A study was undertaken to demonstrate the effects of 10-day exposure to sediments mixed with leachate from chromated copper arsenate Type-C (CCA-C) southern pine marine piles treated to a retention of 40 kg/m³ (2.5 pcf) and untreated southern pine piles on the benthic amphipod, Ampelisca abdita. The biological endpoint used to establish effects was organism survival. Leachate obtained during a 28-day period was dosed onto both low organic carbon and high organic carbon sediments, and the Ampelisca abdita were exposed to each type of sediment dosed with concentrations of leachate ranging from 10 to 100 percent. The components of the CCA-C treatment, copper, chromium and arsenic, were measured during the preparation of the leachate, in sediment mixtures and in the overlying and interstitial water in the exposed vessels. The 10-day exposure was maintained under static conditions with continuous lighting to ensure maximum exposure to sediment. Results showed that leaching of copper, chromium and arsenic from properly treated and fixed CCA-C treated wood does not occur at concentrations which would adversely affect the survival of these organisms exposed to the sediment. Treated pile leachate also had no significant effect on water quality. The study is significant, in part, because its design imitated the natural marine environment more closely than other studies published on this topic.

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