Editing Inco Superstack (section)

==History==
The Superstack was built by Inco Limited (and later purchased by [[Vale Limited|Vale]]) at an estimated cost of 25 million dollars. Construction on the structure was underway during the [[Sudbury tornado]] of August 20, 1970; the structure swayed heavily in the wind but remained standing and suffered only minor damage.<ref name=torstar1>"90 mile winds smash Sudbury area". ''[[Toronto Star]]'', August 20, 1970. p. 1.</ref> Six workers were on top of the construction platform when the storm hit, all of whom survived.<ref name="torstar1" /> The same day was the final day of construction on the stack, with the construction fully completed by the evening of August 21, 1970.<ref>"Smokestack resisted gale to become world's tallest". ''[[Toronto Star]]'', August 22, 1970. p. D3.</ref>

The stack entered into full operation in 1972.<ref name=facts>{{cite web|title=Vale's Iconic Superstack: History and Key Facts|url=http://www.vale.com/canada/EN/aboutvale/communities/sudbury/Pages/Superstack%20History%20Fact%20Sheet_FINAL.pdf|access-date=September 20, 2020|archive-date=July 18, 2021|archive-url=https://web.archive.org/web/20210718142116/http://www.vale.com/canada/EN/aboutvale/communities/sudbury/Pages/Superstack%20History%20Fact%20Sheet_FINAL.pdf|url-status=dead}}</ref> From the date of its completion until the [[Ekibastuz GRES-2]] chimney was constructed in 1987 in [[Kazakhstan]],<ref>{{cite web |title=GRES-2 Chimney (Ekibastuz, 1987) |url=https://structurae.net/en/structures/gres-2-chimney |website=structurae.net |publisher=Structurae |access-date=28 December 2020 |language=en}}</ref> it was the world's tallest smokestack. Between 1972 and 1975, it was the tallest freestanding structure in [[Canada]].

[[File:Blackened rocks in Sudbury, Ontario.JPG|thumb|left|Blackened rocks in 2012]]
Prior to the construction of the Superstack, the waste gases had contributed to severe local ecological damage. The Copper Cliff smelter was already home to some of the world's tallest stacks, including two {{convert|500|ft|abbr=on}} chimneys constructed in 1928-29 and 1936.<ref>[http://www.sudburymuseums.ca/triangle/data/INCOTriangle-19621201.pdf INCO Triangle, December 1962, pp. 6–7, 14.]</ref> However, they proved to be insufficient and were compounded by open coke beds in the early-to-mid-20th century and by logging for fuel, which inevitably caused a near-total loss of native vegetation. Of particular interest to geologists are the now-exposed rocky outcrops, which have been permanently stained charcoal black by the pollution wafting over the decades from the roasting yards and then by the [[acid rain]] in a layer which penetrates up to three inches into the once pink-grey [[granite]].

The Superstack was built to disperse [[sulfur|sulphur]] gases and other byproducts of the smelting process away from the city of Sudbury. It did so by placing the gases high in the air, where they normally blew right past the city on the [[prevailing winds]]. As a result, the gases could be detected in the atmosphere around Greater Sudbury in a {{convert|240|km|mi}} radius of the Inco plant. During the 1970s and 80s, the sulphur dioxide plume formed a permanent, opaque, cloud-like formation running across the entire horizon as seen from a distance. Periodic [[inversion (meteorology)|inversions]] would cause the plume to fall into the city.{{cn|date=October 2020}}

Construction of the Superstack was followed by an environmental reclamation project, which included rehabilitation of existing landscapes and selected water bodies such as [[Lake Ramsey]]. An ambitious regreening plan saw over three million new trees planted within the Greater Sudbury area. In 1992, Inco and the city were given an award by the United Nations in honour of their environmental rehabilitation programmes.{{citation needed|date=March 2023}}

On November 3, 2014, Vale announced that it might decide to stop using the stack after a $1 billion project to reduce emissions by 85% that negates the need for the stack. If no other use for it is found, Vale might decommission the Superstack, demolish it, and replace it with a much smaller chimney.<ref>{{cite news|author1=Jonathan Migneault|title=Vale examines Superstack's future|url=http://www.northernlife.ca/news/localNews/2014/11/03-superstack-sudbury.aspx|newspaper=[[Northern Life (newspaper)|Northern Life]]|access-date=November 4, 2014|date=November 3, 2014}}</ref> In 2017, Vale announced plans to decommission the Superstack upon the construction of two smaller, more energy efficient stacks.<ref>{{Cite web |url=http://www.cbc.ca/news/canada/sudbury/vale-announces-superstack-done-1.3949500 |title=Superstack to be decommissioned, but no immediate plans for demolition |date=January 24, 2017 |website=cbc.ca |access-date=January 25, 2017}}</ref><ref>{{Cite press release |title=Continuous Improvement: The Superstack to be taken out of service |url=http://www.vale.com/canada/EN/aboutvale/communities/sudbury/Pages/superstack.aspx}}</ref> On July 28, 2020, Vale updated that news and stated that the Superstack at its Copper Cliff Complex had been taken out of service. It would remain on "hot standby" for about two months while the replacement flue connections were tested, but it would then be demolished over the years.<ref>{{Cite news |date=July 30, 2020 |title=Sudbury's iconic Superstack no longer operational |url=https://www.timminstoday.com/local-news/sudburys-iconic-superstack-no-longer-operational-2599596 |access-date=July 31, 2020 |work=TimminsToday}}</ref>