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Hydropower plants generate lots of power and sometimes excessive noise.
For employees working inside the powerplants harmful noise levels can cause problems.
In the last 10 years, Reclamation has spent over 5 million dollars in hearing loss claims.
Among the Bureau of Reclamation's 53 hydropower plants, some built more than half a century ago,
noise was not factored into plant design.
Instead, the power industry relies on ear plugs and ear muffs to guard against hearing loss in the noisy environments.
You know, is not just the noise.
When your in there all day it's the percussions and the vibrations
that at the end of the day will mentally exhaust you.
Reclamation's research and development office in Denver Colorado
is working with the Office of Naval Research and a private acoustic design firm
to deploying noise dampening technologies to reduce powerplant noise levels.
It's an important way that we can protect our employees, protect our hearing, and as our plants age we perform rehabilitations
and include noise reduction in those rehabilitation programs.
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In U.S. submarines stationed across the globe the Office of Naval Research has successfully used noise suppression technologies
in engine rooms since the 1970s.
They've put a lot of money into making sure that a submarine is very quite, so their engine rooms are really similar
to maybe a hydropower plant. We just thought that there may be a partnership, relationship there and sure enough it was.
The pilot project, begun in 2013,
targets three Reclamation powerplants. The aim is to isolate sound and improve the environment
for powerplant workers. They've uncovered some surprising results.
In general we've been able to reduce noise in some locations as much as 15 decibles.
And more than that the employees are calmer and its a work environment
that they don't feel as much anxiety. Its a calmer place to work since they spend hours every day in that environment.
Noise control engineers like Jeff Komrower, say that most powerplants have hard concrete walls that magnify sound.
Much like a subrarine engine room these sound waves need a place to go.
And what happens is that energy doesn't go anywhere, it just bounces off the walls. And that tends to increase the noise levels
even way above the source.
To capture the noise profile and target the even the subtlest reverberations, Komrower performed acoustic surveys
using cutting edge analytical equipment to isolate hazardous noise sources.
The equipment looks like it came straight out of the film Star Wars.
It's affectionately known as the death star. It's essentially a globe that's got 36 microphones in it, and it's also got a camera in it that rotates.
What it does is it rotates around, takes about five to six hundred pictures, and creates a 3D picture of the space.
Komrower’s Death Star, or Acoustic Collagraphy Array, measured noise levels and developed noise profiles for generator rooms
at three plants: Roza, Chandler, and Green Springs. Each site had unique characteristics and noise abatement solutions.
And then you sit it stationary and you take an acoustical measurement, and because you have the 36 microphones,
the sound from different areas or from a particular location hits each of those microphones at a slightly different time.
The software allows you to take that time delay and do a transformation. You can overlay where the acoustical hotspots
are on top of the picture to validate what you could probably figure out using engineering judgment
where the source is actually coming from.
At Roza powerplant in Yakima Washington, the challenge was to locate the most aggravating source.
I would say that Roza on average was a fairly noisy small plant, especially with the exhaust fans running..
There was of course a direct noise from the generator. However in that plant there are two large cooling fans that are mounted up on a wall
that actually created a lot more acoustical energy in that space then a generator.
Once the area was identified acoustic engineers found a solution that absorbs sound and reduced the hearing hazard.
At Roza, we worked with a vendor that designed silencers that went right in front of the fans to lower the energy coming into the space,
and then we treated the reverberant situation. It was all concrete, highly reverberant,
so we put tuned absorbers, essentially acoustical panels that have a metal facing that's perforated with some sound absorption material
in the back of it. And that cut down the bouncing of the sound and reduced the overall level in the plant significantly.
We got about a 5 or 6 dB reduction in that plant, very successful.
Roza was a huge improvement. In fact, all three plants were major improvements. We pretty much got all the main,
with the exception of the turbine pits, we got them below the 85 decibel range.
The Green Springs plant was actually so loud at the control station in the plant, that you couldn't use the phone.
And it is now down under 80, no hearing protection required,
you could have a normal conversation. The vibration and percussions were drastically reduced.
With the new sound baffles in you can’t even hear them run. They’re extremely quiet. With the sound abortion materials on the walls
it took a lot of the vibration out of the plant it’s a lot calmer place to be.
Everything with the exception of the turbine pit, we were able to reduce and get below 85 decibels.
The Research and Development group hope their results can be applied to all power plants.
They expect hearing loss claims will be reduced significantly.
This technology just isn't applicable at Reclamation hydropower plants. It's applicable at all hydropower plants across the industry
around the world.
It's a real way to emphasize safety to our staff and the culture as a whole.
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