(CBS) — White Styrofoam will get you a big orange sticker now if you put it in your blue cart, reports WBBM’s John Cody.

Chicago Streets and Sanitation Commissioner Charles Williams says his crews are now handing out orange reminder stickers saying you put the wrong stuff in the big blue recycling carts.

“The most common mistake normally is your grass clippings, or yard waste material,” Williams said. “Another item that should not go in there is Syrofoam. There are also plastic grocery bags don’t go in there.”

Williams says the blue cart does take plastics, but no Styrofoam or yard waste. He says the biggest problem is in two and four flats where there’s no way to tell who put what in which bin.

He says the program’s working and in 91 percent of the blue bins plastered with the orange sticker, the next loads have all been stuff that’s supposed to be in there.