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

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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 <strong>80</strong>
EIA & RA STUDY FOR NAPHTHA SPLITTER PROJECT AT NUMALIGARH REFINERY LIMITEDBaseline Environmental Status3.9.4 Sources of NoiseThe main sources of noise in existing NRL complex are the machines and equipmentswithin different process units and other off-site facilities and utilities. Major noise sourcesare GTG, Air Compressors, Feed Pumps, ID Fans, Cooling Towers, FD Fans, etc. Toevaluate the noise generated by different equipments, noise level measurements werecarried out near the major sources, in all the four directions i.e. north, south, east and westduring day and night periods. The average value of all the evaluations has been reportedin day and night periods.The movement of vehicles inside NRL complex also contribute to ambient noise levels. Anumber of heavy vehicles are operating every day within marketing terminal and along NH-39 which is a very busy highway, located just near the refinery complex.3.9.5 Existing Ambient Noise LevelTo evaluate the ambient noise level of major noise sources inside NRL complex, a studywas carried out during the study period from December 2007 to February 2008. The noiselevels were measured at a distance of 3 metres from major sources. An Integrated SoundLevel Meter was used in all the measurements. The measurements were carried outcontinuously, at hourly intervals, for the 24-hour period to obtain hourly sound pressurelevel. From these values, Leq values for day time, night time and 24-hour period werecalculated. The sampling locations are presented at Plate- 3.9.Table - 3.46DETAILS OF NOISE SAMPLING LOCATIONSLocation Code Description of sampling locationsDistance Directionw.r. to NRLNS1 Main Gate- Refinery - -NS2 Crude Distillation Unit (CDU) - -NS3 Hydrogen Plant (H 2 U) - -NS4 HCU - -NS5 SRU - -NS6 Captive Power Plant (CPP) - -NS7 Bishnupur 1.0 km WNS8 Rong Bong 2.0 km WSWNS9 Numaligarh Town 8.0 km NWNS10 Khumtai 3.5 km NENS11 Pura Bangla 7.0 km ESENS12 Lattakoojan 2.0 km SProjects & Development India Limited, Sindri Page 71 of <strong>80</strong>
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Chapter-III(59-80) - Pollution Control Board, Assam

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