Stop that ‘Dam’ Noise: ONR, Engineers Tackle Noise at Hydroelectric Plants

By Tammy J. White, Office of Naval Research

Using research designed to protect warfighters from noise-induced hearing loss in the naval environment, the Office of Naval Research  has joined the Bureau of Reclamation  and U.S. Army Corps of Engineers  to turn down the volume at the nation’s power plants.

ONR will lend its extensive expertise in noise-induced hearing loss (NIHL) to help identify noise sources and propose engineering controls at dams and hydroelectric plants nationwide as part of the interagency agreement.

“The Navy in general, and ONR in particular, is leading the curve when it comes to understanding the dangers of noise,” says Kurt Yankaskas, a program manager in ONR’s Warfighter Performance Department . “It’s a serious problem not only in the Navy and Marine Corps, but across modern society.”

The added project scope results in $14,000 in additional federal funding, bringing the total to $109,000, to evaluate and seek new controls for protecting plant workers from hearing damage sustained on the job.

Noise is a research area ONR knows all too well.

“Within ONR, we’re addressing noise-induced hearing loss from all perspectives—engineering, audiology, acquisition programs, medical research and more,” Yankaskas says. “The American public is starting to learn how pervasive our noise exposures are.”

The Bureau of Reclamation maintains and operates 476 dams and 58 hydroelectric power plants across 17 western states. Collectively, dams like the Grand Coulee in Washington and the Hoover in Colorado produce more than 40 billion kilowatts of energy.

By its estimates, that’s enough power to satisfy the needs of 9 million people for one year, offsetting the need for an equivalent 6.8 billion tons of coal or 23.5 million barrels of oil.

It’s no wonder the dams have been labeled national strategic assets. But that power comes at a substantial cost.

“Of our worker’s comp costs, about 20-25 percent is due to hearing loss compensation,” says James Meredith, who manages safety and occupational health, security safety and law enforcement at the Bureau of Reclamation. “That amounts to $1.5 to 2 million dollars per year … Dollar-wise, it’s the largest single component of claims that we have.”

The intense roar of the water threatens the hearing of approximately 5,300 of the organization’s workers across the country, despite attempts to provide employees with personal hearing protection.

“Down near the lower elevations of the power plant, where the water is coming down through the pen stocks and coming down over the turbines, noise can range as much as 115-120 decibels, which is quite loud,” Meredith says. “And [for] every five decibels, that increases by seven or eight factors of loudness.”

That’s louder than the sound output at an average rock concert or music venue, which is estimated to range between 110-115 decibels by the Occupational Safety and Health Administration .

Six sites, of varying sizes, will undergo an initial round of noise surveys this spring, with additional surveys slated later this year for plants operated by the U.S. Army Corps of Engineers.

“In essence, we’re being asked to help look into the issue of noise control to reduce noise exposures,” says ONR’s Yankaskas. “This is an opportunity to transition the approaches we’ve been developing for Sailors and Marines ONR to other federal agencies.”

The Corps’ infrastructure includes power-generating units and plants that provide 25 percent of the nation’s hydropower capacity—but its reach expands to a host of other facility types, says Andrea Pouliot, industrial hygiene program manager.

Some 25,000 miles of commercially navigable channels, 225 lock chambers and 2,500 recreational areas fall under the Corps’ charge. At one facility, the John Day Lock and Dam along the Columbia River, the Corps estimates more than 2.5 million gallons of water crashes down every second the dam operates at 100 percent water discharge capacity.

Pouliot attributes safety controls, such as covering turbine generators, to limiting personnel’s exposure.

“We still do have hearing loss cases, and we are excited and interested in trying to figure out how to control the noise so that we’re able to prevent them,” Pouliot says.

Field measurements, including acoustic octave band and vibration analyses, will be taken at selected facilities in the Pacific Northwest and Colorado regions through May 2012: Grand Coulee, Roza, Chandler, Dalles, Detroit, Estes, Mary’s Lake and Flatiron.

Following a data evaluation period this summer, ONR will propose areas for noise improvement through a range of engineering and technology controls.

Sustained exposure to high sound levels attributed to water, aircraft engines, machine shops and other areas in the naval environment—and sudden intense noises like improvised explosive devices encountered in the field—can all contribute to noise-induced hearing loss over time.

Through the interagency partnership, ONR officials continue their efforts to demonstrate the broad applications of naval science and technology across government and industry as well as sectors such as public health, energy and power.

ONR’s Noise-Induced Hearing Loss Program  takes a multi-pronged approach at devising sound solutions in the naval environment: reducing noise at the source; developing personal protective equipment; developing medical prevention and treatment strategies; and evaluating incidence and susceptibility.