The site of the geothermal project in the Deschutes National Forest near Newberry National Volcanic Monument.

SUNRIVER — Cracking of hot rock deep within Newberry Volcano will start early next month, the company leading a geothermal experiment announced Wednesday night at a public meeting.

AltaRock Energy of Seattle plans to pump cold water down a 10,000-foot well beginning the week of Oct. 8, Susan Petty, company president said.

About 20 people attended the meeting in Sunriver, with a vocal contingent of four repeatedly breaking into her presentation with questions about whether the experiment was fracking and if it would taint groundwater.

“The kinds of contamination they are concerned about won’t happen because we are not doing that,” Petty said after the meeting.

Fracking, short for hydraulic fracturing, is the controversial process of breaking underground rock with high pressure water mixed with chemicals to release pockets of oil and natural gas. Petty says AltaRock will be using hydroshearing rather than fracking in the experiment.

Hydroshearing will lead to a network of small cracks, she said, while fracking creates large fractures.

The critics of the experiment argue there isn’t a difference and the company is avoiding using the term “fracking” to avoid controversy.

“Fracking is what it is,” said Sheilajean Whitehead, 59, a former nurse from Bend.

She was among the group who repeatedly questioned Petty about how the project might affect groundwater and the volcano. The other key concern of critics is the possibility the experiment will cause earthquakes, or worse, an eruption.

“How are you going to turn off the volcano once you turn it on?” Whitehead said.

Petty said the experiment will be creating earthquakes, but the “micro” temblors will be so small that people in La Pine and other nearby places won’t feel them. The company will use sensitive equipment to monitor the earthquakes and track the spread of underground cracks. It has plans to stop the experiment if the quakes are strong enough to be felt.

Petty said the experiment won’t trigger volcanic activity.

“This is too small a thing to affect the volcano,” Petty said. The U.S. Department of Energy is covering about half the cost of the $44 million project, which Petty said could lead to major breakthroughs in geothermal power. While there is hot rock in the Newberry Volcano, there is not a traditional geothermal source of steam venting from the rock.

In the experiment, the company is attempting to create geothermal activity by pushing water through cracks in the rock.

The experiment will expand on lessons learned at projects around the world, Petty said, building a larger and more productive network of cracks in the rock. She said the technology could lead to geothermal power production wherever there is hot rock underground.

“That is what we are trying to figure out how to do, how to do this anywhere,” Petty said.

Geothermal experiment at Newberry

AltaRock Energy of Seattle is posting updates online about its geothermal experiment at Newberry Volcano. Go to http://www.facebook .com/NewberryEGS and Blog.NewberryGeothermal.com. You can also get information by calling 855-872-4347 toll free.