The leaching of CCA components from treated wood under acidic conditions were investigated. Western hemlock treated with three types of CCA and two levels of target retention was subjected to leaching at four different levels of pH. After leaching tests, leached samples were subjected to laboratory decay and soft rot tests. The amount of CCA components leached was dependent on acidity of leaching solution, CCA formulation, and target retention. The leaching of CCA components at pH 4.0 or above was not significant even though a relatively low amounts of arsenic were leached. The resistance of leaching according to the type of CCA was in the sequence of CCA-Type C (oxide), CCA-Type C (salt) and CCA-Type B (oxide). The amount of leaching was increased with the increase in target retention. The reduction of biological effectiveness was not distinct for treated wood leached in acidified water of pH 4.0 or above. Based on the results of this study, it might be concluded that losses of CCA components at pH 4.0 or above were not great enough to cause public concern about environmental problems and reduction of biological efficacy in service.

Download document (438 kb)
free for the members of IRG. Available if purchased.

Purchase this document