Aug. 18--A $3 million project at Crites Field is saving the Waukesha County airport $50,000 thanks to a byproduct of the coal- burning process in power plants in Pleasant Prairie and Oak Creek.

Fly ash from We Energies coal-fired power plants is being used this week to rebuild an auxiliary runway and roadways at the airport.

Once upon a time sent to landfills, fly ash is now recycled for use in pavement projects. Waukesha's is the first airport in southeastern Wisconsin to use the coal-burning byproduct, We Energies said.

The fly ash is marketed as a replacement for Portland cement, the type of cement used in virtually all concrete.

When coal is pulverized down to a powder and then combusted in the power plant boiler, the fly ash is captured before it can escape through a plant smokestack. Fly ash, which represents about 5% of the coal that comes into the power plant, works as a lubricant, binding recycled pieces of pulverized asphalt from the old runway together, said Bruce Ramme, manager of land quality at We Energies.

"Airports are probably one of the most challenging applications as far as the performance of pavement, so we're honored to see our fly ash being used in this airport," Ramme said.

We Energies sells its fly ash to Lafarge North America, which transports and delivers the fly ash from the utility's coal plants to various construction sites. This year, the biggest project for We Energies and Lafarge has been at Chicago's O'Hare International Airport, where fly ash is being used for soil stabilization, he said.

Jim Rosenmerkel, an engineer who does consulting work for Lafarge, said fly ash from Wisconsin coal plants has been used at airports in Antigo and Merrill. The Waukesha project ended up saving $50,000 off a price tag of nearly $200,000 that would have been needed to use a more conventional pavement approach.

"It saved the taxpayers here about 25 percent" on the pavement- related portion of the Waukesha airport project, he said. "That's pretty big."

Demand has been so high for the product that We Energies is using more fly ash than its power plants produce. The utility has started to scoop old fly ash from landfills where it was disposed years ago, Ramme said.

The utility told regulators its sales of fly ash totaled $3.15 million last year.

The key for the utility comes in the savings on landfill costs and the ability to make use again of coal, already used once in the electric power generation process.

"You're essentially turning it back into a rock again," Ramme said.