Case Study to Illustrate Evaluation of Contaminant Pathways for Upland Dredged Material Disposal

The U.S. Navy in Pearl Harbor, Hawaii has developed an upland dredged material disposal facility on Waipio Peninsula for management of dredged material from the Pearl Harbor Naval Complex that has been determined to be unsuitable for ocean disposal. This paper presents the approach and results for the detailed evaluation of the environmental effects of dredged material management in the Waipio confined disposal facility (CDF) in accordance with the USACE/EPA "Technical Framework". The framework consists of physical and chemical characterizations and contaminant pathway testing and analysis for the selected confined disposal facility. Modeling is performed to support design/ management/operations decision-making and contaminant pathway analysis. The results of the study showed that disposal of Pearl Harbor dredged material in the Waipio CDF would be technically feasible and poses no significant impacts on human health. Potential contaminant releases by effluent, runoff, plant uptake, and animal uptake pathways represent small environmental impacts that should be acceptable with proper operation, management and controls. Copper, arsenic, and ammonia concentrations in the effluent and runoff exceed water quality standards for chronic toxicity, but, except for ammonia, are similar to the contaminant concentrations in background site water. Plant and animal uptake of cadmium, copper, and lead from the dredged material in a CDF are expected to be elevated over that of the present uptake from site soils, though still low. Controls can be implemented to limit contaminant uptake by plants and foraging animals.