MT NP GLAC 14(6) - Swift Current Spur Rd Rehab_Amended Final Pavement Memo.pdf

DATE: May 16, 2024

TO: Michael Traffalis, Project Manager

FROM: Nassim Sabahfar, Pavement and Materials Engineer

SUBJECT: Amended Final Pavement Structure Recommendations Swiftcurrent Spur Road Rehabilitation

MT NP GLAC 14(6)

Background

Final pavement recommendations specific to only parking area expansions included in Swiftcurrent Spur Road Rehabilitation project are amended in this memorandum. The amendments are made due to concerns for funding and the expectation for traffic to be significantly lower than that of Many Glacier Road as presented in Final Pavement Memorandum. Based on conversations with Glacier National Park, the parking area expansions are expected to receive negligible truck traffic (inclusive of transit bus traffic). The Final Pavement Memorandum is attached to this current report as Appendix A.

Recommended pavement design for rehabilitation of Many Glacier Road, from Many Glacier Hotel intersection to Swiftcurrent Motor Inn, remains unchanged.

Amended Pavement Structure Recommendations

Amended pavement structure recommendations for parking area expansions are provided in Table 1.

Table 1 - Recommended Pavement Design for Parking Area Expansions Thickness (inches)

Description

3 Asphalt Concrete Pavement (Section 403, estimated @ 1.94 tons/cuyd)

6 Roadway Aggregate, Method 2 (Section 302, estimated @ 1.97 tons/cuyd)

It is recommended that asphalt concrete pavement layer be placed in one lift. The binder grade is designated as PG 58-34.

Appendix A

Final Pavement Structure Recommendations

158377846

Memorandum

Western Federal Lands Highway Division 610 E. Fifth Street

Vancouver, WA 98661

DATE: January 8, 2024

TO: Michael Traffalis, Project Manager

FROM: Nassim Sabahfar, Materials Engineer

SUBJECT: Final Pavement Structure Recommendations Swiftcurrent Spur Road Rehabilitation

Background

This memorandum provides final pavement recommendations for rehabilitation of the portion of Many Glacier Road between Many Glacier Hotel intersection and Swiftcurrent Motor Inn and construction of new parking areas along the alignment and at Swiftcurrent Motor Inn. The road segment is approximately one mile long and is the last mile of 12.9 mile long Many Glacier Road. Many Glacier Road begins at Babb, Montana, at the intersection with MT Highway 89 on the Blackfeet Indian Reservation. The rehabilitation of the first 12 miles of the Many Glacier Road was completed in 2021.

To assess the condition of the pavement on Many Glacier Road, a pavement evaluation was conducted by Western Federal Lands Highway Division (WFL) in 2022. The purpose was to gain better understanding of the current pavement condition in order to choose the best rehabilitation option for restoring the remaining portion of the Many Glacier Road. The draft version of the Pavement Evaluation Report is attached to this memorandum as Appendix 1.

Acronyms

AASHTO American Association of State Highway Transportation Officials AADT Annual Average Daily Traffic ACP Asphalt Concrete Pavement ADT Average Daily Traffic FHWA Federal Highway Administration ESAL Equivalent Single Axle Load FLH Federal Lands Highways FP-14 Standard Specifications for Construction of Roads and Bridges on Federal

Highway Projects PDDM Project Design and Development Manual WFL Western Federal Lands Highway Division

Subgrade Data

Glacier National Park had conducted geotechnical investigations along the Swiftcurrent corridor as part of the National Park Headquarters Wastewater System Improvements and the Swiftcurrent Water Distribution. The drilling, conducted in 2022, included a total of eight borings. Two of the borings, SW-11 and SW-12, were drilled along the current project area. The information on the boring log for SW-11 shows 1 inch of asphalt on top of loose to dense, red-brown, poorly graded gravel with silt and sand. Classified as GP-GM according to Unified Soil Classification System. For SW-12, the boring log shows 3 inches of asphalt on top of medium dense, brown, silty sand with gravel. Classified as SM according to Unified Soil Classification System. Geotechnical Memorandum for Swiftcurrent Spur Road Rehabilitation (Geotechnical Memo 3123) that contains the boring log information is attached to this report as Appendix 2.

WFL conducted separate Geotechnical investigations in 2023. The investigation was composed of two subgrade borings, BH-01-SC and BH-02-SC, that were advanced to the depth of 5.5 feet below ground surface and drilled on the proposed new parking area west of the Swiftcurrent Motor Inn. Soil samples extracted from depths between 0.5 feet and 5.5 feet were classified as A-1-a following AASHTO M 145 for soil classification. The boring log information and WFL test results are provided in Appendix 2.

Considering the type of soil encountered on the first 5 feet of the strata on Many Glacier Road and areas designated for parking lot expansions, the resilient modulus of subgrade layer is assumed as 12,000 psi.

Traffic Data

The traffic data was obtained from National Park Service Visitor Use Statistics database at https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Traffic%20Counts?Park =GLAC. Many Glacier received an annual total of 128,064 visitations during 2022. The number of visitations during 2022 were higher than any previous years and also higher than 2023. As such, 2022 is selected as the base year for traffic calculations to forecast the most critical traffic loading on Many Glacier Road.

Using 2022 traffic counts for Many Glacier, the ADT is 700 for Many Glacier Road. Assuming truck traffic composes 10% of traffic, truck factor is 2.0 ESAL per truck, and the annual truck volume growth rate is 2%, the 18-kip ESALs for a 20-year period design life is projected to be about 515,000.

https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Traffic%20Counts?Park=GLAC https://irma.nps.gov/Stats/SSRSReports/Park%20Specific%20Reports/Traffic%20Counts?Park=GLAC

Recommended Pavement Structure

Many Glacier Road; Many Glacier Hotel Intersection To Swiftcurrent Motor Inn

The Pavement Evaluation Report (Appendix 1) notes that the existing pavement on the Many Glacier Road is moderately damaged with edge deterioration, rutting, and minor cracking. Considering that the majority of pavement is in good condition, a structural overlay is recommended for the section to extend the service life of the pavement structure.

To obtain the required roughness on the road surface, a leveling course is recommended prior to placement of the structural overlay. Table 1 provides recommendations for rehabilitation of section of Many Glacier Road between Many Glacier Hotel Intersection and Swiftcurrent Motor Inn.

