The majority of marijuana waste in Washington ends up in the landfill. New legislation aims to redirect it

Washington cannabis growers could soon generate new revenue and help reduce greenhouse gases by selling plant waste with a bill that passed the House on Thursday.

Stalks, stems, leaves and roots of marijuana plants that aren’t considered dangerous waste under state law often end up in landfills, producing methane gas as they decompose.

Legislation now awaiting a signatures from Gov. Jay Inslee hopes to redirect cannabis waste toward new product creation and composting. The bill would allow marijuana cultivators and processors to sell plant byproducts containing less than 0.3% THC concentration to the public.

Repurposed cannabis wouldn’t be used for consumption. Buyers could use plant waste for composting and various hemp-related products, including hempcrete for construction or insulation, and hemp fiber, which comes from the plant’s stem, for textiles, ropes and animal bedding .

Blue Roots Cannabis, a producer and processor in Spokane County, disposes of around 2,200 pounds of cannabis waste a month, filling a large 40-yard container with a mixture of ground marijuana byproducts and other organic material, operations manager Seth Shamberg said.

“Usually, we mix it with dirt, cocoa, wood chips, all kinds of (organic material),” he said. “There isn’t anything recoverable once it’s been ground and mixed like that.”

This mixture is picked up by Spokane’s solid waste services – which comes with a $600 price tag.

Going into their eighth year of operation, Blue Roots Cannabis operates two large steel warehouses, with a third under construction to expand its growing facilities. One warehouse is dedicated solely to plant cultivation, while the other houses offices at the front and has growing, manufacturing and trimming services at the back.

“This doesn’t do our society any good to be continuing to fill landfills, especially when it’s being mixed with nonorganic garbage piling up or being put into plastic contractor bags before it’s dumped,” Shamberg said.

Cannabis waste is required by law to be ground and mixed with at least 50% of other materials like kitty litter, sawdust or wood chips to be properly disposed of, which further contributes to the amount of organic waste heading to the landfill and the amount of methane gas emitted, said Heather Trim, executive director at Zero Waste Washington.

With almost 1,000 marijuana growers in Washington, around 500-1,000 pounds of green waste needs to be disposed of every week during the growing season, she said on Feb. 14.

This year’s bill also aligns with a 2022 law aiming to reduce methane emissions by diverting 75% of organic materials from the landfill by 2030, Trim said.

To sell plant byproducts, they cannot be considered dangerous waste by state law, meaning any discarded or unwanted substances that may contain pesticides, have toxic properties or are flammable cannot be sold. Sales must also be open to the public without discrimination, and a notification must be sent to the Liquor and Cannabis Board and the state Department of Agriculture detailing the quantity and price of the waste, as well as the purchaser’s name or organization.

If the bill is signed into law, Shamberg said they would be interested in exploring the possibility of selling their marijuana waste or redirecting it for composting purposes so it doesn’t continue filling up the landfill.

“It would be nice to see the (Legislature) start to give more detail to some of the cannabis policies that we have in order to give us the opportunity to better rectify the issues that we face,” Shamberg said.

On the house floor, Rep. Shelley Kloba, D-Kirkland, said this bill “creates a circular economy,” by benefiting growers who would generate new revenue, supporting buyers who plan to repurpose the byproducts and aiding the environment by reducing landfill waste and methane emissions.

Rep. Leonard Christian, R-Spokane Valley, voted no because of his childhood experience with marijuana.

His mother would often leave Christian and his siblings home while she went cross-country trucking, giving one of them money for food. The sibling would use that money for marijuana, and Christian’s only opportunity to eat was at school, he said.

“I’ve seen it wreck a lot of lives over the years,” Christian told The Spokesman-Review. “It’s just not for me, and I’m not going to vote for a marijuana bill.”

Since amendments were adopted in the House, the bill heads to the Senate for final approval before reaching the governor’s desk.