I usually dig them hydraulically. Dig a shovel-wide hole about a foot from and around the clump then use a water hose to flush away the soil from the roots. Saves the roots and makes the clump easier to lift. Usually end up lifting the mass out of the hole with a pry bar. I have a steel spud bar which works perfectly for the job. I have a homemade slotted box placed upon saw horses for the final flush and rinse.
