AIR QUALITY 



Saskatchewan 



Ambient sulphur dioxide monitoring began at Coronach in July 1979. 

 To date, a few detectable concentrations have been recorded at this 

 site. There were two high concentrations during 1984, both occurring 

 on June 22, at 1100 and 1200 hours. The levels were 20.3 and 17.0 

 parts per hundred million (pphm) respectively. Saskatchewan Environ- 

 ment's 1 hour air quality standard is 17.0 pphm (Figure 6). Weather 

 information for this day indicates that winds for the entire 24 hour 

 period were blowing mainly from the northwest quadrant. Since the 

 plant is located south of the monitoring station it is unlikely that 

 the plant was the source of the high readings. The source of the two 

 readings has not been determined. The next highest reading of 6.0 

 pphm occurred on May 2 at 1830 hours. Weather information for this 

 day indicates winds blowing from the southeast quadrant for the 

 entire 24 hour period, which would indicate the power plant as the 

 main source. 



Suspended particulate concentrations at Coronach exceeded Saskatche- 

 wan Environment's 24-hour average standard of 120 micrograms per 

 cubic metre (yg/m^) on six occasions, as compared to four in 1983. 

 In four of the cases, April 24, 30, and May 12, 24, weather informa- 

 tion indicated winds blowing predominantly from the northwest quadrant, 

 suggesting that the power plant was not the main source. Wind blown 

 dust from fields north of the monitoring site was the most probable 

 source. The other two instances occurred on June 29 and December 20. 

 Weather data for these 2 days indicated wind directions mainly from 

 the south, suggesting the power plant as a possible source of dust 

 emissions. Power plant operating summaries for December 20 note a 

 power trip of Unit No. 2 precipitator which caused violations of the 

 opacity standard. However, the highest concentration in Montana was 



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