Global firm suggests mitigation plan
Published in The Mining Journal on Jan. 23, 2019
MARQUETTE — The Marquette Board of Light and Power Board of Directors on Tuesday unanimously approved allocating an amount not to exceed $2.9 million to address noises and vibrations emanating from the Marquette Energy Center, or MEC. Vice Chairman and Secretary Bob Niemi was excused from the meeting.
The MEC, which went online in 2017, was projected to cost around $65 million to build, but ended up costing $62 million. Initially, BLP officials hoped to spend the excess money on capital improvement projects.
However, shortly after operations began at the facility, over 20 complaints were submitted by Marquette Township residents who live near the facility about high and low frequency sounds as well as vibrations believed to be coming from the energy center.
Even though there are no sound regulations in the city or state that govern the MEC, the BLP board discussed the issue at nearly every one of its meetings last year, while BLP staff worked to review data with designers and manufacturers of the MEC and its equipment.
Several months ago, international emissions and noise management company INNOVA Global conducted a study at noise-sensitive receptors near the MEC. Representatives from INNOVA presented the results of the study and their recommendations at the BLP’s meeting Tuesday.
Art Cooper, senior acoustical engineer at INNOVA, said the first thing they did was review all existing reports and data.
“There’s been various studies from different groups beforehand, so we came in and assessed all of the prior work before we started to have an understanding of where the facility was on that day,” Cooper said. “Next … we did an oversight of the whole plant.”
After conducting a near-field survey around the entire facility to quantify sound levels of each source, testing was also done near residential areas.
In the study, INNOVA discovered that the major low frequency noise contributors are largely from the building walls and roof of the engine hall. Some of the radiators are also a part of the problem, Cooper said.
“So, our recommendation, first of foremost, is the building envelope,” Cooper suggested. “We propose to retrofit the existing wall and roof with a new design, a heavier design that will help keep the sound in and not let it come out. The building ridge vent, as well. We would remove the existing vent and replace it with an acoustic system, a series of hoods that point to the north, which is away from the bulk of the residents. And finally, looking at some radiator noise control.”
Aaron Atherton, senior manager of business development at INNOVA, said the project will be done in stages.
“If we went in and ripped the whole thing apart, it would be incredibly loud for an extended period,” Atherton said. “It takes us a little bit longer to do it in stages, but again it minimizes the impact and keeps it a little more pleasant for everyone.”
Tom Carpenter, executive director of the BLP, said INNOVA’S proposal has been the best presented to staff so far.
“Another option or two has been proposed but we don’t have any certainty that it’ll work,” Carpenter said. “In one regard it actually might make things worse. There are three pieces to this design, the walls and the roof are one part, the ridge vent is another piece and radiator barriers are the third piece.”
Carpenter said staff plans to explore a possible electrical solution regarding the radiators. He believes the noise might not be from the fan, but instead the speed of the motors. If the electrical mitigation works, the whining, high-pitch noise residents have complained about would be resolved, he said.
INNOVA guarantees they’ll get the sound and vibration down significantly, but the mitigation won’t completely fix the issue.
Once a contract is signed, INNOVA will start assessing the problems and hold post-construction sound measurements and testing as well.
BLP board member Jerry Irby said the board approved an additional $250,000 for sound mitigation in June 2016.
“We thought that additional money going into the project could protect the neighborhood and protect the quality of our MEC system,” Irby said. “So, as it comes to this point, we find out that there is an ongoing problem.”
He said allocating the money to address the issue is doing the right thing for the BLP’s neighbors.
“We want this MEC to be the shining star of the community,” he said.
Board Member John Prince thanked the room full of neighboring residents for their patience, stating that the BLP didn’t want to just throw money at the problem without knowing it could be fixed.
Atherton and Cooper were expected to be available this morning to answer questions or address any concerns at the BLP’s main office, 2200 Wright St.