POST FALLS - Even in hazardous materials speak, this was nasty.

So nasty this material forced Kootenai County's waste transfer station on Prairie Avenue to be evacuated on Thursday morning for nearly three hours, caused a plume of smoke and burned a hole in one of the county's metal trailers.

"We know it was really bad because when it was loaded onto our trailer and came into contact with other garbage, an acid smoke plume came up," said Roger Saterfiel, the county's solid waste director. "Whenever that happens, the smoke may not bother you or it could be so bad that it could take your life."

Saterfiel said a handful of residents and employees were immediately evacuated from the property, while those coming in were turned away while trained county employees in haz-mat suits investigated in the main garbage building of the facility.

"It was a commercial-grade acid, but we're not sure what type," Saterfiel said. "We could not find the container."

Saterfiel said it's also unclear how much of the material spilled.

No one was injured or required treatment.

"I attribute that to our extensive training and drills," Saterfiel said. "Today was an example of why you take the time and money to train and do drills, so no one gets hurt."

Ironically, solid waste staff recently had a surprise drill involving a smoke bomb, which came in handy during Thursday's incident.

"The employees knew exactly what to do," Saterfiel said. "My employees did an excellent job of keeping the public and themselves safe."

Saterfiel estimates haz-mat concerns temporarily close transfer stations in Post Falls and on Ramsey Road in Coeur d'Alene once every two or three months, but Thursday's incident became even more serious due to the smoke and trailer hole.

"In the old days before we really started to train our employees, we had fires on Ramsey once a week," he said. "But now employees are trained to recognize certain chemical containers."

Saterfiel believes someone simply dropped off the material on Thursday morning, not meaning to cause such commotion or any harm. The person who disposed of the material could not be found due to the volume of people who use the facility each day and employees at the entrance typically don't ask residents if they are getting rid of hazardous materials, but rather household products.

"Typically employees ask people if they have household items or garbage and typically people say yes and they're on their way," Saterfiel said.

Anywhere between 200 and 1,000 people use each transfer station per day, depending on the day, weather and other factors.

Household hazardous materials are only supposed to be dropped off at transfer stations on certain days - Fridays and Saturdays at Prairie and Wednesdays and Saturdays on Ramsey - and they go in a special area staffed by a specially-trained employee, not in the regular garbage section.

"It is not economically feasible to have that area open every day," Saterfiel said.

Commercial hazardous materials and agricultural products are collected only on special designated days.

The haz-mat event is the third incident this week to slow down the Prairie station operation.

The station was closed for about an hour late Wednesday afternoon due to a two-vehicle injury accident on Prairie Avenue that damaged the facility's fence. Users were also temporarily held up at the scale earlier in the week after someone dropped off a block of dry ice that was steaming.