Householders should pay special attention to the way they dispose of used propane gas tanks, which retain trace amounts of gas even when they are emptied, according to recycling officials at the state Central Landfill, in Johnston.

In the last two months, Rhode Island Resource Recovery Corporation workers have removed two propane tanks from the paper-recycling area of the recycling center at the landfill, prompting a reminder that used tanks should be recycled through Resource Recovery’s Eco-Depot program.

“The two tanks that we have removed from the sorting area had already passed over a drum feeder’s rotor, which is a machine that would most likely puncture a tank of this type,” said Mike OConnell, executive director of Resource Recovery.

“Because trace amounts of gas linger in an ‘empty’ tank, there is a tremendous risk for explosion and injury to workers,” OConnell said.

By law, propane tanks cannot be put out with the regular trash, tossed into Dumpsters, or put in recycling bins. They must be recycled as household hazardous waste, through Resource Recovery’s Eco-Depot program, OConnell said.

In general the drivers who pick up recyclables at curbside in Rhode Island communities are conscientious about refusing prohibited items, said Resource Recovery spokeswoman Sarah Kite.

But some communities use large covered containers which are lifted mechanically into recycling trucks. The drivers “can’t see what’s inside,” Kite said.

In addition, she said, “we see small camp-type tanks” that can’t always be spotted if they are placed in the bottom or middle of an open container.

Rhode Islanders may make an appointment to drop off a broad range of household hazardous waste at the landfill in Johnston by calling 942-1430 or by going to www.rirrc.org and clicking on the Eco-Depot logo.

gmacris@projo.com