Alberta Acoustics & Noise Association 2011 Spring Noise Conference

2011

Spring Noise Conference

May 24-27, 2011 Fairmont Banff Springs Hotel Banff, AB

buzz? what’s the

ACOUSTICS AND NEW TECHNOLOGIES

ENGINEERED SILENCE

3000 projects 20 years experience Unbiased acoustical consulting

KEEPING ALBERTA QUIET Leaders in noise ControL for industriaL appLiCations For more than 20 years, Patching Associates has been managing noise control challenges for industry, helping to ensure compliance with government regulations and managing community concerns.Whether a gas compressor, apartment building or highway project, Patching Associates can provide you with the right engineered solution. www.patchingassociates.com

Contents

O

n behalf of the Alberta Acoustics & Noise Association executive committee, I am very pleased to welcome all the participants to this, our 9th biennial noise conference. I am so proud of the people who have worked so hard to bring this conference to fruition. The goal of our conference has always been to offer knowledge that comes from the practical application of noise control and acoustical science to realworld situations. To this end, we have pioneered such things as the integration of fundamental acoustic education together with hands-on, front-line experience of people who deal with noise on a daily basis.

The topics covered in the conference range from workshops on both the fundamentals of acoustics and the application of noise regulations in Alberta, through to the latest noise measurement techniques. In between these pillars, we offer technical sessions on heavy industry, power generation, noise regulation and control, ecology, environment and wildlife, industrial and occupational noise. The goal of every session is to present information that is of use to the widest possible audience. We pride ourselves on minimizing the degree of impenetrable academic dissertation and maximizing the accessibility of information about the field of noise control and acoustics.

Every conference, in order not to take ourselves too seriously, we establish a theme that we can enjoy and relate to today’s noise control issues. Themes have run the gamut from “Noise Awareness: Supporting Sound Partnerships” to such unforgettable mottos as “Leave No Tone Unturned” and “For Whom the Decibel Tolls.” This year, our theme of “What’s the Buzz?: Innovations & Issues” reflects our desire to stay at the crest of current developments as well as to acknowledge our willingness to explore new issues that result from technological advances. Undoubtedly, we are one of the few conferences that can boast sessions on acoustic ecology, accompanied by a sound walk in the beautiful Rocky Mountains. In many ways, we strive to achieve a combination of the art and science of sound and noise.

After all one person’s music is another person’s noise.

New to the Spring Noise Conference this year is the vendor exhibition. It has already proven to be a success, and we look forward to having it again at the 2013 conference. The vendor exhibition allows our industry an opportunity to showcase acoustic services and products to all participants.

One measure of our continued success is the fact that our sponsor support is at the highest level it has ever been. The Alberta Acoustics & Noise Association is most appreciative of the generous support of our sponsors, which has allowed us to bring a conference to you that we believe will be the best yet.

A special thank you to JuneWarren-Nickle’s Energy Group, our media partner, for its guidance and support in putting together this conference show guide.

Finally, I’d like to take a moment to thank the 2011 Spring Noise Conference organizing committee for their countless volunteer hours to bring this conference together. Way to go, gang!

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Conference Agenda

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Sponsors

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Noise Timeline

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Wind Turbine Noise

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Noise Issues

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Acoustical Consultants

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Case Studies

Sincerely,

Daryl Caswell, PhD, P.Eng. Chair, 2011 Spring Noise Conference

2011 Spring Noise Conference Guide

Conference Chairman Daryl Caswell, PhD, P.Eng. Conference Coordinator Jessie Roy Managing Editor Robin Himes Published by JuneWarren-Nickle’s Energy Group Publisher Agnes Zalewski Senior Graphic Designer Birdeen Selzer

Alberta Acoustics & Noise Association Board of Directors

President Richard Patching TREASURER Jonathan Chui Director Jim Ulicki Director Don South Director James Farquharson

Contact

Alberta Acoustics & Noise Association Bankers Hall PO Box 22452 Calgary, AB T2P 5G7 info@springnoiseconference.com www.springnoiseconference.com

