Health hazard evaluation report: U. S. Army Corps of Engineers Libby Dam Project, Libby, Montana.
NIOSH, 1999 Apr. :1-17
The U.S. Army Corps of Engineers requested that NIOSH conduct a health hazard evaluation at the Libby Dam project in Libby, Montana. The management and employees of this hydroelectric powerhouse were concerned about low frequency noise exposures to the employees working in the facility. A site visit was conducted by a NIOSH investigator on May 20-21, 1998, where area and personal noise measurements were obtained. The audiometric examinations of the employees were also provided to the NIOSH investigator for analysis. The full-shift, personal noise exposure measurements collected from five Libby Dam employees did not exceed any OSHA criteria for noise. The NIOSH criterion was equaled in two of the five samples. The area sound measurements revealed a predominant sound energy in the 125 Hz third-octave band that is most likely the result of the generation and distribution of electricity. No intense sound energy was measured in the very low (less than 20 Hz) frequency range. There was some indication that structure-borne vibrational energy may be perceived by workers, particularly those who sit in front of computers at a desk. The analysis of the audiometric data collected from the employees showed that the hearing testing program was extremely variable, making it difficult to use these data to pin-point deficiencies in the hearing conservation program at this project.
Noise; Noise-levels; Vibration; Dosimetry; Audiometry;
Author Keywords: Electric Services; hydroelectric power plant; noise; structure-borne vibration;
dosimetry; spectral analysis; audiometry
Hazard Evaluation and Technical Assistance
National Institute for Occupational Safety and Health