Holden Mine Remediation Project

Project Name: Holden Mine Remediation Project

Project Location: Chelan, WA

Owner: Rio Tinto

GC: Magnus Pacific

Engineer: MWH

Project Start and End Date: 2012 – 2015


Mine clean-up is part of the ongoing Legacy Program at Holden Mine. The site was remotely located in the Cascade Mountain Range; all personnel and materials had to come up Lake Chelan by boat.


Griffin was responsible for management of multiple phases of this project from field data gathering to system installations and removals. 200+ deep wells were installed with air rotary over a 3-year period.

· 2012-wellpoint pump test in Railroad Creek Realignment area.

· 2013-installation of 66 deepwells, from 30 to 50 ft. deep, to dry area for 900+ LF of engineered creek bed realignment construction to depths of 12 to 15 ft. below original ground surface.

· 2014-Installation of 20 wells for collection pipe installation under diverted creek bed with multiple pump tests along collection pipe alignment.

· 2015-installation of 133 deepwells, 40 ft. in depth, along 1.25 miles of collection pipe trench extending to 20 ft. in depth.


Careful planning was required to minimize the amount of material that had to be brought up lake but to prepare for most eventualities.

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