2011 Spring Noise Conference

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Conference Agenda

INCE Exams Time

Monday, May 23, 2011 Exam Room 1

Exam Room 2

8:00 – 8:30

Registration

8:30 – 12:00

INCE Fundamentals Exam Preparation

12:00 – 13:00

Lunch

13:00 – 16:30

INCE Fundamentals Exam

INCE Board Certification Exam Part 1 INCE Board Certification Exam Part 2

Conference Schedule Time

Wednesday, May 25

Thursday, May 26

Technical Session Room 1 Technical Session Room 2

Technical Session Room 1

7:30 – 8:00

Registration

Registration

8:00 – 8:30

Opening Remarks

Opening Remarks

8:30 – 9:15

Plenary Speaker 1: Dr. Poppy Crum

Plenary Speaker 3: Dr. Geoff Leventhall

9:15 – 10:00

Plenary Speaker 2: George C. Maling, Jr.

Plenary Speaker 4: Erwin Hartog van Banda

10:00 – 10:30

Coffee Break

Coffee Break

10:30 – 12:00

Heavy Industry Noise

12:00 – 12:30

Lunch Speaker 1: Colin Davison

Lunch Speaker 2: Dave Keenan

12:30 – 13:30

Lunch

Lunch

13:30 – 15:00

Heavy Industry Noise

15:00 – 15:30

Coffee Break

15:30 – 17:00

Noise Regulations, Standards & Policies

Evening Activity

Wine & Cheese Reception

Student Papers

Ecology, Environment & Wildlife

Industrial & Occupational Noise

Noise Regulations, Standards & Policies Coffee Break

Noise Modeling & Measurement Techniques

Community, Public Health & Education Banff Centre Tour

Plenary Schedule Speaker

Presentation Title

Dr. Poppy Crum

To Be Announced

George C. Maling, Jr.

International Activities Related to Noise Source Emissions

Dr. Geoff Leventhall

Low Frequency Noise: Wind Turbines and Other Sources

Erwin Hartog van Banda

From Europe With Noise

Dr. Lily Wang

The Effects of Building Mechanical System Noise with Tones or Time-Varying Fluctuations on Human Performance and Perception

Dr. Malcolm Smith

Prediction Methodologies for Vibration and Structure Borne Noise

Lunch Speakers Lunch Speaker

Presentation Title

Colin Davison

Oil & Gas Exploration Challenges: Drilling Deeper and Closer to the Community

Dave Keenan

How Bad is The Buzz: Tools & Techniques

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Alberta Acoustics & Noise Association

Conference Agenda

Workshop Schedule Tuesday, May 24, 2011 Time

Ivor Petrak Room Alhambra Ballroom

7:30 – 8:30

Registration

8:30 – 12:00

Basic Acoustics 1 Practical Understanding & Application of Noise Regulations Hearing Conservation 1

12:00 – 13:00

Lunch

13:00 – 16:30

Basic Acoustics 2 Practical Understanding & Application of Noise Regulations Hearing Conservation 2

Strathcona Room

Evening Activity Sound Ride

Friday, May 27 Technical Session Room 2

Technical Session Room 1

Technical Session Room 2

Registration Opening Remarks Plenary Speaker 5: Dr. Lily Wang Plenary Speaker 6: Dr. Malcolm Smith Coffee Break Power Generation Noise

Architectural Acoustics

Transportation, Infrastructure & Manufacturing

Closing Remarks

Vibration & Low Frequency Noise Noise measurement technology has advanced rapidly.

Vibration & Low Frequency Noise

Presentation Topic Community, Public Health & Education Noise Regulations, Standards & Policies Vibration & Low Frequency Noise Noise Regulations, Standards & Policies Architectural Photo: BrÜel & Kjær A/S Denmark

