Fixation effects on the release of copper, chromium and arsenic from CCA-C treated marine piles

Abstract

This study sought to determine the effect of fixation time and temperature on the release of copper, chromium and arsenic from treated marine piles immersed in seawater under "worst case" conditions. Sections of piles were CCA-C treated to a target retention of 2.5 lbs/ft3) (40 kg/m3) and then allowed to Condition at 36°F (2°C) for either 3, 7 or 20 days. As a control, one set of "wel1 fixed'' pile sections was conditioned at 80°F (27°C) for 20 days prior to leaching. Following the designated fixation period, the sections were leached in seawater maintained at 36 °F (2 °C). Fixation condition was found to greatly affect the leaching of CCA-C components, and especially chromium. After 120 days, average cumulative leaching from the pile sections fixed for3 days at 36°F (2°C) was 19, 169, and 23 times greater than that from piles fixed for 20 days at 80°F (27°C) for copper, chromium, and arsenic respectively. Fixation at 36°F (2°C) for longer periods substantially lessened arsenic leaching, but releases of copper and chromium remained high after fixation for 20 days. The results of this study verify that a high degree of leach-resistance that can be obtained in adequately conditioned CCA-C treated piling, but also demonstrated that much higher release rates may occur with current practices. The authors encourage the adoption of fixation standards for marine and freshwater piles in order to prevent unnecessary releases of CCA-C components into aquatic environments.

Citation

Lebow, Stan. 1999. Fixation effects on the release of copper, chromium and arsenic from CCA-C treated marine piles. Proceedings, Ninety-Fifth Annual Meeting of the American Wood-Preservers'' Association : May 1-19, 1999, Ft. Lauderdale, FL. Granbury, TX : American Wood Preservers'' Association, 1999. Vol. 95. pages 168-174.