THE IMPACT OF RESIDUALS MANAGEMENT ON CALIFORNIA COST OF COMPLIANCE WITH A LOWER ARSENIC MCL

This paper is based on studies to assess the impact of lowering the arsenic MCL on California water utilities, serving populations from less than 100 people to over 1,000,000 people. These studies, prepared for the Association of California Water Agencies (ACWA), estimated that the California cost of compliance with an arsenic MCL of 5 μg/L would be 1.6 billion in total capital costs and 210 million per year in total annual costs. Water utilities in California that rely primarily on groundwater will bear most of these costs. Because most of the affected sources will be groundwater, many impacted utilities will need to consider implementing treatment for the first time. The utilities will first have to evaluate the water quality (including As(III) – As(V) speciation, pH, sulfate level, etc) of their affected sources and determine what arsenic removal technologies are appropriate for their system. A major concern at many wellhead sites will be the disposal of residuals produced by the arsenic removal processes.