THRO 204 Buck Hill Road Geotechnical Report Full Signed

BUCK HILL ROAD

NP THRO 204(1)

BILLINGS COUNTY, ND

FINAL Geotechnical Report

Prepared by
Federal Highway Administration
Central Federal Lands Highway Division

Geotechnical Services Branch
November 2024

ii

SIGNATURE SHEET

Digitally signed by

DOMINIC J

DOMINIC J MONARCO

Date: 2024.11.25 11:35:04

MONARCO

-07'00'

Dominic J.T. Monarco, Geotechnical Engineer

DEVIN T DIXON

Digitally signed by DEVIN T

DIXON

Date: 2024.11.25 12:48:18 -07'00'

Engineer

For James M. Arthurs, P.E., P.G., Ph.D., Senior Geotechnical

Digitally signed by DEVIN

DEVIN T

T DIXON

Date: 2024.11.25 12:52:33

DIXON

-07'00'
Devin T. Dixon, P.E., Geotechnical Team Leader

Distribution
Electronic:
N:\ND\204(01)\Geotech\7_FinalDocs
K:\TechServices\Geotech\1. Geotech Project Reports
Project Management
Project Development, Lead Designer

Page | i

TABLES

TABLE 2.1

TABLE 2.2

TABLE 3.1

TABLE 3.2

TABLE 4.1

TABLE 4.2

Summary of Nearby Seismic Source Faults
Summary of Seismic Parameters Corrected for Site Class C Summary of the Field Exploration Program
Summaries of Laboratory Index Test Results
Generalized Buck Hill Landslide Mitigation Options
Estimated Material Properties of Native and Backfill Soils for Deep Patch Design

FIGURES

FIGURE 1:

FIGURE 2:

Typical Roadway Conditions
Past and Current Buck Hill Road Alignments

FIGURE 3:

Cross Section Deep Patch

PLATES

PLATE 1

PLATE 2

PLATE 3

PLATE 4

Project Site Map
Geology Map
Landslide Map
Boring Location Map

APPENDICES

APPENDIX A

APPENDIX B

APPENDIX C

APPENDIX D-1

APPENDIX D-2

APPENDIX E

Page | ii

Field Exploration Program
Laboratory Test Results
External and Internal Stability Analysis
Photographs March 9th – 10th
Photographs May 29th – June 3rd
Inclinometers SI-101 and SI-102

SECTION ONE - Introduction
1.1

BACKGROUND AND LOCATION

Buck Hill Road, also known as Route 204, is located in the southeast portion of the South Unit of Theodore Roosevelt National Park, (Park). The route begins at the intersection of Buck Hill Road and the South Unit Loop Road. The route then proceeds southeasterly for approximately ¾ of a mile and ascends approximately 300 feet vertically to the Buck Hill Overlook parking area. The Buck Hill Overlook is a very popular location in the Park with approximately 32% of Park visitors visiting this overlook. This project proposes to rehabilitate the existing pavement and address subsurface issues observed along the route, including a previously identified slide area. The project further proposes to reconstruct and expand the Buck Hill Overlook parking area at the end of the