Air Quality Section
INFORMATION BULLETIN: TILSTON AIR QUALITY
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.)
Background
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
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
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
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
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
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.
»
view
the report as a downloadable PDF file
Drinking Water 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 concerning this
Bulletin, please contact:
Bernie Chrisp, Regional Director
Park-West Region
Manitoba Conservation
tel: (204) 726-6565
fax: (204) 726-6567
e-mail:bchrisp@gov.mb.ca
September, 2000
______________________
Additional information about Air Quality in Manitoba can be
obtained from:
» Manitoba Conservation Air
Quality Section, (204) 945-7100
» Conservation &
Environment Library On-line
Database
Manitoba Conservation Air Quality Section © 2002
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