SANDPOINT — Bonner County might be forced into scaling back some of its road maintenance plans due to the rising cost of liquid asphalt products.

Unit prices for the various types of the material are anywhere from 40 percent to 135 percent higher than last year’s prices, said Ryan Luttmann, the county’s Road & Bridge director.

Bonner County’s request for bids for liquid asphalt yielded only one offer from Idaho Falls-based Idaho Asphalt Supply, which quoted a price of $1.2 million.

Commissioners voted unanimously on Tuesday to turn down the bid and seek new bids for a lesser quantity of liquid asphalt.

Much of the liquid asphalt is used in the county’s chip seal program. Chip seal is a pavement surface treatment that combines the asphalt with a fine aggregate.

Luttmann said 1,700 tons of liquid asphalt were being sought for this year’s chip seal program, but that amount is being scaled back to about 1,000 tons.

The rising cost of liquid asphalt for chip sealing is expected to cut this year’s resurfacing plans in half.

“We’ve been shooting for doing 50 miles a year. We’re looking at scaling back to about 25 miles,” said Luttmann.

The cost of liquid asphalt for chip sealing is about 40 percent higher than last year, while the cost of liquid asphalt for fog seal is up 135 percent, according to Luttmann. Fog seal is used to darken roadway surfaces so there is better contrast when new road striping is laid down.

Liquid asphalt is also used by the county’s DuraPatcher, a machine used for repairing potholes.

Analysts at the University of California’s Institute of Transportation Studies in Berkeley have said the petroleum product’s price can be driven by crude oil prices, in addition to escalating energy, transportation and refinery costs.

“I haven’t bid out asphalt paving yet and I don’t know how those numbers will look,” said Luttmann.