Pronghorn Trail, Suite A - Bozeman, MT 59718
Client: Allied Engineering
Project: Lyman Reservoir
Source of Sample: BH-2A-B/S2A-A
Sample Number: G25364/G25395 Depth: (10’-12’)/(5’-7’)
Proj. No.: 25-084 Date Sampled:
Type of Test:
CU with Pore Pressures
Sample Type: Shelby Tube
Description: Lean Clay, CL (Visual Classification)
Trace gravels present in Specimen #2 and #3.
Specimen #3 contained more gravels.
Assumed Specific Gravity= 2.65
Remarks:Specimen #1 and #2 were prepared from
BH-2A-B (10’-12’) and Specimen #3 was prepared
from BH-2A-A (5’-7’). Specific gravity is assumed
at 2.65.
Figure
Sample No.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Water Content, %
Dry Density, pcf
Saturation, %
Void Ratio
Diameter, in.
Height, in.
Total Pore Pr., psi
Total Pore Pr., psi
Strain rate, in./min.
Back Pressure, psi
Cell Pressure, psi
Fail. Stress, psi
Ult. Stress, psi
s1 Failure, psi
s3 Failure, psiInitialAt Test1
20.3
107.4
99.5
0.5401
2.88
5.72
20.4
107.4
100.0
0.5401
2.88
5.72
0.001
60.6
64.1
12.5
62.1
31.5
52.0
2.0
14.5
2
22.4
102.6
97.1
0.6118
2.85
5.79
22.2
104.1
100.0
0.5885
2.84
5.76
0.001
50.8
57.7
16.2
53.4
24.3
48.5
4.3
20.5
3
22.4
106.1
106.4
0.5587
2.86
5.80
20.4
107.4
100.0
0.5402
2.85
5.78
0.001
60.8
74.7
20.5
68.3
27.6
63.7
6.4
26.9Deviator Stress, psi0
10
20
30
40
50
60
Axial Strain, %
0 5 10 15 20
1
2
3Shear Stress, psi0
6
12
18
Total Normal Stress, psi
Effective Normal Stress, psi
0 6 12 18 24 30 36
C, psi
f, deg
Tan(f)
Total Effective
3.90
15.8
0.28
2.59
28.4
0.54
Tested By: RJ / TS Checked By: JRR
Client: Allied Engineering
Project: Lyman Reservoir
Source of Sample: BH-2A-B/S2A-A Depth: (10’-12’)/(5’-7’)Sample Number: G25364/G25395
Project No.: 25-084 Figure Pioneer Technical Services, Inc.q, psi0
8
16
24
p, psi
Stress Paths: Total Effective
0 8 16 24 32 40 48
Peak Strength
Total Effective
a=
a=
tan a=
3.75 psi
15.3 deg
0.27
2.27 psi
25.5 deg
0.48Total Pore Pressure Deviator Stress psi0
20
40
60
80
100
0% 8% 16%
1
Total Pore Pressure Deviator Stress psi0
20
40
60
80
100
0% 8% 16%
3 Total Pore Pressure Deviator Stress psi0
20
40
60
80
100
0% 8% 16%
2
Total Pore Pressure Deviator Stress psi0
20
40
60
80
100
0% 8% 16%
4
2025 and 2026 Groundwater Monitoring Data: Summary of 8 MWs
Project Name: Lyman Reservoir - Bozeman, MT
Project Number: 25-084
Location: See Maps
Date Installed: 11/10/25 through 11/18/25
Installed By: AESI
NOTES:
1) Ex. MW is located on NE (upslope) side of ex. reservoir and was installed by others many years ago.
2) MW-1 and MW-2 are located on SW (downslope) side of ex. reservoir and were installed by AESI in BH-1 and BH-2.
3) MW-3 and MW-4 are located on SE and NW sides of ex. reservoir and were installed by AESI in BH-3 and BH-4.
4) MW-5 through MW-7 are located to the east of the ex. reservoir and were installed by AESI in BH-5 through BH-7.
5) Ex. MW is 41 feet deep (below ex. ground grade) and has a steel casing height of 1.08 feet (above ex. ground grade).
6) MW-1 is 38.5 feet deep (below ex. ground grade) and has a steel casing height of 2.0 feet (above ex. ground grade).
7) MW-2 is 50 feet deep (below ex. ground grade) and as a steel casing height of 2.08 feet (above ex. ground grade).
8) MW-3 is 50 feet deep (below ex. ground grade) and has a steel casing height of 2.0 feet (above ex. ground grade).
9) MW-4 is 40 feet deep (below ex. ground grade) and has a steel casing height of 2.25 feet (above ex. ground grade).
10) MW-5 is 70 feet deep (below ex. ground grade) and has a steel casing height of 2.08 feet (above ex. ground grade).
11) MW-6 is 70 feet deep (below ex. ground grade) and has a steel casing height of 2.08 feet (above ex. ground grade).
12) MW-7 is 70 feet deep (below ex. ground grade) and has a steel casing height of 2.33 feet (above ex. ground grade).
13) Groundwater depths were monitored by AESI.
14) Groundwater depths (in the table below) are below existing ground (EG); and NOT below top of casing (TOC).
15) "Dry" MWs are noted as dry at bottom of the XX.X-foot MW depth.
