The first, and less expensive choice would have been to transport the nearly 70,000 tonnes of soil to a landfill. That would mean 2,500 truckloads would be passing through Pincher Creek to a specialized landfill area in Cowley. 'We didn't feel it was the right decision,' said Sollid. 'We felt that was an unacceptable safety risk in moving that much material.' Chevron chose instead to treat the soil on site through a process that removes the hydrocarbons and makes the soil reusable.
Thermal desorption cleans the soil in a type of oven. Unlike an incinerator, the equipment does not destroy the chemicals. Instead they reach a high enough temperature to evaporate. The soil can then be reused. 'The only emissions that come out of this equipment are carbon dioxide, nitrogen and water,' said Sollid.
Chevron estimates the clean up will take five months and will be a 24/7 operation. Sollid said after the hydrocarbons have been removed from the soil there will be a lengthy reclamation project. The soil will be landscaped and the site will be returned to its original condition. Chevron will have to monitor it for three years. The site was a natural gas exploration well drilled in 1985. Attempts were made over the years at reclamation. In 1998 it was determined that there was hydrocarbon-impacted soil from diesel fuel. The diesel fuel had mixed with the mud. None of the attempts at clean up completely removed the hydrocarbons from the soil.
Sollid said that in 2004 a final figure of 40,875 cubic metres of hydrocarbon-impacted soil was determined. Chevron conducted a bio-remediation effort until 2007. 'It was not having the desired results,' said Sollid. He said the removal of chemicals from the soil was not happening as quickly as they wanted to see. Chevron decided to try the thermal desorption method. Sollid said Chevron's confidence in this process is 99.9 per cent. Nelson Environmental Remediation Ltd., based out of Spruce Grove, AB, will be heading up the process. Chevron said they have notified all neighbours within a 1.5-kilometre zone and the town and municipal councils. Sollid said the process meets noise guidelines and is approved by the Alberta Energy Resources Conservation Board.