Table 1 - Recommended Pavement Design for Rehabilitation of Many Glacier Road; Many Glacier Hotel Intersection To Swiftcurrent Motor Inn Thickness (inches)

Description

2 Asphalt Concrete Pavement (Section 403, estimated @ 1.94 tons/cuyd)

1 Asphalt Concrete Pavement, Wedge and Leveling (Section 403, estimated @ 1.94 tons/cuyd)

It is recommended that asphalt concrete pavement layer be placed in one lift. Tack coat is required prior to placing the asphalt concrete layer and between wedge and leveling course and existing pavement. Recommended tack coat application rate is 0.1 gal/sqyd. The binder grade designation for the project is PG 58-34.

Parking Area Expansions at Swiftcurrent Motor Inn and Along the Many Glacier Road

The recommendations for parking area expansions are developed using methods from the AASHTO 1993 Pavement Design Guide and guidance from Chapter 11 of the FLH Project Design and Development Manual (approved 2018), and previous experiences at Glacier National Park. Pavement design variables are provided in Table 2 and pavement structure recommendations for parking area expansions are provided in Table 3.

Table 2 - Pavement Design Variables for Parking Area Expansions Description Value Source Initial Serviceability 4.2 FLH PDDM 11.2.1.1 Terminal Serviceability 2.5 FLH PDDM 11.2.1.1 Reliability Level 75% FLH PDDM 11.2.2 Overall Standard Deviation 0.49 FLH PDDM 11.2.2 18-kip ESALs for a 20-year period design

515,000 Traffic Data section of the current report

Roadbed Soil Resilient Modulus 12,000 psi Subgrade Data Section of the current report

Table 3 - Recommended Pavement Design for Parking Area Expansions Thickness (inches)

Description

3 Asphalt Concrete Pavement (Section 403, estimated @ 1.94 tons/cuyd)

8 Roadway Aggregate, Method 2 (Section 302, estimated @ 1.97 tons/cuyd)

It is recommended that asphalt concrete pavement layer be placed in one lift. The binder grade is designated as PG 58-34.

Specifications

Materials will provide SCRs for Sections 403 and 302 for inclusion in the plan-in-hand package.

Appendix 1

Draft Pavement Evaluation Report

Federal Highway Administration

Pavement Evaluation Report Glacier National Park

Rehabilitation of Two Medicine Road Rehabilitation of Many Glacier Road from Hotel Intersection to Swiftcurrent

Motor Inn Glacier County, Montana

MT NP GLAC 12(2)

MT NP GLAC 14(5)

June 2022

Glacier National Park Road Rehabilitation i

TABLE OF CONTENTS

1 Description of Review

2 Two Medicine

2.1 Two Medicine Road

2.1.1 MP 0.0 – 1.0

2.1.2 MP 1.0 – 3.0

2.1.3 MP 3.0 to MP 5.7

2.1.4 MP 5.7 to MP 7.2

2.2 Two Medicine Lake Parking Area

3 Swiftcurrent

3.1 Swiftcurrent Road

3.2 Swiftcurrent Parking

4 Conclusion

Glossary of Pictures; Two Medicine Road and Parking Lot, Swiftcurrent Road and Parking Lot, and Park Headquarters

LIST OF FIGURES

Figure 1. Poorly patched potholes and ruts that are caused by frost heave action between MP 0.7 and MP 0.9

Figure 2. Moderate to severe rutting that is transforming into potholes between MP 0.7 and

MP 0.9

Figure 3. Transverse cracking and bumps, caused by differential settlement, between MP

0.7 and MP 0.9

Figure 4. General frost heave damage on the roadway between MP 1.0 and 3.0

Figure 5. Poor drainage, poor patching, and degradation between MP 1.1 and MP 1.2

Glacier National Park Road Rehabilitation ii

Figure 6. Edge cracks caused by differential settlement at vicinity of MP 1.3

Figure 7. Continues rutting and edge cracks at the vicinity of MP 2.0

Figure 8. Continues moderate to severe rutting at a) MP 3.0 and b) MP 5.3 caused by frost heave action

Figure 9. Ruts, caused by frost heave action, that are improperly patched and distressed again, vicinity of MP 5.1

Figure 10. Different distresses at Two Medicine Road park entrance station between MP

4.0 and MP 4.2 a) rutting, improper patching, and potholes, b) potholes and ruts caused by frost heave action, c) loss of edge support, and d) improper patch on the westbound, seemingly for stabilizing the slope

Figure 11. Transverse cracks and longitudinal cracks caused by frost heave action at a) MP 6.9, b) MP 7.0, c) MP 6.6, and d) MP 7.0

Figure 12. Edge deterioration, poor patching, and frost heave damage at a) MP 7.0, b) MP 5.8, c) MP 7.0, and d) MP 5.7

Figure 13. Pavement distresses at Two Medicine Lake parking are a) accumulation of rainwater in the localized settled and cracked area, b), block cracks, c) frequent diagonal cracks, and d) cracks surrounding settled area

Figure 14. Drainage issues and pavement edge deterioration

Figure 15. Continues rutting on the road segment

Figure 16. Poor drainage, raveling, and slippage cracks

Figure 17. Polished aggregate surface

LIST OF TABLES

Table 1. Location and type of severe pavement distresses on Two Medicine Road

Glacier National Park Road Rehabilitation 1

1 Description of Review

On June 13th-15th, 2022 a pavement evaluation was conducted in Glacier National Park by Corbin Williams and Nassim Sabahfar, Western Federal Lands Highway Division Civil Engineer in training and Materials Engineer. The intent of the investigation was to evaluate general pavement performance along a selection of specific routes within the park. Two road sections and three parking areas were evaluated during this time frame in three separate locations throughout the park as follows:

Two Medicine Road and Two Medicine Lake Parking Area Two Medicine Road is a 7.2 mile long route near East Glacier Park off Montana State Highway 49 that provides access to Two Medicine Lake, Two Medicine Ranger Station, and Two Medicine Campground. Natural viewpoints and hiking trail heads are scattered throughout the route. Two Medicine Parking Area is located at the west end of Two Medicine Road at MP 7.2. The parking area is located along the Northeast shore of Two Medicine lake providing access to the South Shore trailhead and ferry dock.

