ABSTRACT

Regional Water Quality Control Board staffs are given the challenging task of developing total maximum daily loads (TMDL) for numerous watersheds. The complexity of mercury fate and transport, speciation, and biological consequences does not make this job easier. Applying cost estimates for mercury remediation projects complicates the situation even further. However, compiling information on past, current, and proposed projects reveals some insights into general categories of types of remediation costs. Numerous mercury technologies, reduction programs, and remediation techniques provide a clearer vision of the types of activities that public or private entities can do to reduce the risk of mercury contamination and the associated costs of these activities. Gold and mercury mine remediation, mercury reduction programs, sediment management, and ecosystem restoration projects are all possible solutions with certain advantages and disadvantages. Agencies have to decide which priorities are more important when assessing a potential remediation project, area, technique, and activity.

This report focuses on the costs that are associated with a suite of PS and NPS remedial strategies that are applicable to mercury sources for use as a resource in developing an economic analysis for mercury TMDLs in California. These costs are for past, current, and proposed remedial projects comprising of project development, environmental compliance, permit approval, cleanup, construction, and other transaction costs. The purpose of the report is to illustrate the general costs associated with various remedial practices that are applicable to mercury sources in California.

Mercury mitigation efforts could focus on two problems that mercury imposes on the natural environment and the general human population. These problems are the accumulation of mercury in the physical environment, given mercury's affinity for sediment, and the transformation of mercury in response to environmental conditions to an organic form, methyl mercury, which can potentially cause adverse health effects. These problems can be mitigated through mine remediation or sediment control or disposal, as well as through ecosystem restoration projects (although there is the possibility of adverse effects as well).

Although there are several thousand more mines in California, the lengthy and costly endeavor of mitigating mercury contamination prevents many projects from proceeding from the planning stages to the implementation phases. In addition, there are litigation concerns by many mine owners who fear being held liable for future contamination if a site is not fully mitigated. Furthermore, very few projects have been implemented to reduce mercury-laden sediment or to alter ecosystems specifically for mercury reduction. Although costs for remediation projects are site specific, there are some methods for predicting costs through identification and assessment techniques. This report provides an overview of the costs associated with mercury remediation projects in California, along with mitigation strategies in reducing mercury contamination.