Are the water treatment residuals toxic?
No. Water treatment residuals are generally considered non-toxic by the regulatory agencies that permit their disposal. State regulators responsible for approving residuals disposal practices throughout the United States typically permit water treatment residuals to be applied on various types of lands, including agricultural sites, forestland, and in lagoons. Prior to permitting the land disposal of water treatment residuals, state regulators typically require a sample of the residuals to be tested for toxicity to define the potential for the residuals to leach hazardous constituents into the groundwater. A standardized toxicity test, known as the Toxicity Characteristics Leaching Procedure (TCLP), is commonly required to be completed on the proposed residuals to confirm they are not toxic. Similar tests have been performed on Washington Aqueduct water treatment residuals in the past and will be performed again as part of this project. Past TCLP tests on Washington Aqueduct water trea
