All facilities that generate biosolids must operate under both federal and state law. The rules specific to biosolids can be found in Oregon Administrative Rules (OAR) Chapter 340, Division 50 and section 40 of the Code of Federal Regulations (CFR) Part 503.
- OAR Chapter 340, Division 50 - Land Application of Domestic Wastewater Treatment Facility Biosolids, Biosolids Derived Products, And Domestic Septage. These are regulations that identify state-specific requirements and best management practices to protect the environment and public health in Oregon. These regulations prescribe the methods, procedures, and restrictions for the management and use of domestic wastewater treatment facility solids, products derived from biosolids and domestic septage. These rules specify Oregon’s program for biosolids and domestic septage management which satisfies or exceeds minimum federal regulations pertaining to land application.
- 40 CFR Part 503 - Standards for the Use or Disposal of Sewage Sludge. These are federal regulations that set national standards for pathogens, vector attraction reduction, and certain contaminants in biosolids. They also define management practices and operational standards for the safe handling and use of biosolids. The provisions of these regulations are applicable regardless of whether a state or federal permit is required.
In Oregon, biosolids are regulated under DEQ's water quality program, specifically through a water quality permit (National Pollutant Discharge Elimination System or Water Pollution Control Facility permit), a biosolids management plan, and site authorization letters. The permit, management plan, and site authorization letters are specific to a facility and include conditions that are relevant to both state and federal regulations. The conditions in the management plan and site authorization letters are considered an integral part of the permit and thus are enforceable. Oregon’s biosolids regulations are more restrictive than federal regulations.
Each permit is open for public comment when the facility’s permit is renewed. The facility’s biosolids management plan is also open for public comment when the facility’s permit is renewed and anytime there are significant changes to the management plan. The public comment period is at least 30 or 35 days depending on the type of permit.
DEQ requires permittees to take the following measures to apply biosolids to land:
Processing of biosolids
Treatment facilities may use several different processes (such as aerobic digestion, anaerobic digestion, alkaline stabilization, pasteurization, etc.) in transforming wastewater solids into biosolids. Regardless of the method used the final product must meet strict quality standards established in federal and state rule. Treatment facilities are required to control pathogens (disease-causing organisms, such as certain bacteria, viruses and parasites); reduce the solids’ attractiveness to vectors (such as rodents or insects); and ensure their material does not have pollutants above the screening levels. Once the material meets these criteria it can be identified as biosolids and can be beneficially applied to land. State and federal regulations identify two classes of biosolids, either Class A or B.
Class A biosolids must meet strict pathogen, vector attraction reduction, and low pollutant content requirements. Some Class A biosolids may be classified as Exceptional Quality (EQ). Class A biosolids can be safely used by the general public like any other commercial fertilizer/soil conditioner product. Class A biosolids are generally produced by composting or heat-drying.
Class B biosolids must meet somewhat less stringent requirements, but have been proven to be as protective of public health and the environment as Class A biosolids when proper site management and access restrictions are observed. The majority of biosolids produced and applied in Oregon are Class B.
To ensure the biosolids are processed correctly, treatment facilities must routinely test for pathogens, nutrients, and pollutants. All biosolids applied to land in Oregon are routinely sampled and tested for plant nutrients (nitrogen, phosphorus, and potassium) and regulated pollutants (arsenic, cadmium, chromium, copper, lead, mercury, molybdenum, nickel, selenium, and zinc) to demonstrate ongoing compliance. This regular laboratory testing is important because it ensures the biosolids are processed correctly and is used to identify the proper amount that can be applied. Treatment facilities must collect representative samples on an on-going basis and the biosolids must be tested by qualified laboratories using approved testing methods. At a minimum, all treatment facilities must test annually and larger treatment facilities must test more frequently. The results of this routine testing are submitted to DEQ for review on an annual basis.
The Oregon State University extension service produces fertilization guides that identify the amount of nutrients needed to grow a healthy crop. DEQ uses this research to identify the agronomic rate that dictates the appropriate application rates for biosolids on each field for different crops. Developing the agronomic rate for land application is one of the key elements for ensuring that land application provides the correct amount of nutrients to the soil. Too much nitrogen in the soil can leach and degrade groundwater. If a permittee applies Class B biosolids on the same area for two out of three years at the agronomic rate for nitrogen, DEQ requires the permittee to test soil conditions to ensure they are not overloading the land with nutrients. If they are applying at lower than the agronomic rate, soil sampling may not be required by DEQ depending on the field location and site conditions. If carryover nitrogen levels in the soil are observed above the level OSU established for a crop, applications must be reduced or stopped until the soil nitrogen levels are reduced by plant growth.
Class A biosolids are commonly characterized similar to other commercial fertilizers and soil sampling is not required on fields where class A biosolids are applied.
Other protective measures
Before Class B biosolids can be applied on a field, DEQ must conduct a site evaluation. This ensures the field meets specific criteria as outlined in state and federal rule. This evaluation reviews the site location, slope, vegetation, and distance to surface and groundwater. If the field passes the site evaluation, a site authorization letter is issued that also establishes site-specific setbacks or buffer zones between where biosolids can be placed and surrounding features such as surface water, wells, residences, public roadways and property lines. To further ensure that the activity is protective of public health and the environment, DEQ requires other site management practices at Class B biosolids application sites such as limiting public access for a minimum of 12 months following application and not allowing the grazing of livestock or the harvesting of crops for 30 days following application of biosolids.
Because class A biosolids are treated to a higher standard, these extra protective measures are not required, but safe fertilizer management activities are advised.
Record Keeping and Reporting
All treatment facilities must keep detailed records of their operations, the quality of biosolids they produce and their management activities. These requirements are specified in the facility’s water quality permit and biosolids management plan. Each treatment facility that produces biosolids must submit an annual report to DEQ for review. The larger treatment facilities must also submit an annual report to the U.S. Environmental Protection Agency .