Biosolids (Sewage Sludge) Disposal

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Biosolids (Sewage Sludge) and Disposal Regulations

Biosolids, a.k.a. sewage sludge, are solid, semisolid, or liquid residues generated during the treatment of domestic sewage in wastewater treatment works. Biosolids include but are not limited to scum or solids removed in primary, secondary, or advanced wastewater treatment processes, or materials derived from sewage sludge. Biosolids do not include ash generated during the firing of sewage sludge in a sewage sludge incinerator or the grit and screenings generated during preliminary treatment of domestic sewage in treatment works.

The terms “sludge,” “sewage sludge,” and “biosolids” are sometimes used interchangeably, but “biosolids” are primarily sewage sludge that has been stabilized to the disposal standards per 40 CFR 503 and 567 IAC 67 through sludge treatment processes so that they can be beneficially used in the environment.

Section 405 of the Clean Water Act sets the statutory framework for regulating sewage sludge. 40 CFR Part 503  regulates sewage sludge that is applied to a land, placed on a surface disposal site, or fired in a sewage sludge incinerator. It also sets pollutant limits, requirements for reducing pathogens, and vector attractions, as well as procedures for best management practices, sampling, monitoring, recordkeeping, long term plans, and annual biosolids reporting.

Iowa’s sewage sludge land application rules are in Chapter 67, 567 IAC 67 (455B). Compliance with both the federal and state rules are implemented by the National Pollutant Discharge Elimination System (NPDES) permit issued to a municipal wastewater treatment facility.

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Biosolids Annual Report

According to 40 CFR 503 and 567 IAC 67, sludge pollutant monitoring, disposal, and best management practices must be summarized in the biosolids annual report and submitted to the federal government and state agency each year on or before February 19, if a publicly-owned treatment works (POTW) is a major facility. A major facility is a Class I sludge management facility, a facility with design flow (average wet weather or AWW flow) of 1 million gallons per day (MGD) or greater, or a facility serving 10,000 people or more.

EPA requires all major POTWs to submit the biosolids annual reports electronically using the NPDES eReporting Tool (NeT) via EPA’s Central Data Exchange (CDX). NeT-Biosolids is accessed via EPA’s Central Data Exchange (CDX), which is located at https://cdx.epa.gov. For more information on EPA's NeT Biosoilds reporting, please see EPA's NeT Support page.

In addition to the EPA’s annual biosolids report, Iowa requires a submission of supplemental biosolids information. By February 19 or every year, both the federal biosolids report and Iowa supplemental biosolids forms are required to be submitted to the Iowa DNR biosolids email at ia-biosolids-annual-report@dnr.iowa.gov . 

Accessing Biosolids Annual Reports

  • EPA’s Biosolids Report Search - Annual biosolids reports from major POTWs in Iowa can be downloaded from EPA’s ECHO database.
  • Iowa Biosolids Annual Reports Search - Biosolids annual reports from the previous years are available in DNR’s Electronic Records Document Search System.  On the Document Search page, enter "Biosolids Annual Report" in the Document Type field to view a list of available reports.
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Iowa Biosolids Supplemental Forms

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Biosolids Resources

Iowa Biosolids Land Application Site Tracking Map (iBlast)

Iowa Biosolids Land Application Site Tracking (iBlast) is a GIS database that provides information for the site locations on which biosolids are applied by Iowa’s major POTWs. iBlast displays land application site information including location, field size and name, and total amount of biosolids applied per year.

Innovative Sewage Sludge Treatment Process

New and innovative sewage sludge pathogen reduction process that is not defined by Class A or Class B in 40 CFR 503 or Class I or Class II in 567 IAC Chapter 67 needs to be reviewed by the EPA Pathogen Equivalency Committee (PEC) to demonstrate the process robustness and effectiveness in reducing pathogen. Details on how to submit the PEC process review can be found from EPA’s Pathogen Equivalency Committee website.

EPA Links

Iowa DNR Links

Other Information

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