Many Glacier Road from Many Glacier Hotel Intersection to Swiftcurrent Motor Inn and Parking Area Many Glacier Road is approximately 1 mile long route from Many Glacier Hotel intersection to Swiftcurrent Motor Inn (MP 11.5 to MP 12.5). The Many Glacier Parking Area is located at the West end of Many Glacier Road (MP 12.5) and provides access to Swift Current Motor Inn and Many Glacier Campground, along with multiple trailheads.

Glacier Headquarters Parking Area Glacier headquarters parking area encompasses multiple parking areas and a section of Grinnel Drive that provides access to Park Headquarters office, community building, and residential areas.

The pavement evaluation report for Glacier Park Headquarter area is provided in a separate report.

The investigations entailed visual evaluation of the pavement conditions by traversing the routes by foot and vehicle. Areas with more extensive pavement distress were traversed on foot to obtain a more definitive and descriptive assessment of the damage. Segments in relatively good condition were reviewed from a slow moving vehicle with on-the-ground assessments performed at localized areas of distress. Pavement conditions were logged by hand with accompanying photographic documentation and GPS positioning. A photo log of the sections investigated during this field visit is provided in Appendix A.

Glacier National Park Road Rehabilitation 2

2 Two Medicine

2.1 Two Medicine Road

The pavement is generally in poor condition and severely distressed along Two Medicine Road with some sections showing low to moderate levels of distress. Based on the type and severity of distresses, the road is divided into four sections as follows:

MP 0.0 – 1.0

MP 1.0 – 3.0

MP 3.0 – 5.7

MP 5.7 – 7.2

2.1.1 MP 0.0 – 1.0

The pavement is moderately damaged with the list of pavement distresses, in order of frequency, as follows:

• Frost heave damage

• Potholes and patching

• Rutting

• Differential settlement

• Shoving

• Edge cracks and delamination

• Transverse cracking

The upward and downward movement of the pavement caused by frost heave action has caused potholes and ruts on this section of the road. Potholes and ruts have been poorly patched, distressed, and begun to ravel. Moderate to severe rutting, differential settlement, and edge cracks are frequent along the section as well. Differential settlement throughout the section has led to bumps in the roadway and areas of impeded drainage. The settlements have been patched poorly, causing reveling and shoving along the driving surface. Transverse cracks are infrequent throughout this section and seem to have caused by differential settlement.

Figure 1 shows poorly patched potholes and ruts caused by frost heave action and Figure 2 shows moderate to severe rutting that is transforming into potholes between MP 0.7 and MP 0.9. Figure 3 shows an example of transverse cracks on the road way and a road bump at vicinity of MP 0.8.

Glacier National Park Road Rehabilitation 3

Figure 1. Poorly patched potholes and ruts that are caused by frost heave action between MP 0.7 and MP 0.9

Glacier National Park Road Rehabilitation 4

Figure 2. Moderate to severe rutting that is transforming into potholes between MP 0.7 and MP

0.9

Glacier National Park Road Rehabilitation 5

Figure 3. Transverse cracking and bumps, caused by differential settlement, between MP 0.7 and

MP 0.9

2.1.2 MP 1.0 – 3.0

The pavement is severely damaged with the list of pavement distresses, in order of frequency, as follows:

• Frost heave damage

• Differential settlement

• Potholes and patches

• Bumps

Glacier National Park Road Rehabilitation 6

• Rutting

• Loss of edge support

Frequent frost heave damages and differential settlements have caused numerous bumps and loss of edge support on both sides of the road. Minor to severe rutting is present throughout the entire length of the section and transverse cracks are present as well.

Figure 4 shows the general condition of the road as affected by frost heave action with depression under the wheel path and scraped surface between the wheels caused by plawing the snow during winter. Between MP 1.1 and 1.2 poor drainage has caused multiple issues on the road. The effort has been made to address the settlement by adding gravel and the gravel has displaced and distressed. Figure 5 shows pictures of the road condition between MP 1.1 and 1.2.

Figure 6 shows edge cracks that are caused by differential settlement at vicinity of MP 1.3. Figure 7 shows the rutting that is continuous on the section along with transverse cracks at vicinity of MP 2.0.

Figure 4. General frost heave damage on the roadway between MP 1.0 and 3.0

Glacier National Park Road Rehabilitation 7

Figure 5. Poor drainage, poor patching, and degradation between MP 1.1 and MP 1.2

Glacier National Park Road Rehabilitation 8

Figure 6. Edge cracks caused by differential settlement at vicinity of MP 1.3

Glacier National Park Road Rehabilitation 9

Figure 7. Continues rutting and edge cracks at the vicinity of MP 2.0

2.1.3 MP 3.0 to MP 5.7

The pavement is severely damaged with the list of pavement distresses, in order of frequency, as follows:

• Frost heave damage

• Rutting

• Fatigue cracks

• Potholes

• Loss of Edge Support

Rutting caused by frost heave action is continuous throughout the section. Some of the ruts are improperly patched and distressed again. Fatigue cracks that have turned into potholes, differential settlement, and loss of edge support are frequent as well.

Figure 8 shows the continuous moderate to severe rutting and rutting caused by frost heave action.

Figure 9 shows rutted sections that are improperly patched and distressed again.

MP 4.0 to 4.2 is the Two Medicine Road park entrance station. The surrounding pavement has severe distress in the form of rutting, potholes, and differential settlement that has caused loss of edge support. Exiting the station on the westbound there is a poorly patched area. The patching

Glacier National Park Road Rehabilitation 10 seems to have put in place for addressing the slope stability issue. Figure 10 shows different distresses at the vicinity of entrance station.

Figure 8. Continues moderate to severe rutting at a) MP 3.0 and b) MP 5.3 caused by frost heave action

Glacier National Park Road Rehabilitation 11

Figure 9. Ruts, caused by frost heave action, that are improperly patched and distressed again, vicinity of MP 5.1

Glacier National Park Road Rehabilitation 12

Figure 10. Different distresses at Two Medicine Road park entrance station between MP 4.0 and MP 4.2 a) rutting, improper patching, and potholes, b) potholes and ruts caused by frost heave action, c) loss of edge support, and d) improper patch on the westbound, seemingly for stabilizing the slope

2.1.4 MP 5.7 to MP 7.2

The pavement is moderately damaged with the list of pavement distresses as follows:

• Frost heave damage

• Transverse cracks

• Longitudinal cracks caused by frost heave action

• Loss of edge support

• Poor patching

Damages caused by frost heave action are almost continues on this section of the road as well but the severity of damages is less than the former sections of the road. Transverse cracks are more frequent on this section and longitudinal cracks (caused by frost heave action), edge cracks on both sides of the road, and poor patching are frequent as well.