16) Highest (shallowest) GW measurement (prior to emptying reservoir):
17) Highest (shallowest) GW measurement (during/after reservoir refilling):
Ex. MW MW-1 MW-2 MW-3 MW-4
Date Time Depth to GW Depth to GW Depth to GW Depth to GW Depth to GW
below EG below EG below EG below EG below EG
(feet) (feet) (feet) (feet) (feet)
11/19/25 N/A 34.0 Dry @ 38.5 48.2 Dry @ 50.0 27.0
12/18/25 N/A 32.7 Dry @ 38.5 45.1 Dry @ 50.0 25.8
01/06/26 N/A 33.1 Dry @ 38.5 46.3 Dry @ 50.0 26.4
01/20/26 N/A 33.0 Dry @ 38.5 46.8 Dry @ 50.0 26.0
01/27/26 N/A 33.2 Dry @ 38.5 46.9 Dry @ 50.0 26.4
02/03/26 N/A 33.3 Dry @ 38.5 47.0 Dry @ 50.0 26.4
02/10/26 N/A 33.6 Dry @ 38.5 47.4 Dry @ 50.0 27.0
02/18/26 N/A 35.0 Dry @ 38.5 49.9 Dry @ 50.0 29.2
02/20/26 N/A 35.6 Dry @ 38.5 50.0 Dry @ 50.0 30.1
02/24/26 N/A 36.2 Dry @ 38.5 Dry @ 50.0 Dry @ 50.0 31.8
03/03/26 N/A 37.0 Dry @ 38.5 Dry @ 50.0 Dry @ 50.0 33.1
03/05/26 N/A 37.3 Dry @ 38.5 Dry @ 50.0 Dry @ 50.0 33.4
03/06/26 N/A 36.9 Dry @ 38.5 Dry @ 50.0 Dry @ 50.0 33.2
03/09/26 N/A 31.9 Dry @ 38.5 37.4 45.2 20.3
03/10/26 N/A 29.7 32.1 31.6 36.3 16.4
03/12/26 N/A 27.1 26.4 26.9 33.0 13.5
03/13/26 N/A 26.6 26.8 27.2 32.6 14.0
03/16/26 N/A 26.3 27.3 27.4 32.9 15.4
03/23/26 N/A 28.1 32.2 30.6 35.5 19.9
04/02/26 N/A 26.6 33.0 32.0 33.5 18.4
04/15/26 N/A 24.8 32.5 31.8 31.6 16.3
04/29/26 N/A 24.2 33.1 32.5 30.8 16.1
05/13/26 N/A 24.5 34.6 33.7 30.9 17.1
05/27/26 N/A 25.3 36.4 35.2 31.5 18.1
06/17/26 N/A 27.8 38.1 38.5 33.9 21.3
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
Groundwater Monitoring Data: Page 1 of 2
2025 and 2026 Groundwater Monitoring Data: Summary of 8 MWs
Project Name: Lyman Reservoir - Bozeman, MT
Project Number: 25-084
Location: See Maps
Date Installed: 11/10/25 through 11/18/25
Installed By: AESI
NOTES:
1) Ex. MW is located on NE (upslope) side of ex. reservoir and was installed by others many years ago.
2) MW-1 and MW-2 are located on SW (downslope) side of ex. reservoir and were installed by AESI in BH-1 and BH-2.
3) MW-3 and MW-4 are located on SE and NW sides of ex. reservoir and were installed by AESI in BH-3 and BH-4.
4) MW-5 through MW-7 are located to the east of the ex. reservoir and were installed by AESI in BH-5 through BH-7.
5) Ex. MW is 41 feet deep (below ex. ground grade) and has a steel casing height of 1.08 feet (above ex. ground grade).
6) MW-1 is 38.5 feet deep (below ex. ground grade) and has a steel casing height of 2.0 feet (above ex. ground grade).
7) MW-2 is 50 feet deep (below ex. ground grade) and as a steel casing height of 2.08 feet (above ex. ground grade).
8) MW-3 is 50 feet deep (below ex. ground grade) and has a steel casing height of 2.0 feet (above ex. ground grade).
9) MW-4 is 40 feet deep (below ex. ground grade) and has a steel casing height of 2.25 feet (above ex. ground grade).
10) MW-5 is 70 feet deep (below ex. ground grade) and has a steel casing height of 2.08 feet (above ex. ground grade).
11) MW-6 is 70 feet deep (below ex. ground grade) and has a steel casing height of 2.08 feet (above ex. ground grade).
12) MW-7 is 70 feet deep (below ex. ground grade) and has a steel casing height of 2.33 feet (above ex. ground grade).
13) Groundwater depths were monitored by AESI.
14) Groundwater depths (in the table below) are below existing ground (EG); and NOT below top of casing (TOC).
15) "Dry" MWs are noted as dry at bottom of the XX.X-foot MW depth.
16) Highest (shallowest) GW measurement (prior to emptying reservoir):
17) Highest (shallowest) GW measurement (during/after reservoir refilling):
MW-5 MW-6 MW-7
Date Time Depth to GW Depth to GW Depth to GW
below EG below EG below EG
(feet) (feet) (feet)
11/19/25 N/A 50.3 49.0 Dry @ 70.0
12/18/25 N/A 49.7 48.7 Dry @ 70.0
01/06/26 N/A 50.0 48.9 Dry @ 70.0
01/20/26 N/A 50.0 49.0 Dry @ 70.0
01/27/26 N/A 50.1 49.0 Dry @ 70.0
02/03/26 N/A 50.2 49.1 Dry @ 70.0
02/10/26 N/A 50.5 49.2 Dry @ 70.0
02/18/26 N/A 51.8 50.3 Dry @ 70.0
02/20/26 N/A 52.3 50.7 Dry @ 70.0
02/24/26 N/A 52.9 51.3 Dry @ 70.0
03/03/26 N/A 53.8 52.4 Dry @ 70.0
03/05/26 N/A 54.0 52.8 Dry @ 70.0
03/06/26 N/A 54.0 53.0 Dry @ 70.0
03/09/26 N/A 51.1 51.8 Dry @ 70.0
03/10/26 N/A 49.1 51.1 Dry @ 70.0
03/12/26 N/A 46.2 48.8 Dry @ 70.0
03/13/26 N/A 45.6 47.9 Dry @ 70.0
03/16/26 N/A 45.0 46.1 Dry @ 70.0
03/23/26 N/A 45.9 45.7 Dry @ 70.0
04/02/26 N/A 44.6 44.2 Dry @ 70.0
04/15/26 N/A 42.9 42.7 Dry @ 70.0
04/29/26 N/A 42.2 41.5 Dry @ 70.0
05/13/26 N/A 42.2 41.0 Dry @ 70.0
05/27/26 N/A 42.9 41.5 Dry @ 70.0
06/17/26 N/A 45.1 43.3 Dry @ 70.0
32 Discovery Drive
Bozeman, MT 59718
Phone (406) 582-0221
Fax (406) 582-5770
Groundwater Monitoring Data: Page 2 of 2
1
2 3
4
5 6
78
9
1
2
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit Weight (pcf)
Effective Cohesion (psf)
Effective Friction Angle (°)
PiezometricSurface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit A1 - Scenario 1 Slope Stability Analysis Setup
(GW Well Below Bottom of Reservoir - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.829
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit A2 - Scenario 1 Slope Stability Analysis (Static Condition)
(GW Well Below Bottom of Reservoir - Existing 1.57H:1V Slope Geometry)
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
EXISTINGEMBANKMENT
FILL SECTION
1.395
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit Weight (pcf)
Effective Cohesion (psf)
Effective Friction Angle (°)
PiezometricSurface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit A3 - Scenario 1 Slope Stability Analysis (Seismic Condition)
(GW Well Below Bottom of Reservoir - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENT
FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1
2 3
4
5 6
78
9
1
2
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit B1 - Scenario 2 Slope Stability Analysis Setup