Noise Modeling & Measurement Techniques

Presentation Topic Heavy Industry Noise Industrial & Occupational Noise

2011 Spring Noise Conference

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Sponsors

Partner

Platinum

Gold

Silver

Bronze

Thank you to the following companies for listing the 2011 Spring Noise Conference: Pipeline & Gas Journal magazine, JuneWarren-Nickle’s Energy Group, European Acoustics Association, The Institute of Noise Control Engineering of the USA, SVcommunity.com - The Sound & Vibration Site, Canadian Architect magazine, Canadian Consulting Engineer magazine, Brüel & Kjær Sound & Vibration, Measurement A/S North America & International, ISNetworld, NaturalResource.ca, Canadian Interiors magazine, Acoustics.org, The Association of Professional Engineers, Geologists and Geophysicists of Alberta, The International Institute of Acoustics and Vibration (IIAV), National Institute of Advanced Industrial Science and Technology (AIST)-Japan, Building magazine, Société Française d’Acoustique, Akustik Danişmanlik, Canadian Acoustical Association, International Commission for Acoustics, Banff & Lake Louise Tourism.

A special thank you to DGMR Consulting Engineers for sponsoring plenary speaker Erwin Hartog van Banda and to ISVR Consulting for sponsoring plenary speaker Dr. Malcolm Smith.

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Alberta Acoustics & Noise Association

Noise Timeline

July 1982: Environmental Council of Alberta issues a study, Report and Recommendations on Noise in Alberta, which recognized the need for a definitive noise policy and identified the deficiencies in the existing noise control Interim Directive ID 73-1.

1984: Noise Standards Review Committee initiated by the ERCB to investigate technical, social and enforcement issues associated with noise control regulation.

1990

1988: ERCB publishes a new noise control directive (ID 88-1) and accompanying guide.

August 1994: The ERCB issues ID 94-4, superseding ID 92-2. ID 94-4 viewed noise from a receptor viewpoint, rather than considering sound levels at the property line.

It also provides for seasonal adjustments to permissible sound levels, provides guidelines for developing sound models, incorporates new guidelines and regulations covering low frequency noise, offers guidelines for the development of noise management plans, recognizes wind turbines as potential sources of noise and sets out appropriate monitoring criteria.

January 2008: The EUB realigns into two separate regulatory bodies: the ERCB, which regulates the energy industry, and the Alberta Utilities Commission (AUC), which regulates the utilities industry.

1995: The Alberta Energy and Utilities Board (EUB) combines the ERCB and the Public Utilities Board.

2010

2000

September 1999: EUB issues ID 99-8, superseding ID 94-4 and reflecting many significant changes in the structure and format of the directive.

Areas of change include new requirements and proto­ cols for noise impact assessments, new provisions for complaint investigations, guidelines with respect to calibration and certification of noise measurement instrumentation, guidelines pertaining to attenuation of construction noise, recognition of unique challenges in certain areas, such as those designated heavy industrial areas which may contain noise making facilities not subject to EUB regulation, and additional details pertaining to what constitutes “major” and “minor” noncompliance events.

As with previous Interim Directives, Directive 038 attempts to take a balanced viewpoint by considering the interests of both the nearby residents and the oil and gas industry. It does not guarantee that a resident will not hear noises from a facility; rather, it aims to not adversely affect indoor noise levels. The directive sets permissible sound levels for outdoor noise, taking into consideration that the attenuation of noise through the walls of a dwelling should decrease the indoor sound levels to where normal sleep patterns are not disturbed.

March 2009: The AUC implements Rule 012, which originated from Directive 038, to regulate the noise issues under its jurisdiction, including noise emitted from the construction and operation of electric and natural gas utility facilities. Several updates and amendments to Rule 012 follow over the next 18 months.

March 2009: BC Oil & Gas Commission releases British Columbia Noise Control Best Practices Guideline. The guideline outlines the requirements for noise control as they apply to operations, production facilities and gas processing plants under the jurisdiction of the BC Oil & Gas Commission and provides background information and guidance regarding noise management.

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Source: David C. DeGagne, Energy Resources Conservation Board, Alberta Acoustics & Noise Association

July 1986: Noise Standards Review Committee releases its draft report of recommended guidelines.

April 1992: First review of the 1988 noise directive results in a revised directive, ID 92-2.

