Attachment 7: Geotechnical Subsurface Invest

National Park Service

GCLA Bullfrog Launch Ramp

GLCA-220829

Preliminary Geotechnical Exploration

Final

February 2023

Prepared by:

Jacobs Government Services Company
Herndon, VA
Contract No. 140P2021D0007
Task Order No. 140P2021F0261

National Park Service
U.S. Department of the Interior
GCLA Bullfrog Launch Ramp

GLCA-220829

List of Figures

List of Tables

List of Appendices
Appendix A – Rock Core Boring Logs
Appendix B – Photolog
Appendix C – Rock Core Photologs
Appendix D – Laboratory Data Sheets
Appendix E – Geologic Maps and Cross-sections

Preliminary Geotechnical Exploration, Final

February 2023
Page i

National Park Service
U.S. Department of the Interior
GCLA Bullfrog Launch Ramp

GLCA-220829

Acronyms and Abbreviations
Acronym

Definition

~

approximately

>

greater than

bgs

below ground surface

ID

identifier

Jacobs

Jacobs Government Services Company

NPS

National Park Service

pcf

pound(s) per cubic foot

psi

pound(s) per square inch

RQD

Rock Quality Designation

UCS

unconfined compressive strength

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Preliminary Geotechnical Exploration, Final
Acronyms and Abbreviations

February 2023
Page ii

National Park Service
U.S. Department of the Interior
GCLA Bullfrog Launch Ramp

GLCA-220829

Chapter 1 – Introduction
This report summarizes the preliminary geotechnical exploration that was conducted for the Glen Canyon Launch Ramp project. The National Park Service proposes to modify or relocate launch ramps at four visitor use areas within Glen Canyon National Recreation Area due to unprecedented low water conditions at Lake Powell in order to develop a rapid response plan to maintain boater access with resilient, long-term, engineered solutions. Users must continue to have access to Lake Powell for recreational activities. The launch ramps serve a public health and safety need to provide safe access to the water as well as protect impacts to natural resources by providing designated access points to the water. The original water elevation for Lake Powell was 3,700 feet. At the time of this report in early 2023, the water level has fallen to 3,522 feet. The Bullfrog Launch Ramp is being relocated from its existing location to the Stanton Creek Area due to low water.
This geotechnical exploration gathered geological and subsurface information at the proposed launch ramp site for the conceptual design and provides geotechnical data to the design-build contractors to assist in their response to the request for proposals for