The answer is gravel.

The question? How does a Great Falls-based company known for its fleet of big yellow trucks and work on local road, paving and utility projects, get involved in developing what may be Montana's first commerical wind farm?

"That's the lifeblood of the company -- gravel," said Bob McIntyre, chairman of United Materials of Great Falls.

The company depleted its main gravel pit on Gore Hill, south of Interstate 15, a few years back. A search for more gravel led United Materials north, across the four-lane Interstate, to a 1,700-acre site on the northwest edge of the Gore Hill bench.

While the gravel was plentiful and access was good, the new pit site acquired by United Materials lacked a key element: enough electricity to run the machinery used to mine and process gravel.

The site is some distance from a commercial utility line large enough to supply the operation. Extending a big line would involve a costly new substation and a series of overhead lines.

"That was not economically feasible for us to do on our dollar," McIntyre said.

Search for power

The short-term solution involved installing diesel generators. The long-term plan involved head scratching and casting about for ways to get commercial power.

"In our conversations, we talked about wind" and other options, McIntyre said. "The more we researched it, the more the wind made sense."

For the past 2Þ years, McIntrye has been working on developing a commercial wind farm on the west end of the United Materials property. The Cascade County commission recently approved a plan to install six, 326-foot-tall wind turbines that will produce nine megawatts of electricity.

But the juice won't run the United Materials operation. The plan, as McIntryre explained, is to build the wind turbines, use the substation and lines that come with the project to connect the United Materials plant to a commercial electricity supplier, and sell the wind-based juice to a utility company "as a profit center for United Materials."

The company has a tentative deal to sell the nine megawatts of electricity it would generate to Idaho Power Co. The utility company has asked the Idaho Public Utilities Commission to approve the deal.

United Materials has teamed with Exergy Development Group of Missoula to build the turbines. McIntrye said United Materials will finance the project but he declined to discuss the cost. Industry observers say it costs about $1 million per megawatt to build wind generating facilities, giving the Great Falls-area project about a $9 million price tag.

Hurdles remain

While the project has cleared the local planning process, several hurdles remain.

United Materials needs to work out an "interconnection and transmission" agreement with NorthWestern Energy that will allow it to put the wind-generated electricity on a NorthWestern line that runs along the west edge of its property and ship it to a buyer. Negotiations on that agreement are under way, McIntyre said.

The company is keeping a close eye on Washington, D.C. A big energy bill before Congress contains wind energy production tax credits that McIntrye said are crucial to the project.

"That bill is stalled at this point," said Christine Real de Azua, a spokeswoman for the American Wind Energy Association. "We are looking at alternatives in Congress."

The tax credits, which expired at the end of 2003, amount to 1.5 cents per kilowatt hour each year. For a nine-megawatt project, the credits could total $13,500 annually. The production tax credits were only offered for utility-grade projects, not turbines built for individual use, De Azua noted. The wind energy association is seeking a three-year extension of the tax credits, saying the incentives are crucial to the continued development of wind energy in the U.S.

"We don't have any control over congressional action," McIntyre said. "When those two things are completed, we will be looking at starting construction."

If work on the turbines begins this summer, generation could begin by year's end, he said.

Delays possible

Another possible delay could involve the turbines themselves. A number of big wind energy projects across the United States are on hold because of the stalled production tax credit situation. If and when the energy bill is enacted, it could unleash substantial demand for turbines, and the relatively small United Materials project might not be a priority for General Electric or another turbine manufacturer.

"We are hoping to not get lost in the shuffle and be able to get turbines," McIntyre said.

One factor in the project, the wind, leaves little uncertainty. The turbines perched on the edge of the Gore Hill Bench will be exposed to wind that cruises unobstructed for many miles.

The wind project will be just a few miles from the Great Falls International Airport, and McIntyre and others relied heavily on wind data gathered by the National Weather Service office, also on Gore Hill.

The average wind speed on Gore Hill is 12.4 miles per hour, according to the weather service. The average peaks at 14.7 mph in January and hits its low in July at 9.9 mph.

"It trails off as we head into the warmer season," said Dave Bernhardt, a weather service meteorologist, noting the averages are based on measurements from an anemometer or wind gauge about 30 feet high.

"His instruments will be a lot higher than that," and exposed to greater wind speeds, Bernhardt said.

Winds studied

United Materials installed its own 150-foot anemometer a little over a year ago not far from where the turbines eventually will rest.

"I'm really comfortable that we know how much energy we can generate in an average year," McIntyre said. "Of course, with the wind, there is no average year."

A small substation near the wind turbines will "ramp up" electricity and put it on a 100,000-volt NorthWestern line that crosses the west edge of the United Materials property.

Once the turbines are installed and spinning, United Materials has no plans to divert from its core business of producing and selling gravel, asphalt and cement and doing road, runway and underground utility installation work.

With a solid niche in the Great Falls area, United Materials sees its future in the ground, not blowing in the wind.

When developing the turbine project, "our primary thought was going towards how we are going to develop the gravel pit," McIntyre said.

Larcombe can be reached by e-mail at blarcomb@greatfal.gannett.com, or by phone at (406) 791-1463 or (800) 438-6600.

The United Materials gravel pit off McIver Road will be the site of the wind farm.

A 150-foot anemometer west of the United Material gravel pit measures wind speeds. The tower is less than half of the height of the turbines that will be built on the site.