Glacier National Park Road Rehabilitation 13

Figure 11 shows transverse and longitudinal cracks and Figure 12 shows edge deterioration and poor patching on multiple locations on the road segment.

Figure 11. Transverse cracks and longitudinal cracks caused by frost heave action at a) MP 6.9,

b) MP 7.0, c) MP 6.6, and d) MP 7.0

Glacier National Park Road Rehabilitation 14

Figure 12. Edge deterioration, poor patching, and frost heave damage at a) MP 7.0, b) MP 5.8, c)

MP 7.0, and d) MP 5.7

Glacier National Park Road Rehabilitation 15

The list and location of severe pavement distresses on Two Medicine Road are tabulated in Table 1.

Table 1. Location and type of severe pavement distresses on Two Medicine Road

Approx.

MP Distress Type Associated Fig. Comments

0.7-0.9 Poorly patched potholes Figure 1 Caused by frost heave action

0.7-0.9 Ruts that are transferring to potholes Figure 2 Caused by frost heave action

0.7-0.9 Transverse cracking & bumps

Figure 3 Caused by differential settlement

1.1-1.2 Poor drainage, poor patching, & degradation Figure 5

5.3 Severe rutting Figure 8 b) Caused by frost heave action

5.1 Severe ruts that are

improperly patched Figure 9 Caused by frost heave action

4.0-4.2 Rutting, Patching, & potholes Figure 10 Caused by frost heave action and differential settlement

2.2 Two Medicine Lake Parking Area

Two Medicine Lake parking is severely distressed with frequent fatigue and block cracks scattered in the area. Majority of cracks have occurred on localized settled areas, forming puddles that collect rainwater and allow for further infiltration of moisture into the pavement structure. Figure 13 shows different pavement distresses at Two Medicine Lake parking area.

Glacier National Park Road Rehabilitation 16

Figure 13. Pavement distresses at Two Medicine Lake parking are a) accumulation of rainwater in the localized settled and cracked area, b), block cracks, c) frequent diagonal cracks, and d) cracks surrounding settled area

3 Swiftcurrent

3.1 Swiftcurrent Road

The pavement is moderately damaged with the list of pavement distresses, in order of frequency, as follows:

• Pavement edge deterioration

• Rutting and minor Cracking

The main issue on the road section is poor drainage along shoulders leading to deterioration of pavement edge. Rutting and minor cracks are present in driving surface as well. Figure 14 shows drainage issues and pavement edge deterioration caused by it. Figure 15 shows rutting that is almost continuous along the road segment.

Glacier National Park Road Rehabilitation 17

Figure 14. Drainage issues and pavement edge deterioration

Glacier National Park Road Rehabilitation 18

Figure 15. Continues rutting on the road segment

3.2 Swiftcurrent Parking

Swiftcurrent Parking Area has a large amount of standing water and debris from poorly drained runoff. The pavement is moderately damaged with some slippage cracks, raveling, and polished aggregates. Figure 16 shows drainage issues and an example of slippage crack. Figure 17 shows the polished aggregate surface in the Swift Current parking area.

Glacier National Park Road Rehabilitation 19

Figure 16. Poor drainage, raveling, and slippage cracks

Figure 17. Polished aggregate surface

Glacier National Park Road Rehabilitation 20

4 Conclusion

This report presents the general evaluation of the pavement condition of Two Medicine Road, Two Medicine Lake parking lot, Swiftcurrent Road, and Swiftcurrent parking lot in Glacier National Park based on the field investigation conducted on June 13 – 15, 2022. The majority of segments evaluated including but not limited to Two Medicine Road and Parking are beyond repair by common preservation measures such as bituminous surface treatments, crack sealing/filling, mill and overlay, and patching. The majority of distresses mentioned in Sections 2and 3 for each road segment are rooted in deeper pavement layers, making reconstruction of entire pavement sections unavoidable.

Any further evaluation on the methodology and approach to use for roadway improvements and rehabilitation alternatives will depend on the results of subsurface explorations. Subsurface explorations for Swiftcurrent Road and Parking lot and Two Medicine Road and Parking lot are scheduled for September and October of 2022.

Glacier National Park Road Rehabilitation 1

Glossary of Pictures; Two Medicine Road and Parking Lot, Swiftcurrent Road and Parking Lot, and Park Headquarters

Glacier National Park Road Rehabilitation 2

Figure A- 1. Moderate frost heave damage, Two Medicine Road (vicinity of MP 7.0)

Figure A- 2. Edge deterioration on both sides of the road and transverse cracks, Two Medicine Road (vicinity of MP 7.0)

Glacier National Park Road Rehabilitation 3

Figure A- 3. Longitudinal cracks caused by frost heave, Two Medicine Road (MP 6.0 – MP 7.0)

Figure A- 4. Distortion caused by frost heave action, Two Medicine Road (vicinity of MP 6.0)

Glacier National Park Road Rehabilitation 4

Figure A- 5. Drainage and degradation of road surface, Two Medicine Road (MP 1.1)

Glacier National Park Road Rehabilitation 5

Figure A- 6. Edge failure, Two Medicine Road (vicinity of MP 5.5)

Figure A- 7. Bridge Approaches, Two Medicine Road (MP 5.2)

Glacier National Park Road Rehabilitation 6

Figure A- 8. Hole in the ground, Two Medicine Road (MP 1.8)

Figure A- 9. Frost heave damage, Two Medicine Road (vicinity of MP 1.0)

Glacier National Park Road Rehabilitation 7

Figure A- 10. Frost heave damage and loss of edge support, Two Medicine road (vicinity of MP 1.0)

Figure A- 11. Frost heave damage and potholes, Two medicine Road (vicinity of MP 5.0)

