EARTHWORKS

Noise Resources

General Information on how humans perceive noise

There are some key concepts and facts that will help readers better understand noise:

What is sound?
Noise is often defined as unwanted sound. Sound is defined as any pressure variation heard by the human ear. The sound pressure level (SPL) is a measure of the air vibrations that make up sound. Because the human ear is sensitive to a wide range of pressure levels, the SPL is measured on a logarithmic scale with units of decibels (dB).

How do humans perceive sound?
Healthy human ears perceive pressure variations over a wide range of frequencies -- from low frequencies of 20 Hz to frequencies as high as 20,000 Hz. In terms of sound pressure levels, the human ear's range starts at the threshold of hearing (0 dB) and ends at the threshold of pain (around 140 dB).

The human ear is less sensitive to sounds in the low frequencies compared to the higher frequencies. For example, a 50 Hz (low frequency) tone must be at a level of 85 dB in order to be perceived by the listener as being the same loudness as the higher frequency 1000-Hz tone at a level of 70 dB.

How is sound quantified?
As mentioned above, sound levels are usually measured and expressed in decibels (dB). Most environmental noise does not consist of a single frequency, but rather a broad band of frequencies differing in sound level. The intensities of each frequency add to generate sound. The method commonly used to quantify environmental sounds involves evaluating all of the frequencies of a sound according to a weighting system which reflects that human hearing is less sensitive at low frequencies and extremely high frequencies than at the mid-range frequencies. This is called "A" weighting, and the decibel level measured is called the A-weighted sound level (dBA).

As a rule of thumb, a doubling in the loudness of the sound occurs with every increase of 10 dB in sound pressure. In other words, for most individuals a 60 dBA noise would sound twice as loud as a 50 dBA noise.

How Sound Travels
Sound is caused by changes in air pressure. For example, when a mallet strikes a drum the drumhead begins to move back and forth (vibrate). As the drumhead moves down, air is pulled toward it, and as the head bounces back up it pushes air away. This creates changes in air pressure that move (or propagate) away from the drum, eventually striking our eardrum. These changes in pressure are known as sound waves.

There are a number of factors that affect the propagation of sound. The most important include: distance from source; obstacles such as barriers and buildings; atmospheric absorption;wind direction and speed; temperature and temperature gradient; humidity; precipitation;reflections; and ground absorption.[1]

It is important to understand that noise does not always decrease as one moves away from a noise source. The above factors can work to increase or decrease noise levels. For example, at short distances (up to 160 feet) the wind has a minor influence on the measured sound level.

At distances greater than 1,000 feet from a noise source, noise can become louder on the downwind side by as much as 20 dB, while on the upwind side levels can drop by 20 dB (depending on wind speed and distance).[2]

Other things to consider include the fact that while barriers may act to reduce high frequency sounds, low frequency sounds are difficult to reduce using obstacles or barriers. Additionally, while soft ground surfaces and the atmosphere are effective at absorbing mid-frequency and high frequency noise, these factors do not tend to reduce low frequency noise to the same degree. This means that as one moves away from the source, low frequencies often become much more prominent.[3]

All noise is not equally annoying
Not all noise has the same effect on humans, nor do all humans react in the same way to noise stimuli. Certain noise characteristics can greatly increase the annoyance factor and the potential health impacts associated with noise. In addition to the sound pressure level, these factors include: 1) difference between the new noise and the prior ambient noise environment; 2) the presence tonal noise; 3) low frequency noise; 4) fluctuating, intermittent or periodic sounds; and 5) impulsive sounds.

Noise from oil and gas operations

Noise from oil and gas development comes from a number of sources: truck traffic, drilling and completion activities, well pumps and compressors. For some landowners, noise from oil and gas operations is so loud or of such a different sound quality that it makes them feel as if they are living in an industrial zone.

 

Van Staverans
Noise from wells and compressors led the Van Staverans to move from their home.

For people who live in rural areas, the arrival of a new, industrial noise source can greatly disturb the natural environmental soundscape. Gail and Al Van Staveran were so greatly affected by the noise of nearby wells and compressors that they were driven away from their home.

 

Landowners often complain about noise levels associated with natural gas compressors. The noise level varies with the size of the compressor and distance from the compressor; and it changes with shifts in wind direction and intensity. According to the Powder River Basin Resource Council, "Depending on the wind direction, the roar of a field compressor can be heard three to four miles from the site. Near the compressor stations, people need to shout to make themselves heard over the sound of the engines."

