Is “volunteer” covered by workers’ comp?

Diane Minish filed suit against Hanuman Fellowship, Mount Madonna Institute and the Mount Madonna Center seeking compensatory and punitive damages for personal injuries she suffered when she fell off a forklift allegedly due to the defendants’ negligence.  While at the defendants’ property, she had climbed onto the prongs of the forklift and the operator raised the prongs and drove over uneven ground into a hole.  She was thrown onto the ground and suffered serious injuries.