A unique remediation/risk management strategy was used for the Brownfields redevelopment of a former smelter and battery recycling facility, Northwest Smelting and Refining, located in Winnipeg, Manitoba.
Historically, the northern portion of the site was used as a waste disposal area for battery casings and metal debris. Metal-impacted soil was found to be at hazardous levels across the site. A remedial options analysis was completed. The recommended remedial option included designing an engineered granular cap on the northern portion of the site to cover hazardous material in that area, where metal impacts and debris already existed, and excavating and placing metal-impacted soils from the rest of the site below it.
The work program included the preparation of technical specifications for site remediation; contract development and preparation; remediation plan (RP) development; development and implementation; preparation of closure documentation including construction supervision and soil screening using an X-ray Fluorescence Analyzer; closure sampling; and contract administration services. Dillon also applied for, and obtained, a City of Winnipeg permit for land development and site drainage works prior to site remediation. A human health and ecological risk assessment was prepared to establish site-speciﬁc remediation criteria and to demonstrate that the proposed remedial strategy addressed the exposure pathways/risk for the site.
Challenges included the discovery of a former operation consisting of four kilns with associated additional metal-impacted soil below the former building foundations. Previous studies of the property suggested that it was not likely that impacts would be encountered below the former building foundations; however, this was not the case. The soils below the foundation were found to have elevated levels of metals requiring removal. To accommodate the increase in impacted material, the engineered cap design was enlarged and raised.
Approximately 8,500 m3 of impacted soil was removed from the southern portion of site through excavation and relocated beneath the engineered cap on the northern portion of the site. Approximately 500 m3 of hazardous granular material was removed from the site.
In addition to having substantially more impacted soil than anticipated that required additional effort and time by both the contractor and Dillon, the original project scope was also increased as the owner requested that Dillon also facilitate receiving a city permit for the project. Although both items increased the fees and overall project cost, the objectives of the RP were achieved. A closure letter was received from Manitoba Sustainable Development which cleared the contaminated site designation.
The southern section of the site is now suitable to be redeveloped as an industrial/commercial area. The northern portion of the site is designed for use as a storage area (e.g., parking lot, material storage).