(GW at Bottom of Reservoir - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.829
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit B2 - Scenario 2 Slope Stability Analysis (Static Condition)
(GW at Bottom of Reservoir - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENT
FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.396
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit B3 - Scenario 2 Slope Stability Analysis (Seismic Condition)
(GW at Bottom of Reservoir - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENT
FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1
2 3
4
5 6
78
9
1
2
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit C1 - Scenario 3 Slope Stability Analysis Setup
(GW at Interface of Native Subgrade Soils and Embankment Fill Section - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.705
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit C2 - Scenario 3 Slope Stability Analysis (Static Condition)
(GW at Interface of Native Subgrade Soils and Embankment Fill Section - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENT
FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.257
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit C3 - Scenario 3 Slope Stability Analysis (Seismic Condition)
(GW at Interface of Native Subgrade Soils and Embankment Fill Section - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENT
FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1
2 3
4
5 6
78
9
1
2
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit D1 - Scenario 4 Slope Stability Analysis Setup
(Mid-Level Leak/Partially Saturated Embankment - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.649
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit D2 - Scenario 4 Slope Stability Analysis (Static Condition)
(Mid-Level Leak/Partially Saturated Embankment - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENTFILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.221
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit D3- Scenario 4 Slope Stability Analysis (Seismic Condition)
(Mid-Level Leak/Partially Saturated Embankment - Existing 1.57H:1V Slope Geometry)
EXISTINGEMBANKMENTFILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1
2 3
4
5 6
78
9
1
2
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit E1 - Scenario 5 Slope Stability Analysis Setup
(High-Level Leak/Partially Saturated Embankment - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.582
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit E2 - Scenario 5 Slope Stability Analysis (Static Condition)
(High-Level Leak/Partially Saturated Embankment - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.171
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
Distance
Exhibit E3 - Scenario 5 Slope Stability Analysis (Seismic Condition)
(High-Level Leak/Partially Saturated Embankment - Existing 1.57H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1
2 3
4
5 6
78
9
10
1
23
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit F1 - Scenario 6 Slope Stability Analysis Setup
(High-Level Leak/Partially Saturated Embankment - New 2H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
NEW EMBANKMENT FILL SECTION
1.686
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit F2 - Scenario 6 Slope Stability Analysis (Static Condition)
(High-Level Leak/Partially Saturated Embankment - New 2H:1V Slope Geometry)
EXISTING EMBANKMENT FILL SECTION
EXISTING RESERVOIR
NATIVE SUBGRADE SOILS
NEW EMBANKMENT FILL SECTION
1.193
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit F3 - Scenario 6 Slope Stability Analysis (Seismic Condition)
(High-Level Leak/Partially Saturated Embankment - New 2H:1V Slope Geometry)
NEW EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1
2 3
4
5 6
78
9
10
1
2
3
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit G1 - Scenario 7 Slope Stability Analysis Setup
(High-Level Leak/Partially Saturated Embankment - New 2.5H:1V Slope Geometry)
NEW
EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
EXISTING RESERVOIR
NATIVE SUBGRADE SOILS
1.823
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit G2 - Scenario 7 Slope Stability Analysis (Static Condition)
(High-Level Leak/Partially Saturated Embankment - New 2.5H:1V Slope Geometry)
NEW
EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.219
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit G3 - Scenario 7 Slope Stability Analysis (Seismic Condition)
(High-Level Leak/Partially Saturated Embankment - New 2.5H:1V Slope Geometry)
NEW
EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
EXISTING RESERVOIR
NATIVE SUBGRADE SOILS
1
2 3
4
5 6
78
9
10
1
2
3
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit H1 - Scenario 8 Slope Stability Analysis Setup
(High-Level Leak/Partially Saturated Embankment - New 3H:1V Slope Geometry)
NEW EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.960
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit H2 - Scenario 8 Slope Stability Analysis (Static Condition)
(High-Level Leak/Partially Saturated Embankment - New 3H:1V Slope Geometry)
NEW EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
1.245
0 25 50 75 100 125 150 175 200 225 250Elevation0
10
20
30
40
50
60
Color Name Unit
Weight
(pcf)
Effective
Cohesion
(psf)
Effective
Friction
Angle ()
Piezometric
Surface
Embankment Fill (Sandy Clay) 125 350 28 1
Native (Clay with Sand/Gravel) 130 100 30 1
New Embankment Fill (Sandy Clay) 125 350 28 1
Distance
Exhibit H3 - Scenario 8 Slope Stability Analysis(Seismic Condition)
(High-Level Leak/Partially Saturated Embankment - New 3H:1V Slope Geometry)
NEW EMBANKMENT FILL SECTION EXISTING EMBANKMENT FILL SECTION
NATIVE SUBGRADE SOILS
EXISTING RESERVOIR
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.
