Approved for public release; distribution is unlimited. SSC San Diego San Diego, CA 92152--5001 TECHNICAL DOCUMENT 3052 December 1998 H. D. Johnson J. G. Grovhoug

this report was based on numerous assumptions, which, in turn, were supported by data that also varied in quality and availability. Consequently, some loading estimates are considered potentially more accurate than others. Navy hull leachate and civilian hull leachate were determined to be the two most significant loading sources in all four Navy harbors. Both were calculated from an average leach rate determined from several years of data collected in San Diego Bay. A simulated leaching apparatus (rotating drum), as well as actual in situ leach rate measurements on active naval vessel hulls, were used to make this estimate. The naval leach rate data were used for civilian hull leach rate calculations because civilian data were not available. Consequently, this assumption should be supported by actual in situ civilian leach rate data since civilian antifouling paints are not likely to be of the same formulation type as naval paints in service. The naval in situ leach rate data should also be improved with more in situ measurements on hulls with new coatings. Clearly, any assumptions may be tested and improved with additional data. Because of the magnitude of the hull leach rate contribution to total dissolved copper loading relative to other sources, and the calculation of this contribution based on a shared leach rate factor, it is felt that additional in situ data from both civilian and naval antifouling coatings is warranted. Additional data supporting other assumptions associated with lesser dissolved copper sources would be useful, but it is not anticipated that additional data would dramatically change copper loading from the minor sources identified. Figure ES-1. Estimated dissolved copper load for four U.S. Navy homeport harbor

EXECUTIVE SUMMARY

As part of the U.S. Navy’s antifouling (AF) program, a scientific team from SPAWAR Systems Center San Diego (SSC San Diego) conducted studies to evaluate low copper release coatings and non-metal, non-persistent biocide AF coatings, including Seanine, AF025, and AF028. The team used computer models previously developed and calibrated to simulate existing copper concentrations in San Diego Bay, as well as predicted concentrations of copper, Seanine, AF025, and AF028 resulting from designed implementation of non-metal and nonpersistent biocides. Model results provided reliable and scientific data that quantified cause-andeffect relationships between bay water contaminant concentrations and sources from ship hull paint leachate. Modeling approaches in this study were used to justify risk-management decision-making scientifically