February 2007: Directive 038 is issued by the EUB, which provides requirements for noise control as they apply to all operations and facilities under the jurisdiction of the EUB. The requirements address environmental noise, not health-related impacts, such as noise induced hearing loss. Alberta Human Resources and Employment regulates matters related to occupational noise guidelines. Non-energy facility noise issues are the jurisdiction of Alberta Environment or the local municipality.

1980

1973: Energy Resources Conservation Board (ERCB) publishes a noise control Interim Directive (ID 73-1) for the energy industry. As the energy industry and the population of Alberta steadily grew, the impact of encroachment by or towards energy industry facilities presented unique challenges. Noise was becoming one of the main concerns identified by the public and it was clear that the simplistic approach taken by the early noise control directives would not suffice.

1970

Finding quiet

A compact history of noise regulation in western Canada

Wind Turbine Noise

Hearing the power of the wind Listening to grey giants

By Sherrie Todd-Beshore

A

s society seeks the most efficient sources of green energy for the 21st century and forward, ramping up wind power just as we harnessed water energy has created both scientific excitement and environmental concerns.

The noise emitted by turbine blades moving through air generally falls within the 35-45 decibel (dBA) level as measured from 300 metres (984 feet) from the source (per the National Research Council, or NRC). The NRC reported that from a single turbine at its source, the measured noise levels were 90-105 dB. Since we’re not likely to shimmy to the top of a 90-metre (300-foot) tubular steel tower and spacing minimums set residential dwellings at specified distances (500 metres or more, depending on tower size and design), industry standards work diligently to maintain the decibel level at or below human conversation, which is typically 55 dBA. Public relations and community input has become as much of a factor in the work we do as the physics and the mathematics, says mechanical engineer Brian Howe, M.Eng., MBA, P.Eng. of Ontario.

“The broadband noise radiated from the moving rotor blade is a combination of boundary layer noise and trailing edge noise. The aerodynamic interference of the rotor blades and the tower is minimal as the tower scatters sound,” says Werner Richarz, PhD, P.Eng. “Upstream observers appear to experience a small increase in sound pressure level, whereas observers downstream of the tower experience a drop in pressure level because the tower blocks the direct line of transmission from source.”

The rotating diameter of the giant blades can be 70 metres (230 feet) or more. The blades multiply the wind’s force, so even a gentle breeze is enough to make the outer edges of the blades turn around. If the blades rotate slowly, the inner axle and turbine still rotate with enough force to turn the generator to make electricity. On the flip side, the wind turbines have an automatic speed measuring device with a mechanism that locks the blades if the wind speed is too high.

“From our perspective,” Howe says, “further strides are to be made in reducing noise, stemming from design, materials and maintenance. In manufacturing, there are internal

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Alberta Acoustics & Noise Association

controls for balance and safety that you don’t see. But it’s always changing, with an eye to what can be improved.”

The turbine is just one of three main parts. The second part is a gearbox that converts the slow speed of the spinning blades into a higher speed rotary motion that turns the drive shaft quickly enough to power the electricity generator. And the generator is the third main part of a turbine that functions like an enormous, scaled-up version of a dynamo for a bicycle lamp.

Turbines used in wind farms for the commercial production of electricity usually have three blades, with tip speeds of over 320 kilometres per hour at high efficiency.

“From a distance, the turbine blades look slow and graceful,” offers Dr. Richarz. “But if you were sitting on the tips of the blades, you would be in for a fast ride.”

The blades are usually coloured a light grey to blend in with the clouds and can range in length from 20 to 40 metres or more. Designed to exploit the wind energy that exists naturally at specific locations, modeling is used to determine spacing, optimum tower height, control systems, number of blades and blade shape.

However, regardless of the sleek design and the simplest and most efficient internal moving parts, those parts are moving and they leave a distinctive noise signature.

The audible “swish, swish, swish” of the blade sweep area

“Further strides are to be made in reducing noise, stemming from design, materials and maintenance.”

— Brian Howe, Mechanical Engineer

merges with the low frequency driveshaft noise, the turbine motor and the wind noise to create a complex mix of noises that must be dealt with by the developer.

