Wednesday, March 26, 2009:
U.S. Environmental Protection Agency (EPA) On-Scene Coordinator (OSC) Dan Heister was notified via email by Denise Baker-Kircher, EPA, Remedial Project Manager (RPM) for the site that the adit drainage diversion system at the Formosa Mine near Riddle, Oregon had developed a blockage causing the upper portion of the drainage to leak profusely. The leak was noted the previous week by a remedial contractor during a site walk at the Formosa Mine. The blockage was located in the drain pipe that connected two large concrete weired vaults and was causing a continuous release from the top of the upper tank, such that the released water was flowing overland toward and into the headwaters of Middle Creek.
This was the first site walk of the year as the snow had just melted and fallen trees had been cleared allowing access to this remote site.
After the 2008 emergency response the site had been inspected four times from July 2008 through November 2008 and continued to be in working order. The worst winter in 40 years brougt extremely heavy snow and restricted access to the area after late November. There is no way to know when the blocakage triggered the release. Most likely it ocurred at the heighth of the snow melt earlier in March, when high flows likely dislodged a significant amount of "yellow boy" (solid percipitate which settles and cakes in the pipes) and blocked the system.
OSC Heister informed Chris Field of EPA of the adit diversion system release into the Middle Creek headwaters. A decision to mobilize immediately to repair the leak to the adit diversion system was made by Field. Heister mobilized ERRS to Canyonville, OR from Seattle, WA on 03/26/2009 to be ready to proceed to the site on the morning on 03/27/2009.
