Draft Deloro cleanup plan sets out steps for final on-site containment of wastesIn preparation for the final phase of the Deloro mine site cleanup project, the Ontario Ministry of Environment (MOE) has released its draft cleanup plan for a 60-day public consultation period, running to January 12, 2005. The plan, prepared for the MOE by CH2M Hill Canada, proposes the secure containment of contaminated wastes on the 202-hectare Deloro site. This would include the placement of an engineered cap of clay, sand, topsoil and vegetation over 60, 000 m2 of contaminated material to prevent contact with water and the environment.
The MOE assumed responsibility for the mining, refining, and manufacturing site in 1979 when the site owner failed to comply with Ministry orders to stop pollution. Since then, the MOE has invested more than $20.5 million in the cleanup project. Work to date has reduced the amount of arsenic (the main contaminant of concern) coming from the site by 80%. The draft cleanup plan addresses the remaining 20%.
"The ministry will finish the cleanup of this site," said Environment Minister Leona Dombrowsky. "We will do it in a way that ensures the site is safe for hundreds of years and improves the quality of life for area residents." The MOE estimates it will spend another $30 to 40 million in capital investments to finish the job.
For more than 100 years, mining, refining and manufacturing activities were carried out at facilities on the property, situated on the banks of the Moira River at the eastern edge of the village of Deloro. The environmental legacy of the site's history of industry includes contamination of soil, sediment, groundwater and surface water, primarily with arsenic but also with cobalt, copper, nickel and low-level radioactive waste.
Among the cleanup activities completed to date have been:
*construction and continuing operation of an arsenic treatment plant to treat contaminated groundwater (the plant removes about 99.5% of the arsenic from the contaminated groundwater it treats);
*establishment of an extensive ground and surface water monitoring network;
*construction of an on-site laboratory to analyze ground and surface water samples; and
*capping eight hectares of tailings with a half-metre of crushed limestone to minimize contact with air and water.
The Ministry has also conducted two off-site assessments study to assess potential off-site impacts to people and the environment. These included the Deloro Village environmental health risk study; and the Moira River study.
The purpose of the draft cleanup plan is to complete the cleanup of the abandoned mining and industrial complex at Deloro by isolating and containing wastes and engineering the site to ensure its long-term safety from an environmental and human health perspective. Once completed, the ministry says its plan will reduce the amount of arsenic coming from the site by 98%.
The activities outlined in the plan will serve to isolate and contain the remaining complex blend of contamination (a total of about 650,000 cubic metres (m3)) at the site itself. None of the existing waste materials will be taken off-site. Management of wastes will be conducted following the Site Specific Risk Assessment Approach (SSRA), under MOE's 1997 Guideline for Use at Contaminated Sites in Ontario.
The cleanup will focus on four main areas where different industrial, mining and manufacturing activities took place. Because each area has its own specific environmental issues, remedial strategies have been customized to suit each area.
The general terms of the draft cleanup plan include:
*excavation and consolidation of the most severely contaminated material under engineered covers made of clay, sand, topsoil, loam and clay liner, topped with vegetation;
*use of engineered clay caps to cover less contaminated material; and
*management of surface water and groundwater to eliminate contact with contained wastes.
The draft plan has been reviewed by MOE and by the project's public, and technical liaison committees, which include federal, provincial and municipal government representatives, area residents and local environmental groups. After the public consultation period ends, staff from the MOE and CH2M Hill will record and review all comments and make changes to the draft cleanup plan as necessary. Once finalized, the ministry must submit the cleanup plan to various federal and provincial government agencies to seek appropriate licenses, permits and approvals.
Full engineering designs and specifications will be developed to support approvals and will be finalized prior to tendering and construction. Detailed design work will begin in early 2005 and will be completed in the summer of 2006. Construction is expected to begin in 2007 once permits and approvals have been obtained. A complete implementation plan will be developed as the construction period approaches.
More information is available on the Deloro page of the MOE Web site, www.ene.gov.on.ca, or from Heather Hawthorne of the MOE, 613/548-6927.