Also might try a long auger bit to make holes every 6" or so to loosen it up. https://www.amazon.com/Bosch-Daredevil-NKLT24-Auger-2-Inch/dp/B003BIFMXS/ref=sr_1_2?s=hi&ie=UTF8&qid=1477919695&sr=1-2&keywords=1.5+auger+bit