The fire at the city landfill last month may have seemed insignificant to most people because it burned only garbage, but city officials estimate it cost more than $15,000 to fight.

Firefighters battled the blaze May 26 - suspected to be arson-caused - for more than 18 hours, Provo Fire Chief Bill Blair said. Other city employees also helped, amounting to significant overtime for everyone involved.The time equaled 100 man-hours of overtime, or 150 hours of pay for firefighters, Blair said. "That's like hiring four people for a week. An incident like this is expensive."

The total cost to the department was about $4,000, he said.

The Public Services Department spent about $11,000 for overtime and equipment use, according to Dale Stephenson, streets and sanitation manager.

Blair said the fire was "suspicious" and is still under investigation. Officials initially thought the fire had ignited from ashes dumped at the landfill, but police are now investigating reports of arson.

"We are quite certain it was arson," Detective Don Messick said. "We have no suspects at this point, but we are looking at a few people."

Stephenson said the city would have let the fire burn if there wasn't a pollution concern. "We're in the business of taking care of the problem within our communities of how to dispose of waste, and we are surely but slowly working to operate in an environmentally safe manner."

Landfill fires can spread beneath the surface and burn underground for hours, days or months, much like a mattress, Blair said. If fire is found under the surface, it has to be dug up to be put out. In the incident May 26, fire consumed trash as much as 5 feet down.

"People don't realize it's not free (to fight fires)," Blair said. "The taxpayers, and that includes me, pay for things like this. It's an expensive item, but we have to fight it. It causes an air pollution problem if we don't."

Smoke drifted south to Springville, Mapleton and parts of Spanish Fork, affecting visibility and air quality in the area.

Four fire engines were called to the fire, which was reported by an area resident at 1:30 p.m. Firefighters propped up hoses to provide continuous flow of water to the blaze.