Noise.pptx

Noise

NoiseUnwanted Sound: Sound in the wrong place and/or at wrong time.

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Sound & NoiseSound is a mechanical energy from a vibrating surface and is transmitted by cycling series of compressions and rarefactions of the molecules of the materials through which it passes.

The number of compressions and rarefactions of the air molecules in the unit of time is described as its frequency.

Frequency is expressed as hertz (Hz), which is the same as the number of cycles per second.

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Health effectsAnnoyanceInterference with communication Interference with sleepDepressionAural pain, nausea and reduced muscular controlIncreased heart RateSocial effectsEffect on social behavior Lowered Property ValueFlora and FaunaBird stop laying eggsBreeding of animals affectedPlant growth hampered

Sound & NoiseHuman ear does not respond linearly to increase in sound pressure, it is essentially logarithmic.

Human can detect sounds with frequencies ranging from about 20 to 20,000 Hz.

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NoiseThus noise measurements are expressed by the term sound pressure level (SPL),

SPL= Sound Pressure Level, dBP = sound pressure barP0 = reference pressure, 0.0002 bar

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Counting Decibels (dBA)Boom Car140Jet Takeoff140Shotgun130Rock Concert125Thunder Clap120Leaf Blower100Motorcycle 95Lawn Mower 90Traffic Noise 80Conversation 50Whisper 30Breathing 10Pain Threshold 125Hearing Loss Risk 100Very Annoying 90Intrusive 70Comfortable 60Very Quiet 30Just Audible 20

Noise Generally A weighted sound level scale is used. The scale is suitable as human ear doesn't respond to sounds of all frequencies, being less efficient in detecting sound at low and high frequencies than at medium or speech frequencies.To obtain a single number representing a sound level containing a wide range of frequencies and yet representative to the human responses, it is necessary to weight the low and high frequencies with respect to average, or A frequencies. Resultant SPL is A-weighted and the units are A-weighted decibels (dBA). The A-weighted sound level is also called noise levelSound level meters have A-weighing network, thus yielding A-weighted dB, or dBA readings.

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Larry W canter

Relative Response (dB)Frequency (Hz)31.2562.51252505001000200040008000dB(A)-39.4-26.2-16.1-8.6-3.201.21-1.1dB(B)-17-9-4-1000-1-3dB(C)-3-0.8-0.2000-0.2-0.8-3

Engineeringtoolbox.com

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Sound LevelsEquivalent Sound Level (Leq)It is the energy equivalent sound level, in decibels for any time period under consideration. It is the equivalent steady noise level that in a stated period of time, would contain the same noise energy as the time varying noise during the same period.

f is the fraction of time

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Problems

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Solution

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Leq

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Day-Night Average Sound Level (Ldn)Day-Night Average Sound Level (Ldn)It is the 24 average sound levels in decibel for the period of midnight to midnight, obtain after addition of 10 decibels to sound levels in the night from 10:00 pm to 6 amLdn = 10 log [ 0.667 (10(Ld/10) )+ 0.333 (10(Ln + 10)/10)]

Where:Ld = Leq for the daytime (0600-2200 hr) and Ln = Leq for the nighttime ( 2200-060 hr)

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Noise Pollution David H.F. Liu Howard C. Roberts




EIA methodology for noise impacts

Identification of noise impacts of proposed projectPreparation of description of existing noise environmental conditionProcurement of relevent noise standards and/or guidelinesNoise Impact PredictionAssessment of impact significanceIdentification and incorporation of mitigation measure

IDENTIFICATION OF NOISE IMPACTS OF PROPOSED PROJECT

DESCRIPTION OF EXISTING NOISE ENVIRONMENTAL CONDITION

Noise MonitoringThe monitoring schedulenormal daytime activities i.e. from 06:00am to 10:00pm And nighttime activities i.e. 10:00pm to 06:00am (at night). The locations covered for monitoring is a mix of all zones i.e.ResidentialCommercial Industrial The monitoring schedule carried out on all working days and one weekend to differentiate the noise levels between normal days to weekend days

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Place of the InstrumentThese are some important factors for doing monitoring: Away from facades Away from obstacles With the microphone 1.2 - 1.5 m above ground level.

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Construction NoiseThe Construction sector is of a significant size, employing as many workers as the sawmill and the heavy manufacturing sectors.

Currently 8% of all hearing loss claims are attributed to this sector.

