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Biosolids: Technical Assistance

Technical information

​All domestic wastewater treatment facilities that apply biosolids to the land must operate under a biosolids management plan that has been reviewed and approved by DEQ. The plan is specific to each facility and serves as the administrative tool to guide the production, treatment, storage, transportation, and land application of biosolids for beneficial use.
  • Biosolids Management Plan Template:  PDF  |   DOC

​​​A site authorization letter is issued by DEQ regional water quality staff and is required prior to land application at a particular site. The letter specifies conditions for land application, including crop requirements, biosolids application rates, seasonal restrictions, setback distances to roads, wells, and water sources, and other pertinent site management information.
Soil information is needed to determine the suitability of a site for biosolids land application. Information from a soil survey should be attached to the site authorization request. 

All water quality permittees in Oregon that land apply biosolids, or sell or give away biosolids derived products for distribution and marketing during a calendar year are required to submit an annual report to DEQ. The annual report is due by February 19 of the following year and must include specific information on biosolids management and land application activities.

​Class A biosolids that are sold or distributed as a fertilizer must be registered with the Oregon Department of Agriculture. The application for this registration is available at the link below. This registration is not required for Class B biosolids because of the additional land application restrictions.

Commercial laboratories conduct a wide range of analytical methods for a number of different applications. It is vitally important the laboratory knows what you wish to be analyzed and how you want the results to be reported. For example if you do not specify your needs, the laboratory may report your inorganics as percent wet weight when you need the results in mg/kg dry weight; or they may report your nitrogen as “ammonium” (NH4+) when you need them to report it as “ammonium-N” (N). Laboratory results that state “ammonium” are not the same as “ammonium-N”. In addition total nitrogen is not the same as plant available nitrogen (PAN). These simple differences can have significant ramifications in your land application calculations and regulatory compliance. It is also important to ensure the laboratory is using the approved analytical methods for biosolids as specified in 40 CFR 503.8.

To help address some of these issues, the Pacific Northwest Extension Service produced a worksheet for calculating biosolids application rates. There are also spread sheets that can run these calculations for land application rates, but if you enter the wrong data (wet weight results or NH4+ instead of dry weight results or N), you will get the wrong answer and could be out of compliance. Be sure you know what the spread sheet or formula requires and produces or you may be relying on the wrong answer.

It may be worthwhile to have a professional agronomist calculate your application rates or at least review your work. Certified Crop Advisors are professional agronomists accredited by the American Society of Agronomy.

Resources and information links



For overall program information, please contact Pat Heins 503-229-5749.

For specific wastewater treatment facility and land application site information, please contact the appropriate regional specialist below.

Northwest Region

Tim Ruby 

Western Region  

Steve McMillan

Eastern Region  
Carl Makepeace