Glacier National Park Road Rehabilitation 8

Figure A- 12. Frost heave damage and loss of edge support at near park entrance station, Two Medicine Road (MP 4.1)

Figure A- 13. Patching on son shoulder, Two Medicine Road (MP 4.0)

Glacier National Park Road Rehabilitation 9

Figure A- 14. Potholes caused by frost heave action, Two Medicine Road (vicinity of MP 3.1)

Figure A- 15. Parking lot at Running Eagle Falls nature trail, Two Medicine Road (MP 5.2)

Glacier National Park Road Rehabilitation 10

Figure A- 16. Two Medicine Parking Lot

Figure A- 17. Swiftcurrent Road

Glacier National Park Road Rehabilitation 11

Figure A- 18. Swiftcurrent Road

Figure A- 19. Swiftcurrent Road

Glacier National Park Road Rehabilitation 12

Figure A- 20. Swiftcurrent Parking Lot

Figure A- 21. Swiftcurrent Parking Lot

Glacier National Park Road Rehabilitation 13

Figure A- 22. Swiftcurrent Parking Lot, cracking due to root upheaval

Figure A- 23. Swiftcurrent Parking Lot, chip seal raveling

Appendix 2

Geotechnical Memorandum for Swiftcurrent Spur Road Rehabilitation

158377846

M E M O R A N D U M

610 E. Fifth Street

Vancouver, WA 98661

DATE: October 16, 2023

TO: Michael Traffalis Project Manager

FROM: Leah Wilmot Geotechnical Engineer

SUBJECT: Geotechnical Memo 3123 Final Geotechnical Recommendations Swiftcurrent Spur Road Rehabilitation

Glacier County, Montana

INTRODUCTION

This memorandum provides geotechnical investigation results, design, and construction recommendations for the Swiftcurrent Spur Road Rehabilitation Project being performed for Glacier National Park in Montana. The project stationing referenced in this report is from 30% Design Set, dated June 2023.

Project Description

The geotechnical scope of work for this project included a literacy review, a visual reconnaissance along the proposed alignment and a subsurface investigation program consisting of two subgrade borings. The subgrade borings, and laboratory testing was completed by Western Federal Lands Highway Division (WFL) and a subcontractor.

This memorandum was prepared to provide geotechnical recommendations for roadway rehabilitation design and construction considerations.

This memorandum supersedes all other previous memorandums for this project.

PROJECT DESCRIPTION

The project is located in Glacier National Park on Swiftcurrent Spur Road in Glacier County, Montana as shown in Figure 1 Regional Map. The project starts at the Swiftcurrent Motor Inn Parking Area at stationing 15+98 and ends at stationing 66+65 near the intersection of Swiftcurrent Spur Road and Many Glacier Loop Road.

Swiftcurrent Spur Road Rehabilitation October 2023

Figure 1 Regional Map

The project consists of rehabilitating 0.96 miles of existing asphalt pavement covered road, construction of a pedestrian path, the addition of a new parking lot, and adding new parking spaces along the alignment as seen in Figure 2.

Figure 2 Vicinity Map

Previous Work

HDR Engineering by Shannon and Wilson conducted a geotechnical investigation that included geotechnical borings along the Swiftcurrent Spur Road in 2022 (Shannon and Wilson, 2022).

This geotechnical investigation was conducted for GNP as part of the National Park Headquarters Wastewater System Improvements and the Swiftcurrent Water Distribution System Replacement Project.

A total of eight geotechnical borings were drilled at the Swiftcurrent site. Of those eight geotechnical borings, two, SW-12 and SW-11, were drilled along the currently proposed alignment for this project a seen in Figure A-1 in Appendix A on June 6, 2022, and June 8, 2022.

Geotechnical boring SW-11 was advanced to a depth of 11.5 feet bgs. The boring encountered 1-inch of asphalt overlying loose to dense, poorly graded gravel with silt and sand. Groundwater was encountered at 5.3 feet bgs at this location.

Geotechnical boring SW-12 was advanced to a depth of 11.5 feet below ground surface (bgs).

The boring encountered 3-inches of asphalt overlying medium dense silty sand with gravel.

Medium dense to dense poorly graded gravel with clay and sand was underlying the above silty sands.

Geotechnical boring locations of SW-11 and SW-12 can be seen in Appendix A.

GEOLOGY

The project is located in a region of varied geologic processes and forces. The principal natural architects of the current geologic scene have been the geologic history that created the rock types in the area, the mountain building forces that created the tremendous vertical relief, especially near the west end of Many Glacier Road, and the glaciation that carved the huge U-shaped valley and left lakes and extensive deposits of silty and clayey gravel in the bottom and sides of the Swiftcurrent/Many Glacier Valley.

Thrust faulting was a major factor in creating the mountainous terrain and was directly responsible for reversing the normal positions of younger rocks overlying older rocks. The west-to-east upward angle of thrust faulting in the eastern part of Glacier National Park has brought much older, relatively hard metasedimentary rocks from deep within the earth’s crust and placed them on top of younger, relatively soft sedimentary rocks. Geologists have interpreted the age difference between the two rock masses to be over 500 million years. This feature extends for tens of miles along the entire east side of Glacier National Park and is known as the Lewis Thrust Fault.

Paul Carrara (1990) mapped the surficial geology within the GNP. The mapping along the project alignment shows till (t3) as seen in Figure 3 Surficial Geology of Glacier National Park by Carrara (1990). The “t3” unit is dated to be late Pleistocene and is described as unsorted subrounded to subangular boulder rubble, consisting mainly of Belt Supergroup rocks and minor amounts of sand, silt, and clay. This unit is found on valley floors within mountainous areas where it was deposited as ground moraine by local mountain glaciers.

Figure 3 Surficial Geology of Glacier National Park by Carrara (1990)

Geologic Hazards

There are no mapped geologic hazards within the project’s vicinity. The closest mapped fault is the Mission fault which is approximately 50 miles southwest of the project vicinity near Kalispell, Montana (USGS, 2023).

SITE CONDITIONS

The project is located along the northern Rocky Mountains front range and elevation ranges from approximately 4,900 feet near the intersection of Swiftcurrent Spur Road and Many Glacier Loop Road to about 4940 feet at the Swiftcurrent Motor Inn. The mountains surrounding the Swiftcurrent Valley are dramatically steep and rises to an elevation of up to approximately 9,250 feet at Mt. Wilbur.

