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Geotechnical Engineering

 

TRB Mid-Year Meeting Symposium On The Effects of Abandoned Underground Mines on Transportation Facilities

US-69 Reconstruction over Abandoned Lead and Zinc Mines

Robert Henthorne
Regional Geologist
Kansas Department of Transportation

Abstract

The Kansas Department of Transportation has proposed reconstruction of a 12 mile stretch of US-69 Highway in Cherokee County. During the Discovery Phase of the project, It was brought to the designer's attention that the southern of the proposed roadway will pass over a ¾ mile section that is severely undermined.

This area is a portion of the Tri-State Mining District. Mining for lead and zinc began in this area in 1870 and continued until 1970. These mines vary in depth from 200 to 400 feet with openings of 10 to 90 feet. One section of US-69 has an unsupported area of over 630 feet with no roof support!

Investigation of the mined area will initially require a 2-D Seismic Tomography Survey along the existing roadway. This survey should delineate any unknown mined areas and caved zones. An expanded 3-D survey will be conducted based on the information obtained.

This information will then be utilized in selecting the type of remediation.

Types of Remediation:

1. Grouting: If grouting is selected, we will install 20-foot diameter grout bags on 50-foot centers.

2. Real-Time Monitoring System: This system would be installed in the boreholes used in obtaining the seismic survey information. A complete warning system will be required with the dial up and emergency capabilities.

The cost of remediating deep underground mines is very expensive; however, the cost is slight when compared to a catastrophic collapse of a newly reconstructed highway.


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Updated: 04/07/2011

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