The City of Phoenix’s new composting facility is up and running and successfully producing high-quality compost. The facility was designed by Green Mountain Technologies and a team of architects and engineers. The ribbon was cut on the facility back in April of this year. We wrote an article about the event: http://compostingtechnology.com/city-of-phoenix-cuts-ribbon-on-new-composting-facility/.

The facility’s first day of composting was on June 19th. Green Mountain Technologies’ President Michael Bryan-Brown has since visited Phoenix and is happy to report that despite outdoor temperatures topping out at more than 120℉, their composting system is performing well. The system is able to maintain moisture levels and keep the compost process at a stable, cooler temperature despite the heat.

Phoenix’s geography and climate offers challenges for municipal-scale composting. The climate is exceedingly hot and dry and expected to get even hotter and drier in the coming years as a result of climate change. The City of Phoenix has ambitious goals to become a truly sustainable desert city. According to Phoenix Mayor Greg Stanton, as quoted in the City of Phoenix’s press release (https://www.phoenix.gov/news/publicworks/1702),opening this facility will help us reach our ambitious waste reduction goals while building our circular economy”. Phoenix needs composting infrastructure that is resilient to extreme heat and monsoon storms, and provides excellent odor control.

Green Mountain Technologies built a custom Turned Aerated Pile (TAP) system that uses an aerated composting pad to keep the composting piles cool and aerobic. The Phoenix TAP is a positive/negative reversing aeration system. Below-grade piping is used to push or pull air into or out of the compost piles.

In negative aeration mode, the TAP system pulls warm, moist air down through the compost piles and into the below-grade aeration piping. From there, the air is directed into a biofilter pad which removes over 90% of the odors. In positive aeration mode, the air is drawn up through the compost piles. A biocover is placed on top of the compost piles to remove the odor from the air pushed into the piles by the blower. In this way, the odors emitted from the compost process are absorbed in both positive and negative aeration modes. The biofilter and biocover employ screened large wood chips and/or finished compost to filter odors. The biofilter media essentially acts like the ground cover on a forest floor. Microbes on the dry material eat the organic acids and other compounds that cause odors. The facility has received no odor complaints thus far.  

A drainage system collects condensate and leachate for treatment and reuse. Wireless temperature probes send temperature readings from each compost pile to the control building. The TAP program automatically responds to the temperature data input by adjusting the direction and volume of airflow in the pile.

The monsoon season has started in Phoenix and Green Mountain Technologies’ stormwater design will soon be tested by flash floods. The system is designed to capture any runoff rainwater from the compost site, store it in the stormwater pond, and divert the water back into the system. Once the stormwater collection system is proven to work in monsoon storms, the facility will begin to accept food waste from Phoenix’s residents.

The compost facility is currently capable of processing up to 110,000 tons of green and food waste per year and will divert more than 10% of Phoenix’s total waste from the landfill. Green Mountain Technologies’ design earned the Envision® Silver Rating from the Institute for Sustainable Infrastructure. The system will enable the city to expand its operations in the future to process up to 220,000 tons per year. Composting is an important step for Phoenix to become a truly sustainable desert city.

Linked is the City of Phoenix’s compost facility brochure which contains information about the Resource Innovation Campus on 27th Avenue in Phoenix and displays a map of the TAP composting system located there: https://www.phoenix.gov/publicworkssite/Documents/Compost%20Facility%20brochure%20041217.pdf