The Swiftcurrent Spur Road is located on the south facing slope of the valley floor. The valley consists of quaking aspen groves, wild grasses and deciduous forest that transitions into a montane forest near the Swiftcurrent Motor Inn. The north slopes along the roadway consist of exposed shear rocks faces compromised of the Belt Supergroup.

The two subgrade borings, located north of the existing Swiftcurrent Motor Inn parking lot, encountered topsoil and duff thickness of approximately 0.3- to 0.6-inches. Topsoil is defined as surficial soil layers that contain sufficient amounts of organic materials, including peat, rootlets, and plant matter to be classified as unsuitable materials in Section 101 of the FP-14 (FHWA, 2014). In general, the area is covered in thick vegetation, including liverworts and mosses, in addition to numerous trees and stumps.

The Federal Lands Highway (FLH) Pavement Evaluation Report (Nassim, 2022) that encompassed the Swiftcurrent Spur Road Rehabilitation Project noted that the pavement along the Swiftcurrent Spur Road was moderately damaged with observed pavement edge deterioration, rutting and minor cracking. The Swiftcurrent Parking Area was observed to have large amounts of standing water and debris from poorly drained runoff. The pavement was observed to be moderately damaged with slippage cracks, raveling, and polished aggregate (Western Federal Lands Highway Division, 2022).

Average Temperatures and Precipitation

The project site has a highly variable climate. The winter months see cold temperatures and snow cover the entire season that transition into warmer, rainier springs. Summer months are typically hot during the day and have cooler temperatures at night. During the fall, temperatures again become colder with snow possible by mid-September (NPS, 2023). Table 1 Climate Data Summary shows the average maximum and minimum temperatures, average monthly precipitations, and the average monthly snowfall data for the period of 1906 to 2011 for the Many Glacier, Montana USC00245361 weather station (Western Region Climate Center, 2023).

Table 1 Climate Data Summary Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Annual

Avg.

Max.

Temp.

(F)

22.8 34 37.1 46.6 56.5 64.8 72.5 70.8 61.1 46.7 36.4 28 48.1

Avg.

Min.

Temp.

(F)

2.8 17.2 20.4 29.2 36.5 42.1 45.1 44.3 39.5 31.3 21.2 11.1 28.4

Avg.

Total

Precip.

(in.)

5.47 2.71 3.66 1.82 3.57 4.9 1.82 2.09 3 3.3 3.11 5.35 40.8

Avg.

Total

Snowfall (in.)

63 21.1 36.6 21 5 1.5 0 0 1.5 8.8 18.9 33.1 210.5

Avg.

Snow Depth (in.)

No Data

Note: Period of Record: 1906 to 2011 USC00245361, Western Region Climate Center (2023)

SUBSURFACE CONDITIONS

Under the direction of WFL, SK Geotechnical drilled a total of two subgrade borings (BH-01-SC and BH-02-SC) in 2023 in the area of the proposed new parking area west of the Swiftcurrent Motor Inn. The subgrade borings were drilled to a depth of 5.5 below ground surface (bgs) on

May 24, 2023. The approximate locations of the subgrade borings and the approximate coordinates can be viewed in the investigation map in Appendix A and below in Table 2. The boring logs are included in Appendix B.

Table 2 Subgrade Boring Approximate Locations

Subgrade Boring

Coordinates

Latitude Longitude

BH-01-SC 48.79774 -113.67818

BH-02A-SC 48.798024 -113.677868

The geotechnical subgrade borings were performed in native soils to the west of the Swiftcurrent Motor Inn and north of the existing Swiftcurrent Parking Area. Drilling methods during the investigation included the use of a 12-inch power augur to advance the subgrade borings.

Large grab bag samples and moisture samples were obtained for each change in strata.

Test borings were logged in the field by SK Geotechnical. Disturbed soil samples were collected and delivered to WFL in Vancouver, Washington, where samples and draft test boring logs were reviewed by a WFL geotechnical engineer or engineering geologist. Following review, selected samples of soil were submitted to the WFL Materials Laboratory for testing. Final test boring logs were modified as necessary to reflect additional information from laboratory testing.

The Federal Lands Highway Soil Description and Identification Guidelines and Federal Lands Highway Rock Characterization Guidelines are used to characterize soil units encountered during drilling operations. The USCS, as outlined in ASTM 2487 and ASTM 2488, was utilized in subgrade boring logs and is based on distribution and behavior of fine-grained and coarse-grained soil constituents. Soil and rock descriptive terms and the USCS chart is provided in the Descriptive Terminology for Boring Logs at the beginning of Appendix B.

Laboratory Materials Testing

Laboratory test results were completed for select soil samples for the subgrade borings.

Laboratory tests consisted of soil testing to characterize subsurface materials and characterize engineering properties of soils that may be encountered during construction. A summary of laboratory testing can be found in Tables C-1 of Appendix C, along with individual sample laboratory test results provided in Appendix C.

SUBSURFACE CONDITIONS

This section provides a synthesis of observed subsurface conditions during the subsurface investigation. No groundwater was encountered during the drilling of the subgrade borings.

Soil and Rock Types

In general, the subgrade borings encountered a peat layer, interpreted as topsoil overlying poorly graded gravel with silt and sand or poorly graded sand with silt and gravel.

In BH-01-SC, we encountered a peat layer to a depth of 6-inchs bgs. Underlying the peat layer, we encountered poorly graded gravel with silt and sand and trace cobbles to the terminating depth of 5.5 feet. In BH-02A-SC, we encountered a peat layer to a depth of 3.6-inches bgs.

Underlying this layer, we encountered poorly graded sand with silt and gravel to the terminating depth of 5.5-feet.

ANALYSIS

The above information was analyzed to determine design recommendations for parking lot and design and cut and fill slopes. The following sections provide our final recommendations for roadway design.

Cut Slopes

Cut slope areas are expected along the project alignment. Cuts slopes are anticipated to be approximately 10 feet or less. We recommended a cut slope inclination of 1V:2H along the alignment in soil. Anticipated soil conditions at cut slope locations include poorly graded gravels and sands. Exceptions to these recommendations are possible with the approval of the project Geotechnical Engineer if field conditions should warrant changes.

