Chapter-III(59-80) - Pollution Control Board, Assam

EIA & RA STUDY FOR NAPHTHA SPLITTER PROJECT AT NUMALIGARH REFINERY LIMITEDBaseline Environmental StatusThe damage risk criteria for hearing, enforced by the U.S. Occupational Safety and HealthAdministration to reduce hearing loss, are as follows:Maximum allowableduration/day, hoursTable - 3.45Damage Risk CriteriaNoise level, dB(A)(slow Response)8 906 924 953 972 1001.5 1021 1050.5 1100.25 or less 115Any community noise exposure comparable to those shown above is clearly unacceptableand constitutes a community health hazard. In community noise exposure, annoyance andphysiological damage can occur at much lower noise levels. For example, sleepinterference begins to occur at around 45 dB(A). Adverse community response andcomplaints start at around 70 dB(A) level. However, noise levels up to 65 dB(A) aregenerally acceptable and continued exposure to higher noise levels may cause hearingloss, leading to hearing handicap and deafness. In most cases, hearing loss is caused bya gradual shifting of threshold of hearing due to repeated exposure to noise. Backgroundnoise in the environment may interrupt speech communication, may cause awakeningfrom sleep, can keep one from falling asleep and can also affect the quality of sleep.3.9.3 Monitoring Methodology & Baseline Environmental StatusThe objective of ambient noise monitoring around NRL complex was to assess the backgroundnoise levels due to existing refinery operations and impact of noise from proposedNS project on human settlements in the study area. Methodology involved in datageneration of noise level may be summarized as under:• Identification and characterization of noise sources within NRL complex• Identification and characterization of noise sources around NRL complex in the studyarea• Measurement of noise level of different equipments of different plants within NRLcomplex including boundary area.Projects & Development India Limited, Sindri Page 70 of 80