One Wyoming landowner has described compressor noise in this way:

Now comes the second phase. The dreadful noise generated by a nearby large compressor station. Noise that was so loud that our dog was too frightened to go outside to do his business without a lot of coaxing. Noise that sounds like a jet plane circling over your house for 24 hours a day. Noise that is constant. Noise that drives people to the breaking point. My neighbor called the sheriff, state officials and even the governor and was told nothing could be done about the noise. Like I said, the noise drives people to the breaking point, and my neighbor fired 17 rifle shots toward the station.
--Excerpted from CBM Destroys Retirement Dream.

How loud is oil and gas noise?

A study in La Plata County, Colorado, reported noise levels for a number of oil and gas activities:[4]

 

Typical compressor station 50 dBA (375 feet from property boundary)
Pumping units 50 dBA (325 feet from well pad)
Fuel and water trucks 68 dBA (500 feet from source)
Crane for hoisting rigs 68 dBA (500 feet from source)
Concrete pump used during drilling 62 dBA (500 feet from source)
Average well construction site 65 dBA (500 feet from source)

 

The Bureau of Land Management (BLM) published different numbers. At 50 feet from the source, the measured noise levels were: well drilling - 83dBA; pump jack operations - 82 dBA; produced water injection facilities - 71 dBA; and gas compressor facilities - 89 dBA.[5]

In the same study, BLM also reported typical noise levels from construction equipment and oil and gas activity. These are presented in the chart below. Again, the sound levels were taken at a distance of 50 feet (15 meters). Estimates of noise attenuation at distances greater than 50 feet can be made by reducing noise levels by a factor of 6 dBA (A-weighted sound levels) for each doubling of distance. The actual noise levels experienced by a receptor, however, will depend on the distance between the receptor and the equipment, the topography, vegetation, and meteorological conditions (e.g., wind speed and direction, temperature, humidity).

Equipment Noise from Oil and Gas.  Source:  BLM.

Noise levels reported by the Bureau of Land Management. See endnote [5]

Rationale for a 45 dBA (or lower) residential noise standard

In many residential neighborhoods, especially low density and rural areas, the nighttime noise level is very quiet. According to a Colorado-Based noise consultant, ambient noise levels in residential areas are frequently as low as 35 dBA during the nighttime, and are occasionally lower [6]. In these situations, if oil and gas facilities are allowed to emit noise at 45 dBA, the noise will be perceived by many as being twice as loud as the ambient noise in the area. In Alberta, Canada, it has been estimated that the ambient rural noise level is 35 dBA at night.

Noise standards of 45 dBA LEQ (nighttime) or lower are used in many jurisdictions that have oil and gas operations.

There are several jurisdictions that require oil and gas operators to meet a 45 decibel level during the night-time, in residential areas. Typically, noise measurements are taken outside, at a certain distance from or at the property line of the receiver (e.g., a house, hospital, etc.). These are called "receptor-based" noise standards. In some cases, noise measurements are taken a certain distance from the noise source ("source-based" standards). In 2005, Colorado amended its noise rule from a "receptor-based" to a "source-based" standard, requiring noise measurements to be taken 350 feet from the oil and gas noise source.

Alberta, Canada: Alberta is a major oil and natural gas producing province in Canada. In Alberta, the Energy and Utilities Board has the responsibility for regulating noise from oil and gas operations. The EUB has produced what may be the most comprehensive noise regulations for the oil and gas industry across North America. The EUB essentially has a sliding scale noise standard whereby acceptable noise levels vary with the ambient noise. For example, if a citizen lives in an area where ambient noise is low (e.g., where housing density and traffic noise are low), then the oil and gas operator must ensure that noise reaching the receptor is no louder than 40 dBA. In some instances, if the ambient noise is very low (e.g., 30 dBA), companies may be required to mitigate noise to even lower levels (e.g., 35 dBA).

As ambient noise conditions increase, the allowable noise level increases. The highest allowable level in a residential neighborhood is 56 dBA at night. This noise level applies when there are more than 160 dwellings in a quarter-mile radius, and there is a major traffic source (road, rail, air) within 30 m (90 feet) of any of the dwellings.

World Bank: For onshore well sites, the recommended maximum noise level is 55 dB(A) and 45 dB(A) for day and night, respectively (measured at receptors or the edges of a property boundary, on an average hourly basis). These levels apply to residential, educational and institutional areas. Noise abatement measures should achieve either the levels state above or a maximum increase in background levels of 3 decibels (measured on the A scale) [i.e., dBA].

Sacramento County, CA: Sacramento County is a significant producer of dry natural gas in California. In the county, the allowable noise level is 50 dBA L50 (daytime) and 45 dBA L50 (nighttime), measured at residential properties. This is according to the Noise Element Of The1993 County Of Sacramento General Plan.

