A Brief Summary of the Federal Standards for Land Application of Sewage Sludge

by Ellen Z. Harrison


Cornell Waste Management Institute
Department of Crop & Soil Sciences, Cornell University
Ithaca, NY 14853 ~ 607/255-1187 ~ cwmi@cornell.edu



The US Environmental Protection Agency adopted regulations in 1993 (40 CFR Part 503, known as Part 503) that establish minimum standards which must be met if sewage sludges are to be land applied.  The regulations include concentration limits for 9 metals and for pathogens, and requirements for vector (flies and rodents) attraction reduction.

The federal regulations establish standards for 9 contaminants (Table 1).  The standards include “exceptional quality” (EQ) sludges which meet certain concentration limits (no more than X parts per million of any of the 9 regulated contaminants) as well as pathogen limits and vector reduction requirements.  In regard to metal concentrations, sludges and sludge products which fail to meet one or more of those “EQ” pollutant concentrations but which fall below a higher ceiling concentration may be applied, but the agricultural applicator is directed to keep track of the total amount of each metal applied and cease application when a regulatory cumulative pollutant loading limit is reached.

Pathogen treatment is addressed in the rules.  The regulations establish Class A sludges which have been treated to “essentially eliminate pathogens” (disease causing organisms) and Class B in which pathogens have been reduced, but are still present in significant numbers.  Under the 503 rules, sludges and sludge products meeting Class A and “EQ” standards can be applied without restriction in amount or duration, for use in home gardens, parks, crop production, etc.  There are no requirements for labeling or for recording or notification of where and how much is used.  Under the federal rules pertaining to the application of Class B sludges or sludges not meeting “EQ” limits but falling below the ceiling limits, certain restrictions concerning cumulative loading of contaminants and site access restrictions apply, but no individual site permits are required for land application.  Sludge products which fail to meet one or more of the “EQ” pollutant concentrations, but which meet Class A pathogen and vector reduction requirements and fall below the ceiling concentrations for contaminants, may also be distributed to homes or in bags so long as information on the acceptable annual pollutant loading rate (APLR) is provided to the user.

A risk assessment was performed to establish the US EPA limits and to determine what contaminants to address (Table 2).  Since the regulations were adopted in 1993, the list of regulated contaminants has been decreased with the elimination of chromium.  A list of 31 additional contaminants were being considered for regulation in “Round 2,” but it is likely that only co-planar PCBs and dioxins and furans to the list of 9 regulated contaminants in the next several years.

State regulations must be at least as strict as the federal standards, but states have the option of adopting regulations that are more stringent than the federal standards.  Land application must follow the more stringent state rules where they exist.

        Table 1. Pollutant Limits In US EPA Part 503 Regulations


        Table 2. Exposure Pathways Used In the Part 503 Risk Assessment