Attachment 11: GRCA North Rim GIR

Geotechnical Investigation Report

GRCA 318719: Rehabilitate North Rim
Utility Infrastructure
Grand Canyon North Rim, Arizona
Submitted to:
HDR Engineering, Inc.
419 Canyon Avenue
Fort Collins, CO 80521
Submitted by:
GEI Consultants, Inc.
350 Indiana Street, Suite 750
Golden, CO 80401
303.625.9502
August 11, 2025
Project No. 2305987

Nate C. Soule, P.E., P.G.
Principal Engineer

Matt P. Olson, P.E.
Project Manager

August 11, 2025
Project No. 2305987
VIA EMAIL: [email protected]
Matt Gough, P.E.
HDR Engineering, Inc.
419 Canyon Avenue
Fort Collins, CO 80521
Re:

Geotechnical Investigation Report
GRCA 318719: Rehabilitate North Rim Utility Infrastructure Grand Canyon North Rim, Arizona

Mr. Gough:
Submitted herewith is the Geotechnical Engineering Investigation for the North Rim Portion of the Grand Canyon National Park Rehabilitate North Rim Utility Infrastructure project. This study was conducted in accordance with our contract between GEI Consultants, Inc. and HDR Engineering, Inc. This report contains the results of our findings, an engineering interpretation with respect to the available project characteristics, and recommendations to aid design and construction of earth-related phases of this project.
If you have any questions regarding the contents of this report, please contact the undersigned. Sincerely,
GEI Consultants, Inc.

Rob D. Johanson, P.E.
Project Engineer

R. Charlie Magill, P.G.
Project Geologist

Matt. P. Olson, P.E.
Project Manager

Nate C. Soule, P.E., P.G.
Principal Engineer

www.geiconsultants.com

GEI Consultants, Inc.
350 Indiana Street, Suite 750
Golden, CO 80401
303.625.9502

Geotechnical Investigation Report
GRCA 318719: Rehabilitate North Rim Utility Infrastructure Grand Canyon North Rim, Arizona
August 11, 2025

1.

Introduction and Background

2.

Geologic Setting

2.1.
2.2.

Regional Geology
Karst Geology

3.

Geotechnical Investigation

3.1.

3.2.

Subsurface Investigation

3.1.1. Geotechnical Borings

3.1.2. Percolation Tests

3.1.3. Test Pit Investigation

3.1.4. Geotechnical Laboratory Testing

3.1.5. Corrosion Potential Testing

Geophysical Investigation

4.

Subsurface Conditions

4.1.

4.2.

Subsurface Materials

4.1.1. Existing Fill

4.1.2. Residuum

4.1.3. Kaibab Formation Bedrock

4.1.4. Karst Features

Groundwater

5.

Geotechnical Design Recommendations

5.1.
5.2.
5.3.
5.4.
5.5.
5.6.
5.7.
5.8.
5.9.

Foundation Recommendations
Lateral Earth Pressures
Mechanically Stabilized Earth Wall Recommendations