Comparable to the heavy manufacturing group (next sector)

Road Equipment Noise Level MeasurementsConcrete Saw 95 dBA (7-hour sample)

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Road Equipment Noise Level MeasurementsJackhammering 102 dBA (7.5-hour sample)Source: OSHA case files

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Road Equipment Noise Level MeasurementsBreaking pavement 112 dBA (7-hour sample)Source: OSHA case files

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Road Equipment Noise Level Measurements

97 dBA (6.5-hour sample)104 dBA (7-hour sample)

Lateral drillingSource: OSHA case files

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Sample Noise Level Measurements

Source: OSHA case filesBridge Sandblasting 125 dBA (4-hour sample) 109 dBA (inside hood)

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Sample Noise Level MeasurementsSource: OSHA case filesDumping concrete 96 dBA (4-hour sample)

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NOISE MEASURMENT RESULTSS.No.LocationCategory of Area/ZoneLeq.- dB (A)StandardsDayNightDayNight1NQ 1Commercial68.864.765552NQ 2Industrial63.553.175703NQ 3Residential54.744.255454NQ 4Silence56.8843.35040

Noise Results

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PROCUREMENT OF RELEVENT NOISE STANDARDS AND/OR GUIDELINES

NATIONAL AMBIENT NOISE LEVEL STANDARDSNoise Regulation Rule 2000 under sector 3 of Environmental Protection Act 1986Area Code Category of Area/ZoneLimits in dB (A) LeqDay Time Night Time (A)Industrial 75 70 (B) Commercial 65 55 (C )Residential 55 45 (D) Silence 50 40

Daytime: 6:00am to 10:00pm Night time: 10:00pm to 6:00am Silence Zone is an area comprising not less than 100 m around Hospital, Educational Institution, Courts, Religious places or any other area, which is declared as such by the competent authority. Mixed categories of areas may be declared as one of the four above mentioned categories by the competent authority. No Firecracker and Loudspeaker between 10:00 pm to 6:00 am

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Environmental Standards (Vehicles)Category of Vehicles Maximum Permissible Noise Level Two wheelers (Petrol driven) 80 dB (A)

All passengers cars, all Petrol driven three- wheelers and diesel driven two wheelers 82 dB (A) Passenger or Light Commercial Vehicles including three wheelers vehicles fitted with diesel engine with gross vehicles weight upto 4000 kgs. 85 dB (A) Passenger or Commercial Vehicles with gross vehicles weight above 4000 kgs and upto 12000 kgs 89 dB (A) Passenger or Commercial Vehicles with gross vehicles weight above 12000 kgs. 91 dB (A)

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EquipmentNoise Limit dB (A)Window Air Conditioner68Air Cooler60Diesel Generators85-90Compactors (rollers), Front Loaders, Concrete Mixers, Cranes, Vibrators & Saws75

NOISE LIMITS FOR EQUIPMENTS AT CONSTRUCTION STAGE

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Generators Up to 1000 KVA, 75 dB(A) at 1 meter from the enclosure surface. A) Noise Standards for DG sets (15-500 KVA)The total sound power level of a DG set should be less than 94+10 log10 (KVA), dB(A), at the manufacturing stage, where, KVA is the nominal power rating of a DG set.This level should fall by 5 dB(A) every five years, till 2007, i.e. in 2002 and then in 2007.

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STANADARDS AND GUIDELINES FOR CONTROL OF NOISE POLLUTION FROM STATIONARY DIESEL GENERATOR (DG) SETS

( (B) Mandatory acoustic enclosure/acoustic treatment of room for stationary DG sets (5 KVA and above)Noise from the DG set should be controlled by providing an acoustic enclosure on by treating the room acoustically.The acoustic enclosure/acoustic treatment of the room should be designed for minimum 25 dB(A) Insertion Loss or for meeting the ambient noise standards, whichever is on the higher sideThe DG set should also be provided with proper exhaust muffler with Insertion Loss of minimum 25 dB(A).(C) Guidelines for the manufacturers/users of DG sets 5 KVA and above)1 The manufacturer should offer to the user a standard acoustic enclosure of 25 dB(A) Insertion Loss and also a suitable exhaust muffler with Insertion Loss of 25 dB(A).

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OSHA Exposure Limits

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NOISE IMPACT PREDICTION

Noise Level with Speed

Typical Noise Level with Increase in Population Density

Leq PredictionLeq = 42.3 + 10.2 log (Vc+6 Vt) -13.9 log D + 0.13SLeq= energy equivalent of sound level during one hour, dBAVc= Volume of four tires automobile, veh/hVt= Volume of six or more tires automobiles, veh/hD = Distance from edge to receiver, mS = Average speed of traffic during one hour, km/h

ASSESSMENT OF IMPACT SIGNIFICANCE

Professional judgement: Case StudyDraw Noise contour mapOverlay on topographical mapDetermine the environmental sensitivity.Whether sensitive receptors, silence zone, Whether activity is permitted or provide mitigation measures or alternatives

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IDENTIFICATION AND INCORPORATION OF MITIGATION MEASURES

The city of Ames, Iowa, began operation of three automated horn warning systems (AHS) in September of 1998. These systems were installed after nearby residents repeatedly expressed concerns over the disturbance created by the loud train horns.

The automated horn system provides a similar audible warning to motorists and pedestrians by using two stationary horns mounted at the crossing. Each horn directs its sound toward the approaching roadway. The horn system is activated using the same track signal circuitry as the gate arms and bells located at the crossing.

