ARCHIVE SITE - Last updated Jan. 19, 2017. Please visit www.NACWA.org for the latest NACWA information.
In 2000 NACWA approached the U.S. Environmental Protection Agency (EPA) with an idea for a project that would evaluate the effectiveness of pollution prevention programs at reducing the amount of mercury entering the nation's publicly owned treatment works (POTWs). With a grant from EPA, and the consulting assistance of Larry Walker and Associates, NACWA set out to determine whether pollution prevention or some form of source control could sufficiently reduce influent mercury levels to enable POTWs to comply with increasingly stringent limits for mercury. The project also sought to identify any beneficial impacts of wastewater source control programs on other pathways by which mercury enters the environment.
While the project did not involve implementation of actual pollution prevention programs, it did rely on a handful of POTWs from across the country to serve as case studies for the evaluation. Extensive effort was made to accurately estimate the mercury contributions from the major sources, including dental offices, domestic wastewater, and hospitals, which were then used to estimate the influent mercury load for each POTW case study. From there, the analysis estimated the load reductions achievable through the implementation of a control strategy, accounting for participation and effectiveness. The resulting effluent levels, based on the potential reductions, were compared to a list of mercury criteria to determine whether the source control programs could help POTWs comply with more stringent mercury limits. Finally, the costs to implement these programs and any additional treatment that might be necessary to ensure compliance were also evaluated.
At its conclusion, the project clearly demonstrated that mercury source control and pollution prevention programs have the potential to achieve measurable reductions in influent levels of mercury, and to have positive impacts with respect to reducing other environmental releases of mercury. The extent to which these source control programs alone will enable POTWs to meet increasingly stringent effluent limits, however, appears limited. During the course of the project a number of questions were raised that may ultimately have an impact on the effectiveness of pollution prevention programs for mercury. NACWA hopes that these questions will be answered through future projects like this one, and that together, these projects may provide us with a more complete understanding of how to curb releases of mercury to the environment.
NACWA would like to thank those agencies that served as case studies for the project and extend a special thanks to those individuals who served on the project oversight committee.
Links to the Executive Summary, Final Report, and Appendices