Hennepin County stopped collecting batteries at all but two drop-off recycling sites Wednesday owing to fears that discarded vape pens and e-cigarettes can easily activate, heat up and start a fire.

A staff member at the county's Westonka Library in Mound two weeks ago noticed smoke wafting from a plastic barrel used as a collection point for recycling batteries. County officials investigated and learned that a discarded vape pen had flipped on and begun igniting other batteries in the bin.

David McNary, assistant director of environmental services for Hennepin County, said that if the incident had gone unnoticed or happened at night, things could have been much worse.

"One vape pen and you could lose an entire building," he said.

The county now will accept batteries only at its drop-off sites in Bloomington and Brooklyn Park. Both locations are staffed by people trained to handle batteries, among other potentially hazardous items.

On Wednesday afternoon, cars were rolling through the Bloomington site at a steady clip without waiting. Nevertheless, the ease and convenience of dumping batteries at a nearby bin are gone. The barrels have been removed from city and county buildings, libraries, schools and recreational centers.

David McNary of Hennepin County held the vape pen and battery that started a fire in a recycling bin.

Louisa Tallman, who is in charge of household hazardous waste operations at the county, wasn't happy about having to make the decision to remove the bins. For one thing, community collection sites accounted for 50,000 pounds of batteries in 2018 — about 25% of the county's entire intake.

"I felt like I was giving up and crying uncle," she said. "It was hard. I'm supposed to be able to figure it out. I'm the fixer."

But she saw no alternative. "This is not something we did lightly," she said.

McNary agreed. He said that increasing awareness of the dangers of vaping and e-cigarette devices has caused a bump in their disposal.

Tallman said there were eight such devices in the Westonka bin, and it wasn't even a quarter full yet.

Like click pens, the devices have easy push-button activators that flip on with little pressure and ignite. Because separating the batteries from the devices is exceedingly difficult, users tend to dump them whole, with the batteries still inside.

County officials say users should bring unwanted vaping and e-cigarette devices intact to the drop-off sites in Bloomington (1400 W. 96th St.) and Brooklyn Park (8100 Jefferson Hwy.), and professionals will take it from there. Some big- box stores also run their own battery recycling programs.

Tallman and McNary said that rechargeable, lithium ion, button and rechargeable batteries should always be handled with care because they are extremely toxic and combustible. Before bringing them to the drop-off, each battery should be placed in its own bag or tape should be placed over each end.

Any button battery bigger than a dime needs to be recycled, Tallman said; tiny batteries from hearing aids do not.

Single-use alkaline batteries do not contain hazardous materials and can be placed in the trash or brought in to drop-off facilities for recycling. For safe storage, they should be handled the same as other batteries.

More information is available at the Hennepin County website or via e-mail at environment@hennepin.us.

Rochelle Olson • 612-673-1747 Twitter: @rochelleolson