April 14, 2006

CFRTAC advisors have been busy poring through newly-released draft planning documents for the start of the Milltown Reservoir cleanup. Now available are CFRTAC summaries of the site access and control plan and contingency plans for protecting groundwater and surface water.

The site access control plan (PDF) describes how Envirocon will prevent entry of unauthorized people to the Milltown construction site, including closure of portions of the Blackfoot River and Clark Fork River near the dam. Closure of the reservoir site and the rivers is necessary to protect the health and safety of the general public and to secure site facilities from vandalism and theft. Closure of most of the site, including the rivers, will begin in late 2006 or early 2007.

The groundwater contingency plan (PDF) spells out the actions that Envirocon would either take or consider if arsenic rises above drinking water standards in private or public supply wells, or if arsenic exceeds trigger values in early warning monitoring wells. Please note that this is a draft document that could change before the final version is accepted. It is expected that lowering water levels in the reservoir will decrease the extent of the arsenic plume, but nonetheless, the contingency plan spells out the actions that would be taken, and the possible changes to construction practices that could be used, if contamination were to spread.

The surface water contingency plan (PDF) details the steps that Envirocon would either take or consider if suspended sediment, dissolved arsenic, or dissolved metals were to increase above the warning limits established for temporary construction-related water quality standards in the Clark Fork River. For the most part, warning limits are 80 percent of the standard, which is based on aquatic life criteria for dissolved metals, and the drinking water standard for dissolved arsenic.

Instructions on how to access the full documents are available here. The documents were discussed at the next Milltown Design Review Team meeting on April 18. Check out CFRTAC’s comments (PDF) to the EPA on the plans.

Go to top