NOA Air-Quality Lessons Learned During Calaveras Dam Replacement Project

The Calaveras Dam Replacement Project (CDRP) pioneered technical approaches for addressing community exposure to naturally occurring asbestos (NOA) via the inhalation pathway. Over the course of the CDRP, approaches were developed for key issues, including determining the NOA particles of interest, defining the toxicity limits to apply to various types of NOA particles, establishing dust control, and creating appropriate feedback loops for using laboratory data. Specific issues of interest included whether to count only structures above a certain length and the inhalation unit risk value to use for amphiboles. The knowledge gained on the CDRP can and is being used to optimize NOA evaluation and control at other, similar projects.