Informational Notices:

Informational Bulletin - Tilston Air Quality

Manitoba Conservation

September 2000

Over the last several years, concerns have been raised by some residents of the Tilston area about potential outdoor air quality issues arising from oil and gas activity in the area. This matter has received considerable attention both in the Tilston area and more broadly. Manitoba Conservation has been active in addressing these concerns as part of its mandate to foster an oil and gas industry as well as to ensure environmental protection to all Manitobans. This information bulletin has been prepared to inform interested parties about air quality (and other environmental) monitoring that was undertaken over the period from 1998 to 2000 in the Tilston area. It is also being distributed more broadly within the oil-producing area of southwestern Manitoba. More detailed reports on the air quality monitoring data and the vegetation and soil monitoring survey are available on request. (See contact information at end of this bulletin.)


Tilston is a small community in the south-west corner of Manitoba located about 100 km south-west of Brandon and about 5 km from the province of Saskatchewan. Since 1997 some residents in the Tilston area, who live near an oil battery north-west of Tilston (8-8-6-29 W.P.M.), have expressed concerns about local air quality. They believe that emissions from oil and gas production and the flaring of produced gas associated with oil extraction have affected their health and that of their livestock.

Oil was discovered in the Tilston area in 1952. Production from oil pools in the area increased dramatically with the introduction of horizontal drilling in 1993. The 8-8-6-29 W.P.M. battery is located about 8 km northwest of the community of Tilston. This battery was built in 1985 to process crude oil from the wells and has been operated by Tundra Oil and Gas Ltd. since 1992. Natural gas separated from the oil is burned as fuel in the treater and excess gas is burned at an incinerator (or flare stack under upset conditions). The battery has an alarm and shutdown system to alert the company and shut down the battery in the event of operational problems.

Figure 1. Oil Pump Well

Figure 1. Oil pump well

The gas burned at the battery is a mixture of methane, ethane and other hydrocarbon components, as well as nitrogen, carbon dioxide and hydrogen sulphide. The presence of hydrogen sulphide, which smells like rotten eggs, makes even minor emissions from the battery easy to detect. Potential sources of emissions that have been identified in the past include the loading and transportation of oil from the battery, routine battery repairs and modifications, minor equipment malfunctions, and tank venting. The produced gas in the Tilston area contains about 13.5% hydrogen sulphide.

In addition to the oil battery at 8-8-6-29 W.P.M., the environmental practices and performance of other batteries in the Tilston area have recently been questioned. Operators of these batteries have also undertaken modifications recently to reduce their emissions.

Air Quality Monitoring

In order to evaluate local air quality, Manitoba Conservation conducted environmental air quality monitoring from July 1998 to June 2000 in the vicinity of the oil battery located at 8-8-6-29 W.P.M. The initial program of one sulphur dioxide monitor was expanded in April 1999 when two trailers fitted with state-of-the-art air quality analyzers were located in the vicinity of the battery. The first trailer was located in a farm yard about 1600 m to the southeast of the oil battery; the second trailer was located by an oil well about 400 m to the east of the battery.

The substances chosen for the environmental monitoring reflected those anticipated to be released by oil and gas industry production and flaring activities (e.g., sulphur dioxide, hydrogen sulphide, various hydrocarbons, etc.). The monitoring results were compared with existing air quality guidelines, where available, or levels encountered in other areas of Manitoba to assess the "acceptability" of the results.

Figure 2. Air monitoring trailer at oil pump well

Figure 2. Air monitoring trailer at oil pump well

The hydrogen sulphide monitoring program, which had run for about a year, detected levels of hydrogen sulphide near or above the hourly ambient air quality guideline of 11 parts per billion (ppb) on an infrequent basis (16 hours over 13 months) at the two monitoring sites. Two-thirds of these elevated levels were recorded during August 1999 at the site closest to the 8-8-6-29 W.P.M. battery. [Note: 1 part per billion is equivalent to 1 drop in 4,000 barrels of water.]

Figure 3. Air monitoring trailer at farm yard site

Figure 3. Air monitoring trailer at farm yard site

At these and lower levels of hydrogen sulphide, it may still have been possible for local residents to smell this air pollutant. The air quality guideline for hydrogen sulphide protects against annoyance from odours and is much lower than levels at which health effects such as eye or throat irritation are reported in the published literature (e.g., 1,000 to 2,000 ppb).

Figure 4. Monitoring equipment in trailer at farm yard site

Figure 4. Monitoring equipment in trailer at farm yard site

Monitoring of sulphur dioxide had taken place over about 22 months. Sulphur dioxide was usually only detected at very low levels in the area on infrequent occasions. The only exception was four hours in August 1998 when the hourly air quality objective of 340 ppb was exceeded.

