Approaches to contamination at mercury mill sites; examples from California and Idaho

Abandoned or inactive mercury mines are found throughout the western United States. Mercury contamination from these mines has migrated into a variety of different media in varying forms. Cleanups and mitigation projects have been undertaken by various agencies and private entities at a number of these mines, although many remain to be addressed. Although each cleanup has similar objectives, such as source control, the methods employed in each area of the site may differ. By having an understanding of mercury and its effects and assessing different methods used at mercury-mine cleanups, future actions can be more effective at addressing the variety of issues posed by mercury contamination at former extraction and processing sites. This paper provides background on mercury, its occurrences, its health effects, and the mercury mining process. Four cleanup sites that utilized different methods for addressing mercury contamination illustrate how different sources at abandoned mercury mill sites may be addressed to mitigate impacts.