The noise made by wind turbines is the equivalent of background noise in a conference room, an engineer testified Monday night at a meeting before the McLean County Zoning Board of Appeals.

Timothy Casey of HDR Engineering, Minneapolis, Minn., continued testimony began at the last meeting on his company’s noise analysis of the proposed wind turbines. His analysis was based on a wind speed of 22 mph — the wind might blow more, but the turbines are adjusted so they don’t spin faster if the wind speed is higher.

He said because of a redesign of the configuration of the blades, they are quieter and don’t “thump” like older models do. Earlier, it was reported that the county requires 1,500-foot setbacks to distance turbines from homeowners.

About 100 people attended one in a continuing series of four-hour meetings that continue this month. Invenergy Wind LLC of Chicago has proposed that 100 wind turbines be located on 12,200 acres in McLean and Woodford Counties. The White Oak Energy Center would be located west of Interstate 39 and north and east of Interstate 74. A total of 83 acres of farmland would ne taken out of production in the project, Invenergy has said.

Members of the audicence also questioned Casey. One audience member, Nick Goloff, of rural Secor, spent half an hour asking questions peppered with technical references but also asked, “Have you ever flown a kite?” It was then chairwoman Sally Rudolph, interjected, “OK, I have flown a kite.”

She said Casey should not have to answer that question and ordered a 10-minute recess.

Most of the audience members who spoke were from the Carlock area. The audience also found out there would be expensive road upgrades at Invenergy’s expense if the project is approved. No exact cost figures and other details were available because everything is still being negotiated.

Bloomington attorney Robert Lenz said he was negotiating road maintenance agreements for townships roads affected if the project is approved.

“Our job is to try to make sure all roads affected by construction have been repaired and upgraded,” Lenz said.

Board member Drake Zimmerman asked if local residents would be hired for the road work, and Lenz replied that would be up to Invenergy.

David Brown, a consulting engineer with Lewis, Yockey and Brown, a Bloomington engineering firm, said he was working much the same as Lenz with county highway roads to determine which ones would be used in construction and determining the final extent of road improvements.

Meetings will also be at 6 p.m. Wednesday and Thursday at the same location, and the room has also been reserved for Monday, and Jan. 30 and 31.