In 184.108.40.206 Fuel Handling - Coal of NFPA 850 established that
220.127.116.11 There are measures that can be taken to lessen the likelihood of coal pile fires. These measures are dependent on
the type and rank of coal. Among the more important are the following:
(1) Short duration, active, or “live” storage piles should be worked to prevent dead pockets of coal, a potential source
of spontaneous heating.
(3) Coal placed in long-term storage should be piled in layers, appropriately spread, and compacted prior to the addition
of subsequent layers to reduce air movement and to minimize water infiltration into the pile.
So, i have question. How many days to mean short duration and long-term storage?