April 2012, Vol. 239 No. 4

Features

Consider The Silent Treatment

Driven by public concerns, regulations and technology improvements, noise control in Alberta’s energy industry has evolved during the past four decades into one of the best in North America. Before the late 1960s, if you had a noise complaint against an energy firm in the Province you had to negotiate.

Then the first energy crisis spawned a proliferation of drilling, pumping and processing infrastructure across the western landscape, driving a push for regulation. “Initially it was pressure from landowners and residents,” said James Farquharson, principal of Calgary-based FDI Acoustics.

“The industry was driven from public concerns and complaints. To address the need for noise regulation, several years of consultations between the public and the province’s Energy Resources Conservation Board (ERCB) ensued. “It was an iterative process,” he recalled.

That process produced ERCB’s first noise control (interim) directive in 1973. It wasn’t perfect as complaints continued to rise. So the Environmental Council of Alberta took on an in-depth study culminating in a 1982 report calling for a serious overhaul and update. By 1988 the ERCB had a brand- new directive in place which was periodically reviewed. September 1999 saw major changes to guide complaint investigations, instrumentation and noise impact assessments (NIA).

The requirement for licensees to obtain NIAs for most projects kindled a new industry for the province: acoustic consultants. The need for sound professionals became clear, and Farquharson spotted an opportunity.

“I started in the business in 1989, and at that time you could count the number (of consultants) on your fingers,” he said. And it has blossomed from there. “Now I would say there are around 40.”

As a consultant, Farquharson participated in several regulatory reviews which kept pace with changes in public demand and technological advances, as well as the need to include not just nuisance noise, but environmental noise and health impacts too. The current directive, ERCB Directive 038, was issued in February 2007 and is seen by most jurisdictions as one of North America’s best.

ERCB Directive 038 attempts to take a balanced viewpoint – by considering the interests of both nearby residents and the licensee. Section 1.2.1 sums up the philosophy, “It does not guarantee that a resident will not hear noises from a facility; rather, it aims to not adversely affect indoor noise levels for residents near a facility.”

It states, “The directive sets permissible sound levels (PSL) 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.”

Professional acoustic consultants assist licensees in achieving approved PSLs. Ideally, consultants are enlisted at the design phase of a facility in order to ensure noise regulation compliance upon startup. Farquharson said they typically recommend particular types and models of pumps, fans, silencers, exhausts etc. to address the main sources of noise in field gas processing plants for example.

“With a gas plant you have the engine noise, powered by compressed natural gas,” he said. “And any time you compress gas, heat is generated, so that must be cooled.” Usually the plant is inside a building, for protection from the elements. “So hot air must be ducted out of the building, which involves a fan. For instance we look at low speed fans.”

The consultant also needs to maintain flexibility, Farquharson said.

“Often the licensee will come along and say they will be using a different type of equipment than originally specified in the scope of work and we then input the new piece of equipment and remove the old to see the impact on cumulative overall noise levels. It’s very much an iterative process.” This is why computer modeling is extensively employed. Sophisticated software allows the gauging of the effect of a new piece of equipment on the overall PSL.

Advances in measurement technology help. “We work with vibration analysts to detect individual component frequencies,” Farquharson said.

Acoustic consultants’ jobs don’t end with the design phase. Once a facility is up and running, the consultants may undertake a sound survey. “We use meters to detect sound levels at several locations around the plant,” he explained. “Not just at the property lines.”

Once compliance is demonstrated, continuous or periodic noise monitoring may be involved throughout a plant’s life. For this, advances in technology at the detection end have played a large role, but one of the most important new growth areas is in data transfer.

“Right now, unless there is good cell coverage, we store the data from a remote location and then take it back to the office for downloading,” Farquharson said. “Real time, with satellite transmission, is where the advances are coming. That will speed things up considerably.” It can clearly reduce site visit frequencies to once-a-year calibration and maintenance checks.

Where there’s good Internet connectivity, new Web-based systems are speeding the data process. Anywhere the Internet is available, all that’s needed is a standard computer to log onto. Together with cloud computing these Internet-based systems are enabling operators to increase their capacity and convenience without having to invest in new infrastructure and software.

It’s the hottest growth area. “The greatest advance within noise monitoring of oil and gas activities over the last five years has been remote access to the data,” said Gregory Bracci, business development manager Urban/Industrial at Brüel and Kjær EMS Inc.

“With this you can proactively manage the noise, responding to potential noise issues instantaneously. Systems now have the ability to send an e-mail or text message alert when a pre-determined threshold level is exceeded. Using the Internet, it is also possible to listen to what is going on at the site from anyplace in the world. In the past, without real-time access to the data you (could) only respond to issues that (had) already happened.”

At more remote sites, connectivity can still be a bottleneck.

“As with any advancement, there are setbacks along the way. Modem connectivity, especially in remote parts of the U.S. and Canada can cause data transfer problems,” Bracci said. “On some of the more remote sites, customers look to use Wi-Fi or a DSL connection for data transfer.”

As far as Bracci is concerned, what’s important going forward is continued improvements in data transfer. “In the future we see a need for even more detailed data to be available in real time,” he said. “This will help provide a more accurate representation of the noise impact of facilities.”

On the reduction aspect, noise control has advanced from simple barriers, insulation and retro-fitted equipment to new technology like re-designed fan blades and higher-speed compressor motors.

Noise cancellation technology, long used in the aviation industry and noise-reduction headsets, is now being applied in the energy industry as well.

“Component manufacturers are developing noise cancellation – the frequencies are detected and processed, and signals are generated that are 180 degrees out of phase with the noise, to effectively cancel it out,” Farquharson said. The technique is particularly effective on lower frequencies.

So what’s on the horizon? The ERCB said it isn’t looking to further update Directive 038 at this time. But ways continue to grow to meet its requirements through technology improvements. New ideas are presented and exchanged at the biannual Spring Noise Conference in Banff, hosted by the Alberta Acoustics & Noise Association, and initiated in 1993 by the ERCB.

Universities are at the cutting edge, too. The School of Mechanical Engineering at Indiana’s Purdue University, for example, is investigating “intelligent” noise-control devices that auto-adapt to changing conditions. Smart foams, adaptive engine mounts, and adaptive mufflers will further streamline sound control automation and help quieten the western countryside.

Author
Graham Chandler is an award-winning Calgary freelance writer with more thanr 400 published articles, mostly energy and technology-related.