A typical turbine at a wind generating facility is capable of generating about a megawatt of electricity, which is enough to run 500 electric toasters simultaneously. But because wind turbines don’t generate anywhere near as much energy as a conventional power plant, it takes a farm of them, and the largest farms in Canada incorporate more than 100 turbines, with the turbine towers set in various patterns in various spacings, partly with a view to minimizing noise disturbances associated with that many turbines in a relatively small space.

“Visually, the preference is for minimal interference as much as possible,” Howe says. “And once each tower is in place, the actual footprint and spacing allows for resumed crop planting and harvesting, or normal grazing.”

Noise Issues

Environmental and Occupational Noise Issues in Alberta Why are they linked? nmenta Enviro lN ois e

Regulatory ERCB AUC Alberta Transportation NEB CEAA/Health Canada

Cumulative Effects Natural sounds Regulated industry Non-regulated industry Transportation Community activities

Consequences Complaints Compliance issues Interveners Community relations

Affected Parties Stakeholders Industry Consultants Manufacturers

Design Optimization Noise enclosure, silencers, barrier Management control PPE and signage Acoustic prediction modeling

Source: Jonathan Chui, P.Eng. INCE and Teresa A. Drew, B.Sc., INCE

Acoustic guarantees 85 dBA at 1m (is not a panacea) Tonality Low frequency noise/vibration

Cumulative Effects Multiple equipment Indoor acoustics Reflecting surfaces

Regulatory Alberta OHS Code Canada Labour Code

Consequences

Affected Parties Workers Industry Consultants Manufacturers

pational N Occu o i se

Equipment Performance

Hearing impairment Productivity Liability

2011 Spring Noise Conference

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Acoustical Consultants

Acoustical consultants turn down the volume at Alberta industrial installations

revolution

By Darrell Stonehouse

N

oise from industrial installations like gas plants and compressor stations has long been a source of conflict between Alberta landowners and the energy industry.

Solving the noise control challenge has led to the rise of a new industry in the province over the last 40 years, with acoustical consultants and manufacturers of equipment and materials working to silence the ongoing confrontation between industry and affected residents.

“In the 1960s, there was one person in the province doing noise consulting,” explains Les Frank, M.S., P.Eng., P.E., an acoustical engineering consultant who began working on finding solutions to industrial noise in Alberta in 1976.

“In the 1970s, there were two. Since then it has grown around thirtyfold to fortyfold in the last 35 years. Contractors and suppliers have been growing too, and they even have more people on board than the consultants.”

Frank says regulators have driven the growth in demand for acoustical consulting in Alberta and consultants have responded by developing a host of technologies to measure and model noise, and to design solutions. He credits government for responding to public demands to manage industrial noise.

The Energy Resources Conservation Board (ERCB) first instituted noise regulations for oil and gas facilities in 1973.

Those regulations were replaced with a more comprehensive directive from the ERCB in 1988, which was most recently updated in 2007.

“Much of the early work in the sector was complaint driven and was largely focused on compressor stations and gas plants,” says James Farquharson, who began noise consulting in 1989. “A farmer would complain to the board and the company would follow up with an investigation,” he explains. “So the industry started as complaint driven and then has grown towards design.”

Changes in natural gas development throughout the 1990s and the new century added to the need for noise consultants, says Farquharson. As gas fields matured across the province and reservoir pressure dropped, smaller field compressors began dotting the countryside, many of which brought on concerns about noise.

The next phase of gas development, coalbed methane, also acted as a driver for growth.

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Alberta Acoustics & Noise Association

With industry continually encroaching on rural residents, noise concerns have expanded to cover other field equipment. Farquharson says companies have worked on mitigating noise from pumpjacks and even drilling rigs.

Alberta’s strict noise control regulations have made the province a leader in acoustical consulting and in manufacturing noise control equipment.

“We have people call us from other jurisdictions in North America looking for the expertise developed here,” he explains. “American companies come here for expertise.

ERCB legislation is looked at all over the world.”

As an example of just how good a job the combination of ERCB regulations and the industry have done in solving noise control issues, Frank points to multinational petrochemical officials who recently visited a world-scale ethylene facility in the province.

