June 18, 2007

Intensive probe fails to determine cause of H2S odour incident

An investigation by the Alberta Energy and Utilities Board (EUB) into a series of odour complaints in the Drayton Valley in mid-January has failed to determine the cause of the incident. The agency has documented the events and actions taken to address the problem in a public report.

From late January 14 to mid-morning on January 15, 2007, the EUB's Drayton Valley field centre received 49 complaints of sporadic hydrogen sulfide (H2S) odours west of Drayton Valley and north of Lodgepole over an area of about 48 square kilometres.

The highest peak reading of H2S (i.e. the highest level recorded by an EUB air monitoring unit over a 15-minute period) during the incident was 170 parts per billion or 0.17 parts per million (ppm). Alberta's occupational exposure limit is ten ppm over eight hours. The report emphasizes that at no time during the incident was public safety adversely affected.

Following the initial complaint call and for the next three days, the EUB deployed its Drayton Valley field centre personnel and resources and enlisted the assistance of ten local energy companies in the area in an effort to determine the source of the odour. All sour gas facilities in the search area were inspected by ground, by air, or both. Equipment utilized in the detection effort included three helicopters equipped for emission detection, a fixed-wing aircraft, stationary air monitoring units (AMU's), five mobile AMU's, snow machines, and a portable meteorological tower.

Although a few minor maintenance issues were discoverd at remote locations during the search and promptly addressed, these were not considered to be the source of the odours. In addition to the ground and air search, the EUB conducted a comprehensive investigation and records search, also without success.

During the search, the EUB established communication links for notification and status updates with Emergency Management Alberta, Alberta Environment, the town of Drayton Valley, local health facilities and agencies, local and regional authorities, local and provincial media and the animal health investigator, as well as any area resident who registered a complaint or concern with the EUB Field Centre.

Despite all efforts, the source of the emissions was never found. In its report, the EUB has expressed its appreciation for the support received from industry, other government officials, the local authorities, and the public.

For the future, the Board has made plans to intensify monitoring and inspections in the general area south and west of the town of Drayton Valley and will continue to watch for anomalies while carrying out its regular duties.

The incident report may be viewed on-line at www.eub.ca/docs/documents/reports/IR_20070522_DraytonValleyOdour.pdf.

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