In the recent years, many cases regarding sediment contamination in Taiwan were uncovered. Whether removal of the contaminated sediments or not is highly related to the high cost of the remediation action, with uncertainty of ecological and health effects. In order to clarify the issues related to the contaminated sediments, understand the current situation of sediment quality in Taiwan, and establish the sediment quality guidelines (SQGs), management strategy and treatment technology assessment, the Environmental Protection Administration of Taiwan (Taiwan EPA) commissioned this project to the Industrial Technology Research Institute (ITRI). This project compiled the information collected from the US, Canada, New Zealand, Australia and some EU’s member nations regarding management strategies for contaminated sediments, SQGs and methods used to establish these guidelines. After reduction of those SQGs, it is suggested that combination of logistic regression and equilibrium partitioning approaches used by the USEPA could be applied for SQGs establishment for Taiwan. This project also compiled the information from the US regarding to physical, chemical and biological treatment techniques for contaminated sediments. Three detailed case studies, clean-up of PCB contaminated sediment in Hudson River superfund site in New York, USA, clean-up of dioxin contaminated sediment in the Homebush Bay in Australia and clean-up of dioxin contaminated sediment in a channel in Japan, were also described.
In addition to the information from the foreign countries, this project also compiled sediment quality data collected from Taiwan EPA reports regarding sediment pollution investigation between 1997 and 2008. Those data showed that the contamination of river sediments was mainly contributed by heavy metals including chromium, copper, mercury, nickel and zinc. Concentrations of organic contaminants including PAHs, pesticides, PCBs and PCDD/Fs in the sediments were lower than Tier 1 and Tier 2 criteria proposed by the USEPA. Grab sample analyses from the Er-jen River conducted in this project showed that the highest concentrations of lead (664 mg/kg), cadmium (5.39 mg/kg), chromium (1130 mg/kg), copper (1570 mg/kg), zinc (1990 mg/kg) and nickel (318 mg/kg) were found in the sediments from the Station SY-2 (about 200 m upstream San-ye River before it enters Er-jen River). PCB concentration was found the highest at the Station 9 (3.16 mg/kg) and PCDD/Fs was found the highest at the Station 11 (464.7 ng I-TEQ/kg d.w.), which is three times higher than the Interim Sediment Removal Criteria in Japan. In this project, a sediment management strategy was also proposed to streamline a decision-making process among institutes to ensure the consistency on the consideration of risks and the use of approaches to manage the risks. The framework includes four actions needed to be taken: evaluation of sediment quality, assessment of pollution extent and ecological risks, treatment and disposal actions, and legislative actions for protecting human health.