Please refer to the investigation logs in Appendix B for additional details, interpretations, and other data.

Soil Embankment Slopes

All other areas are considered embankment areas and should be generally limited to maximum slopes of 1V:2H with exceptions possible with the approval of the project Geotechnical Engineer. These slope angles assume the use of the on-site native poorly graded gravel and sand materials for embankment fill. These slopes should be designed for both temporary and permanent erosion control such as the use of a bonded-fiber hydromulch or rolled erosion control products (RECP). If layers of organics are encountered in the excavation it should not be used as embankment material.

CONSTRUCTION CONSIDERATIONS

Excavation

Observed topsoil depths are between 3.6- to 6-inches and will vary depending on the density of the vegetation at the location of the excavation. Conserve topsoil per 204.05 to be used on completed slopes per 624.

Based on the limited subgrade investigation and results of materials testing, excavated material may be reused for embankment construction, or may be processed to remove excessive fines and meet proper gradation as outlined under Section 704. – Soil. It is anticipated most material could be used as Unclassified Borrow (704.06). Reuse of excavated material can be considered to reduce the amount of waste and haul.

Processing of excavated material would require added space for material storage and processing on site with water during construction. Further, no subgrade samples were tested for durability, abrasion, weathering, and other tests for aggregate production suitability and mineral aggregate quality, so it is recommended aggregate testing be completed if uses other than Unclassified Borrow are considered.

As of the preparation of this memorandum, a suitable waste site has not been provided or identified by the County. Therefore, it will be the responsibility of the contractor to identify and procure a legal waste site in accordance with the contract.

Subgrade surfaces should consist of suitable materials to receive fill materials in preparation for a pavement section. Organics, loose soils, or other unsuitable materials should be removed from the locations. Subgrades should be covered immediately to prevent changes in moisture content or excessive drying, which could adversely affect the subgrade performance following construction.

If on-site moisture sensitive soils are encountered, they will be susceptible to disturbance and will generally provide inadequate support of construction equipment when the soil moisture content is above optimum and during wet weather conditions. These soils will be difficult to compact if they are over optimum moisture and use of vibratory compactors may cause pumping of subgrade soils. If pumping occurs, the soil should be dried to a moisture content near optimum (±2 percent of optimum moisture) and static compaction methods should be used.

Embankment

Minor embankments including sliver fills are planned for the project. We recommend planning for imported materials to be used in the embankment construction due to the types present in the majority of the roadway excavations.

During embankment preparation if ground conditions should differ from what is expected, the project Geotechnical Engineer should be contacted to assess the conditions for adverse effects on the design.

Material and Aggregate Sources

Imported fill materials are planned for select borrow, roadway aggregates and other materials.

As the preparation of this memorandum there is no Government provided material source for this project. It is the Contractor’s responsibility to locate an approved material source from an available commercial or private source for all construction materials that meet the requirements of the contract.

If suitable soils are encountered and the Contractor should desire to use the onsite materials, it will be the Contractor’s responsibility to ensure that the materials are processed to meet the contract requirements.

LIMITATIONS

This memorandum was prepared to provide geotechnical recommendations for the design and construction of the Swiftcurrent Spur Road Rehabilitation Project in Glacier National Park, Montana. Professional judgments and recommendations are presented in this memorandum.

They are based partly on evaluation of the technical information gathered and partly on the Geotechnical Team’s general experience with subsurface conditions in the area. It should be noted that the borings might not represent potentially unfavorable subsurface conditions between borings. The observed water levels and/or conditions may vary considerably, with time, according to the climate, rainfall, and other factors and are otherwise dependent on the duration of, and methods used in, and interpretations made form the subsurface investigation program.

If, during construction, soil conditions are encountered that vary from those discussed in this memorandum, or if project stationing, and/or configurations change, the WFL Geotechnical Team should be notified immediately in order to evaluate what effects, if any, the changes have on the recommendations contained in this memorandum. The recommendations presented in this report are applicable only to this specific site. These data are not to be used for other purposes.

REFERENCES

Carrara, P.E., 1990, Surficial geologic map of Glacier National Park, Montana, Miscellaneous Investigations Series Map I-1508-D, Scale 1:100,000

Federal Lands Highway, FP-14, (2014) Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects, U.S. Department of Transportation, Federal Highway Administration

National Park Service, Glacier National Park Montana, 2023, Weather: Weather - Glacier National Park (U.S. National Park Service) (nps.gov) (accessed September 2023).

Shannon and Wilson, 2022, “Preliminary Geotechnical Report, NPS Glacier National Park Headquarters and Swiftcurrent Utility Improvements”, Prepared for HDR Engineering Inc., dated December.

U.S. Geological Survey’s Interactive Quaternary Faults Database: U.S. Quaternary Faults (arcgis.com) (accessed September 2023).

Western Federal Lands Highway Division (WFLHD), 2022, DRAFT Pavement Evaluation Report, Rehabilitation of Two Medicine Road, Rehabilitation of Many Glacier Road from Hotel Intersection to Swiftcurrent Motor Inn, June 2022.

Western Regional Climate Center, 2023, Cooperative Climatological data summaries: MANY GLACIER, MONTANA - Climate Summary (dri.edu) ( September 2023)

Whipple, J.W., 1992, Geologic map of Glacier National Park, Montana, Miscellaneous Investigations Series Map I-1508-F, Scale 1:100,000.

CLOSING

Please contact Leah Wilmot at (360) 619-7697 or Leah.Wilmot@dot.gov with any questions regarding this memorandum.

CC: Michael Traffalis, Project Manager

Chris Conrad, Highway Design Geotechnical File

Attachments: Appendix A: Figures

Appendix B: Test Boring Logs Appendix C: Laboratory Test Reports

APPENDIX A

Figure A-1 Shannon and Wilson Boring Locations Figure A-2 Subgrade Investigation Map

0 300 600

Approximate Scale In Feet

GLCA 307440 & 307606

NPS Glacier National Park

Flathead and Glacier Counties, Montana

SWIFTCURRENT

SITE AND EXPLORATION PLAN

FIG. 3

December 2022 107857-001

SHANNON & WILSON, INC.

