An explosion at the Ames Resource Recovery Plant this morning roused the neighbors, but resulted in little damage and no injuries. Plant supervisor John Pohlman says the explosion happened in the primary shredder room.He says the primary shredder is where garbage is shredded up to be used as fuel for the city power plant. Pohlman says there was little damage to the building and equipment as it is specially designed for just such an emergency.He says the building has 16 inch steel reinforced walls and the shredder has one inch thick steel. The top of the shredder has steel plates and rubber flaps that’re designed to let out and dampen the force of the explosion. He’s says they haven’t determined what exploded.He says it’s hard to tell what it was because everything is shredded up, but he believes it may’ve been a propane tank. Pohlman says a new mandate requiring people to use tanks with new safety valves has led to many of the tanks being thrown away. He says they offer to take the tanks at no charge to avoid the danger of explosions in the shredder, but they can’t screen them all out.He says they have a magnet to pull metals out of the garbage, but that happens after it has been shredded, and he says a tank could slip through unnoticed. Neighbors who heard the explosion around eighth o’clock this morning called the fire department. Pohlman says the plant was shut down a time for inspection, but is back up and running.