MEMS has conducted many air quality assessments for steam assisted gravity draining (SAGD) projects in Alberta’s oil sands. The 60.000 barrel per day OSUM Sepiko Kesik project is one example. MEMS developed a nested CALMET model to provide higher resolution meteorological variables in immediate vicinity of the project, and broader resolution across the regional assessment area, interpolating from upper-level MM5 data and eight surface stations. Concentrations and deposition of SO2, NOx, CO, VOC, PAH and PM2.5, nitrogen and PAI were modelled using the CALPUFF dispersion model. MEMS’ client benefited from our strength in estimating project emissions from combustion sources, providing an important project design backstop.