ANDERSON SPRINGS, Calif. – Calpine Corp. is in the middle of a $400,000 upgrade to one of its power plants which was determined to be the source of a noise disturbance for some neighbors.

In particular, residents in the area of Anderson Springs – located between Middletown and Cobb – have reported ongoing issues with the noise.
Findings in a recent noise survey pinpointed the noise to cooling fans in a southwesterly power plant.

The fans are currently being replaced, according to Bruce Carlsen, director of environmental services for Calpine.

“Overall results of the noise survey determined the dominant sound was coming from the cooling fans in Unit 16,” Carlsen said.

Carlsen said the fans operate at different times and on two different speeds.

One particular fan, he said, while operating on high speed, was found to be excessively noisy.

Carlsen said the fan blades on the particular unit were changed and while the noise level decreased, the results did not translate to the community.

Additional mitigation efforts, he said, include changing the gear boxes on the fans with a recommendation to reduce the oscillation speeds.

“These are huge pieces of equipment so it's not a small recommendation. There are 11 fans and we've changed the gear boxes on one through seven. The sound is less frequent but the loudness is the same,” Carlsen said. “It takes a sustained effort to get those gear boxes changed.”

According to Carlsen, determining the source of the disturbance also required a sustained effort, beginning with an initial noise survey in February 2011.

The initial survey was conducted in response to a complaint from a resident of the Anderson Springs area, Carlsen said.

Efforts were directed toward identifying the noise the resident was describing including the hiring of a noise consultant, he said.

Carlsen said changing atmospheric conditions, in addition to when the fans activated, made it difficult to pinpoint the source of the resident's concern.

He said results of the first survey were not accepted and a second was initiated.

Monitoring sites were established at power plants in areas north and south of the community. Carlsen said the power plant in the north was identified as the source of disturbance.

“We didn't hear any power plant noises at the south site, which confirmed the findings of the 2011 survey,” he said.

Calpine works cooperatively with the Anderson Springs Geothermal Committee, as appointed by the Lake County Board of Supervisors, to address geothermal impacts to the community. It is an ongoing effort conducted through Calpine's Community Investment Fund.

Carlsen said in the initial survey all power plants were included in the report.

“Unit 16 had the most impact so the second study focused on that unit. The level of sounds measured at the power plant in the Anderson Springs area were in compliance with the county's general plan,” he said.

“However, it seemed to be the No. 1 issue in the community and purpose of the community fund is to work with the community,” Carlsen added. “We are working to reduce those sounds because that is what the community wants.”

Joan Clay, representing the Anderson Springs Geothermal Committee, said while a person's location is relevant, some noise does persist.

“Some people want the area to be the way it used to be,” she said. “Calpine has done many things to improve conditions but the noise is not completely gone.”

Carlsen said Calpine plans a $400,000 expense to upgrade the fan systems in Unit 16.

He said the noise survey, at $138,000, was funded through use of the county's geothermal royalty funds.

Northern California Power Agency, which operates two power plants in the geothermal zone, also participated in the survey, he said.

Danielle Matthews Seperas, Calpine manager of government affairs, said visitor tours of the system provides people with a better understanding of how it works and the impacts that may affect the community.

Regular tour dates are posted on the Calpine Web site, www.geyser.com .

Additionally, those interested can reserve a spot for a tour during Calpine's annual Earth Day celebration, to be held May 2 at the Calpine Visitor and Information Center in Middletown.

For more information or to make a reservation call the center during regular business hours, 11 a.m. to 5 p.m., Wednesday through Saturday, toll-free at 1-866-439-7377.

Email Denise Rockenstein at This email address is being protected from spambots. You need JavaScript enabled to view it. .