RELEASES OFF-SITE TO DISPOSAL: 732,825,092 kg

North American facilities reported off-site releases to disposal of 357 pollutants in 2009, with releases of hydrogen sulfide accounting for about 61% of the total. Together with three metals (zinc, manganese, and barium and their compounds), the top four pollutants accounted for about 80% of all reported releases off-site for disposal.

Please note that the terminology for off-site releases to disposal used in Taking Stock has been adopted for purposes of comparability among the three PRTRs, and can vary from that used by the national programs. Readers are reminded that each country has specific reporting requirements for sectors, facilities and pollutants that affect the North American picture of industrial pollution. Using and Understanding Taking Stock.

The Canadian sector that provides support for mining – much of it oil and gas extraction – reported almost 430 million kg of hydrogen sulfide released off-site to disposal in 2009, with one gas processing facility in the province of British Columbia accounting for almost 100% of this amount. Canadian oil and gas extraction facilities also reported almost 53 million kg of off-site releases to disposal of substances including total reduced sulfur and hydrogen sulfide*, along with others such as methanol, benzene, and toluene. The oil and gas extraction sector is not required to report to the US TRI; and in Mexico a total of 289 kg was reported by four facilities in this sector.

The primary metal manufacturing sector ranked second for off-site releases to disposal in 2009, reporting more than 86 million kg. Within this sector, iron and steel mills and ferroalloy manufacturers, mainly in the United States and Canada, accounted for over half of the total, reporting large proportions of metals including zinc, manganese, lead and chromium compounds. US foundries, along with a small number located in Mexico and Canada, also contributed almost 9 million kg in total off-site releases to disposal. These facilities reported large proportions of metal compounds and a variety of other substances.

Utilities ranked fourth for releases off-site to disposal. Of the total reported, coal- and oilfired power plants, most of them in the United States, reported more than 34 million kg 20 (or 73%); the other 12.5 million kg were reported by public wastewater treatment facilities, almost all in Canada. Among the top pollutants released off-site to disposal by power plants, barium compounds accounted for more than 56%, followed by other metals and their compounds such as manganese, vanadium, zinc, copper, and chromium. Barium compounds are not subject to PRTR reporting in Canada and Mexico, with a number of other top substances reported by this sector also not subject to RETC reporting.

Canadian wastewater treatment plants reported large proportions for off-site disposal of phosphorous and ammonia, along with a number of metals and their compounds. Public wastewater treatment facilities (called “publicly owned treatment works – POTWs – in the United States) are not subject to TRI reporting, and no such facility in Mexico reported off-site releases to disposal.

The "Off-site releases to disposal" category used in Taking Stock describes pollutants sent off site to be disposed of in a variety of ways including on land, in landfills or via underground injection. For purposes of PRTR reporting comparability, and because metals cannot be destroyed, metal compounds reported as transferred off-site for treatment, sewage or energy recovery are also included in the off-site releases to disposal category.

*Note about Total Reduced Sulfur (TRS) reported to NPRI: TRS was added to the NPRI substance list for the 2007 reporting year due to concerns about its impact on air quality. TRS consists of six individual substances: 3 of these (hydrogen sulfide, carbon disulphide, and carbonyl sulfide) are also listed individually under the NPRI. Therefore, there is a potential for “double counting” if data on TRS and the individual substances are combined. For additional guidance, refer to the NPRI website at www.ec.gc.ca/inrp-npri.