The 1000 lineal foot Echo Tunnel was repaired by installing a HDPE liner with inlet and outlet structures. Mark Suden Mining Construction was subcontracted for all underground activities. The work involved re-shoring the failed and distressed timber sets, sinking a 35' reinforced vertical shaft through the failed section of tunnel to facilitate access, and removing the sediment and debris distributed throughout the reach of the tunnel resulting from the collapse. A concrete invert, and pipe installations guides were installed to ensure consistent grade. The 36" SDR21 liner was pulled through and a light weight cellular grout was installed in the annular void, to prevent further settling or sink-holing on the ground's surface. The project was located at 7500' elevation, and had to be installed prior to the winter snow pack. Work was performed at the end of September through mid- December.