AWWA ACE58259

In 2001, the US Environmental Protection Agency (USEPA) published a revised maximum contaminant level (MCL) requiring arsenic concentrations to be maintained below 10 ug/L in drinking water. The two groundwater wells operated by the Walker River Paiute Tribe (Tribe) have arsenic levels between 70 and 110 ug/L. In addition to arsenic, significant levels of silica (55 mg/L) and an "elevated" pH (8.4) are present that must be addressed when selecting the appropriate treatment technology. The Tribe identified critical issues associated with meeting the revised MCL and implemented the Arsenic Removal Technology Pilot Plant Study. For this study the Tribe selected multiple technologies for evaluation of arsenic removal through bench- and pilot-scale studies. Through a rigorous testing program, technologies are being evaluated for their ability to: consistently reduce the arsenic concentration below 10 ug/L; expand easily through modular construction; incorporate continuous advancements introduced into the market for arsenic removal; avoid the production of hazardous wastes; and, eliminate excess wasted water. Finally, the selection of a technology at the end of the pilot study for full-scale application must consider the limited Tribal resources, operation and maintenance demands on the staff, and the natural aesthetics of the Tribal lands. Includes table, figures.