as was mentioned try banking it, but with a coal with a high coke button like the coal that you're burning and especially one with a lot of fines and smaller sizes, there will be no good way to deal with the problem outside of redesigning your furnace. There is no reason to burn crappy coal in an area like yours with so many options and sources. I would highly suggest trying some of the coals mentioned or trying Valier Coalyard (south of punxsy) They have nut coal and a coal that is about baseball or softball size, Thier coal is not a low coke-button coal, but it is not as high as what you're using and neither I nor my customers have ever had problems w/ it bridging, especially in the larger "oversize" size. http://www.valiercoalyard.com
- was $80/ton for lump/"oversize" coal.
also, be sure you're using a deep bed at all times, and it's a good idea to bank it slightly nonetheless.