New Colorado marijuana waste guidelines encourage composting


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Colorado marijuana regulators have passed new waste management rules to help reduce the industry’s growing carbon footprint.

According to the Department of Public Health and Environment, 3,650 tons (7.3 million pounds) of marijuana plant waste was produced by the state potting industry in 2019, and that number would be reduced to 7,300 tons by requiring that unused plant matter and products not be used mixed with waste like sawdust, mature compost, bleach, coffee grounds, sand, glass or shredded paper – as long as the ratio of marijuana to waste is 50/50.

Although the state marijuana enforcement department did not lift or change the 50/50 requirement as discussed in previous meetings, the MED opened several avenues around it and new exemptions for biomass in the last round of the department’s extensive rule updates added recycling and composting methods. Kaitlin Urso, environmental impact researcher and small business consultant at CDPHE for marijuana, said the new waste disposal regulations will come into effect in early 2021.

“This is something that cultivators asked what they wanted,” she says. “Growers want to make these sustainable choices and send plants to compost.”

Under the new MED rules, marijuana growers can send their leftover stems, leaves, and unusable plant matter to anaerobic digestion facility, an accelerated reassembly process that captures the emitted gases.

“It captures the gases in order to use them as goods,” explains Urso. “If you only compost, you regain the nutritional value from the plant material, but still release the gases into the atmosphere.”

Further options are biocharring or the burning of plant material to form a nutrient-dense charcoal that can be used as a cultivation additive, as well as the gasification of biomass, a thermochemical conversion of plant material into usable gases. The new exemptions will also make it cheaper to remove waste more sustainably, adds Urso, as most commercial composting companies charge a pound per fee for collection. Under the previous 50/50 rules, this would have doubled the cost.

Additions to the industry’s retail code also allow for greater consumer recycling. Colorado already had marijuana packaging recycling rules in place, but they didn’t address disinfection and structural integrity to ensure child safety. These details have since been ironed out and the pharmacies are now allowed to offer package containers in their lobbies. Previously, the containers had to be placed in the retail areas of the pot shop, spaces that are generally not very large and are sought after by vendors. The new rules also allow customers to recycle marijuana packaging bought in various stores.

The MED will be reaching out to marijuana business owners shortly to inform stakeholders about the new waste disposal options.

The new rules represent Urso hoping the MED will address future environmental impacts over the next year. She is currently working on a government study that measured the carbon effects of terpenes – plant compounds that are responsible for the smells and flavors of marijuana – in urban marijuana growing areas. The CDPHE is expected to publish this before the end of the year.

The state’s new waste disposal and packaging has been implemented as part of a variety of MED updates to the state’s marijuana retail code. Another notable addition is a new marijuana business accelerator program for low-income entrepreneurs.

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Thomas Mitchell has been writing about everything cannabis-related for Westword since 2014, covering sports, real estate, and general news en route to publications like the Republic of Arizona, Inman, and Fox Sports. He is currently the cannabis editor for

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