“Their first reaction was, ‘why is it so quiet?’” he says.

New technologies have played a major role in helping consultants measure and mitigate noise at energy facilities.

“For the public, noise is subjective,” Frank says. “But for us, it is totally objective. It’s a numbers game, and we’re like accountants. The numbers are what they are and we compare them to the regulations. Sometimes the numbers are lower than the regulations and the landowner is upset. Sometimes they are high, but they are happy with the results.”

Frank says as technology has advanced, industry and public perception of the noise consulting industry has changed.

“We think we have proven noise consulting is a science and not an art,” he explains. “We’ve proven noise can be predicted, noise controls can be designed and solutions can be costestimated. We have had successes, and industry engineers who design facilities now know noise control can be designed.”

Frank says advances in measuring instrumentation are improving the data used by the industry to design noise management plans.

“The new instruments can do amazing things and five years from now they will be vastly different again,” he says.

“They will provide a lot more data and that gives engineers more tools to work with.”

Farquharson agrees there’s been a generational change in the sound meters used in the field.

In recent years there has been rapid growth in the community of companies providing noise consulting and mitigation services to industry in Alberta.

Photo: KINETICS Noise Control

“They have faster processors and they’re handheld for convenience,” he notes. “That’s made them more costeffective and they have improved accuracy.”

He credits the advent of computer noise modeling as another major improvement in managing noise.

“This business is very math intensive, so the advent of computers and software has really advanced the business.”

Frank agrees. “The models are now extremely detailed and accurate,” he explains, pointing to a model for a refinery with as many as 800-1,000 noise sources as an example of how detailed the models have become. “We have good predictive capabilities.”

The new information technologies have helped make noise management cost effective for energy companies, says Farquharson. “Prices have decreased or stayed the same over time, even though the costs of staffing have increased,” he comments. “The technologies have brought costs down because what used to take us 50 hours, we can now do in half the time.”

While strides have been made in shielding western Canadians from the encroaching noises of the oil and gas industry, there have been major advances on the commercial and residential front as well. The field of building acoustics now takes in the properties of a particular space not just for the purposes of noise control, but also for sound reinforcement and clarity.

“Noise suppression is a large factor in the design of tunnels, sound walls, multi-family residential units, and structures like schools, offices, banks, hotels and restaurants,” says Clifford Faszer, P.Eng. “We recommend thicker walls for multi-family dwellings, hospitals and hotels that have a damping layer in the middle.”

Attention to other details like clamping systems for plumbing to prevent pipes from vibrating can make a significant difference to the level of ambient noise, especially in a hotel where many people take their showers at about the same time. Most people can work or sleep with a certain level of noise that the brain can actually tune out, but any sounds above the normal level of typical conversation (about 55 decibels) creates work and study distractions as well as sleep disruption, Faszer says.

And it’s in this area, he adds, that computer model­ ing has been particularly helpful for consultants and contractors.

“Really, for noise control technology, the evolution of sophisticated computer software that’s available now has been a major valuable tool,” says Faszer. “With the modeling, we can demonstrate that we have the ability to zero in on problem areas and show clients how our proposed noise solutions work.”

Another significant driving force in the growth of the noise consulting business in Alberta has been the biennial Spring Noise Conference, hosted by the Alberta Acoustics & Noise Association. Initiated by the ERCB in 1993 to foster a better understanding of ERCB noise regulation and its application, the event has grown to showcase new innovations in noise control and noise control management technologies.

“The conference now attracts both attendees and presenters from outside of the Calgary area. Many come to learn about Alberta’s leading-edge regulations and technology,” says Farquharson.

“It’s a mature industry, but there is still room for growth.”

2011 Spring Noise Conference

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Case Study - Wind

Rising wind

Noise modeling for wind turbines helps predict cumulative effects of wind farms

By Pascal Everton, P.Eng. and Richard Wright, P.Eng.

A

proponent of a wind turbine power generation project in southern Alberta needed to conduct a Noise Impact Assessment (NIA) to fulfill its regulatory obligations and ensure the Permissible Sound Levels at nearby residences were not exceeded.