APPENDIX E
Cost Estimates
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternatives Cost Summary
Total Intitial
Project Cost Life Cycle Cost
Alternative 1.1: Rehabilitate Existing Reservoir with New Geomembrane Liner 4,048,380$ 21,118,377$
Alternative 1.2: Rehabilitate Existing Reservoir with Concrete Coating System 5,214,380$ 26,798,359$
Alternative 2.1: Rehabilitate Existing Reservoir with Geomembrane Liner + New 1 MG Reservoir 9,659,175$ 28,586,508$
Alternative 2.2: Rehabilitate Existing Reservoir with Coating System + New 1 MG Reservoir 10,823,612$ 33,875,449$
Alternative 3: New 5 MG Reservoir at Existing Site 12,275,207$ 25,855,315$
Alternative 4: New 5 MG Reservoir and Treatment at Upgradient Site 18,569,283$ 33,930,253$
Alternatives Cost Summary
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternative 1.1: Rehabilitate Existing Reservoir with New Geomembrane Liner
ITEM DESCRIPTION UNIT PRICE UNITS QTY TOTAL COST
Construction
Site Improvements
101 Replace Roof Down Spouts and Splash Pads $500.00 EA 8 $4,000.00
102 Replace Concrete Collar for Storm Drain MH's Lower catch basin rim elevation $500.00 EA 4 $2,000.00
103 Outlet Control Building Entry Improvements $25,000.00 LS 1 $25,000.00
Reservoir Rehabilitation
201 Removal of Existing Membrane Liner, Geocomposite Fabric, and Hypernet Underdrain $100,000.00 LS 1 $100,000.00
202 High Pressure Water Jetting (CSP 1-2) $3.50 SF 46,621 $163,173.50
203 Concrete Inspection $20,000.00 LS 1.0 $20,000.00
204 Joint Repair (assumes all joints need repair) $40.00 LF 1,448 $57,929.60
205 Crack Repair (assumes same quantity of cracks as 2004) $54.00 LF 952 $51,408.00
206 Spalling and Delamination Repair (assumes 5% of surface area) $2.00 SF 2,331 $4,662.10
207 Resurfacing Mortar (assumes 5% of surface area) $55.00 SF 2,331 $128,207.75
208 Slab Replacement (assumes 3% of surface area) $170.00 SF 1,398.6 $237,767.10
209 XR-PW3 Liner $4.70 SF 46,621 $219,118.70
210 Geocomposite $1.00 SF 46,621 $46,621.00
211 Baffles $58,333.00 EA 3 $174,999.00
212 Pipe Penetration Boot $2,000.00 EA 3 $6,000.00
213 Column Boot $4,000.00 EA 12 $48,000.00
214 Inlet Pipe Thrust Block and Drain Sump Fabrication $3,000.00 EA 2 $6,000.00
215 Barwork $40.00 LF 900 $36,000.00
216 Equipment/Rigging $15,000.00 LS 1 $15,000.00
217 QA/QC Setup and QC $20,000.00 LS 1 $20,000.00
218 3rd Party Leak Location Survey $15,000.00 LS 1 $15,000.00
219 Repairs $20,000.00 LS 1 $20,000.00
220 Warranty $10,000.00 LS 1 $10,000.00
221 2" Inlet Air Relief Valve $4,000.00 EA 1 $4,000.00
222 16" Inlet Pipe Coating $425.00 LF 55 $23,375.00
223 16" Inlet Pipe Stands $3,000.00 EA 3 $9,000.00
224 Entrance Access Ladder $95,000.00 EA 2 $190,000.00
225 Replace Vestibule Structure $400.00 SF 238 $95,200.00
226 Grout Rub Damaged Exterior Panels $14,000.00 EA 4 $56,000.00
227 Clean and Recoat All Existing Steel Hardware $30,000.00 LS 1 $30,000.00
228 Steel Components of Parallel Connections to Tri-Deck Replacement $35,000.00 LS 1 $35,000.00
229 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
230 16" Tank Bypass $94,155.00 LS 1 $94,155.00
231 Other $185,346.18 LS 1 $185,346.18
Subtotal Materials and Labor $2,232,962.93
General Conditions
001 Mobilization/Demobilization (5%)$112,000.00
002 Taxes, Bonds and Insurance (3%)$67,000.00
003 General Requirements (8%)$179,000.00
Subtotal General Conditions $358,000.00
Subtotal Construction Cost $2,590,962.93
Construction Contingency (25%) $647,740.73
Total Construction Cost $3,238,703.66
Non-Construction Costs
Engineering (25%)$809,675.91
Subtotal Non-Construction Cost $809,675.91
TOTAL PROJECT COST $4,048,379.57
Alternative 1.1: Rehabilitate Existing Reservoir with New Geomembrane Liner
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternative 1.2: Rehabilitate Existing Reservoir with Concrete Coating System
ITEM DESCRIPTION UNIT PRICE UNITS QTY TOTAL COST
Construction
Site Improvements
101 Replace Roof Down Spouts and Splash Pads $500.00 EA 8 $4,000.00
102 Replace Concrete Collar for Storm Drain MH's Lower catch basin rim elevation $500.00 EA 4 $2,000.00
103 Outlet Control Building Entry Improvements $25,000.00 LS 1 $25,000.00
Reservoir Rehabilitation
201 Removal of Existing Membrane Liner, Geocomposite Fabric, and Hypernet Underdrain $100,000.00 LS 1 $100,000.00
202 High Pressure Water Jetting (CSP 4-6) $7.00 SF 46,621 $326,347.00
203 Concrete Inspection $20,000.00 LS 1.0 $20,000.00
204 Joint Repair (assumes all joints need repair) $40.00 LF 1,448 $57,929.60
205 Crack Repair (assumes same quantity of cracks as 2004) $54.00 LF 952 $51,408.00
206 Spalling and Delamination Repair (assumes 5% of surface area) $2.00 SF 2,331 $4,662.10
207 Resurfacing Mortar (assumes 5% of surface area) $55.00 SF 2,331 $128,207.75
208 Slab Replacement (assumes 3% of surface area) $170.00 SF 1,398.6 $237,767.10
209 Abandon Underdrain Outlet $35,000.00 LS 1.0 $35,000.00
210 Seal 16" Outlet Penetration $35,000.00 LS 1 $35,000.00