City of Longbeach, CA: The allowable exterior noise level in many parts of the city is 45 dBA (nighttime), according to the Longbeach city ordinances. Oil and gas operations must meet this standard, except during drilling and well servicing.

Examples of residential noise requirements of 45 dBA for oil and gas operations

 

 

Measurement Location

Nighttime level (dBA)

World Bank - new oil and gas projects in residential areas At receptors or edge of property boundary 45

Alberta, Canada -

low traffic noise, low density housing

med. traffic, med. density

high traffic, high density

15 metres from a dwelling/receptor

40

45

56

Sacramento County, CA At residential property line 45
City of Longbeach, CA At residential property line 45
New Colorado Noise Rule 350 feet from noise source 45

 

45 dBA is achievable, even as close as 350 feet from the noise source

There are numerous examples that show that 40 - 45 dBA is achievable at 350 feet from the source. The City of Farmington, New Mexico uses "1 dBA over ambient" as a standard for all wells constructed in the city. In January of 2005, OGAP staff conducted sound measurements at well sites in the City of Farmington. Noise levels measured at 300 feet from the noise source varied from 39 to 49 dBA. It is estimated that if measurements had been taken at 350, these sound levels would have been in the range of 37 to 47 dBA. For more information, please download the OGAP/SJCA submission to the COGCC.

It is not cost prohibitive to achieve 45 dBA at 350 from the noise source

As part of its submission to the Colorado OIl and Gas Conservation Commission noise rule hearing, OGAP prepared a chart of noise mitigation cost estimates for oil and gas facilities that have achieved the 40-45 dBA noise level.

Noise Mitigation Options

There are many proven ways of mitigating noise from oil and gas operations. One only has to look to regions that have fairly stringent noise regulations (e.g., Farmington, New Mexico, Alberta, Canad) to find excellent examples of noise mitigation. There are numerous acoustical or noise abatement companies that provide services to the oil and gas industry.

Noise from pumpjacks

A low-profile pumping unit can replace the conventional unit, which uses a 30- to 40-foot beam and looks like a giant, bobbing horse's head. The conventional pump is run on a gas- or diesel-powered engine, which is noisy and smelly. Alternatives to this large pump include using a pneumatic pumping device that doesn't require an engine, therefore, produces little or no noise. This pump stands about 10 to 15-feet tall. According to one company, pneumatic pumps will not function correctly if a lot of water is extracted while extracting methane gas. Consequently, when larger amounts of water are produced, an alterative to the standard beam pump is the progressive cavity pump. These pumps come in different shapes and sizes, and like the pneumatic pump, they can run on electric motors, and therefore, be much quieter than conventional pumps.

Vehicle Noise

Noise created by operators constantly driving in and out from the well pad to monitor well production can be mitigated using an automated monitoring system, which allows wells to be monitored remotely, e.g., from the company's office. Vehicle noise may also be controlled to some extent by limiting the hours that industry employees use residential roads for accessing wells (e.g., limiting vehicles to the hours of 7:00 a.m. to 9:00 p.m., except in emergency situations).

Engine noise

To mitigate noise impacts from engines, sound barriers made out steel and sound-absorbing insulation (i.e., NOT styrofoam) may be used. Sound barriers may be placed in an L-shape above the engine, and they extend past the sides of the engine. To reduce noise in sensitive areas, pumpjacks, engines, or well-site or field compressors may be entirely enclosed in a sound-insulated building.

Some engines can operate at a constant number of revolutions per minute (RPM), which reduces the often annoying fluctuating noise caused by engines that speed up and slow down. Mufflers, like those used for automobile engines, can be used to minimize engine noise. In noise sensitive situations, hospital-grade mufflers used in series can be more effective at reducing noise from engines.

In some situations, natural gas or diesel engines can be replaced with electric motors. These motors, if properly installed, tend to be much less noisy than their engine counterparts. The use of electrical motors depends on the availability of electricity, and whether or not a company is willing to run an electrical line to the site.

Compressor noise

Noise from compressors can be mitigated most effectively by treating each significant oise source: gas turbines or engines, compressors, exhaust outlets and air inlets, and cooling and ventilation fans. Abatement may involve changing the blades on fans, which can change the frequency of sound emitted, thereby removing the annoying tones. Engine noise can be muffled using automotive-type mufflers, or by housing the engines in acoustically insulated structures. Also, the entire compressor can be housed in an acoustically insulated building.

Cost of Mitigation

Some oil and gas opearators refuse to apply noise mitigation to their sites, using the excuse that mitigation is too expensive. If noise mitigation measures are installed when the site is constructed, rather than attempting to abate the noise after the equipment is installed, the costs are much more affordable. OGAP has compiled some examples of the costs of mitigation.