When the project was first envisioned in 2004, there were few other neighbouring wind turbine projects to be included in a cumulative effects assessment. However, since 2004, several other proponents have either proposed or built wind turbine projects that have effectively surrounded the original project.

In the application to the Alberta Utilities Commission under Rule 007, a cumulative effects assessment to include all the neighbouring wind turbine projects according to Rule 012 had become necessary to ensure that the Permissible Sound Levels were not exceeded at the nearby residences.

In order to properly complete the cumulative effects assessment, data for all the neighbouring wind turbine projects (turbine locations, hub heights, sound power levels, modes of operation, etc.) was required.

As all the projects were competing for the same limited transmission capacity, direct sharing of data among the competitive projects was not granted. As a result, only publicly available data from regulatory applications could be used.

Fortunately, the applications for most neighbouring wind projects contained enough information that a complete computer model of the entire area, including all wind turbines, nearby residences and detailed ground elevation data, could be constructed. The sound sources included 20 proposed turbines for the client, 64 existing or recently in-service wind turbines and 97 proposed wind turbines for another neighbouring project. As well, four proposed or existing electrical substations were included in the noise model.

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Alberta Acoustics & Noise Association

The model was built using the CadnaA software package, as developed by DataKustik GmbH in Germany. The model was run using the ISO 9613 Standard, which accounts for downwind conditions, as required by the regulator.

However, the use of ISO 9613 provides very conservative predictions, as the Standard assumes downwind sound propagation toward each residence from each sound source.

In practice, since the sound sources are scattered over a large area, this condition is unrealistic at nearby residences as the wind can only blow in a single direction at any given time. This conservative assumption provides the regulator with a high degree of confidence that the actual installation is likely to achieve compliance with its regulations if the predicted sound levels meet the Permissible Sound Levels.

The neighbouring proposed project had a noise management strategy that reduced the power levels at night in order to meet the nighttime Permissible Sound Levels at all nearby residences. Even before the addition of the 20 proposed wind turbines for the client’s project, there was very little acoustical space at some residences.

Using the contributions from the neighbouring wind turbine projects as a starting point, several iterations were required to locate the client’s 20 turbines and remain in compliance with all applicable regulations. Those regulations included citing considerations beyond just noise, which placed additional constraints on the potential locations of the turbines.

In summary, with a good predictive model, cumulative effects of noise can be determined. By including all wind turbine projects that can potentially affect residential locations, compliance with noise regulations can be assured, allowing all potential projects to proceed.

Noise modeling helps developers mitigate the impact of wind farms on nearby residents.

Case Study - Transportation

Creating spaces Transportation noise mitigation structures can actually improve the visual aesthetics of a community

By Neil Morozumi, P.Eng., and Michael Thompson, P.Eng.

W

hen many people see noise barriers alongside a roadway, the first thing that might come to mind is that the homes behind the barrier are being subjected to a noisy environment.

It is true that the primary purpose of a noise barrier is to mitigate the noise received at a home to a level that has been deemed acceptable by the local governmental body, but there are also many other considerations that designers should take into account when incorporating a noise barrier into the design of a roadway.

From a purely technical perspective, considerations include noise reduction by taking advantage of geometry, access to buried utilities, safety concerns, snow clearing, space availability and so forth.

At many public consultation sessions, we hear comments from the affected residents that noise barriers are ugly, they are imposing and they make people feel claustrophobic. We also hear concerns about the shadows that are created and their effect on the growth of flower beds and gardens, particularly given Calgary’s short growing season.

We have found that these are typical issues that are most often brought forth when a barrier is designed close to residences. In the simplest terms, a noise barrier functions by forcing sound to bend over the top of the barrier. In this regard, it is generally most effective when a barrier is located either very close to the receiver or very close to the source.

Placing the barrier at the resident’s property line is the most common practice, mainly due to the technical constraints previously mentioned. Sometimes, however, when all of the technical needs are met, the designer is afforded a bit more freedom to make use of a noise barrier to truly improve the community that it is designed to protect.