211 Seal 8" Drain Penetration $30,000.00 LS 1 $30,000.00
212 Spray-Apply Coating system $20.00 SF 46,621 $932,420.00
213 2" Inlet Air Relief Valve $4,000.00 EA 1 $4,000.00
214 16" Inlet Pipe Coating $425.00 LF 55 $23,375.00
215 16" Inlet Pipe Stands $3,000.00 EA 3 $9,000.00
216 Entrance Access Ladder $95,000.00 EA 2 $190,000.00
217 Replace Vestibule Structure $400.00 SF 238 $95,200.00
218 Grout Rub Damaged Exterior Concrete Panel $14,000.00 EA 4 $56,000.00
219 Clean and Recoat All Existing Steel Hardware $30,000.00 LS 1 $30,000.00
220 Steel Components of Parallel Connections to Tri-Deck Replacement $30,000.00 LS 1 $30,000.00
221 Abandon Dechlorination Equipment $10,000.00 LS 1 $10,000.00
222 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
223 16" Tank Bypass $94,155.00 LS 1 $94,155.00
224 Other $243,731.66 LS 1 $243,731.66
$2,875,203.21
General Conditions
001 Mobilization/Demobilization (5%)$144,000.00
002 Taxes, Bonds and Insurance (3%)$87,000.00
003 General Requirements (8%)$231,000.00
Subtotal General Conditions $462,000.00
Subtotal Construction Cost $3,337,203.21
Construction Contingency (25%) $834,300.80
Total Construction Cost $4,171,504.01
Non-Construction Costs
Engineering (25%)$1,042,876.00
Subtotal Non-Construction Cost $1,042,876.00
TOTAL PROJECT COST $5,214,380.01
Alternative 1.2: Rehabilitate Existing Reservoir with Concrete Coating System
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternative 2.1: Rehabilitate Existing Reservoir with Geomembrane Liner + New 1 MG Reservoir
ITEM DESCRIPTION UNIT PRICE UNITS QTY TOTAL COST
Construction
Site Improvements
101 Replace Roof Down Spouts and Splash Pads $500.00 EA 8 $4,000.00
102 Replace Concrete Collar for Storm Drain MH's Lower catch basin rim elevation $500.00 EA 4 $2,000.00
103 Outlet Control Building Entry Improvements $25,000.00 LS 1 $25,000.00
Reservoir Rehabilitation
201 Removal of Existing Membrane Liner, Geocomposite Fabric, and Hypernet Underdrain $100,000.00 LS 1 $100,000.00
202 High Pressure Water Jetting (CSP 1-2) $3.50 SF 46,621 $163,173.50
203 Concrete Inspection $20,000.00 LS 1.0 $20,000.00
204 Joint Repair (assumes all joints need repair) $40.00 LF 1,448 $57,929.60
205 Crack Repair (assumes same quantity of cracks as 2004) $54.00 LF 952 $51,408.00
206 Spalling and Delamination Repair (assumes 5% of surface area) $2.00 SF 2,331 $4,662.10
207 Resurfacing Mortar (assumes 5% of surface area) $55.00 SF 2,331 $128,207.75
208 Slab Replacement (assumes 3% of surface area) $170.00 SF 1,398.6 $237,767.10
209 XR-PW3 Liner $4.70 SF 46,621 $219,118.70
210 Geocomposite $1.00 SF 46,621 $46,621.00
211 Baffles $58,333.00 EA 3 $174,999.00
212 Pipe Penetration Boot $2,000.00 EA 3 $6,000.00
213 Column Boot $4,000.00 EA 12 $48,000.00
214 Inlet Pipe Thrust Block and Drain Sump Fabrication $3,000.00 EA 2 $6,000.00
215 Barwork $40.00 LF 900 $36,000.00
216 Equipment/Rigging $15,000.00 LS 1 $15,000.00
217 QA/QC Setup and QC $20,000.00 LS 1 $20,000.00
218 3rd Party Leak Location Survey $15,000.00 LS 1 $15,000.00
219 Repairs $20,000.00 LS 1 $20,000.00
220 Warranty $10,000.00 LS 1 $10,000.00
221 2" Inlet Air Relief Valve $4,000.00 EA 1 $4,000.00
222 16" Inlet Pipe Coating $425.00 LF 55 $23,375.00
223 16" Inlet Pipe Stands $3,000.00 EA 3 $9,000.00
224 Entrance Access Ladder $95,000.00 EA 2 $190,000.00
225 Replace Vestibule Structure $400.00 SF 238 $95,200.00
226 Grout Rub Damaged Exterior Panels $14,000.00 EA 4 $56,000.00
227 Clean and Recoat All Existing Steel Hardware $30,000.00 LS 1 $30,000.00
228 Steel Components of Parallel Connections to Tri-Deck Replacement $35,000.00 LS 1 $35,000.00
229 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
1 MG Tank
301 Clearing and Grubbing $10,000.00 AC 0.6 $5,825.99
302 Unclassified Excavation $15.00 CY 11,550 $173,250.00
303 Backfill $20.00 CY 2,929 $58,580.00
304 Embankment $7.00 CY 8,621 $60,347.00
305 Seeding - Disk/Drill/Roll $1,500.00 AC 0.5 $750.00
306 Rammed Aggregate Piers $135.00 LF 838.0 $113,130.00
307 12" Min Structural Fill Under Slab $53.00 CY 225.0 $11,925.00
308 1" Minus Clean Crushed Rock $53.00 CY 75.0 $3,975.00
309 1 MG Prestressed Concrete Tank $1,900,000.00 LS 1.0 $1,900,000.00
310 Reroute Gravel Access Road $85.00 LF 290.0 $24,650.00
311 Road Mix $53.00 CY 75 $3,975.00
312 16" Inlet/Outlet Pipe $135.00 LF 230 $31,050.00
313 16" Tee $6,800.00 EA 2 $13,600.00
314 16" 90⁰ Bend $5,000.00 EA 1 $5,000.00
315 16" 22.5⁰ Bend $3,800.00 EA 1 $3,800.00
316 16" Gate Valve $5,000.00 EA 3 $15,000.00
317 15" Drain Pipe $120.00 LF 460 $55,200.00
318 Drain Manholes $10,000.00 EA 3 $30,000.00
319 Process Improvements, Flow/Level Control $250,000.00 LS 1 $250,000.00
320 Relocate Existing Drainfield $30,000.00 LS 1 $30,000.00
Alternative 2.1: Rehabilitate Existing Reservoir with Geomembrane Liner + New 1 MG Reservoir
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
321 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
322 Other $484,351.97 LS 1 $484,351.97
