HB2483 – Regulating and encouraging biochar production from agricultural and forestry biomass.
Prime Sponsor – Representative Chapman (D; 24th District; Olympic Peninsula) (Co-Sponsors Shavers & Kloba – Ds)
Current status – Referred to the House Committee on Environment & Energy.
Next step would be – Scheduling a hearing.
Legislative tracking page for the bill.

Summary –
The bill would add producing biochar using mobile units with reduced emissions relative to open burning, and consuming less than 150 green tons a month of clean cellulosic biomass, to the list of alternative forestry disposal practices DNR is currently supposed to encourage. Those materials are defined as residuals from agricultural and forest-derived biomass including green wood, forest thinnings, wood pellets and various kinds of waste; urban wood including tree trimmings, stumps, and related forest-derived biomass; corn stover and other crops used specifically for the production of biofuels; bagasse and other crop residues; and wood collected from fire clearance, trees and clean wood found in disaster debris, and clean biomass from land clearing. (Materials couldn’t contain contaminants at concentrations not normally associated with virgin biomass.)

You’d need a burning permit from DNR to produce biochar with biomass from forestry operations, and a burning permit from Ecology to produce it from agricultural waste. including a fee of $1 per ton of waste.