Hillsborough County Fire Rescue says "high-density plastic pipes" are to blame for the thick, black smoke billowing from a massive fire at the Mosaic fertilizer plant Monday evening in Riverview. The fire department received 911 calls from Mosaic at 5:47 p.m. about a fire at their facility at 8813 U.S. 41. Crews arrived to "heavy fire" at the plant and a nearby grass fire that was sparked by brush. The fires were "rapidly expanding due to high winds," the fire department said. "We had multiple levels to deal with here," Rob Herrin, the department's public safety information chief, said. Aerials from Sky 10 showed a large cloud of black smoke coming from the Mosaic property — a result of the thick polyethylene pipes within the plant, according to Herrin. "Think about, kind of, PVC burning except really big," he said. Herrin explained that the fire is also particularly hot because of Mosaic's plastic pipes. “The challenge right now is there’s a lot of heat and a lot of heat requires a lot of water," he said. MORE: https://www.wtsp.com/article/news/local/hillsboroughcounty/black-smoke-fire-riverview-hillsborough-mosaic/67-60568bd1-c7f0-4c0e-b3a7-50e9d90015eb ►Subscribe: https://on.wtsp.com/youtube ►Website: https://www.wtsp.com/ ►Facebook: https://facebook.com/10TampaBay ►X: https://twitter.com/10TampaBay