Subtotal Materials and Labor $5,327,871.71
General Conditions
001 Mobilization/Demobilization (5%)$267,000.00
002 Taxes, Bonds and Insurance (3%)$160,000.00
003 General Requirements (8%)$427,000.00
Subtotal General Conditions $854,000.00
Subtotal Construction Cost $6,181,871.71
Construction Contingency (25%) $1,545,467.93
Total Construction Cost $7,727,339.64
Non-Construction Costs
Engineering (25%)$1,931,834.91
Subtotal Non-Construction Cost $1,931,834.91
TOTAL PROJECT COST $9,659,174.55
Alternative 2.1: Rehabilitate Existing Reservoir with Geomembrane Liner + New 1 MG Reservoir
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternative 2.2: Rehabilitate Existing Reservoir with Coating System + New 1 MG Reservoir
ITEM DESCRIPTION UNIT PRICE UNITS QTY TOTAL COST
Construction
Site Improvements
101 Replace Roof Down Spouts and Splash Pads $500.00 EA 8 $4,000.00
102 Replace Concrete Collar for Storm Drain MH's Lower catch basin rim elevation $500.00 EA 4 $2,000.00
103 Outlet Control Building Entry Improvements $25,000.00 LS 1 $25,000.00
Reservoir Rehabilitation
201 Removal of Existing Membrane Liner, Geocomposite Fabric, and Hypernet Underdrain $100,000.00 LS 1 $100,000.00
202 High Pressure Water Jetting (CSP 4-6) $7.00 SF 46,621 $326,347.00
203 Concrete Inspection $20,000.00 LS 1.0 $20,000.00
204 Joint Repair (assumes all joints need repair) $40.00 LF 1,448 $57,929.60
205 Crack Repair (assumes same quantity of cracks as 2004) $54.00 LF 952 $51,408.00
206 Spalling and Delamination Repair (assumes 5% of surface area) $2.00 SF 2,331 $4,662.10
207 Resurfacing Mortar (assumes 5% of surface area) $55.00 SF 2,331 $128,207.75
208 Slab Replacement (assumes 3% of surface area) $170.00 SF 1,398.6 $237,767.10
209 Abandon Underdrain Outlet $35,000.00 LS 1.0 $35,000.00
210 Seal 16" Outlet Penetration $35,000.00 LS 1 $35,000.00
211 Seal 8" Drain Penetration $30,000.00 LS 1 $30,000.00
212 Spray-Apply Coating system $20.00 SF 46,621 $932,420.00
213 2" Inlet Air Relief Valve $4,000.00 EA 1 $4,000.00
214 16" Inlet Pipe Coating $425.00 LF 55 $23,375.00
215 16" Inlet Pipe Stands $3,000.00 EA 3 $9,000.00
216 Entrance Access Ladder $95,000.00 EA 2 $190,000.00
217 Replace Vestibule Structure $400.00 SF 238 $95,200.00
218 Grout Rub Damaged Exterior Concrete Panel $14,000.00 EA 4 $56,000.00
219 Clean and Recoat All Existing Steel Hardware $30,000.00 LS 1 $30,000.00
220 Steel Components of Parallel Connections to Tri-Deck Replacement $30,000.00 LS 1 $30,000.00
221 Abandon Dechlorination Equipment $10,000.00 LS 1 $10,000.00
222 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
1 MG Tank
301 Clearing and Grubbing $10,000.00 AC 0.6 $5,825.99
302 Unclassified Excavation $15.00 CY 11,550 $173,250.00
303 Backfill $20.00 CY 2,929 $58,580.00
304 Embankment $7.00 CY 8,621 $60,347.00
305 Seeding - Disk/Drill/Roll $1,500.00 AC 0.5 $750.00
306 Rammed Aggregate Piers $135.00 LF 838.0 $113,130.00
307 12" Min Structural Fill Under Slab $53.00 CY 225.0 $11,925.00
308 1" Minus Clean Crushed Rock $53.00 CY 75.0 $3,975.00
309 1 MG Prestressed Concrete Tank $1,900,000.00 LS 1.0 $1,900,000.00
310 Reroute Gravel Access Road $85.00 LF 290.0 $24,650.00
311 Road Mix $53.00 CY 75 $3,975.00
312 16" Inlet/Outlet Pipe $135.00 LF 230 $31,050.00
313 16" Tee $6,800.00 EA 2 $13,600.00
314 16" 90⁰ Bend $5,000.00 EA 1 $5,000.00
315 16" 22.5⁰ Bend $3,800.00 EA 1 $3,800.00
316 16" Gate Valve $5,000.00 EA 3 $15,000.00
317 15" Drain Pipe $120.00 LF 460 $55,200.00
318 Drain Manholes $10,000.00 EA 3 $30,000.00
319 Process Improvements, Flow/Level Control $250,000.00 LS 1 $250,000.00
320 Relocate Existing Drainfield $30,000.00 LS 1 $30,000.00
321 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
322 Other $542,737.45 LS 1 $542,737.45
$5,970,111.99
General Conditions
001 Mobilization/Demobilization (5%)$299,000.00
002 Taxes, Bonds and Insurance (3%)$180,000.00
Alternative 2.2: Rehabilitate Existing Reservoir with Coating System + New 1 MG Reservoir
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
003 General Requirements (8%)$478,000.00
Subtotal General Conditions $957,000.00
Subtotal Construction Cost $6,927,111.99
Construction Contingency (25%) $1,731,778.00
Total Construction Cost $8,658,889.99
Non-Construction Costs
Engineering (25%)$2,164,722.50
Subtotal Non-Construction Cost $2,164,722.50
TOTAL PROJECT COST $10,823,612.49
Alternative 2.2: Rehabilitate Existing Reservoir with Coating System + New 1 MG Reservoir
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternative 3: New 5 MG Reservoir at Existing Site
ITEM DESCRIPTION UNIT PRICE UNITS QTY TOTAL COST
Construction
Site Improvements
101 Replace Roof Down Spouts and Splash Pads $500.00 EA 8 $4,000.00
102 Replace Concrete Collar for Storm Drain MH's Lower catch basin rim elevation $500.00 EA 4 $2,000.00
103 Outlet Control Building Entry Improvements $25,000.00 LS 1 $25,000.00
5 MG Reservoir
201 Clearing and Grubbing $10,000.00 AC 1.0 $10,000.00
