How does Pitkin County's Composting Program Work?

The Composting Process

Leaves, grass, shredded untreated wood, food waste, and biosolids are mixed to a specific ratio and assembled into windrows that are 14 feet tall and 150 feet long. Biological activity quickly begins and the windrows heat up to about 140 degrees fahrenheit.  The temperature of the windrow is monitored; once the material has been at at least 131 degrees Fahrenheit for 15 days, the initial phase of composting is done.  The windrow is then moved to a second location and cured for at least 3 months.  This period of intense biological activity destroys weed seeds and reduces pathogens to safe levels.  After curing, the product is screened to ⅜”, tested, and then sold!

Our composting program follows rigorous operational, monitoring, and sampling protocols. We use standards set by the US Composting Council (USCC).  In 2013, the County’s Compost program became USCC Standard of Testing Assurance (STA) Certified.  To become USCC STA Certified the compost program underwent a rigorous review of our procedures and laboratory sampling; the program is recertified annually.  STA certification means that our compost is suitable for use in USDA certified organic farming.  For a copy of our most recent test results, send a request via email to:

There is significant cost involved in processing the organic material into compost. The operational costs of composting include permitting, reporting, laboratory sampling, equipment use, fuel, and time.  To make the compost operation viable it is necessary to charge a fee for incoming material. The compost program does generate positive revenue for the Landfill and these funds are used to support other non-revenue generating solid waste programs such as recycling, household hazardous waste collection, purchase and maintenance of equipment, and state-required post-closure care fund.

Contaminants such as plastic and metal enter the compost piles when people do not put trash or recyclable items into the correct bins at their home or business. This is a constant challenge for most composting programs across the country.  The final screening process catches most of this contamination, which is then sent to the trash.  Contamination increases the cost to process the compost because it increases the amount of labor and equipment use required.


How to Use Our Compost

Our compost can be used to add extra nutrients and organic matter into your soil. Since our compost contains more Nitrogen than regular dirt, it is not a replacement for topsoil or potting soil.  Plants should not be planted in pure compost; it needs to be mixed with your existing soil or one of our other soil products like topsoil.