USCC STA Compost Text plus TX Dot Compost Test

STA Certified Compost plus TxDOT

Definition of Compost

Knowing what compost is (and what it’s not) is an important first step in ensuring that you use compost in the best way possible. Below is the official definition for what can be considered compost.

Compost - is the product manufactured through the controlled aerobic, biological decomposition of biodegradable materials. The product has undergone mesophilic and thermophilic temperatures, which significantly reduces the viability of pathogens and weed seeds (in accordance with EPA 40 CFR 503 standards) and stabilizes the carbon such that it is beneficial to plant growth. Compost is typically used as a soil amendment, but may also contribute plant nutrients. (AAPFCO definition, official 2018) Finished compost is typically screened to reduce its particle size, to improve soil incorporation.

Related and Allowable Products

1. Vermicompost/Worm castings for which all feedstocks have been composted prior to it utilized as worm bedding or feed, and the final product meets EPA 40 CFR 503 standards;
2. Digested solids (materials anaerobically digested) that have been composted after removal from the digester and which the final product meets EPA 40 CFR 503 standards; or
3. Any other substance that undergoes composting and is similar to Compost Product(s) in appearance, application and performance may apply to be considered by the STA Advisory Committee on a case by case basis.
   

These products may be registered as either standard STA products, or derivatives of STA products, depending on their manufacturing process.

1. Composted Mulch – Compost of a coarser particle size, containing a larger percentage of composted wood particles, and that meets the STA Program rules.The product is commonly used on the surface of the soil.
2. Erosion Control Compost – Compost of a coarser particle size, containing a larger percentage of composted wood particles, and that meets the STA Program rules, and meets user defined specifications related to particle size distribution.The product is commonly used as an erosion control blanket, berm, or sock media.
3. Soil Remediation / Stormwater Management Compost – Compost of a coarser particle size, containing a larger percentage of composted wood particles, and that meets the STA Program rules, and meets user defined specifications related to particle size distribution.The product is commonly used in soil incorporation in soil remediation and stormwater management applications.

To learn more about the STA Program click on the link. STA Program Requirements

Frequent Testing

Testing compost often is key to staying on top of understanding a product that is constantly evolving.
Manufacturers who produce:

Over 17,501 wet tons / year must test monthly
17,500 to 6,201 wet tons / year must test every two months
Under 6,200 wet tons / year must test every three months

* SPECIAL INSTRUCTIONS *

Sample Size Required - 2 x 1 Gallon sized ziplock bags

Please ship these samples overnight in an insulated container with ice packs.

DOT’s in each state have a customized format for their CTDS Data Sheet in the STA Certified Compost program. Here are some examples. Beside each test result you’ll see the boundaries of what that state DOT will accept for each value.

TxDOT Specifications TxDOT Specifications

For more information on each of the components tested and an explanation of their importance click on the link to read more at the USCC website. Compost - Characteristics and their Importance

STA Certified Compost participants must meet the EPA testing limits for heavy metals AND pathogens in every CTDS (Compost Technical Data Sheet) for every STA Certified Compost product.

Metals - maximum concentrations expressed on a dry weight basis ( Chromium and Molybdenum do not have EPA 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

Pathogens - pass either Fecal Coliform or Salmonella, at the manufacturers choice. Must pass both in California.

Fecal Coliform maximum concentrations

< 1000 MPN / gram of dry compost

Salmonella maximum concentrations

< 3 MPN / 4 grams of dry compost

Turnaround Time is 14 Business Days