202 Unclassified Excavation $15.00 CY 16,654 $249,810.00
203 Backfill $20.00 CY 8,397 $167,940.00
204 Embankment $7.00 CY 8,257 $57,799.00
205 Seeding - Disk/Drill/Roll $1,500.00 AC 1.0 $1,500.00
206 Rammed Aggregate Piers $135.00 LF 1,780.0 $240,300.00
207 12" Min Structural Fill Under Slab $53.00 CY 915.0 $48,495.00
208 1" Minus Clean Crushed Rock $53.00 CY 150.0 $7,950.00
209 5 MG Prestressed Concrete Tank $4,700,000 LS 1.0 $4,700,000.00
210 Reroute Gravel Access Road $120.00 LF 550.0 $66,000.00
211 Road Mix $53.00 CY 143 $7,557.41
212 16" Inlet/Outlet Pipe $135.00 LF 457 $61,695.00
213 16" Tee $6,800.00 EA 2 $13,600.00
214 16" 90⁰ Bend $5,000.00 EA 1 $5,000.00
215 16" 22.5⁰ Bend $3,800.00 EA 1 $3,800.00
216 16" Gate Valve $5,000.00 EA 3 $15,000.00
217 15" Drain Pipe $120.00 LF 540 $64,800.00
218 Drain Manholes $10,000.00 EA 3 $30,000.00
219 Process Improvements, Flow/Level Control $250,000.00 LS 1 $250,000.00
220 Relocate Existing Drainfield $30,000.00 LS 1 $30,000.00
221 Inlet Control Building Improvements $100,000.00 LS 1 $100,000.00
222 Decommission Existing Reservoir $250,000.00
LS 1 $250,000.00
223 Other $641,224.64 LS 1 $641,224.64
Subtotal Materials and Labor $7,053,471.05
General Conditions
Mobilization/Demobilization (5%)$353,000.00
Taxes, Bonds and Insurance (3%)$212,000.00
General Requirements (8%)$565,000.00
Subtotal General Conditions $1,130,000.00
Subtotal Construction Cost $8,183,471.05
Construction Contingency (20%) $1,636,694.21
Total Construction Cost $9,820,165.26
Non-Construction Costs
001 Engineering (25%)$2,455,041.31
Subtotal Non-Construction Cost $2,455,041.31
TOTAL PROJECT COST $12,275,206.57
Alternative 3: New 5 MG Reservoir at Existing Site
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
City of Bozeman Lyman Reservoir Predesign
Opinion of Probable Project Costs
08/2026
Alternative 4: New 5 MG Reservoir and Treatment at Upgradient Site
ITEM DESCRIPTION UNIT PRICE UNITS QTY TOTAL COST
Construction
5 MG Reservoir
101 Clearing and Grubbing $10,000.00 AC 1.0 $10,000.00
102 Unclassified Excavation $15.00 CY 20,000 $300,000.00
103 Backfill $20.00 CY 10,000 $200,000.00
104 Embankment $7.00 CY 10,000 $70,000.00
105 Seeding - Disk/Drill/Roll $1,500.00 AC 1.0 $1,500.00
106 Rammed Aggregate Piers $135.00 LF 1,780.0 $240,300.00
107 12" Min Structural Fill Under Slab $53.00 CY 915.0 $48,495.00
108 1" Minus Clean Crushed Rock $53.00 CY 150.0 $7,950.00
109 5 MG Prestressed Concrete Tank $4,700,000.00 LS 1.0 $4,700,000.00
110 Reroute Gravel Access Road $120.00 LF 5,620.0 $674,400.00
111 Road Mix $53.00 CY 1,457 $77,222.96
112 16" Inlet/Outlet Pipe $135.00 LF 735 $99,225.00
113 16" 45⁰ Bend $4,000.00 EA 5 $20,000.00
114 16" 90⁰ Bend $5,000.00 EA 1 $5,000.00
115 16" Gate Valve $5,000.00 EA 2 $10,000.00
116 Buried Power $100.00 LF 5,620 $562,000.00
117 Electric Service to Disinfection Building $20,000.00 LS 1 $20,000.00
118 Piping Modifications $200,000.00 LS 1 $200,000.00
119 Decommission Existing Reservoir $450,000.00 LS 1 $450,000.00
Inlet/outlet control building and treatment system
201 Inlet, Outlet and Chlorination Building $589.00 SF 1440 $848,160.00
202 Flow Meter $20,000.00 EA 1 $20,000.00
203 Inlet/Outlet Control Valves $5,000.00 EA 2 $10,000.00
204 Inlet Check Valve $3,000.00 EA 1 $3,000.00
205 Chlorination Equipment $200,000.00 LS 1 $200,000.00
206 Piping and Appurtenances $100,000.00 LS 1 $100,000.00
207 Septic System $30,000.00 LS 1 $30,000.00
208 Other $1,336,087.94 LS 1 $1,336,087.94
$10,243,340.91
General Conditions
Mobilization/Demobilization (5%)$513,000.00
Taxes, Bonds and Insurance (3%)$308,000.00
General Requirements (8%)$820,000.00
Subtotal General Conditions $1,641,000.00
Subtotal Construction Cost $11,884,340.91
Construction Contingency (25%) $2,971,085.23
Total Construction Cost $14,855,426.13
Non-Construction Costs
001 Engineering (25%)$3,713,856.53
Subtotal Non-Construction Cost $3,713,856.53
TOTAL PROJECT COST $18,569,282.67
Alternative 4: New 5 MG Reservoir and Treatment at Upgradient Site
N:\0417\100-Lyman Predesign\03 Pre-Design\Cost Estimates\Capital Cost Estimate
Year
Yearly Repayment of
Initial Project Repair Project
Yearly Repayment of
Rehab Project Notes
2026 259,692$ Initial Project
2027 259,692$
2028 259,692$
2029 259,692$
2030 259,692$
2031 259,692$
2032 259,692$
2033 259,692$
2034 259,692$
2035 259,692$
2036 259,692$
2037 259,692$
2038 259,692$
2039 259,692$
2040 259,692$
2041 259,692$
2042 259,692$
2043 259,692$
2044 259,692$
2045 259,692$ 1,397,356$ Roof Replacement
2046
2047
2048
2049
2050 726,359$ Reline Project
2051 726,359$
2052 726,359$
2053 726,359$
2054 726,359$
2055 726,359$
2056 726,359$
2057 726,359$
2058 726,359$
2059 726,359$
2060 726,359$
2061 726,359$
2062 726,359$
2063 726,359$
2064 726,359$
2065 726,359$
2066 726,359$
2067 726,359$
2068 726,359$
2069 726,359$
2070
2071
2072
2073
2074
2075
2076
Total 5,193,839$ 1,397,356$ 14,527,183$
21,118,377$ Total 50-Year Life Cycle Cost
