U p in northern Alberta, Syncrude Canada Ltd. has put in a sophisticated system that keeps tubs on
Air quality at the tar sands Ashok Kumar Syncrude Canada Ltd. Ednionton, Alberta T5J 3E5 Canada
Local fuel shortages and forecasts of rising energy prices are symptoms of the grolving scarcity of energy, in relation to other resources. However, development of the Athabasca T a r Sands in Canada is a step toward fulfilling energy needs of the future. The tar sands of Alberta are believed to be some 200 million years old, and contain nearly 600 billion barrels (bbl) of bitumen. The biggest and shallowest deposit occurs around the Syncrude plant, and, with today’s mining technology, could yield approximately 29 billion bbl of synthetic crude oil. Syncrude Canada Ltd. is a $2.14 billion venture which is expected to produce 129 000 bbl/d synthetic crude oil, a t its design capacity. Apart from large expenditures involved in building a plant of this size, environmental problems, such as those resulting from the emission of air contaminants, are anticipated. Potential air contaminants which are controlled include sulfur, particulates, hldrocarbons, carbon monoxide, and normal products of combustion. I n order to avoid adverse effects of these air contaminants on humans, vegetaFcwtirrr articles in ES&T hare by-lines, repthe i . i r i < . r o f r h e airrhmr, and are edired h \ , rhe Wathingron .x!afJ, ! f j , o u ore interested i i i cotrtrihirrirrg (in nrricle. conrnct the ninnaging cYlitrJr.
rc\rnt
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Environmental Science & Technology
On station. Moniroring or Synmtde tire
tion, and wild life in the area, Syncrude’s air quality monitoring consists primarily of the following interrelated activities: monitoring of baseline meteorological conditions 0 ambient air quality monitoring 0. continuous monitoring network 0 0 static air quality monitoring network 0. sulfur dustfall stations 0. biological air quality monitoring network 0 source-emissions monitoring. T h e basic idea behind air quality monitoring is to assure compliance with applicable provincial air quality
standards, to provide data for industrial research directed toward improving the air quality, and to assist in taking necessary measures for controlling air quality. Monitoring Meteorological data were collected for approximately five years before operations began in August 1978. These data formed the basis for selecting sites for air quality monitors, and were used to study the meteorological conditions that will be responsible for causing the permissible levels of concentrations of a particular pollutant to be exceeded. Current use of the data is to build computer models for simulating the atmospheric boundary layer, for the purpose of developing an air quality prediction system. Syncrude has established five continuous ambient air monitoring stations within 15 km of the main stack, in order to measure wind direction and speed, sulfur dioxide, and hydrogen sulfide. The monitors were sited in locations a t which a high probability of plume impingement existed during the period September 1974 through August 1975. T h e distances from the main stack, and the azimuths are given below: Azimuth Station
‘True
No.
North
I 2 3 4 5
I80 315 075 330 005
Distance from main stack (km)
5.5 6.5 3.5 14.5 1.0
0013-936X/79/0913-0650$01 .OO/O @ 1979 American Chemical Society
The locations of these stations are shown in Figure 1. Note that monitor sites are near places at which events were predicted to occur most frequently, but have been displaced outward, to avoid the tailings pond and mined-out areas. Each station consists of the following instruments: H2S and SO2 analyzers: Two T E C 0 4 3 SO2 analyzers and a T E C 0 3 4 0 H2S converter are used for measuring instantaneous concentrations of SO2 and H2S in the surrounding air. The T E C 0 4 3 SO2 analyzer employs a pulsed fluorescent technique to measure the concentration of S02. This instrument measures concentrations in the range of 0-5 ppm SO2 by volume. A T E C 0 4 3 SO2 analyzer and a T E C 0 3 4 0 H2S converter (an integrated unit) are used to measure H2S concentration. The concentration of H2S in the ambient air is determined by converting any H2S in the air into
S02, and then measuring the SOz. The concentration range of the analyzer is 0-0.5 ppm H2S by volume. Wind instrument: The wind instrument is a Windflo 540 system which measures the wind speed and wind direction continuously. The wind speed is measured by means of a rotating three-cup anemometer, while the wind direction is monitored by a direction vane. The instrument is mounted at the 40-ft level of the towers at stations I , 2, 4 and 5, and a t the 30-ft level a t station 3. The system is set up to measure speed in the range of 0-1 44 km/h. Calibration instrumentation: Two T E C O 102 diluters are used to perform an automatic daily check of the analytical instruments. Data acquisition and processing system (DAP): The DAP system (Figure 2) is a minicomputer-based system which communicates with the five remote stations via telemetry or land line. A P D P 11/05 computer is
used for processing of the data, while the mass storage of raw data is done by two “floppy disk” drives. Each station is designed to incorporate an NO, analyzer and a hydrocarbon HCB analyzer in the future. Network operation At one minute intervals, data on SO2 and H2S concentrations, and on wind direction and velocity are transmitted by radio telemetry or land line to a central station in the operations laboratory. At the central station, a minicomputer stores all incoming data on a “floppy disk” storage device. Each day the data are transferred to a computer for processing and storage on magnetic tape. The central station computer also calculates running half-hour averages for all the data coming from remote stations. Concentration data are compared against two levels-a violation level, and an alarm level which is about one-half of the violation level.