A good example of thoughtful barrier design can be seen in GE5 (Glenmore Trail/Elbow Drive/Fifth Street), one of the City of Calgary’s largest interchange projects.

The roadway design depressed Glenmore Trail up to nine metres below the existing crossing road at Elbow Drive.

To accommodate the six-lane depressed expressway, four bridges were constructed, along with 13,000 square metres of retaining wall structures. Over 500,000 cubic metres of soil were excavated, requiring the relocation of major existing utilities including fibre-optic trunk lines, high-pressure gas, sanitary, storm, water and electrical distribution.

Paramount to the project’s success was the integration of the new expressway into the existing community. Extensive communication was conducted with a stakeholders representative committee, which included community and business representatives from the area.

The committee participated in the selection of the style and colours of the new noise barriers and was heavily involved in the design of a new linear park. The park not only serves as a transition from the community to the new expressway, but also provides a relaxing environment for a regional pathway connecting active modes of transportation, such as walking and cycling, between communities, and a new pedestrian bridge crossing the expressway.

Noise barriers can be designed so they integrate better with adjacent communities.

Photo: Roy Ooms/LightWorks Photography

Ultimately, the noise barriers not only provide a required technical function, but they also provide a key community function defining the road environment and the community environment.

The GE5 project is an excellent example of how, when properly integrated into a project, noise barriers can help create a space that the City and the local communities are very proud of.

2011 Spring Noise Conference

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Case Study - Vibration

The right vibe

Modeling vibration expectations in a building renovation

By Russ Lewis, M.Eng., P.Eng.

L

aboratories house a variety of highly vibration-sensitive equipment used for research and production in fields such as metrology, biotechnology, medicine and micro/optoelectronics, in which activities require environments with vibration levels well below human perception thresholds.

The impacts of external vibration sources, including road and rail traffic and construction, are best controlled through good site selection. Internal sources, such as walking, building services and other lab equipment, can be addressed by structural design (for example, floors with adequate natural frequencies, stiffness and mass), proper location of sensitive uses within the lab, and the isolation of building services and vibrating lab equipment.

Evaluating external vibration sources in relation to the location of a building site is an important basic design consideration. A comprehensive vibration survey is an essential element of site selection.

Reduce your risk with sound advice

In this case study, involving the expansion and renovation of an existing university research building, the consulting team assessed vibration effects from a nearby railway and determined the ability of portions of the existing building to support the proposed research equipment.

Assessment The vibration survey captured typical vibration levels from both interior and exterior sources. Exterior sources included trains and vehicular traffic. Interior sources included ambient footfalls and mechanical equipment, as well as staged footfall activity. The primary source of concern was train traffic.

Vibration transmission is highly dependent on subsoil conditions. Ground transmission was assessed by simultaneously measuring train pass-bys at multiple distances from the tracks. Differences between vibration levels just outside and just inside the existing foundation were measured and used to develop a vibration prediction model for extrapolation of results.

The vibration caused by the local train traffic is expected to reach 2,000 μin/s (VC-A) inside the building nearest the tracks on a regular basis, with levels occasionally exceeding 4,000 μin/s (ISO Operating Theater).

However, areas within the building at further distances from the tracks (and slab-on-grade) benefit from the additional distance and screening provided by the intervening building mass. Much lower vibration levels were measured in some areas.

Staged footfall activity consisted of heel drops to determine the fundamental frequency of the floor and then walking at various speeds (including matching a sub-harmonic of the natural floor frequency) through the center of the structural bay.

Conclusions

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14

Alberta Acoustics & Noise Association

Assessment of the duration and frequency of train traffic indicated that the south wing could house equipment requiring 250 μin/s (VC-D), while the north wing could house equipment requiring from 125 μin/s (VC-E) to 500 μin/s (VC-C) depending upon specific location—provided that research measurements were short in duration and could be repeated if impacted by train passes. For proposed research that requires long durations, cannot be repeated and cannot tolerate occasional exceedances of 4,000 μin/s (ISO Operating Theater), mitigation measures including foundation isolation, slab-on-grade isolation, upper-floor slab isolation and equipment isolation tables are indicated.

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