Tetra Tech’s Superfund Technical Assessment and Response Team (START) was tasked by the U.S. Environmental Protection Agency (EPA) to conduct a geotechnical investigation adjacent to Gold King Level 7.  The project is part of the Bonita Peak Mining District, which consists of 48 historic mines or mining-related sources where ongoing releases of metal-laden water and sediments are occurring.

Team Members


Tetra Tech

Schnabel Engineering

Crux Subsurface

Crux’s Role

Crux was contracted to drill and sample one near-horizontal boring to a depth of 1,300 feet.  The goal was to collect continuous rock core sample to assist in subsurface analysis, including rock strength and fracture data.  Drilling took place through a vertical rock face with the expectation of weathered and fractured material.

The drill site was located at high elevation and was accessed by a steep, narrow, unimproved roadway.  Crux provided a drill capable of drilling and sampling to the proposed depths, while simultaneously capable of accessing the remote site by track.  A Morooka track carrier was ultimately utilized to transport the drill, and telehandler forklifts were used to assist with equipment and materials onsite.  Additional challenges included working during the heat of the summer season.

Crux successfully provided the client with continuous samples over the full depth of the hole.  Drilling stayed within the client’s allowable deviation tolerance, reaching within 8 feet of the target for a total deviation of less than 1 degrees over the 1,300 feet.

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