At 1:20pm flames and smoke were observed coming from the top of #6 concrete coal silo. The GFD was contacted at 1:25 and arrived on site at 1:35. When the GFD arrived on site, there were no visible flames however to ensure that the fire was extinguished, the GFD sprayed water into the top of the silo until no additional smoke was visible. Smoke was no longer visible at 2:15pm.