STA Certifications

STA Certified Compost-02-01

Compost Classes I, II, and III are all types of compost products that earn a U.S. Composting Council Seal of Testing Assurance (STA). (Class IV composts undergo primary and secondary nutrient testing, but are not STA-certified, and should only be used in agricultural applications.)

What does STA certification mean?

STA Certification Requirements for Compost Manufacturers

For a compost product to earn an STA certification from the Composting Council, manufacturers must meet the following criteria. (This information is sourced directly from CompostingCouncil.org.)

 

1. The product must meet the U.S. Composting Council’s definition of compost.

According to the Composting Council, to be considered compost, a product must:

  • Be created via the controlled aerobic, biological decomposition of biodegradable materials.
  • Undergo mesophilic (68° to 113° F) and thermophilic (106° to 252° F) temperatures to reduce the viability of pathogens and weed seeds, and to stabilize carbon levels so as to be beneficial to plant growth. This thermophilic heat sanitization must meet the standards of the Processes to Further Reduce Pathogens (PFRP) as defined in the Code of Federal Regulations Title 40, Part 503, Appendix B, Section B.
  • Be used as a soil amendment or to contribute plant nutrients.
  • Bear little resemblance to the raw material from which it was created.
  • Be an organic matter that is able to improve the chemical, physical, and biological characteristics of soils or growing media.

Or a product must:

  • Be vermicompost/worm castings (worm manure) for which all feedstocks have been composted prior to being digested by the worms.
  • Meet PFRP standards.

 

2. The product must comply with all federal, state, and local regulations and permitting.

STA Certified Compost products are subject to regulation from officials in order to control for environmental impact (air emissions, leachate), impact to neighbors (odor, traffic), and operational issues (safety, end product applications).

In Colorado, the regulatory agency that oversees composting is the Colorado Department of Public Health and Environment. You can learn more about federal, state, and local regulations on the U.S. Composting Council’s Regulations page.

If any issues arise with regulations or permitting, manufacturers are advised to immediately inform the U.S. Composting Council.

 

3. Manufacturers must use Composting Council-approved labs for testing.

These labs use TMECC (Test Method for the Examination of Composting and Compost) methods and are tested against one another three times a year through the STA’s CAP program, ensuring that each lab is held to a high standard.

 

4. Manufacturers must periodically submit compost products for quality testing.

Product testing guidelines are as follows:

  1. Compost samples must only be sent to STA Compost Certified labs.
  2. Samples must be collected from ready-to-sell finished compost using the TMECC compost sampling methods. You can learn more about collecting samples in the “Collecting Field Samples” resource provided by the U.S. Composting Council.
  3. Compost samples should be sent in using the Chain of Custody form.
  4. Frequency of testing depends on the annual finished wet tonnage of compost that you manufacture:
    • 1 – 6,200 tons: 1 sample per 3 months
    • 6,201 – 17,500 tons: 1 sample per 2 months
    • More than 17,500 tons: 1 sample per 1 month

Both the compost manufacturer and the U.S. Composting Council receive test results directly from the labs.

 

5. Manufacturers must provide customers with STA Compost Technical Data Sheets (CTDS).

CTDS sheets include information about the composition of a compost product, its test results, practical applications, and instructions for use.

 

6. The product must meet the EPA testing limits for heavy metals and pathogens.

The Environmental Protection Agency (EPA) sets maximum concentrations for heavy metals like arsenic, lead, or mercury in every compost product. Products must also comply with maximum concentration limits for pathogens including salmonella and fecal coliform. These concentrations are expressed on a dry weight basis.

Heavy metal concentration limits:

  • Arsenic (As): 41 mg/Kg
  • Cadmium (Cd): 39 mg/Kg
  • Copper (Cu): 1500 mg/Kg
  • Lead (Pb): 300 mg/Kg
  • Mercury (Hg): 17 mg/Kg
  • Nickel (Ni): 420 mg/Kg
  • Selenium (Se): 100 mg/Kg
  • Zinc (Zn): 2800 mg/Kg

Pathogen concentration limits:

  • Fecal coliform: <1,000 MPN/gram
  • Salmonella: <3 MPN/gram

This information is included in the CTDS for each STA Certified Compost product.

 

7) Compost manufacturers must sign the STA Certified Compost rules contract.

This contract ensures compliance with all of the regulations outlined on this page.

 

8) Manufacturers must pay a yearly fee to the U.S. Composting Council.

These fees help to sustain the STA Certified Compost program.

 

9) Manufacturers must renew their STA Certification contract and payments yearly.

To learn more about STA Certification standards, visit CompostingCouncil.org or feel free to contact us at A1 Organics.

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