Figure 5. Canister for collecting VOC samples

Figure 5. Canister for collecting VOC samples

Samples of air were taken once a week in the Tilston area for the measurement of the various hydrocarbons such as volatile organic compounds (VOC's) (e.g., chloromethane, toluene, ethane, etc.) and aldehydes and ketones. The levels measured were substantially less than any available guidelines (i.e., at least fifty to millions of times less than the guidelines). The levels of these hydrocarbons were also within the range of levels measured in Winnipeg.

Overall, the air quality monitoring program has shown that the air quality in the Tilston area is good, most of the time. The level of air pollutants detected in the outdoor air in the Tilston area have met the air quality guidelines, except on some infrequent occasions. (The goal is to have air quality within guidelines at all times.)

Most recently (between February and June 2000), only two hours with hydrogen sulphide levels above its guideline were observed. On the basis of the air quality monitoring, air quality dispersion modeling conducted to date and continuous improvements at the 8-8-6-29 W.P.M. battery (and others in the area), it is believed that air quality has improved and should continue to be within air quality guidelines almost all of the time. It is expected that during those infrequent occasions when the guidelines may not be met, the odour of hydrogen sulphide will probably be detectable but its concentration should be far below levels causing health effects.

Vegetation and Soil Monitoring

Manitoba Conservation conducted a vegetation and soil monitoring program in the vicinity of the 8-8-6-29 W.P.M. oil battery during the summer of 1999. The study was designed to determine if sulphur compounds, released from oil processing at the battery, were affecting the local vegetation or soils. During the study, plants in the vicinity of the battery at 8-8-6-29 W.P.M. were examined for visible signs of injury and the sulphur content of vegetation and soils was tested.

The study concluded that the cause of injured or unhealthy plants in the area, was fungal or other disease; there was no visible sulphur dioxide injury. The sulphur content in aspen leaves and soils tended to be slightly higher at some locations close to the battery, but there was no conclusive evidence that sulphur compound emissions were the cause.

Drinking Water and Monitoring

Concerns had been raised in early 1999 regarding potential problems with the quality of the drinking water in the Tilston area. Water samples were collected from four local private wells in June 1999; these samples were analyzed for bacteria and general chemical analysis. The levels found were generally consistent with ground water quality in the area, with some parameters slightly above the provincial guidelines. Homeowners were advised accordingly.

Human Health Effects

Manitoba Health has interviewed local residents and has undertaken a comprehensive review of the available published literature on health effects. In response to on-going health concerns of some members of the local community, Manitoba Health is re-assessing the issue. As part of this re-assessment, Manitoba Health contracted an occupational and environmental medicine specialist to undertake clinical assessments of concerned individuals in May 2000. A report on the findings is pending.

Livestock Health Effects

Veterinarians from Manitoba Agriculture and Food have responded to complaints from local farmers regarding the health of their livestock. Meetings have been held with the farmers and a local herd was inspected.

Manitoba Agriculture and Food, which has the expertise to investigate potential animal health effects, has indicated that it is willing to investigate further concerns of the local livestock producers, with their cooperation.

Community Advisory Group

A local Community Advisory Group (CAG) was established in order to benefit from local citizens' knowledge of the area and local air quality issues. The CAG has guided the development of the air quality monitoring program and has served as a forum to exchange information and discuss issues related to oil and gas environmental matters.

Summary  of Findings

The environmental monitoring that has been undertaken in the Tilston area has found that:

  • the air quality is good and should continue to be within air quality guidelines most of the time;
  • there was no visible sign of vegetation damage due to air pollutants; and
  • samples of well water were consistent with ground water quality in the area.

On-Going Efforts

Recognizing that some residents of the Tilston area still have concerns about air quality in the area and, in response to broader environmental issues relating to the oil and gas industry, Manitoba Conservation is undertaking a number of activities:

  • continue to administer the provisions of the Manitoba Oil and Gas Act; including responding to concerns and issues from local residents;
  • continue short-term monitoring in Virden and Pierson to further evaluate air quality in oil producing areas in southwestern Manitoba;
  • develop regulatory changes strengthening requirements governing gas flaring, venting and battery emissions under the Oil and Gas Act;
  • pursue opportunities to participate in a comprehensive Alberta-led Western Canada research study on the effects of gas flaring on livestock and human health;
  • participate in the national review and development of air quality objectives and guidelines that benefit from the most recent information and afford appropriate protection to human health and the environment;
  • track new information on issues associated with oil and gas emissions and potential substances released to the environment and their impact on the environment; and
  • investigate other potential localized sources of hydrogen sulphide emissions (e.g., sloughs).

For further information, please contact:

Bernie Chrisp, Regional Director
Park-West Region
Manitoba Conservation
Tel: 204-726-6565
Fax: 204-726-6567

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