Attachment 7

REPORT

Geological Assessment Findings and Recommendations
for Repairs and Corrective Actions
Blanchard Springs Caverns - Geological Assessment and Design Submitted to:

United States Forest Service
Southern Region (R08)
Ozark-St. Francis National Forest
Sylamore Ranger District
Submitted by:

Golder Associates Inc.
13515 Barrett Parkway Drive, Suite 260, Ballwin, Missouri, USA 63021

+1 314 984-8800
19129310
July 31, 2020 - Rev1

July 31, 2020 - Rev1

19129310

Distribution List
Golder Associates Inc.
United States Forest Service
Robert Peccia & Associates, Inc.

i

July 31, 2020 - Rev1

19129310

Executive Summary
The United States Forest Service (Forest Service) contracted Golder Associates Inc. (Golder) through Robert Peccia & Associates, Inc. (RPA) in September 2019 to perform various tasks associated with the Blanchard Springs Caverns – Geological Assessment and Design Project (the Project) at Blanchard Springs Caverns, located near Fifty-Six, Arkansas (Project Site or Site). This report of Geological Assessment Findings and Recommendations for Repairs and Corrective Actions (Report) presents the findings from Golder’s geotechnical investigation and site assessment, presents the methodology and results of geotechnical analyses completed to determine recommendations for permanent repairs, presents recommendations for permanent ground support in the assessment areas, presents recommendations for instrumentation and monitoring, presents replacement options for airlock doors and security doors, and includes a preliminary construction cost estimate and schedule. Golder visited the Site to complete the Site investigation/assessment on January 13-15, 2020. During the Site assessment, Golder gathered additional data and samples to aid in our geological assessment and design recommendations for five separate areas (assessment areas); the Dripstone Cave Entrance, Dripstone Cave Bypass Tunnel, Dripstone Cave Exit, Discovery Cave Exit, and Surface Sinkhole Area. For all areas, Golder visually observed rock and existing support conditions and used measuring devices to collect data. Samples of cavern roof rock were collected from loose rock bulk samples that were recently scaled from the cavern roof in the Dripstone Cave Entrance and were submitted for laboratory geotechnical testing. Photographs were also taken of the various assessment areas. In the Discovery Cave Exit, Golder drilled a series of probe holes in the shotcrete roof structure on either side of the inner airlock doors. Once drilled, a borescope camera was inserted into the