Geotechnical and Environmental Consultants

Fishercap Lake

Swiftcurrent Creek

W ilb ur C re ek

Service Road

Loop Road

Route 3

SW-09

SW-10

SW-11

SW-12

SW-13

SW-14 SW-15

SW-16

N

LEGEND

&< Approximate Boring Location and DesignationSW-03

Headquarters

Swiftcurrent

National Geographic, Esri, Garmin, HERE, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, increment P Corp., Maxar

Many Glacier Campground

Existing Tank Location

Proposed Tank Location

Horizontal Directional Drilling Location

NPS Administration Area

Chlorination Building

Swiftcurrent Motor Inn

Altyn Peak

Figure A-1: Shannon and Wilson Subsurface Exploration Map showing locations of SW-12 and SW-13. (Shannon and Wilson, 2022)

610 East Fifth Street Vancouver, WA 98661

Project No. Subgrade Investigation Map Figure A‐2MT NP GLAC 14(6) Scale

BH‐02A‐SC and BH‐01‐SC N/A File Name:

N/A Date:

September 2023

APPENDIX B

B-1 Test Boring Logs

B-2 Shannon and Wilson 2022 Boring Logs

APPENDIX B-1

Test Boring Logs

Project Name: Swift Current Motor Inn Parking Lot Expansion Project Location: Glacier National Park, Montana

Fracture Frequency (fractures per foot) Percent Passing No. 200 Sieve Liquid Limit (%) Non-Plastic Plastic Limit (%) Pocket Penetrometer Reading Rock Core Recovery Rock Quality Designation Specific Gravity Unconfined Compressive Strength Vibrating Wire Piezometer Water Content (%)

BORING LOG LEGEND

DRILLING METHOD SYMBOLS

SAMPLE TYPE SYMBOLS

Grab Sample

Hollow Stem Auger

ABBREVIATIONS

FF

Fines

LL

NP

PL

PP

Rec

RQD

SG

UC

VWP

WC

U. S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

FEDERAL LANDS HIGHWAY DIVISION

F H

W A

B O

R

IN

G L

O G

L E

G E

N D

F

H W

A _D

A T

A T

E M

P

LA

T E

_2

.G

D T

/1 5/

:0

D :\T

W O

M E

D A

N D

S W

IF

T

C U

R R

E N

T \4

3.

G P

J ow er a ug er to

.5 '/1

2"

Fines = 7%

PEAT, black, moist. Topsoil.

0.5 ft Poorly graded GRAVEL with silt and sand (GP-GM), gray, fine gravel to coarse gravel, angular to subangular, trace cobbles. A-1-a (0).

5.5 ft Bottom of borehole at 5.5 ft.

D ril lin g

M et ho d

Field Blow Count (Recovery)No.

T yp e

Test Results

SAMPLE

BH-01-SC

Sheet: 1 of 1

Project Location: Glacier National Park, Montana

20 40 60 80

PL LLWC

N VALUE

20 40 60 80

Project Name: Swift Current Motor Inn Parking Lot Expansion D ep th ft)

MATERIAL DESCRIPTION

BORING LOG

U. S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

FEDERAL LANDS HIGHWAY DIVISION

F H

W A

L O

G

F H

W A

_D A

T A

T E

M P

LA

T

E .G

D T

/1 5/

:0

D :\T

W O

M E

D A

N D

S W

IF

T

C U

R R

E N

T \4

3.

G P

J

Groundwater Depth:

Notes:

After Drilling: No Groundwater Encountered

While Drilling: No Groundwater Encountered At Completion: No Groundwater Encountered

Moved 2' east of original staked location due to tree stumps.

Latitude: 48.79774° Longitude: -113.67818° Date Started: 5/24/23 Date Completed: 5/24/23 Driller/Company: E. Hollibaugh/SK Geotechnical

Logger/Company: C. Binstock/SK Geotechnical

Drill CME-75HT Hammer Type: NA

NP

G ra ph ic

L og ow er a ug er to

.5 '/1

2"

Fines = 6%

PEAT, black, moist. Topsoil.

0.3 ft

Poorly graded SAND with silt and gravel (SP-SM), gray, fine sand to coarse sand, angular to subangular, A-1-a (0).

5.5 ft Bottom of borehole at 5.5 ft.

D ril lin g

M et ho d

Field Blow Count (Recovery)No.

T yp e

Test Results

SAMPLE

BH-02A-SC

Sheet: 1 of 1

Project Location: Glacier National Park, Montana

20 40 60 80

PL LLWC

N VALUE

20 40 60 80

Project Name: Swift Current Motor Inn Parking Lot Expansion D ep th ft)

MATERIAL DESCRIPTION

BORING LOG

U. S. DEPARTMENT OF TRANSPORTATION

FEDERAL HIGHWAY ADMINISTRATION

FEDERAL LANDS HIGHWAY DIVISION

F H

W A

L O

G

F H

W A

_D A

T A

T E

M P

LA

T

E .G

D T

/1 5/

:0

D :\T

W O

M E

D A

N D

S W

IF

T

C U

R R

E N

T \4

3.

G P

J

Groundwater Depth:

Notes:

After Drilling: No Groundwater Encountered

While Drilling: No Groundwater Encountered At Completion: No Groundwater Encountered

Moved 26.5' east and 33.5' north of orginal staked location due to sloping terrain and trees.

Latitude: 48.798024° Longitude: -113.677868° Date Started: 5/24/23 Date Completed: 5/24/23 Driller/Company: E. Hollibaugh/SK Geotechnical

Logger/Company: C. Binstock/SK Geotechnical

Drill CME-75HT Hammer Type: NA

NP

G ra ph ic

L og

APPENDIX B-2

Shannon and Wilson 2022 Boring Logs

0.1

11.5 S

-1 S

-2 S

-3 S

-4

1 inch of Asphalt

Loose to dense, red-brown, Poorly Graded Gravel with Silt and Sand (GP-GM); moist.

Till

BOTTOM OF BORING

COMPLETED ON 06/08/2022

G ro un dw at er n ot e nc ou nt er e d du ri ng d ri lli ng

Hollow-Stem Auger Vine Laboratories CME 75 Truck Rig

LEGEND

Drilling Method:

Drilling Company:

Drill Rig Equipment:

Other Comments:

SOIL DESCRIPTION

GLCA 307440 & 307606

NPS Glacier National Park

Flathead and Glacier…