50-Year Life Cycle Cost Analysis
Alternative 1.1: Rehabilitate Existing Reservoir with New Geomembrane Liner
Year
Yearly Repayment of
Initial Project Repair Project
Yearly Repayment of
Rehab Project Notes
2026 334,488$ Initial Project
2027 334,488$
2028 334,488$
2029 334,488$
2030 334,488$
2031 334,488$
2032 334,488$
2033 334,488$
2034 334,488$
2035 334,488$
2036 334,488$
2037 334,488$
2038 334,488$
2039 334,488$
2040 334,488$
2041 334,488$
2042 334,488$
2043 334,488$
2044 334,488$
2045 334,488$ 1,397,356$ Roof Replacement
2046
2047
2048
2049
2050 935,563$ Recoating Project
2051 935,563$
2052 935,563$
2053 935,563$
2054 935,563$
2055 935,563$
2056 935,563$
2057 935,563$
2058 935,563$
2059 935,563$
2060 935,563$
2061 935,563$
2062 935,563$
2063 935,563$
2064 935,563$
2065 935,563$
2066 935,563$
2067 935,563$
2068 935,563$
2069 935,563$
2070
2071
2072
2073
2074
2075
2076
Total 6,689,750$ 1,397,356$ 18,711,253$
26,798,359$ Total 50-Year Life Cycle Cost
50-Year Life Cycle Cost Analysis
Alternative 1.2: Rehabilitate Existing Reservoir with Concrete Coating System
Year
Yearly Repayment of
Initial Project Repair Project
Yearly Repayment of
Rehab Project Notes
2026 619,608$ Initial Construction
2027 619,608$
2028 619,608$
2029 619,608$
2030 619,608$
2031 619,608$
2032 619,608$
2033 619,608$
2034 619,608$
2035 619,608$
2036 619,608$
2037 619,608$
2038 619,608$
2039 619,608$
2040 619,608$
2041 619,608$
2042 619,608$
2043 619,608$
2044 619,608$
2045 619,608$ 1,397,356$ Roof Replacement
2046
2047
2048
2049
2050 739,849$ Reline & Renewal Project
2051 739,849$
2052 739,849$
2053 739,849$
2054 739,849$
2055 739,849$
2056 739,849$
2057 739,849$
2058 739,849$
2059 739,849$
2060 739,849$
2061 739,849$
2062 739,849$
2063 739,849$
2064 739,849$
2065 739,849$
2066 739,849$
2067 739,849$
2068 739,849$
2069 739,849$
2070
2071
2072
2073
2074
2075
2076
Total 12,392,166$ 1,397,356$ 14,796,986$
28,586,508$ Total 50-Year Life Cyle Cost
50-Year Life Cycle Cost Analysis
Alternative 2.1: Rehabilitate Existing Reservoir with Geomembrane Liner + New 1 MG Reservoir
Year
Yearly Repayment of
Initial Project Repair Project
Yearly Repayment of
Rehab Project Notes
2026 694,304$ Initial Construction
2027 694,304$
2028 694,304$
2029 694,304$
2030 694,304$
2031 694,304$
2032 694,304$
2033 694,304$
2034 694,304$
2035 694,304$
2036 694,304$
2037 694,304$
2038 694,304$
2039 694,304$
2040 694,304$
2041 694,304$
2042 694,304$
2043 694,304$
2044 694,304$
2045 694,304$ 1,397,356$ Roof Replacement
2046
2047
2048
2049
2050 929,601$ Reline & Renewal Project
2051 929,601$
2052 929,601$
2053 929,601$
2054 929,601$
2055 929,601$
2056 929,601$
2057 929,601$
2058 929,601$
2059 929,601$
2060 929,601$
2061 929,601$
2062 929,601$
2063 929,601$
2064 929,601$
2065 929,601$
2066 929,601$
2067 929,601$
2068 929,601$
2069 929,601$
2070
2071
2072
2073
2074
2075
2076
Total 13,886,073$ 1,397,356$ 18,592,021$
33,875,449$ Total 50-Year Life Cycle Cost
50-Year Life Cycle Cost Analysis
Alternative 2.2: Rehabilitate Existing Reservoir with Coating System + New 1 MG Reservoir
Year
Yearly Repayment of
Initial Project Repair Project
Yearly Repayment of
Rehab Project Notes
2026 787,419$ Initial Construction
2027 787,419$
2028 787,419$
2029 787,419$
2030 787,419$
2031 787,419$
2032 787,419$
2033 787,419$
2034 787,419$
2035 787,419$
2036 787,419$
2037 787,419$
2038 787,419$
2039 787,419$
2040 787,419$
2041 787,419$
2042 787,419$
2043 787,419$
2044 787,419$
2045 787,419$
2046
2047
2048
2049
2050 505,347$ Renewal Project
2051 505,347$
2052 505,347$
2053 505,347$
2054 505,347$
2055 505,347$
2056 505,347$
2057 505,347$
2058 505,347$
2059 505,347$
2060 505,347$
2061 505,347$
2062 505,347$
2063 505,347$
2064 505,347$
2065 505,347$
2066 505,347$
2067 505,347$
2068 505,347$
2069 505,347$
2070
2071
2072
2073
2074
2075
2076
Total 15,748,385$ -$ 10,106,930$
25,855,315$ Total 50-Year Life Cycle Cost
50-Year Life Cycle Cost Analysis
Alternative 3: New 5 MG Reservoir at Existing Site
Year
Yearly Repayment of
Initial Project Repair Project
Yearly Repayment of
Rehab Project Notes
2026 1,191,166$ Initial Construction
2027 1,191,166$
2028 1,191,166$
2029 1,191,166$
2030 1,191,166$
2031 1,191,166$
2032 1,191,166$
2033 1,191,166$
2034 1,191,166$
2035 1,191,166$
2036 1,191,166$
2037 1,191,166$
2038 1,191,166$
2039 1,191,166$
2040 1,191,166$
2041 1,191,166$
2042 1,191,166$
2043 1,191,166$
2044 1,191,166$
2045 1,191,166$
2046
2047
2048
2049
2050 505,347$ Renewal Project
2051 505,347$
2052 505,347$
2053 505,347$
2054 505,347$
2055 505,347$
2056 505,347$
2057 505,347$
2058 505,347$
2059 505,347$
2060 505,347$
2061 505,347$
2062 505,347$
2063 505,347$
2064 505,347$
2065 505,347$
2066 505,347$
2067 505,347$
2068 505,347$
2069 505,347$
2070
2071
2072
2073
2074
2075
2076
Total 23,823,323$ -$ 10,106,930$
33,930,253$ Total 50-Year Life Cycle Cost
50-Year Life Cycle Cost Analysis
Alternative 4: New 5 MG Reservoir and Treatment at Upgradient Site
APPENDIX F
Record Drawings