I already linked it, their test pile is 2k-5k tons ... a truckload is 20-23 tons ... so their test piles is 200-250 truck loads ... a truck load is about $4k-$5k ... so $400k-$1mil...

if a truckload can a year or ..in a pile or bin ... I don't see why it couldn't last longer ... (based on reading some threads on nepacrossroads.com )

the paper discusses covering the pile with ash/dirt to prevent loss of calories....

but like I said, if I were going to try to store 40 tons or two truck loads or $8k-$10k worth of coal
I'd talk to more than one person in the industry, a professor, osha, someone whos studied it in-depth and has a checklist