EPA conducted the National Sewage Sludge Survey (NSSS) in 1988 and 1989 to obtain a current and reliable database on biosolids quality and management that could be used to help develop the final Part 503 rule. The NSSS included an analysis of 412 analytes in samples of biosolids from 180 publicly owned treatment works (POTWs) as well as analysis of questionnaire information on use or disposal practices from 475 POTWs with secondary or more advanced wastewater treatment. The resulting national estimates of pollutant concentrations in biosolids, quantities of biosolids generated, and biosolids treatment, practices, and related costs permitted a more accurate assessment of the level of risk posed by biosolids.

• Sampling Procedures and Protocols for the National Sewage Sludge Survey

• Statistical Support Documentation for the 40 CFR Part 503 - Volume I (PDF)(286 pp, 11 MB, November 1992)
• Statistical Support Documentation for the 40 CFR Part 503 - Volume II (PDF)(359 pp, 20 MB, November 1992)