Thanks for Recognition
I would sincerely like to thank you for the great article you wrote about the East Chicago water filtration plant. The article shows all of the hard work that went into the planning, engineering, designing, construction, training and startup of our new system.
I believe I can speak on the behalf of all water and wastewater treatment system professionals, in thanking your magazine for providing us with the means to show the general public what we do, 24 hours a day, seven days a week, and 365 days a year. You have shown us that we should speak up and tell our stories on how we provide clean drinking water and how we treat wastewater before returning it to the environment.
Sincerely,
Peter Baranyai
Director of Utilities
City of East Chicago, Ind.
Question on Sound Levels
In regard to your article, “Turbines Stand Tall” (WSO, May/June), I want to point out a mistake in the discussions of noise output. The article says the wind turbines produce 89 dB at 18 feet and at residences 120 feet away noise problems were resolved. A couple of things:
• Probably, the author meant, “A-weighted sound level,” denoted as dBA.
• I assume the 89 dBA value is for one turbine, and best case is if the data is for four turbines operating simultaneously. If so, assuming turbine noise is a point source, no ground acoustical reflection, wind not toward the residences, no temperature inversions and no intervening hills, trees or other objects, the sound level at the residences would be about 72 dBA for one turbine. If we add up all four, we get an energy average of 78 dBA.
• Either 72 dBA or 78 dBA is far above most common residential noise codes, which are 65 dBA day and 55 dBA night. Some codes are even more restrictive.
So it is puzzling to say that the problems were “resolved,” unless the residents accept relatively loud sound levels.
Richard J. Peppin, P.E., P.Eng.
President
Scantek, Inc. Sound and Vibration Instrumentation and Engineering
Columbia, Md.
