Pierre River Mine Project

AIR AENV SIRS 6 – 14
Section 11.1
Request 8b Shell states Overall, the results show that the maximum NO2 predictions near the
major NOx emissions sources using ARM are lower than the OLM results. Based
on the application of the OLM formulation as noted in Table 1, this statement
should be corrected to allow a complete assessment of this component of the EIA.
Response 8b The ambient ratio method (ARM) formula is provided in EIA Volume 3,
Appendix 3-8, Section 2.3.5 and was applied to each model hour. The formula is
provided below for reference.
Syncrude North
where:
Mine
[ NO
[NO2] = nitrogen dioxide concentration [ppm]
2 −0.
608
= 0.
100×
[ NO ]
[ NO ]
X
X
[NOx] = oxides of nitrogen concentration [ppm]
April 2010 Shell Canada Limited 11-5
CR029
]
The ozone limiting factor (OLM) formula from the Air Quality Model Guideline
(AENV 2003) is as follows:
If [O3] > 0.9x[NOx] then [NO2] = [NOx]
otherwise [NO2] = [O3] + 0.1x[NOx]
where:
[O3] = ozone concentration [ppm]
[NO2] = nitrogen dioxide concentration [ppm]
[NOx] = oxides of nitrogen concentration [ppm]
Hourly ground-level ozone observations from the Wood Buffalo Environmental
Association (WBEA) Fort McKay air quality monitoring station for 2002 were
used in the OLM formula. The year 2002 was chosen to coincide with the
meteorological data and modelling year. The OLM formula was applied by
matching the hourly NOx predictions with the hourly monitored ozone
concentrations.
Since the background ozone concentrations and the predicted NOx concentrations
vary by hour, it is not feasible to show calculations for every hour; however,
example values are shown in Table AENV 8-1. These sample calculations show
that either the OLM or the ARM method can produce higher NO2 predictions
based on the hourly NOx and ozone concentrations. However, based on the
results in the May 2009 Pierre River Mine, Supplemental Information, Volume 2,
SIR 244, Tables 244-1 to 244-3, the ARM-based 1-hour and 24-hour NO2
predictions are consistently lower than those derived from the OLM when
considering locations near the major NOx sources (e.g., active mine areas).