California Code, Public Resources Code - PRC § 4438

Flammable forest product waste material may be disposed of by means of fire in an enclosed device effective in preventing the spread of sparks or fire, situated in an area cleared of grass, grain, brush, slash, litter, and snags for a distance of 30.5 meters (100 feet) surrounding the device or by landfill or other methods which meet applicable state and local fire safety, air, and water quality standards.

A burning permit shall be obtained for the use of the device pursuant to Section 4423 and all other provisions of law.