Examples of companies providing noise mitigation services to oil and gas industry

Noise and its Effects on Human Health

There are adverse physical and mental effects from noise. For example, prolonged periods of exposure to 65 dBA can cause mental and bodily fatigue. Furthermore, noise can affect the quantity and quality of sleep; cause permanent hearing damage; contribute to the development or aggravation of heart and circulatory diseases;
and transform a person's initial annoyance into more extreme emotional responses and behavior.
[7]

According to the World Health Organization: [8]
Noise annoyance is a global phenomenon. A definition of annoyance is "a feeling of displeasure associated with any agent or ondition, known or believed by an individual or group to adversely affect them."

. . .apart from 'annoyance', people may feel a variety of negative emotions when
exposed to community noise, and may report anger, disappointment, dissatisfaction, withdrawal, helplessness, depression, anxiety, distraction, agitation, or exhaustion.

. . . Social and behavioural effects include changes in overt everyday behaviour patterns (e.g. closing windows, not using balconies, turning TV and radio to louder levels, writing petitions, complaining to authorities); adverse changes in social behaviour (e.g., aggression, unfriendliness, disengagement, non-participation); adverse changes in social indicators (e.g. residential mobility, hospital admissions, drug consumption, accident rates); and changes in mood (e.g. less happy, more depressed).

The World Health Organization also reports that "a large proportion of low-frequency components in noise may increase considerably the adverse effects on health." [9]

Health effects of low frequency noise

Unfortunately, many of the health effects of noise due to oil and gas operations have not been scientifically documented. The lack of scientific study does not mean, however, that noise issues related to oil and gas are insignificant. The loud, continuous noise during the drilling phase; the loud short-term noises from flaring or hydraulic fracturing; the intermittent whine of poorly maintained pump jacks and other equipment; and the loud or low frequency noise from compressors are common complaints related to oil and gas development. Numerous citizens have reported disruption of sleep and increased anxiety caused by noise from oil and gas developments.[10]

Noise and its Effects on Wildlife

Noise effects wildlife in a variety of different ways. It can cause the temporary or permanent displacement of animals and birds from particular areas. It can also have physiological effects that are detrimental to wildlife health.

The Draft Resource Management Plan for leasing federal lands in southern New Mexico states that in some cases, federally threatened and endangered wildlife species may be affected by elevated noise levels. For example:

In the final Environmental Impact Statement for the Jonah natural gas field, the BLM stated that:

It is likely that noise already has contributed to the apparent decrease in wildlife use on and adjacent to the Jonah Infill Drilling Project Area (JIDPA), with observed decreases in raptor nesting activity and productivity, male greater sage-grouse lek attendance and sage-grouse nesting within the JIDPA having been reported over the past several years. Data also suggest that noise may contribute to disturbance and/or departure of greater sage-grouse from area leks. [13]



For more information:

ENDNOTES

[1] Breul and Kjaer. 2000. Environmental Noise Handbook, pp. 16-22.

[2] McGregor, H. (Engineering Dynamics). 1998. Compression Facility Noise Guidelines for Colorado Oil and Gas Commission. p. 10; and Breul and Kjaer. 2000. p. 20. See endnote [1].

[3] Casella Stanger. 2001. Low Frequency Noise. (Technical research support for U.K.Department for Environment, Food and Rural Affairs Noise Programme). p. 4; and Breul and Kjaer. 2000. pp. 18 and 19. See endnote [1].

[4] La Plata County (Colorado). 2002. La Plata County Impact Report. pp. 3-98.

[5] Bureau of Land Management. Oct.2000. Draft RMPA/EIS for Federal Fluid Minerals Leasing and Development in Sierra and Otero Counties. Page 4-29.

[6] McGregor, H.N. (Engineering Dynamics, Inc., Englewood, CO). Propagation of Noise from Gas Compression Facilities Located in Mountainous Terrain. (COGCC Noise Stakeholder Meeting Handout.)

[7] Marsh, A. 1999. University of Western Australia, School of Architecture and Fine Arts. Cited in East of Huajatolla Citizens Alliance. Noise.

[8] Berglund, B., Lindvall, T. and Schwela, D. 1999. Guidelines for Community Noise. World Health Organization. p. 50.

[9] See endnote [8].

[10] Clarren, Rebecca. "Status quo reigns in New Mexico," High Country News. Sept. 25, 2000. p. 10.

[11] See endnote [5]. p. 2-9.

[12] See endnote [5]. p. 4-42.

[13] BLM. Jan. 2006. Final Environmental Impact Statement, Jonah Infill Drilling Project. Sublette County, WY. Chapter. 4. p. 4-48.

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