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EPA's Region 6 Office

Serving: Arkansas, Louisiana, New Mexico, Oklahoma, Texas, and 66 Tribal Nations

Sewage Sludge/Biosolids Program

hand holding treated biosolids

"Sewage Sludge" refers to the solids separated during the treatment of municipal wastewater. The definition includes domestic septage. "Biosolids" refers to treated sewage sludge that meets the EPA pollutant and pathogen requirements for land application and surface disposal. See EPA’s biosolids program at the national level for more general information and documents.

Biosolids Regulations

The Federal biosolids rule is contained in 40 CFR Part 503. This rule is described in the EPA publication entitled: A Plain English Guide to the EPA Part 503 Biosolids Rule.

Elements of the Part 503 Rule

diagram showing the elements of Part 503 Rule which include pollutant limts, operational standards, management practices and more; see link to Guide in paragraph above

The risk assessment for the Federal Part 503 rule that governs the land application of biosolids took nearly ten years to complete and had extensive rigorous review and comment. The risk assessment did evaluate and establish limits for a number of pollutants. These limits may be found in chapter four of the EPA publication: A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule.

In the process of establishing these limits, EPA compared the relevant toxic's exposure data, which was obtained from a cross section of representative studies, to the appropriate oral reference dose (RfD) and human cancer potency (Q1*) values, (i.e., the allowable dose of each pollutant.) These exposures were evaluated via 14 pathways of exposure with the most limiting pathway being chosen as the limit. In spite of all the safety factors and uncertainty factors built into the process, environmental and human health risks were found to be very low.

Biosolids in Region 6

Info on Region 6 Compliance and Enforcement

For further questions, please contact:
Denise Hamilton
Sewage Sludge/Biosolids Coordinator
U.S. EPA Region 6
1445 Ross Avenue
Dallas, TX 75202-2733
Phone: 214-665-2775
Fax: 214-665-2191

Ted Palit
Biosolids Coordinator and Enforcement Officer
U.S. EPA Region 6
1445 Ross Avenue
Dallas, TX 75202-2733
Phone: 214-665-2775
Fax: 214-665-2191

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