Young's Creek enters the Deloro Mine Site at its northeast corner and flows south along the eastern side of the Tailings Area, connecting with the Moira River south of Highway # 7. Over the last century, run off from the Tailings Area has resulted in heavy sediment contamination in the creek. Water flow is very low in this area, which is typically wetland-like in nature.
Young's Creek currently contributes about three percent of the arsenic loading to the Moira River watershed. Cleanup of this area is planned due to the high levels of metals in sediments, the presence of low-level radioactive material in the on-site onsite portion, and due to the potential for occasional high river flows to re-suspend contamination, especially during a 100-year flood event. Biological diversity and abundance in this area are affected as a direct result of contaminated sediments.
The Young's Creek Area is part of a provincially significant wetland, known as the Deloro Wetland Complex. In light of that fact, a wetland restoration plan will be implemented following removal of contaminated sediments.
Area: Onsite – about 47 hectares (ha) Offsite (south of Highway # 7) – about 19 ha
Contaminants of Concern: Onsite area - Arsenic, cobalt, copper, nickel, and low-level radioactive material; Offsite area - Arsenic, cobalt, copper, and nickel. There is no radioactivity in the offsite area.
Volume of Wastes: Onsite - 100,000 m3 of shallow contaminated sediments and an equal amount of contaminated deeper soils Offsite - About 68,000 m3 of contaminated shallow sediment
Full depth excavation of onsite sediment, shallow depth excavation of offsite sediment, and disposal in a new onsite engineered containment cell followed by creek rehabilitation.
The Young's Creek Area includes an onsite and an offsite portion. The onsite portion is much more contaminated, and to a greater depth than the offsite portion. The onsite portion also contains some low-level radioactive material.
Excavation and containment
Contaminated sediments and soils will be excavated, dewatered, and placed in a secure engineered containment cell that will be built onsite to the south of the Tailings Area.
The containment cell will have an engineered vegetated cap and liner system to isolate contamination from the environment. The cell will be substantial in size, covering an area of about 5 hectares (ha) to a height of approximately 17 metres.
Areas of the wetland removed by excavation will be reconstructed. This is especially important for rebuilding the ecosystem since this area is part of a provincially significant wetland.