The Emission Reduction Program (ERP)
The Emission Reduction Program (ERP) is operated to control downwind community ground level sulphur dioxide (SO2) gas concentrations, resulting from Vale process emissions to atmosphere.
Weather conditions determine the dispersion of SO2 in the atmosphere. Weather data from a multitude of sources is analyzed daily in the Vale's meteorological office to construct a forecast that is specific to the Sudbury Region. To assess the atmospheric stability, upper air balloon soundings are conducted. Wind speed and direction as well as temperatures are monitored throughout the day at different altitudes using Vale's SODAR/RASS unit in addition to data from several local meteorological towers.
The ERP program is both predictive and reactive in nature. From the weather forecasts, complex numerical models are used to predict downwind ground level concentrations of sulphur dioxide at different emission rates. This data is used to set a stack emission rate limit to meet the MOE SO2 concentration limits in the community; the operation of the smelting vessels is then controlled to remain under the modelled emission limits. The most unfavourable dispersion conditions generally occur under sunny skies with light winds, which require the most severe cutbacks to production. The characteristic looping plume is evident at this time and a sulphur taste may be noticeable in the air. Smelter production is frequently restricted under these conditions, especially during the summer months.
The ERP Operators at Vale also monitor measurements from a network of thirteen continuous SO2 monitoring stations spread throughout the community. This coverage is complemented by a mobile monitoring vehicle, which locates and monitors ground level concentrations at points between the fixed stations in the community. This vehicle also responds to community complaints. As well, the ERP operators control a number of video cameras to view the superstack plume and rooftop level emissions from the Vale facilities.
Calls to the Vale Community Concerns line (705-682-8283) are received and responded to by the ERP Operator. This additional community input is used to direct the mobile monitor to areas of concern in the community.
The ERP program, based on the science of meteorology and atmospheric dispersion, has continually improved over the past thirty years with the advancement of new technology and refined modelling methods. Since 1986, Vale (previously known as Inco) has spent close to $1 billion to reduce SO2 emissions at our Sudbury operations. The latest project, which captured and fixed Fluid Bed Roaster offgases, came on line in late 2006, further lowering emissions to allow Vale to meet the new 2007 annual regulatory limit of 175 kilotonnes SO2. Since 1970, Vale has reduced overall SO2 emissions by 90 percent and our goal is to further lower annual SO2 emissions to below 66 kilotonnes from Sudbury operations by 2015.
