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The US Environmental Protection Agency (USEPA) was charged with determining whether minimum federal Clean Water Act requirements should be established for National Pollutant Discharge Elimination System permits on the discharge of residuals produced at water treatment plants. A key factor in USEPA's evaluation was the cost of residuals management at facilities where such treatment does not currently exist or where significant treatment changes would be required to meet such a technology‐based management requirement. AWWA initiated this project to provide independent cost information to aid in the USEPA cost‐benefit analysis. Cost estimates were developed for implementing residuals management at existing coagulation and lime‐softening plants of various sizes and solids production rates. In addition to capital costs, annual costs associated with residuals management were estimated and used to calculate the 20‐year current worth for residuals management. The work also provides guidance on focus areas where costs can be reduced.

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Key Takeaways As the practice of recycling water treatment residuals matures, additional contaminants beyond pathogens are becoming increasingly relevant to how facilities may recycle their residuals streams. Manganese recycling and residuals treatment will become more critical if the US Environmental Protection Agency (USEPA) ultimately promulgates a primary drinking water regulation targeting manganese. If a facility implements onsite dewatering and subsequently recycles their residuals streams, they may need to reduce the polyacrylamide levels to comply with USEPA regulations.