Rail Noise: A Case Study

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Sound Level

Train Horn

AHS Horn

Reduction

(dBA)

Area (acres)

Area (acres)

> 70

265

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86%

> 80

171

5

97%

> 90

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< 1

98%

Train Horn Noise Reduction

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Intersection of railroad with North Dakota Avenue:A graphical depiction of the reductionBefore

70 dBA

80 dBA

90 dBA

70 dBA

80 dBA90 dBA

After

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Ames Train Horn Noise Survey

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CONSTRUCTION PHASE Construction stage causes an increase in ambient noise levels within 200 m due to traffic movement and construction equipments.

Heavy construction activity should be preferred during the daytime, considering the habitations are present in vicinity of the project site.

Directing trucks to less noise-sensitive routesHearing protection- Earplugs are provided to those working very close to the noise generating machinery.

Noise Reduction- Strict codes for construction is implemented; where unnecessary, noise generating activity such as honking is avoided wherever possible.

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Noise Control MethodsSubstitute with quieter process or equipment:

Replacing a large jackhammer with a middle range one reduced the noise level by 10 dBA.

New, quieter generators have sound-proofing and produce only 75 dBA at 1 meter and 65 dBA at 7 meters under load.

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Noise control methodsInstall silencers/mufflersRetrofit old equipmentOperate equipment as designed per manufacturers instructionsDamp noisy equipment and partsinstall sound-absorbing materialMaintain equipment properlyreplace worn, loose, or unbalanced machine parts that cause vibrationkeep machine parts well lubricated to reduce frictionadjust belts and valves, tighten boltsEliminate or minimize noise at the source:

Acoustically treated operator cabins on earth-moving equipment have noise levels of 75 dBA or below.

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Noise control measures

Noise enclosuresNoise barriersmust be higher and wider than noise source to work effectivelymay be simple walls or curtains of acoustic materials -inch plywood can provide a 10dB noise reductionplace close to noise sourceInclude acoustic panels or baffles to walls/ceilingsMinimize leaks and openingse.g., cover joints with 1/8-inch thick neoprene strip or duct tapeIsolate/enclose the process or operator:A portable screen set up around a power pack reduced the noise level from 98 to 90 dBA at 1 meter.

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Noise control measuresIsolating or enclosing noisy equipment with operatorThis method will reduce noise levels outside the barrier, but may increase noise levels inside the barrier.

if the source of noise is equipment operated by a worker, his or her noise exposure may be increased because of reflected noise.

Lining the barrier with sound absorbing material will reduce the reflected noise to operator.

Reflected NoiseNoise from sourceBARRIERTransmittedNoise

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Other Noise Control MeasuresLimit time exposed: job rotation, rescheduling work

Limit use of noisy equipment

Provide breaks away from the noisy area

Turn off equipment not in useChange employee work practices:

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Operation phase

OPERATIONAL PHASE

Implementation of engineering noise control measures by industries:Provision of acoustic enclosures for machinery. Provision of greenbelt by each industryReducing structure borne transmission by isolation of the source using resilient mountings.Damping of vibrating metal structures or by replacement with materials such as wood.Placing attenuating screens between the operations and the source.Servicing Air conditioning systems regularly as per manufacturers guidance, to ensure that noise emissions are low.

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Operation PhaseAcoustics enclosure for the DG sets will be provided in the Power Generator as per MoEF notification.Strict adherence to maintenance schedule of generators, as specified by vendors.Anti honking sign boards will be placed in the parking areas and on entry and exit points.Use of specific road surfaces that reduce noise.Provision & maintenance of Greenbelt at site.

Noise Control of Machinery

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HIGHWAYSNoise control measures for roads or highways include construction of barriers to obstruct or dissipate sound emissions elevated or depressed highways : provides differences in grade, thus shielding traffic noise and reducing noise levels on adjacent propertiesabsorption effects of landscaping (trees, bushes and shrubs), important factors include the relative height of the barrier, the noise source affected area horizontal distances between the source and the barrier and between the barrier and the noise affected area.

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Noise Barriers

Earthern Berm BarrierWooden BarrierConcrete BarrierPVC BarrierGlass Barrier

Outdoor Noise Abatement measuresConditions:Noise- L10 dBAFour Lane Highway5000 Veh/h85 kmph5 % trucks

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Road Surfaces

Thin surfacingsPorous elastic surfaceAsphalt Rubber Concrete

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Noise Control Measures

Rubber Surfaces on inter locking blocks

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Pavement Cross section

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Railway Crossings

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Noise contours around an airport calculated using INM (Integrated Noise Modeling) based on previous noise measurements

55 - 60 dB = Light blue60 - 70 dB = Dark blue70 - 75 dB = Red75 - 80 dB = Green80 - 85 dB = Yellow> 85 dB = Pink Airport Noise

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Airport Noise

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Noise Components in Form 1-A5.5. Will there be significant increase in traffic noise & vibrations? Give details of the sources and the measures proposed for mitigation of the above. 5.6. What will be the impact of DG sets & other equipment on noise levels & vibration in & ambient air quality around the project site? Provide details.

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TOR

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Noise.pptx