Dow Canada Dioxin Air Emissions
Dow Canada Disposal to Landfills
Dow Canada Disposal to Wells and Caverns
The Canadian Environmental Protection Act (CEPA) requires chemical manufacturers and many other industries to report emissions to air and water, disposal to land and underground caverns or wells, and off-site transfers for more than 300 chemical substances, if the releases exceed reporting thresholds set by Environment Canada. The data are compiled by Environment Canada on an annual basis in the National Pollutant Release Inventory (NPRI). The NPRI was created in 1992 to provide information to Canadians on the release of pollutants by facilities in their community.
NPRI data are available on the Environment Canada Web site.
Dioxin and the NPRI
Dioxin was included in the NPRI for the first time in 2000. Under NPRI rules, manufacturing facilities engaged in a specified list of activities must report dioxin and furan releases to Environment Canada on June 1 each year. As such, Dow Chemical Canada Inc. reports dioxin and furan release and disposal data for its manufacturing site in Fort Saskatchewan, Alberta. Unlike the U.S. TRI these data are reported in grams per year of toxic equivalents (I-TEQ grams per year).
The Fort Saskatchewan facility has no process water going to the nearby North Saskatchewan River and therefore does not have any dioxin and furan emissions to water. However, the site does make use of government-regulated disposal to underground wells, caverns and landfills, and has reported these amounts annually since 2000. Air emissions have also been reported to NPRI since 2000 and in the Dow Canada Public Report since 1995.
Dow Canada Dioxin Air Emissions
In 1995, Dow Canada set a goal to reduce dioxin and furan emissions by 90 percent by 2000. Air emissions were identified as a priority since these emissions presented the greatest potential for human exposure. Testing in 1994 revealed air emissions from the Fort Saskatchewan site were 1.7 grams TEQ per year. By 1998, the technology to reduce dioxin and furan air emissions was identified and installed. Today, these emissions have been reduced by more than 95%, and since 2000 have remained well below 0.1 grams TEQ annually.
Dow Canada Disposal to Landfills
After reducing dioxin and furan emissions to air by more than 95 percent, Dow Canada is now working to achieve a reduction in releases of dioxins and furans in wastes using pollution prevention as the preferred approach. These on-site waste and recycle streams were considered a lower priority due to the limited potential for exposure. Secure on-site landfill is one method used to manage dioxin and furan contaminated waste that ensures minimal risk to the environment and human health. Dioxin and furan disposal in the on-site landfill at the Fort Saskatchewan site is reported each year to NPRI.
Dow Canada Disposal to Wells and Caverns
Like other Dow sites, Fort Saskatchewan extracts salt as brine from underground caverns created in deep geological formations. In order to recover salt and reduce water discharges, spent brines are recycled back to the brine caverns to extract more salt. These recycled brines contain low levels of dioxins and furans attached to very small solid particles which tend to drop out to the bottom as they pass through the caverns.
Once spent, these caverns are used as disposal caverns for unwanted solid minerals such as calcium and magnesium carbonates that are mined with the salt. This material builds up in ponds over time and periodically is injected back into these solids disposal caverns. This material is primarily inorganic minerals that came from the caverns, but does contain dioxins and furans from brine recycle operations. In 2001 a large quantity of this material was disposed of as part of a maintenance operation to clean out a process pond. In 2005, this activity was repeated in two waste water ponds and a much larger volume of materials was disposed of.
In addition to the brine caverns, the site also uses a regulated liquid disposal well for injecting waste water into a deep geological formation. This government-approved method of disposal is used by many Alberta companies and allows the site to meet the goal of having no emissions of process water to any open waterway. Low levels of dioxins are also contained in this process water.
All of these sources are included in the underground disposal numbers reported to NPRI. Since this material resides in deep underground formations with extremely low possibility to migrate, these methods of disposal are considered protective of the environment and human health.