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651
Whenever the alarm level is reached, an alarm signal is transmitted to the central station, and the data are printed on a teletype. An “A” is printed with the parameter value to indicate the alarm condition, and a “V” if the higher limit is exceeded. The data may also be monitored on a C R T display located at the central station. The time, duration and severity of any excursion beyond permissible limits of SO2 or H2S can be established from the teletype printout, and would be reported to Alberta Environment within 72 hours, should such an incident occur. Monthly and yearly reports, in the form prescribed by Al-
berta Environment, will be prepared from the data on magnetic tapes, with the aid of the Edmonton computer.
Static air quality network The types of stations used to monitor static air quality are widely used as a practical method of measuring total sulfation and H2S concentrations in ambient air. This method gives a cumulative, rather than instantaneous, measure of air quality. It is intended to determine the relative sulfation from place to place, and to indicate longterm trends in pollution levels. A network of 40 stations (“candles”) was established between Fort McMurray
FIGURE I
Locations of 5 continuous am stations, and 40 static air qua (“candles”)
“Candles“ 1,2, and 36 are outside map area
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Environmental Science & Technology
and Fort MacKay, and has been in operation since May 1977. The locations of these stations are shown in Figure I . Station No. 1 is located at the No. 1 Fire Hall in Fort McMurray. Each station is made up of two cylinders-one for the lead peroxide method for total sulfation, and the other for the hydrogen sulfide, by means of zinc acetate. For protection from mechanical injury and precipitation, both cylinders are sheltered in a small box with a metal top and louvered sides. The cylinders are replaced monthly. Results from the analysis of these cylinders are included in the monthly report submitted to Alberta Environment.
Other monitoring Pending the approval of the Director of Standards and Approvals, Alberta Environment, four sulfur dustfall stations will be installed at locations around the sulfur storage area. These consist simply of an open container, mounted 1 to 2 m above the ground. At some future time, when the breaking of sulfur blocks, and sulfur shipment is imminent, four additional stations will be installed. Also, a study of possible long-term biological effects of low concentrations of pollutants on lichens has been undertaken by Syncrude. Since lichens are highly sensitive to air pollutants such as S02, they are capable of showing damage or reduced growth long before it is detectable in other vegetation. This project involves observations at regular intervals of a system of 56 permanent plots laid out in a symmetrical radiating pattern from the Syncrude plant site. This system utilizes two lichen species, Pnrmelia sulcata and Hypogymnia physodes, as indicators of vegetative responses to changes in air quality.
~-
~
FIGURE2
Data acquisition and processing (DAP)system
Floppy disk
Antenna
drives
Watchdog timer
High
alarm Annunciator
Master terminal unit (MTU) PDP 11105
~~
computer
Figure 3 is a plot showing the locations of 56 biological monitoring stations. Further details of this project are contained in Syncrude Environmental Research Monographs, 1976-2 and 1977-5.
Source emissions Emissions from the plant are determined regularly, and the following instruments have been installed a t the 92-m level of the main stack: for particulates, Lear Siegler Model RM41 Visible Emission Monitoring System for emission rate, volume flow rate and exit temperature, Western Research and Development CSEM System for S02. T h e purpose is to measure stack emission parameters such as SO2 concentration, particulate concentration, total gas volume flow rate and flue eas exit temoerature. A block diggram for th'e stack-gas monitoring system is given in Figure 4. SO2 concentrations will be measured a t one minute intervals. An analog computer will calculate SOzemission rates each minute, using the data on SO2 concentration, gas flow rate, and temperature. Data on all the above
FIGURE3
Biological air quality monitoring network 0
0
0
0
0
0 0
0
0
0
0
0 0
0
" Thickwood 0 initial study sites (11)
0Long term monitoring sites (54) L -I
0 km
McMurrav
16 km
Volume 13.Number 6, June 1979 653
EPA:
,
.
... . . .. .
.
FIGURE 4
right way,
Continuous stack gas monitoring system
t Main stack
Wt'Ong wait until state or local
Velocity data
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Environmental Science & Technology
parameters will be displayed in the main control room and in the operations laboratory (Environmental Section). A data acquisition and processing (DAP) system will verify that the parameters are within the range specified. I f not, the system will sound, alarms in the main control room. Data acquired by the DAP system will be transferred to the DAP support system which will generate operating reports, as required. For the purpose of sampling stack gases, four sampling ports have also been installed at the 92-m level of the main stack. These will also be used for periodic surveys to verify the calibration of instruments. A platform which can be reached by elevator or stairs has been provided at this stack level. A 4-m-long sampling probe, lined with stainless steel, will be used to remove the samples. Thus, Syncrude has installed the air quality monitoring network to ensure compliance with the law and to fulfill its commitment to minimize the effects of such a large development on air, land, water and people.
Additional reading Douglas, G. W., Skorepa, A. C., Monitoring Air Quality with Lichens: A Feasibility Study, Monograph No. 1976-2, Syncrude Canada Ltd. Peterson, W. L., Douglas, G. W., Air Quality Monitoring with a Lichen Network: Baseline data, Monograph No. 1977-5, Syncrude Canada Ltd.
Ashok Kumar, an atmospheric physicist at Syncrude Canada Ltd. has, since February 1977, planned and conducted studies related to the dispersion of emissions. He received his B S c . Eng. (Hons.) f r o m Aligarh University in India and his M.A.Sc. (Mech. Eng.) f r o m the University of Ottawa. He earned a doctorate f r o m the University of Waterloo in 1977. He is a registered professional engineer in the Province of Alberta. Coordinated by J J
